JP2018047408A - Chemical reactor, and production method of particle using chemical reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical reactor with which quality of particles can efficiently be improved.SOLUTION: In a chemical reactor, particles are deposited in a solution while a raw material liquid is supplied into the solution. The chemical reactor includes: a stirring vessel to contain the solution; a raw material liquid supply tube having a discharge part to discharge the raw material liquid in the stream of the solution; and a flow adjustment member to adjust the stream of the solution on the upstream side of the discharge part, in which the flow adjustment member has a wall surface to receive the stream of the solution and make it flow toward the discharge part, and has protrusions protruding from the wall surface.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a chemical reaction apparatus and a method for producing particles using the chemical reaction apparatus.

  In recent years, with the spread of portable electronic devices such as mobile phones and notebook personal computers, development of small and lightweight secondary batteries having high energy density is required. In addition, as a battery for electric vehicles such as hybrid vehicles, development of a high output secondary battery is also required. There is a lithium ion secondary battery as a non-aqueous electrolyte secondary battery that satisfies such requirements. A lithium ion secondary battery includes a negative electrode, a positive electrode, an electrolytic solution, and the like, and a material capable of desorbing and inserting lithium is used as an active material for the negative electrode and the positive electrode.

  A lithium ion secondary battery using a lithium composite oxide, particularly a lithium cobalt composite oxide that is relatively easy to synthesize as a positive electrode material, is expected as a battery having a high energy density because a high voltage of 4V class is obtained. Practical use is progressing. A battery using a lithium cobalt composite oxide has been developed so far to obtain excellent initial capacity characteristics and cycle characteristics, and various results have already been obtained.

  However, since lithium cobalt composite oxide uses an expensive cobalt compound as a raw material, the unit price per capacity of a battery using this lithium cobalt composite oxide is significantly higher than that of a nickel metal hydride battery. Limited. Therefore, not only for small secondary batteries for portable devices, but also for large-sized secondary batteries for power storage and electric vehicles, it is possible to reduce the cost of positive electrode materials and manufacture cheaper lithium ion secondary batteries There is great expectation for this, and it can be said that its realization has great industrial significance.

  As a new material of the active material for the lithium ion secondary battery, a lithium nickel composite oxide using nickel which is cheaper than cobalt can be cited. This lithium nickel composite oxide is more than the lithium cobalt composite oxide. Since it exhibits a low electrochemical potential, decomposition due to oxidation of the electrolytic solution is less likely to be a problem, higher capacity can be expected, and high battery voltage is exhibited in the same manner as cobalt-based, and therefore, development is actively performed. However, when a lithium-ion secondary battery is produced using a lithium-nickel composite oxide synthesized solely with nickel as a positive electrode material, the cycle characteristics are inferior to those of a cobalt-based battery, and the battery is relatively easy to use and store in a high-temperature environment. Lithium nickel composite oxides in which a part of nickel is substituted with cobalt or aluminum are generally known because they have a drawback that the performance tends to be impaired.

  A general method for producing a positive electrode active material is as follows: (1) First, a nickel composite hydroxide, which is a precursor of a lithium nickel composite oxide, is prepared by neutralization crystallization, and (2) the precursor is converted into a lithium compound. A method of mixing and baking is known. Among these, as a method for producing particles by the neutralization crystallization method of (1), a typical embodiment is a process using a stirring tank.

  In Patent Document 1, a mixed aqueous solution containing a nickel salt and a cobalt salt, an aqueous solution containing an ammonium ion supplier, and a caustic aqueous solution are allowed to react in a stirring tank, and the particles of nickel cobalt composite hydroxide are reacted. It is deposited. It is described that particles having a large particle size, high crystallinity, and a substantially spherical shape can be obtained by setting the ratio of the supply amount to the reaction aqueous solution amount per supply port of the mixed aqueous solution to 0.04 vol% / min or less. ing.

JP 2011-201764 A

  Conventionally, various studies have been made to obtain particles having desired characteristics using a stirring tank.

  However, every time the structure of the apparatus such as the type and diameter of the stirring blade and the volume of the stirring tank changes, it is necessary to determine the conditions.

  The present inventor has studied the conditions that can improve the quality of particles universally in chemical reactors of various structures, and has focused on the volume ratio of the highly supersaturated region in the solution in the stirring tank.

  Here, the high supersaturation region means a region where the concentration of the particle component dissolved in the solution is a predetermined value or more. In the high supersaturation region, the concentration of the particle component is sufficiently higher than the solubility, so that the precipitation of the particle component proceeds at a significant speed.

  The present inventor has found that the smaller the volume ratio of the highly supersaturated region in the solution in the stirring tank, the more slowly the precipitation of the particle component proceeds, so that the particle quality can be improved.

  By the way, the high supersaturation region is formed in the vicinity of the discharge port for discharging the raw material liquid into the solution. In order to reduce the volume of the high supersaturation region, prompt dispersion of the particle components is required, and an increase in the number of revolutions of the stirring blade is effective.

  However, when the rotation speed of the stirring blade is increased, the energy consumption increases.

  This invention is made | formed in view of the said subject, Comprising: It aims at provision of the chemical reaction apparatus which can improve the quality of particle | grains efficiently.

In order to solve the above problems, according to one aspect of the present invention,
A chemical reaction device for precipitating particles in the solution while supplying the raw material liquid into the solution,
A stirring tank containing the solution;
A raw material liquid supply pipe having a discharge section for discharging the raw material liquid in the flow of the solution;
A flow adjusting member for adjusting the flow of the solution on the upstream side of the discharge unit,
A chemical reaction device is provided in which the flow adjusting member has a wall surface that receives the flow of the solution toward the discharge portion and a protrusion that protrudes from the wall surface.

  According to one embodiment of the present invention, a chemical reaction device that can efficiently improve the quality of particles is provided.

It is a top view which shows the chemical reaction apparatus by one Embodiment. It is sectional drawing along the II-II line of FIG. It is a perspective view which shows the principal part of the chemical reaction apparatus by one Embodiment. It is a perspective view which shows the principal part of the chemical reaction apparatus by a 1st modification. It is a perspective view which shows the principal part of the chemical reaction apparatus by a 2nd modification. It is a perspective view which shows the principal part of the chemical reaction apparatus by a 3rd modification. It is a flowchart of the manufacturing method of the nickel containing hydroxide by one Embodiment. It is sectional drawing which modeled the aggregate formed in the first half of the particle growth process by one Embodiment. It is sectional drawing which modeled the outer shell formed in the second half of the particle growth process by one Embodiment. It is a figure which shows the 1st highly supersaturated area | region in the reaction aqueous solution in the nucleation process by one Embodiment. It is a SEM photograph of an example of the particles obtained when the volume ratio of the first highly supersaturated region in the reaction aqueous solution in the continuous stirring tank is 0.025%. It is a SEM photograph of an example of the particle | grains obtained when the volume ratio of the 1st high supersaturation area | region which occupies for the reaction aqueous solution in a continuous stirring tank is 0.100%. It is a figure which shows the 2nd highly supersaturated area | region in the reaction aqueous solution in the particle growth process by one Embodiment. It is a SEM photograph of an example of the section of the particle obtained when the volume ratio of the 2nd high supersaturation field to the reaction aqueous solution in a continuous stirring tank is 0.379%. It is a SEM photograph of an example of the section of the particle obtained when the volume ratio of the 2nd high supersaturation field which occupies for the reaction aqueous solution in a continuous type stirring tank is 0.624%.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In each of the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof will be omitted.

  FIG. 1 is a top view showing a chemical reaction device according to an embodiment. FIG. 2 is a cross-sectional view taken along line II-II in FIG.

  The chemical reaction apparatus 10 deposits particles in the solution while supplying the raw material liquid into the solution. For example, the solution contains a metal salt and a base, the raw material solution contains a metal salt, and the particles are precipitated by neutralization crystallization. When the metal salt includes a nickel salt, the particles are nickel-containing hydroxides. The kind of particles is not limited to nickel-containing hydroxide.

  The chemical reaction apparatus 10 includes, for example, a stirring tank 20, a stirring blade 30, a stirring shaft 40, and a baffle 50. The stirring tank 20 stores the solution in a cylindrical internal space. The stirring blade 30 stirs the solution in the stirring tank 20. The stirring blade 30 is attached to the lower end of the stirring shaft 40. The stirring blade 30 is rotated by rotating the stirring shaft 40 by a motor or the like. The center line of the stirring tank 20, the center line of the stirring blade 30, and the center line of the stirring shaft 40 may coincide with each other and may be vertical. The baffle 50 is also called a baffle plate. The baffle 50 protrudes from the inner peripheral surface of the agitation tank 20, and generates an upward flow and a downward flow by obstructing the rotational flow, thereby improving the efficiency of stirring the solution.

  The inventor has studied the conditions that can improve the quality of particles universally with chemical reaction apparatuses having various structures, and has focused on the volume ratio of the highly supersaturated region in the solution in the stirring tank 20.

  The high supersaturated region means a region where the concentration of the particle component dissolved in the solution is a predetermined value or more. In the high supersaturation region, the concentration of the particle component is sufficiently higher than the solubility, so that the precipitation of the particle component proceeds at a significant speed.

  As the volume ratio of the highly supersaturated region occupying the solution in the stirring tank 20 is smaller, the precipitation of the particle component proceeds more gradually, so that the quality of the particles can be improved. Here, when there are a plurality of high supersaturation regions, the volume of the high supersaturation region means the total volume.

  The high supersaturated region is formed in the vicinity of the raw material liquid discharge port. Since the discharge port is installed in the flow field of the solution, the volume of the highly supersaturated region is affected by the flow field. A flow field changes with conditions, such as the rotation speed of the stirring blade 30, the type and blade diameter of the stirring blade 30, and the volume of the stirring tank 20. Hereinafter, conditions that affect the flow field in the stirring tank 20 are referred to as stirring conditions.

  The flow field in the stirring tank 20 and the volume of the highly supersaturated region can be confirmed by simulation. Hereinafter, steady state fluid analysis in the case of producing nickel hydroxide by reacting nickel sulfate and sodium hydroxide in a continuous stirring tank will be mainly described. As the fluid analysis software, ANSYS CFX Ver15.0 (trade name) manufactured by ANSYS is used. The analysis conditions are shown below.

<Coordinate system>
-Of the region where fluid analysis is performed (hereinafter also referred to as "analysis region"), the area around the stirring shaft and stirring blade is handled by a rotating coordinate system that rotates together with the stirring shaft and stirring blade. The area handled in the rotating coordinate system is cylindrical, and its center line is overlapped with the center line of the stirring shaft and stirring blade, its diameter is set to 115% of the blade diameter of the stirring blade, and the vertical range is stirred. From the inner bottom of the tank to the liquid level.
・ Other analysis areas are handled in the stationary coordinate system.
• The rotating coordinate system and stationary coordinate system are connected using the interface function of the fluid analysis software. As an interface function, the optional “Frozen Rotor” is used.

<Turbulent model>
・ The flow in the stirring tank is not laminar but turbulent. As the turbulence model, an SST (Shear Stress Transport) model is used.

<Chemical reaction>
-The formula of the chemical reaction that occurs in the stirred tank is shown below.
NiSO ₄ + 2NaOH → Ni (OH) ₂ + Na ₂ SO ₄ .
・ In fluid analysis, a single-phase multi-component fluid containing the following five components is handled.
1) Reaction component A: NiSO ₄
2) Reaction component B: NaOH
3) Product component C: Ni (OH) ₂
4) Product component D: Na ₂ SO ₄
5) The speed of water / chemical reaction is calculated by the eddy dissipation model. The vortex dissipation model is a reaction model that assumes that the chemical reaction occurs when the reaction component A and the reaction component B are mixed to the molecular level by turbulent dispersion. The vortex dissipation model setting is the default setting of the fluid analysis software.

<Calculation method of mass fraction of each component>
The total mass fraction of the five components is 1 at an arbitrary position in the analysis region and at an arbitrary time point. Therefore, the mass fraction of each of the four components excluding water among the above five components is a value obtained by solving the transport equation using CFX, and the mass fraction of water is from 1 to the total mass fraction of the above four components. The value obtained by subtracting.

<Boundary conditions>
・ Wall boundary (boundary where fluid does not go in and out)
At the boundary with solids such as a stirring tank, a stirring shaft, a stirring blade, and a baffle, no slip is assumed. On the other hand, there is slippage at the boundary (liquid level) with the outside air. Note that the liquid surface is not deformed by stirring and is a flat surface having a constant height.
・ Inflow boundary (boundary where fluid enters)
An inflow boundary where an aqueous solution containing the reaction component A (hereinafter referred to as “aqueous solution A”) flows into the fluid in the stirring tank and an aqueous solution containing the reaction component B (hereinafter referred to as “aqueous solution B”). Provide separate inflow boundaries.
The inflow rate of the aqueous solution A, the ratio of the reaction component A in the aqueous solution A, and the inflow rate of the aqueous solution B and the ratio of the reaction component B in the aqueous solution B are constant. The inflow flow rate of the aqueous solution B is set so that the pH of the aqueous solution in the stirring tank is maintained at a predetermined value (for example, 12.0).
・ Outflow boundary (boundary where fluid flows out)
An outflow boundary through which the fluid in the agitation tank exits is provided on a part of the inner peripheral surface of the agitation tank. The liquid that flows out contains product components C and D, unreacted reaction components A and B, and water. The outflow amount is set so that the pressure difference between the analysis region and the outside of the system becomes zero.
In the case of an overflow type continuous type, the liquid level is the outflow boundary.

<Thermal conditions>
-The temperature of the fluid in the stirring tank is kept constant at 25 ° C. It is assumed that there is no heat generation due to chemical reaction and no heat inflow or outflow at the inflow boundary or outflow boundary.

<Initial conditions>
The fluid in the agitation tank is homogeneous in the initial state, and includes only two components of the reaction component B and water among the above five components. Specifically, among the fluid in the stirring tank, the initial mass fraction of reaction component A, the initial mass fraction of product component C, the initial mass fraction of product component D is zero, and the initial mass fraction of reaction component B Is set so that the pH of the aqueous solution in the agitation tank becomes the predetermined value.
Note that the initial mass fraction of the generation component C and the initial mass fraction of the generation component D are set to zero here, but in order to reduce the number of iterations (that is, calculation time) for obtaining a steady solution, You may set to the average value in the whole analysis area | region estimated to reach | attain in a state. The average value in the entire analysis region is the quantitative expression represented by the chemical reaction equation, the inflow rate of the aqueous solution A, the ratio of the reaction component A in the aqueous solution A, the inflow rate of the aqueous solution B and the ratio of the reaction component B in the aqueous solution B. It can be calculated based on the relationship.

<Convergence judgment>
-Iterative calculation to obtain a steady solution is the mean square of the flow velocity component (m / s) and pressure (Pa) of each of the above four components at any position in the analysis region. Repeat until the square root residual is 10 ^-4 or less.

<Calculation method of volume in highly supersaturated region>
-A high supersaturation area | region is an area | region where the density | concentration of the production | generation component C melt | dissolved in the aqueous solution in a stirring tank is more than predetermined value. The predetermined value is, as will be described later in detail, in the nucleation step 5.0 mol / ^{m 3,} in the particle growth step to 1.7 mol / ^{m 3.} Hereinafter, the high supersaturation region set in the nucleation step is also referred to as “first high supersaturation region”, and the high supersaturation region set in the particle growth step is also referred to as “second high supersaturation region”. The reason why the lower limit value of the concentration of the first highly supersaturated region is higher than the lower limit value of the concentration of the second highly supersaturated region is that the lower limit concentration at which nucleation occurs is higher than the lower limit concentration at which particle growth occurs. The high supersaturation region is formed around the inflow boundary of the aqueous solution A.
In the fluid analysis, as described above, since the five components are handled as a single-phase multi-component fluid, all the generated components C are handled as liquids. On the other hand, most of the product component C is precipitated and becomes solid, and only the remaining part of the product component C is dissolved in the aqueous solution as a liquid.
Therefore, the volume of the highly supersaturated region is calculated by correcting the concentration distribution of the generated component C obtained by the fluid analysis. In the correction, the concentration of the generated component C is uniformly reduced by a predetermined value in the whole fluid in the stirring tank so that the concentration of the generated component C becomes equivalent to the solubility at the outflow boundary sufficiently separated from the inflow boundary of the aqueous solution A.
・ In addition, when the agitation tank is a batch type rather than a continuous type, there is no outflow boundary. In this case, in the concentration distribution correction, the concentration of the generated component C can be uniformly reduced in the entire fluid in the stirring tank by a predetermined value so that the concentration of the generated component C becomes equivalent to the solubility at the liquid level of the aqueous solution in the stirring tank. That's fine. Incidentally, in the case of the overflow type continuous type, the liquid level is the outflow boundary.

In the above description, the analysis conditions for obtaining nickel hydroxide are shown, but the analysis conditions for obtaining nickel composite hydroxide can also be set similarly. For example, when nickel sulfate or manganese sulfate is reacted with sodium hydroxide to obtain a nickel manganese composite hydroxide, the fluid analysis handles a single-phase multi-component fluid containing the following seven components.
1) Reaction component A1: NiSO ₄
2) Reaction component A2: MnSO ₄
3) Reaction component B: NaOH
4) Product component C1: Ni (OH) ₂
5) Product component C2: Mn (OH) ₂
6) Product component D: Na ₂ SO ₄
7) Water Here, two chemical reactions of “A1 + 2B → C1 + D” and “A2 + 2B → C2 + D” occur in the stirring tank, and a vortex dissipation model corresponding to each chemical reaction is used as a reaction model. The reaction component A1 and the reaction component A2 are supplied from the same inflow boundary in a state of being uniformly dissolved in water. That is, the aqueous solution A containing both the reaction component A1 and the reaction component A2 is supplied from the inflow boundary. A highly supersaturated region is formed around the inflow boundary of the aqueous solution A. The high supersaturated region is a region where the total molar concentration of all metal hydroxides (here, the generated component C1 and the generated component C2) among the generated components dissolved in the aqueous solution in the stirring tank is equal to or higher than the predetermined value. That is.

  Here, the reason for summing up the molar concentrations of all the metal hydroxides among the generated components will be described. First, as described above, the reaction component A1 and the reaction component A2 flow from the same inflow boundary while being uniformly dissolved in water. At this time, the reaction component A1 and the reaction component A2 react quickly with the reaction component B to generate the product component C1 and the product component C2. Therefore, the generation component C1 and the generation component C2 exist in a sufficiently mixed state at the time of generation. As a result, the product component C1 and the product component C2 are not precipitated as individual hydroxides, but as a solid solution of hydroxides in which the respective components are combined.

  The number of inflow boundaries of the aqueous solution A may be plural, and the number of high supersaturation regions may be plural. When there are a plurality of high supersaturation regions, the volume of the high supersaturation region means the total volume.

  The method for producing the nickel-containing hydroxide may include a step of confirming, by simulation, the volume ratio of the highly supersaturated region in the aqueous solution in the stirring tank. This confirmation may be performed every time the manufacturing conditions are changed. For example, in the case of a batch type, confirmation only needs to be performed once while the manufacturing conditions are the same, and each confirmation is unnecessary.

The inventor has studied, by simulation, means for reducing the volume of the high supersaturation region when the stirring conditions are the same and the supply flow rate of the raw material liquid into the stirring tank 20 is the same. As a result, the volume of the highly supersaturated region mainly depends on (1) the number N of raw material liquid outlets and (2) U and K in the vicinity of the raw material liquid outlets (details will be described later). I found. U is the flow speed (m / s), and K is the turbulent diffusion coefficient (m ² / s).

Table 1 shows the number N of the raw material liquid discharge ports and the volumes V1 and V2 of the high supersaturation region when the stirring conditions are the same and the supply flow rate of the raw material liquid into the stirring tank 20 is the same. Show the relationship. The supply flow rate from each discharge port when N is plural is 1 / N of the supply flow rate from the discharge port when N is 1. The supply flow rate is the supply amount per unit time. Further, U and K in the vicinity of each discharge port when N is plural are substantially the same as U and K in the vicinity of the discharge port when N is 1. Further, the interval between the discharge ports when N is plural is set so that the highly supersaturated regions do not overlap each other.
In Table 1, V1 represents the volume of the first highly supersaturated region, and V2 represents the volume of the second highly supersaturated region. V1 ₀ represents the value of V1 when N is 1, and V2 ₀ represents the value of V2 when N is 1. When N is plural, V1 means the total volume of the N first high supersaturation regions, and V2 means the total volume of the N second high supersaturation regions.

As is clear from Table 1, there was a tendency for the volumes V1 and V2 of the high supersaturation region to decrease as the number N of the raw material liquid discharge ports increased. This tendency was similarly observed even when the stirring conditions were changed. Further, this tendency was similarly observed even when the supply flow rate of the raw material liquid into the stirring tank was changed. The present inventor has found that the volumes V1 and V2 of the high supersaturation region can be reduced by dividing the raw material liquid and supplying it into the stirring tank from a plurality of discharge ports.

  Although the chemical reaction apparatus of this embodiment has one discharge part 61 (refer FIG. 3) which discharges a raw material liquid in the solution in the stirring tank 20, you may have multiple. In this case, one discharge port is formed in each discharge portion 61. By dividing the raw material liquid into the stirring tank 20 from the plurality of discharge units 61, the volumes V1 and V2 of the highly supersaturated region in the solution in the stirring tank 20 can be reduced, and the quality of the obtained particles can be improved.

  In order to sufficiently obtain this effect, it is preferable to set the interval between the discharge portions 61 so that the highly supersaturated regions do not overlap each other. If the discharge units 61 are close to each other so that the highly supersaturated regions overlap each other, the significance of making the number of the discharge units 61 plural is reduced. Whether or not the highly supersaturated regions overlap can be determined by the simulation.

  In order to prevent the first highly supersaturated regions from overlapping each other in the nucleation step, the interval between the centers of the discharge portions 61 is, for example, 75 mm or more. Further, in order to prevent the second highly supersaturated regions from overlapping each other in the particle growth step, the interval between the centers of the discharge portions 61 is, for example, 120 mm or more.

  Only one of (A) the first highly supersaturated regions do not overlap each other in the nucleation step and (B) the second highly supersaturated regions do not overlap each other in the particle growth step may be established. The interval between the ejection units 61 may be set so as to be established.

  The interval between the discharge units 61 may be the same in the nucleation step and the particle growth step, but may be changed according to the step when the nucleation step and the particle growth step are performed separately.

  Further, the present inventor has found that the volume of the high supersaturation region can be reduced by installing the discharge port of the raw material liquid at a position where U and K in the stirring tank are large. The larger K is, the more easily the raw material liquid diffuses, so the volume of the highly supersaturated region becomes smaller. Further, as U is larger, the amount of the solution is relatively increased at the joining point of the raw material liquid and the solution, so that the raw material liquid is easily dispersed and the volume of the high supersaturation region is reduced.

  FIG. 3 is a perspective view showing a main part of the chemical reaction device according to one embodiment. In FIG. 3, the arrow represents the direction of the solution flow. As shown in FIG. 3, the chemical reaction apparatus includes a raw material liquid supply pipe 60 including a discharge unit 61 that discharges a raw material liquid in the flow of the solution, and a flow adjustment that adjusts the flow of the solution on the upstream side of the discharge unit 61. Member 70.

  The raw material liquid supply pipe 60 includes a discharge portion 61 that discharges the raw material liquid in the flow of the solution. A discharge port is formed in the discharge unit 61, and the raw material liquid is discharged from the discharge port. The raw material liquid supply pipe 60 is, for example, inserted downward from the liquid surface of the solution, has a discharge portion 61 at the lower end portion, and discharges the raw material liquid downward from the discharge portion 61.

  The raw material liquid supply pipe 60 may protrude upward from the bottom of the agitation tank 20, have a discharge part 61 at the upper end, and discharge the raw material liquid upward from the discharge part 61. Further, the raw material liquid supply pipe 60 may have a discharge part 61 at the center in the vertical direction, and discharge the raw material liquid from the discharge part 61 in the horizontal direction. The position of the discharge unit 61 and the discharge direction are not particularly limited.

  The flow adjusting member 70 is a plate-like member, for example. In FIG. 3, the flow adjusting member 70 is connected to the raw material liquid supply pipe 60 in order to fix the posture with respect to the raw material liquid supply pipe 60, but may be provided apart from the raw material liquid supply pipe 60. The position and orientation of the flow adjusting member 70 may be changed according to the position of the ejection unit 61 and the ejection direction.

  The flow adjusting member 70 has a wall surface 71 that receives the flow of the solution toward the discharge unit 61. The wall surface 71 is inclined with respect to the main direction of the flow F <b> 1 that collides with the wall surface 71, changes the direction of the flow F <b> 1, and forms a flow F <b> 11 toward the discharge unit 61 along the wall surface 71. The flow F <b> 11 that has collided with the wall surface 71 and changed the direction toward the discharge unit 61 and the flow F <b> 2 that has not collided with the wall surface 71 and directed toward the discharge unit 61 merge in the vicinity of the discharge unit 61. Therefore, the flow speed U in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be efficiently reduced.

  The flow adjusting member 70 has a protrusion 72 protruding from the wall surface 71. A plurality of protrusions 72 may be provided at intervals as shown in FIG. The shape of the protrusion 72 is a columnar shape in FIG. 3, but may be an elliptical column shape, a rectangular column shape, or the like. Since the flow F11 toward the discharge part 61 along the wall surface 71 cannot completely wrap around the back side of the protrusion 72, a phenomenon called flow separation occurs, and a vortex is formed on the back side of the protrusion 72. Propagate to the vicinity of 61. Therefore, the turbulent diffusion coefficient K in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be reduced more efficiently.

  FIG. 4 is a diagram showing a main part of the chemical reaction device according to the first modification. In the above embodiment, the flow F <b> 1 above the discharge unit 61 collides with the flow adjustment member 70. On the other hand, in this modification, the flow F3 below the discharge unit 61 collides with the flow adjustment member 70A. Hereinafter, the difference will be mainly described.

  As shown in FIG. 4, the flow adjusting member 70 </ b> A has a wall surface 71 </ b> A that receives the flow F <b> 3 below the discharge unit 61 toward the discharge unit 61 on the upstream side of the discharge unit 61. The wall surface 71A is inclined with respect to the main direction of the flow F3 that collides with the wall surface 71A, changes the direction of the flow F3, and forms a flow F31 toward the discharge portion 61 along the wall surface 71A. The flow F31 that has collided with the wall surface 71A and changed the direction toward the discharge unit 61 and the flow F2 that has traveled toward the discharge unit 61 without colliding with the wall surface 71A merge in the vicinity of the discharge unit 61. Therefore, the flow speed U in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be efficiently reduced.

  The flow adjusting member 70A has a protrusion 72A protruding from the wall surface 71A. A plurality of protrusions 72A may be provided at intervals as shown in FIG. The shape of the protrusion 72A is a columnar shape in FIG. 4, but may be an elliptical column shape, a rectangular column shape, or the like. Since the flow F31 directed toward the discharge portion 61 along the wall surface 71A cannot completely wrap around the back side of the protrusion 72A, a phenomenon called flow separation occurs, and a vortex is formed on the back side of the protrusion 72A. Propagate to the vicinity of 61. Therefore, the turbulent diffusion coefficient K in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be reduced more efficiently.

  FIG. 5 is a perspective view showing a main part of a chemical reaction device according to a second modification. In the said embodiment, the wall surface 71 of the flow adjustment member 70 is comprised by a single plane. On the other hand, in the present modification, the wall surface 71B of the flow adjusting member 70B is configured by a fan-shaped curved surface. Hereinafter, the difference will be mainly described.

  Similar to the flow adjustment member 70 of the above-described embodiment, the flow adjustment member 70B of the present modification includes a wall surface 71B that receives the flow of the solution toward the discharge unit 61, and a protrusion 72B that protrudes from the wall surface 71B. Therefore, U and K in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be efficiently reduced.

  The wall surface 71B of the flow adjusting member 70B is, for example, a fan-shaped curved surface. The wall surface 71B has two linear side edges 71Ba and 71Bb that are closer to each other toward the discharge section 61, and is recessed downstream with respect to a plane connecting both side edges 71Ba and 71Bb. Thereby, the flows F11 to F13 (including the vortex formed by the protrusion 72B of the wall surface 71B) along the wall surface 71B can be collected toward the discharge unit 61. Therefore, U and K in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be reduced more efficiently.

  In addition, although the flow adjustment member 70B of this modification has the protrusion 72B which protrudes from the wall surface 71B, it does not need to have the protrusion 72B. In this case, by collecting the flows F11 to F13 along the wall surface 71B toward the discharge unit 61, U in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be efficiently reduced. it can. In addition, the flow adjusting member 70B of the present modification receives the flow F1 above the discharge unit 61, but the flow F3 below the discharge unit 61 (FIG. 4) in the same manner as the flow adjustment member 70A of the first modification. See).

  FIG. 6 is a perspective view showing a main part of a chemical reaction device according to a third modification. In the said embodiment, the wall surface 71 of the flow adjustment member 70 is comprised by a single plane. On the other hand, in the present modification, the wall surface 71C of the flow adjusting member 70C is constituted by a plurality of planes and has a V-shaped cross-sectional shape. Hereinafter, the difference will be mainly described.

  Similarly to the flow adjusting member 70 of the above-described embodiment, the flow adjusting member 70C of the present modification includes a wall surface 71C that receives the flow of the solution toward the discharge unit 61, and a protrusion 72C that protrudes from the wall surface 71C. Therefore, U and K in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be efficiently reduced.

  The wall surface 71C of the flow adjusting member 70C is constituted by, for example, a plurality of planes. The wall surface 71 </ b> C has two linear side edges 71 </ b> Ca and 71 </ b> Cb that are closer to each other toward the discharge unit 61, and is recessed downstream with respect to a plane connecting both side edges 71 </ b> Ca and 71 </ b> Cb. Accordingly, the flows F11 to F13 (including the vortex formed by the protrusion 72C of the wall surface 71C) along the wall surface 71C can be collected toward the discharge unit 61. Therefore, U and K in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be reduced more efficiently.

  In addition, although the flow adjustment member 70C of this modification has the protrusion 72C which protrudes from the wall surface 71C, it does not need to have the protrusion 72C. In this case, by collecting the flows F11 to F13 along the wall surface 71C toward the discharge unit 61, U in the vicinity of the discharge unit 61 can be increased, and the volume of the high supersaturation region can be efficiently reduced. it can. Further, the flow adjusting member 70C of the present modification receives the flow F1 above the discharge unit 61, but the flow F3 below the discharge unit 61 (FIG. 4) in the same manner as the flow adjustment member 70A of the first modification. See).

  FIG. 7 is a flowchart of a method for producing a nickel-containing hydroxide using a chemical reaction device according to an embodiment. As shown in FIG. 7, the method for producing a nickel-containing hydroxide is to obtain particles of nickel-containing hydroxide by neutralization crystallization, and a nucleation step S11 for generating nuclei of particles, And a particle growth step S12 for growth. Hereinafter, although each process is demonstrated, the nickel containing hydroxide obtained is demonstrated before that.

(Nickel-containing hydroxide)
The nickel-containing hydroxide is used as a precursor of the positive electrode active material of the lithium ion secondary battery. Nickel-containing hydroxide is, for example, (1) the general _{formula: Ni 1-x-y Co} x Al y (OH) 2 + α (0 ≦ x ≦ 0.3,0.005 ≦ y ≦ 0.15,0 ≦ or a nickel complex hydroxide represented by alpha ≦ 0.5), or, (2) the general _{formula: Ni x Co y Mn z M} t (OH) 2 + α (x + y + z + t = 1,0.1 ≦ x ≦ 0.7, 0.1 ≦ y ≦ 0.5, 0.1 ≦ z ≦ 0.8, 0 ≦ t ≦ 0.02, 0 ≦ α ≦ 0.5, M is Ti, V, Cr And one or more additional elements selected from Zr, Nb, Mo, Hf, Ta, and W).

  The nickel-containing hydroxide contains nickel, and preferably further contains a metal other than nickel. A hydroxide further containing a metal other than nickel is referred to as a nickel composite hydroxide. The metal composition ratio (for example, Ni: Mn: Co: M) of the nickel composite hydroxide is maintained even in the obtained positive electrode active material, so that it matches the metal composition ratio required for the positive electrode active material. Adjusted to

(Method for producing nickel-containing hydroxide)
As described above, the method for producing the nickel-containing hydroxide includes the nucleation step S11 and the particle growth step S12. In this embodiment, the nucleation step S11 and the particle growth step S12 are performed separately by controlling the pH value of the aqueous solution in the stirring tank using a batch type stirring tank.

  In the nucleation step S11, nucleation occurs prior to particle growth, and particle growth hardly occurs. On the other hand, in the grain growth step S12, grain growth takes precedence over nucleation and almost no new nuclei are produced. By carrying out the nucleation step S11 and the particle growth step S12 separately, homogeneous nuclei with a narrow particle size distribution range can be formed, and thereafter the nuclei can be grown homogeneously.

  Hereinafter, the nucleation step S11 and the particle growth step S12 will be described. The aqueous solution in the stirring vessel in the nucleation step S11 and the aqueous solution in the stirring vessel in the particle growth step S12 have different pH value ranges, but the ammonia concentration range and temperature range may be substantially the same. .

  In addition, in this embodiment, although a batch type stirring tank is used, you may use a continuous stirring tank. In the latter case, the nucleation step S11 and the particle growth step S12 are performed simultaneously. In this case, the range of the pH value of the aqueous solution in the stirring tank is naturally the same, and may be set in the vicinity of 12.0, for example.

(Nucleation process)
First, a raw material liquid is prepared. The raw material liquid contains at least a nickel salt, and preferably further contains a metal salt other than the nickel salt. As the metal salt, nitrate, sulfate, hydrochloride and the like are used. More specifically, for example, nickel sulfate, manganese sulfate, cobalt sulfate, titanium sulfate, ammonium peroxotitanate, potassium oxalate, vanadium sulfate, ammonium vanadate, chromium sulfate, potassium chromate, zirconium sulfate, zirconium nitrate, Niobium oxalate, ammonium molybdate, sodium tungstate, ammonium tungstate and the like are used.

  Since the metal composition ratio (for example, Ni: Mn: Co: M) of the raw material liquid is also maintained in the obtained nickel composite hydroxide, it should match the composition ratio required for the nickel composite hydroxide. Adjusted.

  Moreover, the aqueous solution which supplied and mixed alkaline aqueous solution, aqueous ammonia solution, and water in the stirring tank is stored. The mixed aqueous solution is hereinafter referred to as “pre-reaction aqueous solution”. The pH value of the pre-reaction aqueous solution is adjusted in the range of 12.0 to 14.0, preferably 12.3 to 13.5, based on the liquid temperature of 25 ° C. The concentration of ammonia in the pre-reaction aqueous solution is preferably adjusted within the range of 3 to 25 g / L, more preferably 5 to 20 g / L, and still more preferably 5 to 15 g / L. Furthermore, the temperature of the pre-reaction aqueous solution is preferably adjusted within the range of 20 to 60 ° C, more preferably 35 to 60 ° C.

  As the alkaline aqueous solution, for example, one containing an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is used. The alkali metal hydroxide may be supplied as a solid, but is preferably supplied as an aqueous solution.

  As the aqueous ammonia solution, one containing an ammonia supplier is used. As the ammonia supplier, for example, ammonia, ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium fluoride and the like can be used.

  In this embodiment, an ammonia supplier is used as the non-reducing complexing agent, but ethylenediaminetetraacetic acid, nitritotriacetic acid, uracil diacetic acid, glycine, or the like may be used. Any non-reducing complexing agent may be used as long as it can form a complex by binding nickel ions or the like in an aqueous solution in a stirring tank.

  After adjusting the pH, ammonia concentration, temperature, etc. of the aqueous solution before reaction, the raw material solution is supplied into the stirring vessel while stirring the aqueous solution before reaction. As a result, a reaction aqueous solution in which the pre-reaction aqueous solution and the raw material liquid are mixed is formed in the stirring tank, nuclei are generated by neutralization crystallization, and the nucleation step S11 is started.

  In the nucleation step S11, if the pH value of the reaction aqueous solution is 12.0 or more, nucleation becomes more dominant than particle growth. In addition, in the nucleation step S11, if the pH value of the reaction aqueous solution is 14.0 or less, it is possible to prevent the nuclei from becoming too fine and to prevent the reaction aqueous solution from gelling. In the nucleation step S11, the fluctuation range (maximum value and minimum value range) of the pH value of the aqueous reaction solution is preferably 0.4 or less.

  Further, in the nucleation step S11, when the ammonia concentration in the reaction aqueous solution is 3 g / L or more, the solubility of metal ions can be kept constant, and nuclei having a uniform shape and particle size are easily generated. In addition, in the nucleation step S11, when the ammonia concentration in the reaction aqueous solution is 25 g / L or less, metal ions remaining in the liquid without being precipitated are reduced, and the production efficiency is improved. In the nucleation step S11, the fluctuation range (maximum value and minimum value) of the pH value of the aqueous reaction solution is preferably 5 g / L or less.

  Further, in the nucleation step S11, if the temperature of the reaction aqueous solution is 20 ° C. or higher, the solubility of the nickel-containing hydroxide is high, so that nucleation occurs slowly and nucleation control is easy. On the other hand, if the temperature of the reaction aqueous solution is 60 ° C. or lower, the volatilization of ammonia can be suppressed, so that the amount of ammonia water used can be reduced and the production cost can be reduced.

  In the nucleation step S11, in addition to the raw material liquid, an alkaline aqueous solution and an aqueous ammonia solution are supplied into the stirring tank so that the pH value, ammonia concentration, and temperature of the aqueous reaction solution are maintained within the above ranges. Thereby, the production | generation of a nucleus is continued in reaction aqueous solution. Then, when a predetermined amount of nuclei is generated, the nucleation step S11 is terminated. Whether or not a predetermined amount of nuclei has been generated can be estimated from the supply amount of the metal salt.

(Particle growth process)
After the completion of the nucleation step S11 and before the start of the particle growth step S12, the pH value of the reaction aqueous solution in the stirring vessel is 10.5 to 12.0, preferably 11.0 to 12 on the basis of the liquid temperature of 25 ° C. 0.0 and lower than the pH value in the nucleation step S11. The pH value is adjusted by stopping the supply of the alkaline aqueous solution into the stirring tank, or supplying an inorganic acid (for example, sulfuric acid in the case of sulfate) in which the metal of the metal salt is replaced with hydrogen into the stirring tank. It can be adjusted with.

  After adjusting the pH, ammonia concentration, temperature, etc. of the reaction aqueous solution, the raw material liquid is supplied into the stirring tank while stirring the reaction aqueous solution. Thereby, the growth of the nucleus (particle growth) starts by neutralization crystallization, and the particle growth step S12 is started. In the present embodiment, the nucleation step S11 and the particle growth step S12 are performed in the same stirring tank, but may be performed in different stirring tanks.

  In the particle growth step S12, if the pH value of the aqueous reaction solution is 12.0 or less and lower than the pH value in the nucleation step S11, new nuclei are hardly generated, and particle growth is more preferable than nucleation. Preferentially occurs.

  When the pH value is 12.0, it is a boundary condition between nucleation and particle growth, and therefore the priority order changes depending on the presence or absence of nuclei present in the reaction aqueous solution. For example, if the pH value of the nucleation step S11 is higher than 12.0 to cause a large amount of nucleation, and then the pH value is set to 12.0 in the particle growth step S12, a large amount of nuclei exist in the reaction aqueous solution. , Grain growth is a priority. On the other hand, when no nuclei exist in the reaction aqueous solution, that is, when the pH value is set to 12.0 in the nucleation step S11, nucleation takes precedence because there are no growing nuclei. Thereafter, if the pH value is made smaller than 12.0 in the particle growth step S12, the generated nucleus grows. In order to clearly separate nucleation and particle growth, the pH value of the particle growth step is preferably 0.5 or more lower than the pH value of the nucleation step, more preferably 1.0 or more.

  In the particle growth step S12, when the pH value of the reaction aqueous solution is 10.5 or more, the solubility by ammonia is low, so that metal ions remaining in the liquid without being precipitated are reduced, and the production efficiency is improved.

  In the particle growth step S12, in addition to the raw material liquid, an alkaline aqueous solution and an aqueous ammonia solution are supplied into the stirring tank so that the pH value, ammonia concentration, and temperature of the aqueous reaction solution are maintained within the above ranges. Thereby, particle growth is continued in the reaction aqueous solution.

  The particle growth step S12 can be divided into a first half and a second half by switching the atmosphere in the stirring tank. The first half atmosphere is an oxidizing atmosphere as in the nucleation step S11. The oxygen concentration in the oxidizing atmosphere is 1% by volume or more, preferably 2% by volume or more, more preferably 10% by volume or more. The oxidizing atmosphere may be an easily controlled air atmosphere (oxygen concentration: 21% by volume). The upper limit of the oxygen concentration in the oxidizing atmosphere is not particularly limited, but is 30% by volume or less. On the other hand, the latter atmosphere is a non-oxidizing atmosphere. The oxygen concentration in the non-oxidizing atmosphere is 1% by volume or less, preferably 0.5% by volume or less, more preferably 0.3% by volume or less. The oxygen concentration in the non-oxidizing atmosphere is controlled by mixing oxygen gas or air with an inert gas.

  FIG. 8 is a cross-sectional view schematically showing aggregates formed in the first half of the particle growth step according to an embodiment. FIG. 9 is a cross-sectional view schematically showing an outer shell formed in the latter half of the particle growth process according to an embodiment.

  In the first half of the particle growth step S12, the seed crystal particles 2 are formed by the growth of the nuclei, and when the seed crystal particles 2 become large to some extent, the seed crystal particles 2 collide with each other. Aggregates 4 are formed. On the other hand, a dense outer shell 6 is formed around the aggregate 4 in the latter half of the particle growth step S12. As a result, particles composed of the aggregate 4 and the outer shell 6 are obtained.

  The structure of the nickel-containing hydroxide particles is not limited to the structure shown in FIG. For example, when the nucleation step S11 and the particle growth step S12 are performed at the same time, the structure of the particles obtained upon completion of neutralization crystallization is a structure different from the structure shown in FIG. For example, the structure corresponding to the seed crystal particles 2 and the structure corresponding to the outer shell 6 are mixed to form a uniform structure in which the boundary is not easily understood.

  When the nickel-containing hydroxide particles grow to a predetermined particle size, the particle growth step S12 is terminated. The particle size can be estimated from the supply amount of the metal salt in each of the nucleation step S11 and the particle growth step S12.

  In addition, after completion | finish of nucleation process S11, supply of raw material liquid etc. may be stopped in the middle of particle growth process S12, stirring of reaction aqueous solution may be stopped, particle | grains may be settled, and supernatant liquid may be discharged | emitted. Thereby, the metal ion density | concentration in the reaction aqueous solution decreased by neutralization crystallization can be raised.

  FIG. 10 is a diagram showing a first highly supersaturated region in the aqueous reaction solution in the nucleation step according to one embodiment. In FIG. 10, the flow adjustment member 70 of FIG. 3 is used, but the flow adjustment member 70A of FIG. 4, the flow adjustment member 70B of FIG. 5, the flow adjustment member 70C of FIG.

The first highly supersaturated region 12A means a region where the molar concentration of the nickel-containing hydroxide dissolved in the reaction aqueous solution is 5.0 mol / m ³ or more. In the first highly supersaturated region 12A, the molar concentration of the nickel-containing hydroxide is sufficiently higher than the solubility, so that nucleation occurs at a significant rate.

Here, the solubility means a limit amount (g / 100 g-H ₂ O) of a nickel-containing hydroxide that is soluble in 100 g of water. The solubility of nickel hydroxide (Ni (OH) ₂ ) is, for example, 10 ⁻⁷ (g / 100 g-H ₂ O). Thus, since the solubility of nickel-containing hydroxide is close to zero, it is negligibly small compared to the lower limit value of 5.0 mol / m ³ of the molar concentration of the first highly supersaturated region 12A.

  FIG. 11 is an SEM photograph of an example of particles obtained when the volume ratio of the first highly supersaturated region in the reaction aqueous solution in the continuous stirring tank is 0.025%. The outer surface of the particle | grains shown in FIG. 11 was smooth, and unevenness was hardly recognized. On the other hand, FIG. 12 is a SEM photograph of an example of particles obtained when the volume ratio of the first highly supersaturated region in the reaction aqueous solution in the continuous stirring tank is 0.100%. Remarkable irregularities were observed on the outer surface of the particles shown in FIG.

  As apparent from FIGS. 11 and 12, from the viewpoint of suppressing the occurrence of irregularities on the outer surface of the particles obtained upon completion of neutralization crystallization, the volume of the first highly supersaturated region in the reaction aqueous solution in the nucleation step S11. The ratio (hereinafter referred to as the first volume ratio) is preferably less than 0.100%. If the first volume ratio is less than 0.100%, the reason why it is possible to suppress the occurrence of irregularities on the outer surface of the particles obtained at the completion of neutralization crystallization is estimated as follows.

  In the nucleation step S11, nuclei are mainly generated in the first highly supersaturated region 12A and then dispersed throughout the reaction aqueous solution. When the first volume ratio is less than 0.100%, the number of nuclei generated per unit volume of the reaction aqueous solution is small. Therefore, in the first half of the particle growth step S12, the number of seed crystal particles 2 per unit volume of the reaction aqueous solution is relatively small, and the number of aggregates 4 composed of a plurality of seed crystal particles 2 is also relatively small. As a result, in the latter half of the particle growth step S12, the thickness of the outer shell 6 formed around the aggregate 4 increases. Therefore, the unevenness of the outer surface of the aggregate 4 can be covered with the thick outer shell 6, and the unevenness of the outer surface of the finally obtained particles can be reduced. This effect is also obtained when the nucleation step S11 and the particle growth step S12 are performed simultaneously.

  From the viewpoint of reducing unevenness on the outer surface of the particles obtained upon completion of neutralization crystallization, the smaller the first volume ratio, the better. The first volume ratio depends on U and K of the flow field in the vicinity of the discharge unit 61. The larger the U and K, the smaller the first volume ratio. The first volume ratio is preferably 0.070% or less, more preferably 0.050% or less, and still more preferably 0.030% or less. However, since U and K are restricted by the capacity of the motor that rotates the stirring shaft 40, the first volume ratio is preferably 0.004% or more.

  In the nucleation step S <b> 11, the raw material liquid may be divided and discharged from the plurality of discharge portions 61 into the reaction aqueous solution. Thereby, a 1st volume ratio can be made small efficiently. At this time, it is preferable that the intervals between the plurality of discharge units 61 are set so that the plurality of first highly supersaturated regions 12A discharged from the plurality of discharge units 61 do not overlap.

  FIG. 13 is a diagram showing a second highly supersaturated region in the aqueous reaction solution in the particle growth step according to an embodiment. In FIG. 13, the flow adjustment member 70 of FIG. 3 is used, but the flow adjustment member 70A of FIG. 4, the flow adjustment member 70B of FIG. 5, the flow adjustment member 70C of FIG.

The second highly supersaturated region 12B means a region where the molar concentration of the nickel-containing hydroxide dissolved in the reaction aqueous solution is 1.7 mol / m ³ or more. In the second highly supersaturated region 12B, the molar concentration of the nickel-containing hydroxide is sufficiently higher than the solubility, so that particle growth occurs at a significant rate.

As described above, since the solubility of the nickel-containing hydroxide is close to zero, it is negligibly small compared to the lower limit value of 1.7 mol / m ³ of the molar concentration of the second highly supersaturated region 12B.

  FIG. 14 is an SEM photograph of an example of a cross section of particles obtained when the volume ratio of the second highly supersaturated region in the reaction aqueous solution in the continuous stirring tank is 0.379%. No annual ring-like structure was observed in the cross section of the particle shown in FIG. On the other hand, FIG. 15 is an SEM photograph of an example of a cross section of the particles obtained when the volume ratio of the second highly supersaturated region in the reaction aqueous solution in the continuous stirring tank is 0.624%. In the cross section of the particle shown in FIG. 15, an annual ring-like structure was observed at a position indicated by an arrow.

  As apparent from FIGS. 14 and 15, from the viewpoint of suppressing the generation of annual ring-like structures, the volume ratio of the second highly supersaturated region 12B in the reaction aqueous solution (hereinafter referred to as the second volume ratio) is 0.624. It is preferable that it is less than%. If the second volume ratio is less than 0.624%, the reason why generation of an annual ring-like structure can be suppressed is estimated as follows.

  In the particle growth step S12, the particles are dispersed throughout the reaction aqueous solution and grow mainly when passing through the second highly supersaturated region 12B. If the volume ratio of the second highly supersaturated region 12B in the entire reaction aqueous solution is less than 0.624%, particle growth occurs gently, and generation of an annual ring-like structure composed of a plurality of layers having different densities can be suppressed. It is presumed that the slow growth of grain growth can suppress the change in crystal growth orientation and the generation of voids accompanying the change.

  From the viewpoint of suppressing the generation of an annual ring-like structure, the volume ratio of the second highly supersaturated region 12B in the reaction aqueous solution (hereinafter referred to as the second volume ratio) is preferably as small as possible. The second volume ratio depends on U and K of the flow field in the vicinity of the discharge unit 61. The larger the U or K, the smaller the second volume ratio. The second volume ratio is preferably 0.600% or less, more preferably 0.500% or less, and still more preferably 0.400% or less. However, since U and K are restricted by the capacity of the motor that rotates the stirring shaft 40, the second volume ratio is preferably 0.019% or more.

  In the particle growth step S12, the raw material liquid may be divided and discharged from the plurality of discharge portions 61 into the reaction aqueous solution. Thereby, a 2nd volume ratio can be made small efficiently. At this time, it is preferable that the intervals between the plurality of discharge units 61 are set so that the plurality of second highly supersaturated regions 12B discharged from the plurality of discharge units 61 do not overlap.

  Although the embodiments of the chemical reaction apparatus have been described above, the present invention is not limited to the above-described embodiments and the like, and various modifications are possible within the scope of the gist of the present invention described in the claims. Improvements are possible.

  Although the number of the discharge parts 61 is one in FIGS. 3-6, multiple may be sufficient. In that case, the flow adjustment member should just be provided in the vicinity of the at least 1 discharge part 61. FIG. Preferably, a flow adjusting member may be provided in the vicinity of each discharge unit 61.

  In FIG. 3 to FIG. 6, one flow adjustment member is provided in the vicinity of one discharge portion 61, but a plurality of flow adjustment members may be provided. For example, both the flow adjusting member 70 shown in FIG. 3 and the flow adjusting member 70A shown in FIG.

  The flow that collides with the flow adjusting member and changes its direction is the upper flow F1 or the lower flow F3 on the basis of the flow F2 toward the discharge unit 61 without colliding with the flow adjusting member in FIGS. A horizontal flow may be used with reference to the flow F <b> 2 toward the discharge unit 61 without colliding with the adjustment member.

2 Seed crystal particle 4 Aggregate 6 Outer shell 10 Chemical reactor 12 High supersaturation region 20 Stirrer tank 30 Stirrer blade 40 Stirrer shaft 50 Baffle 60 Raw material liquid supply pipe 61 Discharge unit 70 Flow adjusting member 71 Wall surface 72 Projection

Claims (5)

A chemical reaction device for precipitating particles in the solution while supplying the raw material liquid into the solution,
A stirring tank containing the solution;
A raw material liquid supply pipe having a discharge section for discharging the raw material liquid in the flow of the solution;
A flow adjusting member for adjusting the flow of the solution on the upstream side of the discharge unit,
The said flow control member is a chemical reaction apparatus which has the wall surface which receives the flow of the said solution toward the said discharge part, and the protrusion which protrudes from the said wall surface.   The wall surface has two linear side edges that are closer to each other toward the discharge section, and is recessed downstream with respect to a plane connecting the two linear side edges, thereby allowing the flow along the wall surface to flow. The chemical reaction device according to claim 1, wherein the chemical reaction device collects toward the discharge unit. A chemical reaction device for precipitating particles in the solution while supplying the raw material liquid into the solution,
A stirring tank containing the solution;
A raw material liquid supply pipe having a discharge section for discharging the raw material liquid in the flow of the solution;
A flow adjusting member for adjusting the flow of the solution on the upstream side of the discharge unit,
The flow adjusting member has a wall surface for receiving the flow of the solution toward the discharge part,
The wall surface has two linear side edges that are closer to each other toward the discharge portion, and is recessed downstream with respect to a plane connecting the two linear side edges, thereby allowing the flow along the wall surface to flow. A chemical reaction apparatus that collects toward the discharge unit.   A method for producing particles, wherein the chemical reaction apparatus according to claim 1 is used to deposit particles in the solution while supplying the raw material liquid into the solution.   The method for producing particles according to claim 4, wherein the solution is an aqueous solution, the raw material liquid contains a nickel salt, and the particles are nickel-containing hydroxide.