JPS585394A - Submerged granulation of pulverized coal - Google Patents

Abstract

PURPOSE:To increase the yield of granulated coal in the submerged granulation of pulverized coal, by separating the pulverized coal and granulated coal of a particle size below a desired value by the flotation of a screened slurry consisting of the pulverized coal and a binder, and circulating them to a submerged granulation process. CONSTITUTION:A pulverized coal slurry and a binder are introduced to a submerged granulator 1, granulated by agitation and overflowed in the form of a slurry via an outlet of the granulator 1. The overflowed slurry is supplied to an arc screen 2 and a vibrating screen 3, and the granulated coal of a desired particle size is separated on the screen and a slurry contg. ungranulated pulverized coal and granulated coal of particle size < the desired value is separated through the screen. The granulated coal on the screen is transferred to a storage bin by a conveyor 4. The screened slurry is supplied to a flotation means 5, in which the ungranulated pulverized coal and the granulated coal of particle size below the desird value in the slurry are separated in the presence of a foaming agent by flotation, and they are discharged as froth from the flotation means 5 and recycled to the entrance of the granulator 1. Mud in the screened slurry is discharged from the bottom of the flotation means 5 to a thickener 6 and discarded after concentrated therein.

Description

[Detailed Description of the Invention] A method for underwater granulation of pulverized coal, in which pulverized coal is granulated by stirring in water in the presence of a Nono Inder, and the resulting slurry is sieved to recover granulated coal with a desired particle size. It is said that it is preferable to use as little amount of I9 binder (usually heavy oil or other viscous oil is used) as possible in the This is because if the amount is too large, drainage of the granulated coal becomes extremely difficult when dividing the slurry. Of course, if the amount of binder is too small, only a commensurate amount of pulverized coal will be granulated, and the yield of granulated coal will decrease. Ideally, the amount of binder should be adjusted to just the right amount, taking into account the conditions. However, it is extremely difficult in practice to adjust the amount of binder to just the right amount, so in actual operations, the amount of binder is slightly insufficient and the slurry from the granulation process is sieved to produce the target particle size. The conventional underwater granulation method collects the granulated coal and discards the slurry under the sieve. However, it cannot escape the disadvantage of escaping into the sieve slurry.

The present invention proposes a method for increasing the yield of granulated coal by incorporating a flotation step into the conventional underwater granulation method, thereby granulating coal particles that escape into the slurry under the sieve in the conventional method. , the method of the present invention includes the steps of granulating pulverized coal underwater in the presence of a saunder, and briefly applying the slurry from this underwater granulation step to collect granulated coal of the desired particle size on a sieve. In the underwater granulation method of pulverized coal, the above-mentioned part is obtained by subjecting the under-sieve slurry obtained in the process to flotation treatment to separate the pulverized coal contained in this slurry and granulated coal with a particle size below the desired particle size. The invention is characterized in that the coal particles are recycled to the underwater granulation process described above. In the illustrated example, the underwater granulator f1 is made up of three stirring tanks connected in series, each equipped with a stirring blade. The slurry is granulated by stirring in the presence of the granulator 1, and overflows from the outlet of the granulator 1 in the form of a slurry. This oat safe flow has a desired mesh size (e.g. sieve mesh 0.5).
m) is supplied to an arcuate sieve 2 and a linear sieve 3, where granulated coal with a desired particle size (for example, 0.5 m or more) is placed on the sieve with ungranulated pulverized coal and pulverized coal with a particle size smaller than the desired particle size. The slurry containing granulated coal is separated under the sieve. Then, the granulated coal on the sieve is transported to the storage place by the conveyor 4. On the other hand, the slurry under the sieve obtained from the arc @ 2 and the vibrating sieve 3 is supplied as it is to the thickener 6 according to the conventional method-ζ. Solid-liquid separation is performed, and the solid content is discarded.According to the present invention, the above-mentioned under-sieve slurry is supplied to the flotation machine 5.In the flotation machine 5, the under-sieve slurry is separated in the presence of a foaming agent. The ungranulated pulverized coal and the granulated coal with a particle size smaller than the desired size are flotated, and these are taken out from the flotation machine 5 as froth and circulated to the inlet of the underwater granulation device 1 as shown in Figure 1. be. The mud in the undersieve slurry is discharged from the bottom of the flotation machine 5 to the thickener 6, where it is concentrated and then discarded. As is clear from the above explanation, according to the method of the present invention, Since pulverized coal and granulated coal having a particle size smaller than the desired particle size can be repeatedly subjected to the granulation process, the desired granule can be produced without increasing the amount of A-ing, or in other words, without sacrificing the drainage properties of the granulated coal. can increase the yield of granulated coal in diameter, and therefore can also significantly reduce the ax of pulverized coal.

[Brief explanation of the drawing]

The drawing is a full diagram adopted in one embodiment of the present invention.

Claims (1)

[Claims] 1. An underwater granulation method for pulverized coal that includes the steps of granulating pulverized coal underwater in the presence of a binder, and simply applying slurry from this underwater granulation step to recover granulated coal of a desired particle size. In the above-mentioned sieving process, the under-sieve slurry obtained in the process is subjected to flotation treatment to separate the pulverized coal contained in this slurry and the granulated coal having a particle size below the desired particle size, and these are then subjected to the above-mentioned underwater granulation process. Underwater granulation method for pulverized coal characterized by circulation in the granulation process O