JPH09279152A - Grinding of coal charged into coke oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out improvement of coke strength and reduction of coke raw material cost due to increased used of slightly caking coal by grinding and blending coal, etc., having a whole coefficient of expansion of a prescribed value or above under specific conditions to control particle size of charged coal. SOLUTION: Coal having >=50% whole coefficient of expansion is crudely ground so that a ratio of coal having <=3mm size becomes smaller by >=4wt.% than a prescribed value and coal having <50% whole coefficient of expansion is finely ground so that a ratio of coal having <=3mm size becomes larger by >=4wt.% than a prescribed value and these coals are blended so that a ratio of charged coal having <=3mm size becomes 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 of pulverizing coal blends which can reduce coke material cost by improving coke strength with the same coal blend or by increasing the use of inexpensive non-caking coal of the same strength. is there.

[0002]

2. Description of the Related Art In the production of blast furnace coke, when the average particle size of the coal charged in the coke oven is made finer, the homogenization of the coal improves the DI ¹⁵⁰ ₁₅ of the coke, but at the same time, the bulk density of the coal decreases and the CSR (CO ₂ reaction) After-strength) is reduced. Thus, it is difficult to simultaneously improve both DI ¹⁵⁰ ₁₅ and CSR when simply adjusting the average particle size of the blended coal.

Therefore, as a conventional technique, when the coal is crushed, the property of collecting the inactive component in the coarse-grain portion and the active component in the fine-grain portion is utilized, and the selective pulverization using a sieve is performed to prevent the decrease of the bulk density. And there is a selective crushing method for homogenizing coal. According to this method, coal is divided into a group having a large amount of active components (vitrinite and exgenite) and a group having a large amount of inactive components (inertinite) by a structural analysis, and the particles are classified and pulverized by a sieve suitable for each group.

[0004]

However, the conventional selective crushing method has a high sieving cost, and the effect is small with coal having a small amount of inert components, and the CSR is effective only when the strength level is low. I can't.

An object of the present invention is to provide a pulverizing method of blended coal which can improve the CSR or reduce the cost of the coke raw material by increasing the use of non-caking coal while maintaining DI ¹⁵⁰ _15. is there.

[0006]

[Means for Solving the Problems] In order to solve the above problems, (1) Coal of a brand having a total expansion rate of 50% or more is coarsened so that a ratio of 3 mm or less is less than a predetermined value. After crushing and finely pulverizing the coal of the brand whose total expansion rate is less than 50% so that the ratio of 3 mm or less is more than the specified value, mix it and adjust the ratio of 3 mm or less of the charged coal to the specified value. A method for crushing coal charged in a coke oven, characterized by:

(2) Coal of a brand having a total expansion rate of 50% or more is coarsely crushed so that a ratio of 3 mm or less is 4% by weight or more less than a predetermined value, and a brand of coal having a total expansion rate of less than 50% is Crushing of coke oven charged coal, characterized by finely pulverizing so that the ratio of 3 mm or less is 4% by weight or more above 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.

Here, the total expansion coefficient was measured according to JIS-M8801.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 shows the relationship between the crushed particle size of plain coal and the CSR of coke produced.

Generally, when the particle size of coal is made coarse, the expandability at the time of thermal softening is improved, so that the fine pores in the produced coke are reduced and the specific surface area is reduced. Therefore, CSR is improved by decreasing the reaction rate of coke with CO ₂ .

Further, the average total expansion rate of the coal charged into the coke oven is about 50%, and in the case of coal having a total expansion rate of less than 50%, the degree of decrease in the specific surface area of the coke due to the above-mentioned coarsening is relatively small. Therefore, the effect of improving the CSR is small, but in the case of coal having a total expansion coefficient of 50% or more, the degree of decrease in the specific surface area of the coke due to the coarsening is relatively large, and therefore the effect of improving the CSR is large. From this, the total expansion coefficient of coal is set to 50% as a boundary index for dividing the particle size during coal crushing.

Further, with respect to the increase or decrease of the ratio of the coal of each brand of 3 mm or less with respect to the predetermined value, if the amount is less than 4% by weight, the effect of improving the CSR is small, so that 4% by weight.
Above.

[0013]

EXAMPLE Coal is divided into two groups within the range of total expansion coefficient, and the coke strength when coke is produced by changing the particle size of each group is shown in Table 1.

[0014]

[Table 1]

Comparative Example 1 shows a case in which the particle size of all blended coals is adjusted so that the ratio of 3 mm or less becomes the same as the blended coal average value.

In Comparative Example 2, coal having a total expansion coefficient of 50% or more is coarse so that the ratio of -3 mm is 4% or more smaller than the average particle size of the coal blend, and coal having a total expansion coefficient of less than 50% has an average particle size of the coal blend. This is the case when the particle size is adjusted so that it becomes almost the same as. In this case, the CSR is improved as compared with Comparative Example 1, but the DI ¹⁵⁰ ₁₅ is slightly decreased.

In Example 1, coal having a total expansion rate of 50% or more is coarse so that the ratio of -3 mm to the average particle size of the blended coal is 4% smaller, and coal having a total expansion rate of less than 50% is the blended coal average. The case where the particle size is finely adjusted so that the ratio of -3 mm to the particle size is 6% larger is shown. In this case, DI
Both ¹⁵⁰ ₁₅ and CSR are better than Comparative Example 1.

[0018]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, DI ¹⁵⁰ ₁₅
While maintaining the above, it is possible to improve the CSR or reduce the cost of the coke material by increasing the use of the non-caking coal.

[Brief description of drawings]

Fig. 1 Relationship between crushed particle size of plain coal and CSR of coke produced

Claims (2)

[Claims] 1. Coal of a brand having a total expansion rate of 50% or more is 3
Coarsely crushed so that the ratio of mm or less is less than the specified value, and finely pulverized coal of the brand whose total expansion rate is less than 50% so that the ratio of 3 mm or less is more than the specified value, and then blending and charging. A method for pulverizing a coal charged in a coke oven, which comprises adjusting a ratio of coal of 3 mm or less to a predetermined value. 2. Coal of a brand having a total expansion rate of 50% or more is 3
Coarsely crushed so that the ratio of mm or less is 4% by weight or more less than the predetermined value, and 3 brand coals with a total expansion rate of less than 50%
Milling of coke in a coke oven characterized by finely pulverizing so that the proportion of mm or less is 4% by weight or more above a predetermined value and then blending to adjust the proportion of 3 mm or less of the charging coal to a predetermined value. Method.