JP7215199B2 - Separation method, hydrophilic particle recovery method, and hydrophobic particle recovery method - Google Patents

Description

The present invention provides a separation method for rapidly and efficiently separating hydrophobic particles and hydrophilic particles from a mixture of hydrophobic particles and hydrophilic particles, and hydrophilic particles using the separation method. The present invention relates to a recovery method and a recovery method for hydrophobic particles.

Fly ash generated during power generation at a coal-fired thermal power plant or the like is recycled into raw materials for concrete, building materials, cement, and the like. However, fly ash contains unburned carbon, which is a carbon component remaining after burning, in ash composed of metal oxides such as Al ₂ O ₃ and SiO ₂ . Therefore, in order to improve the quality of recycled fly ash, it is preferable to separate and remove unburned carbon contained in fly ash.

As methods for separating unburned carbon in fly ash, for example, an electrostatic separation method and a flotation method are known. The electrostatic separation method is a method in which fly ash is put into parallel plate electrodes in a dry state, and charged unburned carbon is attracted to the positive electrode side and separated. In addition, in the flotation method, unburned carbon particles are attached to micro-air generated using a foaming agent in fly ash slurry through a collector such as kerosene, thereby removing unburned carbon particles. It is a method of floating and separating.

For example, Patent Literature 1 discloses a method of removing unburned carbon in fly ash by flotation. In the flotation method of Patent Document 1, first, by stirring fly ash slurried by adding water, activation energy is generated on the surface of the unburned carbon particles to make the unburned carbon particles lipophilic. (Hydrophobic). Next, a scavenger such as kerosene or light 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 generated bubbles are covered with the unburned carbon. is attached and floated. By such a flotation method, a mixture of unburned carbon (specific gravity: 1.3 to 1.5), which is a hydrophobic particle, and metal oxide (specific gravity: 2.4 to 2.6), which is a hydrophilic particle, Unburned carbon is separated from some fly ash.

JP 2007-167825 A

However, in the flotation method in which unburned carbon contained in fly ash is adhered to 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.

Specifically, in the flotation method described in Patent Document 1, as shown in FIG. 18, water and fly ash are mixed and stirred, and many metal oxide 102 particles are suspended in the water. In phase 105 , particles of unburned carbon 101 adhere to fine air bubbles 103 via collector 104 , and unburned carbon 101 floats in water phase 105 together with air bubbles 103 . At this time, the unburned carbon 101 may be separated from the air bubbles 103 , and the unburned carbon 101 gradually floats while repeating floating and settling in the water phase 105 and gathers on the surface layer of the water phase 105 . Therefore, since the separation speed of the unburned carbon 101 is slow, in order to separate the unburned carbon 101 from the metal oxide 102 and reduce the content of the unburned carbon 101 to the target value or less, it takes about 1 hour, for example. It takes a long time.

In addition, in the flotation method, the separation efficiency of the unburned carbon 101 depends on the particle size and degree of hydrophobicity of the unburned carbon 101 (these depend on the type of coal used), the existence form of the unburned carbon 101, etc. receive a considerable amount of For example, if the particles of the unburned carbon 101 are large, not only does it become difficult for the unburned carbon 101 to adhere to the air bubbles 103 due to its own weight, but it also becomes difficult for the unburned carbon 101 to float in the water phase 105 . Furthermore, when the unburned carbon 101 is present in the metal oxide 102, the surface portion of the unburned carbon 101 to which the air bubbles 103 can adhere becomes smaller, so the unburned carbon 101 is less likely to adhere to the air bubbles 103. Become. Due to these causes, the separation speed of the unburned carbon 101 decreases, the separation efficiency of the unburned carbon 101 deteriorates, and in many cases the content of the unburned carbon 101 in the mixture cannot be reduced to the target value, and the processing cost is also increased. it was high.

In the above, the problem of floating unburned carbon from fly ash, which is a mixture of unburned carbon (hydrophobic particles) and metal oxides (hydrophilic particles), was described, but other hydrophobic particles Similar problems can arise even when separating individual particles from a mixture of hydrophilic and hydrophilic particles.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to separate hydrophobic particles and hydrophilic particles from a mixture in which hydrophobic particles and hydrophilic particles are mixed. The object is to improve separation efficiency.

In order to solve the above problems, according to one aspect of the present invention,
In a separation method for separating hydrophobic particles and hydrophilic particles from a mixture in which hydrophobic particles and hydrophilic particles are mixed,
A mixing step of mixing the mixture with water and a hydrophobic liquid having a higher specific gravity than the water to form a slurry;
While separating the slurry produced in the mixing step into an aqueous phase and a hydrophobic liquid phase, the hydrophilic particles are transferred to the aqueous phase and the hydrophobic particles are transferred to the hydrophobic liquid phase. , a separation step of separating the hydrophobic particles and the hydrophilic particles;
wherein the combination of the mixing step and the separation step is repeated N stages (where N is an integer of 2 or more) by a countercurrent multistage continuous process .

In the separation step, the slurry is allowed to stand still in a separation device, and the slurry is divided into the aqueous phase containing the hydrophilic particles and the hydrophobic liquid containing the hydrophobic particles by using the difference in specific gravity. You may make it isolate|separate into a phase.

N is an integer of 3 or more,
The mixture and the water are added in the mixing step of the first stage,
The hydrophobic liquid is introduced in the mixing step of the Nth stage,
The aqueous phase containing the hydrophilic particles and the remaining hydrophobic particles separated in the separation step of the n-th stage (n is an integer of 1 or more and N-2 or less), and the separation step of the n+2 stage The separated hydrophobic particles and the hydrophobic liquid phase containing the remaining hydrophilic particles may be mixed in the mixing step (n+1) to form a slurry.

further comprising a washing step of removing the hydrophilic particles remaining in the hydrophobic liquid phase containing the hydrophobic particles separated in the first separation step;
The washing step includes
a cleaning mixing step of adding and mixing the water to the hydrophobic liquid phase containing the hydrophobic particles separated in the first separation step and the remaining hydrophilic particles to form a slurry;
While separating the slurry generated in the mixing step for washing into an aqueous phase and a hydrophobic liquid phase, the remaining hydrophilic particles are moved to the aqueous phase, whereby the hydrophobic particles and the remaining hydrophilic particles are separated from each other. a cleaning separation step for separating the sexual particles;
may be included.

The combination of the washing mixing step and the washing separation step in the washing step may be repeated M steps (M is an integer of 2 or more).

a first recovery step of separating the water from the aqueous phase containing the hydrophilic particles separated by the separation step and recovering the hydrophilic particles;
a second recovery step of separating the hydrophobic liquid from the hydrophobic liquid phase containing the hydrophobic particles separated by the separation step and recovering the hydrophobic particles;
further comprising
The water separated in the first recovery step and the hydrophobic liquid separated in the second recovery step may be reused in the mixing step.

In the first collection step,
The hydrophobic liquid remaining in the aqueous phase is removed by subjecting the aqueous phase containing the hydrophilic particles separated by the separation step to at least one of heating and decompression. You may do so.

A magnetic separation step may be further included in which magnetic substances mixed in the mixture are separated by adsorption using a magnet.

the hydrophobic liquid is a hydrophobic organic solvent,
The specific gravity of the hydrophobic organic solvent may be greater than 1.05 and smaller than the specific gravity of the hydrophobic particles.

the hydrophobic liquid is a hydrophobic organic solvent,
The boiling point of the hydrophobic organic solvent may be 40° C. or higher and 150° C. or lower under atmospheric pressure.

the hydrophobic liquid is a hydrophobic organic solvent,
The boiling point of the hydrophobic organic solvent may be 40° C. or higher and 95° C. or lower under atmospheric pressure.

The hydrophilic particles are metal oxides,
The hydrophobic particles may be coke dust or coal dust.

The mixture may be fly ash.

The mixture is fly ash, and the method may further include a pulverization step of pulverizing the fly ash prior to the separation step.

In the pulverization step, at least one of a hydrophobic liquid and water is mixed with the fly ash to generate a mixed liquid, and the carbon particles as the hydrophobic particles contained in the mixed liquid are pulverized using beads. You may do so.

The beads may have a diameter of 1 mm or less.

Also, in order to solve the above problems, according to another aspect of the present invention,
A method for recovering hydrophilic particles is provided, comprising recovering the hydrophilic particles from the aqueous phase containing the hydrophilic particles separated by the separation method.

Also, in order to solve the above problems, according to another aspect of the present invention,
A hydrophilic particle recovery method is provided, comprising recovering the aqueous phase containing the hydrophilic particles separated by the separation method.

Also, in order to solve the above problems, according to another aspect of the present invention,
A method for recovering hydrophobic particles is provided, comprising recovering the hydrophobic particles from the hydrophobic liquid phase containing the hydrophobic particles separated using the separation method.

As described above, according to the present invention, it is possible to improve the separation speed and separation efficiency when separating hydrophobic particles and hydrophilic particles from a mixture in which hydrophobic particles and hydrophilic particles are mixed.

FIG. 4 is a schematic diagram showing the state of the mixed liquid immediately after mixing and stirring the mixture containing the hydrophobic particles and the hydrophilic particles with water and the hydrophobic organic solvent in the separation method according to the first embodiment of the present invention. FIG. 4 is a schematic diagram showing an example of a state after the mixed liquid is left to stand for about 1 to 30 seconds in the separation method according to the present embodiment. FIG. 4 is a schematic diagram showing an example of a state after the mixed liquid is left to stand for 30 seconds or more in the separation method according to the present embodiment. FIG. 10 is a schematic diagram showing another example of the state after the mixed liquid has been allowed to stand for 30 seconds or longer in the separation method according to the present embodiment. It is the graph which showed the relationship between slurry density _| concentration CS of an aqueous phase, and slurry specific gravity _dS . 4 is a graph showing the relationship between the particle diameter φ _P of hydrophilic particles and the apparent specific gravity d _P of water-coated particles. It is a schematic diagram showing the particle separation device according to the same embodiment and a single-stage continuous process using it. It is a schematic diagram which shows the particle separation apparatus which concerns on the modification of the same embodiment, and a single stage continuous process using the same. It is a schematic diagram which shows the cross-flow separation apparatus which concerns on the same embodiment. It is a schematic diagram which shows the upflow-type separator which concerns on the example of a change of the same embodiment. FIG. 4 is a schematic diagram showing a countercurrent two-stage continuous process using a particle separator according to a second embodiment of the present invention. It is process drawing which shows the separation method by N stage|countercurrent type|mold multistage continuous process which concerns on the same embodiment. FIG. 4 is a process chart showing a separation method by a countercurrent multistage continuous process to which a washing step is added according to the same embodiment. FIG. 4 is a process diagram showing a separation method by a countercurrent multistage continuous process in which washing processes are performed in multiple stages according to the same embodiment. FIG. 3 is a schematic diagram showing a countercurrent two-stage continuous process including a magnetic separation step according to a third embodiment of the present invention; 4 is a graph showing changes in content of hydrophobic particles in each stage of a countercurrent three-stage continuous process according to an example of the present invention. 4 is a graph showing changes in content of hydrophobic particles in each stage of a countercurrent four-stage continuous process including a washing step according to an example of the present invention. 4 is a graph showing changes in content of hydrophobic particles in each stage of a countercurrent four-stage continuous process including a washing step according to an example of the present invention. It is a schematic diagram which shows the floating principle of the unburned carbon in the conventional flotation method.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

[1. Target of Separation Method]
First, the mixture, hydrophilic particles, hydrophobic particles, hydrophobic liquid, etc. to be processed by the separation method according to the first embodiment of the present invention will be described.

Table 1 shows examples of objects to be processed (mixture of hydrophilic particles and hydrophobic particles) of the separation method according to the present embodiment. As shown in Table 1, for example, fly ash and blast furnace gas ash to be treated include particles of metal oxides (Al ₂ O ₃ , SiO ₂ , Fe ₂ O ₃ etc.) which are hydrophilic particles, and hydrophobic particles. It is a mixture in which unburned carbon particles (coal powder or the like) are mixed. In addition, the coal to be treated is carbon particles (coke powder, coal powder, etc.), which are hydrophobic particles, and particles of metal oxides (Al ₂ O ₃ , SiO ₂ , etc.), which are hydrophilic particles, are mixed. A mixture.

More specifically, most fly ash contains approximately 90 to 95 mass % of oxide particles, which are hydrophilic particles, and approximately 5 to 10 mass % of unburned carbon, which is hydrophobic particles. The particle size of fly ash is about 1-200 μm. Some particles in fly ash exist as particles in which carbon and metal oxide are integrated.

Blast furnace gas ash is collected dust of raw materials charged into the blast furnace, dust generated by metallurgical reaction in the blast furnace, in other words, blast furnace dust ash, and contains 15 to 30% by mass of carbon as a component. include. The particle size of blast furnace gas ash is about 1 to 200 μm. Examples of blast furnace gas ash components are shown in Table 2 below. Blast furnace gas ash contains coke-derived carbon as hydrophobic particles. Further, the blast furnace gas ash contains multiple kinds of metal oxides shown in Table 2 as hydrophilic particles. Some particles in blast furnace gas ash exist as particles in which carbon and metal oxides are integrated.

In the present embodiment, hydrophilic particles (eg, metal oxide) and hydrophobic particles (eg, carbon) are separated and recovered from the mixture of hydrophilic particles and hydrophobic particles as described above. As a result, metal oxides can be reused, for example, as raw materials for concrete (aggregates, admixtures, etc.) and building materials, and carbon can be reused, for example, as coal for power generation, iron manufacturing, and cement clinker. used. At this time, if the carbon content in the recovered metal oxide can be reduced to, for example, 3% by mass or less, the ignition loss ( (almost the same as the content of unburned carbon), and by adjusting other quality regulations such as fineness, it becomes possible to recycle the metal oxide as fly ash for concrete for a fee, and furthermore, it is used for recycling. also extend.

Next, the hydrophobic liquid used in the separation method according to this embodiment will be described. A hydrophobic liquid is a liquid having hydrophobicity, that is, a liquid having low affinity for water (hardly soluble in water or difficult to mix with water). A hydrophobic liquid is, for example, a liquid whose solubility in water at 20° C. is 0 g/L or more and 5.0 g/L or less. In addition, hydrophobicity in this specification is a property including lipophilicity. The hydrophobic liquid may be, for example, a hydrophobic organic solvent (hereinafter referred to as “hydrophobic organic solvent”) or various oils. Hydrophobic liquids have a low affinity for water, so when a mixed liquid obtained by mixing and stirring a hydrophobic liquid and water is allowed to stand, an aqueous phase mainly composed of water and a hydrophobic liquid (for example, a hydrophobic organic solvent) are separated. It separates into two phases, a predominantly hydrophobic liquid phase (eg, a hydrophobic organic solvent phase).

Furthermore, in this embodiment, a liquid having a specific gravity greater than that of water, that is, a liquid having a specific gravity greater than 1 is used as the hydrophobic liquid. By using a hydrophobic liquid with a higher specific gravity than water, when the mixture of the hydrophobic liquid and water is stirred and then allowed to stand still, the difference in specific gravity between the two liquids causes the upper water phase and the lower hydrophobic liquid phase to separate. is separated into

Table 3 shows examples of hydrophobic liquids used in the separation method according to this embodiment. As shown in Table 3, the hydrophobic liquid may be, for example, a fluorine-, bromine-, or chlorine-based organic solvent, or an oil such as silicone oil. All of the hydrophobic liquids exemplified in Table 3 have a specific gravity of more than 1, a solubility in water of 5 g/L or less, and are hydrophobic.

Preferably, the hydrophobic liquid has a specific gravity greater than 1.05. As a result, after mixing water (specific gravity 1) and a hydrophobic liquid and standing still, it can be rapidly separated into two phases, an aqueous phase and a hydrophobic liquid phase, in a short period of time, for example, about 1 to 30 seconds. can be increased. Also, the specific gravity of the hydrophobic liquid is preferably smaller than the specific gravity of the hydrophobic particles (for example, 1.2 to 1.8). As a result, in the step of separating and recovering the hydrophobic particles from the hydrophobic liquid phase containing the hydrophobic particles, the hydrophobic liquid and the hydrophobic particles can be efficiently separated using the solid-liquid separation device. , the details of which will be described later.

Next, hydrophilic particles and hydrophobic particles will be described. Hydrophilic particles are particles that have an affinity for water, and have the property of being more easily mixed with water than the hydrophobic liquid. On the other hand, hydrophobic particles are particles that have an affinity for the hydrophobic liquid, and have the property of being more easily mixed with the hydrophobic liquid than with water. Therefore, in a mixture of water and a hydrophobic liquid, the hydrophilic particles migrate from the hydrophobic liquid phase to the aqueous phase and are dispersed mainly in the aqueous phase. On the other hand, the hydrophobic particles migrate from the aqueous phase to the hydrophobic liquid phase and mainly exist dispersedly in the hydrophobic liquid phase.

Hydrophilic particles are, for example, particles of metal oxides such as Al ₂ O ₃ , SiO ₂ , Fe ₂ O ₃ as shown in Table 1 above, but particles having hydrophilicity may be of other materials. may be particles of On the other hand, the hydrophobic particles are, for example, coal powder such as unburned carbon, coke powder, plastic powder, or the like, but may be particles of other materials as long as they are hydrophobic particles. The particle size of the hydrophilic particles targeted by the present embodiment is 500 μm or less, preferably 200 μm or less. The particle size of the hydrophobic particles is 500 μm or less. Details will be described later.

The content of hydrophilic particles and the content of hydrophobic particles contained in the mixture, which is the object to be treated, are not particularly limited, but, for example, the content of hydrophilic particles in the mixture is 5 to 97% by mass. Well, the content of hydrophobic particles may be about 3 to 95% by mass. However, the total content of the hydrophilic particles and the hydrophobic particles 6 is 100% by mass or less. When the hydrophobic particles are carbon, for example when the mixture is fly ash or blast furnace gas ash, the ignition loss rate can be measured and taken as the hydrophobic particle content. The ignition loss rate is the mass reduction rate when a sample dried at 105° C. is held in an atmospheric furnace set at 975° C. for 15 minutes or more. In addition, when the hydrophobic particles are plastic, for example, polyethylene terephthalate powder or vinyl chloride resin powder, the carbon content in the sample is measured by, for example, the combustion-infrared absorption method, and the carbon content of each plastic is determined. The converted value can be used as the content of the hydrophobic particles. In the above combustion-infrared absorption method, the sample is covered with a combustion improver (pure iron powder and tungsten powder), heated and burned in a high-frequency furnace, the carbon component in the sample is gasified into CO ₂ , and the generated CO This is a method for measuring the carbon content in a sample from _two amounts.

Also, as shown in Table 1, the specific gravity of the hydrophilic particles is, for example, 2.4 to 2.6 (Al ₂ O ₃ , SiO ₂ ) and 4 to 5 (Fe ₂ O ₃ ). The specific gravity of the hydrophobic particles is, for example, 1.2-1.8. When the hydrophobic particles are carbon particles, the carbon particles have a specific gravity of, for example, 1.3 to 1.5. Even if the specific gravity of the hydrophobic particles is smaller than the specific gravity of the hydrophilic particles, according to the separation method according to the present embodiment, as described later, the hydrophilic particles are added to the upper aqueous phase. and allow the hydrophobic particles to settle in the lower hydrophobic liquid phase for rapid and efficient wet separation of both particles. In the present specification, the specific gravity of particles is the specific gravity (true specific gravity) of the particles themselves, not the bulk specific gravity of the particles.

[2. Overview of Separation Method]
Next, an outline of a method for separating hydrophilic particles and hydrophobic particles from a mixture according to this embodiment will be described.

The separation method according to the present embodiment separates hydrophilic particles and hydrophilic particles from a mixture (e.g., fly ash) in which hydrophilic particles (e.g., metal oxides) and hydrophobic particles (e.g., unburned carbon) are mixed. It is a wet separation method.

In this separation method, water is used as an extractant for hydrophilic particles, and a hydrophobic liquid having a higher specific gravity than water is used as an extractant for hydrophobic particles. Then, the water and the hydrophobic liquid are mixed with the mixture (solid content) to be treated and stirred to generate a mixed liquid (first slurry) in which the mixture is dispersed (mixing step). Next, by allowing the mixed solution to stand still in a separation device (e.g., a settler such as a sedimentation tank or a stationary tank), the mixed solution is separated from the upper aqueous phase using the difference in specific gravity between water and the hydrophobic liquid. and the lower hydrophobic liquid phase, the hydrophilic particles are moved to the aqueous phase and the hydrophobic particles are moved to the hydrophobic liquid phase (separation step). In the case of processing a small amount of a mixture, etc., instead of a settler, various containers such as a beaker may be used as a separation device to allow the mixed liquid to stand and separate it into an aqueous phase and a hydrophobic liquid phase. can. Furthermore, from the aqueous phase (second slurry) separated in the separation step, the hydrophilic particles are separated and recovered (first recovery step), and the hydrophobic liquid phase (third slurry) separated in the separation step ), the hydrophobic particles are separated and recovered (second recovery step). As a result, the hydrophilic particles and the hydrophobic particles can be quickly and efficiently separated, and the hydrophilic particles and the hydrophobic particles having a high content can be recovered and reused. The separation method will be described in detail below.

[2.1. Separation principle and effect]
Here, the principle of the separation method according to this embodiment will be described with reference to FIGS. 1 and 2. FIG. The specific gravities of the hydrophobic particles and the hydrophilic particles are assumed to be greater than 1. A hydrophobic organic solvent is used as the hydrophobic liquid. Further, hereinafter, "hydrophobic organic solvent" may be referred to as "hydrophobic solvent" or simply "solvent" or the like, and "hydrophobic organic solvent phase" may be referred to as "hydrophobic solvent phase" or simply "solvent phase". be.

In FIG. 1, water and a hydrophobic organic solvent are added to a mixture containing hydrophobic particles and hydrophilic particles, and immediately after vigorous stirring, the mixed liquid (first slurry) of the mixture, water, and hydrophobic organic solvent is on the upper side. It shows a state of separation into an aqueous phase 1 and a hydrophobic organic solvent phase 2 on the lower side. FIG. 2 shows that the mixture was separated into an aqueous phase 1 containing hydrophilic particles 5 and a hydrophobic organic solvent phase 2 containing hydrophobic particles 6 by standing still for about 1 to 30 seconds after the stirring. Indicates status.

As shown in FIG. 1, immediately after stirring the mixed liquid, droplets 3 of a hydrophobic organic solvent (hereinafter sometimes referred to as "solvent droplets 3" or simply "droplets 3") are present in the aqueous phase 1. ) are present, and water droplets 4 are present in the hydrophobic organic solvent phase 2 . The inside of the solvent droplet 3 contains hydrophobic particles 6 , and the hydrophobic particles 6 adhere to the surface of the solvent droplet 3 . On the other hand, the inside of the water droplet 4 contains hydrophilic particles 5 , and the hydrophilic particles 5 adhere to the surface of the water droplet 4 . The solvent droplets 3 and the water droplets 4 often have a diameter of, for example, 0.5 mm or more, depending on the strength of stirring the mixed liquid.

The specific gravity of water is 1, and the specific gravity of the hydrophobic organic solvent is 1.05-1.8. The sedimentation velocity of the solvent droplets 3 (diameter 0.5 mm) in the water phase 1 is, for example, about 0.05 to 0.1 m/sec, which is very high, although the specific gravity and viscosity of the water and the hydrophobic organic solvent also affect the viscosity. , and the sedimentation velocity of the hydrophobic particles 6 adhering to the solvent droplets 3 is also large. In addition, although the specific gravity and viscosity of water and the hydrophobic organic solvent are also affected, the floating speed of the water droplet 4 (diameter 0.5 mm) in the hydrophobic organic solvent phase 2 is, for example, about 0.1 to 0.2 m/ sec, which is very large, and the floating speed of the hydrophilic particles 5 adhering to the water droplets 4 is also large.

In the aqueous phase 1 , most of the hydrophobic particles 6 adhere to the solvent droplets 3 or are taken inside the solvent droplets 3 . However, the water phase 1 also contains a small amount of the hydrophobic particles 6 that could not adhere to the solvent droplets 3 . A thin liquid film (for example, about 5 to 20 μm) of a hydrophobic organic solvent having a higher specific gravity than water adheres to the surface of the hydrophobic particles 6 . Therefore, the apparent specific gravity of the hydrophobic particles 6 to which the liquid film of the hydrophobic organic solvent is adhered is an intermediate specific gravity between the specific gravity of the hydrophobic solvent and the specific gravity of the hydrophobic particles 6 . Therefore, the apparent particle size (including liquid film thickness) increases due to the liquid film of the hydrophobic organic solvent adhering to the surfaces of the hydrophobic particles 6 . Therefore, in the aqueous phase 1, the hydrophobic particles 6 to which the hydrophobic organic solvent is adhered tend to settle, and the settling speed increases.

On the other hand, in the hydrophobic organic solvent phase 2, there are also a few hydrophilic particles 5 that could not adhere to the water droplets 4. FIG. A thin water film (for example, about 5 to 20 μm) is attached to the surface of the hydrophilic particles 5 . Since the specific gravity of water is smaller than that of the hydrophobic organic solvent, the apparent specific gravity of the hydrophilic particles 5 coated with the water film (hereinafter sometimes referred to as "water-coated particles 5") is It is smaller than the specific gravity of 5 itself. Therefore, when the thickness of the adhered water film is constant, if the apparent particle diameter of the water film particles 5 (the combined particle diameter of the hydrophilic particles 5 and the water film) is small, the water film particles 5 are hydrophobic. While floating from the organic solvent phase 2 to the aqueous phase 1 , the water-coated particles 5 in the hydrophobic organic solvent phase 2 settle in the hydrophobic organic solvent phase 2 if the apparent particle size is large.

As described above, in the separation method according to the present embodiment, in the aqueous phase 1 shown in FIG. 6 settles rapidly from the aqueous phase 1 to the hydrophobic organic solvent phase 2. Furthermore, in the hydrophobic organic solvent phase 2 shown in FIG. surface.

Therefore, in the present embodiment, after mixing and stirring the mixture to be separated with water and a hydrophobic organic solvent, the mixture is allowed to stand, for example, in a short time of about 1 to 30 seconds. As shown in 2, the mixture is separated into an upper aqueous phase 1 and a lower hydrophobic organic solvent phase 2. Along with the separation of the upper and lower liquid phases, the hydrophobic particles 6 sediment at a high sedimentation velocity and move to the hydrophobic organic solvent phase 2 . On the other hand, the hydrophilic particles 5 float at a high floating speed and move quickly to the water phase 1 . Therefore, the hydrophilic particles 5 and the hydrophobic particles 6 can be quickly separated.

Here, in the conventional flotation method described in Patent Document 1, instead of using a large amount of hydrophobic organic solvent as in the present embodiment, a small amount of a collector such as kerosene or light oil and a foaming agent was used to attach hydrophobic particles (unburned carbon 101) having a relatively small specific gravity to air bubbles 103 and float them (see FIG. 18). At this time, the amount of the trapping agent and foaming agent added to the water is very small, about several percent by mass with respect to the mass of the fly ash. However, in such a conventional method, when the particle diameter of the unburned carbon 101 is large, even if the unburned carbon 101 adheres to the air bubble 103, it is easy to separate from the air bubble 103, so that it is difficult to float and separate. In this conventional method, air bubbles are attached to the unburned carbon 101 which is about to settle, and the unburned carbon 101 is forced to float against the force of gravity. For this reason, the floating speed is very slow, and it takes about an hour to reduce the unburned carbon content to a low content (for example, 3% by mass or less). In some cases, the content of unburned carbon 101 in the oxide) cannot be reduced to a target value or less (for example, 3% by mass or less), resulting in poor separation efficiency.

On the other hand, in the separation method according to the present embodiment, a hydrophobic organic solvent having a higher specific gravity than water is used in a large amount to the same extent as water, and the separation action between the hydrophobic organic solvent and water is used. , to separate the hydrophilic particles 5 and the hydrophobic particles 6 . That is, by surely contacting a large amount of the hydrophobic organic solvent and the hydrophobic particles 6, the hydrophobic particles 6 having a relatively small specific gravity (for example, specific gravity: 1.3 to 1.5) are formed into the solvent droplets 3. etc., and incorporated into the lower hydrophobic organic solvent phase 2 (for example, specific gravity: more than 1.05 and 1.8 or less). On the other hand, hydrophilic particles 5 having a relatively large specific gravity (for example, specific gravity: 2.4 to 2.6) are floated together with water droplets 4 and incorporated into the upper aqueous phase 1 (specific gravity: 1). Even if the specific gravity of the hydrophobic particles 6 is greater than the specific gravity of the hydrophilic particles 5, the hydrophilic particles 5 and the hydrophobic particles 6 can be separated from each other by using water and a hydrophobic organic solvent of about the same amount as described above. It is possible to separate

Furthermore, in the separation method according to the present embodiment, as described later, the hydrophobic organic solvent used in the separation step is recovered by the subsequent recovery step such as solid-liquid separation and distillation treatment, and recycled to the mixing step and the separation step. use. As a result, a large amount of the hydrophobic organic solvent can be recycled in the mixing process and the separation process, so that the probability of contact between the hydrophobic particles 6 and the hydrophobic organic solvent is very high during these processes. Furthermore, since the hydrophobic particles 6 having a specific gravity greater than 1 and the hydrophobic organic solvent having a specific gravity greater than 1 adhere to each other, the hydrophobic particles 6 can be more easily sedimented.

Therefore, the separation method according to the present embodiment efficiently separates the hydrophobic particles 6 (for example, unburned carbon) into the hydrophobic organic solvent phase 2 compared to the conventional flotation method described in Patent Document 1. can be separated, and the ability to separate the hydrophobic particles 6 from the mixture is excellent. Therefore, the separation speed of the hydrophobic particles 6 can be greatly increased, and the separation efficiency can be improved, so that the content of the hydrophobic particles 6 in the recovered hydrophilic particles 5 can be greatly reduced.

As described above, as a result of wet separation of the hydrophilic particles 5 and the hydrophobic particles 6 using the aqueous phase 1 and the hydrophobic organic solvent phase 2, the hydrophobic particles are finally obtained as shown in FIG. 6 is hardly contained in the aqueous phase 1. For this reason, the aqueous phase 1 (second slurry containing the hydrophilic particles 5) is extracted from the upper part of the container used in the separation step and dehydrated to recover the hydrophilic particles 5 having a low content of the hydrophobic particles 6. be able to. On the other hand, the hydrophobic organic solvent phase 2 (third slurry containing the hydrophobic particles 6) is extracted from the bottom of the container, and the hydrophobic organic solvent is solid-liquid separated to obtain a hydrophobic solvent having a low content of the hydrophilic particles 5. Particles 6 can also be recovered.

Although not shown in FIGS. 1 and 2, at the interface between the aqueous phase 1 and the gas phase 9, a thin surface layer of the hydrophobic organic solvent is formed above the surface layer of the aqueous phase 1 due to surface tension. may occur. Hydrophobic particles 6 can adhere to the surface layer of this hydrophobic organic solvent. Therefore, when the aqueous phase 1 (second slurry containing hydrophilic particles 5) separated by the separation step is extracted from the container, rather than collecting from near the surface of the aqueous phase 1, from the surface of the aqueous phase 1, for example, 2 to 2 It is preferable to extract the second slurry containing the hydrophilic particles 5 from a region approximately 30 cm below. Thereby, the hydrophobic particles 6 floating on the surface layer of the hydrophobic organic solvent formed on the upper side of the aqueous phase 1 can be prevented from being collected. Therefore, the content of the hydrophobic particles 6 in the recovered hydrophilic particles 5 can be further reduced.

[2.2. Relationship between the specific gravity of the aqueous phase slurry and the specific gravity of the hydrophobic organic solvent]
Next, with reference to FIGS. 3A and 3B (hereinafter sometimes collectively referred to as "FIG. 3") and FIG. 4, an aqueous phase containing hydrophilic particles 5 suitable for realizing the above separation method The relationship between the specific gravity of the slurry of No. 1 and the specific gravity of the hydrophobic organic solvent will be described.

The specific gravity of the hydrophilic particles 5 in the aqueous phase 1 shown in FIG. 3 is usually larger than the specific gravity of the hydrophobic organic solvent. Nevertheless, most of the hydrophilic particles 5 in the water phase 1 remain in the water phase 1 without sinking in the hydrophobic organic solvent phase 2 .

In particular, as shown in FIG. 3, in the above separation method, the hydrophilic particles 5 dispersed in the aqueous phase 1 (that is, the slurry of water and the hydrophilic particles 5) settle in the aqueous phase 1, At the bottom of , a concentrated portion 7 of hydrophilic particles 5 is formed. The concentrated portion 7 is a region in which a large number of hydrophilic particles 5 are densely present in the lower portion of the aqueous phase 1 . When the specific gravity of the slurry in the concentrating section 7 is sufficiently smaller than the specific gravity of the hydrophobic organic solvent, the interface between the aqueous phase 1 and the hydrophobic organic solvent phase 2 becomes horizontal and clear. However, when the specific gravity of the slurry in the concentrating section 7 is approximately equal to or greater than the specific gravity of the hydrophobic organic solvent phase 2, the slurry in the concentrating section 7 settles in the solvent phase 2, resulting in the aqueous phase 1 and the hydrophobic organic solvent phase 2. The interface with becomes unclear.

For example, when a mixture (fly ash) mainly composed of hydrophilic particles 5 is added to a mixture of trichlorethylene (specific gravity: 1.46) and water (specific gravity: 1) as a hydrophobic organic solvent, trichlorethylene The interface between phase (solvent phase 2) and aqueous phase 1 becomes obscured. At this time, the average specific gravity of the fly ash concentrated portion 7 slurry precipitated in the aqueous phase 1 is 1.35, which is close to the specific gravity of trichlorethylene (1.46). In the concentration part 7 of the fly ash, since consolidation progresses from the interface near the interface between the water phase 1 and the trichlorethylene phase, the specific gravity of the slurry in the concentration part 7 increases and is even closer to the specific gravity of trichlorethylene, 1.46. Therefore, it is considered that the interface becomes unclear. In particular, as shown in FIG. 3B, as the number of hydrophobic particles 6 floating in the solvent phase 2 increases, the apparent specific gravity of the concentrated portion 7' of the hydrophobic particles 6 in the solvent phase 2 becomes smaller than the specific gravity of the solvent itself. It becomes close to the apparent specific gravity of the concentrated portion 7 of the hydrophilic particles 5 in the aqueous phase 1 . Therefore, the interface between the aqueous phase 1 and the solvent phase 2 is further obscured.

FIG. 4 is a graph showing the relationship between the slurry concentration C _S of the aqueous phase 1 and the slurry specific gravity d _S . FIG. 4 also shows the range of specific gravities of the main hydrophobic organic solvents.

Here, the slurry concentration C _S [% by mass] is the mass ratio of the hydrophilic particles 5 contained in the aqueous phase 1 (slurry of water and hydrophilic particles 5), and is represented by the following formula (1). Slurry specific gravity d _S is the apparent density ρ _S [g/cm ³ ] of the water phase 1 (slurry of water and hydrophilic particles 5) with the density ρ _w [g/cm ³ ] of water at the same temperature and pressure. It is a value obtained by division, and is represented by the following formula (2).

CS= _mP /( _{mP + mW} ) (1)
dS= _ρS / _ρw =( _{mP + mW} )/( _VP + _VW )/ _ρw (2)
m _P [g] : Mass of hydrophilic particles 5 contained in water phase 1 m _W [g] : Mass of water contained in water phase 1 _VP [cm ³ ] : Hydrophilic particles 5 contained in water phase 1 Volume of V _W [cm ³ ]: Volume of water contained in water phase 1 ρ _S [g/cm ³ ]: Apparent density of slurry of water and hydrophilic particles 5 in water phase 1 ρ _w [g/cm ³ ] : Density of water at the same temperature and pressure

As shown in FIG. 4, when the object to be separated is fly ash (specific gravity: 2.4) and the hydrophobic solvent is trichlorethylene (specific gravity: _1.46 ), the slurry concentration CS becomes 54% by mass or more. , the slurry specific gravity _dS becomes 1.46 or more. Therefore, if the slurry concentration _CS is less than 54% by mass, the metal oxide (hydrophilic particles 5) contained in the fly ash and the slurry of water (water phase 1) are contained in the trichlorethylene phase (solvent phase 2). It can be said that it does not settle. However, when fly ash and water are mixed, if the slurry concentration CS is 54% by mass, the mixture becomes a hard mud and is no longer a slurry, resulting in poor _mixability and mixing with trichlorethylene. It is difficult.

Therefore, when fly ash is used as the object to be separated, it depends on the form of _unburned carbon in the fly ash, so it is necessary to obtain it by experiment, but the slurry concentration CS is less than 38% by mass. preferable. When the slurry concentration CS exceeds 38% by mass, almost no decrease in the content of _{unburned carbon} in the fly ash after treatment is observed. The content of unburned carbon in fly ash decreases, and when it becomes less than 27% by mass, the content of unburned carbon in fly ash after treatment becomes constant at a low level. Therefore, it is possible to adjust the mixing ratio of fly ash and water in the mixing step or to select a hydrophobic organic solvent with an appropriate specific gravity so that the slurry concentration _CS of the aqueous phase 1 is less than 38% by mass. preferable.

Further, when the object to be separated is blast furnace gas ash (specific gravity: 4.0) and the hydrophobic solvent is trichlorethylene (specific gravity: 1.46), as shown in FIG. 4, the slurry concentration _CS is 42% by mass. When it becomes above, the specific gravity of a slurry will be 1.46 or more. Therefore, if the slurry concentration _CS is less than 42% by mass, the metal oxide (hydrophilic particles 5) contained in the blast furnace gas ash and the slurry of water (water phase 1) are contained in the trichlorethylene phase (solvent phase 2). can be said to not settle.

Blast furnace gas ash tends to concentrate near the interface between the water phase 1 and the trichlorethylene phase (solvent phase 2) more easily than fly ash, and the slurry specific gravity _dS in the concentration section 7 tends to increase. For this reason, although it depends on the form of existence of unburned carbon in the blast furnace gas ash, it needs to be determined by experiments, but in order to lower the slurry specific gravity _dS in the concentrating section 7, the slurry concentration _Cs should be less than 14% by mass. Preferably. When the slurry concentration CS exceeds 14% by mass, there is almost no decrease in the content of _unburned carbon in the blast furnace gas ash after treatment, but when the slurry concentration _CS is less than 14% by mass, after treatment The content of unburned carbon in the blast furnace gas ash decreases, and when CS is less than 7% by mass, the content of _unburned carbon in the blast furnace gas ash after treatment remains low and constant.

As described above with reference to FIG. 4, the greater the specific gravity of the hydrophilic particles 5, the more the hydrophilic particles 5 settle in the solvent phase 2 from the water phase 1 by selecting a hydrophobic organic solvent with a higher specific gravity. can be prevented, and the content of the hydrophilic particles 5 in the aqueous phase 1 (slurry concentration C _S ) can be increased. When the specific gravity of the hydrophilic particles 5 is small, it is not necessary to select a hydrophobic organic solvent with a small specific gravity, and the range of applicable hydrophobic organic solvents can be expanded.

[2.3. Relationship between apparent particle size of hydrophilic particles and specific gravity of hydrophobic organic solvent]
Next, referring to FIGS. 1 and 5, hydrophilic particles 5 coated with a water film in a hydrophobic organic solvent phase 2 (also referred to as “water-coated particles 5”) are suitable for realizing the separation method described above. ) and the relationship between the apparent particle size and the specific gravity of the hydrophobic organic solvent

As shown in FIG. 1, in the hydrophobic organic solvent phase 2, a thin water film (for example, about 5 to 20 μm) may adhere to the surface of the hydrophilic particles 5 that could not adhere to the water droplets 4. The apparent specific gravity of the hydrophilic particles 5 coated with the water film is smaller than the specific gravity of the hydrophilic particles 5 themselves. The amount of the water film adhering to the hydrophilic particles 5 varies depending on the thickness of the water film, voids in the hydrophilic particles 5, and the like.

For example, FIG. 5 shows the particle diameter φ _P of the hydrophilic particles 5 and the apparent specific gravity d _P of the water-coated particles 5 when a 10-μm-thick water coating is attached to spherical microparticles (hydrophilic particles 5) without voids. is a graph showing the relationship between

Here, the apparent specific gravity d _P of the water coated particles 5 is obtained by dividing the apparent density ρ _P [g/cm ³ ] of the water coated particles 5 by the density of water ρ _w [g/cm ³ ] at the same temperature and pressure. , which is expressed by the following equation (3).

dP= _ρP / _ρw =( _{mP + mC} )/( _VP + _VC )/ _ρw (3)
m _P [g] : Mass of hydrophilic particles 5 m _C [g] : Mass of water film adhering to hydrophilic particles 5 _VP [cm ³ ] : Volume of hydrophilic particles 5 _VC [cm ³ ] : Hydrophilicity Volume of the water film attached to the physical particles 5 ρ _P [g/cm ³ ]: Apparent density of the water film particles 5 ρ _w [g/cm ³ ]: Density of water at the same temperature and pressure

As shown in FIG. 5, the smaller the particle diameter φ _P of the hydrophilic particles 5 is, the larger the thickness t of the water film with respect to the particle diameter φ _P of the hydrophilic particles 5 is. _dP becomes smaller. When the apparent specific gravity d _P of the water-coated particles 5 becomes smaller than the specific gravity of the hydrophobic organic solvent, the water-coated particles 5 float in the solvent phase 2 and move to the aqueous phase 1 .

Therefore, depending on the particle diameter φ _P of the hydrophilic particles 5, the thickness t of the water film, the degree of voids in the hydrophilic particles 5, and the like, a hydrophobic organic solvent having an appropriate specific gravity is selected, and the appearance of the water film particles 5 is It is preferable to adjust the specific gravity _dP to be smaller than the specific gravity of the hydrophobic organic solvent. If it is difficult to directly measure the thickness t of the water film, for example, 0.5 to 1 g of the hydrophilic particles 5 are added to a mixed liquid of 80 ml of water and 20 ml of a hydrophobic organic solvent in a capped graduated cylinder, At that time, it is preferable to select such a hydrophobic organic solvent that most of the hydrophilic particles 5 do not settle in the hydrophobic organic solvent phase 2 . As a result, in the separation step, the water-coated particles 5 can be floated from the solvent phase 2 to the water phase 1 and retained in the water phase 1, and the hydrophilic particles 5 can be separated from the hydrophobic organic solvent and the hydrophobic particles 6. can be quickly and efficiently separated from

[2.4. Preferable Range of Particle Diameter or Specific Gravity of Particles]
Next, with reference to FIG. 3, the range of the particle diameter or specific gravity of particles suitable for realizing the separation method will be described. As shown in FIG. 3, when the hydrophilic particles 5 settle in the water phase 1 and reach the interface between the water phase 1 and the hydrophobic solvent phase 2, the hydrophilic particles 5 have buoyancy and interfacial tension. and gravity. The interfacial tension acts as an energy barrier that prevents the hydrophilic particles 5 from moving from one phase 1 to the other phase 2 at the interface. It can be said that the balance of these forces determines to which phase the hydrophilic particles 5 move. If the particle diameter of the hydrophilic particles 5 is large enough to exceed the sum of the buoyant force and interfacial tension acting on the hydrophilic particles 5, or if the specific gravity of the hydrophilic particles 5 is higher than the specific gravity of water, the It is believed that the particles 5 migrate from the aqueous phase 1 through the interface to the solvent phase 2 . In this case, the separation efficiency between the hydrophilic particles 5 and the hydrophobic particles 6 is lowered. From this point of view, it is preferable to remove the hydrophilic particles 5 having a large particle diameter or a large specific gravity to the extent that they pass through the interface and move to the solvent phase 2 before the separation treatment. For example, the particle diameter of the hydrophilic particles 5 contained in the mixture before the separation treatment may be 500 μm or less, preferably 200 μm or less.

As shown in FIG. 3B, the same applies to the hydrophobic particles 6 floating in the hydrophobic solvent phase 2 and reaching the interface. The particle diameter of the hydrophobic particles 6 is large enough to exceed the sum of the gravitational force and interfacial tension acting on the hydrophobic particles 6, or the hydrophobic If the specific gravity of the organic particles 6 is small, it is considered that the particles 6 move from the solvent phase 2 to the aqueous phase 1 through the interface. From this point of view, it is preferable to remove the hydrophobic particles 6 whose particle diameter is large or whose specific gravity is small enough to pass through the interface and move to the aqueous phase 1 before the separation treatment. For example, the particle diameter of the hydrophobic particles 6 contained in the mixture before the separation treatment may be 500 μm or less, preferably 200 μm or less. The maximum particle size of these hydrophilic particles 5 or hydrophobic particles 6 can be controlled by screening with a sieve or classification with a cyclone.

[3. Separability improvement by pulverization]
Some mixtures of hydrophobic particles and hydrophilic particles are partially integrated with hydrophobic particles and hydrophilic particles. For example, when the mixture is fly ash, the oxide particles in the fly ash are approximately spherical particles mainly composed of Al ₂ O ₃ and SiO ₂ . Many oxide particles are present outside the unburned carbon particles. However, the unburned carbon particles in the fly ash are porous, and some of the oxide particles enter the pores of the unburned carbon particles. The proportion of oxide particles entrapped in unburned carbon particles can be as large as the mass of unburned carbon.

The above [2. Overview of separation method], the separation of hydrophobic particles and hydrophilic particles proceeds to some extent, but if there are many parts in which the hydrophobic particles and hydrophilic particles are integrated in the mixture, Separability worsens. For example, when the mixture is fly ash, the content of unburned carbon in the separated and collected hydrophilic particles is often 3% by mass or less, but may exceed 3% by mass and varies. The content of unburned carbon in the separated and recovered hydrophobic particles is often 50% by mass or more, but the content varies greatly. The cause of these fluctuations is that unburned carbon particles and oxide particles are partially integrated in the fly ash. If there are many integrated parts, the separability deteriorates. Therefore, [2. Summary of Separation Method], by subjecting the target mixture to a pulverization treatment before separation by the method shown in Section 1, the separation between the hydrophobic particles and the hydrophilic particles is improved.

As a pulverizing method, the slurry mixture is pulverized by a mill using pulverizing media such as balls and beads, pulverized by colliding with the high-speed shearing blades of a high-shear homogenizer, or ultrasonically using an ultrasonic pulverizer. , and the like may be used. The hardness of each of the hydrophilic particles and the hydrophobic particles in the mixture, the state of integration of both particles, and the like are observed, and finally the pulverization method is tested to select the optimum method.

For example, when the mixture is fly ash, porous unburned carbon particles are easily pulverized, but oxide particles are spherical and dense and difficult to pulverize. Therefore, by adopting a pulverization process using beads, brittle unburned carbon particles can be efficiently pulverized in a short time without destroying hard oxide particles contained in fly ash. The larger the diameter of the beads (hereinafter referred to as the bead diameter), the smaller the diameter of the unburned carbon particles between the approximately spherical oxide particles. This reduces the possibility of collision between the beads and small unburned carbon particles. On the other hand, the smaller the bead diameter, in other words, the larger the curvature of the bead, the more the bead can come into contact with small-diameter unburned carbon particles without colliding with hard, substantially spherical oxide particles. Therefore, it can be said that the bead diameter is preferably 1 mm or less.

Therefore, when the mixture is fly ash, beads with a diameter of 1 mm or less are used, and the slurry fly ash is pulverized for about 1 second to 5 minutes to remove mainly unburned carbon particles. Can be pulverized. At this time, the oxide particles that have entered the pores of the unburned carbon particles are released from the unburned carbon particles. [2. Overview of separation method], the unburned carbon content in the separated and recovered hydrophilic particles is stabilized at 1% by mass or less, and the separated and recovered hydrophobic particles The content of unburned carbon becomes 70% by mass or more and less than 95%, and is stabilized.

[4. Single-stage continuous process]
Next, an embodiment will be described in which the separation method and recovery method according to the present embodiment are carried out in a single-stage continuous process using one set of a mixing device (mixing step) and a separation device (separation step). In the separation method according to the present embodiment, the mixing step, separation step, recovery step, and the like can be performed by batch processing. It is preferable to carry out the continuous treatment.

[4.1. Configuration and Separation Method of Particle Separator]
First, referring to FIG. 6, the configuration of the particle separation device 8 according to the present embodiment, and the method for separating and collecting the hydrophilic particles 5 and the hydrophobic particles 6 using the particle separation device 8 will be described. FIG. 6 is a schematic diagram showing a particle separator 8 according to this embodiment and a single-stage continuous process using the same.

As shown in FIG. 6 , the particle separation device 8 includes a mixer 10 (mixing device), a settler 20 (separation device), a first recovery device 30 and a second recovery device 40 .

(1) Mixing step by mixing device (S1)
In the mixing step, a mixture in which the hydrophilic particles 5 and the hydrophobic particles 6 are mixed is mixed with water and a hydrophobic liquid (hereinafter, an example of a hydrophobic organic solvent will be described), and the mixed liquid is stirred to form a slurry. to produce a first slurry (S1). Thereby, as shown in FIG. 1, the hydrophilic particles 5 adhere to the surface of the water droplet 4 or are taken into the water droplet 4, and the hydrophobic particles 6 adhere to the surface of the solvent droplet 3 or It is entrapped inside the droplet 3 .

As a mixing device for performing this mixing step (S1), for example, a vessel equipped with stirring blades for stirring the mixed liquid, a line mixer, or a pump capable of internally stirring the mixed liquid can be used. The mixer 10 in the example of FIG. 6 is an example of a container equipped with stirring blades for stirring the liquid mixture.

The mixer 10 is a stirrer having a motor 11 and stirring blades 12 . This mixer 10 is connected to a downstream settler 20 via a pipe 13 . A mixture to be separated, water, and a hydrophobic organic solvent having a higher specific gravity than water are put into the container of the mixer 10 . The mixer 10 rotates the stirring blades 12 by the motor 11 to mix the mixture, water and the hydrophobic organic solvent to form a first slurry (hydrophilic particles 5, hydrophobic particles 6, water and hydrophobic organic solvent mixture) is generated (mixing step).

(2) Separation step by separation device (S2)
Settler 20 is an example of a separation device that performs the separation process. The settler 20 allows the first slurry produced in the mixing step (S1) to stand still, thereby utilizing the difference in specific gravity between water and the hydrophobic organic solvent to obtain an aqueous phase 1 mainly containing hydrophilic particles 5, It is separated into a hydrophobic organic solvent phase 2 mainly containing hydrophobic particles 6 (S2).

The settler 20 is an example of a specific gravity separation device that allows a mixed liquid of a plurality of types of liquids to stand still and separates the liquids by using the difference in specific gravity. In addition, the settler 20 is connected to the subsequent first recovery device 30 via a pipe 21, and the pipe 21 is connected to a pump for sending out the aqueous phase 1 (second slurry) containing the hydrophilic particles 5. 22 are provided. Furthermore, the settler 20 is also connected to the subsequent second recovery device 40 via a pipe 23, to which the solvent phase 2 (third slurry) containing the hydrophobic particles 6 is sent. A pump 24 is provided.

The settler 20 uses the difference in specific gravity to separate the first slurry introduced from the mixer 10 through the pipe 13 into an upper aqueous phase 1 and a lower hydrophobic organic solvent phase 2, while making it hydrophilic. By transferring the particles 5 to the aqueous phase 1 and the hydrophobic particles 6 to the solvent phase 2, the hydrophilic particles 5 and the hydrophobic particles 6 are separated. This separation principle is as explained with reference to FIGS. 1 and 2 above. After that, the aqueous phase 1 (second slurry) containing the hydrophilic particles 5 is discharged from the top of the settler 20 through the pipe 21 to the first recovery device 30 . On the other hand, the solvent phase 2 (third slurry) containing the hydrophobic particles 6 is discharged from the bottom of the settler 20 through the pipe 23 to the second recovery device 40 .

(3) First recovery step (S3) by first recovery device 30
The first recovery device 30 separates water from the aqueous phase 1 (second slurry) containing the hydrophilic particles 5 separated in the separation step (S2), and recovers the hydrophilic particles 5 (for example, metal oxide). (S3). The first collection device 30 comprises a centrifuge 31 , a drying device 32 and a condenser 33 .

The centrifugal separator 31 is an example of a solid-liquid separator, and uses centrifugal force to separate a solid suspended in a liquid from a liquid. The centrifugal separator 31 is connected via a pipe 34 to a drying device 32 in the latter stage, and is connected via a pipe 35 to the mixer 10 in the previous stage. The aqueous phase 1 (second slurry) containing the hydrophilic particles 5 is introduced into the centrifuge 31 from the settler 20 . The centrifuge 31 uses centrifugal force to separate the second slurry into the hydrophilic particles 5 and water (solid-liquid separation step). The hydrophilic particles 5 dehydrated by the centrifuge 31 are discharged to the drying device 32 through the pipe 34 . On the other hand, the water separated by the centrifuge 31 is returned to the mixer 10 through the pipe 35 and reused in the mixing step (S1).

In the present embodiment, the second slurry is solid-liquid separated into water and the hydrophilic particles 5 by centrifugal separation by the centrifuge 31, but instead of this, a solid-liquid separation method such as filter press, distillation, or filtration is used. may be used. However, when the hydrophobic organic solvent is volatile, the use of a filter press is not preferable because the volatilized solvent gas leaks violently. In order to reduce leakage of the solvent gas, it is preferable to use, for example, a distillation apparatus, a centrifugal separation apparatus, or a filtration apparatus as the solid-liquid separation apparatus.

The drying device 32 heats the hydrophilic particles 5 introduced from the centrifugal separator 31 to evaporate the remaining moisture, thereby drying the hydrophilic particles 5 (drying step). The dried hydrophilic particles 5 are discharged from the pipe 36 and recovered. The condenser 33 condenses the water vapor delivered from the drying device 32 through the pipe 37 and returns it to liquid water (condensation step). The liquid water produced in the condenser 33 is returned to the mixer 10 through the pipe 38 and reused in the mixing step (S1) (first recycling step).

Thus, in the method for collecting hydrophilic particles 5 according to the present embodiment, in the first collecting step (S3), the aqueous phase 1 (second Slurry) is separated into hydrophilic particles 5 and water by a centrifuge 31, and then the hydrophilic particles 5 are dried by a drying device 32 to recover the hydrophilic particles 5 as dry powder. However, the first recovery step (S3) is not limited to such an example, and the aqueous phase 1 (second slurry) containing the hydrophilic particles 5 separated in the separation step (S2) is subjected to the solid-liquid separation The hydrophilic particles 5 in the water slurry state may be recovered by recovering them as they are without performing the process and the drying process. Whether the hydrophilic particles 5 are recovered in a dry powder state or in an aqueous slurry state can be appropriately selected according to the recycling application of the hydrophilic particles 5 or the like.

Further, in the first recovery step (S3), the aqueous phase 1 (second slurry) containing the hydrophilic particles 5 separated in the separation step (S2) is heated to a temperature equal to or higher than the boiling point of the hydrophobic organic solvent. It is preferable to evaporate and remove the hydrophobic organic solvent remaining in the water phase 1 by heating or reducing the pressure to a pressure at which the hydrophobic organic solvent evaporates. As a result, the hydrophilic particles 5 to be collected can be prevented from containing the hydrophobic organic solvent, and the quality of the hydrophilic particles 5 can be improved. In the particle separation device 8 according to the present embodiment, the hydrophobic organic solvent remaining in the second slurry is heated and evaporated together with water in the drying step by the drying device 32 shown in FIG. Solvent can be removed. When the hydrophobic organic solvent has volatility, it evaporates at room temperature, but since the specific gravity of the hydrophobic organic solvent is greater than that of water, it is often not in direct contact with the gas phase, so stirring or aeration is required. It is desirable to prevent the volatilized solvent from scattering.

(4) Second recovery step (S4) by second recovery device 40
The second recovery device 40 separates the hydrophobic organic solvent from the hydrophobic organic solvent phase 2 (third slurry) containing the hydrophobic particles 6 separated in the separation step (S2), and the hydrophobic particles 6 (for example, carbon) is recovered (S4). The second collection device 40 includes a centrifuge 41 , a drying device 42 and a condenser 43 .

The centrifugal separator 41 is connected via a pipe 44 to a drying device 42 in the latter stage, and is connected via a pipe 45 to the mixer 10 in the previous stage. The hydrophobic organic solvent phase 2 (third slurry) containing the hydrophobic particles 6 is introduced from the settler 20 into the centrifuge 41 . The centrifuge 41 uses centrifugal force to separate the third slurry into the hydrophobic particles 6 and the hydrophobic organic solvent (solid-liquid separation step). The hydrophobic particles 6 from which the hydrophobic organic solvent has been separated by the centrifuge 41 are discharged to the drying device 42 through the pipe 44 . On the other hand, the hydrophobic organic solvent separated by the centrifuge 41 is returned to the mixer 10 through the pipe 45 and reused in the mixing step (S1). In this embodiment, the third slurry is solid-liquid separated into the hydrophobic organic solvent and the hydrophilic particles 5 by centrifugal separation by the centrifuge 41. A liquid separation method may be used.

The drying device 42 heats the hydrophobic particles 6 introduced from the centrifugal separator 41 to evaporate the remaining hydrophobic organic solvent, thereby drying the hydrophobic particles 6 (drying step). The dried hydrophobic particles 6 are discharged from the pipe 46 and collected. The condenser 43 condenses the vapor of the hydrophobic organic solvent delivered through the pipe 47 from the drying device 42 and returns it to the liquid hydrophobic organic solvent (condensation step). The liquid hydrophobic organic solvent produced in the condenser 43 is returned to the mixer 10 through the pipe 48 and reused in the mixing step (S1) (second recycling step).

Thus, in the method for recovering the hydrophobic particles 6 according to the present embodiment, in the second recovery step (S4), the solvent phase 2 (third After separating the slurry) into the hydrophobic particles 6 and the hydrophobic organic solvent by the centrifuge 41, the hydrophobic particles 6 are dried by the drying device 42 to recover the dry powder hydrophobic particles 6 (for example, carbon powder). .

The steps (S1 to S4) of the separation method according to the present embodiment and the recovery method of the hydrophilic particles 5 or the hydrophobic particles 6 have been described above. In this embodiment, since the method is performed in a single-stage continuous process, the mixing step (S1), the separation step (S2), the first recovery step (S3), and the second recovery step (S4) are performed in parallel. . Thereby, the separation efficiency and productivity of the hydrophilic particles 5 and the hydrophobic particles 6 can be improved.

Furthermore, the water separated from the hydrophilic particles 5 in the first recovery step (S3) is recovered and reused as water to be introduced in the mixing step (S1), and in the second recovery step (S4) The hydrophobic organic solvent separated from the hydrophobic particles 6 is recovered and reused as the hydrophobic organic solvent introduced in the mixing step (S1). As a result, the water and the hydrophobic organic solvent do not have to be thrown away, so that the material cost and disposal cost of the hydrophobic organic solvent can be reduced. Furthermore, a large amount of the hydrophobic organic solvent can be repeatedly used in the mixing step (S1) and the separation step (S2), increasing the chances of the hydrophobic particles 6 coming into contact with the hydrophobic organic solvent. Further, in the separation step (S2), the hydrophilic particles 5 and the hydrophobic particles 6 are separated from the mixture with high efficiency by incorporating the hydrophobic particles 6 into the hydrophobic particles 6 and incorporating the hydrophilic particles 5 into the aqueous phase 1. Separable.

Therefore, the separation method according to the present embodiment can significantly improve the separation speed and separation efficiency of the hydrophilic particles 5 and the hydrophobic particles 6 compared to the conventional flotation method described in Patent Document 1 above. For example, the separation step (S2) according to the present embodiment can rapidly separate the hydrophilic particles 5 and the hydrophobic particles 6 in a short period of time, for example, about 1 second to 30 seconds. In addition, when the mixture to be separated is, for example, fly ash, the content of the hydrophobic particles 6 contained in the separated and recovered hydrophilic particles 5 can be reduced to 3% by mass or less, and the hydrophilic particles 5 with high purity can be obtained. can be recovered. Similarly, when the mixture to be separated is, for example, fly ash, the content of the hydrophilic particles 5 contained in the separated and recovered hydrophobic particles 6 can be reduced to 50% by mass or less, preferably 20% by mass or less. , the hydrophobic particles 6 with high purity can also be recovered.

[4.2. Specific example of separation device]
Next, with reference to FIGS. 7 to 9, specific examples of the separation device (for example, the settler 20) included in the particle separation device 8 according to the present embodiment will be described.

As the separation device (settler 20) that performs the separation step (S2) of the separation method according to the present embodiment, for example, the specific gravity of the horizontal flow separation device 200 shown in FIG. A separation device may be used. Alternatively, a liquid cyclone separator (not shown) can be used as the separator.

As shown in FIG. 8, in the cross-flow separator 200, a liquid mixture is horizontally supplied from the side of a horizontally long container 201, and the liquid mixture is allowed to stand in the container 201, thereby separating the aqueous phase 1 and The solvent phase 2 is gravity separated. Further, as shown in FIG. 9, in the upflow separator 210, the liquid mixture is supplied upward from the bottom surface of the vertically long container 211, and the liquid mixture is allowed to stand still in the container 211, so that the aqueous phase 1 and the solvent phase 2 by specific gravity separation.

When the mixed liquid is gravity-separated using such a cross-flow separator 200 or upward-flow separator 210, the interface between the aqueous phase 1 and the solvent phase 2 is the content of the hydrophilic particles 5 in the aqueous phase 1. The slurry concentration C _s in the water phase 1 can be increased because it is less affected. In particular, as shown in FIGS. 7 and 9, in the upflow separation device 210, the liquid mixture (first slurry) is supplied upward from the bottom surface of the container 211. The magnetic particles 5 are difficult to concentrate, and the increase in the slurry concentration CS is _small . Therefore, it is possible to increase the concentration of the first slurry (that is, the content of the hydrophilic particles 5) supplied to the upward flow separation device 210, so that the amount of the hydrophilic particles 5 to be separated and processed can be increased, and the productivity is improved. can improve.

On the other hand, in the _hydrocyclone separator, if the slurry concentration CS in the aqueous phase 1 is increased, the _slurry concentration CS in the aqueous phase 1 tends to increase near the interface between the aqueous phase 1 and the solvent phase 2. Compared to the cross-flow separator 200 and the _upflow separator 210, it is necessary to lower the slurry concentration CS in the water phase 1 . However, in the liquid cyclone separator, centrifugal force is applied along with the rotating flow in the cyclone, so it is possible to separate the hydrophilic particles 5 having a large particle size in the water phase 1 .

[4.3. Preferred Range of Specific Gravity of Hydrophobic Organic Solvent]
Next, the preferred range of the specific gravity (liquid specific gravity) of the hydrophobic organic solvent used in the separation method according to this embodiment will be described in detail.

The specific gravity of the hydrophobic organic solvent is preferably greater than 1.05. If the specific gravity of the hydrophobic organic solvent is 1.05 or less, the specific gravity of the hydrophobic organic solvent is close to that of water, so that the specific gravity separation speed by a separation device such as Settler 20 in the separation step (S2) decreases. For this reason, it takes a long time, such as 1 minute or more, for the liquid mixture (first slurry) to stand still in the separator until it separates into two upper and lower phases, the aqueous phase 1 and the solvent phase 2. In order to obtain a throughput of 1, it is necessary to increase the size of the separation apparatus.

Furthermore, when the specific gravity of the hydrophobic organic solvent is 1.05 or less, as shown in FIG. 4, the slurry concentration in the aqueous phase 1 is _CS should be less than 6% by mass, or less than 3% by mass with some margin, and the size of the separation apparatus is also increased.

Therefore, by setting the specific gravity of the hydrophobic organic solvent to be more than 1.05, after the water and the hydrophobic organic solvent are allowed to stand in the separation device, the water phase 1 and the solvent phase are rapidly separated, for example, in about 1 to 30 seconds. 2 can be separated into two phases, and the specific gravity separation speed can be improved. Furthermore, since the slurry concentration C 2 _S in the water phase 1 can be made, for example, at least 3% by mass or more, the separation throughput per unit time can be increased and a large separation apparatus can be dispensed with.

Moreover, the specific gravity of the hydrophobic organic solvent is preferably smaller than the specific gravity of the hydrophobic particles 6 (eg, 1.2 to 1.8), and preferably less than 1.8. As a result, in the second recovery step (S4), the hydrophobic particles 6 can be efficiently separated from the solvent phase 2 (third slurry) containing the hydrophobic particles 6 using the centrifuge 41, and the liquid is removed. improve sexuality. The reason for this will be explained below.

In the separation step (S2), when the water phase 1 and the hydrophobic organic solvent phase 2 are separated in the settler 20, as shown in FIGS. 3A and 3B, due to the difference in specific gravity between the hydrophobic organic solvent and the hydrophobic particles 6, The hydrophobic particles 6 settle or float in the solvent phase 2 . Thereafter, in the second recovery step (S4), the hydrophobic particles 6 are separated from the hydrophobic organic solvent phase 2 by a solid-liquid separation process using a centrifuge 41 or the like.

Since the centrifugal separator 41 performs solid-liquid separation using the specific gravity difference of the object, if "the specific gravity of the hydrophobic particles 6 < the specific gravity of the hydrophobic organic solvent", the relatively light hydrophobic particles 6 It floats inside the centrifuge 41 . As a result, the hydrophobic particles 6 are concentrated on the surface layer of the hydrophobic organic solvent, but since the surface layer of the hydrophobic organic solvent fluctuates, the gaps between the hydrophobic particles 6 often do not become sufficiently small, which is good. It becomes difficult to obtain the liquid removal property. Therefore, when using the centrifuge 41 for the solid-liquid separation device in the separation step (S2), the hydrophobic organic solvent is is preferred. Even when "the specific gravity of the hydrophobic particles 6 < the specific gravity of the hydrophobic organic solvent", a centrifugal separator can be used, although the liquid removal is inferior, or a filtration or distillation solid-liquid separation device can be used. can also

On the other hand, when "the specific gravity of the hydrophobic particles 6>the specific gravity of the hydrophobic organic solvent", the relatively heavy hydrophobic particles 6 settle in the centrifuge 41 and deposit on the bottom of the centrifuge container. Therefore, when the hydrophobic particles 6 are recovered, the excess amount of the hydrophobic organic solvent to be recovered can be reduced, so that the liquid removing property is improved. Therefore, it is preferable to use a hydrophobic organic solvent having a specific gravity smaller than that of the hydrophobic particles 6 (for example, 1.2 to 1.8).

[4.4. Preferred Range of Boiling Point of Hydrophobic Organic Solvent]
Next, the preferable boiling point range of the hydrophobic organic solvent used in the separation method according to this embodiment will be described.

In the first recovery step (S3), when the hydrophilic particles 5 are recovered from the aqueous phase 1 containing the hydrophilic particles 5, the hydrophobic organic solvent remaining in the aqueous phase 1 is heated to evaporate. Therefore, it is desirable to remove the hydrophobic organic solvent. Here, the appropriate boiling point range of the hydrophobic organic solvent differs depending on whether the hydrophilic particles 5 to be recovered are cake-like or slurry-like.

The aqueous phase 1 (second slurry) containing the hydrophilic particles 5 separated by the separator such as the settler 20 is in the form of a slurry. Cake-like hydrophilic particles 5 are obtained. Compared with the second slurry containing the hydrophilic particles 5, the cake-like hydrophilic particles 5 have less moisture.

Therefore, when the cake-shaped hydrophilic particles 5 are heated to remove the hydrophobic organic solvent, the amount of heat required to evaporate the water is small, so the hydrophobic organic solvent is heated to evaporate and remove. can reduce the amount of heat required for Therefore, even if a hydrophobic organic solvent having a boiling point exceeding 100° C. under atmospheric pressure is used, the cake-shaped hydrophilic particles 5 can be easily heated to the boiling point or higher with a relatively small amount of heat. It can be removed by evaporating the organic solvent. However, if the boiling point of the hydrophobic organic solvent exceeds 150°C, the equipment cost of the heating device and the heat treatment cost increase, so the boiling point of the hydrophobic organic solvent is preferably 150°C or less.

On the other hand, when removing the hydrophobic organic solvent by heating the slurry-like hydrophilic particles 5, since the water content is large, if a hydrophobic organic solvent having a boiling point of 100° C. or higher is used, not only the hydrophobic organic solvent but also It becomes necessary to evaporate a large amount of water, which increases the amount of heat required for the heat treatment. Therefore, it is preferable to use a hydrophobic organic solvent having a boiling point of less than 95° C. that is lower than that of water. As a result, when removing the hydrophobic organic solvent by heating the slurry-like hydrophilic particles 5, the heating temperature is set to a temperature lower than 100 ° C. and a temperature equal to or higher than the boiling point of the hydrophobic organic solvent, thereby suppressing evaporation of water. while allowing the hydrophobic organic solvent to evaporate. Therefore, the amount of heat required for the heat treatment can be reduced, and the equipment cost of the heating device and the heat treatment cost can be suppressed.

Further, if the boiling point of the hydrophobic organic solvent is less than 40° C., the amount of the solvent volatilized at normal temperature and atmospheric pressure will be significantly increased, and the amount of unrecoverable solvent will increase. Therefore, the boiling point of the hydrophobic organic solvent is preferably 40° C. or higher so that the hydrophobic organic solvent can be easily handled at room temperature and atmospheric pressure.

As described above, the boiling point of the hydrophobic organic solvent is preferably 40° C. or higher and 150° C. or lower under atmospheric pressure. This makes it possible to easily evaporate and remove the hydrophobic organic solvent from the cake-like hydrophilic particles 5 after solid-liquid separation. Furthermore, the boiling point of the hydrophobic organic solvent is more preferably 40° C. or higher and 95° C. or lower under atmospheric pressure. As a result, when the hydrophobic organic solvent is evaporated and removed from the slurry-like hydrophilic particles 5, the evaporation of water can be suppressed, so that the hydrophobic organic solvent can be easily evaporated and removed with a small amount of heat. be able to.

[5. Countercurrent multistage continuous process]
Next, a separation method and a recovery method according to a second embodiment of the present invention will be described. The separation method according to the second embodiment employs a countercurrent multistage continuous process in which multiple sets of mixing devices and separation devices are installed to repeat the mixing step (S1) and the separation step (S2).

As described above, in the separation step (S2) by the separation device (settler 20), after the mixed liquid (first slurry) is allowed to stand, for example, for 1 second to 30 seconds, the water phase 1 and the hydrophobic organic solvent phase 2 are separated. Separation is preferred. If the stationary time is too long, the slurry concentration C _S in the lower part of the aqueous phase 1 near the interface between the aqueous phase 1 and the solvent phase 2 will increase too much, the interface will become unclear, and the separation efficiency of the hydrophobic particles 6 will decrease. may decline. Therefore, although the separation method according to the present embodiment can be performed as a batch process, it is preferably performed as a continuous process.

As described above, in the separation method according to the present embodiment, the separation speed in the separation step (S2) is high, and phase separation can be performed in several seconds to several tens of seconds. In this case, as in the second embodiment described below, the mixing step (S1) by the mixing device (mixer 10, etc.) and the separation step (S2) by the separation device (settler 20, etc.) are repeatedly applied. , a multi-stage continuous process can be employed. From the viewpoint of the separation efficiency and quality of the hydrophilic particles 5 and the hydrophobic particles 6, the multi-stage continuous process according to the second embodiment is preferable to the single-stage continuous process (see FIG. 6) according to the first embodiment. is preferred. As a result, the content of the hydrophobic particles 6 contained in the solids recovered from the aqueous phase 1 can be reduced, and the content of the hydrophobic particles 6 contained in the solids recovered from the solvent phase 2 can be reduced. content can be increased.

[5.1. Configuration of Particle Separator and Countercurrent Two-Stage Continuous Process]
Here, with reference to FIG. 10, the configuration of the particle separator 8A according to the second embodiment and the countercurrent two-stage continuous process using the same will be described. FIG. 10 shows an example of a countercurrent two-stage continuous process in which the mixing step (S1) and the separation step (S2) are combined in two stages in the countercurrent multistage continuous process.

As shown in FIG. 10, a particle separation device 8A for carrying out a countercurrent two-stage continuous process according to the second embodiment includes two sets of mixing devices and separation devices (two sets of mixers 10A, 10B and a settler 20A, 20B), a first recovery device 30, and a second recovery device 40. Here, the functions and configurations of the mixers 10A and 10B, the settlers 20A and 20B, the first recovery device 30, and the second recovery device 40 are substantially the same as those of the first embodiment (see FIG. 6, etc.). Since they are the same, detailed description is omitted.

As shown in FIG. 10, in the particle separation device 8A according to the second embodiment, the first-stage mixer 10A and the settler 20A perform the first-stage mixing step (S1_1) and the first-stage separation step (S2_1). to run. Further, the second-stage mixer 10B and the settler 20B perform a second-stage mixing step (S1_2) and a second-stage separation step (S2_2). Then, the first recovery device 30 recovers the hydrophilic particles 5 and water from the aqueous phase 1 containing the hydrophilic particles 5 separated in the second separation step (S2_2) (S3). On the other hand, the second recovery device 40 recovers the hydrophobic particles 6 and the hydrophobic organic solvent from the hydrophobic organic solvent phase 2 containing the hydrophobic particles 6 separated in the first separation step (S2_1) (S4 ).

Specifically, first, the mixture supplied from the outside, the water recycled in the system, and the solvent phase 2 containing the hydrophobic particles 6 discharged from the second stage settler 20B are transferred to the first stage mixer 10A. They are thrown in, mixed and stirred (S1_1), and separated into a water phase 1 and a solvent phase 2 in the first stage settler 20A (S2_1). Next, the aqueous phase 1 (second slurry) containing the hydrophilic particles 5 and the remaining hydrophobic particles 6 discharged from the top of the first-stage settler 20A is introduced into the second-stage mixer 10B through the pipe 21A. , is mixed and agitated with the hydrophobic organic solvent separated into solid and liquid in the subsequent centrifuge 41 (S1_1), and further separated into the aqueous phase 1 and the solvent phase 2 in the second stage settler 20B (S2_2 ). Next, the aqueous phase 1 (second slurry) containing the hydrophilic particles 5 discharged from the upper part of the second stage settler 20B is introduced into the centrifuge 31 of the first recovery device 30 through the pipe 21B, and solid-liquid After separation, drying, etc., the hydrophilic particles 5 are recovered (S3). The water recovered in this first recovery step (S3) is recycled, put into the first-stage mixer 10A, and used in the first-stage mixing step (S1_1).

On the other hand, the hydrophobic organic solvent is put into the second-stage mixer 10B and mixed and stirred together with the aqueous phase 1 (second slurry) containing the hydrophilic particles 5 discharged from the top of the first-stage settler 20A. (S1_2), and further separated into a water phase 1 and a solvent phase 2 in the second settler 20B (S2_2). Next, the solvent phase 2 (third slurry) containing the hydrophobic particles 6 and the remaining hydrophilic particles 5 discharged from the bottom of the second-stage settler 20B is introduced into the first-stage mixer 10A through the pipe 23B. , and mixed and agitated with the above mixture and water separated into solid and liquid by the centrifugal separator 31 in the latter stage (S1_1), and separated into an aqueous phase 1 and a solvent phase 2 in the first stage settler 20A (S2_1). . Next, the solvent phase 2 (third slurry) containing the hydrophobic particles 6 discharged from the bottom of the first-stage settler 20A is introduced into the centrifuge 41 of the second recovery device 40 through the pipe 23A, and solid-liquid Through separation, drying, etc., the hydrophobic particles 6 are recovered (S4). The hydrophobic organic solvent recovered in the second recovery step (S4) is recycled, put into the second-stage mixer 10B, and used in the second-stage mixing step (S1_2).

As described above, in the countercurrent two-stage continuous process according to the second embodiment, the combination of the mixing step (S1) and the separation step (S2) is performed in two steps using two sets of mixing devices and separation devices. be done. As a result, the aqueous phase 1 containing the hydrophilic particles 5 and the solvent phase 2 containing the hydrophobic particles 6 are separated in two steps. 5 and the hydrophobic particles 6 can be further improved. Therefore, the hydrophilic particles 5 having a lower content of the hydrophobic particles 6 and the hydrophobic particles 6 having a lower content of the hydrophilic particles 5 can be recovered. Furthermore, since it is a countercurrent type continuous process, the separation speed and productivity are not lowered as compared with the single-stage continuous process according to the first embodiment.

[5.2. Separation method by countercurrent multistage continuous process]
In FIG. 10 above, the countercurrent two-stage continuous process was described, but the separation method according to the second embodiment can also be applied to a countercurrent multistage continuous process with N or more stages (N is an integer of 3 or more). is.

FIG. 11 is a process diagram showing a separation method by an N-stage countercurrent multistage continuous process. As shown in FIG. 11, in the N-stage countercurrent multistage continuous process, the combination of the mixing step (S1) and the separation step (S2) is repeated for N stages. As N increases, the separation efficiency of the hydrophilic particles 5 and the hydrophobic particles 6 improves, and the contents of the hydrophilic particles 5 and the hydrophobic particles 6 in the recovered solids can be increased.

In the example shown in FIG. 11, for example, in the first mixing step (S1_1), the mixture to be separated and water are added, and in the second to N mixing steps (S1_2 to N), water is used alone. will not be put in. On the other hand, in the mixing step (S1_N) of the N stage, which is the final stage, a hydrophobic organic solvent is introduced, and in the mixing steps (S1_1 to N-1) of the 1st to N-1 stages, the hydrophobic organic solvent is not entered alone.

Then, the aqueous phase 1 containing the hydrophilic particles 5 and the remaining hydrophobic particles 6 separated in the separation step (S2_n) of the n-th stage (n is an integer of 1 or more and N-2 or less), and the n + 2nd stage The solvent phase 2 containing the hydrophobic particles 6 separated in the separation step (S2_n+2) and the remaining hydrophilic particles 5 are mixed and slurried in the n+1 stage mixing step (S1_n+1). Then, in the n+1 stage separation step (S2_n+1), the aqueous phase 1 mainly containing the hydrophilic particles 5 and the solvent phase 2 mainly containing the hydrophobic particles 6 are separated.

By repeating the combination of the mixing step (S1) and the separation step (S2) in each stage, the aqueous phase 1 having a higher content of the hydrophilic particles 5 can be obtained from the first stage to the N stage. , the solvent phase 2 having a higher content of the hydrophobic particles 6 is obtained from the N stage to the first stage. Thereafter, in the first recovery step (S3) in the latter stage of the N-th stage, the hydrophilic particles 5 and water are separated and recovered from the aqueous phase 1 having a high content of the hydrophilic particles 5, and the recovered water is It is returned to the first-stage mixing step (S1_1) and reused. On the other hand, in the second recovery step (S4) in the latter stage of the first stage, the hydrophobic particles 6 and the hydrophobic organic solvent are respectively separated and recovered from the solvent phase 2 having a high content of the hydrophobic particles 6, and recovered. The hydrophobic organic solvent is returned to the N-th mixing step (S1_N) and reused.

In this way, by performing the countercurrent multistage continuous process in N stages, the separation efficiency of the hydrophilic particles 5 and the hydrophobic particles 6 is further improved compared to the single-stage continuous process according to the first embodiment. can be improved, and the hydrophilic particles 5 with a low content of the hydrophobic particles 6 and the hydrophobic particles 6 with a low content of the hydrophilic particles 5 can be recovered, and the separation speed and productivity are not reduced. .

In the example of FIG. 11, the mixture, which is the object to be separated, is put in the first mixing step (S1_1), but the mixture is put in the other mixing steps (S1_2 to N). good too.

[5.3. Countercurrent multistage continuous process with additional washing process]
Next, with reference to FIGS. 12 and 13, a countercurrent multistage continuous process with an additional washing step with water will be described.

FIG. 12 shows a separation method by an N-stage countercurrent multistage continuous process in which one washing step (S5, S6) is added to the N-stage countercurrent multistage continuous process shown in FIG. It is a process chart. As shown in FIG. 12, one washing step (S5, S6) is added before the first mixing step (S1_1) and separation step (S2_1).

In the washing steps (S5, S6), the minute amount of hydrophilic particles 5 are removed from the solvent phase 2 containing the hydrophobic particles 6 separated in the first separation step (S2_1) and the minute amount of remaining hydrophilic particles 5. It is a process for removing. The washing steps (S5, S6) include a washing mixing step (S5) and a washing separation step (S6).

In the washing mixing step (S5), the above-described mixing device (for example, the mixer 10 in FIG. 6) is used to separate the hydrophobic particles 6 separated in the first separation step (S2_1) and the remaining minute amount of hydrophilic particles. Water is added to the solvent phase 2 (third slurry) containing 5 and mixed and stirred to form a slurry. Next, in the washing separation step (S6), the slurry produced in the washing mixing step (S5) is divided into the aqueous phase 1 and the solvent phase 2 using the above-described separation device (for example, the settler 20 in FIG. 6). The hydrophilic particles 5 are separated from the hydrophobic particles 6 by moving a minute amount of the hydrophilic particles 5 to the aqueous phase 1 while separating.

After that, the solvent phase 2 containing the hydrophobic particles 6 separated in the washing separation step (S6) is sent to the second recovery step (S4), and the hydrophobic particles 6 are separated from the solvent phase 2 containing the hydrophobic particles 6. and the hydrophobic organic solvent are respectively separated and recovered, and the recovered hydrophobic organic solvent is returned to the N-th mixing step (S1_N) and reused. On the other hand, the aqueous phase 1 containing a small amount of hydrophilic particles 5 separated in the washing separation step (S6) is sent to the first stage mixing step (S1) and mixed with the mixture and the hydrophobic organic solvent, After that, it is processed in the same way as above.

As described above, in the washing step (S5, S6), only water is added to the solvent phase 2 containing the hydrophobic particles 6 and a small amount of the hydrophilic particles 5, and the hydrophilic particles 5 are washed with the water. A minute amount of hydrophilic particles 5 remaining in the solvent phase 2 can be taken into the water and removed. Thereby, the content of the hydrophobic particles 6 in the solids recovered from the solvent phase 2 in the second recovery step (S4) can be further increased.

Next, with reference to FIG. 13, a countercurrent multistage continuous process in which the washing steps (S5, S6) are performed in multiple stages will be described. FIG. 13 is a process diagram showing a separation method by a countercurrent multistage continuous process in which M-stage washing steps (S5 and S6) are added to the N-stage countercurrent-type multistage continuous process shown in FIG. be. As shown in FIG. 13, before the first-stage mixing step (S1_1) and separation step (S2_1), M-stage (M is an integer of 2 or more) washing steps (S5_-1 to -M, S6_-1) ~-M) has been added.

As shown in FIG. 13, the combination of the washing mixing step (S5) and the washing separation step (S6) in the washing step may be repeated M steps. The more M is, the more effectively the minute amount of hydrophilic particles 5 remaining in the solvent phase 2 can be separated and removed, and the more hydrophilic particles 5 are contained in the hydrophobic particles 6 recovered in the second recovery step (S4). rate can be lowered.

In the example shown in FIG. 13, for example, water is added in the -M stage cleaning mixing process (S5_-M), and -M+1 to -1 stage cleaning mixing processes (S5_-M+1 to -1 ), and the 1st to N-th mixing steps (S1_1 to N), water is not added alone. On the other hand, in the N-th mixing step (S1_N), which is the final stage, a hydrophobic organic solvent is introduced, and the 1st to N-1st mixing steps (S1_1 to N-1), and -M to - In the first washing mixing step (S5_-M to -1), the hydrophobic organic solvent is not charged alone.

Then, a solvent phase 2 containing the hydrophobic particles 6 separated in the washing separation step (S6_-m) of the -mth stage (m is an integer of 1 or more and M-2 or less) and the remaining hydrophilic particles 5 , the aqueous phase 1 containing the hydrophilic particles 5 separated in the -m-2nd washing separation step (S6_-m-2) and the remaining hydrophobic particles 6 is subjected to the -m-1st washing It is mixed and slurried in the second mixing step (S5_-m-1). Then, in the -m-1 stage separation step (S6_-m-1), the aqueous phase 1 mainly containing the hydrophilic particles 5 and the solvent phase 2 mainly containing the hydrophobic particles 6 are separated. be.

By repeating the combination of the cleaning mixing step (S5) and the cleaning separation step (S6) in each stage, a solvent having a higher content of the hydrophobic particles 6 is obtained from the -1 stage to the -M stage. Phase 2 is obtained, while aqueous phase 1 having a higher hydrophilic particle 5 content is obtained from the -M stage to the -1 stage. Thereafter, in the second recovery step (S4) in the latter stage of the −M stage, the hydrophobic particles 6 and the hydrophobic organic solvent are respectively separated and recovered from the solvent phase 2 having a high content of the hydrophobic particles 6, and recovered. The resulting hydrophobic organic solvent is returned to the N-th stage mixing step (S1_N) and reused.

As described above, in the -M to -1 stage, the addition of water removes the trace amount of hydrophilic particles 5 remaining in the solvent phase 2, and in the 1 to N stages, the addition of the solvent causes the aqueous phase 1 , the remaining hydrophobic particles 6 are removed. In this way, in the countercurrent multistage continuous process, by performing the M-stage washing steps (S5, S6), the hydrophobic particles 6 are further removed from the By separating the hydrophobic particles 6, the hydrophobic particles 6 having a low content of the hydrophilic particles 5 can be recovered without lowering the separation speed and productivity.

[5.4. Separation of magnetic substances]
Next, with reference to FIG. 14, a separation method and recovery method including a magnetic separation step according to a third embodiment of the present invention will be described.

When the mixture to be separated by the above separation method is fly ash, for example, when fly ash is mixed with a mixture of water and a hydrophobic organic solvent and left to stand, metal oxides containing iron (hydrophilic particles 5) are mainly formed. and a solvent phase 2 containing unburned carbon (hydrophobic particles 6). Since the specific gravity of iron is large (specific gravity: 4 to 5), if the particle size of iron is larger than 6 μm, the iron is a hydrophilic particle, but as described in FIG. There is also As described above, fly ash may contain magnetic substances such as iron as contamination. In the furnace of a coal _- fired power plant, etc. _, the oxygen concentration is low and the coal stays in the furnace for a short time. is reduced to magnetite (Fe ₃ O ₄ ). Therefore, the iron mainly remains in the fly ash as magnetite powder (Fe ₃ O ₄ ).

Magnetic substances such as magnetite powder are preferably collected separately from the hydrophilic particles 5 and the hydrophobic particles 6 in the separation method according to the present embodiment. Therefore, the third embodiment further includes a magnetic separation step of adsorbing and separating magnetic substances (eg, magnetite powder) mixed in the mixture to be separated (eg, fly ash) using a magnet.

FIG. 14 is a schematic diagram showing a particle separation device 8B for performing a separation method including a magnetic separation step according to the third embodiment, and a countercurrent multistage continuous process using the same. Note that the particle separation device 8B (see FIG. 14) according to the third embodiment has magnetic separation strainers 51, 52, and 53 compared to the particle separation device 8 (see FIG. 10) according to the second embodiment. etc., and the functions and configurations of other devices are substantially the same as those of the second embodiment, so detailed description thereof will be omitted.

As shown in FIG. 14, for example, magnetic separation strainers 51, 52, 53 and the like are conceivable as a magnetic separation device for executing the magnetic separation process. In the particle separation device 8B that performs a countercurrent multistage continuous process, the installation position of the magnetic separation device varies depending on the purpose of the magnetic separation, and may be, for example, (1) to (3) below.

(1) When separating the magnetic substance from the entire mixture to be separated, magnetic separation A strainer 51 may be installed.
(2) When separating the magnetic substance from the solid matter (mainly the hydrophobic particles 6) mixed in the hydrophobic organic solvent phase 2, the latter stage of the first stage separation device (settler 20A) shown in FIG. , the magnetic separation strainer 52 may be installed at the position of the pipe 23A that connects the settler 20A and the second recovery device 40 .
(3) When separating the magnetic substance from the solid matter (mainly the hydrophilic particles 5) mixed in the aqueous phase 1, a settler The magnetic separation strainer 53 may be installed at the position of the pipe 21B that connects the 20B and the first recovery device 30 .

When the magnetic separation strainers 51, 52, and 53 are used as the magnetic separation device, the method of collecting the magnetic substances is, for example, when the magnetic substances accumulate to some extent in the electromagnetic strainer, the magnetic substances are manually taken out from the inside of the strainer and collected. method, and a method of automatically taking out and recovering the magnetic substance. Manual collection or automatic collection may be selected according to the magnetic substance content and processing amount.

Here, the magnetic separation method when the mixture to be separated is fly ash will be described in detail. As described above, magnetite powder (Fe ₃ O ₄ ) is the main component of magnetic substances contained in fly ash. The magnetite powder is oxidized to Fe ₂ O ₃ at high temperature and turns red. On the other hand, metal oxides such as SiO ₂ and Al ₂ O ₃ that constitute fly ash are pale gray to white. Here, by removing the magnetic substances from the fly ash by the magnetic separation process according to the present embodiment, it is possible to reduce the color unevenness of the recovered metal oxide (hydrophilic particles 5) and improve the quality. In this case, it is preferable to install a magnetic separation device at the position of (1) a magnetic separation strainer 51 and (3) a magnetic separation strainer 53 shown in FIG.

However, fine magnet powder with a size of less than about 6 μm present in the aqueous phase 1 may be difficult to migrate to the solvent phase 2 due to the interfacial tension acting at the interface between the aqueous phase 1 and the solvent phase 2. There are many. Therefore, in order to remove the fine magnetic particles contained in the water phase 1, it is preferable to install a magnetic separation device at the position of (3) the magnetic separation strainer 53 shown in FIG. In addition, when it is desired to increase the carbon content in the unburned carbon and increase the efficiency as a fuel, in order to remove the magnetic substances contained in the solvent phase 2 together with the unburned carbon (hydrophobic particles 6), It is preferable to install the magnetic separator at the position of (2) the magnetic separation strainer 52 shown in 14 .

As described above, if the fly ash is to be separated in the steel industry and the magnetic separation process is performed, the fly ash contains fine magnetic powder. It is considered preferable to install a magnetic separation device at the position of , collect iron-containing magnetic powder, and use it in the iron manufacturing process together with the unburned carbon concentrate.

In addition, although the above described an example in which the iron content in the fly ash is magnetically separated as the magnetic substance separated in the magnetic separation process, the magnetic substance is not limited to such an example. For example, blast furnace gas ash contains spinel ferrite having a magnetic spinel-type crystal structure, AFe ₂ O ₄ (where A is Fe, Mn, Ni, Zn, etc.) and the like as magnetic substances. Therefore, when the mixture to be separated is blast furnace gas ash, it is also possible to separate and recover these magnetic substances from the blast furnace gas ash by magnetic separation.

Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

[Example 1]
First, the test of Example 1 will be described with reference to Table 4. Table 4 shows the test conditions and results of Example 1.

As shown in Table 4, 80 ml of water and 20 ml of various hydrophobic liquids were placed in a 100 ml graduated cylinder with a stopper, and then the slurry concentration C _S [% by mass] in the aqueous phase 1 was the concentration shown in Table 4. The mixture was added so that Next, the liquid mixture in the graduated cylinder was vigorously mixed by hand for 10 seconds, and then allowed to stand still for 10 seconds. Immediately thereafter, a sample was taken from a portion of the aqueous phase 1, the solid matter in the aqueous phase 1 was recovered, and the content of the recovered solid matter was measured. Also, the content _CB of the hydrophobic particles 6 in the collected solid matter was measured. Also, the hydrophobic particle separation rate _KA represented by the following formula (4) was calculated. On the other hand, the hydrophilic particle recovery rate _KB was 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] : mass of the charged hydrophobic particles 6 m _B [g] : mass of the hydrophobic particles 6 contained in the aqueous phase 1 m _Q [g] : mass of the charged hydrophilic particles 5 m _P [g ]: Mass of hydrophilic particles 5 contained in aqueous phase 1

In addition, as shown in Table 4, the fly ash of Comparative Example 1 and Examples 1-1 to 1-9 used as the mixture to be separated contained 1.9% by mass of carbon, and the volume The standard 50% particle size was 19 µm. The fly ash of Examples 1-10 to 1-13 contained 5.3% by mass of carbon, and its volume-based 50% particle size was 21 μm. The blast furnace gas ash of Example 1-14 contained 26% by mass of carbon, and its volume-based 50% particle size was 15 μm. The 50% volume-based particle size of the polyethylene terephthalate powder of Examples 1-15 was 94 μm. The volume-based 50% particle size of the vinyl chloride resin powder of Example 1-16 was 87 μm. In Examples 1-15 and 1-16, the volume-based 50% particle size of the Fe ₂ O ₃ powder (reagent) was 1.2 μm, and the hydrophobicity of the mixtures used in Examples 1-15 and 1-16 The particle contents were 10% by mass and 10.4% by mass, respectively. In Example 1-17, the mixed liquid obtained by slurring the fly ash used in Examples 1-10 to 1-13 with water was pulverized with beads having a diameter of 0.3 mm for 5 seconds. Fly ash obtained by drying the mixed liquid after such pulverization treatment was used. The volume-based 50% particle diameter was measured by a wet method in which a sample is slurried with water and dispersed by stirring and ultrasonic waves using a laser diffraction/scattering method.

As a result of the above tests, as shown in Table 4, all of Examples 1-1 to 1-17 had a hydrophilic particle recovery rate K _B of 73% by mass or more, particularly Examples 1-1 and 1- In Examples other than 6, it was 92% by mass or more. Therefore, it can be seen that the hydrophilic particles 5 can be recovered from the mixture at a high recovery rate by the separation method according to the present embodiment. The hydrophobic particle separation rate K _A was as high as 96 to 98% by mass in Examples 1-15 and 1-16, and 42 to 56% by mass in Examples 1-1 to 1-14. Therefore, by the separation method according to the present embodiment, the content of the hydrophobic particles 6 contained in the recovered hydrophilic particles 5 can be significantly reduced, and high-quality hydrophilic particles 5 with a high content can be recovered. confirmed. Furthermore, in Example 1-17 in which the fly ash was pulverized, compared with Example 1-11 under the same conditions except for the pulverization treatment, the hydrophobic particle separation rate K _A and the hydrophilic particle recovery rate K _B Both increased, and the content of the hydrophobic particles 6 contained in the recovered hydrophilic particles 5 also decreased significantly.

The content C _B of the hydrophobic particles 6 in the solid matter recovered from the aqueous phase 1 was 1.2% by mass in Example 1-1 in which the specific gravity of the silicone oil as the hydrophobic liquid was 1.07. rice field. On the other hand, in Comparative Example 1 in which the specific gravity of the silicone oil is 1.03, the content _CB was 1.9% by mass. Therefore, it can be seen that the specific gravity separation speed can be improved by setting the specific gravity of the hydrophobic liquid to more than 1.05. That is, in Comparative Example 1, since the specific gravity of the silicone oil is 1.05 or less, the specific gravity of the aqueous phase 1 is close to the specific gravity of the solvent phase 2, which is a hydrophobic liquid phase, and the phase separation speed is very slow. After the above mixing, the mixture was allowed to stand for 1 minute, but phase separation hardly progressed. About 20 ml of the upper portion of the graduated cylinder was sampled, the solid matter was recovered, and the content of the hydrophobic particles 6 in the recovered matter was measured and found to be 1.9% by mass. That is, there was almost no change from the content of the hydrophobic particles 6 in the fly ash charged.

In addition, when comparing Examples 1-2 to 1-6 in which the slurry concentration C _s in the aqueous phase 1 was changed, when the slurry concentration in the aqueous phase 1 was 38% by mass or more, the solid recovered from the aqueous phase 1 The content C _B of the hydrophobic particles 6 in the substance increased, and in particular when the slurry concentration in the aqueous phase 1 was 47% by mass (Example 1-6), C _B was 1.7% by mass. , only slightly reduced compared to the content of hydrophobic particles in the original sly ash (1.9% by weight). This is because if the slurry concentration _CS in the water phase 1 is too high, the interface between the water phase 1 and the solvent phase 2 becomes unclear, and the content of the hydrophobic particles 6 in the solids recovered from the water phase 1 _CB is presumed to represent that it did not decrease much.

[Example 2]
Next, the test of Example 2 will be described. In the test of Example 2, the separation process was performed in a single-stage batch process using the particle separator 8 equipped with the mixer 10 and the settler 20 shown in FIG. First, 1 L/min of water and a brominated organic solvent (1-bromopropane) were added to a mixer 10 (capacity of 0.3 L) serving as a mixing device, and 75 g/min of fly ash was charged, followed by vigorous mixing with a stirrer. The mixed liquid was continuously introduced into Settler 20 (diameter: 40 mm, height: 300 mm), which is an upflow separator, at a flow rate of 2 L/min by a pump. A brominated organic solvent phase (solvent phase 2) is formed in the lower part of the settler 20, an aqueous phase 1 is formed in the upper part, and a thin film of the brominated organic solvent phase is formed between the aqueous phase 1 and air. rice field. Then, the aqueous phase 1 was continuously withdrawn at a rate of 1 L/min from a portion approximately 3 cm below the surface layer of the aqueous phase 1 to obtain a sample of the aqueous phase 1. On the other hand, a sample of solvent phase 2 was obtained by continuously withdrawing the brominated organic solvent phase at a rate of 1 L/min from about 3 cm from the bottom of the brominated organic solvent phase. Each sample was deliquored by centrifugation (1,700 G×30 seconds) and then dried in a drying oven to collect solid matter. The hydrophobic particle separation rate K _A and the hydrophilic particle recovery rate K _B were calculated based on the above formulas (4) and (5). The fly ash used contained 13% by mass of carbon, and its volume-based 50% particle size was 21 μm. The volume-based 50% particle size was measured in the same manner as in Example 1.

As a result of the test of Example 2, the hydrophobic particle separation rate K _A was 55 mass %, and the hydrophilic particle recovery rate K _B was 90 mass %. In addition, the content C _B of the hydrophobic particles 6 in the solid recovered from the aqueous phase 1 is 6.9% by mass, and the content of hydrophobic particles in the solid recovered from the brominated organic solvent phase is It was 53% by mass. According to the test results, it was confirmed that the hydrophilic particles 5 and the hydrophobic particles 6 can be separated and collected with high separation efficiency by the separation method using the particle separation device 8 according to the present embodiment.

[Example 3]
Next, the test of Example 3 will be described with reference to FIG. Note that FIG. 15 shows changes in the content of hydrophobic particles 6 in the solid matter of the aqueous phase 1 or solvent phase 2 in each stage of the countercurrent three-stage continuous process (see FIG. 11) that does not include a washing step. show.

In the test of Example 3, a countercurrent three-stage continuous process (mixing-upflow separation, in FIG. 11 when N=3) was performed. In Example 3, the fly ash used in Example 2 was also used, and the test was conducted under the same conditions as in Example 2.

As a result of the test of Example 3, the hydrophobic particle separation rate K _A was 81 mass %, and the hydrophilic particle recovery rate K _B was 91 mass %. Further, as shown in FIG. 15, the content C _B of the hydrophobic particles 6 in the solid recovered from the aqueous phase 1 is 2.9% by mass, and the content of the solid recovered from the brominated organic solvent phase The hydrophobic particle content was 56% by weight. According to the test results, in the countercurrent three-stage continuous process of Example 3, both the hydrophobic particle separation rate K _A and the hydrophilic particle recovery rate K _B the content of the hydrophobic particles 6 in the solid recovered from the aqueous phase 1 decreases, and the content of the hydrophobic particles 6 in the solid recovered from the _brominated organic solvent phase increases. confirmed.

[Example 4]
Next, the test of Example 4 will be described with reference to FIG. In addition, FIG. 16 shows the hydrophobic particles in the solid matter of the aqueous phase 1 or the solvent phase 2 in each stage of the countercurrent four-stage continuous process (see FIG. 13) including the washing steps (S5, S6) and the washing step. 6 shows the change in the content of 6.

In the test of Example 4, a set of -1st stage mixing device and separation device shown in FIG. , S6) was carried out (mixing-upflow separation, when N=4 in FIG. 12). In Example 4, the fly ash used in Example 3 was also used, and the test was conducted under the same conditions as in Example 3.

As a result of the test of Example 4, the hydrophobic particle separation rate K _A was 82 mass %, and the hydrophilic particle recovery rate K _B was 91 mass %. Further, as shown in FIG. 16, the content C _B of the hydrophobic particles 6 in the solid recovered from the aqueous phase 1 is 2.8% by mass, and the content of the solid recovered from the brominated organic solvent phase The content of hydrophobic particles 6 was 58% by mass. According to the test results, in the countercurrent four-stage continuous process of Example 4, compared with Example 3, the washing steps (S5, S6), the fourth-stage mixing step (S1-4), and the separation step By adding ( _S2-4 ), the content of hydrophobic particles 6 in the solid recovered from the aqueous phase 1 is lowered while the hydrophobic particles in the solid recovered from the brominated organic solvent phase It was confirmed that the content of 6 can be significantly improved.

[Example 5]
Next, the test of Example 5 will be described with reference to FIG. Note that FIG. 17 shows changes in the content of the hydrophobic particles 6 similar to FIG.

In the test of Example 5, the fly ash used in Example 3 above was slurried with water (slurry concentration 500 g/l). Using a bead mill, the above slurry was put into a container (1 l) containing 1 kg of zirconia beads with a diameter of 500 μm at a rate of 1 l/min and stirred at 1500 rpm to obtain slurry after pulverization. After the pulverization, the slurry was dried to obtain the pulverized fly ash as a dry powder. Using fly ash after pulverization, the solid matter was recovered in the same manner as in Example 4, and the results shown in FIG. 17 were obtained.

As a result of the test of Example 5, the hydrophobic particle separation rate K _A was 97 mass %, and the hydrophilic particle recovery rate K _B was 97 mass %. Further, as shown in FIG. 17, the content _CB of the hydrophobic particles 6 in the solid recovered from the aqueous phase 1 is 0.4% by mass, and the content of the solid recovered from the brominated organic solvent phase The content of the hydrophobic particles 6 was 84% by mass. According to the test results, by crushing the fly ash in advance, the content of the hydrophobic particles 6 in the solid matter recovered from the aqueous phase 1 was further _lowered , while the fly ash was recovered from the brominated organic solvent phase. It was confirmed that the content of the hydrophobic particles 6 in the solid could be significantly improved.

[Example 6]
Next, a test in which a magnetic separation process using a neodymium magnet was performed for Examples 1 to 3 (see Table 4) will be described.

The iron content in the fly ash used as the object to be separated was 5.7% by mass in terms of magnetite. After this fly ash was mixed with only water to form a water slurry, a neodymium magnet was brought close to separate the magnetic substance. As a result, a magnetic substance containing 32% by mass in terms of magnetite was obtained, which was 35 mass in terms of magnetite. % iron was recovered. In addition, when a neodymium magnet was brought close to the aqueous phase 1 separated in Example 1-3 to separate the magnetic substance, a magnetic substance containing 34% by mass in terms of magnetite could be obtained, and 37% by mass in terms of magnetite. iron was recovered. Furthermore, when a neodymium magnet was brought close to the solvent phase 2 separated in Example 1-3 to separate the magnetic substances, 24% by mass of magnetic substances in terms of magnetite could be obtained. In both cases, the iron concentration in terms of magnetite increased, and it was confirmed that the magnetic substances could be recovered by the magnetic separation process. In the above test, the iron content in fly ash was measured by the ICP method and converted to magnetite (Fe ₃ O ₄ ).

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. , of course, are also understood to belong to the technical scope of the present invention.

1 Aqueous phase 2 Hydrophobic solvent phase 3 Solvent droplets 4 Water droplets 5 Hydrophilic particles 6 Hydrophobic particles 7 Concentrating part 8, 8A, 8B Particle separation device 10 Mixer (mixing device)
20 Settler (separation device)
30 First recovery device 31 Centrifuge 32 Drying device 33 Condenser 40 Second recovery device 41 Centrifugal separator 42 Drying device 43 Condenser 51, 52, 53 Magnetic separation strainer 200 Horizontal flow separation device 210 Upflow separation device S1 Mixing step S2 Separation step S3 First recovery step S4 Second recovery step S5 Mixing step for washing S6 Separation step for washing

Claims (18)

In a separation method for separating hydrophobic particles and hydrophilic particles from a mixture in which hydrophobic particles and hydrophilic particles are mixed,
A mixing step of mixing the mixture with water and a hydrophobic liquid having a higher specific gravity than the water to form a slurry;
While separating the slurry produced in the mixing step into an aqueous phase and a hydrophobic liquid phase, the hydrophilic particles are transferred to the aqueous phase and the hydrophobic particles are transferred to the hydrophobic liquid phase. , a separation step of separating the hydrophobic particles and the hydrophilic particles;
including
A separation method , wherein a combination of the mixing step and the separation step is repeated in N stages (N is an integer of 2 or more) in a countercurrent multistage continuous process . The separation method according to claim 1 , wherein the mixture is fly ash . In the separation step, the slurry is allowed to stand still in a separation device, and the slurry is divided into the aqueous phase containing the hydrophilic particles and the hydrophobic liquid containing the hydrophobic particles by using the difference in specific gravity. 3. The separation method according to claim 1 or 2 , wherein the phase is separated. N is an integer of 3 or more,
The mixture and the water are added in the mixing step of the first stage,
The hydrophobic liquid is introduced in the mixing step of the Nth stage,
The aqueous phase containing the hydrophilic particles and the remaining hydrophobic particles separated in the separation step of the n-th stage (n is an integer of 1 or more and N-2 or less), and the separation step of the n+2 stage According to any one of claims 1 to 3, the hydrophobic liquid phase containing the separated hydrophobic particles and the remaining hydrophilic particles is mixed in the n+1 stage mixing step to form a slurry. Separation method described. further comprising a washing step of removing the hydrophilic particles remaining in the hydrophobic liquid phase containing the hydrophobic particles separated in the first separation step;
The washing step includes
a cleaning mixing step of adding and mixing the water to the hydrophobic liquid phase containing the hydrophobic particles separated in the first separation step and the remaining hydrophilic particles to form a slurry;
While separating the slurry generated in the mixing step for washing into an aqueous phase and a hydrophobic liquid phase, the remaining hydrophilic particles are moved to the aqueous phase, whereby the hydrophobic particles and the remaining hydrophilic particles are separated from each other. a cleaning separation step for separating the sexual particles;
The separation method according to any one of claims 1 to 3, comprising 6. The separation method according to claim 5, wherein the combination of the washing mixing step and the washing separation step in the washing step is repeated for M stages (M is an integer of 2 or more). a first recovery step of separating the water from the aqueous phase containing the hydrophilic particles separated by the separation step and recovering the hydrophilic particles;
a second recovery step of separating the hydrophobic liquid from the hydrophobic liquid phase containing the hydrophobic particles separated by the separation step and recovering the hydrophobic particles;
further comprising
The separation according to any one of claims 1 to 6, wherein the water separated in the first recovery step and the hydrophobic liquid separated in the second recovery step are reused in the mixing step. Method. In the first collection step,
The hydrophobic liquid remaining in the aqueous phase is removed by subjecting the aqueous phase containing the hydrophilic particles separated by the separation step to at least one of heating and decompression. The separation method according to claim 7. The separation method according to any one of claims 1 to 8, further comprising a magnetic separation step of adsorbing and separating magnetic substances mixed in the mixture using a magnet. the hydrophobic liquid is a hydrophobic organic solvent,
The separation method according to any one of claims 1 to 9, wherein the specific gravity of the hydrophobic organic solvent is greater than 1.05 and smaller than the specific gravity of the hydrophobic particles. the hydrophobic liquid is a hydrophobic organic solvent,
The separation method according to any one of claims 1 to 10, wherein the hydrophobic organic solvent has a boiling point of 40°C or higher and 150°C or lower under atmospheric pressure. the hydrophobic liquid is a hydrophobic organic solvent,
The separation method according to any one of claims 1 to 10, wherein the hydrophobic organic solvent has a boiling point of 40°C or higher and 95°C or lower under atmospheric pressure. the mixture is fly ash,
The separation method according to any one of claims 1 to 12 , further comprising a pulverization step of pulverizing the fly ash prior to the separation step. In the pulverization step, at least one of a hydrophobic liquid and water is mixed with the fly ash to generate a mixed liquid, and the carbon particles as the hydrophobic particles contained in the mixed liquid are pulverized using beads. 14. Separation method according to claim 13 . 15. The separation method according to claim 14 , wherein the beads have a diameter of 1 mm or less. A method for recovering hydrophilic particles, comprising recovering the hydrophilic particles from the aqueous phase containing the hydrophilic particles separated by the separation method according to any one of claims 1 to 15 . A method for recovering hydrophilic particles, comprising recovering the aqueous phase containing the hydrophilic particles separated by the separation method according to any one of claims 1 to 15 . A method for recovering hydrophobic particles, comprising recovering the hydrophobic particles from the hydrophobic liquid phase containing the hydrophobic particles separated by the separation method according to any one of claims 1 to 15 .

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