JPS5898395A - Coal deashing - Google Patents

Abstract

PURPOSE:To deash coal in a shortened granulation time in a small apparatus, by classifying roughly crushed coal into coarse coal, fine coal and pulverized coal, and using a granule obtd. by pulverzation, oil addition, granulation and dehydration of the high-ash coarse and pulverized coals as a nucleus for oil addition/granulation of the low-ash fine coal. CONSTITUTION:Coal roughly crushed by a raw mill 1 is classified into coarse coal, fine coal and pulverized coal by a classifier 10. The coarse and pulverized coals of high ash content are introduced via line L1 into a pulverizer 2 and, after pulverized, introduced from a slurrying vessel 3 into an agitating granulator 4, in which they are granulated with supply of an emulsion from an emulsifying vessel 8, and then dehydrated by a dehydrator 9. The fine coal is intoduced via line L2 into a pulverizer 2A, while the dehydrated coal granule is introduced via the line L1 into the line L2. Although the primarily granulated coal is crushed again, it has a high granulating property and services as a nucleus, so that it is possible to shorten a granulation time, to decrease an amt. of added oil and to increase deashing rate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for deashing coal by hot oil granulation.

Coal contains ash, which deteriorates combustion efficiency and causes combustor blockage, which is a major problem in using coal. Therefore, various methods for removing ash from coal have been investigated, and a coal deashing process using hot oil granulation has been established as a promising method.

Hereinafter, a conventional coal deashing method using hot oil granulation will be described with reference to FIG.

After the dry coal is coarsely pulverized by a coarse pulverizer 1 such as a wet jaw crusher, the dry coal is further pulverized by a pulverizer 2 such as a wet ball mill. The finely pulverized coal is prepared into a coal slurry of an appropriate concentration in a slurry preparation tank 3, and then sent to an agitation granulator 4. On the other hand, aquarium 5,
Water, oil, and surfactant are sent from the oil tank 6 and the surfactant tank 7 to an emulsion preparation tank 8, where they are emulsified and sent to the stirring granulator 4. In the stirring granulator 4, coal and oil are combined and granulated, and the ash is dispersed in water and remains as a solid. The produced nine pellets are dehydrated in a dehydrator 9, and in this way the coal is deashed.

However, this method has the following drawbacks.

■ If the amount of ash dispersed in water increases, the amount of ash mixed into the granules will increase. Unless measures are taken, such as increasing the amount of water used or diluting the slurry concentration, the deashing rate will decrease. It is difficult to transport and is economically and operationally disadvantageous.

■ It is difficult to downsize the equipment because the granulation time is long.

■ It is economically disadvantageous because the oil temperature is large.

The present invention aims to improve the deashing rate of coal, shorten the granulation time, and downsize the equipment in a coal deashing method using hot oil granulation. After classification into fine granule coal and pulverized coal, coarse granule coal and pulverized coal with a high ash content are finely pulverized, granulated in oil, dehydrated, and the granules are processed into oil granulated coal with a low ash content. It is characterized by being used as a core when graining.

The outline of the coal deashing method of the present invention will be explained using FIG.

In addition, in the figure, the same reference numerals as in FIG. 1 have the same functions and effects.

The wet coal that has been coarsely crushed by the coarse crusher 1 is classified into coarse coal, fine coal, and pulverized coal by a dry classifier 10.

Comparing the grindability of the coal structure components, Durite (usually called dark coal, dull dark color, grainy structure, and hard) with a high ash content is difficult to grind and is concentrated in the coarse coal part. be done. On the other hand, fusite with a high ash content (charcoal-like appearance, soft and easily powdered) is easily crushed and concentrated in the pulverized coal portion. On the other hand, Pi) IJ) (Vitrit) with low ash content
θ: A homogeneous part usually called a luminescent flame, which is a typical part of coal. It has a black luster and a homogeneous feel like glass. relatively brittle and easy to powder) and clarit (C!1aritθ
; Usually the part called charcoal. It's shiny, but it doesn't have a homogeneous feel like glass. (relatively brittle) is concentrated in the fine coal part.

Utilizing these characteristics, the coal is divided into coarse and pulverized coal with a high ash content and fine granulated coal with a low ash content, and the coarse and pulverized coal with a high ash content is led to the pulverizer 2 through line L1. After pulverizing,
As in the case of FIG. 1, the slurry is led from the slurry preparation tank 5 to the stirring granulator 4, supplied with emulsion liquid from the cocote emulsion preparation tank 8, granulated at oil temperature, and dehydrated in the dehydrator 9. On the other hand, fine granulated coal is sent to the pulverizer 2A through line L2, and granulated coal dehydrated by the dehydrator 9 from the TJ 1 is introduced into this line L2. These are pulverized by a pulverizer 2A, guided to a slurry adjustment tank 6, then granulated by adding oil emulsion to an emulsion preparation tank 8 by a stirring granulator 4A, dehydrated by a dehydrator 9A, and deashed. Charcoal is obtained.

This method provides the following effects.

■ Coarse coal and pulverized coal with a high ash content are separated from the ash by primary deashing and granulation, but since the ash content dispersed in the slurry water is high, it is expected that a large amount of ash will be mixed into the granulated coal. Ru. Therefore, after the next granulation, the wastewater containing ash and the granulated coal are separated, the granulated coal is re-pulverized by two people using a pulverizer, and all the ash mixed in the granulated coal is washed out. By removing a large amount of ash from a large amount of coal during primary granulation, the amount of ash dispersed in water during secondary granulation is reduced.

By reducing the amount of ash mixed into the granulated coal in this manner, the deashing rate can be increased.

■ Once granulated, it is re-pulverized, but even if it is re-pulverized, the granulation property is high and it acts as a nucleus, which can shorten the granulation time and reduce the amount of oil cooling.

FIG. 3 shows another embodiment of the coal deashing method of the present invention. In the figure, books having the same reference numerals as those in FIGS. 1 and 2 have the same functions and effects, so their explanation will be omitted, and differences from FIG. 2 will be explained.

In FIG. 6, the granulated coal dehydrated in the dehydrator 9 is fed just before the slurry preparation tank 3A, and is used as a core during oil-hot granulation in the stirring granulation tank 4A.

This method provides the following effects.

■ Coarse coal with low yield and high ash content and pulverized coal are granulated in separate granulation tanks, the coal and ash are separated, water containing ash is discarded, and the granulated coal is granulated with fine granulated coal. Use it as a core when Therefore, when oil-washing and granulating fine-grained coal with a high yield and low ash content, the amount of ash dispersed in the slurry water is reduced, so the amount of ash mixed into the granulated coal can be reduced and the deashing rate can be improved. .

■ By using granulated coal as a core, granulation properties are improved, shortening granulation time and reducing the amount of oil cooling.

Example: After coarsely crushing Australian bituminous coal of 50-60 mm to less than 2 mm using a hammer cranyer, using a sieve of 2 o mesh 7 mm, 100 mesh 7 mm, 20 mesh over, 20 mesh ~ 100 mesh / Yu, 100 mesh under 6
After separating into groups, combine 20 mesh over and 100 mesh 7 under and make 20 mesh to 10
It was divided into two groups with 0 meshes.

Thereafter, the two separated groups were pulverized using a dry ball mill using a sieve with an opening of 74 microns each until the bottom of the sieve was about 76 inches, and then made into a 60% water slurry.
Add to this a polyoxyalkylene nonionic surfactant 30
An oil-cooled granulation deashing test was conducted using a batch two-oil cold granulator as shown in FIG. 4 by adding 0 ppm (based on coal) and 26 g (based on coal) of C heavy oil. In addition, as a surfactant, anionic type (alkylbenzene sulfonate, etc.), cationic type (dodecyltrimethylammonium chloride, etc.),
Amphoteric (carboxylic acid type) compounds can also be used. In FIG. 4, 40 is a batch type oil temperature granulator, 41 is an 85φX3Q Q Tomo granulation tank made of acrylic resin, 42 is an impeller inserted into the granulation tank 41, and 43 is the same impeller 42. The stirrer 44 is arranged to surround the granulation tank 41 and is a thermostatic tank.

Table 1 shows the analytical values of the Australian e* coal used in the test.

Table 1 daf weight %: dry ash free weight % Table 2 shows the yield and residual ash content of fixed volume lots classified using 20 mesh and 100 mesh sieves.
It is clear that the ash content of the fine particles ranging from 20 mesh to 100 mesh/unit is about 20% lower than that of other lots.

Tables 2 and 3 show the results of oil washing and granulation of each of the two divided samples.

Table 3 In Table 4, after dividing into high ash content and low ash content by classification operation, high ash content is granulated at oil temperature in the first stage, and low ash content is granulated in the first stage. We compared A, where Tokuno pellets were added in the stage, and B, where raw coal was finely pulverized and granulated with oil washing without any classification operation. It was confirmed that by adding ash as a seed during granulation of coal, the granulation time could be shortened and the amount of ash remaining in the pellets could be reduced.

Table 4

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing a conventional coal deashing method using oil section granulation, FIGS. 2 and 3 are flow sheets showing a specific example of the deashing method of the present invention, and FIG. The figure is a sectional view showing the structure of a batch type oil temperature granulator. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] In the hot oil granulation method, which uses the difference in the wettability of coal and coal-containing ash to water and oil to separate the coal and ash, after classifying coarsely crushed coal into coarse coal, fine coal, and pulverized coal, The coal is divided into two parts: coarse and pulverized coal with a high ash content, and fine granulated coal with a low ash content.The coarse and pulverized coal with a high ash content is pulverized, then granulated at oil temperature, deashed, and then dehydrated. A method for deashing coal, characterized in that the resulting granules are used as cores when fine granulated coal with a low ash content is pulverized and subjected to hot oil granulation.