JP6957984B2 - Copper removal method, electronickel manufacturing method - Google Patents

Description

The present invention relates to a method for removing copper in an electric nickel manufacturing process and a method for producing the electric nickel.

As a hydrometallurgy process for recovering the target metal from sulfide, nickel matte and nickel-cobalt mixed sulfide (MS: mixed sulfide), which are raw materials, are leached with chlorine (chlorine leaching step), and impurities are removed from the obtained leachate. There is a method of recovering electric nickel or electric cobalt in an electrolytic process through a liquid purification process or the like.

For example, as shown in FIG. 5, in the leachate (copper-containing nickel chloride solution) obtained in the chlorine leaching step, excess copper is removed in the copper removal electrolysis step provided between the cementation step and the leaching step (for example, Patent Document). 1 to 3), and after removing impurities such as iron and arsenic in the iron removal step, the solution is sent to the 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). The nickel chloride solution is further removed of impurities in the liquid purification step to become highly pure and sent to the nickel electrolysis step, and electrolytic nickel is produced by electrowinning. Further, the cobalt chloride solution is also sent to the cobalt electrowinning step after further removing impurities in the liquid purification step to become highly pure, and electrowinning produces electric cobalt.

By the way, in the decopper electrolysis step, conventionally, a part of the chlorine leachate is introduced into the decopper electrolysis facility, and copper is deposited and removed on the cathode side by the reactions of the following chemical formulas (1) and (2). ..
^{Cu + + e - = Cu 0} ··· (1)
Cu ²⁺ + 2e ⁻ = Cu ⁰ ... (2)

However, the copper contained in the chlorine leachate is mainly divalent copper ions (Cu ²⁺ ), and when a large amount of divalent copper ions are present, the copper (Cu ⁰ ) electrodeposited on the cathode by the electrolytic reaction is represented by the following reaction formula (3). It is known that the copper is redissolved by the reaction shown in), and there is a problem that the current efficiency represented by the following formula (I) is lowered when the copper removal electrolysis treatment is performed.
Cu ⁰ + Cu ²⁺ = Cu ⁺ ... (3)
Current efficiency (%) = Cu removal amount (kg / day) ÷ theoretical electrodeposition amount (kg / day)
(Note that the standard is divalent copper ion.)

From this, in order to reduce the amount of divalent copper ions in the chlorine leachate, for example, in Patent Document 1, a reducing agent is added to the chlorine leachate to add divalent copper ions (Cu ²⁺ ) to monovalent copper ions. A method of reducing to (Cu ^{+) is disclosed.} Further, Patent Document 2 discloses a method of adding a reducing agent by defining an oxidation-reduction potential (ORP). Further, Patent Document 3 discloses a method of suppressing variation in copper concentration when mixing chlorine leachate and anolite using a colorimetric meter to prevent excess divalent copper ions. ..

However, although the above-mentioned conventional techniques can be expected to improve the current efficiency, the current efficiency of the electrolysis process in the copper removal electrolysis process is about 60% at the actual operation site, and the current efficiency is further improved. Improvement is required.

On the other hand, 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 above-mentioned cementation step. However, the copper fixed and removed as sulfide by the electrolysis treatment is contained in the cementation residue and returned to the chlorine leaching step to circulate in the system, and thus is disclosed in Patent Document 4. It is difficult to directly apply the technique as a technique for extracting copper from the system as in the treatment in the copper removal electrolysis process.

Further, in addition to the above-mentioned problem of current efficiency, there is also a problem in terms of raw materials. That is, the copper content of the nickel mat used in the conventional operation was about 2% by mass to 4% by mass, but the copper content increased significantly to 15% by mass to 18% by mass depending on the raw material situation. The number of cases where nickel mats are used is increasing, and there is also a problem that it is difficult to sufficiently cope with the processing capacity in the conventional copper removal electrolysis process.

For this reason, there is a need for a treatment technology in the copper removal electrolysis process, which has a high ability to handle raw materials, and which can deal with problems in terms of raw materials, rather than a costly method such as increasing the equipment used for the treatment in the copper removal electrolysis process. ing.

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

The present invention has been proposed in view of such circumstances, and an object of the present invention is to provide a method capable of improving the processing capacity in the copper removal electrolysis step without increasing the equipment cost and the like.

As a result of diligent studies, the present inventors have performed a copper decopper electrolysis step on a part of the reaction final solution obtained through the first cementation step in the electronickel manufacturing process in which a two-step cementation process is performed. It has been found that the above-mentioned problems can be solved by using it as the starting liquid of the copper electrolysis treatment in the above, and the present invention has been completed.

(1) The first invention of the present invention is in a process for producing electrolytic nickel by an electrolytic sampling method from a copper-containing nickel chloride solution obtained by subjecting a copper-containing nickel sulfide to a chlorine leaching treatment. In the method for removing copper, the electrolytic nickel production process is to add nickel sulfide to a copper-containing nickel chloride solution and at least reduce divalent copper ions in the copper-containing nickel chloride solution to monovalent copper ions. To the slurry obtained through the first step and the first step, a nickel mat and a chlorine leaching residue obtained by the chlorine leaching treatment are added, and the monovalent copper ion contained in the slurry is sulfided. A part of the reaction final solution obtained through the first step in the cementation step is used as the starting solution of the copper removal electrolysis treatment, including a cementation step having a second step of immobilizing the copper. This is a method for removing copper by electrolytically collecting copper.

(2) In the second invention of the present invention, in the first invention, the redox potential (silver / silver chloride electrode standard) of the reaction final solution obtained through the first step is 300 mV or more and 350 mV or less. This is a method for removing copper, which is used as the starting liquid for the copper removal electrolysis treatment.

(3) The third invention of the present invention is a method for producing electrolytic nickel by an electrolytic sampling method from a copper-containing nickel chloride solution obtained by leaching a nickel sulfide containing copper with chlorine. A copper sulfide electrolysis step of electrolytically removing copper contained in the copper-containing nickel chloride solution is included, and nickel sulfide is added to the copper-containing nickel chloride solution as a starting solution for the copper removal electrolysis treatment in the copper removal electrolysis step. Then, at least, the nickel mat and the chlorine leaching treatment are applied to the slurry obtained through the first step of reducing the divalent copper ions in the copper-containing nickel chloride solution to the monovalent copper ions and the first step. The reaction termination obtained through the first step in the electrolysis step having the second step of adding the chlorine leaching residue obtained in the above step and immobilizing the monovalent copper ion contained in the slurry as sulfide. This is a method for producing electrolytic nickel using a part of a liquid.

According to the present invention, it is possible to improve the processing capacity in the copper removal electrolysis step without increasing the equipment cost and the like, and it is possible to efficiently increase the amount of copper removal.

It is a process diagram which shows the flow of the manufacturing process of electric nickel. It is a schematic process diagram which shows the flow of the conventional copper removal electrolysis treatment in the manufacturing process of electric nickel. It is a schematic process diagram which shows the flow of the copper removal electrolysis treatment of this invention in the manufacturing process of electric nickel. The process chart which shows the flow of the process in a copper removal electrolysis process is shown. It is the whole process diagram of the wet smelting process.

Hereinafter, the present invention will be specifically described. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention.

≪1. How to remove copper from copper-containing nickel chloride solution ≫
The method for removing copper according to the present invention is a method for electrowinning and removing copper from a copper-containing nickel chloride solution (copper-containing nickel chloride solution). More specifically, this method is a method for removing copper in the process of producing electric nickel by electrowinning from a copper-containing nickel chloride solution obtained by leaching copper-containing nickel sulfide with chlorine. be.

For example, 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 electrolytic nickel, copper and nickel derived from raw materials such as nickel sulfide and nickel mat are leached by chlorine leaching treatment (chlorine leaching step S1), and then electrolyzed as a copper-containing nickel chloride solution (electrolysis). In step S5), it becomes an electrolytic solution for producing electrolytic nickel. Then, in the process of this production process, the copper contained in the copper-containing nickel chloride is fixed as a sulfide (cementation steps S2 and S3), and a process of concentrating the nickel 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 a chlorine leaching treatment (chlorine leaching step S1) to be subjected to the leaching treatment.

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 leached nickel in the raw material during the chlorine leaching process. That is, in the chlorine leaching treatment, copper in the raw material is oxidized by the blown chlorine gas to become divalent copper ions, and nickel in the raw material is leached by oxidative leaching by the divalent copper ions. Therefore, copper plays an important role in effectively and stably leaching nickel in the raw material.

However, for example, when the amount of nickel sulfide or nickel matte processed is increased for the purpose of increasing the production of electric nickel, or when a raw material having a high copper content is used due to the raw material situation, it is inevitable. The amount of copper circulating in the electronickel manufacturing process system also increases.

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

FIG. 2 is a schematic process diagram showing the flow of the conventional copper removal electrolysis treatment in the electric nickel manufacturing process system. In the conventional method, a part of the chlorine leachate (copper-containing nickel chloride solution) obtained in the chlorine leaching step is transferred to the decopper electrolysis step, copper is electrolytically collected by the electrolysis treatment, and then after the treatment, after decopperation. The solution was combined with the copper-containing nickel chloride solution of other parts and treated in the electrolysis step. However, the copper contained in the chlorine leachate is mainly divalent copper ions, and since the content is large, ^{a phenomenon occurs in which the electrolytically precipitated copper (Cu 0} ) is redissolved in the treatment in the copper decopping electrolysis step, resulting in decoppering. Causes a decrease in current efficiency in electrolytic processing.

Here, the current efficiency in the decopper electrolysis treatment is expressed by the ratio of the Cu removal amount (kg / day) to the theoretical electrodeposition amount (kg / day) with "divalent copper ions as a reference".
Current efficiency (%) = Cu removal amount (kg / day) ÷ theoretical electrodeposition amount (kg / day) x 100

On the other hand, in the present invention, as shown in FIG. 3, in the process of producing electrolytic nickel, a cementation treatment for immobilizing copper in a copper-containing nickel chloride solution as sulfide is performed in two steps (FIG. 3). (Refer to the process diagram of No. 1). Used as the starting solution for treatment. 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 production process, as shown in FIG. 1, nickel sulfide is added to the copper-containing nickel chloride solution, and at least the divalent value 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) of adding the obtained chlorine leaching residue and immobilizing the monovalent copper ion contained in the slurry as sulfide.

In the first cementation step S2 in the two-step cementation treatment, as shown in the following equations (4) and (5), it is obtained by adding nickel sulfide to the copper-containing nickel chloride solution. A reaction occurs in which most of the copper ions in the final solution (copper-containing nickel chloride 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 solution obtained through the first cementation step S2 is transferred to the copper removal electrolysis step to perform the copper removal electrolysis treatment, whereby the reaction final solution is contained. Since most of the copper ions are in the state of monovalent copper ions, the above-mentioned current efficiency represented by the divalent copper ion standard can be doubled, and the equipment and facilities used for the copper removal electrolysis treatment and the equipment and the like. The amount of copper that can be removed from the process system can be doubled while keeping the same power consumption.

For example, since the reaction final liquid obtained through the first cementation step S2 is in the form of a slurry (mainly composed of a copper-containing nickel chloride solution and undissolved nickel sulfide), the slurry is transferred. A pump for this purpose, a solid-liquid separator, a solid content tank, a solution tank, and a pipe for sending the solution to the copper removal electrolysis step are required, and a certain cost is required in the copper removal electrolysis treatment. At this time, if it is attempted to double the amount of copper removed from the process system by the conventional method, equipment (for example, an electrolytic cell, a rectifier, etc.) for processing in the same processing time is 2. It is necessary to double the power consumption, and it is necessary to double the power consumption. Alternatively, it is necessary to double the processing time and double the power consumption in the processing time, and it is easily understood that a large cost is required in these embodiments.

Moreover, if there is no space for new equipment or if the processing time cannot be doubled, it is practically impossible to improve the capacity of copper removal electrolysis treatment by the conventional method. It becomes.

In this respect as well, according to the present invention, the treatment start liquid to be subjected to the copper removal electrolysis treatment is the reaction final liquid obtained through the first step (S2) in the two-step cementation treatment. Therefore, by performing the decopper electrolysis treatment on a part of the reaction final liquid, the amount of copper is about twice as much as the conventional one without increasing the equipment, power consumption and treatment time of the decopper electrolysis treatment. Can be removed efficiently.

In the copper electrolysis treatment, the reaction final liquid obtained through the first cementation step S2 may be subjected to a solid-liquid separation treatment to remove solids such as nickel sulfide contained in the solution. preferable.

By the way, in general, in the cementation step (S2, S3), a plurality of reaction tanks are used for processing. The reaction final solution obtained through the first cementation step S2, that is, the process solution in the middle of the cementation process, has an oxidation-reduction potential (ORP: silver / silver chloride electrode standard) in the range of 350 mV or less, and is approximately 100. % Copper ion is known to be a monovalent copper ion having a valence of monovalent. On the other hand, it is known that when the ORP of the process liquid is less than 300 mV, it easily reacts with sulfur and copper sulfide precipitates.

Therefore, in the cementation step (S2, S3) treated using a plurality of reaction tanks, a step solution having an ORP in a range of preferably 300 mV or more and 350 mV or less, more preferably 320 mV or more and 350 mV or less is specified. By withdrawing from the reaction vessel of the above, a liquid corresponding to the final reaction liquid obtained through the first cementation step S2 can be withdrawn. Then, by using the process liquid of ORP belonging to such a range as the starting liquid for the copper removal electrolysis treatment, copper can be efficiently electrowinned and removed as described above.

Further, a part of the final reaction solution extracted from the first cementation step S2 may be stored in a predetermined tank to adjust the state of the solution immediately before being subjected to the copper removal electrolysis treatment. Specifically, prior to subjecting the reaction final solution to the copper removal electrolysis treatment, the reaction final solution is charged and stored in a predetermined tank (copper removal liquid supply adjusting tank), and a reducing agent is appropriately added. Then, the solution may be prepared so that the ORP of the solution is in the range of 300 mV or more and 350 mV or less.

Even if most of the copper ions in the copper-containing nickel chloride solution are reduced to the form of monovalent copper ions in the first cementation step S2, one of the reaction final solutions in the first cementation step S2. Even if the part can be properly extracted from the reaction vessel, the copper ions in the solution may change to the state of divalent copper ions in the process of solid-liquid separation treatment or the process of transferring to the copper removal electrolysis step. be. Even in such a situation, a reducing agent is added and an appropriate ORP range is provided before the reaction final liquid is subjected to the copper removal electrolysis treatment by providing the copper removal liquid supply adjusting tank as described above. By adjusting the liquid to, the state of monovalent copper ions can be easily restored, and the copper removal electrolysis treatment with high current efficiency can be reliably executed.

In such an embodiment, the reducing agent used for the liquid preparation is not particularly limited, but it is possible to use the nickel electrolytic waste liquid (anolite) discharged from the electrolytic step S5 in the electrolytic nickel production process from the viewpoint of cost and the like. And preferable from the viewpoint of efficient operation.

The solution to be subjected to the copper removal electrolysis treatment is preferably about 60 ° C. to 70 ° C. The final reaction solution obtained through the first cementation step S2 has a temperature of about 80 ° C. after recovery. Therefore, by lowering the temperature of the final reaction solution to about 60 ° C. to 70 ° C., the solid content can be separated using a solid-liquid separation device such as a filter press, and the operation efficiency can be improved. ..

The method for lowering the temperature of the final reaction solution is not particularly limited, and for example, a simple method such as temporarily storing the extracted reaction final solution (process solution) in a tank provided with cooling means may be selected.

Here, FIG. 4 shows a process diagram showing a process flow in the copper removal electrolysis step. As shown in FIG. 4, in the decopper electrolysis step, a copper-containing nickel chloride solution (a part of the reaction final solution obtained through the first cementation step S2) to be decopperized and, for example, a nickel electrolytic waste solution. A reducing agent such as (anolite) is mixed in a mixing tank (mixing step S11). In this way, by mixing the reaction final solution and anolite prior to the copper removal electrolysis treatment, the copper concentration in the reaction final solution is diluted to a predetermined concentration, and the copper ions are surely monovalent copper ions. In the form of.

Next, the mixed solution (decopper electrolytic supply liquid) obtained in the mixing step S11 is charged into the copper decopper electrolytic cell, and the decopper electrolytic treatment is performed (copper electrolysis treatment step S12). By this copper removal electrolysis treatment, an electrolytic reaction (Cu ⁻ + e ⁻ ⇒ Cu) occurs and copper (copper powder) is electrodeposited on the cathode. The post-electrolysis liquid obtained after the electrolytic reaction is recovered and transferred to the second cementation step S3.

Next, the electrolytically collected copper powder is washed (repulp step S13). The obtained copper powder is in a wet state with a copper-containing nickel chloride solution, and the nickel-containing solution can be recovered by repulping such copper powder with washing water or the like.

Next, the copper powder slurry obtained by washing in the repulp step S13 is subjected to a solid-liquid separation treatment (solid-liquid separation step S14). The solid-liquid separation treatment can be carried out 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 removed from the system, and the decopper filtrate after separating the copper powder can be returned to the decopper electrolytic cell.

≪2. Electrical nickel manufacturing process ≫
Next, the outline of the electric nickel manufacturing process will be described.

As described above, FIG. 1 is a process diagram showing the flow of the electronickel manufacturing process. As shown in FIG. 1, in the electric nickel production process, a copper-containing nickel sulfide solution (copper-containing nickel sulfide solution) is used as a raw material to leach out the metal components of nickel and copper, and is a chlorine leachate. A first cementation step S2 in which nickel sulfide is added as a raw material to the obtained copper-containing nickel chloride solution to reduce at least divalent copper ions to monovalent copper ions. In the second cementation step S3 in which a nickel mat and a chlorine leaching residue are added to immobilize monovalent copper ions to the slurry after the cementation step S2 in 1, impurities other than nickel are removed from the cementation final solution. It has a purification step S4 and an electrolytic step S5 for obtaining electrolytic nickel from a nickel chloride solution from which impurities have been removed by an electrolytic sampling method.

[1] Chlorine leaching step In the chlorine leaching step S1, nickel sulfide containing copper is subjected to leaching treatment using chlorine as a raw material, and nickel and copper metal components contained in the copper-containing nickel sulfide are leached. do.

As the copper-containing nickel sulfide to be leached, for example, nickel sulfide (nickel-cobalt mixed sulfide) produced by hydrometallurgy from nickel oxide ore can be used. In addition, the cementation residue 16 obtained through the cementation step (second cementation step S3) described later can also be used.

In the chlorine leaching step S1, a chlorine leaching treatment is performed by blowing chlorine gas such as chlorine gas 18 recovered in the electrolytic step S5 into a slurry of copper-containing nickel sulfide composed of nickel sulfide and cementation residue 16. .. By this chlorine leaching treatment, nickel and copper in the copper-containing nickel sulfide are leached to generate a copper-containing nickel chloride solution 11'as a chlorine leaching solution 11 and an leaching residue.

As the cementation residue 16 composed of copper-containing nickel sulfide, a repulped and slurryed product is used. The repulp liquid is not particularly limited, and for example, the nickel chloride solution 17 obtained in the electrolysis step S5 can be preferably used.

More specifically, in the chlorine leaching treatment in the chlorine leaching step S1, for example, the reactions shown in the following reaction formulas (6) to (8) occur.
Cl ₂ + 2Cu ⁺ → 2Cl ⁻ + 2Cu ²⁺ ... (6)
NiS + 2Cu ²⁺ → Ni ²⁺ + S ⁰ + 2Cu ⁺ ... (7)
Cu ₂ S + 2Cu ²⁺ → 4Cu ⁺ + S ⁰ ... (8)

In this chlorine leaching treatment, metal components such as nickel sulfide and copper sulfide contained in the copper-containing nickel sulfide are oxidatively leached by divalent copper ions oxidized by the chlorine gas 18, and the copper-containing chloride as the chlorine leachate 11 is obtained. A nickel solution 11'is produced. On the other hand, the chlorine leaching residue 13 containing sulfur as a main component remains in the solid phase. The chlorine leachate 11 produced in the chlorine leaching step S1 is sent to a first cementation step S2 and a subsequent second cementation step S3, which will be described later, to fix and remove copper, and then to produce electrolytic nickel. It becomes an electrolytic solution for. On the other hand, the chlorine leaching residue 13 serves as a raw material for recovering sulfur or a sulfur source for fixing copper ions in the cementation step (second cementation step S3) described later.

[2] First Cementation Step In the first cementation step S2, a copper-containing nickel chloride solution 11'which is the chlorine leaching solution 11 obtained in the chlorine leaching step S1 is sent, and this copper-containing nickel chloride solution is fed. Nickel sulfide 10 is added to 11'. As a result, the divalent copper ions in the copper-containing nickel chloride solution 11'are mainly reduced to monovalent copper ions.

The nickel sulfide 10 added in the first cementation step S2 is added as, for example, a slurry produced by repulping together with the nickel chloride solution 17 obtained in a subsequent step in the electric nickel production process. As the nickel sulfide 10, for example, nickel sulfide produced by hydrometallurgy from nickel oxide ore or the like is used.

Specifically, in the first cementation step S2, for example, the reaction represented by the following formula (9) mainly occurs, and in part, the reaction represented by the formula (10) occurs.
4NiS + 2Cu ²⁺ → Ni ²⁺ + Ni ₃ S ₄ + 2Cu ⁺ ... (9)
_{^{NiS + 2Cu + → Ni 2+ +}} Cu 2 S ··· (10)

That is, by adding nickel sulfide 10 to the copper-containing nickel chloride solution 11'delivered from the chlorine leaching step S1, nickel sulfide (NiS), which is the main form in the nickel sulfide 10, is copper-containing. The divalent copper ion in the nickel chloride solution 11'is reduced to the monovalent copper ion (the above formula (9)). Further, in a part thereof, which is the main form NiS is immobilized as a monovalent copper ions of copper sulfide _(Cu 2 S) (the formula (10)).

However, the reducing power of NiS, which is the main form in nickel sulfide 10, is weak, and the effect of fixing monovalent copper ions as copper sulfide is weak. Therefore, in the first cementation step S2, the reaction of reducing divalent copper ions in the copper-containing nickel chloride solution 11'to monovalent copper ions (the above formula (9)) mainly proceeds. Then, the reduced monovalent copper ion is immobilized as copper sulfide by a sulfur source in the second cementation step S3 as described later.

The copper-containing nickel chloride solution 11'used in the first cementation step S2 and the chlorine leaching solution 11 sent from the chlorine leaching step S1 are not particularly limited and can be applied in any composition state. .. For example, those having a nickel concentration of 150 g / L to 270 g / L, a copper concentration of 20 g / L to 40 g / L, and a pH of 0.5 to 2.0 can be used. The form of copper ions in the copper-containing nickel chloride solution 11'is not particularly limited, and for example, the divalent copper ion ratio is 60% to 90%, and the monovalent copper ion ratio is 10% to 40%. Some can be used.

The nickel sulfide 10 used in the first cementation step S2 is obtained by, for example, hydrometallurgy of low-grade nickel oxide ore as described above, and contains nickel and cobalt. As described above, by adding the nickel oxide 10 obtained by hydrometallurgy to the copper-containing nickel chloride solution 11', the reducing power of nickel sulfide and cobalt sulfide contained in the nickel sulfide is used. Divalent copper ions can be efficiently reduced to monovalent copper ions.

The amount of nickel sulfide 10 added is preferably such that the concentration in the copper-containing nickel chloride solution 11'is 60 g / L to 110 g / L. If the amount added is less than 60 g / L, divalent copper ions cannot be sufficiently reduced to monovalent copper ions, and efficient copper removal may not be possible. On the other hand, if the addition amount exceeds 110 g / L, the effect of further reduction treatment cannot be obtained, resulting in inefficiency in operation.

Further, as the nickel sulfide 10, it is preferable to use one that has been wet-pulverized by, for example, a tower mill or a bead mill. Specifically, it is preferable to use one having an average particle size (D50) of 80 μm or less, preferably 20 μm or less, and more preferably 10 μm or less by wet pulverization. As a result, the monovalent copper ions contained in the copper-containing nickel chloride solution 11'can be efficiently reduced, and the copper ion removal efficiency can be improved. In particular, by setting the particle size of the nickel sulfide 10 to 20 μm or less, more preferably 10 μm or less in terms of the average particle size (D50), the copper concentration (in terms of monovalent copper) in the copper-containing nickel chloride solution 11'is effectively achieved. ) Can be 30 g / L or less, and copper in the copper-containing nickel chloride solution 11'can be efficiently removed to 0.1 g / L or less through the second cementation step S3. The average particle size (D50) is a particle size at which the cumulative volume is 50% as measured by laser particle size distribution measurement.

The reaction temperature condition in the first cementation step S2 is preferably 80 ° C. to 110 ° C., and more preferably 90 ° C. to 95 ° C. By setting the temperature condition to 80 ° C. or higher, the reduction treatment of copper ions in the copper-containing nickel chloride solution 11'can be efficiently advanced, and the copper ion removal efficiency in the second cementation step S3 described later can be achieved. Can be improved. When the temperature condition is higher than 110 ° C., the efficiency of removing copper from the copper-containing nickel chloride solution 11'is improved, but the equipment cost due to the heat resistant specifications and the operating cost due to the increase in the amount of steam are incurred, and efficient operation is possible. It disappears.

As described above, in this electronickel production process, a two-step cementation treatment is performed, and in the first cementation step S2, divalent copper ions in the copper-containing nickel chloride solution 11'are mainly efficient. It is reduced to monovalent copper ion. Therefore, as shown in FIG. 3, a part of the final reaction liquid obtained through the first cementation step S2 is transferred to the decopper electrolysis step in which the decopper electrolysis treatment is performed. As a result, the current efficiency can be improved by the electrolytic treatment, and about twice the amount of copper can be removed from the system as compared with the conventional case.

When a part of the final reaction liquid obtained through the first cementation step S2 is transferred to the decopper electrolysis step for decopper treatment, the post-electrolysis liquid after decopperation (after decoppering). The liquid) can be returned to the first electrolysis step S2 (see FIG. 3).

[3] Second Cementation Step In the second cementation step S3, the nickel mat 12 and the chlorine leaching residue 13 are added to the slurry containing the copper-containing nickel chloride solution 11'obtained through the first cementation step S2. Is added to reduce the divalent copper ion to the monovalent copper ion, and the monovalent copper ion is immobilized as a sulfide such as copper sulfide.

Specifically, in the second cementation step S3, for example, the reactions shown in (11) to (14) below occur.
Ni + Cu ²⁺ → Ni ²⁺ + Cu ⁺ ... (11)
Ni ₃ S ₂ + 2Cu ²⁺ → Ni ²⁺ + 2NiS + 2Cu ⁺ ... (12)
Ni + 2Cu ^＋ ＋ S → Ni ₂ ^＋ ＋ Cu 2 S ・ ・ ・ (13)
Ni ₃ S ₂ + 2Cu ^＋ ＋ S → Ni ₂ ^＋ ＋ 2NiS ＋ Cu 2 S ・ ・ ・ (14)

In the second cementation step S3, as shown in the above equations (11) and (12), copper-containing _{metal (Ni) and nickel sulfide (Ni 3} S _{2) contained in the added nickel mat 12 are used.} The divalent copper ions remaining in the nickel chloride solution 11'are reduced to monovalent copper ions. As described above, the divalent copper ions remaining unreduced in the first cementation step S2 are reduced by the nickel matte in the second cementation step S3.

Further, in the second cementation step S3, the monovalent copper ions reduced in the first cementation step S2 and the second cementation step S3 are contained in the nickel mat 12 as Ni or Ni ₃ S _2. As a result, a reaction of immobilizing as sulfide using the chlorine leaching residue 13 added as a sulfur source occurs (Equations (13) and (14)). As a result, the copper contained in the copper-containing nickel chloride solution 11'is immobilized and removed.

As the nickel mat 12 added in the second cementation step S3, for example, a nickel mat obtained by dry smelting is used, and divalent copper ions are utilized by utilizing the reducing power of nickel metal and nickel sulfide, which are the main forms. Is reduced to monovalent copper ions. On the other hand, nickel metal and the like in the nickel mat 12 are leached into nickel ions by the oxidizing power of divalent copper ions. As the nickel mat 12, for example, a nickel mat 12 that has been pulverized and repulped with a nickel chloride solution 17 generated from the electrolysis step S5 in the subsequent step to be slurried can be used.

The chlorine leaching residue 13 added in the second cementation step S3 is a residue remaining in the solid phase as a by-product in the chlorine leaching step S1 and is added as a sulfur source for immobilizing copper ions. The chlorine leaching residue 13 immobilizes monovalent copper ions as sulfides such as copper sulfide with sulfur, which is the main form, together with the nickel mat 12.

The reaction temperature condition in the second cementation step S3 is preferably 70 ° C. to 100 ° C., more preferably 80 ° C. to 90 ° C. By setting the temperature condition to 70 ° C. or higher, the reaction of reducing the remaining divalent copper ions to monovalent copper ions and efficiently immobilizing the monovalent copper ions with sulfur can proceed. When the temperature condition is higher than 100 ° C., the copper removal efficiency from the copper-containing nickel chloride solution 11'does not improve any more, and it is preferably 100 ° C. or lower from the viewpoint of operating efficiency.

As described above, first, in the first cementation step S2, the nickel sulfide 10 is added to the copper-containing nickel chloride solution 11', and the divalent copper ion is reduced to the monovalent copper ion by the nickel sulfide 10. .. Then, in the second cementation step S3, the nickel mat 12 and the chlorine leaching residue 13 are added to the generated slurry, and the divalent copper ion is reduced to the monovalent copper ion by the nickel mat 12 and used as a sulfur source. The monovalent copper ion is immobilized as a sulfide such as copper sulfide using the chlorine leaching residue 13 of the above, and copper in the copper-containing nickel chloride solution 11'is removed.

In this way, instead of reducing and immobilizing divalent copper ions only with nickel metal and nickel sulfide contained in the nickel mat 12 and the chlorine leaching residue 13, the reducing power of the nickel sulfide 10 is first utilized to the maximum extent. The divalent copper ions in the copper-containing nickel chloride solution 11'are reduced to monovalent copper ions, and then the monovalent copper ions are immobilized as sulfides with the nickel mat 12 and the chlorine leaching residue 13. As a result, the copper circulating in the system can be efficiently decopperized with the same amount of nickel matte as before, and copper can be reliably removed from the copper-containing nickel chloride solution 11'. ..

The slurry obtained through the second cementation step S3 can be separated into a cementation final liquid 14 and a cementation residue 16 by subjecting a solid-liquid separation treatment. The solid-liquid separation treatment is not particularly limited, and can be carried out by a well-known method such as a centrifuge or a filter press, and can efficiently separate and remove a precipitate such as copper sulfide which is a cementation residue. can.

[4] Purification step In the purification step S4, a nickel chloride solution for removing impurities other than nickel from the cementation final solution (nickel leachate) 14 obtained through the second cementation step S3 and electrowinning. To get.

The liquid purification step S4 mainly includes an iron removal step, a cobalt removal step, a lead removal step, and a zinc removal step. In these steps, as a method for removing impurities from the nickel leachate which is the final cementation liquid 14, for example, an oxidation neutralization method using chlorine gas as an oxidizing agent and carbonate as an alkali agent can be used. The oxidation-neutralization method utilizes the property that heavy metals such as cobalt and iron tend to become hydroxides in the low pH range when they become higher-order oxide ions. It is a method that is widely used for wastewater treatment including.

For example, in the liquid purification step S4, impurities are removed by the reaction represented by the following formula (15).
2M ²⁺ + Cl ₂ + 3NiCO ₃ + 3H ₂ O →
2M (OH) ₃ + 3Ni ²⁺ + 2Cl ⁻ + 3CO ₂ ... (15)
(However, M is cobalt or iron.)

As shown in the above equation (15), in the liquid purification step S4, chlorine gas is used to form a hydroxide precipitate of the target impurities from the nickel leachate to generate a nickel chloride solution from which the impurities have been removed.

Generally, as the chemical used in the oxidation neutralization method, hypochlorous acid, oxygen, air or the like can be used as the oxidizing agent in addition to chlorine gas. Further, as the alkaline agent, in addition to carbonate, hydroxides such as caustic soda, ammonia and the like can be used. Although these chemicals are used in a combination suitable for the process conditions, it is preferable to use chlorine gas as an oxidizing agent and carbonate as an alkaline agent in the nickel hydrometallurgy process. The reason for using chlorine gas as the oxidizing agent is that chlorine gas is a strong oxidizing agent generated in the process and is easy to use. Further, the reason why carbonate is used as the alkaline agent is that the ion concentration of nickel, sodium, sulfuric acid, etc. in the whole process can be controlled, and the reactivity at the time of oxidation neutralization is excellent.

[5] Electrolytic Step In the electrolytic step S5, electric nickel 15 is obtained from the nickel chloride solution purified through the above-mentioned liquid purification step S4 by an electrowinning method.

Specifically, in the electrolysis step S5, the reactions shown in (16) and (17) below occur at the cathode and the anode, respectively.
(Cathode ^{side) Ni 2+ + 2e - → Ni} 0 ··· (16)
(Anode side) 2Cl ⁻ → Cl ₂ + 2e ⁻・ ・ ・ (17)

That is, on the cathode side, as shown in the above equation (11), nickel ions in the nickel chloride solution are precipitated as metal (electronickel 15). Further, on the anode side, as shown in the above equation (12), chlorine ions in the nickel chloride solution are generated as chlorine gas 18. The generated chlorine gas 18 is used as the recovered chlorine gas in the chlorine leaching step S1 or the like.

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]
A decopper electrolysis treatment was performed to remove excess copper in the process system of the electrolytic nickel manufacturing process (see FIG. 1). In the copper removal electrolysis treatment, 6 tanks (each tank: length 0.95 m, width 3.92 m, average depth 1.2 m) are connected and executed, and the liquid supply flow rate to be treated is 1 tank. It was set to 20 L / min.

In Example 1, a part of the final reaction liquid obtained through the first cementation step S2 was used as the process liquid to be subjected to the copper removal electrolysis treatment. The ORP (silver / silver chloride electrode standard) of this reaction final solution was 300 mV. In addition, a precipitate of copper sulfide was partially confirmed in the final solution of the reaction to be subjected to the copper removal electrolysis treatment.

As a result of performing the electrolysis treatment with the total flow rate of the final solution of the reaction to the copper removal electrolytic cell set to 1200 L / min, the current efficiency was 150%, and the daily copper removal amount reached 4.8 tons, and copper was efficiently removed. Was able to be removed.

The current efficiency is expressed by the following formula with reference to the divalent copper ion.
Current efficiency (%) = Cu removal amount (kg / day) ÷ theoretical electrodeposition amount (kg / day) x 100

[Example 2]
In Example 2, as in Example 1, a part of the final reaction liquid obtained through the first cementation step S2 was used as the process liquid to be subjected to the copper removal electrolysis treatment. The final solution of the reaction having an ORP (silver / silver chloride electrode standard) of 350 mV was extracted from the reaction tank for cementation treatment and used. In addition, no precipitate of copper sulfide was confirmed in the final solution of the reaction to be subjected to the copper removal electrolysis treatment.

As a result of performing the electrolysis treatment with the total flow rate of the final solution of the reaction to the copper removal electrolytic cell set to 1200 L / min, the current efficiency was 160%, and the daily copper removal amount reached 5.1 tons, and copper was efficiently removed. Was able to be removed.

[Example 3]
In Example 3, as in Example 1, a part of the final reaction liquid obtained through the first cementation step S2 was used as the process liquid to be subjected to the copper removal electrolysis treatment. The ORP (silver / silver chloride electrode standard) of this reaction final solution was 380 mV, and 95% of all copper ions were monovalent copper ions.

As a result of performing the electrolysis treatment with the total flow rate of the final solution of the reaction to the copper removal electrolytic cell set to 1200 L / min, the current efficiency was 152%, and the daily copper removal amount reached 4.8 tons, and copper was efficiently removed. Was able to be removed.

[Comparative Example 1]
In Comparative Example 1, a part of the chlorine leaching solution obtained through the chlorine leaching step S1 was used as the process liquid to be subjected to the copper removal electrolysis treatment. The ORP (silver / silver chloride electrode standard) of this chlorine leachate was 545 mV.

As a result of performing the electrolysis treatment with the total flow rate of the chlorine leachate into the copper removal electrolytic cell set to 780 L / min, the current efficiency is 80%, the daily copper removal amount is 2.5 tons, and copper is efficiently removed. I couldn't.

Claims (2)

A method for removing copper in the process of producing electric nickel by an electrowinning method from a copper-containing nickel chloride solution obtained by subjecting a nickel sulfide containing copper to a chlorine leaching treatment.
The electronickel manufacturing process is
The first 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 second step in which a nickel mat and a chlorine leaching residue obtained by the chlorine leaching treatment are added to the slurry obtained through the first step, and monovalent copper ions contained in the slurry are immobilized as sulfide. Including the process and the cementation process having
Rutotomoni using a part of the reaction completion solution obtained through the first step in the cementation step as starting solution for copper removal electrolysis process, the reaction completion solution, prior to subjecting the copper removal electrolysis , The reaction final liquid is charged and stored in the copper removal liquid supply adjustment tank, and the oxidation-reduction potential (silver / silver chloride electrode reference) of the reaction final liquid in the copper removal liquid supply adjustment tank is 300 mV or more and 350 mV or less. A method of removing copper by electrolytically collecting copper by adjusting the liquid using the nickel electrolytic waste liquid discharged from the electrolytic process in the electrolytic nickel manufacturing process so as to fall within the range of. It is a method for producing electric nickel by electrowinning from a copper-containing nickel chloride solution obtained by leaching nickel sulfide containing copper with chlorine.
The copper-depleted electrolysis step of electrolyzing and removing the copper contained in the copper-containing nickel chloride solution is included.
As the starting liquid of the copper removal electrolysis treatment in the copper removal electrolysis step,
The first 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 second step in which a nickel mat and a chlorine leaching residue obtained by the chlorine leaching treatment are added to the slurry obtained through the first step, and monovalent copper ions contained in the slurry are immobilized as sulfide. A part of the reaction final solution obtained through the first step in the cementation step having the step is used , and
Prior to subjecting the reaction final liquid to the copper removal electrolysis treatment, the reaction final liquid is charged and stored in the copper removal liquid supply adjustment tank, and the reaction final liquid in the copper removal liquid supply adjustment tank is charged. The liquid is prepared using the nickel electrolytic waste liquid discharged from the electrolytic step in the electrolytic nickel manufacturing process so that the redox potential (based on the silver / silver chloride electrode) is in the range of 300 mV or more and 350 mV or less.
Manufacturing method of electric nickel.

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