JPH0328476B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a highly concentrated deashed coal-water slurry.

The coal-rich water slurry is a slurry fuel composed of 60 to 85% (wt%) coal, 0.01 to 5.0 wt% surfactant to coal powder, and water: the remaining weight%. The coal concentration and surfactant addition rate in a highly concentrated coal water slurry vary depending on the type of coal. Coal contains ash, but when a high-concentration water slurry of coal is burned in a boiler, the presence of ash reduces boiler efficiency, so it is preferable to remove as much ash as possible before combustion. . Further, by making the residual ash content in coal the same for each type of coal, it is possible to minimize variations in calorific value and combustion effect depending on the type of coal. Based on this background, a process for producing a highly concentrated coal water slurry incorporating a conventional deashing process will be explained with reference to FIG.

Put the raw coal 30 into the raw coal receiving tank 31 and quantitative feeder 3
2, the coal is supplied to a coal crusher 33. The coal crusher 33 crushes raw coal 30 of about 30 to 50 mm into fine coal 34 of about 3 mm or less. This fine coal 34 is screen 3
5, the coal is separated into coal 37 larger than 3 mm and coal 36 smaller than 3 mm. Coal smaller than 3mm36
is stored in the fine coal receiving tank 38. Coal 37 of 3 mm or more is returned to the raw coal receiving tank 31 again. Coal 36 smaller than 3 mm stored in the fine coal receiving tank 38 is fed at a constant rate by a metering feeder 39 to a pulverizer (usually a wet pulverizer) 40, where it is mixed with water 43 and is mixed with 200 mesh passes of 70 to 95%. Like pulverized coal 4
Finely ground to 1. Pulverized coal 41 is in the form of a coal-water slurry (approximately 45 to 55% by weight in terms of coal concentration) and is stored in pulverized coal storage tank 4.
2 is accepted. The pulverized coal 41 is water 1 separated from a dehydrator 2 after the flotation machine 1, which will be described later.
4, the concentration is adjusted to about 20 to 30% by weight, and the foaming agent 24 and the collecting agent 25 are supplied to the condition tank 4,
Coal with low ash content introduced into flotation machine 1 (clean coal) 11
It is divided into 12 types of coal (tail) with a high ash content. Coal (tail) 12 with a high ash content is sent to a wastewater treatment facility and disposed of.

Coal with a low ash content (clean coal) (1)(1) is dehydrated by dehydrator 2 to a coal concentration of approximately 20% water by weight.
The separated water 14 is reused to adjust the concentration of the pulverized coal 10 supplied to the conditioning tank 4 as described above. The cake-like clean coal 13 having a moisture content of approximately 20% is readjusted to the final coal concentration of a high coal concentration water slurry 15 using a surfactant aqueous solution 26 in a slurry adjustment tank 3.

The above is the coal high concentration water slurry production process incorporating the conventional deashing process. Here, in the conventional process, pulverized coal 41 having a considerably wide particle size range is simultaneously treated in the condition tank 4 and sent to the flotation machine 1.
However, when the conditioned tank 4, the pulverized coal 41, the foaming agent 24, and the collecting agent 25 are sufficiently stirred and mixed, there is a difference in the degree of adhesion of the foaming agent 24 and the collecting agent 25 between the pulverized coal 41 and the coarse granulated coal. This causes a large difference in the deashing process in the flotation machine 1 between fine coal and coarse coal, resulting in a decrease in the deashing efficiency of all pulverized coal.

In other words, since the surface area of fine coal is larger than that of coarse grain coal, the amount of foaming agent 24 and collecting agent 25 that adheres to it is large, but because the particle size is small, the flotation properties are poor and the adhesion to coarse grain coal is poor. Although the amount is small, the recovery rate of coal (clean coal) 11 with a low overall ash content is lower than the addition rate of foaming agent 24 and collecting agent 25 due to its large particle size and good flotation properties. This results in a relatively low percentage. Conversely, increasing the foaming agent 24 and collecting agent 25 improves the recovery rate of coal with a low ash content (clean coal) 11, but
The percentage of residual ash in 1 also increases. In other words, the deashing efficiency of the clean coal 11 has decreased, which is a problem.

Therefore, the present inventor completed the present invention as a result of intensive research in order to develop a process in which the clean coal recovery rate and deashing treatment efficiency can be efficiently maintained even when there are fluctuations in the coal particle size distribution.

That is, the present invention grinds coal to a particle size suitable for a highly concentrated coal-water slurry, classifies it into coal grain groups of larger particle size and smaller particle size, and separately infuses each classified coal particle group into a coal-water slurry. After adding and stirring a foaming agent and a scavenger in an amount corresponding to the particle size and surface area of the coal grains in each slurry, both coal-water slurries were separately subjected to flotation deashing treatment. The present invention relates to a method for producing a deashed high-concentration coal-water slurry, which is characterized in that clean coal obtained by ash treatment is combined into a high-concentration coal-water slurry.

Hereinafter, one embodiment of the present invention will be described with reference to FIG. In FIG. 2, the steps up to the pulverized coal storage tank 42 in FIG. 1 are the same and are therefore omitted.

A slurry of 70 to 95% pulverized coal 41 from a pulverized coal storage tank is classified into particles larger than 200 mesh and particles smaller than 200 mesh using a classifier 100 such as a wet cyclone. Coal particles 50 larger than 200 mesh are obtained by dehydrating coal (clean coal) 11 with a low ash content from the flotation machine 1 to about 20% water by weight using the dehydrator 2 in the same manner as explained in connection with FIG. The concentration is adjusted to about 20 to 30%, and the coal particles 50 larger than 200 mesh are sufficiently stirred by being supplied to the condition tank 4 together with the foaming agent 24 and the collecting agent 25, and foaming corresponding to the surface area of the coal particles 50 is carried out. It adheres to and collides with the agent 24 and the collecting agent 25.
Thereafter, it is introduced into a flotation machine 1, where it is separated into coal 11 with a low ash content (clean coal) and coal 12 with a high ash content (tail). Coal (tail) 12 with a high ash content is sent to wastewater treatment facility 115 and disposed of. Coal (clean coal) 11 with a low ash content is dehydrated by a dehydrator 2 to a coal concentration of about 20% water by weight, and the water 14 separated from the dehydrator 2 is used as coal larger than 200 mesh to be supplied to the conditioner 4. It is reused to adjust the concentration of particles 50. The cake-like clean coal 13 having a water content of about 20% forms part of a highly concentrated coal water slurry 15 in a slurry adjustment tank 3 with an aqueous surfactant solution 26 .

On the other hand, 150 coal particles of less than 200 mesh are also
This is also coal with a low ash content (clean coal) from the flotation machine 101.
The water 14 obtained by dehydrating 111 to about 20% water content by the dehydrator 102 reduces the coal concentration to about 20 to 30%.
The coal particles 150 of 200 mesh or less are sufficiently stirred, and the foaming agent 24 and the collecting agent 25 corresponding to the surface area of the coal particles 150 are supplied to the condition tank 104 together with the foaming agent 24 and the collecting agent 25. and adhesion,
make it collide. Thereafter, it is introduced into a flotation machine 101 and separated into coal 111 with a low ash content (clean coal) and coal 112 with a high ash content (tail). Coal ash-rich (tail) 112 is sent to wastewater treatment facility 115 and disposed of.

Coal with a low ash content (clean coal) 11 is sent to a dehydrator 102
The water 114 separated from the dehydrator 102 is dehydrated to a coal concentration of about 20% water by weight.
Coal particles of 200 mesh or less supplied to 4.15
Reused for adjusting the density of 0. Cake moisture approx.
20% clean coal 113 is mixed with a surfactant aqueous solution 26 in a slurry adjustment tank 3, and deashed coal high concentration water slurry 15
together with clean coal 13.

The flow of one embodiment of the present invention has been explained above, but to describe the general conditions in each step, the residence time of the coal-water slurry in each condition tank is 5 to 20 minutes, and the flotation conditions are PH
6-8, flotation coal concentration 5-30% by weight, flotation time 5
~20 minutes was adopted, and in the condition bath, foaming agents such as α-terpineol and methyl isobutyl carbinol and scavenging agents such as kerosene were used.
A weight proportion of the mixture (flotation agent) is added.

Example Daido coal with a grain size of 200 and a mesh pass of 70% was treated according to the flow shown in Figures 1 and 2. For both flows, the residence time in the conditioned tank was 7 minutes, and the flotation conditions were PH6 in a Fahrenwald type flotation machine.
~8. The flotation coal concentration was 10% by weight, and the flotation time was 7 minutes. In both flows, the flotation agent added to the conditioned tank was in a ratio of 1 part α-terpineol (foaming agent) to 4 parts kerosene (collecting agent).

However, in the flow shown in Figure 1, 800 ppm of flotation agent per coal is added to conditioned tank 4, and in the flow shown in Figure 2, 500 ppm of flotation agent per coal is added to conditioned tank 4 (coarse particle side). A flotation agent was added to tank 104 (fine particle side) at 800 ppm per coal.

The results are shown in FIG. In FIG. 3, the horizontal axis shows the deashing rate (%), and the vertical axis shows the pure coal recovery rate (%).
Graph A shows the results of the flow shown in FIG. 2 (method of the present invention), and graph B shows the results of the flow shown in FIG. 1 (conventional method).

[Brief explanation of drawings]

Figure 1 is a production flow of a deashed highly concentrated coal-water slurry incorporating a conventional deashing process, Figure 2 is a flowchart of the present invention, and Figure 3 is a graph showing the effects of the present invention. .

Claims (1)

[Claims] 1. Pulverize coal to a particle size suitable for highly concentrated coal-water slurry, classify it into coal grain groups of larger particle size and smaller particle size, make each classified coal particle group separately into coal-water slurry, and After adding and stirring a foaming agent and a scavenger in an amount corresponding to the particle size and surface area of the coal grains in the slurry, both coal-water slurries were subjected to flotation and deashing treatment separately, and the resulting product from each deashing treatment was 1. A method for producing a deashed high concentration coal-water slurry, which comprises combining the purified coal to form a high concentration coal-water slurry.