JP2014065823A - Production method of ashless coal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of ashless coal in which ashless coal with an ash content satisfactorily removed can be produced with high efficiency and at low cost even when the ashless coal is produced, for example, at a place of production of coal where there is no margin to variously select a coal kind of a raw material (coal).SOLUTION: A production method of ashless coal includes: an extract process in which slurry obtained by mixing coal and solvent is heated to extract a coal component soluble in a solvent; a separation process in which the slurry obtained by the extract process is separated to a solution containing the coal component soluble to the solvent and a solid content concentration fluid in which a coal component insoluble to the solvent is concentrated; and an ashless coal acquisition process in which the solvent is separated by evaporation from the solution separated in the separation process to obtain ashless coal. The production method of ashless coal further includes a fineness adjustment process in which fineness adjustment of coal is performed by, for example, comminution before mixing the coal and the solvent, so that cohesiveness of the coal component insoluble to the solvent is improved by the fineness adjustment process.

Description

  The present invention relates to a method for producing ashless coal for obtaining ashless coal from which ash is removed from coal.

  As a method for producing ashless coal, for example, there is one described in Patent Document 1. The method for producing ashless coal described in Patent Document 1 is prepared by mixing coal and a solvent to prepare a slurry, heating the resulting slurry to extract a coal component soluble in the solvent, and extracting the coal component. The slurry is separated into a solution part containing a coal component soluble in the solvent and a non-solution part containing a coal component insoluble in the solvent, and then the solvent is separated from the separated solution part to remove ashless coal. It is to get. The method for producing ashless coal described in Patent Document 1 uses, as a raw material for ashless coal, coal obtained by mixing caking coal with general coal when adopting the gravity sedimentation method for separating the solution portion and the non-solution portion. It is characterized by that.

  According to the production method described in Patent Document 1, the sedimentation rate of the solvent-insoluble component is improved when the gravity sedimentation method is performed, and as a result, ashless coal from which ash is sufficiently removed is produced with high efficiency and at low cost. be able to.

JP 2009-227718 A

  As described above, in Patent Document 1, the sedimentation rate of the solvent-insoluble component is improved by using coal obtained by mixing caking coal with general coal as a raw material. However, for example, when producing ashless coal in the coal production area, there is no room for selecting various types of raw material (coal). That is, when manufacturing ashless coal, as described in Patent Document 1, it may be difficult to mix caking coal with steam coal.

  The present invention has been made in view of the above circumstances, and the purpose thereof is, for example, a case where ashless coal is produced in a coal production area where there is no room for selecting various types of raw material (coal). Another object of the present invention is to provide a method for producing ashless coal, which can produce ashless coal from which ash is sufficiently removed at high efficiency and at low cost.

  The present invention includes an extraction step for extracting a coal component soluble in a solvent by heating a slurry obtained by mixing coal and a solvent, and a slurry obtained in the extraction step with a coal component soluble in a solvent. A separation step of separating the solution into a solid content concentrate in which a coal component insoluble in the solvent is concentrated, and obtaining ashless coal by evaporating and separating the solvent from the solution separated in the separation step And a process for producing ashless coal. The method for producing ashless coal further includes a particle size adjusting step for adjusting the particle size of the coal before mixing the coal and the solvent, and improves the cohesiveness of the coal component insoluble in the solvent by the particle size adjusting step. It is characterized by that.

  By improving the cohesiveness of the coal component insoluble in the solvent by the particle size adjusting step, the separation efficiency of the coal component in the separation step is improved. As a result, ashless coal from which ash has been sufficiently removed can be produced with high efficiency. In this manufacturing method, the use of the caking coal described in Patent Document 1 is unnecessary. That is, according to the present invention, for example, even when ashless coal is produced in a coal production area where there is no room for various types of raw material (coal), ashless coal from which ash is sufficiently removed can be obtained. It can be manufactured with high efficiency and at low cost. Note that the caking coal described in Patent Document 1 is more expensive than steam coal. In the present invention, it is not necessary to use such expensive caking coal. Also from this viewpoint, according to the present invention, ashless coal from which ash is sufficiently removed can be produced at low cost.

It is a block diagram which shows the ashless coal manufacturing equipment for demonstrating the manufacturing method of the ashless coal which concerns on one Embodiment of this invention. It is a figure for demonstrating the outline | summary of the verification experiment that the sedimentation (separation property, sedimentation speed) of the coal component insoluble in a solvent improves with the manufacturing method which concerns on this invention. It is a graph which shows the particle size distribution after the grinding | pulverization of the coal which is a raw material. It is a graph which shows the result of sedimentation property (separability, sedimentation speed) verification experiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the ashless coal production facility 100 includes a coal hopper 1, a solvent tank 2, a slurry preparation tank 3, a transfer pump 4, a preheater 5, in order from the upstream side of the ashless coal (HPC) production process. An extraction tank 6, a gravity settling tank 7, a filter unit 8, and solvent separators 9 and 10 are provided.

  Here, the manufacturing method of the ashless coal of this embodiment has a particle size adjustment process, an extraction process, a separation process, an ashless coal acquisition process, and a byproduct coal acquisition process. Hereinafter, each step will be described. In addition, there is no restriction | limiting in particular in the coal used as a raw material in this manufacturing method, Bituminous coal with a high extraction rate (ratio of the soluble component of the coal extracted to a solvent) may be used, and cheaper inferior quality coal (sublimation). (Bituminous coal, brown coal) may be used. The ashless coal means ash content of 5% by weight or less, preferably 3% by weight or less.

(Granularity adjustment process)
Before performing the slurry preparation process mentioned later which mixes coal and a solvent which are raw materials, the particle size of coal is first adjusted (particle size adjustment process). This improves the cohesiveness of coal components that are insoluble in the solvent (solvent-insoluble components such as ash).

  Adjustment of the particle size of coal adjusts the particle size (particle size) by grind | pulverizing coal, for example. A coal pulverizer (not shown) for particle size adjustment may be installed between the coal hopper 1 and the slurry preparation tank 3 or may be installed upstream of the coal hopper 1. In addition, since coal should just be grind | pulverized before mixing coal and a solvent, the installation position of a grinder is not limited to an above-described position.

Here, it is preferable to adjust (for example, pulverize) the particle size of the coal so that the coal particles having a particle size of 3 mm or less are 90% by weight or more.
More preferably, the coal particle size is adjusted so that coal particles having a particle size of 1 mm or less are 90% by weight or more and the maximum particle size is 3 mm or less.
More preferably, the maximum particle size is 1 mm or less, most preferably 0.5 mm or less, that is, the particle size of all coal particles is 1 mm or less, most preferably 0.5 mm or less. It is good to adjust the grain size of coal.

  When verifying the particle size such as whether the particle size of the coal particles is 3 mm or less or whether the particle size is 1 mm or less, for example, the particle size is verified by a screening test specified in JIS A 1102 I do.

  Generally, the fineness (smallness) of the particle size becomes higher as the particle cohesiveness. When the cohesion is high, the sedimentation property of the particles in the liquid is improved, that is, the sedimentation rate is increased. This is because the particles strongly aggregate to form a lump and the diameter increases. On the other hand, the sedimentation rate of particles is considered to be larger when the particle size is coarser (larger). From these, in the case of halfway fine particles (small), the cohesiveness is low, and the sedimentation rate may be lower than particles with coarser (larger) particle sizes.

  Therefore, coal may be pulverized (particle size adjustment) so that the particle size is as small as possible, that is, the maximum particle size is small and the average particle size is small, but this increases the cost required for pulverization. End up. From the above, coal is pulverized so that the particle size is smaller (smaller) than the particle size in which the cohesiveness is reduced (the sedimentation rate is significantly reduced). Thus, as described above, for example, coal is pulverized so that coal particles having a particle size of 3 mm or less are 90% by weight or more. The verification result of sedimentation property (sedimentation velocity) will be described later.

  The adjustment of the coal particle size is not limited to pulverization. For example, the coal particle size may be adjusted using a sieve without crushing the coal. In this case, only coal having a predetermined particle size range is used, that is, only a part of the coal is used. Therefore, the particle size adjustment by pulverization that can use all coal is superior to the particle size adjustment by sieving.

(Extraction process)
An extraction process is a process of extracting the coal component soluble in a solvent by heating the slurry obtained by mixing coal and a solvent. This extraction step includes, for example, a slurry preparation step of preparing a slurry by mixing coal having a particle size adjusted by pulverization and a solvent, and a slurry component that is soluble in the solvent by heating the slurry obtained in the slurry preparation step. It is divided into the extraction main process (solvent soluble component extraction process) to extract.

<Slurry preparation process>
The slurry preparation step is a step of preparing a slurry by mixing coal and a solvent. This slurry preparation process is implemented in the slurry preparation tank 3 in FIG. Coal as a raw material is charged into the slurry preparation tank 3 from the coal hopper 1, and a solvent is charged into the slurry preparation tank 3 from the solvent tank 2. The coal and solvent charged into the slurry preparation tank 3 are mixed by the stirrer 3a to become a slurry composed of coal and solvent.

  The mixing ratio of coal with respect to the solvent is, for example, 10 to 50% by weight on the basis of dry coal, and more preferably 20 to 35% by weight.

<Extraction main process>
This extraction step is a step of heating the slurry obtained in the slurry preparation step to extract a coal component soluble in the solvent (dissolve in the solvent). This extraction main process is implemented in the preheater 5 and the extraction tank 6 in FIG. The slurry prepared in the slurry preparation tank 3 is supplied to the preheater 5 by the transfer pump 4 and heated to a predetermined temperature, then supplied to the extraction tank 6, and held at the predetermined temperature while being stirred by the stirrer 6a. Extraction is performed.

  Coal in the slurry is agglomerated by colliding with each other in the extraction tank 6. Since the number of solids in the extraction tank 6 increases as the particle size of the coal (raw material) decreases, the chance of collision in the extraction main process increases. That is, the smaller the coal (raw material) particle size, the higher the cohesiveness.

  When extracting coal components that are soluble in the solvent by heating the slurry obtained by mixing coal and solvent, a solvent with a large dissolving power for coal, often an aromatic solvent (hydrogen donating property) Or a non-hydrogen-donating solvent) and coal are mixed and heated to extract organic components in the coal.

  The non-hydrogen donating solvent is a coal derivative which is a solvent mainly composed of a bicyclic aromatic and purified mainly from a coal carbonization product. This non-hydrogen donating solvent is stable even in a heated state and has an excellent affinity for coal. Therefore, when this non-hydrogen donating solvent is used, the extraction rate is increased. The non-hydrogen donating solvent is a solvent that can be easily recovered by a method such as distillation. Main components of the non-hydrogen donating solvent include bicyclic aromatic naphthalene, methyl naphthalene, dimethyl naphthalene, trimethyl naphthalene and the like, and other non-hydrogen donating solvent components have aliphatic side chains. Naphthalenes, anthracenes, fluorenes, and these include biphenyl and alkylbenzenes having long aliphatic side chains.

  In the above description, the case where a non-hydrogen-donating compound is used as a solvent has been described, but it is needless to say that a hydrogen-donating compound (including coal liquefied oil) typified by tetralin may be used as a solvent. . When a hydrogen donating solvent is used, the yield of ashless coal is improved.

  Further, the boiling point of the solvent is not particularly limited. From the viewpoint of pressure reduction in the extraction main step and separation step, extraction rate in the extraction main step, solvent recovery rate in the ashless coal acquisition step, etc., for example, a boiling point of 180 to 300 ° C., particularly 240 to 280 ° C. A solvent is preferably used.

  The heating temperature of the slurry in this extraction step is not particularly limited as long as the solvent-soluble component can be dissolved, and is, for example, 300 to 420 ° C. from the viewpoint of sufficient dissolution of the solvent-soluble component and improvement of the extraction rate. More preferably, it is 360-400 degreeC.

  Also, the heating time (extraction time) is not particularly limited, but is, for example, 10 to 60 minutes from the viewpoint of sufficient dissolution and improvement of the extraction rate. The heating time is the total heating time in the preheater 5 and the extraction tank 6 in FIG.

  This extraction step is performed in the presence of an inert gas such as nitrogen. The pressure in the extraction tank 6 is preferably 1.0 to 2.0 MPa, although it depends on the temperature at the time of extraction and the vapor pressure of the solvent used. When the pressure in the extraction tank 6 is lower than the vapor pressure of the solvent, the solvent volatilizes and is not confined in the liquid phase, so that extraction cannot be performed. In order to confine the solvent in the liquid phase, a pressure higher than the vapor pressure of the solvent is required. On the other hand, if the pressure is too high, the cost of the equipment and the operating cost increase, which is not economical.

  As in this embodiment, after mixing coal and solvent, the obtained slurry is not heated to extract coal components soluble in the solvent, but only the solvent is heated first and heated. Alternatively, coal may be supplied into a solvent at a high temperature (for example, 380 ° C.) (supplied in a dry state), the coal may be mixed and heated, and solvent-soluble components in the coal may be extracted with the solvent.

(Separation process)
In the separation step, the slurry obtained in the extraction step is subjected to, for example, a gravity sedimentation method, a solution containing a coal component soluble in a solvent, and a solid concentrate (solvent insoluble component concentrate) in which a coal component insoluble in a solvent is concentrated. ). This separation step is performed in the gravity settling tank 7 in FIG. The slurry obtained in the extraction step is separated into a supernatant liquid as a solution and a solid content concentrated liquid by gravity in the gravity settling tank 7. The supernatant liquid in the upper part of the gravity sedimentation tank 7 is sent to the solvent separator 9 through the filter unit 8 as necessary. The solid concentration liquid settled in the lower part of the gravity settling tank 7 is sent to the solvent separator 10.

  The gravitational sedimentation method is a method in which a slurry is retained in a tank to settle and separate solvent-insoluble components using gravity. A solvent-insoluble component (for example, ash) having a specific gravity greater than that of a solution containing a coal component that is soluble in the solvent is settled by gravity in the lower part of the gravity settling tank 7. A continuous separation process is possible by continuously discharging the supernatant from the top and the solid concentrate from the bottom while continuously supplying the slurry into the tank.

  Further, since the slurry is allowed to stand in the gravity settling tank 7, the aggregation state of the solvent-insoluble component is easily maintained as it is after the extraction main process. This is because in the stationary state, almost no force is applied to solve the aggregation state. Thus, according to the gravity sedimentation method, the separation efficiency in the separation process of the coal component insoluble in the solvent is further improved. In addition, leaving still means that it does not perform anything such as agitation and is left as it is.

  The gravity sedimentation tank 7 is preferably kept warm (or heated) or pressurized in order to prevent reprecipitation of solvent-soluble components eluted from coal. The heat retention (heating) temperature is, for example, 300 to 380 ° C., and the tank internal pressure is, for example, 1.0 to 3.0 MPa.

  As a method of separating the slurry obtained in the extraction step into a solution containing a coal component soluble in a solvent and a solid concentrate concentrated with a coal component insoluble in the solvent, filtration is performed in addition to the gravity sedimentation method. Method and centrifugation.

(Ashless coal acquisition process)
The ashless coal acquisition step is a step of obtaining ashless coal (HPC) by evaporating and separating the solvent from the solution (supernatant liquid) separated in the separation step. This ashless charcoal acquisition process is performed by the solvent separator 9 in FIG. The solution separated in the gravity settling tank 7 is filtered by the filter unit 8 and then supplied to the solvent separator 9, and the solvent is evaporated and separated from the supernatant in the solvent separator 9.

  As a method for separating the solvent from the solution (supernatant liquid), a general distillation method, evaporation method or the like can be used. The solvent separated by the solvent separator 9 can be returned to the solvent tank 2 and circulated for repeated use. By separating the solvent from the supernatant, ashless charcoal (HPC) substantially free of ash can be obtained. Ashless coal contains almost no ash, has no moisture, and exhibits a higher calorific value than raw coal. Furthermore, the softening and melting property, which is a particularly important quality as a raw material for coke for iron making, has been greatly improved, and the obtained ashless coal (HPC) has good softening and melting properties even if the raw material coal does not have softening and melting properties. Have Therefore, ashless coal can be used, for example, as a blended coal for coke raw materials. In addition, ashless coal containing almost no ash content has high combustion efficiency and can reduce the generation of coal ash. Therefore, the use of ashless coal as a gas turbine direct injection fuel in a high-efficiency combined power generation system based on gas turbine combustion has attracted attention.

(By-product coal acquisition process)
The byproduct charcoal acquisition step is a step of obtaining byproduct charcoal by evaporating and separating the solvent from the solid concentrate separated in the separation step. This byproduct charcoal acquisition step is performed by the solvent separator 10 in FIG. The solid content concentrate separated in the gravity sedimentation tank 7 is supplied to the solvent separator 10, and the solvent is evaporated and separated from the solid content concentrate in the solvent separator 10. In addition, a byproduct charcoal acquisition process is not an essential process.

  As a method for separating the solvent from the solid concentrate, a general distillation method, evaporation method, or the like can be used as in the above-described ashless coal acquisition step. The solvent separated by the solvent separator 10 is returned to the solvent tank 2 and can be circulated and used repeatedly. By separating the solvent, by-product charcoal (also referred to as RC or residual charcoal) in which solvent-insoluble components including ash and the like are concentrated can be obtained from the solid concentrate. By-product charcoal contains ash, but has no water and has a sufficient calorific value. By-product coal does not exhibit softening and melting properties, but the oxygen-containing functional groups are eliminated, so that when used as a blended coal, it inhibits the softening and melting properties of other coals contained in this blended coal. It is not a thing. Therefore, this by-product coal can be used as a part of the blended coal of the coke raw material, as in the case of ordinary non-slightly caking coal, and is used for various fuels without using the coke raw coal. It is also possible.

(Verification experiment)
It verified that the sedimentation property (separability, sedimentation speed) of the coal component (for example, ash content) insoluble in a solvent improved by the manufacturing method which concerns on this invention. This will be described with reference to FIGS.

  Coal pulverized such that coal particles having a particle size of 3 mm or less are 90% by weight or more (hereinafter referred to as “Example coal 1”), coal pulverized so that the maximum particle size is 1 mm or less (hereinafter, “ Example coal 2 ”) and coal pulverized so as to have a maximum particle size of 0.5 mm or less (hereinafter referred to as“ example coal 3 ”) were prepared in total. The maximum particle size was adjusted by an operation in which the sample after passing through the pulverizer was put on a screen and the sample remaining on the screen was put into the pulverizer again. That is, a similar operation of the sieving operation shown in JIS A 1102 was performed simultaneously with pulverization. When adjusting Example Coal 1, a screen with an opening of 3 mm, Example Coal 2 with 1 mm, and Example Coal 3 with a 0.5 mm screen was used. These three types of particle size distributions are shown in FIG. The particle size distribution was examined by performing a sieving operation shown in JIS A1102.

  Each of these three types of coal was mixed with a solvent to prepare a slurry having a coal concentration of 20 wt% dry (based on dry coal). As a solvent, an oil component (coal derivative) purified from coal containing methylnaphthalene, which is a bicyclic aromatic compound, as a main component was used.

  The vertically long autoclave 50 used in the experiment was a cylindrical pressure vessel, and as shown in FIG. 2, the liquid was allowed to escape from a total of two places at a predetermined height from the bottom. Further, a stirrer 50 a is installed inside the autoclave 50. The autoclave 50 is erected so that the longitudinal direction thereof coincides with the vertical direction.

The prepared slurry was put into the autoclave 50. And extraction of a solvent soluble component was performed for 20 minutes at 400 degreeC. Thereafter, the temperature was lowered to 350 ° C. and stirring was performed, and the liquid level was adjusted by extracting the liquid from the sampling position P1 to the sampling container 51a. Liquid level adjustment means that the liquid level in the autoclave 50 at this time is adjusted so that the liquid level comes to the level (height) of the sampling position P1, as shown in FIG. is there. Further, to determine the concentration C ₀ of the solvent-insoluble component contained in the liquid at this time _(initial concentration).

Then, stirring was stopped and the liquid was allowed to stand for an arbitrary time t. The liquid was collected into a sampling vessel 51b from the sampling position P2 after a time t, to measure the concentration C _t of the solvent-insoluble component contained in the liquid.

Then, the sedimentation rate [m / h] of the solvent insoluble component was calculated from the distance H between the sampling position P1 and the sampling position P2 (the distance at which the solvent insoluble component settled) and the standing time t. Further, the sedimentation rate [%] of the solvent-insoluble component was calculated from the initial concentration C ₀ and the concentration C _t after the standing time t. The results are shown in FIG.

  As can be seen from FIG. 4, even with Example Coal 1, a sufficient sedimentation rate was obtained. In Examples Coal 2 and 3, sedimentation was further rapid. Moreover, there was no big difference in the sedimentation speed between Example Coal 2 and Example Coal 3. That is, it is understood that it is preferable to pulverize coal so that the maximum particle size is 1 mm or less in consideration of the cost required for pulverizing coal.

(Action / Effect)
In the present invention, by adjusting the particle size of the coal before mixing the coal and the solvent, the cohesiveness of the coal component insoluble in the solvent is improved. By improving the cohesiveness of the coal component insoluble in the solvent, the separation efficiency of the coal component in the separation step (sedimentation speed when using the gravity sedimentation method) is improved. As a result, ashless coal from which ash has been sufficiently removed can be produced with high efficiency. In this manufacturing method, the use of the caking coal described in Patent Document 1 is unnecessary. That is, according to the present invention, for example, even when ashless coal is produced in a coal production area where there is no room for various types of raw material (coal), ashless coal from which ash is sufficiently removed can be obtained. It can be manufactured with high efficiency and at low cost.

  In addition, by adjusting the coal particle size so that the coal particles having a particle size of 3 mm or less are 90% by weight or more, coal components insoluble in the solvent can be sufficiently separated in the separation step.

  Furthermore, the coal particle size is adjusted so that the coal particle having a particle size of 1 mm or less is 90% by weight or more and the maximum particle size is 3 mm or less, or the maximum particle size is 1 mm or less (all coals If the particle size of the coal is adjusted so that the particle size of the particles is 1 mm or less, coal components insoluble in the solvent can be separated more quickly.

  As a method for adjusting the particle size of coal, there are a method of pulverizing coal, a method of sieving, and the like. However, according to the method of pulverizing coal, all the coal can be used, which is excellent in economic efficiency.

  In the separation step of separating the solution containing a coal component that is soluble in the solvent and the solid content concentrate in which the coal component insoluble in the solvent is concentrated, methods such as gravity sedimentation, filtration, and centrifugation are used. Can be used. The gravity sedimentation method can suppress the equipment cost and operation cost required to implement the method lower than the filtration method and the centrifugal separation method. That is, if the gravity sedimentation method is used in the separation step, ashless coal can be produced at a lower cost. Moreover, according to the gravity sedimentation method, the aggregation state of the solvent-insoluble component is easily maintained, so that the separation efficiency in the separation step is further improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

1: Coal hopper 2: Solvent tank 3: Slurry preparation tank 4: Transfer pump 5: Preheater 6: Extraction tank 7: Gravity settling tank 8: Filter unit 9, 10: Solvent separator 100: Ashless coal production equipment

Claims (6)

An extraction step of heating a slurry obtained by mixing coal and a solvent to extract a coal component soluble in the solvent;
A separation step of separating the slurry obtained in the extraction step into a solution containing a coal component soluble in a solvent and a solid content concentrate in which a coal component insoluble in the solvent is concentrated;
Ashless coal acquisition step of obtaining ashless coal by evaporating and separating the solvent from the solution separated in the separation step;
In a method for producing ashless coal,
A particle size adjusting step for adjusting the particle size of the coal before mixing the coal and the solvent;
The method for producing ashless coal, wherein the coagulation property of a coal component insoluble in a solvent is improved by the particle size adjustment step. In the manufacturing method of ashless coal of Claim 1,
The method for producing ashless coal, wherein the particle size of the coal is adjusted so that coal particles having a particle size of 3 mm or less are 90% by weight or more in the particle size adjusting step. In the manufacturing method of the ashless coal of Claim 2,
In the particle size adjusting step, the coal particle size is adjusted so that coal particles having a particle size of 1 mm or less are 90% by weight or more and the maximum particle size is 3 mm or less. . In the manufacturing method of the ashless coal of Claim 3,
The method for producing ashless coal, wherein in the particle size adjustment step, the particle size of the coal is adjusted so that the maximum particle size is 1 mm or less. In the manufacturing method of the ashless coal in any one of Claims 1-4,
The method for producing ashless coal, wherein the particle size is adjusted by pulverizing coal in the particle size adjusting step. In the manufacturing method of the ashless coal in any one of Claims 1-5,
Gravity sedimentation method is used in the said separation process, The manufacturing method of ashless coal characterized by the above-mentioned.

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