JPH0328475B2 - - Google Patents

Description

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

Highly concentrated coal water slurry consists of 60-85% coal (weight%), surfactant 0.01-5.0% by weight (based on coal powder),
Moisture: Slurry fuel made up of the remaining weight percent. 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 efficiency 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 to a pulverizer (usually a wet pulverizer) 40 by a quantitative feeder 39, and while being mixed with water 43, 200 mesh passes 70 to 95%. The coal is pulverized into pulverized coal 41 as shown in FIG. The pulverized coal 411 is received in the pulverized coal storage tank 42 in the form of a coal-water slurry (coal concentration of about 45 to 55% by weight). And pulverized coal 41 is
The water 14 separated from the dehydrator 2 after the flotation machine 1 (to be described later) is concentrated to about 20 to 30% by weight, and is supplied to the condition tank 4 together with the foaming agent 24 and the collecting agent 25, where it is flotated. Coal is introduced into coal 1 and 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 a wastewater treatment facility and disposed of.

The coal (clean coal) 11 with a low ash content is dehydrated by the 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, in condition tank 4, pulverized coal 41 and foaming agent 24,
When the collecting agent 25 is sufficiently stirred and mixed, there will be a difference in the degree of adhesion of the foaming agent 24 and the collecting agent 25 depending on the fine and coarse particle size of the pulverized coal 41, and the fine powder will be used for the deashing process in the flotation machine 1. A large difference occurs between coal and coarse coal, and the deashing efficiency of all pulverized coal decreases.

In other words, since the surface area of pulverized coal is larger than that of coarse granulated 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 granulated coal is poor. Although the amount is small, the recovery rate of coal (clean coal) 11 with 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 small 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 highly concentrated coal-water slurry, classifies it into coal grain groups of larger particle size and smaller particle size, and separately converts each classified coal particle group into coal-water slurry. After adding and stirring a foaming agent and a collecting agent in an amount corresponding to the particle size and surface area of the coal grains in each slurry, the two coal-water slurries are combined and subjected to flotation deashing treatment. The present invention relates to a method for producing a characteristic deashed highly concentrated 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 200 mesh pass 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, which are larger than 200 mesh, are sufficiently stirred and supplied to the conditioned tank 4 together with the foaming agent 24 and the collecting agent 25. It adheres to and collides with the foaming agent 24 and the collecting agent 25.

On the other hand, 150 coal particles of less than 200 mesh are also
This is also low ash coal (clean coal) 11 from flotation machine 1.
The coal concentration is adjusted to about 20 to 30% using water 14 which has been dehydrated to about 20% water content by the dehydrator 2, and is supplied to the conditioning tank 104 together with the foaming agent 24 and the collecting agent 25 to reduce the coal concentration to 200 mesh or less. coal particles 15
The coal particles 150 are sufficiently stirred to adhere and collide with the foaming agent 24 and the collecting agent 25 corresponding to the surface area of the coal particles 150. Thereafter, the above-mentioned coal particles 50 larger than 200 mesh are introduced into the flotation machine 1, and coal with a low ash content (clean coal) 11 and coal with a high ash content (tail) 12 are introduced into the flotation machine 1.
It is divided into 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 approximately 20% water by weight, and water 14 separated from the dehydrator 2 is passed through the condition tanks 4 and 104.
It is reused to adjust the concentration of coal particles supplied to the The cake-like clean coal 13 having a water content of about 20% is turned into a deashed coal high concentration water slurry 15 with a surfactant aqueous solution 26 in the slurry adjustment tank 3.

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) 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 Deashing is characterized by 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, and then combining the two coal-water slurries and subjecting them to flotation deashing. Method for producing ash-high concentration coal-water slurry.