JP7022331B2 - Copper removal electrolytic treatment method, copper removal electrolytic treatment equipment - Google Patents

Description

The present invention relates to a copper-removing electrolytic treatment method in a process for producing electric nickel by an electrolytic sampling method from a copper-containing nickel chloride solution, and a copper-removing electrolytic treatment apparatus used for the copper-removing electrolytic treatment.

As a hydrometallurgical process for recovering the target metal from nickel-containing sulfides, nickel matte and nickel-cobalt mixed sulfides (MS: mixed sulfide, also simply referred to as "nickel sulfides"), which are raw materials, are leached out with chlorine. There is a method of removing impurities from the leachate and recovering electric nickel and electric cobalt in an electrolytic step.

For example, as shown in FIG. 7, the chlorine leaching solution (copper-containing nickel chloride solution) obtained in the chlorine leaching step is a surplus copper in the copper removal electrolysis step (not shown) provided between the cementation step and the cementation step. Is removed (see, for example, Patent Documents 1 to 3), and after impurities such as iron and arsenic are removed in the iron removal step, the solution is sent to a cobalt solvent extraction step.

In the cobalt solvent extraction step, nickel and cobalt are separated by solvent extraction to obtain a nickel chloride solution (NiCl ₂ ) and a cobalt chloride solution (CoCl ₂ ). Impurities are further removed from the nickel chloride solution in the purification process to obtain high purity, and the solution is sent to the nickel electrolysis process, where electrowinning produces electrolytic nickel. Further, the cobalt chloride solution is also sent to the cobalt electrowinning step after further removing impurities in the purification step to have high purity, and electrowinning produces electric cobalt.

By the way, in the copper decopper electrolysis step, conventionally, a part of the chlorine leachate is supplied to the decopper electrolysis facility as the starting liquid of the decopper electrolysis treatment, and copper is deposited and removed on the cathode side.

The copper contained in the chlorine leachate is mainly divalent copper ion (Cu ²⁺ ), and on the cathode side, the reaction represented by the following formula (1) mainly occurs and copper is electrodeposited.
Cu ²⁺ + ^2e- → Cu ⁰ ... (1)

Here, Patent Document 4 discloses a technique for removing copper from a copper-containing nickel chloride aqueous solution by executing a two-step cementation process as a technique for improving the cementation step in the electrolytic nickel manufacturing process. Has been done. According to this method, in the first cementation step, nickel sulfide is added to the chlorine leachate to reduce the divalent copper ions in the chlorine leachate to monovalent copper ions, followed by the second cementation step. By adding a nickel mat and a chlorine leaching residue, the monovalent copper ion can be immobilized in the form of a sulfide, and copper can be efficiently and effectively removed from the chlorine leaching solution.

The applicant of the present invention is a part of the final reaction liquid obtained through the first cementation step in the copper removal electrolysis step of performing the copper removal electrolysis treatment on the premise of the method of executing such a two-step cementation treatment. Is proposed (Japanese Patent Application No. 2017-105799). As described above, in the two-step cementation treatment, in the first cementation step, a reaction of mainly reducing the divalent copper ion in the chlorine leachate to the monovalent copper ion occurs. Therefore, most of the copper ions contained in the final reaction liquid obtained through the reaction in the first cementation step are in the form of monovalent copper ions.

From this, by using a part of the reaction final solution obtained through the first cementation step as the treatment start solution (electrolyte solution) in the copper removal electrolysis step, the reaction represented by the following formula (2) on the cathode side. Can be efficiently generated, and the current efficiency in the copper removal electrolysis treatment, that is, the recovery efficiency per current can be improved to about twice that of the conventional method (reaction of the above formula (1)). .. The reaction represented by the following formula (3) occurs on the anode side.
Cathode side ^: Cu ⁺ + e- → Cu ⁰ ... (2)
Anode side ^: 2Cl- → Cl ₂ + 2e -... ⁽ 3)

Japanese Unexamined Patent Publication No. 11-80986 Japanese Unexamined Patent Publication No. 2001-262389 Japanese Unexamined Patent Publication No. 2016-89259 Japanese Unexamined Patent Publication No. 2012-26027

As described above, in the treatment in the copper removal electrolysis step, the current efficiency is effectively improved by using a part of the reaction final liquid obtained from the first cementation step as the starting liquid of the copper removal electrolysis treatment. Can be done.

However, as the current efficiency of the electrolytic treatment improves, the rate of formation of copper powder electrodeposited on the surface of the cathode also increases. The copper powder electrodeposited on the surface of the cathode shows a shape called dendrite-like or dendritic-like. This copper powder is intermittently blown off by a means such as a beam dropping method using an air cylinder, collected at the bottom of the copper removal electrolytic cell, and intermittently extracted as a copper powder slurry. However, as described above, when a part of the reaction final solution obtained from the first cementation step is used as the starting solution for the copper removal electrolysis treatment, the production rate of copper powder increases, and therefore, for example, it is removed. Even if measures such as doubling the frequency are taken, there still arises a problem that copper powder remains on the surface of the cathode and grows to the vicinity of the surface of the anode provided opposite to each other. Such growth of copper powder is also referred to as "abnormal growth of copper grains". Abnormal growth of copper particles causes a short circuit between the electrodes, so it is necessary to stop the energization of the electrolytic cell (power failure) and manually remove the copper particles grown on the cathode surface. Become.

The power failure operation of the electrolytic cell due to the removal of the copper particles significantly reduces the operating rate of the electrolytic cell (the energization time rate of the electrolytic cell). Further, the copper grain removing work increases the work load in the copper removal electrolysis treatment operation, in other words, lowers the work efficiency. Further, if the copper particles are dropped to the bottom of the tank without darkness during the copper grain removal work, another trouble of blocking the bottom punching valve at the bottom of the copper-removing electrolytic cell may occur. The operating rate of the electrolytic cell refers to the ratio of the actual energization time when the energization time is 100% when the energization is continued for one day.

The present invention has been proposed in view of such circumstances, and in the copper removal electrolysis treatment in the copper removal electrolysis step, problems such as short circuit due to abnormal growth of copper particles occur while maintaining high current efficiency. And provide a method that can prevent a decrease in work efficiency.

As a result of diligent studies, the present inventors have subjected to copper removal electrolysis treatment of a part of the reaction final solution obtained through the first cementation step in the electronickel manufacturing process in which the two-step cementation treatment is performed. In the copper removal electrolysis treatment used as the starting liquid of the above-mentioned treatment, by controlling the surface roughness of the negative electrode provided in the electrolytic cell, the residual copper powder on the negative electrode surface is suppressed and the fall from the negative electrode is promoted. It was found that the present invention could be solved, and the present invention was completed.

(1) The first invention of the present invention is decopper electrolysis in the process of producing electric nickel by an electrolytic sampling method from a copper-containing nickel chloride solution obtained by subjecting nickel sulfide to a chlorine leaching treatment. In the process for producing electrolytic nickel, nickel sulfide is added to the copper-containing nickel chloride solution, and at least the divalent copper ions in the copper-containing nickel chloride solution are reduced to monovalent copper ions. To the slurry obtained through the first electrolysis step and the first electrolysis step, a nickel mat and the chlorine leaching residue obtained by the chlorine leaching treatment are added, and the monovalent copper contained in the slurry is added. Including a second cementation step of immobilizing ions as sulfide and a cementation step having, in the decopper electrolysis treatment, the surface is composed of a metal containing titanium and copper is deposited. Ra) is 0.2 μm to 1.2 μm, and the maximum height (Rz) is 1.2 μm to 6.0 μm. This is a decopper electrolysis treatment method in which a part of the reaction final liquid obtained through the cementation step is supplied as a decopper electrolysis starting liquid to perform the decopper electrolysis treatment.

(2) In the second invention of the present invention, in the first invention, the electrolytic treatment is performed with the redox potential (based on the silver / silver chloride electrode) of the copper removal electrolytic treatment starting solution in the range of 300 mV to 470 mV. It is a copper electrolysis treatment method.

(3) The third invention of the present invention is decopper electrolysis in the process of producing electric nickel by an electrolytic sampling method from a copper-containing nickel chloride solution obtained by subjecting nickel sulfide to a chlorine leaching treatment. It is a decopper electrolysis treatment device that executes the treatment, and is provided with an electrolytic tank having an electrode pair consisting of a positive electrode and a negative electrode. It is a copper removal electrolysis treatment apparatus having a ra (Ra) of 0.2 μm to 1.2 μm and a maximum height (Rz) of 1.2 μm to 6.0 μm.

(4) In the third invention, the fourth invention of the present invention is to add a nickel sulfide to the copper-containing nickel chloride solution in the process of producing electronick nickel, and at least in the copper-containing nickel chloride solution. A nickel mat and a chlorine leaching residue obtained by the chlorine leaching treatment are added to the slurry obtained through the first electrolysis treatment for reducing divalent copper ions to monovalent copper ions and the first cementation treatment. A two-step cementation treatment consisting of a second cementation treatment for adding and immobilizing the monovalent copper ion contained in the slurry as a sulfide and a two-step cementation treatment consisting of the addition is performed, and the electrolytic tank is subjected to the cementation treatment. It is a decopper electrolysis treatment apparatus in which a part of the reaction final liquid obtained through the first cementation treatment is supplied as a decopper electrolysis treatment starting liquid.

According to the present invention, in the copper removal electrolysis treatment in the copper removal electrolysis step, it is possible to effectively prevent the occurrence of problems such as short circuit due to abnormal growth of copper particles and the decrease in work efficiency while maintaining high current efficiency. can.

It is a process diagram which shows the flow of the manufacturing process of electric nickel which manufactures electric nickel from a copper-containing nickel chloride solution. It is a schematic process diagram which shows the flow of the copper removal electrolysis processing in the manufacturing process system of electric nickel. It is a photographic figure which shows the state of the precipitation growth of the copper grain on the negative electrode surface. It is a schematic diagram which shows the outline of the structure of the processing equipment including the copper removal electrolysis processing apparatus. It is sectional drawing of the copper removal electrolysis test apparatus used in an Example and a comparative example, and is the simplified figure which shows the structure of the apparatus which provided with the electrode pair which consists of a positive electrode and a negative electrode. It is a photographic figure which showed the state of the negative electrode surface before energization and the state of the negative electrode surface after energization for 3 hours in the decopper electrolysis treatment of Example 1 and Comparative Example 1. It is the whole process diagram of the wet smelting process.

Hereinafter, a specific embodiment of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be changed without changing the gist of the present invention. Further, in the present specification, the notation "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

≪1. Copper removal electrolysis method (copper removal method) ≫
The copper removal electrolysis treatment method according to the present invention is a method of electrowinning and removing copper from a copper-containing nickel chloride solution (copper-containing nickel chloride solution). More specifically, this method is a copper-removing electrolytic treatment in a copper-removing electrolytic step in an electric nickel manufacturing process for producing electric nickel by an electrolytic sampling method from a copper-containing nickel chloride solution obtained by leaching nickel sulfide with chlorine. The method.

<1-1. Overview of copper removal and electrolysis process in electric nickel manufacturing process>
(Copper removal electrolysis process)
FIG. 1 is a process diagram showing a flow of an electric nickel manufacturing process for producing electric nickel from a copper-containing nickel chloride solution. In the process of producing electric nickel, copper and nickel contained in raw materials such as nickel sulfide and nickel mat are leached by the chlorine leaching treatment (chlorine leaching step S1), and then become a copper-containing nickel chloride solution, which is contained. The copper nickel chloride solution goes through each treatment step and becomes an electrolytic solution for electrolytically sampling (electrolytic step S5) to produce electric nickel. Then, in the process of this manufacturing process, the copper contained in the copper-containing nickel chloride is fixed as a sulfide (cementation steps S2 and S3), and a process of separating the nickel and copper in the copper-containing nickel chloride solution is performed. ..

The cementation residue containing copper sulfide obtained through the cementation steps (S2 and S3) is again subjected to the chlorine leaching treatment (chlorine leaching step S1) to be subjected to the leaching treatment. On the other hand, the cementation final liquid obtained through the cementation steps (S2, S3) is then subjected to a purification treatment for removing impurities (cleaning step S4), and becomes an electrolytic solution for nickel electrowinning. ..

As described above, in the process of producing electric nickel from the copper-containing nickel chloride solution, copper derived from the raw material circulates in the process system while maintaining a certain predetermined concentration. Copper acts to efficiently leach nickel in the raw material during the chlorine leaching process. That is, in the chlorine leaching treatment, the copper in the raw material is oxidized by the blown chlorine gas to become divalent copper ions, and the nickel in the raw material is leached by the oxidative leaching by the divalent copper ions. Therefore, copper plays an important role as an leaching agent for effectively and stably leaching nickel in the raw material.

In the electrolytic nickel manufacturing process, copper contained in the raw material is stored in the process system and a large amount of copper is circulated as a chlorine leachate and cementation residue, but the amount of copper circulated in the system is kept appropriate. For that purpose, it is necessary to extract the amount of copper corresponding to the copper newly supplied from the raw material from the system.

Therefore, in such an electric nickel manufacturing process, a process of electrolytically collecting and removing a part of the copper circulating in the system (decopper electrolytic process) is performed.

(Starting liquid for copper removal electrolysis treatment)
FIG. 2 is a schematic process diagram showing the flow of copper removal electrolysis treatment in the electric nickel manufacturing process system. As shown in FIG. 2, in the present embodiment, in the process of producing electric nickel, a cementation treatment for immobilizing copper in a copper-containing nickel chloride solution as a sulfide is performed in two steps (step of FIG. 1). (Refer to the figure). Used as a liquid. According to such a method, the capacity of the copper removal electrolysis treatment can be improved and the amount of copper removal can be effectively increased without incurring equipment costs and the like.

Specifically, in the two-step cementation treatment in the electronickel manufacturing process, as shown in FIG. 1, nickel sulfide is added to the copper-containing nickel chloride solution, and at least the divalent in the copper-containing nickel chloride solution is added. A nickel mat and a chlorine leaching treatment (chlorine leaching step S1) are applied to the slurry obtained through the first step (first cementation step S2) for reducing copper ions to monovalent copper ions and the first step. It is composed of a second step (second cementation step S3) in which the obtained chlorine leaching residue is added and the monovalent copper ion contained in the slurry is immobilized as a sulfide.

In the first cementation step S2 in the two-step cementation treatment, it is obtained by adding nickel sulfide to the copper-containing nickel chloride solution as shown in the following formulas (4) and (5). Reaction A reaction occurs in which most of the copper ions in the final solution are reduced to monovalent copper ions. This is because NiS, which is the main form in nickel sulfide, has a weak reducing power and the effect of fixing monovalent copper ions as copper sulfide is unlikely to appear. Therefore, mainly divalent copper ions in the solution are monovalent copper. This is due to the progress of the reaction of reducing to ions.
4NiS + 2Cu ²⁺ → Ni ²⁺ + Ni ₃ S ₄ + 2Cu ⁺ ... (4)
NiS + 2Cu ²⁺ → Ni ²⁺ + 2Cu ⁺ + S ⁰ ... (5)

Then, a part of the reaction final liquid obtained through the first cementation step S2 is transferred to the decopper electrolysis step and used as the decopper electrolysis start liquid to perform the electrolysis treatment. Since most of the copper ions in the final solution of the reaction are in the state of monovalent copper ions, the current efficiency in the decopper electrolysis treatment represented by the divalent copper ion standard can be improved about twice. ..

Here, the current efficiency in the decopper electrolysis treatment is based on "divalent copper ions", and for example, the ratio of the actual electrodeposition amount (kg / day) to the theoretical electrodeposition amount (kg / day) of copper per day. It is represented by.
Current efficiency (%) = actual electrodeposition amount (kg / day) ÷ theoretical electrodeposition amount (kg / day) x 100

Conventionally, in this decopper electrolysis step, a part of the chlorine leachate obtained in the chlorine leaching step S1 has been used as the starting liquid for the decopper electrolysis treatment. In the present embodiment, as described above, a part of the reaction final solution obtained through the first cementation step S2 containing copper ions in the state of monovalent copper ions is used as the starting solution for the copper removal electrolysis treatment. Since it is used, the current efficiency can be improved to about twice as much as that of the conventional method.

(Conditions for the starting solution of electrolytic treatment)
In the copper removal electrolysis treatment, the reaction final liquid obtained through the first cementation step S2 is subjected to a solid-liquid separation treatment to remove solids such as nickel sulfide contained in the solution, and the solid content is removed. It is preferable to use the solution from which the above is removed as the starting solution.

Further, as the decopper electrolytic treatment starting solution, a redox potential (ORP) (based on silver / silver chloride electrode) preferably in the range of 300 mV or more and 470 mV or less, more preferably in the range of 320 mV or more and 450 mV or less may be used. preferable. By using a solution of ORP belonging to such a range as the starting solution for the copper removal electrolysis treatment, copper can be electrowinned and removed more efficiently.

Here, in the decopper electrolysis treatment, when a part of the reaction final solution extracted from the first cementation step S2 is supplied to the electrolytic cell as the decopper electrolysis initial solution, the reaction final solution is predetermined. It may be stored in a tank to adjust the state of the solution (preparation). Specifically, prior to supplying the reaction final solution to the decopper electrolytic treatment, the reaction final solution is charged and stored in a predetermined tank (decopper supply liquid adjusting tank), and a reducing agent is appropriately added. The solution may be prepared so that the ORP of the solution is in the range of 300 mV or more and 470 mV or less.

Further, the liquid temperature of the starting liquid for the copper removal electrolysis treatment supplied to the copper removal electrolysis treatment is preferably about 60 ° C. to 70 ° C. Since the reaction final solution obtained through the first cementation step S2 has a temperature of about 80 ° C. after recovery, the temperature of the reaction final solution is preferably lowered to about 60 ° C. to 70 ° C. To. As a result, the solid content in the solution can be separated by using a solid-liquid separation device such as a filter press, and the operation efficiency can be improved. If the temperature drops to this extent, it is possible to cool naturally, but for example, select a simple method such as temporarily storing the extracted reaction final liquid (process liquid) in a tank equipped with cooling means. Is more preferable.

<1-2. Specific method of copper removal electrolysis treatment in copper removal electrolysis process>
(Decopper electrolytic treatment method)
In the copper removal electrolysis treatment in the copper removal electrolysis step, as described above, a part of the reaction final liquid obtained through the first cementation treatment in the cementation step in which the two-step cementation treatment is performed is used as the starting solution for the electrolytic treatment. The copper is removed and electrolyzed. This copper removal electrolysis treatment is performed by an electrolysis treatment apparatus in which a plurality of electrolytic cells having an electrode pair consisting of a positive electrode and a negative electrode are provided in parallel with the liquid supply. Therefore, a part of the final reaction liquid obtained through the first cementation treatment is supplied in parallel to each of the electrolytic cells constituting the electrolytic cell, and the copper removal electrolysis treatment is performed in each electrolytic cell. ..

By this copper removal electrolysis treatment, copper powder having a dendrite-like or dendritic shape is deposited on the surface of the negative electrode provided in each electrolytic cell, while chlorine gas is generated at the positive electrode.

Here, FIG. 3 is a photographic view showing the state of abnormal growth of copper particles on the surface of the negative electrode. FIG. 3 is a photographic view when the bottom punching valve is opened to discharge the copper powder accumulated on the bottom of the tank and the liquid level in the electrolytic cell is temporarily lowered, and the plate-like body on the left side of the drawing is shown. The negative electrode is the negative electrode, and the positive electrode is visible on the right side. As shown in this photographic diagram, it can be seen that the copper particles grow from the surface of the negative electrode toward the surface of the opposite positive electrode.

In the decopper electrolysis treatment using the reaction final solution obtained through the first cementation treatment as the starting solution for the decopper electrolytic treatment, the electrolytic treatment is performed with high current efficiency based on the monovalent copper ions present in the solution. Will be possible. However, due to the high current efficiency, the reaction of the electrolytic treatment, that is, the precipitation reaction of copper on the surface of the negative electrode proceeds, so that the rate of copper precipitation growth also increases. When the rate of copper precipitation growth increases as the current efficiency improves, the copper powder deposited in the form of dendrites on the surface of the negative electrode grows to the vicinity of the adjacent positive electrode and becomes copper particles. Is more likely to cause a short circuit.

Therefore, in the decopper electrolysis treatment according to the present embodiment, an electrolytic device for executing the decopper electrolysis treatment in which the roughness of the surface of the negative electrode is controlled is used. Specifically, it is composed of a metal containing titanium, and the arithmetic average roughness (Ra) of the surface on which copper is deposited is in the range of 0.2 μm to 1.2 μm, and the maximum height (Rz) is in the range of 1.2 μm to 1.2 μm. An electrolytic cell equipped with a negative electrode and a positive electrode having a range of 6.0 μm is used, and a part of the reaction final solution obtained through the first cementation treatment is supplied to the electrolytic cell as the decopper electrolysis treatment starting solution. It is characterized by being liquid and subjected to copper removal electrolysis treatment. The above-mentioned arithmetic mean roughness (Ra) and maximum height (Rz) are based on the definitions according to JIS B0601: 2001.

According to such a method, since the roughness of the surface of the negative electrode on which copper is deposited is controlled within a specific range, the residual copper powder on the surface of the negative electrode is suppressed. Then, at the stage where the copper powder is deposited and grown on the surface of the negative electrode by the electrolytic treatment, the copper powder is likely to fall due to its own weight, and the copper particles are close to the surface of the opposite positive electrode due to excessive growth (abnormal growth). It is possible to prevent abnormal growth of copper and prevent the occurrence of defects such as short circuits. In addition, since the copper powder tends to fall naturally due to its own weight, it is not necessary to stop the energization and scrape off the copper particles deposited and grown on the negative electrode according to the degree of precipitation and growth of the copper particles. Can be improved.

Here, examples of the titanium-containing metal constituting the negative electrode include a metal made of titanium alone and an alloy containing titanium.

As for the surface roughness of the negative electrode composed of a metal containing titanium, the arithmetic mean roughness (Ra) is in the range of 0.2 μm to 1.2 μm, preferably 0.4 μm to 1 as described above. The range is 0.0 μm. The maximum height (Rz) is in the range of 1.2 μm to 6.0 μm, preferably in the range of 2.0 μm to 5.0 μm.

When Ra exceeds 1.2 μm or Rz exceeds 6.0 μm, the surface of the negative electrode becomes too rough, the adhered copper powder to the surface of the negative electrode becomes strong, and the peelability deteriorates. In this case, copper powder tends to remain on the surface of the negative electrode, so that abnormal growth of copper particles tends to occur with the electrolytic treatment. Then, the possibility that the copper particles reach the surface of the facing positive electrode and cause a problem such as a short circuit increases. Further, when removing the abnormally grown copper particles, it is necessary to stop the energization of the electrolytic cell and scrape it off.

Therefore, on the surface of the negative electrode, by controlling the surface roughness so that the Ra value is 1.2 μm or less and the Rz value is 6.0 μm or less, the residual copper powder is suppressed and it is natural. It can be made easy to fall.

Regarding the lower limit of the surface roughness, if Ra is less than 0.2 μm or Rz is less than 1.2 μm, the process corresponds to the so-called mirror polishing process, which requires a special processing technique. Further, in the copper removal electrolysis operation, the surface of the negative electrode is chemically and mechanically slightly scratched, so that the smoothing treatment more than necessary becomes meaningless. Therefore, by setting the Ra value in the range of 0.2 μm to 1.2 μm and the Rz value in the range of 1.2 μm to 6.0 μm, the copper powder is satisfactorily deposited by the electrolytic treatment, while the negative electrode of the copper powder is deposited. Excessive growth on the surface can be suppressed.

The arithmetic mean roughness (Ra) and maximum height (Rz) can be measured according to JIS B0601: 2001. For the measurement, for example, a commercially available differential inductance type surface roughness meter can be used.

The surface roughness of the negative electrode can be adjusted by performing a polishing process using a polishing device or the like when the surface roughness of the base plate is smoothed. On the other hand, when the surface roughness of the base plate is made rougher than the surface roughness, it can be performed by performing a shot blasting process, a grid blasting process, or the like.

(Recovery of copper powder)
By performing the copper removal electrolysis treatment by the method as described above, copper in the solution can be recovered as copper powder while maintaining high current efficiency, and abnormal growth of copper particles at the negative electrode can be suppressed. It is possible to prevent the occurrence of problems such as short circuits.

The copper powder deposited on the surface of the negative electrode by the electrolytic treatment is removed from the surface of the negative electrode by intermittently applying a drop vibration by, for example, a wiping means consisting of a cylinder provided on the upper part of the negative electrode. Can be recovered by. As the wiping means, in addition to the method of vibrating the negative electrode, a method of inserting a scraper into the electrolytic solution between the positive electrode and the negative electrode to reciprocate, and a forced stirring method such as bubbling are also possible.

The copper powder recovered by such a method is collected in the bottom of the electrolytic cell formed in the shape of an inverted quadrangular pyramid, and can be taken out from the electrolytic cell by opening the bottom punching valve. At this time, since the copper powder is in the form of a slurry mixed with a nickel chloride solution, washing water, or the like, only the copper powder can be recovered by subjecting the copper powder slurry to a solid-liquid separation treatment. .. The solid-liquid separation treatment can be performed by a known method such as a filtration treatment, and the copper powder and the decoppered filtrate are separated by this treatment. The recovered copper powder can be discharged out of the system, and the decoppered filtrate after separating the copper powder can be returned to the cementation step.

In the present embodiment, since the roughness of the surface of the negative electrode on which copper is deposited is controlled within a specific range, it is possible to suppress the strong residue of copper powder. Therefore, the work load can be effectively reduced even when the negative electrode plate is maintained and maintained.

≪2. Copper removal electrolysis treatment equipment ≫
Next, the decopper electrolysis treatment apparatus that performs the above-mentioned decopper electrolysis treatment will be described.

<2-1. Configuration of processing equipment including copper removal electrolysis processing equipment>
FIG. 4 is a diagram schematically showing the configuration of a processing facility including a copper removal electrolysis processing device. The processing equipment (whole) is indicated by reference numeral 1. The processing equipment 1 includes a decopper electrolysis treatment device 2 for performing decopper electrolysis treatment, and a start liquid storage tank group 3 for accommodating the decopper electrolysis start liquid to be supplied to the decopper electrolysis treatment device 2. ing.

[Decopper electrolysis treatment equipment]
The copper-removing electrolysis treatment device 2 is composed of an electrolytic cell 21 for performing the copper-removing electrolysis treatment. Specifically, in the copper removal electrolysis treatment device 2, a plurality of electrolytic cells 21 (21a to 21d) are provided in parallel with the liquid supply. Although not shown, each electrolytic cell 21 is provided with one or a plurality of electrode pairs composed of a positive electrode and a negative electrode. The number of electrolytic cells 21 provided in parallel is not particularly limited, and FIG. 4 shows an embodiment in which four electrolytic cells are provided as an example, but only one. Alternatively, a plurality of tanks of 5 or more may be provided in parallel.

Each electrolytic cell 21 contains, as an electrolytic solution, a decopardized electrolytic cell starting solution (reaction final solution obtained through the first cementation treatment) from the initial solution accommodating tank group 3 described later, and is composed of a positive electrode and a negative electrode. An electrolytic reaction is caused by passing a DC current through the electrode pair.

In the electrolytic cell 21, the positive electrode and the negative electrode are provided so as to face each other.

The positive electrode provided in the electrolytic cell 21 is, for example, an insoluble electrode, and for example, a chlorine generation electrode having an active film of a platinum group oxide formed (coated) on the surface of a titanium substrate can be used. At this positive electrode, chloride ions (Cl ⁻ ) in the electrolytic solution are oxidized to generate chlorine gas (2Cl ⁻ → Cl ₂ + 2e ⁻ ). The positive electrode is housed in a resin frame such as FRP (fiber reinforced plastic), and the outer periphery of the frame is covered with a filter cloth that allows the electrolytic solution to pass through to form an anode box. Instead of the filter cloth, an ion exchange membrane may be interposed to allow only a specific electrolyte to permeate. This anode box has a structure closed by a frame and a filter cloth or an ion exchange membrane, and the inside of the anode box is adjusted to a negative pressure with respect to an external pressure, and chlorine gas and an electrolytic solution are sucked and discharged. It has become. Therefore, the chlorine gas generated from the surface of the positive electrode does not leak to the outside from the anode box.

The negative electrode provided in the electrolytic cell 21 is made of a metal plate containing titanium. In this negative electrode, copper in the electrolytic solution is deposited on the surface of the negative electrode as dendrite-like copper powder during the electrolytic treatment. Here, in the present embodiment, the roughness of the surface of the negative electrode made of the metal plate containing titanium is in the range of 0.2 μm to 1.2 μm in arithmetic average roughness (Ra), and the maximum height ( Rz) is controlled in the range of 1.2 μm to 6.0 μm. According to the electrolytic cell 21 provided with such a negative electrode, abnormal growth of copper particles can be suppressed even when the copper removal electrolysis treatment is performed with high current efficiency, that is, at a high electrodeposition speed.

A liquid supply pipe 11 for supplying the starting liquid of the decopper electrolysis treatment into the tank is connected to the electrolytic cell 21. The other end of the liquid supply pipe 11 is connected to a starting liquid storage tank group 3 for storing the starting liquid for copper removal electrolysis treatment. As shown in the schematic diagram of FIG. 4, the liquid supply pipe 11 can be configured by a branch pipe branched at a predetermined position, and a predetermined amount is provided for each of the electrolytic cells 21 constituting the copper removal electrolysis treatment device 2. Copper removal electrolysis treatment The starting liquid is supplied. The decopper electrolysis treatment starting liquid supplied by the liquid supply pipe 11 is a part of the reaction final liquid obtained through the first cementation step S2.

[Starting liquid storage tank group]
The starting liquid accommodating tank group 3 is a storage tank group for accommodating the target to be electrolytically treated in the electrolytic cell 21 in the decopper electrolysis treatment apparatus 2, that is, the decopper electrolysis treatment starting liquid. For example, as shown in FIG. 4, the starting liquid storage tank group 3 is composed of a relay tank 31 and a receiving tank 32.

The relay tank 31 is a tank for accommodating a part of the reaction final liquid obtained through the treatment in the first cementation step S2, and the reaction final liquid is used as the copper removal electrolytic treatment starting liquid to be a copper removal electrolytic treatment apparatus. It is a tank that acts as a relay for supplying liquid to 2.

The receiving tank 32 is a tank that temporarily receives the reaction final liquid as the copper removing electrolytic treatment starting liquid contained in the relay tank 31 before supplying the liquid to the copper removing electrolytic treatment apparatus 2. In the receiving tank 32, the concentration is adjusted, the redox potential (ORP) is adjusted, and the like, if necessary, prior to supplying the liquid to the decopper electrolysis treatment device 2.

The above-mentioned liquid supply pipe 11 is directly connected to the receiving tank 32. For example, the final reaction liquid obtained by adjusting the concentration or ORP in the receiving tank 32 is used as the starting liquid for copper removal electrolysis treatment. Liquid is supplied to the copper removal electrolysis treatment device 2 (electrolytic cell 21) via the liquid supply pipe 11.

<2-2. About the flow of copper removal electrolysis treatment in the treatment equipment>
In the processing equipment 1 having the above-described configuration, the copper removal electrolysis treatment is performed, for example, in the following flow.

That is, in the first cementation step S2 of the electric nickel manufacturing process, the chlorine leaching solution (copper-containing nickel chloride solution) obtained through the chlorine leaching treatment in the chlorine leaching step S1 is subjected to the cementing treatment. , A part of the reaction final solution of the first cementation treatment is accommodated in the relay tank 31 in the initial solution accommodating tank group 3. The final reaction solution contained in the relay tank 31 is a starting solution for the copper removal electrolysis treatment, and is a nickel chloride solution containing copper-containing chloride mainly containing monovalent copper ions as copper ions. It is a nickel solution.

The final reaction liquid contained in the relay tank 31 is then transferred to the receiving tank 32. In the receiving tank 32, a reducing agent or the like is added as necessary to adjust the ORP or the like. The starting liquid for the electrolytic treatment preferably has an ORP in the range of about 300 mV to 470 mV, and can be prepared by contacting it with metallic nickel as a reducing agent, for example.

The final reaction liquid prepared in the receiving tank 32 as necessary is used as the starting liquid for the copper-removing electrolysis treatment, and is used as the starting liquid for the copper-removing electrolysis treatment. Liquid is supplied to ~ 21d) respectively.

The electrolytic cell 21 constituting the copper removal electrolysis treatment device 2 is provided with an electrode pair composed of a positive electrode and a negative electrode, and is a reaction final liquid (first) which is the start liquid of the copper removal electrolysis treatment via the liquid supply pipe 11. When the final solution of the reaction obtained through the cementation process of No. 1 is supplied, an electrolytic reaction occurs by passing a DC current through the electrode pair.

In the electrolytic cell 21, simple copper is deposited on the surface of the negative electrode 52 by an electrolytic reaction using a nickel chloride solution containing monovalent copper ions as an electrolytic solution. Chlorine gas is generated at the positive electrode. This electrolytic reaction occurs in the electrolytic cell 21 constituting the copper removal electrolysis treatment device 2.

Conventionally, in an electrolytic cell, a decopper electrolysis treatment is performed using a reaction final solution, which is a nickel chloride solution containing monovalent copper ions, as a decopper electrolytic treatment starting solution, so that the electrolytic reaction proceeds with high current efficiency. .. Therefore, for example, as shown in the photograph of FIG. 3, the growth rate of the copper particles deposited on the surface of the negative electrode is also high, and so-called abnormal growth may occur in which the copper particles grow to the vicinity of the surface of the positive electrode facing the negative electrode.

On the other hand, in the electrolytic cell 21 constituting the copper removal electrolysis treatment device 2, since the roughness of the surface of the negative electrode is controlled within a specific range, the copper powder is strongly deposited while maintaining good precipitation. It is possible to suppress the residual material and prevent it from growing abnormally and becoming copper particles. As a result, it is possible to prevent the occurrence of defects such as short circuits, the occurrence of work for removing abnormally grown copper grains, and the deterioration of operating efficiency such as operating rate and work efficiency caused by the work.

Hereinafter, examples of the present invention will be described in more detail, but the present invention is not limited to the following examples.

[Example 1]
In Example 1, the copper removal electrolysis treatment test in the electric nickel manufacturing process was performed using the copper removal electrolysis test apparatus 22 whose configuration is schematically shown in FIG. The positive electrode 51 provided in the copper removal electrolysis test apparatus 22 is made of a copper plate 51a charged in a titanium net (titanium box) 51b, and the negative electrode 52 is a titanium plate 52a. The reason why the copper plate 51a is used for the positive electrode 51 here is to prevent chlorine gas from being generated from the positive electrode in the laboratory.

Specifically, in the process of producing electric nickel, nickel sulfide is added to the chlorine leaching solution (copper-containing nickel chloride solution) obtained from the chlorine leaching treatment (chlorine leaching step S1), and the solution is contained in the copper-containing nickel chloride solution. In the first treatment of reducing the divalent copper ion to the monovalent copper ion, nickel mat and chlorine leaching residue are added to the obtained slurry, and the monovalent copper ion contained in the slurry is immobilized as a sulfide. A two-step cementation process consisting of a second process and a two-step cementation process was performed. Then, a part of the final reaction liquid obtained from the first treatment (first cementation step S2) of the two-step cementation treatment was used as the feed liquid of the copper removal electrolysis test apparatus 22.

Then, the reaction final liquid as the start liquid of the copper removal electrolysis treatment was supplied to the copper removal electrolysis test apparatus 22 to execute the electrolytic treatment.

Here, in the copper removal electrolysis test apparatus 22, the roughness (surface roughness) of the surface 52s on which copper is deposited as the negative electrode 52 is 1.014 μm in arithmetic average roughness (Ra), and is the maximum height (). The Rz) of 5.987 μm was used. The surface roughness was measured using a small surface roughness measuring instrument (Surftest SJ-210) manufactured by Mitutoyo Co., Ltd. in accordance with JIS B0601: 2001. The copper concentration of the decopper electrolysis starting solution is 40 g / L, the ORP (silver / silver chloride electrode standard) is 405 mV, and the divalent copper ion ratio is calculated as Cu ²⁺ / (Cu ⁺ + Cu ²⁺ ) x 100%. It was 15%. The current density of the negative electrode was 557 A / m ² .

[Comparative Example 1]
In Comparative Example 1, the surface roughness (surface roughness) on which copper is deposited as the negative electrode in the electrolytic cell is 3.402 μm in arithmetic average roughness (Ra) and 17.083 μm in maximum height (Rz). Was used. Except for this, the electrolytic treatment was carried out in the same manner as in Example 1.

[evaluation]
FIG. 6 is a photographic diagram showing the state of the negative electrode surface before energization and the state of the negative electrode surface after energization for 3 hours in the decopper electrolysis treatment of Example 1 and Comparative Example 1.

As shown in this photographic diagram, in Comparative Example 1, it can be seen that the copper powder deposited on the surface of the negative electrode grows toward the facing positive electrode and remains on the negative electrode with a strong adhesive force. When the electrolytic treatment in Comparative Example 1 is continued, there is a high possibility that the grown copper particles come into contact with the surface of the positive electrode and a short circuit occurs.

On the other hand, in Example 1, although the copper powder adhered to the surface of the negative electrode, the amount of the copper powder adhered was clearly small, and it fell to the bottom of the electrolytic cell by its own weight with the electrolytic treatment. According to such an electrolytic treatment in Example 1, the deposited and grown copper powder naturally falls due to its own weight, so that abnormal growth of copper particles to the vicinity of the surface of the positive electrode is suppressed, and problems such as short circuit occur. It can be considered that the occurrence of can be effectively prevented.

In both the electrolytic treatments of Example 1 and Comparative Example 1, the current efficiency based on the divalent copper ion was as high as about 160%. The current efficiency of the electrolytic treatment was calculated by "current efficiency (%) = actual electrodeposition amount of copper (kg / month) ÷ theoretical electrodeposition amount (kg / month) x 100".

1 Processing equipment 2 Copper removal electrolysis treatment equipment 3 Starting liquid storage tank group 11 Liquid supply piping 21 (21a, 21b, 21c, 21d) Electrolysis tank 22 Copper removal electrolysis test equipment 31 Relay tank 32 Receiving tank 51 Positive electrode 52 Negative electrode 52s Negative electrode surface

Claims (3)

It is a method of decopperation electrolytic treatment in the manufacturing process of electric nickel for producing electric nickel by an electrowinning method from a copper-containing nickel chloride solution obtained by subjecting nickel sulfide to chlorine leaching treatment.
The electronickel manufacturing process is
A first cementation step of adding nickel sulfide to the copper-containing nickel chloride solution and reducing at least the divalent copper ions in the copper-containing nickel chloride solution to monovalent copper ions.
A nickel mat and a chlorine leaching residue obtained by the chlorine leaching treatment are added to the slurry obtained through the first cementation step, and the monovalent copper ion contained in the slurry is immobilized as a sulfide. Including a cementation step having 2 cementation steps and
In the decopper electrolysis treatment, the surface is composed of a metal containing titanium, and the arithmetic average roughness (Ra) of the surface on which copper is deposited is 0.2 μm to 1.2 μm, and the maximum height (Rz) is 1.2 μm or more. A part of the reaction final solution obtained through the first cementation step in the cementation step is supplied to an electrolytic tank provided with a 6.0 μm negative electrode and a positive electrode as a decopper electrolysis starting solution. Copper removal electrolysis treatment method. The method for removing copper electrolysis according to claim 1, wherein the electrolysis treatment is performed with the redox potential (based on the silver / silver chloride electrode) of the starting solution of the copper removal electrolysis treatment in the range of 300 mV to 470 mV. A copper-removing electrolytic treatment device used for copper-removing electrolytic treatment in the process of producing electric nickel by an electrolytic sampling method from a copper-containing nickel chloride solution obtained by subjecting nickel sulfide to chlorine leaching treatment. ,
The electronickel manufacturing process is
A first cementation treatment in which nickel sulfide is added to the copper-containing nickel chloride solution to reduce at least the divalent copper ions in the copper-containing nickel chloride solution to monovalent copper ions.
A nickel matte and a chlorine leaching residue obtained by the chlorine leaching treatment are added to the slurry obtained through the first cementation treatment, and the monovalent copper ion contained in the slurry is immobilized as a sulfide. It is a process including a cementation step of performing a two-step cementation process consisting of two cementation processes.
The decopper electrolytic treatment device is
An electrolytic cell having an electrode pair consisting of a positive electrode and a negative electrode is provided.
The positive electrode is composed of an insoluble electrode and is composed of an insoluble electrode.
The negative electrode is made of a metal containing titanium, and the arithmetic mean roughness (Ra) of the surface on which copper is deposited is 0.2 μm to 1.2 μm, and the maximum height (Rz) is 1.2 μm to 6.0 μm. And
A part of the reaction final liquid obtained through the first cementation treatment in the cementation step is supplied to the electrolytic cell as the starting liquid for the copper removal electrolysis treatment, and the copper removal electrolysis treatment is executed.
Copper removal electrolysis treatment equipment.

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