JPS5898393A - Coal deashing - Google Patents

Abstract

PURPOSE:To economically deash coal in the oil addition/granulation method by preliminarily separating roughly crushed coal into a low-ash floating material and a high-ash sediment by dense medium separation using a gravity liquid and pulverizing only the sediment. CONSTITUTION:Coal roughly crushed into particle size <=2mm. by a raw crusher 1 is separated into a floating material and a sediment in a dense medium separator 10 by dense medium separation using a gravity liquid. Said liquid may be either an inorg. one such as a cool dressing waste liquid or an org. one such as a benzene/carbon tetrachloride mixt. The floating material is withdrawn as such via a line L1 as a product because of its low ash content. The sediment is transferred via a line L2 to a granulating deashing step. It is introduced into a pulverizer 2, slurrying vessels 3 and agitating granulator 4 and, after granulated with addition of an oil emulsion from an emulsifying vessel 8, dehydrated to obtain deashed coal. It is possible to reduce the ash content from 6wt% to 5.4% and an amt. of added oil from 26wt% to 9%, as compared with the conventional method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a coal deashing method using hot oil granulation.

Coal contains ash, which deteriorates combustion efficiency and causes blockage of combustors, which is a major problem when using coal. Therefore, various methods for removing the ash content 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 oil hot granulation will be described with reference to FIG.

Coal is coarsely crushed by a coarse crusher 1 such as a dry or wet show crusher, and then further finely crushed by a fine crusher 2 such as a dry or wet ball mill. The finely pulverized coal is prepared into a coal-water 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, and the emulsified product is sent to the stirring granulator 4. In the stirring granulator 4, coal and oil are combined and granulated, and ash remains dispersed in water. The produced pellets are dehydrated in a dehydrator 9, and in this way, coal Φ is deashed.

However, this method has the following drawbacks.

■ If there is a large amount of ash dispersed in the water.

This is because there is a large amount of ash mixed into the granules.

Unless measures are taken such as increasing the amount of water used and diluting the slurry concentration, it will be difficult to improve the deashing rate, and from an economic and operational point of view,
It is disadvantageous.

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

■ It is economically disadvantageous because there are many oil-cold products.

SUMMARY OF THE INVENTION The present invention aims to reduce noise reduction in a coal deashing method using hot oil granulation, reduce power costs for coal crushing, and reduce water usage for separating ash. , Coarsely pulverized coal is separated into a heavy liquid using a specific gravity liquid, the floats with a low ash content are used as a product as is, and the sediment with a concentrated ash content is finely pulverized and deashed using an oil-cooled granulation method. °.

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

In FIG. 1, the same reference numerals as in FIG. 1 have the same effects.

The coal that has been coarsely crushed to about 2 WrM or less in the coarse crusher 1 is subjected to heavy liquid separation using a specific gravity liquid in a heavy liquid separation tank 10 to separate it into floats and sediments. As a specific gravity liquid, copper oxide (FeO
There are inorganic types such as silicates (or equivalent), magnetite, pyrite, and coal waste, and organic types such as halogenated hydrocarbons, such as benzene-carbon tetrachloride mixtures.

Since the floating material has a low ash content, it can be used as a product on line L.
Take out from 1. On the other hand, since the sediment has a high ash content, the granulation and deashing operation is started from line L2, as in the case of Fig. 1 of J.
After being finely pulverized by the pulverizer 2, the slurry is fed into the slurry adjustment tank 5, then into the agitation granulator 4, where an oil emulsion is added from the emulsion preparation tank 8 and granulated, followed by a dehydrator? to obtain deashed coal.

The ash content of the float can be freely changed by selecting the specific gravity of the heavy liquid in the heavy liquid separation tank.

The method of the present invention provides the following effects.

■ The floating material has a low ash content, so it is expected that the deashing effect will be small even if it is granulated at oil temperature, but since only the sediment is granulated and deashed, the amount of coal to be granulated and deashed will be reduced. , the added oil t' can be reduced in proportion to the amount of coal processed.

■ After coarse pulverization, heavy liquid is separated and only the deposits are pulverized and deashed, reducing the amount of coal to be processed, reducing the amount of pulverizing power and water used.

Example: After coarsely crushing Chinese bituminous coal of 50-60III11 and Datong coal using a hammer crusher to less than 0.5cm, Co/+ -C with a specific gravity of 1.65! After separating the heavy liquid using a 6H6-based specific gravity liquid, dry the precipitate, and use a dry ball mill to pulverize it to a 76% sieve with a 74μ mesh opening.Then, mix the pulverized coal with a 60% water slurry. 500 pp of polyoxyalkylene nonionic surfactant
An oil hot granulation deashing test was conducted using a batch two-oil cold granulator as shown in FIG. In addition, as a surfactant, anionic (alkylbenzene sulfonate, etc.), cationic (alkylbenzene sulfonate, etc.)
dodecyltrimethylammonium chloride, etc.), and amphoteric (carboxylic acid type) ones can also be used. In FIG. 5, 40 is a batch type oil temperature granulator, 41 is an 85φ x 300+ nm granulation tank made of acrylic resin, 42 is an impeller inserted into the granulation tank 41, and 43 is the same impeller 4.
The stirrer 2 and 44 are constant temperature baths arranged so as to surround the granulation tank 41.

Table 1 shows the analysis results of the composition of the coal used in the test.

Tables 1 and 2 show the yields of floats and precipitates and residual ash content by gravity separation.

Table 2 Table 3 shows a comparison between result A, in which the precipitate from heavy liquid separation was granulated at oil temperature and deashed, and result B, in which raw coal was pulverized and then granulated at oil temperature without heavy liquid separation. I did it.

In Tables 3 and 4, taking into account the results in Tables 1 to 5, we show the difference between the method of the present invention using both specific gravity separation and oil temperature granulation, and the conventional method of only performing oil temperature granulation without using both. We compared the noise reduction and residual ash amount required for hot oil granulation.

Table 4 Looking at the total amount of recovered coal as described above, in the method of the present invention, compared to the conventional method, the ash content decreased from 60 heavy lids to 5.4% by weight, and the amount of oil cooling decreased from 26.0% to 9.0% by weight. It can be said that it is a very economical and efficient deashing method.

[Brief explanation of the drawing]

Figure 1 is a flow sheet showing a conventional coal deashing method using oil hot granulation, and Figure 2 is a flow sheet showing a coal deashing method of the present invention using both specific gravity separation and oil hot granulation. be. FIG. 5 is a sectional view showing the structure of a batch type oil temperature granulator. Sub-Agents 1) Meifuku Agent Hagiwara Sales -

Claims (1)

[Claims] In the oil hot granulation method, which separates coal and ash by utilizing the difference in wettability of coal and coal-containing ash to water and oil, coarsely crushed coal is separated from a heavy liquid using a specific gravity liquid, resulting in flotation with a low ash content. A coal deashing method that is characterized by separating coal into coal and ash-rich sediment, pulverizing only the sediment, and deashing it by oil hot granulation.