JP3083079B2 - Copper electrorefining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to copper electrorefining, and more particularly, to a method for copper electrolysis while preventing impurities from being eluted into an electrolytic solution.

[0002]

2. Description of the Related Art In copper electrolysis, impurities eluted from crude copper in an electrolytic solution during electrolytic refining, particularly Sb and Bi, remain in the electrolytic solution without being precipitated at the cathode. When the concentration increases, it precipitates and adheres to the pipes or the like as scale, blocks the pipes, or adheres to and gets caught in electrolytic copper, adversely affecting the product. Therefore, in order to remove Sb and Bi from the electrolytic solution out of the system, as shown in FIG. 2, the electrolytic solution is once concentrated, and the copper in the electrolytic solution is recovered as alum, and then Cu, A method of electrolytically extracting Sb and Bi (electrolytic extraction method) is employed.

In the electrowinning method, impurities in a copper electrolyte such as As, Sb, Bi and the like are also deposited due to a decrease in the Cu concentration as the electrolysis proceeds, and as a result, these impurities are deposited on the cathode and removed. You. However, this method may generate harmful gases such as arsine and the current efficiency is extremely low, so that many problems remain in operation. Furthermore, in the above-mentioned electrowinning method, since a copper seed plate is used as a cathode, the obtained cathode is used to recover Cu.
The process is repeated to the smelting process while b and Bi are electrodeposited. However, as a result, there are problems that not only Sb and Bi cannot be discharged out of the system but also the amount of Cu in-process cannot be reduced.

[0004] As a method for solving this drawback, there is a method using a chelate resin and the like. According to this method, Sb and Bi can be directly paid out of the system. However, this method requires a large facility, and the treatment of the eluted liquid requires cost and labor. It is also conceivable to oxidize these Sb and Bi using an oxidizing agent and remove them as oxides. However, the cost of the oxidizing agent is high, and the efficiency is low when low-cost air is used as the oxidizing agent. Therefore, neither is practical.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned situation, and it is intended to prevent the precipitation of Sb and Bi on an electrolytic cell device and electrolytic copper in the electrolytic refining of copper, and to perform electrowinning. It is an object of the present invention to provide a method that can reduce the repetition of Cu, Sb, Bi in the purification process by using the electrolytic copper obtained in the above as a high-quality product.

[0006]

In other words, the method of the present invention for solving the above-mentioned problems lies in a combination of electrolytic refining and electrowinning , and comprises S in the electrolytic slime produced in the electrolytic refining step.
b, and in order to concentrate the Bi, the electrolytic refining process is discharged from performed decoppered electrolysis an electrolyte drainage as liquid supply electrowinning step, the electrolytic refining step the waste electrolytic solution discharged from the electrowinning step To the liquid.

Specifically, an electrolytic wastewater discharged from an electrolytic cell in an electrolytic refining process using an anode having an increased amount of copper oxide is supplied to an electrolytic cell in an electrolytic sampling process, and an electrolytic sampling process using an insoluble anode is performed. The electrolytic effluent rich in dissolved oxygen discharged from the electrolytic cell is supplied to the electrolytic cell in the electrolytic refining step.

When employing the method of the present invention, it is preferable to maintain a constant amount of copper electrodeposited on the cathode in the electrowinning step by controlling the oxygen concentration of the anode for electrolytic refining.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a flowchart of an embodiment of the present invention. In the electrolytic refining tank, electrolysis is performed using the blister copper as the anode and the Cu seed plate as the cathode, as in the prior art.
In the electrowinning tank, copper removal electrolysis is performed using an insoluble electrode such as Pb as the anode and a Cu seed plate as the cathode. In copper electrorefining, the current efficiency of the anode and the current efficiency of the cathode are usually not equal, and the current efficiency on the anode side is generally high. Therefore, the amount of copper eluted from the anode is larger than the amount of copper electrodeposited at the cathode, and the extra eluted C
u flows out together with the electrolytic effluent in the form of copper sulfate, and is deposited on the cathode by copper removal electrolysis in the electrolytic collection tank.

In this embodiment, in the electrolytic refining of copper, the electrolytic refining step and the electrolytic retrieving step are combined with each other, and the electrolytic retrieving effluent rich in dissolved oxygen is supplied to the electrolytic refining step. By suppressing the elution of Sb and Bi, the concentration of Sb and Bi in the electrowinning electrolyte is prevented from increasing, and the precipitation of Sb and Bi on the cathode (electrolytic copper) is prevented. Furthermore, the electrolytic copper obtained by the electrowinning becomes a high-quality product, and the repetition of Cu, Sb, and Bi in the refining process can be reduced.

That is, only the usual additives are added to the drainage of the electrolytic cell in the electrolytic refining step, and the solution is directly supplied to the electrolytic collecting tank. By performing a series of cycles of supplying liquid to the electrolytic cell, Sb and Bi are effectively prevented from being eluted from the anode for electrolytic refining into the electrolytic solution, and Sb and Bi are concentrated as electrolytic slime. As a result, Cu deposited on the cathode side in the electrowinning step becomes high quality electrolytic copper.

Although there is some unclear point about this principle, since the concentration of Sb and Bi existing in the electrolytic solution also decreases, the dissolved oxygen generated at the anode for electrolytic collection enters the electrolytic purification tank. SbO ⁺ and BiO ⁺ once eluted from the anode for electrolytic purification are oxidized by the dissolved oxygen,
It was considered that oxides such as ₂ O ₅ and Bi ₂ O ₅ were formed and precipitated as slime in the electrolytic purification tank. 2SbO ⁺ + 3H ₂ O → Sb ₂ O ₅ + 6H ⁺ + 6e 6H ⁺ + 3O ₂ + 6e → 3H ₂ O Cu ⁺⁺ + 2e → Cu

On the other hand, in the electrowinning tank, the reaction on the anode side mainly uses oxygen generation because an insoluble anode such as Pb is used, and copper does not elute. Therefore, it is necessary to supply the amount of copper deposited on the cathode side by some method. This amount of copper
This is achieved by increasing the oxygen quality in the anode in electrorefining. In other words, it is considered that oxygen in the anode of the electrolytic refining tank is usually fixed in the form of copper oxide, and this copper oxide does not require electric energy even in the electrolytic refining tank, and is replaced with sulfuric acid or sulfuric acid in the electrolytic solution. Chemically dissolved by dissolved oxygen. _{CuO + H 2 SO 4 → CuSO} 4 + H 2 O Cu 2 O + 2H 2 SO 4 + 1 / 2O 2 → 2CuSO 4 + 2H 2 O

Therefore, if the oxygen quality in the anode of the electrolytic refining tank is increased, that is, if the amount of copper oxide is increased, the amount of copper in the electrolytic drainage from the electrolytic refining step increases, and the cathode in the electrolytic sampling step increases. Can be supplied with the copper amount of electrolytic copper deposited on the substrate. For example, as shown in JP-A-7-0106216, the difference between the elution of copper from the anode and the electrodeposition of copper at the cathode in electrolytic refining, that is, the increase C of the Cu elution rate, is defined by the following equation. C = {(anode elution amount) / (cathode electrodeposition amount) -1}
× 100

The anode has an oxygen grade of 0.22-0.
In the range of 06%, the following regression equation is obtained for oxygen quality B. C = 4.91B + 0.166

Using the above equation, the oxygen grade B in the anode of the electrolytic refining tank is adjusted so as to compensate for the copper electrodeposited in the electrolytic sampling step.
Should be set. For example, if the amount of electricity in the electrowinning step is about 2% of the amount of electricity in the electrolytic refining step, 2% is substituted into the above equation C, and the anode oxygen quality may be adjusted to 0.37%.

[0017]

Next, the present invention will be further described with reference to examples.

[Example] An electrolytic refining tank and an electrolytic collection tank were prepared. The electrolytic refining tank has a height of 500 mm, a width of 200 mm and a height of 2
Sm: 0.03%, Bi: 0.
Four anodes each having a quality of 02%, a thickness of 30 mm, and a weight of 5 kg were loaded. 0.7mm thick cathode
Were placed at intervals of 20 mm. The electrodeposited areas of the anode and the cathode were 140 mm × 140 mm.
The electrolyte was placed in the top of the electrolytic refining tank, and the drain was drained. The liquid discharged from the bottom was put into a pump tank, and sent from the pump tank to an electrolytic collecting tank by a pump to perform electrolytic sampling. Then, the excess liquid from the electrolytic collection tank was supplied to the electrolytic purification tank.

As the anode, a Pb plate having an electrode area of 80 mm × 95 mm and a thickness of 5 mm was masked on one side as an anode, and the cathode was 0.7 mm thick.
Was charged.

The electrolytic solution is sulfuric acid: 190 g / l, Cu: 5
0 g / l, Sb; 0.60 g / l, Bi; 0.67 g /
The composition was 1 l, the liquid volume was 10 liters, and the liquid temperature was 60 ° C. The flow rate was 40 ml / min. The current density in the electrolytic refining was 250 A / m ^2, and electricity was supplied for 10 days. The current was supplied at the same time as the electrolytic refining at a current density of 60 A / m ² for the electrolytic sampling. In addition, since the oxygen grade of the anode of the electrolytic refining tank used for the test was 0.20%, the amount of current was 10300 A · Hr in the electrolytic refining tank, and the amount of electrowinning was set to 1.16%. The amount of current in the electrolytic collection tank was 120 A · Hr, and there was almost no change in the Cu concentration during 10 days of energization.

[Comparative Example] The comparative example was carried out under the same conditions as in the example except that there was no electrolytic refining tank.

Table 1 shows B of the initial solution and the final solution in the electrolytic cell.
The concentrations of i and Sb are shown, and Table 2 shows the Sb and Bi quality in the slime generated in the electrolytic cell. As shown in Table 1, it can be seen that the method according to the present example can prevent elution of Sb and Bi more effectively than the comparative example. The analysis values of Sb and Bi in the slime of Table 2 also show that Sb and Bi are concentrated in the slime. Further, the elution rate was a negative value in the example, and it was confirmed that the elution rate was also precipitated from the electrolytic solution. Further, when the cathodes of the electrolytic collection tank and the electrolytic refining tank were analyzed, as shown in Table 3, no problem was caused in terms of impurities, and it was confirmed that the product was a high-grade electrolytic copper product.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

According to the present invention, the elution of Sb and Bi into the electrolytic solution in the electrolytic refining tank can be suppressed, and the purification step can be greatly simplified.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of the related art.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-104687 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C25C 1/00-7/08

Claims (3)

(57) [Claims] 1. In an electrolytic slime produced in an electrolytic refining step.
To concentrate Sb, the Bi in the waste electrolytic solution to be discharged from the electrolytic refining process and the liquid supply of the electrowinning step, liquid feed of the waste electrolytic solution discharged from the electrowinning step to said electrolytic refining step And a copper electrolytic refining method. 2. An electrolytic cell in an electrowinning step using an insoluble anode, wherein an electrolytic drainage discharged from an electrolysis cell in an electrorefining step using an anode having an increased amount of copper oxide is supplied to an electrolysis tank in an electrowinning step. A copper electrolytic refining method characterized by supplying an electrolytic drainage discharged from the electrolytic refining process to an electrolytic cell in an electrolytic refining step. 3. The method according to claim 1, wherein the amount of copper electrodeposited on the cathode in the electrowinning step is kept constant by controlling the oxygen concentration of the anode for electrolytic refining.