JPH11241073A - Method for pretreating coal for coke making - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretreatment method for introducing coal for coke making into a chamber type coke oven without raising dust. SOLUTION: In making coke by introducing coal for coke making into a chamber type oven, the coal for coke making containing not less than 40% caking coal is previously subjected to dry classification in a fluidized bed and then, the coarse coal and the fine coal after classification are preheated to 300-400 deg.C. Subsequently, the fine coal is formed into massive coal having a bulk density of not smaller than 1.12 g/cm<3> by a roll-type mass-making machine under a roll pressure of not lower than 3 t/cm and subsequently, the massive coal is mixed with the preheated coarse coal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pretreating coking coal for use in the production of coke for metallurgy, particularly for coke for blast furnaces, and more particularly to a pretreatment for charging coking coking coal into a room-type coke oven. It's about the method.

[0002]

2. Description of the Related Art In recent technology for producing coke for metallurgy, particularly coke for blast furnaces, coke oven charging coal has been dried in advance in order to shorten the carbonization time or reduce the use ratio of expensive caking coal. A method of charging the coke oven after it is wet is adopted. For example, in a method called a humidified coal charging process, the water content of coking coal is adjusted to about 6%, and in a method called a preheating coal charging process, the water content becomes 0%. It has been preheated and dried.

[0003] In the method of reducing the water content of the charged coal, the productivity can be improved by shortening the carbonization time, and the coke strength can be increased by increasing the charging density of the raw coal in the coke oven. Therefore, there is an advantage that the use ratio of non-coking coal can be increased if a constant coke strength is maintained.

[0004] However, when the charged coal is dried in advance as described above, the fine powder originally aggregated by moisture is separated from the lump, and the charged fine powder is charged into a coke oven. When it is dusted. For this reason, in the humidified coal charging process, the lower limit of the water content is limited to 6%. On the other hand, in the preheating charcoal charging process, although the measures are taken by suction from the double main or the like, there have been problems such as mixing of dust coal into by-products and carbon adhesion to the furnace upper part and riser pipe.

Therefore, Japanese Patent Application Laid-Open No. 9-48977 and the like disclose:
Regarding the preheated charcoal charging process, the raw coal is preheated and dried, then classified into pulverized coal and coarse coal, the pulverized coal is hot agglomerated, and then the coal is preheated to the coarse coal. A method of mixing and charging the coke oven has been proposed. However, in the method according to this proposal, the agglomeration conditions of pulverized coal at high temperatures are determined by productivity and the quality of agglomerated coal, and if the conditions are not appropriate, dusting of pulverized coal may not be prevented. there were.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to propose a pretreatment method for charging coke raw coal into a room-type coke oven without dusting.

[0007]

As a technique capable of advantageously achieving the above-mentioned object, the present invention provides a coke oven having a coke oven of 40% in coking coal production.
The raw coal containing above is dried and classified in a fluidized bed in advance, and then
The classified coal and pulverized coal are preheated to a temperature of 300 to 400 ° C., and then the pulverized coal is agglomerated by a roll-type agglomerating machine having a roll pressure of 3 t / cm or more to obtain a bulk density of 1.12 g / cm 2. The present invention proposes a pretreatment method for raw coal for coke, which comprises forming a lump coal having a size of ³ cm or more and then mixing the coal with the preheated coarse coal. In the above-mentioned coking coking coal pretreatment method, when agglomerating pulverized coal, the volume of the
It is preferable to be 34 cc or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the pretreatment method of coking coal for coke according to the present invention, caking coal is mixed in pulverized coal after dry classification in order to obtain a required agglomerate coal strength. Therefore, coking coal containing at least 40% caking coal is used (see FIG. 2).

The drying of the raw coal is carried out by using a fluidized bed dryer capable of classifying pulverized coal simultaneously with drying from the viewpoint of efficiency. In particular, in the present invention, in order to increase the strength of the agglomerated coal, the raw coal after the dry classification is preheated to 300 ° C or more and 400 ° C or less. The reason is that the higher the preheating temperature of the raw coal, the higher the strength of the agglomerated coal. However, if the temperature exceeds 400 ° C, stickiness of the coal appears and troubles such as clogging occur in the rolling process. On the other hand, if the temperature is lower than 300 ° C., the required strength of the agglomerated coal cannot be obtained (see FIG. 3).

In the agglomeration of pulverized coal in the present invention, a roll-type agglomerator is used in consideration of productivity. The shape of the agglomerated coal formed using this roll-type agglomerator is not particularly limited, and may be, for example, a Pillow type, a Macek type, or an almond type. It is necessary for the agglomerated coal having such a shape to have at least a bulk density of 1.12 g / cm ³ or more and secure an I-type strength as shown in FIG. When the volume of the agglomerated coal increases, the thickness of the agglomerated coal increases, and the roll pressure during the agglomeration becomes difficult to be transmitted to the inside of the agglomerated coal, so that the bulk density decreases and the strength decreases. Therefore, in the present invention, the volume of agglomerated coal
It is desirable to make the following (see FIG. 6). In addition, the higher the roll pressure during agglomeration, the higher the strength of the agglomerated coal, but 3 tons are required to maintain the bulk density of the agglomerated coal at 1.12 g / cm ³ or more.
/ Cm or more (see FIG. 5). The roll pressure in the present invention means a linear pressure per width in the roll axis direction.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG. FIG. 1 is a diagram showing a typical flow for producing coke. In this figure, when coke is produced by charging coking coal into a coke oven furnace, first, coking coal containing caking coal at a predetermined ratio is loaded into a fluidized bed dryer using hot air. Is entered. At this time, the pulverized coal is discharged together with the hot air, collected by a bag filter or the like, and classified as coarse coal. Next, the classified coarse coal and fine coal are respectively charged into a pneumatic conveying type preheater using hot air and preheated to a predetermined temperature. Thereafter, the pulverized coal is charged into a roll-type hot agglomerating machine adjusted to a predetermined pressure to form a compacted coal having a predetermined volume. Will be charged.

[0012] In producing coke in this manner, I-type strength is used as an index indicating the degree of generation of fine powder contributing to dust generation at the time of handling up to charging the coke oven with respect to the agglomerated coal prepared under predetermined conditions. Was measured. The results are shown in FIGS. The I-type strength was evaluated by placing 200 g of an agglomerated carbonized product in a cylinder having a length of 700 mm and a diameter of 130.8 mm, and the weight ratio of powder of 1 mm or more after 60 rotations. Here, the allowable value of dust generation based on the conventional knowledge is about 70 at this I-type strength.

FIG. 2 is a graph showing the relationship between the ratio of use of caking coal and the I-type strength of compacted coal prepared by changing the ratio of caking coal contained in the raw coal. At this time,
The preheating temperature of the raw coal was 300 ° C., the roll pressure was 3 t / cm, and the bulk density of the compacted coal was 1.12 g / cm ³ . As is clear from this figure, it is understood that the use ratio of the caking coal can satisfy the allowable value of the I-type strength at 40% or more.

FIG. 3 is a graph showing the relationship between the preheating temperature and the I-type strength of the agglomerated coal prepared by changing the preheating temperature of the raw coal. At this time, the caking coal usage ratio is 40
%, The roll pressure is 3 t / cm and the bulk density of agglomerated coal is 1.12.
g / cm ³ . As is clear from this figure, it is understood that the preheating temperature of the raw coal during hot agglomeration can satisfy the allowable value of the I-type strength at 300 ° C. or higher.

FIG. 4 is a graph showing the relationship between the bulk density of the compacted coal and the I-type strength of the compacted coal prepared by changing the bulk density. At this time, the coking coal use ratio was 40%, the preheating temperature of the coking coal was 300 ° C., and the roll pressure was 3 t / cm. As is clear from this figure, the bulk density of agglomerated coal is 1.
It is understood that the allowable value of the I-type strength can be satisfied at 12 g / cm ³ or more.

FIG. 5 is a graph showing the relationship between the roll pressure and the I-type strength of the agglomerated coal prepared by changing the roll pressure. At this time, the ratio of caking coal used was 40%, the preheating temperature of coking coal was 300 ° C, and the bulk density of agglomerated coal was 1.12 g / cm
^{It was set to 3} . As is clear from this figure, the roll pressure is
It is understood that the allowable value of the I-type strength can be satisfied at 3 t / cm or more.

FIG. 6 is prepared by changing the volume of agglomerated coal.
The relationship between the volume of compacted coal and the I-type strength is shown.
This is a graph. At this time, the ratio of caking coal use is 40%,
The preheating temperature of coal is 300 ° C and the roll pressure is 3t / cm.
The bulk density of agglomerated coal is 1.12 g / cm ^ThreeAnd It is clear from this figure
As expected, the volume of agglomerated coal is less than 34cc and I type strength is acceptable.
It can be seen that the value can be satisfied.

[0018]

As described above, according to the pretreatment method of the present invention, it is possible to prepare agglomerated coal having a very small degree of generation of fine powder contributing to dust generation, and as a result, to obtain dried preheated coal. It can be charged in a coke oven without generating dust.

[Brief description of the drawings]

FIG. 1 is a diagram showing a typical flow for producing coke.

FIG. 2 is a graph showing the relationship between the usage ratio of caking coal contained in the raw coal and the I-type strength.

FIG. 3 is a graph showing the relationship between the preheating temperature of raw coal and the I-type strength.

FIG. 4 is a graph showing the relationship between bulk density of compacted coal and I-type strength.

FIG. 5 is a graph showing the relationship between the roll pressure and the I-type strength of the roll-type compacting machine.

FIG. 6 is a graph showing the relationship between agglomerated coal volume and I-type strength.

Claims (2)

[Claims] 1. To prepare coke by charging coking coal into a coke oven furnace, coking coal containing at least 40% of caking coal is dried and classified in a fluidized bed in advance, and then the coarse The pulverized coal and pulverized coal are preheated to a temperature of 300 to 400 ° C., and thereafter, the pulverized coal is agglomerated by a roll-type agglomeration machine having a roll pressure of 3 t / cm or more to obtain a bulk density of 1.12 g / cm ³ or more. A method for pretreating coking coking coal, comprising agglomerating coal and mixing with the preheated coarse coal. 2. A volume of 34 cc for agglomerating the pulverized coal.
The pretreatment method according to claim 1, wherein the following agglomerated coal is used.