JP6992691B2 - How to separate copper from nickel and / or cobalt - Google Patents

Description

The present invention relates to a method for separating copper and nickel and / cobalt from an alloy containing copper and nickel and / or cobalt, for example, a waste lithium ion battery.

Vehicles such as electric vehicles and hybrid vehicles and electronic devices such as mobile phones, smartphones, and personal computers are equipped with lithium-ion batteries (hereinafter, also referred to as "LIB"), which are characterized by being lightweight and having a high output.

The LIB is a negative electrode material in which a negative electrode active material such as graphite is fixed to the surface of a negative electrode current collector using a copper foil inside an outer can made of a metal such as aluminum or iron or a plastic such as vinyl chloride. A positive electrode material in which a positive electrode active material such as lithium nickelate or lithium cobaltate is fixed to a positive electrode current collector made of an aluminum foil is charged together with a separator made of a porous resin film of polypropylene or the like, and phosphoric acid hexafluoride is charged. It has a structure impregnated with an organic solvent containing an electrolyte such as lithium (LiPF ₆ ) as an electrolytic solution.

When a LIB is incorporated into a vehicle or electronic device as described above and used, it eventually becomes unusable due to deterioration of the automobile or electronic device or the life of the LIB, and is called a waste lithium ion battery (waste LIB). Become. In addition, waste LIB may be generated as a defective product in the manufacturing process from the beginning.

These waste LIBs contain valuable components such as nickel, cobalt, and copper, and it is desirable to recover and reuse those valuable components for effective utilization of resources.

Generally, when trying to efficiently recover valuable components from equipment, members, and materials made of metal, they are put into a furnace, etc., all melted at high temperature, and separated into valuable metal and slag for disposal. It is considered that the dry process using the pyrometallurgical technique is simple.

For example, Patent Document 1 discloses a method for recovering a valuable metal by using a dry treatment. By applying the method disclosed in Patent Document 1 to a method for recovering valuable metals from waste LIB, a copper alloy containing nickel or cobalt can be obtained.

Although the dry treatment has a problem that it requires energy for heating to a high temperature, it has an advantage that various impurities can be treated in a simple process and separated at once. In addition, since the obtained slag has relatively stable chemical properties, there is no concern about causing environmental problems, and there is an advantage that it is easy to dispose of.

However, when the waste LIB is treated by the dry treatment, there is a problem that most of some valuable components, particularly cobalt, are distributed to the slag, resulting in a cobalt recovery loss. Further, the metal obtained by the dry treatment is an "alloy" in which valuable components coexist, and in order to reuse it, it is necessary to separate each component from the alloy and purify it to remove impurities.

As a method of element separation generally used in the dry method, there is a method of separating copper and lead or lead and zinc by slowly cooling from a high-temperature molten state. However, when copper and nickel are the main components as in waste LIB, copper and nickel have the property of uniformly melting over the entire composition range, so even if they are slowly cooled, copper and nickel are only mixed and solidified in layers. And they cannot be separated effectively.

Further, there is also a purification method in which nickel is disproportionated using carbon monoxide (CO) gas and volatilized from copper or cobalt to be separated. However, it is difficult to ensure safety because it uses highly toxic CO gas.

Further, as a method for separating copper and nickel, which has been industrially performed, there is a method for coarsely separating a mixed mat (sulfide). In this method, a mat containing copper and nickel is produced in a smelting process, which is slowly cooled in the same manner as described above to separate copper-rich sulfide and nickel-rich sulfide. That is. However, even with this method, the separation of copper and nickel is limited to a crude separation level, so that a separate process such as electrolytic refining is required to obtain high-purity nickel or copper.

As another method, for example, as disclosed in Patent Document 2, a method of utilizing the vapor pressure difference via chloride has been studied, but since it is a process of handling a large amount of toxic chlorine, it is necessary to take measures against equipment corrosion. It is hard to say that it is an industrially suitable method for safety measures.

The same applies to the separation of copper and cobalt and the separation of cobalt and nickel.

As described above, the separation and purification of each element by the dry method has the disadvantages that the separation and purification of each element remain at the crude separation level or the cost is high as compared with the wet method.

On the other hand, wet treatment using methods such as acid leaching treatment, neutralization treatment, solvent extraction treatment, etc. consumes less energy, and it is possible to separate the mixed valuable components individually and directly recover them with high-purity grade. There are merits. However, when the waste LIB is treated by a wet treatment, the hexafluorophosphate anion contained in the waste LIB is a difficult-to-treat product that is not completely decomposed even with high-temperature and high-concentration sulfuric acid, and is a valuable component. Will be mixed in the leached acid solution. Furthermore, since the hexafluorophosphate anion is a water-soluble carbonic acid ester, it is difficult to recover phosphorus and fluorine from the aqueous solution after recovering valuable resources, and they are released to public sea areas by wastewater treatment. There is a problem that it becomes difficult to suppress this.

In addition, it is not easy to obtain a solution capable of efficiently leaching valuable components from waste LIB and using it for purification with only an acid. Since the waste LIB itself is difficult to leached out, if it is forcibly leached out by using an acid with strong oxidizing power to improve the leaching rate of valuable components, aluminum, iron, manganese, etc. that are not subject to recovery together with the valuable components will be removed. There is a problem that even the components are leached out in large quantities, and the amount of neutralizing agent added to treat them and the amount of wastewater to be handled increase.

Furthermore, when adjusting the pH of the solution or neutralizing impurities and fixing them to the starch in order to perform separation treatment such as solvent extraction and ion exchange from the acidic leachate, the amount of neutralized starch generated. Therefore, there are many problems in terms of securing the processing place and ensuring the stability.

Furthermore, electric charges may remain in the waste LIB, and if it is attempted to be treated as it is, it may cause heat generation, explosion, or the like. Therefore, it is necessary to take time-consuming measures such as immersing in salt water and discharging.

It is not always an advantageous method to treat the waste LIB using only the wet treatment as described above.

Therefore, the above-mentioned waste LIB, which is difficult to treat by the dry treatment alone or the wet treatment alone, is removed as much as possible by the dry treatment by a method combining the dry treatment and the wet treatment, that is, by roasting the waste LIB. Attempts have been made to generate a uniform waste LIB treated product and then wet-treat the treated product to separate it into valuable components and other components.

In the method combining this dry treatment and the wet treatment, fluorine and phosphorus in the electrolytic solution are removed by volatilizing and the like by the dry treatment, and the organic members such as plastics and separators which are the structural parts of the waste LIB are decomposed. .. However, as described above, the cobalt contained in the waste LIB is distributed to the slag by undergoing the dry treatment, so that the problem of recovery loss caused by it still remains.

A method of distributing cobalt as a metal by adjusting the atmosphere, temperature, degree of reduction, etc. in the dry treatment and reducing and melting the cobalt so as to reduce the distribution to the slag is also conceivable. However, this time, the metal obtained by such a method forms a poorly soluble corrosion-resistant alloy containing nickel and cobalt based on copper, and is to be dissolved with an acid in order to separate and recover valuable components. However, there is a problem that it becomes difficult to dissolve.

Further, even if the above-mentioned corrosion-resistant alloy is acid-dissolved using chlorine gas, for example, the obtained solution (leaching solution) contains high-concentration copper and relatively low-concentration nickel or cobalt. Among them, nickel and cobalt are not so difficult to separate by using a known method such as solvent extraction. However, it is not easy to separate a large amount of copper from nickel or cobalt easily and at low cost.

As described above, it has been difficult to efficiently separate only copper, nickel, and cobalt from waste LIB containing copper, which is a valuable component, and nickel, cobalt, and various other non-recoverable components.

The above-mentioned problems also exist in the case of separating the metals from waste batteries containing copper, nickel, and cobalt other than waste LIB, and copper, nickel, and cobalt derived from other than waste batteries. Similarly exists when separating those metals from an alloy containing.

Japanese Unexamined Patent Publication No. 2012-172169 Japanese Unexamined Patent Publication No. 63-259033

The present invention has been proposed in view of such circumstances, and provides a method for efficiently separating copper and nickel and / or cobalt from an alloy containing copper and nickel and / or cobalt. The purpose is.

The present inventor has made extensive studies to solve the above-mentioned problems. As a result, an alloy containing copper and nickel and / or cobalt is used as the anode, and metal ions are eluted from the anode into the electrolytic solution by electrolytic treatment, and at that time, sulfur powder is added to the electrolytic solution for electrolytic treatment. We have found that copper and nickel and / or cobalt can be selectively and effectively separated by performing the above, and have completed the present invention.

(1) The first invention of the present invention is a method for separating copper and nickel and / or cobalt from an alloy, using an alloy containing copper and nickel and / or cobalt as an anode. This is a separation method in which sulfur powder is added to the electrolytic solution when metal ions are eluted from the anode into the electrolytic solution by electrolytic treatment.

(2) In the second invention of the present invention, in the first invention, the amount of the sulfur powder added to the electrolytic solution is the theoretical elution amount of copper ions calculated from the amount of current supplied in the electrolytic treatment. On the other hand, it is a separation method in the range of 1 to 3 equivalents (S-mol / Cu-mol).

(3) The third aspect of the present invention is the separation method in which the electrolytic solution is a sulfuric acid acidic solution in the first or second invention.

According to the present invention, copper and nickel and / or cobalt can be efficiently separated from an alloy containing copper and nickel and / or cobalt.

The electrolytic solution containing nickel and / or cobalt separated from the alloy can be used as it is as a stock solution for a battery material after removing impurity components such as iron, and nickel and cobalt can be used as they are by a known method. Can be separated and effectively reused as high-purity nickel and cobalt metals and salts. Furthermore, since the copper separated from the alloy is in the form of a sulfide suitable for copper smelting, it can be directly put into a copper smelting converter or the like and subjected to means such as electrolytic refining, thereby achieving high purity. Copper can be recovered.

Hereinafter, specific embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the following embodiments, and the gist of the present invention is changed. It can be implemented by making appropriate changes within the range that does not apply. In this specification, the notation "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

The separation method according to the present embodiment is a method for separating copper and nickel and / or cobalt from an alloy (alloy material) containing copper and nickel and / or cobalt.

As the alloy material containing copper and nickel and / or cobalt, which is the object of separation processing, for example, scrap of the lithium ion battery generated due to disposal due to deterioration of automobiles, electric devices, etc. or the life of the lithium ion battery ( Examples thereof include alloys obtained by heating and melting waste batteries (including defective products produced in the manufacturing process) such as waste lithium ion batteries () and reducing them. Further, waste batteries containing copper, nickel, and cobalt other than waste lithium ion batteries, and alloys containing copper, nickel, and cobalt other than batteries can also be used as alloys to be treated. Such an alloy obtained by dry-treating a waste battery such as a waste lithium ion battery is a copper alloy having low solubility and excellent corrosion resistance. It should be noted that the above-mentioned alloy does not exclude the addition of other metals, resins and the like as appropriate, and in that case, it is referred to as an alloy including other metals and resins.

Specifically, the separation method according to the present embodiment is a method in which an alloy containing copper and nickel and / or cobalt is used as an anode, and metal ions are eluted from the anode into the electrolytic solution by electrolytic treatment. The electrolytic treatment is characterized by adding sulfur powder to the electrolytic solution.

As described above, an alloy containing copper and nickel and / or cobalt is an alloy that is difficult to dissolve in an acidic solution such as sulfuric acid, but it is contained in the alloy by electrolyzing using such an alloy as an anode. The metal elutes in the form of ions (electrolytic elution). At this time, copper contained in the alloy is generated by adding sulfur powder (elemental sulfur: S ⁰ ) to an electrolytic solution such as an acidic sulfuric acid solution and energizing the state in which the sulfur powder is suspended in the electrolytic solution. Most of it can be selectively fixed as copper sulfide. On the other hand, nickel and / or cobalt contained in the alloy is eluted as metal ions in the electrolytic solution by the electrolytic treatment, so that copper and nickel and / or cobalt are separated by solid-liquid separation after the electrolytic treatment. , Can be separated efficiently.

Further, when the copper ion present in the electrolytic solution is not immobilized as copper sulfide and a part of the copper ion is eluted in the electrolytic solution as copper ion (Cu ²⁺ ), the copper ion is generated by continuing the electrolytic treatment. It can be electrolyzed on a cathode electrode (for example, a titanium plate) with priority over nickel ions (Ni ²⁺ ) and cobalt ions (Co ²⁺ ). From this point as well, copper and nickel / and cobalt can be effectively separated.

[About electrolytic treatment]
In the separation method according to the present embodiment, as described above, an alloy containing copper and nickel and / or cobalt (hereinafter, also simply referred to as “alloy”) is used as an anode (metal anode). Examples of the alloy to be separated include an alloy obtained by heating and melting a waste lithium ion battery and reducing it, and the anode plate is formed by casting the alloy into a plate shape.

The cathode is not particularly limited, and for example, titanium, stainless steel, platinum, platinum-plated titanium, a plate-shaped cathode of titanium and platinum, or the like can be used.

In the electrolytic treatment, the anode and the cathode made of an alloy are arranged so as to face each other in a predetermined electrolytic cell, and the electrolytic solution is charged into the electrolytic cell. After that, a current is supplied between the electrodes. As the electrolytic solution, a sulfuric acid-acidic electrolytic solution can be used.

According to such an electrolysis treatment, metal ions are eluted from the anode composed of the alloy into the electrolytic solution with the electrolysis. At this time, the present embodiment is characterized in that sulfur powder (elemental sulfur: S ⁰ ) is added to the electrolytic solution and the electrolytic treatment is performed in the coexistence of the sulfur powder.

[Reaction at the electrode by electrolytic treatment]
Specifically, electrolytic treatment is performed using an anode composed of an alloy containing copper and nickel and / or cobalt, and at that time, powdered sulfur is added to a sulfuric acid-acidic electrolytic solution and an electric current is passed. Copper on the surface of the alloy will be fixed as sulfide based on the coexisting sulfur powder. As a result, elution of copper ions (Cu ²⁺ ) into the electrolytic solution can be suppressed, and nickel and / or cobalt can be selectively eluted in the form of ions from the alloy.

More specifically, the reaction generated by this electrolytic treatment is shown in the following formula. That is, as shown in the following formula, on the side of the anode composed of the alloy, copper sulfide is generated by the contact between the copper metal on the surface of the alloy constituting the anode and the powdered sulfur present in the electrolytic solution. Reaction occurs (Equation 1). Further, nickel, cobalt, or a part of copper contained in the alloy loses electrons and elutes as ions in the electrolytic solution (formula 2-1 to formula 2-3).

(Anode side)
Cu + S → CuS ・ ・ ・ (Equation 1)
Ni-2e → Ni ²⁺ ... (Equation 2-1)
Co-2e → Co ²⁺ ... (Equation 2-2)
Cu-2e → Cu ²⁺ ... (Equation 2-3)

On the other hand, on the cathode side, an acid consumption reaction occurs in which hydrogen ions derived from sulfuric acid in a sulfuric acid-acidic electrolytic solution receive electrons and become hydrogen gas (Equation 3). Further, a reaction (formula 4) in which some copper ions (Cu ²⁺ ) eluted in the electrolytic solution receive electrons and precipitate as copper powder occurs. Some of the eluted copper ions are deposited on the cathode electrode (for example, a titanium plate) with priority over nickel ions (Ni ²⁺ ) and cobalt ions (Co ²⁺ ).

(Cathode side)
2H ⁺ + 2e → H ₂ ... (Equation 3)
Cu 2 ⁺ + 2e → Cu ⁰ ... (Equation 4)

As described above, in the present embodiment, since the electrolytic treatment using the anode composed of the alloy is performed in a state where the sulfur powder is added to the electrolytic solution and coexists, it is included in the alloy. The copper can be fixed as copper sulfide, while nickel and / or cobalt can be selectively eluted in the electrolytic solution in the form of ions to separate copper from nickel and / or cobalt. In addition, some copper ions eluted in the electrolytic solution are also electrolyzed onto the cathode preferentially over nickel ions and cobalt ions by the electrolytic treatment, so that they can be effectively separated and can be effectively separated in the electrolytic solution. Copper ions contained in can be almost eliminated.

[About sulfur powder to be added]
The sulfur powder (elemental sulfur: S ⁰ ) added to the electrolytic solution in the electrolytic treatment can be used without particular limitation, such as a crystalline powder such as a monoclinic crystal system or an orthorhombic crystal system, or an amorphous powder. ..

The particle size of the sulfur powder is not particularly limited, but it is preferable to use a sulfur powder having a particle size in the range of 1 μm to 45 μm. The particle size can be adjusted by crushing the sulfur powder with a mortar or pestle. The sulfur powder preferably has a high grade (sulfur grade), and for example, a sulfur powder having a sulfur grade of 99% or more is more preferable.

The amount of sulfur powder added to the electrolytic solution is 1 to 3 equivalents (S-mol / Cu-mol) with respect to the theoretical elution amount (molar amount) of copper ions calculated from the amount of current supplied in the electrolytic treatment. The range of 1.2 equivalents to 3 equivalents is more preferable, and the range of 1.5 equivalents to 2.8 equivalents is even more preferable. When the amount of sulfur powder added is 1 equivalent or more with respect to the theoretical elution amount of copper ions, copper can be more effectively fixed as copper sulfide and the elution of copper ions into the electrolytic solution is suppressed. can do. If sulfur powder exceeding 3 equivalents with respect to the theoretical elution amount of copper ions is added, the immobilization of copper is not promoted any more, and the sulfur powder remains in the electrolytic solution, so that the solid liquid after the electrolytic treatment is applied. Separation efficiency in separation may decrease.

As described above, in the separation method according to the present embodiment, copper can be immobilized as copper sulfide by the coexisting sulfur powder, and some copper ions eluted in the electrolytic solution are also preferentially treated. Since it can be electrodeposited on the cathode as copper powder, copper ions can be almost eliminated in the electrolytic solution. Therefore, after the electrolytic treatment, it is not necessary to perform a separate treatment such as a copper removal treatment using a copper removal facility or the like for the copper ions and nickel ions and / or cobalt ions contained in the electrolytic solution. The load of processing can be effectively reduced.

It should be noted that the operation of removing a trace amount of copper ions contained in a trace amount from the electrolytic solution recovered by solid-liquid separation after the electrolytic treatment is not excluded by the copper removal treatment, and such a copper removal treatment may be performed as appropriate. Specifically, as a method for removing copper ions remaining in the electrolytic solution (copper removal treatment method), a sulfide treatment by adding a sulfide agent, a separate electrolytic treatment, a neutralization treatment by adding a neutralizing agent, etc. are performed. A method of recovering the copper contained in the electrolytic solution as a precipitate can be mentioned.

As described above, in the separation method according to the present embodiment, when an alloy containing copper and nickel and / or cobalt is electrolytically eluted as a metal anode, sulfur powder is added and electrolytically treated to form an alloy. The contained copper can be recovered as a solid substance (copper sulfide and copper powder), and the solid substance can be efficiently separated into an electrolytic solution (leaching solution) containing nickel and / or cobalt.

The recovered copper solids such as copper sulfide and copper powder can be formed into an anode by, for example, being charged into a copper smelting converter or the like as it is as a raw material for an existing copper smelting treatment process. Then, high-purity copper can be obtained by electrolytic refining using the anode.

Further, nickel and cobalt leached into the electrolytic solution can be used as they are as the undiluted solution of the battery material after removing impurities such as iron as appropriate. Further, nickel metal and cobalt metal can be obtained by providing them in an existing nickel smelting treatment step, separating nickel and cobalt by means such as solvent extraction, and electrowinning them. It can also be purified as a nickel salt or a cobalt salt and recycled again as a battery raw material containing a lithium ion battery.

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

(Test condition)
The waste lithium-ion battery was subjected to a dry treatment of heating and melting to reduce it, and a molten metal of an alloy containing copper, nickel and cobalt was obtained and cast into a plate shape (electrode plate shape). Table 1 below shows the results (grade of the anode alloy component) obtained by cutting out a part of the obtained alloy and analyzing it using an ICP analyzer.

Next, an electrolytic elution test (Test Examples 1 to 3) was performed under the conditions shown in Table 2 below, using the obtained alloy (cast in a plate shape) as an anode. A titanium plate was used for the cathode, and the electrolytic area was processed with insulating tape so as to have an electrolytic area of 7.5 cm ² (7.5 cm × 1 cm).

Here, the electrolytic treatment was carried out in the presence of sulfur by adding sulfur powder (elemental sulfur: S ⁰ ) to the electrolytic solution. As the sulfur powder, sulfur flakes (sulfur grade: 99% or more) were crushed into powder in a mortar so that the size was in the range of 1 μm to 45 μm. Further, the "S / Cu equivalent (mol / mol)" shown in Table 2 is the theoretical copper calculated from the integrated current amount (A · h) applied when the anode alloy shown in Table 1 is electrolytically eluted. The amount of sulfur powder added (mol) with respect to the amount of ion elution (mol) is shown. In the case of an alloy contained in a waste lithium ion battery as in this test example, since the main component of the alloy is industrially copper, it was calculated using the theoretical elution amount of copper.

(Result: Presence / absence of sulfur powder addition and equivalent comparison)
An electrolytic elution test (Test Examples 1 to 3) was performed under the conditions shown in Table 2. Regarding the anode alloy after electrolytic elution, the slime adhering to the surface was thoroughly washed and removed, and then the weight was weighed, and the elution amount was confirmed from the weight before and after the electrolytic treatment.

Further, the solid matter (sulfur powder, cathode copper powder, anode slime) and the post-electrolyzed liquid in the electrolytic cell are separated into solid and liquid by suction filtration treatment using 5C quantitative filter paper under reduced pressure, and the solid matter is vacuum dried. Later, the weight was weighed and the amount of sediment recovered was confirmed. In addition, after confirming the amount of the liquid after electrolysis, the concentration and elution rate of each component were confirmed using an ICP analyzer. The elution rate (%) of each component was calculated by multiplying the elution amount of the theoretical alloy by the grade of each component as 100%.

The results of each are also shown in Table 2 above. As shown in Table 2, in Test Example 1 (basic conditions) in which electrolytic treatment was performed without adding sulfur powder, the elution rate of copper into the electrolytic solution was 60% (the remaining 40% was used as cathode copper powder). In contrast to (electrolysis), in Test Examples 2 and 3 in which sulfur powder was added and electrolyzed, the elution rate of copper into the electrolytic solution decreased to 19% regardless of the equivalent amount.

Further, it can be seen that at a level where the amount of sulfur powder added is large (Test Example 3: 2.8 equivalents), the elution rate of nickel and cobalt exceeds 100%, and nickel and cobalt are selectively eluted from the anode alloy. .. This is because the electrolytic treatment in the coexistence of the sulfur powder causes the copper on the surface of the anode alloy to react with the sulfur powder to generate copper sulfide (Equation 1 above), so that the elution of copper is suppressed. At the same time, it is considered that the elution of nickel and cobalt proceeded selectively instead of the elution of copper.

As described above, it was found that the elution of copper from the anode alloy can be suppressed by adding the sulfur powder and performing the electrolytic treatment. It was also found that the larger the amount of sulfur powder added, which is represented by the S / Cu equivalent (mol / mol), the more the leaching of nickel and cobalt is promoted, and as a result, the selective leaching of nickel and cobalt becomes possible. ..

Claims (3)

A method of separating copper from nickel and / or cobalt from an alloy.
A separation method in which an alloy containing copper and nickel and / or cobalt is used as an anode, and sulfur powder is added to the electrolytic solution when metal ions are eluted from the anode into the electrolytic solution by electrolytic treatment. The amount of the sulfur powder added to the electrolytic solution is in the range of 1 to 3 equivalents (S-mol / Cu-mol) with respect to the theoretical elution amount of copper ions calculated from the amount of current supplied in the electrolytic treatment. The separation method according to claim 1. The separation method according to claim 1 or 2, wherein the electrolytic solution is a sulfuric acid acidic solution.