JP2000073196A - Production method of electrolytic copper - Google Patents

Abstract

(57) [Problem] To perform electrolysis at a current density of 500 to 1000 A / m ² and obtain a grade of As <5 ppm, Sb <4 ppm,
Electrocopper with Bi <2 ppm, Pb <5 ppm, and S <15 ppm is produced by electrolytic refining or electrolytic sampling. SOLUTION: In a high current density electrolysis method employing bubble stirring, bubbles are discharged from a nozzle hole 4 of 1.5 mm or less from a lower position at least 10 cm away from lower ends of electrodes 1 and 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing electrolytic copper by electrolytic refining or electrolytic extraction.
Electrolytic refining is performed to purify anode blister copper obtained by casting blister copper melted by a converter. The current status of electrolytic copper production by electrolytic refining in Japan is "resources and materials" 1.
993. vol. 109. No. 12 (non-ferrous smelting and refining). On the other hand, electrowinning is performed when adjusting the copper concentration in the electrorefining step, or when leaching ore with an electrolysis tail solution. For example, an operation example of the applicant's electrolytic refining is shown on page 951 of the same journal.
The current density in many electrolytic factories is about 200 to 300 A / m ^{2 for} both electrolytic refining and electrolytic sampling, and the current efficiency is about 95 to 99%.

[0002]

2. Description of the Related Art The importance of increasing the current density in a copper electrolysis process is widely known. However, when the current density is increased, the anode becomes inactive and the electrodeposition at the cathode becomes poor. Phenomenon appears. As a countermeasure, it has been proposed to circulate the electrolyte at a high speed with a pump (resources / materials 97, "material processing" (Sept. 23-25, 1997, Sapporo), pp. 17-20).

[0003] A method for producing high quality electrolytic copper with high current density proposed in US Patent No. 3,875,041 for both electrolytic refining and electrowinning is to continuously agitate the electrolytic solution with bubbles on the cathode surface. About the method. According to the description in this specification, a method of stirring an electrolytic solution with a gas has been conventionally used. However, since the electrolytic solution cannot be sufficiently convected and the current density cannot be increased, (a) (B) Insulating baffles are provided on both sides of the anode in the vertical direction; (c)
It has been proposed to release plate-like bubbles into the anode-cathode gap. As a result, the current density was 20 to 30 ASF (216 to 3 ASF).
24 A / dm ² ), and the current efficiency is 62 to 70% (Table II,
Examples 1 to 4) have been obtained.

[0004]

The internal volume of the electrolytic cell shown in Table 2 in "Non-Ferrous Smelting No.", page 951, is about 9 m ³ per cell, and the number of cells in the electrolytic factory is 509. Then, the total internal volume becomes about 4600 m ³ . If a method of increasing the current density by circulating the entire electrolytic solution with a pump is adopted in an electrolytic plant, the pumping capacity for circulating at an appropriate flow rate becomes extremely large, which is not practical.

On the other hand, the agitation method using bubbles proposed in US Pat. No. 3,875,041 can be said to be an excellent method in that the whole liquid does not flow at high speed by a pump. However, since the current efficiency at which a good electrodeposition surface can be obtained is 70% or less, it cannot be said that the operation is performed with sufficiently high current efficiency.

The operating conditions of an electrolytic plant in Japan are such that the current efficiency is as high as 95% or more, but the current density is 300 A / m ^2.
Productivity is not enough because it is suppressed to the extent. Accordingly, the present invention has been made in view of these circumstances, and provides a high-productivity electrolytic refining or extraction operation method for producing high-quality electrolytic copper with higher current efficiency by improving the bubble stirring method. Aim.

[0007]

Means for Solving the Problems The present inventor conducted an experiment of the bubble stirring method using a transparent plastic tank and observed the generation state of the bubbles. As a result, the position where the bubbles were released into the electrolyte was close to the electrode. It was found that the generation rate of bubbles was too high, and the electrolysis results were not excellent. The present invention floats air bubbles along these electrode surfaces in an electrolytic solution in which an anode made of blister copper is disposed at a position facing the cathode, and discharges the air bubbles from the side edges of the electrodes to the outside of the electrode surface. In a method of producing electrolytic copper for performing electrolysis while suppressing the occurrence of the electrolysis, the air bubbles are discharged from a nozzle hole having a diameter or a maximum dimension of 1.5 mm or less from a position 10 cm or more away from a lower end of the anode. An object of the present invention is to provide a method for producing electrolytic copper, which is characterized by performing purification or electrolytic sampling. Hereinafter, the present invention will be described in detail.

In the method of the present invention, As <5p, which is the copper grade currently achieved by electrolytic refining and electrowinning.
pm, Sb <4 ppm, Bi <2 ppm, Pb <5 pp
Assuming that electrolytic copper of m, S <15 ppm is obtained,
The goal of the electrolysis operation is to achieve the current efficiency of 95% or more achieved in the current electrolysis plant; to achieve a current density much higher than that achieved in the current electrolysis plant. . A method of simultaneously achieving these two goals has not been known in the past. However, by changing the bubble stirring conditions as described above, the electrolysis situation dramatically changes and can be achieved.

Hereinafter, preferable conditions for carrying out the present invention will be described. In the present invention, the current density is 500 to
1000 A / m ² is preferred. Current density is 500A / m
^If it is less than ² , the productivity is not excellent. On the other hand, if it exceeds 1000 A / m ² , the quality of electrolytic copper deteriorates and the current efficiency also decreases, so the above range is preferable. Further, it is preferable that the position from which the bubbles are released is a distance 10 to 20 cm away from the lower end of the anode. If the distance exceeds 20 cm, the distance in the depth direction of the electrolytic cell to the electrode increases, and the amount of copper supplied to the electrolytic cell increases. Preferred flow rates electrode 1 m ² per 10～20L (liters of gas generating bubbles,
The same applies hereinafter) / min. Further, the distance between the anode and the cathode is preferably 10 to 20 mm. In addition, the bubble guide plate extends below the lower end of the anode and the lower end of the cathode so as to guide the entire amount of gas released from the nozzle hole between the electrode facing surfaces, so that air bubbles are uniformly distributed over the entire electrode surface. Becomes possible.

[0010]

The present inventor observed the behavior of the flow, rise, spread, etc. of bubbles in the transparent plastic electrolytic cell. As a result, steady bubbles could not be obtained up to 10 cm above the bubble generation position, and bubbles were found above that. It has been confirmed that the rising speed of the bubble depends on the maximum size nozzle such as the diameter of the nozzle hole or the rectangular outlet. Thereafter, an experiment was performed, and the ideal bubble-stirring electrolysis method was achieved by moving the bubble generation position away from the electrode and specifying the diameter or size.

[0011]

FIG. 1 is an assembly drawing of an anode and a cathode which are immersed in an electrolytic cell when the present invention is carried out. The anode is made of blister copper in the case of electrolytic refining, and is made of an electrically conductive insoluble material such as lead in the case of electrolytic extraction. In the figure, 1 is an anode, 2 is a cathode, 3 is an insulating bottom plate, 4 is a nozzle formed in the bottom plate at equal intervals, 5 is an insulating lid (bubble guide plate) supporting the bottom 1a of the anode, 6 Is an insulating baffle for closing the side gap between the anode and the cathode. When the above-described structure is used, the distance between the nozzle 4 and the anode bottom 1a and the cathode bottom 2b is determined by the height (L) of the lid 5, and the gas released from the nozzle 4 is the above 1, 2, 3,. It is released into the electrolyte filling the closed space defined by the various plate-like members 5 and 6, and escapes to the atmosphere from the opening at the upper part of this space. Regarding the electrolytic solution, the concentration of Cu ²⁺ was 30 to 55 g / L and the concentration of SO ₄ ² was 1 in both cases of electrolytic refining and electrolytic sampling.
What is about 80 to 220 g / L is usually used. Reference numeral 7 denotes an insulating tape adhered to determine the anode area. Reference numeral 8 denotes an insulating spacer extending to the longitudinal edges of these electrodes to set the distance between the anode and the cathode. Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

[0012]

EXAMPLES In the following experimental examples, tests were conducted on a laboratory scale using one anode / cathode assembly shown in FIG.
The anode 1 was made of a lead plate and the cathode 2 was made of stainless steel, and its area was 50 × 300 mm. For electrolysis, the cell voltage is 150
The test was performed in the range of 0 to 2000 mV for 30 hours. Test conditions other than the above are shown in FIG. 2 (Table 1). In the table, electrode bottom
The nozzle distances + and-mean that the nozzle is located below and above the electrode lower end, respectively. In addition, the pump agitation achieved the same amount as the circulating liquid in an actual electrolytic factory. In addition, No. Reference numeral 9 (comparative example) shows a configuration in which the baffle plate 6 is removed so that some of the air bubbles escape from outside the electrode facing surface. The test results are shown in FIG. 3 (Table 2).

In Table 2, the state of electrodeposition on the cathode plate was determined according to the following criteria. ○: good △: normal ×: bad

Nos. In Tables 1 and 2 Examples 1 to 4 are examples of the present invention. On the other hand, in Comparative Example No. In No. 5, since the bubble generation position was too close to the lower end of the electrode, both the current efficiency and the copper grade were poor. Comparative Example No. In No. 6, both the current efficiency and the quality were poor because the bubble generation position was inappropriate. Comparative Examples 7 and 8 have a large nozzle diameter, and Comparative Example 9 has no current barrier and a poor copper grade because no baffle plate is provided.

[0015]

As described above, according to the present invention, it is possible to produce a product of the same grade as electrolytic copper in a conventional electrolytic plant with about 1.5 to 3 times the productivity. Further, in order to carry out the method of the present invention, it is necessary to newly install equipment for blowing air and to remodel electrodes, but it can be expected that capital investment will be sufficiently attracted to an increase in production volume.

[Brief description of the drawings]

FIG. 1 is a perspective view of an apparatus in which an anode and a cathode used in the method of the present invention are assembled.

FIG. 2 is a table (Table 1) showing test conditions of Examples and Comparative Examples of the present invention.

FIG. 3 is a table (Table 2) showing test results of Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 1-anode 2-cathode 3-insulating bottom plate 4-nozzle 5-insulating lid (bubble guide plate) 6-insulating baffle plate

Claims (8)

[Claims] A bubble is floated along an electrode surface of a bleached copper anode or an insoluble anode immersed in an electrolytic solution disposed at a position facing the cathode, and the bubble is moved from the side edge of the electrode. In a method for producing electrolytic copper for performing electrolysis while suppressing discharge to the outside of an electrode surface, a nozzle hole having a diameter or a maximum dimension of 1.5 mm or less from a lower position at least 10 cm away from a lower end of the electrode. A method for producing electrolytic copper, comprising performing electrolytic refining or electrolytic sampling for more release. ^2. Electrolysis is performed at a current density of 500 to 1000 A / m ² , and the quality is As <5 ppm and Sb <4 pp.
m, Bi <2 ppm, Pb <5 ppm, S <15 ppm
The method for producing electrolytic copper according to claim 1, wherein the electrolytic copper is produced. 3. The method according to claim 1, wherein the bubble is moved from the lower end of the anode by 10 to 2
3. The method for producing electrolytic copper according to claim 1, wherein the electrolytic copper is released from a distance of 0 cm. 4. The method for producing electrolytic copper according to claim 1, wherein the flow rate of the gas for generating the bubbles is 10 to 20 L (liter) / min per 1 m ² of the electrode surface. 5. The distance between the anode and the cathode is 10 to 20 mm.
The method for producing electrolytic copper according to any one of claims 1 to 4, wherein 6. A bubble guide plate extending below the lower end of the anode and the lower end of the cathode to guide the entire amount of gas released from the nozzle hole between the electrode facing surfaces. The method for producing electrolytic copper according to any one of the preceding claims. 7. The method for producing electrolytic copper according to claim 1, wherein the blister copper of the anode is electrolytic copper by electrolytic refining. 8. The method for producing electrolytic copper according to claim 1, wherein said anode is insoluble, and electrolytic solution is electrolytically collected to produce electrolytic copper.