KR20210069880A - Method of preparing cockes - Google Patents

Abstract

The present invention relates to a method for manufacturing high-strength coke for a furnace. The manufacturing method includes the steps of: manufacturing raw coal by mixing blended coal and high carbonization coal; separating the raw coal into first raw coal and second raw coal; manufacturing coal briquettes by molding the first raw coal; manufacturing mixed coal by mixing the coal briquettes and the second raw coal; and heat-treating the mixed coal.

Description

The manufacturing method of coke {METHOD OF PREPARING COCKES}

To provide a method for producing coke.

As a countermeasure against the global warming problem caused by GHG (Green House Gas), efforts around the world to reduce _{CO 2 emission, which is one of the GHG gases, are in progress. Korea also announced a 37% reduction in the 2030 CO 2} emission estimate in the Paris Agreement for 15 years, and is conducting a lot of research and development.

In order to produce molten iron (molten iron) from ore in a blast furnace, a carbon reducing agent (hereinafter referred to as coke) is generally used. Coke is produced in the form of lumps by heating in an inert atmosphere using caking coal. Coke is fed to the furnace to produce carbon monoxide, which serves as a reducing agent to reduce the ore, and also reacts with the air supplied to the furnace to supply heat and a passage through which gases and molten iron/slag in the furnace can flow. plays a role Most of this coke is composed of carbon (87% or more), and eventually it is _{discharged as CO 2} , so there is a problem of a large amount of emission as a result.

Therefore, _{it is necessary to reduce the generation of CO 2} by coke, and for this purpose, it is necessary to reduce the coke used in the furnace.

As one of the methods of reducing the amount of coke used in the blast furnace, that is, the coke usage cost, a method of blowing by-product gas having a high hydrogen content generated in the steel mill into the lower part of the blast furnace has been proposed. At this time, since hydrogen is also used as a reducing agent, it is possible to reduce the coke usage ratio.

As an example of this method, COG (coke oven gas) in the by-product gas is reformed so that the hydrogen content is from 56% to 80% or more and blown into the furnace, and the coke is partially replaced by hydrogen reduction in the furnace to CO ₂ A study to reduce generation by 10% (COURSES50) is being conducted in Japan.

Since the blast furnace using hydrogen as a reducing agent can use a small amount of coke, the thickness of the coke layer charged and accumulated in the blast furnace is thinner than before, and hydrogen has a faster reduction rate compared to carbon monoxide at high temperatures. Since _{the reaction between H 2 O and coke occurs faster than the reaction between CO 2} and coke produced by the carbon monoxide reduction reaction, the coke may be consumed faster.

In this way, the coke layer formed by accumulating coke supports the load of the charges (ore and coke) that are continuously charged into the furnace over it, and serves as a heat source, reducing agent, and ventilation/liquid permeability, so hydrogen is used as a reducing agent in this way. In the furnace used, the coke used in a smaller amount than in the general furnace must be subjected to the same stress as in the general furnace, so higher strength coke is required.

Accordingly, in the COURSE50 study in Japan, research is being conducted on the development of a technology that aims to achieve a coke strength of 88% or more.

In order to produce high-strength coke for blast furnaces using hydrogen as a reducing agent, many studies have been conducted on mixing ashless coal as an additive to coal blended coal for coke production. For example, Japanese Patent Application Laid-Open No. 2018-131549 discloses a method of manufacturing coke by extracting ashless coal from bituminous coal or lignite coal, mixing the ashless coal with coal, and controlling the temperature increase rate in the coal softening temperature region. , Japanese Patent Registration No. 6227482 proposes a method of manufacturing coke for a blast furnace by mixing 3 wt% to 20 wt% of ashless coal with coal blended coal for coking so that the expansion rate of the coal blended coal is 20% or less, and Japanese Patent Registration 6189811 No. presents a technique for utilizing the expansion index and true specific gravity of ashless coal when determining the blending amount of ashless coal when mixing ashless coal and raw coal.

Ashless coal is extracted from coal using a solvent at high temperature and high pressure. There is no ash and there is no caking property, so it has an effect of improving coke strength when added. However, it requires a lot of cost to manufacture ashless coal because it uses a complex process and solvent at high temperature and high pressure. There is a problem with the economic feasibility.

As another method for manufacturing high-strength coke, a method of using raw coal blending, pretreatment, and additives is being studied. Of these, the raw coal blending method relates to a blending technology using caking properties and dry distillation properties, the pretreatment method relates to coal drying, coal particle size control, and oil addition to improve the charging density, and the additive method is tar/pitch addition to supplement the caking property. , adding an inert material, and the like.

One embodiment is to provide a method for producing coke using hydrogen as a reducing agent.

According to one embodiment, the method comprising: preparing raw coal by mixing coal blended coal with high carbonization coal; separating the raw coal into first and second raw coal; manufacturing the coal briquettes by molding the first raw coal; preparing coal briquettes by mixing the coal briquettes and the second coal briquettes; And it provides a method for producing coke comprising the step of heat-treating the coal mixture.

Vitrinite reflectance (Rm) of the high carbonization coal is 1.3% to 1.7% can

The vitrinite reflectance (Rm) of the coal blend may be 1.0% to 1.15%.

The vitrinite reflectance (Rm) of the mixed coal may be 1.11% to 1.215%.

In one embodiment, the process of preparing a mixture by mixing the raw coal and tar may be further performed. In this case, the mixing ratio of the raw coal and the tar may be 97: 3 by weight to 95: 5 by weight. In addition, the mixing ratio of the coal blend and the high carbonization degree coal may be in a weight ratio of 2:10 to 5:20 by weight.

The first raw coal corresponds to a maximum of 50% by weight of the weight of the raw coal, and according to one embodiment, may correspond to 10% to 50% by weight of the weight of the raw coal.

The second raw coal may be powdered coal.

The coal blend may include 85% or more of particles having a particle size of 3 mm or less.

The maximum fluidity (LMF) of the coal blend may be 2.3 to 2.5, and the total expansion coefficient (TD) may be 90% to 110%.

The method for manufacturing coke according to an exemplary embodiment may manufacture high-strength coke having excellent hot strength and cold strength.

1 is a view schematically showing a process of a method for manufacturing high-strength coke for a furnace according to an embodiment.
FIG. 2 is a graph showing cold strength of coke prepared according to Examples 1 to 6 and Comparative Example 1. FIG.
3 is a graph showing hot strength of coke prepared according to Examples 1 to 6 and Comparative Example 1. FIG.
4 is a graph showing the measurement of the charging density of coke prepared according to Examples 7 to 11 and Comparative Example 1. FIG.
5 is a graph showing cold strength of coke prepared according to Examples 7 to 11 and Comparative Example 1. FIG.
6 is a graph showing the measurement of hot strength of coke prepared according to Examples 7 to 11 and Comparative Example 1. FIG.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, and the present invention is not limited thereto, and the present invention is only defined by the scope of the claims to be described later.

A method of manufacturing coke according to an embodiment includes: preparing raw coal by mixing coal blended coal with high carbonization coal; separating the raw coal into first and second raw coal; manufacturing the coal briquettes by molding the first raw coal; preparing coal briquettes by mixing the coal briquettes and the second coal briquettes; and heat-treating the coal mixture.

Hereinafter, a method of manufacturing coke according to an embodiment will be described in detail with reference to FIG. 1 .

Coal is prepared by mixing coal blended coal with high carbonization degree coal (S1).

High carbonization coal generally refers to coal with a high degree of coalescence, and as the degree of coalification increases, the carbon content increases and the volatile matter content decreases. means high coal.

In one embodiment, among the high carbonization coals having a high vitrinite reflectance (Rm), in particular, high carbonization coal having a vitrinite reflectance (Rm) of 1.3% to 1.7% may be preferably used. When the vitrinite reflectance (Rm) is within the above range, an appropriate number of benzene ring rings are included in the coal, and the carbon in the matrix structure that can react with carbon dioxide is reduced accordingly, so that _{the reactivity of CO 2} can be appropriately reduced , the strength of the product coke can be further increased, which is appropriate. In particular, since it is used in combination with coal blended coal, the degree of coalification can be increased.

If the vitrinite reflectance of the high carbonization coal is lower than the above range, it is difficult to improve the strength of the product coke to a desired level. Due to this deficiency, the strength of the coke produced may be lowered.

The particle size of the high carbonization coal may be appropriately adjusted and used according to the caking properties of the high carbonization coal. For example, in the case of high carbonization coal with little caking property, those having a particle size of 0.1 mm or less can be used, and in the case of high carbonization coal with caking property, those containing 85% or more of particles having a particle size of 3 mm or less can be used. .

The coal blend is prepared by mixing various single coals, and for example, it can be prepared by mixing single coals widely used in the art, such as American coal, strong coal, semi-strong coal, weak coal, and ordinary coal. . In a more detailed description of this, coal blended coal is manufactured by pulverizing single coals for each type of coal to a certain particle size in a crusher, placing them in a hopper for each type of coal, and then discharging a certain amount of each single coal from the hopper and mixing it on a belt. can

Regardless of the type and number of single coals in the coal blend, it is appropriate to mix and adjust the physical properties of the coal blend so that the vitrinite reflectance (Rm) is 1.0% to 1.15%. When the blended coal having a vitrinite reflectance within the above range is mixed with high carbonization coal, it is possible to obtain an advantage of improving the cold and hot strength of the produced coke.

In addition, in the coal blend, each single coal may be crushed to a particle size of 10 mm or less, and in particular, may include 85% or more of particles having a particle size of 3 mm or less. As a result, coal blends are mostly composed of particles with a small particle size of 3 mm or less, and during the heat treatment process, The advantage of improving bonding by softening and melting can be obtained.

In addition, regardless of the type and number of single coals in the coal blend, the maximum fluidity (LMF: Logarithmic Maximum Fluidity) of the coal blend is 2.3 to 2.5, and the total expansion rate (TD) is adjusted to be 90% to 110%. Mixing is appropriate. When the maximum fluidity and total expansion coefficient of the oriented coal are within the above ranges, it is possible to obtain an advantage that the softened molten material of coal can improve the bonding between coal particles during the heat treatment process.

In addition, the coal blend may include 25 wt% to 27 wt% of volatile matter, 8 wt% to 10 wt% of ash, and the balance fixed carbon. When coal blended coal having such a composition is used, it is possible to obtain the advantage of economically producing coke of a quality suitable for a blast furnace.

The mixing ratio of the coal blend and the high carbonization degree coal may be 80: 20 weight ratio to 98.5: 1.5 weight ratio, and 80: 20 weight ratio to 98: 2 weight ratio.

When the mixing ratio of the coal blended coal and the high carbonization degree coal is included in the above range, the vitrinite reflectance of the mixed coal for coke production manufactured using the raw coal may be a desired level of 1.11% to 1.215%.

Next, the raw coal is separated into a first raw coal and a second raw coal (S2). In this case, the first raw coal means to correspond to a maximum of 50% by weight, preferably 10 to 50% by weight of the weight of the raw coal, and the remainder is referred to as the second raw coal. Since the second raw coal was not formed, it exists as powdered coal.

In one embodiment, in order to supplement the caking properties of the raw coal, a process of mixing the raw coal and tar may be further performed before separating the raw coal into the first and second raw coal. In this case, the mixing ratio of the raw coal and the tar may be 97: 3 weight ratio to 95: 5 weight ratio. When the mixing ratio of the raw coal and the tar is out of the above range, that is, when the amount of tar used is too small, caking is not sufficient, and when the amount of tar is too excessive, the effect of improving coke quality and improving the strength of coal briquettes during production of coal briquettes cannot be obtained, which may not be appropriate.

Coal briquettes are manufactured by molding the first coal briquettes, and the coal briquettes are mixed with the second coal briquettes to prepare coal briquettes (S3). As described above, when the coal briquettes are manufactured from the first coal briquettes that are a part of the coal briquettes, and the coal briquettes and the second coal briquettes are mixed, it is appropriate because the charging density can be increased.

Coal briquettes are prepared with the first coal briquettes corresponding to a maximum of 50% by weight, preferably 10% to 50% by weight of the raw coal weight, and the second coal briquettes are obtained by excluding the first coal briquettes from the raw coal, so the coal briquettes and the second mixture It goes without saying that the mixing ratio of the coal is the same as the contents of the first and second raw coals. That is, the coal mixture contains at most 50% by weight, preferably 10% to 50% by weight of the coal briquettes, and contains at least 50% by weight, preferably 90% to 50% by weight of the second raw coal. can do.

The vitrinite reflectance of the mixed coal may be 1.11% to 1.215%. If the vitrinite reflectance of the mixed coal is lower than 1.11%, the matrix structure of the final product, coke, is weak and the quality is deteriorated. If it is higher than 1.215%, the bonding between the coal particles may be insufficient, so that the final product It is not suitable because the quality of the product coke may be deteriorated.

Coke is manufactured by heat-treating the coal mixture (S4). This heat treatment process may be performed at a temperature of 1050 ° C. to 1100 ° C. for 8 hours to 24 hours. To describe the heat treatment process more specifically, the mixture is added to a furnace heated to 650 ° C. to 700 ° C., and heated to 1050 ° C. to 1100 ° C. at a heating rate of 2 ° C./min to 3 ° C./min. , when the core temperature of the furnace reaches 1000°C to 1100°C, it can be carried out by maintaining a soaking time for 1 hour to 2 hours. As the furnace, a general furnace widely used in the art may be used.

Coke produced by this process can exhibit good strength, such as good cold strength and good hot strength.

Such coke can be usefully used in a furnace, and in particular, it can be usefully used in a furnace using hydrogen as a reducing agent.

Hereinafter, Examples and Comparative Examples of the present invention will be described. The following examples are only examples of the present invention, and the present invention is not limited to the following examples.

(Comparative Example 1 and Examples 1 to 6)

10 types of single bullets were crushed with a crusher, and the particle size was prepared to be 10 mm or less.

Combined coal was prepared by mixing 10 types of single coals whose particle size was adjusted to 10 mm or less so as to have the physical properties shown in Table 1 below, and 85 wt % of the particles to have a particle size of 3 mm or less.

ash
(Ash, wt%) volatile matter
(VM, wt%) Fixed Carbon (F.C.) Vitrinite Reflectance (Rm, %) maximum flow
(LMF) total expansion rate
(TD, %) 9.11 26.04 balance 1.1 2.53 101

High carbonization coal having the physical properties shown in Table 2 was prepared. The particle size of the high carbonization coal A shown in Table 2 below was prepared to be 0.1 mm or less, and the high carbonization coal B was prepared in which 85 wt% of the particles had a particle size of 3 mm or less.

division Industrial analysis (dry basis), wt% Properties Volatile content (V.M) Ash Fixed Carbon (F.C.) reflectivity
(Rm, %) maximum flow
(LMF) total expansion rate
(TD, %) Free Swelling Index (FSI) A 18.78 10.32 70.90 1.31 0 0 One B 15.45 9.35 75.2 1.67 0.79 34 7.5

Coal coal was prepared by mixing the coal blended coal shown in Table 1 and the high carbonization degree coal shown in Table 2 at the content shown in Table 3 below. 50 wt% of the raw coal was separated into the first raw coal, and the remaining 50 wt% was separated into the second raw coal.

Coal briquettes were manufactured by molding the first raw coal, and the coal briquettes were mixed with the second raw coal to prepare coal briquettes. Since the coal briquettes were prepared in 50 wt% of the raw coal, in the coal briquettes, the content of the coal briquettes was 50 wt%. The vitrinite reflectance of this mixed coal was measured, and the results are shown in Table 3 below.

The mixed coal was gravity-charged from the top in a coke test furnace heated to 650°C. In the coke test furnace, a battery heater was used so that heat transfer could occur from both walls in the same manner as in a commercial coke oven.

Then, the heating wall temperature of the coke test furnace is heated to 1100° C. at a heating rate of 2.7° C./min. When the oven center temperature reaches 1080° C., a soaking time is maintained for 1 hour, followed by extrusion. Then, the extruded red young coke was digested and cooled under a nitrogen atmosphere to prepare coke. The gas generated during this heat treatment process, that is, the coal distillation process, was burned with an after burner and released into the atmosphere.

Coal blend (wt%) High carbonization coal type (A or B) high carbonization coal
(weight%) Mixed projectile reflectance
(Rm, %) Comparative Example 1 100 X 0 1.1 Example 1 94 A 6 1.113 Example 2 90 A 10 1.121 Example 3 95 B 5 1.129 Example 4 90 B 10 1.157 Example 5 85 B 15 1.186 Example 6 80 B 20 1.214

* Cold strength (Drum index) evaluation

After 10 kg of the coke prepared in Examples 1 to 6 and Comparative Example 1 was rotated 150 times in a drum having a diameter of 1.5 m, only coke having a particle size of 15 mm or more was classified and obtained. ^{The cold strength, DI 150} ₁₅ , which is the weight ratio of coke having a separated particle size of 15 mm or more to the total weight of coke (10 kg), was obtained, and the results are shown in FIG. 2 . In FIG. 2, Rm is the vitrinite reflectance of the mixed coal shown in Table 3 above.

As shown in Table 3, in the case of the mixed coal according to Examples 1 to 6, in which the high carbonization coal was mixed with the coal blend, the reflectance of the mixed coal according to Comparative Example 1 that did not use the high carbonization coal was 1.1%, improved 1.113% to 1.214%, and it can be seen that the cold strength value of the coke according to Examples 1 to 6 was almost similar to that of Comparative Example 1 or slightly increased, and as a result, the cold strength value was as high as about 78%.

As such, since the cold strength value is high, it can be seen that the high-strength coke has a low content of coke differentiated into fine powder.

* Evaluation of hot strength (strength after reaction, Coke Strength after Reaction, CSR)

The coke prepared according to Examples 3 to 6 and Comparative Example 1 was classified, and only coke having a particle size of 20 nm was obtained. 200 g of obtained coke having a particle size of 20 mm _{was reacted at 1100° C. for 2 hours under a CO 2} atmosphere, and then rotated 600 times on an I drum, and only coke having a particle size of 10 mm or more was classified and obtained. The hot strength, CSR (%), which is the weight ratio of coke having a separated particle size of 10 mm or more to the total coke weight (200 g), was calculated, and the results are shown in FIG. 3 . In FIG. 3, Rm is the vitrinite reflectance of the mixed coal shown in Table 3 above.

As shown in FIG. 3 , as the amount of high carbonization coal increases, the reflectance of the mixed coal increases, and as the reflectance of the mixed coal increases, it can be seen that the hot intensity value also increases linearly. This is because, as the carbonization degree of coal increases, the vitrinite reflectance increases, the benzene ring contained in the coal increases, and the structure of the coke, which is the final product, becomes dense, and the reaction _{between carbon and CO 2 in the coke matrix structure decreases.} is judged to be

(Examples 7 to 11)

Coal coal was prepared by mixing coal blended coal shown in Table 1, high carbonization coal shown in Table 2, and tar in the amounts shown in Table 4 below. A part of the weight of the raw coal was separated into the first raw coal, and the remaining weight was separated into the second raw coal. In this case, the contents of the first and second raw coal are shown in Table 4 below.

Coal briquettes were manufactured by molding the first raw coal, and the coal briquettes were mixed with the second raw coal to prepare coal briquettes. At this time, since the coal briquettes were prepared with the first raw coal, the content of the coal briquettes was the same as that of the first coal briquettes in 100 wt% of the mixed coal. The vitrinite reflectance of the mixed coal was measured, and the results are shown in Table 4 below. For comparison, the composition and vitrinite reflectance measurement results of Comparative Example 1 are also shown in Table 4 below.

The mixed coal was gravity-charged from the top in a coke test furnace heated to 650°C. In the coke test furnace, a battery heater was used so that heat transfer could occur from both walls in the same manner as in a commercial coke oven.

Then, the heating wall temperature of the coke test furnace is heated to 1100°C at a heating rate of 2.7°C/min, and when the oven center temperature reaches 1080°C, the soaking time is maintained for 1 hour, Then, the extruded red young coke was digested and cooled under a nitrogen atmosphere to prepare coke. The gas generated during this heat treatment process, that is, during the coal drying process, was burned with an after burner and released into the atmosphere.

blended coal
(weight%) High carbonization coal type (A or B) high carbonization coal
(weight%) tar
(weight%) 1st Coal Coal
(weight%) 2nd Coal
(weight%) Reflectance of mixed projectiles (Rm, %) Comparative Example 1 100 A 0 0 0 100 1.1 Example 7 91 A 6 3 10 90 1.113 Example 8 91 A 6 3 20 80 1.113 Example 9 91 A 6 3 30 70 1.113 Example 10 91 A 6 3 40 60 1.113 Example 11 91 A 6 3 50 50 1.113

* Bulk Density evaluation

The charging density of the coke prepared according to Examples 7 to 11 and Comparative Example 1 was measured by ASTM D291-07 Standard Test Method for Cubic Foot Weight of Crushed Bituminous Coal, and the results are shown in Fig. 4 is shown.

As shown in FIG. 4 , it can be seen that as the coal briquettes mixing ratio increases, the bulk density increases. In particular, in the case of Example 7 in which the coal briquettes mixing ratio is 10% by weight, Comparative Example in which the coal briquettes are not mixed Compared to 1, the charging density was significantly increased, and it can be seen that it increased linearly when increasing to 20 wt%, 30 wt%, 40 wt%, and 50 wt%. Since the coal briquettes have a higher apparent density than the second coal briquettes, it is determined that the charging density increases as the coal briquettes mixing ratio increases.

* Cold strength (Drum index) evaluation

After 10 kg of the coke prepared in Examples 7 to 11 and Comparative Example 1 was rotated 150 times in a drum having a diameter of 1.5 m, only coke having a particle size of 15 mm or more was classified and obtained. ^{The cold strength, DI 150} ₁₅ , which is the weight ratio of coke having a particle size of 15 mm or more separated to the total weight of coke (10 kg), was obtained, and the results are shown in FIG. 5 .

As shown in FIG. 5 , it can be seen that as the content of coal briquettes increases, the cold strength increases. It is considered that as the content of the coal briquettes increases, the charging density increases by 19% or more, and the coke structure becomes dense, so that the cold strength increases.

* Evaluation of hot strength (strength after reaction, Coke Strength after Reaction, CSR)

The coke prepared according to Examples 7 to 11 and Comparative Example 1 was classified, and only coke having a particle size of 20 nm was obtained. 200 g of obtained coke having a particle size of 20 mm _{was reacted at 1100° C. for 2 hours under a CO 2} atmosphere, and then rotated 600 times on an I drum, and only coke having a particle size of 10 mm or more was classified and obtained. The hot strength, CSR (%), which is the weight ratio of coke having a separated particle size of 10 mm or more to the total coke weight (200 g), was calculated, and the results are shown in FIG. 6 .

As shown in Figure 6, as the content of the coal briquettes increases, it can be seen that the hot strength value also increases linearly. It is considered that as the content of the coal briquettes increases, the charging density increases by 19% or more, and the coke structure becomes dense and the hot strength increases.

The present invention is not limited to the above embodiments, but can be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present invention pertains can take other specific forms without changing the technical spirit or essential features of the present invention. It will be understood that it can be implemented as Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (12)

preparing raw coal by mixing coal blended coal with high carbonization degree coal;
separating the raw coal into first and second raw coal;
manufacturing the coal briquettes by molding the first raw coal;
preparing coal briquettes by mixing the coal briquettes and the second coal briquettes; and
heat-treating the coal mixture
A method for producing high-strength coke for a furnace comprising a. According to claim 1,
The method for producing coke having a vitrinite reflectance (Rm) of 1.3% to 1.7% of the high carbonization coal. According to claim 1,
A method for producing coke having a vitrinite reflectance (Rm) of 1.0% to 1.15% of the coal blend. According to claim 1,
A method for producing coke having a vitrinite reflectance (Rm) of 1.11% to 1.215% of the mixed coal. According to claim 1,
Before the step of separating the raw coal into a first raw coal and a second raw coal, a process of mixing the raw coal and tar is further performed. 6. The method of claim 5,
The mixing ratio of the raw coal and tar is 97:3 to 95:5 by weight. According to claim 1,
The mixing ratio of the coal blend and the high carbonization degree coal is 80: 20 weight ratio to 98.5: 1.5 weight ratio of coke manufacturing method. According to claim 1,
The method for producing high-strength coke for a blast furnace, wherein the first raw coal corresponds to a maximum of 50% by weight of the weight of the raw coal. 9. The method of claim 8,
The method for producing high-strength coke for a blast furnace, wherein the first raw coal corresponds to 10% to 50% by weight of the weight of the raw coal. According to claim 1,
The method of manufacturing high-strength coke for a blast furnace, wherein the second raw coal is powdered coal. According to claim 1,
The method for producing coke for a blast furnace, wherein the coal blend contains 85% or more of particles having a particle size of 3 mm or less. According to claim 1,
The maximum fluidity (LMF) of the coal blend is 2.3 to 2.5, and the total expansion coefficient (TD) is a method of manufacturing high-strength coke for a blast furnace of 90% to 110%.

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