TW201936490A - Carbon-containing powder, separation method, and use of carbon-containing powder - Google Patents

Abstract

To provide a novel and improved carbon-containing powder. A carbon-containing powder containing carbon particles P2 and oxide particles P1, wherein the content of a carbon component in the carbon-containing powder is 50 to 95% by mass inclusive, the oxide particles P1 are particles made from a compound containing a SiO2 component and/or a Al2O3 component, the total content of the SiO2 component and the Al2O3 component in the oxide particles P1 is 75% by mass or more, the carbon particles P2 are porous particles each having multiple pores P20 formed therein, at least a portion of the oxide particles P1 is present in the pores P20 in the carbon particles P2.

Description

Carbonaceous powder, separation method, and utilization method of carbonaceous powder

The present invention relates to a carbonaceous powder.

BACKGROUND ART Fly ash generated during power generation such as a coal-fired power plant is often reused for concrete raw materials, building materials, and cement raw materials. The fly ash includes ash composed of a metal oxide such as Al ₂ O ₃ or SiO ₂ and unburned carbon which is a carbon component remaining. Therefore, in order to be used as a building material raw material, a raw material for concrete (mixing agent), etc., it is preferable to separate unburned carbon contained in fly ash, and to reduce the unburned carbon concentration.

As a method of 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 fly ash is introduced into a parallel plate electrode in a dry state, and charged unburned carbon is attracted to the positive electrode side to separate it. Further, the flotation method is a method of using a micro-air generated by a bubble agent in a slurry of fly ash, and attaching unburned carbon particles by a scavenger such as kerosene to float unburned carbon particles. The method of separating it.

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, the fly ash which has been slurried by adding water is stirred, whereby active energy is generated on the surface of the unburned carbon particles, and the unburned carbon particles are oleophilized ( Hydrophobic). Next, a scavenger such as kerosene or gas oil and a foaming agent are added to the slurry containing the oleophilic unburned carbon to adhere the scavenger to the unburned carbon, and the unburned carbon is attached to the generated bubbles. For flotation. By the flotation method, unburned carbon can be separated from the unburned carbon (specific gravity: 1.3 to 1.5) of the hydrophobic particles and the metal oxide (specific gravity: 2.4 to 2.6) which is a hydrophilic particle, that is, unburned. carbon.

PRIOR ART DOCUMENT PATENT DOCUMENT Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-167825

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, when fly ash is reused, not only metal oxides such as Al ₂ O ₃ and SiO ₂ described above are used, but also unburned carbon is expected to be effectively utilized.

However, in the flotation method in which the unburned carbon contained in the fly ash is caused to adhere to the air 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. Therefore, since many fine particles of metal oxide remain in the separated unburned carbon, it is difficult to separate and recover only unburned carbon at a high carbon content. Further, in the dry state, the fine particles of the metal oxide such as SiO ₂ or Al ₂ O ₃ are likely to aggregate with other particles by the attraction force such as the wattage force or the electrostatic force, and therefore adhere to the unburned carbon particles. Therefore, it is more difficult to appropriately separate the fine particles of the unburned carbon particles and the metal oxide contained in the fly ash.

For the above reasons, it is difficult to separate the unburned carbon contained in the fly ash at a high carbon content by the conventional separation method. Therefore, in the past, the individual characteristics of unburned carbon obtained by separating and recovering fly ash have not been clearly explained, and this has become a major factor hindering the effective utilization of unburned carbon. Therefore, in the past, it has been desired to separate a carbonaceous powder such as unburned carbon having a high carbon content from coal ash such as fly ash, and to clearly explain its characteristics to effectively utilize the carbonaceous powder.

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a novel and improved carbonaceous powder, a separation method, and a method for utilizing a carbonaceous powder.

Means for Solving the Problems In order to solve the above problems, according to one aspect of the present invention, a carbonaceous powder containing carbon particles and oxide particles is provided;
The carbon component content in the carbon-containing powder is 50% by mass or more and 95% by mass or less.
Particles of the oxide particles by any component ₂ O ₃ or SiO _2, and Al composition of one or both of the compound composed of the oxide particles and the SiO ₂ component and the Al ₂ O ₃ component of The total content is 75 mass% or more: and the carbon particles are porous particles in which a plurality of pores are formed, and at least a part of the oxide particles are present in the pores of the carbon particles.

The content of the carbon component in the carbon-containing powder may be 70% by mass or more and 95% by mass or less.

The N/C ratio, which is a mass ratio of the nitrogen component contained in the carbon-containing powder to the carbon component, may be greater than 0 and not more than 0.02.

The particle diameter of the oxide particles may be 1 to 20 μm in terms of volume-based 50% particle diameter.

The average circularity of the oxide particles may be greater than 0.9 and not more than 1.

The content of the SiO ₂ component in the oxide particles may be 50% by mass or more and 80% by mass or less.
The content of the Al ₂ O ₃ component in the oxide particles may be 10% by mass or more and 30% by mass or less.

The carbonaceous powder may have a specific surface area of 50 to 300 m ² /g.

Further, in order to solve the above problems, according to another aspect of the present invention, there is provided a separation method for separating carbon particles and oxide particles from a mixture, and the mixture is derived from fly ash and mixed with carbon particles and Oxide particles;
The method includes the following steps:
a mixing step of mixing the mixture, water, and a hydrophobic liquid having a specific gravity larger than the water to form a mixed liquid; and a specific gravity separation step of allowing the mixed liquid to be separated into a hydrophobic liquid phase containing the carbon particles, The carbon particles and the oxide particles are separated from the aqueous phase containing the oxide particles.

Further, it may further include a first recovery step of separating the water from the water phase separated in the specific gravity separation step, thereby recovering the oxide particles.

Further, it may further comprise a second recovery step of separating the hydrophobic liquid from the hydrophobic liquid phase which has been separated in the specific gravity separation step, thereby recovering the carbonaceous powder,
The carbonaceous powder contains the carbon particles and the oxide particles.
The carbon component content in the carbon-containing powder is 50% by mass or more and 95% by mass or less.
Particles of the oxide particles by any component ₂ O ₃ or SiO _2, and Al composition of one or both of the compound composed of the oxide particles and the SiO ₂ component and the Al ₂ O ₃ component of The total content is 75 mass% or more, and the carbon particles are porous particles in which a plurality of pores are formed, and at least a part of the oxide particles are present in the pores of the carbon particles.

The N/C ratio, which is a mass ratio of the nitrogen component contained in the carbon-containing powder to the carbon component, may be 0.02 or less.

The combination of the foregoing mixing step and the aforementioned specific gravity separating step may also be repeated in multiple stages by a countercurrent multi-stage continuous process.

Moreover, it may be further included in the pulverization step.
The pulverizing step is performed by pulverizing a mixture of either or both of the hydrophobic liquid or the water and the mixture before the specific gravity separation step or in the specific gravity separation step, thereby pulverizing the mixed liquid Carbon particles.

In the pulverization step, the carbon particles contained in the mixed liquid may be pulverized by using a pulverization treatment with beads.

The fly ash can also be produced by burning coal.
The carbon particles may be particles of unburned carbon remaining in the combustion, and the oxide particles may be particles in which the ash of the coal carbon is melted into particles during the combustion.

The step of separating the specific gravity may also include the following steps:
The crude separation step is carried out by allowing the mixed liquid to be separated into a hydrophobic liquid phase containing the carbon particles and an aqueous phase containing the oxide particles; and a water washing step, which is already separated in the foregoing coarse After the water-repellent liquid phase separated in the step is mixed with water, the liquid mixture of the hydrophobic liquid phase and water is allowed to stand, thereby separating the hydrophobic liquid phase containing the carbon particles and the oxide particles. water box.

Further, in order to solve the above problems, according to another aspect of the present invention, a method for using a carbon-containing powder is provided.
The carbonaceous powder is used in place of the coal used in the sintering machine, the furnace or the converter, or as an SO ₂ adsorbent or a denitration material.

The carbonaceous powder may be mixed with other powders to increase the volume specific gravity of the carbonaceous powder.

Advantageous Effects of Invention As described above, according to the present invention, a novel and improved carbonaceous powder, a separation method, and a method for utilizing a carbonaceous powder can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION 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, the same reference numerals are given to the components that have substantially the same functional structure, and the repeated description is omitted.

[1. Background and Summary of the Invention]
First, the outline of the background of the present invention and the carbon-containing powder and the method for producing the same according to the embodiment of the present invention will be described.

As described above, fly ash is one type of coal ash which is produced by burning coal, and for example, fly ash is generated by burning fuel coal in a boiler of a power plant or the like. As fuel coal in power plants, mainly bituminous or sub-bituminous coal is used.

The fly ash contains a metal oxide (ash) composed of a compound containing an Al ₂ O ₃ component, a SiO ₂ component, or the like, and contains unburned carbon (carbon component) which is a carbon component remaining. The carbon content (carbon component content) in the fly ash is 1.5 to 15% by mass, and the metal oxide content of the SiO ₂ component and the Al ₂ O ₃ component is 75 to 98% by mass.

In a coal-carbon combustion process such as a power plant, oxides such as SiO ₂ component and Al ₂ O ₃ component in the fuel coal are temporarily melted. Therefore, in the fly ash after combustion, the oxide has a small surface unevenness. The form of spherical particles exists. The near-spherical shape referred to herein is not limited to a true spherical shape, and is preferably included in a shape such as an ellipsoidal shape or a polygonal spherical shape as long as the surface unevenness is small and substantially approximates the shape of the ball. The particle diameter of the oxide particles is approximately 200 μm or less in diameter, and most of them also contain 5 to 10% by mass of oxide particles having a diameter of less than 1 μm. Unlike the porous particles such as unburned carbon particles described later, the oxide particles are almost all spherical solid particles, and fine pores are not formed in the surface layer of the oxide particles. As described above, the fly ash is rich in nearly spherical solid oxide particles, so that the specific surface area of the fly ash becomes 0.5 to 10 m ² /g. Moreover, the particle size of the fly ash is about 1 to 200 μm.

On the other hand, when coke is produced from bituminous coal or sub-bituminous coal, bituminous coal and sub-bituminous coal are subjected to dry distillation treatment in a coke oven or the like. In the carbonization treatment, it is known that the specific surface area of the dry distillation product is increased by the voids generated when the volatile components are lost by heating (Non-Patent Document 1).
Non-Patent Document 1: Hashimoto and three other people, “Identification of Coal and Coke”, Report of the Central Bureau of Tariffs of the Ministry of Finance of Japan, Vol.49 pp.69-76, March 19, 2011

However, coal is in a combustion state in a power plant boiler, and is different from the dry distillation state in the above coke oven. Therefore, it has not been known in the past whether or not the surface of unburned carbon particles in the fly ash is gradually activated. Further, in the dry state, the smaller the particle diameter of the fine oxide particles, the easier it is to aggregate with other particles by the gravitational force such as van der Waals force or electrostatic force, and the content of unburned carbon particles in the fly ash is small. Therefore, a large number of oxide particles adhere to the surface of the unburned carbon particles. Therefore, the individual characteristics of the unburned carbon particles remaining in the boiler internal combustion cannot be clearly explained.

Further, even if pores of the surface layer of the unburned carbon particles are activated by activation, the fine oxide particles enter the pores and adhere due to gravity such as van der Waals force or electrostatic force. Therefore, it is difficult to remove the oxide particles from the pores of the unburned carbon particles, so it is more difficult to clearly explain the individual characteristics of the unburned carbon particles.

Under the circumstances as described above, the inventors have found a method in which unburned carbon particles in fly ash are appropriately separated from oxide particles by a special wet separation method, and unburned carbon particles can be produced. The carbonaceous powder was investigated, and various new features were discovered by investigating and analyzing the characteristics of the carbonaceous powder produced by the method.

Specifically, first, it is understood that in the boiler of a power plant or the like, the nitrogen content of the fly ash (coal ash) after combustion is low, and the N/C ratio of the fly ash is 0.02 or less. Further, the fly ash contains unburned carbon particles (carbon component) and oxide particles (ash) composed of a compound containing SiO ₂ component and Al ₂ O ₃ component, and is as shown in FIG. 1A and FIG. 1B (hereinafter, collectively As shown in FIG. 1), it is understood 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. Further, it is understood that the oxide particles P1 are solid particles that are nearly spherical, and may adhere to the surface of the unburned carbon particles P2, and may enter and exist in a plurality of pores P20 formed on the surface layer of the unburned carbon particles P2. internal.

Then, 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 as shown in FIG. 1, the method for producing the carbon-containing powder of the present embodiment In the special wet separation method as follows.

First, a mixed liquid obtained by mixing and stirring water, a hydrophobic liquid (for example, a hydrophobic organic solvent) and fly ash is allowed to stand, thereby separating into a hydrophobic liquid phase containing unburned carbon particles P2, and containing oxidation. The aqueous phase of the particle P1 (specific gravity separation step). Next, the hydrophobic liquid is separated from the hydrophobic liquid phase, whereby the cake containing the unburned carbon particles P2 is recovered (solid-liquid separation step). Thereafter, the cake is heated to volatilize the hydrophobic liquid, thereby recovering the carbonaceous powder from which the unburned carbon particles P2 are concentrated.

According to this production method, the unburned carbon particles P2 can be separated and concentrated from the fly ash, and a carbon-containing powder having a high carbon content (carbon content: 50% by mass or more) can be obtained. According to this separation method, as shown in FIG. 2A and FIG. 2B (hereinafter, collectively referred to as FIG. 2), the fine oxide particles P1 which enter the pores P20 of the unburned carbon particles P2 are not removed, but are separable and Almost all of the oxide particles P1 adhering to the surface of the unburned carbon particles P2 are removed.

Further, it is preferred that the mixture of the water or the hydrophobic liquid and the fly ash is subjected to a pulverization treatment (pulverization step) in the preceding step or the subsequent step of the above-described specific gravity separation step. Further, examples of the pulverization method include pulverization treatment by ultrasonic waves, pulverization treatment by a high-speed shear mixer, and pulverization treatment by a ball mill or a bead mill. Further, the hydrophobic liquid used in the pulverization step may be the same as or different from the hydrophobic liquid L2 used in the specific gravity separation step.

By the pulverization treatment, as shown in FIG. 3A and FIG. 3B (hereinafter, collectively referred to as FIG. 3), the unburned carbon particles P2 in the fly ash are pulverized, and are divided into a plurality of pieces by the fracture surface P21, and are miniaturized. . Thereby, the nearly spherical oxide particles P1 which have entered the pores P20 in the vicinity of the fracture surface P21 are released from the pores P20. Therefore, not only the oxide particles P1 adhering to the surface of the unburned carbon particles P2 but also the oxide particles P1 which have entered the pores P20 are separated and removed by the unburned carbon particles P2, so that they can be separated more appropriately. Unburned carbon particles P2 and oxide particles P1. Thereby, the carbon powder having a higher carbon content (carbon content: 70% by mass or more) can be obtained by pulverizing the fly ash.

[2. Structure of carbon-containing powder]
Next, the structure of the carbonaceous powder, which is mainly composed of the unburned carbon particles separated and recovered from the fly ash of the present embodiment, will be described in detail.

[2.1. Characteristics of carbonaceous powder]
In the investigation and analysis of the components and physical property values of the carbonaceous powder (carbon content: 50% by mass or more) obtained from the fly ash by the above-described production method, it is understood that the carbonaceous powder has the following characteristics. Hereinafter, the characteristics of the carbon-containing powder of the present embodiment will be described with reference to Table 1 in comparison with the conventional carbonaceous material.

[Table 1]

(1) N/C ratio
The N/C ratio is the mass ratio of the amount of nitrogen (nitrogen content) to the amount of carbon component (carbon content) in a material, and can be calculated by dividing the nitrogen content by the carbon content. Since the carbon-containing powder of the present embodiment has a low nitrogen content and a high carbon content, the carbon-containing powder has an N/C ratio of more than 0 and 0.02 or less, and is, for example, in the range of 0.0065 to 0.0196. Although not shown in Table 1, the N/C ratio of anthracite, bituminous coal and sub-bituminous coal is, for example, 0.008 to 0.03, and is mostly greater than 0.02. The N/C ratio of the carbonaceous powder of the present embodiment corresponds to a lower region even in the N/C ratio of anthracite, bituminous coal and sub-bituminous coal. The unburned carbon contained in the original fly ash before the wet separation step of the present embodiment has an N/C ratio of 0.02 or less and a low nitrogen content. Therefore, the carbon-containing powder mainly composed of unburned carbon obtained by separation and recovery has an N/C ratio of 0.02 or less. Although detailed later, we believe that as the combustion temperature in the boiler of the power plant rises, the N/C ratio will decrease.

(2) Carbon content rate The carbon content rate C _A of the carbon powder recovered from the fly ash by wet separation is 50% by mass or more and 95% by mass or less by the production method of the present embodiment. In particular, the carbonaceous powder recovered by the production method including the above-described pulverization step has a carbon content C _A of 70% by mass or more and 95% by mass or less.

Therefore, the carbonaceous powder produced by the production method of the present embodiment has a carbon content C _A of 50% by mass or more, preferably 70% by mass or more, and a small N/C ratio. 0.02 or less. Therefore, the carbonaceous powder of the present embodiment can be used as a coal having a low nitrogen content (low nitrogen coal), and can be effectively utilized as a conventional low nitrogen coal used in a coal carbon processing facility such as a sintering machine, a power plant, and a converter. Alternative. In particular, in order to effectively utilize the low nitrogen coal used as a substitute in the sintering machine, the N/C ratio is preferably 0.015 or less. Therefore, according to the production method of the present embodiment, it is possible to recover and reuse the carbonaceous powder having the same high carbon content and low N/C ratio as the low nitrogen coal from the fly ash, which is industrially important and beneficial. .

(3) Specific surface area As shown in Fig. 2 and Fig. 3, the unburned carbon particles P2 contained in the carbonaceous powder of the present embodiment are porous particles in which a plurality of pores P20 are formed on the surface layer. Therefore, the specific surface area of the carbon-containing powder of the present embodiment is 50 to 300 m ² /g which is equivalent to that of the activated coke powder, and is larger than the specific surface area (0.5 to 10 m ² /g) of the fly ash before the separation treatment. Tens of times to hundreds of times.

(4) SO ₂ adsorption capacity and denitration ability As described above, the carbonaceous powder of the present embodiment has a specific surface area of 50 to 300 m ² /g, which is considerably large. Therefore, the carbon-containing powder of the present embodiment has SO ₂ adsorption ability and denitration ability, and can be effectively utilized as an SO ₂ adsorption material and a denitration material.

(5) Component of Oxide Particles The oxide particles P1 are particles composed of at least a compound containing either or both of an SiO ₂ component or an Al ₂ O ₃ component. In the fly ash, Si and Al are mainly contained in the form of a compound such as mullite (Al ₆ Si ₂ O ₁₃ ), quartz (SiO ₂ ), or 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 composed of the compound. Therefore, the carbonaceous powder separated from the fly ash also contains a part of the remaining oxide particles P1 composed of the compounds.

The carbonaceous powder of the present embodiment is a powder mainly composed of unburned carbon (carbon component), but also contains oxide particles P1 which cannot be completely separated by a specific gravity separation treatment which will be described later. The oxide particles P1 in the carbonaceous powder have a content of less than 50% by mass and 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 an SiO ₂ component and an Al ₂ O ₃ component, and may contain an oxide of another element. The content of the SiO ₂ component in the oxide particles P1 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 P1 is 10% by mass or more and 30% by mass. %the following. Further, it is preferable to use the "average content ratio" as the content ratio of the particles. The average content rate can be obtained by measuring the content ratio of the SiO ₂ component and the Al ₂ O ₃ component by using a sample of the plurality of oxide particles P1, and calculating the average of the plurality of measured values.

(6) Particle size, roundness, and presence of the oxide particles In the carbonaceous powder of the present embodiment, not only the unburned carbon particles P2 but also the oxide particles P1 are mixed. When the coal particles are burned by a boiler or the like as described above, the ash of the coal is melted by the heat of combustion, and then cooled into granular particles, and almost all of them are nearly spherical solid particles. 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 roundness of the oxide particles P1 is greater than 0.9 and is 1 or less. Here, the roundness of a particle is the ratio of the circumference of a circle equal to the projected image of the particle to the circumference of the projected image of the particle.

At least a part of the oxide particles P1 enter into a plurality of pores P20 which have been formed in the surface layer of the unburned carbon particles P2 and are present therein. The content of the oxide particles P1 remaining in the pores P20 and the oxide particles P1 outside the pores P20 in the inside of the carbonaceous powder after the oxide particles P1 are separated from the surface by the specific gravity separation treatment described later may be more than 5 % by mass and less than 50% by mass. As described above, the carbonaceous powder of the present embodiment has a unique structure in which a granular oxide (near spherical oxide particles P1) is mixed in the pores P20 of the porous unburned carbon particles P2, and the particles are mixed. The 50% particle diameter of the oxide is 1 to 20 μm, and the average value of the roundness is more than 0.9 and 1 or less. The carbonaceous powder having the above unique structure can be said to be a novel and useful low nitrogen coal powder which has not been known in the past.

[2.2. Measurement method]
Next, a method of measuring the above characteristics of the carbon-containing powder of the present embodiment will be described.

(1) Method for Measuring Specific Surface Area A flow type specific surface area measuring device (for example, FlowSorb II 2300 manufactured by Shimadzu Corporation) can be used to measure carbon powder containing porous unburned carbon particles by gas adsorption method. The specific surface area at the end (unit: m ² /g). In the gas adsorption method, a single gas adsorption amount and a specific surface area of a gas can be calculated by a BET equation using a mixed gas of cerium and nitrogen (volume ratio: 7:3).

(2) Method for measuring SO ₂ adsorption capacity 5 to 50 ml of carbonaceous powder (sample) was placed in a reaction vessel, the reaction vessel temperature was set to 100 ° C, and the sample gas was supplied for 3 hours. The composition of the sample gas can be set to SO ₂ : 2 vol%, H ₂ O: 10 vol%, and O ₂ : 6% by volume, and the remainder is nitrogen. After the sample gas is supplied to the gas, the carbon powder is heated to 400 ° C under a nitrogen stream, and the generated SO _{2 is} captured and quantified, whereby the SO ₂ adsorption capacity of the carbon powder can be determined (unit: mg-SO _{2 )} /g-carbon powder).

(3) Method for measuring denitration capacity In the reaction tank, 5 to 50 ml of carbonaceous powder (sample) is charged, and the sample gas is supplied to the reaction vessel at a reaction bath temperature of 150 ° C and SV 500 h ^-1 for 10 hours. . The composition of the sample gas can be set to NO: 200 ppm, NH ₃ : 200 ppm, O ₂ : 6 vol%, and H ₂ O: 10 vol%, and the remainder is nitrogen. After the sample gas is supplied to the gas, the NO concentration and the O ₂ concentration in the gas discharged from the reaction tank are measured, and the NO concentration reduction rate at the steady state is calculated, whereby the denitration rate (vol%) of the carbon powder can be calculated. .

(4) Method for measuring carbon content and nitrogen content The carbon content and nitrogen content of the carbonaceous powder of the present embodiment were measured in accordance with JIS M8819.

(5) Method for measuring sulfur content The sulfur content of the carbonaceous powder of the present embodiment was measured in accordance with JIS M8813.

(6) Method for Measuring Particle Size of Oxide Particles in Carbon-Containing Powder The carbon-containing powder of the present embodiment is placed in a crucible, and heated at 600 ° C for 2 hours in the presence of air to form a carbon component. combustion. Thereby, as the residue, a granular oxide (near spherical oxide particles P1) which is an intermediate particle contained in the carbon-containing powder can be obtained. Usually, the component mainly composed of carbon is burned at 600 ° C, but the granular oxide does not melt, so that the granular oxide can be recovered without changing the form. Next, the particle size distribution of the granular oxide is measured by a laser diffraction type particle size distribution measuring apparatus, whereby the volume-based 50% particle diameter (median diameter D50) can be calculated.

(7) Method for Measuring Roundness of Oxide Particles in Carbon-Containing Powder The roundness of the oxide particles P1 recovered in the above (6) can be analyzed by the particle image analyzer to analyze the captured oxide particles. The shape is obtained. For example, a suspension obtained by adding a dispersant aqueous solution to a sample of oxide particles and performing dispersion treatment by ultrasonic waves is prepared. The oxide particles in the suspension were imaged as a static image by a sheath flow method using a flow type particle image analyzer. The average of the roundness may be the average of the roundness of the predetermined number or more of oxide particles measured in the sample. The number of oxide particles used to calculate the above average value may be, for example, 10,000 or more.

(8) The content of the SiO ₂ component and the content ratio of the Al ₂ O ₃ component in the oxide particles. The content ratio of the SiO ₂ component in the nearly spherical oxide particles P1 recovered in the above (6) [% by mass] The content ratio [% by mass] of the Al ₂ O ₃ component in the nearly spherical oxide particles can be measured by a fluorescent X-ray analysis method.

The SiO ₂ content can be quantitatively analyzed by a glass bead method by a fluorescent X-ray analyzer (XRF). Specifically, after the measurement sample of the known SiO ₂ content rate is changed and the plurality of measurement samples are prepared, the fluorescent X-ray analysis device is used to measure the X-ray derived from Si of the prepared measurement sample. strength. Using the obtained X-ray intensity derived from Si and the SiO ₂ content, a calibration curve indicating the relationship between the SiO ₂ content and the fluorescence X-ray intensity was prepared in advance. Then, for the sample of the unknown SiO ₂ content of the eye, the intensity of the fluorescent X-ray derived from Si can be measured by a fluorescent X-ray analyzer, and the obtained fluorescent X-ray intensity and the calibration curve are used to specify SiO ₂ content. Thereby, the content rate of the SiO ₂ component in the oxide particle P1 can be calculated.

Further, the Al ₂ O ₃ content rate can be quantitatively analyzed by a glass bead method by a fluorescent X-ray analyzer (XRF). Specifically, the measurement sample of the known Al ₂ O ₃ content rate is changed, and a plurality of the measurement samples are prepared, and then the prepared measurement sample is measured by a fluorescent X-ray analyzer to be derived from Al. Light X-ray intensity. Using the obtained fluorescent X-ray intensity derived from Al and the Al ₂ O ₃ content, a calibration curve indicating the relationship between the Al ₂ O ₃ content ratio and the fluorescence X-ray intensity was prepared in advance. Then, for the sample of the unknown Al ₂ O ₃ content of the eye, the intensity of the fluorescent X-ray of Al ₂ O ₃ can be measured by a fluorescent X-ray analyzer, and the obtained fluorescent X-ray intensity and calibration curve can be used. To specify the Al ₂ O ₃ content. Thereby, the content rate c _Al of the Al ₂ O ₃ component in the oxide particles P1 can be calculated.

The content ratio c _Si [% by mass] of the SiO ₂ component in the oxide particles P1 obtained in the above manner and the content ratio c _Al [% by mass] of the Al ₂ O ₃ component in the oxide particles P1 are as follows. In the formula (1), the total content ratio c _T [% by mass] of the SiO ₂ component and the Al ₂ O ₃ component in the oxide particles P1 in the carbon-containing powder can be measured.
c _T = c _Si + c _Al・・・(1)

Further, when the content ratio of the above (4), (5), and (8) is measured, a plurality of samples may be used to measure a plurality of contents, and an average value thereof may be calculated, or only one sample may be used for measurement. Contain rate. From the viewpoint of measurement accuracy, it is preferable to use a plurality of samples to calculate the content ratio. The particle diameter of the above (6) and the roundness of (7) are also the same.

[2.3. Principle of Reduction of N/C Ratio of Carbon-Containing Powder]
Next, the reason why the nitrogen-containing ratio and the N/C ratio of the carbon-containing powder of the present embodiment are low will be described with reference to Fig. 4 . Fig. 4 is a flow chart showing an outline of a method for producing the carbon-containing powder P0 of the present embodiment.

As shown in Fig. 4, in the manufacturing method of the present embodiment, for example, fuel coal FC such as bituminous coal or sub-bituminous coal is burned in a boiler 4 or the like of a thermal power plant, and as a result of the combustion, fly ash FA belonging to coal ash is produced ( Burning step). The fly ash FA is introduced into the separation and recovery device 5 (described later in detail), and is separated into oxide particles P1 composed of a SiO ₂ component and an Al ₂ O ₃ component by the special wet separation method of the present embodiment. Ash (with ash), and unburned carbon particles P2 (carbon component), and recovered (separation and recovery step). Therefore, the carbon-containing powder P0 of the present embodiment is produced by the combustion step in the boiler 4 and the separation and recovery step in the separation and recovery device 5. Here, we consider that the reason why the nitrogen content of the carbon-containing powder P0 of the present embodiment is low is as described below, and is a coal combustion step in the boiler 4.

In general, in the carbon steel retorting step in a coke oven, various dry distillation gases are produced. According to Non-Patent Document 2, depending on the type of coal carbon, among the nitrogen-based gases (HCN, NH ₃ , N ₂ ) in the dry distillation gas, HCN and NH _{3 are} generated from about 300 ° C at 800 ° C. End left and right. On the other hand, it is known that N ₂ starts from about 600 ° C and continues to be generated at a high temperature of 800 ° C or higher which almost ends the generation of other nitrogen-based gas. Further, in general, carbon-based gases (CO, CH ₄ , HCN) are scarcely produced in the dry distillation gas. Based on these reasons, it is predicted that in the dry distillation of coal, as the dry distillation temperature in the coke oven rises, the N/C ratio of coal will decrease.
Non-Patent Document 2: Kawabe Kanehiro and two others, "Non-gas measurement by coal gas and XPS determination of carbon distribution in the carbonization process", Materials and Processes, Vol.25 No.2, Page.ROMBUNNO.36, September 1, 2012

On the other hand, in the combustion step of the manufacturing method of 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-carbon powder in the coke oven is relatively short, and the coal-carbon powder in the boiler 4 is not in a dry distillation state but in a burning state. 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 we believe that the portion is in a state close to the dry distillation state. Therefore, it is considered that, in the same manner as the above-described dry distillation step of the coal, in the combustion step in the boiler 4, the surface layer of the coal powder having a particle diameter of only about several mm at a high temperature of 800 ° C or higher. Part of the distillation is carried out, and the nitrogen compound contained in the surface layer portion is decomposed and gasified, so that the nitrogen component of the coal carbon powder is reduced. Therefore, it is considered that the nitrogen content of the unburned carbon particles P2 in the fly ash FA after the combustion step is lowered, so that the N/C ratio of the carbon powder P0 obtained by concentrating and recovering the unburned carbon particles is also lowered. In addition, we believe that as the combustion temperature in the boiler 4 rises, the N/C ratio of the carbonaceous powder P0 decreases.

[2.4. Characteristics of intermediate particles in carbon-containing powders]
Next, the relevant features of the nearly spherical oxide particles P1 as the intermediate particles contained in the carbon-containing powder of the present embodiment will be described in further detail with reference to FIG. 1 to FIG.

As shown in FIG. 1, the fly ash FA before the wet separation treatment contains a large amount of the nearly spherical oxide particles P1, and the oxide particles P1 enter the unburned carbon particles P2 as compared with the unburned carbon particles P2. In the pores P20, the oxide particles P1 cover the surface of the unburned carbon particles P2. Therefore, conventionally, the individual characteristics of the unburned carbon particles P2 are not clear.

Then, in the production method according to the first embodiment of the present invention to be described later, the unburned carbon particles P2 and the unburned carbon particles P2 are used by a wet separation treatment (see FIG. 5 described later) using water and a hydrophobic liquid without a pulverization treatment. The 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 can be removed, but it is difficult to remove the oxide particles P1 that have entered the pores P20 of the unburned carbon particles P2. The reason for this is that, in the above-described wet separation treatment, either or both of water or a hydrophobic liquid cannot enter the pores P20 of the unburned carbon particles P2, so that it is difficult to discharge from the pores P20. Oxide particles P1.

In this case, a case where the carbonaceous powder containing the unburned carbon particles P2 is used as the SO ₂ adsorbent can be considered. The pores P20 of the unburned carbon particles P2 blocked by the oxide particles P1 are counted in the specific surface area of the carbonaceous powder. However, since the oxide particles P1 are held in the pores P20 of the unburned carbon particles P2, almost no exhaust gas (normal pressure) containing SO ₂ or the like can enter the deep portion of the pores P20. Therefore, the pores P20 of the unburned carbon particles P2 are not effectively utilized as the adsorption surface of the SO ₂ , and there is still room for improvement as a function of the SO ₂ adsorbent.

Then, in the production method according to the second embodiment of the present invention to be described later, the wet separation treatment with the pulverization treatment of the unburned carbon particles P2 is performed (see FIGS. 7 to 10 which will be described later). By the pulverization treatment, as shown in FIG. 3, the fragile porous unburned carbon particles P2 are easily pulverized, and the plurality of pores P20 are connected to each other by the fracture surface P21, so that the unburned carbon particles P2 are easily fined. Chemical. When the unburned carbon particles P2 are pulverized, the nearly spherical oxide particles P1 in the pores P20 can easily come into contact with either or both of water or a hydrophobic liquid, and the majority of the oxide particles P1 can be fine. The hole P20 is discharged, and the unburned carbon particles P2 are separated. Thereby, the carbonaceous powder mainly composed of the unburned carbon particles P2 from which the oxide particles P1 have been separated can be obtained. In the carbon-containing powder, as the carbon content increases, the surface area of the carbon component as the adsorption surface of SO ₂ also increases. Therefore, the treatment ability of the SO ₂ -containing gas containing the carbon powder is increased, and the function as the SO ₂ adsorbent is enhanced.

[3. Method for producing carbon-containing powder]
Next, a method of producing the carbonaceous powder of the present embodiment will be described in detail.

[3.1. Outline of Manufacturing Method of Carbon-Containing Powder]
First, an outline of a method for producing a carbon-containing powder according to the present embodiment will be described with reference to Fig. 4 .

As shown in Fig. 4, the method for producing a carbonaceous powder according to the present embodiment includes a combustion step (S0) and a separation and recovery step (S1). In the combustion step (S0), the fuel coal FC is burned by the boiler 4 such as a thermal power plant to generate fly ash FA which is a coal ash. Next, in the separation and recovery step (S1), the oxide particles P1 and the unburned carbon particles P2 are separated from the fly ash FA by the separation and recovery device 5, and are collected separately.

[3.2. Gravity Separation Method]
Next, in the separation and recovery step (S1) of 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.

In the separation and recovery step of the present embodiment, the mixture derived from the fly ash FA and having the oxide particles P1 and the unburned carbon particles P2 mixed therein is wet-separated into a carbon powder mainly composed of the unburned carbon particles P2. P0 and oxide particles P1.

In the separation method, water is used as an extractant for the hydrophilic particles, that is, the oxide particles P1, and an extractant such as a hydrophobic liquid having a specific gravity larger than water is used as the hydrophobic particles, that is, the unburned carbon particles P2. Next, the water and the hydrophobic liquid are mixed with a fly ash (solid content) FA which is a mixture of the treatment target, and stirred to form a mixed liquid (first slurry) in which the mixture is dispersed (mixing step). Next, the mixed solution is placed in a separation device (for example, a sedimentation tank such as a sedimentation tank or a stationary tank), whereby the mixed liquid is separated into the upper aqueous phase and the lower portion by the difference in specific gravity between the water and the hydrophobic liquid. The two sides of the hydrophobic liquid phase are moved, and the oxide particles P1 (hydrophilic particles) are moved to the aqueous phase, and the unburned carbon particles P2 (hydrophobic particles) are moved to the hydrophobic liquid phase (specific gravity separation step). Then, the oxide particles P1 are separated and recovered from the separated aqueous phase (second slurry) (first recovery step first recovery step), and from the hydrophobic liquid phase which has been separated in the above separation step (the first 3 Slurry) Separation and recovery of unburned carbon particles P2 (second recovery step). Thereby, 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 rate can be separately recovered and reused.

Here, the hydrophobic liquid is a liquid having hydrophobicity, that is, a liquid having a property of having low affinity for water (in other words, it is difficult to dissolve in water or difficult to mix with water). The hydrophobic liquid may be a liquid having a solubility in water of 20 ° C of 0 g / L or more and 5.0 g / L or less. Further, the hydrophobicity referred to in the present specification is a property including lipophilicity. The hydrophobic liquid may be a hydrophobic organic solvent (hereinafter referred to as "hydrophobic solvent") or various oils such as eucalyptus oil. As the hydrophobic solvent, for example, a fluorine-based, bromine-based or chlorine-based organic solvent can be used. Since the hydrophobic liquid has a low affinity for water, if a mixture of a hydrophobic liquid and water is mixed and stirred, the water-based aqueous phase can be separated, and a hydrophobic liquid (for example, hydrophobic) can be separated. The solvent is a two phase of a hydrophobic liquid phase (for example, a hydrophobic solvent phase) of the host.

Table 2 shows an example of a hydrophobic liquid used in the separation method of the present embodiment. The hydrophobic liquids exemplified in Table 2 have a specific gravity greater than 1, and have a solubility in water of 5.0 g/L or less, all of which are hydrophobic.

[Table 2]

Further, the specific gravity of the hydrophobic liquid is preferably more than 1.05. Thereby, the difference in specific gravity between the water and the hydrophobic liquid can be quickly separated into the aqueous phase and the hydrophobic liquid phase in a short time of, for example, about 1 to 30 seconds after the mixture is allowed to stand.

The hydrophilic particles are particles having affinity for water, and have a property of being more easily mixed with water than the above 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 affinity for the above hydrophobic liquid, and have a property of being more easily mixed with a hydrophobic liquid than water. The unburned carbon particles P2 contained in the fly ash FA are hydrophobic particles. Thus, in a mixed liquid of water and a hydrophobic liquid, the hydrophilic particles (oxide particles P1) move from the hydrophobic liquid phase to the aqueous phase, and are mainly dispersed and present 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 are mainly dispersed and present in the hydrophobic liquid phase.

Further, the hydrophilic particles, that is, the oxide particles P1, have a specific gravity of, for example, 2.4 to 2.6. The hydrophobic particles, that is, the unburned carbon particles P2, have a specific gravity of, for example, 1.3 to 1.5. Even in the case where the specific gravity of the hydrophobic particles is smaller than the specific gravity of the hydrophilic particles as described above, the hydrophilic particles can be floated to the aqueous phase of the upper phase and the hydrophobic particles can be settled by the separation method according to the present embodiment. The hydrophobic phase of the lower phase allows the two particles to be wet separated quickly and efficiently. Further, even if the specific gravity of the oxide particles P1 is smaller than the specific gravity of the unburned carbon particles P2, the oxide particles P1 and the unburned carbon particles P2 can be separated by wet separation using water and a hydrophobic liquid as described above. . In the present specification, the specific gravity of the particles means the specific gravity (true specific gravity) of the particles themselves, and is not the bulk specific gravity of the particles.

[3.3. Separation and recovery method of carbonaceous powder]
Next, a method of separating and recovering in the method for producing a carbon-containing powder according to the present embodiment will be described in detail with reference to Fig. 5 . In the following description, a description will be given of an example in which a hydrophobic solvent is used as the hydrophobic liquid.

As shown in FIG. 5, the separation and recovery step (S1) includes a specific gravity separation step (S2) and a recovery step (S4). Further, the specific gravity separation step (S2) includes a coarse 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).

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 leaving the mixed solution, the hydrophobic solvent phase ph2 mainly containing the unburned carbon particles P2 as a solid component (in other words, carbon particles) and the aqueous phase ph1 mainly containing the oxide particles P1 are separated by specific gravity. Through the coarse 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 the solid content in the hydrophobic solvent phase ph2 (in other words, the carbon content) can be increased.

Next, in the water washing step (S22), water L1 is added to the hydrophobic solvent phase ph2 which has been separated in the above-mentioned crude separation step (S21), and mixed. By leaving the mixed solution, the hydrophobic solvent phase ph2 in which the unburned carbon particles P2 are concentrated as a solid component and the aqueous phase ph1 mainly containing the remaining oxide particles P1 are separated by specific gravity. By the water washing step (S22), the hydrophobic solvent phase ph2 containing the unburned carbon particles P2 is washed with water L1, and the oxide remaining in the crude separation step (S21) can be separated from the unburned carbon particles P2. The particles P1 are removed. Therefore, the unburned carbon particles P2 contained in the hydrophobic solvent phase ph2 can be concentrated, and the content ratio (carbon content) of the unburned carbon particles P2 in the solid component in the hydrophobic solvent phase ph2 can be further increased.

The water washing step (S22) may be carried out only once, or may be carried out a plurality of times (for example, 2 to 4 times) to cause the content ratio of the unburned carbon particles P2 in the solid in the hydrophobic solvent phase ph2 (in other words, , that is, the carbon content) is further increased. Further, in the specific gravity separation step (S2), the water washing step (S22) is not necessarily required, and only the above-described coarse separation step (S21) may be performed. Even in such a case, the unburned carbon particles P2 and the oxide particles P1 can be separated to some extent, and the hydrophobic solvent phase ph2 having a high unburned carbon particle P2 content can be obtained.

Next, in the solid-liquid separation step (S41) of the recovery step (S4), the hydrophobic solvent phase ph2 which has been separated in the above-described specific gravity separation step (S2) is subjected to solid-liquid separation treatment such as filtration or centrifugation. The hydrophobic solvent L2 separated into a liquid component and the particles of the solid component (mainly unburned carbon particles P2 and residual oxide particles P1) are removed from the solid component particles to remove the hydrophobic solvent L2. Thereby, the cake C2 can be recovered, and the cake C2 is mainly composed of solid component particles such as unburned carbon particles P2.

Thereafter, in the drying step (S42), the hydrophobic solvent L2 remaining in the cake C2 is volatilized by heating the cake C2. Thereby, the carbonaceous powder P0 (carbon content: 50% by mass or more) mainly composed of the unburned carbon particles P2 can be recovered.

Here, the boiling point of the hydrophobic solvent L2 is preferably lower than 200 ° C at atmospheric pressure, more preferably lower than 100 ° C. Thereby, in the drying step (S42), the cake C2 mainly composed of the unburned carbon particles P2 is dried to volatilize and remove the hydrophobic solvent L2, and an inexpensive heat source (for example, steam) can be used as the vapor source. Heating source.

As described above, according to the separation and recovery step of the method for producing a carbon-containing powder of the present embodiment, the carbonaceous powder P0 mainly composed of unburned carbon particles P2 can be separated and recovered from the fly ash FA, and the carbon content is obtained. 50% by mass or more of the carbonaceous powder P0.

[4. Structure of separation and recovery device]
Next, the configuration and operation of the separation and recovery device 5 that performs the separation and recovery step of the present embodiment will be described in detail with reference to Fig. 6 . Fig. 6 is a schematic view showing the separation and recovery device 5 of the present embodiment. Further, the specific gravity of the hydrophobic solvent L2 used is more than 1.05.

As shown in Fig. 6, the separation and recovery device 5 of the present embodiment includes two sets of mixing devices (mixers 51A and 51B) and separation devices (settling tanks 52A and 52B) for performing the above-described specific gravity separation step (S2), and first recovery. The device 61 and the second recovery device 62 that performs the above-described recovery step (S4).

(1) A coarse separation step using a mixing device and a separation device (S21)
In the coarse separation step (S21) of the specific gravity separation step (S2), in the mixed liquid in which the water L1 and the hydrophobic solvent L2 are mixed, the fly ash FA is mixed and allowed to stand. Thereby, the mixed liquid phase can be separated into the aqueous phase ph1 and the hydrophobic solvent phase ph2, and the hydrophilic oxide particles P1 can be moved to the aqueous phase ph1 to move the hydrophobic unburned carbon particles P2 to the hydrophobic solvent phase. Ph2, and the oxide particles P1 are roughly separated from the unburned carbon particles P2. This coarse separation step (S21) includes a mixing step using a mixing device (mixer 51A) and a specific gravity separating step using a separating device (settling tank 52A).

In the mixing step, the fly ash FA in which the oxide particles P1 and the unburned carbon particles P2 are mixed is mixed in the water L1 and the hydrophobic solvent L2, and the mixed liquid is stirred to form a slurry to form a first slurry. . As the mixing device for performing the mixing step, for example, a vessel having a stirring blade capable of stirring the mixed liquid, a line mixer or a pump which can internally stir the mixed liquid can be used.

The mixer 51A as an example of Fig. 6 is a mixer having a motor 511A and a stirring blade 512A. The mixer 51A is connected to the settling tank 52A of the rear stage through the pipe 80A. A mixture of the separation targets, that is, fly ash FA, water L1, and a hydrophobic solvent L2 having a larger specific gravity than water L1 are placed in the container of the mixer 51A. The mixer 51A rotates the agitation blade 512A by the motor 511A to mix the fly ash FA, the water L1, and the hydrophobic solvent L2 to generate a first slurry (oxide particles P1, unburned carbon particles P2, water L1, and hydrophobic). a mixture of solvents L2) (mixing step).

The settling tank 52A is an example of a separating device that performs a specific gravity separation step. The settling tank 52A is separated from the aqueous phase ph1 mainly containing the oxide particles P1 by the difference in specific gravity between the water L1 and the hydrophobic solvent L2 by standing still on the first slurry formed in the mixing step, and mainly contains unburned The hydrophobic solvent phase ph2 of the carbon particles P2.

The settling tank 52A is an example of a specific gravity separating device that separates a liquid of a plurality of kinds of liquids and separates the liquid by a specific gravity difference, and is connected to the mixer 51A through a permeate line 80A. Further, the settling tank 52A is connected to the first recovery device 61 in the subsequent stage through the conduit 81A. The line 81A is provided with a pump 71A for discharging the aqueous phase ph1 (second slurry) containing the oxide particles P1. Further, the settling tank 52A is connected to the mixer 51B of the rear stage through the line 82A, and the line 82A is provided with a pump 72A for discharging the solvent phase ph2 (third slurry) containing the unburned carbon particles P2.

The mixer 52A is a water phase ph1 in which the first slurry introduced from the mixer 51A through the line 80A is separated into the upper phase by the specific gravity difference, and the hydrophobic solvent phase ph2 of the lower phase (hereinafter, sometimes referred to as "solvent" The phase ph2") moves the oxide particles P1 to the aqueous phase ph1 and moves the unburned carbon particles P2 to the solvent phase ph2. Thereby, the oxide particles P1 and the unburned carbon particles P2 are separated. Thereafter, the aqueous phase ph1 (second slurry) containing the oxide particles P1 is discharged from the upper portion of the settling tank 52A to the first recovery device 61 through the line 81A. On the other hand, the solvent phase ph2 (third slurry) containing the unburned carbon particles P2 is discharged from the lower portion of the settling tank 52A to the mixer 51B through the line 82A. The third slurry mainly contains unburned carbon particles P2 as a solid component, but also contains oxide particles P1 which have not been completely separated.

(2) Water washing step using the mixing device and the separating device (S22)
In the water washing step (S22) of the specific gravity separation step (S2), after the water L1 is added to the solvent phase ph2 (third slurry) recovered in the coarse separation step (S21) and mixed, Stand still. Thereby, the mixed liquid phase can be separated into the aqueous phase ph1 and the hydrophobic solvent phase ph2, and the oxide particles P1 remaining in the third slurry can be moved to the aqueous phase ph1 to concentrate the unburned carbon particles P2 in the 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.

This water washing step (S22) includes a mixing step using a mixing device (mixer 51B) and a specific gravity separating step using a separating device (settling tank 52B). As the mixer 51B, a device having the same configuration as that of the above mixer 51A can be used. As the settling tank 52B, a device having the same structure as the above-described settling tank 52A can be used.

The solvent phase ph2 (third slurry) supplied from the settling tank 52A is supplied to the inside of the container of the mixer 51B. The mixer 51B mixes the third slurry and the water L1 by rotating the stirring blade 512B by the motor 511B to generate a fourth slurry (unburned carbon particles P2, remaining oxide particles P1, water L1, and hydrophobic solvent L2). Mixture) (mixing step).

The settling tank 52B is connected to the mixer 51B through the passage 80B. Further, the settling tank 52B is connected to the first recovery device 61 in the subsequent stage through the flow line 81B. The line 81B is provided with a pump 71B for discharging the aqueous phase ph1 (the fifth slurry) containing the oxide particles P1. Further, the settling tank 52B is connected to the second recovery device 62 of the subsequent stage through the passage 82B. The line 82B is provided with a pump 72B for discharging the solvent phase ph2 (sixth slurry) containing the unburned carbon particles P2.

The settling tank 52B is separated from the aqueous phase ph1 mainly containing the oxide particles P1 by the fourth slurry formed by the mixer 51B, and separated into a water phase ph1 mainly containing the oxide particles P1. The solvent phase ph2 of the unburned carbon particles P2 is followed. Thereafter, the aqueous phase ph1 (the fifth slurry) containing the oxide particles P1 is discharged from the upper portion of the settling tank 52B to the first recovery device 61 through the line 81B. On the other hand, the solvent phase ph2 (sixth slurry) containing the unburned carbon particles P2 is discharged from the lower portion of the settling tank 52B to the second recovery device 62 through the line 82B.

(3) First recovery step using the first recovery device (S3)
The first recovery device 61 separates the water L1 from the aqueous phase ph1 of the oxide-containing particles P1 to recover the oxide particles P1, and the aqueous phase ph1 of the oxide-containing particles P1 is washed by the coarse separation step (S21) and water washing. The net step (S22) is separated. The first recovery device 61 includes a centrifugal separator 611, a drying device 612, and a condenser 613.

The centrifugal separator 611 is an example of a solid-liquid separation device that separates a solid suspended in a liquid from a liquid by centrifugal force. The centrifugal separator 611 is connected to the drying device 612 of the subsequent stage through the pipe 832, and is connected to the mixers 51A, 51B of the preceding stage through the pipe 831. The aqueous phase ph1 (second slurry, fifth slurry) containing the oxide particles P1 is introduced into the centrifugal separator 611 from the settling tanks 52A and 52B. On the other hand, the centrifugal separator 611 separates the slurry into the cake C1 containing the oxide particles P1 and the water L1 by centrifugal force (solid-liquid separation step). The oxide particles P1 dehydrated by the centrifugal separator 611 are discharged to the drying device 612 through the line 832. On the other hand, the water L1 separated by the centrifugal separator 611 is returned to the mixers 51A and 51B through the line 831 to be reused in the above-described coarse separation step (S21) and water washing step (S22).

Further, in the present embodiment, in order to separate the slurry into the water L1 and the oxide particles P1, the centrifugal separation process by the centrifugal separator 611 is employed, but a solid-liquid separation method such as pressure filtration, distillation or filtration may be employed. To replace it. However, if the hydrophobic solvent L2 is volatile, in order to reduce the leakage of the volatilized solvent gas, for example, a distillation apparatus, a centrifugal separation apparatus or a filtration apparatus is preferably used as the solid-liquid separation apparatus.

The drying device 612 heats the cake C1 to evaporate the remaining water, and the cake C1 is introduced from the centrifugal separator 611 and contains the oxide particles P1. Thereby, the oxide particles P1 can be dried (drying step). The dried oxide particles P1 are discharged from the line 833 and recovered. The condenser 613 condenses the water vapor sent from the drying device 612 through the line 834, and returns to the liquid water L1 (condensation step). The water L1 of the liquid generated by the condenser 613 is returned to the mixer 51 through the line 835 for reuse in the above-described coarse separation step (S21) and water washing step (S22).

As described above, in the separation and recovery method of the present embodiment, in the first recovery step (S3), the aqueous phase ph1 (second and fifth slurry) containing the oxide particles P1 is separated into two by the centrifugal separator 611. The oxide particles P1 and the water L1, and the aqueous phase ph1 of the oxide-containing particles P1 are separated by the specific gravity separation step (S2). Thereafter, the oxide particles P1 are dried by the drying device 612, and the oxide particles P1 of the dry powder are recovered. However, the first recovery step (S3) is not limited to this example, and the aqueous phase ph1 (second and fifth slurry) of the oxide-containing particles P1 separated by the specific gravity separation step (S2) may not be performed. The solid-liquid separation step or the drying step described above directly recovers the oxide particles P1 in the water slurry state. The oxide particles P1 are collected in a state of a dry powder state, a cake form, or a water slurry state by appropriately selecting the use of the oxide particles P1.

Further, in the first recovery step (S3), the aqueous phase ph1 (second and fifth slurry) of the oxide-containing particles P1 separated by the specific gravity separation step (S2) is preferably heated to a hydrophobic solvent. The temperature above the boiling point of L2 or the pressure is reduced to a pressure at which the hydrophobic solvent L2 can be evaporated, whereby the hydrophobic solvent L2 remaining in the aqueous phase ph1 is evaporated and removed. Thereby, the hydrophobic solvent L1 to be recovered can be prevented from containing the hydrophobic solvent L2, and the quality of the oxide particles P1 can be improved. In the separation and recovery device 5 of the present embodiment, the water L1 and the hydrophobic solvent L2 are heated together by a drying step using the drying device 612 shown in Fig. 6 to evaporate, thereby being removed in the second. The hydrophobic solvent L2 in the fifth slurry. Further, when the hydrophobic solvent L2 is volatile, it can be evaporated at normal temperature. However, since the specific gravity of the hydrophobic solvent L2 is larger than that of the water L1, the hydrophobic solvent L2 does not directly contact the gas phase. Therefore, stirring or aeration is preferred, and appropriate treatment should be taken at this time so that the solvent L2 after volatilization does not scatter.

When the hydrophobic solvent L2 is heated to evaporate, when the oxide particles P1 to be recovered are in the form of a cake, the boiling point of the hydrophobic solvent L2 is preferably 150 ° C or less at atmospheric pressure. Thereby, the hydrophobic solvent L2 can be evaporated and removed at a lower cost. On the other hand, when the oxide particles P1 to be recovered are in the form of a slurry, the boiling point of the hydrophobic solvent L2 is preferably 95 ° C or lower at atmospheric pressure. Thereby, 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. Further, the boiling point of the hydrophobic solvent L2 is preferably 40 ° C or higher at atmospheric pressure. Thereby, the amount of volatilization of the hydrophobic solvent L2 at normal temperature atmospheric pressure can be suppressed, and recovery and disposal can be easily performed.

(4) A second recovery step using the second recovery device (S4)
The second recovery device 62 separates and removes the hydrophobic solvent L2 from the hydrophobic solvent phase ph2 (the sixth slurry) containing the unburned carbon particles P2 to recover the carbonaceous powder P0 mainly composed of the unburned carbon particles P2 ( S4), the hydrophobic solvent phase ph2 containing the unburned carbon particles P2 is separated by the specific gravity separation step (S2). The second recovery device 62 includes a centrifugal separator 621, a drying device 622, and a condenser 623.

The centrifugal separator 621 is connected to the drying device 622 of the subsequent stage through the pipe 842, and is connected to the mixer 51A of the front stage through the pipe 841. The hydrophobic solvent phase ph2 (sixth slurry) containing the unburned carbon particles P2 is introduced into the centrifugal separator 621 from the settling tank 52B. On the other hand, the centrifugal separator 621 separates the sixth slurry into a cake C2 mainly composed of unburned carbon particles P2 and a hydrophobic solvent L2 by centrifugal force (solid-liquid separation step (S41)). The unburned carbon particles P2 separated from the hydrophobic solvent L2 by the centrifugal separator 621 are discharged to the drying device 622 through the line 842. On the other hand, the hydrophobic solvent L2 separated by the centrifugal separator 621 is returned to the mixer 51A through the line 841 to be reused in the above-described coarse separation step (S21). Further, in the present embodiment, in order to separate the sixth slurry into the hydrophobic solvent L2 and the unburned carbon particles P2, centrifugal separation by the centrifugal separator 621 is employed, but pressure filtration, distillation, or filtration may be employed. Replace the solid-liquid separation method.

The drying device 622 heats the cake C2 to volatilize the remaining hydrophobic solvent component, and the cake C2 is introduced from the centrifugal separator 621 and contains unburned carbon particles P2. Thereby, the solid component mainly composed of the unburned carbon particles P2 can be dried to obtain the carbonaceous powder P0 (drying step (S42)). The carbonaceous powder P0 mainly composed of the unburned carbon particles P2 after being dried is discharged from the line 843 and recovered. The condenser 623 condenses the vapor of the hydrophobic solvent L2 sent out from the drying device 622 through the line 844, and returns to the liquid hydrophobic solvent L2 (coagulation step). The liquid hydrophobic solvent L2 generated by the condenser 623 is returned to the mixer 51A through the line 845 to be reused in the above-described coarse separation step (S21) (second reuse step).

As described above, in the separation and recovery method of the present embodiment, in the second recovery step (S4), the solvent phase ph2 (the sixth slurry) containing the unburned carbon particles P2 is separated into the uncontaining portion by the centrifugal separator 621. The cake of the carbonaceous particles P2 and the hydrophobic solvent L2, and the solvent phase ph2 of the unburned carbon particles P2 are separated by the specific gravity separation step (S2). Thereafter, the cake C2 is dried by the drying device 622, and the carbonaceous powder P0 mainly composed of the unburned carbon particles P2 of the dry powder is recovered.

The structure of the separation and recovery device 5 of the present embodiment and the separation and recovery method of the carbonaceous powder P0 using the same are described above. In the present embodiment, in order to carry out the method 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.

Further, the water L1 separated from the oxide particles P1 in the first recovery step (S3) is recovered for reuse as the water L1 charged in the specific gravity separation step (S2), and is recovered in the second recovery step ( The hydrophobic solvent L2 separated from the unburned carbon particles P2 in S4) is reused as the hydrophobic solvent L2 to be charged in the specific gravity separation step (S2). Thereby, it is possible to reduce the raw material cost and the disposal cost of the hydrophobic solvent L2 without discarding the used water L1 and the hydrophobic solvent L2. Moreover, a large amount of the hydrophobic solvent L2 can be repeatedly used in the specific gravity separation step (S2), and the chance that the unburned carbon particles P2 are in contact with the hydrophobic solvent L2 can be increased. Further, in the coarse separation step (S21) and the water washing step (S22) of the specific gravity separation step (S2), the unburned carbon particles P2 in the fly ash FA are taken up into the hydrophobic solvent phase ph2, and the oxide particles are P2 is taken into the aqueous phase ph1, whereby the oxide particles P1 and the unburned carbon particles P2 can be efficiently separated.

Therefore, compared with the conventional flotation method described in the above Patent Document 1, the separation and recovery method in the method for producing a carbon-containing powder of the present embodiment can greatly improve the separation speed and separation of oxide particles and unburned carbon particles. effectiveness. For example, by the coarse separation step (S21) of the present embodiment, the oxide particles P1 and the unburned carbon particles P2 can be rapidly separated in a short time of, for example, about 1 second to 30 seconds. In addition, the content of the unburned carbon particles P2 in the oxide particles P1 obtained by the separation and recovery can be reduced to 3% by mass or less, and the high-purity oxide particles P1 can be recovered. In the same manner, the content of the oxide particles P1 mixed in the carbonaceous powder P0 obtained by separation and recovery can be reduced to less than 50% by mass, and more desirably to 30% by mass or less. Therefore, the content 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.

[4.1. Preferred conditions for gravity separation]
Next, preferred conditions for the specific gravity separation in the separation method of the present embodiment will be described in detail. First, a preferred range of the specific gravity (liquid specific gravity) of the hydrophobic solvent used in the separation method of the present embodiment will be described.

When standing in the above-described coarse separation step (S21) or water washing step (S22), concentration of oxide particles and unburned carbon particles may occur in the vicinity of the interface between the aqueous phase and the hydrophobic solvent phase. For example, in a mixed liquid of trichloroethylene (specific gravity: 1.46) and water (specific gravity: 1), which is a hydrophobic solvent, an oxide particle (specific gravity: 2.4 to 2.6) which is a hydrophilic particle is introduced as a main component. A mixture (such as fly ash) and allowed to stand for about 30 seconds or more. The oxide particles settle in the aqueous phase, while on the other hand, the unburned carbon particles (specific gravity: 1.3 to 1.5) float in the trichloroethylene phase. As a result, in the vicinity of the interface between the aqueous phase and the trichloroethylene 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 in the vicinity of the interface, the separation property of the two may be deteriorated. Therefore, in order to prevent the separation property between the oxide particles and the unburned carbon particles from deteriorating, it is preferred to separate the aqueous phase from the hydrophobic solvent in a short time after standing, and it is preferable not to take it in the vicinity of the interface between the two phases.

The larger the specific gravity of the oxide particles, the more preferable the hydrophobic solvent is selected. Thereby, it is possible to prevent the oxide particles from sinking from the aqueous phase to the solvent phase. Further, when the specific gravity of the oxide particles is small, it is not necessary to specifically select a hydrophobic solvent having a small specific gravity, and it is possible to expand the specific gravity range of the applicable hydrophobic solvent.

The mass ratio of the oxide particles contained in the aqueous phase (that is, the slurry of water and oxide particles) is taken as the slurry concentration C _S [% by mass] of the aqueous phase. The slurry concentration C _S is represented by the following formula (2). The aqueous phase of the apparent density ρ _S [g / cm ^3] and divided at the same temperature under the same pressure of the water density ^{_{ρ w [g / cm 3]}} , and the value obtained as the proportion of the aqueous phase of the slurry d _S . The slurry specific gravity d _S is represented by the following formula (3).

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]: the mass of oxide particles contained in the aqueous phase
m _W [g]: the quality of the water contained in the aqueous phase
V _P [cm ³ ]: volume of oxide particles contained in the aqueous phase
V _W [cm ³ ]: volume of water contained in the aqueous phase ρ _S [g/cm ³ ]: apparent density of water slurry of water phase and oxide particles ρ _w [g/cm ³ ]: same temperature And the density of water under the same pressure

As long as the specific gravity of the aqueous phase is smaller than the specific gravity of the hydrophobic solvent, the aqueous phase is less likely to settle into the solvent phase, which is advantageous for smooth phase separation of the aqueous phase and the solvent phase. Therefore, in order to suppress the above-described sedimentation, it is preferred to adjust the mixing ratio of the mixture (fly ash) to water in the mixing step, or to select a hydrophobic solvent having an appropriate specific gravity.

Further, the specific gravity of the hydrophobic solvent is more preferably greater 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 smaller than the specific gravity of the hydrophobic solvent as described above, the slurry concentration C _{S of} the aqueous phase needs to be lower than a predetermined value. In this case, there is a possibility that the separation device is enlarged. On the other hand, by making the specific gravity of the hydrophobic solvent larger than 1.05, the slurry concentration C _S of the aqueous phase can be increased to be larger than the predetermined enthalpy, so that the separation amount per unit time can be increased without using a large separation device.

Further, in the solvent phase, a thin (for example, about 5 to 20 μm) water film may be adhered to the surface of the oxide particles which are not adhered to the water droplets. The specific gravity of the oxide particles (hereinafter also referred to as "water film particles") coated with the water film is smaller than the specific gravity of the oxide particles. Therefore, it is preferred to select a hydrophobic solvent having a specific gravity greater than that of the water-coated film particles. Thereby, in the above separation step, the water-coated film particles can be floated from the solvent phase to the aqueous phase and retained in the aqueous phase. Therefore, the oxide particles can be quickly and efficiently separated from the hydrophobic solvent and the unburned carbon particles. When it is difficult to directly measure the apparent specific gravity of the water-coated film particles, for example, 0.5 to 1 g of oxide particles may be added to a mixed liquid composed of 80 ml of water and 20 ml of a hydrophobic solvent in a measuring cylinder with a cap. The oxide particles hardly settle to the hydrophobic solvent of the solvent phase.

Further, the specific gravity of the hydrophobic solvent is preferably smaller than the specific gravity 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 the centrifugal separator 621, the liquid repellency is improved, and the separation can be efficiently separated. Unburned carbon particles P2. In addition, even in the case of "the specific gravity of the unburned carbon particles P2 <the specific gravity of the hydrophobic solvent L2", the centrifugal separator may be used although the liquid detachability is poor, or the solid-liquid separation by filtration or distillation may be employed. Device.

Next, a preferred range of the particle diameter or specific gravity of the particles used in the separation method of the present embodiment will be described. In the state where the oxide particles settle in the aqueous phase and reach the interface between the aqueous phase and the hydrophobic solvent phase, buoyancy, interfacial tension, and gravity act on the oxide particles. The interfacial tension acts as an energy barrier that hinders the movement of particles from one phase to the other in the above interface. It can also be said that the balance of these forces determines which phase the oxide particles will move to. We believe that if the particle size of the oxide particles is so large that the gravity is greater than the sum of the buoyancy and interfacial tension acting on the oxide particles, or the specific gravity of the oxide particles is greater than the specific gravity of the water, the particles will Move from the aqueous phase through the interface to the solvent phase. In this case, the separation efficiency of the oxide particles and the unburned carbon particles is lowered. From this point of view, it is preferred to remove oxide particles having a particle size which is large enough to move to the solvent phase through the interface, or oxide particles which are more important to move to the solvent phase through the interface, before the separation treatment. For example, the particle size of the oxide particles contained in the fly ash before the separation treatment may be 500 μm or less, and preferably 200 μm or less.

The unburned carbon particles that float in the hydrophobic solvent phase and reach the interface are also the same as described above. We believe that if the particle size of the unburned carbon particles is so large that the buoyancy is greater than the sum of the gravity and interfacial tension acting on the unburned carbon particles, or the specific gravity of the unburned carbon particles is less than the specific gravity of the hydrophobic solvent, The particles move from the solvent phase through the interface to the aqueous phase. From this point of view, it is preferred to remove unburned carbon particles having a particle size that is large enough to move to the aqueous phase through the interface, or unburned carbon particles having a specific gravity that is small enough to move to the aqueous phase through the interface, before the separation treatment. . For example, the particle size of the unburned carbon particles contained in the fly ash before the separation treatment may be 500 μm or less, and preferably 200 μm or less. Further, the mesh may be sieved or classified by a cyclone to control the maximum particle size of the mesh.

[5. Separation and recovery method with pulverization step]
Next, a method for producing a carbonaceous powder according to a second embodiment of the present invention will be described. The manufacturing method of the second embodiment is characterized in that it further comprises a pulverization step of pulverizing the unburned carbon particles in the fly ash to increase the carbon content in the recovered carbon-containing powder.

[5.1. Flow of separation and recovery method with pulverization step]
7 to 10 are process diagrams showing a separation and recovery method in the manufacturing method of the second embodiment. As shown in Fig. 7 to Fig. 10, the pulverization step (S5) is added to the separation and recovery method of the second embodiment as compared with the separation and recovery method (see Fig. 5) of the first embodiment. In the example of the steps shown in FIGS. 7 to 9, the pulverization step (S5) is added before the coarse separation step (S21) of the specific gravity separation step (S2). On the other hand, in the example of the step shown in Fig. 10, in the middle of the specific gravity separation step (S2), specifically, the pulverization is added between the coarse separation step (S21) and the water washing step (S22). Step (S5).

First, an example of the steps shown in Fig. 7 will be described. As shown in Fig. 7, first, a mixture of fly ash FA, water L1 and hydrophobic solvent L2 is pulverized (S5). Thereby, even if the oxide particles P1 adhere to the surface of the unburned carbon particles P2 as shown in FIG. 2, or the oxide particles P1 enter the pores P20 of the unburned carbon particles P2, the pulverization treatment can be carried out as shown in FIG. The unburned carbon particles P2 are pulverized and refined. As a result, a part of the oxide particles P1 in the pores P20 are released, so that the unburned carbon particles P2 and the oxide particles P1 which have been miniaturized are separated or at least easily separated.

After the pulverization step (S5), the coarse separation step (S21) and the water washing step (S22) of the specific gravity separation step (S2) are performed in the same manner as in the first embodiment. Thereby, the pulverized unburned carbon particles P2 are easily separated from the oxide particles P1 and moved to the solvent phase ph2, and the oxide particles P1 are also easily separated from the unburned carbon particles P2 and moved to the aqueous phase ph1. Therefore, in the specific gravity separation step (S2), the oxide particles P1 and the unburned carbon particles P2 can be more appropriately separated, and the carbon content of the carbon-containing powder P0 recovered in the recovery step (S4) can be increased to 70% by mass or more.

Further, the aqueous phase ph1 of the oxide-containing particles P1 separated in the coarse separation step (S21) is subjected to solid-liquid separation and dried, whereby an oxide powder can be obtained. Since the pulverization treatment is carried out in the pulverization step (S5), the unburned carbon particles P2 accompanying the oxide particles P1 are smaller than those of the fly ash FA before the treatment, and the solid matter obtained from the aqueous phase ph1 is contained. The carbon rate is greatly reduced. The carbon content is substantially higher than the carbon content in the solid obtained by recovering the aqueous phase ph1 of the oxide-containing particles P1 separated from the coarse separation step (S21) of Fig. 5 having no pulverization step. reduce.

Next, an example of the steps of FIGS. 8 and 9 will be described. As shown in Fig. 8, first, a mixture of fly ash FA and water L1 is pulverized (S5). As a result, the unburned carbon particles P2 are pulverized and refined, and the unburned carbon particles P2 and the oxide particles P1 are easily separated. Next, in the coarse separation step (S21) of the specific gravity separation step (S2), the hydrophobic solvent L2 is added to the pulverized mixed solution and mixed, and the mixed solution is subjected to specific gravity separation, followed by a water washing step. (S22).

Moreover, in the example of the procedure of FIG. 9, first, the mixed liquid of the fly ash FA and the hydrophobic solvent L2 is pulverized (S5). As a result, the unburned carbon particles P2 are pulverized and refined, and the unburned carbon particles P2 and the oxide particles P1 are easily separated. Next, in the coarse separation step (S21) of the specific gravity separation step (S2), water L1 is added to the pulverized mixed liquid and mixed, and the mixed liquid is subjected to specific gravity separation, and then subjected to a water washing step (S22). ).

As described above, in the examples of FIGS. 8 and 9, in the initial pulverization step (S5), the mixture liquid obtained by adding either the water L1 or the hydrophobic solvent L2 to the fly ash FA is subjected to pulverization treatment. Thereafter, in the specific gravity separation step (S2), the other of the water L1 or the hydrophobic solvent L2 is added to the mixed liquid after the pulverization and mixed, and then the specific gravity is separated. Even in the step sequence, the oxide particles P1 and the unburned carbon particles P2 can be further appropriately separated in the specific gravity separation step (S2), and the carbonaceous powder P0 recovered in the recovery step (S4) can be used. The carbon content is increased to 70% by mass or more.

Further, the aqueous phase ph1 of the oxide-containing particles P1 separated in the coarse separation step (S21) is subjected to solid-liquid separation and dried, whereby an oxide powder can be obtained. Since the pulverization treatment is carried out in the pulverization step (S5), the unburned carbon particles P2 accompanying the oxide particles P1 are smaller than those of the fly ash FA before the treatment, and the solid matter obtained from the aqueous phase ph1 is contained. The carbon rate is greatly reduced. The carbon content is substantially higher than the carbon content in the solid obtained by recovering the aqueous phase ph1 of the oxide-containing particles P1 separated from the coarse separation step (S21) of Fig. 5 having no pulverization step. reduce.

Next, an example of the steps of FIG. 10 will be described. As shown in FIG. 10, first, in the coarse separation step (S21), the mixed liquid of the fly ash FA, the water L1, and the hydrophobic solvent L2 is subjected to coarse separation treatment. As a result, in the same manner as in the first embodiment (see FIG. 5), the mixed liquid is separated into the aqueous phase ph1 mainly containing the oxide particles P1 and the hydrophobic solvent phase ph2 mainly containing the unburned carbon particles P2. Thereafter, the separated hydrophobic solvent phase ph2 is recovered, and in the pulverization step (S5), only the hydrophobic solvent phase ph2 is pulverized, and in the aqueous phase ph1, the pulverization treatment is not performed. By the pulverization treatment, the unburned carbon particles P2 contained in the hydrophobic solvent phase ph2 are pulverized and refined, and are easily separated from the remaining oxide particles P1. Therefore, in the subsequent water washing step (S22), the oxide particles P1 and the unburned carbon particles P2 can be further appropriately separated, and the carbon-containing powder P0 recovered in the recovery step (S4) can be contained. The carbon ratio is increased to 70% by mass or more.

As described above, in the step example shown in Fig. 10, the unburned carbon particles P2 in the solvent phase ph2 separated and recovered in the coarse separation step (S21) are pulverized in the subsequent pulverization step (S5), and The oxide particles P1 in the aqueous phase ph1 separated and recovered in the coarse separation step (S21) are not pulverized. Therefore, the pulverization treatment can be carried out particularly for the unburned carbon particles P2, so that the pulverization efficiency of the unburned carbon particles P2 can be improved. On the other hand, in the example of the steps of FIGS. 7 to 9 described above, both the unburned carbon particles P2 and the oxide particles P1 are pulverized. Therefore, not only the unburned carbon particles P2 but also the oxide particles P1 are pulverized, and when it is desired to recover the micronized oxide particles P1, the unburned carbon particles P2 and the oxide particles P1 can be pulverized. The steps are unified, but a useful method.

[5.2. Smashing method used in the pulverizing step]
Next, a specific example of the pulverization method in the above pulverization step (S5) will be described. As described above, as the pulverization method in the pulverization step (S5), for example, pulverization treatment by ultrasonic waves, pulverization treatment by a high-speed shear mixer, pulverization treatment by a ball mill or a bead mill, or the like can be employed. In the pulverization treatment by the bead mill, a spherical bead is filled in a cylindrical container, and a mixture (for example, fly ash) as a target to be pulverized is supplied, and the stirring member is rotated. Thereby, a collision force or a shearing force acts on the object to be pulverized and the bead, and the object to be pulverized is pulverized. By the pulverization treatment using the beads, for example, the porous and fragile unburned carbon particles P2 can be efficiently pulverized in a short time without destroying the hard oxide particles P1 contained in the fly ash. Therefore, the separation property of the unburned carbon particles can be improved, the carbon content in the recovered carbonaceous powder can be increased, and the carbon content in the recovered oxide can be reduced.

Further, the beads used in the pulverization treatment by the bead mill described above preferably have a diameter (hereinafter referred to as a bead diameter) of 1 mm or less. The nearly spherical oxide particles are solid and hard and are not easily broken, and the unburned carbon particles are porous, so they are fragile and easily broken. On the other hand, the diameter of the nearly spherical oxide particles is almost 100 μm or less, and the 50% particle diameter of the oxide particles is 1 to 20 μm. The larger the diameter of the beads, the more the unburned carbon particles having a small particle size between the nearly spherical oxide particles must be pulverized, and the hard oxide particles must be pulverized, and the beads collide with the unburned carbon particles having a small particle diameter. The possibility is getting lower. The smaller the diameter of the beads and the larger the curvature of the beads, the less the beads collide with the hard, nearly spherical oxide particles in the pulverization step (S5), and the smaller the unburned carbon particles with the smaller particle size. contact. Therefore, it can be said that the diameter of the beads is preferably 1 mm or less.

Further, the bead density is preferably 3.5 g/cm ³ or more. When the bead density is 3.5 g/cm ³ or more, the destructive force when the beads collide with the unburned carbon particles becomes large, so that the time taken for pulverizing the unburned carbon particles can be shortened, and the pulverization treatment can be made more efficient. In order to make the bead density be 3.5 g/cm ³ or more, the bead material is preferably made of ceramics or metal.

[6. Countercurrent multi-stage continuous process]
Next, a separation and recovery method in the production method of the third embodiment of the present invention will be described. The separation and recovery method of the third embodiment employs a countercurrent type multi-stage continuous process which is a combination of a mixing step of a multistage reusing mixing device (mixer) and a specific gravity separation step using a separating device (settling tank). For example, in the case where the coarse separation step (S21) employs a multi-stage continuous process, the aqueous phase containing the oxide particles and the solvent phase containing the unburned carbon particles are separated in the multistage coarse separation step (S21). Therefore, compared with the single-stage continuous process of the first embodiment, the separation efficiency of the oxide particles and the unburned carbon particles can be further improved, and the oxide particles contained in the recovered solid can be respectively unburned. The content of carbon particles increases. The same applies to the multi-stage continuous process in the water washing step (S22).

In the example shown in Fig. 11, the coarse separation step (S21) and the water washing step (S22) are repeated in multiple stages. While repeating the N stage of the coarse separation step (S21) (N is an integer of 2 or more), the water washing step (S22) M step (M is an integer of 2 or more) is repeated.

If, for example, the coarse separation step (S21) is attempted, in the case where N is an integer of 3 or more, the aqueous phase ph1 and the solvent phase ph2 are mixed and slurried in the mixing step of the n+1th stage, and the aqueous phase ph1 is Separated in the specific gravity separation step of the nth stage (n is an integer of 1 or more and N-2 or less), and contains the oxide particles P1 and the remaining unburned carbon particles P2, and the solvent phase ph2 is at the n+th The two-stage specific gravity separation step is separated, and contains unburned carbon particles P2 and residual oxide particles P1. Next, in the specific gravity separation step of the n+1th stage, the aqueous phase ph1 mainly containing the oxide particles P1 and the solvent phase ph2 mainly containing the unburned carbon particles P2 are separated. The combination of the mixing step and the specific gravity separation step is repeated in each stage, whereby the higher the content of the oxide particles P1 is, the higher the content of the oxide particles P1 is, the more the water phase ph1 is obtained from the first stage to the Nth stage. From the Nth stage to the first stage, the solvent phase ph2 having a higher content ratio of the unburned carbon particles P2 can be obtained. The water washing step (S22) is also the same as the coarse separation step (S21). The more the solvent phase ph2 is obtained from the first stage to the Mth stage, the higher the content rate of the unburned carbon particles P2 is obtained, and the oxide particles P1 can be obtained from the M stage to the first stage. The higher the content rate of the aqueous phase ph1.

The hydrophobic solvent L2 is charged in the mixing step of the Nth stage. Thereafter, in the first recovery step (S3) after the Nth stage, the oxide particles P1 and L1 are separated and recovered from the aqueous phase ph1 having a high content of the oxide particles P1. The recovered water L1 is sent back to the mixing step of the M stage for reuse. On the other hand, water L1 is supplied in the mixing step of the Mth stage. Thereafter, in the second recovery step (S4) after the Mth stage, the unburned carbon particles P2 and the hydrophobic solvent L2 are separated and recovered, respectively, in the solvent phase ph2 having a high content of the unburned carbon particles P2. The recovered hydrophobic solvent L2 is returned to the mixing step of the Nth stage for reuse.

Further, in the example of Fig. 11, the fly ash FA is charged in the mixing step of the first stage, but the fly ash FA may be charged in the mixing step of the other stage. Further, either of the coarse separation step (S21) and the water washing step (S22) may be a single stage, in other words, M or N may be 1. Further, the pulverization step (S5) may be added before or after the coarse separation step (S21) or the water washing step (S22) at any stage, following the example of the steps shown in Figs. 7 to 10.

[7. Method of using carbon-containing powder]
Next, a method of using the carbonaceous powder of the present embodiment produced by the above production method will be described.

As described above, the carbonaceous powder of the present embodiment has a carbon content of at least 50% by mass or more, preferably 70% by mass or more, and is considerably high. Therefore, the combustion efficiency can be improved when the carbonaceous powder is burned. Further, the carbon-containing powder has a N/C ratio of 0.02 or less, is extremely low, and has a low nitrogen content. Therefore, the generation of nitrogen oxides (NOx) can be suppressed when the carbonaceous powder is burned.

Therefore, the carbonaceous powder of the present embodiment can be effectively utilized in place of the low nitrogen content coal (i.e., low nitrogen coal) used in a furnace such as a sintering machine or a power plant, and is very advantageous in the industry. .

Further, the carbonaceous powder of the present embodiment is rich in unburned carbon particles which are porous particles, and has a specific surface area of 50 to 300 m ² /g which is equivalent to that of the activated coke powder, and a specific surface area of the fly ash (0.5~). 10m ² /g) is tens of times to hundreds of times. Therefore, the carbon-containing powder of the present embodiment has SO ₂ adsorption ability and denitration ability, and can be effectively utilized as an SO ₂ adsorption material or a denitration material. In particular, when the pulverization treatment is carried out as in the second embodiment, the specific surface area of the carbon-containing powder becomes larger, so that it can be effectively utilized as a high-quality SO ₂ adsorbent or denitration material.

Further, from the viewpoint of improving the rationality of the carbonaceous powder of the present embodiment, it is preferred to knead the carbonaceous powder with other powders (for example, scale, coke powder, etc.) to make the carbonaceous powder. After the bulk specific gravity is increased, it is used for the above various uses. The carbonaceous powder is a porous material having a small specific gravity and a small particle size, so that it is a very difficult to handle fine particles in a single state. Therefore, it is preferred to mix the carbonaceous powder with other powder materials having a large volume ratio to increase the bulk specific gravity (for example, 1 g/cm ³ or more). Thereby, there is an advantage that the occurrence of dust can be suppressed and it becomes easy to handle.
[Examples]

Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments.

[Example 1]
First, the test of Example 1 will be described with reference to Table 3. Table 3 shows the test conditions and results of the present Example 1.

In a measuring cylinder of 100 ml with a cap, 80 ml of water (L1) and 20 ml of various hydrophobic liquids (L2) were added, and then the mixture (P1+P2) was added to make the slurry concentration in the aqueous phase C _S [% by mass]. The concentration shown in Table 3 was obtained. As a mixture (P1+P2), fly ash was used. Next, the mixture in the graduated cylinder was vigorously mixed by hand for 10 seconds, and then allowed to stand for 10 seconds. Immediately thereafter, a sample was taken from the portion of the aqueous phase, and the solid matter in the aqueous phase was recovered, and the content of the recovered solid matter was measured. Further, the content rate C _{B of the} unburned carbon particles in the recovered solid matter was measured. Then, the unburned carbon particle separation ratio K _A represented by the following formula (4) is calculated. On the other hand, the oxide particle recovery rate K _{B is} calculated by the following formula (5).

K _A [% by mass] = {(m _{A -} m _B ) / m _A } × 100 ・・・(4)
K _B [% by mass] = (m _P / m _Q ) × 100 ・・・(5)
m _A [g]: the quality of the unburned carbon particles put in
m _B [g]: the mass of unburned carbon particles contained in the aqueous phase
m _Q [g]: the mass of the oxide particles that are input
m _P [g]: the mass of oxide particles contained in the aqueous phase

Further, as shown in Table 3, in Comparative Example 1 and Examples 1-1 to 1-9, the content rate C _C of the unburned carbon particles in the fly ash used as the mixture (P1+P2) to be separated was 1.9 mass%, the volume-based 50% particle diameter of the fly ash was 19 μm. The content C _C of the unburned carbon particles in the fly ash of Examples 1-10 to 1-13 was 5.3% by mass, and the 50% particle diameter based on the volume of the fly ash was 21 μm.

[table 3]

As a result of the above test, as shown in Table 3, the oxide particle recovery rate K _B was 73% by mass or more in any of Examples 1-1 to 1-13, particularly in Examples 1-1 and 1-6. In the embodiment, it is 92% by mass or more. Therefore, it is understood that the oxide particles P1 can be recovered from the mixture (P1+P2) at a high recovery rate by the separation method of the present embodiment. The unburned carbon particle separation rate K _A was 42 to 56% by mass in Examples 1-1 to 1-13. Therefore, it has been confirmed that the content of the unburned carbon particles P2 contained in the oxide particles P1 recovered can be greatly reduced by the separation method of the present embodiment, and the high-quality oxide particles P1 having a high content can be recovered. .

In Example 1-1 in which the specific gravity of the eucalyptus oil as the hydrophobic liquid L2 was 1.07, the content C _B of the unburned carbon particles in the solid obtained from the aqueous phase was 1.2% by mass. On the other hand, in Comparative Example 1 in which the specific gravity of eucalyptus oil was 1.03, the content rate C _B was 1.9% by mass. Therefore, it is understood that the specific gravity separation speed can be increased by setting the specific gravity of the hydrophobic liquid L2 to be more than 1.05. That is, in Comparative Example 1, since the specific gravity of the eucalyptus oil was 1.05 or less, the specific gravity of the aqueous phase was close to the specific gravity of the hydrophobic liquid phase, and the separation speed of the phase was very slow. In Comparative Example 1, it was allowed to stand for 1 minute after the above mixing, but the phase separation hardly progressed. Then, about 20 ml of the upper portion of the graduated cylinder was taken, and the solid matter was recovered, and the content C _{B of the} unburned carbon particles in the recovered product was measured and found to be 1.9% by mass. That is, the content C _{C of the} unburned carbon particles in the fly ash to be input is hardly changed.

Also, when the change in the aqueous phase of the slurry of Example C _S concentration of 1-2 to 1-6 under comparison, the slurry concentration C _S, if in more than 38% by mass, recovered from the aqueous phase obtained The content C _{B of the} unburned carbon particles in the solid becomes large. In particular, when the slurry concentration C _S was 47% by mass (Example 1-6), the content ratio C _B was 1.7% by mass. Compared with the content of unburned carbon particles in the original fly ash (1.9 mass%), it is only slightly reduced. It is presumed that this means that since the slurry concentration C _S in the aqueous phase is too high, the interface between the aqueous phase and the solvent phase is unclear, and therefore, the unburned carbon particles in the solid obtained from the aqueous phase are recovered. The content rate C _B is not much lower.

[Embodiment 2]
In Example 2, trichloroethylene was used as the hydrophobic solvent, and the carbonaceous powder was recovered from fly ash (hereinafter simply referred to as FA) according to the separation and recovery method shown in Fig. 5 .

Specifically, 250 ml of water and trichloroethylene (specific gravity: 1.46) were placed in a closed vessel (separation funnel), and 35 g of FA (carbon content: 9.3% by mass) was charged. The sealed container (separation funnel) was vigorously shaken by hand for 30 seconds to thoroughly mix FA, water and trichloroethylene. After mixing, the sealed container (separation funnel) was allowed to stand for 10 seconds, and then the trichloroethylene phase in which unburned carbon was concentrated was collected and placed in another closed vessel (separation funnel) (crude separation step S21). Further, after the sample near the interface between the trichloroethylene phase and the aqueous phase is discarded, the aqueous phase in which the oxide is concentrated is recovered, and after filtration, the solid matter is dried and recovered. 250 ml of water was added to the recovered trichloroethylene phase, and the closed vessel (separation funnel) was vigorously shaken by hand for 30 seconds to mix the trichloroethylene phase with water. Thereafter, after standing in a sealed container (separation funnel) for 10 seconds, the unburned carbon trichloroethylene phase was again recovered (water washing step S22). At this time, the sample near the interface between the trichloroethylene phase and the aqueous phase is not recovered, and is discarded. This water washing step S22 was repeated three times, and the trichloroethylene phase in which unburned carbon was concentrated was recovered. After the recovered trichloroethylene phase is filtered (solid-liquid separation step S41), moisture and trichloroethylene are volatilized by drying (drying step S42) to obtain a carbonaceous powder.

As a result, the carbon content of the carbon-containing powder of Example 2 was 57% by mass, and the ratio of the nitrogen content to the carbon content in the carbon-containing powder, that is, the N/C ratio (mass ratio) was 0.0072. Further, the total of the SiO ₂ component and the Al ₂ O ₃ component in the oxide particles in the carbon-containing powder is 75 mass% or more. Further, it was confirmed that the carbon content in the solid matter recovered from the aqueous phase was 2.8% by mass, which was a decrease from the carbon content in the FA before the treatment.

[Comparative Example 2]
In Comparative Example 2, the carbonaceous powder was recovered from the FA according to the flotation method described in Example 1 of Patent Document 1.

Specifically, while stirring 1000 ml of water and 200 g of FA (unburned carbon, 9.3% by mass), the mixture was mixed to prepare a slurry. Further, the slurry was subjected to high-speed stirring (high-speed shearing mixer power: 80 Kw/m ³ ) using a high-speed shearing mixer to impart shearing force to the slurry. Thereafter, the slurry was stirred at a low speed, and 1.3 ml of kerosene was added as a scavenger, and 200 mg of MIBC (methyl isobutylmethanol) was added as a foaming agent. Then, bubbles are generated by the flotation treatment, the unburned carbon is attached to the generated bubbles to float, and the bubbles after the floating are taken out in the form of a foam. And the flotation step was continued for 5 minutes.

Next, the FA (tailing) remaining in the vessel was dried and measured, and as a result, it was 152 g, and the carbon content thereof was 3.3% by mass. Further, after the floating carbon concentrate was dried, it was washed with n-hexane to remove the adhered kerosene and the foaming agent, and dried, and then subjected to component analysis.

As a result, the carbon concentrate of Comparative Example 2 had a carbon content of 34% by mass and an N/C ratio of 0.0095.

[Example 3]
In Example 3, the carbon concentrate obtained in Comparative Example 2 (carbon content: 34% by mass) was treated in the same manner as in Example 2 to obtain a carbon-containing powder. As a result, the carbonaceous powder of Example 3 had a carbon content of 56% by mass and an N/C ratio of 0.0074. Further, the total of the SiO ₂ component and the Al ₂ O ₃ component in the oxide particles in the carbon-containing powder is 75 mass% or more.

[Example 4]
In Example 4, 1-bromopropane was used as a hydrophobic solvent, and a carbonaceous powder was recovered from FA according to the separation and recovery method shown in FIG.

Specifically, 250 ml of water and 1-bromopropane (specific gravity: 1.35) were placed in a container, and 35 g of FA (carbon content: 9.3% by mass) was charged. Thereafter, the mixture is stirred at a low speed in a container, and the mixture is subjected to ultrasonic treatment using an ultrasonic vibrator, whereby the treatment for pulverizing the particles in the mixed liquid is performed (pulverization step S5). At this time, an ultrasonic wave of 5,250 kJ/m ^{3 was} given for 3 minutes. After the pulverization treatment, the mixture was transferred to a sealed container (separation funnel), and the closed container (separation funnel) was vigorously shaken by hand for 30 seconds to thoroughly mix FA, water, and 1-bromopropane. After mixing, the closed vessel (separation funnel) was allowed to stand for 10 seconds, and then the 1-bromopropane phase in which unburned carbon was concentrated was recovered, and the aqueous phase was discarded (coarse separation step S21). Further, after the sample near the interface between the 1-bromopropane phase and the aqueous phase was discarded, the aqueous phase in which the oxide was concentrated was recovered, and after filtration, the solid matter was dried and recovered. The recovered 1-bromopropane phase was placed in a closed vessel (separation funnel), and after adding 250 ml of water, the closed vessel (separation funnel) was vigorously shaken by hand for 30 seconds to mix the 1-bromopropane phase with water. . Thereafter, the sealed container (separation funnel) was allowed to stand for 10 seconds, and then the 1-bromopropane phase in which unburned carbon was concentrated was recovered again (water washing step S22). At this time, the sample near the interface between the 1-bromopropane phase and the aqueous phase was not recovered, and was discarded. This water washing step S22 was repeated three times, and the 1-bromopropane phase in which unburned carbon was concentrated was recovered. The recovered 1-bromopropane phase is filtered (solid-liquid separation step S41), and moisture is volatilized with 1-bromopropane by drying (drying step S42) to obtain a carbon-containing powder.

As a result, the carbonaceous powder of Example 4 had a carbon content of 82% by mass and an N/C ratio of 0.0061. Further, the total of the SiO ₂ component and the Al ₂ O ₃ component in the oxide particles in the carbon-containing powder is 75 mass% or more. In addition, it was confirmed that the carbon content in the solid matter recovered from the aqueous phase was 1.2% by mass, which was lower than that in the FA before the treatment, and was compared with Example 2 The carbon content of the solids obtained from the aqueous phase obtained is also reduced.

[Example 5]
In Example 5, trichloroethylene was used as a hydrophobic solvent, and a carbonaceous powder was recovered from FA according to the separation and recovery method shown in FIG.

Specifically, 250 ml of water was placed in a container, and 35 g of FA (carbon content: 10.8 mass%) was charged. Thereafter, the mixed liquid in the vessel was pulverized by a high-speed shear mixer (homogeneizer) for 3 minutes (pulverization step S5). After the pulverization treatment, the mixture was transferred to a closed vessel (separation funnel), 250 ml of trichloroethylene (specific gravity: 1.46) was added, and the closed vessel (separation funnel) was vigorously shaken by hand for 30 seconds to make FA, water and three. The vinyl chloride is thoroughly mixed. After mixing, the sealed container (separation funnel) was allowed to stand for 10 seconds, and then the trichloroethylene phase in which unburned carbon was concentrated was collected and placed in another closed vessel (separation funnel) (crude separation step S21). Further, after the sample near the interface between the trichloroethylene phase and the aqueous phase is discarded, the aqueous phase in which the oxide is concentrated is recovered, and after filtration, the solid matter is dried and recovered. 250 ml of water was added to the recovered trichloroethylene phase, and the closed vessel (separation funnel) was shaken vigorously by hand for 30 seconds, and the trichloroethylene phase and water were mixed, and then the closed vessel (separation funnel) was allowed to stand for 10 seconds. The trichloroethylene phase concentrated with unburned carbon is recovered again (water washing step S22). At this time, the sample near the interface between the trichloroethylene phase and the aqueous phase is not recovered, and is discarded. This water washing step S22 was repeated three times, and the trichloroethylene phase in which unburned carbon was concentrated was recovered. After filtering the trichloroethylene phase (solid-liquid separation step S41), moisture is volatilized with trichloroethylene by drying (drying step S42) to obtain a carbon-containing powder.

As a result, the carbonaceous powder of Example 5 had a carbon content of 87% by mass and an N/C ratio of 0.011. Further, the total of the SiO ₂ component and the Al ₂ O ₃ component in the oxide particles in the carbon-containing powder is 75 mass% or more. In addition, it was confirmed that the carbon content in the solid matter recovered from the aqueous phase was 1.4% by mass, which was lower than that in the FA before the treatment, and was compared with Example 2 The carbon content of the solids obtained from the aqueous phase obtained is also reduced.

[Example 5-1]
In Example 5-1, trichloroethylene was used as a hydrophobic solvent, and a carbonaceous powder was recovered from FA according to the separation and recovery method shown in FIG.

Specifically, 250 ml of water was placed in a container, and 35 g of FA (carbon content: 9.3% by mass) was charged. Thereafter, 100 g of zirconia beads (density: 6.0 g/cm ³ ) were placed, and the mixture was vigorously shaken by hand for 30 seconds to pulverize the FA (pulverization step S5). Further, the diameter of the beads used (hereinafter referred to as the bead diameter D _B ) was changed to be 100, 200, 300, 500, 800, 1000, 1500, 2000, and 3000 μm. After the pulverization treatment, the container was allowed to stand for 5 seconds to precipitate zirconia beads. After recovering the aqueous phase containing the pulverized FA in the upper part of the vessel and moving it to another closed vessel (separation funnel), 250 ml of trichloroethylene (specific gravity: 1.46) was added, and the closed vessel was shaken vigorously by hand (separation funnel) ) 30 seconds to thoroughly mix FA, water and trichloroethylene. After mixing, the sealed container (separation funnel) was allowed to stand for 10 seconds, and then the trichloroethylene phase in which unburned carbon was concentrated was collected and placed in another closed vessel (separation funnel) (crude separation step S21). At this time, the sample near the interface between the trichloroethylene phase and the aqueous phase was discarded. 250 ml of water was added to the recovered trichloroethylene phase, and the closed vessel (separation funnel) was shaken vigorously by hand for 30 seconds, and the trichloroethylene phase and water were mixed, and then the closed vessel (separation funnel) was allowed to stand for 10 seconds. The trichloroethylene phase concentrated with unburned carbon is recovered again (water washing step S22). At this time, the sample near the interface between the trichloroethylene phase and the aqueous phase is not recovered, and is discarded. This water washing step S22 was repeated three times, and the trichloroethylene phase in which unburned carbon was concentrated was recovered. After filtering the trichloroethylene phase (solid-liquid separation step S41), moisture is volatilized with trichloroethylene by drying (drying step S42) to obtain a carbon-containing powder.

As a result, the relationship between the bead diameter D _B as shown in Fig. 12 and the carbon content C _A of the carbonaceous powder was obtained. As shown in Fig. 12, when it is confirmed that the bead diameter D _B is 1000 μm or less, the carbon content C _A in the carbon-containing powder is more than 70%.

[Embodiment 6]
In Example 6, trichloroethylene was used as a hydrophobic solvent, and the carbonaceous powder was recovered from FA according to the separation and recovery method shown in FIG.

Specifically, 250 ml of trichloroethylene (specific gravity: 1.46) was placed in a sealed container, and 35 g of FA (carbon content: 9.3% by mass) was charged. Thereafter, 100 g of zirconia beads (100 μmφ, density: 6.0 g/cm ³ ) were placed, and vigorously shaken by hand for 30 seconds to pulverize the FA (pulverization step S5). After the pulverization treatment, the sealed container was allowed to stand for 5 seconds to precipitate zirconia beads. The trichloroethylene phase containing the pulverized FA in the upper portion of the closed vessel was recovered, and transferred to another closed vessel (separation funnel), and 250 ml of water was added thereto, and the closed vessel (separation funnel) was vigorously shaken by hand for 30 seconds. Mix FA, water and trichloroethylene thoroughly. After mixing, the sealed container (separation funnel) was allowed to stand for 10 seconds, and then the trichloroethylene phase in which unburned carbon was concentrated was collected and placed in another closed vessel (separation funnel) (crude separation step S21). Further, after the sample near the interface between the trichloroethylene phase and the aqueous phase is discarded, the aqueous phase in which the oxide is concentrated is recovered, and after filtration, the solid matter is dried and recovered. 100 ml of water was added to the recovered trichloroethylene phase, and the closed vessel (separation funnel) was vigorously shaken by hand for 30 seconds to mix the trichloroethylene phase with water. Thereafter, after standing in a sealed container (separation funnel) for 10 seconds, the unburned carbon trichloroethylene phase was again recovered (water washing step S22). At this time, the sample near the interface between the trichloroethylene phase and the aqueous phase is not recovered, and is discarded. This water washing step S22 was repeated three times, and the trichloroethylene phase in which unburned carbon was concentrated was recovered. After the recovered trichloroethylene phase is filtered (solid-liquid separation step S41), moisture and trichloroethylene are volatilized by drying (drying step S42) to obtain a carbonaceous powder.

As a result, the carbonaceous powder of Example 6 had a carbon content of 85% by mass and an N/C ratio of 0.0068. Further, the total of the SiO ₂ component and the Al ₂ O ₃ component in the oxide particles in the carbon-containing powder is 75 mass% or more. In addition, it was confirmed that the carbon content in the solid matter recovered from the aqueous phase was 1.0% by mass, which was lower than that in the FA before the treatment, and was compared with Example 2 The carbon content of the solids obtained from the aqueous phase obtained is also reduced.

[Embodiment 7]
In Example 7, trichloroethylene was used as a hydrophobic solvent, and a carbonaceous powder was recovered from FA according to the separation and recovery method shown in FIG.

Specifically, 250 ml of water and trichloroethylene (specific gravity: 1.46) were placed in a closed vessel (separation funnel), and 35 g of FA (carbon content: 9.3% by mass) was charged. The sealed container (separation funnel) was vigorously shaken by hand for 30 seconds to thoroughly mix FA, water and trichloroethylene. After mixing, the sealed container (separation funnel) was allowed to stand for 10 seconds, and then the trichloroethylene phase in which unburned carbon was concentrated was recovered and put into another container (coarse separation step S21). At this time, the sample near the interface between the trichloroethylene phase and the aqueous phase was discarded. Thereafter, the mixture is stirred at a low speed in a container, and the mixture is subjected to ultrasonic treatment using an ultrasonic vibrator, whereby the treatment for pulverizing the particles in the mixed liquid is performed (pulverization step S5). At this time, an ultrasonic wave of 5,250 kJ/m ^{3 was} given for 3 minutes. After the pulverization treatment, the mixture was transferred to a sealed container (separation funnel), and 250 ml of water was added to the mixture in the closed container (separation funnel), and then the closed container (separation funnel) was vigorously shaken by hand for 30 seconds to be mixed. Trichloroethylene phase with water. Thereafter, after standing in a sealed container (separation funnel) for 10 seconds, the unburned carbon trichloroethylene phase was again recovered (water washing step S22). At this time, the sample near the interface between the trichloroethylene phase and the aqueous phase is not recovered, and is discarded. This water washing step S22 was repeated three times, and the trichloroethylene phase in which unburned carbon was concentrated was recovered. After the recovered trichloroethylene phase is filtered (solid-liquid separation step S41), moisture and trichloroethylene are volatilized by drying (drying step S42) to obtain a carbonaceous powder.

As a result, the carbonaceous powder of Example 7 had a carbon content of 86% by mass and an N/C ratio of 0.0081. Further, the total of the SiO ₂ component and the Al ₂ O ₃ component in the oxide particles in the carbon-containing powder is 75 mass% or more.

The results of the above Examples 2 to 5, 6, 7 and Comparative Example 2 are shown in Table 4.

[Table 4]

As shown in Table 4, the carbon content of the carbon-containing powders of Examples 2 to 7 of the present invention was 56 to 87% by mass, which was 50% by mass or more based on the standard. In particular, in Examples 4 to 7 produced by the separation and recovery method with the pulverization step S5, the carbon content was 82% by mass or more, and the higher basis was 70% by mass or more. On the other hand, the carbon content of the carbon-containing powder of Comparative Example 2 was 34% by mass, which was considerably low, and did not satisfy the standard of 50% by mass. According to the result of the separation and recovery method in the production method of the present embodiment, the unburned carbon particles can be appropriately separated from the FA, and the carbonaceous powder having a carbon content of at least 50% by mass or more can be appropriately obtained. .

[Embodiment 8]
In Example 8, the carbonaceous powder (Table 5) was kneaded in coke to be used in the sintering step of the sintering machine to be used as a sintering raw material, which was in the same manner as in Example 2 The same method was obtained from FA (carbon content: 11.8% by mass). The carbonaceous powder in the sintering step was evaluated by a pot test. Further, for comparison, a test using only the coke of the general work was carried out in the same manner as below.

[table 5]

In the pot test, about 50 kg of the sintered raw material was placed in a pot-shaped furnace covered with a refractory, and then ignited on the surface portion, and air suction was performed from below. As a sample of the pot test, the carbonaceous powder (volume specific gravity: 0.32 g/cm) obtained by the same method as in Example 2 was additionally blended with 8 mass% of the scale and 16 mass% of the lime powder. ³ ), made of mixed materials (dry powder). Further, 6% by mass of water was additionally added to the mixed material and kneaded, and then dried at normal temperature to prepare 50 kg of a sintered sample composed of pseudo particles having a diameter of 2 to 5 mm.

The sintered sample was placed in a pot test apparatus to a height of 600 mm, and the atmosphere was sucked at 1500 mmAq by a blower, and fired on the surface layer by an ignition furnace for 90 seconds. The results of the production test of the sintered ore were as shown in Table 6 below. As shown in Table 6, in the case where the carbonaceous powder was kneaded, a block (≧5 mm-mesh) can be obtained in the same yield as the coke (N/C=0.021) which is only a general operation. Sinter. Therefore, it is understood that there is no problem in using the above carbon-containing powder as a sintering raw material. On the other hand, the average concentration of NOx in the exhaust gas generated in the production of the sintered ore is reduced. We believe that this is because the carbonaceous powder is lower in nitrogen in terms of N/C ratio than coke, so the amount of NOx produced can be reduced.

[Table 6]

[Embodiment 9]
In Example 9, carbon-containing powders (Table 6) and other powders (rust skin) obtained in the same manner as in Example 2 were mixed in advance to increase the bulk density. Further, the mixed material is kneaded in coke to be used in the sintering step of the sintering machine to be used as a sintering raw material. The carbonaceous powder in the sintering step was evaluated by a pot test. Further, for comparison, a test using only the coke of the general work was carried out in the same manner as below.

In the pot test, about 50 kg of the sintered raw material was placed in a pot-shaped furnace covered with a refractory, and then ignited on the surface portion, and air suction was performed from below. As a sample of the pot test, the carbonaceous material (volume specific gravity: 0.32 g/cm ³ ) obtained by the same method as in Example 2 was blended with 84% by mass of the scale, 16% by mass of the lime powder, and an additional 8% by mass. ), made of mixed materials (dry powder). When mixing, the carbonaceous material is mixed with a part of the scale in a sealed container in advance (the blending ratio is 4:6 by weight; the bulk specific gravity after mixing: 1.2 g/cm ³ ) to prepare the above mixed material ( Dry powder). Further, 6% by mass of water was additionally added to the mixed material and kneaded, and then dried at normal temperature to prepare 50 kg of a sintered sample composed of pseudo particles having a diameter of 2 to 5 mm.

The sintered sample was placed in a pot test apparatus to a height of 600 mm, and the atmosphere was sucked at 1500 mmAq by a blower, and fired on the surface layer by an ignition furnace for 90 seconds. The results of the production test of the sintered ore were as shown in Table 7 below. As shown in Table 7, even in the case where the scale and the carbonaceous powder were kneaded in advance, the sintering of the bulk (≧5 mm-mesh) can be obtained in the same yield as the coke only in the general operation. mine. Therefore, it is understood that there is no problem in using the above carbon-containing powder as a sintering raw material. On the other hand, in the same manner as in the eighth embodiment, the average concentration of NOx in the exhaust gas generated at the time of producing the sintered ore was reduced. We believe that this is because the carbonaceous powder is lower in nitrogen in terms of N/C ratio than coke, so the amount of NOx produced can be reduced. Further, when a mixed material (dry powder) is produced, dust due to fine carbonaceous materials is less likely to occur, and the working environment can be improved.

[Table 7]

[Embodiment 10]
In Example 10, the specific surface area, the SO ₂ adsorption ability, and the denitration ability were measured for the carbon powder-containing samples obtained in Example 2 and Example 5. The results are shown in Table 8.

Both samples were confirmed to have SO ₂ adsorption capacity and denitrification capacity. When the carbonaceous powder obtained in Example 2 was observed by SEM, a large number of fine pores (less than 2 μm in diameter) were observed. We believe that this is because of the large number of fine pores, which increases the specific surface area of the carbon-containing powder, and further has the SO ₂ adsorption capacity and the denitration ability. Further, in the fine pores, it was observed that a large number of nearly spherical oxide particles entered and blocked the deep portion of the fine pores. According to this, we believe that there is a micropore portion that does not function as an SO ₂ adsorption capacity or a denitration ability. On the other hand, in the carbon-containing powder of Example 5, the specific surface area was increased by about 2 times by pulverization, and the SO ₂ adsorption ability and the denitration ability were increased more. We believe that this is because the spheroidal oxide that has entered the fine pores can be removed by pulverization, and almost all of the fine pores can function as the SO ₂ adsorption capacity and the denitration ability.

[Table 8]

[Example 11]
In Example 11, the carbonaceous powder was recovered from the FA through the countercurrent type multi-stage continuous process shown in FIG. In the test of the eleventh embodiment, the counter-flow type four-stage continuous process of the first stage water washing step (S22_1) is carried out by using the separation and recovery device 5 shown in Fig. 6 (M = 1, N = 4 in Fig. 11). ). The capacities of the mixers 51A, 51B are each 0.3 L. Further, an ascending flow separation device (diameter: 40 mm, height: 300 mm) was used as the settling tanks 52A, 52B. In the mixer 51B of the water washing step (S22_1), water is introduced at 1 L/min, and in the mixer 51A of the fourth-stage crude separation step (S21_4), a bromine-based organic solvent (1) is introduced at 1 L/min. Bromopropane), and in the mixer 51A of the crude separation step (S21_1) of the first stage, the FA was charged at 75 g/min.

In the lower portion of the settling tank 52A and the settling tank 52B, a bromine-based organic solvent phase is formed, and an aqueous phase is formed on the upper portion, and a film of a bromine-based organic solvent phase is formed between the aqueous phase and the air. Approximately 3 cm from the surface portion of the aqueous phase, the aqueous phase was continuously withdrawn at 1 L/min to obtain a sample for analyzing the aqueous phase. On the other hand, a bromine-based organic solvent phase was continuously withdrawn from the lowermost portion of the bromine-based organic solvent phase by about 3 cm upward at 1 L/min to obtain a sample for analyzing the solvent phase. Each sample was deliquored by centrifugation (1,700 G × 30 seconds), dried in a drying oven, and solid matter was recovered. From the above formula (4) and formula (5), the unburned carbon particle separation ratio K _A and the hydrophilic particle recovery ratio K _{B were} calculated. Further, the FA used contained 13% by mass of carbon and had a particle diameter of 200 μm or less.

The test result of the example 11 was that the unburned carbon particle separation ratio K _A was 82% by mass, and the hydrophilic particle recovery ratio K _B was 91% by mass. Further, as shown in FIG. 13, after the crude separation step (S21_4) of the fourth stage, the content C _B of the unburned carbon particles in the solid recovered from the aqueous phase in the first recovery step (S3) is 2.8 mass%. After the water washing step (S22_1), the content C _{A of} the unburned carbon particles in the solid obtained from the bromine-based organic solvent phase in the second recovery step (S4) was 58% by mass. According to the results of the test, it was confirmed that in the reverse-flow type four-stage continuous process of Example 11, the content C _B of the unburned carbon particles in the solid obtained by recovering from the aqueous phase can be made low, and the improvement can be improved. The content ratio of unburned carbon particles in the solid obtained by recovering the bromine-based organic solvent phase is C _A .

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. And it is obvious that any person skilled in the art to which the present invention pertains can make various modifications or modifications within the scope of the technical idea described in the claims, and it is understood that such Technical scope.

4‧‧‧Boiler

5‧‧‧Separation and recovery unit

51A, 51B‧‧‧ Mixer (mixing device)

52A, 52B‧‧‧ Settling tank (separation device)

61‧‧‧1st recovery unit

62‧‧‧2nd recovery unit

71A, 71B, 72A, 72B‧‧ ‧ pump

80A, 80B, 81A, 81B, 82A, 82B, 831, 832, 833, 834, 835, 841, 842, 843, 844, 845 ‧ ‧ pipeline

511A, 511B‧‧ ‧ motor

512A, 512B‧‧‧ stirring blades

611, 621‧‧ ‧ centrifugal separator

612, 622‧‧‧ drying equipment

613, 623‧‧ ‧ condenser

C1, C2‧‧‧ cake

FA‧‧‧ fly ash

FC‧‧‧fuel coal

L1‧‧‧ water

L2‧‧‧hydrophobic solvent (hydrophobic liquid)

P0‧‧‧carbon powder

P1‧‧‧ oxide particles

P2‧‧‧Unburned carbon particles (carbon particles)

P20‧‧‧Pore

P21‧‧‧ fracture surface

Ph1‧‧‧Water phase

Ph2‧‧‧hydrophobic solvent phase (hydrophobic liquid phase)

S0‧‧‧ burning steps

S1‧‧‧Separation and recovery steps

S2‧‧‧ specific gravity separation step

S3‧‧‧First recovery step

S4‧‧‧Second recovery step (recovery step)

S5‧‧‧Smashing step

S21‧‧‧ coarse separation step

S22‧‧‧Water washing steps

S41‧‧‧ Solid-liquid separation step

S42‧‧‧ drying step

Fig. 1A is a front elevational view showing the fly ash before the wet separation treatment according to the first embodiment of the present invention.

Fig. 1B is a cross-sectional view schematically showing fly ash before the wet separation treatment of the embodiment.

Fig. 2A is a front view schematically showing a carbonaceous powder after the wet separation treatment of the embodiment.

Fig. 2B is a cross-sectional view schematically showing the carbonaceous powder after the wet separation treatment of the embodiment.

Fig. 3A is a front view schematically showing a carbonaceous powder after a pulverization treatment and a wet separation treatment according to a second embodiment of the present invention.

Fig. 3B is a cross-sectional view schematically showing the carbonaceous powder after the pulverization treatment and the wet separation treatment of the embodiment.

Fig. 4 is a flow chart showing an outline of a method for producing a 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 a carbonaceous powder according to the embodiment.

Fig. 6 is a schematic view showing the separation and recovery apparatus of the embodiment.

FIG. 7 is a flow chart showing a separation and recovery method in the method for producing a carbon-containing powder according to the second embodiment of the present invention.

Fig. 8 is a flow chart showing a modified example of the separation and recovery method of the embodiment.

Fig. 9 is a flow chart showing a modified example of the separation and recovery method of the embodiment.

Fig. 10 is a flow chart showing a modified example of the separation and recovery method of the embodiment.

Fig. 11 is a flow chart showing a separation and recovery method using a countercurrent type multi-stage continuous process according to a third embodiment of the present invention.

Figure 12 is a graph showing the relationship between the diameter of beads of Example 5-1 of the present invention and the carbon content of carbonaceous powder.

Fig. 13 is a graph showing changes in the content of unburned carbon particles in the solid phase of the aqueous phase or the solvent phase in each of the stages of the countercurrent four-stage continuous process of the eleventh embodiment of the present invention.

Claims (18)

A carbon-containing powder containing carbon particles and oxide particles; wherein the carbon content of the carbon-containing powder is 50% by mass or more and 95% by mass or less, and the oxide particles are composed of a SiO ₂ component or Al _{2 .} a particle composed of a compound of the O ₃ component or a compound of the two, and the total content of the SiO ₂ component and the Al ₂ O ₃ component in the oxide particle is 75 mass% or more; and the carbon particle A porous particle having a plurality of pores is formed, and at least a part of the oxide particles are present in pores of the carbon particles. The carbonaceous powder according to claim 1, wherein the carbon component content in the carbonaceous powder is 70% by mass or more and 95% by mass or less. The carbonaceous powder according to claim 1 or 2, wherein a mass ratio of the nitrogen component contained in the carbonaceous powder to the carbon component, that is, an N/C ratio, is more than 0 and not more than 0.02. The carbonaceous powder according to any one of claims 1 to 3, wherein the particle diameter of the oxide particles is 1 to 20 μm in terms of a volume-based 50% particle diameter. The carbonaceous powder according to any one of claims 1 to 4, wherein the average value of the roundness of the oxide particles is greater than 0.9 and less than 1. The carbonaceous powder according to any one of claims 1 to 5, wherein a content of the SiO ₂ component in the oxide particles is 50% by mass or more and 80% by mass or less, and the foregoing in the oxide particles The content of the Al ₂ O ₃ component is 10% by mass or more and 30% by mass or less. The carbonaceous powder according to any one of claims 1 to 6, wherein the carbonaceous powder has a specific surface area of 50 to 300 m ² /g. a separation method for separating carbon particles and oxide particles from a mixture, and the mixture is derived from fly ash and mixed with carbon particles and oxide particles; The method includes the following steps: a mixing step of mixing the mixture, water, and a hydrophobic liquid having a specific gravity greater than that of the water to form a mixed liquid; In the specific gravity separation step, the mixed liquid is allowed to stand, and is separated into a hydrophobic liquid phase containing the carbon particles and an aqueous phase containing the oxide particles, thereby separating the carbon particles and the oxide particles. The separation method of claim 8, further comprising a first recovery step of separating the water from the aqueous phase which has been separated in the specific gravity separation step, thereby recovering the oxide particles. The separation method of claim 8 or 9, further comprising a second recovery step of separating the hydrophobic liquid from the hydrophobic liquid phase separated in the gravity separation step, thereby recovering In the carbon powder, the carbon powder contains the carbon particles and the oxide particles, and the carbon content of the carbon powder is 50% by mass or more and 95% by mass or less, and the oxide particles are made of SiO. ₂ Al or any component particles ₂ O ₃ component in one of or both of the compound, in a total ₂ O ₃ component of the oxide particles and the SiO ₂ component and the Al content ratio at 75 mass% or more And the carbon particles are porous particles in which a plurality of pores are formed, and at least a part of the oxide particles are present in the pores of the carbon particles. The separation method of claim 10, wherein the mass ratio of the nitrogen component contained in the carbon-containing powder to the carbon component, that is, the N/C ratio is 0.02 or less. The separation method according to any one of claims 8 to 11, wherein the combination of the mixing step and the gravity separation step is repeated in multiple stages by a countercurrent multi-stage continuous process. The separation method according to any one of claims 8 to 12, further comprising a pulverizing step of either or both of the hydrophobic liquid or the water before the gravity separation step or in the gravity separation step The mixture of the mixture and the mixture is pulverized to pulverize the carbon particles contained in the mixture. The separation method of claim 13, wherein in the pulverizing step, the carbon particles contained in the mixed liquid are pulverized by a pulverization treatment using beads. The separation method according to any one of claims 8 to 14, wherein the fly ash is produced by burning coal, The carbon particles are particles of unburned carbon remaining in the combustion state, and The oxide particles are particles in which the ash of the coal carbon is melted into particles during the combustion. The separation method according to any one of claims 8 to 15, wherein the aforementioned specific gravity separation step comprises the following steps: The coarse separation step is carried out by allowing the mixed liquid to stand to separate into a hydrophobic liquid phase containing the carbon particles and an aqueous phase containing the oxide particles; The water washing step is carried out by adding water to the hydrophobic liquid phase separated in the crude separation step, and then allowing the mixed liquid of the hydrophobic liquid phase and water to be separated, thereby separating it into the carbon-containing particles. A hydrophobic liquid phase and an aqueous phase containing the aforementioned oxide particles. A method for utilizing a carbonaceous powder by using the carbonaceous powder according to any one of claims 1 to 7 in place of the coal used in a sintering machine, a furnace or a converter, or as a SO ₂ adsorbent Or denitrification material. The method for using a carbonaceous powder according to claim 17, wherein the carbonaceous powder is mixed with the other carbon powder to increase the volume specific gravity of the carbonaceous powder.