JP5749952B2 - Method for estimating and evaluating the degree of coalification of reformed coal - Google Patents

Description

  The present invention relates to a method for estimating and evaluating the degree of coalification of reformed coal. More specifically, the present invention relates to estimation of the degree of coalification of a blend in which heavy oil rich in aromaticity is blended with powdered low-coalizing coal. And an evaluation method. The present invention is a modification material particularly useful in the implementation of a technique using non-slightly caking coal modified with heavy oil and converted to caking coal as raw coal used in the manufacture of iron-making coke. Estimation and evaluation of coalification degree of heavy oil blended non-slightly caking coal that can easily and accurately estimate the degree of coalification of blends of heavy oil and noncohesive coal as raw coal Regarding the method.

  In recent years, non-caking coal or slightly caking coal classified as low-carbonized coal, which has not been used in the past, has been used as a raw material for coke for steelmaking for the purpose of effectively utilizing resources (summarized these). Active use of non-slightly caking coal).

In addition, although the term in this invention is based on JISM0104 (coal utilization technical term), the definition of main terms is as follows.
・ Coking coal: Coal which shows caking property in classification according to the property of coal.
・ Slightly caking coal: Coal that shows slightly caking in the classification according to the properties of the coal.
-Non-caking coal: Coal that does not show caking in the classification according to the properties of the coal.
・ Caking property: A general term for properties (stickiness, fluidity, expansibility, etc.) observed in the plastic stage when coal is carbonized.
-Stickiness: The property of softening and melting and coalescing when coal is carbonized.
Regarding the caking property and adhesiveness, a flow rate is measured by using a Gieseler plastometer (JIS M8801 (coal testing method)) as a measuring device. The fluidity is usually expressed in ddpm units. The maximum fluidity (MF) is used as the characteristic value of coal. Conventionally, this is often called fluidity. A common logarithm of ddpm may be used.
Reflectivity: When light is incident on the surface of an object, it is expressed as a percentage by the ratio of the energy of the reflected light and the energy of the incident light.
In the case of coal, according to JIS M 8816, light at 546 nm is used, the oil immersion maximum reflectance of the fine structure component is measured under a microscope, and the average maximum reflectance is calculated. Usually, when referring to the reflectance of coal, it often means the oil immersion maximum reflectance of vitrinite. Represents the degree of coal coalization. The display is represented by Ro or Romax.

  The above is the definition of JIS M0104, but the coal is actually considered as follows. The caking coal (usually referred to as raw coal) is softened and melted at a temperature of 350 to 500 ° C. and heated to a temperature higher than that, and finally becomes a coke. Non-coking coal does not show a molten state as it is heated and remains in a solid state to become carbon (usually referred to as char), and does not become lump coke even when heated. Slightly caking coal is located between caking coal and non-caking coal. Currently, in the steel industry, non-caking coal is caking as being located between caking coal and non-caking coal. Used in a form that is used in combination with charcoal. Because caking coal is expensive and produces less than non-caking coal, non-slightly caking coal can be easily converted to caking coal to promote more aggressive use. There is a strong demand for technology that can be modified. Here, non-slightly caking coal is defined in the steel industry as Ro is 0.85 or less and log MF is 2.5 or less, or Ro is 0.85 or more and log MF is 0.5 or less.

  There are various proposals for converting non-slightly caking coal to caking coal, but neither method can produce coke with high strength completely with non-slightly caking coal. According to the report on the conventional method, it is said that the ratio of the non-slightly caking coal is about 20-50% at most, and the ratio is actually lower.

  In order to solve such problems, the present inventors have already made 350 to 450 ° C. in a state where a dry powdery low-coal coal and a petroleum-based or coal-based reformer coexist. The technique which heats at the temperature of (degreeC) and reforms a low-coalification degree coal is proposed (refer patent document 1 and patent document 2). As a result of repeated investigations on low-rank coal to be reformed and heavy oil as a reforming agent, according to such technology, reforming during the production of coke for steelmaking By using heavy oil rich in aromaticity as a material, it is possible to modify non-slightly caking coal and efficiently convert it into caking coal equivalent.

  Specifically, the present inventors reduced the ratio of the reforming material blended with respect to the non-slightly caking coal, improved the reforming speed, selected the reforming material that is as cheap as possible and excellent in reforming efficiency, The following results have been obtained by examining the selection of non-slightly caking coal useful as raw material coal. First, the present inventors have found that, for example, a heavy oil such as SDA pitch produced as a by-product in a petroleum refining process is effective as a cheaper and higher softening agent. More specifically, heavy oil having a softening point of 200 ° C. or lower and 80 ° C. or higher, a QI of 10% or lower, and an aromatic index fa of 0.3% or higher is useful. Furthermore, as the properties of the raw material coal, it is effective to use a low-coalizing non-coking coal having a Ro of 0.85 or less and a log MF of 2.5 or less.

JP 2009-132895 A International Publication No. 2010/090230 Pamphlet

  However, even if the present inventors can convert non-slightly caking coal to caking coal by the method as described above, there is a new method that there is no reliable method for judging and evaluating the converted caking coal equivalent. We came to recognize problem. That is, unless it can be determined that the non-slightly caking coal can be converted to caking coal, smooth operation becomes difficult in practical use. In other words, the current evaluation technology cannot accurately evaluate the effects of the type of non-slightly caking coal used, the type of heavy oil, and the amount of blended oil, making it difficult to design optimal coke production raw materials. There are challenges.

  Therefore, the object of the present invention can accurately confirm the reforming effect when the heavy oil is added to the non-slightly caking coal to reform the coal. That is, it is providing the estimation and evaluation method of the degree of coalification of reformed coal which makes it possible to estimate and evaluate the degree of coalification in these blends.

  The above object is achieved by the present invention described below. That is, the present invention is a method for estimating and evaluating the degree of coalification of reformed coal used in the method for reforming low-degree coal for converting low-degree coal to a caking coal equivalent. X-ray diffraction was performed on a standard sample obtained by heat-treating four or more types of coals having different degrees of coalification and holding the coal at a temperature of 1,000 ° C. or higher with the air turned off. The regression line of Ro-N or Ro-La is obtained in advance from the average number of layers N obtained by the above or the crystallite size La of the layer surface and the degree of coalization Ro measured for each coal, and the powdery low A molded body made of a mixture obtained by mixing coal-modified coal and heavy oil rich in aromaticity as a modifier is prepared, and the molded body is subjected to the same heat treatment as that of the standard sample. Obtain N or La for the measurement sample obtained by X-ray diffraction, and obtain it as described above. Using a regression line provides an estimate and evaluation method of coalification degree of reforming coal and obtaining coal degree Ro from N or La in the mixture.

  As a preferred embodiment of the method for estimating and evaluating the degree of coalification of the above-mentioned modified coal, the molded body is appropriately prepared by adding heavy oil rich in aromaticity to a dry and pulverized low-coalized coal sample. It may be a molded body formed by molding a blended material in an amount, or the low-coalizing coal may be non-slightly caking coal.

  According to the present invention, it is possible to accurately confirm the reforming effect when reforming coal by adding heavy oil to non-slightly caking coal, the degree of coalification in these blends A method for estimating and evaluating the degree of coalification of reformed coal that makes it possible to reliably estimate and evaluate the above is provided. More specifically, according to the present invention, it is possible to provide a technique that can accurately display the degree of coalification and the caking property of the modified coal used as the raw coal during coke production.

It is an example of the regression line of Ro-N used in the estimation and evaluation method of the degree of coalification of the reformed coal of this invention. It is a schematic block diagram at the time of industrializing the coke manufacturing method which can utilize this invention.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.
First, a conventional coking property evaluation method will be briefly described. The evaluation of coking property is based on the principle that the target coal is carbonized to coke and its strength is measured. So far, the evaluation method of coking coal has been carried out from the degree of coalification and cohesiveness of coking coal. Among the most prominent methods, the degree of coalification is determined by the reflectance Ro of the vitrinite of the coal, and the caking property is evaluated by the maximum fluidity (MF) of the Gieseller Plastometer. In the method for estimating and evaluating the degree of coalification of the reformed coal according to the present invention, the degree of coalification (Ro) of the reformed coal can be estimated.

  In the reforming method of low-carbonized coal for converting low-carbonized coal to be used by the present invention into caking coal equivalent, heavy oil (hereinafter, (Also referred to as pitch), and then molded, charged into a coke oven and heated, and the effect of the reforming is the degree of coalification Ro and caking MF during non-slightly caking coal reforming by pitch. If you know, you can judge. Here, the caking property MF can be easily found by measuring the MF of the mixed molded product of pitch and dry and pulverized non-fine caking coal. However, the method for estimating the value corresponding to Ro is problematic.

  Here, as one of the conventionally known evaluation methods for coal, for the purpose of examining the microstructure of heat-treated coal, after heating the coal to 1,000 ° C. or higher, X-ray diffraction is performed, and the average total product number N And crystallite size La (expressed in nm). In addition, there is an example in which the degree of coalification is expressed by the carbon content (C%) of coal, and Ro is obtained from C%. On the other hand, the present inventors, in the process of studying the conversion of low-coalized coal to caking coal equivalent, N and La of the coal obtained by performing X-ray diffraction, and the coal of the coal When the relationship with the degree Ro was determined, they were found to show a very good correlation with each other. And based on such knowledge, the present inventors are able to convert the low-carbonized coal developed by the present inventors into caking coal equivalent, powdered low-carbonized coal, With regard to a mixture (compound) obtained by mixing a heavy oil rich in aromaticity as a modifier, whether or not it is possible to estimate and evaluate the degree of coalification was studied earnestly. As a result, the present inventors have found that a technique for estimating and evaluating the degree of coalification of reformed coal can be established by obtaining a value corresponding to Ro from the N value or La value. Here, when calculating | requiring La, after carbonizing a raw material to 1,000 degreeC or more, it is necessary to decalcify a carbide | carbonized_material using HCl and to make it 2% or less. This is because the ash content needs to be removed from the measurement sample in order to reduce the measurement accuracy. For this reason, it can be said that using the N value is simpler as an estimation and evaluation method than using the La value.

  In the present invention, first, four or more types of coals having different degrees of coalification are used, and the coal is coke obtained by heat-treating the coal at a temperature of 1,000 ° C. or higher while keeping the air out. From the average number N of layers obtained by X-ray diffraction or the crystallite size La obtained by X-ray diffraction and the degree of coalization Ro measured for each coal, a regression line of Ro-N or Ro-La is obtained in advance. I ask for it. On the other hand, a molded product made of a mixture (compound) obtained by mixing dry powdery low-coal coal and heavy oil rich in aromaticity is prepared. The same heat treatment as in the case of the standard sample is performed, and the obtained sample is used as a measurement sample, and N or La is obtained for the sample by X-ray diffraction. Then, by using the regression line obtained above, the degree of coalification is accurately estimated and evaluated for the modified coal by determining the degree of coalification Ro from the N value or La value measured for the molded body. Is possible.

  In the above, the coal type used when obtaining the regression line may be four or more, which are different in degree of coalification, but more preferably five or more if possible. This is to increase the accuracy of the regression line.

  Furthermore, in the present invention, as a measurement sample to be evaluated, a molded body made of a blend formed by blending heavy oil rich in aromaticity with low-coalized coal is prepared, and the molded body Then, a measurement sample heated to coke is prepared under the same temperature condition as the regression line was obtained. For the sample made of the molded body thus obtained, the average number N of layers or the crystallite size La on the layer surface is obtained by X-ray diffraction. In the present invention, there is one feature in the above-mentioned sample preparation, which is obtained by forming a molded body, heating it to coke, and performing X-ray diffraction on this. Specifically, a dry-ground coal sample is formed by molding a mixture obtained by mixing an appropriate amount of heavy oil rich in aromaticity, and the molded body is heated to prepare a measurement sample. Is preferred. Since the present invention relates to a method for estimating and evaluating the degree of coalification of reformed coal, the amount of heavy oil in the above constitutes the reformed coal to be tested. However, it is an appropriate amount necessary for reforming.

  According to the present invention, the above-mentioned molded body composed of a blend obtained by mixing dry and pulverized non-fine caking coal with pitch is subjected to X-ray diffraction and converted to a high quality caking coal equivalent to obtain an N value. Or Ro is calculated | required by the simple method of calculating | requiring La value. In addition, about MF value, it calculates | requires easily by MF measurement of the compound for producing a molded object. Therefore, by the above simple method, Ro and MF of the modified caking coal equivalent are known, and from this value, the evaluation of the mixture of the dry and pulverized non-caking coal and pitch as a coke raw material can be determined. .

  We have commercialized a method for reforming low-coalification coal to convert low-coalification coal to caking coal equivalent to which the method for estimating and evaluating the degree of coalization of the modified coal of the present invention can be applied. An example image of the time is shown in FIG. FIG. 2 shows the cast charcoal method. Briefly, non-coking coal is dried and pulverized at the same time by a drying pulverizer. The pulverized product is collected in a cyclone, transported on a screw conveyor, heated modifier (heavy oil) is added and mixed well in a kneader, and then a 20 mm briquette is produced in a briquette machine. To do. The product briquette is charged into a coke oven and heated to modify the non-coking coal. Further, the same result can be obtained by simply blending the coke oven without the dry pulverization and molding as described above. However, in this case, the amount of heavy oil for reforming increases.

  The method for reforming low-coalification coal is performed in the manner as described above, and coke is produced. If the evaluation method of the present invention is introduced to the evaluation of the molded product charged in the coke oven at that time, As a result, it is possible to continuously and reliably use the modified coal that is a caking coal equivalent.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to these. Unless otherwise specified,% is based on mass.

[Example 1]
As described below, the Ro value (average reflectance = degree of coalification) of the modified coal is estimated from the N value (average number of layers) of the pitch-mixed coal of non-slightly caking coal and pitch as raw materials. I verified that it was possible.

  In Table 1, Ro (average reflectance) measured by a standardized method for six types of coals A to G having different degrees of coalification used for performing regression analysis to obtain a regression line and The analytical values of MF (Gieseller maximum fluidity) are shown respectively. Moreover, the N value (average number of lamination | stacking) of the coal each used as the raw material was calculated | required by carrying out the X-ray diffraction about the sample obtained by performing a baking process in the following procedure, and coking. In Table 1, the measurement results of the N value thus obtained are also shown. Specifically, for each coal sample, using an electric furnace, the temperature was raised to 1,000 ° C. at a rate of 10 ° C./min under an argon flow of 0.1 L / min, held at that temperature for 1 hour, and then The sample was naturally cooled to room temperature to obtain a sample for measurement, and the sample was subjected to X-ray diffraction to obtain an N value.

  Of the coals used to determine the regression line, each of A, B and C coals having a low Ro value was used, and 10% of the characteristic pitches shown in Table 2 were added and mixed. I got coal. Further, a coal sample for reforming was prepared using each of the obtained pitch-mixed coals. Specifically, first, the A, B, and C coal samples were shrunk and then prepared into samples of 35 mesh or less, which were dried under reduced pressure at room temperature for 72 hours. The obtained dried and pulverized coal samples were each uniaxially molded with a pitch of 10%, and the molded body was used as a sample for modification.

  The modifying pitch-mixed coals A to C obtained as described above were subjected to the following firing treatment to be coke to prepare samples for X-ray diffraction. That is, the pitch mixed coal for reforming obtained above is taken in an alumina boat and heated to 1,000 ° C. at a rate of 10 ° C./min under a flow of argon at 0.1 L / min using an electric furnace. Then, after maintaining at that temperature for 1 hour, the sample obtained by naturally cooling the sample to room temperature was used as a sample for X-ray diffraction. These samples were subjected to X-ray diffraction to evaluate the number of condensed polycyclic aromatic laminates. The obtained values are shown in Table 3. Moreover, about the pitch mixing coal AC before uniaxial shaping | molding by the above, the flow rate tester was used and the Gieseler highest fluidity was measured. In Table 3, the obtained MF values are also shown.

  As a result, it can be seen from Tables 1 and 3 that the average number of layers N of the non-slightly caking coal as the raw material and the pitch-mixed coal tends to increase slightly by adding pitch. It was. Moreover, as shown in Table 3, by using pitch mixed coal in a state where pitch is added to coals A to C having a low degree of coalification, the MF value is remarkably increased in any coal. We were able to confirm that it was quality. In particular, in the pitch mixed coal A, a surprising value exceeding the measurement limit was confirmed.

Each analysis value shown in Table 1 was examined. As a result, a clear correlation was recognized between the values of Ro and N shown in Table 1, and a regression line was obtained by performing regression analysis on this relationship. As a result, the relationship between them was as shown in the following formula (1). It is confirmed that the following formula (1) is statistically 1% significant between Ro and N. This means that if the following formula (1) is used, Ro can be estimated from the N value obtained by X-ray diffraction.
Ro = 0.84N-1.48 (1)

  Therefore, the above-described formula (1) obtained by regression analysis was used to evaluate the modified pitch-mixed coal. That is, the average number of layers N obtained by X-ray diffraction analysis performed on a sample obtained by firing and coking pitch-mixed coals A to C shown in Table 3 (reproduced in the upper part of Table 4), the above formula (1 ) Was used to calculate Ro for these coals A to C, respectively. The results are shown in Table 4. The Ro values (calculated values from the regression line) in Table 4 are higher in each case than the Ro values of the raw material coal shown in Table 1, and the pitch is mixed. It was clearly shown that the reforming treatment improved the degree of coalification.

[Example 2]
As described below, it is possible to estimate the Ro value (average reflectance = degree of coalification) of the modified coal from the La value of pitch-mixed coal of non-slightly caking coal and pitch as a raw material. I verified it.

  In this example, the La value was used in place of the N value used in Example 1. The pitch used for the study is the same as in the first embodiment. In addition, analysis values of coal used for the development of the regression line are as shown in Table 5. Table 5 shows Ro (average reflectance) and MF (Gieseller maximum fluidity), respectively, for four types of coal used in different stages of coalification.

  In the measurement of La value, the coal shown in Table 5 was coked and then deashed to reduce the ash content to 2% or less. At this time, coking was performed by raising the temperature up to 1,000 ° C. at 3 ° C./min. And La (nm) was measured by X-ray diffraction. The values are as follows.

From the Ro in Table 5 and La (Å) in Table 6, the regression line was as follows.
Ro = 0.98La-1.068 (2)
The coal A used in Example 1 was blended with 10% of the same pitch as used in Example 1, and was molded in the same manner as described in Example 1 and then calcined and coked to obtain La of 19.40 ( I) (= 1.940 nm). This coke has been decalcified. Using this La value, Ro was found from the regression line equation (2) obtained above, which was 0.83, which was the same as the case of estimation using the N value performed in Example 1.

Claims (3)

A method for estimating and evaluating the degree of coalification Ro of reformed coal used in a method for reforming low-degree coal to convert low-degree coal to a caking coal equivalent,
X-ray diffraction was performed on a standard sample obtained by heat-treating four or more kinds of coals having different degrees of coalification Ro in stages and maintaining the coal at a temperature of 1,000 ° C. or higher with the air turned off. The regression line of Ro-N or Ro-La is obtained in advance from the average number of stacked polycyclic aromatics N obtained by the above or the crystallite size La of the layer surface, and the degree of coalification Ro measured for each coal. Every
A molded body made of a mixture obtained by mixing powdery low-coalizing coal and a heavy oil rich in aromaticity as a modifier is prepared. N or La is obtained by X-ray diffraction for a measurement sample obtained by the same heat treatment, and the degree of coalification Ro is obtained from N or La of the mixture using the regression line obtained above. A method for estimating and evaluating the degree of coalification Ro of peat. 2. The molded body according to claim 1, wherein the molded body is a molded body obtained by molding a blend of dry and pulverized powdery low-coalized coal sample with an appropriate amount of heavy oil rich in aromaticity. Of estimating and evaluating the degree of coalization Ro of the modified coal. The method for estimating and evaluating the coalification degree Ro of the reformed coal according to claim 1 or 2, wherein the low coalization degree coal is non-slightly caking coal.

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