Method for obtaining representative particle size using a turbidimeter in a crystallizer and representative particle size obtaining system

Abstract

An object of the present invention is to provide a method for obtaining the particle size of particles produced in a crystallizer during a crystallization process by using a single correlation equation from turbidity, the concentration of the produced particles, and the supply amount of raw material. [Solution] A correlation equation for these variables is created in advance from basic data, such as the representative particle size of the produced particles obtained by a particle size distribution measuring device, the turbidity of the dispersion of the produced particles, the concentration of the produced particles in the dispersion of the produced particles, and the supply amount of metal derived from the metal salt. In the crystallization process, the representative particle size of the produced particles is obtained using the correlation equation from the turbidity, the concentration of the produced particles, and the supply amount of metal derived from the metal salt obtained by measuring the dispersion of the produced particles.

Description

[Technical field]

[0001] The present invention relates to a method for acquiring a representative particle size of a crystallized substance produced during crystallization and a representative particle size measuring system. [Background technology]

[0002] Crystallization is a process for precipitating crystals from a liquid phase. Crystallization occurs when a liquid is placed in a supersaturated state, which can be achieved by cooling, evaporation, reaction, or pressure. For example, when a reaction creates a supersaturated state and product particles are formed, this is called reactive crystallization. In normal crystallization operations, it is necessary to produce crystals with a certain representative particle size and particle size distribution. Applications of crystallization include the production of lithium ion battery cathode precursors, various inorganic materials, cosmetic materials, etc., and in these applications, the representative particle size and particle size distribution are important physical properties for the performance of the materials obtained by crystallization. Therefore, obtaining information on the particle size of the generated particles is important for ensuring their performance.

[0003] Methods for measuring the particle size of particles on the order of microns and submicrons include dynamic light scattering, laser diffraction / scattering, centrifugal sedimentation, and image analysis, but all of these require expensive measuring equipment or require a long measurement time.

[0004] Meanwhile, a method that enables efficient particle size measurement at low cost has been proposed (Patent Document 1). The disclosed method includes a step of mixing a predetermined amount of suspended matter having a known average particle size with water for each average particle size to prepare suspensions for each average particle size, a step of measuring the turbidity of the suspensions for each average particle size for each average particle size to identify the correspondence between the average particle size and the turbidity, and a step of measuring the turbidity of a target suspension containing suspended matter to be measured for particle size, and identifying the average particle size of the suspended matter contained in the target suspension by comparing the measured turbidity with the correspondence. Specifically, a graph of turbidity and particle size is created for each amount (concentration) of suspended solids, and the turbidity of the target suspension is compared to the turbidity-average particle size relationship graph. Here, a graph is created for each concentration of suspended solids, and the concentration of the target suspension needs to be adjusted to the concentration of suspended solids in the graph created above. Patent Document 1 also discloses that a graph is created for each color and concentration of suspended matter, which are kaolin (white), slate (gray), and basic volcanic rocks (brown), and the turbidity of the target suspension is compared with the corresponding color graph among the turbidity-average particle size relationship graphs to identify the average particle size of suspended matter contained in the target suspension having a white, gray, or brown color tone. In this case, too, it is necessary to match the concentration of the target suspension to the concentration of suspended matter in the above-created graph. Furthermore, it is necessary to select a turbidity-average particle size relationship graph for each color of suspended matter. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication 2008-191057 Summary of the Invention [Problem to be solved by the invention]

[0006] The prior art utilizes a graph of the turbidity-average particle size relationship prepared by the concentration of the suspended solids, or a graph of the turbidity-average particle size relationship prepared by the concentration of the suspended solids and by three different colors. Therefore, it is necessary to match the concentration of the target suspension to the concentration of the suspended matter in the created graph, and if the suspended matter is colored, it is necessary to use the turbidity-average particle size relationship graph of that color. It was difficult to apply this method to a concentration crystallization process in which the average particle size varies depending on the turbidity of the suspension, the slurry concentration, and the supply amount of the raw material.

[0007] An object of the present invention is to provide a method for obtaining the particle size of particles produced in a crystallizer during a crystallization process by using one correlation equation from turbidity, the concentration of the produced particles, the supply amount of raw materials, etc. Another object of the present invention is to provide a method for obtaining the particle size of particles produced in a crystallizer by using one correlation equation from turbidity, the concentration of the produced particles, and the supply amount of raw materials when particles are produced by a reaction of raw materials. [Means for solving the problem]

[0008] The aspects of the means for solving the above problems are as follows.

[0009] (First aspect) A method for obtaining a representative particle size of particles produced in a crystallization step in which aqueous solutions each containing a plurality of types of metal salts are supplied to a crystallizer and brought into contact with each other to produce particles, comprising the steps of: a step of acquiring basic data including a representative particle diameter of the generated particles acquired by a particle size distribution measuring device, a turbidity of a dispersion of the generated particles, a concentration of the generated particles in the dispersion of the generated particles, and a supply amount of metal derived from the metal salt; creating a correlation equation that expresses a relationship between a representative particle diameter of the generated particles, a turbidity of a dispersion of the generated particles, a concentration of the generated particles in the dispersion of the generated particles, and a supply amount of one or more metals selected from the metals, the representative particle diameter being obtained in the step of acquiring basic data; In the crystallization step, a step of acquiring the turbidity of the dispersion of the generated particles, the concentration of the generated particles, and the supply amount of metal derived from the multiple types of metal salts; obtaining a representative particle size of the generated particles by the correlation equation based on the respective values ​​of the turbidity of the dispersion of the generated particles obtained in the crystallization step, the concentration of the generated particles, and the supply amount of one or more metals selected from the metals derived from the metal salt; A method for obtaining a representative particle size of particles produced in a crystallizer, comprising:

[0010] (Action and effect)

[0011] According to this method, there is no need for expensive equipment such as a particle size distribution measuring device, and the representative particle size of the produced particles can be easily and quickly obtained from the turbidity meter response value of the dispersion of the produced particles, the concentration of the produced particles in the dispersion of the produced particles, and the supply amount of metal derived from the metal salt.

[0012] (Second aspect) In the step of creating the correlation equation, The plurality of metal salts are three types, When the turbidity of the dispersion of the generated particles is X1 NTU, the concentration of the generated particles is X2 mass %, the supply amount of the metal is X3 moles, X4 moles, and X5 moles, and the representative particle diameter of the generated particles is Y μm, In the following formula expressing the relationship between Y and X1, X2, X3, X4, and X5, the correlation formula is determined by finding the respective coefficients a, b, c, d, and e by the least squares method. A method for obtaining a representative particle size of particles produced in the crystallizer according to the first embodiment.

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[0013] (Action and effect) By using the above correlation equation, the representative particle size of the produced particles can be obtained with high accuracy.

[0014] (Third aspect) In the step of creating the correlation equation, The plurality of metal salts are three types, The method for obtaining a representative particle size of the product particles in a crystallizer according to the second aspect, wherein the turbidity of the dispersion of the product particles is X1 NTU, the concentration of the product particles is X2 mass%, X3 is the number of moles of cobalt ions, X4 is the number of moles of manganese ions, and X5 is the number of moles of nickel ions.

[0015] (Action and effect) The molar ratio of cobalt ions to nickel ions and the molar ratio of manganese ions to nickel ions affect the properties of the generated particles. Since the properties of the generated particles affect the acquisition of particle size based on turbidity, by incorporating the molar ratio of cobalt ions to nickel ions and the molar ratio of manganese ions to nickel ions into the correlation equation, it becomes possible to acquire a more accurate representative particle size.

[0016] (Fourth aspect) A system for obtaining a representative particle size of particles produced in a crystallizer, the system comprising: a crystallizer that supplies aqueous solutions each containing a plurality of types of metal salts to the crystallizer and brings the aqueous solutions into contact with each other to produce particles, the system comprising: a turbidity acquisition unit that acquires the turbidity of a dispersion of generated particles in the crystallizer; a generated particle concentration acquisition unit that acquires a concentration of the generated particles in the generated particle dispersion; a metal supply amount acquisition unit that acquires a supply amount of a metal derived from the metal salt; a correlation equation creating unit that stores a correlation equation that represents a relationship between a representative particle diameter of the generated particles obtained by a particle size distribution measuring device, a turbidity of a dispersion of the generated particles, a concentration of the generated particles in the dispersion of the generated particles, and a supply amount of one or more metals selected from the metals derived from the metal salt; a representative particle diameter calculation unit which obtains a representative particle diameter of the produced particles by the correlation equation based on the respective numerical values ​​of the turbidity of the dispersion of the produced particles obtained by the turbidity acquisition unit, the concentration of the produced particles obtained by the produced particle concentration acquisition unit, and the supply amount of one or more metals selected from the metals derived from the metal salt obtained by the metal supply amount acquisition unit; A system for acquiring a representative particle size of particles produced in a crystallizer.

[0017] (Action and effect) A system can be obtained that does not require a particle size distribution measuring device, and that can easily and quickly obtain the representative particle size of generated particles by combining a relatively inexpensive device such as a turbidity meter.

[0018] (Fifth embodiment) The correlation equation creating unit is The plurality of metal salts are three types, When the turbidity of the dispersion of the generated particles is X1 NTU, the concentration of the generated particles is X2 mass%, the supply amount of the metal is X3 moles, X4 moles, and X5 moles, and the representative particle diameter of the generated particles is Y μm, In the following formula that expresses the relationship between Y and X1, X2, X3, X4, and X5, a correlation formula is created and stored by finding each of the coefficients a, b, c, d, and e using the least squares method. A system for acquiring a representative particle size of produced particles in a crystallizer according to the fourth embodiment.

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[0019] (Action and effect) By creating the correlation equation using the correlation equation creating section, a system can be obtained that can obtain the representative particle size of generated particles with high accuracy.

[0020] (Sixth embodiment) The system for acquiring a representative particle size of produced particles in a crystallizer according to the fifth aspect, wherein X3 is the number of moles of cobalt ions, X4 is the number of moles of manganese ions, and X5 is the number of moles of nickel ions.

[0021] (Action and effect) The molar ratio of cobalt ions to nickel ions and the molar ratio of manganese ions to nickel ions affect the properties of the generated particles. Since the properties of the generated particles affect the acquisition of particle size using turbidity, by incorporating the molar ratio of cobalt ions to nickel ions and the molar ratio of manganese ions to nickel ions into the correlation equation, it becomes possible to acquire a representative particle size with higher accuracy. Effect of the Invention

[0022] According to the present invention, in the crystallization process, it is possible to obtain the particle size of the particles produced in the crystallizer from the turbidity and the concentration of the produced particles by using one correlation equation. Also, when the particles are produced by the reaction of the raw materials, it is possible to obtain the particle size of the particles produced in the crystallizer from the turbidity, the concentration of the produced particles, and the supply amount of the raw materials by using one correlation equation. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram of an entire crystallizer. [Diagram 2] FIG. 1 is a schematic diagram of a reactor. [Diagram 3] 1 is a flow chart showing a representative particle size acquisition flow. [Figure 4] This is the system configuration. [Diagram 5] 1 is a graph showing typical particle diameter calculation values ​​and actual measurement values ​​according to a method of an embodiment. [Figure 6] 1 is a graph showing typical particle diameter calculation values ​​and actual measurement values ​​according to a method of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Next, an embodiment of the present invention will be described. An example of an apparatus and a method for obtaining the particle diameter of generated particles will be described.

[0025] (Crystallizer) A typical example of the crystallization apparatus according to the present invention is a reactive crystallization apparatus for obtaining product particles of metal particles. One specific example is intended for producing product particles using transition metals such as Ni, Co, Mn, etc. However, since the method of performing reactive crystallization is widely applicable, it may be intended for metals other than the transition metals or other substances.

[0026] Fig. 1 shows an example of a crystallizer according to the present invention, and Fig. 2 shows an example of a reactor according to the present invention. The liquid flow in the reactor 10 is made a swirling flow, and an injection liquid containing a substance to be injected is injected into the reactor 10 at the contact site in the reactor 10, where reaction treatment is carried out. In the illustrated example, liquids A, B, and C are injected as injection liquids containing a metal salt to be injected, but only liquids A and B may be used.

[0027] In the illustrated reactor 10, a liquid is circulated through circulation lines 11 and 14 (withdrawal lines 11 and The circulating liquid is circulated through the return line 14) and the return liquid of the circulating liquid is introduced into the reactor 10. The reference numeral 15 denotes a heater for heating the liquid, which is provided as necessary. An inlet position including an inlet 10X for the return liquid of the circulating liquid is at one end in the longitudinal direction of the reactor 10, and an outlet position including an outlet 10Y for the dispersion liquid of the produced particles after the reactive crystallization is at the other end in the longitudinal direction.

[0028] The dispersion of the produced particles is introduced into a temporary reservoir 20, where the dispersion is stabilized and the particles are allowed to settle, and the final dispersion of the produced particles 10Z is transferred from the temporary reservoir 20 as an overflow liquid or by a withdrawal pump 22 to a subsequent commercialization means (not shown). 21 is a withdrawal valve. 23 is an adjustment agitator. The remaining liquid is returned to the reactor 10 by a circulation pump 13 through a return line 14.

[0029] A pressure indicator 12A is provided at the inlet of the reactor 10, and a pressure regulating valve 12B is provided at the outlet. The pressure regulator valve 12B is opened to reduce the discharge pressure of the circulating pump 13. Thus, the pressure inside the reactor 10 is kept pressurized. The pressure inside the reactor 10 is adjusted by adjusting the valve opening of the pressure regulating valve 12B based on the current pressure indicated by the pressure indicator 12A. The pressure in the reactor 10 is 0.01 to 1.0 MPa at the inlet of the reactor 10. A pressure of 0.05 to 0.3 MPa is preferable.

[0030] An in-line turbidimeter can be used as the turbidimeter 30 for measuring the turbidity of the dispersion of generated particles. Any turbidimeter using the backscattering method, side scattering method, light transmission / scattering comparison method (integrating sphere method), or light beam transmission method can be used, but when the dispersion of generated particles has a high generated particle concentration, the backscattering method is preferred. This is because when the concentration is high, backward scattering becomes the main phenomenon. The turbidity meter 30 can be installed on the side of the temporary reservoir 20. Alternatively, it can be installed in the circulation paths 11, 14. Although Fig. 1 shows an example in which the turbidity meter is installed between the reactor 10 and the temperature regulator 15 in the circulation path 14, the turbidity meter may be installed between the temporary reservoir 20 and the circulation pump 13, or may be installed in another position. It is more preferable to install the turbidity meter in the temporary reservoir 20 or between the temporary reservoir 20 and the circulation pump 13, since the particle size measurement can be performed more stably by installing the turbidity meter in a place where the crystallization reaction is not affected and the dispersion liquid is sufficiently mixed.

[0031] The liquid flow in the reactor 10 becomes a swirling flow R. In particular, the flow in the inner peripheral portion near the vortex center of the swirling flow R is extremely fast compared to the average flow velocity, and the flow is also highly turbulent. When the injection liquids A to C containing the metal salts to be injected are injected at such a position, the injection liquids are rapidly diffused, enabling a homogeneous reaction. Therefore, as shown in FIG. 2, it is desirable to prevent each of the injection liquids A to C from contacting each other by using injection pipes 16A, 16B . . . until they are discharged from the tip of each pipe. Furthermore, in order to prevent the influence of the swirling flow R, it is desirable to insert a guide pipe 17.

[0032] Here, the injection positions of the injection liquids A to C containing the metal salt to be injected need only be at a position closer to the center than the inner wall surface of the reactor 10 at the contact site within the reactor 10, and as shown in Figure 2, the injection positions are preferably within 2 / 3, and more preferably within 1 / 2 of the radius r from the center. The flow in the inner periphery near the center of the vortex of the swirling flow R is extremely fast compared to the average flow velocity, and the flow is also highly turbulent. At this location, the injected liquid is rapidly diffused, allowing for a homogeneous reaction. Therefore, this device can produce particles with a uniform particle size.

[0033] (Representative particle size acquisition method) Below, we will explain a method of acquiring the particle size of the generated particles from data such as turbidity, without directly measuring the particle size of the generated particles with a particle size distribution measuring device. Figure 3 shows the flow of acquiring the representative particle size of the generated particles. As basic data, the representative particle size of the dispersion liquid of the generated particles, turbidity, the concentration of the generated particles, and the supply amount of each component are acquired (S1). Other measured values ​​such as temperature may also be added. The representative particle size can be measured using a particle size distribution analyzer. For example, dynamic light scattering, laser diffraction / scattering, centrifugal sedimentation, image analysis, etc. can be used. When using the laser diffraction / scattering method, the volume average particle size can be obtained, but weight average particle size, number average particle size, etc. can also be used. In some cases, the particle size is expressed as d50, which is the particle size at 50% by volume, calculated from the smaller particle size. In this case, the particle size at 10% by volume, calculated from the smaller particle size, is expressed as d10, and the particle size at 90% by volume, calculated from the smaller particle size, is expressed as d90. The volume average particle size can also be expressed by the following formula:

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[0034] Next, a correlation equation for obtaining the representative particle size is created based on the obtained basic data (S2). As the correlation equation, a multivariate polynomial, an exponential-logarithmic equation, etc. are conceivable, but considering the complexity of the calculation, a multivariate linear polynomial is preferable. Using the obtained basic data as variables, for example, a multivariate linear function shown below is set, and each coefficient is determined using the least squares method based on the data of the representative particle size obtained by the particle size distribution measuring device. Y is the representative particle size obtained by the particle size distribution measuring device. X1 is, for example, a turbidimeter response value. X2 is, for example, the concentration of the generated particles. X3 and X4 are, for example, the supply amount of each component. Here, in the following equation, two types of component amounts are used for each component amount, but three or more types may be used.

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[0035] In this case, the color of the produced particles affects the turbidity. Therefore, when the produced particles have a color, it is preferable to add basic data that affects the color of the produced particles as a variable. For example, if a nickel sulfate solution is used as liquid A, a cobalt sulfate solution is used as liquid B, and a manganese sulfate solution is used as liquid C, and these solutions are injected into a reactor together with caustic soda, a ternary crystal system of nickel, cobalt, and manganese is obtained. In this case, the ratio of cobalt ions to nickel ions and the ratio of manganese ions to nickel ions affect the color of the generated particles, and therefore, it is preferable to use the turbidity meter response value, the concentration of the generated particles, the ratio of cobalt ions to the supplied nickel ions, and the ratio of manganese ions to nickel ions as variables. Then, the following correlation equation can be set:

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[0036] The concentration of the generated particles is preferably 1 to 40% by mass, more preferably 1 to 15% by mass, and even more preferably 2 to 10% by mass. If the concentration is less than 1% by mass, the intensity of the scattered light from the particles is weakened, and the accuracy of the correlation equation may decrease. If the concentration is more than 2% by mass, the intensity of the scattered light from the particles is sufficient, and the accuracy of the correlation equation increases. On the other hand, if the concentration is more than 40% by mass, the accuracy of the turbidity measurement may decrease as the upper limit of the sensitivity of the scattered light intensity approaches, and in this case, the accuracy of the correlation equation may decrease. If the concentration is less than 15%, there is a sufficient margin for the upper limit of the sensitivity of the scattered light intensity, and the accuracy of the correlation equation increases, and if the concentration is less than 10%, the accuracy of the correlation equation increases for the same reason.

[0037] According to Mie's scattering theory, if the particle diameter of the suspended solid is d, the turbidity is (1 / d) n It is known that the particle size distribution is proportional to the representative particle size. Here, n is considered to be approximately 1. Therefore, when the particle size distribution of the generated particles is wide and contains many particles other than the representative particle size, that is, when the variance of the particle size distribution is large, the influence of particles other than the representative particle size on the turbidity becomes large, and the influence on the accuracy of the correlation equation also becomes large. Therefore, in order to improve the accuracy of the correlation equation, a narrow particle size distribution is preferable. In creating the correlation equation, it is preferable that the value of (d90-d10) / d50 is 1.5 or less for d10, d50, and d90 of the generated particles obtained by a particle size distribution measuring device, which are based on the volume of the generated particles. If it is larger than 1.5, the error due to the influence of particles other than the representative particle size becomes large, and the accuracy of the correlation equation decreases.

[0038] The turbidity meter is preferably an in-line turbidity meter, since it is possible to obtain data successively. The representative particle size obtaining method of the present invention is applicable to both continuous and batch crystallizers. In the case of a batch crystallizer, in order to maintain the operational balance, the dispersion of the produced particles cannot be sampled from the crystallizer until the crystallization process is completed. Therefore, the representative particle size obtaining method using an in-line turbidity meter that can obtain the representative particle size during operation is particularly effective in the batch crystallizer.

[0039] (Representative particle size acquisition system) A representative particle size acquisition system will be described below, which acquires the particle size of generated particles from data such as turbidity, without directly measuring the particle size of the generated particles with a particle size distribution measuring device. The representative particle size acquisition system includes a crystallizer 100, a turbidity acquisition unit 110 that acquires the turbidity of the dispersion of the product particles, a product particle concentration acquisition unit 120 that acquires the concentration of the product particles in the dispersion of the product particles, a component supply amount acquisition unit 130 that acquires the supply amount of metal derived from the metal salt, a correlation equation creation unit 150 that stores a correlation equation that expresses the relationship between the representative particle size of the product particles acquired by the particle size distribution measurement device, the turbidity of the dispersion of the product particles, the concentration of the product particles in the dispersion of the product particles, and the supply amount of one or more metals selected from the metals derived from the metal salt, and a representative particle size calculation unit 140.

[0040] The turbidity acquisition unit 110 acquires the turbidity of the generated particle suspension. An in-line turbidity meter can be used as the turbidity meter 30 that measures the turbidity of the generated particle dispersion. Any turbidity meter using the backscattering method, side scattering method, light transmission / scattering comparison method (integrating sphere method), or light beam transmission method can be used, but when the generated particle concentration in the generated particle dispersion is high, the backscattering method is preferable. This is because when the concentration is high, backward scattering is the main phenomenon.

[0041] The generated particle concentration acquisition unit 120 acquires the concentration of generated particles in the generated particle suspension. The generated particle concentration acquisition unit acquires the concentration of generated particles as a value obtained by dividing the mass of particles generated from each injected metal salt by the mass of the dispersion of all generated particles. For example, when nickel, cobalt, and manganese are injected in a molar ratio of 1:1:1, all of the metals are Ni, 1 / 3 Co 1 / 3 Mn 1 / 3 It is assumed that OH2 is produced and is calculated from the mass of the metal supplied.

[0042] The component supply amount acquisition unit 130 acquires the supply amount of metal components derived from the multiple metal salts supplied to the crystallizer. In particular, since the properties of the particles generated are a factor that affects the acquisition of the representative particle size in the present invention, it is important to acquire the amount of components that affect the properties of the particles generated. For example, when the metal salts supplied to the crystallizer are nickel sulfate, cobalt sulfate, and manganese sulfate, the amounts of nickel, cobalt, and manganese supplied are acquired.

[0043] In addition to the above, for example, a data acquisition unit for acquiring data such as the internal temperature of the crystallizer may be provided.

[0044] According to the representative particle size acquisition system having the above configuration, it is possible to acquire the representative particle size of the produced particles from each data of the turbidity of the dispersion liquid of the produced particles, the concentration of the produced particles, and the metal supply amount without using a particle size distribution measuring device, by using the correlation equation stored in the correlation equation creation unit 150. Note that the correlation equation creation unit 150 does not need to create a correlation equation each time, and can use a correlation equation that has been created and stored in advance.

[0045] (Production example) As for the operating conditions, demineralized water was first charged into the device, and then an aqueous solution adjusted to 3 mol / L of cobalt sulfate, 4 mol / L of manganese sulfate, and 5 mol / L of nickel sulfate was added to the reactor simultaneously with caustic soda water and ammonia water to react and obtain the product particles. As shown in Table 1, operation was performed under multiple conditions, with 100×X3 / X5 varying from 0 to 14.46 and 100×X4 / X5 varying from 0 to 6.02.

[0046] The particle size distribution of the resulting particles was analyzed using a laser diffraction / scattering type particle size distribution analyzer. The laser diffraction / scattering type particle size distribution analyzer used was SALD-2300 (Shimadzu Corporation). The measurement conditions were as follows: a flow cell was used, dispersion was confirmed by ultrasonic irradiation, and the measurement was performed at a refractive index suitable for the sample. In this case, the representative particle size obtained was the volume-based particle size.

[0047] The turbidity of the resulting dispersion of the produced particles was analyzed using a backscattering turbidity meter. The turbidity meter used was an NBP007 (KEMTRAK) or an InPro8100 / S / 120 (Mettler-Toledo). The measurement conditions were a light source wavelength of 850 nm or 880 nm.

[0048] The solid content (%) was calculated assuming that all the raw materials fed to the reactor reacted and metal hydroxides were produced. For example, when X3:X4:X5=1:1:1, the produced particles were Ni 1 / 3 Co 1 / 3 Mn 1 / 3 It was calculated from the masses of nickel, cobalt, and manganese supplied, assuming that OH2 was produced.

[0049] (Example) Using the following correlation equation and the data in Table 1, the coefficients a, b, c, d, and e were calculated by the least squares method.

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[0050] The calculated values ​​(predicted values) of the d50 particle size calculated using the correlation equation based on the data in Table 1 are shown in Table 1. Figure 5 shows a plot of the actual measured values ​​of the d50 particle size using a particle size distribution analyzer and the calculated values ​​using the correlation equation. The coefficient of determination R2 was 0.56.

[0051] (Comparative Example) Without considering the amount of cobalt (X3 (mol)), manganese (X4 (mol)), and nickel (X5 (mol)), a, b, and e were calculated by the least squares method using the following formulas, where X1 (NTU) represents the turbidity of the dispersion of the produced particles, and X2 (mass%) represents the concentration of the produced particles.

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[0052] When the correlation equation according to the present invention is used, the coefficient of determination R of the correlation between the measured value and the calculated value of the d50 particle size 2 is 0.56, and the coefficient of determination R 2 was 0.22, demonstrating the effectiveness of the present invention. [Industrial Applicability]

[0053] The present invention makes it possible to obtain a method for obtaining the particle size of particles produced in a crystallizer during a crystallization process by using a single correlation equation from the measured turbidity, the concentration of the produced particles, and the supply amount of raw material, and makes it possible to easily and quickly predict the representative particle size without using an expensive particle size distribution measuring device. [Table 1] [Explanation of symbols]

[0054] 10...reactor, 10X...inlet, 10Y...outlet, 10Z...dispersion of final produced particles, 11, 14...circulation path, 12A...pressure indicator, 12B...pressure regulating valve, 13...circulation pump, 16A, 16B...injection pipe, 17...guide pipe, 20...reservoir, 22...withdrawal pump, 30...turbidity meter, A, B, C...injection liquid.

Claims

1. A method for obtaining a representative particle size of particles produced in a crystallization step in which aqueous solutions each containing a plurality of types of metal salts are supplied to a crystallizer and brought into contact with each other to produce particles, comprising the steps of: a step of acquiring basic data including a representative particle diameter of the generated particles acquired by a particle size distribution measuring device, a turbidity of a dispersion of the generated particles, a concentration of the generated particles in the dispersion of the generated particles, and a supply amount of metal derived from the metal salt; creating a correlation equation that expresses a relationship between a representative particle diameter of the generated particles, a turbidity of a dispersion of the generated particles, a concentration of the generated particles in the dispersion of the generated particles, and a supply amount of one or more metals selected from the metals, the representative particle diameter being obtained in the step of acquiring basic data; In the crystallization step, a step of acquiring the turbidity of the dispersion of the generated particles, the concentration of the generated particles, and the supply amount of metal derived from the multiple types of metal salts; obtaining a representative particle size of the generated particles by the correlation equation based on the respective values ​​of the turbidity of the dispersion of the generated particles obtained in the crystallization step, the concentration of the generated particles, and the supply amount of one or more metals selected from the metals derived from the metal salt; A method for obtaining a representative particle size of particles produced in a crystallizer, comprising:

2. In the step of creating the correlation equation, The plurality of metal salts are three types, The turbidity of the dispersion of the generated particles is X １ NTU, the concentration of the generated particles is X ２ %, the amount of the metal supplied is X ３ Mol, X ４ Mol, X ５ mol, and the representative particle diameter of the generated particles is Y μm, Y and X １ , X ２ , X ３ , X ４ , X ５ The correlation equation is determined by finding each of the coefficients a, b, c, d, and e by the least squares method in the following equation, which represents the relationship between the above: A method for obtaining a representative particle size of particles produced in a crystallizer according to claim 1. [0010]

3. In the step of creating the correlation equation, The plurality of metal salts are three types, The turbidity of the dispersion of the generated particles is X １ NTU, the concentration of the generated particles is X ２ Mass%, X ３ is the number of moles of cobalt ions, X ４ is the number of moles of manganese ions, X ５ The method for obtaining a representative particle size of particles produced in a crystallizer according to claim 2, wherein m is the number of moles of nickel ions.

4. The method for obtaining a representative particle size of the produced particles in a crystallizer according to any one of claims 1 to 3, wherein the concentration of the produced particles is 1 to 40 mass%.

5. The method for obtaining a representative particle size of the produced particles in a crystallizer according to any one of claims 1 to 3, wherein the turbidity is obtained by measurement with a turbidity meter installed in-line in the crystallizer.

6. In creating the correlation equation, the volume of the generated particles obtained by a particle size distribution measuring device is used as a reference for d10, d50, and d90. The value of (d90-d10) / d50 is 1.5 or less. A method for obtaining a representative particle size of particles produced in the crystallizer according to any one of claims 1 to 3.

7. The method for obtaining a representative particle size of the product particles in a crystallizer according to any one of claims 1 to 3, wherein the crystallization step for obtaining the product particles is a batch type or a continuous type.

8. A system for obtaining a representative particle size of particles produced in a crystallizer, the system comprising: a crystallizer that supplies aqueous solutions each containing a plurality of types of metal salts to the crystallizer and brings the aqueous solutions into contact with each other to produce particles, the system comprising: a turbidity acquisition unit that acquires the turbidity of a dispersion of generated particles in the crystallizer; a generated particle concentration acquisition unit that acquires a concentration of the generated particles in the generated particle dispersion; a metal supply amount acquisition unit that acquires a supply amount of a metal derived from the metal salt; a correlation equation creating unit that stores a correlation equation that represents a relationship between a representative particle diameter of the generated particles obtained by a particle size distribution measuring device, a turbidity of a dispersion of the generated particles, a concentration of the generated particles in the dispersion of the generated particles, and a supply amount of one or more metals selected from the metals derived from the metal salt; a representative particle diameter calculation unit which obtains a representative particle diameter of the produced particles by the correlation equation based on the respective numerical values ​​of the turbidity of the dispersion of the produced particles obtained by the turbidity acquisition unit, the concentration of the produced particles obtained by the produced particle concentration acquisition unit, and the supply amount of one or more metals selected from the metals derived from the metal salt obtained by the metal supply amount acquisition unit; A system for acquiring a representative particle size of particles produced in a crystallizer.

9. The correlation equation creating unit is The plurality of metal salts are three types, The turbidity of the dispersion of the generated particles is X １ NTU, the concentration of the generated particles is X ２ %, the amount of the metal supplied is X ３ Mol, X ４ Mol, X ５ mol, and the representative particle diameter of the generated particles is Y μm, Y and X １ , X ２ , X ３ , X ４ , X ５ In the following formula expressing the relationship between the above, the coefficients a, b, c, d, and e are calculated by the least squares method to create a correlation formula, which is then stored. The system for acquiring a representative particle size of particles produced in a crystallizer according to claim 8. [0010]

10. X ３ is the number of moles of cobalt ions, and X ４ is the number of moles of manganese ions, and X ５ The system for obtaining a representative particle size of particles produced in a crystallizer according to claim 9, wherein the mole number of nickel ions is 1.

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