JP6979267B2 - How to make coke - Google Patents

Description

The present invention relates to a method for producing coke.

Conventionally, coke used as a raw material for steelmaking is required to have high strength in order to ensure liquid permeability in a blast furnace.

However, the cost of producing coke increases when a large amount of high-quality coal is used to produce high-strength coke. Therefore, various studies have been conducted on inexpensive and high-strength coke manufacturing technology, and as a part of this, a method of controlling the strength by optimizing the pulverized particle size has been studied.

Generally, it is said that if the filling density when coal is charged into a coke oven is constant, the homogeneity increases as the coal is finely crushed in the same composition, and the strength of coke obtained by carbonization increases.

However, there has been a concern that the packing density is lowered and the productivity is lowered by making the pulverized particle size finer. Therefore, in order to suppress the decrease in the filling density, a method has been reported in which each simple coal before compounding is arranged according to the properties of each coal and an appropriate crushed particle size of each coal is set.

For example, Patent Document 1 discloses that the pulverized particle size is determined according to the length and size of the inert structure of the coking coal. In Patent Document 1, the crushed particle size of all coking coal is determined according to the length and size of the inert structure.

Japanese Unexamined Patent Publication No. 2010-138254

Higher accuracy is required for the method of determining the crushed particle size. An object of the present invention is to provide a method for producing coke, which can further optimize the crushed particle size of coking coal and increase the strength of the produced coke.

The present inventors have diligently studied a method for determining the pulverized grain size of coal according to the size of the inert. As a result, it was found that the correlation between the size of the inert and the increase in strength (crushing effect) obtained by crushing is low in the coal having high fluidity, and the correlation is high in the coal having low fluidity. The present invention is based on the above findings.

That is, the present invention provides the following.
It is a method for producing coke, which is a method for producing coke by carbonizing charged coal obtained by blending a plurality of types of simple coal.
A method for producing coke in which the following steps A to C are performed on a simple coal having a maximum fluidity of less than 350 ddpm.
Step A to obtain the index dHI of each simple coal according to the following procedures (a) to (c),
Procedure (a): The value calculated by the following formula (1) using the heating weight loss when the simple coal is heated is used as the index I _{H / C.}
I _{H / C} = aX ₀ + b ... Equation (1)
(However, X ₀ = heat loss (mg / g-coal.daf), and a and b are constants)
Procedure (b): The value calculated by the following formula (2) using the amount _{of CH 4} , CO, and CO ₂ generated in the gas generated in the above procedure (a) _{is used as the index IO / C.}
I _{O / C} = cX ₁ + d ... Equation (2)
(However, X ₁ = 1- [CH ₄ / (CH ₄ + CO + CO ₂ )], and c and d are constants)
Procedure (c): Calculate index dHI = (index I _{H / C} -index I _{O / C} ).
When each simple coal is crushed so that the proportion of crushed coal having a grain size of 3.0 mm or less is 80%, ^{the content of inertia having an area of 34500 μm 2} or more with respect to the entire simple coal structure (g / g / 100 g-Coal) and the content of inertia with an area of 34500 μm ² or more (g / g / Step B to obtain the Δ large inertia size (g / 100g-Coal), which is the difference from 100g-Coal), and
Step C for calculating the value Y indicating the crushing effect of each simple coal by the following formula (3).
Y = e × X ₂ ＋ f × X ₃ ＋ g × X ₄ ＋ h ・ ・ ・ ・ ・ ・ ・ ・ Equation (3)
(However, X ₂ is an index dHI, X ₃ is TI (volume ratio of the total amount of _{inertia structure to the total amount of coal), X 4} is Δ large inertia size, and e, f, g and h are. It is a constant.)

According to the above configuration, the value Y indicating the crushing effect is calculated based on the indexes dHI, TI, and the Δ large inertia size for the simple coal having a maximum fluidity of Gieseller less than 350 ddpm (steps A to step A). C). This is because the present inventors have found that for simple coal having low fluidity, the indicators dHI, TI, and Δ large inertia size have a good correlation with the crushing effect. The large crushing effect means that the degree of improvement in coke strength is large when the same amount of simple coal is crushed.
As a result, it is possible to determine the order of crushing and the crushed particle size in the simple coal having low fluidity.
As a result, it is possible to further optimize the pulverized particle size and increase the strength of the produced coke.
In Patent Document 1, the crushed particle size of all coking coals is determined according to the length and size of the inert structure, and the fluidity of each coking coal is not taken into consideration.

In the above configuration, it is preferable to carry out the following steps D to F for the simple coal having a maximum fluidity of 350 ddpm or more.
Step D of sieving each of the simple coals with a sieve having a predetermined opening.
Step E, in which the total expansion rate of fractions having a predetermined particle size or less sieved by the step D is measured with a dilatometer, and
Step F for calculating the value Y indicating the crushing effect by the following formula (4).
Y = i × X ₅ ＋ j × X ₆ ＋ k ・ ・ ・ ・ ・ ・ ・ ・ Equation (4)
(However, X ₅ is the maximum fluidity of the gieseller (ddpm), X ₆ is the total expansion coefficient of fractions having a predetermined particle size or less, and i, j and k are constants.)

According to the above configuration, for a simple coal having a maximum fluidity of Gieseller of 350 ddpm or more, a value Y indicating a crushing effect is calculated based on the maximum fluidity of Gieseller and the total expansion coefficient of fractions having a predetermined particle size or less. (Step D to Step F). This is because the present inventors have found that for simple coal having high fluidity, there is a good correlation between the maximum fluidity of Gieseller and the total expansion coefficient of fractions having a predetermined particle size or less and the crushing effect. ..
As a result, it is possible to determine the order of crushing and the crushed particle size among all the monolithic coals obtained by combining the monolithic coals having low fluidity and the monolithic coals having high fluidity.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing coke, which can further optimize the crushed particle size of coking coal and increase the strength of the produced coke.

It is a graph which shows the relationship between the "actual measurement crushing effect" actually obtained by the drum strength test, and the value Y "estimated crushing effect" of coals A to H calculated by the procedure of steps A to F.

Hereinafter, embodiments of the present invention will be described.

The method for producing coke according to this embodiment is
It is a method for producing coke, which is a method for producing coke by carbonizing charged coal obtained by blending a plurality of types of simple coal.
A method for producing coke in which at least the following steps A to C are performed on a simple coal having a maximum fluidity of less than 350 ddpm.
Step A to obtain the index dHI of each simple coal according to the following procedures (a) to (c),
Procedure (a): The value calculated by the following formula (1) using the heating weight loss when the simple coal is heated is used as the index I _{H / C.}
I _{H / C} = aX ₀ + b ... Equation (1)
(However, X ₀ = heat loss (mg / g-coal.daf), and a and b are constants)
Procedure (b): The value calculated by the following formula (2) using the amount _{of CH 4} , CO, and CO ₂ generated in the gas generated in the above procedure (a) _{is used as the index IO / C.}
I _{O / C} = cX ₁ + d ... Equation (2)
(However, X ₁ = 1- [CH ₄ / (CH ₄ + CO + CO ₂ )], and c and d are constants)
Procedure (c): Calculate index dHI = (index I _{H / C} -index I _{O / C} ).
When each simple coal is crushed so that the proportion of crushed coal having a grain size of 3.0 mm or less is 80%, ^{the content of inertia having an area of 34500 μm 2} or more with respect to the entire simple coal structure (g / g / 100 g-Coal) and the content of inertia (g / 100 g) with ^{an area of 34500 μm 2} or more with respect to the entire simple coal structure when crushed until the ratio of crushed particles of 3.0 mm or less is 100%. Step B to obtain Δlarge inertia size (g / 100g-Coal), which is the difference from −Coal), and
Step C for calculating the value Y indicating the crushing effect of each simple coal by the following formula (3).
Y = e × X ₂ ＋ f × X ₃ ＋ g × X ₄ ＋ h ・ ・ ・ ・ ・ ・ ・ ・ Equation (3)
(However, X ₂ is an index dHI, X ₃ is TI (volume ratio of the total amount of _{inertia structure to the total amount of coal), X 4} is Δ large inertia size, and e, f, g and h are. It is a constant.)

Hereinafter, each step will be described.

In the coke manufacturing method according to the present embodiment, the following steps A to C are performed on the simple coal having a maximum fluidity of Gieseller of less than 350 ddpm.

[Step A]
First, in step A, for the simple coal having a maximum fluidity of less than 350 ddpm, the index dHI of each simple coal is obtained by the following procedures (a) to (c).
Procedure (a): The value calculated by the following formula (1) using the heating weight loss when the simple coal is heated is used as the index I _{H / C.}
I _{H / C} = aX ₀ + b ... Equation (1)
(However, X ₀ = heat loss (mg / g-coal.daf), and a and b are constants)
Procedure (b): The value calculated by the following formula (2) using the amount _{of CH 4} , CO, and CO ₂ generated in the gas generated in the above procedure (a) _{is used as the index IO / C.}
I _{O / C} = cX ₁ + d ... Equation (2)
(However, X ₁ = 1- [CH ₄ / (CH ₄ + CO + CO ₂ )], and c and d are constants)
Procedure (c): Calculate index dHI = (index I _{H / C} -index I _{O / C} ).

The index I _{H / C} and the index I _{O / C} are indexes that can be used to estimate the drum strength DI of the blended coal. Details are described in Japanese Patent Application Laid-Open No. 4-275389 (particularly, paragraphs [0019] to [0027]), and detailed description thereof will be omitted here.

Further, the value calculated by the above formula (1) using the heating weight loss can be used as the index I _{H / C, and CH 4} , CO, CO ₂ in the gas generated during the procedure (a). For details on the fact that the value calculated by the above formula (2) can be used as the index _{IO / C} by using the amount of the above-mentioned generation amount, see Japanese Patent Application Laid-Open No. 4-275389 (particularly, paragraph [0039]). Although detailed description is omitted here because it is described, the inventors of the present applicant have previously found a high degree of correlation between IH _{/ C and thermal weight loss of raw coal. We have also found that there is a high degree of correlation between IO / C} and the amount of CO generated in the generated gas of the raw coal, and these values can be obtained, for example, from a thermal balance and a gas chromatograph. We have found that simultaneous measurement can be performed relatively easily with a combined device. In the present invention, it was decided to obtain _{the index I H / C} and the index I _{O / C values of each simple coal based on this.}

The constants a to d are constants determined by the measurement method and can be obtained by statistically analyzing a large number of measurement data.

[Step B]
Next, when each simple coal is crushed so that the ratio of the crushed grain size of 3.0 mm or less is 80%, the content of ^{inertia having an area of 34500 μm 2 or more with respect to the entire simple coal structure is contained.} (G / 100g-Coal) and the content of ^{inertia with an area of 34500 μm 2} or more with respect to the entire simple coal structure when crushed until the ratio of crushed grain size of 3.0 mm or less is 100% (g / 100 g-Coal). The Δ large inertia size (g / 100g-Coal), which is the difference from g / 100g-Coal), is obtained.

Specifically, it can be obtained by the method described in the examples.

[Process C]
Next, the value Y indicating the crushing effect of each simple coal is calculated by the following formula (3).
Y = e × X ₂ ＋ f × X ₃ ＋ g × X ₄ ＋ h ・ ・ ・ ・ ・ ・ ・ ・ Equation (3)
(However, X ₂ is an index dHI, X ₃ is TI (volume ratio of the total amount of _{inertia structure to the total amount of coal), X 4} is Δ large inertia size, and e, f, g and h are. It is a constant.)
The constants e to h are constants determined by the type of the furnace and the operating method, and can be obtained by statistically analyzing a large number of measurement data.

In the coke manufacturing method according to the present embodiment, it is preferable to further perform the following steps D to F for the simple coal having a maximum fluidity of 350 ddpm or more.

[Step D]
In step D, each of the simple coals having a maximum fluidity of 350 ddpm or more is sieved with a sieve having a predetermined opening.

The mesh opening of the sieve is preferably within a range in which the total expansion coefficient of the fraction measured in the step E described later and the actually measured pulverization effect can be correlated to some extent. Specifically, examples of the mesh opening of the sieve include 3.0 mm, 1.5 mm, and 0.5 mm. When the mesh opening of the sieve is selected within the range of 3.0 mm or less, the correlation between the total expansion coefficient of the fraction and the actually measured crushing effect becomes high. Therefore, if the mesh opening of the sieve is selected within the range of 3.0 mm or less, the estimated value of the crushing effect becomes more accurate.

[Step E]
Next, the total expansion rate of the fractions having a predetermined particle size or less sieved by the step D is measured by a dilatometer.

[Step F]
Next, step F in which the value Y indicating the crushing effect is calculated by the following formula (4).
Y = i × X ₅ ＋ j × X ₆ ＋ k ・ ・ ・ ・ ・ ・ ・ ・ Equation (4)
(However, X ₅ is the maximum fluidity of the gieseller (ddpm), X ₆ is the total expansion coefficient of fractions having a predetermined particle size or less, and i, j and k are constants.)

The constants i, j, and k are constants determined by the type of the furnace and the operation method, and can be obtained by statistically analyzing a large number of actual operation data. Specifically, it can be obtained by multiple regression analysis.

[Process G]
After the steps A to F, at least one of the above-mentioned values Y from all the simple coals (single coal having a maximum fluidity of Gieseller less than 350 ddpm and single taste coal having a maximum fluidity of Gieseller of 350 ddpm or more). Determine the largest simple charcoal. In the present embodiment, it is preferable to determine at least which of the simple coals has the largest value Y, but it is more preferable to determine the order of the simple coals in descending order of the value Y. When determining the ranking, all the simple coals may be ranked, but only the top few types may be ranked. For example, when 10 kinds of simple coals are blended, the ranking may be given only to the 5th value having the larger value Y.
In the present embodiment, the formula for obtaining the value Y is changed between the simple coal having a maximum fluidity of Gieseller of less than 350 ddpm and the single coal having a maximum fluidity of Gieseller of 350 ddpm or more. This is because the present inventors have discovered that the parameters that correlate with the crushing effect differ depending on the fluidity of the simple coal.
In the present embodiment, the formula for obtaining the value Y is changed between the simple coal having a maximum fluidity of Gieseller less than 350 ddpm and the single coal having a maximum fluidity of Gieseller of 350 ddpm or more, and calculated regardless of the fluidity. The resulting crushing effect (estimated crushing effect) is highly correlated with the actual crushing effect. As a result, it is possible to determine the order of crushing and the crushed particle size among all the monolithic coals obtained by combining the monolithic coals having low fluidity and the monolithic coals having high fluidity.

[Step H]
Next, it is preferable to pulverize at least the simple coal determined to have the largest value Y. The simple coal having the largest value Y determined in the step G is the single coal having the largest crushing effect. The large crushing effect means that the degree of improvement in coke strength is large when the same amount of simple coal is crushed.
That is, if the simple coal determined to have the largest crushing effect among the plurality of types in step G is crushed in step H, the coke strength is made efficient in such a manner that the crushed particle size of the entire charged coal does not become too fine. The strength can be increased.

Further, when the order of the simple coal is determined in the order of the value of the value Y in the step G, the simple coal is crushed in the order of the value of the value Y in the step H. For example, if the simple coal is crushed in the order determined in the step G until the target crushed particle size of the entire charged coal is reached, the coke strength can be increased more efficiently.

In the above-described embodiment, the case where the order of the simple coal is determined in descending order of the value Y in step G and the case where the simple coal is crushed in descending order of the value Y in step H has been described. However, the present invention is not limited to this example, and the ranked ones may be grouped by one or a plurality of types (preferably grouped into three or more) and crushed by the group.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

(Example 1)
<Verification of the correlation between the measured value of coke intensity DI and the estimated value>
First, eight types of simple coal (A charcoal to H charcoal) shown in Table 1 were prepared.
Table 1 shows the properties of these simple coals (VM, Ro _, MF, TI, I _{H / C} , I _{O / C} , dHI, Δ large inertia size, total expansion rate, -0.5 mm total expansion rate). Is shown. dHI is the value obtained by subtracting I _{O / C from I H / C} , that is, dHI = [I _{H / C −} I _{O / C} ].
The heating weight loss required to obtain the index I _{H / C} and the index I _{O / C and the amount of CH 4} , CO, and CO ₂ generated are determined by Rigaku's device name: differential thermal balance-mass spectrometry. The value obtained by heating to 800 ° C. using a simultaneous measuring device ThermoMass (TG-MS) was used.
In Table 1, VM, Ro _, MF, TI, total expansion coefficient, and -0.5 mm total expansion rate mean the following.
VM: Value obtained by subtracting water content from the mass loss rate when the sample is heated under predetermined conditions by cutting off contact with air (measured according to JIS M 8812).
Ro: In the reflectance measurement of vitrinit (microstructure derived mainly from the xylem of plants), the average value of the maximum reflectance of 50 points or more of one polished sample. A parameter that indicates the degree of coal conversion of raw coal. )
MF: The logarithmic value of the value at which the rotor indicates the maximum rotation speed in the Gieseller maximum fluidity (test using the Giesera-plastometer (heat softening and melting property test of coal whose details are specified in JISM8801). An index that represents cohesiveness.)
TI: Volume ratio of total amount of inert structure to total coal (measured according to JIS M 8816)
Total expansion rate: Total expansion rate of unsieved simple coal-0.5 mm Total expansion rate: After sieving the unsieved simple coal with a 0.5 mm mesh. Total expansion rate of fractions with a particle size of 0.5 mm or less The above-mentioned total expansion rate and -0.5 mm total expansion rate are both shrinkage rates measured by the expansion measurement method (diratometer method) described in JIS M8801. And the sum of the expansion rates (Total Dilatation).

Here, how to obtain the Δ large inertia size will be described.
First, each simple charcoal is crushed so that the proportion of those having a pulverized particle size of 3.0 mm or less is 80%, and the proportion of pulverized charcoal having a pulverized particle size of 3.0 mm or less is 100%. For the case of crushing, the weight ratio of the simple coal contained in each particle size range was determined by dividing by particle size. The results are shown in Table 2.
The weight ratio of the simple coal contained in each particle size range was determined as follows.
First, using a sieve with the following openings, the particles were sieved to each particle size with a low-tap type sieve shaker (manufactured by Iida Seisakusho).
Opening: 50mm, 25mm, 15mm, 9.5mm, 5.6mm, 3.0mm, 1.5mm, 0.5mm, 0.25mm, 0.15mm, 0.075mm
Next, the weight ratio was calculated by the following formula. The weight ratio is a percentage of the weight on each sieve.
(Weight ratio,%) = [(Weight on each sieve, g) / (Total weight, g)] x 100
For example, looking at brand A, coal having a particle size in the range of 9.5-5.6 mm when crushed until the proportion of coal having a crushed particle size of 3.0 mm or less is 80% is Coal with a particle size of 5.5% and a particle size in the range of 3.0-1.5 mm is 19.6%, and coal with a particle size in the range of 1.5-0.5 mm is 19.6%. The percentage of coal that is 31.1% and the particle size is in the range of 0.5-0.25 mm is 12.5%. On the other hand, when brand A is crushed until the proportion of coal having a crushed particle size of 3.0 mm or less is 100%, the amount of coal having a particle size in the range of 3.0-1.5 mm is 19.1%. There are 26.2% of coal having a particle size in the range of 1.5-0.5 mm, and 9.2% of coal having a particle size in the range of 0.5-0.25 mm. be.

Further, when each simple coal is crushed so that the ratio of those having a crushed particle size of 3.0 mm or less is 80%, and the ratio of crushed coal having a crushed particle size of 3.0 mm or less is 100%. For the case of crushing, the area ratio of inertia (the area of the structure that does not show the softening and meltability of coal) was calculated by dividing by particle size. Specifically, the inerts were identified by the method disclosed in Japanese Patent Application Laid-Open No. 2016-065821, and the total area of the inerts was calculated. Further, the coal portion (including the inertia) was identified by the same method, the total area of the coal portion was calculated, and the calculation was made by (inert area ratio) = (total inertia area) / (total coal partial area). The results are shown in Table 3.
For example, looking at brand A, when crushed to a ratio of 80% containing crushed particle size of 3.0 mm or less, it is contained in coal whose particle size is in the range of 9.5-5.6 mm. The area ratio of the inertia is 0.317, and the area ratio of the inertia contained in the coal having a particle size in the range of 3.0-0.25 mm is 0.155. On the other hand, when brand A is crushed until the ratio of crushed particles having a particle size of 3.0 mm or less becomes 100%, the area of inertia contained in coal having a particle size in the range of 3.0-1.5 mm. The ratio is 0.234, and the area ratio of the inert contained in the coal having a particle size in the range of 1.5-0.5 mm is 0.150, and the particle size is 0.5-0.25 mm. The area ratio of the inert contained in the coal within the range of is 0.155.

Further, when each simple coal is crushed so that the ratio of those having a crushed particle size of 3.0 mm or less is 80%, and the ratio of crushed coal having a crushed particle size of 3.0 mm or less is 100%. For the case of crushing, the area ratio of the ^{inertia having an area of 34500 μm 2} or more was obtained from the inertia (the area of the structure showing the softening and melting property of coal) divided by particle size. Specifically, the inerts were identified by the method disclosed in Japanese Patent Application Laid-Open No. 2016-065821, and the total area of the inerts was calculated. Also, of the inert to the identified area is screened 34500Myuemu ² or more inert, was calculated by (area ratio of 34500Myuemu ² or more inert) = (total area of 34500Myuemu ² or more inert) / (total inert area). The results are shown in Table 4.
For example, looking at brand A, when crushed so that the proportion of coal having a crushed particle size of 3.0 mm or less is 80%, the grain size of coal is within the range of 9.5-5.6 mm. Among the contained inertia, the area ratio of the inertia having an area of 34500 μm ² or more is 0.353, and the area ratio of the inertia contained in the coal having a particle size in the range of 3.0-0.25 mm is 0. .313. On the other hand, when brand A is crushed until the ratio of crushed particles having a particle size of 3.0 mm or less becomes 100%, among the inertia contained in coal having a particle size in the range of 3.0-1.5 mm. The area ratio of the inertia having an area of 34500 μm ² or more is 0.424, and the area ratio of the inertia contained in the coal having a particle size in the range of 1.5-0.5 mm is 0.000. The area ratio of inertia contained in coal having a particle size in the range of 0.5-0.25 mm is 0.000.

Next, when each simple coal is crushed so that the ratio of those having a pulverized particle size of 3.0 mm or less is 80%, and the ratio of pulverized coal having a pulverized particle size of 3.0 mm or less is 100%. The content ratio (g / 100g-Coal) of ^{large inerts (inerts having an area of 34500 μm 2} or more) contained in each particle size range was determined by dividing the case of crushing to the above by particle size.
For example, looking at brand A, when crushed to a ratio of 80% containing crushed particle size of 3.0 mm or less, it is contained in coal having a crushed particle size in the range of 9.5-5.6 mm. The ratio of large inerts is (weight ratio) x (inert area ratio) x (large inert area ratio) / (total weight ratio) = (5.5 x 0.317 x 0.353) / (5.5 + 19). 6.6 + 31.1 + 12.5) = 0.0090.
After that, the total content of large inert was calculated for each simple charcoal.
For example, looking at brand A, when pulverized so that the proportion of those having a pulverized particle size of 3.0 mm or less is 80%, the total content of large inert is 0.0090 + 0.0445 = 0. It became 0535. Further, when the mixture was crushed until the proportion of those having a crushed particle size of 3.0 mm or less was 100%, the total content of the large inert was 0.0347.

Then, the Δ large inertia size (g / 100g-Coal) was determined. Specifically, from the total content of large inerts when crushed until the ratio of crushed particles of 3.0 mm or less is 100%, the ratio of crushed particles of 3.0 mm or less is 80. The content ratio of large inert when crushed to% was subtracted, and this was taken as Δ large inert size (g / 100 g-Coal). The results are shown in Table 5.
For example, looking at brand A, the crushed particle size is 3. 0.0535, which is the total content of large inerts when crushed so that the proportion of 0 mm or less contained was 80%, was subtracted to obtain −0.0188 as the Δlarge inert size.

<Correlation between measured crushing effect and estimated crushing effect>
(Production Examples 1 to 8)
An evaluation blended coal was prepared in which any of A charcoal to H charcoal was blended with the blended coal as the base at the blending ratio shown in "blending ratio" in Table 6. The blended coal as a base and the coal to be evaluated (A coal to H coal) were blended so as to be 100% in total. For example, in Production Example 1, 20% of A charcoal was blended with 80% of the base blended coal to prepare a blended coal for evaluation.
When blending, the ratio including those having a crushed particle size of 3.0 mm or less was crushed with a hammer mill, a jaw crusher or a coffee mill so as to be the ratio shown in "Ratio of 3.0 mm or less" in Table 6. Above, compounded.
Specifically, in each production example, the crushed particle size of the evaluated coal (coal A to H) was pulverized to two levels, one having a particle size of 3.0 mm or less of about 80% and the other having a particle size of 100%.
For example, in Production Example 1-A in Production Example 1, the pulverized particle size of the evaluation coal A (A coal) is 79.5% or less when 3.0 mm or less (3.0 mm or less when the whole A coal is 100%). The ratio of those was 79.5%), while in Production Example 1-B, it was 100%.

After preparing the compound coal for evaluation, the water content was adjusted to 7.5% ± 0.2%.

Next, the water-adjusted sample was filled in a can container having an L: 235 mm × W: 300 mm × H: 235 mm with a filling density of 735 dry-kg / m ³ .

Next, carbonization was carried out at a dry distillation temperature of 1,000 ° C. for about 19 hours to obtain coke.

[Drum strength test] (Calculation of actual measurement crushing effect)
After performing the shutter test twice, the obtained coke was rotated 150 times with a drum tester, and DI ¹⁵⁰ ₁₅ was measured. The results are shown in Table 6. The actual measurement crushing effect is also shown in Table 6. The measured crushing effect is the DI improvement amount per 1% of coal having a particle size of 3.0 mm or less. For example, in Production Example 1, when the amount of charcoal having a particle size of 3.0 mm or less increases by 20.5% (100% -79.5% = 20.5%), the DI is improved by 0.2 (84.7). -84.5 = 0.2), and the measured crushing effect is about 0.010 (0.2 / 20.5≈0.010). Here, the larger the value of the measured crushing effect, the greater the effect of improving the strength by crushing.

(Calculation of estimated crushing effect)
<Regarding simple coal with a maximum fluidity of less than 350 ddpm>
The maximum fluidity of the Gieseller of A coal to E coal is less than 350 ddpm. Therefore, for the A coal to the E coal, the value Y indicating the estimated crushing effect was calculated by the following formula (3). The results are shown in Table 6.
Y = e × X ₂ ＋ f × X ₃ ＋ g × X ₄ ＋ h ・ ・ ・ ・ ・ ・ ・ ・ Equation (3)
(However, X ₂ is an index dHI, X ₃ is TI (volume ratio of the total amount of _{inertia structure to the total amount of coal), X 4} is Δ large inertia size, and e, f, g and h are. It is a constant. Specific e, f, g and h are as follows, and are constants determined by the type and operation method of the furnace, and can be obtained by statistically analyzing a large number of measurement data. .)
e: -0.16798
f: 0.00137
g: -1.50650
h: -0.09589

<About single-flavored charcoal with a maximum fluidity of 350 ddpm or more>
The F coal to H coal have a maximum fluidity of 350 ddpm or more. Therefore, for the F coal to the H coal, the value Y indicating the estimated crushing effect was calculated by the following formula (4). The results are shown in Table 6.
Y = i × X ₅ ＋ j × X ₆ ＋ k ・ ・ ・ ・ ・ ・ ・ ・ Equation (4)
(However, X ₅ is the maximum fluidity of the gieseller (ddpm), X ₆ is the total expansion coefficient of fractions having a predetermined particle size or less, and i, j and k are constants. Specific i, j and k is as follows and was obtained by multiple regression analysis.)
i: 4.48 × ^10-6
j: 0.000833
k: -0.0320

FIG. 1 is a graph showing the relationship between the “actually measured crushing effect” actually obtained by the above drum strength test and the value Y “estimated crushing effect” of the A coal to the H coal calculated by the procedures of steps A to F. be.
As can be seen from FIG. 1, the value of the actually measured crushing effect and the value of the estimated crushing effect according to the present invention show a good correlation. Therefore, it can be seen that if each simple coal is crushed based on the value of the estimated crushing effect, the coke strength can be efficiently increased in such a manner that the crushed particle size of the entire charged coal does not become too fine.

If the same formula (3) as that of the A coal to the E coal is used instead of the formula (4) for the F coal to the H coal having the maximum fluidity of the Gieseller of 350 ddpm or more, Table 6 shows. It was the value described in "Estimated crushing effect, when equation (3) was used". As can be seen from this result, it was found that when the formula (3) was used for the F coal to H coal having a maximum fluidity of 350 ddpm or more, the value was far from the actual crushing effect.

Claims (1)

It is a method for producing coke, which is a method for producing coke by carbonizing charged coal obtained by blending a plurality of types of simple coal.
The following steps A to C are performed on the simple coal having a maximum fluidity of less than 350 ddpm.
The following steps D to F are performed on the simple coal having a maximum fluidity of 350 ddpm or more.
After that, a method for producing coke in which the following steps G and H are performed.
Step A to obtain the index dHI of each simple coal according to the following procedures (a) to (c),
Procedure (a): The value calculated by the following formula (1) using the heating weight loss when the simple coal is heated is used as the index I _{H / C.}
I _{H / C} = aX ₀ + b ... Equation (1)
(However, X ₀ = heat loss (mg / g-coal.daf), and a and b are constants obtained by statistically analyzing a large number of measurement data)
Procedure (b): The value calculated by the following formula (2) using the amount _{of CH 4} , CO, and CO ₂ generated in the gas generated in the above procedure (a) _{is used as the index IO / C.}
I _{O / C} = cX ₁ + d ... Equation (2)
(However, X ₁ = 1- [CH ₄ / (CH ₄ + CO + CO ₂ )], and c and d are constants obtained by statistically analyzing a large number of measurement data).
Procedure (c): Calculate index dHI = (index I _{H / C} -index I _{O / C} ).
When each simple coal is crushed so that the proportion of crushed coal having a grain size of 3.0 mm or less is 80%, ^{the content of inertia having an area of 34500 μm 2} or more with respect to the entire simple coal structure (g / g / 100 g-Coal) and the content of inertia (g / 100 g) with ^{an area of 34500 μm 2} or more with respect to the entire simple coal structure when crushed until the ratio of crushed particles of 3.0 mm or less is 100%. Step B to obtain Δlarge inertia size (g / 100g-Coal), which is the difference from −Coal),
Step C, which calculates the value Y indicating the crushing effect of each simple coal by the following formula (3),
Y = e × X ₂ ＋ f × X ₃ ＋ g × X ₄ ＋ h ・ ・ ・ ・ ・ ・ ・ ・ Equation (3)
(However, X ₂ is an index dHI, X ₃ is TI (volume ratio of the total amount of _{inertia structure to the total amount of coal), X 4} is Δ large inertia size, and e, f, g and h are. It is a constant determined by the type and operation method of the reactor, and is a constant obtained by statistically analyzing a large number of measurement data.)
Step D of sieving each of the simple coals with a sieve having a mesh size of 3.0 mm or less,
Step E, in which the total expansion rate of the fractions below the opening sieved by the step D is measured by a dilatometer.
Step F, which calculates the value Y indicating the crushing effect by the following formula (4),
Y = i × X ₅ ＋ j × X ₆ ＋ k ・ ・ ・ ・ ・ ・ ・ ・ Equation (4)
(However, X ₅ is the maximum fluidity of the gieseller (ddpm), X ₆ is the total expansion rate of the fractions below the opening sieved by the step D , and i, j and k are the coefficients of the furnace. It is a constant determined by the model and operation method, and is a constant obtained by statistically analyzing a large number of actual operation data.)
Step G, which determines the order of the simple coal in descending order of the value Y.
Step H of crushing the simple coal until the target crushed particle size of the entire charged coal is reached in descending order of the value Y.