Title of invention: Carbon-containing powder, separation method, and usage of carbon-containing powder Technical field [0001] 　The present invention relates to carbon-containing powder. Background technology [0002] 　Most of fly ash generated during power generation in a coal-fired thermal power plant or the like is recycled as a raw material for concrete, a raw material for building materials, a raw material for cement, or the like. Fly ash contains ash composed of metal oxides such as Al 2 O 3 and SiO 2 and unburned carbon that is the unburned carbon component. Therefore, in order to use it as a building material raw material, a concrete raw material (admixture), etc., it is preferable to separate unburned carbon contained in fly ash to reduce the unburned carbon concentration. [0003] 　As a method for separating unburned carbon in fly ash, for example, an electrostatic separation method or a flotation method is known. The electrostatic separation method is a method in which, in a dry state, by throwing fly ash into the electrodes of the parallel plates, the charged unburned carbon is attracted to the positive electrode side and separated. Further, the flotation method, by attaching unburned carbon particles through a collecting agent such as kerosene to the micro air generated using a foaming agent in the fly ash slurry, the unburned carbon particles are removed. It is a method of floating and separating. [0004] 　For example, Patent Document 1 discloses a method of removing unburned carbon in fly ash by flotation. In the flotation method of Patent Document 1, first, water is added to stir fly ash that is slurried to generate active energy on the surface of the unburned carbon particles, thereby making the unburned carbon particles lipophilic. (Hydrophobize). Next, a slurry containing oleophilicized unburned carbon is added with a scavenger such as kerosene or light oil and a foaming agent to adhere the scavenger to the unburned carbon, and to generate unburned carbon in the bubbles. Attach and float. By such a flotation method, a mixture of unburned carbon (specific gravity: 1.3 to 1.5) which is a hydrophobic particle and a metal oxide (specific gravity: 2.4 to 2.6) which is a hydrophilic particle is used. Unburned carbon is separated from a fly ash. Prior art documents Patent literature [0005] Patent Document 1: Japanese Patent Laid-Open No. 2007-167825 Summary of the invention Problems to be Solved by the Invention [0006] 　By the way, when recycling fly ash, it is desirable to effectively utilize not only metal oxides such as Al 2 O 3 and SiO 2 but also unburned carbon as described above. [0007] 　However, in the flotation method in which the unburned carbon contained in the fly ash is adhered to the bubbles and floated as described in Patent Document 1, there is a problem that the separation speed is slow and the separation efficiency is poor. For this reason, a large amount of fine particles of the metal oxide remain in the separated unburned carbon, making it difficult to separate and collect only unburned carbon with a high carbon content. Furthermore, fine particles of metal oxides such as SiO 2 and Al 2 O 3 tend to agglomerate with other particles due to attractive forces such as van der Waals force and electrostatic force in a dry state, and therefore, they are less than unburned carbon particles. Will also adhere. Therefore, it is more difficult to properly separate the unburned carbon particles and the fine particles of the metal oxide contained in the fly ash. [0008] 　For these reasons, it has been difficult to separate unburned carbon contained in fly ash with a high carbon content by the conventional separation method. For this reason, conventionally, the characteristics of the unburned carbon alone separated and collected from the fly ash have not been elucidated, which has been an obstacle to the effective use of the unburned carbon. Therefore, conventionally, it has been desired to separate carbon-containing powder such as unburned carbon having a high carbon content from coal ash such as fly ash, elucidate its characteristics, and effectively use the carbon-containing powder. .. [0009] 　Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved carbon-containing powder, a separation method, and a method of using the carbon-containing powder. Means for solving the problem [0010] 　In order to solve the above problems, according to an aspect of the present invention, 　a carbon-containing powder containing carbon particles and oxide particles, 　wherein the content of the carbon component in the carbon-containing powder is 50% by mass or more. , 95% by mass or less, and the 　oxide particles are particles composed of a compound containing one or both of a SiO 2 component and an Al 2 O 3 component, and the SiO 2 component in the oxide particles. The total content of the Al 2 O 3 components is 75% by mass or more, the 　carbon particles are porous particles in which a plurality of pores are formed, and 　at least a part of the oxide particles is Provided is a carbon-containing powder that is present in the pores of carbon particles. [0011] 　The content of the carbon component in the carbon-containing powder may be 70% by mass or more and 95% by mass or less. [0012] 　The N/C ratio, which is the mass ratio of the nitrogen component and the carbon component contained in the carbon-containing powder, may be more than 0 and 0.02 or less. [0013] 　The particle diameter of the oxide particles may be 1 to 20 μm in terms of volume-based 50% particle diameter. [0014] 　The average value of the circularity of the oxide particles may be more than 0.9 and 1 or less. [0015] The content of the 　SiO 2 component in the oxide particles is 50% by mass or more and 80% by mass or less, and the content of the 　Al 2 O 3 component in the oxide particles is 10% by mass or more, 30% or more. You may make it a mass% or less. [0016] 　The carbon-containing powder may have a specific surface area of ​​50 to 300 m 2 /g. [0017] 　Further, in order to solve the above problems, according to another aspect of the present invention, 　a separation derived from fly ash, a mixture in which carbon particles and oxide particles are mixed is separated to separate the carbon particles and the oxide particles. A method, which 　comprises mixing the mixture, water, and a hydrophobic liquid having a specific gravity larger than that of the water to form a mixed liquid, and allowing the 　mixed liquid to stand, and a hydrophobic property containing the carbon particles. A separation method is provided that includes a specific gravity separation step of separating the carbon particles and the oxide particles by separating the liquid phase and the aqueous phase containing the oxide particles. [0018] 　A first recovery step of recovering the oxide particles by separating the water from the aqueous phase separated in the specific gravity separation step may be further included. [0019] 　The hydrophobic liquid phase separated in the specific gravity separation step further includes a second recovery step of recovering the carbon-containing powder by separating the hydrophobic liquid, 　wherein the carbon-containing powder includes the carbon particles and the containing oxide particles, 　the content of the carbon component in the carbon-containing powder, 50 mass% or more and 95 mass% or less, 　the oxide particles, SiO 2 component or Al 2 O 3 either of the components It is a particle composed of a compound containing one or both of them, and the total content of the SiO 2 component and the Al 2 O 3 component in the oxide particles is 75% by mass or more, and the 　carbon particles are plural. The porous particles may have pores formed therein, and 　at least a part of the oxide particles may be present in the pores of the carbon particles. [0020] 　The N/C ratio, which is the mass ratio of the nitrogen component and the carbon component contained in the carbon-containing powder, may be 0.02 or less. [0021] 　The combination of the mixing step and the specific gravity separation step may be repeated in multiple stages by a countercurrent multistage continuous process. [0022] 　Before the specific gravity separation step, or during the specific gravity separation step, 　either or both of the hydrophobic liquid and water, and by performing a pulverization process on the mixed solution with the mixture, contained in the mixed solution. The method may further include a crushing step of crushing the carbon particles . [0023] 　In the crushing step, the carbon particles contained in the mixed solution may be crushed by a crushing process using beads. [0024] 　The fly ash is produced by burning coal, the 　carbon particles are particles of unburned carbon left unburned during the combustion, and the 　oxide particles are ash content of the coal melted during the combustion. You may make it a granular particle. [0025] 　In the specific gravity separation step, the 　mixed solution is allowed to stand to separate into a hydrophobic liquid phase containing the carbon particles and a water phase containing the oxide particles, and a 　coarse separation step. Water is added to and mixed with the hydrophobic liquid phase, and the hydrophobic liquid phase containing the carbon particles and the oxide particles are mixed by allowing the liquid mixture of the hydrophobic liquid phase and water to stand. A water washing step of separating into an aqueous phase may be included. [0026] 　In order to solve the above problems, according to another aspect of the present invention, the 　carbon-containing powder is used as a substitute for coal used in a sintering machine, a combustion furnace or a converter, or an SO 2 adsorbent or A method of using a carbon-containing powder, which is used as a denitration material, is provided. [0027] 　The carbon-containing powder may be used after mixing the carbon-containing powder with another powder to increase the bulk specific gravity of the carbon-containing powder. Effect of the invention [0028] 　As described above, according to the present invention, it is possible to provide a new and improved carbon-containing powder, a separation method, and a method of using the carbon-containing powder. Brief description of the drawings [0029] FIG. 1A is a front view schematically showing the fly ash before the wet separation treatment according to the first embodiment of the present invention. FIG. 1B is a sectional view schematically showing fly ash before the wet separation treatment according to the same embodiment. FIG. 2A is a front view schematically showing the carbon-containing powder after the wet separation treatment according to the same embodiment. FIG. 2B is a sectional view schematically showing the carbon-containing powder after the wet separation treatment according to the same embodiment. FIG. 3A is a front view schematically showing the carbon-containing powder after the pulverization treatment and the wet separation treatment according to the second embodiment of the present invention. FIG. 3B is a sectional view schematically showing the carbon-containing powder after the pulverization treatment and the wet separation treatment according to the same embodiment. FIG. 4 is a process chart showing the outline of the method for producing carbon-containing powder according to the first embodiment of the present invention. FIG. 5 is a process chart showing a separation and recovery method in the method for producing carbon-containing powder according to the same embodiment. FIG. 6 is a schematic diagram showing a separation and recovery apparatus according to the same embodiment. FIG. 7 is a process chart showing a separation and recovery method in the method for producing carbon-containing powder according to the second embodiment of the present invention. FIG. 8 is a process drawing showing a modified example of the separation and recovery method according to the same embodiment. FIG. 9 is a process drawing showing a modified example of the separation and recovery method according to the same embodiment. FIG. 10 is a process drawing showing a modified example of the separation and recovery method according to the same embodiment. FIG. 11 is a process diagram showing a separation and recovery method by a countercurrent multistage continuous process according to a third embodiment of the present invention. FIG. 12 is a graph showing the relationship between the bead diameter and the carbon content of the carbon-containing powder according to Example 5-1 of the present invention. FIG. 13 is a graph showing changes in the content of unburned carbon particles in the solid matter of the water phase or the solvent phase in each stage of the countercurrent four-stage continuous process according to Example 11 of the present invention. MODE FOR CARRYING OUT THE INVENTION [0030] 　Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, constituent elements having substantially the same functional configuration are designated by the same reference numerals, and a duplicate description will be omitted. [0031] [1. Background and Outline of the Present Invention] 　First, a background of the present invention and an outline of a carbon-containing powder and a method for producing the same according to an embodiment of the present invention will be described. [0032] 　As described above, fly ash is a kind of coal ash produced by combustion of coal, and for example, fly ash is produced by burning fuel coal in a boiler or the like of a power plant. Bituminous coal or sub-bituminous coal is mainly used as fuel coal at the power plant. [0033] 　Fly ash contains unburned carbon (carbon component), which is a carbon component that has remained unburned, in addition to metal oxides (ash content) made of a compound including an Al 2 O 3 component, a SiO 2 component, and the like. The carbon content (content of carbon component) in the fly ash is 1.5 to 15% by mass, and the content of metal oxide such as SiO 2 component and Al 2 O 3 component is 75 to 98% by mass. . [0034] 　During the combustion process of coal in power plants, etc. , oxides such as SiO 2 component and Al 2 O 3 component in fuel coal are temporarily melted. It exists as substantially spherical particles with few irregularities. The substantially spherical shape referred to here is not limited to a true spherical shape, and may be a shape having almost no irregularities on the surface and almost a spherical shape, and also includes shapes such as an ellipsoidal shape and a polygonal spherical shape. The particle diameter of the oxide particles is generally 200 μm or less, and oxide particles having a diameter of less than 1 μm are often included in an amount of 5 to 10% by mass. Unlike porous particles such as unburned carbon particles described later, such oxide particles are mostly solid particles having a substantially spherical shape, and pores are not formed in the surface layer of the oxide particles. As described above, since fly ash contains a large amount of substantially spherical solid oxide particles, the specific surface area of ​​fly ash is as small as 0.5 to 10 m 2 /g. The particle size of fly ash is about 1 to 200 μm. [0035] 　On the other hand, when coke is produced from bituminous coal and subbituminous coal, the bituminous coal and subbituminous coal are subjected to carbonization treatment in a coke oven or the like. It has been found that in this dry distillation treatment, the specific surface area of ​​the dry distillation product becomes large due to the voids generated when the volatile matter disappears by heating (Non-Patent Document 1). 　Non-Patent Document 1: Tsuyoshi Yukumoto, 3 others, "Discrimination of Coal and Coke", Ministry of Finance Tariff Central Analysis Report, Vol. 49 pp. 69-76, March 19, 2011 [0036] 　However, since coal is burned in the boiler of the power plant, which is different from the dry distillation state like in the coke oven, it is not known whether activation has progressed on the surface of unburned carbon particles in fly ash in the past. Met. Furthermore, in the dry state, the finer the oxide particles, the smaller the particle size, the more easily they agglomerate with other particles by the attractive force such as Van der Waals force or electrostatic force, and the unburned carbon particles in the fly ash. Content is low. Therefore, many oxide particles adhere to the surface of the unburned carbon particles. For this reason, it has not been possible to elucidate the individual characteristics of the unburned carbon particles that have remained unburned in the boiler. [0037] 　Further, even if pores are present in the surface layer of the unburned carbon particles due to activation, fine oxide particles enter the pores and are attached by an attractive force such as van der Waals force or electrostatic force. For this reason, it is difficult to remove the oxide particles from the pores of the unburned carbon particles, and it has become more difficult to elucidate the individual characteristics of the unburned carbon particles. [0038] 　In the situation as described above, the present inventor suitably uses a special wet separation method to separate unburned carbon particles in fly ash from oxide particles, and the unburned carbon particles are enriched in carbon-containing carbon. A method for producing powder was found, the characteristics of the carbon-containing powder produced by the method were investigated and analyzed, and various new characteristics were found. [0039] 　Specifically, first, it was found that the nitrogen content of fly ash (coal ash) after combustion in a boiler or the like of a power plant is low, and the N/C ratio of the fly ash is 0.02 or less. The fly ash contains unburned carbon particles (carbon component) and oxide particles (ash content) made of a compound containing a SiO 2 component, an Al 2 O 3 component, etc. Hereinafter, it is found that the unburned carbon particles P2 are porous particles and a large number of pores P20 are formed in the surface layer of the unburned carbon particles P2, as shown in FIG. .. Further, the oxide particles P1 are substantially spherical solid particles and may adhere to the surface of the unburned carbon particles P2, or may have a plurality of pores P20 formed in the surface layer of the unburned carbon particles P2. It turned out that there are cases where it exists inside of the. [0040] 　Therefore, as shown in FIG. 1, in order to separate and concentrate the unburned carbon particles P2 from the fly ash in which the unburned carbon particles P2 and the oxide particles P1 are mixed, the carbon-containing powder according to the present embodiment. In the manufacturing method of, the following special wet separation method is used. [0041] 　First, water, a hydrophobic liquid (for example, an organic solvent having a hydrophobic property), and fly ash are mixed and stirred, and the mixture is left to stand, whereby a hydrophobic liquid phase containing unburned carbon particles P2 and oxidation are performed. It separates into the aqueous phase containing the physical particles P1 (specific gravity separation step). Next, the cake containing the unburned carbon particles P2 is recovered by separating the hydrophobic liquid from the hydrophobic liquid phase (solid-liquid separation step). Then, the cake is heated to volatilize the hydrophobic liquid, thereby collecting the carbon-containing powder in which the unburned carbon particles P2 are concentrated (collection step). [0042] 　By such a production method, the unburned carbon particles P2 can be separated and concentrated from the fly ash to obtain a carbon-containing powder having a high carbon content (carbon content: 50 mass% or more). In this separation method, as shown in FIGS. 2A and 2B (hereinafter collectively referred to as FIG. 2), the fine oxide particles P1 that have entered the pores P20 of the unburned carbon particles P2 are not removed so much. Most of the oxide particles P1 adhering to the surface of the unburned carbon particles P2 can be separated and removed. [0043] 　Furthermore, it is preferable to perform a pulverization process on the mixed solution of either or both of the water and the hydrophobic liquid and fly ash in a step before or after the specific gravity separation step (pulverization step). Examples of the pulverizing method include ultrasonic pulverizing treatment, high-speed shear mixer pulverizing treatment, and ball mill or bead mill pulverizing treatment. The hydrophobic liquid used in the crushing step may be the same as or different from the hydrophobic liquid L2 used in the specific gravity separation step. [0044] 　As shown in FIGS. 3A and 3B (hereinafter, collectively referred to as FIG. 3), the unburned carbon particles P2 in the fly ash are crushed by the crushing process and divided into a plurality of pieces at the fracture surface P21 to be made into fine particles. To be done. As a result, the substantially spherical oxide particles P1 that have entered the pores P20 near the fracture surface P21 are released from the pores P20. Therefore, not only the oxide particles P1 attached to the surface of the unburned carbon particles P2 but also the oxide particles P1 that have entered the pores P20 are separated and removed from the unburned carbon particles P2. The fuel carbon particles P2 and the oxide particles P1 can be more preferably separated. By doing this, it is possible to obtain a carbon-containing powder having a higher carbon content (carbon content: 70% by mass or more) by subjecting fly ash to a pulverization process. [0045] [2. Configuration of Carbon-Containing Powder] 　Next, the configuration of the carbon-containing powder mainly composed of unburned carbon particles separated and collected from the fly ash according to the present embodiment will be described in detail. [0046] 　[2.1. Characteristics of Carbon-Containing Powder] 　As a result of investigating and analyzing the components, physical properties, etc. of the carbon-containing powder (carbon content rate: 50 mass% or more) recovered from the fly ash by the above manufacturing method, the carbon-containing powder is It has been found to have characteristics. Below, with reference to Table 1, the characteristics of the carbon-containing powder according to the present embodiment will be described in comparison with the conventional carbon-containing substance. [0047] [table 1] [0048] 　(1) N/C ratio The 　N/C ratio is a mass ratio between the amount of nitrogen component (nitrogen content) and the amount of carbon component (carbon content) in a certain material. It is calculated by dividing by the content rate. Since the carbon-containing powder according to the present embodiment has a low nitrogen content and a high carbon content, the N/C ratio of the carbon-containing powder is more than 0 and 0.02 or less. It is within the range of 0065 to 0.0196. Although not shown in Table 1, the N/C ratio of anthracite, bituminous coal, and subbituminous coal is, for example, 0.008 to 0.03, but most of them are more than 0.02. The N/C ratio of the carbon-containing powder according to the present embodiment corresponds to a low region among the N/C ratios of anthracite, bituminous coal, and subbituminous coal. The N/C ratio of unburned carbon contained in the original fly ash before the wet separation step according to the present embodiment is 0.02 or less, and the nitrogen content is low. Therefore, the N/C ratio of the carbon-containing powder mainly composed of the separated and recovered unburned carbon is also 0.02 or less. As will be described later, it is considered that the N/C ratio decreases as the combustion temperature in the boiler of the power plant increases. [0049] 　(2) Carbon content 　Carbon content C of the carbon-containing powder is recovered by a wet separation from the fly ash by the production method according to the present embodiment A is preferably 50 mass% or more and 95 mass% or less. In particular, the carbon content C A of the carbon-containing powder recovered by the manufacturing method including the crushing step is 70% by mass or more and 95% by mass or less. [0050] 　Therefore, in the carbon-containing powder produced by the production method according to the present embodiment, the carbon content C A is 50% by mass or more, more preferably 70% by mass or more, and the N/C ratio is 0.02 or less. And small. Therefore, the carbon-containing powder according to the present embodiment can be used as coal having a low nitrogen content (low-nitrogen coal), and can be used as a conventional low-nitrogen coal used in a coal processing facility such as a sintering machine, a power plant, and a converter. It can be effectively used as a substitute for. In particular, the N/C ratio is more preferably 0.015 or less for effective use as a substitute for the low-nitrogen coal used in the sintering machine. Therefore, the production method according to the present embodiment is capable of recovering and recycling carbon-containing powder having a carbon content as high as low-nitrogen coal and a low N/C ratio from fly ash. Important and beneficial to. [0051] 　(3) Specific Surface Area As 　shown in FIGS. 2 and 3, the unburned carbon particles P2 contained in the carbon-containing powder according to the present embodiment are porous particles having a large number of pores P20 formed in the surface layer thereof. .. Therefore, the specific surface area of ​​the carbon-containing powder according to the present embodiment is 50 to 300 m 2 /g, which is equivalent to that of the activated coke powder, and the specific surface area of ​​the fly ash before the separation treatment (0.5 to 10 m 2 /g). More than a few dozen times to a hundred times larger. [0052] 　(4) SO 2 Adsorption Ability and Denitrification Ability 　As described above, the specific surface area of ​​the carbon-containing powder according to the present embodiment is extremely large at 50 to 300 m 2 /g. Therefore, the carbon-containing powder according to the present embodiment has an SO 2 adsorbing ability and a denitrifying ability, and can be effectively used as an SO 2 adsorbent and a denitrifying agent. [0053] 　(5) Component of 　Oxide Particle The oxide particle P1 is a particle made of a compound containing at least one or both of a SiO 2 component and an Al 2 O 3 component. In fly ash, Si and Al are mainly contained as compounds such as mullite (Al 6 Si 2 O 13 ), quartz (SiO 2 ), and amorphous (nAl 2 O 3 .mSiO 2 ). However, n and m are positive numbers. These compounds correspond to the SiO 2 component or the Al 2 O 3 component. The fly ash contains oxide particles P1 made of such a compound. Therefore, the carbon-containing powder separated from the fly ash also contains a part of the oxide particles P1 made of the compound, which remains. [0054] 　The carbon-containing powder according to the present embodiment is a powder mainly composed of unburned carbon (carbon component), but also contains oxide particles P1 that could not be separated by the specific gravity separation process described later. The content of the oxide particles P1 in the carbon-containing powder is less than 50% by mass, preferably less than 30% by mass. The total content of the SiO 2 component and the Al 2 O 3 component in the oxide particles P1 is 75% by mass or more and 98% by mass or less. As described above, the oxide particles P1 are composed of a compound mainly composed of a SiO 2 component and an Al 2 O 3 component, but may contain oxides of other elements in addition to them. The content of the SiO 2 component in the oxide particles P1 is 50 mass% or more and 80 mass% or less, and the content of the Al 2 O 3 component in the oxide particles P1 is 10 mass% or more, 30 mass% or more. It is not more than mass %. In addition, it is preferable to use "average content rate" as the content rate of these. The average content is obtained by measuring the content of the SiO 2 component and the Al 2 O 3 component using a sample of a plurality of oxide particles P1 and calculating the average of the plurality of measured values. [0055] 　(6) Particle Size, Circularity, and Existence Form of Oxide Particles The 　carbon-containing powder according to the present embodiment contains not only unburned carbon particles P2 but also oxide particles P1. These oxide particles P1 are particles which are cooled and granulated after the ash content of coal is melted by combustion heat when burning coal as described above, and most of them are substantially spherical solid particles. Is. The particle diameter of the oxide particles P1 is 1 to 20 μm in terms of volume-based 50% particle diameter (median diameter D50). The average value of the circularity of the oxide particles P1 is more than 0.9 and 1 or less. Here, the circularity of a particle is the ratio of the perimeter of a circle having the same area as the projected image of the particle to the perimeter of the projected image of the particle. [0056] 　At least a part of the oxide particles P1 is present in a large number of pores P20 formed in the surface layer of the unburned carbon particles P2. The content ratio of the oxide particles P1 remaining in the pores P20 and the oxide particles P1 contained outside the pores P20 in the carbon-containing powder in which the oxide particles P1 are separated from the surface by the specific gravity separation treatment described below is It may be more than 5% by mass and less than 50% by mass. As described above, in the carbon-containing powder according to the present embodiment, the 50% particle diameter is 1 to 20 μm in the pores P20 of the porous unburned carbon particles P2, and the average value of the circularity is more than 0.9. It has a characteristic configuration in which granular oxides (substantially spherical oxide particles P1) of 1 or less are mixed. The carbon-containing powder having such a characteristic constitution has not hitherto been known and can be said to be a new and useful low-nitrogen carbon powder. [0057] 　[2.2. Measuring Method] 　Next, a measuring method of the above characteristics of the carbon-containing powder according to the present embodiment will be described. [0058] 　(1) Method for measuring specific surface area Using a 　flow-type specific surface area measuring device (for example, FlowSorb II 2300 manufactured by Shimadzu Corporation), a carbon-containing powder mainly composed of porous unburned carbon particles was obtained by a gas adsorption method. The specific surface area (unit: m 2 /g) can be measured. In the gas adsorption method, a mixed gas of helium and nitrogen (volume ratio 7:3) is used, and the amount of monomolecular gas adsorbed and the specific surface area can be calculated using the BET formula. [0059] 　(2) Method for measuring SO 2 adsorption capacity 　5 to 50 ml of carbon-containing powder (sample) is put in a reaction tank, the temperature of the reaction tank is set to 100° C., and a sample gas is bubbled for 3 hours. The composition of the sample gas can be SO 2 : 2% by volume, H 2 O: 10% by volume, O 2 : 6% by volume, and the balance being nitrogen. After aeration of the sample gas, the carbon-containing powder was heated to 400° C. under a nitrogen stream, and the generated SO 2 was collected and quantified to determine the adsorption capacity of SO 2 by the carbon-containing powder (unit: mg-SO 2 /G-carbon-containing powder) can be measured. [0060] 　(3) Method 　for measuring denitrification capacity 5 to 50 ml of carbon-containing powder (sample) is put in a reaction tank for analysis , and a sample gas is aerated for 10 hours at a reaction tank temperature of 150° C. and SV of 500 h −1 . The composition of the sample gas can be NO: 200 ppm, NH 3 : 200 ppm, O 2 : 6% by volume, H 2 O: 10% by volume, and the balance nitrogen. After ventilating the sample gas, the NO concentration and O 2 concentration in the gas discharged from the reaction tank are measured, and the denitration rate (volume %) by the carbon-containing powder is calculated by calculating the reduction rate of the NO concentration in the steady state. be able to. [0061] 　(4) Method of measuring carbon content and nitrogen content The carbon content and the nitrogen content of the 　carbon-containing powder according to the present embodiment were measured according to JIS M8819. [0062] 　(5) Method of measuring sulfur content The sulfur content of the 　carbon-containing powder according to this embodiment was measured according to JIS M8813. [0063] 　(6) Method for measuring particle size of oxide particles in 　carbon-containing powder The carbon-containing powder according to the present embodiment is put in a crucible and heated at 600° C. for 2 hours in the presence of air to burn the carbon component. .. As a result, granular oxides (substantially spherical oxide particles P1) that are intervening particles contained in the carbon-containing powder can be obtained as a residue. Usually, at 600° C., the component containing carbon as a main component burns, but since the granular oxide does not melt, the granular oxide can be recovered without changing its shape. Then, the particle size distribution of the granular oxide is measured using a laser diffraction type particle size distribution measuring device, whereby the volume-based 50% particle size (median size D50) can be obtained. [0064] 　(7) Method for measuring circularity of oxide particles in carbon-containing powder For the circularity of 　the oxide particles P1 recovered in (6) above, the shape of the imaged oxide particles is analyzed using a particle image analyzer. You can ask for it. For example, a suspension obtained by adding a dispersant aqueous solution to a sample of oxide particles and subjecting to ultrasonic waves for dispersion treatment is prepared. The oxide particles in the suspension can be picked up as a still image by the sheath flow method using a flow type particle image analyzer. The average value of the circularity may be the average of the circularity of a predetermined number or more of oxide particles measured in the sample. The number of oxide particles used to calculate the average value may be, for example, 10,000 or more. [0065] 　(8) Method for measuring content of SiO 2 component and Al 2 O 3 component 　in oxide particles Content of SiO 2 component [mass %] in substantially spherical oxide particles P1 recovered in (6) above , Also, the content [mass %] of the Al 2 O 3 component in the substantially spherical oxide particles can be measured by a fluorescent X-ray analysis method. [0066] The content of 　SiO 2 can be quantitatively analyzed by a fluorescent X-ray analyzer (XRF) by the glass bead method. Specifically, a plurality of measurement samples having a known SiO 2 content rate are prepared with different content rates, and the fluorescent X-ray intensity derived from Si of the prepared measurement sample is measured by a fluorescent X-ray analyzer. . Using the obtained Si-derived fluorescent X-ray intensity and the SiO 2 content , a calibration curve showing the relationship between the SiO 2 content and the fluorescent X-ray intensity is created in advance. After that, with respect to the sample of interest of which the content of SiO 2 is unknown, the fluorescent X-ray intensity derived from Si is measured by the fluorescent X-ray analyzer, and the obtained fluorescent X-ray intensity and the calibration curve are used to obtain SiO 2 The content rate of can be specified. Thereby, the content rate of the SiO 2 component in the oxide particles P1 can be obtained. [0067] 　Further, the content rate of Al 2 O 3 can be quantitatively analyzed by a fluorescent X-ray analyzer (XRF) by a glass bead method. Specifically, a plurality of measurement samples having a known Al 2 O 3 content rate are prepared by changing the content rate, and the fluorescent X-ray intensity derived from the Al of the prepared measurement sample is measured by a fluorescent X-ray analyzer. taking measurement. Using the obtained Al-derived fluorescent X-ray intensity and the Al 2 O 3 content rate , a calibration curve showing the relationship between the Al 2 O 3 content rate and the fluorescent X-ray intensity was created in advance. deep. Then, the fluorescent X-ray intensity of Al 2 O 3 is measured by a fluorescent X-ray analyzer with respect to a sample of which attention is paid to the content of Al 2 O 3 is unknown, and the obtained fluorescent X-ray intensity and a calibration curve are used. Thus, the content rate of Al 2 O 3 can be specified. Thereby, Al 2 O 3 in the oxide particles P1 is The content c of component Al can be obtained. [0068] 　From the content c Si [mass%] of the SiO 2 component in the oxide particles P1 and the content c Al [mass%] of the Al 2 O 3 component in the oxide particles P1 obtained as described above , It is possible to measure the total content c T [mass %] of the SiO 2 component and the Al 2 O 3 component in the oxide particles P1 in the carbon-containing powder by using the equation (1) . 　c T =c Si +c Al　(1) [0069] 　When measuring the content rates of (4), (5), and (8) above, an average value of a plurality of content rates measured using a plurality of samples may be calculated, or only one sample may be calculated. It may be used to measure the content. From the viewpoint of measurement accuracy, it is preferable to obtain the content rate using a plurality of samples. The same applies to the particle size of (6) and the circularity of (7). [0070] 　[2.3. Principle of Lowering N/C Ratio of Carbon-Containing Powder] 　Next, with reference to FIG. 4, the reason why the nitrogen content rate and the N/C ratio of the carbon-containing powder according to the present embodiment are low will be described. FIG. 4 is a process diagram showing the outline of the method for producing the carbon-containing powder P0 according to the present embodiment. [0071] 　As shown in FIG. 4, in the manufacturing method according to the present embodiment, for example, a fuel coal FC such as bituminous coal or subbituminous coal is burned in the boiler 4 or the like of a thermal power plant, and as a result of this combustion, fly ash that is coal ash is produced. Ash FA is generated (combustion process). The fly ash FA is introduced into the separation/recovery device 5 (details will be described later), and by the special wet separation method according to the present embodiment, oxide particles P1 composed of SiO 2 component, Al 2 O 3 component, etc. (Ash) and unburned carbon particles P2 (carbon component) are separated and collected (separation and collection step). Therefore, the carbon-containing powder P0 according to the present embodiment is manufactured through the combustion process in the boiler 4 and the separation/recovery process in the separation/recovery device 5. Here, the reason why the nitrogen content of the carbon-containing powder P0 according to the present embodiment is low is considered to be due to the combustion process of coal in the boiler 4, as described below. [0072] 　Generally, various carbonization gas is generated in the coal carbonization process in a coke oven. According to Non-Patent Document 2, although depending on the coal type, the nitrogen-containing gas in the carbonization gas (HCN, NH 3 , N 2 of), HCN, NH 3 occurs in starts from about 300 ° C., 800 It ends at about ℃. On the other hand, it is known that N 2 starts to be generated at about 600° C. and continues to be generated even at a high temperature of 800° C. or higher at which the generation of other nitrogen-based gas is almost finished. Further, generally, the carbon-based gas (CO, CH 4 , HCN) in the carbonized gas is rarely generated. From these, it can be predicted that during carbonization of coal, the N/C ratio of coal decreases as the temperature of carbonization in the coke oven increases. 　Non-Patent Document 2: Yasuhiro Fujibe, 2 others, “Distribution behavior of nitrogen in coal carbonization process by gas real-time measurement and XPS measurement”, Materials and Processes, Vol. 25 No. 2, Page. ROMBUNNO. 36, September 1, 2012 [0073] 　On the other hand, in the combustion process of the manufacturing method according to the present embodiment, the combustion temperature in the boiler 4 of the power plant is about 1300 to 1500° C., and the residence time of the coal powder in the boiler 4 is about several seconds. The residence time of the coal powder in the coke oven is extremely short, and the coal powder in the boiler 4 is in a combustion state rather than a carbonization state. It is considered that there is an oxygen concentration distribution in the boiler 4, and the oxygen concentration is particularly low near the surface of the coal powder, and the state is partially close to the carbonization state. Therefore, similarly to the coal carbonization step, even in the combustion step in the boiler 4, under the high temperature condition of the combustion temperature of 800° C. or higher, only the surface layer portion of the coal powder having a particle diameter of about several mm is carbonized, It is considered that the nitrogen component of the coal powder is reduced because the nitrogen compound contained in the surface layer is decomposed and gasified. Therefore, it is considered that the nitrogen content of the unburned carbon particles P2 in the fly ash FA after the combustion step decreases, and the N/C ratio of the carbon-containing powder P0 recovered by concentrating the unburned carbon particles also decreases. To be Further, it is considered that the N/C ratio of the carbon-containing powder P0 decreases as the combustion temperature in the boiler 4 increases. [0074] 　[2.4. Characteristics of Intervening Particles in Carbon-Containing Powder] 　Next, with reference to FIGS. 1 to 3, the characteristics relating to the substantially spherical oxide particles P1 included as intervening particles in the carbon-containing powder according to the present embodiment will be described in more detail. Explained. [0075] 　As shown in FIG. 1, the fly ash FA before the wet separation treatment contains more substantially spherical oxide particles P1 than the unburned carbon particles P2, and the unburned carbon particles P2 have pores P20 in the pores P20. The oxide particles P1 enter and the surfaces of the unburned carbon particles P2 are covered with the oxide particles P1. Therefore, conventionally, the characteristics of the unburned carbon particles P2 alone have been unclear. [0076] 　Therefore, in the manufacturing method according to the first embodiment of the present invention described below, unburned carbon particles are subjected to a wet separation process using water and a hydrophobic liquid (see FIG. 5 described below) without pulverization process. P2 and oxide particles P1 are separated. As a result, as shown in FIG. 2, the oxide particles P1 adhering to the surface of the unburned carbon particles P2 are removed, but the oxide particles entering the pores P20 of the unburned carbon particles P2. It is difficult to remove P1. The reason for this is that in the above wet separation treatment, either one or both of water and hydrophobic liquid cannot penetrate into the inside of the pores P20 of the unburned carbon particles P2, so that the oxide particles pass through the pores P20. It is considered that it is difficult to discharge P1. [0077] 　Here, consider a case where the carbon-containing powder containing such unburned carbon particles P2 is used as an SO 2 adsorbent. The pores P20 of the unburned carbon particles P2 blocked by the oxide particles P1 are counted in the specific surface area of ​​the carbon-containing powder. However, since the oxide particles P1 are held in the pores P20 of the unburned carbon particles P2, most of the exhaust gas (normal pressure) containing SO 2 and the like cannot enter the deep portion of the pores P20. . Thus, SO 2 not be effectively utilized pores P20 of unburned carbon particles P2 as an adsorption surface of, SO 2 there is room for improvement in performance as the adsorbent. [0078] 　Therefore, in a manufacturing method according to a second embodiment of the present invention described later, a wet separation process (see FIGS. 7 to 10 described later) that accompanies the pulverization process of the unburned carbon particles P2 is performed. By this crushing treatment, as shown in FIG. 3, the fragile porous unburned carbon particles P2 are easily crushed, and the plurality of pores P20 are connected by the fracture surface P21, so that the unburned carbon particles P2 are miniaturized. Cheap. If the unburned carbon particles P2 are pulverized, the substantially spherical oxide particles P1 in the pores P20 can easily contact with either or both of water and the hydrophobic liquid, and many oxides can be formed. The particles P1 can be discharged from the pores P20 and separated from the unburned carbon particles P2. As a result, a carbon-containing powder containing the unburned carbon particles P2 as a main component, in which the oxide particles P1 are separated, is obtained. In this carbon-containing powder, the carbon content increases and the surface area of ​​the carbon component serving as the SO 2 adsorption surface also increases. Therefore, the processing ability of the SO 2 containing gas by the carbon containing powder is increased, and the performance as the SO 2 adsorbent is improved. [0079] [3. Method for Producing Carbon-Containing Powder] 　Next, the method for producing carbon-containing powder according to the present embodiment will be described in detail. [0080] 　[3.1. Outline of Manufacturing Method of Carbon-Containing Powder] 　First, an outline of a manufacturing method of the carbon-containing powder according to the present embodiment will be described with reference to FIG. [0081] 　As shown in FIG. 4, the method for producing carbon-containing powder according to the present embodiment includes a combustion step (S0) and a separation/collection step (S1). In the combustion step (S0), the boiler 4 such as a thermal power plant burns the fuel coal FC to generate fly ash FA that is coal ash. Next, in the separation/collection step (S1), the separation/collection device 5 separates the oxide particles P1 and the unburned carbon particles P2 from the fly ash FA, and collects them. [0082] 　[3.2. Specific Gravity Separation Method] 　Next, in the separation and recovery step (S1) according to the present embodiment, a method of separating the fly ash FA into the oxide particles P1 and the unburned carbon particles P2 will be described in more detail. [0083] 　In the separation and recovery step according to the present embodiment, a mixture derived from fly ash FA and containing oxide particles P1 and unburned carbon particles P2 is mixed with carbon-containing powder P0 mainly containing unburned carbon particles P2 and oxidized. Wet separation is performed on the product particles P1. [0084] 　In this separation method, water is used as an extractant for the oxide particles P1 which are hydrophilic particles, and a hydrophobic liquid having a larger specific gravity than water, for example, is used as an extractant for the unburned carbon particles P2 which are hydrophobic particles. use. Then, the water and the hydrophobic liquid are mixed with fly ash (solid content) FA which is a mixture to be treated and stirred to generate a mixed liquid (first slurry) in which the mixture is dispersed (mixing step). Then, the mixed solution is allowed to stand in a separation device (for example, a settling tank, a settling tank such as a stationary tank) to make use of the difference in specific gravity between water and the hydrophobic liquid, so that the mixed solution is placed in the upper aqueous phase. And the lower hydrophobic liquid phase, while separating the oxide particles P1 (hydrophilic particles) into the aqueous phase and unburned carbon particles P2 (hydrophobic particles) into the hydrophobic liquid phase. Move (specific gravity separation step). Further, while separating and recovering the oxide particles P1 from the separated aqueous phase (second slurry) (first recovery step), from the hydrophobic liquid phase (third slurry) separated in the above separation step, The unburned carbon particles P2 are separated and collected (second collecting step). As a result, the oxide particles P1 and the unburned carbon particles P2 can be separated quickly and efficiently, and the oxide particles P1 and the unburned carbon particles P2 having a high content can be recovered and reused. [0085] 　Here, the hydrophobic liquid is a liquid having a hydrophobic property, that is, a liquid having a low affinity for water (in other words, it is difficult to dissolve in water or mix with water). The hydrophobic liquid may be a liquid whose solubility in water at 20° C. is 0 g/L or more and 5.0 g/L or less. The term “hydrophobicity” as used herein means a property including lipophilicity. The hydrophobic liquid may be a hydrophobic organic solvent (hereinafter referred to as “hydrophobic solvent”) or various oils such as silicone oil. As the hydrophobic solvent, for example, a fluorine-based, bromine-based, or chlorine-based organic solvent can be used. Since such a hydrophobic liquid has a low affinity for water, when the mixed liquid obtained by mixing and stirring the hydrophobic liquid and water is allowed to stand, an aqueous phase mainly composed of water and a hydrophobic liquid (for example, a hydrophobic solvent) are separated. It is separated into two phases, a hydrophobic liquid phase (for example, a hydrophobic solvent phase) as a main component. [0086] 　Table 2 shows an example of the hydrophobic liquid used in the separation method according to this embodiment. Each of the hydrophobic liquids illustrated in Table 2 has a specific gravity of more than 1, a solubility in water of 5.0 g/L or less, and is hydrophobic. [0087] [Table 2] [0088] 　The specific gravity of the hydrophobic liquid is preferably more than 1.05. Thereby, due to the difference in specific gravity between water and the hydrophobic liquid, it is possible to rapidly separate the aqueous phase and the hydrophobic liquid phase in a short time of, for example, about 1 to 30 seconds after the mixed solution is allowed to stand. [0089] 　The hydrophilic particles are particles having an affinity for water and have a property of being more easily mixed with water than the hydrophobic liquid. The oxide particles P1 contained in the fly ash FA are hydrophilic particles. On the other hand, the hydrophobic particles are particles having an affinity for the above-mentioned hydrophobic liquid and have a property of being more easily mixed with the hydrophobic liquid than water. The unburned carbon particles P2 contained in the fly ash FA are hydrophobic particles. Therefore, in the mixed liquid of water and the hydrophobic liquid, the hydrophilic particles (oxide particles P1) move from the hydrophobic liquid phase to the aqueous phase, and mainly exist dispersed in the aqueous phase. On the other hand, the hydrophobic particles (unburned carbon particles P2) move from the aqueous phase to the hydrophobic liquid phase and mainly exist dispersed in the hydrophobic liquid phase. [0090] 　The specific gravity of the oxide particles P1 which are hydrophilic particles is, for example, 2.4 to 2.6. The specific gravity of the unburned carbon particles P2 that are hydrophobic particles is, for example, 1.3 to 1.5. Thus, even when the specific gravity of the hydrophobic particles is smaller than the specific gravity of the hydrophilic particles, according to the separation method of the present embodiment, the hydrophilic particles are floated in the upper aqueous phase, The hydrophilic particles can be allowed to settle into the lower hydrophobic liquid phase for wet separation of both particles quickly and efficiently. Even if the specific gravity of the oxide particles P1 is smaller than that of the unburned carbon particles P2, the oxide particles P1 and the unburned carbon particles P2 are separated by wet separation using water and the hydrophobic liquid as described above. It is possible. In the present specification, the specific gravity of particles is the specific gravity (true specific gravity) of the particles themselves, not the bulk specific gravity of the particles. [0091] 　[3.3. Separation and Recovery Method of Carbon-Containing Powder] 　Next, with reference to FIG. 5, a separation and recovery method in the method for producing carbon-containing powder according to the present embodiment will be described in detail. In the following description, an example in which a hydrophobic solvent is used as the hydrophobic liquid will be described. [0092] 　As shown in FIG. 5, the separation and collection step (S1) includes a specific gravity separation step (S2) and a collection step (S4). The specific gravity separation step (S2) includes a rough separation step (S21) and a water washing step (S22), and the recovery step (S4) includes a solid-liquid separation step (S41) and a drying step (S42). [0093] 　In the coarse separation step (S21) of the specific gravity separation step (S2), fly ash FA, water L1 and hydrophobic solvent L2 are mixed. By allowing the mixed solution to stand, a specific gravity is separated into a hydrophobic solvent phase ph2 mainly containing unburned carbon particles P2 (in other words, carbon particles) as a solid content and an aqueous phase ph1 mainly containing oxide particles P1. To do. By this rough separation step (S21), the unburned carbon particles P2 and the oxide particles P1 in the fly ash FA can be roughly separated. Thereby, the content rate of the unburned carbon particles P2 (in other words, carbon content rate) in the solid content in the hydrophobic solvent phase ph2 can be increased. [0094] 　Next, in the water washing step (S22), water L1 is added to and mixed with the hydrophobic solvent phase ph2 separated in the rough separation step (S21). By allowing the mixed solution to stand, the specific gravity is separated into the hydrophobic solvent phase ph2 in which the unburned carbon particles P2 are concentrated as the solid content and the aqueous phase ph1 mainly containing the remaining oxide particles P1. By this water washing step (S22), the hydrophobic solvent phase ph2 containing unburned carbon particles P2 is washed with water L1, and the oxide particles P1 remaining in the rough separation step (S21) are separated from the unburned carbon particles P2. Can be removed. Therefore, the unburned carbon particles P2 contained in the hydrophobic solvent phase ph2 can be concentrated to further increase the content rate (carbon content rate) of the unburned carbon particles P2 in the solid content in the hydrophobic solvent phase ph2. .. [0095] 　The water washing step (S22) may be carried out only once, but by carrying out a plurality of times (for example, 2 to 4 times), the unburned carbon particles P2 contained in the solid matter in the hydrophobic solvent phase ph2 are contained. The rate (in other words, the carbon content rate) can be further increased. In the specific gravity separation step (S2), the water washing step (S22) is not essential and only the rough separation step (S21) may be performed. Even in this case, the unburned carbon particles P2 and the oxide particles P1 can be separated to some extent, and it is possible to obtain the hydrophobic solvent phase ph2 having a high content rate of the unburned carbon particles P2. [0096] 　Next, in the solid-liquid separation step (S41) of the recovery step (S4), the hydrophobic solvent phase ph2 separated in the specific gravity separation step (S2) is subjected to a liquid fraction by a solid-liquid separation treatment such as filtration or centrifugation. The hydrophobic solvent L2 is separated into solid particles (mainly unburned carbon particles P2 and remaining oxide particles P1), and the hydrophobic solvent L2 is removed from the solid particles. As a result, the cake C2 mainly composed of solid particles such as unburned carbon particles P2 is recovered. [0097] 　Then, in the drying step (S42), the hydrophobic solvent L2 remaining in the cake C2 is volatilized by heating the cake C2. As a result, the carbon-containing powder P0 (carbon content: 50% by mass or more) mainly containing the unburned carbon particles P2 is recovered. [0098] 　Here, the boiling point of the hydrophobic solvent L2 is preferably less than 200° C. under atmospheric pressure, and more preferably less than 100° C. Thereby, in the drying step (S42), when the cake C2 mainly composed of the unburned carbon particles P2 is dried to volatilize and remove the hydrophobic solvent L2, an inexpensive heat source (for example, steam) as a heating source. Can be used. [0099] 　As described above, according to the separation/collection step of the method for producing carbon-containing powder according to the present embodiment, the carbon-containing powder P0 mainly composed of the unburned carbon particles P2 is separated and collected from the fly ash FA to obtain the carbon. It is possible to obtain the carbon-containing powder P0 having a content of 50% by mass or more. [0100] [4. Configuration of Separation/Recovery Apparatus] 　Next, with reference to FIG. 6, the configuration and operation of the separation/recovery apparatus 5 for executing the separation/recovery step according to the present embodiment will be described in detail. FIG. 6 is a schematic diagram showing the separation/collection device 5 according to the present embodiment. The specific gravity of the hydrophobic solvent L2 used is more than 1.05. [0101] 　As shown in FIG. 6, the separation/collection device 5 according to the present embodiment includes two sets of mixing devices (mixers 51A and 51B) and separation devices (settlers 52A and 52B) that execute the specific gravity separation step (S2). The 1st recovery device 61 and the 2nd recovery device 62 which performs the above-mentioned recovery process (S4) are provided. [0102] 　(1) Coarse Separation Step (S21) 　Using Mixing Device and Separation Device In the coarse separation step (S21) of the specific gravity separation step (S2), fly ash FA is mixed with a mixed solution of water L1 and hydrophobic solvent L2. And let stand. Thereby, the mixed liquid is phase-separated into the aqueous phase ph1 and the hydrophobic solvent phase ph2, the hydrophilic oxide particles P1 are moved to the aqueous phase ph1, and the hydrophobic unburned carbon particles P2 are transferred to the hydrophobic solvent phase. By moving it to ph2, the oxide particles P1 and the unburned carbon particles P2 are roughly separated. The rough separation step (S21) includes a mixing step by the mixing device (mixer 51A) and a specific gravity separation step by the separating device (settler 52A). [0103] 　In the mixing step, the fly ash FA in which the oxide particles P1 and the unburned carbon particles P2 are mixed is mixed with the water L1 and the hydrophobic solvent L2, and the mixed solution is stirred to be slurried to generate the first slurry. As a mixing device for executing this mixing step, for example, a container equipped with a stirring blade for stirring the mixed liquid, a line mixer, or a pump capable of stirring the mixed liquid inside can be used. [0104] 　The mixer 51A in the example of FIG. 6 is a stirrer having a motor 511A and a stirring blade 512A. The mixer 51A is connected to the settler 52A in the subsequent stage via a pipe 80A. Fly ash FA, which is a mixture to be separated, water L1, and a hydrophobic solvent L2 having a larger specific gravity than water L1 are put into the container of the mixer 51A. The mixer 51A mixes the fly ash FA, water L1, and the hydrophobic solvent L2 by rotating the stirring blade 512A by the motor 511A, and the first slurry (oxide particles P1, unburned carbon particles P2, and water L1). And a hydrophobic solvent L2) are produced (mixing step). [0105] 　The settler 52A is an example of a separation device that executes a specific gravity separation process. The settler 52A uses the difference in specific gravity between the water L1 and the hydrophobic solvent L2 by allowing the first slurry produced in the above mixing step to stand still, and the aqueous phase ph1 mainly containing the oxide particles P1 and the unburned state. The hydrophobic solvent phase ph2 mainly containing the carbon particles P2 is separated. [0106] 　The settler 52A is an example of a specific gravity separation device that allows a mixed liquid of a plurality of types of liquid to stand still and separates the liquid using a specific gravity difference, and is connected to the mixer 51A via a pipe 80A. .. Further, the settler 52A is connected to the first recovery device 61 in the subsequent stage via a pipe 81A. The pipe 81A is provided with a pump 71A for delivering the aqueous phase ph1 (second slurry) containing the oxide particles P1. Further, the settler 52A is connected to the mixer 51B in the subsequent stage via a pipe 82A, and a pump 72A for delivering the solvent phase ph2 (third slurry) containing unburned carbon particles P2 is connected to the pipe 82A. It is provided. [0107] 　The settler 52A utilizes the difference in specific gravities of the first slurry introduced from the mixer 51A through the pipe 80A to make use of the difference in specific gravity between the upper phase aqueous phase ph1 and the lower hydrophobic solvent phase ph2 (hereinafter referred to as “solvent phase ph2”). In some cases, the oxide particles P1 are moved to the aqueous phase ph1 and the unburned carbon particles P2 are moved to the solvent phase ph2. As a result, the oxide particles P1 and the unburned carbon particles P2 are separated. Then, the aqueous phase ph1 (second slurry) containing the oxide particles P1 is discharged from the upper part of the settler 52A to the first recovery device 61 through the pipe 81A. On the other hand, the solvent phase ph2 (third slurry) containing unburned carbon particles P2 is discharged from the lower part of the settler 52A to the mixer 51B through the pipe 82A. The third slurry mainly contains unburned carbon particles P2 as a solid content, but also contains oxide particles P1 that could not be separated. [0108] 　(2) Water Washing Step (S22) by Mixing Device and Separating Device In the water washing step (S22) of the 　specific gravity separating step (S2), the solvent phase ph2 (third slurry) recovered in the rough separating step (S21). Water L1 is added to and mixed with, and then allowed to stand. As a result, the mixed liquid is phase-separated into the aqueous phase ph1 and the hydrophobic solvent phase ph2, the oxide particles P1 remaining in the third slurry are moved to the aqueous phase ph1, and the unburned carbon particles P2 are removed. Concentrate to solvent phase ph2. As a result, the content ratio of the unburned carbon particles P2 in the solid matter contained in the solvent phase ph2 can be increased. [0109] 　The water washing step (S22) includes a mixing step by the mixing device (mixer 51B) and a specific gravity separation step by the separating device (settler 52B). As the mixer 51B, an apparatus having the same configuration as the mixer 51A described above can be used. As the settler 52B, an apparatus having the same configuration as the settler 52A described above can be used. [0110] 　The solvent phase ph2 (third slurry) supplied from the settler 52A is put into the container of the mixer 51B. The mixer 51B rotates the stirring blade 512B by the motor 511B to mix the third slurry and the water L1, and the fourth slurry (unburned carbon particles P2, the remaining oxide particles P1, and the water L1). , A mixed solution of the hydrophobic solvent L2) (mixing step). [0111] 　The settler 52B is connected to the mixer 51B via a pipe 80B. Further, the settler 52B is connected to the first recovery device 61 at the subsequent stage via a pipe 81B. The pipe 81B is provided with a pump 71B for delivering the aqueous phase ph1 (fifth slurry) containing the oxide particles P1. Further, the settler 52B is connected to the second recovery device 62 in the subsequent stage via a pipe 82B. The pipe 82B is provided with a pump 72B for delivering the solvent phase ph2 (sixth slurry) containing unburned carbon particles P2. [0112] 　The settler 52B is condensed with the aqueous phase ph1 mainly containing the oxide particles P1 by utilizing the difference in specific gravity between the water L1 and the hydrophobic solvent L2 by allowing the fourth slurry generated by the mixer 51B to stand. Separated into the solvent phase ph2 containing the unburned carbon particles P2. Then, the aqueous phase ph1 (fifth slurry) containing the oxide particles P1 is discharged from the upper portion of the settler 52B to the first recovery device 61 through the pipe 81B. On the other hand, the solvent phase ph2 (sixth slurry) containing unburned carbon particles P2 is discharged from the lower portion of the settler 52B to the second recovery device 62 through the pipe 82B. [0113] 　(3) First recovery process (S3) by 　the first recovery device The first recovery device 61 extracts from the aqueous phase ph1 containing the oxide particles P1 separated by the rough separation process (S21) and the water washing process (S22). , The water L1 is separated, and the oxide particles P1 are recovered. The first recovery device 61 includes a centrifuge 611, a drying device 612, and a condenser 613. [0114] 　The centrifuge 611 is an example of a solid-liquid separator, and uses centrifugal force to separate a solid suspended in a liquid from a liquid. The centrifuge 611 is connected to the post-stage drying device 612 via a pipe 832, and is connected to the pre-stage mixers 51A and 51B via a pipe 831. The aqueous phase ph1 (second slurry, fifth slurry) containing the oxide particles P1 is introduced into the centrifuge 611 from the settler 52A, 52B. The centrifuge 611 uses centrifugal force to separate the slurry into a cake C1 containing the oxide particles P1 and water L1 (solid-liquid separation step). The oxide particles P1 dehydrated by the centrifuge 611 are discharged to the drying device 612 through the pipe 832. On the other hand, the water L1 separated by the centrifuge 611 is returned to the mixers 51A and 51B through the pipe 831 and reused in the rough separation step (S21) and the water washing step (S22). [0115] 　In the present embodiment, in order to perform solid-liquid separation of the slurry into water L1 and oxide particles P1, a centrifuge treatment by a centrifuge 611 is used, but instead of this, a solid matter such as a filter press or distillation or filtration is used. A liquid separation method may be used. However, when the hydrophobic solvent L2 has volatility, it is preferable to use, for example, a distillation apparatus, a centrifugal separation apparatus, or a filtration apparatus as the solid-liquid separation apparatus in order to reduce the leakage of the volatilized solvent gas. [0116] 　The drying device 612 heats the cake C1 containing the oxide particles P1 introduced from the centrifugal separator 611 to evaporate the remaining water. Thereby, the oxide particles P1 are dried (drying step). The dried oxide particles P1 are discharged from the pipe 833 and collected. The condenser 613 condenses the water vapor sent from the drying device 612 through the pipe 834 and returns it to the liquid water L1 (condensing step). The liquid water L1 generated in the condenser 613 is returned to the mixer 51 through the pipe 835 and reused in the rough separation step (S21) and the water washing step (S22). [0117] 　As described above, in the separation/recovery method according to the present embodiment, in the first recovery step (S3), the aqueous phase ph1 (second and fifth) containing the oxide particles P1 separated in the specific gravity separation step (S2). The slurry) is separated into oxide particles P1 and water L1 by a centrifugal separator 611. After that, the oxide particles P1 are dried by the drying device 612, and the dry powder oxide particles P1 are collected. However, the first recovery step (S3) is not limited to this example, and for the aqueous phase ph1 (second and fifth slurries) containing the oxide particles P1 separated by the specific gravity separation step (S2), The oxide particles P1 in the water slurry state may be recovered as they are without performing the solid-liquid separation step and the drying step. Whether to recover the oxide particles P1 in a dry powder state, a cake state, or a water slurry state can be appropriately selected according to the recycling application of the oxide particles P1 and the like. [0118] 　In the first recovery step (S3), the boiling point of the hydrophobic solvent L2 or more is higher than that of the aqueous phase ph1 (second and fifth slurries) containing the oxide particles P1 separated in the specific gravity separation step (S2). It is preferable to evaporate and remove the hydrophobic solvent L2 remaining in the aqueous phase ph1 by heating to the temperature of 1 or reducing the pressure to a pressure at which the hydrophobic solvent L2 evaporates. Thereby, it is possible to prevent the recovered oxide particles P1 from containing the hydrophobic solvent L2 and improve the quality of the oxide particles P1. In the separation/collection device 5 according to the present embodiment, in the drying process by the drying device 612 shown in FIG. 6, the hydrophobic solvent L2 is heated and evaporated together with the water L1, so that it remains in the second and fifth slurries. The hydrophobic solvent L2 present can be removed. When the hydrophobic solvent L2 has volatility, it can be evaporated at room temperature, but since the specific gravity of the hydrophobic solvent L2 is larger than that of water L1, the hydrophobic solvent L2 should not come into direct contact with the gas phase. There are many. Therefore, it is preferable to perform stirring or aeration, and at this time, it is desirable to take measures to prevent the volatilized solvent L2 from scattering. [0119] 　When the hydrophobic solvent L2 is heated and evaporated, when the recovered oxide particles P1 are in a cake form, the boiling point of the hydrophobic solvent L2 is preferably 150° C. or lower under atmospheric pressure. Thereby, the hydrophobic solvent L2 can be evaporated and removed at low cost. When the recovered oxide particles P1 are in a slurry state, the boiling point of the hydrophobic solvent L2 is preferably 95° C. or lower under atmospheric pressure. As a result, the evaporation of the water L1 can be suppressed, so that the hydrophobic solvent L2 can be easily evaporated and removed with a small amount of heat. The boiling point of the hydrophobic solvent L2 is preferably 40° C. or higher under atmospheric pressure. As a result, the volatilization amount of the hydrophobic solvent L2 at room temperature and atmospheric pressure can be suppressed, so that recovery and handling can be facilitated. [0120] 　(4) Second recovery process by second recovery device (S4) 　The second recovery device 62 includes a hydrophobic solvent phase ph2 (sixth slurry) containing unburned carbon particles P2 separated by the specific gravity separation process (S2). Then, the hydrophobic solvent L2 is separated and removed to recover the carbon-containing powder P0 mainly composed of the unburned carbon particles P2 (S4). The second recovery device 62 includes a centrifuge 621, a drying device 622, and a condenser 623. [0121] 　The centrifuge 621 is connected to the drying device 622 in the subsequent stage via a pipe 842, and is connected to the mixer 51A in the previous stage via a pipe 841. The hydrophobic solvent phase ph2 (sixth slurry) containing the unburned carbon particles P2 is introduced into the centrifuge 621 from the settler 52B. The centrifuge 621 uses centrifugal force to separate the sixth slurry into a cake C2 mainly composed of unburned carbon particles P2 and a hydrophobic solvent L2 (solid-liquid separation step (S41)). The unburned carbon particles P2 from which the hydrophobic solvent L2 has been separated by the centrifugal separator 621 are discharged to the drying device 622 through the pipe 842. On the other hand, the hydrophobic solvent L2 separated by the centrifuge 621 is returned to the mixer 51A through the pipe 841 and reused in the rough separation step (S21). In addition, in the present embodiment, in order to perform solid-liquid separation of the sixth slurry into the hydrophobic solvent L2 and the unburned carbon particles P2, a centrifugal separation process by the centrifugal separator 621 is used, but instead of this, a filter press or distillation is used. Alternatively, a solid-liquid separation method such as filtration may be used. [0122] 　The drying device 622 heats the cake C2 containing the unburned carbon particles P2 introduced from the centrifugal separator 621 to volatilize the remaining hydrophobic solvent component. Thereby, the solid content mainly composed of the unburned carbon particles P2 is dried to obtain the carbon-containing powder P0 (drying step (S42)). The carbon-containing powder P0 mainly composed of the dried unburned carbon particles P2 is discharged from the pipe 843 and collected. The condenser 623 condenses the vapor of the hydrophobic solvent L2 sent from the drying device 622 through the pipe 844 and returns it to the liquid hydrophobic solvent L2 (condensing step). The liquid hydrophobic solvent L2 generated in the condenser 623 is returned to the mixer 51A through the pipe 845 and reused in the rough separation step (S21) (second recycling step). [0123] 　As described above, in the separation recovery method according to the present embodiment, the solvent phase ph2 (sixth slurry) containing the unburned carbon particles P2 separated in the specific gravity separation step (S2) in the second recovery step (S4). Is separated into a cake C2 containing unburned carbon particles P2 and a hydrophobic solvent L2 by a centrifugal separator 621. After that, the cake C2 is dried by the drying device 622, and the carbon-containing powder P0 mainly composed of the dry powder unburned carbon particles P2 is collected. [0124] 　The configuration of the separation/recovery device 5 according to the present embodiment and the method for separating/recovering the carbon-containing powder P0 using the same have been described above. In this embodiment, since the method is performed in a single-stage continuous process, the specific gravity separation step (S2), the first recovery step (S3), and the second recovery step (S4) are simultaneously performed in parallel. Thereby, the separation efficiency and productivity of the oxide particles P1 and the unburned carbon particles P2 can be improved. [0125] 　Further, the water L1 separated from the oxide particles P1 in the first recovery step (S3) is recovered and reused as the water L1 input in the specific gravity separation step (S2), and the second recovery step (S4). ), the hydrophobic solvent L2 separated from the unburned carbon particles P2 is recovered and reused as the hydrophobic solvent L2 added in the specific gravity separation step (S2). Thereby, it is not necessary to dispose of the water L1 and the hydrophobic solvent L2, so that the raw material cost and the disposal cost of the hydrophobic solvent L2 can be reduced. Further, a large amount of the hydrophobic solvent L2 can be repeatedly used in the specific gravity separation step (S2), and the chances that the unburned carbon particles P2 come into contact with the hydrophobic solvent L2 can be increased. In the coarse separation step (S21) and the water washing step (S22) of the specific gravity separation step (S2), the unburned carbon particles P2 of the fly ash FA are taken into the hydrophobic solvent phase ph2, and the oxide particles P1 are separated into the aqueous phase. By incorporating into ph1, oxide particles P1 and unburned carbon particles P2 can be separated with high efficiency. [0126] 　Therefore, the separation and recovery method in the method for producing carbon-containing powder according to the present embodiment has a higher separation speed and separation efficiency for oxide particles and unburned carbon particles than the conventional flotation method described in Patent Document 1. It can be greatly improved. For example, the coarse separation step (S21) according to the present embodiment can quickly separate the oxide particles P1 and the unburned carbon particles P2 in a short time of, for example, about 1 to 30 seconds. Further, the content ratio of the unburned carbon particles P2 mixed in the separated and collected oxide particles P1 can be reduced to 3% by mass or less, and the oxide particles P1 with high purity can be collected. Similarly, the content of the oxide particles P1 mixed in the separated and recovered carbon-containing powder P0 can be reduced to less than 50% by mass, preferably 30% by mass or less. Therefore, the content ratio of the unburned carbon particles P2 contained in the carbon-containing powder P0 can be increased to 50% by mass or more, so that the carbon-containing powder P0 having a high carbon content and a low N/C ratio can be recovered. [0127] 　[4.1. Preferred Conditions for Specific Gravity Separation] 　Next, preferred conditions for specific gravity separation in the separation method according to the present embodiment will be described in detail. First, a preferable range of the specific gravity (liquid specific gravity) of the hydrophobic solvent used in the separation method according to this embodiment will be described. [0128] 　During the standing in the rough separation step (S21) or the water washing step (S22), the oxide particles and the unburned carbon particles may be concentrated near the interface between the aqueous phase and the hydrophobic solvent phase. For example, a mixture of trichloroethylene (specific gravity: 1.46) as a hydrophobic solvent and water (specific gravity: 1) is mainly mixed with oxide particles (specific gravity: 2.4 to 2.6) as hydrophilic particles. The mixture (for example, fly ash) is added, and the mixture is allowed to stand for about 30 seconds or longer. The oxide particles settle in the aqueous phase, while the unburned carbon particles (specific gravity: 1.3 to 1.5) float in the trichlorethylene phase. As a result, near the interface between the water phase and the trichlorethylene phase, the oxide particles and the unburned carbon particles are concentrated, and the specific gravity gradually approaches. Since the oxide particles and the unburned carbon particles are mixed near the interface, the separability between the two may deteriorate. Therefore, in order to prevent the separability of the oxide particles and the unburned carbon particles from deteriorating, it is preferable to separate the aqueous phase and the hydrophobic solvent phase in a short time after standing, and further, in the vicinity of the interface between both phases. It may be preferable not to collect. [0129] 　It is preferable to select a hydrophobic solvent having a higher specific gravity as the specific gravity of the oxide particles is higher. This can prevent the oxide particles from settling from the aqueous phase into the solvent phase. When the specific gravity of the oxide particles is small, it is not necessary to intentionally select a hydrophobic solvent having a small specific gravity, and the range of applicable specific gravity of the hydrophobic solvent can be expanded. [0130] 　The aqueous phase (i.e. a slurry of water and oxide particles) the mass ratio of the oxide particles contained in, the aqueous phase slurry concentration C S and [mass%]. The slurry concentration C S is represented by the following equation (2). A value obtained by dividing the apparent density ρ S [g/cm 3 ] of the aqueous phase by the density ρ w [g/cm 3 ] of water at the same temperature and the same pressure is defined as the slurry specific gravity d S of the aqueous phase . The slurry specific gravity d S is represented by the following formula (3). [0131] 　C S =m P /(m P +m W )...(2) 　d S =ρ S /ρ w =(m P +m W )/(V P +V W )/ρ w　...(3) 　　m P [g]: weight of the oxide particles contained in the aqueous phase 　　m W [g]: weight of water contained in the aqueous phase 　　V P [cm 3 ]: volume of the oxide particles contained in the aqueous phase 　　V W [cm 3 ]: Volume of water contained in the water phase 　　ρ S [g/cm 3 ]: Apparent density of slurry of water and oxide particles in water phase 　　ρ w [g/cm 3 ]: Density of water at the same temperature and the same pressure [0132] 　If the slurry specific gravity of the aqueous phase is less than the specific gravity of the hydrophobic solvent, the aqueous phase is less likely to settle in the solvent phase, and it can be said that it is advantageous for suitably performing phase separation between the aqueous phase and the solvent phase. Therefore, it is preferable to adjust the mixing ratio of the mixture (fly ash) and water in the mixing step or select a hydrophobic solvent having an appropriate specific gravity so that the sedimentation is suppressed. [0133] 　Further, the specific gravity of the hydrophobic solvent is more preferably more than 1.05. When the specific gravity of the hydrophobic solvent is 1.05 or less, in order to make the slurry specific gravity d S of the aqueous phase less than the specific gravity of the hydrophobic solvent as described above, the slurry concentration C S of the aqueous phase is set to a predetermined value or less. Need to lower. In this case, the size of the separation device may increase. On the other hand, by setting the specific gravity of the hydrophobic solvent to be more than 1.05, the slurry concentration C S of the aqueous phase can be increased to be higher than the above predetermined value, so that the separation treatment amount per unit time can be increased and Eliminates the need for separation equipment. [0134] 　Further, in the solvent phase, a thin (for example, about 5 to 20 μm) water film may be attached to the surface of the oxide particles that could not be attached to water droplets. The apparent specific gravity of the oxide particles coated with the water coating (hereinafter, also referred to as “water coating particles”) is smaller than the specific gravity of the oxide particles themselves. Therefore, it is preferable to select a hydrophobic solvent having a specific gravity larger than the apparent specific gravity of the water-coated particles. Thereby, in the separation step, the water-coated particles can be floated from the solvent phase to the water phase and retained in the water phase. Therefore, the oxide particles can be quickly and efficiently separated from the hydrophobic solvent and the unburned carbon particles. If it is difficult to directly measure the apparent specific gravity of the water-coated particles, for example, add 0.5 to 1 g of oxide particles to a mixed liquid consisting of 80 ml of water and 20 ml of a hydrophobic solvent in a measuring cylinder with a stopper, and oxidize at that time. It is preferable to select a hydrophobic solvent in which most of the product particles do not settle in the solvent phase. [0135] 　Further, the specific gravity of the hydrophobic solvent is preferably smaller than that of the unburned carbon particles. Thereby, in the second recovery step (S4), when the unburned carbon particles P2 are separated from the solvent phase ph2 (third slurry) by using the centrifugal separator 621, the deliquoring property is improved and the unburned carbon particles are improved. P2 can be separated efficiently. Even when "the specific gravity of the unburned carbon particles P2