JP2007262296A - Method for producing metallurgical coke - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing metallurgical coke stabilized even when a raw material coal blended with new species of coals having various characteristics is used by avoiding large variation in quality of coke products. <P>SOLUTION: In producing metallurgical coke by preparing the raw material coal by blending two or more species of coals and dry distilling the raw material coal in a coke oven, the various species of coals are classified based on values of degrees of coalification (R<SB>O</SB>) and melt flow rates (MF) inherent in the coals and the brand-name coal satisfying 0.85≤R<SB>O</SB>≤1.25 and 50≤MF≤5,000 is brought to be in ≥50 mass% content based on the raw material coal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing metallurgical coke, and more particularly to a technique for stabilizing the quality of coke produced when a new brand of coal is used as raw coal.

Coke is widely used as industrial raw materials and fuels. In particular, in the blast furnace ironmaking method, it functions as a fuel and a reducing agent, and functions to form hot metal and gas flow paths in the furnace. It is an extremely important material. The quality of the coke used in this blast furnace (hereinafter referred to as metallurgical coke) includes not only the carbon content necessary for functioning as a fuel and reducing agent, but also a packed bed in the furnace, In order to maintain a gap through which gas flows, high strength is required.

For this purpose, conventionally, in the production of metallurgical coke, a plurality of brands of coal are combined in various combinations (called coking coal), and the coking coal is dry-distilled. Coal coalization degree (symbol: (R 2 _{O 3} )) is a main indicator, and other indicators specific to coal such as fluidity, ash content, inert, etc. have been measured and used. For example, for the purpose of producing coke having high reactivity while maintaining the strength of coke at a value that can be used, various brands of coal are mixed with low carbonization coal ( _RO < 0.9), medium carbonized charcoal (0.9 ≦ R _O <1.2) and high carbonized charcoal (R _O ≧ 1.2). The raw coal is 35 to 65% by mass, high carbonized coal is 10 to 30% by mass, and the remainder is medium carbonized coal, and the maximum fluidity (Log MF) of the raw coal is a weighted average of the coal blending ratio. A technique for providing an upper limit of 3.0 or less has been proposed (see Patent Document 1).

  This technology mixes low-carbon coal with coking coal in order to increase the coke reactivity, but if too much is added, the strength of the coke produced will decrease, contributing to the improvement of coke strength. In addition to blending 10% by mass or more of high carbonized coal, medium carbonized coal is blended in order to ensure the meltability of the raw coal during dry distillation in a coke oven. Moreover, this technique mix | blends the coal of the brand from which a coalification degree differs greatly when manufacturing highly reactive coke, and forms the coal raw material of a coalification degree suitable for coke manufacture on the average. In other words, this is a technology that uses a large amount of coal with a degree of coalification that deviates from the characteristic range of coal that is suitable as a raw material coal for the production of metallurgical coke.

  However, such a technique for managing the average characteristics of coal to be blended within a predetermined range has various problems in actual practical use.

  The first problem is due to the recent trend of securing coking coal resources. The amount of coal that has characteristics suitable for the production of metallurgical coke that has been used in the past has decreased, and has deviated from the conventional intention. The number of new brands of coal with characteristics has increased. If such a new brand of coal is blended in large quantities simply using the degree of coalification as a guideline, the produced coke often does not have the expected properties due to the interaction with other coals. Product coke quality could become unstable.

The second problem is that when coals with extremely different coalification levels are mixed in the conventional coke mixing process, it is not possible to completely prevent the partial blending, which is uneven. Will become a raw coking coal. When such non-uniform coking coal was charged into a coke oven and dry-distilled, the quality of the product coke obtained could vary greatly. To avoid this problem, it is necessary to improve the mixing process, but another problem arises that costs for equipment and operation increase.
JP 2004-224844 A

  In view of such circumstances, the present invention avoids significant fluctuations in the quality of the product coke obtained and can stabilize it even when using raw coal containing a new brand of coal having various characteristics. It aims at providing the manufacturing method of the coke for a house.

The inventor has intensively studied to achieve the above object, and the results have been embodied in the present invention. In the present invention, when a plurality of brands of coal are blended to form coking coal, and the coking coal is carbonized in a coke oven to produce metallurgical coke, each brand of coal has its own coalification degree. (R _O ) and Gieseler maximum fluidity (MF) are classified on the basis of the value of coal of a brand satisfying 0.85 ≦ R _O ≦ 1.25 and 50 ≦ MF ≦ 5000. It is a manufacturing method of the metallurgical coke characterized by setting it as% or more. In this case, it is preferable that the blending ratio of brand coal exhibiting MF ≦ 10 is 10% by mass or less of the raw coal.

  According to the present invention, when blending raw coal, not only the use of a new brand of coal whose characteristics such as the degree of coalification deviate from the preferred range for the production of metallurgical coke, but also mixing in the existing coal mixing process. However, stable quality metallurgical coke can be produced without causing large quality fluctuations.

  Hereinafter, the best embodiment of the present invention will be described based on the background of the invention.

  First, the inventor considered that there was no segregation in the raw coal filled in the coking chamber of the coke oven in order to avoid and greatly stabilize the quality of the manufactured metallurgical coke. . That is, it is important that the coking coal packed in any of the carbonization chambers is blended with the amount of coal constituting each brand almost as scheduled.

  However, as a result of investigating this, some results have been obtained by improving the means for cutting out coal from the hopper and the mixing process, and it is necessary to make significant equipment modifications to suppress segregation. I understood it. However, such modifications are not economically viable as described above.

  Therefore, the inventor paid attention to the combination (content of blending) of the coal composing the raw coal and dealt with the characteristics of the coal that dominates the combination, and conducted extensive research. As a result, if not only the degree of coalification but also other characteristics are added and the coal is blended under stricter conditions than before, the quality of the produced coke, especially the strength fluctuation (daily fluctuation, room fluctuation) All the behaviors such as fluctuations in the room, fluctuations in the vertical direction in the room, etc.) can be reduced as compared with the past. And as this another characteristic, it decided to employ | adopt the fluidity | flux of coal (represented by the highest Gieseller fluidity (symbol: MF)) so that coal may be melted as uniformly as possible in the carbonization chamber.

Specifically, as shown in FIG. 1, the coal of each brand based on their unique carbonization degree (R _O) and Gisera maximum fluidity degree (MF), classified as a two-dimensional matrix, organize, therein Therefore, we decided to find an area where the quality of coke was good. For that purpose, confirmation by a test operation is necessary. Actually, various types of raw coals containing various brands of coal were manufactured to try to manufacture metallurgical coke, and a use test was conducted in a blast furnace. The test results were evaluated by the output ratio, which is an index of blast furnace productivity. The brewing ratio is a numerical value obtained by dividing the amount of drought per day (t / day) of the blast furnace by the internal volume (m ³ ) of the blast furnace, and a larger value is an index that can be evaluated as having higher productivity. If the quality of the coke is stable, the in-furnace condition of the blast furnace is stabilized and high productivity can be achieved.

An example of test results obtained by adopting the usual operating conditions of the coke oven (dry distillation temperature, fire extinguishing method, sieve, etc.) and the operating conditions of the blast furnace are 0.85 ≦ R _O ≦ 1.25. FIG. 2 shows the relationship between the ratio (expressed by the blending ratio (mass%)) of coal satisfying 50 ≦ MF ≦ 5000 and the blast furnace productivity.

From FIG. 2, when coke is produced with the ratio of coal that satisfies 0.85 ≦ R _O ≦ 1.25 and 50 ≦ MF ≦ 5000 accounting for 50% by mass or more, extremely high productivity is achieved in blast furnace operation. It is clear that this is a metallurgical coke that can achieve stable blast furnace operation. Therefore, the original coal was formed by blending a coal multiple brands, when the raw material coal by dry distillation in a coke oven to produce a metallurgical coke, coal of each brand, their unique coal degree (R _O ) And fluidity (MF) value, and a coal that satisfies 0.85 ≦ R _O ≦ 1.25 and 50 ≦ MF ≦ 5000 is 50% by mass or more of the raw coal. Therefore, the present invention has been completed.

  Subsequently, the inventor also examined further improvements of the present invention described above. This is because the coke quality is considered to be better if the blending amount of the low-flow coal is limited among the coals constituting the raw coal. When this idea was actually tried, the relationship shown in FIG. 3 was obtained. In other words, when the requirement that the blending ratio of brand coal exhibiting MF ≦ 10 is 10% by mass or less of the raw coal is added to the above two requirements, the productivity of the blast furnace may be further increased. confirmed. Therefore, it was decided to add coke to the present invention in accordance with these three requirements.

11 types of coal from brands A to K shown in Table 1 are blended to form 3 types of coking coal, each coking coal is charged into a coke oven and dry-distilled. Manufactured. The operating condition of the coke oven was 20 hours as usual for carbonization. The obtained metallurgical coke was used for 5000 m ³ grade blast furnace operation to produce hot metal. As is apparent from Table 1, the grades A to E have a carbonization degree and fluidity satisfying 0.85 ≦ R _O ≦ 1.25 and 50 ≦ MF ≦ 5000, and the grade F The coal of ~ K is out of the above range.

The operation results are as follows. Each time 1,000 tons of coke is obtained, sampling is performed to obtain a sample, and the “drum method” defined in JIS K 2151, 7/2, which is the Japanese Industrial Standard. The strength test was carried out and the strength was measured and evaluated. The test conditions are a drum rotation number of 30 and a sieve mesh of 6 mm.

The test results were evaluated by standard deviation for variation in drum strength, whereas the coking coal 3 of the comparative example had a value of 1.0, whereas the coke produced with the coking coals 1 and 2 by applying the present invention. Was 0.5 and 0.7, respectively. In other words, it was confirmed that, when the present invention is applied, it is possible to manufacture a metallurgical coke which is a product with less variation in strength than before.

  Moreover, about the use results in a blast furnace, it evaluated by the frequency | count of performing a wind pressure raise / decrease per day during the period using three types of coke, respectively, and the case of coking coal 1 and coking coal 2 is 0.2 respectively. In the case of the coking coal 3 of the comparative example, it was 0.5 times. This wind pressure increase and decrease means that when the blowing pressure rises due to an increase in pressure loss in the furnace during operation, the amount of blowing is reduced to suppress the pressure rise. Means unstable. Therefore, the above result suggests that when the metallurgical coke according to the present invention is used in a blast furnace, the operation is stabilized.

It is a figure which shows the condition which classified and arranged the coal of each brand which comprises coking coal as a two-dimensional matrix based on carbonization degree ( _RO ) and maximum fluidity (MF) peculiar to them. A diagram showing a relationship between 0.85 ≦ _{R O} ≦ 1.25 and the ratio accounts for 50 ≦ MF ≦ 5000 coking coal coal satisfying the (mixing ratio represented by (mass%)) and blast furnace productivity in coke production is there. It is a figure which shows the blast furnace productivity at the time of further adding the requirement that the mixture rate of the brand coal which exhibits MF <= 10 shall be 10 mass% or less of the raw coal of FIG.

Claims (2)

When producing coke for metallurgy by blending multiple brands of coal to form coking coal and carbonizing the coking coal in a coke oven,
Each brand of coal is classified based on their inherent coalification (R _O ) and Gieseler maximum fluidity (MF) values, with 0.85 ≦ R _O ≦ 1.25 and 50 ≦ MF ≦ 5000 A method for producing metallurgical coke, characterized in that a coal of a brand satisfying the requirements is 50 mass% or more of the raw coal.   Furthermore, the compounding rate of the brand coal which exhibits MF <= 10 shall be 10 mass% or less of the said raw coal, The manufacturing method of the metallurgical coke of Claim 1 characterized by the above-mentioned.

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