JPS60255632A - Production of nickel hydroxide of high purity - Google Patents

Abstract

PURPOSE:The reaction of an aqueous alkali hydroxide with an aqueous nickel chloride or sulfate is carried out under specific conditions (at a specific pH and residence time) to produce nickel hydroxide of high purity through simple operations. CONSTITUTION:Aqueous sodium hydroxide (pH; 8-9.5, temperature; over 40 deg.C) is charged in the reaction vessel and aqueous nickel chloride (about 50-200g/l concentration) and aqueous sodium hydroxide (about less than 500g/l concentration) are blown into the bottom part of the reactor under stirring, as the pH and temperature stated above are maintained to effect the reaction (residence time of the product; over about 1hr) and the resulting nickel hydroxide is filtered off and dried. In case that nickel sulfate is used as a nickel salt, the pH is kept at 9-10 during the reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing high-purity nickel hydroxide.

[Conventional technology]

Nickel hydroxide is useful for adjusting the concentration of nickel electrolyte during nickel electrolysis or as a raw material for chemical products, catalysts, and the like.

Conventional methods for producing nickel hydroxide include ■) adding an aqueous solution of nickel salt to an aqueous solution of sodium hydroxide, or adding an aqueous solution of sodium hydroxide to an aqueous solution of nickel salt, and 2) adding ammonium ions to an aqueous solution of nickel salt. A method in which the hydroxide is precipitated by adding alkali hydroxide after adjusting the pH to 8.0 or higher (Japanese Patent Publication No. 53-61)
3) Add alkali hydroxide to an aqueous solution of nickel sulfate to make a basic sulfate slurry with a pH of 7 to 10, after removing at least 50% of the aqueous phase of the slurry or replacing it with water. , add alkali hydroxide again to pH11
A method of forming nickel hydroxide by keeping the temperature at ~14 (
JP-A-54-77297) and the like have been put into practice or proposed.

However, the nickel hydroxide obtained by the above method 1) has poor filterability and is therefore oxidized during the filtration operation, making it impossible to obtain a product suitable for use as in the method of the present invention.

The method 2) is said to produce nickel hydroxide with excellent crystallinity and electrochemical stability, but according to the experimental results of the inventor of the present application, the high purity that is the objective of the method of the present invention cannot be obtained. do not have.

In addition, the method 3) has many problems, such as the process being divided into three steps and the operation being complicated, and the reaction with PHII-14 in a strongly alkaline state making it difficult to treat wastewater and the like.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a method for producing high-purity nickel hydroxide (N1(oH)) by solving the above-mentioned problems and using simple operations.

[Means for Solving the Problems] The inventors of the present invention have found that the purity, properties, etc. of the product obtained vary significantly depending on the conditions for producing nickel hydroxide.

The major factors in the production of nickel hydroxide are, first, the pH value when reacting the nickel salt aqueous solution with the alkaline aqueous solution and the reaction method of the aqueous solution, as well as the processing temperature and residence time of the formed precipitate, etc. These factors If these conditions are satisfied, nickel hydroxide with excellent filterability and oxidation resistance and extremely high purity will be produced.

In the method of the present invention, when the raw material prepared by adding an alkali to water is an aqueous nickel chloride solution, the pH is 8.0 to 9.5;
In the case of nickel sulfate aqueous solution, pH9.0-10.0
, to a small amount (200 to 500 ml in the case of reaction vessels 1 to 51) of an aqueous solution maintained at a temperature of +oC or higher, preferably 600 or higher, the above room temperature nickel salt aqueous solution and alkali aqueous solution are simultaneously added, and the PH of the aqueous solution in the reaction tank and While maintaining the temperature, add by blowing into the bottom of the aqueous solution,
It is characterized in that the residence time of the product is 1 hour or more, preferably 7 hours or more.

[Effect]

When the raw material is nickel chloride, the P'H is 8.0 to 9.5) In the case of nickel sulfate, 9.0 to 10.0 is preferable because if the pH is lower than this, precipitation of nickel hydroxide and chlorination occur. This is because some double salts with basic sulfates or nickel hydroxides are formed, and if the pH is higher than this, the formed nickel hydroxide is unstable and easily oxidized, resulting in poor filterability and difficulty in removing alkali metals. This is because it will be insufficient. The reaction temperature is set to 40C or higher, preferably 60C or higher, because below this temperature, the filtration rate of the product is slow.

Since the reaction temperature and the filtration rate of the product are approximately proportional, it is desirable that the temperature be as high as possible, but from the viewpoint of cost, it is practically preferable to set the temperature to 100C or less.

Next, first prepare a small amount of alkaline aqueous solution at a predetermined pH value and medium temperature in a reaction tank, and add an aqueous solution of nickel salt and preferably an aqueous solution such as sodium hydroxide or potassium hydroxide to this to maintain the pH value and temperature. However, the reason why nickel chloride is added by blowing at the same time is that when a nickel chloride aqueous solution of a predetermined concentration is added to a concentrated alkaline aqueous solution as in the conventional method, the reaction between the concentrated nickel chloride aqueous solution and the alkali proceeds locally. This is because, before normal nickel hydroxide crystals are produced, a product partially containing other double salts is formed, resulting in a precipitate with very poor settling and filterability.

It is safer to obtain a high-quality product by using dilute aqueous solutions of nickel salts, i.e., nickel chloride and nickel sulfate, used here, but from a cost perspective, they are only too concentrated. , that is, in the case of nickel chloride, N
1 concentration 50-200 g/l %N for nickel sulfate
It is preferable to use one having a concentration of 50 to 100 g/l in an equivalent amount or less than the equivalent amount to the alkali added at the same time. Nickel salt aqueous solution and alkaline aqueous solution added here (in the case of alkali, preferably 500 g/l or less)
If the nickel hydroxide is too concentrated, the crystal growth of nickel hydroxide will be insufficient, resulting in hydroxide clusters, resulting in a product with poor filterability, oxidation resistance, etc., so care must be taken.

Next, the reason why the nickel hydroxide produced in the reaction vessel is allowed to remain for at least 1 hour, preferably for at least 7 hours, is that the reaction rate for producing the hydroxide is generally fast, so the residence time is usually not a problem, but the present invention According to the experiments of these authors, in the case of the method of the present invention, this is thought to be due to the growth of the generated nickel hydroxide particles, but due to the difference in residence time,
It was found that the filtration rate of the product varied and also contributed significantly to the bulk density of the product. In order to improve the above-mentioned bulk density, this residence time is preferably about 7 hours or more and about 10 hours.

The nickel hydroxide obtained by the method of the present invention has sufficient filtration rate and oxidation resistance as seen in the examples.
In particular, high purity products containing almost no alkali metals, which are avoided as impurities, can be obtained.However, in the process of drying nickel hydroxide, it is relatively difficult to remove adhering water at low temperatures; Care must be taken when drying as it may generate some trivalent hydroxide.

〔Example〕

Examples will be described below.

Example 1 In a beaker with a capacity St, add 400 ml of an aqueous solution at a predetermined pH of 60C, which was adjusted by adding an aqueous sodium hydroxide solution to water.
and while stirring it with a three-one motor, add a nickel chloride aqueous solution containing 50 to 1 bog/l of nickel and 20
0 g/l sodium hydroxide aqueous solution at room temperature using a roller pump, and nickel chloride at 5 to 2 ml per minute.
5m1S The alkali for this is 1.02 to 1.2 respectively.
equivalent amounts were simultaneously added by blowing into the bottom of the beaker, the vessel was tilted to accommodate the product residence time, and the overflow was allowed to spill into another vessel, while the vessel was maintained at 60 U in a water bath. and PH is PH manufactured by Hirama Rika.
The controller turns on the addition of sodium hydroxide.
〇, FF was maintained at a predetermined pH value, and a predetermined amount was allowed to react.

During this time, the residence time of the reaction solution was varied, the resulting slurry was filtered using a vacuum filter, and the filtration rate was measured.

Next, the obtained cakes were subjected to repulp washing 8 times by adding 1 liter of ionized water per 200 g and filtering, and then dried at each SOC for 24 hours and analyzed for major components and major impurities.

The results are shown in Table 1.

As is clear from Table 1, whether the pH value during the reaction is too low or too high, the filtration rate of the slurry product decreases significantly;
Moreover, the content of impurities also increased.

In Tests 2 to 5, products of a somewhat satisfactory purity were obtained, and Test 5, which had a long residence time, had a high bulk density.

Example 2 Using a nickel sulfate aqueous solution as a nickel salt and a potassium hydroxide aqueous solution as an alkali, the amount of nickel salt added and the pH
Nickel hydroxide was obtained in the same manner as in Example 1 except that .

The results are shown in Table 2.

As can be seen from Table 2, test A7, in which the pH value was outside the range of the method of the present invention, had a high alkali metal content and a reduced filtration rate, but in all other cases, high-purity nickel hydroxide was used. Obtained.

Although not specifically shown as an example, the ml (oH) produced by the method of the present invention was placed in a dry analyzer kept at 70C.
Even after being left for 0 days, the solubility in organic acids such as octylic acid did not change, and the oxidation resistance was also excellent.

〔Effect of the invention〕

According to the production method of the present invention, highly pure nickel hydroxide can be obtained with a simple operation.

Applicant: Sumitomo Metal Mining Co., Ltd. 7---・ Agent: Patent attorney Katsunari Donakamura, °1. ．．ノ・″－－ノ

Claims (1)

[Claims] (1) In the method of producing nickel hydroxide from an aqueous solution of nickel chloride or nickel sulfate, when adding alkali hydroxide to water and reacting nickel chloride, the pH is 8 to 9.
．． 5. When reacting with nickel sulfate, pH 9.0-1
An aqueous solution of 0.0 is prepared, maintained at a temperature of 40C or higher, and the above nickel salt aqueous solution and the above alkaline aqueous solution are simultaneously added to the aqueous solution while stirring, and the P of the aqueous solution is
1. A method for producing high-purity nickel hydroxide, which comprises adding hydrogen by blowing into the bottom of the aqueous solution while maintaining the temperature, and the residence time of the product is at least 1 hour.