JP6735192B2 - Lithium-ion battery scrap processing method - Google Patents

Description

The present invention relates to a method for treating lithium-ion battery scraps, and particularly proposes a technique that can be effectively used for recovering valuable metals from various lithium-ion battery scraps.

Lithium ion batteries, which are used in many industrial fields including various electronic devices, use a lithium metal salt containing manganese, nickel and cobalt as a positive electrode active material. Along with the increase in the number of batteries and the range of use, the amount of batteries discarded due to product life and defects in the manufacturing process is increasing.
Under such circumstances, it is desired to easily recover the above-mentioned expensive elements such as nickel and cobalt from a large amount of scrap lithium-ion battery scraps at a relatively low cost for reuse.

In order to treat lithium-ion battery scraps for recovering valuable metals, first, for example, powdery or granular lithium-ion battery scraps obtained through various steps such as roasting, crushing and sieving as required. Is leached with an aqueous solution of hydrogen peroxide, and lithium, nickel, cobalt, manganese, iron, copper, aluminum and the like which may be contained therein are dissolved in the solution to obtain a solution after leaching.

Then, a solvent extraction method is performed on the post-leaching solution to separate the metal elements. Here, in order to separate the respective metals leached in the liquid after leaching, the leaching liquid is sequentially subjected to solvent extraction or neutralization in a plurality of stages according to the metal to be separated, and further, at each stage. Each of the solutions obtained in 1. is subjected to back extraction, electrolysis, carbonation and other treatments. Specifically, each valuable metal can be recovered by first recovering iron and aluminum, then manganese and copper, and then cobalt, and then nickel, and finally leaving lithium in the aqueous phase. ..

As a conventional technique of this kind, Patent Document 1 discloses a method of recovering nickel from a sulfuric acid acidic aqueous solution containing nickel and cobalt and iron, aluminum and manganese and other impurity elements. Iron and aluminum are removed by an oxidative neutralization treatment, and then a mixed hydroxide containing nickel and cobalt is separated and recovered by the neutralization treatment, and then the concentrated liquid obtained by dissolving the mixed hydroxide is obtained. It is described that a back extraction liquid containing cobalt and nickel respectively is obtained by a solvent extraction treatment.
Further, in Patent Document 2, solvent extraction under predetermined conditions is performed on a metal mixed aqueous solution containing a metal group A made of lithium, manganese, nickel, and cobalt and a metal group B made of copper, aluminum, and iron. It is described that each metal is separated by sequentially performing.

JP, 2010-180439, A Japanese Patent No. 5706457

As described above, many treatments are required to separate and recover each metal from the post-leaching solution containing a plurality of types of metal ions. Therefore, of the multiple types of metal ions contained in the post-leaching solution, if a specific metal ion can be left as a solid without being dissolved, a post-leaching solution for separating and recovering each metal in the subsequent recovery step. Among the various treatments to be carried out on 1, the treatments necessary for recovering the metal left as a solid can be simplified or omitted, which is effective from the viewpoint of treatment efficiency and cost.
In particular, when copper ions are contained in the liquid after leaching at a high concentration, for example, in the electrolysis step after solvent extraction and back extraction of cobalt, it may cause an abnormal electrodeposition, and in the post step. There is a problem that the load is heavy.

The present invention has an object to solve such a problem that the conventional technology has, and an object of the invention is to leach lithium-ion battery scrap containing copper as much as possible by leaching copper. It is an object of the present invention to provide a method for treating lithium-ion battery scrap, which can be left as a solid without being dissolved in an acidic solution to reduce the load in a later step.

As a result of intensive studies by the inventor, when the lithium-ion battery scrap containing copper is leached by bringing it into contact with an acidic solution, oxidation dissolution of copper is suppressed while cobalt or the like remains as a solid in the acidic solution. It was newly found that when the cobalt etc. are not completely leached and the cobalt etc. is completely dissolved thereafter, the leaching of copper starts and the redox potential rapidly rises accordingly.
Then, by utilizing this, it was thought that copper could be left as a solid without being dissolved in the acidic solution.

Based on this knowledge, the method for treating lithium ion battery scrap of the present invention has a leaching step of leaching the lithium ion battery scrap by contacting the lithium ion battery scrap containing at least copper with an acidic solution, and applying the leaching step to the leaching step. Then, at the timing when the oxidation-reduction potential (ORPvsAg/AgCl) of the acidic solution starts to rapidly rise, a metal piece containing at least one element of iron, nickel and cobalt is added to the acidic solution, and the metal piece is added. The timing is to be from when the rate of increase of the oxidation-reduction potential becomes 15 mV/min or more until 5 minutes have elapsed .

In the method for treating lithium-ion battery scrap of the present invention, the post-leaching solution obtained in the leaching step contains aluminum and iron, and the post-leaching solution is neutralized to a pH within a range of 4.0 to 6.0 and then solidified. Liquid separation is performed, and a dealumination step of removing aluminum in the solution after leaching is performed, and after the dealumination step, an oxidizing agent is added to adjust the pH within the range of 3.0 to 5.0, and then solidified. It is preferable to further include a deironing step of performing liquid separation and removing iron.
Here, in the leaching step, copper contained in the lithium-ion battery scrap is left as a solid in the liquid after leaching, and in the dealumination step, copper in the leaching solution is removed together with aluminum by solid-liquid separation. More preferably.

In the method for treating lithium ion battery scrap of the present invention, the post-leaching solution obtained in the leaching step contains aluminum and iron, and after solid-liquid separation is performed on the post-leaching solution, an oxidizer is added. Then, after adjusting the pH within the range of 3.0 to 4.0, solid-liquid separation is performed to remove iron, and after the iron removal step, within the range of pH 4.0 to 6.0. It is preferable to further include a dealumination step of removing aluminum by performing solid-liquid separation after neutralization.

The oxidizing agent added in the iron removal step described above is preferably one or more selected from the group consisting of manganese dioxide, a positive electrode active material, and a manganese-containing leaching residue obtained by leaching the positive electrode active material. ..

The post-separation liquid obtained through the dealumination process and the iron removal process described above contains manganese, copper, iron and/or aluminum dissolved in the post-separation liquid, and solvent extraction is performed on the post-separation liquid. It is preferable to further include an extraction step of removing manganese, copper, iron and/or aluminum from the liquid after the separation.
In this extraction step, it is preferable to perform solvent extraction on the post-separation liquid using a mixed extractant containing a phosphoric acid ester-based extractant and an oxime-based extractant.

The lithium ion battery scrap processing method of the present invention preferably further includes a cobalt/nickel recovery step of recovering cobalt and/or nickel from the extraction residual liquid after the above extraction step.
Further, it is preferable to further include a lithium recovery step of recovering lithium after the cobalt/nickel recovery step.

According to the lithium-ion battery scrap processing method of the present invention, in the leaching step, a metal piece containing at least one element of iron, nickel and cobalt is added at the timing when the oxidation-reduction potential of the acidic solution starts to rise rapidly. Since the dissolution of copper is suppressed by adding it to the acidic solution, copper can be left as a solid without being dissolved in the acidic solution as much as possible to reduce the load in the subsequent steps.

It is a flow figure showing one embodiment of the processing method of the lithium ion battery scrap of this invention. It is a flowchart which shows other embodiment of the processing method of the lithium ion battery scrap of this invention. It is a graph which shows the change of ORP, pH, and Cu density|concentration with progress of time in an Example. It is a graph which shows the change of ORP, pH, and Cu density|concentration with progress of time in a comparative example.

Hereinafter, embodiments of the present invention will be described in detail.
In the method for treating a lithium-ion battery scrap according to one embodiment of the present invention, in the leaching step of leaching the lithium-ion battery scrap by bringing the lithium-ion battery scrap containing at least copper into contact with the acidic solution, the oxidation reduction of the acidic solution is performed. At the timing when the potential (ORPvsAg/AgCl) starts to rapidly rise, a metal piece of a metal of at least one element of iron, nickel and cobalt or an alloy containing the at least one element is added to the acidic solution. ..

(Lithium-ion battery scrap)
The lithium-ion battery scrap targeted by the present invention may be any scrap of lithium-ion batteries used in various electronic devices such as mobile phones and the like. It is preferable from the viewpoint of effective utilization of resources to target those that have been discarded due to manufacturing defects or other reasons.

As the lithium-ion battery scrap, it can be so-called battery slag, may be a mixture of this battery slag with a positive electrode material with an aluminum foil or a positive electrode active material, also, the battery slag, if necessary, roasted, It may be chemically treated, crushed, and/or sieved.

In addition to the positive electrode active material, which is a lithium metal salt containing manganese, nickel and cobalt, the negative electrode material containing carbon, iron and copper, the aluminum foil to which the positive electrode active material is attached, and the aluminum of the lithium ion battery A housing may be included. Specifically, in a lithium ion battery, a single metal oxide composed of one element of lithium, nickel, cobalt, and manganese constituting a positive electrode active material and/or a composite metal oxide composed of two or more elements. Objects, as well as aluminum, copper, iron, carbon and the like.

In the present invention, it is particularly effective to target a lithium ion battery scrap containing copper in an amount of 0.5% by mass to 5% by mass, preferably 1% by mass to 15% by mass. When such a lithium-ion battery scrap containing a relatively large amount of copper is leached by the conventional method, solvent extraction is performed on a solution in which a large amount of copper is dissolved. This will cause the occurrence of. When the amount of copper contained in the lithium-ion battery scrap is too small, this is not a serious problem, but the effect of applying the present invention is small.

(Leaching process)
In the leaching step, for example, the powdery lithium ion battery scrap obtained under the sieve by crushing and sieving is brought into contact with an acidic solution such as a sulfuric acid acidic solution as a leaching solution to be leached. Thereby, a post-leaching solution in which a predetermined metal contained in the lithium-ion battery scrap is leached is obtained.

Here, in this embodiment, the oxidation-reduction potential (ORPvsAg/AgCl) of the acidic solution charged with the lithium-ion battery scrap is measured every few minutes such as 0.5 minutes or 0.1 minutes, and the redox potential thereof is measured. At the timing when the electric potential started to rise sharply as compared with the change so far, the acidic solution contained a metal of at least one element of iron, nickel and cobalt, or a metal composed of an alloy containing the at least one element. Add pieces.

When the acidic solution and the lithium-ion battery scrap containing copper are brought into contact with each other, for example, cobalt of the positive electrode active material that may be contained in the lithium-ion battery scrap, aluminum of the aluminum foil, or the like becomes a base metal than copper. Due to this, it dissolves before copper, and when the metals are completely dissolved thereafter, the dissolution of copper starts and the redox potential rises sharply.
By adding iron, nickel, and/or cobalt to the acidic solution at this timing, the added metal is dissolved instead of copper, and the dissolution of copper is suppressed and copper is not leached. It should be noted that here, when the oxidation-reduction potential rapidly rises and the dissolution of copper begins after reaching the ORP value at which copper is dissolved, even if copper is slightly dissolved before the addition of iron, nickel and/or cobalt. It is considered that copper may return from an ion to a solid with the dissolution of added iron, nickel and/or cobalt. In any case, the addition of iron, nickel and/or cobalt contributes to leaving copper as a solid in the post-leaching solution obtained in the leaching step.

Regarding the timing of adding the metal piece to the acidic solution, specifically, after the acidic solution and the lithium ion battery scrap are brought into contact with each other, the rate of increase of the oxidation-reduction potential of the acidic solution is 15 mV/min or more, preferably 30 mV/min. When the rate of increase of the oxidation-reduction potential once reaches 15 mV/min or more, 5 minutes have elapsed, preferably 1 minute has elapsed. Is preferred. When the rate of increase of the oxidation-reduction potential is less than 15 mV/min, it is considered that cobalt or the like that may be contained in the lithium-ion battery scrap is not completely dissolved and copper is not yet dissolved. Further, it is feared that a considerable amount of copper is already dissolved after 5 minutes have passed since the rate of increase of the redox potential was 15 mV/min or more.

More specifically, when the redox potential of the acidic solution is, for example, −300 mV or more and −100 mV or less, preferably −250 mV or more and −200 mV or less, the above-mentioned metal piece is added. You can If metal pieces are added when the oxidation-reduction potential is too low, it is considered that cobalt, which may be contained in lithium-ion battery scrap, is not completely dissolved and copper is not yet dissolved. This is because if the metal piece is added in a state where the reduction potential is too high, it is feared that copper has already been dissolved.

The metal piece added to the acidic solution is a metal containing at least one element of iron, nickel, and cobalt, and it does not matter whether it is a simple metal or an alloy.
Iron, nickel, and cobalt have an ionization tendency larger than that of copper and are more easily melted than copper, so that the leaching of copper as described above can be suppressed. Moreover, these elements are often contained in the lithium ion battery scrap in the first place, and are easily removed or recovered after the leaching step. It should be noted that aluminum also has a greater ionization tendency than copper and can be contained in lithium-ion battery scrap, but it is relatively unfavorable as an additive element to an acidic solution because it is relatively difficult to remove after the leaching step.

The above-mentioned elements are added to the acidic solution in the form of metal pieces because they facilitate recovery by solid-liquid separation in various steps after the leaching step. The metal piece may be, for example, a plate-like or foil-like material having a maximum dimension of preferably 1 mm to 1000 mm, more preferably 10 mm to 100 mm. If the metal piece has a size within this range, a contact area with an acidic solution that can be effectively dissolved is secured, and the undissolved material after dissolution can be easily recovered in a subsequent step. When it is made into a fine powder, it may take time and equipment to collect it after the leaching step.On the other hand, when it is made into a block or a lump having a certain size, the contact area with the acidic solution becomes small. May not be dissolved so much that the dissolution of copper may not be effectively suppressed.

In the leaching step, the pH of the leaching solution can be 0 to 2.0. If the pH at this time is too high, the leaching rate of cobalt and nickel may not be sufficient. On the other hand, if the pH is too low, the leaching proceeds rapidly and copper is leached. This is because there is a possibility that the cost will increase due to the pH adjustment when it is necessary to raise the pH.

In the leaching step, the leaching time from the time when the lithium ion battery scrap is added to the acidic solution to the end of the leaching is preferably 0.5 hours to 10 hours. If the reaction time is too short, the desired cobalt or nickel may not be sufficiently dissolved. On the other hand, if the leaching time is too long, the dissolution of copper may start. The more preferable range of the leaching time is 1 hour to 5 hours, and further preferably 1 hour to 3 hours.

After the leaching step described above, for example, the steps of the embodiment shown in FIG. 1 or the embodiment shown in FIG. 2 can be performed. Each embodiment will be described in detail below.

<Embodiment shown in FIG. 1>
In the embodiment shown in FIG. 1, after the above leaching step, a dealumination step and an iron removal step are performed in this order, and then a cobalt/nickel recovery step and a lithium recovery step are performed through an extraction step.

(Dealuminization process)
In the dealumination step, the pH of the post-leaching solution obtained in the above-mentioned leaching step is increased to a range of 4.0 to 6.0 for neutralization to precipitate aluminum in the post-leaching solution, The aluminum is removed by the subsequent solid-liquid separation.

In this dealumination step, if the pH is too low, aluminum cannot be sufficiently precipitated, while if the pH is too high, other metals such as cobalt will also be precipitated. From this viewpoint, the pH of the solution after leaching in the dealumination step is more preferably 4.0 to 6.0, and particularly preferably 4.5 to 5.0.
In the dealumination step, since the pH is raised within the above range, an alkali such as sodium hydroxide, sodium carbonate or ammonia can be added to the post-leaching solution.

In the dealumination step, the redox potential (ORPvsAg/AgCl) of the solution after leaching is preferably −500 mV to 100 mV, and more preferably −400 mV to 0 mV. If the redox potential at this time is too high, cobalt may precipitate as tricobalt tetroxide (Co ₃ O ₄ ). On the other hand, if the redox potential is too low, cobalt may be a single metal (Co metal). ) And is likely to precipitate.

In addition, in the dealumination step, it is preferable that the temperature of the liquid after leaching is 50°C to 90°C. This means that if the temperature of the liquid after leaching is lower than 50°C, the reactivity may deteriorate, and if it is higher than 90°C, a device capable of withstanding high heat is required, and for safety reasons. Is also not preferable.

After the aluminum is sufficiently precipitated as described above, solid-liquid separation is performed using a known device and method such as a filter press or thickener to mainly remove the precipitated aluminum.
In the solid-liquid separation in the dealumination step, copper that has not been melted and remains as a solid in the leaching step and carbon that can be contained in the lithium ion battery scrap can also be separated. In this solid-liquid separation, copper can be removed together with aluminum, so that solid-liquid separation for removing copper alone immediately after the leaching step can be omitted, and treatment efficiency can be improved and cost can be reduced. it can. Therefore, it is preferable that the solid-liquid separation is not performed after the leaching step and before the dealumination step, and the copper in the liquid after leaching remains as a solid.

Further, when trying to filter the precipitate of only aluminum, it is difficult to filter the gel-like aluminum precipitate, which leads to a decrease in the filtration rate, but in the solid-liquid separation in this dealumination step, the precipitate becomes Since not only aluminum but also copper, carbon, etc. are contained, such copper, carbon, etc. can compensate for the difficulty in filtering the gel-like aluminum precipitate and shorten the time required for filtration.

In the case where the post-leaching solution obtained in the above-mentioned leaching step contains lithium dissolved therein, the molar ratio of lithium to aluminum (Li/Al ratio) in the post-leaching solution should be 1.1 or more. For example, aluminum contained in the precipitate in the dealumination step produces gel-like Al(OH) ₃ as well as crystalline complex oxides such as LiAlO ₂ and LiAl ₂ (OH) ₇ , and complex hydroxides. Then, it becomes a powder-like form. In this case, the filtration time can be further shortened. From this viewpoint, the molar ratio of lithium to aluminum (Li/Al ratio) in the liquid after leaching is preferably 1.1 or more.

The lithium in the post-leaching solution may be lithium that is originally contained in the lithium-ion battery scrap, which has been acid-leached.In addition, other lithium-containing materials may be added to the post-leaching solution to remove the acid. It can also be used. Also, the addition of the lithium-containing material makes it possible to adjust the Al/Li ratio in the liquid after leaching. As the lithium-containing material, a reagent may be used, but lithium carbonate, lithium hydroxide or other lithium compound obtained in the process of treating lithium-ion battery scrap, or at least one of these dissolved in water The obtained lithium aqueous solution is preferable.

(Deferring process)
In the iron removal step, the solution obtained in the above dealumination step is added with an oxidizing agent, and the pH is adjusted within the range of 3.0 to 5.0 to precipitate iron in the solution, Such iron is removed by the subsequent solid-liquid separation.

In this iron removal step, the iron in the solution is oxidized from divalent to trivalent by the addition of an oxidizing agent, and trivalent iron is oxidized (hydroxylated) at a pH lower than that of divalent iron. Since it precipitates as a substance), iron can be precipitated by adjusting to a relatively low pH as described above. In many cases, iron precipitates as a solid such as iron hydroxide (Fe(OH) ₃ ).
Here, if the pH is raised significantly, it causes the precipitation of cobalt, but in this deironing step, the iron can be precipitated without raising the pH so much, so that the precipitation of cobalt at this time is prevented. It can be effectively suppressed.

In the iron removal step, if the pH is too low, iron cannot be sufficiently precipitated, while if the pH is too high, other metals such as cobalt will also be precipitated. From this viewpoint, the pH in the deironing step is more preferably 3.0 to 4.0, and particularly preferably 3.0 to 3.5.

In the iron removal step, the redox potential (ORPvsAg/AgCl) of the solution is preferably 300 mV to 900 mV, more preferably 500 mV to 700 mV. If the oxidation-reduction potential at this time is too low, iron may not be oxidized, while if the oxidation-reduction potential is too high, cobalt may be oxidized and precipitated as an oxide.

In the iron removal step, the pH is lowered to the above-mentioned range prior to the addition of the oxidizing agent, so that an acid such as sulfuric acid, hydrochloric acid or nitric acid can be added.

The oxidizing agent added in the iron removal step is not particularly limited as long as it can oxidize iron, but manganese dioxide, a positive electrode active material, and/or a manganese-containing leaching residue obtained by leaching the positive electrode active material. Is preferred. These are able to effectively oxidize iron in solution. The manganese-containing leaching residue obtained by leaching the positive electrode active material with an acid or the like may contain manganese dioxide.
When the above positive electrode active material or the like is used as the oxidizing agent, a precipitation reaction occurs in which manganese dissolved in the solution becomes manganese dioxide, so that the precipitated manganese can be removed together with iron.

After the addition of the oxidizing agent, alkali such as sodium hydroxide, sodium carbonate or ammonia can be added to adjust the pH within a predetermined range.

(Extraction process)
When manganese is contained in the post-separation liquid obtained through the dealumination process and deironing process due to the inclusion of manganese in the lithium-ion battery scrap, etc., and the leaching process, dealumination process, and deironing process described earlier In some cases, copper, aluminum, and iron that have not been removed and remain in the post-separation liquid, and in this case, an extraction step of extracting manganese or the like from the post-separation liquid can be performed. However, when the liquid after separation does not contain manganese or the like, this extraction step can be omitted.

Specifically, in the extraction step, solvent extraction is performed on the post-separation liquid after the iron removal step using a mixed extractant containing a phosphoric acid ester-based extractant and an oxime-based extractant to obtain manganese, copper, iron. And/or aluminum can be separated.
In particular, the combined use of the phosphoric acid ester-based extractant and the oxime-based extractant markedly improves the separation efficiency of copper, iron, and aluminum. Most of all, copper can be extracted.

(Cobalt/Nickel recovery process)
After the manganese extraction step, cobalt and/or nickel in the extraction residual liquid is recovered. The recovery of cobalt and/or nickel can be performed by known methods. Specifically, solvent extraction of cobalt and nickel is performed sequentially, cobalt in the solvent is transferred to the aqueous phase by back extraction and recovered by electrowinning, and nickel in the solvent is also back extracted and electrolyzed. It can be collected by collection.

(Lithium recovery process)
If lithium remains after the cobalt/nickel recovery step, the lithium in the aqueous phase can be carbonized and recovered as lithium carbonate, for example.

<Embodiment shown in FIG. 2>
In the embodiment shown in FIG. 2, after the leaching step described above, the iron removal step and the dealumination step are performed in this order, which is the reverse of the embodiment shown in FIG. Then, after the extraction process, a cobalt/nickel recovery process and a lithium recovery process are performed.
In the embodiment shown in FIG. 2, at the end of the leaching step described above, solid-liquid separation is performed on the post-leaching solution by using a known device and method such as a filter press or thickener, and copper contained in the post-leaching solution is removed. Solids, etc. can be removed.

(Deferring process)
After solid-liquid separation in the leaching step, as an iron removal step, an oxidizing agent is added and the pH is adjusted within the range of 3.0 to 4.0 to precipitate iron in the solution, and then the solid is removed. Liquid separation removes such iron.
In this deironing step, the iron in the solution is oxidized from divalent to trivalent by the addition of an oxidizing agent, and the trivalent iron precipitates as an oxide (hydroxide) at a pH lower than that of divalent iron. Therefore, iron can be precipitated by adjusting to a relatively low pH as described above. In many cases, iron precipitates as a solid such as iron hydroxide (Fe(OH) ₃ ).
When the pH is raised significantly, cobalt is precipitated, but in this deironing step, iron can be precipitated without raising the pH so much, so that the precipitation of cobalt at this time is effectively suppressed. be able to.

In the iron removal step, if the pH is too low, iron cannot be sufficiently precipitated, while if the pH is too high, other metals such as cobalt will also be precipitated. From this viewpoint, the pH in the deironing step is more preferably 3.0 to 4.0.

In the iron removal step, the redox potential (ORPvsAg/AgCl) of the solution is preferably 500 mV to 1400 mV, more preferably 700 mV to 1200 mV. If the redox potential at this time is too high, cobalt may be oxidized and precipitated as an oxide. On the other hand, if the redox potential is too low, iron may not be oxidized.

The oxidizing agent added in the iron removal step is not particularly limited as long as it can oxidize iron, but manganese dioxide, a positive electrode active material, and/or a manganese-containing leaching residue obtained by leaching the positive electrode active material. Is preferred. These are able to effectively oxidize iron in solution. The manganese-containing leaching residue obtained by leaching the positive electrode active material with an acid or the like may contain manganese dioxide.
When the above positive electrode active material is used as the oxidizing agent, manganese dissolved in the solution causes a precipitation reaction to form manganese dioxide, so that the precipitated manganese can be removed together with iron.

Further, in the deferring step, in order to adjust the pH within the above range, for example, an alkali such as sodium hydroxide, sodium carbonate or ammonia can be added.

(Dealuminization process)
In the dealumination step, the pH of the solution obtained in the above deferring step is raised to be in the range of 4.0 to 6.0 for neutralization to precipitate aluminum in the solution, and then Such aluminum is removed by solid-liquid separation.

In this dealumination step, if the pH is too low, aluminum cannot be sufficiently precipitated, while if the pH is too high, other metals such as cobalt will also be precipitated. From this viewpoint, the pH in the dealumination step is more preferably 4.0 to 6.0, and particularly preferably 4.5 to 5.0.
In the dealumination step, in order to raise the pH within the above range, for example, an alkali such as sodium hydroxide, sodium carbonate or ammonia can be added.

In addition, in the dealumination step, it is preferable that the temperature of the solution is 60°C to 90°C. This means that if the temperature is lower than 60°C, the reactivity may deteriorate, and if the temperature is higher than 90°C, a device capable of withstanding high heat is required and it is not preferable in terms of safety. .. Therefore, the temperature of the solution is preferably 60°C to 90°C.

Here, when the post-leaching solution obtained in the above-mentioned leaching step contains dissolved lithium, the molar ratio of lithium to aluminum (Li/Al ratio) in the post-leaching solution may be set to 1.1 or more, It is preferable in terms of improving the filterability of the precipitate in this dealumination step. In this case, aluminum contained in the precipitate in the dealumination step is not only gel Al(OH) ₃ but also crystalline oxides such as LiAlO ₂ and LiAl ₂ (OH) ₇ and complex hydroxides. This precipitate, which is formed and has a form close to a powder, is easy to filter during solid-liquid separation, and therefore the time required for filtration during solid-liquid separation in the dealumination step can be shortened.
From this viewpoint, the molar ratio of lithium to aluminum (Li/Al ratio) in the liquid after leaching is preferably 1.1 or more.

The lithium in the solution after leaching can be lithium that is originally contained in the lithium-ion battery scrap and is acid leached.In addition, other lithium-containing materials can be added to the solution after leaching to add this to acid leaching. It can also be made. Also, the addition of the lithium-containing material makes it possible to adjust the Al/Li ratio in the liquid after leaching. As the lithium-containing material, a reagent may be used, but lithium carbonate, lithium hydroxide or other lithium compound obtained in the process of treating lithium-ion battery scrap, or at least one of these dissolved in water The obtained lithium aqueous solution is preferable.

(Extraction process)
When manganese is contained in the post-separation liquid obtained through the deironing process and the dealumination process due to the inclusion of manganese in the lithium-ion battery scrap, etc. In some cases, the copper, iron, and aluminum that have not been removed but remain in the post-separation liquid may be included. In this case, an extraction step of extracting manganese or the like from the post-separation liquid may be performed. However, if the liquid after separation does not contain manganese or the like, this extraction step can be omitted.

Specifically, in the extraction step, solvent extraction is performed on the post-separation liquid after the dealumination step using a mixed extraction agent containing a phosphoric acid ester-based extraction agent and an oxime-based extraction agent to obtain manganese, copper, iron. And/or aluminum can be separated.
In particular, the combined use of the phosphoric acid ester-based extractant and the oxime-based extractant markedly improves the separation efficiency of copper, iron, and aluminum. Most of all, copper can be extracted.

(Cobalt/Nickel recovery process)
After the manganese extraction step, cobalt and/or nickel in the extraction residual liquid is recovered. The recovery of cobalt and/or nickel can be performed by known methods. Specifically, solvent extraction of cobalt and nickel is performed sequentially, cobalt in the solvent is transferred to the aqueous phase by back extraction and recovered by electrowinning, and nickel in the solvent is also back extracted and electrolyzed. It can be collected by collection.

(Lithium recovery process)
If lithium remains after the cobalt/nickel recovery step, the lithium in the aqueous phase can be carbonized and recovered as lithium carbonate, for example.

Next, the present invention was carried out on a trial basis, and the effect thereof was confirmed. However, the description here is for illustrative purposes only and is not intended to be limiting.

41.1 g of battery powder having the quality shown in Table 1 as lithium-ion battery scrap was put into pure water, stirred at a speed of 500 rpm, and 98% concentrated sulfuric acid was added thereto so that the pH was 1.8. The acidic solution obtained was heated to 70°C.

Then, stirring was continued at 70° C. until the ORP of the acidic solution became −250 mV (Ag/AgCl), and concentrated sulfuric acid was appropriately added so that the pH was maintained at 1.8 during this period.
In the example, when the ORP of the acidic solution reached −250 mV, 0.5 g of Co metal pieces were added to the acidic solution, and after the addition, stirring was continued at 70° C. for 30 minutes. On the other hand, in Comparative Example, stirring was continued at 70° C. for 30 minutes after the ORP of the acidic solution reached −250 mV without adding such metal pieces.

The changes in ORP, pH, and Cu concentration over time in each of these examples and comparative examples are shown graphically in FIGS. 3 and 4, respectively. Further, the measured values of ORP, pH and Cu concentration in each of the example and the comparative example are shown in Table 2 and Table 3 together with the ORP increasing rate.
Here, the time when the liquid temperature reached 70° C. was set to 0 h.

In the example, as shown in FIG. 3, the Cu concentration in the acidic solution could be suppressed low by adding the metal piece at the timing when the ORP rapidly increased. On the other hand, in the comparative example, as shown in FIG. 4, the Cu concentration was significantly increased because the metal piece was not added.

From the above test results, it has been found that according to the present invention, copper can be left as a solid without being dissolved in an acidic solution in the leaching step, which can contribute to the reduction of the load in the subsequent step.

Claims (9)

Contacting a lithium-ion battery scrap containing at least copper with an acidic solution, and having a leaching step of leaching the lithium-ion battery scrap,
In the leaching step, at a timing when the oxidation-reduction potential (ORPvsAg/AgCl) of the acidic solution starts to rapidly increase, a metal piece containing at least one element of iron, nickel and cobalt is added to the acidic solution,
A method for treating a lithium-ion battery scrap , wherein the timing of adding the metal piece is from the time when the rate of increase of the redox potential becomes 15 mV/min or more until 5 minutes have elapsed . The post-leaching liquid obtained in the leaching step contains aluminum and iron,
The post-leaching solution is neutralized to a pH range of 4.0 to 6.0, and solid-liquid separation is performed to remove aluminum in the post-leaching solution, and an oxidizer after the dealumination step. Of the lithium ion battery scrap according to claim 1, further comprising a deironing step of removing iron by performing solid-liquid separation after adjusting the pH to a range of 3.0 to 5.0 by adding. Processing method. In the leaching step, copper contained in lithium-ion battery scrap is left in the liquid after leaching as a solid, and in the dealumination step, copper in the leaching solution is removed together with aluminum by solid-liquid separation. Item 3. A method for treating lithium-ion battery scrap according to Item 2 . The post-leaching liquid obtained in the leaching step contains aluminum and iron,
After the solid-liquid separation is performed on the post-leaching liquid, an oxidizing agent is added to adjust the pH within the range of 3.0 to 4.0, and then the solid-liquid separation is performed to remove iron. The lithium according to claim 1, further comprising a step and a dealuminizing step of removing aluminum by performing solid-liquid separation after neutralizing the pH within a range of 4.0 to 6.0 after the deironing step. Ion battery scrap processing method. The oxidizing agent to be added in the deferrisation step, manganese dioxide, the positive electrode active material, and, the one or more selected from the group consisting of manganese-containing leach residue obtained by leaching the positive electrode active material, according to claim 2-4 The method for treating lithium-ion battery scrap according to any one of 1. The post-separation liquid obtained through the dealumination process and the iron removal process contains manganese, copper, iron and/or aluminum dissolved in the post-separation liquid,
Wherein performs solvent extraction on the post-separation solution, the manganese from the separation after the liquid, copper, iron and / or further comprising an extraction step for removing aluminum, lithium ions according to any one of claims 2-5 Battery scrap processing method. The method for treating lithium ion battery scrap according to claim 6 , wherein solvent extraction is performed on the post-separation liquid using a mixed extractant containing a phosphoric acid ester-based extractant and an oxime-based extractant in the extraction step. The method for treating lithium-ion battery scrap according to claim 7 , further comprising a cobalt/nickel recovery step of recovering cobalt and/or nickel from the extraction residual liquid after the extraction step. The method for treating lithium ion battery scrap according to claim 8 , further comprising a lithium recovery step of recovering lithium after the cobalt/nickel recovery step.