Treatment system of waste lithium ion battery

Abstract

A waste lithium ion battery treatment system for recovering lithium from a fluorine-containing waste lithium ion battery, the waste lithium ion battery treatment system comprising: a first dissolving tank into which a roasted product obtained by roasting the waste lithium ion battery is introduced and immersed in water; a first separator for performing first solid-liquid separation on the immersed aqueous solution in the first dissolving tank; a lithium recovery device for recovering the lithium from the aqueous solution separated by the first separator; a second dissolving tank, which is different from the first dissolving tank, and which introduces and immerses the immersed residue in the first dissolving tank into water to which calcium hydroxide has been added; a second separator for performing second solid-liquid separation on the immersed aqueous solution in the second dissolving 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.

Description

Technical Field

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

[0002] In order to recover the lithium contained in the lithium ion battery, the waste lithium ion battery is calcined, and the calcined product is immersed in water to dissolve the lithium ions in the water, thereby separating the lithium from the impurities.

[0003] However, in lithium-ion batteries, electrolytes, adhesives, etc. contain a large amount of fluorine, and when waste lithium-ion batteries are roasted, lithium ions may combine with fluorine 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 in order to separate lithium from a lithium solution containing fluorine and lithium.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2021 / 090571 Utility Model Content

[0008] Issues to be Solved by Utility Models

[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 has been made in view of the above-mentioned problems, and its object is to provide a waste lithium-ion battery processing system that can promote the dissolution of lithium fluoride and improve the recovery rate of lithium.

[0011] Means for solving problems

[0012] A waste lithium-ion battery processing system according to one embodiment of the present invention is a waste lithium-ion battery processing system for recovering lithium from waste lithium-ion batteries containing fluorine, and comprises: a first dissolution tank, into which a roasted product obtained by roasting the waste lithium-ion battery is introduced and immersed in water; a first separator, which performs a first solid-liquid separation on the aqueous solution after immersion in the first dissolution tank; a lithium recovery device, which recovers the lithium from the aqueous solution separated by the first separator; a second dissolution tank, into which the residue after immersion in the first dissolution tank is introduced and immersed in water to which calcium hydroxide is added, and the second dissolution tank is different from the first dissolution tank; a second separator, which performs a second solid-liquid separation on the aqueous solution after immersion in the second dissolution tank; and a calcium separation device, which separates the remaining calcium from the calcium hydroxide and the lithium from the aqueous solution separated by the second solid-liquid separation.

[0013] Effect of utility model

[0014] 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

[0015] Figure 1 This is a schematic process diagram showing a treatment process in a waste lithium-ion battery treatment system according to one embodiment of the present invention.

[0016] Figure 2 Yes Figure 1 The schematic structure diagram of the thermal decomposition system of the thermal decomposition step is shown.

[0017] Figure 3 Yes Figure 1 A schematic diagram of the recovery system of the recovery process shown. DETAILED DESCRIPTION

[0018] Hereinafter, one embodiment will be described with reference to the drawings. Figure 1 1 is a schematic process diagram showing a treatment process in a waste lithium ion battery treatment system according to an embodiment of the present disclosure. It should be noted that, hereinafter, lithium ion batteries may be abbreviated as LIBs.

[0019] The waste LIB to be treated by the treatment system in this embodiment is, for example, an NCM type lithium ion battery containing nickel, cobalt, and manganese in the positive electrode active material. However, lithium ion batteries other than the NCM type may also be treated. A lithium ion battery is a battery containing graphite as a negative electrode active material, using aluminum foil as a positive electrode current collector, and using copper foil as a negative electrode current collector. In addition, the lithium ion battery contains a fluorine compound as an electrolyte or a binder.

[0020] This processing system targets large waste LIBs, that is, battery modules composed of battery cells of a plurality of waste LIBs, and battery packs composed of a plurality of battery modules. The battery pack is configured to house a plurality of electrically connected battery modules, a control device, and a cooling device in a housing. It is assumed that this processing system removes waste LIBs mounted on electric vehicles and hybrid vehicles, and processes the removed waste LIBs, that is, battery packs or battery modules, without disassembling them.

[0021] like Figure 1 As shown, the treatment system in this embodiment includes: a thermal decomposition step P1, thermally decomposing waste LIB and calcining the obtained powder containing active materials; and a recovery step P2, immersing the calcined active materials in water to dissolve lithium and then recovering lithium.

[0022] First, the thermal decomposition step P1 is described. The thermal decomposition step P1 includes a pre-treatment step P11, a crushing and sorting step P12, and a calcining step P13. Figure 2 Yes Figure 1 The schematic configuration diagram of the thermal decomposition system of the thermal decomposition process shown in FIG. The thermal decomposition system 1 includes a supply device 10 , a pre-treatment device 11 , a crushing and sorting device 12 , and a roasting device 13 .

[0023] The pretreatment step P11 is to calcine the waste LIB at a second temperature lower than the first temperature in the calcination step P13 described later, in order to decompose and remove the electrolyte contained in the waste LIB. For this purpose, the waste LIB is supplied from the supply device 10 to the pretreatment device 11. The supply device 10 is composed of, for example, a belt conveyor, etc. The pretreatment device 11 is composed of, for example, a grate preheater.

[0024] The second temperature in the pretreatment step P11 is set to a temperature at which the electrolyte contained in the waste LIB can be decomposed and removed. For example, the second temperature may be 150°C or higher and lower than 400°C, or 150°C or higher and 250°C or lower.

[0025] The crushing and sorting step P12 crushes the waste LIB treated in the pre-treatment step P11, separates the active material from the current collector of the crushed waste LIB, and sorts the active material. To this end, the crushing and sorting device 12 includes a crusher 12a and a sorter 12b. The crusher 12a is composed of, for example, a roller crusher. The crusher 12a crushes large waste LIBs (battery packs or battery modules) into a size of a battery cell or smaller.

[0026] The sorting machine 12b is configured to separate the active material from the current collector for the waste LIB crushed by the crusher 12a, and to sort out the active material. The sorting machine 12b is composed of, for example, a sieve vibrator. In fact, not only the positive electrode active material is taken out by the sorting machine 12b, but also a small amount of impurities other than the active material such as the negative electrode active material are taken out and supplied to the roasting device 13. The outer packaging materials, current collectors, etc. of the waste LIBs other than these are transported to other processing equipment.

[0027] The roasting step P13 roasts the waste LIB sorted in the crushing and sorting step P12 at a predetermined first temperature. It should be noted that the mixed waste LIB is a mixture of active materials and alkali metal salts of the waste LIB. The roasting device 13 is composed of, for example, an externally heated rotary kiln. The externally heated rotary kiln includes a cylindrical body 13a rotating around a central axis and a heating jacket 13b provided so as to surround the outer circumference of the cylindrical body 13a.

[0028] The cylindrical body 13a has one end as a receiving port 13c and the other end as a discharge port 13d, and is tilted downward from the receiving port 13c to the discharge port 13d so that the central axis has a predetermined angle of inclination and is supported to be rotatable around the central axis in this state. The waste LIB supplied from the sorting machine 12b to the receiving port 13c of the cylindrical body 13a is transported toward the discharge port 13d by the rotation of the cylindrical body 13a.

[0029] The interior of the cylinder 13a is an air atmosphere. It should be noted that, as an alternative, the interior of the cylinder 13a may also be a reducing atmosphere or a low-oxygen atmosphere, for example, with an oxygen concentration of 10% or less. By supplying heating gas to the heating jacket 13b surrounding the outer periphery of the cylinder 13a, the outer wall of the cylinder 13a is heated, and the waste LIB transported inside the cylinder 13a is heated and discharged from the discharge port 13d as a roasted product. The roasting temperature in the roasting step P13, i.e., the first temperature, is 400°C or more, for example, 800°C.

[0030] Next, the recovery step P2 will be described. Figure 3 Yes Figure 1 The schematic structure diagram of the recovery system of the recovery process shown in FIG. The recovery process P2 includes a first dissolution process P21, a first separation process P22 and a lithium recovery process P24. Correspondingly, the recovery system 2 includes a first dissolution tank 21, a first separator 22 and a lithium recovery device 24.

[0031] The first dissolution step P21 immerses the roasted product in water. For this purpose, water is stored in the first dissolution tank 21 and the roasted product is introduced. The roasted product is supplied to the first dissolution tank 21 via the hopper 20 in a predetermined amount each time. As a result, the aqueous solution in the first dissolution tank 21 becomes a mixture of water and the roasted product. The first dissolution tank 21 is provided with a stirring mechanism for stirring the aqueous solution in the first dissolution tank 21.

[0032] Most of the lithium components contained in the calcined product are lithium carbonate (Li 2 CO 3 ). Lithium carbonate is dissolved in the water in the first dissolution tank 21.

[0033] The first separation step P22 performs a first solid-liquid separation on the aqueous solution treated in the first dissolution step P21. For this purpose, the first separator 22 is composed of a solid-liquid separator. By performing solid-liquid separation using the first separator 22, solid residues are removed from the aqueous solution. The lithium recovery step P24 recovers lithium from the aqueous solution separated by the first solid-liquid separation.

[0034] 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 is composed of, for example, an evaporation concentration device or a crystallization device that heats the aqueous solution to 80° C. or higher and evaporates 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.

[0035] 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, lithium carbonate is precipitated from the slurry by performing solid-liquid separation. Thus, lithium is recovered as lithium carbonate. The remaining aqueous solution is subjected to 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 later.

[0036] Here, the calcined product introduced into the first dissolution tank 21 contains lithium fluoride. As described above, since the waste LIB contains fluorine, the fluorine combines with lithium during calcination to generate lithium fluoride (LiF). Lithium fluoride does not dissolve in water in the first dissolution tank 21 but is contained in the residue.

[0037] In this embodiment, the recovery step P2 includes a second dissolution step P25 , a second separation step P26 , and a calcium separation step P27 . Accordingly, the recovery system 2 includes a second dissolution tank 25 , a second separator 26 , and a calcium separation device 27 .

[0038] In the second dissolution step P25, the residue after immersion in the first dissolution tank 21 is introduced into a second dissolution tank 25 different from the first dissolution tank 21 and immersed in water. For this purpose, 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 in a predetermined amount each time through the hopper 30. Calcium hydroxide (Ca(OH) 2). Thus, the aqueous solution in the second dissolution tank 25 becomes a mixture of new water, residue and calcium hydroxide. The second dissolution tank 25 is provided with a stirring mechanism for stirring the aqueous solution in the second dissolution tank 25.

[0039] In the second dissolution tank 25 into which water, residue and calcium hydroxide are introduced, the following three reactions occur.

[0040] Ca(OH) 2 →Ca 2+ +2OH - ...(1)

[0041] LiF→Li + +F - ...(2)

[0042] Ca 2+ +2F - →CaF 2 ...(3)

[0043] That is, when calcium hydroxide is added to the water in the second dissolving tank 25, as shown in reaction formula (1), calcium hydroxide dissolves in water to generate calcium ions and hydroxide ions. When lithium fluoride contained in the residue in the second dissolving tank 25 dissolves in water, as shown in reaction formula (2), lithium ions and fluoride ions are generated. At this time, as shown in reaction formula (3), calcium ions combine with fluoride ions to generate calcium fluoride (CaF 2 ). By generating calcium fluoride, the concentration of fluoride ions in the aqueous solution is reduced, which promotes 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.

[0044] It should be noted that the residue after immersion in the first dissolution tank 21 may contain some lithium carbonate that is 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, and it is considered that the influence of the second dissolution tank 25 on the dissolution of lithium fluoride is sufficiently small.

[0045] The solubility of lithium fluoride is lower than that of lithium carbonate. Therefore, the weight ratio of water in the second dissolving tank 25 to the residue is set to be greater than the weight ratio of water in the first dissolving tank 21 to the roasted product. For example, the amount of water in the second dissolving tank 25 is set to be 20 times or more and 40 times or less relative to the weight ratio of the residue introduced into the second dissolving tank 25.

[0046] When the weight ratio is less than 20 times, the lithium concentration is not thin 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, and the water consumption also increases, so 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 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.

[0047] The second separation step P26 performs a second solid-liquid separation on the aqueous solution treated in the second dissolution step P25. To this end, the second separator 26 is composed of a solid-liquid separator. By performing solid-liquid separation using the second separator 26, solid residues containing calcium fluoride and other impurities are removed from the aqueous solution. The calcium separation step P27 separates the remaining calcium and lithium from the calcium hydroxide from the aqueous solution separated by the second solid-liquid separation.

[0048] The calcium separation step P27 includes a precipitation step P28 and a third separation step P29. Correspondingly, the calcium separation device 27 includes a precipitation tank 28 and a third separator 29. The precipitation step P28 uses carbon dioxide to bubble the aqueous solution separated by the second solid-liquid separation. For this purpose, the precipitation tank 28 is configured to be able to introduce carbon dioxide. By bubbling the aqueous solution in the precipitation tank 28 with carbon dioxide, the remaining calcium from the calcium hydroxide introduced in the second dissolution step P25 is converted into solid calcium carbonate (CaCO 3 ) precipitation. 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 due to the added calcium.

[0049] In the present embodiment, the bubbling of carbon dioxide is performed in such a manner that the pH of the aqueous solution separated by the second solid-liquid separation is within a range of 8 to 10. When the pH of the aqueous solution after bubbling is less than 8, the precipitated calcium carbonate may be present as calcium bicarbonate (Ca(HCO 3 ) 2 ) is dissolved again, and it is possible that calcium cannot be separated from lithium. In addition, the pH of the aqueous solution before bubbling is about 12, so when the pH of the aqueous solution after bubbling is greater than 10, the remaining calcium cannot be fully precipitated. In contrast, the bubbling of carbon dioxide is carried out in a manner such that the pH of the aqueous solution separated by the second solid-liquid separation is within the range of more than 8 and less than 10, thereby enabling calcium and lithium in the aqueous solution to be properly separated. It should be noted that the pH of the aqueous solution after bubbling is more preferably set to 8.5.

[0050] The third separation step P29 performs a third solid-liquid separation on the aqueous solution after bubbling. For this purpose, the third separator 29 is composed of a solid-liquid separator. By using the third separator 29 to perform solid-liquid separation, 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.

[0051] In the present 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 introducing the aqueous solution flowing out of the first separator 22 and the aqueous solution flowing out of the third separator 29. Thus, lithium in the aqueous solution separated by the third solid-liquid separation is also recovered in the lithium recovery step P24.

[0052] As described above, according to the present embodiment, the residue after the roasted product obtained by roasting the waste lithium ion battery is immersed in water in the first dissolving tank 21 is immersed in water again in the second dissolving tank 25 different from the first dissolving tank 21. At this time, calcium hydroxide is added to the second dissolving tank 25. Therefore, the dissolution of lithium fluoride contained in the residue is promoted, and the lithium component contained in the residue can be recovered. Therefore, the recovery rate of lithium can be improved.

[0053] Here, the reason why calcium hydroxide is not added to the first dissolution tank 21 is explained. As described above, the calcined product of waste LIB is introduced into the first dissolution tank 21. The calcined product 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 is dominant in the first dissolution tank 21, and the dissolution of lithium fluoride hardly occurs. Furthermore, the amount of lithium carbonate in the calcined product 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.

[0054] Therefore, it is considered that even if calcium hydroxide is added to the aqueous solution in the first dissolution tank 21, the lithium ions are saturated due to the dissolution of lithium carbonate, and the dissolution of lithium fluoride does not proceed. The inventors have obtained such a view and thought of immersing the residue containing lithium fluoride in new water, that is, water that is 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.

[0055] 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.

[0056] As can be seen from the above description, many improvements or other embodiments of the present disclosure are obvious to those skilled in the art. Therefore, the above description should only be interpreted as an example, and is provided for the purpose of teaching the best mode for performing the present disclosure to those skilled in the art. The details of its structure or function can be substantially changed without departing from the spirit of the present disclosure.

[0057] [Other embodiments]

[0058] For example, in the above-mentioned embodiments, a processing system in which one or a plurality of devices or equipments correspond to each process is exemplified, but the processing system may be configured so that a plurality of processes are realized by one device or equipment.

[0059] In addition, in the above embodiment, the aqueous solution separated by the calcium separation device 27 and the aqueous solution separated by the first separator 22 are mixed and introduced into the lithium recovery device 24, but these aqueous solutions may be processed separately. For example, the calcium separation device 27 may also have the same function as the lithium recovery device 24 after the third separation step P29, that is, the function of implementing the concentration and solid-liquid separation step.

[0060] [Summary of the present disclosure]

[0061] [Solution 1]

[0062] A method for treating waste lithium-ion batteries according to one embodiment of the present disclosure is 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 batteries 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, 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 the remaining calcium from the calcium hydroxide and the lithium are separated from the aqueous solution separated by the second solid-liquid separation.

[0063] According to the above method, the residue after the roasted product obtained by roasting the waste lithium ion battery is immersed in water in the first dissolving tank is immersed in water again in the second dissolving tank different from the first dissolving tank. At this time, calcium hydroxide is added in the second dissolving tank. Therefore, the dissolution of lithium fluoride contained in the residue is promoted, and the lithium component contained in the residue can be recovered. Therefore, the recovery rate of lithium can be improved.

[0064] [Solution 2]

[0065] In the method for treating waste lithium-ion batteries of Scheme 1, the amount of water in the second dissolving tank may be 20 times or more and 40 times or less of the weight of the residue introduced into the second dissolving tank. Thus, the lithium fluoride contained in the residue can be fully dissolved in the second dissolving tank, and the increase in cost can be suppressed.

[0066] [Solution 3]

[0067] In the treatment method of 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 aqueous solution after the bubble is subjected to a third solid-liquid separation, and the above-mentioned residual calcium is removed as a solid. By implementing the bubbling of carbon dioxide, the residual 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 due to the added calcium.

[0068] [Solution 4]

[0069] In the method for treating waste lithium-ion batteries of Scheme 3, the bubbling of carbon dioxide may 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 calcium and lithium in the aqueous solution to be appropriately separated.

[0070] [Solution 5]

[0071] Another embodiment of the 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, and comprises: a first dissolution tank, into which a roasted product obtained by roasting the waste lithium ion battery is introduced and immersed in water; a first separator, which performs a first solid-liquid separation on the aqueous solution after immersion in the first dissolution tank; a lithium recovery device, which recovers the lithium from the aqueous solution separated by the first separator; a second dissolution tank, into which the residue after immersion in the first dissolution tank is introduced and immersed in water to which calcium hydroxide is added, and the second dissolution tank is different from the first dissolution tank; a second separator, which performs a second solid-liquid separation on the aqueous solution after immersion in the second dissolution tank; and a calcium separation device, which separates 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.

[0072] Explanation of symbols

[0073] 2 Recovery system (treatment system)

[0074] 21First dissolution tank

[0075] 22First Separator

[0076] 24Lithium recovery device

[0077] 25 Second dissolution tank

[0078] 26 Second separator

[0079] 27 Calcium separation device.

Claims

1. A waste lithium ion battery processing system for recovering lithium from waste lithium ion batteries containing fluorine, characterized in that: The waste lithium-ion battery processing system has: A first dissolution tank is used to introduce the roasted product obtained by roasting the waste lithium-ion battery and immerse it in water; a first separator for performing a first solid-liquid separation on the impregnated aqueous solution 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, which is different from the first dissolution tank, and is used to immerse the immersion residue in the first dissolution tank in water to which calcium hydroxide has been added; 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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