JP2000309893A - Electrolytic refining method for copper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic refining method for copper which executes processing without converting soluble components, such as of Cu powder, settled without being eluted in an electrolyte to slime in electrolytic refining of copper and reduces the processing load in a slime processing stage. SOLUTION: In the electrolytic refining of the copper which electrodeposits the copper on a cathode by using blister copper as an anode in an electrolytic cell and dissolving the blister copper in the electrolyte by energization, the bottom of the electrolytic cell is formed by using a bottom plate which is substantially composed of material which can be the insoluble anode. By the constitution described above, the electrolytic slime is deposited on the bottom plate and the bottom plate is electrically connected to the anode and is energized as the anode, by which the slime is dissolved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for electrolytically refining copper.

[0002]

2. Description of the Related Art In the electrolytic refining of metals such as copper, an anode made of a crude metal containing impurities and a cathode for depositing a target metal are charged into an electrolytic cell filled with an electrolytic solution. This is done by energizing this. The target metal is eluted from the anode by energization, and the eluted target metal is deposited on the cathode. On the other hand, impurities in the anode are eluted from the anode into the electrolytic solution and are accumulated in the electrolytic solution, and others are deposited as slime on the bottom of the electrolytic cell like noble metals during copper electrolysis.

Most precious metals such as gold and silver are converted into slime, and are recovered as products by treating them in a separate process. In addition, even impurities that become slimes other than noble metals can be recovered by some method.
Often it is advantageous.

However, for some reason, components which can be easily removed by electrowinning from an electrolytic wastewater or the like, such as Cu, which should be eluted and should be deposited on the cathode, for some reason, than the slime-forming method such as As. In some cases, it may be slimeed, and it is not always advantageous to slime it and treat it in a separate step. The original soluble component can be directly recovered from the electrolytic solution and is inexpensive, so that it is not necessary to forcibly convert it into slime. When these soluble components are converted into slime, the soluble components in the slime are dissolved in an acid prior to the recovery of the noble metal, and refluxed to the electrolyte. For this reason, the number of processes is increased, and this is also a cause of an increase in the amount of in-process precious metals.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the processing load in a slime treatment step by treating a soluble component such as Cu powder which does not elute in an electrolyte solution and does not slime. The present invention provides a method for electrolytically refining copper.

[0006]

In order to solve the above-mentioned problems, in the present invention, a soluble component is eluted while settling in a battery case as slime. In the present invention, in the electrolytic refining of copper in which electrolytic copper is supplied with blister copper as an anode, dissolved in an electrolytic solution, and copper is deposited on a cathode, the bottom of the electrolytic cell is substantially made of a material that can be an insoluble anode. Use the bottom plate to do. Specifically, it is practical to lay a metal on a sheet such as lead or titanium at the bottom. The slime can be dissolved by forming as described above, depositing electrolytic slime on the bottom plate, electrically connecting the bottom plate to the anode, and supplying electricity as the anode.

Further, a mesh made of a material that can be an insoluble anode is attached above the bottom plate, and coarse slime is deposited on the mesh, and the mesh is electrically supplied as an anode to further promote dissolution. Can be.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some of the Cu to be eluted from the anode may settle in the battery case for some reason. In order to dissolve them, it is considered effective to place them in a titanium box or the like and conduct electrolysis again as an anode, or to leaching them in the presence of air. However, if it is transferred to another container, it is the same as treating it as slime from the beginning, and it is meaningless.

On the other hand, in the actual operation of electrolytic refining, slime often remains settled at the bottom of the tank during the energization period of 10 to 20 days. If the soluble metal in the slime can be gradually leached by effectively utilizing this time, the cost for the slime treatment can be reduced. However, blowing air into the tank bottom floats the settled slime,
This may cause deterioration of the appearance quality of the product such as mixing of impurities into the product copper or generation of pinholes due to air.

On the other hand, the present inventors have found that a bottom plate made of an insoluble material is placed on the bottom of an electrolytic cell, and slime is settled on the bottom plate, so that soluble components such as Cu can be leached out. . For the material of the bottom plate, for example, in the case of copper electrolysis, lead or titanium is appropriate. This material is electrically connected as an anode. Even if the anode is present at the bottom of the battery case, most of the current flows toward the blister copper anode because the blister copper anode is superior in terms of distance to the cathode and overvoltage. Therefore, although the gas generation from the bottom plate and its influence are negligible, the potential on the anode surface of the bottom plate is high and sufficient leaching is possible. further,
By disposing a net made of a material that can be an insoluble anode above the bottom plate, depositing coarse slime on the net, and electrically passing the net as an anode, dissolution can be further promoted. Dissolution is promoted as the position of the mesh is increased upward from the bottom plate. However, if the mesh is too close to the anode and the cathode, the amount of current passing through the mesh increases, and the original electrolytic refining operation is hindered.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Conventional example) As an anode, the electrode area is 1 width.
Bronze cast to a size of 40 mm, a length of 140 mm, and a weight of 4.4 kg was used. The composition at the time of casting was Cu: 99.
2 wt%, As: 0.07 wt%, Sb: 0.04 wt
%, Bi: 0.02 wt%, and Pb: 0.05 wt%.

For the cathode, an electrolytic copper plate having a thickness of 0.7 mm was cut so as to have an electrode area of 140 mm * 140 mm.

One anode and two cathodes were placed in an electrolytic cell so that the distance between the surfaces was 20 mm.

The electrolytic cell has a width of 200 mm, a length of 260 mm,
A thing made of polyvinyl chloride with a depth of 260 mm was used.
A drainage tank having a capacity of 5 liters was connected to the drainage of the battery tank, and the drainage of the storage tank was discharged at a rate of 50 ml / ml using a constant volume pump.
circulated in min.

The electrolytic solution is Cu 45 g / l, sulfuric acid 190 g
/ L and a liquid temperature of 60 ° C. Note that no additives were used.

Electric current was applied at a current density of 250 A / m ² for 240 hours.

After the completion of the current supply, the slime at the bottom of the tank was collected, washed, dried and analyzed. Table 1 shows the analysis results. (Example 1) Electricity was supplied under the same electrolysis conditions as in the conventional example. However, a thickness of 4 mm is applied to the entire bottom of the battery case (200 mm * 260 mm).
mm Pb plate was spread and electrically connected to the anode. The current flowing to the bottom plate during electrolysis was about 10% of the whole. After the completion of the energization, the slime at the bottom of the tank was collected, washed, dried and analyzed. Table 1 shows the analysis results. (Example 2) Electricity was supplied under the same electrolysis conditions as in the conventional example. However, a titanium mesh of 200 mesh was attached at a position 10 mm above the bottom plate, so that coarse slime was caught on the titanium mesh. The mesh was also electrically connected to the bottom plate as well as the anode. The current flowing through the bottom plate and the net during electrolysis was about 10% of the whole. After energization, the titanium net and the slime on the bottom plate were collected and analyzed. Table 1 shows the analysis results
Shown in

Table 1 shows the composition of the slime obtained in the conventional example and each example. The quality of each component is% by weight. In Examples 1 and 2 according to the present invention, about 70 to 90% of Cu and As present in the slime could be removed as compared with the conventional example which is a normal case.

[0019]

According to the present invention, soluble components such as Cu can be effectively leached while the anode slime is settling at the bottom of the tank, and the load in the slime treatment step can be reduced. .

Claims (2)

[Claims] In the electrolytic refining of copper, which is energized by using crude copper as an anode in an electrolytic cell, is dissolved in an electrolytic solution, and deposits copper on a cathode, the bottom of the electrolytic cell is made of a material which can be an insoluble anode. A method for electrolytically refining copper, comprising forming a bottom plate, depositing electrolytic slime on the bottom plate, and energizing the bottom plate as an anode to promote dissolution of the slime. 2. The method according to claim 1, wherein a net made of a material that can be an insoluble anode is attached above the bottom plate, and coarse slime is deposited on the net, and the net is electrically used as an anode to conduct electricity. Copper electrolysis method.