JP7701604B2 - Method for evaluating binder and method for producing coke - Google Patents

Description

The present invention relates to a method for evaluating a binder and a method for producing coke.

Coke is produced, for example, by carbonizing the coal material, which is the raw material for coke, in a coke oven. The coal material charged into the coke oven may be a single type, or it may be a blend of multiple types of coal material. When the coal material charged into the coke oven is heated to a certain temperature range (for example, about 300 to 550°C), it softens and melts, and then foams and expands as volatile matter is generated. This foaming and expansion causes the individual coal particles to bond together (in other words, the gaps between the coal particles are blocked), forming a lump of semi-coke. The semi-coke is further heated to around 1000°C to be sintered and become a robust coke.

Here, in the process of producing semi-coke, the lower the softening temperature of the coal material, the more coal particles will soften and melt, and the more coal particles will foam and expand. As a result, more voids are blocked, and a stronger coke is produced.

In order to lower the softening and melting temperature of coal materials, a mixture (blended coal) of coal materials and binders may be added to the coke oven. Examples of binders include tar pitch, petroleum pitch, solvent refined coal, and solvent extracted coal.

JP 2015-199791 A JP 2012-72390 A International Publication No. 2011/004495

Shinohara et al., "Evaluation of coal swelling by adding organic compounds using molecular dynamics simulation," Abstracts of the 56th Coal Science Conference, Vol. 2-10 Hata et al., "Construction of a molecular structure model of coal," Abstracts of the 28th Japan Society of Energy, Vol. 1-4-1

One of the properties required of a binder is the ability to improve expansion, which allows more coal particles to foam and expand. A binder with a high expansion improvement effect can foam and expand more coal particles by lowering the softening and melting temperature of the coal material. There is compatibility between binders and coal materials, and just because binder A has a high expansion improvement effect on a certain coal material A, it does not necessarily mean that binder A will also have a high expansion improvement effect on another coal material B.

For this reason, there has been a strong demand for a method for appropriately and simply evaluating the expansion-improving effect of a binder, but no such method has been proposed so far. For example, Patent Documents 1 to 3 and Non-Patent Documents 1 and 2 disclose technologies related to coke production. In summary, Patent Document 1 discloses a technology for blending caking coal and non-slightly caking coal. Patent Document 2 discloses a technology for evaluating the softening and melting characteristics (expansion-improving effect) of a binder in a state simulating the surrounding environment of the softened and melted coal material and the binder in a coke oven. Patent Document 3 discloses a binder that includes a matrix phase containing an aromatic compound having a hydrogen-donating naphthene group and carbon particles dispersed in the matrix phase.

Non-Patent Document 1 discloses that there is a positive correlation between the calculated density of a coal blend containing different types of binders and the maximum expansion rate of the coal blend. Non-Patent Document 2 discloses a three-dimensional molecular aggregation model that can qualitatively express the thermal relaxation behavior of two types of coal.

However, none of these techniques were able to adequately evaluate the expansion-improving effect of the binder. Patent Documents 1 and 3, and Non-Patent Document 2 make no mention of the expansion-improving effect of the binder. Patent Document 2 evaluates the expansion-improving effect of the binder using a parameter called the permeation distance, but in order to calculate the permeation distance, it is necessary to measure the Gieseler maximum fluidity, which is very time-consuming. Non-Patent Document 1 discloses that there is a positive correlation between the calculated density of the coal blend and the maximum expansion rate of the coal blend, but this correlation does not exist for all binders.

Other evaluation methods are known, such as using a Gieseler plastometer to measure the fluidity of a coal blend, or using a dilatometer to measure the expansion rate of a coal blend, but both of these require a great deal of work.

The present invention has been made in consideration of the above problems, and the object of the present invention is to provide a method for evaluating a binder and a method for producing coke that appropriately and simply evaluates the expansion-improving effect of the binder.

In order to solve the above problems, according to one aspect of the present invention, a binder evaluation method is provided, which includes a glass transition point acquisition step of determining the glass transition point of a coal material that is a raw material for coke, and further determining the glass transition points of mixtures of the coal material and a binder to be mixed with the coal material for multiple types of binders, and an evaluation step of evaluating the expansion improvement effect of each binder on the coal material based on the glass transition point of the coal material and the glass transition points of the mixtures obtained for each binder.

According to another aspect of the present invention, a method for evaluating a binder is provided, which includes a glass transition point acquisition step of acquiring the glass transition point of a coal material that is a raw material for coke, and further acquiring the glass transition point of a mixture of the coal material and a binder to be mixed with the coal material, and an evaluation step of evaluating the effect of the binder in improving the expansion of the coal material based on the glass transition point of the coal material and the glass transition point of the mixture.

Here, in the evaluation process, the smaller the glass transition temperature obtained for each binder is relative to the glass transition temperature of the coal material, the greater the expansion improvement effect of the binder may be evaluated.

In addition, when the glass transition temperature obtained for each binder is 15°C or more lower than the glass transition temperature of the coal material, the binder may be evaluated as having a large effect of improving expansion properties.

Here, in the glass transition point acquisition process, a molecular model of the coal material is constructed by modeling the molecules that make up the coal material, and a molecular model of the binder is constructed by modeling the molecules that make up the binder. The specific volume of a mixed model of the molecular model of the coal material and the molecular model of the binder is calculated at multiple temperatures using a molecular dynamics calculation method, and the glass transition point of the mixture is calculated based on a correlation graph between the specific volume of the mixed model and temperature.

In addition, in the glass transition point acquisition process, a molecular model of the coal material may be constructed by modeling the molecules that make up the coal material, the specific volume of the molecular model of the coal material may be calculated at multiple temperatures using a molecular dynamics calculation method, and the glass transition point of the coal material may be calculated based on a correlation graph between the specific volume of the molecular model of the coal material and temperature.

The coal material may also be hard coking coal or non- or slightly hard coking coal.

According to another aspect of the present invention, a method for producing coke is provided, which is characterized in that a binder to be added to a coal material is determined based on the above-mentioned binder evaluation method, and coke is produced using the determined binder and the coal material.

According to the above-mentioned aspects of the present invention, the expansion improving effect of the binder can be appropriately and simply evaluated.

1 is a structural formula showing the average molecular structure of the second component AS. 1 is a structural formula showing the average molecular structure of the third component, PS. 1 is a structural formula showing the average molecular structure of the fourth component PI. 1 is a structural formula showing the average molecular structure of the fifth component MI. (a) A schematic diagram showing the molecular structure of coronene, a type of binder. The upper figure is a plan view, and the lower figure is a side view. (b) A schematic diagram showing the molecular structure of corannulene, a type of binder. The upper figure is a plan view, and the lower figure is a side view. FIG. 2 is an explanatory diagram showing the behavior of a mixed model A of a molecular model of a coal material and a molecular model of coronene in three dimensions. FIG. 1 is an explanatory diagram showing the behavior of a mixed model B of a molecular model of a coal material and a molecular model of corannulene in three dimensions. FIG. 2 is an explanatory diagram showing the behavior of a molecular model of a coal material in three dimensions. 1 is a graph showing the correlation between specific volume and temperature of a molecular model of a coal material. 13 is a graph showing the correlation between specific volume and temperature for mixture model A. 13 is a graph showing the correlation between specific volume and temperature for mixed model B. FIG. 1 is a conceptual diagram illustrating an example of a modeling measurement method. 1 is a flowchart illustrating an example of a modeling measurement method. FIG. 1 is a structural formula showing the average molecular structure of the second component AS, the third component PS, and the fifth component MI of coal II. FIG. 1 shows the molecular structures of (a) coronene, (b) pyrene, (c) anthracene, and (d) naphthalene, which are types of binders. 1 is a graph showing the glass transition temperature when various binder model molecules are added to coal II (non- or slightly caking coal). 1 is a graph showing the total expansion rate when various binder molecules are added to coal II (non- or slightly caking coal) (values are set at 100% for coal alone).

The preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. The inventor has intensively studied a method for evaluating a binder that appropriately and simply evaluates the expansion-improving effect of the binder. The inventor has focused on the glass transition point of a mixture of coal material, which is the raw material for coke, and a binder mixed with the coal material. As a result, the inventor has found that the expansion-improving effect of the binder can be evaluated by comparing the glass transition point of the mixture with the glass transition point of the coal material. In general, if the glass transition point of the mixture is lower than the glass transition point of the coal material, the expansion-improving effect of the binder contained in the mixture is high. The present embodiment will be described in detail below.

1. Overview of evaluation method
First, an overview of the binder evaluation method according to the present embodiment will be described. The binder evaluation method according to the present embodiment includes a glass transition temperature acquisition step and an evaluation step. In the glass transition temperature acquisition step, the glass transition temperatures of mixtures of coal material, which is a raw material for coke, and binders to be mixed with the coal material are acquired for a plurality of types of binders. In the evaluation step, the expansion improvement effect of each binder on the coal material is evaluated based on the glass transition temperature of the mixture obtained for each binder. Note that the expansion improvement effect in this embodiment is evaluated by, for example, the maximum expansion coefficient defined in JIS M 8801 2008. The larger the maximum expansion coefficient, the greater the expansion improvement effect. In this embodiment, the expansion improvement effect can be evaluated without performing a test according to JIS M 8813. Each step will be described in detail below.

<1-1. Glass transition temperature obtaining process>
As described above, in the glass transition temperature acquisition step, the glass transition temperatures of the mixture of the coal material as the raw material of the coke and the binder to be mixed with the coal material are acquired for a plurality of types of binder. Here, the coal material and the binder to be the subject of the binder evaluation method according to the present embodiment are not particularly limited, and include all of those that can be used for coke production or that may be used in the future.

For example, the coal material according to this embodiment includes all coals known as raw coal. Raw coal is coal that is the raw material for coke, and examples of such coal include caking coal (such as bituminous coal) and non- or slightly caking coal. The coal material may be a single type, or may be a blended coal obtained by mixing (blending) multiple types of coal materials from different places of origin, etc.

The type of binder is not particularly limited. Examples of binders include tar pitch, petroleum pitch, solvent refined charcoal, and solvent extracted charcoal. A binder made of a single type of carbonaceous material (e.g., coronene, corannulene, etc.) may also be used. Such carbonaceous materials may be obtained, for example, by subjecting existing tar pitch, etc., to the above-mentioned solvent extraction, or may be newly synthesized.

Specific methods for obtaining the glass transition point include a method of obtaining the glass transition point by modeling the coal material and binder, and a method of measuring the glass transition point using DSC (differential scanning calorimetry). Here, we will explain in detail the method of obtaining the glass transition point by modeling the coal material and binder (hereinafter also referred to as the "modeling method").

Here, we will explain the advantages of the modeling method and why the inventors focused on the glass transition point as an index for evaluating the expansion improvement effect.

Coal materials, whether they are a single type or a blend of multiple types of coal, are often composed of multiple types of molecules with significantly different molecular weights. The inventor believes that among these molecules, molecules with relatively low molecular weights soften and melt from low temperatures, and as they melt components with larger molecular weights one after another, they expand the softening and melting region, thereby exhibiting expansive properties, and that softening and melting is promoted by starting softening and melting at a lower temperature, thereby improving expansive properties. Therefore, the inventor believes that softening and melting is promoted and expansive properties are improved by the glass transition temperature, which is the temperature at which the aggregated structure of coal molecules relaxes, occurring at a low temperature.

As mentioned above, when the coal material charged into the coke oven is heated to a certain temperature range (for example, about 300 to 550°C), it softens and melts, and then foams and expands as volatile matter is generated. This foaming and expansion causes the individual coal particles to bond together, blocking the voids between the coal particles and producing a robust coke. Therefore, in order to increase the strength of the coke, it is important to soften and melt as much coal material as possible. Here, the softening and melting of the coal material occurs when the interactions between the molecules that make up the coal material (mutually attractive interactions, such as van der Waals forces (intermolecular forces) and electrostatic interactions) weaken, allowing the molecules to move freely around each other.

Although the details will be described later, in the modeling measurement method, a molecular model of the coal material is constructed by modeling the molecules that constitute the coal material. In summary, the coal material is extracted with multiple types of solvents to extract multiple types of molecules from the coal material, and the molecules in each solvent are modeled. Then, the molecular models are mixed according to their mass ratio to construct a molecular model of the coal material. At this time, the molecular model of the coal material is necessarily included in the molecular model of the coal material. In the modeling measurement method, the glass transition point of the coal material (or the mixture of the coal material and the binder) is obtained taking into account the molecular model of the low molecular weight. Furthermore, the lower the glass transition point, the weaker the interaction between the molecules that constitute the coal material will be at a lower temperature, so that the softening and melting of the coal material will begin at a lower temperature, and a stronger coke will be produced. For this reason, the inventor decided to focus on the glass transition point.

On the other hand, in the method of measuring the glass transition point using DSC (differential scanning calorimetry), the glass transition point of the coal material (or a mixture of the coal material and the binder in a desired mixing ratio) is directly measured. However, in DSC measurements, the endothermic peak due to gas generation may overlap with the endothermic peak due to thermal expansion, making it difficult to calculate the glass transition point.

In the modeling measurement method, a molecular model of the coal material is constructed by modeling the components that make up the coal material. The specific details of the modeling measurement method are described below with reference to Figures 12 and 13. Figure 12 is a conceptual diagram, and Figure 13 is a flow chart. Specifically, first, the coal material is prepared. It is preferable to thoroughly crush the coal material in advance. This is to make it easier to dissolve the soluble components in each solvent in each solvent. Next, the coal material is extracted with multiple types of solvents to extract multiple types of components from the coal material.

First, in step S10, the coal material is put into the first solvent 100. Here, the first solvent 100 may be, for example, a solvent in which NMP (N-methyl-2-pyrrolidone) and carbon disulfide are mixed in a volume ratio of 50:50 (hereinafter also referred to as "magic solvent"). Next, the first solvent 100 to which the coal material has been put is thoroughly stirred to fractionate the coal material into a first component (a component dissolved in the magic solvent; hereinafter also referred to as "MS") and a fifth component (a component not dissolved in the first solvent 100; hereinafter also referred to as "MI"), which is an extraction residue. Next, the first component MS is extracted from the first solvent 100, and the fifth component MI is separated from the first solvent 100 by filtration or the like, washed, and dried.

Next, in step S20, the first component MS is put into the second solvent 110. Here, examples of the second solvent 110 include acetone, toluene, and chloroform. These solvents may be used alone, or one or more of them may be mixed together. Next, the second solvent 110 containing the first component MS is thoroughly stirred to fractionate the first component MS into a second component (a component dissolved in the second solvent 110; hereinafter also referred to as "AS") and an extraction residue (a component not dissolved in the second solvent 110; hereinafter also referred to as "AI"). Next, the extraction residue AI is separated from the second solvent 110 by filtration or the like, washed, and dried.

Next, in step S30, the extraction residue AI is put into the third solvent 120. Here, examples of the third solvent 120 include pyridine, ethylenediamine, and tetrahydrofuran. These solvents may be used alone or in combination. Next, the third solvent 120 into which the extraction residue AI has been put is thoroughly stirred to fractionate the extraction residue AI into a third component (a component dissolved in the third solvent 120; hereinafter also referred to as "PS") and a fourth component (a component not dissolved in the third solvent 120; hereinafter also referred to as "PI"), which is the extraction residue. Next, the third component PS is extracted from the third solvent 120, and the fourth component PI is separated from the third solvent 120 by filtration or the like, washed, and dried.

Through the above steps, the coal material is fractionated into four components, namely the second to fifth components AS, PS, PI, and MI. The first component MS described above is composed of the second to fourth components AS, PS, and PI. In the above example, the coal material is fractionated using 100 to 120 of the first to third solvents (e.g., magic solvent, acetone, and pyridine), but the type and number of solvents used are not limited to these examples. For example, the more types of solvents used, the more components the coal material can be fractionated into, which is expected to improve the accuracy of the glass transition point measurement described below. However, the more solvents used, the more fractionation steps will be required, so it is preferable to use about three types as described above.

Next, elemental analysis, ¹ H NMR measurement, ¹³ C NMR measurement, and GPC (Gel Permeation Chromatography) measurement of the second to fifth components AS, PS, PI, and MI are performed to identify the constituent elements, molecular structure, and molecular weight (at least one of weight average molecular weight and number average molecular weight) of the second to fifth components AS, PS, PI, and MI. Here, elemental analysis of the second to fifth components AS, PS, PI, and MI can be performed in accordance with JIS M 8813 or JIS M 8819. Next, the average molecular structure (i.e., molecular model) of the second to fifth components AS, PS, PI, and MI is constructed so as to match the respective analytical values. An example of the average molecular structure of the second to fifth components AS, PS, PI, and MI is shown in FIG. 1 to FIG. 4. Here, the average molecular structure is a molecular structure that satisfies the molecular weight, specified carbon skeleton structure, functional groups, and elemental analysis values of each fraction component. It does not necessarily indicate that a compound with the average molecular structure is present in coal, but it is considered to be a molecular structure that reflects the physical properties of the fraction components.

It should be noted here that the structures shown in Figures 1 to 4 are merely average molecular structures of the second to fifth components AS, PS, PI, and MI. In other words, the second to fifth components AS, PS, PI, and MI do not necessarily contain compounds with the average molecular structures shown in Figures 1 to 4. For example, the average molecular structure shown in Figure 1 has a structure in which two polycyclic aromatic hydrocarbons are connected by a chain aliphatic hydrocarbon, but the second component AS does not necessarily have the average molecular structure shown in Figure 1. For example, the second component AS may be composed of a single polycyclic aromatic hydrocarbon, or may be an aggregate of multiple types of polycyclic aromatic hydrocarbons. An example of such an average structure is shown in Figure 1. In other words, in this embodiment, various possibilities are considered for the structure of the second component AS, but it is assumed to have one type of average molecular structure in order to simplify the molecular dynamics calculation. The same is true for the other third to fifth components PS, PI, and MI.

Next, the molecular number ratio (unit molecular number ratio) of the second to fifth components AS, PS, PI, and MI is obtained based on the mass ratio and molecular weight of the second to fifth components AS, PS, PI, and MI. As an example, if the second to fifth components AS, PS, PI, and MI have the average molecular structure shown in Figures 1 to 4 and their mass ratio is 4.2:13.8:18.5:65.4 (note that the total slightly exceeds 100, but this is due to a very small amount of solvent remaining, etc. In any case, it does not affect the subsequent calculations), the unit molecular number ratio of the second to fifth components AS, PS, PI, and MI is 1:1:2:3. Next, a molecular model of the coal material is constructed based on these data. The molecular model of the coal material has second to fifth components AS, PS, PI, and MI, and the second to fifth components AS, PS, PI, and MI have the average molecular structure described above. The molecular model of the coal material also has the second to fifth components AS, PS, PI, and MI in the unit molecule number ratio described above.

Next, the molecules that make up the binder are modeled. Here, in order to simplify the molecular dynamics calculations and make it easier to select an appropriate binder, the binder is assumed to be composed of a single component (e.g., coronene or corannulene). Therefore, the molecular structure of the components that make up the binder can be used as is as the average molecular structure (molecular model). Figure 5 (a) shows a molecular model of coronene, and (b) shows a molecular model of corannulene. The upper figure is a plan view, and the lower figure is a side view. Coronene has an almost planar structure, while corannulene has a slightly three-dimensional structure.

However, the binder actually used may be composed of multiple types of components, such as tar pitch and petroleum pitch. In this case, the molecular structure and mass ratio of the components constituting the binder may be identified by a known method (for example, Gas Chromatography-Mass Spectrometry (GC-MS) or Field Desorption-Mass Spectrometry (FD-MS), which are a type of mass spectrometry), and the expansion improvement effect may be evaluated for each component by the evaluation method described below. Then, a binder containing a large amount of components with a high expansion improvement effect (for example, 50 mass% or more) may be selected. Alternatively, the binder may be modeled in the same manner as the method for modeling coal materials. For example, the binder may be fractionated into multiple types of components using the first to third solvents 100 to 120 described above, and the average molecular structure and unit molecule number ratio of each component may be obtained. The molecular model of the binder obtained in this way has multiple components, and each component has an average molecular structure. Furthermore, the molecular model of the binder has each component in a unit molecular number ratio.

Next, a mixed model of the molecular model of the coal material and the molecular model of the binder is constructed. The binder is often added to the coal material at about 2 to 10 mass%. Taking this into consideration, the unit molecular number ratio of each component constituting the mixed model is calculated. Each component constituting the mixed model (coal material components and binder components) has the average molecular structure described above. As an example, the mixed model includes the second to fifth components AS, PS, PI, and MI and the binder coronene or corannulene in a unit molecular number ratio of 1:1:2:3:1. In this case, coronene or corannulene is added to the coal material at a ratio of approximately 5.0 mass% of the coal material. In the following description, the mixed model of the molecular model of the coal material and coronene is also referred to as mixed model A, and the mixed model of the molecular model of the coal material and corannulene is also referred to as mixed model B.

Next, a molecular dynamics calculation is performed on the mixed model to obtain the specific volume of the mixed model. The software used for the molecular dynamics calculation is not particularly limited, but an example is MaterialStudio manufactured by Daikin Industries, Ltd. The force field used in the molecular dynamics calculation is COMPASSII, and the molecular dynamics calculation is performed in a predetermined time interval (for example, 1 fs interval) and a predetermined step (for example, 5,000,000 steps (= 5 ns)) under the NPT ensemble. This process is performed at a predetermined temperature interval within a predetermined temperature range (for example, 50°C interval within a range of 0 to 600°C) to obtain the specific volume at each temperature. Note that the temperature of the mixed model here is assumed to be the temperature of the mixture of the coal material and the binder. Note that the predetermined temperature range and the predetermined temperature interval are not limited to the above example. For example, if the glass transition point described later is not found within the range of 0 to 600°C, it is preferable to expand the predetermined temperature range.

The specific calculation method is described below. First, unit cells of the mixed model are randomly arranged in a three-dimensional space. Here, the unit cell of the mixed model only needs to contain each component constituting the mixed model (coal material components and binder components) in the minimum number of the unit molecule number ratio described above. For example, if the mixed model contains the second to fifth components AS, PS, PI, and MI and the binder coronene or corannulene in a unit molecule number ratio of 1:1:2:3:1, the unit cell of the mixed model contains the second to fifth components AS, PS, PI, and MI and the binder coronene or corannulene in the following number of molecules: 1, 1, 2, 3, 1.

Figures 6 and 7 show a unit cell 10, which is an example of a unit cell arranged in a three-dimensional space. Specifically, Figure 6 is an explanatory diagram showing in three dimensions the behavior of a mixed model of a molecular model of a coal material and a molecular model of coronene. Figure 7 is an explanatory diagram showing in three dimensions the behavior of a mixed model of a molecular model of a coal material and a molecular model of corannulene. The unit cell 10 is composed of multiple molecular models (molecular model group) 10a that make up the coal material and a molecular model 10b or 10c of a binder. The molecular model 10b represents coronene, and the molecular model 10c represents corannulene.

Next, the total intermolecular interactions of the unit cell 10 are measured using the above-mentioned software. Then, the molecular arrangement of the unit cell 10 is changed at the above-mentioned predetermined time interval (e.g., 1 fs), and the total intermolecular interactions of the unit cell 10 are calculated again. When changing the molecular arrangement, the arrangement of each molecular model is determined so that the total intermolecular interactions of the unit cell 10 are reduced. This process is performed for a predetermined number of steps (e.g., 5,000,000 steps (= 5 ns)). At the end of the steps, the total intermolecular interactions generally converge to a certain value.

6 and 7, a box 30 that contains the unit cell 10 is placed in a three-dimensional space. The shape and size of the box 30 are not particularly limited, but may be, for example, a cube with one side of 5 nm. Of course, the shape of the box 30 is not limited to a cube, but may be a rectangular parallelepiped or any other shape. The size of the box 30 is also not important. Next, the boxes 30 are connected so that all the molecules that make up the unit cell 10 are contained. Note that only one box 30 is shown in FIGS. 6 and 7. In these examples, a part of the unit cell 10 protrudes from the box 30. Therefore, the boxes 30 are connected so that all the molecular models that make up the unit cell 10 fit inside the connected body of the boxes 30. Of course, if all the molecular models that make up the unit cell 10 fit within one box 30, it is not necessary to connect the boxes 30. Next, the density of the unit cell 10 is calculated by dividing the mass of the unit cell 10 by the total volume of the box 30 (or the connected body of the boxes 30 when the boxes 30 are connected). The inverse of this density is then used as the specific volume of the mixture model. The above process is carried out at predetermined temperature intervals within a predetermined temperature range (for example, at 50°C intervals within a range of 0 to 600°C) to determine the specific volume at each temperature.

On the other hand, a unit cell consisting of only the molecular model of the coal material is constructed, and the same process as described above is performed. That is, the molecular models constituting the unit cell of the coal material are randomly arranged in a three-dimensional space. Here, the unit cell of the molecular model of the coal material contains each component (component of the coal material) constituting the molecular model of the coal material in the minimum number of unit molecule ratios described above. For example, if the mixture model contains the second to fifth components AS, PS, PI, and MI in a unit molecule ratio of 1:1:2:3, the unit cell of the molecular model of the coal material contains the second to fifth components AS, PS, PI, and MI in the number of molecules of 1, 1, 2, and 3.

Figure 8 shows a unit cell 10', which is an example of a unit cell arranged in a three-dimensional space. That is, Figure 8 is an explanatory diagram showing the behavior of a molecular model of a coal material in three dimensions. The unit cell 10' is composed of multiple molecular models (group of molecular models) that make up the coal material.

Then, the above-mentioned software is used to calculate all intermolecular interactions in the unit cell 10'. Then, the molecular arrangement of the unit cell 10' is changed at the above-mentioned predetermined time interval (e.g., 1 fs), and all intermolecular interactions in the unit cell 10' are calculated again. When changing the molecular arrangement, the arrangement of each molecular model is determined so that the total intermolecular interactions in the unit cell 10' are reduced. This process is performed for a predetermined number of steps (e.g., 5,000,000 steps (= 5 ns)). At the end of the steps, all intermolecular interactions generally converge to a certain value.

Next, as shown in FIG. 8, a box 30 that contains the unit cell 10' is placed in a three-dimensional space. The characteristics of the box 30 are as described above. Next, the boxes 30 are connected so that all the molecules that make up the unit cell 10' are contained. Note that only one box 30 is shown in FIG. 8. In this example, a part of the unit cell 10' protrudes from the box 30. Therefore, the boxes 30 are connected so that all the molecular models that make up the unit cell 10' are contained inside the connected body of the boxes 30. Of course, if all the molecular models that make up the unit cell 10' can be contained within one box 30, it is not necessary to connect the boxes 30. Next, the density of the unit cell 10' is calculated by dividing the mass of the unit cell 10' by the total volume of the box 30 (or the connected body of the boxes 30 when the boxes 30 are connected). Next, the reciprocal of this density is taken as the specific volume of the molecular model of the coal material. The above process is carried out within a specified temperature range at specified temperature intervals (for example, within a range of 0 to 600°C at 50°C intervals), and the specific volume at each temperature is calculated. Note that the temperature of the molecular model of the coal material here is assumed to be the temperature of the coal material.

Next, the specific volumes (specific volumes of the molecular model of the coal material, or specific volumes of the mixed model) obtained by each of the above processes are summarized in a graph. An example is shown in Figs. 9 to 11. In Fig. 9, the horizontal axis indicates the temperature (°C) of the coal material, and the vertical axis indicates the specific volume (SV) (cm ³ /g) of the molecular model of the coal material. Point P1 indicates the calculated values of the temperature and specific volume of the coal material, graph L1 indicates the approximation line of point P1 on the high temperature side, and graph L2 indicates the approximation line of point P1 on the low temperature side. The approximation line is obtained, for example, by the least squares method. Then, the temperature corresponding to the intersection of graphs L1 and L2 is set as the glass transition point of the coal material. In the example of Fig. 9, the intersection of graphs L1 and L2 is in area A1, and the temperature corresponding to the intersection is 286°C. Therefore, in this example, the glass transition point (Tg) of the coal material is 286°C.

The glass transition point may be determined, for example, by the following method. That is, in this example, the temperature at which the rate of change of the specific volume with respect to temperature changes is determined as the glass transition point (glass transition temperature). This is determined as the intersection of the regression lines of the low-temperature point group and the high-temperature point group in drawing. Alternatively, for example, when the specific volume is determined at n different temperatures T1 to Tn, if the correlation coefficient when linearly regressing the (n-2) points T3 to Tn is R ² (1), Rsum(1)=1+R ² (1), and next, if the correlation coefficients when linearly regressing the points T1 to T3 and the points T4 to Tn are R ² (2) and R ² (3), respectively, Rsum(2)=R ² (2)+R ² (3) is determined. Thereafter, Rsum(n-2) = R ² (n-2) + R ² (n-1) is calculated in order, and the correlation coefficient R ² (n-1) obtained by linearly regressing the group of points T1 to T(n-2) is calculated to obtain Rsum(n-1) = R ² (n-1) + 1. When the maximum value of Rsum(1) to Rsum(n-1) is Rsum(k), the glass transition point may be determined as the temperature corresponding to the intersection of the regression lines of the group of points T1 to T(k-1) and the group of points T(k) to T(n). In the examples described later, the glass transition point was determined by this method.

The horizontal axis of FIG. 10 indicates the temperature (°C) of the mixed model A (mixture model of a molecular model of a coal material and coronene), and the vertical axis indicates the specific volume (SV) ( ^cm3 /g) of the mixed model A. Point P2 indicates the calculated values of the temperature and specific volume of the mixed model A, graph L3 indicates the approximation line of point P2 on the high temperature side, and graph L4 indicates the approximation line of point P2 on the low temperature side. The approximation lines are obtained, for example, by the least squares method. The temperature corresponding to the intersection of graphs L3 and L4 is the glass transition point of the coal material. In the example of FIG. 10, the intersection of graphs L3 and L4 is in area A2, and the temperature corresponding to the intersection is 247°C. Therefore, in this example, the glass transition point (Tg) of the mixed model A is 247°C.

The horizontal axis of FIG. 11 indicates the temperature (°C) of the mixed model B (a mixed model of a molecular model of a coal material and corannulene), and the vertical axis indicates the specific volume (SV) (cm ³ /g) of the mixed model B. Point P3 indicates the calculated values of the temperature and specific volume of the mixed model B, graph L5 indicates the approximate straight line of point P3 on the high temperature side, and graph L6 indicates the approximate straight line of point P3 on the low temperature side. The approximate straight lines are obtained, for example, by the least squares method. The temperature corresponding to the intersection of graphs L5 and L6 is the glass transition point of the coal material. In the example of FIG. 11, the intersection of graphs L5 and L6 is in area A3, and the temperature corresponding to the intersection is 411°C. Therefore, in this example, the glass transition point (Tg) of the mixed model B is 411°C.

Although the modeling measurement method has been described above, the glass transition point acquisition process is not limited to this example, and the glass transition point may be measured directly using DSC. In this case, the glass transition point of the coal material (or a mixture of the coal material and the binder in a desired mixing ratio) is directly measured using an appropriate DSC measurement device. In this case, in measuring the glass transition point, the endothermic peak due to the vaporization of molecules with small molecular weights may overlap with the endothermic peak due to thermal expansion, which may slightly reduce the measurement accuracy of the glass transition point. From this perspective, the modeling measurement method is preferable.

<1-2. Evaluation process>
In the evaluation step, the expansion improvement effect of each binder on the coal material is evaluated based on the glass transition point of the mixture (mixture model) obtained for each binder. For example, the smaller the glass transition point obtained for each binder is relative to the glass transition point of the coal material, the greater the expansion improvement effect of the binder may be evaluated. For example, when the glass transition point obtained for each binder is 15°C or more lower than the glass transition point of the coal material, the expansion improvement effect of the binder may be evaluated to be greater. As described above, the lower the glass transition point of the coal material, the lower the temperature at which the coal material charged into the coke oven softens and melts, and therefore a stronger coke is produced. Note that, for a binder whose glass transition point of the mixture with the coal material is different from that of a binder whose glass transition point has already been obtained, the glass transition point of the mixture of the coal material and the binder may be obtained and compared with the glass transition point already obtained to evaluate the expansion improvement effect of the binder.

In the examples of Figures 6 to 11, the glass transition point of the coal material is 286°C, the glass transition point of the mixture obtained for coronene (mixture model A) is 247°C, and the glass transition point of the mixture obtained for corannulene (mixture model B) is 411°C, so for this coal material, coronene is a binder with a better expansion improvement effect than corannulene. Note that the smaller the glass transition point obtained for each binder is relative to the glass transition point of the coal material, the greater the expansion improvement effect of the binder can be evaluated as. For this reason, for example, if there exists a binder whose mixture with the coal material exhibiting the characteristics of Figure 9 has a glass transition point lower than 247°C, that binder would be a binder with a better expansion improvement effect than coronene.

In the examples of Figures 6 to 11, it is not clear why coronene has a better expansion-improving effect than corannulene. If we dare to consider the reason, it is known that the van der Waals forces between the molecules that make up caking coal act stronger than those between the molecules that make up non- or slightly caking coal. On the other hand, since coronene has a more planar structure than corannulene (see Figures 5(a) and (b)), it is easy to penetrate between the molecules of the coal material against the van der Waals forces. And, the coronene that penetrates between the molecules of the coal material relaxes the van der Waals forces acting between the molecules of the coal material. In other words, it lowers the glass transition point. As described above, when the glass transition point of the coal material is lowered, the coal material charged into the coke oven starts to soften and melt at a lower temperature, so that the components that do not melt at low temperatures (i.e., components that do not melt at that temperature) melt in the area that melts at low temperatures, and as a result, the softening and melting area expands, and a stronger coke is produced. Considering these factors, it is believed that the coal materials used in the examples of Figures 6 to 11 contain more caking components and are more compatible with coronene (the addition of coronene reduces the van der Waals forces, i.e., lowers the glass transition point, and softening and melting begin at a lower temperature).

Of course, this judgment is merely one example, and it is entirely possible that the above judgment will change if the coal material changes. For example, for coal materials that exhibit characteristics different from those shown in Figure 9, it is entirely possible that the glass transition point of a mixture with corannulene will be lower than the glass transition point of a mixture with coronene. In this case, corannulene will have a superior effect on improving the expansiveness of that coal material.

As described above, according to this embodiment, the expansion improvement effect of the binder can be evaluated based on the glass transition temperature of the mixture of the coal material and the binder, so that the expansion improvement effect of the binder can be evaluated without conducting a large-scale test using a Gieseler blastometer or a dilatometer. Furthermore, as shown in the examples described later, the evaluation results according to this embodiment also match the test results using a Gieseler blastometer. Therefore, according to this embodiment, the expansion improvement effect of the binder can be appropriately and simply evaluated. The expansion improvement effect in this embodiment is evaluated, for example, by the maximum expansion coefficient defined in JIS M 8801. The larger the maximum expansion coefficient, the greater the expansion improvement effect. In this embodiment, the expansion improvement effect can be evaluated without conducting a test according to JIS M 8801.

Furthermore, in the glass transition point acquisition process, a molecular model of the coal material may be constructed by modeling the molecules that constitute the coal material, and a molecular model of the binder may be constructed by modeling the molecules that constitute the binder. The specific volume of a mixed model of the molecular model of the coal material and the molecular model of the binder may then be calculated at multiple temperatures using a molecular dynamics calculation method, and the glass transition point of the mixture may be obtained based on a correlation graph between the specific volume of the mixed model and temperature. In this case, the behavior of molecules with relatively low molecular weights can also be more accurately reflected in the calculation of the glass transition point.

Furthermore, in the glass transition point acquisition step, a molecular model of the coal material may be constructed by modeling the molecules that make up the coal material, and the specific volume of the molecular model of the coal material may be calculated at multiple temperatures using a molecular dynamics calculation method. Then, the glass transition point of the coal material may be acquired based on a correlation graph between the specific volume of the molecular model of the coal material and temperature, and in the evaluation step, the expansion improvement effect of each binder on the coal material may be evaluated based on the glass transition point of the coal material and the glass transition point of the mixture obtained for each binder. This makes it possible to more accurately evaluate the expansion improvement effect of the binder.

Furthermore, in the evaluation process, the smaller the glass transition temperature obtained for each binder is relative to the glass transition temperature of the coal material, the greater the expansion improvement effect of the binder may be evaluated. In this case, the expansion improvement effect of the binder can be evaluated more accurately.

2. Coke manufacturing method
Next, a method for producing coke using the above-mentioned binder evaluation method will be described. In the method for producing coke according to this embodiment, a binder to be added to a coal material is determined based on the above-mentioned binder evaluation method, and the determined binder and the coal material are used to produce coke.

Specific methods for selecting a binder include, for example, the following. First, the glass transition point of the coal material used in the production of coke is obtained according to the binder evaluation method described above. Meanwhile, the glass transition point of the mixture (mixture model) of the binder and coal material to be used is obtained according to the binder evaluation method described above. Next, a binder is selected that will cause the glass transition point of the mixture to be lower than that of the coal material. Next, the difference in glass transition point (glass transition point of the coal material - glass transition point of the mixture of the binder and the coal material) may be calculated for each selected binder, and the binder with the largest difference may be selected. Alternatively, a target value may be set for the difference, and a binder with a difference larger than the target value may be selected. For example, of the binders with a difference larger than the target value, the one that is the easiest to obtain (e.g., low cost) or the one that is easiest to handle may be selected.

The following examples (test examples) were carried out to verify the effects of this embodiment. Of course, the present invention is not limited to the examples described below. It is clear that a person with ordinary knowledge in the technical field to which this invention pertains can come up with various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

First, molecular models of the coal materials were constructed. Coal I (caking coal) and coal II (non- or slightly caking coal) were used as the coal materials.
The coal material was put into the above-mentioned magic solvent and thoroughly stirred. As a result, the coal material was fractionated into a first component MS (a component dissolved in the magic solvent) and a fifth component MI (a component not dissolved in the magic solvent) which was an extraction residue.

Next, the first component MS was added to acetone and thoroughly stirred. This resulted in fractionation of the first component MS into the second component AS (the component dissolved in the second solvent 110) and the extraction residue AI (the component not dissolved in the second solvent 110).

Next, the extraction residue AI was added to pyridine and thoroughly stirred. This resulted in the extraction residue AI being fractionated into a third component PS (a component dissolved in the third solvent 120) and a fourth component PI (a component not dissolved in the third solvent 120), which is the extraction residue.

Through the above process, the coal material was fractionated into four components, namely the second to fifth components AS, PS, PI, and MI. The first component MS mentioned above is composed of the second to fourth components AS, PS, and PI.

Next, the second to fifth components AS, PS, PI, and MI were subjected to elemental analysis (analysis in accordance with JIS M 8813), ¹ H NMR measurement, ¹³ C NMR measurement, and GPC (Gel Permeation Chromatography) measurement to identify the constituent elements, molecular structures, and weight average molecular weights of the second to fifth components AS, PS, PI, and MI. Next, the average molecular structures (i.e., molecular models) of the second to fifth components AS, PS, PI, and MI were constructed so as to match the respective analytical values. The average molecular structures of the second to fifth components AS, PS, PI, and MI obtained from coal I are shown in Figures 1 to 4. AS, PS, and MI obtained from coal II are shown in Figure 14. Here, the average molecular structures were determined from the above-mentioned viewpoints.

As mentioned above, the components contained in the coal material are not necessarily limited to the second to fifth components AS, PS, PI, and MI, and may contain other components in addition to (or instead of) the second to fifth components AS, PS, PI, and MI. Here, in order to simplify the molecular dynamics calculations, the processing was carried out assuming that the average molecular structures of the components contained in the coal material are those shown in Figures 1 to 4 and 14.

Next, the molecular number ratios (unit molecular number ratios) of the second to fifth components AS, PS, PI, and MI were calculated based on the mass ratios and molecular weights of the second to fifth components AS, PS, PI, and MI. As a result, the mass ratios of the second to fifth components AS, PS, PI, and MI for coal I and coal II were 4.2:13.8:18.5:65.4 and 6.5:16.3:0.3:75.8, respectively. The total slightly exceeds 100, but this is due to the fact that a very small amount of solvent remained. In any case, this does not affect the subsequent calculations. Therefore, the unit molecular number ratios of the second to fifth components AS, PS, PI, and MI for coal I and coal II were 1:1:2:3 and 1:1:0:4, respectively. Next, molecular models of coal I and coal II were constructed based on these data. The molecular model of the coal material has second to fifth components AS, PS, PI, and MI, and the second to fifth components AS, PS, PI, and MI have the average molecular structure described above. The molecular model of the coal material also has the second to fifth components AS, PS, PI, and MI in the unit molecule number ratio described above.

Next, the molecules that make up the binder were modeled. Here, in order to simplify the molecular dynamics calculations and make it easier to select an appropriate binder, the binder for coal I was assumed to be composed of a single component (e.g., coronene or corannulene). Therefore, the molecular structure of the components that make up the binder becomes the average molecular structure (molecular model) of the binder. Figure 5 (a) shows a molecular model of coronene, and (b) shows a molecular model of corannulene. The upper figure is a plan view, and the lower figure is a side view. Coronene, pyrene, anthracene, and naphthalene were used for coal II. The molecular structures of coronene, pyrene, anthracene, and naphthalene are shown in Figure 15.

Next, for coal I, a mixed model of the molecular model of the coal material and the molecular model of the binder was constructed, assuming that 5% by mass of coronene or corannulene was added to coal I. Therefore, the mixed model in this test example (mixed model A or B) contains the second to fifth components AS, PS, PI, and MI and the binder coronene or corannulene in a unit molecular ratio of 1:1:2:3:1. For coal II, a mixed model of the molecular model of the coal material and the molecular model of the binder was constructed, assuming that 5% by mass of one of coronene, pyrene, anthracene, or naphthalene was added to coal II. Therefore, the mixed models for coal II (mixed models C to F) contain the second to fifth components AS, PS, PI, and MI and the binder coronene, pyrene, anthracene, or naphthalene in a unit molecular ratio of 1:1:0:4:1.

Next, a molecular dynamics calculation was performed on the mixed model to determine the specific volume of the mixed model. The software used for the molecular dynamics calculation was MaterialStudio manufactured by Daikin Industries, Ltd. The force field used in the molecular dynamics calculation was COMPASSII, and the molecular dynamics calculation was performed for a specified time interval (here, 1 fs interval) and a specified step (here, 5,000,000 steps (= 5 ns)) under the NPT ensemble. This process was performed at specified temperature intervals within a specified temperature range (here, 50°C intervals within the range of 0 to 600°C), and the specific volume at each temperature was determined.

The specific calculation method for the specific volume at each temperature is as described above. That is, first, unit cells of the mixed model were randomly arranged in a three-dimensional space. Here, the unit cell of the mixed model for coal I contains the second to fifth components AS, PS, PI, and MI and the binder coronene or corannulene with the molecular numbers of 1, 1, 2, 3, and 1. Also, the unit cell of the mixed model for coal II contains the second to fifth components AS, PS, PI, and MI and one of the binders coronene, pyrene, anthracene, or naphthalene with the molecular numbers of 1, 1, 0, 4, and 1.

Below, molecular dynamics calculations of the mixed model will be explained using two models for coal I as examples. Figures 6 and 7 show a unit cell 10, which is an example of a unit cell arranged in three-dimensional space. The unit cell 10 is composed of multiple molecular models (molecular model group) 10a that constitute the coal material and a molecular model 10b or 10c of the binder. Molecular model 10b shows coronene, and molecular model 10c shows corannulene. That is, Figure 6 shows a unit cell of mixed model A, and Figure 7 shows a unit cell of mixed model B.

Next, the total intermolecular interactions of the unit cell 10 were calculated using the above-mentioned software. Then, the molecular arrangement of the unit cell 10 was changed at the above-mentioned predetermined time intervals (here, 1 fs), and the total intermolecular interactions of the unit cell 10 were calculated again. Here, when changing the molecular arrangement, the arrangement of each molecular model was determined so that the total intermolecular interactions of the unit cell 10 were reduced. This process was performed for a predetermined number of steps (here, 5,000,000 steps (= 5 ns)). At the end of the steps, the total intermolecular interactions generally converged to a certain value. The convergence value was a different value for each temperature.

Next, as shown in Figures 6 and 7, a box 30 containing a unit cell 10 was placed in a three-dimensional space. Here, the box 30 was a cube with a side length of 5 nm. Next, the boxes 30 were connected so that all of the molecules constituting the unit cell 10 were contained. Note that only one box 30 is shown in Figures 6 and 7. In these examples, a part of the unit cell 10 protrudes from the box 30. Therefore, the boxes 30 were connected so that all of the molecular models constituting the unit cell 10 were contained inside the connected body of the boxes 30. Next, the density of the unit cell 10 was calculated by dividing the mass of the unit cell 10 by the total volume of the connected body of the boxes 30. Next, the reciprocal of this density was taken as the specific volume of the mixed model. The above process was performed at predetermined temperature intervals within a predetermined temperature range (here, at 50°C intervals within the range of 0 to 600°C) to determine the specific volume at each temperature.

Meanwhile, a unit cell consisting only of the molecular model of the coal material was constructed, and the same process as described above was carried out. That is, the molecular models constituting the unit cell of the coal material (coal I) were randomly arranged in a three-dimensional space. Here, the unit cell of the molecular model of coal I contains the second to fifth components AS, PS, PI, and MI with the molecular numbers of 1, 1, 2, and 3. Similarly, the unit cell of the molecular model of coal II contains the second to fifth components AS, PS, PI, and MI with the molecular numbers of 1, 1, 0, and 4.

Figure 8 shows a unit cell 10', which is an example of a unit cell arranged in a three-dimensional space. The unit cell 10' is composed of multiple molecular models (group of molecular models) that make up coal material.

Next, the total intermolecular interactions of the unit cell 10' were calculated using the above-mentioned software. Then, the molecular arrangement of the unit cell 10' was changed at the above-mentioned predetermined time intervals (here, 1 fs), and the total intermolecular interactions of the unit cell 10' were calculated again. Here, when changing the molecular arrangement, the arrangement of each molecular model was determined so that the total intermolecular interactions of the unit cell 10' were reduced. This process was performed for a predetermined number of steps (here, 5,000,000 steps (= 5 ns)). At the end of the steps, the total intermolecular interactions generally converged to a certain value. The convergence value was a different value for each temperature.

Next, as shown in FIG. 8, a box 30 containing the unit cell 10' was placed in a three-dimensional space. Again, the box 30 was a cube with a side length of 5 nm. The boxes 30 were then connected so that all of the molecules constituting the unit cell 10' were contained. The density of the unit cell 10' was then calculated by dividing the mass of the unit cell 10' by the total volume of the connected boxes 30. The reciprocal of this density was then taken as the specific volume of the molecular model of the coal material. The above process was carried out at a predetermined temperature interval (here, at 50°C intervals within the range of 0 to 600°C) to determine the specific volume at each temperature.

The specific volumes (specific volumes of the molecular models of the coal materials, or specific volumes of the mixed models) obtained by each of the above treatments were then compiled in graphs. The results are shown in Figures 9 to 11, using the results for coal I as an example. The definitions for Figures 9 to 11 are as described above. The glass transition points were obtained from the graphs in Figures 9 to 11 using the method described above. As shown in Figures 9 to 11, the glass transition point (Tg) of coal I was 286°C, the glass transition point (Tg) of mixed model A was 247°C, and the glass transition point (Tg) of mixed model B was 411°C.

From the above results, it can be concluded that coronene is the binder that exhibits an excellent expansion improvement effect on the coal material. Next, in order to confirm that this judgment is correct, the maximum expansion coefficient was measured according to JIS B 8801 for each of the coal material, mixture A' in which 5% by mass (mass % relative to the coal material) of coronene was added to the coal material, and mixture B' in which 5% by mass (mass % relative to the coal material) of corannulene was added to the coal material. As a result, the maximum expansion coefficient of mixture A' increased by 101% compared to the maximum expansion coefficient of the coal material, while the maximum expansion coefficient of mixture B' was almost the same as the maximum expansion coefficient of the coal material. Therefore, it can be concluded that coronene is the binder that exhibits an excellent expansion improvement effect on this coal material. Next, the results obtained for coal II will be described. It was found that the glass transition temperature of coal II was 301°C. The glass transition temperatures obtained from a mixture model in which any one of coronene, pyrene, anthracene, and naphthalene coexisted are shown in FIG. 16. As a result, compared to the case of only coal II, the glass transition temperature of the mixed model in which naphthalene coexists with coal II as a binder molecule was 288°C, which was lower than that of coal II alone. The glass transition temperature of the mixed model in which coronene coexists with coal II as a binder molecule was also 284°C, which was lower than that of coal II alone. The glass transition temperatures of the mixed models in which coal II coexists with pyrene and anthracene were all higher than those of the pure coals. In accordance with JIS M8801, the expansion coefficients of the systems in which only coal II and 5% by mass of each binder were added to coal II were measured. As a result, as shown in FIG. 17, compared to the case of only coal II, the total expansion coefficients of the systems in which 5% by mass of coronene and naphthalene were added to coal II increased to 210% and 113%, respectively, but the total expansion coefficients of the systems in which 5% by mass of pyrene and anthracene were added to coal were lower than those of the pure coals.
From the above, by calculating the glass transition temperature using molecular dynamics calculations for each system of coal II only and coal II with a binder added, it was shown that if the glass transition temperature is lower in the system with the addition of a binder than in the system of coal only, it can be predicted that the additive has the effect of improving the expansion of coal.
Therefore, this method is effective not only for heavily caking coals, but also for coals with relatively low expansion properties, such as non- or slightly caking coals.

As a result of the above, it was confirmed that the binder evaluation method according to this embodiment, i.e., by evaluating the expansion improvement effect of the binder based on the glass transition point of the mixture of the coal material and the binder, the expansion improvement effect of the binder can be accurately evaluated.

Although the preferred embodiments and examples of the present invention have been described in detail above, the present invention is not limited to these examples. It is clear that a person with ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

10 Unit cell of the mixed model 10' Unit cell of the molecular model of the carbon material 10a Molecular model of the coal material 10b Molecular model of coronene 10c Molecular model of corannulene

Claims (6)

A glass transition point acquisition step of acquiring a glass transition point of a coal material that is a raw material for coke, and further acquiring glass transition points of a mixture of the coal material and a binder to be mixed with the coal material for a plurality of types of the binder;
and an evaluation step of evaluating an expansion improving effect of each binder on the coal material based on the glass transition point of the coal material and the glass transition point of the mixture obtained for each binder .
In the glass transition temperature obtaining step,
A molecular model of the coal material is constructed by modeling the components constituting the coal material, a specific volume of the molecular model of the coal material is calculated at a plurality of temperatures by a molecular dynamics calculation method, and a glass transition point of the coal material is obtained based on a correlation graph between the specific volume of the molecular model of the coal material and the temperature, or a glass transition point of the coal material is measured by differential scanning calorimetry;
A molecular model of the coal material is constructed by modeling the components constituting the coal material, and a molecular model of the binder is constructed by modeling the components constituting the binder. The specific volumes of a mixed model of the molecular model of the coal material and the molecular model of the binder are calculated at a plurality of temperatures by a molecular dynamics calculation method, and the glass transition point of the mixture is measured based on a correlation graph between the specific volume of the mixed model and the temperature, or the glass transition point of the mixture is measured using differential scanning calorimetry.
A method for evaluating a binder, comprising: a glass transition point acquisition step of acquiring a glass transition point of a coal material that is a raw material for coke, and further acquiring a glass transition point of a mixture of the coal material and a binder to be mixed with the coal material;
and an evaluation step of evaluating an expansion improving effect of the binder on the coal material based on a glass transition point of the coal material and a glass transition point of the mixture .
In the glass transition temperature obtaining step,
A molecular model of the coal material is constructed by modeling the components constituting the coal material, a specific volume of the molecular model of the coal material is calculated at a plurality of temperatures by a molecular dynamics calculation method, and a glass transition point of the coal material is obtained based on a correlation graph between the specific volume of the molecular model of the coal material and the temperature, or a glass transition point of the coal material is measured by differential scanning calorimetry;
A molecular model of the coal material is constructed by modeling the components constituting the coal material, and a molecular model of the binder is constructed by modeling the components constituting the binder. The specific volumes of a mixed model of the molecular model of the coal material and the molecular model of the binder are calculated at a plurality of temperatures by a molecular dynamics calculation method, and the glass transition point of the mixture is measured based on a correlation graph between the specific volume of the mixed model and the temperature, or the glass transition point of the mixture is measured using differential scanning calorimetry.
A method for evaluating a binder, comprising: In the evaluation step,
3. The method for evaluating a binder according to claim 1, wherein the binder is evaluated to have a greater expansion improvement effect as the glass transition temperature obtained for each binder is smaller than the glass transition temperature of the coal material. The method for evaluating a binder according to claim 1 or 2, characterized in that when the glass transition point obtained for each binder is 15°C or more lower than the glass transition point of the coal material, the binder is evaluated as having a large expansion improvement effect. The method for evaluating a binder according to any one of claims 1 to 4 , wherein the coal material is a hard caking coal or a non- or slightly caking coal. A method for producing coke, comprising: determining a binder to be added to a coal material based on the binder evaluation method according to any one of claims 1 to 5 ; and producing coke using the determined binder and the coal material.

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