Treatment method and treatment system for waste lithium ion battery

Abstract

A method and system for treating a waste lithium ion battery for recovering lithium from a fluorine-containing waste lithium ion battery, the method comprising: introducing a roasted product obtained by roasting the waste lithium ion battery into a first dissolving tank and immersing the roasted product in water; performing first solid-liquid separation on the immersed aqueous solution in the first dissolving tank, recovering the lithium from the aqueous solution separated by the first solid-liquid separation, introducing the immersed residue in the first dissolving tank into a second dissolving tank different from the first dissolving tank, and immersing the immersed residue in water; calcium hydroxide is added to the water in the second dissolving tank, a second solid-liquid separation is performed on the immersed aqueous solution in the second dissolving tank, and the remaining calcium and lithium from the calcium hydroxide are separated from the aqueous solution separated by the second solid-liquid separation.

Description

Technical Field

[0001] The present disclosure relates to a method and system for treating spent lithium-ion batteries. Background Art

[0002] To recover lithium contained in lithium-ion batteries, waste lithium-ion batteries are calcined, and the calcined product is immersed in water to dissolve lithium ions in the water, thereby separating the lithium from impurities.

[0003] However, lithium-ion batteries contain a large amount of fluorine in the electrolyte, binder, etc., and when spent lithium-ion batteries are roasted, lithium ions may combine with fluoride ions to form lithium fluoride. Lithium fluoride is difficult to dissolve in water, so when lithium fluoride is discarded as residue, the recovery rate of lithium is reduced.

[0004] Patent Document 1 listed below describes adding calcium hydroxide to a lithium solution containing fluorine and lithium in order to separate lithium from the lithium solution.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2021 / 090571 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] However, even when calcium hydroxide is added to a dissolution tank in which the calcined product is immersed in water, lithium fluoride does not actually dissolve, and fluorine and lithium cannot be separated.

[0010] The present disclosure is made in view of the above-mentioned problems, and its purpose is to provide a method and system for treating spent lithium-ion batteries that can promote the dissolution of lithium fluoride and improve the recovery rate of lithium.

[0011] Means for solving problems

[0012] One embodiment of the present disclosure relates to a method for treating waste lithium-ion batteries for recovering lithium from waste lithium-ion batteries containing fluorine, wherein a calcined product obtained by calcining the waste lithium-ion battery is introduced into a first dissolution tank and immersed in water, a first solid-liquid separation is performed on the aqueous solution after immersion in the first dissolution tank, and the lithium is recovered from the aqueous solution separated by the first solid-liquid separation. The immersion residue in the first dissolution tank is introduced into a second dissolution tank different from the first dissolution tank and immersed in water, calcium hydroxide is added to the water in the second dissolution tank, a second solid-liquid separation is performed on the aqueous solution after immersion in the second dissolution tank, and residual calcium from the calcium hydroxide and the lithium are separated from the aqueous solution separated by the second solid-liquid separation.

[0013] In addition, another embodiment of the waste lithium-ion battery processing system disclosed in the present invention is a waste lithium-ion battery processing system for recovering lithium from waste lithium-ion batteries containing fluorine, which comprises: a first dissolution tank, which introduces a roasted product obtained by roasting the above-mentioned waste lithium-ion battery and immerses it in water; a first separator, which performs a first solid-liquid separation on the impregnated aqueous solution in the above-mentioned first dissolution tank; a lithium recovery device, which recovers the above-mentioned lithium from the aqueous solution separated by the above-mentioned first separator; a second dissolution tank, which introduces the impregnated residue in the above-mentioned first dissolution tank into water to which calcium hydroxide is added and immerses it, and the second dissolution tank is different from the above-mentioned first dissolution tank; a second separator, which performs a second solid-liquid separation on the impregnated aqueous solution in the above-mentioned second dissolution tank; and a calcium separation device, which separates the remaining calcium from the above-mentioned calcium hydroxide and the above-mentioned lithium from the aqueous solution separated by the above-mentioned second solid-liquid separation.

[0014] Effects of the Invention

[0015] According to the present disclosure, the dissolution of lithium fluoride can be promoted to improve the recovery rate of lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic process diagram showing the processing steps in the waste lithium-ion battery processing system according to one embodiment of the present invention.

[0017] Figure 2 is to proceed Figure 1 The schematic structure diagram of the thermal decomposition system of the thermal decomposition process is shown.

[0018] Figure 3 is to proceed Figure 1 The schematic structure diagram of the recovery system of the recovery process shown is shown. DETAILED DESCRIPTION

[0019] Hereinafter, one embodiment will be described with reference to the drawings. Figure 1 This is a schematic process diagram showing the processing steps in a waste lithium-ion battery processing system according to one embodiment of the present disclosure. It should be noted that, hereinafter, lithium-ion batteries may be abbreviated as LIBs.

[0020] The waste LIBs targeted by the treatment system in this embodiment are, for example, NCM-type lithium-ion batteries whose positive electrode active materials contain nickel, cobalt, and manganese. However, lithium-ion batteries other than NCM-type batteries can also be treated. Lithium-ion batteries use graphite as the negative electrode active material, aluminum foil as the positive electrode current collector, and copper foil as the negative electrode current collector. Furthermore, lithium-ion batteries contain fluorine compounds as electrolytes or binders.

[0021] This processing system targets large waste LIBs, namely, battery modules composed of battery cells assembled from multiple waste LIBs, and battery packs composed of multiple battery modules. A battery pack, for example, houses multiple electrically connected battery modules, a control device, and a cooling device within a housing. This processing system is designed to remove waste LIBs from, for example, electric vehicles and hybrid vehicles and process the removed waste LIBs, namely, battery packs or battery modules, without disassembling them.

[0022] like Figure 1 As shown, the treatment system in this embodiment includes: a thermal decomposition step P1, which thermally decomposes the waste LIB and calcines the obtained powder containing active material; and a recovery step P2, which immerses the calcined active material in water to dissolve lithium and then recover lithium.

[0023] First, the thermal decomposition step P1 will be described. The thermal decomposition step P1 includes a pretreatment step P11, a crushing and sorting step P12, and a calcination step P13. Figure 2 is to proceed Figure 1 The thermal decomposition system 1 includes a supply device 10 , a pre-processing device 11 , a crushing and sorting device 12 , and a calcining device 13 .

[0024] Pretreatment step P11 involves calcining the waste LIBs at a second temperature, lower than the first temperature in calcining step P13, described later, to decompose and remove the electrolyte contained in the waste LIBs. This is known as pre-calcining. To this end, the waste LIBs are supplied from a supply device 10 to the pre-treatment device 11. Supply device 10 is, for example, a belt conveyor. Pre-treatment device 11 is, for example, a grate preheater.

[0025] The second temperature in the pretreatment step P11 is set to a temperature capable of decomposing and removing the electrolyte contained in the waste LIB. For example, the second temperature may be 150°C or higher and lower than 400°C, or 150°C or higher and lower than 250°C.

[0026] The crushing and sorting step P12 crushes the waste LIBs processed in the pretreatment step P11, separating the active material from the current collectors in the crushed waste LIBs and sorting the active material. To this end, the crushing and sorting device 12 includes a crusher 12a and a sorter 12b. The crusher 12a is, for example, a roller crusher. The crusher 12a crushes large waste LIBs (battery packs or battery modules) into sizes similar to or smaller than battery cells.

[0027] The sorter 12b is configured to separate the active material from the current collector in the waste LIBs crushed by the crusher 12a, sorting the active material. The sorter 12b is comprised of, for example, a sieve vibrator. In practice, the sorter 12b not only removes the positive electrode active material but also removes a small amount of impurities other than the active material, such as the negative electrode active material, and supplies them to the calcining device 13. The remaining waste LIB packaging, current collector, and other materials are transported to other processing facilities.

[0028] The calcination step P13 calcines the waste LIBs sorted in the crushing and sorting step P12 at a predetermined first temperature. It should be noted that the mixed waste LIBs are a mixture of active materials from the waste LIBs and alkali metal salts. The calcination apparatus 13 is, for example, an externally heated rotary kiln. The externally heated rotary kiln comprises a cylindrical body 13a that rotates about a central axis and a heating jacket 13b that surrounds the outer circumference of the cylindrical body 13a.

[0029] The cylindrical body 13a has one end serving as a receiving port 13c and the other end serving as a discharge port 13d. The cylindrical body 13a is tilted downward from the receiving port 13c toward the discharge port 13d, with the central axis tilted at a predetermined angle. The cylindrical body 13a is supported so that it can rotate about the central axis in this manner. Waste LIBs supplied from the sorting machine 12b to the receiving port 13c of the cylindrical body 13a are transported toward the discharge port 13d as the cylindrical body 13a rotates.

[0030] The interior of cylinder 13a is filled with air. Alternatively, cylinder 13a may be filled with a reducing atmosphere or a low-oxygen atmosphere, for example, with an oxygen concentration of 10% or less. Heating gas is supplied to a heating jacket 13b surrounding the outer periphery of cylinder 13a, heating the outer wall of cylinder 13a. The waste LIBs conveyed within cylinder 13a are heated and discharged as calcined waste from outlet 13d. The calcination temperature in calcination step P13, or the first temperature, is 400°C or higher, for example, 800°C.

[0031] Next, the recovery step P2 will be described. Figure 3 is to proceed Figure 1 The schematic diagram of the recovery system for the recovery process shown in FIG. Recovery process P2 includes a first dissolution process P21, a first separation process P22, and a lithium recovery process P24. Accordingly, recovery system 2 includes a first dissolution tank 21, a first separator 22, and a lithium recovery device 24.

[0032] The first dissolution step P21 immerses the calcined material in water. To this end, water is stored in a first dissolution tank 21, into which the calcined material is introduced. The calcined material is supplied to the first dissolution tank 21 via a hopper 20 in predetermined amounts. As a result, the aqueous solution in the first dissolution tank 21 becomes a mixture of water and the calcined material. The first dissolution tank 21 is equipped with a stirring mechanism for stirring the aqueous solution therein.

[0033] Most of the lithium components contained in the calcined product are lithium carbonate (Li 2 CO 3 ) generated in the calcination step P13 . The lithium carbonate is dissolved in the water in the first dissolution tank 21 .

[0034] The first separation step P22 performs a first solid-liquid separation on the aqueous solution treated in the first dissolution step P21. To this end, the first separator 22 comprises a solid-liquid separator. Solid-liquid separation by the first separator 22 removes solid residues from the aqueous solution. The lithium recovery step P24 recovers lithium from the aqueous solution separated by the first solid-liquid separation.

[0035] More specifically, the lithium recovery step P24 concentrates the aqueous solution separated in the first separation step P22. To this end, the lithium recovery device 24 may include a concentrator. The concentrator may be, for example, an evaporation concentration device or a crystallization device that heats the aqueous solution to 80°C or above to evaporate the water in the aqueous solution. By concentrating the aqueous solution, the concentration of lithium contained in the aqueous solution increases, generating a slurry containing lithium carbonate.

[0036] Furthermore, the lithium recovery step P24 performs solid-liquid separation on the generated slurry. To this end, the lithium recovery device 24 may be equipped with a solid-liquid separator. In the lithium recovery step P24, solid-liquid separation is performed to separate lithium carbonate from the slurry. Thus, the lithium is recovered as lithium carbonate. The remaining aqueous solution is then processed for waste liquid treatment. It should be noted that the remaining aqueous solution may also be returned to the first dissolution tank 21 or the buffer tank 23 described below.

[0037] The calcined product introduced into the first dissolution tank 21 contains lithium fluoride. As mentioned above, because the spent LIB contains fluorine, this fluorine combines with lithium during calcination to form lithium fluoride (LiF). The lithium fluoride does not dissolve in water in the first dissolution tank 21 and is contained in the residue.

[0038] In this embodiment, the recovery process P2 includes a second dissolution process P25, a second separation process P26, and a calcium separation process P27. Accordingly, the recovery system 2 includes a second dissolution tank 25, a second separator 26, and a calcium separation device 27.

[0039] In the second dissolution step P25, the immersion residue in the first dissolution tank 21 is introduced into a second dissolution tank 25, which is different from the first dissolution tank 21, and immersed in water. To this end, new water is stored in the second dissolution tank 25, and the residue is introduced. The residue is supplied to the second dissolution tank 25 via a hopper 30 in a predetermined amount at a time. Calcium hydroxide (Ca(OH)2) is then added to the water in the second dissolution tank 25. As a result, the aqueous solution in the second dissolution tank 25 becomes a mixture of new water, the residue, and calcium hydroxide. The second dissolution tank 25 is equipped with a stirring mechanism for stirring the aqueous solution in the second dissolution tank 25.

[0040] In the second dissolution tank 25 into which water, residue, and calcium hydroxide are introduced, the following three reactions occur.

[0041] Ca(OH)2→Ca 2+ +2OH-...(1)

[0042] LiF→Li + +F-...(2)

[0043] Ca 2+ +2F-→CaF2...(3)

[0044] That is, when calcium hydroxide is added to the water in the second dissolution tank 25, as shown in reaction formula (1), the calcium hydroxide dissolves in the water to generate calcium ions and hydroxide ions. When the lithium fluoride contained in the residue in the second dissolution tank 25 dissolves in the water, as shown in reaction formula (2), lithium ions and fluoride ions are generated. At this time, as shown in reaction formula (3), the calcium ions combine with the fluoride ions to generate calcium fluoride (CaF2). The generation of calcium fluoride reduces the fluoride ion concentration in the aqueous solution, thereby promoting the ionization, i.e., the dissolution, of lithium fluoride. As a result of promoting the dissolution of lithium fluoride, the lithium ions in the aqueous solution increase.

[0045] It should be noted that the immersion residue in the first dissolution tank 21 may contain some lithium carbonate that was not dissolved in the first dissolution step P21. The lithium carbonate contained in the residue is dissolved in the second dissolution tank 25. However, even in this case, since the amount of lithium carbonate introduced into the second dissolution tank 25 is less than the amount of lithium carbonate introduced into the first dissolution tank 21, and the solid-liquid ratio of the second dissolution tank 25 is greater than that of the first dissolution tank 21, the lithium concentration becomes dilute. Therefore, it is believed that the influence of the second dissolution tank 25 on the dissolution of lithium fluoride is sufficiently small.

[0046] The solubility of lithium fluoride is lower than that of lithium carbonate. Therefore, the weight ratio of water in the second dissolution tank 25 to the residue is set to be greater than the weight ratio of water in the first dissolution tank 21 to the calcined product. For example, the amount of water in the second dissolution tank 25 is set to be 20 times or more and 40 times or less of the weight ratio of the residue introduced into the second dissolution tank 25.

[0047] When the weight ratio is less than 20 times, the lithium concentration is not dilute enough, so the lithium fluoride may not be fully dissolved. On the other hand, if the weight ratio exceeds 40 times, the second dissolving tank 25 becomes too large, the water consumption also increases, and the cost increases. In contrast, by setting the amount of water in the second dissolving tank 25 to a weight ratio of more than 20 times and less than 40 times relative to the weight of the residue introduced into the second dissolving tank 25, the lithium fluoride contained in the residue in the second dissolving tank can be fully dissolved, and the increase in cost can be suppressed. It should be noted that the weight ratio is more preferably more than 25 times or less than 35 times. The weight ratio is further preferably about 28 times.

[0048] Second separation step P26 performs a second solid-liquid separation on the aqueous solution treated in second dissolution step P25. To this end, second separator 26 comprises a solid-liquid separator. Solid-liquid separation by second separator 26 removes solid residues containing calcium fluoride and other impurities from the aqueous solution. Calcium separation step P27 separates excess calcium and lithium from calcium hydroxide from the aqueous solution separated by the second solid-liquid separation.

[0049] Calcium separation process P27 comprises precipitation process P28 and the 3rd separation process P29.Correspondingly, calcium separation device 27 possesses precipitation tank 28 and the 3rd separator 29.Precipitation process P28 utilizes carbon dioxide to bubble the aqueous solution separated by the second solid-liquid separation.For this reason, precipitation tank 28 is configured to import carbon dioxide.By the bubbling of utilizing carbon dioxide to the aqueous solution in precipitation tank 28, the residual calcium from calcium hydroxide imported in the second dissolving process P25 is separated as solid calcium carbonate (CaCO 3 ).Therefore, lithium and calcium contained in the aqueous solution separated by the second solid-liquid separation can be easily separated.Thus, the purity of the lithium carbonate that can suppress recovery is reduced because of the calcium added.

[0050] In the present embodiment, the bubbling of carbon dioxide is utilized to carry out in a manner that the pH value of the aqueous solution separated by the second solid-liquid separation is more than 8 and is within the scope of less than 10. When the pH value of the aqueous solution after bubbling is less than 8, the calcium carbonate of precipitation is likely to be used as calcium bicarbonate (Ca (HCO 3 ) 2) redissolved, and it is likely that calcium cannot be separated from lithium. In addition, the pH value of the aqueous solution before bubbling is about 12, so under the state that the pH value of the aqueous solution after bubbling is greater than 10, residual calcium cannot be fully precipitated. In contrast, the bubbling of carbon dioxide is utilized to carry out in a manner that the pH value of the aqueous solution separated by the second solid-liquid separation is more than 8 and is within the scope of less than 10, so that the calcium in the aqueous solution can be suitably separated from lithium. It should be noted that the pH value of the aqueous solution after bubbling is more preferably set at 8.5.

[0051] The third separation step P29 performs a third solid-liquid separation on the foamed aqueous solution. To this end, the third separator 29 comprises a solid-liquid separator. By performing the solid-liquid separation in the third separator 29, solid residues such as calcium carbonate are removed from the aqueous solution. The aqueous solution separated by the third solid-liquid separation is introduced into the lithium recovery device 24.

[0052] In this embodiment, the recovery step P2 includes a storage step P23 for temporarily storing the aqueous solution separated by the first solid-liquid separation and the aqueous solution separated by the third solid-liquid separation. To this end, the recovery system 2 includes a buffer tank 23 for receiving the aqueous solution flowing out of the first separator 22 and the aqueous solution flowing out of the third separator 29. Thus, lithium is also recovered from the aqueous solution separated by the third solid-liquid separation in the lithium recovery step P24.

[0053] As described above, according to this embodiment, the calcined product obtained by calcining spent lithium-ion batteries is immersed in water in the first dissolution tank 21. The residue is then immersed in water again in the second dissolution tank 25, which is different from the first dissolution tank 21. At this time, calcium hydroxide is added to the second dissolution tank 25. This promotes the dissolution of lithium fluoride contained in the residue, allowing the lithium component contained in the residue to be recovered. Consequently, the lithium recovery rate can be improved.

[0054] Here, the reason why calcium hydroxide is not added to the first dissolution tank 21 is explained. As described above, the calcined waste LIB is introduced into the first dissolution tank 21. The calcined waste contains at least lithium carbonate and lithium fluoride as lithium compounds. The solubility of lithium carbonate in water is greater than the solubility of lithium fluoride in water. Therefore, the dissolution of lithium carbonate in the first dissolution tank 21 is dominant, and the dissolution of lithium fluoride hardly occurs. Furthermore, the amount of lithium carbonate in the calcined waste is greater than the amount of lithium fluoride, which can also be one of the reasons why the dissolution of lithium fluoride is difficult to occur.

[0055] Therefore, it is believed that even if calcium hydroxide is added to the aqueous solution in the first dissolution tank 21, the lithium carbonate will dissolve, leading to saturation of lithium ions and dissolution of lithium fluoride. The inventors, having obtained this understanding, came up with the idea of ​​immersing the residue containing lithium fluoride in fresh water, i.e., water not saturated with lithium ions, in a second dissolution tank 25 different from the first dissolution tank 21, in order to dissolve lithium fluoride in water.

[0056] The lithium fluoride that is not dissolved in the first dissolution tank 21 and is separated as a residue can be re-immersed in water in the second dissolution tank 25 to dissolve the lithium fluoride and recover the lithium component contained in the lithium fluoride.

[0057] As will be apparent from the foregoing description, many modifications or alternative embodiments of the present disclosure will be readily apparent to those skilled in the art. Therefore, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best way to implement the present disclosure. The details of its structure and functionality may be substantially modified without departing from the spirit of the present disclosure.

[0058] [Other embodiments]

[0059] For example, in the above-described embodiment, a processing system is illustrated in which one or a plurality of devices or equipment correspond to each process. However, the processing system may be configured so that a plurality of processes are realized by a single device or equipment.

[0060] In addition, in the above embodiment, the aqueous solution separated by the calcium separator 27 and the aqueous solution separated by the first separator 22 are mixed and introduced into the lithium recovery device 24. However, these aqueous solutions may be processed separately. For example, the calcium separator 27 may have the same function as the lithium recovery device 24 after the third separation step P29, that is, the function of performing the concentration and solid-liquid separation steps.

[0061] [Summary of the present disclosure]

[0062] [Scheme 1]

[0063] One embodiment of the present disclosure relates to a method for treating waste lithium-ion batteries for recovering lithium from waste lithium-ion batteries containing fluorine, wherein a calcined product obtained by calcining the waste lithium-ion battery is introduced into a first dissolution tank and immersed in water, a first solid-liquid separation is performed on the aqueous solution after immersion in the first dissolution tank, and the lithium is recovered from the aqueous solution separated by the first solid-liquid separation. The immersion residue in the first dissolution tank is introduced into a second dissolution tank different from the first dissolution tank and immersed in water, calcium hydroxide is added to the water in the second dissolution tank, a second solid-liquid separation is performed on the aqueous solution after immersion in the second dissolution tank, and residual calcium from the calcium hydroxide and the lithium are separated from the aqueous solution separated by the second solid-liquid separation.

[0064] According to the above method, the calcined product obtained by calcining the waste lithium-ion battery is immersed in water in a first dissolution tank, and then the residue is immersed in water again in a second dissolution tank different from the first dissolution tank. In this case, calcium hydroxide is added to the second dissolution tank. This promotes the dissolution of the lithium fluoride contained in the residue, and the lithium content contained in the residue can be recovered. Therefore, the recovery rate of lithium can be improved.

[0065] [Scheme 2]

[0066] In the method for treating waste lithium-ion batteries of Option 1, the amount of water in the second dissolution tank may be 20 to 40 times the weight of the residue introduced into the second dissolution tank. This allows the lithium fluoride contained in the residue to be fully dissolved in the second dissolution tank while suppressing cost increases.

[0067] [Scheme 3]

[0068] In the method for treating waste lithium-ion batteries of Scheme 1 or 2, the aqueous solution separated by the second solid-liquid separation can be bubbled with carbon dioxide, and the bubbled aqueous solution is subjected to a third solid-liquid separation to remove the remaining calcium as a solid. By implementing the bubbling with carbon dioxide, the remaining calcium from the calcium hydroxide added in the second dissolving tank can be precipitated. Therefore, the lithium and calcium contained in the aqueous solution separated by the second solid-liquid separation can be easily separated. Thus, the purity of the recovered lithium carbonate can be suppressed from being reduced by the added calcium.

[0069] [Scheme 4]

[0070] In the method for treating waste lithium-ion batteries of Option 3, the bubbling of carbon dioxide can be performed so that the pH of the aqueous solution separated by the second solid-liquid separation is within a range of 8 to 10. This allows for appropriate separation of calcium and lithium in the aqueous solution.

[0071] [Scheme 5]

[0072] Another embodiment of a waste lithium-ion battery processing system disclosed herein is a waste lithium-ion battery processing system for recovering lithium from waste lithium-ion batteries containing fluorine, comprising: a first dissolution tank for introducing a roasted product obtained by roasting the waste lithium-ion battery and immersing the product in water; a first separator for performing a first solid-liquid separation on the aqueous solution after immersion in the first dissolution tank; a lithium recovery device for recovering the lithium from the aqueous solution separated by the first separator; a second dissolution tank for introducing the residue after immersion in the first dissolution tank into water to which calcium hydroxide has been added and immersing the residue, the second dissolution tank being different from the first dissolution tank; a second separator for performing a second solid-liquid separation on the aqueous solution after immersion in the second dissolution tank; and a calcium separation device for separating the remaining calcium from the calcium hydroxide and the lithium from the aqueous solution separated by the second solid-liquid separation; and calcium hydroxide is added to the water in the second dissolution tank.

[0073] Explanation of symbols

[0074] 2 Recovery system (treatment system)

[0075] 21First dissolution tank

[0076] 22First separator

[0077] 24 lithium recovery device

[0078] 25 Second dissolution tank

[0079] 26 Second separator

[0080] 27 Calcium separation device

Claims

1. A method for treating waste lithium-ion batteries, for recovering lithium from waste lithium-ion batteries containing fluorine, wherein: The calcined product obtained by calcining the waste lithium ion battery is introduced into a first dissolution tank and immersed in water. performing a first solid-liquid separation on the aqueous solution after immersion in the first dissolving tank, recovering the lithium from the aqueous solution separated by the first solid-liquid separation, The residue after immersion in the first dissolution tank is introduced into a second dissolution tank different from the first dissolution tank and immersed in water. Add calcium hydroxide to the water in the second dissolution tank, The second solid-liquid separation is performed on the aqueous solution after immersion in the second dissolution tank, The remaining calcium from the calcium hydroxide and the lithium are separated from the aqueous solution separated by the second solid-liquid separation.

2. The method for treating waste lithium-ion batteries according to claim 1, wherein: The amount of water in the second dissolution tank is 20 times or more and 40 times or less of the weight of the residue introduced into the second dissolution tank.

3. The method for treating waste lithium-ion batteries according to claim 1 or 2, wherein: The aqueous solution separated by the second solid-liquid separation is bubbled with carbon dioxide, and the bubbled aqueous solution is subjected to a third solid-liquid separation to remove the excess calcium as a solid.

4. The method for treating waste lithium-ion batteries according to claim 3, wherein: The bubbling of carbon dioxide is performed so that the pH of the aqueous solution separated by the second solid-liquid separation is within a range of 8 to 10.

5. A waste lithium-ion battery processing system for recovering lithium from waste lithium-ion batteries containing fluorine, the waste lithium-ion battery processing system comprising: A first dissolution tank is provided for introducing a roasted product obtained by roasting the waste lithium-ion battery and immersing the product in water; a first separator for performing a first solid-liquid separation on the aqueous solution after immersion in the first dissolving tank; a lithium recovery device for recovering the lithium from the aqueous solution separated by the first separator; a second dissolution tank, wherein the immersion residue in the first dissolution tank is introduced into water to which calcium hydroxide is added and immersed, and the second dissolution tank is different from the first dissolution tank; a second separator for performing a second solid-liquid separation on the aqueous solution after immersion in the second dissolving tank; and A calcium separation device separates the remaining calcium from the calcium hydroxide and the lithium from the aqueous solution separated by the second solid-liquid separation.

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