JPS58194990A - Treatment of coal - Google Patents

Abstract

PURPOSE:To obtain a raw material giving coke of good quality with low cost, by a process wherein coked coal is crushed, dried, and then separated into coarse coal and pulverized coal, which is deashed and thereafter mixed with the coarse coal again. CONSTITUTION:Coking coal from coal yard 1 is ground into pieces at a crushing stage 2 and blended in a blender 3 in a given ratio to produce a blended coal, which is then dried in a dryer 4. Then pulverized coal of a high ash content is separated, extracted out of the blended coal by, e.g., air classification in the dryer 4 and collected by a dust collector 5 to suppress dust scattering. After being deashed in a deashing stage 6, the collected pulverized coal is mixed with coarse coal not collected by the collector 5 again, and the mixture is fed to a coke oven 7 and carbonized to give a coke of good quality.

Description

[Detailed Description of the Invention] This invention selectively extracts the pulverized coal portion generated in the coal pre-treatment process for producing coke for blast furnaces, and deashes the pulverized coal portion that has a characteristic of high ash content. In particular, it relates to a method for obtaining high quality coke.

The coke industry is actively researching and developing technology to strengthen resource handling capabilities and improve quality. As one of these methods, a method is well known in which ash, which has a large effect on coke quality, is removed by deashing. The ash content in the coal is fixed in the coke as it is during the carbonization process, but the presence of the ash content in the coke gives rise to internal stress, which gives rise to cold coke strength (drum index) Kgel'.

Furthermore, it is generally known that alkali oxides (Na□0K20) in the ash act as catalysts in the reaction between coke and CO2, and the presence of ash increases the strength after hot coke reaction (C8R). have a major impact on

Therefore, although coke quality can be improved by removing the ash content in coal and lowering the coke ash content, K has not yet become widespread.

The reason is as follows.

As deashing technology, O, A, method (all mgglome
Many methods have been proposed, including pulverization, but all of them have low deashing efficiency unless the coal is pulverized, and therefore pulverization requires a huge amount of energy.

The present invention eliminates the drawbacks such as overburden, separates the pulverized coal contained in the charged coal, and selectively deashes the ash concentrated in the pulverized coal, reducing the processing energy. The purpose of this project is to reduce carbon dioxide emissions and improve coke quality.The gist of the project is to pulverize melted coke coal, dry it, sort it into pulverized coal and coarse granulated coal, and then demineralize it into the pulverized coal. This is a method for treating coal which, after being treated, is mixed with the coarse coal again to use as a raw material for coke production.

The present invention will be described in detail below based on examples.

When producing coke for blast furnaces, generally, multiple types of coking coal are blended and pulverized, or each brand is pulverized and then blended. The method used is to obtain a coal blend and supply it to a coke oven. When blending multiple types of coking coal, the degree of mixing is increased and the coke is crushed in batches to produce homogeneous coke with high lump strength. In this case, if we look at the particle size structure of the blended coal more microscopically, it is found that in the normal blending and pulverizing method and the pulverizing and blending method, it is about 3 m or less, for example, 1 in 87
Approximately 81 tons of powder (flt) with less than 0 mesh. □LJ67?6゜゛(:・ Therefore, when we investigated the properties of the pulverized coal portion and the remaining coarse granulated coal portion in the charged coal, we obtained the following results.

First, as shown in Figure 1, coarse grain coal B (9
Table 1 shows the results of investigating the properties of coal when pulverized coal A (2% by weight) and less than pulverized coal A (8-weight [1] was separated, and the conventional separation method (A + B)).

As shown in the tiEx table above, the pulverized coal part AK has concentrated ash and sulfur content. On the other hand, regarding the relationship between the deashing zone and the coal particle size, it is generally known that the smaller the particle size, the higher the deashing capacity.゛The feature of the present invention is that by deashing the pulverized coal portion where the ash content in the charged coal is concentrated, the power deashing efficiency is increased and high quality coke is obtained with low cost deashing.

Next, under the same classification particle size as above, coke was produced by electric furnace soaking, and a comparison was made between the case where A was deashed and the case where it was not treated. A obtained by decalcification is referred to as A'.

The results are shown in Table 2.

As a result of deashing Table 2 A, the coking coal & (Aah) decreases and the coke cold strength (DI, ) and hot strength (C
8R) Id has improved. In particular, the improvement in CAH is large.

In the above test examples, the preferred separation limit for pulverized coal was set at 200 meshes, but it goes without saying that the optimal classification point may be slightly higher or lower than 200 meshes depending on the properties of the coal, the operating conditions of the coal dryer, etc. It is.

Next, an embodiment of the present invention is shown in FIG. This will be explained based on an application example in combination with method A.

In the ti/c2 diagram, coal taken out from a coal yard 1 is crushed in a crushing step 2 and stored in a blending tank 3, from which a constant feedware is used to make blended coal of a predetermined ratio. The blended coal is dried in a dryer 4, for example, from an average content of 9 g to about 2 to 5 g. In the dryer 4, the pulverized coal portion of the blended coal is selected and extracted by a method such as wind classification, and collected in a dust collector 5 for preventing initial production release. The collected pulverized coal is partially added with heavy oil in the deashing process 6, and after being deashed and mixed with the coarse coal part that was not collected in the dust collector 5 in the drying process, it is conveyed to the coke oven 7. It is carbonized. In addition, we will explain the method of the present invention, which is deashed using methods O and A in Fig. 2, mixed with the remaining coarse granulated coal, and then used as a raw material for coke production. It is also an effective method to inject the pulverized coal portion from the tuyeres as auxiliary fuel for the blast furnace. In the case of kernels, the raw material for coke production is the remainder from drying step 4, coarse coal part B, but as shown in Table #c1, coarse coal part B has low ash content and high caking properties, so it is of good quality. Coke is obtained. Table 3 shows the results obtained in the electric furnace experiment.

Table 3 On the other hand, the deashed pulverized coal part is used as auxiliary fuel for blast furnaces, and because it has a low ash content, high combustion efficiency can be obtained, and there is also little ash adhesion to the tip of the tuyere, making it extremely It has been confirmed that it has high drying properties.

As described above, the present invention limits the target of deashing to the pulverized coal portion of the charged coal, thereby making it possible to achieve high deashing efficiency and low cost deashing, and to reduce the value of stones and stones. It is possible to raise the level to an extremely high level, and by adopting the method of the present invention, great economic effects can be obtained.

FIG. 1 is a diagram showing the particle size and ratio after pulverizing coal for coke production, and FIG. 2 is a system diagram showing an embodiment of the present invention.

l...Crusher for coal yard 2 3...Blending tank 4...Dryer 5...Dust collector
6... Deashing equipment 7... Coke oven

Claims (1)

[Claims] Coal for coking is pulverized and dried, then sorted into pulverized coal and coarse granulated coal, and then the pulverized coal is subjected to deashing treatment and then mixed with the coarse granulated coal again to be used as a raw material for coke production. coal treatment method.