JPH0259197B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for producing coal-water slurry,
In particular, it relates to a method of obtaining a slurry with a low ash content.

In recent years, fuel conversion from oil to coal has been rapidly progressing in thermal power plants, etc., but one of the problems when using coal is its high ash content. On the other hand, attempts have been made to turn coal, a solid fuel, into a fluid to make it easier to handle and reduce transportation costs. ) is of increasing interest.

To produce a highly concentrated coal-water slurry, it is necessary to adjust the particle size distribution and minimize the interparticle gaps, and to achieve this, it is necessary to have a wide particle size distribution. This cannot be achieved by pulverization, and it is necessary to add a certain amount of coarse particles. On the other hand, in order to increase the deashing rate of coal,
It is essential to separate the coal and ash components into independent particles (single separation), and in order to obtain a deashing rate of several tens of percent or more, the coal must be pulverized to about -200 mesh. . However, there is a problem in that when the maximum particle size is finely pulverized to about 200 mesh, it is no longer possible to prepare a highly concentrated slurry.

The purpose of the present invention is to solve the above-mentioned problems in coal deashing technology, and to have a high deashing rate and a wide particle size distribution.
An object of the present invention is to provide a method for producing a highly concentrated coal-water slurry.

The present invention mixes refined coal obtained by performing a deashing operation on the fine particles among the coarse particles and fine particles obtained by crushing one or more types of coal with the coarse particles. After that, it is made into a slurry. More typically, in producing a highly concentrated coal-water slurry, the present invention divides raw material coal into a coarse particle group and a fine particle group, and performs a deashing operation on the fine particle group. By mixing refined coal with coarse particles and then slurrying it, a high-quality, highly concentrated coal-water slurry with a low ash content is prepared.

The basic principle of the present invention is to divide the raw material for CWM production into a coarse particle group and a fine particle group, perform a deashing operation on the fine particle group, and then mix the two to produce CWM. As a result, it is possible to perform the deashing operation on the fine particle portion, which generally has a high ash content, and at the same time, it is possible to exclude in advance from the target of deashing the coarse coal that cannot float in the flotation method.

On the other hand, for the production of highly concentrated slurry, a wide particle size distribution is required, and for this purpose a mixture containing coarse particles must be fed to a pulverizer. If coal is subjected to a complete deashing operation without being classified, the coarse coal will usually be mixed into the high ash content residual coal, and the subsequent high-concentration slurry must be targeted only at fine particles. A highly concentrated slurry can no longer be obtained. Therefore, in order to obtain a highly concentrated slurry with a wide particle size distribution, dividing the coarse particle portion, which generally has a low ash content, before the deashing operation and mixing it after the fine particle group has been deashed is effective. is important.

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

Figures 1A to 1E show the abundance ratio and ash content of particles of 32 mesh or less after pulverizing various types of coal. In Figure 1, A is Talon coal, B is Taiheiyo coal, C is Miike coal, D is Wanbo coal, and E is the crushed product of D's Wanbo coal. From the results shown in Figure 1, it can be seen that although there are some differences depending on the type of coal, in general, the finer the particle group, the higher the ash content. Therefore, even if the pulverized material is divided and only the fine particle portion is subjected to deashing, and the coarse coal portion is directly sent to CWM production, the resulting CWM
It can be seen that the quality (ash content) of the coal does not decrease as much as estimated from the ratio of coal that is not subjected to deashing, that is, coarse coal.

Next, FIG. 2 shows an example of the present invention.
This is a flow sheet of a water slurry manufacturing method. The raw coal is supplied from a pipe 1 to a crusher 2, and after being crushed, it is classified into a coarse particle group and a fine particle group through a pipe 3 and a classifier 4, and is stored in tanks 7 and 8, respectively. The fine particles are supplied from the tank 7 through the pipe line 5 to the deashing device 9, where they are deashed. As the deashing method, in addition to the flotation method, heavy liquid separation, magnetic separation, electrostatic deashing, etc. can be adopted. The refined coal taken out from the pipe 10 exits the tank 12 and is dehydrated in a dehydrator 14 if necessary, and then mixed with coarse particles taken out from the tank 8 through the pipe 6 in a slurrying device 15. , into high quality coal slurry 17. In addition,
The residual coal separated by the deashing device 9 is stored in a tank 13 via a pipe 11.

The crushing method of the crusher 2 may be either wet or dry, but when deashing is carried out by a wet method such as flotation, it is desirable that the crushing is also carried out by a wet method.

The classification point of the classifier 4 for dividing coal particles into a coarse particle group and a fine particle group is preferably within the range of about 32 to 200 meshes. If the particle size corresponding to the classification point is made too large, coarse particles are also subjected to deashing, and especially in the flotation deashing method, coarse particles do not float, resulting in a decrease in deashing efficiency. On the other hand, if the classification points of the coarse particle group and the fine particle group are lowered too much, the proportion of coal to be subjected to the deashing operation will decrease.

In the present invention, the maximum particle size of the coarse coal must be large enough to enable production of a highly concentrated slurry in the subsequent stage. In other words, when combined with refined coal,
It must be possible to obtain a predetermined particle size distribution by re-grinding or the like. The maximum particle size of such coarse particles is preferably about 6 to 48 mesh. If the maximum particle size of the coarse particles is small, the particle size distribution of the CWM obtained by re-grinding will be narrow and a highly concentrated coal slurry will not be obtained. In addition, if the maximum particles are large, the separation of coal and ash is incomplete, and the proportion of coal that is deashed by flotation etc. decreases, making it difficult to obtain high-quality deashed CWM. Become.

In the present invention, in order to obtain a highly concentrated slurry, the coarse particle group and the purified fine particle group are separately pulverized to a predetermined particle size distribution and then mixed, or both particle groups are mixed and then the refined particle group has a predetermined particle size distribution. A method of crushing is used. In addition to the method of preparing the coarse particle group 8 and the fine particle group 7 from the same type of coal, it is also possible to adopt a method of preparing two types of particle groups using multiple types of coal. In particular, the method of using coal with a high ash content to prepare the fine particle group and coal with a low ash content to prepare the coarse particle group can provide high quality deashing because all of the high ash content can be subjected to the deashing operation. Ash CWM is an excellent way to obtain.

Next, the present invention will be explained based on specific examples.

Example 1 Miike coal with an ash content of 10.5% and pulverized to 100 mesh or less was deashed by a flotation method using kerosene as a collection agent to obtain refined coal with an ash content of 7.0%.
50 parts by weight of this refined coal (dry basis), 20 parts by weight of Miike raw coal (ash content 8.5%) of 16 to 100 mesh, water
30 parts by weight of anionic surfactant (Mignol)
82) When ball milled with the addition of 0.7 parts by weight, a slurry with a viscosity of 1500 cp was obtained. The ash content of the slurry was 7.4% (dry basis).

Example 2 Akahira sludge coal (pulverized coal recovered from coal preparation wastewater, particle size <200 mesh) with an ash content of 58% was deashed in the same manner as in Example 1 to obtain refined coal with an ash content of 15%. 50 parts by weight of this sludge refined coal, Akahira coal with a particle size of 16 mesh or less (ash content 7.0%), 20 parts by weight of water
When a mixture consisting of 30 parts by weight and 0.7 parts by weight of surfactant was ground in a ball mill, a slurry with a viscosity of 1200 cp was obtained. The ash content of the slurry is 12.7%
(dry standard).

As described above, according to the present invention, after separating coal into a coarse particle group and a fine particle group and subjecting the latter to deashing treatment,
By mixing and slurrying, demineralization can be performed more efficiently than deashing the entire product.
In addition, since coarse particles are made into a slurry without going through a deashing operation, the particle size distribution does not become narrower due to re-grinding, etc., and it is possible to obtain a coal slurry with an extremely wide particle size distribution. It becomes possible to increase the concentration and quality of

[Brief explanation of drawings]

Figures 1A, B, C, D, and E are diagrams showing the relationship between the abundance ratio of various pulverized coals by particle size and ash content, and Figure 2 is a diagram showing the relationship between the coal-water ratio and the ash content, which shows an example of the present invention. It is a figure showing a flow sheet of a manufacturing method of slurry. 1...Coal supply pipe, 2...Crusher, 4...Classifier, 7
...Fine particle group tank, 8...Coarse particle group tank, 9
... Deashing device, 12 ... Refined coal tank, 13 ... Remaining coal tank, 14 ... Dehydrator, 15 ... Slurrying device, 1
7...High quality (high concentration) coal slurry tank.

Claims (1)

[Claims] 1. After mixing refined coal obtained by performing a deashing operation on the fine particle group with the coarse particle group, among the coarse particle group and fine particle group obtained by crushing one or more types of coal, A method for producing a coal-water slurry, characterized by forming it into a slurry.