JP2001010817A - Production of copper sulfate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce high purity copper sulfate by immersing copper powder containing Ni as one of impurities into an acid solution to remove Ni contained in the copper powder by dissolving Ni, by dissolving copper powder as filter cake in sulfuric acid and by crystallization to obtain copper sulfate having an Ni grade not larger than a specific value. SOLUTION: Copper powder recovered by electrodeposition from an electrolyte and containing Ni as one of impurities is immersed in an acid solution to remove Ni contained in the copper powder by dissolving Ni. As the acid solution, sulfuric acid solution having a normality not smaller than equivalents to settle the Ni and having the sulfuric acid concentration of 1 wt.% is used. By washing the copper powder before and/or after the immersion into the acid solution, Ni alone can be removed. Copper powder obtained by filtering the acid solution used for the immersion is dissolved in sulfuric acid and then crystallization is carried out to obtain copper sulfate having an Ni grade of <=10 ppm.

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 high purity copper sulfate by efficiently removing Ni from copper powder containing Ni.

[0002]

2. Description of the Related Art Copper sulfate is used as a raw material for agricultural chemicals and plating solutions. In general, such copper sulfate is required to remove copper ions accumulated in the electrolytic solution in the electrolytic copper refining step, since copper deposited on the cathode is about 1% less than copper eluted from the anode. And is manufactured in the copper ion removal step. That is,
Supersaturated copper can be separated in the form of copper sulfate by concentrating and cooling the electrolyte, and the separated copper sulfate can be dried and shipped as a product.

However, in addition to copper ions, the electrolytic solution contains a large amount of impurities eluted and accumulated from the anode and free sulfuric acid of the electrolytic solution. In the above-described method, these impurities are directly mixed into the product. Since most of these impurities are considered to be mainly attached to the copper sulfate crystal surface, the crystallized copper sulfate is dissolved again, and the process of concentrating and crystallizing the same is repeated to obtain copper sulfate with a low impurity quality. That is being done.

However, among impurities, Ni is the most hated impurity in plating of electronic materials and the like.
For use in these applications, for example, Ni grade of 10
It is necessary to lower the grade to about ppm and about 100 times lower than that of ordinary copper sulfate. However,
Since Ni has almost the same behavior as copper and has a large amount of Ni eutectoid with copper in addition to the adhesion to the crystal surface, the method of reducing the amount of Ni by concentration and crystallization is an effective method. I couldn't say it.

There is also a method of separating Ni by pH adjustment. However, since Cu precipitates first and a large amount of Cu precipitates, it is costly to separate Ni by this method. There is a problem that they do not agree from the aspect.

Even when a method such as ion-exchange resin / solvent extraction is used, it is extremely difficult to selectively and effectively remove Ni and copper since they exhibit almost the same separation behavior. For this reason, conventionally, in order to obtain high-purity copper sulfate with a small amount of Ni, it is necessary to repeat the concentration and crystallization process two or more times more than usual copper sulfate,
It was extremely disadvantageous in terms of manufacturing cost, equipment operation rate, man-hours, product yield, etc.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a method for economically producing copper sulfate containing less Ni.

[0008]

In order to solve the above-mentioned problems, according to the present invention, for example, Ni is obtained by immersing an electrolytic copper powder recovered by electrodeposition from an electrolytic solution in an acid. A method of selectively dissolving and removing was used. That is, a copper powder containing Ni as an impurity is used as a raw material, and the copper powder is immersed in an acid solution to form Ni powder contained in the copper powder.
Is dissolved and removed, and after filtration, copper powder is dissolved in sulfuric acid and crystallized to obtain copper sulfate having Ni of 10 ppm or less.

In this method, it is desirable to use, as the acid solution for dissolving and removing Ni, a sulfuric acid solution having an amount equal to or more than an amount capable of fixing Ni and having a concentration of 1% by weight. Further, either before or after immersion in the acid solution, or by removing the Ni component by washing the copper powder with water before and after, so that high-purity copper sulfate is more effectively obtained. can get.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the production of copper sulfate, if a raw material with a low Ni grade is used, copper sulfate with a small amount of Ni mixed into a copper sulfate product in concentration and crystallization should be obtained. However, as described above, it is difficult to prevent Ni from being mixed in the conventional method of directly crystallizing from an electrolytic solution.

Therefore, it is conceivable to use electrolytic copper as a raw material. Since electrolytic copper has a purity of about 99.99%, when used as a raw material, many impurities including Ni have already been separated. However, if the shape of the normal electrolytic copper electrodeposited in the form of a plate is inferior in solubility, cutting is necessary to increase the surface area. For this reason, handling equipment is required and labor is required, and a large amount of air and acid are required for dissolving the cut copper, so that the cost increase due to these can not be ignored.

In order to solve the above-mentioned problems, it is desirable to use powdered or granular electrodeposited copper. With such a shape, it can be relatively easily dissolved with a small amount of air, and handling is easy. But,
On the other hand, in order to obtain powdered or granular electrolytic copper, it is necessary to keep the copper concentration of the electrolytic solution low or to increase the current density. However, under these electrolysis conditions, Ni
Will also increase the likelihood of electrodeposition. It is also true that powdery or granular electrodeposition increases contamination due to entrainment due to an increase in surface area, and as it is, the same problem as in the case of direct crystallization from an electrolytic solution.

Therefore, it has been found that it is effective to remove Ni by washing the obtained copper powder once with an acid. That is, the Ni adhered to the surface of the copper powder is removed with water or a very thin acid, and the Ni deposited inside is washed with an acid enough to dissolve the copper on the surface once.

The higher the acid concentration used for pickling, the better, but as the concentration increases, the elution of Cu in the copper powder increases and the loss increases. Here, in order to selectively remove Ni, the surface of the copper powder is dissolved only by immersing in a small amount of a thin acid solution and left for a while, and then Cu is reprecipitated at the same time as Ni is eluted. I found an effect. By utilizing this effect, it becomes possible to selectively elute only Ni, and it is possible to obtain a copper powder containing little Ni as an impurity. Therefore, high-purity copper sulfate can be produced economically.

[0015]

(Example 1) Cu: 95% by weight, Ni: 0.
100 g of copper powder produced by electrolysis with a quality of 3% by weight
Was added with 500 ml of 1% sulfuric acid by weight and immersed for 4 hours with stirring at room temperature. Thereafter, the mixture was filtered with a 5C filter paper. Subsequently, 500 g of 300 g / l sulfuric acid was added to the precipitate.
and dissolved at a temperature of 80-90 ° C. After almost dissolution, the solution was filtered through a 5C filter paper,
It was concentrated to 0 ml over about 2 hours. After reaching a predetermined liquid volume, the mixture was cooled to room temperature with stirring over 4 hours to separate crystals. The crystals were dried at room temperature and analyzed. As a result, copper sulfate crystals of 4 ppm of Ni were obtained.

The comparison was carried out by changing the immersion time from 1 hour to 24 hours, but it was determined that the Ni concentration of the cleaning liquid reached an equilibrium in about 4 hours, that is, the dissolution was completed. (Example 2) As in Example 1, 100 g of electrolytic copper powder was washed with 1% sulfuric acid at a weight ratio. However, before and after washing, each was washed with pure water (60 ° C., 500 ml) for 30 minutes each, filtered, and then pickled or dissolved. The analytical value after crystallization was Ni 1 ppm, which was the highest purity result.
The analysis of the post-wash solution washed before acid immersion showed that Ni
It was also found that 1 mg / l of Cu and 180 mg / l of copper eluted with negligible loss. Therefore, when water-soluble Ni is attached to the copper powder, it can be effectively separated from copper by washing with water before pickling.

The concentration of the sulfuric acid to be washed is 0.5% to 20%.
%, The results showed that even when the sulfuric acid concentration was increased from 1%, there was no difference in the Ni grade of the obtained copper sulfate, but rather, only the Cu loss to the cleaning solution increased. For this reason, it was confirmed that if the amount of sulfuric acid is equal to or more than an amount capable of fixing Ni as Ni sulfate, a concentration of about 1% that can suppress Cu loss is sufficient. (Comparative example) 300 g to 100 g of the same copper powder as in Example 1
500 ml of sulfuric acid at a concentration of
The mixture was dissolved over 2 hours while blowing at 100 ml / min while heating to ° C. After filtration, it is filtered through a 5C filter paper,
While maintaining the filtrate at 80-90 ° C.,
The mixture was concentrated for about 2 hours until the liquid volume reached 1 l. further,
The mixture was cooled to room temperature over 4 hours while stirring, and the crystals were separated. The crystals were dried at room temperature and analyzed. as a result,
Ni of the copper sulfate was 33 ppm, which was higher than the target, which was insufficient quality. (Conventional example) A conventional method for producing high-purity copper sulfate was carried out. C
Electrolyte 2000 with a concentration of u50 g / l and Ni 15 g / l
The resulting solution was concentrated to 1000 ml at a temperature of 80 ° C. and separated into a solid and a liquid. The Ni grade of the obtained copper sulfate was 196
It was 0 ppm. 1000 ml of this crude copper sulfate crystal
And adjusted to pH 3 at 80 ° C. to neutralize the attached free sulfuric acid. After the solution was filtered, 80
The solution was concentrated at 500C to 500 ml and separated from precipitated crystals by solid-liquid separation. The Ni grade of the copper sulfate at this time was 500 ppm.

Subsequently, by repeating dissolution and precipitation of copper sulfate, Ni-grade copper sulfate of 40 ppm was obtained in the third recrystallization and 1 ppm in the fourth recrystallization.

[0019]

According to the present invention, high-purity copper sulfate containing little Ni can be produced.

Claims (3)

[Claims] 1. A method using a copper powder containing Ni as an impurity as a raw material, dissolving and removing Ni contained in the copper powder by immersing the copper powder in an acid solution, dissolving the copper powder in sulfuric acid after filtration, A method for producing copper sulfate, characterized by obtaining copper sulfate having a Ni grade of 10 ppm or less by crystallization. 2. The method for producing copper sulfate according to claim 1, wherein a sulfuric acid solution having an amount equal to or more than an amount capable of fixing Ni and having a concentration of 1% by weight is used as the acid solution. 3. The method according to claim 1, wherein only the Ni component is removed by washing the copper powder with water before or after immersion in the acid solution or before and after immersion. 3. The method for producing copper sulfate according to item 1.