JPH0214398B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] This invention provides a method for controlling the types and/or blending ratios of a plurality of coking coals constituting the coke oven coal when carbonizing the coke oven coal to produce coke of a predetermined strength. Regarding methods for managing. [Conventional technology] For blast furnace coke, coke strength, particle size,
Stable quality is required in terms of porosity, etc.
In order to produce coke of stable quality, it is necessary to manage the mixture so that the quality of the coke oven charging coal made of a plurality of raw coals satisfies a certain standard. By the way, in Japan, a wide variety of raw material coals are imported and these are appropriately blended to prepare coke oven charging coal. To prepare this coke oven charging coal, usually 20 to 30 brands of coking coal are secured, and 10 to 20 brands of coal are mixed to prepare the coke oven charging coal. In addition, the composition of several brands of raw coal is changed about once every two to three days. However, the properties of coal vary depending on the country of origin, coal mine, coal seam, etc., and in order to produce coke of stable quality, it is necessary to make full use of raw material coal blending technology to produce coke of constant quality. It has become an essential condition to prepare the coal charged in a coke oven in such a way that it can be used in a coke oven, and several methods have been proposed in the past to find the optimum conditions for this coal blend. Such conventional methods include, for example, determining the reflectance distribution of vitrinite, which is the main component of coal, analyzing the coal structure, and determining the optimal blending ratio of each brand of coking coal from the results; The flow rate and its vitrinite reflectance distribution are determined, and the optimal blending ratio of each brand of coking coal is determined from the results.The total expansion rate of the coking coal is determined, and an industrial analysis is performed, and the results are used to determine the optimum blending ratio of each brand of coking coal. Methods for determining the optimal blending ratio have been proposed. [Problems to be Solved by the Invention] However, in the first method using the reflectance distribution of vitrinite and the coal structure analysis, it is necessary to measure the reflectance of the coal and judge the structure using a microscope. In addition to being laborious, although it is effective for classifying and evaluating a single piece of coal, there are problems when measuring coal charged in a coke oven that contains multiple coking coals, and calculations and analyzes are complicated. There is also the problem that there is. In addition, in the second method, which uses the maximum fluidity and the reflectance distribution of vitrinite, as in the first method, it is necessary to measure the reflectance of the coal and judge the structure using a microscope. There is a problem in that it is troublesome, and there is a problem in measuring the coal charged in a coke oven, and the calculation and analysis are complicated, making it unsuitable for daily coal blend management. Furthermore, the third method, which uses the total expansion rate and industrial analysis, has the advantage that the test to determine the index is relatively easy; however, it has no additivity to the total expansion rate, and other There is a problem in that it is inappropriate for blending control of coke oven charging coal prepared by blending raw material coal. Therefore, each of the conventional methods has its advantages and disadvantages, and even if one method is adopted, it is only for reference; in reality, the current situation is that we rely on experience and intuition. be. [Means and effects for solving the problems] In view of this point of view, the present invention provides a method that allows coal blending management to be performed as efficiently as possible, and also allows finding truly optimal coal blending conditions. When preparing coke oven charging coal by determining the types and/or blending ratios of multiple raw material coals, the solidification temperature and maximum fluidity of each raw material coal are measured in advance, and the coke oven charging coal is The average value of the solidification temperature, the variation in solidification temperature, and the average value of the maximum fluidity of each raw material coal are calculated by considering the blending ratio of This is a blending control method for coal for coke production in which the correlation between the average value and coke quality is determined in advance and the coking ability of coal charged in a coke oven is evaluated based on this correlation. The raw material coal to which the present invention is applied may be any coal that can measure the solidification temperature and maximum fluidity used in calculating the index required to evaluate coking property, and Coal, etc. whose solidification temperature and maximum fluidity can be estimated by conventionally known estimation methods even if they cannot be directly measured, or coal whose solidification temperature and maximum fluidity can be measured by changing test conditions. is also included. The basis on which the present inventors adopted the above three indicators as indicators for evaluating the coking property of coal charged in a coke oven will be explained below. Since coal particles fuse together to form lump coke, in order to elucidate the mechanism of coke strength development, it is important to understand how the adhesion state after carbonization at the interface between different types of coal differs from the properties of the mutual coal. It is first necessary to clarify whether there is a relationship. Therefore, for each of the above-mentioned raw material coals used to prepare coke oven charging coal, commonly used coal is defined as the reference coal and other blended coals are defined as the test coal, and this reference coal and test coal are used as the reference coal. The test furnace is charged in layers so that the ash is located on the furnace wall side and carbonized, and the state of adhesion between the reference coal and the test coal in the obtained coke is observed and evaluated using a microscope. Since the adhesion state between the two types of coal, that is, the reference coal and the test coal, differs depending on which of them is located on the furnace wall side, it is preferable to select two or more types of coal as the reference coal. . To evaluate the adhesion state between the reference coal and test coal, for example, when observing the state of the interface of the obtained coke under a microscope, it is found that the state is almost the same as the voids observed in the reference coal and test coal. "Adhesive state" where voids are distributed on the interface and the two are firmly adhered,
It is classified into three stages: a "void state" in which more voids are distributed on the interface and insufficient adhesion, and a "broken state" in which there are breaks in the interface and insufficient adhesion. To explain this using a concrete example, for example,
Nine brands of raw material coal a to i were used, and the maximum fluidity (MF) and solidification temperature (S) of each raw material coal were measured by a method using a Gieseler plastometer (JIS M8801). Two types of coal, for example, a and b, are used as the reference coal, and for each reference coal a or b, another coking coal is used as the test coal, creating 16 sets of reference coal and test coal, and for each of these sets. The above-mentioned reference coal is packed in layers in a test furnace so that it is located on the furnace wall side, and carbonized, and the adhesion state between the reference coal and test coal in the obtained coke is observed with a microscope, etc., and the "adhesion state" is determined. As shown in Figure 1, the adhesion state between the reference coal and the test coal is determined by the solidification temperature between the reference coal and the test coal. If the graph is plotted on a graph with the horizontal axis representing the difference (ΔS) and the vertical axis representing the maximum fluidity (MF) of the test coal, it can be seen that the mutual relationship between ΔS and MF indicates a region where the adhesion is sufficient and strong. and weak areas with insufficient adhesion. In other words, if the maximum fluidity (MF) of the test coal is constant, the adhesion state between the reference coal and the test coal is determined by the absolute value of the solidification temperature (S) difference (ΔS) centered on the value 0. The larger the coal becomes, the more brittle it becomes, and if the difference (ΔS) in solidification temperature (S) is constant, the smaller the maximum fluidity (MF) of the test coal, the more brittle it becomes. In this way, whether the physical adhesion between coal particles is sufficient or insufficient can be explained using two indicators, ΔS and MF. However, whether the strength of the bonding surface is large or small is a different matter, and it is necessary to introduce the parameter of the degree of coalification, but in general, there is a correlation between the degree of coalification and the solidification temperature, so the strength of the bonding surface S is adopted as a factor. Although the above results are for a combination of two types of coal, the above theory can also be applied to the case of actual coal charged in a coke oven, which is a mixture of many types of coal. In other words, the difference (ΔS) in solidification temperature (S) between the reference coal and the test coal obtained in the case of a combination of two types of coal is determined by the solidification temperature (ΔS) of each raw material coal in the coke oven charging coal. S) variation (VST)
At that time, the blending ratio of each coking coal in the coke oven charging coal is considered as the contribution rate,
In addition, regarding the maximum fluidity (MF) of each test coal used in the case of a combination of two types of coal, it is considered that there is an equal probability of which side will be on the furnace wall side in the case of a mixed system. Coal is evaluated based on the average value (MF) of the maximum fluidity (MF) of each coking coal, and at that time, the blending ratio of each coking coal in the coal charged in the coke oven is considered as the contribution rate. moreover,
To quantitatively evaluate the adhesive strength between raw coals, an evaluation index of the degree of coalification is required, and the average reflectance of vitrinite, which is commonly used as an index, is determined by the solidification temperature (S). Furthermore, since the solidification temperature (S) reflects the actual coke strength well, the solidification temperature (S) of each raw material coal is used as an evaluation index of the degree of coalification in coke oven charging coal. The average value (ST) is used for evaluation, and at that time, the blending ratio of each coking coal in the coal charged in the coke oven is considered as the contribution rate. The average value of solidification temperature (STI) and its variation (VST) and the average value of maximum fluidity (MF) are calculated using the following formulas. STI=ΣSχ／100 ……(1) S: Solidification temperature of each raw material coal χ: Mixing ratio of each raw material coal (%) VST=√ ……(2) Y=[ΣS ² χ−(ΣSχ) ² /100 ] / 100 MFI = ΣFχ / 100 ... (3) F: MF (logDDPM) χ: Mixing ratio of each raw material coal (%) The average value of the maximum fluidity index (MFI) is based on the fact that coal particles adhere to each other. Although it is necessary to have a large MFI in order to achieve this, there is an optimal value in terms of coke strength. Also, the average value of solidification temperature (STI) as an index
and its variation (VST) have an inverse relationship to the adhesion strength between coal particles, and the smaller the value of the variation in solidification temperature (VST), the better the adhesion state between coal particles. Regarding the average temperature value (STI), the larger the value, the better the adhesive strength when coal particles adhere. Therefore, the relationship between the value obtained by dividing the above solidification temperature variation (VST) by the average solidification temperature value (STI) (VST/STI = VSTI) and the adhesive strength between coal particles becomes smaller as the above VSTI value becomes smaller. The relationship is such that the adhesive strength between coal particles is improved. Thus, STI, VST and
By using the three indicators of MFI, it is possible to evaluate the adhesive strength between coking coals, which is not only an excellent indicator for coal blend control, but also can be easily performed using a single device, such as a Gieseler plastometer. It can be calculated using characteristic values measured in , and can be said to be an extremely advantageous management index. Next, an example of the process of implementing coal blend management using the method of the present invention will be explained step by step. The highest flowability (MF:
logDDPM) and solidification temperature (S:°C) are determined. The maximum fluidity (MF: logDDPM) and solidification temperature (S: °C) may be measured by the commonly used method using a Gieseler plastometer (JIS M8801), or by other conventionally known methods. It's okay. For multiple coal blends, the above three indicators are calculated and each coking test is conducted under constant carbonization conditions, and the coke strength, e.g.
The correlation between DI150/15 and the three indicators can be expressed mathematically or graphically by drawing a line of equal coke strength. If it is necessary to change some of the types of coal charged in a coke oven, the following procedure will be used to determine how to manage the blend. First, we measured the maximum fluidity (MF) and solidification temperature (S) of the changed and newly blended coking coal, and created a new coke with only the coal type changed without changing the blending ratio of each coking coal. Prepare the furnace charging coal and test the new coke oven charging coal.
The values of MFI, STI, and VST are calculated and plotted by applying them to the relationship between each index and coking ability obtained above, and the isocoke intensity line shown by the relationship between each index and coking ability is calculated. Read the position. If the value of the coke strength after the change moves along the above-mentioned equal coke strength line from the position before the change, it means that there is not much change in the coke strength. In addition, if the coke strength is moving in a direction perpendicular to the equal coke strength line, you can evaluate whether the coke strength is increasing or decreasing, and you can evaluate the coking ability of the coal whose blend is being changed. It is then determined whether a change in the formulation is appropriate. In this way, using the target MFI, STI and VST values of the new coke oven charging coal,
The type and/or blending ratio of each raw material coal that satisfies the above MFI, STI, and VST values is determined from the maximum fluidity (MF) and solidification temperature (S) of each raw material coal. [Example] Hereinafter, the method of the present invention will be specifically explained based on Examples. (1) Creation of two-dimensional coordinates of VSTI-MFI Using seven brands of coking coal A to G,
As shown in the table, the maximum fluidity (MF) and solidification temperature (S) of each coking coal are measured using a Gieseler plastometer (JIS
M8801) and five types of coke oven charging coal with different blending ratios of each raw material coal listed above.
For each coke oven charging coal,
The values of MFI, STI, VST, and VSTI were calculated, and the coke strength (DI150/15, JIS K2152) of each coke oven charging coal was measured. Next, from the MF and S of coking coals A to G and the blending ratio, calculate the MFI and
Calculate VSTI and plot it on a graph with VSTI on the horizontal axis and MFI on the vertical axis. Furthermore, in this example, each coke oven charged coal measured for the five types of coke oven charged coal with different blending ratios of each coking coal is shown on a graph with VSTI as the horizontal axis and MFI as the vertical axis. The coke strength of VSTI-MFI was displayed, an equal coke strength line was drawn, and two-dimensional coordinates showing the relationship between VSTI-MFI and coke strength were created. As mentioned above, it is clear from the characteristics of the coal adhesive strength evaluation index that the isocoke strength line in this case has an upward slope to the right. The results are shown in Figure 2.

〔Effect of the invention〕

The coal blending control method of the present invention is based on the adhesion theory during coking of coal, and the coal blending can be controlled simply by measuring the solidification temperature and maximum fluidity of raw coal. These solidification temperature and maximum fluidity can not only be measured with the same measuring device, but also easy to calculate, making it possible to perform troublesome coal blending management efficiently.

[Brief explanation of drawings]

Figure 1 shows the state of adhesion between two types of coking coal, reference coal and test coal, using nine different brands of coking coal, and shows the boundary between strong bonding areas and weak bonding areas. The lined graph in FIG. 2 is a two-dimensional coordinate graph showing the relationship between VSTI-MFI and coke strength according to the embodiment of the present invention.

Claims (1)

[Claims] 1. When preparing coke oven charging coal by determining the types and/or blending ratios of multiple raw material coals, the solidification temperature and maximum fluidity of each raw material coal are measured in advance, and the blending ratio of coke oven charging coal is determined. Calculate the average value of the solidification temperature, the variation in solidification temperature, and the average value of the maximum fluidity of each raw material coal, taking into account the ratio,
The correlation between the average value of solidification temperature, the variation in solidification temperature, and the average value of maximum fluidity and coke quality is determined in advance, and the coking ability of coal charged in a coke oven is evaluated based on this correlation. Coal blend control method for coke production characterized by: