JP5971521B2 - Metal manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a metal by electrolytic refining.

  In general, copper and copper alloys are metals in great demand like iron and aluminum. Therefore, it is important from the standpoint of resource protection to collect and reuse copper from copper scrap containing copper, such as copper wires collected as waste and printed circuit boards of household electrical appliances.

  For example, when recovering copper from copper scrap recovered from the market, in the case of power cable wires, the resin covering the copper wires is peeled off and the resin and the copper wires are separated and recovered Yes. For thick communication lines, it is possible to separate and recover copper by stripping the resin that is coated in the same way, but for thin cables, the work load is too great, and such recovery is possible. Can't do the way.

For this reason, in the case of a thin communication line, the copper wire is crushed while being covered with the resin, and then the specific gravity difference is selected. However, even in this way, fine resin still remains on the copper surface, and it is necessary to further remove the resin by burning.
The recovery of copper by the dry method as described above is simple, but the burden on the environment is large because carbon dioxide is generated by the combustion of the resin, and reduction processing is performed because copper is recovered as copper oxide. Is required. Furthermore, depending on the purity of the copper scrap recovered from the market as a raw material, the purity of the recovered metal copper is lowered.

Moreover, when recovering copper from a printed circuit board used for a personal computer or a home appliance, a recovery method by a wet method is known in addition to a dry method. In this wet method, copper is leached with sulfuric acid, hydrochloric acid or the like, and copper is recovered by electrolytic refining.
However, in the wet method, oxygen is generated at the anode electrode, which inevitably increases power consumption during electrolysis.

For example, Patent Document 1 discloses a cathode electrode for depositing metallic copper in a solution containing monovalent copper ions, an anode electrode in an ammonia alkaline solution containing monovalent copper ions, and a gap between the cathode electrode and the anode electrode. A method is described in which a diaphragm is provided, current is passed through the electrode, and electrolysis is performed while the solution is moved from the cathode electrode side to the anode electrode side to recover metallic copper. According to the method described in Patent Document 1, metallic copper is deposited on the cathode electrode portion, and at the same time, the monovalent copper ions can be converted into divalent copper ions at the anode electrode portion, and the divalent copper ion solution is taken out. Then, the solution containing monovalent copper ions obtained by treating the copper metal waste and the complex layer in which the copper metal waste and the complex compound exist and treating the copper metal waste is used as the solution containing the electrolytic monovalent copper ions. Therefore, it is said that power consumption can be made smaller than before.
However, since the treatment target solution for recovering copper contains ions of metals such as manganese, nickel, zinc, and lead, it is necessary to remove the metal ions in order to perform the electrolysis operation. At this time, if it is difficult to energize for some reason, such as the resistance of the target is high or it is covered with an insulating resin, it is difficult to apply an electrolytic refining technique in which the target is dissolved in the anode and deposited on the cathode side. There is a problem that.

  Further, there is a demand for a method for obtaining an arbitrary metal with high purity from various metal-containing materials that can be easily recovered from the market, not limited to copper.

JP 2003-253484 A

  In view of the above problems, an object of the present invention is to efficiently obtain a high-purity metal by a wet method without increasing the burden on the environment and without generating waste liquid.

  In order to solve the above-mentioned problems, the present inventors have studied to dissolve a target metal in an electrolytic solution containing an oxidizing agent and to refine and electrolyze the metal from the solution.

First, copper with high demand was selected as a metal to be collected, and the study of refining metal copper from metal-containing materials was studied. Prepare a waste material (copper: about 38% by mass, resin: about 47% by mass, moisture: about 15% by mass) recovered from the market as a metal-containing material containing copper, and in a solution containing an oxidizing agent (ammonium persulfate) The waste material was added and stirred to completely dissolve the copper. Undissolved resin and the like were removed by filtration, and the filtrate was recovered. Then, a titanium lath plate coated with platinum as an anode in this solution and a platinum plate as a cathode were charged, and a voltage was applied between both electrodes. The current density was 5 A / dm ^{2 to} 15 A / dm ² . As a result, metallic copper having a purity of 99.99% could be recovered.

Subsequently, in order to verify whether such high-purity metallic copper can be continuously obtained, the method of dissolving the metallic copper deposited on the cathode surface again in the same solution and electrolytic refining was repeated.
As a result, each time the cycle was repeated, the electrodeposition efficiency was increased, but the dissolution rate was slow, and it was not possible to dissolve at the 20th cycle. As a result of investigating this cause, it has been found that this is caused by a decrease in ammonium persulfate in the solution. Therefore, ammonium persulfate was newly replenished every 20 cycles, and further cycles were repeated. As a result, ammonium persulfate precipitated without dissolving at the 60th cycle, and verification could not be continued due to an increase in the amount of precipitates. It was.

  As described above, it has been found that ammonium persulfate is reduced and decomposed at the cathode, and a large amount of sulfate ions accumulate in the solution, which causes the liquid life. Since it is indispensable to do so, the present inventors have further studied to solve the problem.

  As a result, it was found that it is effective to provide a cation exchange membrane between the electrodes in the solution so that ammonium persulfate is not decomposed. Then, it is possible to regenerate the reducing agent on the anode side, and furthermore, by using a diamond electrode with a wide potential window for the anode, it is found that water decomposition is suppressed and the regeneration efficiency of persulfate ions becomes very high. It was. Moreover, it was confirmed that these operations are effective even when electrolytic refining of metals other than copper, and the present invention was completed.

The configuration of the present invention is as follows.
(1) An electrolytic cell partitioned by a cation exchange membrane into a cathode chamber having a cathode and an anode chamber having a plate-like diamond electrode,
Supplying a solution containing metal ions to the cathode chamber;
Supplying a solution containing an oxidant in a reduced state to the anode chamber;
The cathode and the diamond electrode are arranged to face each other through the cation exchange membrane,
A voltage of 20 V or more and 40 V or less is applied between the cathode and the diamond electrode, the metal is deposited on the cathode surface in the cathode chamber, and the oxidant in the solution is regenerated in the anode chamber. Metal manufacturing method.
(2) The solution containing the metal ion is:
The method for producing a metal as described in (1) above, which is obtained by adding a metal-containing material to an electrolytic solution containing at least the oxidizing agent and dissolving the metal in the electrolytic solution.
(3) The solution containing the metal ion is:
What stuffed one or more kinds of pulverized materials selected from the group consisting of electric wires, printed circuit boards, semiconductors, motors, shredder dust for automobiles, and electronic devices containing metals into a water-permeable bag contains at least the oxidizing agent. The method for producing a metal according to the above (1) or (2), wherein the metal is obtained by stirring in an electrolytic solution.
(4) The solution containing the metal ions contains at least one metal ion selected from the group consisting of copper, nickel, and zinc. The method for producing a metal according to any one of the above.
(5) The method for producing a metal according to any one of (1) to (4) above, wherein the metal deposited on the cathode surface is copper, nickel, or zinc.
(6) the oxidizing agent The method for producing a metal according to any one of the above, wherein the ammonium persulfate or peroxide Hydrogen (1) to (5).
(7) The method for producing a metal as described in (6) above, wherein the oxidizing agent is ammonium persulfate.
(8) The metal electrode according to any one of (1) to (7) above, wherein the diamond electrode is obtained by forming a conductive diamond film on a silicon substrate by a CVD method. Production method.

  According to the present invention, a high-purity metal can be efficiently obtained by a wet method without increasing the burden on the environment and without producing waste liquid.

It is the schematic showing an example of the structure of the apparatus for implementing this invention. It is the schematic showing an example of another structure of the apparatus for implementing this invention.

  The present invention supplies a solution containing metal ions to the cathode chamber of an electrolytic cell partitioned by a cation exchange membrane into a cathode chamber having a cathode and an anode chamber having a diamond electrode, and the anode Supplying a solution containing an oxidant in a reduced state to the chamber, applying a voltage between the cathode and the diamond electrode, depositing metal on the cathode surface in the cathode chamber, and in the solution in the anode chamber The oxidant is regenerated.

  FIG. 1 shows an outline of the configuration of an apparatus capable of refining copper as an example of an apparatus capable of performing the metal production method of the present invention. As shown in FIG. 1, the apparatus includes an electrolytic cell in which a cathode chamber and an anode chamber are partitioned by a cation exchange membrane. The cathode chamber has a cathode for depositing metallic copper, and the anode chamber has an anode chamber. Each diamond electrode is arranged. Both electrodes are connected to a power supply so that a voltage can be applied between the cathode and the diamond electrode. The cathode chamber is supplied with a solution containing copper ions, and the anode chamber is supplied with a reduced solution containing an oxidizing agent.

  By applying a voltage between the cathode and the diamond electrode in such an apparatus, it is possible to regenerate the oxidizing agent in the anode chamber while depositing metallic copper on the surface of the cathode. Since the cathode chamber and the anode chamber are separated by a cation exchange membrane, the oxidized oxidant in a reduced state, which is an anion, does not leak from the anode chamber to the cathode chamber. The agent can be regenerated.

After sufficiently depositing copper metal from the solution in the cathode chamber, the solution in the cathode chamber contained a large amount of reduced oxidant, while the solution in the anode chamber was regenerated. Contains a lot of oxidizing agent.
For this reason, when performing electrodeposition of metallic copper continuously, take out the cathode and diamond electrode from both chambers, supply the metallic copper-containing material to the solution containing more regenerated oxidant, and dissolve the copper. Then, an anode may be installed, and a diamond electrode may be installed in a solution containing a large amount of the oxidant in the reduced state on the opposite side, and a voltage may be applied between both electrodes. That is, electrodeposition may be performed by replacing the cathode chamber and the anode chamber in the operation procedure described first. Thereby, metallic copper is deposited on the cathode surface of the new cathode chamber, and the oxidant can be regenerated in the new anode chamber.
As described above, electrolytic refining can be repeated simply by switching the cathode chamber and the anode chamber while supplying metallic copper-containing material, and the oxidant can be regenerated every time, so the liquid life is very long. It is possible to operate without producing waste liquid.

  In the above example, the method of exchanging the cathode chamber and the anode chamber has been described, but the operation can be repeated by the method of exchanging the solutions in both chambers. In this case, the metal copper-containing material is supplied into the solution regenerated by the oxidant in the cathode chamber to dissolve copper, and this solution and the solution in the anode chamber are exchanged to apply a voltage between both electrodes. . This method can be efficiently performed by using, for example, an apparatus as shown in FIG.

  The apparatus shown in FIG. 2 is provided with an electrode tank section on the upper stage and a solution tank section on the lower stage. The upper electrode chamber is divided into three rooms, the central chamber is a cathode chamber provided with a cathode, and the two outer chambers provided so as to sandwich the cathode chamber are anode chambers provided with diamond electrodes. It has become. The central cathode chamber and the anode chambers on both sides thereof are partitioned by a cation exchange membrane.

  In addition, the lower solution tank is divided into two rooms, one of which is supplied with a solution containing copper ions, and the other is supplied with a solution containing a reduced oxidant. ing. A liquid flow pipe is connected to each of the lower chambers so that a solution containing copper ions is supplied to the cathode chamber and a solution containing the reduced oxidizing agent is supplied to the anode chamber via a pump. It has become.

Then, the solutions supplied to the upper cathode chamber and the anode chamber are respectively returned to the room supplied with the solution containing the lower copper ions and the room supplied with the solution containing the reduced oxidizing agent. It is supposed to be.
In order to do this, for example, the lower solution tank part is made larger than the upper electrode tank part, and only one side of the side wall that is not the cation exchange membrane of the cathode chamber is made to be larger than the opposite side wall. Similarly, the side wall of the cathode chamber may be formed low only on the side opposite to the side wall formed low in the anode chamber. As a result, when the amount of each solution supplied to the cathode chamber or anode chamber by the pump exceeds the capacity of each chamber, the solution overflows from the low-formed side walls and is returned to the lower chambers to circulate the solution. As a result, the efficiency of electrolytic refining can be increased.

  After the metal ions are sufficiently deposited on the anode surface, the solution in the lower chamber contains a large amount of reduced oxidant, and the solution in the other chamber contains a large amount of regenerated oxidant. It is like that. To continue operation, remove the upper electrode tank, supply metal copper-containing material to the lower chamber containing the regenerated oxidant-rich solution, dissolve the copper, and again upper electrode tank What is necessary is just to attach a part. At this time, connect the pipe with the upper electrode tank part attached in the opposite direction from the first, and the solution overflowing from the anode will overflow from the cathode into the room containing the solution containing copper ions. Each solution is returned to the room containing the solution containing the reduced oxidant.

  By using the apparatus as described above, the metal production method of the present invention can be carried out continuously. However, as long as the metal production method of the present invention can be carried out, any method can be used. An apparatus may be used. In the above, the present invention has been described by taking the case of producing metallic copper as an example using FIG. 1, but the metal obtained by the present invention is not limited to copper, and any metal contained in the metal-containing material can be used. Can be obtained. That is, any metal can be obtained as long as it can be dissolved in the electrolytic solution by using an oxidizing agent and can be deposited on the anode by applying a voltage.

Then, each component used in the manufacturing method of the metal of this invention is demonstrated.
(Metal-containing material)
Any metal-containing material may be used as long as the target metal is contained. For example, the use of recovered products from the market can contribute to resource protection. For example, copper, nickel, zinc, silver, and iron are included in metal-containing materials by using copper wires, printed circuit boards for personal computers and home appliances, semiconductors, electronic devices, motors, shredder dust for automobiles, harness connectors, etc. Any metal can be obtained.

  When multiple types of metals are contained in the metal-containing material, the multiple types of metals are dissolved in the electrolyte solution described later. In this case, a specific metal is obtained from a solution containing a plurality of types of metal ions. However, in order to obtain a highly pure metal, first, the metal deposited at the lowest voltage is deposited on the cathode and collected. Then, the cathode may be replaced with another one, and electrolytic refining may be performed by applying a higher voltage. By repeating this operation, each metal can be obtained with high purity from a metal-containing material containing plural kinds of metals.

  In addition, from the viewpoint of supplying a metal-containing material in a solution containing a large amount of an oxidant and dissolving the metal, it is preferable to use the metal-containing material after being pulverized as finely as possible. That is, in the present invention, even a material that cannot be directly supplied with power through wiring or the like can be used. For example, even a powder material made of only a metal that is difficult to be energized, such as copper molybdenum or copper tungsten powder, can be used by being dissolved in an electrolytic solution containing an oxidizing agent. In order to prevent the portion other than the metal of the pulverized product that does not dissolve in the solution from diffusing into the solution and contaminating the tank, the pulverized product of the metal-containing material is packed in a water-permeable bag such as a nonwoven fabric. It is preferable.

(Oxidant)
Any oxidizing agent can be used as long as it can dissolve the metal from the metal-containing material, and may be appropriately selected according to the type of metal contained in the metal-containing material. For example, chlorine, ammonium persulfate, hydrogen peroxide, sodium persulfate and the like can be mentioned. Among these, ammonium persulfate is particularly preferable.

(Electrolyte)
The electrolytic solution is not particularly limited, and may be appropriately selected depending on the combination with the oxidizing agent. For example, acidic solutions such as sulfuric acid, hydrochloric acid, phosphoric acid, hydrofluoric acid, and nitric acid are listed. Of these, sulfuric acid is particularly preferred.
In the combination with the oxidizing agent, a combination of hydrogen peroxide and sulfuric acid, a combination of ammonium persulfate and sulfuric acid is preferable, and a combination of ammonium persulfate and sulfuric acid is particularly preferable. Ammonium persulfate can be used in a concentration range of 1 g / L to saturated solubility, but more preferably 30 to 100 g / L. Further, sulfuric acid hydrogen peroxide solution is preferably used in a range of molar ratio of sulfuric acid and hydrogen peroxide _{(H 2 SO 4 / H 2} O 2) is 0.61 to 1.5.

(Cation exchange membrane)
Any cation exchange membrane may be used as long as it does not permeate anions, particularly reduced oxidants. Examples of commercially available products include SF7202 (Asahi Kasei E-Materials Co., Ltd.), Nafion-117 (DuPont Co., Ltd.), and Acibrex (Asahi Kasei Chemicals Co., Ltd.). Of Nafion-117 is particularly preferred.

(cathode)
Any cathode can be used as long as it can deposit metal on the electrode surface. For example, copper, platinum, nickel, iron, titanium and the like can be mentioned, and may be appropriately selected according to the type of the target metal.

(Diamond electrode)
As the diamond electrode, any electrode having conductive diamond on at least the surface can be used. For example, a silicon substrate surface with a conductive diamond film formed by chemical vapor deposition (CVD) can be preferably used. Such a diamond electrode can be purchased from, for example, Sumitomo Electric Hardmetal Corporation in the market.
Since the diamond electrode has a wide potential window (> 2 V) on both the anode side and the cathode side, it has a strong oxidizing / reducing power and can cause reactions other than water electrolysis. For this reason, also in this invention, it becomes possible to reproduce | regenerate an oxidizing agent efficiently by using a diamond electrode as an anode.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, these Examples are illustrations and the manufacturing method of the metal of this invention is not limited to these. The scope of the present invention is defined by the scope of the claims, and includes meanings equivalent to the scope of the claims and all modifications within the scope.

Example 1
As the metal-containing material, fine copper wire pulverized material collected from the market was used. The composition of the pulverized product was about 38% by mass of copper, about 47% by mass of resin, and about 15% by mass of moisture. This was packed in a bag made of polypropylene non-woven fabric.

  To 1 L of 6N sulfuric acid, 60 g of ammonium persulfate was added and stirred until completely dissolved. Furthermore, the bag filled with the pulverized metal-containing material prepared above was immersed in the solution, and stirred well using a stirrer to prepare a solution containing copper ions.

An electrolytic cell provided with a cation exchange membrane (Nafion-117, manufactured by DuPont Co., Ltd.) in the center is prepared, the solution containing the copper ion prepared above is placed in one chamber, and an electrode made of platinum (Pt) (Cathode) was installed to form a cathode chamber.
In the other chamber, which was completely covered with a cation exchange membrane, a solution of 60 g of ammonium sulfate dissolved in 1 L of 6N sulfuric acid was placed, and a diamond electrode (anode) was installed to form an anode chamber. A diamond electrode industrial grade manufactured by Sumitomo Electric Hardmetal Co., Ltd. was used as the diamond electrode.

The cathode and the diamond electrode were opposed to each other with a distance of about 10 cm through the diaphragm, and a voltage of 20 V was applied between the negative and positive electrodes, and energized for 10 minutes.
Metallic copper was deposited on the surface of the cathode, and persulfate ions were confirmed from the solution in the anode chamber. The purity of metallic copper was 99.99%, and it was confirmed that the solution in the anode chamber was an ammonium persulfate solution having a concentration of 80 g / L. In the cathode chamber, ammonium persulfate, which is an oxidizing agent, was reduced to ammonium sulfate.

Subsequently, the cathode and the diamond electrode were taken out from the respective chambers, and a bag filled with the pulverized metal-containing material prepared in the same manner as above was immersed in the solution in the chamber used as the anode chamber and stirred well. A solution containing copper ions was prepared. Then, a newly prepared platinum cathode is installed in the solution, the diamond electrode is installed in the other solution containing a large amount of the oxidant in a reduced state, and a voltage of 20 V is applied between the two electrodes. Then, the energization process was performed for 10 minutes.
Similar to the first energization treatment, 99.99% pure copper was deposited on the surface of the cathode, and the solution in the anode chamber was regenerated by the oxidizing agent to become an ammonium persulfate solution having a concentration of 80 g / L. It was.

  When the same operation as this was repeated, it was confirmed that even after 100 cycles, it could be used continuously without changing the treatment liquid.

(Example 2)
In the same manner as in Example 1, the same metal-containing pulverized material as used in Example 1 was packed in a bag.
To 1 L of 6N sulfuric acid, 0.1 L of 30% hydrogen peroxide solution was added and stirred. The bag prepared above was immersed in the solution and stirred well using a stirrer to prepare a solution containing copper ions.
Except that the solution in the anode chamber was changed to sulfuric acid (6N), the same cation exchange membrane, cathode and diamond electrode as in Example 1 were prepared and set, and a voltage of 20 V was applied between both electrodes. The energization process was performed for 10 minutes.
It was confirmed that 99.99% pure copper was deposited on the surface of the cathode, and that the solution in the anode chamber was sulfuric acid / hydrogen peroxide having a hydrogen peroxide concentration of 0 g / L.

Subsequently, the cathode and the diamond electrode are taken out from the respective chambers, and a bag filled with a pulverized metal-containing material prepared in the same manner as in Example 1 may be immersed in the solution in the chamber used as the anode chamber. Stirring to prepare a solution containing copper ions. Then, a newly prepared platinum cathode is installed in the solution, the diamond electrode is installed in the other solution containing a large amount of the oxidant in a reduced state, and a voltage of 20 V is applied between the two electrodes. Then, the energization process was performed for 10 minutes.
Similar to the first energization treatment, 99.99% pure copper is deposited on the surface of the cathode, and the solution in the anode chamber is regenerated with an oxidizing agent to become sulfuric acid / hydrogen peroxide with a concentration of 5 g / L. It was.
When the same operation was repeated, it was confirmed that the amount of H ₂ O ₂ as an oxidant had decreased after 20 cycles. Therefore, 0.1 L of hydrogen peroxide having a concentration of 30% was added. The same operation was repeated.
By replenishing hydrogen peroxide in a timely manner, it was confirmed that the treatment solution did not reach the end of its life even after 100 cycles and could be used continuously. The added hydrogen peroxide becomes water as the copper dissolves. However, since the evaporation of water occurs, the volume is apparently the same as before the addition of the hydrogen peroxide solution and can be balanced.

(Example 3)
As a metal-containing material, an alloy terminal material consisting of 80% copper, the remaining 19% nickel, and 1% silicon is packed in a bag made of polypropylene nonwoven fabric, and the metal is dissolved and deposited in the same manner as in Example 1. Went.
As a result, when electrolysis was performed at a voltage of 20 V, copper having a purity of 99.99% was deposited on the surface of the cathode (made of Pt) and recovered. Silicon was recovered as a SiO ₂ powder with a filtration filter.
When the recovery of copper was completed, the cathode was replaced with a new one and the voltage was raised to 30 V. As a result, nickel was deposited on the cathode surface with a purity of 99.9% or more and recovered.
Furthermore, it was confirmed that the oxidant can be regenerated with respect to the electrolytic solution and can be repeatedly used in the same manner as in Example 1.

Example 4
As a metal-containing material, an alloy scrap having a copper purity of 1% and the balance of 99% nickel was packed in a bag made of polypropylene nonwoven fabric, and the metal was dissolved and deposited in the same manner as in Example 1.
As a result, as in Example 3, first, copper having a purity of 99.99% or more at 20 V was deposited on the surface of the cathode (made of Pt) and recovered. Furthermore, when the cathode was replaced and the voltage was raised to 30 V, it was confirmed that nickel could be collected by being deposited on the cathode surface with a purity of 99.95%, and the electrolyte solution could be used repeatedly. It was done.

(Example 5)
Alloy scraps having a copper purity of 80% and the balance of zinc as the metal-containing material were packed in a bag made of polypropylene nonwoven fabric, and the metal was dissolved and precipitated in the same manner as in Example 1.
As a result, as in Example 3, first, copper having a purity of 99.9% was deposited at 20 V on the surface of the cathode (made of Pt) and recovered. Furthermore, when the cathode was replaced and the voltage was increased to 40 V, zinc with a purity of 99.9% or more could be recovered by being deposited on the cathode surface with intense gas generation. It was confirmed that it can be used.

(Comparative Example 1)
In the same manner as in Example 1, the same metal-containing pulverized material as used in Example 1 was packed in a bag.
To 1 L of 6N sulfuric acid, 60 g of ammonium persulfate was added and stirred until completely dissolved. Furthermore, the bag filled with the pulverized metal-containing material prepared above was immersed in the solution, and stirred well using a stirrer to prepare a solution containing copper ions.
In the solution containing copper ions, the same cathode and diamond electrode as in Example 1 were installed, and a voltage of 20 V was applied between the two electrodes, followed by energization treatment for 10 minutes. 99% metallic copper was deposited.
Subsequently, the cathode was replaced with a new one, and a bag filled with the pulverized metal-containing material was put in the solution, and stirred well using a stirrer to prepare a solution containing copper ions. In the same manner as described above, a voltage of 20 V was applied between the two electrodes, and an energization process was performed for 10 minutes. As a result, as in the first time, 99.99% pure metallic copper was deposited on the cathode surface.

When the same operation was repeated, it took a long time to dissolve the copper as the cycle was repeated, and it was not possible to dissolve the copper at the 20th cycle. When the solution was investigated, the amount of ammonium persulfate was decreased and the concentration was 6 g / L.
Therefore, ammonium persulfate was added every 20 cycles, and the same operation was repeated. However, at the 60th cycle, ammonium persulfate was not dissolved due to an increase in sulfate ions, and the amount of precipitates increased. For this reason, the operation cannot be continued unless the treatment liquid is replaced.

(Comparative Example 2)
The apparatus was set up in the same manner as in Example 1 except that a platinum anode was used instead of the diamond electrode.
When a voltage of 20 V was applied between the electrodes and energized for 10 minutes, 99.99% pure copper was deposited on the surface of the cathode, but no persulfate ions were generated in the anode chamber. It was.
Further, when the operation was repeated in the same manner as in Example 1, copper could not be dissolved in the 15th to 20th cycles.
Although the operation was continued while adding ammonium persulfate in the same manner as in Comparative Example 2, the ammonium persulfate became insoluble at the 50th cycle and the liquid life was reached.

  According to the present invention, a highly pure metal can be obtained efficiently even from waste such as scrap recovered from the market.

Claims (8)

With a cation exchange membrane, a cathode chamber with a cathode, an anode chamber with a plate-like diamond electrode,
Of the electrolytic cell partitioned into
Supplying a solution containing metal ions to the cathode chamber;
Supplying a solution containing an oxidant in a reduced state to the anode chamber;
The cathode and the diamond electrode are arranged to face each other through the cation exchange membrane,
A voltage of 20 V or more and 40 V or less is applied between the cathode and the diamond electrode, the metal is deposited on the cathode surface in the cathode chamber, and the oxidant in the solution is regenerated in the anode chamber. Metal manufacturing method. The solution containing the metal ions is
The method for producing a metal according to claim 1, wherein the metal is obtained by adding a metal-containing material to an electrolytic solution containing at least the oxidizing agent and dissolving the metal in the electrolytic solution. The solution containing the metal ions is
What stuffed one or more pulverized materials selected from the group consisting of electric wires, printed circuit boards, semiconductors, motors, shredder dust for automobiles, and electronic devices containing metals into a water-permeable bag, at least the oxidizing agent. The method for producing a metal according to claim 1, wherein the metal is obtained by adding the mixture to an electrolyte solution and stirring the solution.   4. The solution according to claim 1, wherein the metal ion-containing solution contains at least one metal ion selected from the group consisting of copper, nickel, and zinc. 5. Metal manufacturing method.   5. The method for producing a metal according to claim 1, wherein the metal deposited on the cathode surface is copper, nickel, or zinc. The oxidizing agent is, method for producing a metal according to any one of claims 1 to 5, wherein the ammonium persulfate or peroxide Hydrogen.   The method for producing a metal according to claim 6, wherein the oxidizing agent is ammonium persulfate.   The method for producing a metal according to claim 1, wherein the diamond electrode is obtained by forming a conductive diamond film on a silicon substrate by a CVD method.