JPH09272871A - Production of high-strength coke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing high-strength coke for a blast furnace in using a raw material coal containing 20-60wt.% of fine non-caking coal by mixing coal having high gas pressure in carbonization and carbonizing. SOLUTION: In preparing a raw material coal from 0-60wt.% of fine noncaking coal coal having <=80% caking power index (CI); defined in this invention} and remainder of caking coal, 10-50wt.% of the raw material coal is used as a coal having >=20kPa gas pressure in carbonization and remainder of the raw material coal is used as a coal having <20kPa gas pressure in the carbonization, then the raw material coal after the mixing is made to have >=0.8 bulk density by drying and/or adding a caking agent, thus charged in a coke oven and carbonized.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention provides a coke manufacturing method for obtaining high-strength coke in a blast furnace coke manufacturing process.

[0002]

2. Description of the Related Art In a conventional furnace-type coke manufacturing method, the coking coal composition is conventionally about 80% by weight of caking coal having a high caking property.
About 20 wt% or less of the above and the remaining raw material coal is charged into a coke oven by mixing the raw material coal with a non-caking coke having a low caking property, and is carbonized to produce a coke raw coal for a blast furnace. There is. Non-caking coal has more reserves and is less expensive than caking coal, so it is possible to reduce the price of coking coal by increasing the mixing ratio of the non-caking coal. . Therefore, a method for increasing the usage rate of the non-slightly caking coal in the raw coal has been conventionally developed, and the following method has been proposed.

[0003] For example, paying attention to the caking property of coal, by adjusting the crushing particle size of each coal and blending it, the caking property of the raw coal is improved during dry distillation, and the use ratio of non-slightly caking coal is increased. Particle size adjustment method (hereinafter referred to as CPCP method)
There is a coking coal method,
Volume 60, No. 653, p. 771-779 etc. In the CPCP method, in order to effectively utilize the caking properties of the raw coal during carbonization, coal containing a small amount of inert and high in vitrinite (hereinafter referred to as high quality coal) is, for example,-
Coarsely crushed to about 5 mm, and on the other hand, coal with a lot of inerts (hereinafter referred to as high-inert coal) is reduced to about -2 mm or less by reducing the crushed particle size as compared with high-quality coal to cause coagulation of raw coal during carbonization. Although the purpose is to improve the characteristics and the quality of coke, the upper limit of the amount of non-slightly caking coal used in this method is about 10 wt%.

[0004] In addition to the above, there is a method of partially charging shaped coal (hereinafter referred to as BBCP method) as a method for improving the bulk density of raw coal when charging it into a coke oven to improve coke strength. For details on how to enter, see Coal Chemistry and Industry (Sankyo Publishing Co., Ltd., Association 1988 edition) p. It was announced in 311 etc. In the BBCP method, a briquette having a bulk density higher than that of pulverized coal is added to the upper part of the coke oven to reduce the difference in the bulk density of the raw coal in the coke oven in the furnace height direction, and to reduce the total amount of coke dry-distilled in the coke oven. The purpose is to improve the quality of coke, but even in this method, the upper limit of the use rate of non-slightly caking coal is about 10 wt%.

Therefore, there has been a need for development of a simple method for producing blast furnace coke, which makes it possible to increase the use of inexpensive non-fine coking coal.

[0006]

As described above, it has been desired to develop a method for producing a high-strength blast furnace coke which enables an increase in the proportion of the non-slightly caking coal in the raw coal.

The present invention aims to present a method for producing high strength blast furnace coke.

[0008]

MEANS FOR SOLVING THE PROBLEMS The present invention is as follows: (1) When the raw coal is blended with 0 to 60 wt% of non-fine coking coal and the rest as coking coal, 10 to 50 wt% of the raw coal.
As a coal having a gas pressure during dry distillation of 20 kPa or more, and the rest of the raw coal is blended as coal having a gas pressure of less than 20 kPa during dry distillation, and charged into a coke oven so that a bulk density of a predetermined value or more is obtained. A method for producing high-strength coke, which comprises performing carbonization.

(2) Drying and / or adding a binder to the raw coal after blending and charging it into a coke oven,
The method for producing high-strength coke according to the item (1), wherein the bulk density is 0.8 or more.

[0010]

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific contents will be described below.

FIG. 1 is a diagram showing a method for producing coke for a blast furnace according to the present invention. 1 is a coal blending tank, 2 is a coal slicing device, 3 is a coking coal belt conveyor, 4 is a binder adding device, 5 is a coking coal supply hopper, 6 is a charging vehicle, and 7 is a coke oven.

The inside of the coal blending tank 1 is divided into partitions for each coal brand, and the blending ratio of each coal is discharged from the coal blending tank by the coal cutting device 2 under the coal blending tank according to a predetermined blending ratio. It is decided by. The coal cut out from the coal blending tank is conveyed by the coking coal belt conveyor 3. Part of the coal is charged into the binder addition device 4, charged into the raw material coal supply hopper 5 together with the rest of the raw material coal, and then charged into the coke oven 7 via the charging vehicle 6.

The present inventor examined a method for producing coke using coal having the properties shown in Table 1 by a carbonization test apparatus capable of simulating the coke production process as shown in FIG.

Since non-slightly caking coal has low fluidity and the gas pressure at the time of carbonization is low, the adhesion state of the coke substrate becomes poor, and the coke strength is low. On the other hand, the coke obtained by dry-distilling coking coal has a good adhesion state and thus has a high coke strength.

Therefore, the present inventor diligently studied a method for improving the coke adhesion state and improving the coke strength by increasing the expansion pressure when carbonizing carbon in the coke oven.

In the process of heating the coking coal in the coke oven to form coke, the coking coal charged in the coke oven progresses to coke from the furnace wall side, and the coke shrinks as shown in FIG. As shown in the example, the coke density in the center of the coke oven becomes low, and the coke adhesion becomes poor. In particular, when a large amount of non-slightly caking coal is blended, the coke strength is significantly reduced.

Therefore, a method for improving coke adhesion by improving the expansion pressure of coal during carbonization to improve coke strength and enabling the use of a large amount of non-fine coking coal was examined.

As shown in FIG. 5, the gas pressure during carbonization varies depending on the type of coal. The present inventor diligently studied a method of satisfactorily improving the adhesion state of coke by blending coal having a high expansion pressure during carbonization in a raw coal at a predetermined ratio. As a result, the coke strength is improved when 10 to 50 wt% of coal having a gas pressure during dry distillation of 20 kPa or more is blended in the raw coal and the rest of the raw coal has a gas pressure during dry distillation of less than 20 kPa. There was found.

Further, the relationship between the charging density of the raw coal and the coke strength was earnestly studied. As a result, when the charging density is 0.8 or more, the adhesion of coke after dry distillation is remarkably improved due to the bulk density improving effect, and as shown in FIG. It was found that an effect of improving coke strength can be obtained.

As a result of the above examination, it becomes possible to produce a high-strength blast furnace coke by the method of the present invention even when 40 to 60 wt% of non-caking coal is blended.

As a method of increasing the bulk density when charging the raw coal into the coke oven, there are a method of drying a part of the coal water content and a method of adding a binder. In order to use as much as 40 to 60 wt%, it is preferable to apply a process combining both of them. As a result of intensive studies by the present inventors, it is preferable that the water content of coal is 5% or less as shown in FIG. As the binder, tar, SOP (soft pitch),
A petroleum-based binder or the like can be applied, and it is preferable that the addition amount be about 3 to 10 wt% with respect to the raw coal.

The present inventor has used 40 to 60 wt.
%, A detailed investigation was conducted on a method for producing coke having high strength even with a raw material coal containing 100%. As a result, the water content of the raw coal containing 10 to 50 wt% of coal having an expansion pressure during dry distillation of 20 kPa or more was adjusted to 5% or less, and the binder was 5 w.
By adding t%, 40-60 wt% of non-caking coal
% Coke having a high strength can be produced even if the raw material coal containing 100% is used.

When the blending ratio of the non-lightly caking coal is increased, the caking property of the coal is lowered and the coke strength is lowered, so that the upper limit of the usage ratio of the non-lightly caking coal is preferably 60 wt%. In this specification, the coke strength is JIS K 2151.
The coke sample is measured by the drum strength test method described in 1. and is expressed as a weight ratio of the coke sample remaining on a 15 mm sieve after 150 rotations.

In the present specification, the non-slightly caking coal is a caking strength index (C
I) indicates coal with 80% or less. Cohesion Index (CI) is a dictionary of technical terms on coal utilization (edited by Japan Fuel Association, Showa 5).
8 years edition) p. 0.25 m as described in 255
Mix 1 g of coal of m or less with 9 g of powder coke of 0.25 to 0.30 mm, dry-distill in a magnetic crucible at 900 ° C. for 7 minutes, and then sieve with 0.42 mm to display the percentage of the weight remaining on the sieve. Is the way.

In this specification, the fluidity of coal is JIS M
It is the value measured by the Gissel plastometer described in 8801.

In the present specification, the expansiveness of coal is JIS M
It is the value measured by the dilatometer described in 8801.

[0028]

【Example】

(Example 1) A coke production test was carried out using a raw material coal having a composition 1 shown in Table 1 according to the method of the present invention. Formulation 1 is 20 wt% of caking coal A coal having an expansion pressure of 23 kPa, 40 wt% of cohesive coal B coal having an expansion pressure of 1.5 kPa, and 40 wt% of non-cohesive coal E coal having an expansion pressure of 0.9 kPa. % Each is composed by mixing. This raw coal has a water content of 3.5%
After adding 3 wt% of soft pitch to the raw coal, the bulk density was 0.82 and the coke oven was charged with 950.
It was distilled to ℃. As a result, as shown in FIG. 2, the strength of the obtained coke was as high as 85.0%, and high strength coke could be produced.

(Comparative Example 1) A coke production test was carried out using a raw material coal having a composition 2 shown in Table 1. Formulation 2 is 20 wt% of caking coal B coal with an expansion pressure of 1.5 kPa, 40 wt% of cohesive coal C coal with an expansion pressure of 10 kPa, and 40 wt% of non-fine coking coal E coal with an expansion pressure of 0.9 kPa. % Each is composed by mixing. 95% of this raw material coal was charged into a coke oven with a water content of 6.5% and a bulk density of 0.75.
It was distilled to 0 ° C. As a result, as shown in FIG. 2, coke having a strength of 82.0% and low strength as a blast furnace coke was obtained.

Example 2 A coke production test was conducted by using a raw material coal having a formulation 3 shown in Table 1 according to the method of the present invention. Formulation 3 is 1 caking coal A coal with an expansion pressure of 23 kPa
20w of cohesive coal B coal with 0wt% and expansion pressure of 1.5kPa
10% of caking coal D coal with t% and expansion pressure of 100 kPa
%, And an expansion pressure of 0.9 kPa for non-caking cohesive coal E coal 6
Each of them is mixed at 0 wt%. The raw coal was adjusted to have a water content of 3.5%, and 3 wt% of soft pitch was added to the raw coal. Then, the raw coal was charged into a coke oven with a bulk density of 0.82, and was dry distilled to 950 ° C. As a result, as shown in FIG. 3, the strength of the obtained coke was as high as 83.5%, and high-strength coke could be produced.

(Comparative Example 2) A coke production test was carried out using a raw material coal having a composition 4 shown in Table 1. Formulation 2 is 10 wt% of caking coal C coal having an expansion pressure of 10 kPa, 30 wt% of cohesive coal B coal having an expansion pressure of 1.5 kPa, and 60 wt of non-fine coking coal E coal having an expansion pressure of 0.9 kPa. %. This raw coal was placed in a coke oven with a water content of 6.5%,
It was charged at a bulk density of 0.75 and dried by distillation to 950 ° C. As a result, as shown in FIG. 3, a coke having a strength of 80.0% and a low strength as a blast furnace coke was obtained.

[0032]

[Table 1]

[0033]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to significantly increase the use ratio of inexpensive non-fine coking coal in the blast furnace coke manufacturing process and to manufacture high-strength blast furnace coke. It was The technical and economic effects of the present invention are very large.

[Brief description of drawings]

FIG. 1 is a diagram showing a blast furnace coke manufacturing process to which the present invention is applied.

FIG. 2 is a diagram illustrating an effect when the present invention is applied to the first embodiment.

FIG. 3 is a diagram showing an effect when the present invention is applied to a second embodiment.

FIG. 4 is a view showing a state of coke carbonization in a width direction of a coke oven.

5 (a), (b) and (c) are diagrams showing examples of expansion pressure during carbonization for each coal type.

FIG. 6 is a diagram showing the relationship between the bulk density of raw coal and the expansion pressure during carbonization.

FIG. 7 is a diagram showing a gold relationship between raw coal water content and coal bulk density.

[Explanation of symbols]

 1: Coal mixing tank 2: Coal cutting device 3: Coking coal belt conveyor 4: Binder addition device 5: Coking coal supply hopper 6: Charging vehicle 7: Coke oven

Claims (2)

[Claims] 1. When blending a raw coal with 0 to 60 wt% of non-slightly caking coal and the rest of the caking coal, 10 to 5% of the raw coal is mixed.
0 wt% was used as coal having a gas pressure during dry distillation of 20 kPa or more, and the rest of the raw coal was blended as coal having a gas pressure during dry distillation of less than 20 kPa, and charged into a coke oven so as to have a bulk density of a predetermined value or more. A method for producing high-strength coke, which comprises carrying out dry distillation. 2. The bulk density is adjusted to 0.8 or more by drying the raw coal after blending and / or adding a binder and charging it into a coke oven. High-strength coke manufacturing method.