JPH0625882A - Electrolytic refining method for copper - Google Patents

Abstract

PURPOSE:To stably produce electrolytic copper having decreased pinholes by specifying an electrolysis temp. and the amt. of the org. additives to be added and changing the copper concn., sulfuric acid concn. and nickel concn. of an electrolyte thereby adjusting the sp. gr. of the electrolyte. CONSTITUTION:The electrolysis temp. and the amt. of the org. additives to be added are specified and one among the copper concn., sulfuric acid concn. and nickel concn. of the electrolyte are changed to adjust the specific gravity of the electrolyte to the 1. 250 to 1.263 range in the electrolytic method for the copper at >=240 ampere/m<2> current density. The electrolysis temp. is specified to about 60 to 65 deg.C and the amt. of the org. additives is selected from the ranges of 50 to 100g/electrodeposition copper ton glue, 50 to 100g/ electrodeposition copper ton thiourea and 10 to 30g/electrodeposition copper ton. The adjustment of the copper concn. of the electrolyte is executed by adjusting the degree of removing the copper excessively chemically dissolved from the anode by a decopperization electrolysis method from the electrolyte.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electrolytically refining copper, and more particularly to a method for producing electrolytic copper with few pinholes.

[0002]

2. Description of the Related Art Electrolytic copper pinholes are bubbles formed by air in liquid or gas generated during electrolysis, which adheres to the surface of the cathode and copper is electrodeposited on the periphery as it is. Without electrodeposition, a diameter of about 3 mm as shown in Fig. 1,
It refers to the remaining holes that are about 10 mm deep. The electrolytic solution remains in the pinholes to increase the sulfur content of electrolytic copper and the appearance of the product is deteriorated, so it is desirable that the amount is as small as possible.

The cause of the bubbles causing the pinholes is thought to be mainly due to the entrainment of air in the electrolytic solution circulation pump or the circulation tank, but this has not been clearly determined, and the pump is adjusted depending on the occasion. , Adjustment of liquid supply, supply,
Various measures were taken such as adjusting the drainage temperature. Especially in electrolysis with high current density of 240 amperes / m ² or more, the concentration of copper in the electrolytic solution must be increased in order to prevent insufficient supply of copper ions on the cathode surface. As a result, the viscosity of the electrolytic solution becomes high, the bubbles adhering to the cathode surface become difficult to peel off, and the number of pinholes in the electrolytic copper tends to increase.

Generally, it has been proposed to add a special organic additive to smooth the surface of electrolytic copper (for example, Japanese Examined Patent Publication No. 61-33918), but the problem is that the organic additive is expensive. There was a point.

[0005]

DISCLOSURE OF THE INVENTION The present invention is directed to copper electrolysis in which pinholes are generated on the surface of electrolytic copper under electrolysis conditions where the current density is particularly high, so that the S content of electrolytic copper is not increased. The purpose is to propose a purification method.

[0006]

The copper electrorefining method according to the present invention is a copper electrolysis method in which a current density is 240 amperes / m ² or more, the electrolysis temperature and the amount of an organic additive added are constant, and the copper concentration in the electrolytic solution is constant. , One of the sulfuric acid concentration and the nickel concentration is adjusted so that the specific gravity of the electrolytic solution is 1.250 to 1.
The feature is that it is set to 263.

[0007]

[Function] Electrolytic copper pinholes occur because bubbles in the electrolytic solution are difficult to separate from the cathode surface as described above, and therefore the viscosity of the electrolytic solution is considered to have a large effect. Since it is difficult to measure the temperature continuously and accurately, the specific gravity of the electrolyte is 2
Electrolyte temperature (61.5 ° C.) at 60 amps / m ² and organic additives (80 g glue / copper ton, thiourea 7)
0g / electrodeposited copper ton, abiton 20g / electrodeposited copper ton) was measured under a constant electrolysis condition, and the relationship with the pinhole occurrence rate was investigated, and it was found that the relationship is as shown in FIG. Invented.

If the specific gravity of the electrolytic solution exceeds 1.263, the rate of occurrence of pinholes in electrolytic copper becomes high, resulting in 1.2
When the value is less than 50, the specific gravity of the electrolytic solution must be adjusted to 1.250 to 1.263 because the copper concentration of the electrolytic solution must be adjusted considerably in order to reduce the specific gravity of the electrolytic solution, which is not economical. is there.

If the electrolysis temperature and the type and addition amount of the organic additive are changed during the operation, the relationship shown in FIG. 2 is largely deviated, so that the electrolysis temperature and the addition amount of the organic additive must be constant.

The electrolysis temperature and the type and amount of the organic additive may be selected so as not to cause a problem in the usual electrolysis, but proper values are as follows: electrolysis temperature 60 to 65 ° C., glue 50 to 100 g / electrodeposition Copper ton, Thiourea 50-10
0 g / ton of electrodeposited copper, 10-30 g of abiton / ton of electrodeposited copper.

The specific gravity of the electrolytic solution is adjusted by changing the copper concentration, the sulfuric acid concentration and the nickel concentration of the electrolytic solution. The copper concentration of the electrolytic solution is decopperization of copper that is chemically dissolved excessively from the anode. The degree of removal from the electrolytic solution is adjusted by an electrolytic method or the like. Further, the nickel concentration of the electrolytic solution is adjusted so that the nickel content is removed from the electrolytic solution as nickel sulfate by an electro-evaporation method or the like. The sulfuric acid concentration in the electrolytic solution is adjusted by adjusting the amount of sulfuric acid added.

The specific gravity of the electrolytic solution may be adjusted by adjusting any of the copper concentration, sulfuric acid concentration and nickel concentration of the electrolytic solution.
It is recommended to select the conditions that are usually carried out so as not to worsen the electrolysis situation. It is desirable that the copper concentration of the electrolytic solution is 47 to 51 g / l in electrolysis at a high current density as in the present invention. It is preferable that the concentration of sulfuric acid in the electrolytic solution is high because the bath resistance of the electrolytic solution is lowered, but if it is too high, passivation of the anode and deterioration of the quality of electrolytic copper may occur, so 150 to 210 g / l is desirable. The higher the nickel concentration of the electrolytic solution, the more the bath resistance of the electrolytic solution increases, and nickel sulfate crystals may crystallize out, which may cause problems such as scaling, so the lower the concentration is, the better. It is not clear because the target anode quality, the cleaning solution cost, etc. differ depending on each electrolysis facility, but 17 to 23 g / l is desirable.

[0013]

[Examples] Electrolysis was performed under the following conditions using an anode obtained by processing in a refining furnace and cast on a turntable and a cathode obtained by seed plate electrolysis. In each test (the test period is one month each), the electrolytic temperature, the type of organic additive, the addition amount is constant, and the specific gravity of the electrolytic solution reaches the target value. Was adjusted. Table 1 shows the results of the composition of the electrolytic solution, the specific gravity (each is a one-month average value), and the occurrence rate of pinholes in electrolytic copper.

Electrolysis conditions Electrolysis temperature 61.5 ° C. ± 0.5 ° C. Organic additive addition amount 80 g / electrodeposited copper ton thiourea 70 g / deposited copper ton Abiton 20 g / electrodeposited copper ton Current density 260 amps / m ² Electrolyzer size 5.6m × 1.25m × 1.4m Number of tanks 256 Number of anodes 50 / tank Quality Cu 99.2%, Ni 0.1 to 0.3% Dimensions 1.04m × 1.03m × 35cm Weight 370kg Number of sheets 51 sheets / tank Cathode size 1.07m × 1.03m × 0.7cm Weight 6.6kg Production rate of electrolytic copper 6000 tons / month Distance between poles 105mm

[0015]

[Table 1]

In Table 1, the specific gravity is a value measured at a temperature of 57 to 62 ° C. using a float balance type hydrometer, and the pinhole generation rate is 10 or more pinholes in one sheet of electrolytic copper. It shows the proportion of the number of sheets.

For comparison, Table 1 shows the results of a test in which the specific gravity of the electrolytic solution was out of the scope of the claims of the present invention under the same electrolysis conditions as those of the examples.

From the results shown in Table 1, it is understood that when the specific gravity of the electrolytic solution is out of the scope of the claims of the present invention, the occurrence rate of pinholes in electrolytic copper is high.

[0019]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the pinholes of electrolytic copper are drastically reduced, electrolytic copper without pinholes can be stably produced, and the quality of electrolytic copper can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of electrolytic copper showing a state of electrolytic copper pinholes.

FIG. 2 is a diagram showing the relationship between the specific gravity of an electrolytic solution and the occurrence rate of pinholes.

[Explanation of symbols]

 1 Electroplated copper 2nd class plate 3 Pinhole

Claims (1)

[Claims] 1. In a copper electrolysis method having a current density of 240 amps / m ² or more, the electrolysis temperature and the amount of organic additives added are kept constant, and at least one of the copper concentration, sulfuric acid concentration and nickel concentration of the electrolytic solution is adjusted. The specific gravity of the electrolyte is 1.25
The copper electrolytic refining method is characterized in that it is from 0 to 1.263.