JPH04309594A - Production of blast furnace coke - Google Patents

Abstract

PURPOSE:To find out a binder for coke which can produce coke of low cost and good quality. CONSTITUTION:Liquefied oil is removed from the product obtained in a coal liquefaction process. The liquefaction residue is mixed with coal and the mixture is carbonized in a usual coke oven. Thus, coke comparable in strength to that obtained from good coal blend can be produced even from coal blend from which coke having a sufficiently high strength has not been obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing coke for use in blast furnaces in the steel industry, in which coke is mixed with coal and carbonized to produce high-quality coke.

0002

[Prior art] When producing blast furnace coke from coal,
When coal lacks fluidity or caking properties, tar or pitch may be mixed. These methods have been conventionally called fluidity fillers or caking filler methods, and are common methods. However, as the prices of tar and pitch have increased in recent years, this method has become less effective. For this reason, there is currently a search for inexpensive fluidity fillers or caking fillers (these are collectively referred to as binders for coke).

0003

SUMMARY OF THE INVENTION In view of the current state of the art, it is an object of the present invention to find a binder for coke that can produce coke of good quality at low cost.

0004

[Means for Solving the Problems] The present invention focuses on the liquefaction residue (530° C. fraction in terms of normal pressure) after extracting liquefied oil as a product from the obtained product in coal liquefaction. Until now, this liquefied residue had no use other than combustion and was discarded.

It has been believed that tar and pitch can be used as effective binders for coke because they produce the same anisotropic structure as coke obtained from highly fluid coal. When the liquefied residue was carbonized and the resulting coke structure was observed under a microscope, an anisotropic structure similar to that of pitch, which is used as a binder for coke, was observed. Therefore, we thought that this liquefaction residue could be used as a binder for coke, and when we mixed it with coal for coking and carbonized it, we were able to produce high-quality coke with sufficient strength.

[0006] That is, the gist of the method for producing coke for blast furnaces of the present invention is to use the liquefaction residue of the 530°C fraction in terms of normal pressure that remains after removing liquefied oil from the product obtained in the coal liquefaction process, and the Gieselerplast. The method involves mixing coal with a flow rate of 1.5 (Log DDPM) or less as measured by a meter at a weight ratio of liquefaction residue of 10% or less, and carbonizing the mixture in a normal indoor furnace.

[0007]

[Operation] As mentioned in the section of means, the liquefied residue has an anisotropic structure similar to the coke structure obtained from highly fluid coal. Therefore, by mixing it with coal that has low fluidity, a fluidity compensation effect appears. This liquefaction residue is particularly effective for coal blends that are generally said to have low fluidity and have a Gieseler plastometer rating of 1.5 or less. However, when the blending ratio of liquefaction residue is increased, the ash content increases significantly, which is not preferable as coke for blast furnaces. Since the ash content of the liquefied residue normally obtained is 15% or more, it is not preferable to blend the liquefied residue in excess of 10% when blending with coal.

[0008]

[Example] The carbonization of coal according to the present invention and the quality of the coke obtained were investigated. First, four types of coal blends with different fluidity were selected and carbonized in a test coke oven called a 1/4 ton coal carbonization furnace, and the drum strength of the resulting coke was examined.

Table 1 shows the properties of the blended coal used. 1/
The 4-ton coal carbonization furnace can heat a container with a width of 400 mm, a height of 615 mm, and a length of 594 mm to a maximum temperature of 1,350°C. Heating is an indirect heating method using a SiC heating element. This time, the furnace wall temperature was 1250°C.

Table 2 shows the composition of the coal liquefaction residue used. First, the coke strength of the coke obtained by carbonizing four types of coal blends alone and the coke obtained by mixing 5% of the liquefaction residue was measured using a drum tester. Table 3 shows the results of the coke strength obtained. From this, it was found that the fluidity compensating effect of the liquefaction residue was remarkable in the blended coal with a Gieseler plastometer fluidity of 1.5 or less.

Next, blended coal A has a remarkable effect of liquefaction residue.
A carbonization test was conducted by changing the blending ratio of the liquefied residue. The results are shown in Table 4. From this, the strength does not change much when the content exceeds 10%. However, the ash content increases, making it undesirable as coke for blast furnaces.

0012

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

[Effects of the Invention] As explained above, even in the case of a coal blend that does not have sufficient strength, by adding liquefaction residue, it is possible to produce coke that has the same strength as a high quality coal blend. However, the effect of adding liquefaction residue is small in coal blends that already produce high-strength coke.

Claims (1)

[Claims] [Claim 1] Mixing the liquefied residue remaining after removing liquefied oil from the product obtained in the coal liquefaction process with coal,
A method for producing blast furnace coke, which is characterized by carbonization in a normal room furnace.