Apparatus and method for producing complex fluoride particles

Abstract

This apparatus for producing complex fluoride particles comprises: a mixer for mixing a first solution in which a first compound that is an alkali metal fluoride is dissolved, a second solution in which a second compound having a metal element different from the alkali metal element contained in the alkali metal fluoride is dissolved, and a third solution in which a third compound that reacts with hydroxide ions to produce water is dissolved, thereby producing a mixed solution containing the complex fluoride particles; a pH detection unit for measuring the pH value of the mixed solution, which changes as water is produced; and an estimation unit for estimating the particle size of the complex fluoride particles according to the pH value.

Description

Complex fluoride particle manufacturing device and manufacturing method

[0001] The present disclosure relates to an apparatus and method for producing complex fluoride particles.

[0002] In the synthesis of inorganic compounds, the concentration and temperature distributions of raw materials result in a size distribution of the product particles. To suppress the variation in size distribution, techniques for monitoring and controlling raw material concentrations and particle sizes during the mixing process are required. Techniques such as ion chromatography (Japanese Industrial Standards JIS K 0127:2013, General Rules for Ion Chromatography) are known for monitoring concentrations. Furthermore, electron microscopes (Japanese Industrial Standards JIS K 0132-1997, General Rules for Scanning Electron Microscopy Test Methods) and dynamic light scattering (Japanese Industrial Standards JIS Z 8828:2019, Particle Size Analysis - Dynamic Light Scattering) are used to measure particle sizes. Furthermore, concentration analysis or particle size analysis can be performed using absorbance measurement techniques (see, for example, Patent Document 1).

[0003] WO2014 / 157282

[0004] Although the above-mentioned techniques of ion chromatography, electron microscopy, and dynamic light scattering can provide highly accurate measurement results, it generally takes at least several tens of minutes to measure one sample, including steps such as setting the sample, and therefore they are not suitable for monitoring information during synthesis in real time.

[0005] On the other hand, the technology of Patent Document 1 detects flow-type absorbance, which can be used to quickly measure the ion concentration of a target solution or the particle size in the solution. However, while concentration analysis reflects the intensity of light absorption by the target substance, particle size analysis reflects the intensity of light scattering by the target substance. Therefore, if the wavelength ranges of the two overlap, the detected signal intensities also overlap, making it extremely difficult to obtain accurate information.

[0006] The present disclosure has been made in consideration of the above-mentioned technical problems, and aims to provide a complex fluoride particle manufacturing apparatus that can estimate particle size in real time.

[0007] A complex fluoride particle manufacturing apparatus according to one embodiment of the present disclosure includes a mixer that generates a mixed solution containing complex fluoride particles by mixing a first solution in which a first compound that is an alkali metal fluoride is dissolved, a second solution in which a second compound having a metal element different from the alkali metal contained in the alkali metal fluoride is dissolved, and a third solution in which a third compound that reacts with hydroxide ions to generate water is dissolved; a pH detection unit that measures the pH value of the mixed solution, which changes as water is generated; and an estimation unit that estimates the particle size of the complex fluoride particles according to the pH value.

[0008] A method for producing complex fluoride particles according to one embodiment of the present disclosure includes a mixing / reaction step of producing a mixed solution containing complex fluoride particles by mixing a first solution in which a first compound that is an alkali metal fluoride is dissolved, a second solution in which a second compound having a metal element different from the alkali metal element contained in the alkali metal fluoride is dissolved, and a third solution in which a third compound that reacts with hydroxide ions to produce water is dissolved; a pH detection step of measuring the pH value of the mixed solution that changes as water is produced; and an estimation step of estimating the particle size of the complex fluoride particles based on the pH value.

[0009] According to the complex fluoride particle manufacturing apparatus according to one embodiment of the present disclosure, the particle size of the complex fluoride particles can be estimated from the measured pH value of the mixed solution during the synthesis of the complex fluoride particles, and whether the generated complex fluoride particles are good or bad can be determined in real time by comparing the pH value with a preset threshold value.

[0010] Fig. 1 is a schematic diagram showing the configuration of an apparatus for producing complex fluoride particles according to embodiment 1. Fig. 2 is a diagram showing an example of the relationship between the pH of a mixed solution and the median value D50 of the particle size distribution of the obtained complex fluoride particles. Fig. 3 is a flowchart of a method for producing complex fluoride particles using the apparatus for producing complex fluoride particles according to embodiment 1. Fig. 4 is Table 1 showing the values ​​of D10, D50, and D90 of the particle size distribution of the complex fluoride particles obtained in Example 1 and Comparative Example 1.

[0011] The complex fluoride particle manufacturing apparatus according to the first aspect includes a mixer that generates a mixed solution containing complex fluoride particles by mixing a first solution in which a first compound that is an alkali metal fluoride is dissolved, a second solution in which a second compound having a metal element different from the alkali metal element contained in the alkali metal fluoride is dissolved, and a third solution in which a third compound that reacts with hydroxide ions to generate water is dissolved; a pH detection unit that measures the pH value of the mixed solution, which changes as water is generated; and an estimation unit that estimates the particle size of the complex fluoride particles according to the pH value.

[0012] The complex fluoride particle manufacturing apparatus according to the second aspect may further include a control unit that adjusts the amounts of the first solution, the second solution, and the third solution in accordance with the estimated particle size in the first aspect.

[0013] With the above-described configuration, the particle size of the complex fluoride particles can be continuously controlled by adjusting the amount of the raw material liquid through feedback control based on the pH value.

[0014] The complex fluoride particle manufacturing apparatus according to a third aspect may be the first aspect, wherein the estimation unit estimates the particle size of the complex fluoride particles based on a correlation between the pH value and the particle size of the complex fluoride particles.

[0015] In the apparatus for producing complex fluoride particles according to a fourth aspect, in the first aspect, the third compound may be selected from a combination of a functional group, a metal element, fluorine, and hydrogen contained in either the first compound or the second compound.

[0016] The method for producing complex fluoride particles according to the fifth aspect includes a mixing / reaction step of producing a mixed solution containing complex fluoride particles by mixing a first solution in which a first compound that is an alkali metal fluoride is dissolved, a second solution in which a second compound having a metal element different from the alkali metal element contained in the alkali metal fluoride is dissolved, and a third solution in which a third compound that reacts with hydroxide ions to produce water is dissolved; a pH detection step of measuring the pH value of the mixed solution that changes as water is produced; and an estimation step of estimating the particle size of the complex fluoride particles according to the pH value.

[0017] The method for producing complex fluoride particles according to a sixth aspect may be the same as the fifth aspect, further comprising a liquid volume adjusting step of adjusting the liquid volumes of the first solution, the second solution, and the third solution in accordance with the estimated particle size.

[0018] Hereinafter, a complex fluoride particle manufacturing apparatus according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. However, unless otherwise specified, the components, types, combinations, shapes, relative positions, and the like described in the embodiment are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0019] First Embodiment <Apparatus for Producing Complex Fluoride Particles> FIG. 1 is a schematic diagram showing the configuration of an apparatus 101 for producing complex fluoride particles according to a first embodiment.

[0020] In the complex fluoride particle manufacturing apparatus 101 according to the first embodiment, a mixed liquid containing complex fluoride particles (hereinafter referred to as a "particle-containing liquid") is manufactured by a synthesis reaction in which a plurality of liquids sent from a liquid sending unit 102 are mixed in a mixer 103 and pass through a single flow path, a retention flow path unit 104. The liquid sending unit 102, which sends the plurality of liquids, and the mixer 103, which mixes the plurality of liquids, are connected by a plurality of flow paths 102a, 102b, and 102c, which send the respective liquids to be mixed, and the reaction required for particle synthesis progresses by mixing the plurality of liquids.

[0021] The complex fluoride particle manufacturing apparatus 101 according to the first embodiment includes a pH detection unit 105 that measures the pH of the particle-containing liquid flowing through a flow path that is a part of the retention flow path unit 104, an estimation unit 106 that estimates the particle size of the complex fluoride particles based on the pH value measured by the pH detection unit 105, and a control unit 107 that controls the liquid sending conditions of the liquid sending unit 102 and the opening and closing of a switching valve 108 based on the particle size estimated by the estimation unit 106. The control unit 107 determines whether the particle-containing liquid is good or bad based on the particle size of the complex fluoride particles estimated by the estimation unit 106 and a preset threshold value, and controls the switching valve 108 to send good products to a recovery unit 110 and bad products to a waste liquid container 109. The control unit 107 also controls the subsequent liquid sending conditions of the liquid sending unit 102 based on the particle size of the complex fluoride particles estimated by the estimation unit 106.

[0022] Hereinafter, each of the components constituting the complex fluoride particle manufacturing apparatus 101 will be described.

[0023] <Complex Fluoride Particles> The complex fluoride particles may contain, for example, at least one alkali metal selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium. The complex fluoride may contain fluorine, an alkali metal, and an additional metal other than the alkali metal as a main component. The additional metal may contain at least one metal selected from the group consisting of alkaline earth metals, aluminum, gallium, indium, zinc, and yttrium. Specifically, the additional metal may contain at least one metal selected from the group consisting of magnesium, calcium, strontium, barium, aluminum, gallium, indium, zinc, and yttrium. Inorganic compounds containing these metal elements can be easily molded into compacts, for example, by a pressurized heating method. Note that the term "main component" as used herein means that the total content of fluorine, alkali metal, and additional metal contained in the complex fluoride particles is 80% or more in molar ratio. The total content may be 85% or more, 90% or more, 95% or more, or even 100%.

[0024] Specifically, the complex fluoride particles are３ AlF ６ and ABF ３ (wherein, in the above composition formula, A represents one or more of the above-mentioned alkali metals, and B represents one or more of the above-mentioned alkaline earth metals). ３ AlF ６ For example, Li ３ AlF ６ , Li ２ NaAlF ６ , Li ２ KAlF ６ , Na ３ AlF ６ , Na ２ LiAlF ６ , Na ２ KAlF ６ , K. ３ AlF ６ , K. ２ LiAlF ６ and K. ２ NaAlF ６ ABF ３ For example, LiMgF ３ , NaMgF ３ , KMgF ３ , LiCaF ３ , NaCaF ３ and KCaF ３ The complex fluoride may contain at least one selected from the group consisting of: ３ AlF ６ and NaMgF ３ It may contain at least one selected from the group consisting of:

[0025] The complex fluoride particles may contain fluorine, an alkali metal, and aluminum as main components. Here, the term "main components" means that the total content of fluorine, alkali metal, and aluminum contained in the complex fluoride particles is 80% or more by molar ratio. The total content may be 85% or more, 90% or more, 95% or more, or even 100%.

[0026] <Regarding the reaction for producing complex fluoride particles> As the complex fluoride particles, for example, Na ３ AlF ６ In this case, the reaction is, for example, as follows: 3NaF + 3NH ４ F + AlCl ３ →Na ３ AlF ６ +3NH ４ In the above Cl production reaction, NaF is the first compound, which is an alkali metal fluoride. ３ is a second compound having a metal element different from the alkali metal fluoride. ４ F is a third compound that reacts with hydroxide ions to produce water, as described below.

[0027] When Li or K is used as the alkali metal instead of Na, the Na in the above-mentioned reaction can be replaced with Li or K. The above-mentioned reaction is merely an example, and the reaction is not limited to the above-mentioned reaction. Furthermore, when the complex fluoride particles are different, the reaction will naturally be different.

[0028] <Side Reactions> The following side reactions occur separately from the above-mentioned production reactions, and react with hydroxide ions to produce water: NH ４ ＋ +OH － →NH ３ +H ２ As the side reaction proceeds, the pH of the particle-containing liquid shifts from alkaline to neutral. Therefore, by measuring the pH of the particle-containing liquid, changes in the pH due to the progression of the side reaction can be detected. As shown in the reaction formula above, along with the change in pH, a change in concentration occurs due to the generation of water. Specifically, the raw material concentration decreases because water is generated by the side reaction.

[0029] Here, as the fluorine source, not only NaF but also NH ４ By using F, it is possible to cause the side reaction of reacting with hydroxide ions to produce water. ４F acts as a third compound that reacts with hydroxide ions to produce water.

[0030] It is desirable that the third compound does not contain any extra elements or functional groups in the main raw materials in the production reaction, and therefore the third compound may be selected from a combination of functional groups, metal elements, fluorine, and hydrogen contained in either the first compound or the second compound.

[0031] <Liquid Delivery Section> The liquid delivery section 102 may be configured with a liquid delivery device such as a syringe pump, plunger pump, diaphragm pump, tube pump, mono pump, or piezo pump, as long as it can deliver a plurality of liquids.

[0032] In FIG. 1, three flow paths 102a, 102b, and 102c extending from a liquid supply unit 102 supply, respectively, a solution of a first compound which is, for example, an alkali metal fluoride, a solution of a second compound which has a metal element different from the alkali metal fluoride, and a solution of a third compound which reacts with hydroxide ions to produce water.

[0033] The mixer 103 may be any mixer capable of mixing multiple liquids in a flow path, and may be configured with a flow path connecting member such as a union tee or manifold of a pipe joint, or a flat plate provided with grooves or through holes, which is fabricated by bonding or stacking multiple flat plates together and fixing them together. Specifically, for example, the mixer may be configured using a four-way joint.

[0034] The present invention is not limited to the simultaneous mixing of solutions in three or more flow paths as described above. For example, three or more solutions may be mixed stepwise in sequence, such as by mixing two solutions that do not cause a reaction to produce complex fluoride particles and then mixing another solution.

[0035] <Retention Channel Portion> The retention channel portion 104 is a channel that connects the mixer 103 and the switching valve 108 .

[0036] <pH detection unit> The pH detection unit 105 is required only to be able to measure the pH of the liquid in the flow path of the retention flow path unit 104, and is composed of, for example, a glass electrode whose potential changes depending on the pH, and a reference electrode for measuring its relative potential.

[0037] <Estimation Unit> The estimation unit 106 estimates the particle size in the liquid from the pH value measured by the pH detection unit 105, utilizing the correlation between the pH value and the particle size (for example, particle diameter D50).

[0038] 2 is a diagram showing an example of the relationship between the pH of the mixed solution (particle-containing liquid) and the median value D50 of the particle size distribution of the obtained complex fluoride particles. For example, FIG. 2 shows a correlation in which the particle size D50 of the complex fluoride particles decreases as the pH value of the particle-containing liquid increases, and the particle size D50 increases as the pH value decreases.

[0039] The estimation unit 106 can estimate the particle size of the complex fluoride particles contained in the particle-containing liquid based on the measured pH value, for example, the relationship between the pH value and the particle diameter D50 shown in Fig. 2. Note that Fig. 2 is an example, and the relationship between the pH value and the particle diameter D50 varies depending on the production reaction and side reaction of the complex fluoride particles. Also, although the particle diameter D50 is used as the particle size in Fig. 2, the present invention is not limited to this.

[0040] <Control Unit> Based on the particle size of the complex fluoride particles in the particle-containing liquid estimated by the estimation unit 106 and a preset threshold, the control unit 107 determines that the particle-containing liquid that meets the preset threshold is a good product, and determines that the particle-containing liquid that does not meet the threshold is a defective product. The control unit controls the switching valve 108 to send the particle-containing liquid determined to be a good product to the recovery unit 110, and to send the particle-containing liquid determined to be a defective product to the waste liquid container 109. Furthermore, based on the particle size estimated by the estimation unit 106, the control unit 107 adjusts the liquid sending conditions of the corresponding pH liquid sending unit 102, such as the liquid sending amount, so as to control the particle size to a more appropriate size.

[0041] <Method for producing complex fluoride particles> Fig. 3 is a flowchart of a method for producing complex fluoride particles using the apparatus for producing complex fluoride particles according to embodiment 1 of the present disclosure. The method for producing complex fluoride particles will be described with reference to Fig. 3 .

[0042] (1) First, the liquid delivery unit 102 starts delivering a plurality of source liquids (S200). For example, in the example shown in Fig. 1, a solution of a first compound, which is an alkali metal fluoride, is delivered through the flow path 102a, a solution of a second compound having a metal element different from the alkali metal fluoride is delivered through the flow path 102b, and a solution of a third compound that reacts with hydroxide ions to produce water is delivered through the flow path 102c.

[0043] Next, the solutions from the three flow paths 102a, 102b, and 102c are mixed in a mixer 103 to generate a particle-containing liquid containing complex fluoride particles, and the particle-containing liquid containing complex fluoride particles is sent through a retention flow path section 104 connected to the mixer 103.

[0044] (2) Next, the pH value of the particle-containing liquid flowing through the retention flow path section 104 is detected by the pH detection section 105 (S201).

[0045] (3) Next, in step S202, the estimation unit 106 starts calculating the particle size (particle diameter D50) of the complex fluoride particles from the pH value measured by the pH detection unit 105. For example, the particle diameter D50 corresponding to the pH value is acquired based on the correlation between the pH value and the particle diameter D50 of the particle-containing liquid shown in FIG.

[0046] (4) Next, the control unit 107 compares the value of the particle diameter D50 calculated by the estimation unit 106 with a preset threshold value of the particle diameter D50 (S203).

[0047] (4-1) Here, if the particle diameter D50 is within the range of the threshold value set in advance, the obtained mixed solution containing the complex fluoride particles is determined to be a non-defective product, and the switching valve 108 is opened in the direction of the recovery vessel 110 (S204), and the liquid transfer is terminated when the specified amount is reached (S205).

[0048] (4-2) If the particle diameter D50 is outside the range of the preset threshold value, the obtained mixed solution containing the complex fluoride particles is determined to be defective, and the switching valve 108 is opened toward the waste liquid container 109 (S206) and discarded. Thereafter, based on the particle diameter D50 calculated by the estimation unit 106 and the preset threshold value of the particle diameter D50, the liquid sending conditions (e.g., the amount of liquid sent) of the liquid sending unit 102 are adjusted (S207), and the pH is measured again (S201).

[0049] As described above, by measuring the pH value of the particle-containing liquid, the particle size (particle diameter D50) of the complex fluoride particles can be estimated, and it can be determined whether the complex fluoride particles contained in the particle-containing liquid are good or bad.

[0050] Furthermore, by controlling the liquid feeding conditions, such as the liquid feeding rate of each raw material solution in the liquid feeding unit 102, based on the estimated particle size (particle diameter D50), feedback control can be performed almost in real time, and even if a defective product is produced, the liquid feeding rate can be immediately controlled, thereby continuously controlling the particle size in the subsequent production of complex fluoride particles. Therefore, when a constant amount of complex fluoride particles is produced, variation in particle size can be suppressed, and complex fluoride particles with a narrow particle size distribution can be obtained.

[0051] (Examples and Comparative Examples) Hereinafter, a prototype of the complex fluoride particle manufacturing apparatus 101 according to the present disclosure was produced, and Na ３ AlF ６ An example of producing particles will be described.

[0052] Example 1 Six double plunger pumps were used as the liquid delivery unit 102 to deliver three types of compound solutions and ultrapure water for diluting each of the compound solutions. A four-way joint made of PEEK material with an inner diameter of 0.5 mm was used as the mixer 103 to mix the diluted and adjusted three types of compound solutions. A PFA tube with an inner diameter of 0.5 mm was used as the retention flow path unit 104 to form a flow path and connect each part.

[0053] A pH meter was used as the pH detection unit 105. A personal computer was used as the estimation unit 106 and the control unit 107, and the control unit 109 was used to control the liquid delivery unit 102 and the switching valve 108.

[0054] Na ３ AlF ６ As compound solutions for synthesizing particles, a first solution containing 768 mM sodium fluoride as the first compound, a second solution containing 640 mM aluminum chloride hexahydrate as the second compound, and a third solution containing 768 mM ammonium fluoride as the third compound were prepared. Furthermore, ultrapure water for dilution was prepared to adjust the above-mentioned three compounds to the specified concentrations, and before the three compounds were mixed in the four-way joint, they were diluted and mixed in a two-way joint made of PEEK material. The set flow rates of each plunger pump were adjusted so that the flow rate of the mixed solution in the four-way joint was 10 mL / min, and 45 mL of particle-containing liquid was collected in the collector 110.

[0055] Generally, in the synthesis of inorganic compounds in a liquid phase, the size of inorganic compound particles varies depending on the concentration of raw materials. This is because the degree of supersaturation of the product affects the number of particle nuclei and the degree of particle growth. For example, the higher the raw material concentration, the smaller the particle size.

[0056] In this example, when three kinds of compound solutions are mixed, the target Na ３ AlF ６ In addition to the reaction that produces particles, a side reaction occurs in which ammonium reacts with hydroxide ions in the liquid. This causes a change in pH and H ２ Since the concentration change accompanying the generation of O simultaneously occurs, by previously knowing the correlation between the pH value and particle size, it is possible to estimate the particle size by measuring the pH. Furthermore, by adjusting the amount of raw material fed so as to maintain a specified pH value, it is possible to produce size-controlled particles. In this embodiment, the particle size range for non-defective products was set to 500 nm ± 100 nm. If the estimated particle size is below 400 nm, the relative feed rate of the third solution is increased to lower the raw material concentration, and feedback control is performed to increase the particle size of the complex fluoride particles obtained thereafter. On the other hand, if the estimated value is above 600 nm, the relative feed rate of the third solution is decreased to increase the raw material concentration, and feedback control is performed to reduce the particle size of the complex fluoride particles obtained thereafter.

[0057] This makes it possible to obtain homogeneous complex fluoride particles with a narrow particle size distribution.

[0058] Comparative Example 1 The configuration of the apparatus was the same as in Example 1, and in Comparative Example 1, 45 mL of particle-containing liquid was collected in the collector 110 without carrying out the particle size evaluation and control described above.

[0059] FIG. 4 is Table 1 showing the D10, D50, and D90 values ​​of the particle size distribution of the complex fluoride particles obtained in Example 1 and Comparative Example 1, respectively.

[0060] The results of Example 1 and Comparative Example 1 will be explained with reference to Table 1 in FIG.

[0061] Table 1 in FIG. 4 shows the cumulative frequency distribution of particle sizes measured by dynamic light scattering for particles obtained from the recovered liquid.

[0062] First, focusing on D50, which represents the median particle size in the cumulative frequency distribution of particle sizes, it was 507.6 nm in Example 1 and 451.5 nm in Comparative Example 1. It is believed that in Comparative Example 1, particle groups formed at a pH value higher than the ideal value in the initial stage of mixing were also recovered, resulting in particle groups with a smaller median particle size than in Example 1. The above is also reflected in D10, which indicates that the proportion of particle sizes equal to or smaller than the measured value is 10% in the cumulative frequency distribution, and was 314.7 nm in Example 1 and 236.3 nm in Comparative Example 1.

[0063] Furthermore, focusing on D90, it was 851.8 nm in Example 1, while it was 932.1 nm in Comparative Example 1. The increase in particle size can be attributed to the growth of primary particles or the formation of secondary particles due to aggregation between primary particles. Generally, the smaller the primary particle size, the higher the surface energy, which leads to higher aggregation force and easier formation of secondary particles. That is, in Example 1, size control was performed, and a relatively large number of particles close to the 500 nm ± 100 nm set as the acceptable value were recovered, while in Comparative Example 1, where size control was not performed, large primary particles and secondary particles were also recovered.

[0064] Furthermore, the difference between D10 and D90 is generally considered to be an index of particle size distribution, and it was shown that Example 1 yielded particles with a narrower distribution than Comparative Example 1.

[0065] A particle group with a relatively narrow distribution was obtained in Example 1, whereas a particle group with an even wider distribution was obtained in Comparative Example 1. From the above, it was demonstrated that the complex fluoride particle manufacturing apparatus according to the present disclosure can manufacture complex fluoride particles with high size uniformity by providing a pH detection unit to estimate particle size and performing control to appropriately adjust the amount of liquid of raw material.

[0066] According to the complex fluoride particle manufacturing apparatus and manufacturing method of the present disclosure, the particle size of the complex fluoride particles can be estimated from the pH measured during synthesis, and whether the generated complex fluoride particles are good or bad can be determined in real time by comparing the pH with a preset threshold value.

[0067] 101 Manufacturing apparatus 102 Liquid delivery section 103 Mixer 104 Retention channel section 105 pH detection section 106 Estimation section 107 Control section 108 Switching valve 109 Wastewater container 110 Recovery container

Claims

1. A complex fluoride particle manufacturing apparatus comprising: a mixer that generates a mixed solution containing complex fluoride particles by mixing a first solution in which a first compound that is an alkali metal fluoride is dissolved, a second solution in which a second compound having a metal element different from the alkali metal element contained in the alkali metal fluoride is dissolved, and a third solution in which a third compound that reacts with hydroxide ions to generate water is dissolved; a pH detection unit that measures the pH value of the mixed solution, which changes as the water is generated; and an estimation unit that estimates the particle size of the complex fluoride particles according to the pH value.

2. The complex fluoride particle manufacturing apparatus according to claim 1, further comprising a control unit that adjusts the amounts of the first solution, the second solution, and the third solution in accordance with the estimated particle size.

3. The complex fluoride particle manufacturing apparatus according to claim 1, wherein the estimation unit estimates the particle size of the complex fluoride particles based on the correlation between the pH value and the particle size of the complex fluoride particles.

4. The complex fluoride particle manufacturing apparatus according to claim 1, wherein the third compound is selected from a combination of a functional group, a metal element, fluorine, and hydrogen contained in either the first compound or the second compound.

5. A method for producing complex fluoride particles, comprising: a mixing / reaction step of producing a mixed solution containing complex fluoride particles by mixing a first solution in which a first compound that is an alkali metal fluoride is dissolved, a second solution in which a second compound having a metal element different from the alkali metal element contained in the alkali metal fluoride is dissolved, and a third solution in which a third compound that reacts with hydroxide ions to produce water is dissolved; a pH detection step of measuring the pH value of the mixed solution that changes as the water is produced; and an estimation step of estimating the particle size of the complex fluoride particles according to the pH value.

6. The method for producing complex fluoride particles according to claim 5, further comprising a liquid volume adjusting step of adjusting the liquid volumes of the first solution, the second solution, and the third solution in accordance with the estimated particle size.

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