JPH09279151A - Grinding of coal charged into coke oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress yield of fine powder and reduce operation cost by grinding and blending coals, etc., having a hardgrove grindability index(HGI) of a prescribed value or above under specific conditions F and controlling particle size of coal charged into a coke oven. SOLUTION: Coal having >=70 HGI is ground so that a ratio of coal each having <=3mm particles size becomes larger by 5-10% than a prescribed value and coal having <70 HGI are ground so that a ratio of coal each having <=3mm particle size becomes smaller by 5-10% than a prescribed value and these coals are blended so that a ratio of charged coal having <=3mm is controlled to a prescribed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pulverizing coal blended in a coke oven.

[0002]

2. Description of the Related Art Usually, coal charged into a coke oven is crushed so that a proportion of 3 mm or less becomes about 80% as a proper point in terms of a balance between improvement in homogeneity and increase in bulk density. There is. The crushed coal contains about 30% of fine powder of 0.3 mm or less which can be a dust source, but the fine powder aggregates in a wet coal operation with a water content of about 9%, and apparently coarsens. Therefore, there is little dust generation when transferring and charging the coke oven.

When the coal charged in the coke oven is dried to reduce the water content, it is possible to improve the quality of the coke or increase the use of the non-caking coal by reducing the amount of dry distillation heat and increasing the bulk density.
Especially when the water content is as low as about 2%, the fine powder that has aggregated during wet coal will exist in the state of the original single particles, so dust will be generated when the dry coal is transferred and charged into the coke oven. Is a problem. Therefore, conventionally, the charged coal after drying is classified and divided into fine powder and coarse particles, and the fine powder portion is agglomerated (Japanese Patent Laid-Open No. 59-4681).

On the other hand, regarding the technology for adjusting the particle size of the coal charged into the coke oven, there is a method in which the coal is divided into a group having a large amount of active components and a group having a large amount of inert components, and the particles are classified and pulverized by suitable sieve openings. However, these are for the purpose of improving the strength of coke or reducing the cost of coke material, and there is no coal particle size control technology for the purpose of suppressing the generation amount of fine powder which is a dust source.

[0005]

However, in the conventional method of classifying and pulverizing, particularly the pulverized and dried blended coal contains about 30% of fine powder, and the agglomeration process of fine powder is performed to prevent dust generation. Equipment costs and operating costs.

Therefore, there is a demand for a coal particle size adjusting method capable of reducing the facility cost or operating cost of the fine powder agglomeration process by suppressing the generation amount of fine powder as a dust source.

An object of the present invention is to provide a method for pulverizing coal which maintains the average particle size of the charged coal constant and reduces the amount of fine powder of 0.3 mm or less that causes dust during transportation. Especially.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, (1) Coal of brands having an HGI of 70 or more is crushed so that the proportion of each of them is 3 mm or less is larger than a predetermined value. A coke oven characterized by crushing coal of a brand having an HGI of less than 70 so that the ratio of 3 mm or less becomes smaller than a predetermined value, and then blending it to adjust the ratio of 3 mm or less of the charged coal to a predetermined value. This is a method of crushing charged coal.

(2) Among coals to be blended, coals having a HGI of 70 or more are premixed and then pulverized so that a ratio of 3 mm or less is larger than a predetermined value. Crushing of coal charged in a coke oven, which is characterized by mixing after mixing so that the ratio of 3 mm or less becomes smaller than a predetermined value, and then blending to adjust the ratio of 3 mm or less of the charged coal to a predetermined value. Is the way.

(3) 3 brands of coal with HGI of 70 or more
It is characterized by crushing so that the ratio of mm or less becomes 5 to 10% larger than a predetermined value, and crushing coal of a brand having an HGI of less than 70 so that the ratio of 3 mm or less becomes 5 to 10% smaller than the predetermined value. The method for pulverizing the coal charged in a coke oven according to (1) or (2) above.

Here, the hard glove grindability index (HG
I) was measured according to JIS-M8801.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION When coals having different grindability are ground to the same average particle size, the energy required for grinding is different.
When pulverizing coal having an HGI of 70 or more and having relatively high pulverizability, a small amount of energy is sufficient, and thus the amount of fine powder generated is small. On the contrary, when pulverizing coal having an HGI of 70 or less and relatively low pulverizability, a larger amount of energy is added to the particles, so that the amount of fine powder generated increases.

1 and 2, the HGI is 70
Coal A (HGI = 86.7) and coal B (HGI = 54.6) with an HGI of less than 70 have two levels of grain size (3 mm
Below 70% and 90%)
This is shown in the Rosin-Rammler diagram.

As is apparent from FIG. 1, in the coal A having an HGI of 70 or more, the slope of the Rosin-Rammler diagram becomes large as the crushing is strengthened, and the increase of fine powder is relatively small. When coal A was crushed and strengthened from 70% to 90% at a ratio of 3 mm or less, the increase of fine powder of 0.3 mm or less was 3.9%.

Further, as is clear from FIG. 2, coal B having an HGI of less than 70 is Rosin-Rammler even if crushing is strengthened.
The change of the inclination of the diagram is small, and the increase of fine powder is relatively large. On the contrary, if the crushing is alleviated, the reduction of fine powder is relatively large. When Coal B was pulverized and relaxed from 90% to 70% at a ratio of 3 mm or less, the reduction amount of fine powder of 0.3 mm or less was 9.2%.

The predetermined value of the ratio of the charged coal of 3 mm or less is determined by the bulk density in the coke passage, and is usually 75% to 85% and 80%.
It is a degree.

Therefore, for example, the average particle size of the charged coal is 3
In order to maintain 80% at a ratio of mm or less, crush and strengthen coal with a brand of HGI of 70 or more to 90% at a ratio of 3 mm or less, and 70% of brand of HGI less than 70 at a ratio of 3 mm or less. By pulverizing and mitigating up to, the proportion of fine powder of 0.3 mm or less in the blended coal is reduced by 2.7%.
This reduced amount of fine powder corresponds to about 10% of the total amount of fine powder in the coal blend.

Not only when the grain size is adjusted for each plain brand, but coals of brands having HGI of 70 or more are mixed in advance and then pulverized so that the ratio of 3 mm or less becomes larger than a predetermined value, and HGI is 70. Even when the coals of the brands below are mixed in advance and pulverized so that the ratio of 3 mm or less becomes smaller than the predetermined value, the same effect of suppressing the generation of fine powder can be obtained.

Furthermore, regarding the increment or decrement of the ratio of coal of each brand of 3 mm or less with respect to a predetermined value, 5
If it is less than 10%, the effect of suppressing the generation of fine powder is small, and if it exceeds 10%, it is difficult to adjust considering the raw coal particle size level and the charging coal average particle size level in the actual operation. Is.

[0020]

As described above, according to the present invention, the generation amount of fine powder is suppressed even when the blended coal average particle size is constant,
The equipment cost or operating cost of the fine powder agglomeration process is about 1
It can be reduced by 0%.

[Brief description of drawings]

Fig. 1 Rosin-Rammler diagram of coal particle size distribution (HGI7
Zero or more coal A).

[Fig.2] Rosin-Rammler diagram of coal particle size distribution (HGI7
Coal less than 0 B).

Claims (3)

[Claims] 1. Coal of a brand having a hard glove grindability index (HGI) of 70 or more is crushed so that a ratio of each of which is 3 mm or less is larger than a predetermined value, and coal of a brand of which HGI is less than 70 is 3 mm or less. A method for crushing coal charged in a coke oven, which comprises crushing so that the ratio is smaller than a predetermined value, and then blending the mixture to adjust the ratio of the charged coal to 3 mm or less to a predetermined value. 2. Among coals to be blended, coals having a HGI of 70 or more are mixed in advance, and then pulverized so that a ratio of 3 mm or less becomes larger than a predetermined value, and coals having a HGI of less than 70 are previously mixed. A method for crushing coal in a coke oven, which comprises mixing and crushing so that a ratio of 3 mm or less becomes smaller than a predetermined value, and then compounding to adjust a ratio of 3 mm or less of the charged coal to a predetermined value. . 3. Coal having a HGI of 70 or more is 3 mm
It is characterized in that the following ratio is crushed so as to be 5 to 10% larger than a predetermined value, and coal of a brand having an HGI of less than 70 is crushed so that a ratio of 3 mm or less becomes 5 to 10% smaller than the predetermined value. A method for pulverizing the coal charged in the coke oven according to claim 1 or 2.