JPH0329114B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a highly concentrated coal-water slurry, and in particular to a highly concentrated coal-water slurry with high coal recovery rate and high deashing rate.
It is an object of the present invention to provide a method for producing a water slurry.

In the present invention, a highly concentrated coal water slurry generally includes 60 to 85% (by weight) coal and 0.01 to 0.01 to 80% surfactant.
Means a slurry fuel consisting of 5.0% by weight (based on coal powder) and the remainder water. The coal concentration and surfactant addition rate in a highly concentrated coal water slurry vary depending on the type of coal. Coal contains ash, and if ash is present when a high-concentration coal water slurry is burned in a boiler, the efficiency of the boiler will decrease, so it is preferable to remove as much ash as possible before combustion. In addition, aligning the residual ash content in coal to the same value for each coal type means that the calorific value of each coal type,
This has the effect of minimizing variations in combustion efficiency. Based on this background, a coal high concentration water slurry manufacturing process incorporating a conventional deashing process will be explained with reference to FIG.

Raw coal 30 is put into a raw coal receiving tank 31, and then supplied to a coal crusher 33 by a quantitative feeder 32. The coal crusher 33 crushes raw coal 30 having a particle size of approximately 30 to 50 mm into fine coal 34 having a particle size of approximately 3 mm or less. The fine coal 34 crushed in this way is separated by a screen 35 into coal 37 with a particle size of 3 mm or more and coal 36 with a particle size of less than 3 mm. Coal 3 with particle size smaller than 3mm
6 is stored in the fine coal receiving tank 38. On the other hand, coal 37 of 3 mm or more is returned to the raw coal receiving tank 31 again. Coal 36 with a particle size smaller than 3 mm stored in the fine coal receiving tank 38 is supplied at a constant rate to a pulverizer (usually a wet pulverizer) 40 by a quantitative feeder 39, and is mixed with water 43 for 200 mesh passes. 70
It is comminuted to pulverized coal 41, such as ~95%. The pulverized coal 41 is received in a pulverized coal storage tank 42 in the form of a coal-water slurry (coal concentration of about 45 to 55% by weight). Then, the pulverized coal 41 is mixed with water 14 separated from the dehydrator 2 installed after the flotation machine 1, which will be described later.
The concentration is adjusted to % by weight, and the conditioned tank 4 is supplied with a foaming agent 24 and a scavenger 25, and the flotation machine 1
The coal is introduced into coal and is divided into coal with a low ash content (clean coal) 11 and coal with a high ash content (tail) 12. Coal (tail) 12 with a high ash content is sent to a wastewater treatment facility and disposed of. On the other hand, coal with low ash content (clean coal) 11
is dehydrated by the dehydrator 2 to a coal concentration of approximately 20% water by weight, and the water 14 separated by the dehydrator 2 is reused to adjust the concentration of pulverized coal 41 supplied to the conditioning tank 4. The cake-like clean coal 13 containing about 20% by weight of water is readjusted to the final coal concentration of a high coal concentration water slurry 15 in a slurry adjustment tank 3 with an aqueous surfactant solution 26. Note that FIG. 2 shows only the conventional deashing process described above.

The above is the coal high concentration water slurry production process incorporating the conventional deashing process. In the conventional process, pulverized coal 41 having a considerably wide particle size is simultaneously treated in the conditioned tank 4 and sent to the flotation machine 1. However, in condition tank 4, pulverized coal 41 and foaming agent 2
When 4 and the collecting agent 25 are sufficiently stirred and mixed, the fine granulated coal of the pulverized coal 41 and the coarse granulated coal combine to form the foaming agent 24 and the collecting agent 2.
There is a difference in the degree of adhesion between the pulverized coal 41 and the deashing process in the flotation machine 1, which results in a large difference between the pulverized coal and the coarse granulated coal. will decrease. In other words, since the surface area of fine granule coal is larger than that of coarse granule coal, foaming agent 2
This is because the amount of adhesion to coarse coal is large, but the flotation characteristics are poor because the particle size is small, whereas the amount of adhesion to coarse coal is small, but the flotation characteristics are good because the coarse diameter is large. As a result, the recovery rate of the coal (clean coal) 11 having a low overall ash content becomes low compared to the addition rate of the foaming agent 24 and the collecting agent 25. On the contrary, foaming agent 2
4 and the collecting agent 25 improves the recovery rate of coal (clean coal) 11 with a small ash content, but the percentage of residual ash in the clean coal 11 also increases. In other words, the deashing efficiency of the clean coal 11 has decreased, which is a problem.

As a result of intensive research aimed at solving the drawbacks of the above-mentioned conventional methods, the present inventors discovered that the clean coal recovery rate and deashing treatment efficiency can be efficiently maintained even when the coal particle size distribution fluctuates. completed. That is, the purpose of the present invention is to pulverize coal to a particle size suitable for a highly concentrated coal-water slurry, classify this into a certain particle size, and separate coal with a larger particle size and coal with a smaller particle size into a conditioned tank. The coal particles are mixed with a foaming agent and a collecting agent according to each particle size and surface area, and then collided with each other, and then ultrasonic vibrations are applied to the coal of smaller particle size to cause the coal particles to resonate in water, causing the coal particles to collide with each other and coarsen the particles. let me,
After that, it is mixed with classified coal of larger particle size and subjected to flotation deashing treatment, and the clean coal is put into a slurry adjustment tank to make a high concentration coal-water slurry. Highly concentrated coal with high demineralization rate
An object of the present invention is to provide a method for producing a water slurry.

The demineralization method of the present invention will be explained with reference to FIG.

200 mesh pass A slurry of 70 to 95% pulverized coal of 10% is passed through a classifier such as a wet cyclone.
It is classified into particles larger than a mesh and particles smaller than 200 mesh. Coal particles 50 larger than 200 mesh have a coal concentration of about 20% by water 14 obtained by dehydrating coal (clean coal) 11 with a low ash content in the flotation machine 1 to about 20% water by weight in the dehydrator 2. ~30%
The coal particles 50 larger than 200 mesh are sufficiently stirred and supplied to the condition tank 4 together with the foaming agent 24 and the collecting agent 25.
Foaming agent 24 and scavenger 25 corresponding to the surface area of
adhesion and collision.

On the other hand, coal particles 150 of 200 mesh or less are obtained by dehydrating coal (clean coal) 11 with a low ash content in a flotation machine 1 to about 20% water by weight in a dehydrator 2.
4, the coal concentration is adjusted to about 20 to 30% and supplied to the condition tank 104 together with the foaming agent 24 and the collecting agent 25, and the coal particles 150 of 200 mesh or less are sufficiently stirred to increase the surface area of the coal particles 150. The corresponding foaming agent 24 and collecting agent 25 are attached and collided with each other.

Thereafter, the 200
Vibration is applied to coal particles 150 that are smaller than a mesh.
Here, the frequency of the diaphragm 31 is 50 to 1000 kHz, which should be called ultrasonic vibration, and the coal particles 150
The frequency that resonates in water is selected. Since the coal particles 150 adhere to and collide with the collecting agent 25 such as A heavy oil or kerosene, the coal particles 150 aggregate with the collecting agent 25 as a binder and grow into coal particles with a large particle size.

This slurry of coal particles that have grown to a large particle size is
It is mixed with a slurry of 50 coal particles larger than 200 mesh, introduced into a flotation machine 1, and separated into coal with a low ash content (clean coal) 11 and coal with a high ash content (tail) 12. 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 sent to a conditioning tank 4,
It is reused to adjust the concentration of coal particles supplied to 104.

On the other hand, coal with a high ash content (tail) 12 is wastewater 1
It is removed from the system as 15.

The thus obtained cake-like clean coal 13 with a water content of about 20% is mixed with an aqueous surfactant solution 26 in a slurry adjustment tank 3.
The coal-high concentration water slurry 15 is produced by mixing with the coal-rich water slurry 15.

The clean coal yields of clean coal deashed in this way and clean coal obtained by the conventional flotation method were compared under the following operating conditions.

Coal type: Daido coal (particle size 200 mesh pass 80%) Flotation machine: Fahrenwald type Flotation conditions: Conditions Tank residence time 7 minutes Flotation time 7 minutes Collection agent A heavy oil (1 part foaming agent to 1 part collection agent) 4 addition) PH 6-8 Flotation machine coal concentration 10% Ultrasonic irradiation treatment 200 mesh pass granule coal
Irradiation at 200kHz for 1 minute The results obtained are shown in Figure 5. 〓 and □• on the left side of the figure are based on the present invention, and 〓 and □• on the right side are based on the conventional method. Figure 5 shows that according to the method of the present invention, the yield of clean coal is approximately 10% compared to the conventional method.
It can be seen that the present invention has achieved an improvement in the ash content in the clean coal and a reduction in the ash content in clean coal, and is excellent in the coal content recovery rate and the deashing rate.

[Brief explanation of the drawing]

Figure 1 is a flow sheet showing the conventional coal high concentration water slurry manufacturing process, and Figure 2 is an extraction of only the deashing process from Figure 1.
FIG. 3 is a flow sheet of the deashing process according to the present invention, and FIG. 4 shows a comparison of clean coal yield between the present invention and the conventional method.

Claims (1)

[Claims] 1. Pulverize coal to a particle size suitable for highly concentrated coal-water slurry, classify this into a certain particle size, and separate larger particle size coal and smaller particle size coal in conditioned tanks to correspond to each particle size and surface area. The coal particles are then mixed with a foaming agent and a collecting agent and collided with each other, and then ultrasonic vibrations are applied to the smaller-sized coal to cause the coal particles to resonate in water to cause the coal particles to collide with each other and become coarser. It is characterized by high coal recovery rate and high deashing rate, which is characterized by mixing it with coal of large particle size and performing flotation deashing treatment, and then putting the clean coal into a slurry adjustment tank to make a highly concentrated coal-water slurry. Method for producing highly concentrated coal-water slurry.