JP2017165850A - Manufacturing method of coke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of coke capable of increasing intensity of manufactured coke by rationalizing pulverization particle size by a simple method without needs for specific device.SOLUTION: There is provided a manufacturing method of coke for manufacturing coke by dry distillating a coal charge obtained by blending a plurality of kinds of single coals, which includes a process A for screening each single col by a sieve with a predetermined opening, a process B for measuring total expansion ratio of a fraction with the predetermined opening or less, which is screened in the process A by a dilatometer, a process C for calculating a value Y exhibiting pulverization effect by Y=a×X+b×X+c, where Xis Gieseler maximum fluidity (ddpm), Xis total expansion ratio of a fraction with the predetermined opening or less and a, b and c are constants, a process D for determining a single coal having at least the largest value Y and a process for pulverizing the single coal which is determined to have at least the largest value Y.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing coke.

  Conventionally, coke used as an iron-making raw material is required to have high strength in order to ensure liquid permeability in a blast furnace.

  However, if a large amount of high-quality coal that produces high-strength coke is used, coke production costs increase. Therefore, various investigations have been made on cheap and high-strength coke production techniques, and as part of this, methods for controlling the strength by optimizing the pulverized particle size have been studied.

  Generally, if the packing density when charging coal into a coke oven is constant, the homogeneity increases as the coal is finely pulverized in the same composition, and the strength of the coke obtained by dry distillation is said to increase.

  However, it has been a concern that reducing the pulverized particle size reduces the packing density and decreases the productivity. Therefore, in order to suppress a decrease in packing density, there has been reported a method of arranging each simple coal before blending according to each coal property and setting an appropriate pulverization particle size of each coal.

  For example, Patent Documents 1 to 4 disclose a method for producing high-strength coke by controlling the pulverization particle size and blending of coal according to the size of the inert structure.

  In Patent Documents 5 to 7, an appropriate pulverization particle size is determined according to various coal properties such as expansion rate, total inert amount, average particle size at arrival, average maximum reflectance, maximum Gieseller fluidity, hard glove index, etc. A method for producing high strength coke is disclosed.

  Patent Document 8 discloses a method for suppressing a decrease in strength by pulverizing coal having a large penetration distance.

  Patent Document 9 pulverizes non-coking coal having a volatile content of 30% by mass or more, a total expansion rate of 40% or less by dilatometer measurement, and a logarithmic value of Gieseller fluidity (ddpm) of 1.5 or less. In producing coke as part of the blended coal, a method for producing coke is disclosed in which the pulverization particle size of the non-slightly caking coal is determined so that the expansion inhibition fluctuation rate is a predetermined value or less.

JP 2004-339503 A JP 2008-297385 A JP 2010-138254 A JP 2006-27384 A JP 2007-112941 A JP 2008-133383 A JP2013-6958A JP 2012-72388 A Japanese Patent Laid-Open No. 2015-203045

  In Patent Documents 1 to 4, methods for evaluating the inert size include coal photographed by a microscope, a method of analyzing a coke image, a method of evaluating from a cumulative volume ratio of inert, and the like. However, the evaluation of the inert size of coal after pulverization or coke after carbonization by such a method is complicated and takes time.

  In the methods of Patent Documents 5 to 7, when coal properties are combined, it is necessary to perform a plurality of measurements, and it takes time to obtain information, and there is a problem that the amount of sample required increases.

  Further, the method of Patent Document 8 has a problem that a special measuring device is required for measuring the penetration distance.

  The present invention has been made in view of the above-described problems, and the object thereof is to increase the strength of coke produced by optimizing the pulverization particle size by a simple method without requiring a special apparatus. An object of the present invention is to provide a method for producing coke that can be used.

  The present inventors diligently studied a method for optimizing the pulverized particle size of each simple coal and increasing the strength of the coke produced. As a result, it was considered that the properties of the fine-grained part of simple coal would contribute to the coke strength. As a result of intensive studies, the present inventors have found that the total expansion rate of fractions having a predetermined particle size or less has a correlation with the grinding effect. The present invention has been made based on the above findings.

That is, the present invention provides the following.
A method for producing coke in which coke is produced by dry distillation of charging coal obtained by blending plural kinds of simple coals,
Step A of sieving each of the above simple coals with a sieve having a predetermined opening,
A step B of measuring a total expansion coefficient of a fraction having a predetermined particle size or less sieved by the step A by a dilatometer;
Step C for calculating the value Y indicating the grinding effect by the following formula (1),
Y = a × X ₁ + b × X ₂ + c... Formula (1)
(Wherein, _{X 1} is Gisera maximum fluidity degree (DDPM), _{X 2} is the total expansion ratio of the predetermined particle size or less of the fractions, a, b and c are constants.)
A step D for determining a simple coal having the largest value Y, and
Step E for crushing simple coal determined to have at least the largest value Y
A method for producing coke, comprising:

According to the above-described configuration, first, based on the Gieseler maximum fluidity of each simple coal and the total expansion coefficient of fractions having a predetermined particle size or less, the simple coal having the largest value Y indicating the grinding effect is determined ( Step A to Step D). The fact that the pulverization effect is large means that the degree of improvement in coke strength is large when the same amount of simple coal is pulverized. And in the process E, the simple charcoal determined that the said value Y is the largest is grind | pulverized.
In other words, in order to pulverize the simple coal determined to have the largest pulverization effect among the plurality of types in Step D in Step E, the coke strength is efficiently reduced in a mode in which the pulverized particle size of the entire charged coal is not too fine. The strength can be increased.
In the method of Patent Document 9, coke is produced as a part of blended coal by pulverizing non-slightly caking coal having a total expansion rate of 40% or less and a logarithmic value of Gieseller fluidity (ddpm) of 1.5 or less. In doing so, the pulverization particle size is determined, and the order of pulverization of a plurality of simple coals is not determined.

  As a result of diligent research, the inventors of the present invention have been able to increase coke strength more efficiently by determining the simple coal to be crushed from among the simple coals having a Gieseler maximum fluidity of 350 ddpm or more. Obtained knowledge that can be.

  That is, in the said structure, it is preferable that each said simple coal has a Gieseler maximum fluidity of 350 ddpm or more. When each of the simple coals has a Gieseler maximum fluidity of 350 ddpm or more, the coke strength can be increased more efficiently.

  In the said structure, it is preferable that the opening of the said sieve is selected within the range of 3 mm or less. As can be seen from the results of the examples, when the sieve opening is selected within a range of 3 mm or less, the correlation between the total expansion coefficient of the fraction and the actually measured pulverization effect increases. Accordingly, if the sieve opening is selected within a range of 3 mm or less, the estimated value of the pulverization effect becomes more accurate. As a result, it becomes possible to determine the simple coal having the largest value Y more accurately, and further, the coke strength can be efficiently increased.

  According to the present invention, it is possible to provide a coke production method capable of increasing the strength of coke produced by optimizing the pulverization particle size by a simple method without requiring a special apparatus. .

It is a graph which shows the relationship between the DI improvement width (actually measured grinding | pulverization effect) per 3.0% ratio 1% actually calculated | required by the drum strength test, and "-0.5mm total expansion coefficient". It is a graph which shows the relationship between the DI improvement width (actual measurement grinding | pulverization effect) per 1% of the ratio of 3.0 mm or less actually calculated | required by the drum strength test, and "-1.5mm total expansion coefficient". It is a graph which shows the relationship between the DI improvement width (actual measurement grinding | pulverization effect) per 1% of the ratio of 3.0 mm or less actually calculated | required by the drum strength test, and "-3.0mm total expansion coefficient". It is a graph which shows the relationship between the measurement grinding | pulverization effect actually calculated | required by the drum strength test, and the value Y (estimated grinding | pulverization effect).

  Hereinafter, embodiments of the present invention will be described.

The method for producing coke according to the present embodiment is as follows:
A method for producing coke in which coke is produced by dry distillation of charging coal obtained by blending plural kinds of simple coals,
Step A of sieving each of the above simple coals with a sieve having a predetermined opening,
A step B of measuring a total expansion coefficient of a fraction having a predetermined particle size or less sieved by the step A by a dilatometer;
Step C for calculating the value Y indicating the grinding effect by the following formula (1),
Y = a × X ₁ + b × X ₂ + c... Formula (1)
(Wherein, _{X 1} is Gisera maximum fluidity degree (DDPM), _{X 2} is the total expansion ratio of the predetermined particle size or less of the fractions, a, b and c are constants.)
A step D for determining a simple coal having the largest value Y, and
Step E for crushing simple coal determined to have at least the largest value Y
At least.

  Hereinafter, each step will be described.

[Step A]
First, in the process A, each said simple charcoal is sieved with the sieve of a predetermined opening.

  The opening of the sieve is preferably within a range in which a correlation between the total expansion coefficient of the fraction measured in Step B, which will be described later, and the measured pulverization effect is obtained to some extent. Specifically, examples of the sieve opening include 3 mm, 1.5 mm, and 0.5 mm. As can be seen from the results of the examples, when the sieve opening is selected within a range of 3 mm or less, the correlation between the total expansion coefficient of the fraction and the actually measured pulverization effect increases. Accordingly, if the sieve opening is selected within a range of 3 mm or less, the estimated value of the pulverization effect becomes more accurate. As a result, it becomes possible to determine the simple coal having the largest value Y more accurately, and further, the coke strength can be efficiently increased.

  In the process A, the simple coal to be subjected to sieving preferably has a Gieseler maximum fluidity of 350 ddpm or more, and more preferably 500 ddpm or more. Moreover, although it is preferable that the Gieseler maximum fluidity of the simple coal is as large as possible, for example, 60000 ddpm or less may be mentioned. When each of the simple coals has a Gieseler maximum fluidity of 350 ddpm or more, the coke strength can be increased more efficiently.

[Step B]
Next, the total expansion coefficient of the fraction having a predetermined particle size or less sieved in the step A is measured with a dilatometer.

[Step C]
Next, a value Y indicating the pulverization effect is calculated by the following formula (1).
Y = a × X ₁ + b × X ₂ + c... Formula (1)
(Wherein, _{X 1} is Gisera maximum fluidity degree (DDPM), _{X 2} is the total expansion ratio of the predetermined particle size or less of the fractions, a, b and c are constants.)

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

[Step D]
Next, at least the simple coal having the largest value Y is determined.
In the present invention, it is only necessary to determine which of the simple charcoal having the largest value Y, but it is preferable to determine the rank of the simple charcoal in descending order of the value Y. In addition, when determining a ranking, you may give a ranking about all the simple charcoal, but you may give a ranking only to several high rank types. For example, when 10 kinds of simple coal are blended, the ranking may be given only to the fifth largest value Y.

[Step E]
Next, at least the simple charcoal determined to have the largest value Y is pulverized. The solid coal having the largest value Y determined in Step C is the simple coal having the largest grinding effect. The fact that the pulverization effect is large means that the degree of improvement in coke strength is large when the same amount of simple coal is pulverized.
In other words, in order to pulverize the simple coal determined to have the largest pulverization effect among the plurality of types in Step D in Step E, the coke strength is efficiently reduced in a mode in which the pulverized particle size of the entire charged coal is not too fine. The strength can be increased.

  Further, when the rank of the simple coal is determined in the order of increasing the value Y in the process D, the simple coal is pulverized in the order of the value Y in the process E. For example, if the simple coal is pulverized in the order determined in the step D until the pulverized particle size of the entire charged coal is reached, the coke strength can be increased more efficiently.

  In the above-described embodiment, in the case where the rank of the simple charcoal is determined in the descending order of the value Y in the process D, the case where the simple charcoal is pulverized in the descending order of the value Y in the process E has been described. However, the present invention is not limited to this example, and those with a ranking may be grouped into one or more types (preferably grouped into three or more) and pulverized into groups.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to a following example, unless the summary is exceeded.

<Correlation between the measured pulverization effect and the total expansion coefficient of fractions of a predetermined particle size or less>
First, four kinds of brand simple charcoal shown in Table 1 were prepared.
Table 1 shows the coal properties (VM, Ro _, MF, TI, total expansion coefficient, −3 mm total expansion coefficient, −1.5 mm total expansion coefficient, −0.5 mm total expansion coefficient) of these simple coals. Show. In Table 1, VM, Ro _, MF, TI, total expansion coefficient, -3 mm total expansion coefficient, -1.5 mm total expansion coefficient, and -0.5 mm total expansion coefficient mean the following.
VM: A value obtained by subtracting moisture from the mass reduction rate when the sample is heated under predetermined conditions with contact with air being cut off (measured according to JIS M 8812).
Ro: average value of 50 or more maximum reflectances of one polishing material in the reflectance measurement of vitrinite (a fine structure mainly derived from a woody part of a plant). A parameter indicating the degree of coalification of raw coal. )
MF: Maximum Gieseller fluidity (logarithmic value of the value at which the rotor blades show the maximum number of revolutions in a test using a Giesera-Plastometer (coal heat softening and melting characteristics test specified in JISM8801). An index representative of caking properties.)
TI: Volume ratio of the total amount of inert tissue to the whole coal (measured according to JIS M 8816)
Total expansion rate: Total expansion rate of uncoated plain coal -3 mm Total expansion rate: Particle size of 3 mm or less after sieving uncoated solid coal with a 3 mm sieve -1.5 mm total expansion coefficient: The total expansion coefficient of the fraction having a particle size of 1.5 mm or less after sieving the uncoated plain coal with a 1.5 mm sieve. -0.5 mm total expansion coefficient: after the sieving of uncoated plain coal with a sieve having an opening of 0.5 mm, the total expansion coefficient of the fraction having a particle size of 0.5 mm or less, the total expansion coefficient,- The 3 mm total expansion coefficient, -1.5 mm total expansion coefficient, and -0.5 mm total expansion coefficient are all of the shrinkage ratio and the expansion coefficient measured by the expansibility measuring method (dilatometer method) described in JIS M8801. It is the sum (Total Dilatation).

<Correlation between measured grinding effect and -0.5 mm total expansion coefficient>
(Production Example 1 to Production Example 4)
An evaluation blended charcoal was prepared by blending any one of coals A to D with the blending ratio shown in “mixing ratio” in Table 2 to the base blended coal. It mix | blended so that the sum total of the combination charcoal used as a base and charcoal of evaluation object (A charcoal-D charcoal) might be 100%. For example, in Production Example 1, 20% of Charcoal A was blended with 80% of the blended coal serving as the base to obtain a blended coal for evaluation.
When blending, the ratio of the particles having a pulverized particle size of 3.0 mm or less was pulverized with a hammer mill, jaw crusher or coffee mill so that the ratio shown in Table 2 “3.0 mm or less ratio” was obtained. Formulated above.
Specifically, in each of the production examples, the pulverized particle sizes of the evaluation coals A to D were pulverized into two levels of 3.0 mm or less, which is about 80%, and 100%.
For example, in Production Example 1 in Production Example 1-A, the pulverized particle size of evaluation coal A is 82.6% when 3.0 mm or less (the ratio of 3.0 mm or less with respect to 100% of the entire A coal is 82%). .6%), while in Production Example 1-B, it was set to 100%.

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

Next, the moisture-adjusted sample was filled into a can container of L: 235 mm × W: 300 mm × H: 235 mm at a filling density of 735 dry-kg / m ³ .

  Next, coke was obtained by carbonization at a carbonization temperature of 1,000 ° C. for about 19 hours.

[Drum strength test]
The obtained coke was subjected to shutter test twice, and then rotated 150 times with a drum tester, and DI ¹⁵⁰ ₁₅ was measured. The results are shown in Table 2. The measured grinding effect is also shown in Table 2. The measured pulverization effect is the DI improvement per 1% of charcoal having a particle size of 3.0 mm or less. For example, in Production Example 1, when the charcoal having a particle size of 3.0 mm or less is increased by 17.4% (100% -82.6% = 17.4%), DI is improved by 0.7 (85.0 -84.3 = 0.7), the measured grinding effect is about 0.040 (0.7 / 17.4≈0.040). Here, the larger the measured grinding effect value, the greater the strength improvement effect by grinding. Therefore, the ranking was given in descending order of the measured grinding effect.

FIG. 1 is a graph showing a DI improvement width per 1% of a ratio of 3.0 mm or less actually obtained by the drum strength test, that is, a relationship between “measured grinding effect” and “−0.5 mm total expansion rate”. It is. Specifically, the values of -0.5 mm total expansion rate of charcoal A to charcoal D in Table 1 are plotted on the horizontal axis, and the measured grinding effect values in Table 2 are plotted on the vertical axis.
As can be seen from FIG. 1, the value of the measured grinding effect and the -0.5 mm total expansion coefficient show a good correlation.

<Correlation between measured grinding effect and -1.5 mm total expansion coefficient>
FIG. 2 shows the DI improvement width per 1% of the ratio of 3.0 mm or less actually obtained in the same manner as in the drum strength test, that is, the relationship between “measured grinding effect” and “−1.5 mm total expansion rate”. It is a graph which shows.

<Correlation between measured grinding effect and -3.0 mm total expansion coefficient>
FIG. 3 shows the DI improvement width per 1% of the ratio of 3.0 mm or less actually obtained in the same manner as in the drum strength test, that is, the relationship between “measured grinding effect” and “−3.0 mm total expansion rate”. It is a graph which shows.

As can be seen from FIG. 2, the measured grinding effect value and the -1.5 mm total expansion coefficient show a good correlation. Moreover, as can be seen from FIG. 3, the value of the measured grinding effect and the -3.0 mm total expansion coefficient show a good correlation. Therefore, in this example, it can be seen that the estimated value of the pulverization effect can be obtained with high accuracy by using the total expansion coefficient of the fraction having a particle size of 3 mm or less. Especially, in the present Example, it turns out that the value of the measurement grinding | pulverization effect and the -1.5mm total expansion coefficient show the better correlation. Therefore, it can be seen that the estimated value of the pulverization effect can be obtained more accurately by using the -0.5 mm total expansion coefficient.
As described above, if a sieve having a mesh opening of 3 mm or smaller is used in Step A, an estimated value of the pulverization effect can be obtained with high accuracy, and it is possible to determine the simple coal to be crushed with high accuracy. .
In addition, what is necessary is just to set suitably the opening of the sieve used in the process A within the range in which a desired correlation is acquired with the measurement grinding | pulverization effect, and it is not limited to 3 mm or less.

<Calculation of estimated grinding effect when -0.5 mm total expansion rate is adopted>
In this example, the most correlated -0.5 mm total expansion coefficient was adopted to calculate the estimated grinding effect. Specifically, the value Y indicating the estimated pulverization effect was calculated by the following formula (1). The results are shown in Table 2.
Y = a × X ₁ + b × X ₂ + c... Formula (1)
(Where X ₁ is the Gieseler maximum fluidity (ddpm), X ₂ is the total expansion coefficient of the fraction of −0.5 mm, and a, b and c are constants. And c are as follows and were determined by multiple regression analysis.)
a: 4.48 × 10 ⁻⁶
b: 0.000834
c: -0.0320

FIG. 4 shows the DI improvement width per 1% of the ratio of 0.5 mm or less actually obtained by the drum strength test, that is, the “measured grinding effect” and the coals A to D calculated by the procedures of the steps A to C. It is a graph which shows the relationship with value Y "estimated crushing effect".
As can be seen from FIG. 4, the measured grinding effect value and the estimated grinding effect value according to the present invention show a good correlation. Therefore, if the value of the estimated pulverization effect, that is, the pulverized coal in order from the highest value Y is pulverized in order, the coke strength can be efficiently increased in a manner that the pulverized particle size of the entire charged coal is not too fine. I understand that I can do it.

Claims (3)

A method for producing coke in which coke is produced by dry distillation of charging coal obtained by blending plural kinds of simple coals,
Step A of sieving each of the above simple coals with a sieve having a predetermined opening,
A step B of measuring a total expansion coefficient of a fraction having a predetermined particle size or less sieved by the step A by a dilatometer;
Step C for calculating the value Y indicating the grinding effect by the following formula (1),
Y = a × X ₁ + b × X ₂ + c... Formula (1)
(Wherein, _{X 1} is Gisera maximum fluidity degree (DDPM), _{X 2} is the total expansion ratio of the predetermined particle size or less of the fractions, a, b and c are constants.)
A step D for determining a simple coal having the largest value Y, and
Step E for crushing simple coal determined to have at least the largest value Y
A method for producing coke, comprising:   The coke production method according to claim 1, wherein each simple coal has a Gieseler maximum fluidity of 350 ddpm or more.   The method for producing coke according to claim 1 or 2, wherein an opening of the sieve is selected within a range of 3 mm or less.

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