JPH07165428A - Production of nickel hydroxide particle - Google Patents

Abstract

PURPOSE:To obtain nickel hydroxide particles which are very desirable as a not-sintered anode in an alkali cell because they have a relatively narrow size distribution, high filling density and substantially spherical shapes. CONSTITUTION:An aqueous nickel salt, aqueous ammonia and aqueous alkali hydroxide are continuously fed in a certain proportion into a reaction tank provided with a filtration function. After the feedstock reaches a certain volume in the reactor, the liquid medium is continuously filtered off through the filtration function to effect reaction, as the reaction volume is kept almost constant under stirring. After prescribed amounts of the reaction system are added, the feed of the reaction mixture is stopped, the particles formed are taken out and separated from the reaction system to obtain fine particles of nickel hydroxide in the shape of balls or eggs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing nickel hydroxide particles, and more particularly to a method for producing nickel hydroxide particles having a controlled particle size distribution and high packing density, which are preferably used in alkaline batteries and the like. Regarding

[0002]

2. Description of the Related Art In many cases, nickel hydroxide particles used in non-sintered nickel positive electrodes of alkaline batteries are mixed with a paste-like conductive agent or the like to prepare a nickel hydroxide particle-containing paste.
It is used as a strike by filling the metallic pocket of the positive electrode. In such a use, the nickel hydroxide particles are preferably spherical particles having a good packing property and packing rate or a shape close thereto, and those having a smooth surface with a uniform particle size are advantageously used. To be Such nickel hydroxide particles having a high packing density are desirable industrially and practically because they can obtain a high utilization rate and discharge rate of the active material.

Therefore, methods for producing such nickel hydroxide particles have been widely studied and proposed. For example, JP-B-53-6119, JP-A-56-143671, and JP-A-61-181074 disclose a method for producing nickel hydroxide from an aqueous solution of nickel complex ammonia and an aqueous solution of alkali hydroxide. Have been described. However, the nickel hydroxide obtained by this method must be crushed before use, and the crushed powder has a wide particle size distribution, and its shape is indefinite and its packing density is low. Further, JP-A-63-16555 and JP-A-63-16556 describe a method for producing nickel hydroxide by continuously introducing a nickel salt aqueous solution and an alkali hydroxide aqueous solution into a reaction vessel under constant conditions. is suggesting. However, this method has a drawback that it takes a long period of time, for example, one month to stabilize the reaction system.

Further, in Japanese Patent Application Laid-Open No. 2-6340, a nickel salt aqueous solution, an alkali metal hydroxide and an ammonium ion supplier are continuously supplied to a reactor, and a reaction mixture is discharged from a reaction tank. The reaction was carried out by keeping the reaction system at a constant temperature in the range of 20 to 80 ° C. and the pH at a constant value in the range of 9 to 12 while keeping the reaction system at a constant volume by overflowing. A method for producing nickel hydroxide particles is described, which proceeds to continuously produce spherical nickel hydroxide particles. However, this method has a problem that the reaction liquid supply balance and p
If the H value changes even slightly, the number of fine particles becomes insufficient,
Alternatively, there is a drawback that it is difficult to stably produce particles having a high packing density because only fine particles are generated.

[0005]

DISCLOSURE OF THE INVENTION The present inventors
As a result of intensive research to find a method for producing nickel hydroxide particles having a smooth particle surface and a high packing density, a practically desirable manufacturing method was found. Therefore, an object of the present invention is to provide a method capable of industrially more advantageously producing fine, substantially spherical fine nickel hydroxide particles used for a positive electrode such as a non-sintered alkaline battery.

[0006]

That is, according to the present invention, a nickel salt aqueous solution, an ammonia water and an alkali hydroxide aqueous solution are simultaneously and continuously supplied at a constant ratio to a reaction tank having a filtering function, and the reaction system is After the volume reaches a predetermined volume, the medium solution in the reaction vessel is continuously filtered off by the filtration function, and the reaction is carried out under stirring conditions while keeping the volume of the reaction system almost constant. After the addition of a predetermined amount of, all the reaction solution supply is stopped, the formed particles are taken out from the reaction system and separated, and a method for producing spherical or egg-shaped fine nickel hydroxide particles is provided. It is a summary.

The nickel salt used in the method of the present invention is
The salt is not particularly limited as long as it is a salt that is soluble in water, but normally, easily soluble mineral acid salts such as nickel sulfate, nickel nitrate and nickel chloride are preferably used. Generally, these nickel salts are adjusted to an aqueous solution concentration of about 0.5 to 3.5 mol per liter (L) and then used in the reaction. Further, the amount of nickel salt supplied to the reaction vessel (container) is in the range of 2 to 20 mol per unit volume (1 L) of the constant volume of the reaction system, and the size of the nickel hydroxide particles to be obtained, It is selected according to the reaction temperature and other conditions. This amount is delivered in 2 to 30 hours.

As the concentration of the ammonia water supplied to the reaction vessel, for example, an aqueous solution having a concentration of 0.5 to 20 molar is conveniently used. The amount of ammonia water supplied to the reaction tank is in the range of 0.2 to 4.0 mol per mol of nickel salt. If the amount of ammonia supplied is less than 0.2 mol, ungrown particles are likely to be formed, and if it is more than 4.0 mol, ammonia loss increases, which is disadvantageous. The preferred feed amount is 0.5 to 3.0 mol. This ammonia water may be supplied to the reaction system alone, but may be mixed with the nickel aqueous solution to be supplied in a predetermined ratio and supplied.

Alkali hydroxide is added in an amount of 1.6 to 2.6 mol per mol of nickel salt. 1.6
If the amount is less than the molar amount, unreacted nickel increases, which is not preferable. The preferred addition amount is 1.8 to 2.4 mol. Typical alkali hydroxides are sodium hydroxide and potassium hydroxide. This alkali hydroxide is usually supplied to the reaction system as an aqueous solution of 2 to 18 mol per liter. In this case, in the present invention, there is an advantage that it is not particularly necessary to control the pH of the reaction system.

In the method of the present invention having the above constitution, the medium liquid of the reaction system can be continuously filtered off by the filtration device provided in the reaction tank itself to keep the volume of the reaction system substantially constant. is important. The control of the volume of such a reaction system is performed by a method in which only the reaction medium solution is withdrawn through a filter material without overflowing the reaction system solution containing the reaction product. . When the filtration efficiency of the filter medium is lowered, an inert gas is back blown to the filter medium.
Let it be played. Further, the method of the present invention is preferably carried out under stirring conditions of the reaction system at a constant temperature within the range of 20 to 80 ° C., for example, when the reaction is carried out while maintaining the temperature at 50 ° C., ungrown particles Substantially free of 3 to 50 μm
Practically desirable spherical or oval nickel hydroxide particles having an average particle size of the order can be obtained.

The medium liquid of the reaction system in the method of the present invention is withdrawn through a filter, and it is important that such filter is alkali resistant. Examples of such filter include: Representative examples include woven or non-woven fabrics made of chemical fibers such as polyethylene and polypropylene, and porous hollow fiber membranes. The mesh size of the filter medium has a nominal pore size of 3 in relation to the target particle size of nickel hydroxide particles.
It is desirable that the particle size be ˜5 μm or less, and industrially, one having a relatively large pore size is advantageously used, but it is appropriately selected according to the desired particle size. If the nominal pore size exceeds 5 μm,
It is not practical because grown particles that become a product are removed, and if it is too small, operability is deteriorated, which is not preferable.

The medium liquid is subjected to natural filtration or suction filtration in a state where such a filter material is brought into direct contact with the liquid in the reaction tank. For example, a filter material may be attached to the outlet formed on the wall of the reaction tank to perform natural filtration, or a filter material may be attached to the tip of the cylinder communicating with the suction device to deeply immerse it in the liquid of the reaction system. Good. Filtration of such a medium liquid does not substantially require a back blower with a filter having a large filtration area, but the filter is clogged and the filtration rate is lowered, so that the volume of the reaction system becomes almost constant. If you can not keep it, back blow
Is reproduced. In the method of the present invention, the filter material to be suction-filtered and back-blown usually uses a reinforcing net for compensating for the insufficient strength. There is no limitation on the method of attachment to the net, and for example, a so-called leaf filter in which a metal mesh or the like is attached to a frame made of metal or synthetic resin and a bag-shaped filter cloth is covered is advantageously used. Further, in order to keep the liquid volume in the reaction system almost constant, a liquid level detection sensor is used, and the feedback from the controller is carried out from there, and the filtration and the operation of the back blower solenoid valve are automatically performed. And it is convenient to make it efficient.

The back blower for regenerating the filter material can inject an inert gas into the reaction system from the suction side to release the nickel hydroxide particles fitted in the eyes of the filter material into the reaction system. . With such a simple short-time back blow, the filter material is effectively regenerated. The time required for the back blow is usually about several seconds. Further, the inert gas used for the back blow may be a gas that does not react with nickel salts and alkalis, and for example, air from which an inert gas such as nitrogen gas or argon gas or carbon dioxide gas has been removed. Is advantageously used in practice.

When the reaction is continued in this way, the nickel hydroxide particles formed in the reaction vessel grow and grow continuously, so that it becomes gradually difficult to stir the reaction system. In the present invention, the reaction is terminated before such a state is reached.
In the batch reaction of the present invention, the amount of nickel salt supplied at the end of the reaction is 2 to 20 mol per liter of the reaction system, although the amount varies depending on the desired particle size of the nickel hydroxide particles and the selection of the reaction conditions. If it exceeds 20 mol, stirring of the reaction system will be hindered and desired nickel hydroxide particles cannot be obtained, which is not preferable. If it is less than 2 mol, the operation efficiency is low and it is extremely disadvantageous.

In carrying out the method of the present invention, an appropriate amount of water, for example, about 20 to 99% of the volume of the reaction tank, or, for example, 3.0 mol or less of alkali, ammonia, or alkali salts is added to the reaction tank in advance. It is practical to add an aqueous solution containing ## STR3 ## and is suitable for the reaction of the present invention. As the liquid to be added at the beginning, the medium liquid taken out in the method of the present invention can be conveniently used.

In the method of the present invention, an aqueous solution of nickel salt, aqueous ammonia and an aqueous solution of alkali hydroxide are continuously added to the reaction tank at a predetermined supply rate, and the reaction system is stirred and reacted by a stirrer or the like. System temperature 20-80 ℃
The temperature is maintained at a predetermined constant temperature within the range, and the amount of the reaction liquid is always maintained constant by the filtration device provided in the device. By satisfying these reaction conditions, spherical or egg-shaped nickel hydroxide particles having excellent particle conditions can be efficiently obtained. According to the method of the present invention, nickel hydroxide particles having an average particle diameter of 3 to 50 μm and a tap density of 1.9 to 2.2 g / ml can be produced with a high production amount of about 0.1 to 2 kg per liter of a reaction vessel, Moreover, since it can be manufactured in a much shorter time than the conventional method, it is industrially extremely advantageous. For example, in the case of producing nickel hydroxide particles having a high packing density in a container having the same reaction volume, compared with the overflow method of JP-A-3-252318, which is said to have good productivity, it takes about 1 hour at the same time. ~ 15 times the amount of particles can be obtained.

In the production of the nickel hydroxide particles of the present invention, a small amount of another metal, for example, a hydroxide of a metal such as cobalt, zinc, cadmium, barium or lithium may be combined with nickel depending on the purpose of application. Can be included. In that case, according to the method of the present invention, it is preferable to add a water-soluble salt solution of these metals to the reaction system together with the nickel salt aqueous solution.

[0018]

The method of the present invention is easy to operate, contains substantially no ungrown nickel hydroxide particles, and has a high packing density as a non-sintered nickel positive electrode for alkaline batteries having a relatively narrow particle size distribution. The nickel hydroxide spherical particles can be obtained very efficiently.

[0019]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Example 1 A filter cloth made of polypropylene woven cloth having a nominal hole diameter of 3 to 5 μm (effective filtration area of about 4 c
250 cc of water was placed in a reaction vessel having a capacity of 500 cc in which a filter equipped with m ² ) was inserted, and this was heated to 50 ° C. While stirring this warm water, 2 mol of nickel sulfate aqueous solution in 1 L, 15 mol of ammonia aqueous solution in 1 L, and 6 mol in 1 L were mixed.
1.85 ml / molar sodium hydroxide solution
Min, 0.62 ml / min and 1.20 ml / min feed rates were continuously added to the reaction vessel. When the volume of the reaction system reached 400 cc, filtration of the medium liquid by a filter was started so as to maintain this liquid amount. About 18 hours later, when the addition of 2 L of the nickel sulfate aqueous solution was completed, the supply of all reaction solutions was stopped.

In this reaction, about 10 hours after the start of the reaction, the efficiency of filtering out from the filter decreased, and the volume of the reaction system could not be kept constant. Therefore, back-blowing was performed every about 10 minutes for 5 seconds to filter. The cloth was regenerated. During the back blow, the reduced pressure was temporarily released and nitrogen gas was spouted into the reaction vessel for 5 seconds.
When 2 L of an aqueous solution containing 2 mol of nickel sulfate was supplied, supply of each reaction solution and filtration of the medium solution were stopped. Then, the particles in the container were separated by filtration, washed with water and dried to obtain 0.38 kg of nickel hydroxide particles. The particles obtained were all spherical or similar in shape, had an average diameter of about 17.8 μm, and had a tap density of 1.93 g / ml.

Example 2 The same as Example 1, but 600 cc of the liquid filtered off by suction in Example 1 was placed in a 1 L reaction vessel equipped with a filter cloth having a filtration area of 16 cm ² , and 1 L was added thereto. 15.0 ml / each of a mixed aqueous solution containing 2 mol of nickel sulfate, 0.05 mol of cobalt sulfate and 0.1 mol of zinc sulfate, 1 mol of an aqueous solution of 15 mol of ammonia and 1 l of an aqueous solution of 6 mol of sodium hydroxide. Min, 4.5 ml / min and 10.75 ml / min feed rates were added continuously to the reaction vessel. Meanwhile, the temperature of the reaction system was kept at 50 ° C. and the reaction was continued under stirring conditions. Three minutes after starting the supply of each reaction solution, the volume reached 700 ml,
From that point, the medium solution was filtered off to keep the volume of the reaction system constant. During the reaction, back blow for about 5 seconds every 10 minutes.
Was carried out in the same manner as in Example 1.

Approximately 5.5 hours after the start of the reaction, the supply of each reaction solution was stopped when 5 L of the metal aqueous solution containing nickel sulfate was supplied, and the formed particles were separated by filtration, washed with water and dried to obtain 1 kg of nickel hydroxide particles. Obtained. The obtained particles had an average diameter of 11.5 μm and a tap density of 2.10 g / ml. The obtained nickel hydroxide particles were substantially spherical and easy to handle as powder.

Example 3 In a 1 L reaction vessel having the filtration device used in Example 2,
600 cc of aqueous solution containing 0.07 mol of sodium hydroxide, 1.5 mol of ammonia and 0.4 mol of sodium sulfate in 1 L.
2 mol of nickel sulfate per liter, 0.05
Mixed aqueous solution containing 1 mol of cobalt sulfate and 4.0 mol of ammonia, 1 mol of zinc sulphate and ammonia per liter
15.0 ml / min and 1.5 mol of a mixed aqueous solution containing 5.0 mol and 6 mol of sodium hydroxide aqueous solution per liter, respectively.
It was continuously added to the reaction vessel at feed rates of ml / min and 11.1 ml / min. Meanwhile, the temperature of the reaction system was kept at 50 ° C. and the reaction was continued under stirring conditions. Three minutes after starting the supply of each reaction solution, the solution amount reached 700 ml, and from that point, the medium solution was filtered off by suction with a filtration device to keep the volume of the reaction system constant.
During the reaction, backblowing was performed about every 10 minutes for about 5 seconds.

When 5 L of the aqueous solution containing nickel sulfate was supplied, the supply of each reaction solution and suction filtration were stopped, and the particles of the reaction system were separated by filtration, washed with water and dried to obtain 1 kg of nickel hydroxide particles. . The obtained nickel hydroxide particles have a spherical shape or a shape close to that, and the average particle size is 1
It was 0.5 μm and the tap density was 2.12 g / ml, and it was easy to handle as a powder.

Example 4 In Example 3, the filtration area of the filter cloth of the filtration device was 60 cm ^2.
Then, the medium solution was continuously filtered off by suction without backblowing to keep the volume of the reaction system constant. The reaction solution and its supply were operated in the same manner as in Example 2, and when 5 liters of the nickel sulfate-containing aqueous solution had been supplied, the supply of each reaction solution was stopped and the extraction of the solution was stopped. Then, the nickel hydroxide particles in the reaction vessel were filtered off, washed with water and dried to obtain 1 kg of a product. The obtained nickel hydroxide particles had a substantially spherical shape or a shape close thereto and were easy to handle as powder. The average particle size was 10.2 μm and the tap density was 2.08 g / ml.

Example 5 A nominal hole diameter of 0.15 μm was provided at the tip of a pipe communicating with a suction device.
Filtration area with polyethylene porous hollow fiber membrane
A m ² filter was inserted and fixed in a reaction vessel having a volume of 30 liters. 18 L of a liquid having the same composition as in Example 3 was placed in this reaction vessel and heated to 50 ° C., and a mixed aqueous solution containing 1.5 mol of nickel sulfate, 0.0375 mol of cobalt sulfate and 3.0 mol of ammonia per 1 L, was added thereto. 1.5 L of a mixed aqueous solution containing 0.75 mol of zinc sulfate and 5.0 mol of ammonia and 6 mol of sodium hydroxide solution per 1 L, respectively.
/ Min, 0.15 L / min and 0.86 L / min feeding rates were added continuously with stirring.

One minute after the start of supplying the reaction solution, the filter was operated so as to keep the amount of the solution constant. The filter is
The hollow fiber membrane was regenerated by back-blowing for 5 seconds every 10 minutes.
When 210 liters of the solution containing nickel sulfate was added (2.3 hours), the supply of each reaction solution was stopped, stirring, heating, and suction filtration of the solution were stopped. The produced particles in the reaction vessel were filtered, washed with water and dried to obtain 31.5 kg of nickel hydroxide particles. The particles were spherical or oval-shaped.
The average particle size of the particles was 10.8 μm, and the tap density was 2.00 g / ml.

COMPARATIVE EXAMPLE 1 In Example 3, except that a pipe having no filter attached at the tip end thereof was placed in the reaction vessel and the liquid containing nickel hydroxide particles was withdrawn from the reaction system so that the amount of the reaction liquid was kept almost constant. Was operated in exactly the same manner to produce nickel hydroxide particles. When the supply of 5 L of the nickel sulfate-containing aqueous solution was completed, the supply of each reaction solution was stopped. The produced particles in the reaction vessel were filtered off, washed with water and dried to obtain 0.12 kg of nickel hydroxide particles. Its average particle size is 9.9 μm, tap density is 1.25 g / ml
Met. The total amount of nickel hydroxide particles extracted from the reaction system was 0.88 kg, and the shape was spherical or oval, but the average particle size was 9.7 μm and the tap density was 1.25 g / ml.
Met.

[0029]

INDUSTRIAL APPLICABILITY The method of the present invention is excellent in operability and productivity, and the produced nickel hydroxide particles are spherical or egg-like, have a relatively narrow particle size distribution, and have a high packing density and are suitable for alkaline batteries. It is extremely useful as a non-sintered nickel positive electrode and has high industrial utility.

Claims (5)

[Claims] 1. A reaction vessel having a filtration function is supplied with nickel salt aqueous solution, ammonia water and alkali hydroxide aqueous solution simultaneously and continuously at a constant ratio, and after the volume of the reaction system reaches a predetermined volume, By the filtration function, the medium solution in the reaction vessel is continuously filtered off, the reaction is carried out under stirring conditions while keeping the volume of the reaction system almost constant, and after adding a predetermined amount of each of the feed solutions, all A method for producing fine spherical or egg-shaped nickel hydroxide particles, characterized in that the supply of the reaction liquid is stopped, and the formed particles are taken out from the reaction system and separated. 2. Ammonia and alkali hydroxide, which are continuously supplied to the reaction tank at a constant ratio, are in a range of 0.2 to 4.0 mol and 1.6 to 2.6 mol, respectively, relative to 1 mol of the nickel salt. The method described in. 3. The method according to claim 1, wherein the supply of the reaction solution is stopped within a range of 2 to 20 mol of nickel salt per liter of the volume of the reaction system which is kept constant. 4. The method according to claim 1, wherein the filtration function has a mechanism for regenerating the filter medium by a back blower if necessary. 5. The method according to claim 1, wherein a small amount of at least one aqueous solution selected from the group consisting of cobalt, cadmium, zinc, lithium and barium is continuously added to the reaction system together with the aqueous nickel salt solution.