JPH0469675B2 - - Google Patents

Description

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

Coal high concentration water slurry (hereinafter referred to as high concentration slurry) is a mixture of 60 to 90% by weight of finely ground coal and water.
It is a mixture of 40 to 10% by weight and a small amount of additives, and is a fluid fuel that can be burned as is in a boiler, etc. without dehydration.It is a fluid fuel that can be used by converting coal, which is a solid fuel, into a fluid. This will dramatically expand the

Conventionally, methods for producing high-concentration slurry can be broadly classified into three types: dry method, high-concentration wet method, and low-concentration wet method.

The dry method uses a mill to pulverize coal in the air, and then mixes and stirs it with water and additives (hereinafter referred to as mixing and stirring) to form a highly concentrated slurry.

In the high-concentration wet method, coal, water and additives are simultaneously charged into a tube mill, and pulverization and mixing and stirring are performed at the same time.

Furthermore, in the low-concentration wet method, coal and mill supply water are put into a tube mill and pulverized at a low concentration, resulting in a low-concentration coal water slurry (hereinafter referred to as (described as low concentration slurry)
This is then dehydrated in a dehydrator to form a dehydrated cake, which is again mixed and stirred with a small amount of adjusted water and additives in a mixer to form a highly concentrated slurry.

What is illustrated in FIG. 1 is a flow sheet relating to a conventional method for manufacturing a low concentration wet high concentration slurry.

In Figure 1, a is a coal supply storage tank, b
is a coal supply line, c is a tank for mill supply water, d is a mill supply water supply line, e is a wet mill, f is a transport line for the low concentration slurry obtained in the wet mill e, and g is a dehydrator. The dehydrator G is used to remove low concentration slurry. h is a line for draining the dehydrated water obtained by dehydration in dehydrator g, i is a transport line for the slurry obtained by dehydration in dehydrator g (hereinafter referred to as dehydrated cake), j is a mixing agitator,
k is a tank for adjusting water that supplies adjusted water to mixing agitator j via adjusting water supply line 1; m is a tank for additives that supplies additives to mixing agitator j via additive supply line n; , o is a transport line for the high concentration slurry product, and p is a storage tank for the high concentration slurry product or combustion means of a boiler (hereinafter referred to as product slurry tank).

In such a flow sheet, the storage tank a
Coal and mill feed water are supplied from tank c to wet mill e through lines b and d, and are pulverized to a low concentration to form a low concentration slurry. This low concentration slurry is supplied to the dehydrator g via line f. In the dehydrator g, the low concentration slurry is dehydrated, the dehydrated water is drained from the line h, and the dehydrated cake is supplied to the mixing and stirring period j through the line i.
This mixer j mixes and stirs the supplied dehydrated cake with the conditioning water and additives supplied from tanks k and m via lines 1 and n to form a highly concentrated slurry with low viscosity. The product is supplied from the high concentration slurry line o to the product slurry tank p.

In such a conventional low-concentration wet method for producing high-concentration slurry, coal is pulverized in water at a low concentration, so that only a small amount of ultrafine coal particles are produced.

Therefore, since the resulting highly concentrated slurry contains only a small amount of ultrafine coal particles, the rheological properties of the highly concentrated slurry become dilatant, resulting in poor storage stability.

Therefore, the inventors conducted an experiment on a method for producing a high concentration slurry using a low concentration wet method, and as a result, the following was found.

That is, the dehydrated water (hereinafter referred to as filtrate) discharged from the dehydrator g through line b contains a considerable amount (sometimes containing several percent) of colloidal ultrafine coal particles. It has been found that when this filtrate is added to a high concentration slurry, the resulting high concentration slurry becomes extremely stable, that is, the filtrate greatly contributes to improving the stability of the high concentration slurry.

The present invention was provided based on the above-mentioned knowledge for the purpose of solving the drawbacks of the conventional low-concentration wet high-concentration slurry manufacturing method.

That is, in the present invention, coal is wet-roughly pulverized in water using a coarse pulverizing mill to prepare a low-concentration coal slurry, and then the low-concentration slurry is dehydrated and separated into a dehydrated cake and a filtrate. The coal particles in the dehydrated cake are ground by the finishing mill, and the dehydrated cake is mixed and stirred with the supplied adjustment water and additives, and the filtrate is passed through the finishing mill. This is a method for producing a highly concentrated slurry, which is characterized in that the slurry is circulated through the production process such as mixing and stirring.

Hereinafter, preferred embodiments of the first aspect of the present invention will be described in detail with reference to the embodiments illustrated in FIGS. 2 to 8.

The embodiment illustrated in FIG.
It is a flow sheet of an example.

In Fig. 2, 1 is a coal supply storage tank, 2 is a coal supply line, 3 is a tank for supplying water to the coarse crushing wet mill, 4 is a supply line for supplying water to the coarse crushing wet mill, and 5 is a coarse crushing wet mill (hereinafter referred to as a coarse grinding mill), 6 is a transport line for the low concentration slurry obtained by the coarse grinding mill 5, 7 is a dehydrator, and the dehydrator 7 dehydrates the low concentration slurry to form a dehydrated cake. be. 8 is a drainage line for the filtrate obtained from the dehydrator 7, 9 is a pump for transporting the filtrate, 10 is a circulating filtrate tank connected to the line 11 for storing the filtrate and feeding the circulating filtrate, and 12 is the water in the circulating filtrate tank 10. This is a line that replenishes water when there is a shortage. 13 is a transportation line for the dehydrated cake obtained by dewatering in the dehydrator 7, 14 is a finishing mill, and 15 is a storage for water supplied to adjust the moisture concentration of the slurry of the finishing mill 14 (hereinafter referred to as adjustment water). The tank 15 is connected to the circulating filtrate water supply line 11. 16 is a supply line for conditioning water; 17 is a tank (hereinafter referred to as an additive tank) for storing additives such as surfactants (hereinafter referred to as additives) to be supplied to the finishing mill 14;
8 is an additive supply line, 19 is a finishing mill 14
20 is a transportation line for high-quality aged high-concentration slurry (hereinafter referred to as product high-concentration slurry) that is mixed and stirred and supplied as a product or to the next process; 20 is a storage line for storing the product high-concentration slurry to be supplied as a product or to the next process; This is a tank (hereinafter referred to as a tank for product high concentration slurry).

Note that the line 19 may be connected to a boiler combustion means or the like (not shown), but the explanation regarding this will be omitted since it is the same below.

In such an embodiment illustrated in FIG.
The coal in the storage tank 1 and the coarse grinding mill supply water in the tank 3 are supplied to the coarse grinding mill 5 through lines 2 and 4, and are ground at a low concentration to form a low concentration slurry of 20 to 60% by weight of coal. This low concentration slurry is supplied to a dehydrator 7 through a line 6, and the filtrate produced by dehydration is discharged through a line 8 and stored in a tank 10 by a pump 9. The filtrate containing colloidal coal particles stored in the tank 10 is sent as a circulating filtrate to the tank 15 via the line 11,
In addition, finishing mill 1 is supplied from line 16 as conditioning water.
Supply to 4. The dewatered cake, on the other hand, is fed via line 13 to finishing mill 14 . Finishing mill 14
Then, the coal grains in the dehydrated cake are ground, the corners of the angular coal grains are removed, and the coal grains are made into a rounder shape, and the coal grains are further refined. and finishing mill 14
In this case, the coal grains are ground to give them a round taste, and the adjusted water is supplied through a line 16 from a tank 15 to adjust the water concentration, which also contains colloidal coal grains. Then, the additives supplied from the tank 17 through the line 18 are mixed and stirred together. The high-concentration product slurry prepared by grinding, mixing, and stirring in the finishing mill 14 is transported from a line 19 to a tank 20 for high-concentration product slurry and stored therein.

As described above in detail based on the flow sheet of FIG. 2 showing the first embodiment of the present invention, the present invention provides the following effects.

(1) In a wet mill, grinding is performed at a low concentration (20 to 60% by weight of coal) where the grinding power is minimal, so it is possible to operate at the point where the grinding power is minimal.

(2) After the coal is coarsely ground in a coarse grinding mill, it is further ground in a finishing mill, giving the coal particles a rounded appearance. Therefore, the additives are well dispersed,
As a result, coal particles are filled with fine coal particles and ultrafine coal particles, and a homogeneous high concentration slurry with high coal concentration and low viscosity can be obtained.

(3) After coarsely pulverizing coal in a coarse pulverizing mill, it is further ground and atomized in a finishing mill, resulting in a highly concentrated slurry that contains a large amount of fine and ultra-fine coal particles, resulting in poor rheological properties. becomes pseudoplastic and improves storage stability.

(4) In addition, a stirring liquid containing colloidal ultrafine coal particles is supplied to the finishing mill as conditioning water and mixed and stirred, so that rheologin properties become even more pseudoplastic and a highly concentrated slurry with extremely good storage stability is obtained. I can do it.

(5) Since the coal is coarsely ground in a coarse grinding mill and then dehydrated, the dewatering performance of the dehydrator is significantly improved, and the water content in the dehydrated cake is reduced, making it possible to reduce the water content of the subsequent high-concentration slurry. I can hold it down. In addition, you can choose from a wide range of moisture adjustment concentrations.

Further, in the flow sheet of the embodiment illustrated in FIG. 2, as shown by the broken line, the return line 11a of the circulating filtrate is connected to the tank 3 for coarse grinding mill supply water and the tank 10 for circulating filtrate. The colloidal coal particles in the filtrate may be supplied to the coarse grinding mill 5 to enhance the pseudoplasticity of the highly concentrated product slurry and improve its storage stability. 2, lines 11 and 11
Either one of these may be used for a, or a combination thereof may be used.

Furthermore, in the flow sheet of the embodiment illustrated in FIG. 2, as shown by the dashed line, a direct feed line 21 for the circulating filtrate is provided which is directly connected from the circulating filtrate water feed line 11 to the regulated water supply line 16 for use in the regulated water. It is also possible to reduce costs by omitting the tank 15. Further, by providing a direct feed line 21a for the circulating filtrate directly connected to the supply line 4 for the coarse grinding mill feed water from the circulation filtrate return line 11a, it is possible to reduce costs by omitting the coarse grinding mill feed water tank 3. In the embodiment illustrated in FIG. 2, lines 21 and 21a
Either of them may be used, or a combination thereof may be used.

Furthermore, in the flow sheet of the embodiment illustrated in FIG. 2, as shown by the two-dot chain line, a direct filtrate feed line 22 is connected directly from the filtrate transport pump to the circulating filtrate water supply line 11 and the circulating filtrate return line 11a. and 22a can be provided to reduce costs by omitting the circulating filtrate tank 10. In the embodiment shown in FIG. 2, any of the lines 21, 21a, 22, and 22a may be used, or any combination thereof may be used.

Note that lines 11, 11a, 21, 2 indicated by broken lines, dashed-dotted lines, and dashed-double-dotted lines in the flow sheets of the embodiment illustrated in FIGS. 3 to 7
1a, 22, 22a are the lines 11, 11a, 21, 11, 11a, 22a shown by broken lines, dashed-dotted lines, and dashed-two dotted lines in the flow sheet of the embodiment shown in FIG.
Since the structure, operation, effect, etc. are almost the same as those of 21a, 22, and 22a, description thereof will be omitted in the following embodiments.

The embodiment illustrated in FIG. 3 is a flow sheet of a second embodiment of the present invention.

In the embodiment illustrated in FIG. 3, the symbols 1 to 20 and 11a, 21a, 22a are the symbols 1 to 20 and 11 in the embodiment illustrated in FIG.
Since they are equivalent to a, 21a, and 22a, their explanation will be omitted. And 23 or 23a is a lump crusher or a torque equalization type lump crusher, and this lump crusher 23
Alternatively, in step 23a, the plate-like or lump-like dehydrated cake supplied via the line 13 is crushed into small lumps or minute lumps. 24 is a line for transporting the dehydrated cake in the form of small lumps or micro lumps (hereinafter referred to as the dehydrated cake in the form of small lumps).

The feature of the second embodiment compared to the first embodiment is that the dehydrated cake supplied from the line 13 is supplied to the crushing device 23 or the torque equalization type crushing device 23a before being led to the finishing mill 14 to form a plate-like or lumpy cake. The dehydrated cake is crushed into small or fine pieces and then fed to the finishing mill 14 via a line 24.

Therefore, in addition to the effects obtained in the first embodiment, the second embodiment provides the following effects.

(1) The finishing mill 14 is used to crush and supply the dehydrated cake to the finishing mill 14 into small pieces.
The uniform mixing and stirring of the adjustment water and additives for adjusting the slurry that is supplied to the slurry goes smoothly, making it possible to obtain a high-quality, uniform product with high concentration slurry.

(2) Furthermore, since homogeneous mixing can be achieved smoothly, the amount of product high-concentration slurry produced per unit time can be significantly increased, and therefore productivity can be improved.

(3) In the case of the torque-equalizing crusher 23a, the torque applied to the motor becomes even, preventing the motor from overheating, and the crushing work can be carried out smoothly with a small-capacity motor. Since the agglomeration operation is performed very smoothly in this way, a large amount of high-concentration product slurry can be produced smoothly.

The embodiment illustrated in FIG.
It is a flow sheet of an example.

In the embodiment shown in FIG.
2a denotes those with the same numerals 1 to 20 in the embodiment shown in FIG. 2, and 11a, 21.
Since it is equivalent to a and 22a, the explanation will be omitted.
13a is a transport line for the dehydrated cake from which coarse particles have been removed (hereinafter referred to as coarse cut dehydrated cake); 25 is a line for separating coarse particles in the low concentration slurry supplied from line 6; a classifier for classifying into concentrated slurry (hereinafter referred to as coarse particle-containing low concentration slurry) and low concentration slurry from which coarse particles have been removed (hereinafter referred to as coarse particle cut low concentration slurry); 26;
The coarse particles classified by the classifier 25 are crushed by the coarse grinding mill 14.
27 is a return circulation line for the coarse grain-containing low concentration slurry to be wet-pulverized again at This is a transportation line for concentrated slurry.

The characteristics of the third embodiment compared to the first embodiment are as follows.

That is, the low-concentration slurry from the coarse grinding mill 5 is supplied to the classifier 25 through the line 6 and is classified into a low-concentration slurry containing coarse particles and a low-concentration slurry containing coarse particles. Line 2 is the low concentration slurry containing coarse particles.
6 and returned to the coarse grinding mill 5 by a pump 27, and the contained coarse particles are further sent to the coarse grinding mill 5.
re-grind into fine or ultra-fine coal. On the other hand, the coarse cut low concentration slurry obtained by the classifier 25 is supplied to the dehydrator 7 through a line 28. Dehydrator 7
The coarse cut thin slurry is then dewatered, the dewatered water being drained through line 8, while the coarse cut dewatered cake is fed to finishing mill 14 via line 13a.

Therefore, in the third embodiment, the following effects can be obtained in addition to the effects obtained in the first embodiment.

(1) The low-concentration slurry containing coarse particles is crushed again in the coarse mill 5.
Since the high concentration slurry is pulverized by pulverization, the number of coarse particles in the high concentration slurry is very small and the number of fine coal particles is increased, so that the rheological properties of the high concentration slurry become pseudoplastic and the storage stability is improved.

(2) Since the low-concentration slurry containing coarse particles is classified by the classifier and crushed again by the coarse grinding mill 5, the maximum diameter of the coarse particles in the high-concentration slurry can be arbitrarily selected. Therefore, it becomes easy to obtain a highly concentrated slurry with a desired particle size distribution.

(3) Since the low concentration slurry containing coarse particles is classified by the classifier 25 and then crushed again by the coarse grinding mill 5, the amount of coarse particles in the high concentration slurry becomes extremely small. Therefore, when the coal is combusted in a combustion heat means such as a boiler, the amount of unburned coal is extremely reduced, there is almost no residue in the boiler, and the thermal sintering efficiency is improved.

The embodiment illustrated in FIG.
It is a flow sheet of an example.

In the embodiment shown in FIG.
21a, 22a, 23a are those with the same numbers from 1 to 28 in the embodiments shown in FIGS. 2 to 4, and 11a, 13a, 21a, 22.
Since it is equivalent to a and 23a, the explanation will be omitted.
Note that 24a is a transportation line for the small-sized coarse cut dehydrated cake.

The characteristics of the fourth embodiment compared to the first to third embodiments are as follows.

That is, before the dehydrated cake supplied from the line 13a is led to the finishing mill 14, it is supplied to the agglomeration device 23 or the torque equalization type agglomeration device 23a, and the coarse cut dehydrated cake in the form of plates or lumps is turned into small or micro-agglomerates. After being crushed, it is fed to the finishing mill 14 via line 24a.

Therefore, in the fourth embodiment, in addition to the effects obtained in the first to third embodiments, the following effects can be obtained.

(1) Classify before dehydration, and send the coarse grain-containing low concentration slurry to the coarse grinding mill 14 and crush it again, dehydrate only the low concentration slurry from which the coarse grains have been cut, and further dehydrate it into plate-like or The coarse cut dehydrated cake in the form of a lump is crushed into small pieces by the crushing device 23 or the torque equalization type crushing device 23a, and then the finishing mill 1
In addition, a filtrate containing colloidal particles is supplied to the finishing mill 14 and mixed and stirred together with additives, so the synergistic effect of these makes it possible to obtain a highly concentrated slurry of extremely high quality product. .

The embodiment illustrated in FIG.
It is a flow sheet of an example.

In the embodiment shown in FIG. 6, those with the same numbers 1 to 27,
Since 21a and 22a are equivalent to those having the same reference numerals 1 to 27 and 11a, 13a, 21a, and 22a in the embodiment shown in FIGS. 2 to 5, their explanation will be omitted.

26a is a return circulation line for the diluted low concentration slurry containing coarse grains, and 28a is a transport line 29 for the coarse grain cut diluted low concentration slurry.The low concentration slurry supplied via line 6 has a concentration that is easy to classify with dilution water. Dilution tank for diluting up to 30
3 is a dilution water tank, 31 is a dilution water supply line that supplies dilution water to the dilution water tank 30, and 32 is a coal 15-40 diluted in the dilution tank 30.
This line transports a low-concentration slurry (hereinafter referred to as diluted low-concentration slurry) containing 60 to 85% water by weight.

The characteristics of the fifth embodiment compared to the first and third embodiments are as follows.

That is, before introducing the low concentration slurry from the coarse grinding mill 5 to the classifier 25 via the line 6, the low concentration slurry is introduced to the dilution tank 29 via the line 6, and from the dilution tank 29 to the tank 30.
diluted with dilution water supplied through line 31 to a concentration that is easy to classify. i.e. coal 15-40
% by weight to make a low concentration slurry. This diluted low concentration slurry is supplied to the classifier 25 through a line 32 and is classified into a coarse grain-containing diluted low concentration slurry and a coarse grain cut diluted low concentration slurry. The diluted, low concentration slurry containing coarse particles is returned to the coarse grinding mill 5 via line 26a, and the contained coarse particles are further ground into fine coal or long fine coal in the coarse grinding mill 5. On the other hand, the coarse cut diluted low concentration slurry obtained by the classifier 25 is supplied to the dehydrator 7 from the line 28a. The dehydrator 7 dewaters the coarse cut diluted low concentration slurry and the filtrate is drained through line 8, while the coarse cut dewatered cake is supplied to the finishing mill 14 conditioning tank via line 13a.

Therefore, in addition to the effects obtained in the first and third embodiments, the fifth embodiment provides the following effects.

(1) 20 to 60% by weight of coal before classification with classifier 25
Dilute low concentration slurry of coal 15-40% by weight
Since the diluted slurry is made into a thin diluted low concentration slurry, the classification efficiency in the classifier 25 is improved and mass production of product high concentration slurry is possible.

In addition, in the flow sheet of the embodiment illustrated in FIG. The colloidal coal particles may be supplied to the coarse powder mill 5 to enhance the pseudoplasticity of the product high concentration slurry and improve storage stability. In the embodiment illustrated in FIG. 6, lines 11, 11a and 11b
may be used, or any combination thereof may be used.

Furthermore, in the flow sheet of the embodiment illustrated in FIG. 6, as shown by a dashed line, a dilution water supply line 31
It is also possible to reduce costs by omitting the dilution water tank 30 by providing a direct feed line 21b for circulating filtrate that is directly connected to the dilution water tank 30.

Furthermore, in the flow sheet of the embodiment illustrated in FIG.
A direct filtrate feed line 22b that is directly connected to the circulation filtrate tank 1 is provided together with the lines 22 and 22a.
It is also possible to reduce costs by omitting 0.

In the embodiment shown in FIG. 6, lines 21, 21a, 21b, 22, 22a, 22
For b, any one of them or any combination thereof may be used.

Note that lines 11b, 21b, and 22b indicated by a dashed-dotted line, a dashed-two dotted line, and a dashed-three dotted line in the flow sheet of the embodiment illustrated in FIG.
is composed of lines 11b, 21b, and 22b shown by a dashed-dotted line, a dashed-two dotted line, and a dashed-three dotted line in the flow sheet of the embodiment illustrated in FIG.
Since the functions, effects, etc. are almost the same, the explanation of the embodiment shown in FIG. 7 will be omitted.

The embodiment illustrated in FIG. 7 is a flow sheet of the sixth embodiment of the present invention.

In the embodiment shown in FIG.
13a, 21a, 21b, 22a, 22b, 23
a, 24a, 26a are those with the same reference numerals 1 to 32, 11a, 11b, 21a, 21b,
Since they are equivalent to 22a, 22b, 23a, 24a, and 26a, their explanation will be omitted.

The characteristics of the sixth embodiment compared to the first to fifth embodiments are as follows.

That is, it is supplied to the dehydrator 7. The dehydrator 7 dewaters the coarse cut diluted low concentration slurry, and the filtrate is discharged through line 8, while the coarse cut dehydrated cake is supplied to the crusher 23 or the torque equalization type crusher 23a via line 13a. do. This agglomeration device 23 or torque-equalized agglomeration device 23a crushes the fed plate-like or lump-like coarse cut dehydrated cake into small or minute agglomerates. This small-sized coarse cut dehydrated cake is fed to the finishing mill 14 via line 24a.

Therefore, in the sixth embodiment, in addition to the above-mentioned effects obtained in the first to fifth embodiments, the following effects can be obtained.

(1) Before classification, it is diluted to make it easier to classify, and the coarse particles are cut by classification, and the diluted low-concentration slurry containing coarse particles is returned to the coarse grinding mill and ground again, and the coarse particles are cut out. To dehydrate only the low-concentration slurry, and further crush the dehydrated plate-shaped or lump-like coarse cut dehydrated cake into small chunks using the crushing device 23 or the torque equalization type crushing device 23a and supplying the same to the finishing mill 14. In addition, the finishing mill 14 is supplied with a filtrate containing colloidal particles, and the additives are constantly mixed and stirred together in the maturing machine, so the synergistic effect of these makes it possible to obtain a highly concentrated slurry of extremely high quality product. I can do it.

[Brief explanation of the drawing]

Figure 1 is a flow sheet related to the conventional low concentration wet high concentration slurry manufacturing method, and Figures 2 to 7
The figure is a flow sheet of an embodiment according to the present invention, and FIGS. 2, 3, 4, 5, 6, and 7 are flow sheets for the first embodiment, second embodiment, and third embodiment. FIG. 3 is a flow sheet of the example, the fourth example, the fifth example, and the sixth example. 1...Coal supply storage tank, 2...Coal supply line, 3...Coarse grinding mill supply water tank, 4...
Coarse grinding mill supply water supply line, 5... Coarse grinding mill, 6... Low concentration slurry transport line, 7...
Dehydrator, 8... Filtrate drainage line, 9... Pump for filtrate transportation, 10... Tank for circulating filtrate, 11
...Water supply line for circulating filtrate, 11a, 11b...
Circulating filtrate return line, 12... Replenishment water replenishment line, 13... Dehydrated cake transport line, 13a
... Transportation line for coarse cut dehydrated cake, 14...
...Finishing mill, 15... Tank for adjustment water, 16...
...Adjusted water supply line, 17... Additive tank, 18... Additive supply line, 19... Product high concentration slurry transportation line, 20... Product high concentration slurry storage tank, 21, 21a, 21b
... Circulating filtrate direct feed line, 22, 22a, 22
b... Filtrate direct water line, 23... Clumping device, 2
3a...Torque uniform type agglomeration device, 24...Transportation line for small block dehydrated cake, 24a...Transportation line for small block coarse cut dehydrated cake, 25...Classifier, 26...Low concentration slurry containing coarse particles 26a...Return circulation line for coarse grain-containing diluted low concentration slurry, 27...Slurry return pump, 28...Transportation line for coarse cut low concentration slurry, 28a...Coarse cut diluted low concentration slurry Concentrated slurry transport line, 29... Dilution tank, 30...
Dilution water tank, 31... dilution water supply line,
32...Transportation line for diluted low concentration slurry.

Claims (1)

[Claims] 1 Coal is wet coarsely pulverized in water using a coarse pulverizing mill to prepare a coal low concentration water slurry, then the above mentioned coal low concentration water slurry is dehydrated and separated into a dehydrated cake and dehydrated water, and the above dehydrated cake is finished. The coal particles in the dehydrated cake are ground by the finishing mill, and the dehydrated cake is mixed and stirred with the supplied conditioning water and additives, and the dehydrated water is passed through the finishing mill. A method for producing a highly concentrated coal water slurry, which is characterized in that the slurry is circulated during production processes such as mixing and stirring.