JPH07187681A - Method for producing low moisture basic cobalt carbonate - Google Patents

Abstract

(57) [Summary] [Objective] We propose a method for producing basic cobalt carbonate with low water content and good filterability. [Structure] A cobalt salt aqueous solution and an alkali carbonate solution are reacted at a constant temperature of 20 to 80 ° C. while controlling the pH within a predetermined narrow pH range of 7 to 9.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the production of basic cobalt carbonate.

[0002]

2. Description of the Related Art Basic cobalt carbonate is used as a starting material for cobalt oxide or as a recovery means for recovering cobalt from wastewater or the like. Conventionally, alkali carbonate or alkali hydrogen carbonate is added to a cobalt salt solution as described in JP-A-54-131597, page 2, lines 8 to 11 of the specification, and the mixture is stirred together. A method of filtering and washing the precipitate generated by the above, and then drying is performed. At this time, the reaction temperature and the pH at the end of the reaction
It is also possible to improve the filterability to some extent by controlling. However, JP-A-54-13159
The basic cobalt carbonate produced under the condition of 7 also had good filterability and was not a product with a low water content. Removing impurities such as anions resulting from the starting salt from a substance with a high water content and poor filterability by washing with water increases the number of washings, the amount of washing liquid, and the amount of liquid to be filtered. It causes an increase and a longer drying time. This is an important factor that makes the production of basic cobalt carbonate difficult and increases the production cost.

[0003]

In view of the above circumstances, an object of the present invention is to propose a new method for producing basic cobalt carbonate having a low water content and good filterability.

[0004]

Means for Solving the Problems In order to achieve the above object, the present invention continuously supplies an aqueous cobalt salt solution and an alkali carbonate solution to a reaction system at the same time, and the temperature of the reaction system is in the range of 20 to 80 ° C. Is characterized in that the reaction is carried out while controlling the pH to a constant value within a predetermined narrow pH range of 7 to 9, and the predetermined narrow pH range is pH 7 to
It is characterized in that the predetermined pH value within the range of 9 is ± 0.05 to ± 0.1.

[0005]

[Function] Generally, basic cobalt carbonate is said to be dissolved by forming a carbonate complex in a solution containing a high concentration of carbonate ions such as alkali carbonates. In addition, generally, in a precipitation formation reaction in water, precipitation formation occurs. It is said that, when the concentration of the precipitate-forming component at that time does not change rapidly, a fine product that deteriorates the filterability and the water content is not mixed into the formed precipitate. According to the method of the present invention, basic cobalt carbonate having a low water content and good filterability can be obtained by strictly controlling the temperature and the pH value as described in the scope of the claims so that the above precipitation It seems that the rapid change in the concentration of the precipitate-forming component was reduced.

That is, the temperature of the reaction system is kept constant in order to keep the carbonate ion concentration in the reaction system constant, that is, the temperature is kept constant so that the amount of the basic cobalt carbonate complex salt does not change. It keeps the value. When the reaction temperature is 20 ° C. or lower, cooling is generally required in the summer, which causes an increase in manufacturing cost and is not general. Also, 80 ℃
In the above case, hydrolysis and oxidation of the produced basic cobalt carbonate become remarkable, resulting in deterioration of filterability and water content. Therefore, the reaction temperature needs to be 20 to 80 ° C.

The reason why the pH of the reaction system is controlled and maintained at a constant pH of 7 to 9 is the same as the temperature maintenance. However, the pH above the temperature has a great influence on the cobalt complex salt concentration in the reaction system, and the control range of the pH is ±
About 0.05 to ± 0.1 is desirable. Below pH 7,
It is not practical because the amount of cobalt loss in the liquid after the reaction is increased. Further, at a pH of 9 or higher, cobalt hydroxide is produced, which deteriorates both the water content and the filterability.

In the present invention, as the cobalt salt solution to be used, any one of sulfate, chloride, nitrate or a mixed solution thereof is used. The cobalt concentration in the solution used is a concentration below the solubility of each salt at 20 ° C.

The alkali carbonate used is sodium carbonate, ammonium carbonate, or a mixed solution of ammonium hydrogen carbonate and ammonia water. When used, the concentration of alkali carbonate is preferably 0.2 times or more the molar concentration of cobalt in the cobalt salt solution used. At a concentration of 0.2 times or less, since the concentration is low, a large amount of liquid must be sent, which makes it difficult to keep the pH of the reaction system constant, and the reaction system after the formation of basic cobalt carbonate becomes difficult. Liquid volume becomes unnecessarily large.

When ammonium hydrogencarbonate and aqueous ammonia are mixed and used, the amount of ammonia required for converting ammonium hydrogencarbonate to ammonium carbonate is 0.
Aqueous ammonia in an amount of 5 times or more and 2 times or less is mixed with the ammonium hydrogen carbonate solution. This is because it is difficult to control the required pH with ammonium hydrogen carbonate alone and ammonium carbonate is more stable because ammonium carbonate is relatively unstable. The cobalt salt solution and the alkali carbonate solution adjusted as described above are simultaneously and continuously supplied to the reaction system.

[0011]

【Example】

(Example 1) Cobalt sulfate (Wako Pure Chemicals reagent first grade) 223
g in 1 liter of pure water to give a cobalt concentration of 46 g /
l of solution was prepared. Further, 300 g of anhydrous sodium carbonate (Wako Pure Chemicals reagent first grade) was dissolved in 2 liters of pure water to prepare a sodium carbonate solution. 250 ml of pure water was poured into a 3 liter beaker, and the cobalt sulfate solution prepared above was continuously supplied to the beaker with a metering pump at 3 ml / min, and the sodium carbonate solution prepared above was adjusted to pH.
With a metering pump controlled by a controller, the cobalt sulfate solution was intermittently supplied to the beaker at the same time and stirred. During this reaction, the pH in the beaker was controlled to 8.5 ± 0.1, and the temperature was controlled to 50 ° C. with a water bath. This reaction was carried out for 5 hours, and the resulting basic cobalt carbonate was suction filtered using a 5C quantitative filter paper at a constant pressure by an aspirator. The basic cobalt carbonate after suction filtration was washed with 1 liter of pure water at room temperature for repulping, suction filtration was repeated 3 times, and dried in the atmosphere at 80 ° C. for 8 hours.

At the time of drying, the water content determined from the weight difference before and after drying was 23%. The filtration rate measured during filtration after the reaction was 13 m ³ / m ² hr.

(Example 2) 200 g of cobalt chloride (Wako Pure Chemicals Reagent Grade 1) was dissolved in 1 liter of pure water to prepare a solution having a cobalt concentration of 45 g / l. In addition, 300 g of ammonium hydrogen carbonate (Wako Pure Chemicals reagent first grade) was dissolved in 2 liters of pure water, and 287 ml of 25% ammonia water (Wako Pure Chemicals reagent first grade) was added to the solution after dissolution to form ammonium hydrogen carbonate. A mixed solution of ammonia water was prepared. The cobalt chloride solution and the mixed solution of ammonium hydrogen carbonate and ammonia water were reacted for 5 hours at a reaction temperature of 40 ° C. and a controlled pH of 7.5 ± 0.05 using the same apparatus as in Example 1. After the reaction, the same operation as in Example 1 was performed. As a result, the water content of the generated basic cobalt carbonate was 24%,
The filtration rate was 12.5 m ³ / m ² hr.

Example 3 The same solution and reaction apparatus as in Example 1 were used, the reaction temperature was 30 ° C., and the control pH was 8.75 ±.
The reaction was performed at 0.1 for 5 hours. After the reaction, the same operation as in Example 1 was performed. As a result, the water content of the produced basic cobalt carbonate was 40%, and the filtration rate was 10 m ³ / m ² hr.

(Comparative Example 1) 1 liter of an ammonium hydrogencarbonate (Wako Pure Chemicals reagent first grade) solution adjusted to a concentration of 140 g / l was placed in a 2 liter beaker and the pH was adjusted to 6.8 ±.
The temperature was adjusted to 0.1 at 40 ° C. and the mixture of Example 2 was stirred.
800 ml of cobalt chloride solution adjusted to the same concentration as
Was added. After reacting for 30 minutes as it was, it was filtered in the same manner as in Example 1, washed with water, and dried in the atmosphere at 80 ° C. for 24 hours. The reason why the drying time is longer than that in the example is that the drying time was not sufficient in the same time as in the example. As a result, the water content of the generated basic cobalt carbonate was 79%,
The filtration rate was 5 m ³ / m ² hr.

Comparative Example 2 The pH during the reaction was 9.3 ± 0.
Basic cobalt carbonate was prepared by using the same apparatus and apparatus as in Example 1 except that No. 1 was used. The basic cobalt carbonate obtained had a water content of 70% and a filtration rate of 6 m ³ / m ² h
It was r.

[0017]

By the method of the present invention, basic cobalt carbonate having a low water content and a high filtration rate can be produced.

Claims (2)

[Claims] 1. A cobalt salt aqueous solution and an alkali carbonate solution are continuously and simultaneously supplied to the reaction system at a temperature of 2
A method for producing low-basic-cobalt basic carbonate, which comprises reacting at a constant value within a range of 0 to 80 ° C. and controlling a pH within a predetermined narrow pH range of 7 to 9. 2. The predetermined narrow pH range is a predetermined pH value ±
The method for producing a low water content basic cobalt carbonate according to claim 1, which is 0.05 to ± 0.1.