MÉTODO PARA PRODUZIR COQUE

Abstract

Provided is a coke production method capable of suppressing a decrease in the strength of the produced coke even when the coke is produced by using mixed coal that is mixed with a carbon material having abnormal surface tension.　This method for producing coke produces coke through dry distillation of mixed coal obtained by mixing a molded article containing a plurality of brands of coal and a powder coal mixture containing a plurality of brands of powdery coal, wherein the brands and the mixing ratios of coal to be mixed in the molded article and the powdery coal mixture are determined so that the interface tension γp of the powdery coal mixture and the interface tension γinter of the mixed coal calculated using the surface tension of heat-treated coal obtained by heat-treating each brand of coal contained in the mixed coal and the mixing ratio of coal of each brand satisfy γinter > γp and γp < 0.03.

Description

1 / 32 METHOD FOR PRODUCING COKE Technical Field

[001] The present invention relates to a method for producing coke. In the method for producing coke, a portion of the coal marks used as feedstock that are carbonized is formed coal. The method includes adjusting the composition of the feedstocks for the formed coal. Antecedent Technique

[002] In blast furnaces, blast furnace coke is used as a reducing agent, heat source, and support material to maintain gas permeability and liquid permeability. The stable operation of blast furnaces requires ensuring gas permeability and liquid permeability in the blast furnaces and therefore requires that the coke have excellent properties; these properties include strength, particle size, and post-reaction strength. In particular, coke strengths, such as tumble resistance, are particularly important properties for blast furnace coke.

[003] Blast furnace coke is produced by carbonizing coal in a carbonization furnace, thereby thermally plasticizing the coal to cause the coal particles to bind to one another. Consequently, the production of high-strength coke requires binding coal with excellent thermoplasticity. Currently, however, suitable binding coal for coke production is nearing depletion. Therefore, there is a need for greater use of materials that have not been used for coke production in the past, such as coal with low thermoplasticity and non-coal carbon materials. Examples of non-coal carbon materials include biomasses such as wood pellets and palm oil residues, torrefied biomasses obtained by subjecting a biomass to torrefaction, carbon materials Petition 870250084110, dated 09 / 18 / 2025, page 8 / 89 2 / 32 of biomass is obtained by subjecting biomass to heat treatment and plastics. As the need to reduce CO2 emissions is increasing today, there is a need to use carbon-derived materials from biomass, residual plastics, and similar sources for coke production.

[004] Blast furnace coke production involves the use of a coal mixture containing various types of coal mixed together. Consequently, in the related area, studies have been conducted on methods for estimating the coking strength of coke produced using a coal mixture as feedstock. Recently, it has been discovered that the surface tension of coal in a thermally plasticized state influences the bond strength of the coal. Patent Literature 1 describes a method for mixing coal and a method for producing coke that utilizes surface tensions and interfacial tensions calculated from the surface tensions.Patent Literature 1 describes that the interfacial tension that occurs between particles of different types of coal is determined based on the surface tensions of the heat-treated coal (semicolon) obtained by heat treatment of the coal (hereinafter referred to as coal surface tensions), and that a coal mixture is controlled based on the magnitude of the interfacial tension.

[005] Coke production involves the carbonization of coal, thereby thermally plasticizing the coal to cause the coal particles to fuse together. Consequently, it can be assumed that the bond strength between coal particles affects the strength of the coke that is produced. In general, the bond strength between coal particles is improved as the interfacial tension at the bonding interfaces decreases. Interfacial tension is expressed in units of mN / mcg, therefore it can be considered free energy present at the interfaces. That is, the presence Petition 870250084110, dated 09 / 18 / 2025, p. 9 / 89 3 / 32 Interfacial tension means that free energy that can act as a force at the interfaces is present. Consequently, it can be assumed that when there is high interfacial tension, rupture at the bonding interfaces is likely to occur. Patent Literature 1 states that when the interfacial tension of the coal mixture is greater than 0.03 mN / m, the strength of the coke produced decreases significantly and that, therefore, it is preferable that the interfacial tension of the coal mixture be 0.03 mN / m or less. List of citations Patent Literature

[006] PTL 1: International Publication No. 2013 / 054526 Non-Patent Literature

[007] NPL 1: MC Williams and DW Fuerstenau, International Journal of Mineral Processing, 20 (1987), pp. 153-157 Summary of the invention Technical problem

[008] Patent Literature 1 states that, to obtain high-strength coke, it is preferable that the various types of coal be mixed in such a way that the interfacial tension of the coal mixture decreases. Consequently, an effective way to produce high-strength coke is to use various types of coal with similar surface tension values ​​in the coal mixture. With this approach, however, it is difficult to use coal with excessively high surface tension and coal with excessively low surface tension. Patent Literature 1 does not disclose any approach that prevents the decrease in coke strength associated with the use of coal or a carbon material with a surface tension significantly different from a weighted average value of the surface tensions of the coal and carbon material included in the coal mixture, and therefore Patent Literature 1 presents a problem, as the range of coal resources that can Petition 870250084110, dated 09 / 18 / 2025, page 10 / 89 4 / 32 of the available usage is limited.

[009] If the range of coal resources that can be used as feedstocks for coke can be expanded, a very significant advantage can be gained in terms of consistent feedstock production and expanding the use of feedstocks that are difficult to utilize. Therefore, there is a need for a method to produce coke that can inhibit the decrease in the strength of the coke that is produced, even if the coke is produced with a coal mixture containing, mixed into it, coal or a carbon material with excessively high surface tension, or coal or a carbon material with excessively low surface tension, compared to the average surface tension of the coal mixture.In the description below, coal or carbon material with excessively high surface tension and coal or carbon material with excessively low surface tension, compared to the average surface tension of the coal mixture, are referred to as carbonaceous material with anomalous surface tension.

[0010] The present invention was made in view of these circumstances, and an objective of the present invention is to provide a method for producing coke that can inhibit a decrease in the strength of the coke that is produced, even if the coke is produced with a coal mixture in which a carbonaceous material with an anomalous surface tension is mixed. Solution to the problem

[0011] The means to solve the problem are as follows.

[0012] [1] A method for producing coke, the method including the production of coke by carbonization of a coal mixture obtained by mixing formed coal with a mixture of coal fines, the formed coal including coal marks, the coal fines mixture including powdered coal marks, wherein the method includes select Petition 870250084110, dated 09 / 18 / 2025, p. 11 / 89 5 / 32 nar marks and mixing ratios of coal that is included in the formed coal and of coal that is included in the coal fines mixture, such that an interfacial tension Yinter of the coal mixture and an interfacial tension γρ of the coal fines mixture satisfy Yinter > γρ and γρ < 0.03, where the interfacial tension Yinter and the interfacial tension YP are calculated from the surface tensions of the heat-treated coal obtained by heat-treating the coal marks that are included in the coal mixture and the mixing ratios of the coal marks, using equation (1) or equation (2), shown below. Mathematics 1

[0013] Yinter OU Yp=wrwt(1) where Ku K12 Yij ·'* Yin Y21 Y22 : Kii Yij Yin Ynl '* YnJ ''' Ynn yíj = yí + yj - βχρ[-β(γι - r / )2]yw Yij = Yji VtZ = (wí W2Wf · · · Wn) γ: the surface tension of heat-treated coal i Yij: the interfacial tension at an interface between thermally treated coal i and thermally treated coal j β = 0.0001247 [(m2mJ)2] w,: the mixing ratio of coal i Yinter or γρ: the interfacial tension of the coal mixture or coal fines mixture. Mathematics 2 Yinter OR γρ=0.032θ γ2(2) where Petition 870250084110, dated 09 / 18 / 2025, p. 12 / 89 6 / 32100ÍV 2 (ΣίΙΐ / ίΐνί)2=100Z?=1uzí-i[2í''-w'-^l^-] η Σ^= 11=1 γ,: the surface tension of thermally treated coal i Yij: the interfacial tension at an interface between heat-treated coal i and heat-treated coal jw: the mixing ratio of coal i Yinter or γρ: the interfacial tension of the coal mixture or coal fines mixture.

[0014] [2] The method for producing coke, according to [1], wherein at least one of the formed coal and of the coal fines mixture contains a carbon material, wherein the method includes selecting grades and mixing ratios of coal that is included in the formed coal and of coal that is included in the coal fines mixture and selecting a type and mixing ratio of the carbon material that is included in the formed coal and of the carbon material that is included in the coal fines mixture, such that the interfacial tension Yinter of the coal mixture and the interfacial tension γρ of the coal fines mixture satisfy Yinter > Yp θ Yp < 0.03, wherein the interfacial tension Yinter and the interfacial tension yp are calculated from the surface tensions of the heat-treated coal and the carbon material, the heat-treated coal being obtained by heat treatment of the coal grades that are included in the coal mixture;and the mixing ratios of the coal marks and carbon material, using equation (3) or equation (4), shown below, instead of equation (1) or equation (2).; Mathematics 3

[0015] Yinter OU YP=WrW1(3) where Petition 870250084110, dated 09 / 18 / 2025, p. 13 / 89 7 / 32 'Yu Υ12 -· Ylj ·· / 1)1 K21 Y22 : Hl Yij Yin Xnl......Ynj * Ynn Ylj = Yi + Yj - βχρ[~β(Υι - Yj)2]^YÍYj Ylj = Yji W = (Wi W2' ' · W( * · · wn) n ZW'= 1t=l Yi: the surface tension of heat-treated coal i or carbon material i Yij: the interfacial tension at an interface between heat-treated coal i or carbon material ie heat-treated coal j or carbon material j β = 0.0001247 [(m2mJ)2] Wí: the mixture ratio of coal i or carbon material i Yinter or γρ: the interfacial tension of the coal mixture or coal fines mixture. Mathematics 4

[0016] Yinter OR Yp=0.032θ y2(4) where100ÍV 2 (Σί'=1 / ίΜ / ,·)2= 100 2^-4^ —^Γ] η ί=1 Yi: the surface tension of heat-treated coal i or carbon material i Yij: the interfacial tension at an interface between heat-treated coal i or carbon material ie and heat-treated coal j or carbon material j Wí: the mixture ratio of coal i or carbon material i Petition 870250084110, dated 09 / 18 / 2025, p. 14 / 89 8 / 32 Yinter ου γρ: the interfacial tension of the coal mixture or coal fines mixture Advantageous effects of the invention

[0017] With the present invention, the reduction in the strength of the coke produced can be inhibited even if the coke is produced with a coal mixture in which a carbonaceous material with anomalous surface tension is mixed. Thus, a wide range of different types of coal or carbon materials, including carbonaceous materials with anomalous surface tension that were unusable in the past, become usable as raw materials for coke, and consequently allow for the consistent production of raw materials and the expansion of resources. Brief description of the drawings

[0018] Figure 1 is a graph illustrating a relationship between an interfacial tension ypde of a mixture of coal fines and a coke resistance, considering Invention Examples 1 to 3 and Comparative Examples 2 and 3.

[0019] Figure 2 is a graph illustrating a relationship between the interfacial tension γρ of a mixture of coal fines and an amount of increase in coke strength, considering Invention Examples 4 to 7 and Comparative Examples 5 and 6. Description of the Modalities

[0020] To solve the problem described above, the inventors of the present invention conducted studies that addressed methods for producing coke, which includes the use of formed coal, which is obtained by subjecting coal to a shaping process and which constitutes part of a coal mixture; and the carbonization of the coal mixture, which contains formed coal, powdered coal, which is not formed coal, and a carbon material (hereinafter referred to as coal fines mixture). Patent Literature 1 indicates that, in the case of a Petition 870250084110, dated 09 / 18 / 2025, p. 15 / 89 9 / 32 coal mixture that does not contain formed coal, the coal mixture has a preferred upper limit of interfacial tension. However, the preferred upper limit of interfacial tension may change if formed coal is used, since in formed coals the coal and similar particles are arranged closer to each other than in coal fines and therefore the bonding between the particles is facilitated compared to coal fines.

[0021] The inventors diligently conducted studies and consequently found that the influence of the interfacial tension of the coal included in the formed coal on the strength of the coke is less significant than the influence of the interfacial tension of the coal included in the coal fines. Specifically, the following finding was made. In cases where a coal mixture containing formed coal and a mixture of coal fines is used, and a carbonaceous material with anomalous surface tension is mixed with the formed coal, the interfacial tension of the coal fines mixture has a dominant influence and, as a result, it is possible to inhibit a decrease in the strength of the coke due to the mixture, in the coal mixture, of a carbonaceous material with anomalous surface tension.In other words, even in cases where the interfacial tension of the coal mixture as a whole is high, if a larger quantity of carbonaceous material with anomalous surface tension is mixed with the coal formed, the interfacial tension of the coal fines mixture is reduced, which makes the interfacial tension of the coal fines mixture dominant and, consequently, the decrease in the coke resistance of the coke that is produced by the carbonization of the coal mixture can be inhibited. With this discovery, the present invention has been completed. The present invention will be described in detail below with reference to the embodiments of the present invention.

[0022] The influence of coal surface tension on coke strength is described in detail in Patent Literature 1. The method for Petition 870250084110, dated 09 / 18 / 2025, p. 16 / 89 10 / 32 To produce coke using the present embodiment, first determine the surface tension of a thermally treated product of coal or carbon material included in the coal mixture that serves as feedstock for the coke. The surface tension measurement can be performed using the same method described in Patent Literature 1. The method for measuring the surface tension is summarized below.

[0023] Examples of known methods for measuring the surface tension of coal or carbon materials include sessile drop methods, capillary rise methods, maximum bubble pressure methods, drop weight methods, pendant drop methods, ring methods, Wilhelmy methods, advance / retreat contact angle methods, inclined plate methods, and film flotation methods. Because coal is formed from various molecular structures, the surface tension of coal is expected to be non-uniform. Consequently, it is preferable to use a method that can assess a surface tension distribution, for example, a film flotation method as described in Non-Patent Literature 1. The film flotation method can be used uniformly for coal, carbon materials, and semicoke obtained by carbonization of any of them, and the method can determine a surface tension distribution using a finely divided coal sample.An average value of the surface tension distribution obtained can be used as the surface tension of the coal sample.

[0024] Since the bonding between coal particles occurs in a state where the coal is thermally plasticized during carbonization under heat, it is preferable to use heat-treated (semicok) coal as the coal sample for surface tension measurement. As no method is known for measuring the surface tension of a coal melt at high temperature, the present embodiment measures the surface tension of heat-treated coal or of a material of Petition 870250084110, dated 09 / 18 / 2025, p. 17 / 89 11 / 32 carbon as in the method disclosed in Patent Literature 1.

[0025] Regarding the temperature for the heat treatment of the coal sample, it is preferable that the temperature be within a range of 350°C or more and 800°C or less, which corresponds to the temperatures at which the coal begins to become thermally plasticized and undergoes bonding and solidification until coking is complete. In particular, it is more preferable to use semi-coke that has been heated to a temperature within a range of 350°C or more and 550°C or less, which is a temperature at which the coal becomes thermally plasticized and is therefore a temperature that contributes to bonding. Specifically, it is particularly preferable to use semi-coke that has been heated to a temperature within a range of 480°C or more and 520°C or less.

[0026] Heating of the coal sample is preferably carried out in an inert gas atmosphere that does not react with coal or carbon material, such as nitrogen, argon, or helium. Preferably, the heating rate is selected according to the heating rate for coke production in a coke oven. For example, heating can be carried out at a heating rate of 3°C / min. Furthermore, it is preferable that the sample heated to a target temperature be rapidly cooled at a cooling rate of 10°C / s or higher, so that the molecular structure at the target temperature can be maintained. A preferred method for cooling is cooling in liquid nitrogen.

[0027] With regard to carbon materials, except coal, it is also preferable that the sample for surface tension measurement be previously heat-treated. Note that if the carbon material is an organic compound that has been previously carbonized (torrified) and if the carbonization temperature is higher than the heat treatment temperature of the coal, the surface tension measurement Petition 870250084110, dated 09 / 18 / 2025, page 18 / 89 12 / 32 ciai can be performed without prior heat treatment of the carbon material.

[0028] Now, formed coal will be described. In the method for producing coke of the present embodiment, a portion of the coal mixture that is loaded into a coke oven is formed coal. Formed coal can be formed by a method such as granulation, compression agglomeration, molding, agglomeration, or kneading. Two or more of these methods can be combined to form formed coal. An example of formed coal is briquettes, which are formed as follows: various types of coal and a carbon material are mixed, a binder is added to them if necessary, the mixture is kneaded in a kneading machine, and subsequently, the result is compacted in a double-roll briquetting machine.Examples of binders that can be used include water, coal-based binders (e.g., coal tar pitch, solvent-refined coal, tar, and tar sludge), petroleum-based binders (e.g., asphalt, asphalt pitch, and propane-deasphalted asphalt), and organic binders (e.g., starches, molasses, synthetic polymer compounds, and resins). Preferably, the coal used for formation has particle sizes adjusted by pulverization so that particles with a size of 3 mm or less are present in an amount of 70 to 100% by mass.

[0029] Preferably, the coal formed has an apparent density of 0.8 g / cm3 or higher, more preferably 0.9 g / cm3 or higher, and even more preferably 1.0 g / cm3 or higher. When the coal formed has an increased apparent density, even a carbonaceous material with anomalous surface tension can have better adhesion to the coal and to the carbon material in the vicinity. Consequently, the decrease in the strength of the coke produced can be inhibited. Petition 870250084110, dated 09 / 18 / 2025, page 19 / 89 13 / 32

[0030] Now, the coal fines mixture will be described. Regarding the method for producing coke of the present embodiment, the portion other than coal formed in the coal mixture that is loaded into a coke oven is called the coal fines mixture. The coal that constitutes the coal fines mixture also preferably has particle sizes adjusted by pulverization, so that particles with a size of 3 mm or less are present in an amount of 70 to 100% by mass. Before being loaded into a coke oven, the coal may be conditioned and dried to adjust the amount of water present in it. A carbon material may be added to the coal fines mixture.

[0031] Now, a method for calculating interfacial tension will be described. The method for producing coke of the present embodiment selects compositions of the formed coal and the mixture of coal fines based on the interfacial tension, which is calculated from the surface tensions. The interfacial tension can be calculated based on the method described in Patent Literature 1. The method for measuring the interfacial tension is summarized below.

[0032] It is preferable that the interfacial tension between coal particles be measured directly at an interface between different coal particles; however, such measurement is very difficult with the current technique. Consequently, it is preferable that the method described in Patent Literature 1, which describes an influence on coke resistance, be used for measurement. The interfacial tension between coal particles can be calculated from the surface tensions of the coal or carbon material constituting the coal mixture and its mixing ratio, using equation (1), shown below. Mathematics 5

[0033] Yinter OU Yp = WFW (1) where Petition 870250084110, dated 09 / 18 / 2025, p. 20 / 89 14 / 32 Ku K12 Yij ·'* Yin Y21 Y22 : Kii Yij Yin Ynl '* Ynj ''' Ynn Yij = Yi + Yj - βχρ[-β(Υι - Yj)2]jftYj Yij = Yji VtZ = (wi W2Wf · · · Wn) γ: the surface tension of heat-treated coal i Yij: the interfacial tension at an interface between thermally treated coal i and thermally treated coal j β = 0.0001247 [(m2mJ)2] w,: the mixing ratio of coal i Yinter or γρ: the interfacial tension of the coal mixture or the mixture of coal fines

[0034] Regarding the surface tensions of the various types of heat-treated coal, the various types of heat-treated coal whose surface tensions are used are those that have been heated to the same temperature. A mixing ratio w, of coal i is the ratio between the mass of each of the coal grades (coal i) that is included in the coal mixture and the total mass of the coal mixture. The interfacial tension between two different grades of coal can be calculated using equation (5), shown below. Mathematics 6

[0035] Yij = Yi + Yj - θχρ[-β(γί - Yj)2]% / YiYj (5)

[0036] In equation (5), β is a constant, and the value of β is 0.0001247 [(m2mJ)2], according to Li and Neumann.

[0037] With regard to the mixing ratio, the yield differences between the various types of coal associated with heat treatment can be considered, and the ratios associated with heat treatment can Petition 870250084110, dated 09 / 18 / 2025, p. 21 / 89 15 / 32 to be calculated. However, whether the calculation is based on the mixing ratios in the coal mixture or on the ratios in the heat-treated product makes no significant difference in the selection of the composition. An interfacial tension γρ, which is an interfacial tension of the coal fines mixture (the remaining portion of the coal mixture, excluding the formed coal), can be calculated similarly from equation (1), provided that the marks of the individual coal types that must be present in the coal fines mixture and their mixing ratios have been selected.

[0038] The interfacial tension of the coal mixture can also be calculated from equation (2), shown below. The result of the calculation of equation (1) agrees with the result of the calculation of equation (2), as suggested by Patent Literature 1. Mathematics 7

[0039] Yinter OU γρ=0,032o y2(2) where100ÍV 2 (Xíll / íW,)2=100Z?=1uzí-i[2í''-w'-^l^-] n Zw,=iÍ=1 γ,: the surface tension of the thermally treated coal i Yij: the interfacial tension at an interface between heat-treated coal ieo and heat-treated coal j wa, the mixing ratio of coal i Yinter or γρ: the interfacial tension of the coal mixture or coal fines mixture.

[0040] Furthermore, equation (3) and equation (4), shown below, are equations that consider the carbon material, which are expanded from equation (1) and equation (2) that determine the interfacial tension of a coal mixture. The concept of the calculation by equation (3) and equation (4) is the same as equation (1) and equation (2). Petition 870250084110, dated 09 / 18 / 2025, page 22 / 89 16 / 32 (2). The interfacial tension of a coal mixture containing a carbon material can be calculated using equation (3) and equation (4). Mathematics 8

[0041] YinterOU Yp= wrwqs) where All Y12 -· Ylj ·· / 1)1 K21 Y22 : Hl Yij Yin Xnl......Ynj * Ynn Ylj = Yi + Yj - βχρ[~β(Υι - Yj)2]y / YíYj Ylj = Yji W = (Wi W2' ' · W( * · · wn) n ZW'= 1t=l Yi: the surface tension of heat-treated coal i or carbon material i Yij: the interfacial tension at an interface between heat-treated coal i or carbon material ie heat-treated coal j or carbon material j β = 0.0001247 [(m2mJ)2] Wí: the mixture ratio of coal i or carbon material i Yinter or γρ: the interfacial tension of the coal mixture or coal fines mixture. Mathematics 9 Yinter OR Yp=0.032θ y2(4) where100ÍV 2 (ΣίΙΐ / ίΜ / ,)2n I=1 Yi: the surface tension of heat-treated coal i or Petition 870250084110, dated 09 / 18 / 2025, p. 23 / 89 17 / 32 carbon material i Yij: the interfacial tension at an interface between heat-treated coal i or carbon material ie and heat-treated coal j or carbon material j Wí: the coal mixture ratio i or carbon material i Yinter or γρ: the interfacial tension of the coal mixture or coal fines mixture

[0042] Now, a method for selecting compositions of formed coal and coal fines mixture will be described. The method for producing coke of the present embodiment selects compositions of formed coal and coal fines mixture such that the interfacial tension γρ of the coal fines mixture is less than the interfacial tension Yinter of the total coal mixture, and that the interfacial tension γρ of the coal fines mixture is less than 0.03. As used herein, the term composition refers to the grade and mixing ratio of the coal that is included and to the type and mixing ratio of the carbon material that is included.

[0043] Note that if the temperature for the heat treatment of coal is changed, the surface tension of the heat-treated coal changes; however, the trend of change is the same regardless of the coal brand, i.e., the value of the interfacial tension between different types of coal does not change substantially, as disclosed in Patent Literature 1. Consequently, a suitable range of the interfacial tension γρ of the coal fines mixture can be determined independently of the temperature for the heat treatment of the coal.

[0044] The mixing ratio of a brand of coal in the coal mixture is the sum of values, where one of the values ​​is the product of the mixing ratio of the coal formed in the coal mixture multiplied by the mixing ratio of the brand of coal in the coal formed, and the other is the Petition 870250084110, dated 09 / 18 / 2025, p. 24 / 89 18 / 32 is the product of the mixing ratio of the coal fines mixture in the coal mixture multiplied by the mixing ratio of the coal grade in the coal fines mixture. Thus, for example, the selection of a coal mixture composition and the selection of a mixing ratio of the coal formed in the coal mixture and the mixing ratios of the coal grades in the formed coal determine the mixing ratios of the coal fines mixture.

[0045] The inventors discovered that the influence of the interfacial tension of the formed coal on the strength of the coke is less significant than the influence of the interfacial tension of the coal fines mixture and that, in a case where a carbonaceous material with anomalous surface tension is mixed with the formed coal, the influence of the interfacial tension of the coal fines mixture is dominant. Thus, a decrease in the strength of the coke produced can be inhibited to a greater degree when the coal mixture used is one with a composition in which the formed coal and the coal fines mixture have different compositions, so that the interfacial tension of the coal fines mixture can be lower than the interfacial tension of the coal mixture, than when the coal mixture used is one in which the formed coal and the coal fines mixture have the same composition.

[0046] That is, it is preferable to select a composition in which the formed coal and the coal fines mixture have different compositions, so that the interfacial tension of the coal fines mixture can be reduced, rather than selecting the same composition for the formed coal and the coal fines mixture. This technical concept can be expressed as an inequality: Yinter > γP. Yinter > γP indicates that it is appropriate to apply the present invention to a coal mixture with a high Yinter, which tends to cause a decrease in the strength of the coke. Petition 870250084110, dated 09 / 18 / 2025, p. 25 / 89 19 / 32

[0047] Furthermore, according to a suggestion from Patent Literature 1, if the interfacial tension Yinterda coal mixture, calculated by equation (1) or equation (2), is 0.03 or higher, a decrease in coke strength may occur. Consequently, by selecting a composition in which coal with anomalous surface tension is included in the coal formed in the coal mixture, such that the interfacial tension ypda coal fines mixture, which influences coke strength, is less than 0.03, it is possible to inhibit a decrease in coke strength and thus improve coke strength to a greater degree than when the coal formed and the coal fines mixture have the same coal mixing ratio with anomalous surface tension.

[0048] It is preferable that the ratio of formed coal to the total coal mixture be within a range of 10% by mass or more and 50% by mass or less. If the formed coal content is less than 10% by mass in the total coal mixture, the effect of expanding the range of usable coal resources is reduced, and therefore such a content is not preferred. If the formed coal content is greater than 50% by mass in the total coal mixture, the cost of forming coal increases, and therefore such a content is not preferred. It is even more preferable that the formed coal mixing ratio be within a range of 15% by mass or more and 40% by mass or less in the total coal mixture.

[0049] Regarding the composition of formed coal, if the fluidity of the formed coal feedstocks is excessively low, many defects may form in the coke-derived portion of the formed coal, and therefore such a composition may not be preferable. Regarding the lower limit of the fluidity of the formed coal feedstocks, although the lower limit varies depending on the amount of mixture of formed coal and the types of coal and carbon material. Petition 870250084110, dated 09 / 18 / 2025, p. 26 / 89 20 / 32 used in formed coal, it is preferable that an average log MF be 1.4 or higher, where the average log MF is determined based on the common logarithms of the Gieseler Fluidity MF of the various types of coal and carbon material that are included in the formed coal and the contents of the various types of coal and carbon material in the formed coal.

[0050] Finally, the carbonization of the coal mixture will be described. The coal mixture, which is prepared by mixing the formed coal with the mixture of coal fines, is loaded into a coke oven and carbonized to produce coke. The carbonization of the coal mixture can be carried out using a common chamber coke oven, and performing carbonization at a temperature of approximately 900°C or higher. EXAMPLES

[0051] Now, Examples will be described in which coke was produced using the method for producing coke of the present embodiment. Table 1 shows the properties of various types of coal and a carbon material that were used in the Examples. Table 1 Mark Ro (%) Log MF (log [ddpm]) Y (mN / m) A 0.71 2.05 43.5 B 1.00 1.63 41.6 C 1.30 1.58 40.4 D 1.52 1.55 39.7 E 1.10 3.15 39.7 F 1.18 2.89 40.6 G 1.24 1.71 40.2 H 1.51 0.48 39.8 1 - - 43.7

[0052] In Table 1 above, A to H are coal, and I is biomass. Petition 870250084110, dated 09 / 18 / 2025, p. 27 / 89 21 / 32 (palm kernel shell) carbonized at 500°C. Among these, coal A and carbon material I exhibit a surface tension γ greater than the average surface tension of the total coal mixture and, therefore, in this composition, coal A and carbon material I can be considered carbonaceous materials with anomalous surface tension.

[0053] Ro is the maximum average reflectance of coal vitrinite, measured according to JIS M 8816:1992. log MF is the common logarithm of the maximum Gieseler flowability of coal, measured according to J IS M 8801:2008. The maximum flowability MF of I was 0 ddpm. γ is the surface tension of the coal or carbon material, which was heat-treated at 500°C, and is an average value of a surface tension distribution determined by the film flotation method described in Patent Literature 1.

[0054] A coal mixture containing formed coal and a mixture of coal fines was prepared with the coal grades listed in Table 1. Each of the coal grades was pulverized so that particles with a size of 3 mm or less were present in an amount of 100% by mass. The formed coal was briquettes with a volume of 34 cm3, which were produced as follows: tar pitch and tar slurry were added as binders in amounts of 4.0 parts and 6.5 parts, respectively, per 100 parts of the formed coal raw materials, and these materials were mixed and subsequently briquetted in a double-roll briquetting machine.

[0055] A mixture of fine coal, which had not been subjected to any shaping process, was mixed with the briquettes, and thus the coal mixture was prepared. The coal mixture was loaded into a carbonization vessel so that its apparent density could be 870 kg / m3 and was then carbonized for 6 hours in an electric arc furnace with a furnace wall temperature of Petition 870250084110, dated 09 / 18 / 2025, page 28 / 89 22 / 32 1050°C. Subsequently, the resulting mixture was cooled under nitrogen to produce coke. Table 2 below shows the coal composition (% by mass based on the total mass of the coal mixture), the interfacial tension of the coal formed or the coal fines mixture, the average log MF, and the coke strength Dl (150 / 15) of the coke produced. Interfacial tension is a value calculated from the surface tensions and mixing ratios of the coal marks using equation (2). The average log MF is a value calculated by the weighted average of the log MFs of the coal marks with the mixing ratios of the coal marks. Coke strength is a drum strength index Dl (150 / 15) measured by a tipping strength test method specified in JIS K 2151:2004. Petition 870250084110, dated 09 / 18 / 2025, page 29 / 89 23 / 32 Table 2 Example of Invention 2 Mixture of fine coal oo~ 15.0 oo~ 15.0 o 14.5 11.5 10.0 0.016 1.81 83.2 Coal Formed 15.0 oo~ 15.0 ooooooooooo 00 oo 1.82 Example of Invention 1 Mixture of fine coal oo~ oo~ 15.0 15.0 o 14.5 11.5 10.0 0.004 1.80 83.3 Coal Formed 15.0 15.0 oo' ooooooooooo CO oo 1.84 Comparative Example 1 of the same Composition 15.0 15.0 15.0 15.0 o 14.5 11.5 10.0 0.051 1.81 82.9 Brand m OQ 111 0 ΞE Interfacial tension (mN / m) Log MF (log [ddpm]) Dl (150 / 15) Petition 870250084110, dated 09 / 18 / 2025, page 30 / 89 24 / 32 Table 2 --continued Comparative Example 3 Mixture of coal fines 10.0 oo~ 5.0 15.0 o 14.5 11.5 10.0 0.050 1.87 81.9 Formed Coal 5.0 15.0 10.0 oo~ oooooooo 0.036 1.68 Comparative Example 2 Mixture of coal fines 5.0 10.0 oo~ 15.0 o 14.5 11.5 10.0 0.035 1.84 82.6 Formed Coal 10.0 o LO 15.0 oo' oooooooo 0.064 1.75 Example of the Invention 3 Mixture of coal fines oo~ O LO o LO 15.0 o 14.5 11.5 10.0 0.009 1.82 83.2 Charcoal Formed 15.0 10.0 10.0 oooooooooo 0.057 1.80 Mark mo Q 111 0 ΞE� Interfacial tension (mN / m) Log MF (log [ddpm]) Dl (150 / 15) Petition 870250084110, dated 09 / 18 / 2025, page 31 / 89 25 / 32

[0056] Comparative Example 1 is an example where the formed coal and the coal fines mixture had the same composition. Consequently, the interfacial tension in this example was the Yinter interfacial tension of the coal mixture. In Invention Examples 1 to 3 and Comparative Examples 2 and 3, the formed coal and the coal fines mixture had different compositions. The average interfacial tension and log MF values ​​are shown for each of the compositions. The mixing ratio of the formed coal in the coal mixture, which was the sum of the mixing ratios of the coal grades included in the formed coal, was adjusted to lie within a range of 30% by mass or more and 35% by mass or less. In the case of the same composition as Comparative Example 1, the mixing ratio of the formed coal was 30% by mass.

[0057] Figure 1 is a graph illustrating the relationship between the interfacial tension γρ of the coal fines mixture and the coke strength, considering Examples of the Invention 1 to 3 and Comparative Examples 2 and 3. In Figure 1, the horizontal axis represents the interfacial tension YP (mN / m) of the coal fines mixture, and the vertical axis represents the coke strength Dl (150 / 15) (-). (-) indicates dimensionlessness. The dashed line in Figure 1 represents the coke strength of Comparative Example 1.

[0058] As shown in Figure 1 and Table 2, the coke strength of the coke produced in Examples of the Invention 1 to 3, which satisfied Yinter > γP and γρ < 0.03, was greater than the coke strength of the coke produced in Comparative Example 1, in which the formed coal and the coal fines mixture had the same composition. It was anticipated that, in the case where the formed coal and the coal fines mixture had different compositions, problems could arise not only with the interfacial tension of the coal fines mixture, but also with the bonding within the formed coal and in the Petition 870250084110, dated 09 / 18 / 2025, p. 32 / 89 26 / 32 boundary portions between the formed coal and the coal fines mixture. The results shown in Figure 1 and Table 2, however, confirm that the strength of the coke produced is predominantly affected by the interfacial tension γρ of the coal fines mixture, regardless of the interfacial tension of the coal formed in the coal mixture. Furthermore, Figure 1 confirms that, under conditions where the interfacial tension γρ of the coal fines mixture is less than 0.03 mN / m, it is possible to achieve a coke strength comparable to or greater than that of the example (Comparative Example 1) where the same composition is employed.

[0059] Furthermore, the results indicate that, under conditions where the same composition (in terms of brands or types of coal and carbon material used and their mixing ratios) is used in the total coal mixture, it is possible to obtain coke with high strength by selecting compositions of the formed coal and the coal fines mixture such that Yinter > γP and γρ < 0.03 are satisfied. One way to select compositions of the formed coal and the coal fines mixture is, for example, as follows. A composition of the total coal mixture is first selected, and then compositions of the formed coal and the coal fines mixture are selected without altering the composition of the total coal mixture.In this case, by selecting a composition in which a larger quantity of a carbonaceous material with an anomalous surface tension is included in the briquettes, the γρ of the coal fines mixture can be reduced and, consequently, the composition can satisfy Yinter > γρ β γρ < 0.03.

[0060] Examples of the Invention 4 to 7 are examples in which coke was produced with a coal mixture containing coal marks and a carbon material. The conditions, apart from the composition, were the same as in Examples of the Invention 1 to 3. The carbon material used was a biomass carbonized at 500°C. The properties of... Petition 870250084110, dated 09 / 18 / 2025, p. 33 / 89 27 / 32 biomass are shown in Mark I in Table 1. With respect to Examples of the Invention 4 to 7, Tables 3 and 4 below show their composition, the interfacial tension of the coal formed or the mixture of coal fines, the average log MF, the coke strength Dl (150 / 15) of the coke that was produced and the amount of increase ÕDI (150 / 15) in the coke strength. Petition 870250084110, dated 09 / 18 / 2025, page 34 / 89 28 / 32 Table 3 Example of the Invention 4 Coal fines mixture ooooo ui X— o ui X— O 14.5 11.5 oo Cü E ω Φ o > ro Cü CL E o O o CL E Φ X o CM o ui o ui o ui o_ LO LO X— oo o_ CM LO O LO CM~ LL X— X— X— Ct C α mo Q LU 0 TE z E rç Ό Cü t φ co >CÜ ω c Φ E CL Ό 70, CD O CD O —1 LO X— o LO X— Q u? X— o LO X— Q <1 Petition 870250084110, dated 09 / 18 / 2025, page 35 / 89 29 / 32 Table 3 -continued- Comparative Example 6 Mixture of coal fines 9.0 o ui Έ— 1.0 5.0 o 14.5 11.5 oo Έ— oo 0.047 1.87 Έ— CO o — Coal Formed o CO ooo Έ— oo Έ— ooooooooo CO 0.068 1.46 Comparative Example 5 Mixture of coal fines o ui oo Έ— oooo Έ— o 14.5 11.5 oo Έ— oo 0.036 98'l· 82.5 CN O Coal Formed oo in o ui Έ— o in ooooooooo có 0.072 1.54 Example of the Invention 5 Mixture of coal fines ooo ui Έ— ooo ui Έ— o 14.5 11.5 oo Έ— oo 0.016 Έ— 00 Έ— 83.0 CO o Charcoal Formed 12.0 ooo ui Έ— oooooooooo CO CN CO OO 1.61 Mark mo Q LU 0 T Interfacial tension (mN / m) Log MF (log [ddpm]) Dl (150 / 15) Δ Dl (150 / 15) Petition 870250084110, dated 09 / 18 / 2025, page 36 / 89 30 / 32 Table 4 Example of Invention 7 Mixture of coal fines oo' 15.0 oo' 15.0 o 14.5 11.5 10.0 O θ' 0.016 1.81 83.1 g'o Coal Formed 10.0 oo' 15.0 oo' oo' oo' oo' oo' 5.0 CO 00 oo' 1.47 Example of Invention 6 Mixture of coal fines oo' oo' 15.0 15.0 o 14.5 11.5 10.0 oo' 0.004 1.80 CO co' 00 o' Coal Formed 10.0 15.0 oo' oo' oo' oo' oo' oo' o LO 0.032 1.50 Comparative Example 7 of the Same Composition 10.0 15.0 15.0 15.0 o 14.5 11.5 10.0 o LO 0.053 1.71 82.6 Brand m OQ 111 0 ΞΕ Interfacial tension (mN / m) Log MF (log [ddpm]) Dl (150 / 15) Δ Dl (150 / 15) Petition 870250084110, dated 09 / 18 / 2025, page 37 / 89 31 / 32

[0061] Examples of the Invention 4 and 5 and Comparative Examples 4 to 6 are examples of production in which coke was produced with a coal mixture containing carbon I material mixed in at a mass percentage of 3%. Examples of the Invention 6 and 7 and Comparative Example 7 are examples of production in which coke was produced with a coal mixture containing carbon I material mixed in at a mass percentage of 5%. Comparative Examples 4 and 7 are examples in which the coal formed and the coal fines mixture had the same composition. The interfacial tensions of Comparative Examples 4 and 7 were the interfacial tension Yinter of the coal mixture. Comparative Examples 4 and 7 had different coke strengths from the coke that was produced, and the ΔI / D values ​​of the corresponding Examples of the Invention and Comparative Examples are shown. ΔI / D is the amount of increase in coke strength.In Table 3, ÕDI is the value obtained by subtracting the coke strength of Comparative Example 4 from the coke strength of Example of the Invention 4 or 5 or Comparative Example 5 or 6. In Table 4, ÕDI is the value obtained by subtracting the coke strength of Comparative Example 7 from the coke strength of Example of the Invention 6 or 7. The average log MF in Tables 3 and 4 was an average value calculated assuming that the log MF of carbon material I is zero.

[0062] Figure 2 is a graph illustrating the relationship between the interfacial tension γρ of the coal fines mixture and the increase in coke strength, considering Examples of the Invention 4 to 7 and Comparative Examples 5 and 6. In the graph of Figure 2, the horizontal axis represents the interfacial tension γρ(mN / m) of the coal fines mixture, and the vertical axis represents the amount of increase ÕDI (150 / 15) in coke strength. In Figure 2, the black circles indicate the results from Table 3, and the white circles indicate the results from Table 4.

[0063] As shown in Figure 2, it was observed that the resistance Petition 870250084110, dated 09 / 18 / 2025, page 38 / 89 32 / 32 The coke strength tended to decrease with increasing γρ. It was also observed that the coke strength decreased significantly when Yp was 0.03 or higher. These results confirm that, even if the composition is one that can increase the interfacial tension of the coal mixture in the case where it includes, in the coal mixture, a carbonaceous material with anomalous surface tension (coal A and carbon I material), which is difficult to use as a typical material for coke, it is possible to inhibit a decrease in the strength of the coke produced and, therefore, achieve the production of high-strength coke, using coal formed in a portion of the coal mixture and selecting a composition such that Yinter > γρ and γρ < 0.03 are satisfied.

[0064] These results confirm that, even in cases where coke is produced with a coal mixture in which a carbonaceous material with anomalous surface tension is mixed, it is possible to inhibit the decrease in the strength of the coke produced and, therefore, achieve the production of high-strength coke by selecting a composition such that Yinter > γP and γρ < 0.03 are satisfied. Therefore, a wide range of various types of coal or carbon materials, including carbonaceous materials with anomalous surface tension that were unusable in the past, become usable as raw materials for coke, and consequently, consistent raw material acquisition and resource expansion can be achieved. Petition 870250084110, dated 09 / 18 / 2025, page 39 / 89

Claims

1 / 4 CLAIMS 1.Method for producing coke, characterized in that it comprises producing coke by carbonizing a coal mixture obtained by mixing formed coal with a mixture of coal fines, the formed coal comprising coal marks, the coal fines mixture comprising powdered coal marks, wherein the method comprises selecting marks and mixing ratios of coal that is included in the formed coal and of coal that is included in the coal fines mixture, such that an interfacial tension Yinter of the coal mixture and an interfacial tension γρ of the coal fines mixture satisfy Yinter > Yp © Yp < 0.03 where the interfacial tension Yinter and the interfacial tension γρ are calculated from the surface tensions of the heat-treated coal, obtained by heat-treating the coal marks that are included in the coal mixture and the mixing ratios of the coal marks, using equation (1) or equation (2), shown below.Mathematics 1 Yinter OR YP = WrW*(1) where Kn / 12 Yij Km ' F21 Y22 : Kii Yij Yin Yij = Yi + Yj - exp[-p(yt - Yj)2]^ / nYj Yij = Yji VtZ = (wí W2 W( · - - Wn) Yí: the surface tension of the thermally treated coal i Petition 870250084110, of 09 / 18 / 2025, page 40 / 89 2 / 4 Yij: the interfacial tension at an interface between thermally treated coal i and thermally treated coal j β = 0.0001247 [(m2 mJ)2] Wí: the mixing ratio of coal i Yinter or γρ: the interfacial tension of the coal mixture or the mixture of coal fines Mathematics 2 Yinter OR Yp = 0.032ο1 γ2 (2) where 2 100 ÍV 2 (Xíll / íW,)2=100Z?=1uzí-i[2í''-w'-^l^-] n Σ^ = 1 í=l Yí: the surface tension of the thermally treated coal i Yif the interfacial tension at an interface between the thermally treated coal ieo thermally treated coal j Wí: the mixing ratio of the coal i Yinter or γρ: the interfacial tension of the coal mixture or the mixture of coal fines.

2. Method for producing coke, according to claim 1, characterized in that at least one of the formed coal and the coal fines mixture comprises a carbon material, wherein the method comprises selecting grades and mixing ratios of coal that is included in the formed coal and of coal that is included in the coal fines mixture and selecting a type and mixing ratio of the carbon material that is included in the formed coal and of the carbon material that is included in the coal fines mixture, such that the interfacial tension Yinter of the coal mixture and the interfacial tension γρ of the coal fines mixture satisfy Yinter > Yp θ Yp < 0.03 Petition 870250084110, dated 09 / 18 / 2025, p.41 / 89 3 / 4 where the interfacial tension Yinter and the interfacial tension γρ are calculated from the surface tensions of the heat-treated coal and the carbon material, the heat-treated coal being obtained by heat treatment of the coal marks that are included in the coal mixture; and the mixing ratios of the coal marks and the carbon material, using equation (3) or equation (4), shown below, instead of equation (1) or equation (2). Mathematics 3 Yinter OR YP= WFW* (3) where / 11 K21 K12 ·-· Yij · Km Y22 : Yij Yin ......Ynj * Ynn Yij = Yí + Yj - βχρ[-β(Yί - Yjy]jYíYj Yij = Yji W = (Wi W2 ' ' ' W( * · · wn) n Yí: the surface tension of thermally treated coal i or carbon material i Yij: the interfacial tension at an interface between thermally treated coal i or carbon material i thermally treated coal j or carbon material j β = 0.0001247 [(m2 mJ)2] Wí: the mixing ratio of coal i or carbon material i Yinter or γρ: the interfacial tension of the coal mixture or the mixture of coal fines Mathematics 4 Yinter OR γρ= 0.032θ γ2 (4) where Petition 870250084110, of 18 / 09 / 2025, p.42 / 89 4 / 4 2 100 ÍV 2 (Z'LlXiVV,)2 n Σ^=ι Í=1 Yí: the surface tension of heat-treated coal i or carbon material i Yij: the interfacial tension at an interface between heat-treated coal i or carbon material i heat-treated coal j or carbon material j Wí: the mixing ratio of coal i or carbon material i Yinter or γρ: the interfacial tension of the coal mixture or the mixture of coal fines. Petition 870250084110, dated 18 / 09 / 2025, p. 43 / 89.

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