JPH026340A - Production of nickel hydroxide - Google Patents

Abstract

PURPOSE:To continuously produce desired spherical nickel hydroxide in high efficiency by continuously and simultaneously supplying an aqueous solution of a nickel salt, an alkali metal hydroxide and an ammonium ion donor to the reaction system and proceeding the reaction while keeping the temperature and pH of the reaction system at respective specific levels. CONSTITUTION:Nickel hydroxide is produced by reacting (A) an aqueous solution of a nickel salt, (B) an alkali metal hydroxide and (C) an ammonium ion donor according to the following process. The above components (A)-(C) are continuously and simultaneously supplied to the reaction system and the reaction is proceeded while keeping the temperature of the reaction system at a definite level between 20 deg.C and 80 deg.C and keeping the pH at a definite level between 9 and 12. Spherical nickel hydroxide particles having an average particle diameter of 2-50mum are produced by the above process and are continuously taken out of the reaction system.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a novel method for producing nickel hydroxide.

Conventional technology and its problems Nickel hydroxide is an industrial product used for various purposes, but it is particularly suitable for use in non-sintered nickel positive electrodes for alkaline batteries because its particle shape is spherical and A narrow particle size distribution is desired. This is because, by using such nickel hydroxide powder, when filling a metal pocket etc. as the active material of the nickel positive electrode, particles do not fall out from the pores of the pocket and can be packed densely. In addition, when the active material is mixed with a conductive agent and used in the form of a paste, the paste properties such as fluidity are stabilized, resulting in good filling performance and filling rate. This is because the discharge rate is improved and an electrode with excellent performance can be obtained.

However, with conventional nickel hydroxide manufacturing methods, it has been difficult to produce 1 q of products that fully meet the above requirements.

That is, in the conventional method for producing nickel hydroxide for electrodes, an ammonia supplier is added in advance to an aqueous nickel salt solution, and then a nickel-ammonium complex salt is obtained by adding or adding an ammonia supplier, and then a caustic alkali is added to produce nickel hydroxide. Method of causing
No. 71, JP-A No. 61-181074) is well known, but in these methods, 1q of dry nickel hydroxide is large in particle size even if it is in solid or powdered form, so it is usually ground. Therefore, the particles become irregularly shaped powders with fractured surfaces, and the particle size distribution is extremely wide, resulting in a disadvantage that the packing density is low.

Recently, a method has been developed in which nickel salt aqueous solution and caustic alkali are introduced into the same water tank and nickel hydroxide is continuously extracted under certain conditions (Japanese Patent Application Laid-Open No. 6316555, Japanese Patent Application Laid-open No. 63-1
No. 6556) has been proposed, but this method has the major drawback of requiring a long period of one month to stabilize the reaction system. The shape is not spherical, and the particle size i is wide, so the packing density is not necessarily high.

Means for Solving the Problems In view of the above-mentioned current situation, the present inventor has developed a method for producing nickel hydroxide with high efficiency, which has a spherical particle shape, a narrow particle size distribution, and a sufficient packing density. I did a lot of research to find out. As a result, a nickel salt aqueous solution, an alkali metal hydroxide, and an ammosimium ion donor, Mitoma, were continuously and simultaneously supplied to the reaction system, and the reaction was carried out while maintaining the temperature and pH of the reaction system at specific constant values. Shin f': rt! It has been discovered that the reaction system can be stabilized within the range of 11 to 100 liters, and that the desired spherical nickel hydroxide can be continuously and extremely efficiently harvested 1 q without any pulverization process, and the present invention has finally been completed. It was completed.

That is, the present invention provides a method for producing nickel hydroxide by reacting (a) a nickel salt aqueous solution, (b) an alkali metal hydroxide, and (c) an ammonium ion donor. and (c) are continuously and simultaneously supplied to the reaction system, while maintaining the temperature of the reaction system at a constant value in the range of 20 to 80 ° C. and the pH at a constant value in the range of 9 to 12. The present invention relates to a method for producing nickel hydroxide, which is characterized in that the reaction is allowed to progress to produce spherical nickel hydroxide particles having an average particle size of 2 to 50 μm, and the particles are continuously taken out.

Examples of the nickel salt aqueous solution (a) used in the present invention include aqueous solutions of various water-soluble nickel salts such as nickel nitrate, nickel sulfate, and nickel chloride. The concentration of the nickel salt aqueous solution is usually 0.5 to 3.5 m
o It is appropriate to set it to about I/Q.

Further, (b) examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, and the like. Alkali metal hydroxide is usually 1.25 to 10 mol/Q
It is best to use it as an aqueous solution.

(iii) As the ammonium ion donor, aqueous solutions of ammonium salts such as aqueous ammonia, ammonia gas, and ammonium nitrate can be used. In the case of ammonia water, it is usually appropriate to use one with a concentration of about 10 to 28% by weight. In addition, in the case of an aqueous solution of heptane-7nium salt, it is usually appropriate to use one with a concentration of about 3 to 7.5 mol/Q.

In the present invention, it is necessary to continuously and simultaneously supply the above three components (a), (b), and (c) to the reaction system. In this case, (a) (mouth) for the nickel salt aqueous solution
During use of alkali metal hydroxide, 1 mol of nickel salt
It is better to add the ammonium ion donor proportionately so that the amount is between 1.8 and 2.2 mol.
- It is best to add proportionately so that fl has a culm degree of ~1.5 mol. These feed additions to the reaction system are carried out with sufficient stirring, and the addition rate (311, volume of the reaction tank M,
FaJ may vary depending on the shape, etc., but it is best to adjust it appropriately so that the 8il residence time in the reaction system is usually about 0.5 to 5 hours. In addition, "simultaneously" means the particle size of the product, p(-1
This means that the addition rate and ratio of each reactant can be adjusted as appropriate because of the adjustment of wJ, etc.

Moreover, the temperature of the reaction system at this time is maintained at a constant value in the range of 20 to 80°C. Normally, it is best to maintain the temperature at about -2°C in one predetermined direction. Similarly, the pH of the reaction system is maintained at a constant 11n in the range of 9-12. Normally, predetermined value ±0.1
It is best to maintain it at a moderate level.

In the present invention, as described above, three components, nickel salt aqueous solution, alkali metal hydroxide, and ammonium ion donor, are continuously and simultaneously supplied to the reaction system, and the temperature and DH of the reaction system are maintained at a specific constant ( By allowing the reaction to proceed while maintaining the internal temperature, the reaction system can be stabilized in a very short period of time, usually between 10 and 3011.
Spherical nickel hydroxide particles of about 50 μm can be continuously and efficiently taken out due to overflow or the like. The extracted nickel hydroxide is appropriately filtered, washed with water, and dried to produce a product. At this time, in the present invention, since the moisture content of nickel hydroxide before drying is usually as low as about 10 to 15 m% and is spherical, ? The advantages are that the filtration rate is high, the impurity removal efficiency in the water-washed culm is high, and the energy for drying = 1 stroke is small (9).Of course, no pulverization is required.

As mentioned above, the nickel hydroxide produced by 1q according to the present invention has an average particle size in the range of about 2 to 50 μm, and particle size distribution measurement and scanning electron microscopy (VQ) observation revealed that the particle size distribution width is narrow and the shape is homogeneous spherical to ellipsoidal. is early. The particle size and particle size distribution can be varied in various ways by adjusting the addition ratio of the ammonium ion donor, the residence time in the reaction system, the degree of stirring, etc. For example, by increasing the addition ratio of ammonium ion donor within the above range, the particle size can be increased, and by decreasing it, the particle size can be decreased. Further, if the residence time is kept within the above range, the particle size can be increased and the particle size distribution can be narrowed, and if the residence time is shortened, the particle size can be decreased and the particle size distribution can be relatively widened. Furthermore, by increasing the stirring effect, the particle size can be reduced, and by decreasing the stirring effect, the particle size can be increased.

In addition, the spherical nickel hydroxide obtained by the present invention has a small specific surface area of about 10 to 30 m27 g, and an apparent density of about 1.3 to 1.70/ml according to the bulk density LIIS K5101 (18) bulk measurement method). 1 in tapping density
．． Since it has a high content of about 8 to 2.1 g/l, it is extremely suitable as a raw material for positive electrodes for alkaline batteries. Also, since the surface is low, it is easy to work with the plate.

Next, an example of an advantageous embodiment of the method of the present invention will be explained with reference to the drawings. FIG. 1 shows an example of a reaction apparatus that can be used in the method of the present invention. In Figure 1, (1) is a reaction tank equipped with a stirrer, (2) is an inlet for the nickel salt aqueous solution,
(3) is the input port for the ammonium ion supplier, (4) is the input port for the aqueous alkali metal hydroxide solution, (5) is the metering pump, (6) is the pH controller, (7) is the temperature controller, and (8) is the We accept orders for each outlet for nickel hydroxide.

First, an appropriate amount of water is put into the reaction tank (1), and the liquid temperature is maintained at a preset constant value by the temperature controller (7) while stirring. The hydroxide aqueous solution is continuously introduced and added through each inlet (2), (3), and (4) using a metering pump. Among these, the alkali metal hydroxide aqueous solution is
Metering pump (5) so that H is a preset constant value.
It is preferable to introduce it by. The rate of addition of each reactant is
The residence time in the reaction system is adjusted to a predetermined time.

Further, in order to achieve a predetermined residence time, it is preferable to keep each input port and the nickel hydroxide outlet (8) as far apart from each other as possible in the reaction tank. For example, as shown in Fig. 1, each inlet is located at the bottom of one wall of the reaction tank, and the outlet is located at the top of the opposite wall, so that the generated nickel hydroxide can be taken out by overflow. preferable. After the above-mentioned operations are carried out and the reaction system is stabilized, the desired spherical nickel hydroxide produced is continuously taken out, which is appropriately filtered, washed with water, and dried to obtain a product.

& J1 Shi Eri According to the present invention, the following special effects are achieved.

(1) The reaction system can be stabilized in an extremely short period of time, and the desired spherical nickel hydroxide can be obtained continuously and extremely efficiently without any pulverization step.

(2>147) Spherical nickel hydroxide has an average particle size within the range of 2 to 50 μm, and can be controlled in various ways within this range, and a narrow particle size distribution can be obtained. The hanging density can be made sufficiently high.

(3) In addition, since the water content of the nickel hydroxide taken out from the reaction tank is low and it is spherical, the filtration rate is high, the impurity removal efficiency in the water washing process is high, and the energy required for drying is high. The advantage is that it is even smaller than 1.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 In a 10Q reaction tank similar to that shown in Fig. 1, each solution concentration was 2.2 m01 of nickel nitrate aqueous solution.
/Q, sodium hydroxide aqueous solution 6.0 mol/+! I) Hll, O ± 0.1, reaction 811! using a nickel nitrate aqueous solution 4.512/hr and ammonia water 0.37 Q/hr with a constant m pump at a constant rate using 25% by weight ammonia water and 25% by weight ammonia water. The temperature was maintained at a constant value of 50 ± 2°C into the tank under stirring, and at the same time, an aqueous sodium hydroxide solution was added using a constant meter pump linked to the H controller to maintain the set pH (average At a flow rate of 3.IQ/hr), nickel hydroxide was continuously produced.

The addition ratio at this time is, per 1 mol of nickel nitrate.
Ammonia was 0.5 mol, and sodium hydroxide was 1,9 mol. In addition, the residence time in the reaction tank is
It was about 1 hour.

The produced spherical nickel hydroxide was continuously taken out, filtered, washed with water, and dried to obtain a powdered product.

The moisture content of dry nickel hydroxide was 12.3% by booth, making it easy to filter. In addition, the moisture content after drying is
It was 0.3% by weight.

1! The average particle size of the produced product is 6.3 μm,
The particle size distribution is extremely narrow as shown in Figure 2.
there were. Further, its specific surface area was 23.6 m2/g, bulk density was 1.56 g, II, and tapping density was 1.95 G/+111. (A scanning electron micrograph (750x magnification) of the prepared product is shown in Figure 3.

Example 2 In a 1OR reaction tank similar to that shown in FIG. 1, each solution concentration was set to fi! Acid nickel aqueous solution 1.6m
ol/l sodium hydroxide aqueous solution 4.5 mol/(!
and 25% by weight ammonia water, nickel sulfate aqueous solution 1.5Q/r1r, ammonia water 0.2112/h
The water was added at a constant rate of r to the stirred tank maintained at a constant pH of 10.0 ± 0.1 and reaction temperature of 50 ± 2°C using a metering pump, and at the same time water was added using a constant m pump linked to a DH controller. An aqueous sodium oxide solution was added to maintain the set pH (average flow rate 0.979/hr) to continuously generate nickel hydroxide.

The addition ratio at this time is, per 1 mol of nickel sulfate,
Ammonia was 1.2 mol+ and sodium hydroxide was 1.82 mol. Further, the residence time in the reaction tank was about 3 hours.

The produced spherical nickel hydroxide was continuously taken out, and was appropriately filtered, washed with water, and dried to obtain a powdered product.

The moisture content of the nickel hydroxide before drying was 11.5% by volume, making it easy to filter. In addition, the moisture content after drying is
It was 0.48%.

The average particle size of the obtained product was 13.8 μm, and the particle size distribution was fairly narrow as shown in FIG. In addition, its specific surface area is 22.1 m2/q, bulk density is 1.68 q/ml, and tapping density is 2.0
It was 20/+111. A scanning electron micrograph (750x magnification) of the obtained product is shown in FIG.

Comparative Example 1 2.2rTIOI/Q1 in 59 batch-type reaction vessels
4M nickel aqueous solution 19 and 25% ammonia water 0
．． 55Q was mixed with stirring, 1.45Q of 6.0 mol/Q sodium hydroxide aqueous solution was added with stirring, and 1.
Stir for an hour to form nickel hydroxide.

The generated nickel hydroxide was filtered, washed with water, and dried.
Since it became solid, it was crushed to obtain powdered nickel hydroxide. The obtained nickel hydroxide had an irregular shape with a fractured surface and a wide particle size distribution.

The specific surface area of the comparative amount obtained was 83 m"/g, the bulk density was 1.06 q/ml, and the tapping density was 1
．． It was 25G/+111. A scanning electron micrograph (750x>) of the comparative amount obtained is shown in FIG.

Comparative Example 2 Nickel hydroxide was produced in the same manner as in Example 1, except that aqueous ammonia was not used in Example 1. However, the addition ratio at this time was 2.05 mol of sodium hydroxide to 1 mol of nickel nitrate.

The generated nickel hydroxide was filtered, washed with water, and dried.
Since it became solid, it was crushed to obtain powdered nickel hydroxide. The obtained nickel hydroxide had an irregular shape with a fractured surface and a wide particle size distribution.

The specific surface area of the comparative amount of 1q was 78 m2/g, the bulk density was 1.140/In+, and the tapping density was 1.380/1111. The obtained comparative amount of scanning electronics 1! A mirror photograph (750x) is shown in Figure 6.

[Brief explanation of the drawing]

FIG. 1 shows an example of a reaction apparatus that can be used in the method of the present invention. In Figure 1, (1) is a reaction tank equipped with a stirrer, (2) is an inlet for an aqueous nickel salt solution, (3) is an ammonium ion donor, and (4) is an aqueous alkali metal hydroxide solution. (5) is the metering pump, (
6) DH controller 1~roller (7) Temperature controller (8) indicates the nickel hydroxide outlet. Second
The figure is a graph showing the particle size distribution of spherical nickel hydroxide obtained in Examples 1 and 2. Figure 3 shows a scanning electron micrograph (75cm) of the spherical nickel hydroxide obtained in Example 1.
0 times). FIG. 4 is a scanning electron micrograph (750x magnification) of the spherical nickel hydroxide obtained in Example 2. FIG. 5 is a scanning electron micrograph (750 times magnification) of the nickel hydroxide obtained in Comparative Example 1. FIG. 6 is a scanning electron micrograph 75 of nickel hydroxide obtained in Comparative Example 2.
0 times). (above) Diagram Diagram Diagram 14 Procedural Correction Words and Behaviors (pm)

Claims (1)

[Claims] (1) In producing nickel hydroxide by reacting (a) nickel salt aqueous solution, (b) alkali metal hydroxide and (c) ammonium ion donor, the above (a), (b) and (c) ) are continuously and simultaneously supplied to the reaction system, and the reaction proceeds while maintaining the temperature of the reaction system at a constant value in the range of 20 to 80°C and the pH at a constant value in the range of 9 to 12. A method for producing nickel hydroxide, which comprises producing spherical nickel hydroxide particles having an average particle size of at least 2 to 50 μm, and continuously taking out the particles.