JP2960876B2 - Copper electrolyte cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a purification method for removing metals such as copper, arsenic, antimony and bismuth which are increased in a circulating copper electrolytic solution when electrolytically refining crude copper to produce high-purity electrolytic copper. It relates to the liquid method.

[0002]

2. Description of the Related Art Generally, a method shown in FIG. 2 is widely used as a method for purifying a copper electrolytic solution in copper electrolytic refining. As the electrolytic refining of blister copper progresses, metals such as copper, arsenic, antimony, bismuth and nickel increase in the electrolytic solution, so the electrolytic solution is heated and concentrated to utilize the difference in solubility of copper sulfate. Then, the copper content is removed as copper sulfate, and then the remaining copper, arsenic, antimony, and bismuth are electrodeposited by electrolytic extraction (referred to as "de-assertion electrolysis") of the decoppered solution. There is a method in which the solution is cooled, nickel is separated as a sulfate using the difference in solubility, and the solution after the frozen crystallization is returned to an electrolytic plant, so that the components of the electrolytic solution are properly maintained.

[0003]

In this conventional method, since the electrowinning method is used to remove arsenic, antimony, and bismuth, there is a danger of generating highly toxic arsine gas (AsH ₃ ) during electrolysis. Furthermore, it has the disadvantage that the power consumption during electrowinning is extremely high. Arsenic gas is generated by converting arsenic in the electrolytic solution into trivalent arsenic ions by injecting arsenic acid gas into the electrolytic solution taken out of the electrolytic cell or into the solution after decopperization, and then depositing copper and arsenic simultaneously as compounds. JP-A-56-201 discloses a method for suppressing
No. 85 (Japanese Patent Publication No. 57-40231), this method cannot always completely prevent the generation of arsine gas.

Japanese Patent Application Laid-Open No. 57-5884 discloses a method for removing copper from an electrolytic solution subjected to electrolytic copper refining, heating the electrolytic solution to 40 ° C. or more, and blowing hydrogen sulfide to a predetermined potential. Describes a method for treating a copper electrolytic solution in which a metal component in the liquid is precipitated as a sulfide, which is filtered off, the precipitate is a raw material for copper smelting, and the filtrate is recycled as a copper electrolytic solution. However, handling highly toxic hydrogen sulfide gas in a large gas state as described in this method has many problems, and is a method that cannot be carried out industrially. Another disadvantage of the system in which hydrogen sulfide gas is blown into the electrolytic solution is that although there is no description in JP-A-57-5884, impurities such as nickel and iron deposited in the electrolytic solution are sufficiently removed. That is not possible.

In connection with the injection of hydrogen sulfide, Japanese Unexamined Patent Publication No.
No. 188,963 discloses a method for recovering high-purity copper from a copper electrolytic waste liquid by treating the copper electrolytic waste liquid with hydrogen sulfide to remove impurities such as copper, arsenic, and antimony in the liquid from a sulfide mainly composed of copper sulfide. And a high purity copper of 99.9% or more is deposited on the cathode by anodic electrolysis using an aqueous solution of sulfuric acid as an electrolytic solution in the anode chamber using an electrolytic cell having an anode chamber partitioned by a diaphragm. At first, a flow of recovering crude nickel sulfate and sulfuric acid after passing the copper removal solution after recovering the sulfide through the nickel sulfate step is proposed. Here, too, the hydrogen sulfide treatment of the copper electrolysis waste liquid is not industrially practical.

[0006] An object of the present invention is to establish a useful industrially feasible method as a method for purifying a circulating copper electrolysis solution, which is an alternative to the separation method by electrowinning arsenic, antimony, and bismuth which generates harmful arsine. That is.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventor has replaced the separation method by electrowinning arsenic, antimony, and bismuth, which generate harmful arsine, with a method in which these metals are separated as sulfides by precipitation and separation. We focused on the usefulness of However, injecting hydrogen sulfide gas into the electrolyte to precipitate and remove these metals as sulfides,
As described above, highly toxic hydrogen sulfide gas must be transported and handled in a gaseous state, which is industrially impossible. As a method of industrially effective separation by sulfide precipitation that eliminates these disadvantages, the present inventor first divides the electrolytic solution from which impurities are to be removed into two, and adds industrial sodium bisulfide to one of the electrolytic solutions. Then, copper, arsenic, antimony, and bismuth in the liquid are precipitated and separated as sulfides, and an excess amount of sodium hydrogen sulfide is added to react with sulfuric acid remaining in the liquid to generate hydrogen sulfide gas. Then, a method of passing this gas through the other electrolyte to precipitate and separate copper, arsenic, antimony, and bismuth as sulfides has been conceived, and its usefulness has been confirmed.

Against this background, the present invention aims to prevent the accumulation of impurities in a circulating electrolytic solution in copper electrolytic refining by extracting a portion of the electrolytic solution, purifying the electrolytic solution, and then purifying the recirculated copper electrolytic solution. In the liquid method, the extracted copper electrolytic solution is divided, and industrial sodium bisulfide is added to one of the divided electrolytic solutions,
Metals such as copper, arsenic, antimony, and bismuth in one of the split electrolytes are precipitated and separated as sulfides, and excess industrial sodium hydrosulfide is added to one of the split electrolytes to remain in one of the split electrolytes Reacts with sulfuric acid to generate hydrogen sulfide gas, passes the generated hydrogen sulfide gas through the other split electrolyte, and precipitates and separates metals such as copper, arsenic antimony and bismuth as sulfide in the other split electrolyte And a method for purifying a circulating copper electrolytic solution, characterized by recirculating the separated filtrate. Furthermore, it is advantageous to add an alkali agent to one of the divided electrolytes to which sodium hydrogen sulfide is added and then separate and remove heavy metal impurities that cannot be sufficiently removed as sulfides by neutralizing precipitation. is there.

It is preferable that most of the copper in the copper electrolyte is recovered from the extracted copper electrolyte by an electrowinning method, and then the copper electrolyte is divided. In this case, before recovering most of the copper in the extracted copper electrolytic solution by the electrowinning method, the copper electrolytic solution is passed through an ion-exchange resin to remove antimony and / or bismuth from the copper electrolytic solution. It is advisable to adsorb and remove the part on the resin. The electrolytic solution can be heated to evaporate water, and copper can be precipitated and separated as copper sulfate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In copper electrolytic refining, the amount of copper eluted from an anode is generally larger than the amount of copper deposited on a cathode, so that the concentration of copper in an electrolytic solution gradually increases. An increase in the copper concentration above a certain level optimally prevents electrolytic refining. On the other hand, arsenic, antimony, bismuth, nickel, iron and the like contained in the copper anode elute in the electrolyte. When these impurity ions reach a certain degree or more, they deposit on the cathode and lower the quality of electrolytic copper. Nickel also has the detrimental effect of raising the electrolysis voltage and antimony being suspended by hydrolysis. Therefore, it is important to remove the electrolytic solution from the electrolytic cell and purify the circulating copper electrolytic solution after the purification and return to the electrolytic cell.

FIG. 1 shows a flow sheet of a process for purifying a copper electrolysis circulating solution according to the present invention. The electrolytic solution from which the impurities from the electrolytic plant should be removed is divided into two parts (this step is shown as a post-decoppering liquid after copper is recovered by decopperizing electrolysis, but this step can be omitted). You. One split electrolyte is introduced into the sodium bisulfide addition tank and the other split electrolyte is introduced into the reaction layer. In the sodium hydrogen sulfide addition tank, industrial sodium hydrogen sulfide is added to one of the divided electrolytes,
Metals such as copper, arsenic, antimony, and bismuth in the split electrolyte are precipitated and separated as sulfides, and excess industrial sodium hydrosulfide is added to the split electrolyte to react with sulfuric acid remaining in the solution. To generate hydrogen sulfide gas, pass the hydrogen sulfide gas through the other split electrolyte in the reaction tank, and precipitate and separate metals such as copper, arsenic antimony, and bismuth in the other split electrolyte as sulfides. Recycle the filtrate. Further, in a neutralization facility, an alkaline agent such as slaked lime or calcium carbonate or caustic soda is added to one of the divided electrolyte solutions to which sodium bisulfide is added to adjust the pH to 8 to 1.
It is beneficial to separate and remove impurities such as nickel and iron which cannot be sufficiently removed as sulfides as neutralized precipitates in the two ranges. The precipitate is sent to the smelting process as filter cake, and the filtrate is discharged as wastewater.

The divided volume ratio of one divided electrolyte to the other divided electrolyte for producing a circulating electrolyte can be in the range of 1: 2 to 1:10. If the other divided electrolyte is too small, the amount of the circulating electrolyte will be small. If the other divided electrolyte is too large, it is not possible to generate a required amount of hydrogen sulfide gas. In the electrolytic solution after copper removal, copper is 5 to 20 g.
/ L, arsenic is 1-10 g / l, antimony is 0.1-
1.0 g / l, bismuth 0.05-1.0 g / l, nickel 5-20 g / l and free sulfuric acid 100-3
00g / l. Depending on the amount of these impurities,
The required hydrogen sulfide gas amount can be determined, and the split ratio can be determined.

The hydrogen sulfide gas is produced by reacting inexpensive industrial sodium hydrogen sulfide with sulfuric acid remaining in the liquid in a sodium hydrogen sulfide addition tank, and the required amount of hydrogen sulfide gas is directly passed through the reaction tank. There is no need to transport and store a large amount of gas, and safe operation can be performed. It is preferable that the sodium hydrogen sulfide addition tank and the reaction tank are provided side by side.

As the metal component in the electrolytic solution, copper is the largest, and when this solution is directly treated, a large amount of copper sulfide is generated, which becomes a repetitive material to the smelting system. It is preferable that copper is removed before sulfide precipitation. As a method for removing copper, an electrowinning method for obtaining electrolytic copper having a purity of 99% or more or a method for separating copper sulfate by heat concentration are suitable. In the case of electrowinning, in order to increase the purity of electrolytic copper, first, an electrolytic solution is treated with an ion exchange resin to remove antimony and / or bismuth, and then copper is recovered by electrowinning. Turned out to be suitable.

[0015]

【Example】

Example 1 As shown in FIG. 1, 30 m ³ of an electrolytic solution containing 45 g / l of copper was treated by a known electrowinning method (copper removal electrolysis), and 450 kg of electrolytic copper having a copper purity of 99.99% was obtained.
Then, 99.9% of electrolytic copper was separated and collected at a point of 600 kg. After the electrolysis, the solution contained 10 g / l of copper and 5 g of arsenic.
g / l, antimony 0.4 g / l, bismuth 0.1
g / l, nickel 15 g / l and free sulfuric acid 21
4 g / l was contained. 500 kg of industrial sodium bisulfide containing about 25% of NaSH was added to 6.7 m ³ of one of the divided electrolyte solutions, which was about 1/5 of this solution, to precipitate copper, arsenic, antimony and bismuth. Further, 1740 Kg of excess sodium hydrogen sulfide for industrial use was added at a rate of about 10 Kg per minute, and reacted with sulfuric acid in the solution to generate hydrogen sulfide gas. This hydrogen sulfide gas is used for the remaining divided electrolyte solution 23.
The solution was led to 3 m ³ , and the remaining split electrolyte and a hydrogen sulfide gas were contacted and reacted to precipitate copper, arsenic, antimony and bismuth. The precipitate was separated by filtration, and the obtained filtrate was clean and had a concentration of copper, arsenic antimony and bismuth of 0.1 g / l or less. Since the solution to which industrial sodium bisulfide is added contains substances such as sulfuric acid, nickel, and iron, 905 kg of slaked lime is added, and p of the solution is added.
After H was set to 10, the heavy metal was neutralized and precipitated, followed by filtration, and the filter cake was repeatedly treated in the smelting process. For neutralization, an alkali agent such as calcium carbonate and caustic soda could be used in addition to slaked lime.

(Example 2) Copper 45 g / l, arsenic 5 g /
l, antimony 0.4 g / l, bismuth 0.1 g /
1, nickel 15g / l and free sulfuric acid 160g / l
Was extracted and passed through an ion exchange resin (EPROUS MX-2 manufactured by Miyoshi Resin Co., Ltd.) to adsorb some of antimony and bismuth. The solution passed through the resin contained 45 g / l copper, 5 g / l arsenic, 0.1 g / l antimony, 0.05 g / l bismuth, 15 g / l nickel and 160 g / l free sulfuric acid. This solution was treated by a known method to remove copper by electrolytic sampling. However, since antimony and bismuth in the solution were low, 600 kg of 99.99% pure copper and 450 kg of 99.9% pure copper were used. Obtained. The solution after the electrolysis was treated in the same manner as in Example 1.

[0017]

As a method for purifying the circulating liquid for copper electrolysis, a useful industrially feasible method has been successfully established in place of electrowinning of arsenic or the like which generates harmful arsine. The hydrogen sulfide gas used is generated by reacting inexpensive industrial sodium hydrogen sulfide with sulfuric acid remaining in the liquid in the sodium hydrogen sulfide addition tank at the site, and the required amount is directly passed through the reaction tank. It is not necessary to transport and store a large amount of highly toxic and expensive hydrogen sulfide gas, and safe operation can be performed.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a process step of purifying a copper electrolyte according to the present invention.

FIG. 2 is a flow sheet showing a process for purifying a copper electrolytic solution according to a conventional method.

Claims (5)

(57) [Claims] In a method of purifying a copper electrolyte solution, a part of the electrolyte solution is extracted and purified in order to prevent the accumulation of impurities in a circulating electrolyte solution in copper electrolytic refining. The liquid is divided, and industrial sodium bisulfide is added to one of the divided electrolytes, and copper, arsenic,
Precipitate and separate metals such as antimony and bismuth as sulfides.Additionally, excess industrial sodium hydrosulfide is added to one of the divided electrolytes and reacted with sulfuric acid remaining in one of the divided electrolytes to generate hydrogen sulfide gas. To cause the generated hydrogen sulfide gas to pass through the other split electrolyte, precipitate and separate metals such as copper, arsenic antimony, and bismuth in the other split electrolyte as sulfides, and recycle the separated filtrate. A method for purifying a copper electrolysis circulating solution, characterized by the following. 2. A method according to claim 1, wherein after the separation of sulfide by precipitation into one of the divided electrolytes to which sodium bisulfide is added, an alkali agent is added to separate and remove heavy metal impurities which cannot be sufficiently removed as sulfide as neutralized precipitate. 1. A method for purifying a copper electrolysis circulating solution. 3. The method for purifying a circulating copper electrolytic solution according to claim 1, wherein the copper electrolytic solution is divided after recovering most of the copper in the electrolytic solution from the extracted copper electrolytic solution by an electrowinning method. 4. Prior to recovering most of the copper in the extracted copper electrolytic solution by an electrowinning method, the copper electrolytic solution is passed through an ion exchange resin, and the antimony and / or
4. The method for purifying a circulating copper electrolytic solution according to claim 3, wherein a part of bismuth is adsorbed and removed by the ion exchange resin. 5. The method for purifying a copper electrolytic circulating solution according to claim 1, wherein the extracted copper electrolytic solution is heated to evaporate water, and the copper electrolytic solution is separated as copper sulfate.