JP2003306681A - Method for producing highly reactive coke for blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a highly reactive coke for blast furnaces by which sufficient coke strength not causing lowering of air permeability by powdering can be ensured and a fuel ratio of the blast furnaces is reduced and blast furnace operation having high productivity can be carried out. <P>SOLUTION: The method for producing the highly reactive coke for blast furnaces comprises mixing ≥2 wt.% coal containing ≥1 wt.% alkaline earth metal and/or transition metal into a mixed coal and drying the mixture by distillation in a coke furnace. In the coal containing ≥1 wt.% alkaline earth metal and/or transition metal, average particle diameter of the alkaline earth metal and the transition metal in the coal are each ≥10 μm. <P>COPYRIGHT: (C)2004,JPO

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 highly reactive coke for a blast furnace for reducing the fuel ratio of the blast furnace, improving the productivity and enabling the operation of the blast furnace.

[0002]

2. Description of the Related Art In a normal blast furnace, iron ore (sintered ore) and normal blast furnace coke are charged in layers from the furnace top.
After reducing this iron ore in the furnace, pig iron in a molten state is manufactured.

By the way, in the blast furnace, there is a region called a heat preservation zone where the temperature is approximately 1000 ° C. and is substantially constant, and this temperature usually corresponds to the gasification start temperature of the blast furnace coke.
That is, in order for the gasification reaction of coke represented by C + CO ₂ = 2CO to occur in the blast furnace, a temperature of about 1000 ° C. or higher is required. About 70% of the reduction of iron ore occurs in a higher temperature region than the heat preservation zone, but as the temperature rises, the reduction equilibrium gas composition becomes higher in CO concentration side, and it is higher in order to promote the reduction reaction. A gas having a CO concentration composition is required. Further, at about 1100 ° C. or higher, melt generation from iron ore is observed, and as a result, permeation of reducing gas into the iron ore (sintered ore) is suppressed. Therefore, when the temperature of the heat preservation zone is high, the indirect reduction of iron ore by CO gas cannot be effectively utilized, and the reduction efficiency does not improve beyond a certain value.

On the other hand, since highly reactive coke for a blast furnace has high reactivity, when CO ₂ in the blast furnace comes into contact with the surface of the coke, a reaction of C + CO ₂ = 2CO is actively carried out from a lower temperature. Further, as a result, the CO gas generated in the furnace effectively reacts with the iron ore to promote the reduction reaction.

The reaction of C + CO ₂ = 2CO is an endothermic reaction and has the effect of lowering the temperature of the heat preservation zone in the blast furnace. That is, when using normal blast furnace coke, 1000
While the heat preservation zone of about ℃ is generated and its temperature hardly changes, the heat preservation zone temperature can be reduced to 900 to 950 ℃ by using the highly reactive coke for blast furnace. As a result, the reduction equilibrium gas composition is on the low CO concentration side, and there is a margin at the reduction equilibrium reaching point, so that the reduction proceeds more and the reduction efficiency improves. Therefore, if the high-reactivity coke for the blast furnace can be used by replacing part or all of the normal blast furnace coke, the reduction efficiency of the blast furnace can be improved and the coke ratio can be reduced.

[0006] The conventional method for producing highly reactive coke for blast furnace is not suitable for producing blast furnace coke, and is blended with coking coal with non-slightly caking coal or steam coal which has high reactivity when coke is formed. (Patent Document 1 or the like), or an iron content that functions as a catalyst for promoting the gasification reaction of coke was mixed with the raw coal.

However, the method for producing highly reactive coke for a blast furnace by blending non-slightly caking coal or steam coal as disclosed in Patent Document 1 is as follows:
If the blending ratio of non-caking coal or steam coal is small, there is a problem that the effect of improving reactivity is small and the reduction efficiency of the blast furnace cannot be improved. In addition, if the mixing ratio of non-cohesive coal or steam coal is large, the coke strength will decrease significantly, and when it is charged from the top of the blast furnace, it will be pulverized and the air permeability of the blast furnace will deteriorate, so in the actual blast furnace There was a problem that it became extremely difficult to use. Further, a method for producing a highly reactive coke for blast furnace by mixing the iron content with coal and carbonizing in a coke oven, at a certain temperature or higher, the silica stone bricks and the iron content forming the oven wall of the coke oven react with each other, This is undesirable because it damages the furnace wall.

Further, as a highly reactive coke for a blast furnace, while maintaining the coke strength, the reaction of producing carbon monoxide from carbon and carbon dioxide is activated for the purpose of extending the blast furnace life, reducing the fuel ratio and improving productivity. As a catalyst, an alkaline earth metal, an alkaline earth metal compound, a mixture of an alkaline earth metal and an alkaline earth metal compound, a mixture of an alkaline earth metal compound, a transition metal, a transition metal compound, a mixture of a transition metal and a transition metal compound, Patent Document 1 discloses a method for producing highly reactive coke for a blast furnace, in which at least one kind of a mixture of transition metal compounds is added to coal and carbonized in a coke oven.
Has been proposed by.

[0009] In this method, the catalyst of the above-mentioned metal, compound or mixture is directly blended with the coal blend, and the coal blend and the catalyst are dry-distilled in a state of being in physical contact with each other in a coke oven.
This is a method of producing coke containing a catalyst, and although it is possible to improve the coke strength to some extent as well as the reactivity of the coke, there is a limit to the sufficient improvement of the coke strength for the blast furnace.

This is because when the catalyst is directly blended with the blended coal, the coal particles softened and melted during carbonization do not have good adhesion to the catalyst particles, so that the surroundings of the catalyst particles in the coke produced. This is because when a crack is generated and the shock is received, the coke is easily broken from this crack as a base point.

[0011]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2001-187887

[Patent Document 2] Japanese Patent Laid-Open No. 2001-348576

[0012]

In view of the above-mentioned conventional state of the art, therefore, in the present invention, it is possible to secure sufficient coke strength as a blast furnace coke that does not cause a decrease in air permeability due to pulverization during blast furnace charging, Moreover, it is an object of the present invention to provide a method for producing highly reactive coke for a blast furnace, which has no problems in terms of blast furnace life and stable operation of the blast furnace.

[0013]

The gist of the present invention is as follows. (1) A highly reactive coke for a blast furnace, characterized in that coal containing 2% by mass or more of an alkaline earth metal and / or a transition metal is compounded in a compounded coal in an amount of 2% by mass or more and carbonized in a coke oven. Production method. (2) The method for producing a highly reactive coke for a blast furnace according to (1) above, wherein the average particle size of the alkaline earth metal and the transition metal is 10 μm or less. (3) The method for producing a highly reactive coke for a blast furnace according to (1) or (2) above, wherein the alkaline earth metal is Ca and the transition metal is Fe. (4) The blast furnace height according to any one of (1) to (3) above, wherein the total expansion coefficient of the coal is 25% or less and / or the fluidity is 1.3 or less. Method for producing reactive coke. (5) In the above coal, the proportion of coal particles having a diameter of 3 mm or less is 60% by mass or more, and the proportion of coal particles having a diameter of 0.3 mm or less is 10% by mass or more and 50% by mass or less. ) To (4), the method for producing a highly reactive coke for a blast furnace according to any one of (1) to (4). (6) The reflectance (Ro) is further 1.
2 or more and the maximum fluidity (MF) of the Giesera fluidity test
Is blended with 10% or more of caking coal that satisfies the following formula (1), and the method for producing a highly reactive coke for a blast furnace according to any one of the above (1) to (5). MF> = − 2.8Ro + 6.4 (1) (7) In the blended coal, the reflectance (Ro) was 1.
2 or more and the maximum fluidity (MF) of the Giesera fluidity test
Is blended with 10% or more of caking coal having a value of 3.0 or more.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have investigated a method for improving the reactivity of coke, and by mixing coal containing a large amount of alkaline earth metal and / or transition metal into blended coal and performing carbonization. It was found that the reactivity of coke can be significantly improved without significantly lowering the coke strength.

The reason why the reactivity of the coke is improved is that the alkaline earth metal and / or the transition metal act as a catalyst for improving the coke reactivity. The reason for acting as a catalyst is that the alkaline earth metal and / or the transition metal act as a medium for exchanging electrons between coke and CO ₂ .

[0016] Such an action has a greater effect on the coal containing both of the alkaline earth metal and the transition metal when it is blended with the coal blend and dry-distilled, as compared with the coal containing either of the alkaline earth metal and the transition metal. It is possible to further activate the reactivity of coke by the synergistic effect of the alkaline earth metal and the transition metal. This is because the transfer of electrons is also performed between the alkaline earth metal that is the catalyst and the transition metal, and the transfer of electrons between coke and CO ₂ is further activated.

Further, in the conventional method in which iron is directly blended with coal blend and carbonized in a coke oven, at a certain temperature or higher, the silica stone constituting the furnace wall of the coke oven and the iron are contacted and reacted, It was said to be undesirable because it would damage the furnace wall.

On the other hand, in the present invention, since the transition elements such as iron are dispersed in the coal particles at the elemental level, it is possible to avoid contact and reaction between the silica brick and the transition elements such as iron, and Effects such as damage to wall bricks can be ignored.

In the present invention, the alkaline earth metal is Be, Mg, Ca, Sr, which belongs to Group 2 of the periodic table.
Such as Ba. Further, the transition metal is an atom having an incompletely filled d shell or an element that produces such a cation, and Sc of Groups 3 to 11 of the periodic table,
Y, Ti, Zr, V, Nb, Cr, Mo, Mn, Tc,
It means Fe, Ru, Co, Rh, Ni, Pd, Cu, Ag and the like.

In the present invention, among alkaline earth metals, in particular, coal containing Ca and transition metals,
In particular, coal containing Fe is preferable because it is easily available.

Here, the coke reactivity means 900 ° C. to 1 ° C.
CO in a high temperature range of about 300 ° C ₂In reactivity with
Generally, JIS K2151 coke test method
It is measured by the reactivity test method described in the method.

Here, the target value of the coke reactivity required for lowering the temperature of the heat preservation zone is 25 ml / min or more in the above JIS test method.

Further, in the method of directly blending the catalyst with the coal blend, which has been conventionally proposed in Patent Document 2 and the like, coal particles softened and melted during carbonization and catalyst particles such as alkaline earth metal or transition metal Since the adhesiveness is not good, cracks are generated around the catalyst particles in the generated coke, and when impact is received, the coke easily breaks from this crack, and it is difficult to sufficiently improve the coke strength. It was

On the other hand, in the present invention, the above-mentioned catalyst is contained in the coal particles in a dispersed state at the elemental level, and no cracks occur at the catalyst interface in the coal particles. Further, in order to produce a high-strength coke, coal particles that have been softened and melted need to firmly adhere to each other, but the coal particles containing the catalyst have extremely high adhesiveness with other coal particles around them. Since it is excellent, it is possible to produce coke having higher strength than conventional coke.

The content (mass%) of the alkaline earth metal and / or the transition metal is the percentage of the ratio of the mass of the alkaline earth metal and / or the transition metal contained in the coal to the mass of the coal. Required by.

That is, the numerical value obtained by the method for quantifying alkaline earth metal oxides and / or transition metal oxides in the method of analyzing JIS M8815 coal ash and coke ash is multiplied by 40/56 to multiply the alkaline earth metal in ash. And / or the mass% of the transition metal is determined. Next, JIS
M8812 The ash content (%) in coal is determined by the ash content determination method described in the industrial analysis method for coals and cokes.

Here, the content (%) of the alkaline earth metal and / or the transition metal is obtained by ash content (%) × mass% of the alkaline earth metal or transition metal in the ash / 100.

If the content of the alkaline earth metal and / or the transition metal in the coal is less than 1% by mass, there is a problem that the effect of improving the reactivity of coke becomes small because the amount of the catalyst is small.

Regarding the upper limit of the content of alkaline earth metal and / or transition metal, the higher the content, the better the catalytic effect is, so the more the content is, the more preferable it is. It is necessary to consider that the fixed carbon of will decrease.

At this time, the ratio of the coal containing the alkaline earth metal and / or the transition metal in an amount of 1% by mass or more in the blended coal is preferably 2% by mass or more. Here, the blended coal refers to coal charged into a coke oven, and is usually a mixture of at least two types of coal, in which 1 mass% or more of alkaline earth metal and / or transition metal is contained. It also includes coal. For example, the fact that the proportion of coal containing 1% by mass or more of alkaline earth metal / or transition metal in the blended coal is 2% by mass means that among the coals charged into the coke oven, alkaline earth metal / or Transition metal 1
It means that the ratio of coal containing 2% by mass or more is 2% by mass, and the ratio of other coals except coal containing 1% by mass or more of alkaline earth metal / or transition metal is 98% by mass. . If the ratio is less than 2% by mass, the amount of calcium as a catalyst is small and the effect of improving the reactivity of coke becomes small, which is not preferable.

In the process of softening and melting of coal into coke, the inventors have found that it is more preferable that alkaline earth metal and transition metal are present in the coal as extremely fine ash. It was It is considered that the reason is that when the alkaline earth metal and the transition metal are dispersed, they are taken into the matrix of the coke structure and the influence on the coke strength is reduced.

According to the studies by the inventors, the sizes of the alkaline earth metal and the transition metal in coal have an average particle size of 10
More preferably, it is less than or equal to μm. This is because when the average particle size is 10 μm or less, the dispersibility of the alkaline earth metal and the transition metal is good, the specific surface area of the catalyst is increased, and the catalytic effect is further increased. The thickness of the wall (matrix) between the pores and pores is about 10
This is because if the average particle size is 0 μm and the average particle size is 10 μm or less, the particles are taken into the substrate wall and the influence on the strength is further reduced.

The sizes of the alkaline earth metal and the transition metal can be measured by, for example, polishing the coal and then performing surface analysis focusing on the alkaline earth metal or the transition metal of EPMA or SEM.

It is generally known that the catalyst has a greater catalytic effect when the dispersibility is improved as much as possible and the specific surface area is increased. However, the alkaline earth metal and the transition metal in coal have good dispersibility. It is possible to sufficiently exert the effect as a catalyst without pulverizing. On the contrary, if the particle size of the coal blend is made fine, dust from the belt conveyor,
It is necessary to consider that problems such as dust generation when the blended coal is charged into the coke oven or an increase in carryover fine powder occur.

Among the coals containing 1% by mass or more of alkaline earth metal and / or transition metal, the present inventors blend coal having a total expansion coefficient of 25% or less and / or a fluidity of 1.3 or less. Have been found to be more preferable for improving coke reactivity. The reason is that when coking coal having a total expansion coefficient of 25% or less and / or a fluidity of 1.3 or less, many pores and cracks through which a reaction gas (carbon dioxide) can pass are formed in the product coke, It is considered that the coke reactivity is more activated. This is because such coal does not soften and melt so much during carbonization, so the pores originally present in the coal remain as they are, or the adhesiveness with other melting coal is poor, and cracks occur during resolidification shrinkage. It is thought that this is due to the occurrence of.

When the total expansion coefficient exceeds 25% or when the fluidity exceeds 1.3, the coal is often softened and melted during carbonization, so that the pores inherent in the coal as described above are generated. It is considered that the pores and the cracks through which the reaction gas can pass are reduced because the particles are blocked and the generation of cracks is suppressed.

Here, the total expansion coefficient means JIS M8801.
It is the sum of the shrinkage rate and the expansion rate measured by the expansivity test method according to. The fluidity is a common logarithmic value of the maximum fluidity measured by a fluidity test method according to JIS M8801.

Further, according to the study of the inventor, among coals containing 1% by mass or more of alkaline earth metal and / or transition metal, the total expansion coefficient is 25% or less and / or the fluidity is 1.3 or less. Since coal has poor caking properties, it was confirmed that fine pulverization further reduces caking properties and coke strength. On the contrary, it was confirmed that even if the grain size is coarse, it adversely affects the coke strength. Therefore, in order to suppress the decrease in coke strength, the crushed particle size of the above-mentioned coal is equivalent to the particle size of the coal normally charged in the coke oven, that is, the proportion of particles of 3 mm or less is 70% by mass to 80% by mass. Is more preferable, and the ratio of particles of 3 mm or less is 60% by mass or more, and the ratio of particles of 0.3 mm or less is 10% by mass or more and 50% by mass or less.

If the proportion of particles having a size of 3 mm or less is less than 60% by mass, the proportion of coarse particles increases, and the portion of coarse coal coarse particles having poor caking that is coked is likely to be the starting point of cracking and has a low coke strength. It is not preferable because it decreases. Three
The upper limit of the proportion of particles of mm or less is not particularly defined.

Furthermore, the ratio of particles of 0.3 mm or less is 1
If it is less than 0% by mass, the proportion of coarse particles increases, and the portion where coarse particles of coal having poor caking property are coked is likely to be a starting point of cracks and the coke strength is lowered, which is not preferable.

The proportion of particles of 0.3 mm or less is 50% by mass.
If it exceeds, the caking property is lowered and the coke strength is lowered, which is not preferable.

Further, the inventors have blended coal with coal containing an alkaline earth metal and / or a transition metal in an amount of 1% by mass or more, and further, reflectivity (Ro)
Is 1.2 or more and the maximum fluidity (MF) of the Giesera fluidity test satisfies the following equation (1): 10% or more of coking coal is added to improve coke reactivity and coke strength. It has also been found to be preferable for further improvement. MF> = − 2.8Ro + 6.4 (1) Here, the reflectance (Ro) is the maximum reflectance or average reflectance of vitrinite measured by the reflectance measurement method of the coal structure described in JIS M8816. It is the rate. The maximum fluidity (MF) of the Giesera fluidity test is an index measured by the coal fluidity test method described in JIS M8801.

The inventors of the present invention aim to further improve coke reactivity and coke strength, and in combination with coal containing the above catalyst (hereinafter referred to as coal 1), blended coal (hereinafter referred to as blended coal 1). The properties of coal (hereinafter, referred to as coal 2) to be blended in) and its blending ratio were experimentally investigated and examined.

FIG. 1 shows that the coal 1 contains 1.5% by mass of calcium, 10% by mass of coal having a maximum fluidity (MF) of 1.6, and the blended coal 1 has an average reflectance (Ro). The value is 1.1, and the average value of the maximum fluidity (MF) is 2.2.
80% by mass of blended coal consisting of several brands of coal, and 10% by mass of 33 types of coal having different reflectance (Ro) and maximum fluidity (MF) as the above-mentioned coal 2 were obtained by dry distillation. The result of investigating the relationship between the strength of the coke and the reflectance (Ro) and the maximum fluidity (MF) of coal 2 is shown.

The results shown in FIG. 1 indicate that the blended coal 1 and the coal 1 were blended in advance at a ratio of 90% to 10% and the carbonization was performed to obtain a drum strength (= 84.0), a reaction. The coke strength is + for the property (= 25 ml / min)
Plots were plotted as ◯ when the reactivity was improved by 0.2 or more and the reactivity satisfied 25 ml / min, and as x when the reactivity was not satisfied.

From this result, the straight line shown in the figure: MF =-
By combining the coal 2 (corresponding to caking coal) satisfying the relationship of the above formula (1) with the range of 2.8Ro + 6.4 or more, in combination with the coal 1 containing the catalyst, into the coal blend 1 It can be seen that the coke strength can be further improved while maintaining the reactivity of the coke.

Note that FIG. 1 shows the results of performing the blending ratio (mass%) of coal 2 at a constant 10 mass%. With the total amount of coal 1 (corresponding to coking coal) satisfying the relationship of charcoal 1 and MF> = − 2.8Ro + 6.4 being constant at 90% by mass, changing coal 2 within the range of 3 to 15% by mass. Similarly, as a result of investigating coke reactivity and strength, it was confirmed that the above effect was stably obtained when the blending ratio of coal 2 was 10% by mass or more.

From the above findings, in the present invention, the blending ratio of the caking coal satisfying the above formula (1) is set to 10% by mass or more. If the blending ratio of this coal is less than 10%, the above effect cannot be sufficiently exhibited due to the characteristics of these coals.

From the experimental results of the inventors, among the coking coals satisfying the above formula (1), the reflectance (Ro) is 1.2 or more, and the maximum fluidity of the Giesera fluidity test ( M
It has been confirmed that it is possible to further improve the coke strength while maintaining the reactivity of the coke by using coking coal having F) of 3.0 or more and blending 10% or more.

The reason why the coking coal having the above properties is blended with the coal containing the catalyst to significantly improve the coke strength without lowering the reactivity of the coke is as follows.
It is considered that when these caking coals are carbonized and softened and melted, they are well adhered to the coal containing the catalyst to improve the fixing strength.

Generally, when such a highly fluid caking coal is blended, the formation of pores of a size that controls the diffusion of gas into the coke is suppressed, and the reactivity is thought to decrease. In the case of blending caking coal and coal containing a catalyst, the interaction between these coals containing a catalyst and these caking coals does not suppress the generation of pores, and it is possible to reach a site containing a catalyst. It is considered that the porosity was generated and the reactivity did not decrease.

[0052]

[Example] Furnace width 425 mm, furnace height 400 mm, furnace length 60
Using a 0 mm test coke oven, the blended coal as shown in Table 1 was charged and charged at a charge density of 0.83 dry-t / m ³ , a furnace temperature of 1250 ° C., and a dry distillation time of 18.5 hours. It was distilled under the conditions. For the coke after firing, after cooling with nitrogen, the drum strength index (+15 mm index after 150 rotations) and the reactivity of the coke according to JIS K2151 were measured. Table 3 shows the calcium content, the average calcium particle size, the total expansion coefficient, and the fluidity of the used coals A to E. Table 4 shows the Fe content, average Fe particle size, total expansion coefficient, and fluidity of the coal F used. Table 5 also shows the reflectances and MFs of the used coals G to I.
Indicates.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

[Table 4]

[0057]

[Table 5]

In Comparative Example 1, 90% by mass of coal A and B of coal were used.
Is an example in which 10% by mass is mixed. At this time, the reactivity of the coke was 15, which did not reach the target value. This is because both the calcium contents of coals A and B are out of the range of the present invention, and the catalytic effect of calcium is not sufficient.

In Example 1, 90% by mass of coal A and coal C were used.
Is an example in which 10% by mass is mixed. At this time, the reactivity of the coke is 30, which is 25 or more, which is the target value. This is because the calcium content of coal C is as high as 1.8% by mass,
This is because the reactivity of coke is improved by the catalytic effect of calcium.

In Example 2, 90% by mass of coal A and coal D were used.
Is an example in which 10% by mass is mixed. The reactivity of coke is 35, which is higher than that in Example 1, and is 25 or more, which is the target value. This is because the average particle size of calcium in coal D is smaller than that of coal C used in Example 1 and the dispersibility is good.

In Example 3, 95% by mass of coal A and coal E were used.
5% by mass, and the pulverized particle size of E carbon is 3 mm or less 100
This is an example in which the amount is 55% by mass and 0.3 mm or less.
At this time, the drum strength was lower than in Examples 1 and 2 because the mass ratio of coal E was 0.3 mm or less, which was lower than that of Examples 1 and 2.
Although it is 0, the value is high enough to be used as blast furnace coke. The reactivity of coke is 30, which is 25 or more, which is the target value.

In Example 4, 95% by mass of coal A and coal E were used.
In an amount of 3% or less and 85% by mass or less and 0.3 mm or less and 25% by mass or less. At this time, the drum strength is improved by 2 points as compared with the third embodiment. This is because the crushed particle size of Coal E, which is inferior in caking property, was made coarser than that in Example 3, and thus the decrease in coke strength was suppressed. Also, the reactivity of coke is 30,
It is above the target value of 25.

In Example 5, 90% by mass of coal A and coal F were used.
Is an example in which 10% by mass is mixed. At this time, the reactivity of the coke is 29, which is 25 or more, which is the target value. This is because the Fe content of coal F was as high as 1.2% by mass, and the reactivity of coke was improved by the catalytic effect of Fe.

In Example 6, 80% by mass of coal A and coal G
Is an example in which 10% by mass and 10% by mass of coal C are mixed.
The fluidity of coal G is 2.7, and MF> -2.
8 × 1.37 + 6.4 = 2.56 is satisfied. At this time, the reactivity of the coke is 28, which is 25 or more, which is the target value. The coke drum strength is 85.
0, which is a higher value than Comparative Example 1 and Example 1.

In Example 7, 80% by mass of coal A and H of coal were used.
Is an example in which 10% by mass and 10% by mass of coal C are mixed.
The fluidity of coal H is 3.6, and MF> -2.
8 × 1.1 + 6.4 = 3.32 is satisfied. At this time, the reactivity of the coke is 29, which is 25 or more, which is the target value. The coke drum strength is 84.8.
Which is higher than Comparative Example 1 and Example 1.

In Example 8, 80% by mass of coal A and coal I were used.
Is an example in which 10% by mass and 10% by mass of coal C are mixed.
Coal I has a reflectance of 1.29 and a fluidity of 3.6, which satisfies the conditions of the reflectance of the present invention of 1.2 or more and the MF of 3.0 or more. At this time, the reactivity of the coke is 28, which is 25 or more, which is the target value. The coke has a drum strength of 85.3, which is higher than those of Comparative Example 1 and Example 1.

From the above, it is understood that the present invention makes it possible to produce a highly reactive blast furnace coke without impairing the coke strength.

[0068]

According to the present invention, a highly reactive coke for a blast furnace can be produced by an extremely simple method without impairing the coke strength. INDUSTRIAL APPLICABILITY The present invention establishes a method for producing a highly reactive coke for a blast furnace, which is suitable for use in the blast furnace, and has a large industrial value in that the reduction efficiency of the blast furnace can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the reflectance (Ro) and the maximum fluidity (MF) of coking coal and the coke reactivity and strength in the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisashige Kitaguchi             20-1 Shintomi, Futtsu City Nippon Steel Co., Ltd.             Inside the surgical development headquarters (72) Inventor Kiyoshi Shibata             20-1 Shintomi, Futtsu City Nippon Steel Co., Ltd.             Inside the surgical development headquarters F-term (reference) 4H012 MA01

Claims (7)

[Claims] 1. High reactivity for blast furnace, characterized in that 2% by mass or more of coal containing 1% by mass or more of alkaline earth metal and / or transition metal is mixed in compounded coal and carbonized in a coke oven. Coke manufacturing method. 2. The method for producing a highly reactive coke for a blast furnace according to claim 1, wherein the average particle size of the alkaline earth metal and the transition metal is 10 μm or less. 3. The method for producing a highly reactive coke for a blast furnace according to claim 1, wherein the alkaline earth metal is Ca and the transition metal is Fe. 4. The total expansion coefficient of the coal is 25% or less and / or the fluidity is 1.3 or less,
The method for producing the highly reactive coke for a blast furnace according to claim 1. 5. In the coal, the proportion of coal particles having a diameter of 3 mm or less is 60 mass% or more, and the proportion of coal particles having a diameter of 0.3 mm or less is 10 mass% or more and 50 mass% or less. Item 5. A method for producing a highly reactive coke for a blast furnace according to any one of Items 1 to 4. 6. The reflectance (R
O) is 1.2 or more, and 10% or more of caking charcoal which the maximum fluidity (MF) of a Giesera fluidity test satisfies the following formula (1) is blended 10% or more, It is characterized by the above-mentioned. The method for producing a highly reactive coke for a blast furnace according to any one of claims 1. MF> = − 2.8Ro + 6.4 (1) 7. The reflectance (R
O) is 1.2 or more, and the maximum fluidity (MF) of the Giesera fluidity test is 3.0 or more, and 10% or more of caking coal is mix | blended, It is characterized by the above-mentioned. Item 3. A method for producing a highly reactive coke for a blast furnace according to Item.