JPS61106422A - Production of high-purity basic nickel carbonate - Google Patents

Abstract

PURPOSE:To obtain efficiently a titled compd. with a simple operation by adding an alkali hydroxide to the product obtd. by bringing an aq. alkali carbonate soln. and aq. NiSO4 soln. into reaction under specific conditions then filtering the precipitate and subjecting such precipitate to repulp cleaning. CONSTITUTION:The aq. NiSO4 soln. and the aq. alkali carbonate soln. having 8.0-9.0pH are added so as to blow simultaneously said solns. to an aq. soln. which is prepd. by adding an alkali carbonate to water to maintain the same at the same 8.0-9.0pH, holding the soln. at >=40 deg.C and keep stirring the soln. then the soln. is subjected to suction filtration in such a manner that the moisture sticking to the formed precipitate attains <=60wt%. The alkali hydroxide of <=1mol concn. is then added to the precipitate at a ratio of <=1mol with 1mol Ni in the precipitate so as to attain <=200g/l slurry concn. The slurry is then kept at >=40 deg.C and is stirred for about 30min and thereafter the slurry is subjected to the suction filtration so that the moisture sticking to the precipitate attains 60wt%. Such precipitate is subjected to plural times of the repulp cleaning by water then to the final suction filtration so as to attain 60wt% the moisture sticking to the precipitate. The titled compd. is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing high-purity basic nickel carbonate useful for replenishing nickel plating baths, catalysts, and the like.

[Conventional technology]

Conventionally, basic nickel carbonate was produced by adding an equivalent amount of alkali carbonate or sodium bicarbonate to an aqueous solution of nickel sulfate, filtering the resulting precipitate, and washing it with water several times. A common method was post-drying. However, in order to obtain high-purity basic nickel carbonate using this conventional method, it is not only impractical because it is necessary to repeatedly wash the precipitate with water, but also there are limits to the removal of impurities by the water washing purification method. However, it was impossible to obtain a product with high purity.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a method for efficiently producing high-purity basic nickel carbonate by eliminating the above-mentioned drawbacks.

[Means for solving problems]

In order to achieve this objective, the present inventors conducted extensive research and found that various nickel double salts, such as
Focusing on the fact that what seems to be 0・Y N15O-Z N1(OH) always coexists, and these are poorly soluble in water,
Furthermore, it was discovered that the above-mentioned nickel double salt exhibits easy solubility in an aqueous alkali hydroxide solution under appropriate conditions, and the method of the present invention was achieved.

That is, in the method of the present invention, an aqueous solution of sodium carbonate or potassium carbonate is added to water to prepare a small amount of aqueous solution with a pH of 8.0 to 0.0, and this is maintained at a temperature of 40C or higher, preferably 5C or higher, and stirred. A nickel sulfate aqueous solution and the same alkaline aqueous solution as above were simultaneously added to the aqueous solution in a state where it was blown into the bottom of the aqueous solution while maintaining the pH and temperature of the aqueous solution, and the water adhering to the formed precipitate was removed. 60% by weight or less, preferably 0% by weight or less, by suction filtration, and then the precipitate is transferred to another container, and the precipitate is 1 mole or less and 1 mole or less per 1 mole of nickel in the precipitate. Preferably, a sodium hydroxide or potassium hydroxide aqueous solution having a concentration of 0.1 to 0.6 mol is added to a slurry concentration of 200 mol.
g7' is added in an amount of preferably 50 to 100 g/l, and stirred for about 30 minutes at +OC or more, preferably 40 to 6 CI', and then the precipitate is added so that its adhering water content is preferably 60% by weight or less, preferably Φ°0 The precipitate is filtered with suction so that it is about 60% by weight, and the precipitate is repulped and washed with water several times.
It is characterized in that it is carried out so that the amount is less than or equal to % by weight.

[Effect]

In the method of the present invention, a small amount of alkali carbonate is added to water to adjust the pH to a predetermined value (sample 5 is 200 to 50
The conventional method is to simultaneously add a nickel sulfate aqueous solution and the same alkaline aqueous solution as above to an aqueous solution of about 0 ml) maintained at 40C or higher and stirred while maintaining the Ps temperature. For example, when an aqueous alkali carbonate solution is added to an aqueous solution of nickel sulfate at a predetermined concentration, a locally concentrated reaction between the two solutions progresses, and before normal nickel carbonate is produced, a product containing some other double salts is formed. This is because the precipitate has poor sedimentation and filterability, and contains many impurities.

In addition, setting the reaction premises pH in the range of 8.0 to 9.0 is as follows:
This is because if the amount is less than this, the yield of nickel decreases, and if it is more than this, the desired high purity product cannot be obtained.

The reason why the precipitate generated in the first step and the filtration after repulping with alkali hydroxide in the second step are suction-filtered to reduce the adhering moisture to 60% by weight or less is that impurities, especially alkali metals, This is to separate and remove as much as possible.

Repulping the precipitate with alkali in an amount of 1 mole or less and 1 mole or less per 1 mole of nickel in the precipitate;
Preferably, a concentration of alkali hydroxide from 0.1 to 0.6 molar is used and a slurry concentration of 200 g/! The following steps are performed because, as shown in the examples, if the slurry concentration is high or the alkali concentration is too high, a highly pure product cannot be obtained.

The above cleaning with alkali usually only needs to be done once.
Next, repulp washing is performed multiple times using ionized water, each at a temperature of 400°C or higher; however, if the temperature at this time is low,
Care must be taken as impurities are hardly removed.

According to the method of the present invention, So
, Na, etc. can be reduced to 7 to 10 times lower than conventional methods.

By the way, the SO of conventional products is 3000 to 7000 ppm.
.

Na content is approximately 15000 ppm, but the product of the present invention has a Na content of 5o4600 or less, Na 100~+00 @ 1) p
m or less can be stably obtained.

In the final step of washing with water, a similar effect can be obtained by using a centrifugal separator and adding warm water as appropriate during the operation. Although not specifically explained, it is also possible to use baking soda as a raw material in the method of the present invention.

However, when baking soda is used, in order to maintain the pH value of the method of the present invention, it is necessary to use alkali hydroxide in combination, which is not preferable in terms of cost.

〔Example〕

Examples will be described below.

Example 1 500 ml of ionized water was placed in a settling tank, an aqueous sodium carbonate solution was added thereto, the pH was set to 50C, and the pH was adjusted to 50C. Add 1.8 to this while stirring with a three-one motor.
3 tons of mol/l nickel sulfate aqueous solution and the same <1.8 mol/l sodium carbonate aqueous solution were each used with roller pumps (some of the nickel sulfate aqueous solution was added per minute on average), and simultaneously blown into the precipitation tank. During this time, the inside of the container was maintained at 50 C using a water bath, and the pH was adjusted to a predetermined pH value while separately turning off the addition of the sodium carbonate aqueous solution using a PH controller (manufactured by Tetarika). Total amount of nickel sulfate,
reacted.

The entire amount of the slurry thus obtained was filtered using a vacuum filter so that the moisture content of the precipitate was approximately 45% by weight, and the resulting precipitate was divided into NaOH (mol)/Ni (mol) =
0.3 sodium hydroxide aqueous solution to a slurry concentration of 1
After stirring with a three-one motor at 50C for 30 minutes, the precipitate was suction-filtered so that the moisture content of the precipitate was about 50% by weight.

Next, hot water at 50 C was added to each precipitate so that the slurry concentration was 100 g/l, and after stirring for 30 minutes, suction filtration was performed three times, and the moisture content of the precipitates was approximately 50% by weight each time. After performing suction operation until , it was dried and analyzed for major impurities.

The results are shown in Table 1.

Table 1 As is clear from Table 1, as the pH increases, Na,
Although the content of so and so increased, products with high purity exceeding the expected values were obtained in both cases.

Example 2 Basic nickel carbonate was produced in the same manner as in Experiment A1 of Example 1, except that the amount of alkali used to wash the nickel carbonate precipitate was varied, and the main impurities were analyzed. Note that the pH at the time of precipitation formation was 8.0.

The results are shown in Table 2.

Table 2 As can be seen from Table 2, Experiment A6, in which the amount of alkaline cleaning solution did not have a large proportion of nickel, had the least amount of impurities.

From this, it was found that whether the alkali concentration was too low or too high, it had a subtle effect, but satisfactory results were obtained in either case.

Example 3 Basic nickel carbonate was produced in the same manner as in Experiment &1 of Example 1, except that the slurry concentration during alkaline washing was varied, and major impurities were analyzed.

The results are shown in Table 3.

Table 3 As shown in Table 3, as the slurry concentration increases, SO
Although no effect was observed on the slurry, the Na content increased rapidly, indicating that the slurry concentration in the case of alkaline cleaning was limited to 200 g//.

〔Effect of the invention〕

According to the method of the present invention, highly pure basic nickel carbonate can be efficiently produced without any particularly complicated operations, while reducing Na and SO, which are difficult to separate, to 1710 or less compared to conventional products.

Claims (1)

[Claims] (1) While stirring an aqueous solution of alkali carbonate with a pH of 8.0 to 9.0 held at 40°C or higher, add an aqueous solution of nickel sulfate and an aqueous solution of alkali carbonate with a pH of 8.0 to 9.0 simultaneously to the above aqueous solution. It is added to the aqueous solution by blowing it while maintaining the pH and temperature of the mixture, and the resulting precipitate is suction-filtered so that the adhering water content is 60% by weight or less.The precipitate is then transferred to another container, and the Add alkali hydroxide in an amount of 1 mol or less to 1 mol or less of nickel in the precipitate so that the slurry concentration is 200 g/l or less, and stir while maintaining the temperature at 40°C or higher. Suction filtration is performed so that the water content is 60% by weight or less, and then repulp washing is performed with water multiple times at the above temperature, and at least the final suction filtration is performed so that the adhering moisture in the precipitate is 60% by weight or less. A method for producing high purity basic nickel carbonate.