JPS6323992A - Production of highly concentrated coal/water slurry by wet process - Google Patents

Abstract

PURPOSE:To obtain a highly conc. coal/water slurry which contains few coarse particles and has excellent combustibility, transportability, storability, etc., by crushing coal together with water and a dispersant in a ball mill in specified two steps by a wet process. CONSTITUTION:Coal 2, water 3 and a dispersant 4 are fed to a first ball mill and crushed by a wet process into a powder having such a particle size distribution that 70-80% thereof is composed of fine particles having a particle size of not larger than 74mum, thus preparing a highly conc. coal/water slurry 5. The slurry 5 is fed to a vibrating sieve, where it is classified by a wet process. The resulting coarse particle slurry 7 is returned to the first ball mill 1 and the fine particle slurry 8 is introduced into a tank 11, where it is stored while it is stirred with a stirring rod 10. The fine particle slurry 8' is fed to a second ball mill 13 and crushed by a wet process into a powder having such a particle size distribution that 80-85% thereof is composed of fine particles having a particle size of not large than 74mu, thus preparing a highly conc. coal/water slurry 14. The slurry 14 is fed to a vibrating sieve 15 and classified by a wet process to obtain a highly conc. coal/water slurry 17 which hardly contains coarse particles.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a wet method for producing a highly concentrated coal/water slurry, and particularly relates to an improvement in the method for preparing a highly concentrated slurry.

[Prior art] Highly concentrated coal/water slurry (hereinafter referred to as "highly concentrated CWMJ") is a mixture of finely pulverized coal of 60 i% or more and water of 40% by weight or less and some additives. It is a directly combustible fuel, and its particle size distribution satisfies its combustibility, transportability and storage properties.

It has homogeneous slurry properties such as concentration and viscosity, and 1
It is required that the content of coarse particles of 501JIn or more be 1 to 2% or less.

The high concentration preparation method (high concentration pulverization method) in the conventional wet production method of high concentration CWM involves feeding crushed coal to a particle size of 3 # or less and 95% by weight or more together with water and a dispersant to a ball mill and wet pulverizing it. , a method in which a high concentration CWM with a coal concentration of 60% by weight or more is prepared from the beginning, coarse particles are removed from this high concentration CWM by wet classification, and a stabilizer is added as necessary. However, according to the above-mentioned conventional high-concentration preparation method, the high-concentration CW that becomes the product may be affected by variations in the properties of the coal supplied to the ball mill, such as moisture, or the amounts of coal and dispersant.
There is a problem that the slurry properties of M become non-uniform, and this tendency is remarkable in the initial stage after starting the ball mill.

In addition, the highly concentrated CWM discharged from the ball mill contains coarse particles that are generated when the coal is short-bathed without being subjected to sufficient pulverizing action, and the removal of coarse particles by wet classification is difficult because it has a relatively high viscosity ( (approximately 1000 cp), and there is a problem that the high concentration CWM that becomes the product contains more than 1 to 2% of coarse particles.

Therefore, the present invention provides a wet manufacturing method for high-concentration CWM that can homogenize the slurry properties and reduce the content of coarse particles to 1 to 2% or less, and has excellent combustibility, transportability, storability, and manufacturability. This is what we are trying to provide.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention, when producing high concentration CWM@ by a high concentration preparation method, wet-pulverizes coal together with water and a dispersant in a first ball mill. After preparing a highly concentrated CWM with a fineness of 70% to 80% below stage 74, this highly concentrated CWM is wet classified to separate into a coarse slurry and a fine slurry, and the coarse slurry is returned to the first ball mill. On the other hand, the fine grain slurry was stored in a tank for a required period of time while being stirred, and the stirred fine grain slurry was wet-pulverized by a second ball mill to produce 74 IJ. nJ'l, lower 80-85%
This is a method for preparing high-concentration CWM with a fineness of 100%.

[Function] According to the above means, the fine slurry is stored in the tank for the required time while being stirred, so that the second ball mill has a concentration of 2.
A fine slurry with uniform particle size is supplied. In addition, wet classification is performed in a relatively low viscosity state with a fineness of 70 to 80% below stage 74, and wet pulverization is performed with a sufficiently long residence time from the first ball mill to the second ball mill. Particle white pass is reduced.

[Example] Hereinafter, one embodiment of the present invention will be described based on the drawings.

In the figure, 1 is a first ball mill, and coal 2 with a particle size of 3 mm or less and 95% by weight or more is supplied together with water 3 and a dispersant 4 to the first ball mill 1, and the coal is wet-pulverized at a coal concentration of 60% by weight or more to a stage of 74 or less. High concentration CW with fineness of 70-80%
Prepare M5.

Here, as the dispersant 4, anionic, cationic,
Nonionic surfactants and the like may be used alone or in appropriate combinations, and are appropriately selected depending on the type of coal. As anionic surfactants, fatty oil sulfate ester salts, higher alcohol sulfate ester salts, etc. are used, as cationic surfactants, alkylamine salts, etc. are used, and as nonionic surfactants, polyoxyalkyl ester salts are used. Ether etc. are used.

Next, the above-mentioned high concentration CWM5 is made with a mesh size of 0.8 to 1.5#.
Coarse particle slurry 7 with a coal concentration of 60% by weight or more and containing many coarse particles of 150 μm or more, which is wet classified using a vibrating sieve 6 of
and a fine grain slurry 8 having a coal concentration of 60% by weight or more and containing a slight amount of coarse particles. The coarse slurry 7 is returned to the first ball mill 1 via the pump 9 and wet-pulverized again, while the fine slurry 8 is stored in a tank 11 for a required period of time while being stirred by an agitator 10. The capacity of the tank 11 is
It is large enough to store the production amount of ball mill 1 for about 40 to 60 minutes.

Then, the fine grain slurry 8' stored while being stirred in the tank 11 is supplied to the second ball mill 13 via the pump 12 and wet-pulverized again, so that the coal Q degree is 60% by weight or more and the grade is 74 or less. High concentration CWM with 80% fineness
Prepare 14. However, this highly concentrated CWM 14 is wet-classified using a vibrating sieve 15 with a mesh size of about 0.5 to 0.8#, and is made into a fine grain slurry 16 with a coal concentration of 60% by weight or more, which contains a small amount of coarse particles of 1501JII or more. , and a fine slurry 17 containing almost no coarse particles (1 to 2% or less) with a coal concentration of 1% or more.The fine slurry 16 is returned to the second ball mill 13 via a pump 18'. Then, the fine slurry 17 is fed through a tank 18 and a pump 19 to a mixer 20 such as a line mixer, where it is mixed with a stabilizer 21 to improve the rheological properties necessary to satisfy storage stability, etc. Stabilized high concentration CW with
It becomes M22 and is transferred to a storage tank (not shown) or the like.

Here, the capacity of the tank 18 is large enough to quantitatively draw out the coarse slurry 17 classified by the vibrating IJ 15 with the pump 19, and the stabilizer 21 is made of carboxymethyl cellulose (CMC). ), polysaccharides,
Bentonite etc. are used.

In the manufacturing method of the above embodiment, the fine slurry 8 is stored in the tank 11 for the required time while being stirred, so that the slurry properties such as the concentration and particle size of the fine slurry 8' supplied to the second ball mill 13 are uniform. This results in homogenization of the slurry properties of the stabilized high-concentration CWM22 that becomes the product.

In addition, wet classification using a vibrating sieve 6 with a mesh opening of 0.8 to 1.5M is performed at a relatively low viscosity with a fineness of 70 to 80% below 74, and wet pulverization is carried out using a vibrating sieve 6 with an opening of 0.8 to 1.5M. Since this is carried out with a sufficiently long residence time of 200 to 3000, the short pass of coarse particles is reduced, and as a result, the coarse particle content in the stabilized high concentration GWM 22 that becomes the product becomes 1 to 2% or less.

[Effects of the Invention] As described above, according to the present invention, fine grain slurry with homogeneous slurry properties is supplied to the second ball mill, so that the slurry properties of high-concentration CWM that become a product can be improved compared to conventional manufacturing methods. Homogenization can be achieved, and the removal of coarse particles by wet classification is carried out at a relatively low viscosity, and the wet grinding is carried out with a sufficiently long residence time (11), so short passes of coarse particles are reduced; The content of coarse particles in high-concentration CWM as a product can be reduced to 1 to 2% or less, and as a result, the high-concentration CWM as a product has excellent combustibility, transportability, storability, and manufacturability. be able to.

[Brief explanation of the drawing]

The figure is a process explanatory diagram of a wet manufacturing method for high concentration CWM showing one embodiment of the present invention. 1...First ball mill 2...Coal 3...Water
4... Dispersant 5... High concentration CWM
6... Vibrating sieve 7... Coarse grain slurry 8.8'... Fine grain slurry

Claims (1)

[Claims] When producing a highly concentrated coal/water slurry by the high concentration preparation method, coal was wet-pulverized with water and a dispersant in a first ball mill to prepare a highly concentrated coal/water slurry with a fineness of 70 to 80% of 74 μm or less. After that, this highly concentrated coal
The water slurry is separated into coarse slurry and fine slurry by wet classification, and the coarse slurry is returned to the first ball mill, while the fine slurry is stored in a tank for the required time while stirring, and the fine slurry is A wet method for producing a highly concentrated coal/water slurry, which comprises wet-pulverizing the slurry in a second ball mill to prepare a highly concentrated coal/water slurry having a fineness of 80 to 85% of 74 μm or less.