JPS6314034B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing coke for blast furnaces using a briquette blending method, and aims to stabilize coke quality and increase the blending ratio of briquette coal. The briquette blending method, which has been adopted as a method for producing coke for blast furnaces, involves blending dense briquette coal with powdered coal that has a moisture content of 5% or more and charging it into a coke oven. It improves coke strength and allows the use of low-rank coal, but
Currently, the blending amount of briquette coal is limited to 30% at most. The reason for this is that when charging raw materials mixed with briquette coal, pulverized coal and briquette coal are not charged in a uniform ratio when charging into a coke oven, and segregation always occurs. Therefore, although theoretically the amount of briquette coal can be up to 50-60%, it is limited to around 30% in consideration of the segregation of briquette coal in the coke oven. In addition, the blended amount of briquette
Even in the case of 30%, segregation actually occurs in the coke oven, and it is known that the segregation of briquette coal at each location in the coke oven is about 10%. In order to prevent such segregation of briquette coal, various mixing methods have been studied, but the best method has not yet been established. Preventing this segregation of briquette coal in the furnace not only stabilizes coke quality but also increases the theoretical blending amount of briquette coal to 50 to 60%.
%, leading to a significant increase in the ratio of low-rank coal used. Therefore, the establishment of technology to prevent briquette coal segregation is especially needed for the production of coke for blast furnaces. In order to establish this technology, the inventors have repeatedly studied the in-furnace segregation phenomenon of briquette coal in the briquette blending method, and found that the cause of the in-furnace segregation of briquette coal is
We found that this is due to the difference in the angle of repose between powdered coal and briquette coal, and based on the knowledge that the angle of repose of powdered coal is affected by the surface tension of adhering moisture, we reduced the angle of repose of powdered coal and reduced the segregation of briquette coal in the furnace. We have established a method for producing coke for blast furnaces that can effectively prevent this. In other words, this invention reduces the angle of repose between the powdered coal and the shaped coal by adding and mixing a surfactant to the powdered coal to reduce the surface tension of adhering moisture and making the angle of repose of the powdered coal equal to or lower than that of the shaped coal. It is characterized by reducing the difference and preventing segregation of briquette coal in the furnace. The experiments conducted by the inventors and their results will be explained below. The inventors manufactured a container for bulk density distribution measurement having a size close to that of an actual furnace, mixed briquette coal with various powdered coals having different moisture contents in various proportions, and
This was charged into a bulk density measurement container from the top, and then the bulk density and briquette blending ratio at each part of the container were measured. As a result, the following was found. In other words, when the blending ratio of briquette coal is kept constant,
As the moisture content of pulverized coal decreases, not only does the bulk density at each location within the furnace improve, but also the segregation of briquette coal tends to decrease. Especially when the moisture content of powdered coal is 5.
% or less, it was estimated that the effects of stabilizing coke quality and improving strength would be significant. Furthermore, when the moisture content of powdered coal is set to 9.5% and the blending ratio of briquette coal is changed, the bulk density at each position in the furnace increases as the blending ratio of briquette coal increases. However, this bulk density improvement effect is due to an increase in the blending ratio of high-density briquette coal, and the bulk density of pulverized coal is rather lower than when briquette coal is not blended. Moreover, it was found that the segregation of briquette coal at each location in the furnace was amplified as the blending ratio of briquette coal increased. This tendency was noticeable immediately below the charging port and between the charging ports, and was estimated to be a cause of variation in coke strength. From the above results, if the moisture content of pulverized coal is suppressed to 5% or less, segregation of briquette coal is prevented, bulk density is improved, and coke quality is greatly improved. However, reducing the moisture content of pulverized coal to 5% or less will result in the generation of a huge amount of dust during the transportation process of raw materials and during charging into a coke oven.
This is difficult in actual operation. Therefore, the inventors investigated the cause of segregation in briquette coal when pulverized coal containing 5% or more water content was used, and found that it was due to the difference in the angle of repose between pulverized coal and briquette coal. In this briquette blending method, the angle of repose of powdered coal and briquette coal is usually about 38 when the former has a moisture content of 10%.
It was found that the latter was about 32 degrees, and in order to prevent segregation of the briquette coal, it was necessary to suppress the difference in the angles of repose to a maximum of 32 degrees. It has also been found that the angle of repose of pulverized coal is greatly influenced by the moisture content, and becomes smaller than the angle of repose of briquette coal when the moisture content is 5% or less. Therefore,
By setting the angle of repose of the powdered coal to be equal to or less than the angle of repose of the briquette coal, segregation of the briquette coal in the furnace can be prevented. As a method for reducing the angle of repose of the pulverized coal, the inventors have confirmed that a method of adding and mixing a surfactant to pulverized coal containing 5% or more water is effective. In other words, surfactants have the effect of reducing the capillary force caused by the surface tension of water that binds coal particles together, and reducing the adhesion force between coal particles, thereby increasing the fluidity of coal particles. This leads to a reduction in the angle of repose. Although such effects vary depending on the type of surfactant, type of raw coal, and water content, it has been confirmed that the amount of surfactant added is not particularly limited, but 0.1% or less is sufficient. did. In addition, as the surfactant in this invention,
Examples include sulfonic acids such as sodium dodecylbenzene sulfonate, alkylbenzene compounds, and fluorinated carbon compounds that greatly lower the surface tension of water. As described above, according to the method of this invention, the angle of repose of the pulverized coal can be reduced by adding and mixing a surfactant to the pulverized coal containing 5% or more water content, thereby preventing the segregation of molten coal in the furnace. be able to. By preventing this segregation, a large number of briquettes (50 to 60
%), and also reduces the variation in coke strength and stabilizes the quality. It is also expected to have the effect of reducing segregation of briquette coal during the transportation process before charging it into a coke oven, eliminating the need for segregation prevention equipment in conventional coal towers and coal loading cars. Next, an example of an apparatus for carrying out the method of the invention will be explained based on the drawings. The drawing is a flow sheet showing the equipment, 1 is a coking coal tank, 2 is a mixer,
3 is a surfactant tank, 4 is a mixer, 5 is a non-caking coal tank, 6 is a binder tank, 7 is a kneader, 8 is a molding machine, and 9 is a molded coal mixer. That is, single coking coal is cut out from the coking coal tank 1, and blended coal 10 is obtained in the mixer 2.
A surfactant 11 in a surfactant tank 3 is added to a portion of this blended coal, and the mixture is sufficiently mixed by a mixer 4 to form an additive-mixed coal 12. On the other hand, the remainder of the blended coal 10 is made by mixing the non-caking coal cut out from the non-caking coal tank 5 and the molding binder cut out from the binder tank 6 into a kneader 7.
The mixture is kneaded in a molding machine 8 to obtain briquette charcoal 13. This briquette coal 13 and the additive-mixed coal 12 are mixed in a mixer 9 to form coke oven charged coal 14. Examples of the present invention will be described below. [Example 1] Using the method shown in the drawing, sodium dodecylbenzenesulfonate was added as a surfactant to a part of powdered coal adjusted to a particle size of 3 mm or less and 83% having the raw material properties and blending ratio shown in Table 1. Additive-mixed charcoal obtained by adding and mixing the charcoal, and briquette charcoal produced by adding non-caking coal shown in Table 1 and soft pitch as a binder to the remainder of the powdered charcoal and kneading it with a molten machine. The briquette blending ratio was set to 30%, and the resulting briquette blend was charged into a coke oven with a frie temperature of 1180°C.
Blast furnace coke was produced by carbonization for 24 hours. The surfactant addition conditions at that time are shown in Table 2, and the variations in the amount of briquette coal and the variation in coke strength in the coke oven are shown in Table 3. In Table 3, the variation in the amount of briquette coal and the variation in coke strength are expressed as standard deviation values. Table 3 also shows, as comparative examples, variations in the amount of briquette coal and variations in coke strength when no surfactant is used, for comparison with the method of the present invention. In addition, the variation in the amount of briquette (δB) is calculated from the briquette content measured at each part of the bulk density measurement container with the size of the actual furnace described in the main text, while the variation in coke strength (δC) is It is calculated from drum strength measurement results for samples at positions within the coke work that are thought to correspond to various parts of the coke oven.

【table】

【table】

[Example 2]

Powdered coal containing 9.5% moisture, the same as in Example 1,
Blast furnace coke was produced in the same manner as in Example 1 when the briquette coal content ratio was increased to 40% and 50%, and the variation in the amount of briquette coal in the coke oven and the resulting product coke were measured. The variation in strength was measured. The results are shown in Table 4. Table 4 also shows the results when no surfactant was added, as in Example 1, for comparison with the method of the present invention.

[Table] As is clear from the results in Table 4, in Tests No. 7 and 9 shown as comparative examples and Test No. 3 of Example 1, the blending ratio of briquette coal was increased to 30%, 40%, and 50%. As a result, the variation in the amount of briquettes in the coke oven and the variation in coke strength greatly increase, whereas in the method of the present invention, as seen in Test Nos. 6 and 8, the variation in the amount of briquette in the coke oven increases. , and variations in coke strength were both slightly increased compared to Test Nos. 1 and 2 of Example 1, in which the briquette ratio was 30%, and coke of stable quality was obtained. . As described above, according to the present invention, even if the blending ratio of briquette coal is increased to the theoretical 50%, the segregation of briquette coal in the coke oven is slight, and coke of stable quality can be obtained. Therefore, the present invention has the extremely great effect of stabilizing the coke quality in the coke production method containing briquette coal and increasing the use of low-rank coal by blending a large amount of briquette coal.

[Brief explanation of the drawing]

The drawing is a flow sheet showing an example of an apparatus for carrying out the method of this invention. In the figure, 1... Caking coal tank, 2... Mixer, 3...
Surfactant tank, 4...Mixer, 5...Non-caking coal tank, 6...Binder tank, 7...Kneading machine, 8...
Molding machine, 9... Molded coal mixer, 10... Blended coal,
11...Surfactant, 12...Additive mixed carbon, 1
3... Molded coal, 14... Coal charged in coke oven.

Claims (1)

[Claims] 1. In a method of manufacturing coke by blending briquette coal with pulverized coal containing 5% or more water, the pulverized coal is preliminarily added to the coal particles by reducing the capillary force caused by the surface tension of water that binds the coal particles together. A method for producing coke for blast furnaces, characterized in that segregation of briquette coal in a furnace is prevented by adding and mixing a surfactant that has the effect of reducing adhesion between coke.