Method for producing fine particles of metal compound, and fine particles of metal compound

Abstract

This method for producing fine particles of a metal compound uses a crystallization device provided with: a stirring blade that has a plurality of holes penetrating in a radial direction and that is rotatable around a central axis; a bottomed cylindrical reaction tank capable of concentrically storing the stirring blades inside the reaction tank; a first liquid supply part that is provided to the reaction tank and that is capable of supplying a first reaction liquid to the inside of the reaction tank; and a second liquid supply part that is provided to the stirring blade and that is capable of supplying a second reaction liquid to the inside of the reaction tank, the method involving: supplying the first reaction liquid from the first liquid supply part and supplying the second reaction liquid from the second liquid supply part; and rotating the stirring blade at a circumferential velocity of 25 m / s or more and thereby reacting the first reaction liquid and the second reaction liquid to precipitate fine particles of a metal compound.

Description

METHOD FOR PRODUCING METAL COMPOUND MICROPARTICLES, METAL COMPOUND MICROPARTICLES

[0001] The present invention relates to a method for producing fine particles of a metal compound, and fine particles of a metal compound.

[0002] There is a demand for higher capacity and higher output in cathode materials for next-generation batteries such as high-performance secondary batteries and all-solid-state batteries.

[0003] To achieve high capacity and high output, research is underway to increase the nickel content in the positive electrode material and to reduce the particle size (secondary particle size).

[0004] Coprecipitation is a commonly used method for producing metal hydroxides, the raw material for cathode materials. To achieve higher capacity, increasing the nickel content in the metal hydroxide increases the particle size of the metal hydroxide obtained by the coprecipitation method, which conflicts with the need for microparticulation to achieve high power output. To achieve both high capacity and high power output, research is underway to develop a technology that can increase the nickel content and produce microparticulate metal hydroxides.

[0005] Methods for increasing the nickel content and reducing the particle size include shortening the residence time of the crystals in the reaction vessel and increasing the pH. While these methods can reduce the secondary particle size, excessive shortening of the residence time or high pH leads to a decrease in crystal quality, such as miniaturization of primary particles and deterioration of the shape of secondary particles (deterioration in sphericity). Therefore, the limit to maintaining crystal quality is the limit of adjustment using these methods. Here, sphericity is defined as (diameter of the circle equivalent to the area of ​​the projected image of the particle) / (diameter of the smallest circumscribed circle of the projected image of the particle).

[0006] Although research has been conducted into suppressing particle size growth by increasing the stirring and shear forces in the reactor, there is a need to efficiently transmit high stirring and shear forces to the micro-reaction field of metal hydroxides, which have extremely short reaction times. In particular, when producing ultrafine particles with an average particle diameter d50 of 3 μm or less using metal hydroxides with a high nickel content, the challenge in increasing sphericity lies in efficiently transmitting high stirring and shear forces to the micro-reaction field.

[0007] Patent Document 1 discloses the production of a positive electrode active material for a non-aqueous electrolyte secondary battery having an average particle size of 1.00 μm to 3.0 μm and a nickel content of up to 80% using a pump and a propeller-type rotor as an agitator. Patent Document 2 discloses a positive electrode active material precursor for a lithium-ion secondary battery having an average particle size of 3 to 15 μm and a nickel content of up to 30%. Patent Document 3 discloses the production of an oxide-based positive electrode active material for an all-solid-state lithium-ion battery having an average particle size d50 of 1.0 to 5.0 μm using a turbine impeller as an agitator.

[0008] Republished WO2019 / 117027 Publication Japanese Patent Application Publication No. 2021-136096 International Publication No. 2020 / 202602 Pamphlet

[0009] The present invention has been made against this background, and aims to provide a method for producing fine particles of a metal compound that have a high nickel content and are micronized, and that can achieve high capacity and high output to the extent that they can be used as positive electrode materials for next-generation batteries, and to provide fine particles of the metal compound.

[0010] A first aspect of the present invention is a method for producing fine particles of a metal compound, which uses a crystallization apparatus including: an agitator blade having a plurality of holes penetrating in the radial direction and rotatable around a central axis; a bottomed cylindrical reaction tank capable of concentrically accommodating the agitator blade inside; a first liquid supply unit provided in the reaction tank and capable of supplying a first reaction liquid to the inside of the reaction tank; and a second liquid supply unit provided in the agitator blade and capable of supplying a second reaction liquid to the inside of the reaction tank; the first reaction liquid is supplied from the first liquid supply unit and the second reaction liquid is supplied from the second liquid supply unit; and the agitator blade is rotated at a peripheral speed of approximately 25 m / s or more, thereby reacting the first reaction liquid with the second reaction liquid and precipitating fine particles of the metal compound.

[0011] According to the first aspect of the present invention, fine particles of a metal compound having a small average particle size and high sphericity can be obtained.

[0012] A second aspect of the present invention is a method for producing fine particles of a metal compound, characterized in that, in the first aspect, the stirring blade of the crystallization device comprises a cylindrical portion, a disk-shaped disk portion whose outer edge is fixed to the inner surface of the cylindrical portion, and a rotating shaft extending upward from the center of the disk portion along the central axis in a planar view, the second reaction liquid can flow through the interior of the disk portion and the rotating shaft, and the second liquid supply portion is provided on the outer edge of the disk portion.

[0013] According to the second aspect of the present invention, the second reaction liquid can be supplied within a range close to the inner and outer periphery of the stirring blade, where shear force is high, and fine particles of a metal compound having a small average particle size and high sphericity can be obtained.

[0014] A third aspect of the present invention is the method for producing fine particles of a metal compound according to the second aspect, characterized in that the second liquid supply part of the crystallizer opens downward.

[0015] According to the third aspect of the present invention, the second reaction liquid can be supplied within a range close to the inner and outer peripheries of the stirring blades, where shear force is high, and fine particles of a metal compound having a small average particle size and high sphericity can be obtained.

[0016] A fourth aspect of the present invention is a method for producing fine particles of a metal compound according to the third aspect, wherein the cylindrical portion of the crystallization device above the disk portion has a plurality of holes penetrating in the radial direction blocked, and a second disk portion having an outer periphery fixed to the inner circumferential surface of the cylindrical portion is provided at the upper end of the cylindrical portion.

[0017] According to the fourth aspect of the present invention, it is possible to reduce the power required to rotate the stirring blades and obtain fine particles of a metal compound having a small average particle size and high sphericity.

[0018] A fifth aspect of the present invention is the method for producing fine particles of a metal compound according to the third aspect, characterized in that the disk portion of the crystallizer is provided at the upper end of the cylindrical portion.

[0019] According to the fifth aspect of the present invention, it is possible to reduce the power required to rotate the stirring blades and obtain fine particles of a metal compound having a small average particle size and high sphericity.

[0020] A sixth aspect of the present invention is the method for producing fine particles of a metal compound according to any one of the second to fifth aspects, wherein He / L3 is 10 or more, where L3 is the clearance between the outer peripheral surface of the cylindrical portion of the crystallizer and the inner peripheral surface of the reaction tank, and He is the height of the cylindrical portion.

[0021] According to the sixth aspect of the present invention, fine particles of a metal compound having a small average particle size and high sphericity can be obtained.

[0022] A seventh aspect of the present invention is a method for producing fine particles of a metal compound according to any one of the first to sixth aspects, characterized in that a plurality of second liquid supply parts are provided in the crystallization device.

[0023] According to the seventh aspect of the present invention, the second reaction liquid can be supplied uniformly in the circumferential direction of the disk portion, and fine particles of a metal compound having a small average particle size and high sphericity can be obtained.

[0024] An eighth aspect of the present invention is a method for producing fine particles of a metal compound according to any one of the first to seventh aspects, comprising: the crystallization device; a circulation pipeline that flows a slurry containing the fine particles discharged from an outlet of the crystallization device and circulates the slurry from the first liquid supply part of the crystallization device into the crystallization device; and a circulation pump that circulates the slurry between the crystallization device and the circulation pipeline, wherein the circulation pipeline uses a crystallization system having a serpentine bend, and the metal-based raw material fed to the crystallization system contains nickel in an amount of 90% or more by substance ratio.

[0025] According to the eighth aspect of the present invention, fine particles of a metal compound can be obtained that have a high nickel content, a small average particle size, and high sphericity.

[0026] A ninth aspect of the present invention is a method for producing fine particles of a metal compound according to the eighth aspect, characterized in that the pH of the mixed solution of the first reaction solution and the second reaction solution and the residence time of the fine particles in the crystallization system are maintained constant.

[0027] According to the ninth aspect of the present invention, fine particles of a metal compound can be obtained which have a high nickel content, a small average particle size, and high sphericity.

[0028] A tenth aspect of the present invention is a method for producing fine particles of a metal compound, characterized in that in the eighth or ninth aspect, the average particle diameter d50 of the fine particles is adjusted by adjusting the peripheral speed of the stirring blade.

[0029] According to the tenth aspect of the present invention, metal compound microparticles having a high nickel content, a small average particle size, and high sphericity can be obtained. In other words, the average particle size of the resulting metal compound microparticles can be controlled primarily by adjusting the peripheral speed of the agitator blades. In other words, by adjusting the peripheral speed of the agitator blades, the shear force and circulating flow can be independently controlled, enabling agitation in the reaction vessel that is specialized for the transmission of shear force. A major benefit of this improved mechanism is that particle size can be controlled primarily by adjusting the peripheral speed of the agitator blades. Unlike conventional particle size control that relies on adjusting residence time and pH value, this method allows particle size control primarily by adjusting the peripheral speed of the agitator blades while maintaining constant residence time and pH values ​​under conditions that do not degrade product quality. This improved functionality allows particle size control while maintaining residence time and pH value that do not deteriorate particle shape, resulting in the production of high-quality, high-nickel metal hydroxides with a small average particle size and high sphericity.

[0030] An eleventh aspect of the present invention is fine particles of a metal compound produced by the production method according to any one of the first to tenth aspects, the fine particles having an average particle size d50 of 3 μm or less and a nickel mass ratio of 90% or more.

[0031] According to the eleventh aspect of the present invention, it is possible to obtain fine particles of a metal compound having high sphericity, a high nickel content, and an average particle size of 3 μm or less.

[0032] A twelfth aspect of the present invention is the eleventh aspect, wherein the fine particles are fine particles of a metal compound, which are fine particles of a ternary metal hydroxide composed of nickel, cobalt, and manganese.

[0033] According to the twelfth aspect of the present invention, it is possible to obtain fine particles of a ternary metal hydroxide composed of nickel, cobalt, and manganese, which have high sphericity, a high nickel content, and an average particle size of 3 μm or less.

[0034] According to the present invention, it is possible to provide a method for producing a metal compound and fine particles of the metal compound that have a high nickel content and are microparticulate, and that can achieve high capacity and high output to the extent that they can be used as positive electrode materials for next-generation batteries.

[0035] FIG. 1 is a schematic diagram of a crystallization system according to a first embodiment of the present invention. FIG. 2 is an enlarged view of a main portion of the crystallization system according to the first embodiment of the present invention. FIG. 3 is a graph showing the relationship between the average particle size of microparticles produced using the crystallization system according to the first embodiment of the present invention and the peripheral speed of the stirring blades. FIG. 4 is a photograph of microparticles produced using the crystallization system according to the first embodiment of the present invention. FIG. 5 is a photograph of microparticles produced using a crystallization system of the prior art. FIG. 6 is a photograph of microparticles produced using the second or third modified version of the crystallization system according to the first embodiment of the present invention. FIG. 7 is a schematic diagram of a crystallization system according to a first modified version of the first embodiment of the present invention. FIG. 8 is a schematic diagram of a crystallization system according to a second modified version of the first embodiment of the present invention. FIG. 9 is a schematic diagram of a crystallization system according to a third modified version of the first embodiment of the present invention.

[0036] First Embodiment A crystallization system 10A according to a first embodiment of the present invention will be described below with reference to FIG.

[0037] The crystallization system 10A includes a crystallizer 4 that mixes multiple raw material solutions to generate particles derived from the raw materials in these multiple raw material solutions, a circulation line Po that is provided downstream of the crystallizer 4 and circulates a slurry D1 discharged from an outlet 6 of the crystallizer 4 to an inlet (first liquid supply section) 5a of the crystallizer 4, and a circulation pump 30 that circulates the slurry D1 between the crystallizer 4 and the circulation line Po. In the following description, particles may be referred to as fine particles or fine particles of a metal compound.

[0038] The circulation pipeline Po has a bent portion Pp, which is a serpentine pipeline. The circulation pipeline Po further has a pipe 22 connecting the crystallizer 4 to the bent portion Pp, a pipe 23 connecting the circulation pump 30 to the bent portion Pp, and a pipe 24 connecting the circulation pump 30 to the crystallizer 4. The bent portion Pp is not limited to a serpentine shape and may have a spiral shape.

[0039] The circulation pump 30 is a circulation pump that has a function of circulating the slurry D1 between the crystallizer 4 and the bent portion Pp in an adjustable flow rate. However, the circulation pump 30 is not necessarily limited to a circulation pump as long as it has a similar function. For example, an impeller with a controllable rotation speed may be provided in the pipe 23 or the pipe 24.

[0040] The crystallizer 4 comprises a bottomed, cylindrical reaction vessel 1 having a vertically oriented central axis O1 and a cylindrical agitator Wc. The agitator Wc is rotatable around a hollow rotary shaft 3 extending upward along the central axis O1 from the center of the agitator Wc in a plan view, and is housed inside the reaction vessel 1 with the central axis O1 as the central axis. The rotary shaft 3 is rotated by torque supplied via a belt B from a prime mover M provided outside the crystallizer 4. The prime mover M is not particularly limited as long as it is a device that generates rotational power, such as a motor or engine. The belt B that transmits the torque to the rotary shaft 3 is not particularly limited as long as it can transmit torque, such as a chain or gears. The bottom of the reaction vessel 1 may be flat as shown in the figure, or may be cone-shaped with a convex downwards. An outlet 6 is provided at the top of the reaction vessel 1, through which a slurry containing particles (crystals) produced in the reaction vessel 1 can be discharged to the next process. A pressure indication controller that maintains or adjusts the pressure of the slurry D1 discharged from the discharge port 6 to the pipe 22 is provided on the pipe 22. Details of the stirring blade Wc will be described later.

[0041] An inlet 5a is provided at the bottom of the reaction vessel 1 to supply the first reaction liquid L1 and the slurry D1 that has flowed through the circulation pipe Po. The first reaction liquid L1 is supplied with the auxiliary raw material S from the outside. Ａ and S Ｂ The auxiliary material S is supplied from a tank (not shown) that stores the Ａ and S Ｂ The auxiliary material S of the first reaction liquid L1 is supplied and mixed. Ａ and S Ｂ The flow rate is measured by the Flow Indication Controller (FIC) ２ , F.I.C. ３ The first reaction liquid L1 is supplied from the inlet 5a to the reaction vessel 1 in a predetermined amount. The supply amount of the first reaction liquid L1 from the inlet 5a can be adjusted to a predetermined amount by, for example, adjusting the rotation speed of the circulation pump 30. A pressure indicator PI is provided in the pipe 24 through which the first reaction liquid L1 flows, as needed. １Further, a second reaction liquid L2 is supplied into the reaction vessel 1 from a liquid supply part (second liquid supply part) 5b provided on the stirring blade Wc. The second reaction liquid L2 is supplied from an external main raw material S Ｍ The flow rate of the second reaction liquid L2 is controlled by a flow rate indicating controller FIC １ The first reaction liquid L1 and the second reaction liquid L2 supplied into the reaction vessel 1 react with each other to produce precipitated and crystallized fine particles of a metal compound. The slurry D1 is a fluid containing these fine particles of the metal compound.

[0042] The bent portion Pp is made up of a plurality of straight pipe portions (Po1, Po2, Po3, Po4, Po5, Po6) with an inner diameter r2 that are arranged to face substantially the same direction at intervals from each other, and a plurality of curved pipe portions C (C) with an inner diameter r3 that connect the adjacent straight pipe portions Po1, Po2, Po3, Po4, Po5, Po6 in a separable or detachable manner. １ , C ２ , C ３ , C ４ , C ５ The plurality of bent pipe sections C are separable, for example, the bent pipe section C provided to connect the straight pipe section Po5 and the straight pipe section Po6. ５ This means that the curved pipe portion C can be separated from the straight pipe portion Po5 and the straight pipe portion Po6. ５ The method of attaching and detaching the straight pipe portion Po5 and the straight pipe portion Po6 is as follows: ５ and at the left end of the straight pipe section Po5 and the straight pipe section Po6. By tightening or loosening the flanges using bolts, nuts, etc., the curved pipe section C can be tightened or loosened relative to the straight pipe section Po5 and the straight pipe section Po6. ５ The method of attachment and detachment is not limited to this, and as long as it is detachable, for example, it is not limited to the method of using a flange portion, but may be a method of attaching and detaching a curved pipe portion C to the left end of the straight pipe portion Po5 and the straight pipe portion Po6. ５The fixing plate 21 may be attached and detached by screwing both ends of the fixing plate 21. Although the fixing plate 21 is rectangular in shape in FIG. 1 , the material and shape of the fixing plate 21 are not particularly limited as long as the multiple straight pipe sections Po1, Po2, Po3, Po4, Po5, and Po6 can be held fixed to the fixing plate 21. As described above, in the multiple separable straight pipe sections and multiple curved pipe sections C, the inner surfaces of the straight pipe sections and curved pipe sections C can be easily cleaned by separating them, thereby improving the maintainability of the crystallization system 10A.

[0043] In the example of FIG. 1, the straight pipe section is composed of six straight pipe sections, namely, straight pipe section Po1, straight pipe section Po2, straight pipe section Po3, straight pipe section Po4, straight pipe section Po5, and straight pipe section Po6, and the curved pipe section C is composed of the curved pipe section C １ , curved pipe part C ２ , curved pipe part C ３ , curved pipe part C ４ , curved pipe part C ５ However, the present invention is not limited to this example. The straight pipe section Po may be composed of six or more straight pipe sections Po, or six or less straight pipe sections Po. The number of curved pipe sections C increases or decreases according to the number of straight pipe sections Po. For example, in the example of FIG. 1, the first end of the curved pipe section C is connected to the right end of the straight pipe section Po3. ２ The second end of the bent pipe C may be connected to the left end of the pipe 22. ２ The bent pipe section C is provided with a bellows section that can be freely stretched and bent. ２ may be stretchable.

[0044] In this way, the pipeline length of the bent portion Pp, i.e., the total length of the straight pipe portions and the curved pipe portions C (the number of straight pipe portions and curved pipe portions C), can be adjusted as desired to retain the slurry D1 for a desired retention time. That is, if a longer retention time is desired, it is desirable to increase the number of straight pipe portions and curved pipe portions C to lengthen the pipeline length of the bent portion Pp, and if a shorter retention time is desired, it is desirable to decrease the number of straight pipe portions and curved pipe portions C to shorten the pipeline length of the bent portion Pp.

[0045] Here, the flow rate of the slurry D1 is determined by the specific gravity and diameter of the particles that make up the slurry D1. That is, the settling rate of the particles that make up the slurry D1 is determined by the specific gravity and diameter of the particles that make up the slurry D1, so the flow rate of the slurry D1 is determined so that the slurry D1 flows through the piping without settling. Therefore, the pipe length of the bent portion Pp can be calculated from the desired residence time of the slurry D1 and the flow rate of the slurry D1 that prevents the slurry D1 from settling.

[0046] The crystallizer 4 and the bent portion Pp are connected by a pipe 22 with an inner diameter r1. The bent portion Pp and the circulation pump 30 are connected by a pipe 23 with an inner diameter r4. The circulation pump 30 and the crystallizer 4 are connected by a pipe 24 with an inner diameter r5. In the example of FIG. 1, the inner diameter of the circulation pipeline Po, that is, the inner diameter r1 of the pipe 22, the inner diameter r2 of the straight pipe portions Po1, Po2, Po3, Po4, Po5, and Po6, and the inner diameter r3 of the bent pipe portion C are １ , C ２ , C ３ , C ４ , C ５ In this case, the inner diameter r3 of the pipe 22, the inner diameter r4 of the pipe 23, and the inner diameter r5 of the pipe 24 are the same. １ , C ２ , C ３ , C ４ , C ５ , 23, and 24 have a constant cross-sectional area, which makes it easy to analyze the flow of the slurry D1 flowing through the pipeline. However, the present invention is not limited to the above example, and the inner diameter of the circulation pipeline Po, i.e., the inner diameter r1 of the pipe 22, the inner diameter r2 of the straight pipe portions Po1, Po2, Po3, Po4, Po5, and Po6, the inner diameter r3 of the curved pipe portion C １ , C ２ , C ３ , C ４ , C ５ The inner diameter r3 of the pipe 21, the inner diameter r4 of the pipe 23, and the inner diameter r5 of the pipe 24 may be different from one another. In this case, the flow analysis should be performed taking into account the different inner diameters.

[0047] The pipe 23 through which the slurry D1 discharged from the bent portion Pp flows is connected to a pipeline connected to a slurry discharge pump 31. This pipeline draws out the slurry D1 from the pipe 23 and collects it to become a product. A flow indication controller (FIC) is installed near the slurry discharge pump 31. ４ is provided to maintain or adjust the flow rate of the slurry D1 extracted to the outside of the crystallization system 10A. The slurry discharge pump 31 is a slurry discharge pump that has the function of adjusting the flow rate, similar to the circulation pump 30. However, the slurry discharge pump 31 is not necessarily limited to a slurry discharge pump as long as it has the function of extracting the slurry D1 from the pipe 23, and for example, an impeller whose rotation speed can be controlled may be provided in the pipe. The pressure of the slurry D1 in the pipe 23 immediately after the slurry D1 is extracted to the outside is measured using a pressure indicator PI as needed. ２ Monitor with.

[0048] In the crystallization system 10A, at least a portion of the bent portion Pp is located within the temperature control tank 13. The temperature control tank 13 is a component that maintains a unidirectional flow of a refrigerant CW, such as cold water, within the temperature control tank 13 using a pump (not shown) or the like. When at least a portion of the bent portion Pp is located within the temperature control tank 13, the refrigerant collides with the straight pipe portions Po1, Po2, Po3, Po4, Po5, and Po6 of the bent portion Pp. In this case, heat exchange occurs between the slurry D1 flowing through the straight pipe portions Po1, Po2, Po3, Po4, Po5, and Po6 of the bent portion Pp and the refrigerant CW via the components that make up the straight pipe portions Po1, Po2, Po3, Po4, Po5, and Po6. This allows the slurry D1 to be cooled or heated. 1, the straight pipe sections Po1, Po2, Po3, Po4, Po5, and Po6 are arranged substantially perpendicular to the flow direction of the refrigerant CW, but the straight pipe sections Po1, Po2, Po3, Po4, Po5, and Po6 do not necessarily have to be arranged substantially perpendicular to the flow direction of the refrigerant CW, and may be arranged at an angle other than perpendicular. Furthermore, heat exchange with the refrigerant CW may occur in the curved pipe section C of the bent section Pp, or heat exchange with the refrigerant CW may occur in both the straight pipe section of the bent section Pp and the curved pipe section C.

[0049] Here, the temperature control capability for the slurry D1 can be adjusted by adjusting the length of the straight pipe sections Po1, Po2, Po3, Po4, Po5, and Po6 or the number of the straight pipe sections Po1, Po2, Po3, Po4, Po5, and Po6 in the bent section Pp. For example, if a heat quantity Q1 is transferred from a slurry D1 having a heat quantity Q flowing through the straight pipe section Po1 to a refrigerant CW by heat exchange, a heat quantity Q2 is transferred from a slurry D1 having a heat quantity (Q-Q1) flowing through the straight pipe section Po2 to the refrigerant CW by heat exchange. Furthermore, if a heat quantity Q3 is transferred from a slurry D1 having a heat quantity (Q-(Q1+Q2)) flowing through the straight pipe section Po3 to the refrigerant CW by heat exchange, the heat quantity of the slurry D1 flowing through the straight pipe section Po4 becomes (Q-(Q1+Q2+Q3)). By repeating this process a desired number of times, the amount of heat in the slurry D1 can be reduced, and the slurry D1 can be cooled by a desired amount. The same applies when heating the slurry D1.

[0050] According to the crystallization system 10A equipped with the circulation pipeline Po having such a bent portion Pp, the particle-containing slurry D1 produced in the crystallizer 4 can be easily and completely mixed uniformly by controlling the flow rate of the circulation pump 30. Furthermore, by adjusting the pipeline length of the bent portion Pp, the particle-containing slurry D1 produced in the crystallizer 4 can be retained for a desired time without requiring a retention tank. Therefore, the retention time of the slurry D1 in the bent portion Pp can be adjusted without performing the complex flow analysis of the slurry D1 that would be required if a retention tank were used. Note that a retention tank (not shown) may be added to the crystallization system 10A.

[0051] Furthermore, according to such a crystallization system 10A, the slurry D1 can be cooled or heated by the desired amount by adjusting the pipe length of the bent section Pp where heat exchange with the refrigerant CW takes place, i.e., the pipe length or number of the straight pipe sections Po1, Po2, Po3, Po4, Po5, and Po6.

[0052] Next, the agitator Wc of the crystallization system 10A will be described in detail. The agitator Wc includes a cylindrical portion 2, a disk-shaped disk portion 8 whose outer periphery is fixed to the inner circumferential surface 2i of the cylindrical portion 2, and a second disk portion 15 whose outer periphery is fixed to the inner circumferential surface 2i of the upper end of the cylindrical portion 2. The disk portion 8 is provided at a position approximately halfway through the height of the cylindrical portion 2, but this is not limited to this example and may be provided below or above approximately halfway through the height of the cylindrical portion 2. A rotating shaft 3 is fixed to the center of the disk portion 8 in a planar view. The second disk portion 15 is a disk-shaped member provided above the disk portion 8 and has a hole in its center in a planar view through which the rotating shaft 3 passes. Except for the hole through which the rotating shaft 3 passes, there are no other holes passing through the second disk portion 15 in the direction of the central axis O1. Therefore, the first reaction liquid L1, the second reaction liquid L2, and the mixture thereof do not enter the inside of the second disk portion 15. The hollow interior of the rotating shaft 3 is made into a pipe P1. A plurality of pipes P2 extend radially from the center toward the outer edge inside the disk portion 8. The pipe P1 of the rotating shaft 3 and the pipe P2 of the disk portion 8 are connected to each other. The rotating shaft 3 of the stirring blade Wc is connected to the main raw material S provided outside the crystallizer 4. Ｍ The second reaction liquid L2 is supplied from a tank (not shown) that stores the second reaction liquid L2. The second reaction liquid L2 is supplied to a hollow pipe P1 of the rotating shaft 3 via a rotary joint R, and then supplied to a pipe P2 of the disk unit 8. The tip of the pipe P2, which is on the outer side in the radial direction of the reaction tank 1, opens downward and serves as a liquid supply section (second liquid supply section) 5b from which the second reaction liquid L2 is discharged. Therefore, the disk unit 8 is provided with a plurality of liquid supply sections 5b spaced apart in the circumferential direction of the disk unit. The number of liquid supply sections 5b is, for example, eight. The number of liquid supply sections 5b is not limited, but it is desirable to provide them symmetrically with respect to the central axis O1.

[0053] In this embodiment, the distance between the inner circumferential surface 2i of the cylindrical portion 2 of the impeller Wc and the center of the liquid supply portion 5b is 2 mm or less. Furthermore, as shown in FIG. 2, if the distance (clearance) between the outer circumferential surface 2o of the cylindrical portion 2 of the impeller Wc and the inner circumferential surface 1i of the reaction vessel 1 is L3, and the height along the central axis O1 of the impeller Wc (cylindrical portion 2) is He, the ratio of He to L3, He / L3, is preferably 10 or greater. Furthermore, it is more preferable that He / L3 is 25 or greater. Therefore, even if a device of a different size is used, a similar device can be manufactured based on this ratio. The impeller Wc rotates at a peripheral speed of 5 m / s or greater and 50 m / s or less. Note that the He / L3 ratio may differ from the above ratio depending on the purpose. For example, if it is desired to suppress crystal crushing, the ratio may be lowered from the above value.

[0054] The cylindrical portion 2 of the agitator Wc has a plurality of holes h penetrating radially through the cylindrical portion 2 below the disk portion 8. These holes h allow the first reaction liquid L1, the second reaction liquid L2, or a mixture thereof to flow through them. Therefore, the first reaction liquid L1, the second reaction liquid L2, or a mixture thereof can move from the inside to the outside of the agitator Wc, or from the outside to the inside of the agitator Wc, through the plurality of holes h. In this way, when the plurality of holes h penetrating radially through the cylindrical portion 2 are provided below the disk portion 8, the agitator Wc can be rotated with less power than when the plurality of holes h are provided both above and below the disk portion 8. Such a cylindrical portion 2 may be formed by processing a cylindrical portion 2 that has holes h evenly distributed throughout its height before processing, and then closing the holes h above the disk portion 8 to form a cylindrical portion 2 that has holes h only below the disk portion 8. Alternatively, the cylindrical portion 2 may be formed such that the holes h are formed only below the disk portion 8 and no holes h are formed above the disk portion 8 .

[0055] In a crystallizer 4 equipped with such an agitator Wc, a predetermined amount of first reaction liquid L1 is supplied to the reaction tank 1 through the inlet 5a. The amount of first reaction liquid L1 supplied may be enough to fill the reaction tank 1 (full state), or may be enough to press the first reaction liquid L1 against the inner circumferential surface 1i of the reaction tank 1 due to centrifugal force generated by the first reaction liquid L1 as the agitator W rotates and the first reaction liquid L1 undergoes circular motion about the central axis O1 of the reaction tank 1, forming a liquid film of the first reaction liquid L1 on the inner circumferential surface 1i of the reaction tank 1. The following description will be given assuming that the first reaction liquid L1 is supplied to the extent that the reaction tank 1 is full. Alternatively, the reaction may be carried out in the reaction tank 1 after the first reaction liquid L1 is supplied to an extent that the first reaction liquid L1 reaches the above-mentioned liquid-filled state or liquid film formation state and then the supply of the first reaction liquid L1 is stopped (batch method described later), or the reaction may be carried out continuously in the reaction tank 1 while maintaining the flow rate of the first reaction liquid L1 at an extent that the above-mentioned liquid-filled state or liquid film formation state is achieved (continuous method described later). For example, by providing an aperture adjustment valve (not shown) at the outlet 6 and adjusting the aperture of this aperture adjustment valve, the reaction tank 1 can be selected to be in either a liquid-filled state or a liquid film state in which a liquid film is formed.

[0056] With the reaction vessel 1 filled with the first reaction liquid L1, the agitator Wc is rotated and the second reaction liquid L2 is discharged from the liquid supply section 5b along the inner circumferential surface 2i of the cylindrical portion 2 of the agitator Wc, thereby supplying the second reaction liquid L2 into the reaction vessel 1. In this manner, the second reaction liquid L2 discharged from the liquid supply section 5b along the inner circumferential surface 2i of the cylindrical portion 2 of the agitator Wc comes into contact with the first reaction liquid L1 that is rotating in association with the rotation of the agitator Wc near the inner circumferential surface 2i of the cylindrical portion 2 of the agitator Wc in the reaction vessel 1 filled with the first reaction liquid L1. This contact between the first reaction liquid L1 and the second reaction liquid L2 causes a reaction to occur, producing particles.

[0057] In this case, the second reaction liquid L2 is supplied to the first reaction liquid L1 from the liquid supply section 5b of the stirring blade Wc, which is rotating at a peripheral speed of 5 m / s or more and 50 m / s or less, so that the second reaction liquid L2 can be uniformly mixed with the first reaction liquid L1.

[0058] Here, due to the centrifugal force generated in the mixture of the first reaction liquid L1 rotating with the rotation of the agitator impeller Wc and the second reaction liquid L2 discharged from the liquid supply portion 5b of the agitator impeller Wc rotating at a peripheral speed of 5 m / s to 50 m / s, the first reaction liquid L1, the second reaction liquid L2, and the mixture (hereinafter sometimes collectively referred to as the mixture) move radially outward from the cylindrical portion 2 of the agitator impeller Wc, pass through multiple holes h provided in the cylindrical portion 2 of the agitator impeller Wc, collide with the inner circumferential surface 1i of the reaction vessel 1, and then move vertically along the inner circumferential surface 1i of the reaction vessel 1. The mixture that moves mainly downward is attracted by the radially outward flow caused by the centrifugal force generated by the rotation of the agitator impeller Wc, passes through multiple holes h provided in the cylindrical portion 2 of the agitator impeller Wc, collide with the inner circumferential surface 1i of the reaction vessel 1, and then moves vertically along the inner circumferential surface 1i of the reaction vessel 1, thereby creating convection. Here, when the mixed liquid passes through the multiple holes h, the mixed liquid is accelerated radially outward due to the effect of the throttle flow path, so the radially outward flow velocity of the mixed liquid is highest near the multiple holes h. Furthermore, a circumferential shear force is applied to the mixed liquid present between the outer peripheral surface 2o and inner peripheral surface 2i of the cylindrical portion 2 of the agitator impeller Wc, which rotates at a peripheral speed of 5 m / s to 50 m / s, and the fixed inner peripheral surface 1i of the reaction vessel 1. The shear force applied to the mixed liquid is greater the closer it is to the inner peripheral surface 2i and outer peripheral surface 2o of the cylindrical portion 2 of the agitator impeller Wc. The shear force applied to the mixed liquid is a major factor in determining the particle size and uniformity of the resulting particles. In particular, the greater the applied shear force, the more fine particles can be obtained.

[0059] In the crystallization apparatus 4 of this embodiment, the liquid supply section 5b is provided on the outer edge of the disk section 8. Specifically, as described above, the distance between the inner circumferential surface 2i of the cylindrical section 2 of the agitator Wc and the center of the liquid supply section 5b is 2 mm or less. Therefore, at the reaction initiation point where the second reaction liquid L2 discharged from the liquid supply section 5b along the inner circumferential surface 2i of the cylindrical section 2 of the agitator Wc first comes into contact with the first reaction liquid L1 rotating in association with the rotation of the agitator Wc near the inner circumferential surface 2i of the cylindrical section 2 of the agitator Wc, maximum shear force is applied in addition to the radially outward flow due to centrifugal force and the effect of the throttle flow channel. Therefore, the region with the greatest applied shear force can be used as the reaction initiation point. Specifically, the reaction initiation point can be formed in a region close to the inner circumferential surface 2i and outer circumferential surface 2o of the cylindrical section 2 of the agitator Wc, for example, within 2 mm. Here, the mixed liquid can move from the inner circumferential side to the outer circumferential side of the cylindrical section 2 through the multiple holes h. Therefore, the shear force promotes the mixing of the first reaction liquid L1 and the second reaction liquid L2 at the reaction initiation point. Therefore, more uniform mixing of the first reaction liquid L1 and the second reaction liquid L2 is initiated from the reaction initiation point, and the mixing and reaction occur in the reaction field, where the reaction occurs along the flow of the mixed liquid, thereby producing fine particles with uniform diameters. Here, the reaction initiation point refers to the area where the reaction begins, and the reaction field refers to the entire field where the reaction occurs. Therefore, the reaction initiation point is included in the reaction field. A baffle (baffle plate) 7 shown in Figure 2 may be installed on the inner surface of the reaction vessel 1, corresponding to the upper part of the stirring blade Wc. When the reaction vessel 1 is filled with liquid, the baffle 7 has the effect of suppressing the generation of vortices and promoting the mixing of the mixed liquid. On the other hand, when the reaction vessel 1 is not filled with liquid and a liquid film of the mixed liquid is formed, the baffle 7 is not necessary. The baffle 7 is not a required component and may be omitted. For example, if a mechanical seal (not shown) is provided at the location in the reaction vessel 1 where the rotating shaft 3 is inserted, and the reaction vessel 1 is completely filled with liquid with no gas phase, the generation of vortices is suppressed, and therefore the baffle 7 is not required. If the baffle 7 is not provided, the flow path resistance is reduced, and the power of the prime mover M can be reduced.

[0060] It should be noted that the same effect as in the case of the liquid-filled state can be obtained even in a state where a liquid film is formed, rather than in a liquid-filled state.

[0061] According to the crystallization system 10A including such a crystallizer 4, it is possible to individually adjust the shear force, the circulation amount of the first reaction liquid L1, and the residence time of the slurry, which affect the particle quality such as particle size, particle size distribution, and sphericity of the reaction product in the crystallizer 4, and thus further improve the controllability of particle quality.

[0062] The crystallization apparatus 4 of this crystallization system 10A is further provided with a control unit CON capable of controlling the rotation speed of the prime mover M. Therefore, by controlling the rotation speed of the prime mover M with the control unit CON, the rotation speed (circumferential speed) of the agitator impeller Wc can be controlled. The control unit CON is a computer that controls the rotation speed of the prime mover M based on operations by an operator of the crystallization system 10A. That is, the control unit CON may be a known computer including a CPU, RAM, ROM, etc., capable of performing the above-described control. The details of the control by the control unit CON may be defined by software that can be changed or updated by the user. As shown in FIGS. 1 and 2 , the control unit CON is electrically or electronically connected to the prime mover M. The control unit CON may also include a rotation speed sensor that measures the rotation speed of the agitator impeller Wc (rotating shaft 3), and the control unit CON may control the rotation speed of the prime mover M so that the rotation speed signal received from the rotation speed sensor corresponds to the desired peripheral speed. For example, if the prime mover M is a motor, the control unit CON may control the rotation speed of the motor by controlling the drive voltage of the motor. When the prime mover M is an engine, the control unit CON may control the rotation speed of the engine by controlling the amount of fuel supplied to the engine.

[0063] Using such a crystallization system 10A, the residence time of the crystals in the crystallization system 10A including the reaction tank 1 and the pH of the mixture of the first reaction liquid L1 and the second reaction liquid L2 in the reaction tank 1 were fixed or maintained at constant conditions, and the average particle diameter d50 of the microparticles obtained when the peripheral speed of the stirring blade Wc was changed was measured. As a result, the average particle diameter d50 of the microparticles obtained when the peripheral speed of the stirring blade Wc was 20 m / s was 3.79 μm (measurement point a). The average particle diameter d50 of the microparticles obtained when the peripheral speed of the stirring blade Wc was 40 m / s was 1.71 μm (measurement point b). The average particle diameter d50 of the microparticles obtained when the peripheral speed of the stirring blade Wc was 50 m / s was 1.32 μm (measurement point c).

[0064] The graph obtained by interpolating the obtained measurement points a, b, and c using a known method is shown in Figure 3. It was confirmed from Figure 3 that as the peripheral speed of the stirring blade Wc increases, fine particles with a smaller average particle diameter d50 are obtained. It was also confirmed from Figure 3 that at a peripheral speed of approximately 25 m / s or more, the obtained average particle diameter d50 is 3 μm or less. Here, a peripheral speed of approximately 25 m / s or more refers to a peripheral speed between 23 m / s and 25 m / s or more, at which the average particle diameter d50 is 3 μm or less.

[0065] The results shown in Figure 3 confirm that using the crystallization system 10A and a microparticle manufacturing method with a peripheral speed of the stirring blade Wc of approximately 25 m / s or greater can produce microparticles with an average particle diameter d50 of 3 μm or less. The microparticles obtained in Figure 3 are metal compounds containing nickel, cobalt, and manganese. More specifically, they are ternary metal hydroxides composed of nickel, cobalt, and manganese. In these microparticles, the nickel content is 90% or greater. A material ratio of 90% or greater here refers to a ratio of nickel to the total material amount of nickel, cobalt, and manganese of 100. Therefore, it was confirmed that, despite a high nickel content, very small microparticles with an average particle diameter d50 of 3 μm or less can be obtained. The microparticles are not necessarily limited to ternary metal hydroxides composed of nickel, cobalt, and manganese, but may also be metal compound microparticles composed of nickel, cobalt, and aluminum.

[0066] The results shown in FIG. 3 were obtained when the crystallization system 10A was operated in a continuous mode. The continuous mode is when the main raw material S Ｍ and auxiliary material S Ａ and S Ｂ is continuously supplied to the crystallization system 10A, and the slurry D1 containing the generated fine particles is continuously discharged to the outside from the crystallization system 10A. Since the material ratio of nickel in the ternary metal hydroxide composed of nickel, cobalt, and manganese produced in the crystallization system 10A is 90% or more, the material ratio of nickel in the metal-based raw materials fed into the crystallization system 10A is also 90% or more. In addition to continuous operation, there is also a batch operation. This is because the main raw material S is continuously supplied to the crystallization system 10A during operation. Ｍ and auxiliary material S Ａ and S Ｂ Before starting the operation of the crystallization system 10A, a predetermined amount of the main raw material S is supplied without supplying the main raw material S. Ｍ and auxiliary material S Ａ and S Ｂ to the crystallization system 10A, the crystallization system 10A is operated, and the operation of the crystallization system 10A is stopped, and then the slurry D1 containing the generated fine particles is discharged to the outside.

[0067] Figure 4 is an electron microscope photograph of microparticles obtained by operating the crystallization system 10A in such a continuous manner so that the peripheral speed of the impeller Wc was approximately 25 m / s or more. It can be seen that the sphericity of the particles was high, averaging 0.85 or more. The average particle diameter d50 in this case was 1.32 μm. Figure 5 is an electron microscope photograph of microparticles obtained using conventional technology that does not use impellers shaped like the impeller Wc of the crystallization system 10A. It can be seen that the sphericity of the microparticles is clearly lower than that of the microparticles in Figure 4. The average particle diameter d50 in this case was 1.37 μm.

[0068] Figure 6 is an electron microscope photograph of microparticles obtained by operating crystallization system 10C or crystallization system 10D (described below) in a batch mode. Similar to the microparticles obtained in the continuous mode shown in Figure 4, the batch mode operation also yields microparticles with a high degree of sphericity, with particle sphericity of 0.9 or more on average. Furthermore, compared to the continuous mode, the uniformity of the particle size distribution is significantly improved, achieving a span of (d90-d10) / d50 = 0.7 or less. The average particle diameter d50 in this case was 1.40 μm.

[0069] By using the crystallization system 10A including the crystallizer 4 equipped with the control unit CON capable of controlling the circumferential speed of the agitator blades Wc, it is possible to produce ternary metal hydroxide microparticles composed of nickel, cobalt, and manganese, which have high sphericity, a high nickel content of 90% or more by mass ratio, and a small average particle diameter d50 of 3 μm or less. Furthermore, the average particle diameter d50 of the resulting metal compound microparticles can be controlled by primarily adjusting the circumferential speed of the agitator blades Wc under the control of the control unit CON. In other words, by providing a control unit CON capable of controlling the circumferential speed of the agitator blades Wc and allowing for independent adjustment of shear force and circulating flow, stirring specialized for the transmission of shear force is possible in the reaction vessel 1. In other words, by adjusting the circumferential speed of the agitator blades Wc, the shear force applied to the mixed solution in the reaction vessel 1 is adjusted, and by adjusting the rotation speed of the circulation pump 30 (see FIG. 1), the circulating flow is adjusted. The major benefit of this improved mechanism is that particle size can be controlled primarily by adjusting the circumferential speed of the agitator blades Wc. Unlike conventional particle size control that relies on adjusting the residence time and pH value, this method allows particle size to be controlled primarily by adjusting the peripheral speed of the stirring blades Wc while maintaining the residence time and pH value constant under conditions that do not degrade product quality, dramatically improving particle size controllability. This improved functionality makes it possible to control particle size while maintaining the residence time and pH value that do not cause deterioration of particle shape, and to obtain a high-quality metal hydroxide with a high nickel content, a small average particle size d50, and high sphericity.

[0070] 7 is a schematic diagram showing a crystallization system 10B according to a first modification of the first embodiment of the present invention. In the following description, only the differences from the crystallization system 10A according to the first embodiment will be described.

[0071] The crystallization system 10B differs from the crystallization system 10A in that the shape of the agitator blade Wd is different from that of the agitator blade We of the crystallization system 10A, and in that the bent portion Pp is not provided inside the temperature adjustment tank 13.

[0072] As shown in FIG. 7, the agitator Wd differs from the agitator Wc in that the disk portion 8 is provided at the upper end of the cylindrical portion 2. Furthermore, the height of the cylindrical portion 2 is approximately half that of the agitator Wc. Using a crystallizer 4d equipped with such an agitator Wd can achieve the same effects as the crystallizer 4 equipped with the agitator Wc. Furthermore, because the cylindrical portion 2 is not provided above the disk portion 8, the agitator Wd can be made lighter than the agitator Wc. Furthermore, because the agitator Wd can have a simple structure, it can be operated with less power than the agitator Wc, which is expected to improve energy efficiency and simplify the manufacture of the crystallizer 4d. Furthermore, because the height of the cylindrical portion 2 is kept short, the crystallizer 4d can be made more compact.

[0073] The crystallization system 10B according to the first modification, which includes the crystallizer 4d, can produce fine particles of a ternary metal hydroxide composed of nickel, cobalt, and manganese, with a high degree of sphericity, a high nickel content of 90% or more by mass, and a small average particle diameter d50 of 3 μm or less, just as in the case of the crystallization system 10A. The temperature control tank 13 used in the crystallization system 10A may be installed in the crystallization system 10B. In this case, the slurry D1 can be cooled or heated by a desired amount, just as in the crystallization system 10A.

[0074] 8 is a schematic diagram showing a crystallization system 10C according to a second modification of the first embodiment of the present invention. In the following description, only the differences from the crystallization system 10A according to the first embodiment will be described.

[0075] The crystallization system 10C differs from the crystallization system 10A in that a retention tank 10 is provided instead of the bent portion Pp of the crystallization system 10A.

[0076] While the crystallization systems 10A and 10B are configured for continuous operation, the crystallization system 10C is configured for batch operation. In this case, a larger device capacity can be secured than when the bent portion Pp is used. Therefore, in a batch operation in which the system forming the crystallization system 10C is closed to the outside during operation, a larger number of microparticles can be produced in a single run. This allows for efficient microparticle production. Even when operated in a batch mode, such crystallization system 10C can produce microparticles with high sphericity, a high nickel content of 90% or more in terms of substance mass, and an average particle diameter d50 of 3 μm or less, as shown in FIG. 6 . Furthermore, when microparticles are produced in a batch mode, the uniformity of the particle size distribution is significantly improved compared to a continuous mode, achieving a span: (d90-d10) / d50 = 0.7 or less. The retention tank 10 of the crystallization system 10C may be equipped with an agitator (not shown). For example, a known screw-type agitator may be used. In this case, the fluidity in the retention tank 10 can be further improved, and the dispersibility when raw materials and additives are added to the retention tank 10 can also be improved.

[0077] 9 is a schematic diagram showing a crystallization system 10D according to a third modification of the first embodiment of the present invention. In the following description, only the differences from the crystallization system 10C according to the second modification of the first embodiment will be described.

[0078] The crystallization system 10D differs from the crystallization system 10C in that a concentrator 11 is connected to the retention tank 10 of the crystallization system 10C.

[0079] By combining the crystallization system 10D with a concentrator 11, the slurry concentration within the system can be increased, improving production volume per unit volume. In principle, the slurry has fluidity and can be increased to a concentration that allows it to be pumped. A filter, centrifuge, thickener, or the like can be used as the concentrator 11. Using this crystallization system 10D, microparticles with high sphericity, a high nickel content of 90% or more by substance weight, and an average particle diameter d50 of 3 μm or less can be produced, as shown in FIG. 6 . The retention tank 10 of the crystallization system 10D may be equipped with an agitator (not shown). For example, a known screw-type agitator may be used. This further improves the fluidity of the retention tank 10 and improves the dispersibility of raw materials and additives added to the retention tank 10.

[0080] Here, the advantages of using the impeller Wc or the impeller Wd will be explained from a different perspective. Compared to using a flat disk turbine as disclosed in Patent Document 3, when operated with the same power, an impeller Wc or an impeller Wd with a blade diameter 1.25 times that of a flat disk turbine can be operated at a peripheral speed 3.3 times that of a flat disk turbine. Therefore, when using the impeller Wc or the impeller Wd, a greater shear force can be applied to the micro-reaction field of the metal hydroxide than with conventional technology. This is thought to be because the impeller Wc or the impeller Wd experiences less resistance from the water when rotated compared to a flat disk turbine. Therefore, the impeller Wc or the impeller Wd can be rotated at a higher speed, which is thought to be able to apply a greater shear force to the micro-reaction field of the metal hydroxide.

[0081] The above has described in detail an embodiment of the present invention and its modified examples with reference to the drawings, but the specific configurations are not limited to the embodiment and its modified examples, and also include designs and the like within the scope of the gist of the present invention, and combinations of the embodiment and modified examples.

[0082] It is possible to provide a method for producing a metal compound and fine particles of the metal compound that have a high nickel content and are microparticulate, and that can achieve high capacity and high output enough to be used as a positive electrode material for next-generation batteries.

[0083] 1 Reaction tank 2 Cylindrical part 3 Rotating shaft 4, 4d Crystallizer 5a Inlet (first liquid supply part) 5b Liquid supply part (second liquid supply part) 6 Discharge port 8 Disk part h Holes 10A, 10B, 10C, 10D Crystallization system 22, 23, 24 Piping 30 Circulation pump 31 Second circulation pump Po Circulation pipe Pp Bent part Po1, Po2, Po3, Po4, Po5, Po6 Straight pipe part C, C １ , C ２ , C ３ , C ４ , C ５ Curved pipe Wc, Wd Mixing blade

Claims

1. A method for producing fine particles of a metal compound, using a crystallization apparatus comprising: an agitator blade having a plurality of holes passing through it in the radial direction and rotatable around a central axis; a cylindrical reaction tank with a bottom that can concentrically accommodate the agitator blade inside; a first liquid supply section that is provided in the reaction tank and can supply a first reaction liquid into the reaction tank; and a second liquid supply section that is provided in the agitator blade and can supply a second reaction liquid into the reaction tank; the method comprises supplying the first reaction liquid from the first liquid supply section and supplying the second reaction liquid from the second liquid supply section, and rotating the agitator blade at a peripheral speed of approximately 25 m / s or more, thereby reacting the first reaction liquid with the second reaction liquid and precipitating fine particles of the metal compound.

2. The method for producing fine particles of a metal compound described in claim 1, wherein the stirring blade of the crystallization device comprises: a cylindrical portion; a disk-shaped disk portion whose outer edge is fixed to the inner surface of the cylindrical portion; and a rotating shaft extending upward from the center of the disk portion along the central axis in a plan view, wherein the second reaction liquid can flow through the interior of the disk portion and the rotating shaft, and the second liquid supply portion is provided on the outer edge of the disk portion.

3. The method for producing fine particles of a metal compound according to claim 2, wherein the second liquid supply section of the crystallizer opens downward.

4. A method for producing fine particles of a metal compound as described in claim 3, wherein the cylindrical portion of the crystallization device above the disk portion has a plurality of holes penetrating in the radial direction blocked, and a second disk-shaped portion having an outer edge fixed to the inner surface of the cylindrical portion is provided at the upper end of the cylindrical portion.

5. The method for producing fine particles of a metal compound according to claim 3, wherein the disk portion of the crystallizer is provided at the upper end of the cylindrical portion.

6. A method for producing fine particles of a metal compound described in any one of claims 2 to 5, wherein, when the clearance between the outer surface of the cylindrical portion of the crystallization device and the inner surface of the reaction tank is L3 and the height of the cylindrical portion is He, He / L3 is 10 or more.

7. The method for producing fine particles of a metal compound according to any one of claims 1 to 5, wherein a plurality of second liquid supply sections are provided in the crystallization device.

8. A method for producing fine particles of a metal compound according to any one of claims 1 to 5, comprising: the crystallization device; a circulation pipeline that flows a slurry containing the fine particles discharged from an outlet of the crystallization device and circulates the slurry from the first liquid supply section of the crystallization device into the crystallization device; and a circulation pump that circulates the slurry between the crystallization device and the circulation pipeline, wherein the circulation pipeline uses a crystallization system having a serpentine bend, and nickel accounts for 90% or more in terms of substance amount of the metal-based raw materials fed into the crystallization system.

9. The method for producing fine particles of a metal compound according to claim 8, wherein the pH of the mixture of the first reaction liquid and the second reaction liquid and the residence time of the fine particles in the crystallization system are maintained constant.

10. A method for producing fine particles of a metal compound as described in claim 8, wherein the average particle diameter d50 of the fine particles is adjusted by adjusting the peripheral speed of the stirring blade.

11. Fine particles of a metal compound produced by the production method described in any one of claims 1 to 5, having an average particle diameter d50 of 3 μm or less and a nickel mass ratio of 90% or more.

12. The fine particles of the metal compound according to claim 11, wherein the fine particles are fine particles of a ternary metal hydroxide composed of nickel, cobalt, and manganese.

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