JP2013053189A - Estimation method of highest flow rate of raw material for coke production, blending method of raw material for coke production, and raw material for coke production made by the blending method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently estimate an optimal combining condition when making a raw material for coke production in which a low grade coal is combined by a convenient method, and to make the raw material for coke production that is excellent in a caking property or flowability.SOLUTION: An estimation method of the highest flow rate of a raw material for coke production is characterized as follows. One or more charcoal types of coking coals are select as a standard charcoal beforehand; a range of a proper flow rate of the standard charcoal, a flow rate characteristic curve to a temperature of the standard charcoal, and the highest flow rate of the standard charcoal based on the flow rate characteristic curve are obtained; in addition, about one or more low grade coals to be combined, a flow rate decrease gradient concerning the low grade coal based on a change of the highest flow rate of the standard charcoal to a combined proportion rate of the low grade coal is obtained; and the highest flow rate of a combined coal in which the low grade coal is combined to the coking coal is estimated from a combined proportion rate of the low grade coal combined to the coking coal based on the highest flow rate of the coking coal actually used, and the flow rate decrease gradient concerning the low grade coal to be actually combined.

Description

  The present invention relates to a method for estimating the maximum fluidity of a raw material for coke production, a method for blending raw materials for coke production, and a raw material for coke production produced by the blending method.

  Coal used as a raw material for metallurgical coke (hereinafter referred to as raw coal) is softened and melted when heated and then re-solidified to form strong coke, which is classified as bituminous coal and is generally referred to as caking coal. However, bituminous coal that can be used as a raw material for coke production has a problem of limited resources and high cost. Accordingly, there is a demand for an increase in the distribution of low-grade weakly caking coal or non-slightly caking coal or even lower grade coal. When low-grade coal is used as a raw material for coke production, since many coals having different properties exist, it is necessary to use coal having caking properties and a degree of coalification in an appropriate range. Therefore, attempts have been made to design a blended coal in which a plurality of types of coal having different properties are combined and blended.

  The cohesiveness of such coal is determined by properties such as fluidity, expansibility, and tackiness, but fluidity greatly affects the coke strength. For this reason, grasping the maximum fluidity of blended coal (hereinafter sometimes referred to as “MF (Maximum Fluidity)”) is an important factor for producing high-strength coke. Conventionally, the MF of blended coal has been estimated by the weighted average value of each MF of blended simple coal. However, the flow start temperature (ST), maximum flow temperature (MFT) and solidification temperature (FT) of each of the blended plain coals are different. Therefore, the weighted average value of each coal simple MF and the MF of blended coal do not match. The estimated value of the common logarithm value (hereinafter sometimes referred to as “logMF”) of the maximum fluidity of the blended coal, which has been conventionally performed, is lower than the actually measured value. Such a tendency becomes more prominent as more MF coal is used, which has been a major cause of reducing the estimation accuracy of coke strength (for example, Patent Document 1 [Prior Art] and [Invention will be solved]. [See the problem to be considered]].

  Then, the estimation method of MF of the coal blend which estimates MF of coal blend based on each flow curve of each coal blended was examined. Specifically, based on the flow curve of each of the blended coal, the flow curve is formulated from the flow start temperature, the maximum flow temperature, the solidification temperature, and the fluidity, and based on the obtained mathematical formula, the flow The flow rate of the blended coal is calculated by calculating the logarithmic value of the flow rate of each of the coals at a constant temperature from the start temperature to the solidification temperature, and calculating the weighted average of the logarithm values of the obtained flow rates. And the method of estimating the maximum value of the fluidity | liquidity of the said coal blend calculated in this way with MF of the said coal blend is proposed (for example, refer patent document 1 [Claim 1]).

Japanese Patent Laid-Open No. 02-20592

However, in the above case, the following problems occur.
(I) Since the method of Patent Document 1 cannot detect log MF of low-grade coal to be blended with coking coal mainly composed of caking coal, MF or log MF of blended coal is not different from MF or log MF of raw coal. Therefore, it cannot be applied as an estimation method.
(Ii) On the other hand, the estimated value of the weight average of each MF or log MF of each coal as in the past may cause a large deviation from the estimated value of MF or log MF of the actual blended coal. Can not do it.
(Iii) In particular, even when blending with low grade coal at the same ratio using the same raw coal, depending on the brand of low grade coal, the weight average of each MF or log MF of each coal The deviation from the estimated value may increase.
(Iv) Currently, a method for obtaining the MF or log MF of the coal blend corresponding to the blending ratio in advance according to the individual blending conditions is not applied except for actual measurement.

  The purpose of the present invention is to estimate the optimum blending conditions efficiently by a simple method when producing a raw material for coke production blended with low-grade coal in view of the problems of the above-mentioned prior art, A method for estimating the maximum fluidity of a coke production raw material capable of producing a coke production raw material having excellent caking or fluidity, and for coke production that maintains or improves compared to conventional coke quality by the estimation method An object of the present invention is to provide a raw material blending method and a coke production raw material produced by the blending method.

  As a result of intensive studies to solve the above problems, the present inventor has obtained the following estimation method of the maximum fluidity of the raw material for coke production, the blending method of the raw material for coke production, and the coke produced by the blending method The inventors have found that the above object can be achieved by using raw materials for production, and have completed the present invention.

The method for estimating the maximum fluidity of the raw material for coke production according to the present invention is to produce a raw material for coke production whose main component is blended coal produced by blending low-grade coal with raw coal.
One or more types of coking coal are selected in advance as a reference coal, a range of an appropriate fluidity of the reference coal, a fluidity characteristic curve with respect to the temperature of the reference coal, and the reference based on the fluidity characteristic curve The maximum fluidity of charcoal is obtained, and for one or more low-grade coal blended, the fluidity of the low-grade coal based on the change in the maximum fluidity of the reference coal relative to the blending ratio of the low-grade coal While finding the decline slope,
Based on the maximum fluidity of the raw coal actually used and the flow rate decrease gradient of the low-grade coal actually blended, the blending ratio of the low-grade coal blended with the raw coal The maximum fluidity of the blended coal in which the low-grade coal is blended with the charcoal is estimated.

Because the blended coal used as a raw material for coke production is required to have proper fluidity or caking property based on fluidity, estimation of the maximum fluidity at the time of blending the specified raw coal and low-grade coal is extremely important. On the other hand, it is difficult to efficiently secure a desired blended coal by the method of measuring the fluidity for each blended coal as before. As a result of verifying the method of estimating the maximum fluidity (MF) of a coal blend in which low-grade coal is blended with raw coal, the present invention estimates the MF of the coal blend from the knowledge that it has the following characteristics. Found that can be done.
(A) The fluidity decrease gradient accompanying the blending of low-grade coal does not depend on the coal type and characteristics of the raw coal (reference coal).
(B) The fluidity decline gradient with low-grade coal blended is unique to the brand of low-grade coal and does not need to be obtained each time blending.
Specifically, one or two or more low-grade coals to be used are blended with reference coal (MF is obtained in advance), and a fluidity decrease gradient related to each low-grade coal is obtained in advance. It became possible to estimate the MF of the blended coal efficiently by a simple method from the blending ratio of the low-grade coal blended with the MF of the raw coal actually used and the flow rate gradient. Here, “low-grade coal” refers to coal or carbide that has not been softened and melted, such as anthracite, and sub-bituminous coal, lignite, or peat, etc. Coal has a relatively coarse structure with a large amount of moisture, oxygen and volatile components and a small amount of carbon. It has little fluidity and caking properties and does not coke itself. In actual evaluation, the comparison is generally made not as MF but as the common logarithm log MF.

The present invention is a method for estimating the maximum fluidity of the coke production raw material, wherein the flow rate decrease gradient with respect to the oxygen content of the blended low-grade coal is determined, and the low-grade coal used is used The flow rate decreasing gradient is corrected by the oxygen content of the low-grade coal.
In the results of the above verification, the MF of the blended coal shows a tendency to decrease in fluidity as the oxygen content of the blended low-grade coal increases with the knowledge that it depends on the brand of blended low-grade coal. And gained knowledge. Since these tendencies affect the flow rate gradient of low-grade coal, they can be corrected based on the oxygen content of the low-grade coal blended (shown in the characteristic chart of coal sold in general). Thus, the MF of the blended coal can be estimated more accurately.

The present invention is a method for estimating the maximum fluidity of the raw material for producing coke, wherein the flow of the low-grade coal to be used is determined by determining the fluctuation of the fluidity-decreasing gradient with respect to the volatile content of the low-grade coal to be blended. The degree-decreasing gradient is corrected by the volatile content of the low-grade coal.
As a result of the above verification, MF of blended coal obtained knowledge that, in addition to the oxygen content of blended low-grade coal, fluidity tends to decrease as the volatile content of low-rank coal increases. . These tendencies affect the flow rate gradient of low-grade coal as well as the oxygen content, and are therefore corrected based on the volatile content of the low-grade coal blended (also clearly indicated in the coal characteristics table). This makes it possible to estimate the MF of the coal blend more accurately.

Further, the present invention is a method for blending raw materials for coke production using any one of the above-described methods for estimating the maximum fluidity of raw materials for coke production, wherein the maximum fluidity of raw coal used actually is low, The blending ratio of the low-grade coal blended with the raw coal is set so as to be within the range of the proper fluidity based on the fluidity decrease gradient related to the grade coal.
The ability to estimate the MF of the blended coal with high accuracy means that the maximum fluidity of the produced coke production raw material can be adjusted appropriately. The present invention sets the blending ratio of the low-grade coal blended with the raw coal based on the flow rate decrease gradient of the low-grade coal obtained in the MF estimation method of the blended coal as described above. It became possible to make MF become the range of the appropriate fluidity.

Further, the present invention is a raw material for coke production mainly composed of blended coal produced by blending low-grade coal with raw coal by the above-described method for blending raw materials for coke production, and the blending of the low-grade coal It has a ratio of 0.1 to 10% and a common logarithmic value of 2 to 3 of the maximum fluidity of the blended coal.
The blended charcoal produced by the blending method has excellent caking properties or fluidity. Such characteristics are sufficient to ensure suitability as a raw material for coke production, and it is useful to use the blended coal thus produced as a raw material for coke production.

Explanatory drawing showing the manufacturing process of metallurgical coke Schematic illustrating the flow characteristic curve with respect to the temperature of the reference coal Schematic illustrating the variation in fluidity of blended coal corresponding to the blending ratio of low-grade coal Schematic illustrating the fluctuation of the flow rate decrease gradient of the blended coal corresponding to the coal type and fluidity of the raw coal Schematic illustrating the variation in flow rate decline gradient of blended coal corresponding to the oxygen content of low grade coal Schematic illustrating the variation in flow rate decline gradient of blended coal corresponding to the oxygen content of low grade coal Schematic illustrating the fluctuation of the flow rate decrease gradient of coal blends corresponding to the volatile content of low grade coal

  The estimation method of the maximum fluidity (MF) of the raw material for coke production according to the present invention (hereinafter referred to as “the present estimation method”) is a coke mainly composed of blended coal produced by blending low-grade coal with raw coal. When producing a raw material for production, one or more types of coking coal are selected in advance as a reference coal, a range of an appropriate fluidity of the reference coal, a fluidity characteristic curve with respect to the temperature of the reference coal, The maximum fluidity of the reference coal is determined based on the fluidity characteristic curve, and the change in the maximum fluidity of the reference coal with respect to the blending ratio of the low-grade coal is further determined for one or more low-grade coal blended. Based on the maximum fluidity of the coking coal actually used and the flowability decreasing gradient of the low-grade coal that is actually blended. Mixing ratio of the low-grade coal blended in Et al., Low-grade coal in the raw material coal and estimates a maximum fluidity degree of coal blend formulated. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Coke production process>
The manufacturing process of metallurgical coke will be briefly described with reference to FIG. Coal is landed from the coal carrier 1 berthed at the quay and stored in the coal storage 2 for each property (brand) of the coal. Coal (including coking coal and low-grade coal) stored in the coal storage 2 is dispensed by a reclaimer for each brand and sent to the blending tank 3 by a belt conveyor. The blending tank 3 has a plurality of tanks, and one brand of coal is stored in one blending tank. Coal has high and low costs due to its properties, and in order to produce coke with good quality at low cost, coal with different properties is cut out from multiple blending tanks at the optimum blending ratio, and raw materials for coke production (blended coal ) Is completed. That is, for coke production, various types (brands) of coal are imported from overseas and stored in the coal storage 2 for each brand. This is because coal mined in each coal mine has different properties for each coal mine, and the properties of coke produced differ depending on the properties. Therefore, by combining multiple coals, it is requested by the user at the cheapest cost. This is because it is necessary to satisfy the coke properties (quality).

  The pulverization equipment 4 is provided with a known pulverizer, and pulverizes the blended coal. The coal pulverized in the pulverization facility 4 is transferred to the coke oven 6 by a belt conveyor or the like. The transferred coal is temporarily stored in a coal bin (coal tower) 6a, and then charged into the coke oven 6 by a charging vehicle 6b and dry-distilled (steamed). The dry-distilled coal becomes coke and is pushed out of the coke oven by the extruder 6c. The obtained product coke is finally fed into the blast furnace.

<Method for estimating MF of blended coal according to the present invention>
In this estimation method, the characteristics of the blended coal that is a raw material for coke production supplied in the coke production process is estimated based on the characteristics of the raw coal and the characteristics of the low-grade coal. That is, this estimation method can estimate MF of coal blend simply and efficiently by the procedures (1) to (5) described later based on the following knowledge.
(A) The fluidity decrease gradient (hereinafter sometimes referred to as “Δlog MF”) accompanying the blending of low-grade coal is less dependent on the coal type and characteristics of the raw coal (reference coal).
(B) Δlog MF of low grade coal is unique to the brand of low grade coal.
Here, “log MF” indicates a common logarithm of the maximum fluidity (MF), and is used in actual evaluation. “Δlog MF” indicates the gradient (fluidity decreasing gradient).
In the following, the verification process in which the knowledge was obtained will be described in detail, and the MF of the blended coal in this estimation method will be described.

[Characteristics of coal]
The quality of coal is usually evaluated by caking or fluidity as physical properties and by four industrial analysis values (water, ash, volatile, fixed carbon) as chemical properties. In this estimation method, the fluidity of the blended coal was estimated in order to evaluate the suitability as a raw material for producing coke by using the fluidity among these characteristics.

(I) Verification of flow rate measurement method The flow rate of coal is measured by the Gieseler plastometer measurement method standardized in JIS-M8801. Specifically, as illustrated in FIG. 2 (A), by using the temperature as an index, the fluctuation of the fluidity in the softened and melted state of the coal to be evaluated is traced, and the fluidity characteristic curve (Giesler fluidity) Curve) and the fluidity of the coal is evaluated with the maximum fluidity (MF) which is the maximum value. Note that, in actual evaluation, it is generally compared not as an MF value but as a common logarithm log MF. In the Gisela plastometer measurement method, the coal to be measured is loaded into a crucible equipped with a stirrer and is heated in a metal bath (solder bath), for example, at a heating rate of 3.0 ± 0.1 ° C./min. Be warmed. Conceptually, the softening of coal starts with the temperature rise, and the stirring rod starts to rotate along with this (the appearance of fluidity). And after showing the maximum number of rotations at the temperature peculiar to coal (equivalent to MF), re-solidification of coal starts, the number of rotations gradually decreases, and the rotation of the stirring rod completely stops at a predetermined temperature. These flow characteristics curves vary with the type of coal.

(Ii) Characteristics of blended coal Fig. 2 (B) shows the raw coal (standard coal), low-grade coal, and blended coal when blending low-grade coal with coking coal (standard coal) in this estimation method. A flow rate curve is shown. In addition, the maximum fluidity MFo of the raw coal (reference coal) is changed (decreased) to the maximum fluidity MFm of the coal blend produced by blending the low-grade coal (MF = 0). At this time, as will be described later, a log MFm value obtained by converting this MFm into a common logarithm, and a log MFm value simply estimated by weighted averaging of log MFo of raw coal and log MF (= 0) of low-grade coal When compared, it was found that there may be a large gap between the two. At the same time, the following findings were obtained.
(A) Δlog MF when the same low-grade coal is blended with different raw coal (reference coal) does not depend on the characteristics of the raw coal (reference coal) such as the type of coal and MF. Therefore, a common estimated value can be set for the same low-grade coal.
(B) Δlog MF when different low-grade coal is blended with the same raw coal (reference coal) is determined by the brand of the low-grade coal to be blended. Therefore, different estimated values can be set for the same raw coal (reference coal) by blending different low-grade coals.

[Procedure of this estimation method]
This estimation method basically includes the following five steps.
(1) Step of actually measuring the fluidity characteristic curve of reference coal prepared in advance (2) Step of setting MF of reference coal (3) Mixing low-grade coal prepared in advance with reference coal, Step of actually measuring MF from degree characteristic curve (4) Step of setting ΔlogMF for each low-grade coal from MF of actually measured blended coal (5) Step of estimating MF of actually used blended coal A procedure for estimating the MF of a typical blended coal will be described in detail.

(1) Step of actually measuring the fluidity characteristic curve of reference coal prepared in advance In order to verify in advance the characteristics of one or more low-grade coals that are actually planned to be blended, a reference coal is selected and Measure the information on charcoal fluidity. Specifically, a fluidity characteristic curve of the reference coal as shown in FIG. The standard coal is preferably a high-fluid caking coal so that the change in fluidity associated with the blending of the low-grade coal can be sufficiently verified. For example, caking coal having a high fluidity of logMF = 2 to 4 [logddpm] is preferable.

(2) Step of setting MF of reference coal Based on the fluidity characteristic curve obtained in (1) above, the maximum fluidity (MF) of reference high-grade coal as shown in FIG. 2 (A) is set. Specifically, the range from the zero base shown in FIG. 2A to the maximum value of the fluidity characteristic curve is set as the MF.

(3) A step of blending low-grade coal prepared in advance with reference coal and measuring MF from a flow characteristic curve of the blended coal With respect to one or more low-grade coal prepared in advance, at least two blending ratios are used. It mix | blends with the reference | standard coal of said (2), and the fluidity | liquidity characteristic curve of each combination charcoal is measured. Each MF is set from the actually measured fluidity characteristic curve.

(4) Step of setting Δlog MF for each low-grade coal from the measured MF of the blended coal From the MF of each blended coal measured and set in (3) above, Δlog MF for each low-grade coal Set. At this time, if the reference coal is a high-fluidity caking coal, it becomes a characteristic line similar to a linearly approximated characteristic line with the log MF of the reference coal as an intercept.

(5) Step of estimating MF of blended coal actually used MF of raw coal used actually and Δ set in (4) above for (planned) low-grade coal actually blended LogMF is used to estimate the MF (logMF) of the blended coal. The fluidity of blended coal accompanying blending of low-grade coal can be expressed by the following formula 1 as a general formula.
Y = S + α × X Equation 1
Where Y is the log MF of the blended coal
S is logMF of coking coal
α is △ logMF [1 /%] of low-grade coal
X is low-grade coal content rate [%]
In addition, when the range of MF (log MF) of blended coal is set in advance, the MF (log MF) of desired blended coal is set by setting the blending ratio of the low-grade coal that is actually blended (planned). ) Can be estimated. In addition, when it is difficult to set the MF (log MF) of the desired blended coal with the low-grade coal to be blended, an appropriate Δ is selected from the other low-grade coals for which Δlog MF is set in (4) above. A low-grade coal for which log MF is set is selected, and the MF (log MF) of the blended coal is estimated. Furthermore, when it is difficult to select low-grade coal, part of the caking coal used in the raw coal is transferred to caking coal with different fluidity, and the log MF at the time of blending the low-grade coal is set within an appropriate range. It is also possible.

<Verification of characteristics of coking coal, low grade coal and blended coal>
(I) Coal used for verification Table 1 shows the characteristics of coking coal (reference coal), low-grade coal, and blended coal used for verification of this estimation method. In the following, this estimation method including examples was used for verification.

(Ii) Verification of fluidity of coking coal (standard coal), low-grade coal and blended coal Using the raw coal (reference coal), low-grade coal and blended coal in Table 1 above, its fluidity characteristic curve was obtained, MF and log MF of raw coal (reference coal) and low grade coal were set. Table 2 below illustrates the flow rate measurement results when low grade coal A or low grade coal B is blended with raw coal J or raw coal K, and is illustrated in FIGS. The values in () below show the weighted average value of log MF = 0 for low-grade coal.

Based on the measurement results in Table 2 above, ΔlogMF of the coal blended with the low-grade coal is obtained. In FIG. 3 and FIG. 4, ♦ indicates the log MF of the coal blend when 1% or 3% of the low-grade coal A is blended with the coking coal (reference coal) J, L, K, and ■ indicates the coking coal (standard Charcoal) The log MF of blended coal when 1% or 3% of low-grade coal B is blended with L and K. As illustrated in FIGS. 3 and 4, when the fluidity log MF of the blended coal corresponding to the blending ratio of the low-grade coal is compared with each coal type and the low-grade coal, the above findings (a) and (b) are obtained. It can be verified quantitatively.
(A) As shown in FIG. 3 and FIG. 4, different coking coals having MFs of 1388 [ddpm] (log MF3.14), 949 [ddpm] (log MF2.98), 206 [ddpm] (log MF2.31) Reference coal) Δlog MF when low grade coal A is blended with respect to J, L and K are -0.096, -0.096 and -0.099, respectively, and raw coal (reference coal) It can be said that it does not depend on the characteristics of coal types, MF, etc. Further, Δ when low grade coal B is blended with different coking coals (reference coals) L and K having MF of 949 [ddpm] (log MF 2.98) and 226 [ddpm] (log MF 2.35). The log MF was -0.130 and -0.128, respectively, and similar results were obtained. A common estimate can be set for the same low-grade coal.
(B) As shown in FIG. 3, low grade coal B was blended with respect to the same raw coal (reference coal) with ΔlogMF of −0.099 when blended with low grade coal A. ΔlogMF in the case is −0.128, and ΔlogMF is determined by the brand of the low-grade coal to be blended. By blending different low-grade coals, different estimated values can be set for the same raw coal (reference coal).

<Verification of correction factors in estimation of MF of blended coal according to the present invention>
By the method as described above, it has become possible to estimate the MF of the blended coal efficiently by an unprecedented simple method. On the other hand, it was found that the MF of the blended coal depends on the brand of the low-grade coal to be blended, and a deviation between the estimated value and the actual measurement value occurs depending on the characteristics of the blended low-grade coal. Specifically, when five types of low-grade coals A to E as shown in Table 3 below were blended with raw coal (reference coal) and ΔlogMF of the blended coal was verified, estimated values and actual measurements shown in the same table were obtained. A value was obtained.

[Characteristic correction by oxygen content of low-grade coal]
From the verification results shown in Table 3 above, the fluidity of the blended coal depends on the brand of the low-grade coal to be blended, and the fluidity tends to decrease as the oxygen content of the low-grade coal increases. I understand. Specifically, as illustrated in FIG. 5, as the oxygen content of the low-grade coal increases, the setting of ΔlogMF related to the low-grade coal that is closer to the final stage of the fluidity estimation process of the blended coal is affected. Giving. At this time, as an actual correction curve, as illustrated in FIG. 6, a curve having a predetermined width (0.046 in the figure) of the characteristic line is used. Table 3 below illustrates the median, upper limit, and lower limit when the blending ratio of low-grade coal is 10 to 30%. Different predetermined widths are set depending on the coal type. This is because the low grade coal may not be the same brand when the oxygen content is different. That is, depending on the specific low-grade coal, the oxygen content rate is different, which may be one of the factors of fluctuation of Δlog MF due to the difference in brands.

This estimation method obtains the fluctuation of Δlog MF with respect to the oxygen content shown in FIG. 6 and corrects Δlog MF related to low-grade coal set in advance by the brand, thereby more accurately as in the examples described later. It became possible to estimate the MF of the blended coal.
Specifically, in the case of the oxygen content rate a, ΔlogMF is calculated based on the following formula 2, and is inserted into the above formula 1 to be corrected.
ΔlogMF = −0.0061 × a + 0.0135 Equation 2
Here, since the oxygen content is normally specified in the characteristic table of coal, actual measurement is not particularly required, and there is no inconvenience associated with correction. Further, when there is a coal quality notation as the industrial analysis value as described above, the oxygen content can be calculated by the following equation 3.
Oxygen content [%] = 100−elements C, H, N, S [%] (Formula 3)

[Characteristic correction due to volatile content of low-grade coal]
The volatile matter is an important factor in chemically evaluating the quality of coal as described above. From the verification results shown in Table 3 above, it can be seen that as the volatile content of low-grade coal increases, the fluidity of the blended coal tends to decrease. Also in this estimation method, it has been found that such tendency affects the low-log coal of Δlog MF of the blended coal. Specifically, as illustrated in FIG. 7, as the volatile content of the low-grade coal increases, the ΔlogMF of the blended coal is affected. This estimation method obtains the fluctuation of Δlog MF with respect to the volatile content shown in FIG. 7 and corrects Δlog MF related to low-grade coal set in advance by the brand, thereby more accurately blending as in the examples described later. It became possible to estimate the MF of charcoal. Note that the volatile content of the low-grade coal to be blended is normally specified in the characteristic table of the coal, so that no actual measurement is required, and there is no inconvenience associated with the correction.
Specifically, in FIG. 7, in the case of the volatile content b [%], ΔlogMF is calculated based on the following formula 4, and is inserted into the above formula 1 to be corrected.
ΔlogMF = −0.000313 × b ² + 0.0216 × b−0.413 Formula 4

<Example>
About the effectiveness of the above estimation method, the following content was verified.
[Example 1] Estimation of fluidity of blended coal when logMF of coking coal is set high [Example 2] Estimation of fluidity of blended coal when logMF of coking coal is set low [Example 3] ] Estimation of fluidity of blended coal when blended with non-flowable charcoal [Example 4] Low grade coal blended firing test using Δlog MF

[Example 1]
The fluidity of the coal blend was estimated when the log MF of the raw coal was set higher.
(I) Experimental condition log MF: Measure and set log MF and Δlog MF of coking coal under conditions of blending ratio of 5 to 10% of low grade coal A, B and C with respect to coking coal L of 2.98 Compared with the estimated value.
(Ii) Experimental results As shown in Table 5 below, it was found that for log MF of coal blend, the estimated value and the actually measured value were very consistent and the correlation was high. The excellent function of this estimation method is proved.

[Example 2]
The estimation of the fluidity of the blended coal when the log MF of the raw coal was set low was performed in the same manner as in Example 1 above (i) the raw coal M having a low experimental condition log MF (around 2.00) and Using coking coal N, low grade coal D, low grade coal E, low grade coal E and low grade coal F are used, and logMF and ΔlogMF of raw coal are measured and set under the conditions of 1 to 10% of the blending ratio. And compared with the estimated values.
(Ii) Experimental results As shown in Table 6 below, even when the log MF of the raw coal is set low, the estimated value of the log MF of the coal blend is in agreement with the measured value.

Example 3
In place of the low-grade coal in Examples 1 and 2 above, the fluidity of the coal blend was estimated when blending a non-fluid carbon material with the raw coal (i) low experimental condition log MF (around 2.00) ) Using raw coal M and raw coal N, using low-grade coal G and low-grade coal H as coal types of non-fluid coal, measured logMF and ΔlogMF of raw coal under the condition of 10% blending ratio , Set and compare with estimated values.
(Ii) Experimental results As shown in Table 7 below, even when using coals such as anthracite and low grade coal G and low grade coal H that are not softened and melted, an estimated value and The measured values are very consistent, and it was found that the fluidity of the blended coal can be estimated.

Example 4
Using Δlog MF, a coking strength was verified by conducting a firing test of the coal blended with low-grade coal.
(I) Experimental conditions Using mixed caking coal (I) as a raw coal and blended caking coal (B) in which a part of the caking coal is replaced with a caking filler, the low-grade coal type is defined as low-grade coal F, The log MF and Δlog MF of the blended caking coal (I) and the blended caking coal (B) were measured and set under conditions of a blending rate of 0 to 10%, and compared with the estimated values. Moreover, the powder ratio and coke strength after coke dropping at this time were compared.
Here, the flow rate decreasing gradient of the low-grade coal F was ΔlogMF = −0.12 [logddpm /%]. In addition, the blended caking coal (b) is calculated in advance by using the previously described log MF estimation formula (formula 1), and the log MF at the time of blending the low grade coal F. Is a high fluidity blended coal in which the blending ratio of the high fluidity coal is increased so as to be 2.0 (a coke strength stable region), and the measured log MF = 2.66.
(Ii) Experimental Results As shown in Table 8 below, the estimated value of the log MF of the coal blend using Δlog MF matches the measured value well. If this estimated value is adjusted to the same level as the base, the coke strength is restored.

<Method of blending raw materials for coke production using this estimation method>
As described above, the present estimation method can accurately estimate the MF of blended coal even when various raw coals and low-grade coals are used. Therefore, by using this estimation method, it is possible to appropriately adjust the maximum fluidity of the coke production raw material to be produced. In other words, based on the maximum fluidity of the coking coal that is actually used and the ΔlogMF related to the low-grade coal blended with it, the grade coal blended with the coking coal so as to have an appropriate fluidity range. By setting the blending ratio, an efficient and excellent blending method of raw materials for coke production (hereinafter referred to as “the present blending method”) can be obtained.

<Method of blending raw materials for coke production using this estimation method>
Moreover, the coal blend produced by this blending method has excellent caking properties or fluidity. Such characteristics are sufficient to ensure suitability as a raw material for coke production, and it is useful to use the blended coal thus produced as a raw material for coke production. That is, as described in detail in the explanation of the estimation method, the blending ratio of the low-grade coal to be blended with the raw coal is 0.1 to 10%, and the log MF is 2 to 3 with respect to the MF of the blended coal. It became possible to secure a raw material for producing coke that was excellent in strength and caking.

DESCRIPTION OF SYMBOLS 1 Coal carrier 2 Coal storage place 3 Mixing tank 4 Crushing equipment 6 Coke oven 6a Coalbin 6b Charged vehicle 6c Extruder

The cohesiveness of such coal is determined by properties such as fluidity, expansibility, and tackiness, but fluidity greatly affects the coke strength. For this reason, grasping the maximum fluidity of blended coal (hereinafter sometimes referred to as “MF (Maximum Fluidity)”) is an important factor for producing high-strength coke. Conventionally, the MF of blended coal has been estimated by the weighted average value of each MF of blended simple coal. However, the flow start temperature (ST), maximum flow temperature (MFT) and solidification temperature (FT) of each of the blended plain coals are different. Therefore, the weighted average value of each coal simple MF and the MF of blended coal do not match. The estimated value of the common logarithm value (hereinafter sometimes referred to as “logMF”) of the maximum fluidity of the blended coal, which has been conventionally performed, is higher than the actually measured value. Such a tendency becomes more prominent as coal having a higher MF is used, which has been a major cause of lowering the estimation accuracy of coke strength (for example, Patent Document 1 [Prior Art] and [Invention try to solve]. Issue)].

<Method for estimating MF of blended coal according to the present invention>
In this estimation method, the characteristics of the blended coal that is a raw material for coke production supplied in the coke production process is estimated based on the characteristics of the raw coal and the characteristics of the low-grade coal. That is, this estimation method can estimate MF of coal blend simply and efficiently by the procedures (1) to (5) described later based on the following knowledge.
(A) The fluidity decrease gradient (hereinafter sometimes referred to as “Δlog MF”) accompanying the blending of low-grade coal is less dependent on the coal type and characteristics of the raw coal (reference coal).
(B) Δlog MF of low grade coal is unique to the brand of low grade coal.
Here, “log MF” indicates a common logarithm of the maximum fluidity (MF), and is used in actual evaluation. “Δlog MF” indicates the gradient (fluidity decreasing gradient) .

Claims (5)

When producing raw materials for coke production whose main component is blended coal produced by blending low-grade coal with raw coal,
One or more types of coking coal are selected in advance as a reference coal, a range of an appropriate fluidity of the reference coal, a fluidity characteristic curve with respect to the temperature of the reference coal, and the reference based on the fluidity characteristic curve The maximum fluidity of charcoal is obtained, and for one or more low-grade coal blended, the fluidity of the low-grade coal based on the change in the maximum fluidity of the reference coal relative to the blending ratio of the low-grade coal While finding the decline slope,
Based on the maximum fluidity of the raw coal actually used and the flow rate decrease gradient of the low-grade coal actually blended, the blending ratio of the low-grade coal blended with the raw coal A method for estimating the maximum fluidity of a raw material for coke production, characterized by estimating the maximum fluidity of a blended coal in which the low-grade coal is blended with charcoal.   Fluctuation of the fluidity lowering gradient with respect to the oxygen content of the low-grade coal to be blended is obtained, and the fluidity-decreasing gradient according to the low-grade coal used is corrected by the oxygen content of the low-grade coal. The method for estimating the maximum fluidity of a raw material for producing coke according to claim 1.   Fluctuation of the flow rate decrease gradient with respect to the volatile content of the low-grade coal to be blended is obtained, and the fluidity decrease gradient according to the low-grade coal used is corrected by the volatile content of the low-grade coal The method for estimating the maximum fluidity of the raw material for coke production according to claim 1 or 2.   Using the estimation method of the maximum fluidity of the raw material for coke production according to any one of claims 1 to 3, based on the maximum fluidity of the raw coal actually used and the fluidity decrease gradient related to the low-grade coal used A method for blending raw materials for coke production, wherein the blending ratio of the low-grade coal blended with the raw coal is set so as to fall within the proper fluidity range. A raw material for coke production mainly composed of blended coal produced by blending low-grade coal with coking coal, the blending ratio of the low-grade coal of 0.1 to 10%, the maximum fluidity of the blended coal The raw material for coke production produced by the method for blending raw materials for coke production according to claim 4, which has a common logarithm value of 2 to 3.

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