JPS6232187A - Aqueous slurry of coal - Google Patents

Abstract

PURPOSE:To prepare a low-cost aqueous slurry of coal having a high concn., by mixing crushed coal, dispersant and water in specified proportions and letting fine particles of coal adsorb the dispersant. CONSTITUTION:The slurry is a mixt. of crushed coal, water and dispersant, with coal contained in the mixt. in 55wt% or higher and consisting of particles having a maximum diameter of less than 11mm. The dispersant is contained in 0.01-5.0% of dry weight of coal and a greater portion of it is adsorbed only by fine particles with a diameter corresponding to 20-70% in cumulative weight distribution where the smallest and the largest particle diameters are set at 0% and 100%, respectively. Preferred dispersants are organic anionic or, nonionic surfactant, inorganic ion compd. and mixt. thereof.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention relates to a coal-water slurry, and particularly to a highly concentrated coal-water slurry in which the amount of adsorbent used is reduced by adsorbing a dispersant only to fine particles in the coal. .

(Prior Art) Powder slurry transport technology has long been studied as a method for transporting solid powder as a fluid that is easy to handle. In recent years, the above-mentioned slurry transportation technology has been applied to the transportation of coal, and there has been active development of technology for producing coal-water slurry that is safe and can be transported through pipes without problems such as coal spontaneous combustion or dust scattering. It is being said.

In such a coal-water slurry, by increasing the coal content as much as possible, the efficiency of transporting the coal can be improved, and by reducing the moisture content, the coal-water slurry can be transported without being extracted and dewatered. Since it has become possible to directly burn coal in coal-water slurry, high-concentration technology has been developed to increase the coal concentration in the coal-water slurry. It is a well-known fact that increasing the solids concentration in a slurry increases its viscosity.However, in a coal-water slurry, the viscosity is kept low enough to allow pipe transportation, while the coal concentration is kept as low as possible. The first method is to increase the concentration by adjusting the particle size distribution of the coal particles in the coal-water slurry, and the second is to further add a dispersant to improve the dispersibility of the coal particles. There is a known method of lowering the viscosity by increasing the
.

Many methods for producing coal-water slurry with high concentration and low viscosity have been disclosed in addition to the above-mentioned known methods, but all of them are based on the above two basic principles. The method for producing coal water slurry according to these known examples includes (1) coal, water,
and a method of wet-pulverizing using a tube mill or the like while mixing predetermined amounts of a dispersant to directly produce a highly concentrated coal-water slurry. (2) After pulverizing the coal into several types of particle sizes,
A method of manufacturing by mixing these so that they have a predetermined particle size distribution, adding a predetermined amount of water and a dispersant, and stirring and mixing. There is a method of manufacturing by wet pulverizing with a tube mill or the like, and then dehydrating and concentrating the obtained slurry to make it highly concentrated.

FIG. 10 is an explanatory diagram showing a process for producing coal-water slurry by a conventional method. Tube mill 22 has a diameter of 500
The crane has a length of 1000 ** and is filled with steel balls with a diameter of 60 to 2 Qmm. Coal (coal) with a particle size of around 50 days is introduced from the hopper 15 to the coarse crusher 16, and is
It is crushed to a size of less than m. The thus pulverized coal is fed to the tube mill 22 by the feeder 17 at a rate of 10 kg/hour. At the same time, an aqueous sodium hydroxide solution is supplied from a water tank 18 by a pump 19, and a surfactant is supplied by a pump 21 from a surfactant tank 20 at a rate of 4.31 kg/hr and 0.05-0.2 kg/hr, respectively.

By any of the methods (1), (2), and (3) above, the coal concentration is 70% by weight or more and the viscosity is about 150%.
It is possible to produce a coal water slurry with high fluidity of 0 cP or less.

As mentioned above, the technology for producing highly concentrated and low viscosity coal-water slurry is almost established, but the purpose of using coal is mainly to use it as a cheap fuel in boilers, etc. For this purpose, the power required to crush coal and the amount of dispersant required are enormous, and it cannot be said that coal-water slurry has necessarily been established as the most economical form of coal utilization using conventional technology alone. By the way, the coal crushing power cost required to satisfy the first basic principle varies slightly depending on the type of coal, but is approximately 0.2 yen/1000Kc.
al, and the cost of the dispersant required to satisfy the second basic principle is approximately 0.5 yen/1000Kcal, and the cost of both is 0.7 yen/100OKca/. Since the price of coal is about 2 yen/100 OKcal, the cost increases by about 35% just for the crushing power and dispersant in producing the coal-water slurry. In the known prior art as described above, the amount of dispersant required to produce the target high concentration, low viscosity coal water slurry is, for example, 0.01 to 5.0% by weight based on dry coal. However, the amount of dispersant required to produce a coal-water slurry with a coal concentration of 70% by weight and a viscosity of 1500 cP by a known method varies depending on the type of coal used, but is approximately 0.5 to 1% by weight. If the slurry is reduced below this level, the viscosity will increase dramatically and a fluid slurry cannot be obtained. As described above, the technical problem with charcoal slurry is to reduce the cost required for its production and establish it as an inexpensive fuel, but this problem has remained unsolved in the prior art.

(Problems to be Solved by the Invention) An object of the present invention is to provide a low-cost coal-water slurry that reduces the amount of dispersant necessary for producing the coal-water slurry without impairing its properties of high concentration and low viscosity. It's about doing.

(Means for Solving the Problems) The present inventors have engaged in research on the manufacturing technology of coal-water slurry, and as a result of conducting intensive studies on methods for improving its economic efficiency, the inventors have found that a coal-water slurry having the following characteristics: By doing so, it was discovered that a coal water slurry having the same concentration and viscosity as a conventional coal water slurry could be obtained with a small amount of dispersant added, which could not be achieved with conventional technology, and the present invention was achieved.

The coal-water slurry of the present invention is a mixture consisting of pulverized coal, water, and a dispersant, and the coal in the mixture contains 50%
The dispersant is composed of particles containing 5% by weight or more and having a maximum particle size of 1 crane or less, and the dispersant is 0.0% by weight based on the dry weight of the coal. O1~1
．． 0%, and most of this dispersant has a particle size equal to or less than 20 to 70% in the cumulative weight distribution where the minimum particle size of the coal in the mixture is 0% and the maximum particle size is 100%. It is added and adsorbed only to fine particles.

In the present invention, if the content of the dispersant does not reach 0.01% by weight, the slurry density will increase;
If it exceeds this amount, the amount added will not be different from the conventional amount, and the object of the present invention cannot be achieved.

In addition, the fine particles on which the dispersant is adsorbed are 2 in the cumulative M amount distribution.
If the particle size is larger than the particle size that accounts for 0 to 70%, it is impossible to achieve the low viscosity and cost reduction that are the objectives of the present invention.

As the dispersant used in the present invention, organic anionic surfactants, nonionic surfactants, inorganic ionic compounds, or mixtures thereof are preferably used.

The coal-water slurry of the present invention is prepared by dry-pulverizing coal to a particle size of less than 100 µm, and then dividing the coal into larger particles (1) and smaller particles (2) with a particle size between 150 and 10 μm as the boundary.
Water and a dispersant are added to the small particle size coal (2) obtained in this way, and the mixture is further crushed using a suitable method such as a ball mill to form a coal-water slurry. It is produced by mixing coal particles (1) of particle size in an appropriate ratio so that the coal content is 55% by weight or more.

Hereinafter, the circumstances leading to the present invention and the principle of the present invention will be explained with reference to the drawings.

Figure 2 shows the relationship between the viscosity of a coal-water slurry with a coal concentration of 70% by weight and the amount of dispersant added, which was produced by supplying predetermined amounts of coal, water, and dispersant to a tube mill according to the conventional method shown in Figure 10. shows. Here, the coal particles in the coal water slurry have a maximum particle size of about 300 μm, and the amount passing through 200 meshes is 75% by weight. An organic anionic surfactant is used as a dispersant, and the pH of the coal water slurry is adjusted to 8 to 8.
Sodium hydroxide was added to maintain the temperature at 10.

The viscosity of the coal-water slurry was measured using a commercially available rotating cylindrical viscosity needle, and the viscosity was measured at a shear rate of 183'''1.
The apparent viscosity at a temperature of 20° C. was defined as the viscosity of the coal-water slurry. As is clear from the results in Figure 2, the amount of dispersant added is approximately 0.6% by weight for A coal compared to dry coal.
It can be seen that for coal, the viscosity of coal slurry increases dramatically below about 1% by weight.

The molecular weight of the organic anionic surfactant used as a dispersant is several thousand, and the diameter of one molecule is approximately several tens of angstroms. The outer surface area of the coal particles in the coal-water slurry is approximately 2×10'cI+! /g.・From the above values, the amount of surfactant required to completely coat the outer surface of the coal particles in the coal-water slurry is estimated to be I x 10"g per 1g of dry coal.
That is, it is calculated to be 0.01% by weight based on dry coal. However, as shown in Figure 2, the dispersant required to produce the desired coal-water slurry is about 50% of the above calculated value.
~100 times the amount.

Based on the above basic considerations, the present inventors investigated the reason why it is necessary to add a large amount of dispersant as described above in order to produce the target coal-water slurry.

The present inventors first investigated the adsorption characteristics of a surfactant used as a dispersant to coal particles. By crushing and classifying coal, 37-74.105-297.297-
500. crm of three different particle sizes were prepared, and 20 g of these coals were immersed in 200 cc of an aqueous organic anionic surfactant solution with a concentration of 5 x 10'% by weight, and the temperature was set at 11.3°C. The temperature was maintained at a constant temperature in a thermostatic water bath, and 1 Qcc of the supernatant was sampled at regular intervals to analyze the surfactant concentration. The analysis was carried out using a modified method. Figure 3 shows the change over time in the amount of surfactant adsorbed onto each coal particle, which was determined from these results. Coal particles (a) with a particle size of 37-74 μm and 29'l-500 μm
Although the outer surface area of coal particles per unit weight differs by about 10 times from that of item m (c), the amount of surfactant adsorbed becomes constant regardless of the coal particle size after a certain amount of time. This suggests that surfactant molecules are adsorbed not only on the outer surface of the coal particles but also on the surface of the pores developed inside them. In addition, in the figure, (b)
shows the change over time in the adsorption amount of coal particles with a particle size of 105-297 μm.

By the way, the reason why the viscosity can be lowered by adding a surfactant to the coal water slurry is as follows. In other words, coal is inherently hydrophobic and has a surface property that makes it difficult to wet with water, but when coal with such properties is pulverized and mixed with water, the surface of the coal particles becomes energetically unstable and they tend to coagulate with each other. do. Under such conditions, the fluidity of the coal-water slurry is poor. Increase the fluidity of coal water slurry,
In other words, in order to reduce the viscosity, it is necessary to allow each coal particle in the slurry to move independently and freely, and for this purpose, the surface of the coal particles must be made hydrophilic and easily wetted by water. is necessary. The surfactant has the effect of dispersing the coal particles by adsorbing onto the coal particles and making the surface hydrophilic, thereby achieving a reduction in the viscosity of the coal-water slurry. For the purpose mentioned above, it is sufficient if the surfactant 12 is adsorbed only on the outer surface of the coal particles 10, as shown in FIG. As shown in FIG. 5, it was revealed that the surfactant 12 diffused into the pores 13 developed inside the coal particles 10 and was adsorbed thereon.

The surfactant adsorbed inside the coal particles does not contribute to lowering the viscosity of the coal-water slurry at all, and is wasted.

Furthermore, as shown in Figure 2, in the conventional method, when the amount of surfactant added is less than 1.0% by weight based on dry coal, the viscosity of the slurry increases rapidly. As shown in Fig. 10, in order to crush the coarse particle coal fed by the feeder 3 in the coexistence of a surfactant from the beginning, the large particles in the slurry that do not affect the fluidity of the slurry during the crushing process. This is thought to be because a large amount of surfactant is adsorbed on the surface.

In order to confirm the above, the following experiment was conducted. 1st
The coal-water slurry produced as shown in Figure 0 is classified using a sieve, and large particles with a particle size of 105 μm or more are collected. After washing off the fine particles adhering around the large particles with water, the amount of adsorption of the dispersant onto the large particles was measured in the same manner as described above. However, in this experiment, the amount of adsorption was increased by immersing the large particle size coal in an aqueous solution with a dispersant concentration of 104%. The results are shown in FIG. As is clear from this result, the dispersant was hardly adsorbed on the collected large particles, and it was confirmed that the dispersant was already adsorbed on these large particles during the production process of the coal-water slurry.

Next, we investigated the influence of the particle size distribution of coal particles on the fluidity of coal-water slurry. As is clear from the known examples cited above, the broader the particle size range of coal, that is, the larger the difference between the maximum particle size and the minimum particle size, the lower the viscosity of the coal-water slurry. Figure 6 shows the fI used for this study.
! Fig. 1 shows the particle size distribution of coal in the coal-water slurry prepared by I.

In the figure, (d) is one with a maximum particle size of about 10 μm, (e) is one with a maximum particle size of 35 μm, and (f) is one with a maximum particle size of about 300 μm.

The slurry was prepared by feeding predetermined amounts of coal, water, and dispersant into a ball mill and wet-milling the coal. As a dispersant, an organic anionic surfactant and sodium hydroxide were used at a concentration of 1.0 and 0.0% per dry weight of coal, respectively.
2% was added. The coal concentration of each slurry was adjusted by sequentially adding water to the slurry thus prepared, and its viscosity was measured. The method for measuring viscosity is as described above. For the particle size distribution, the average value of the same sample measured 3 to 4 times under the same conditions was used. FIG. 7 shows the relationship between the viscosity of the prepared slurry and the coal concentration in the slurry.

As can be seen from FIG. 7, it can be seen that the larger the maximum particle size of the coal particles in the coal-water slurry, that is, the wider the particle size range, the lower the viscosity of the slurry at the same coal concentration. However, when comparing the same viscosity, the maximum particle size is 10
It can also be understood that even if the diameter is increased approximately 30 times from μm (d) to 300 μm (f), the coal concentration in the slurry cannot be made that high. For example, viscosity ioo.

Comparing cP, it is about 67% by weight for a maximum particle size of 10 μm (D), and about 72% by weight for a maximum particle size of 300 μm, and even if the maximum particle size is increased about 30 times, coal is The concentration can only be increased by at most 5% by weight. However, as is clear from Figure 6,
Approximately 60% of the coal in the slurry of (to) is 10 to 300μ
It has a particle size of m. From this result, it is clear that large coal particles, such as those of 10 to 300 μm, do not have any significant effect on the fluidity of the slurry, and that the viscosity is determined solely by the fine particles. be.

Furthermore, in order to confirm this, a coal water slurry was prepared in the same manner as above using another type of coal,
Separately produced fine particles of 10 μm or less were added to this slurry, and the effect on the viscosity was investigated. FIG. 8 shows the particle size distribution of coal particles in the slurry. (g) shows the particle size distribution of the coal in the slurry prepared above, and (ch) shows the particle size distribution of the coal in the slurry prepared by adding the fine particles to the slurry. FIG. 9 shows the relationship between the viscosity of these slurries and the coal concentration. As can be seen from FIG. 8, the number of particles of 10 μm or less increased by only a few percent, but the viscosity of the slurry decreased by about 20%, as shown in FIG. 9. The above results also confirmed the importance of the influence of fine particles on the viscosity of coal-water slurry.

To summarize the above basic study results, the fluidity of coal-water slurry is determined by the dispersibility of the fine particles, and the dispersant required to make the coal-water slurry high in concentration and low in viscosity is adsorbed on the outer surface of the fine particles. It can be said that the required amount is sufficient. However, since the surfactant used as a dispersant penetrates into the pores of the coal and is adsorbed, most of the added surfactant is adsorbed within the coal particles and does not contribute to the fluidity of the slurry. Moreover, the larger the particle size that does not significantly affect the fluidity of the slurry, the more surfactant is adsorbed within the particle. In the preparation of coal slurry by the conventional method described above, since a surfactant, which is a dispersant, is applied to all the particles whose particle size has been adjusted, a large amount is adsorbed inside the coal particles as described above, and therefore the amount added is cannot be reduced.

Based on the facts described above, the present inventors have determined that by applying a dispersant only to the microparticles that play an important role in the fluidity of the slurry, the fluidity of the slurry is not impaired (the amount of dispersant added is We have arrived at the present invention which can reduce this.

Hereinafter, the present invention will be explained in more detail with reference to specific examples.

(Example) FIG. 1 is an explanatory diagram showing an example of the coal-water slurry production process according to the present invention. The coal is introduced into a coarse pulverizer 1, where it is pulverized to a maximum particle size of 11 centimeters or less. The pulverized coal is then introduced into classifier 2, where 150~
It is classified into coarse particles larger than 10 μm in diameter and fine particles smaller than this. The fine particles are introduced from the path 3 into the fine grinder 4, where they are further wet-pulverized in the coexistence of water and a dispersant. From the outlet 5 of the pulverizer 4, a coal-water slurry containing pulverized coal that has been mixed with water and a dispersant in the pulverizer flows out continuously, and the slurry is introduced into a mixing tank 6. .

All or part of the coarse particles classified by the classifier 2 are introduced into the mixing tank 6, where they are mixed with the coal-water slurry. Here, the mixing ratio of the coal water slurry and coarse particles is determined so that the coal particles in the final produced coal water slurry have a predetermined particle size distribution, or The coal concentration can be determined to be a predetermined value. When mixing at the ratio determined as above, if the amount of coarse particles is smaller than that produced by classifier 2, the particle size distribution of the coarsely pulverized coal produced by coarse pulverizer 1 is determined to be appropriate. The grinding capacity of the coarse pulverizer can be adjusted so that the pulverizing capacity of the coarse pulverizer is increased, and on the other hand, if there are too many coarse particles, the excess coarse particles can be fed back to the coarse pulverizer 1 through the path 7 to adjust the material balance. In addition, when mixing the coal water slurry and coarse particles to obtain a predetermined particle size distribution in the mixing tank 6, it is necessary to ensure that the coal concentration of the final produced coal water slurry is high (if the slurry does not exhibit fluidity). In such a case, the mixing tank 6 is used so that the slurry exhibits appropriate fluidity.
The concentration of the slurry can also be adjusted by supplying water to the slurry. Further, if a sufficient amount of fine particles cannot be produced by coarse pulverization tj3i1, the coarsely pulverized coal before being classified by classifier 2 can be directly supplied to pulverizer 4 through route 8.

Example 1 FIG. 12 is an explanatory diagram of a coal water slurry manufacturing process showing another example of the present invention. Coal (coal) is supplied from the homper 31 to the coarse pulverizer 32, where it is pulverized to a maximum particle size of approximately 300 μm. A portion of it is fed by a feeder 33 to a mill 34 at a rate of 3 kg/hour. The mill 34 is filled with steel balls having a diameter of 2u, and a stirring rod 35 with a pin is connected to a motor 36.
This type of grinder performs pulverization by rotating it. At the same time, a pump 3 is connected to the mill 34 from a water tank 37.
An aqueous sodium hydroxide solution is supplied by a pump 8 from a surfactant tank 39, and an organic anionic surfactant is supplied by a pump 40 from a surfactant tank 39 at a rate of 1.61 g/hour and 21 g/hour, respectively. In this way, a coal-water slurry was prepared with a maximum particle size of about 35 μm and a particle size distribution as shown in FIG. 13(E).

This slurry is designated as C.

In addition, a portion of the coal crushed by the coarse crusher 32 is
The particles were classified using a mesh sieve 41, and particles larger than 400 mesh were separated, and smaller particles were returned to the feed port of the mill 34 for use. The powdered coal having a particle size larger than 400 mesh that was separated in this way had a particle size distribution as shown in FIG. This powdered coal is designated as D. This pulverized coal passes through a pumper 42 and a feeder 43, and is mixed and adjusted in a mixer 44.

Samples C and D obtained as described above were mixed in an appropriate ratio in a mixer 44, and then diluted with water or evaporated and concentrated to prepare a coal-water slurry with a coal concentration of 70% by weight. was measured. The result is the first
Shown in Figure 4. The horizontal axis in FIG. 14 indicates the mixing ratio of the above-mentioned coals among the coals in the coal-water slurry prepared as above. In Sample C, the surfactant was present in an amount of 0.7% based on the dry weight of the coal, and no surfactant was present in the sample. From the amount of surfactant in both samples and the mixing ratio of coal, it is possible to calculate the concentration of surfactant in the slurry prepared as above, and the amount of surfactant added to the amount of dry coal M in the slurry. is shown on the horizontal axis in FIG.

As is clear from FIG. 14, according to the method of the present invention, even if the amount of surfactant as a dispersant added is only 0.1% based on the weight of dry coal, the coal concentration is 70 M% and the viscosity is 1000%.
It is possible to produce a slurry of cP, and it can be seen that the amount of surfactant added can be about 1/10 to produce a slurry with the same properties as in the case of producing m using the conventional method. As mentioned above, by effectively adsorbing the surfactant, which is a dispersant, only on the fine coal particles in the coal-water slurry, the amount of surfactant added can be reduced without impairing the fluidity of the slurry. This demonstrates the effect of the present invention, which can dramatically reduce the amount of heat generated.

The coal particles in the coal water slurry prepared as described above were classified using a sieve, large particles with a particle size of 105 μm or more were collected, and the adsorption amount of the dispersant on the large particles (E) was measured. The results are shown in FIG. Figure 11 (R) shows the same method using large particles (F) with a particle size of 105 μm or more, which were collected by classifying the particles of 400 mesh or more with a sieve 41 in Figure 12 and further classifying them with a 105 μm sieve. This is the result of measuring the amount of adsorption. The adsorption amount of E is much larger than (W) in Figure 11, and is almost the same as the adsorption amount of F. In the coal-water slurry produced by the method of the present invention, the dispersant has a large diameter. Does not adsorb to particles,
Most of the particles were adsorbed to microparticles, indicating that they were working effectively. In Figure 11, the adsorption amount of E is slightly lower than that of F, which is caused by the mixer (14 in Figure 12).
This is thought to be because a small amount of the dispersant that remained after being adsorbed to the coal particles in C was adsorbed to the powdered coal when mixed with slurry C in ).

In this example, a coal slurry C having a maximum particle size of about 35 μm was produced by wet pulverization in the coexistence of a dispersant and water, and coarse grained coal was mixed therein to prepare a final coal-water slurry. If the particle size distribution of coal particles in the coal-water slurry after mixing coarse particles is, for example, as shown in Fig. 6,
It is clear that the smaller the maximum particle size of the slurry C, the greater the effect of reducing the amount added. However, if the coal particle size in slurry C is made small as shown in Figure 13 (Y), and after mixing with coarse particles, the particle size distribution becomes as shown in Figure 6 (F). In order to achieve this, it is necessary to contain a large amount of small-sized particles even in the coarse particles, as shown in (evening) of FIG. If such a preparation method is used, it is possible to increase the proportion of coarse particles (shown in Figure 13) when creating the same particle size distribution in the final product slurry, so the curve in Figure 14 will shift to the right. will move in parallel,
The effect of reducing the amount added becomes greater. However, dry grinding requires a lot of power to produce fine particles, and the subsequent mixing also requires a lot of power. Conversely, if the maximum particle size of coal particles in slurry C is increased, the particle size distribution as shown in Figure 6 (f) cannot be obtained unless the proportion of slurry C is increased in mixing with coarse particles. , the effect of reducing the amount added becomes smaller. On the other hand, the number of fine particles in the coarse particles produced by dry pulverization can be reduced, and the power required for pulverization and mixing can be reduced.

From the above, it is clear that the maximum particle size of the coal particles in the slurry C has an optimum value determined by the reducing effect of the dispersant, which is the basis of the present invention, and the power required for pulverization. Based on the current coal pulverization technology and the results of this example, the present inventors have come to the opinion that the optimal maximum diameter of coal particles in slurry C is about 10 to 70 μm. However, this value can vary depending on the maximum diameter of coal particles in the coal-water slurry after mixing, the pulverization method, and the required power.

Example 2 A coal water slurry was continuously manufactured using the apparatus shown in FIG. In Mill 34, slurry A was produced under the same conditions as in Example 1. However, the supply amount of surfactant is 7
It was kept constant at 0g. Powdered coal B classified by the sieve 41 is once stored in a hottuber 42, and then sent through a feeder 43 to
It was fed at a rate of 6.7 kg to the mixer 44, where it was mixed with slurry A to produce a coal water slurry. The coal-water slurry thus obtained has a coal concentration of 7.
0% by weight, and the amount of surfactant added is 0.0% by weight based on the weight of dry coal.
It contains 15%. The viscosity of this slurry was measured and was approximately 900 cP, confirming that by using the manufacturing method of the present invention, the amount of surfactant added can be significantly reduced without deteriorating the properties of the coal-water slurry. did it.

As is clear from the above examples, it was found that by applying the method according to the present invention, the amount of dispersant added in the production of coal water slurry could be significantly reduced. In the above embodiment, two types of coal powder pulverized into different particle size distributions and a slurry were mixed, but in the present invention, of course, two or more types of coal powder and slurry may be mixed. Exactly the same effect as in the above embodiment can be obtained.

(Effects of the Invention) According to the present invention, the amount of dispersant added necessary for producing a highly concentrated and low viscosity coal water slurry can be reduced to, for example, 1/2 of the conventional amount without deteriorating the properties of the coal slurry.
It has the effect of reducing the amount by 2 to 1/10.

[Brief explanation of drawings]

Figure 1 is a diagram showing a schematic diagram of the coal slurry production process according to the present invention, Figure 2 is a diagram showing the effect of the amount of dispersant added on the viscosity of slurry prepared by the conventional method, and Figure 3 is a diagram showing the effect of the amount of dispersant added on the coal particles. Figures 4 and 5 are schematic diagrams showing the state of adsorption of surfactant into coal particles and their pores, and Figure 6 is a diagram showing the changes in the amount of surfactant adsorbed over time. Diagram showing the particle size distribution of coal in coal water slurry,
Figure 7 is a diagram showing the relationship between coal concentration and viscosity of coal-water slurry, Figure 8 is a diagram showing the particle size distribution of coal in the coal-water slurry used in the experiment, and Figure 9 is a diagram showing the relationship between coal concentration and coal-water slurry. FIG. 10 is a flow diagram of a coal-water slurry manufacturing apparatus showing an example of the present invention. FIG. 11 is a diagram showing the amount of dispersant adsorbed onto coal particles. 13 is a diagram showing a flow diagram of a coal-water slurry production apparatus showing another embodiment of the present invention, FIG. 13 is a diagram showing the particle size distribution of pulverized coal prepared in an embodiment of the present invention, and FIG.
The figure is a diagram showing the results of an example of the present invention. 1... Coarse crusher, 2... Classifier, 3... Fine particle path, 4... Fine crusher, 5... Fine crusher outlet, 6...
・Mixing tank, 7... Feedback path, 8...
Feed path, IO... Coal particle, 12... Dispersant molecule, 13... Pore, 31... Hopper, 32...
・Coarse crusher, 33... feeder, 34... mill,
35... Stirring rod, 36... Motor, 37... Water tank, 38... Pump, 39... Dispersant tank,
40... Pump, 41... Sieve, 42... Hopper, 43... Feeder, 44... Mixer. Agent Takeshi Kawakita Figure 2 Figure 3 Time (n) Figure 6 Figure 7 Coal concentration (wt'/a) Figure 8 Figure 9 Elapsed time (h) Figure 13 Figure 14 Dispersion Amount of agent (wt'10) D mixing side stand (wt'10)

Claims (2)

[Claims] (1) A mixture consisting of pulverized coal, water, and a dispersant, wherein the mixture contains 55% by weight or more of coal and is composed of particles with a maximum particle size of 1 mm or less, and the dispersant is used to dry the coal. Contains 0.01 to 5.0% by weight,
Moreover, most of this dispersant is added and adsorbed only to fine particles whose particle size corresponds to 20 to 70% in the cumulative weight distribution, where the minimum particle size of coal in the mixture is 0% and the maximum particle size is 100%. Coal-water slurry. (2) The coal water slurry according to claim 1, wherein the dispersant is an organic anionic surfactant, a nonionic surfactant, an inorganic ionic compound, or a mixture thereof.