WO2014042136A1 - Method for recycling lithium-ion batteries and device therefor - Google Patents

Description

Method and apparatus for recycling lithium ion battery

The present invention relates to a method and apparatus for recycling lithium ion batteries, and more particularly, to a method for producing lithium salts, cobalt salts, and the like from waste lithium ion batteries.

Lithium ion batteries are widely used in a wide range of electronic and electrical devices such as mobile phones, notebook computers, digital cameras and video as small and large capacity secondary batteries. The amount of use is said to increase further in the future for hybrid electric vehicles (HEV) and electric vehicles (EV). While the amount of use increases, many waste products are born. Lithium ion batteries include iron-based materials or aluminum as containers, copper as negative electrode current collector materials, carbon as negative electrode active material, aluminum as positive electrode current collector material, lithium compounds as positive electrode active material, etc. Various materials are used, and among them, the positive electrode active material includes rare metals (so-called rare metals) such as lithium, cobalt, and nickel, although there are some contents depending on the battery. There is a growing need for product recycling.

Conventional recycling technology for waste lithium ion batteries includes firing, pulverizing waste lithium ion batteries and dissolving them using strong acids such as nitric acid, sulfuric acid, hydrochloric acid, etc. And then back-extracted into the aqueous phase with acid (exfoliation from the organic solvent phase), and then added with an aqueous alkaline solution or reacted with an aqueous carbonate solution to precipitate hydroxide or carbonate. It was collected as. As such a conventional technique, there is JP 2011-74410 A (Patent Document 1).

In addition, as another conventional technique in this technical field, there is JP-A-2004-11010 (Patent Document 2). In this publication, lithium cobaltate which is a battery positive electrode active material is reduced and roasted together with hydrogen or carbon, thereby changing the compound form of lithium cobaltate and leaching the roasted product with water. Are disclosed in which the lithium content is eluted and the cobalt is distributed into the residue and recovered. Further, there is JP 2011-94227 A (Patent Document 3). This publication describes a technique for selectively recovering lithium by leaching a roasted product obtained by roasting a mixture of carbon and lithium manganate.

JP 2011-74410 A JP 2004-11010 A JP 2011-94227 A

The method according to Patent Document 1 requires a large amount of acid for dissolution and alkali for neutralization, and has a problem that the operation cost is high because the process is complicated. In addition, the product obtained by firing or pulverizing a waste battery may be mixed with iron, which is a battery container material, or aluminum, which is a positive electrode current collector material. . That is, in the solvent extraction method, since aluminum, iron, and the like are extracted with priority over lithium, there is a problem that even if lithium is to be recovered, they are extracted at the same time and high purity cannot be achieved. If iron or aluminum is extracted first in order to avoid such a problem, the number of steps until lithium is extracted increases, resulting in an increase in recovery cost. In addition, in the stage of extracting lithium, there is a problem that it is difficult to increase the purity of the recovered lithium because some of the elements extracted in the previous stage remain. Further, regarding lithium, the relatively high solubility of carbonates and hydroxides also causes the following problems. That is, even if it is attempted to recover lithium as a carbonate or hydroxide precipitate, an amount of lithium corresponding to the solubility is present in the aqueous phase, which is discarded. Therefore, there is a problem that the recovery rate is low in the method in which an alkaline aqueous solution or a carbonate aqueous solution is used.

Moreover, in the method of applying Patent Documents 2 and 3 to the recycling of the waste lithium ion battery, there is a problem that there is no step of removing when a current collector material or a case other than the positive electrode active material is mixed. .

In order to solve these problems, the present invention provides a method for separating and recovering lithium, cobalt, etc. in a high yield, which can be operated at a low cost with a simple process using a minimum of acid and alkali. To do.

In order to solve the above-mentioned problems, the inventors conducted intensive studies. As a result, it has been found that it can be solved by the following means. The present application includes a plurality of means for solving the above-described problems. An example of the means is as follows.

The inventors performed firing, pulverization, and sieving on a waste lithium ion battery at a temperature of 500 ° C. or less and a reduced pressure of 10 Pa or less, and then leaching deionized water or lithium. It has been found that when an acid whose pH is adjusted so that the equilibrium pH of the solution is 8.6 or more is allowed to act, lithium is selectively leached and can be separated from copper, iron, cobalt and the like. This made it possible to recover lithium preferentially over other elements. Furthermore, when an acid was made to act on the said residue which leached lithium, it discovered that cobalt was selectively leached and can be isolate | separated from copper, iron, and aluminum. From these findings, it became clear that dissolution and separation can be performed simultaneously, and the process can be simplified.

In addition, when the inventors want to separate lithium from iron or aluminum that elutes in a trace amount during the leaching of lithium with water, after the leaching of lithium with the water, the solvent is added while adding a complex-forming substance. It has been found that by performing extraction, extraction of iron and aluminum is suppressed, and only lithium is selectively extracted in the oil phase.

Furthermore, the inventors conducted reverse extraction of lithium selectively extracted into the oil phase by solvent extraction into the aqueous phase, for example, using a solution containing a high concentration of lithium compound, and simultaneously crystallizing the lithium compound. It was found that the precipitation generation efficiency of the lithium compound can be remarkably improved by carrying out under the proceeding conditions, and a crystallization peeling apparatus was configured. As a result, the purity and recovery rate of the recovered lithium compound can be dramatically improved.

By the method of the present invention, lithium, cobalt and the like can be separated and recovered from waste lithium ion batteries at a low cost using a minimum amount of chemicals.

It is a figure which shows an example of the recycling process flow of a waste lithium ion battery. It is a figure which shows the selective leaching test result of lithium using pure water. It is a figure which shows the pH dependence of the leaching of the various metal ion by an acid. It is a figure which shows the selective leaching of the cobalt by the acid from the residue after lithium extraction. It is a test result of selective extraction of lithium by solvent extraction. It is a test result of selective extraction of lithium by solvent extraction which changed the extractant. It is a test result which shows the effect of the chelating agent with respect to extraction of lithium. It is a test result which shows the effect of a chelating agent with respect to extraction of aluminum. It is a test result which shows the effect of a chelating agent with respect to extraction of iron. It is a test result which shows the effect of various extractants with respect to extraction of lithium. It is a test result which shows the effect of TBP with respect to extraction of lithium. It is a figure which shows a crystallization peeling apparatus.

Hereinafter, examples will be described with reference to the drawings.

In this example, after roasting the waste lithium ion battery, deionized water (pure water) is allowed to act on the sieving product obtained by crushing and sieving, and lithium is selectively leached and recovered. A method will be described.

After roasting lithium ion battery waste using a lithium transition metal oxide such as lithium cobaltate as the positive electrode active material at a temperature of 500 ° C. and a pressure of 7 Pa (preferably under a reduced pressure of 10 Pa or less) for 1 hour. Then, it is mechanically pulverized and separated by a 35 mesh (420 μm opening) sieve to obtain a recovered material having a particle size of 0.42 mm or less from the lower side of the sieve. The composition of the recovered material varies depending on the battery manufacturer and product. However, when an example is shown by weight percentage, Li: 4.1%, Al: 2.3%, Mn: 0.7%, Fe: 0.2% Co: 36.3%. 1 g of this recovered product is dispersed in 50 mL of deionized water (pure water) at room temperature, stirred for 10 minutes, and then filtered to obtain a filtrate and a residue. From the results of analyzing cations in the filtrate, the leaching rate of each element (the ratio of the weight of the target element ions dissolved in the liquid to the total weight of the target elements contained in the sieving product) was determined. However, all of Co, Cu, Fe, Mn, Al, and Ni were less than 1% except that Li was 89%. In addition, the leaching rate of each element changed as shown in FIG. 2 with respect to the stirring time. From the figure, the leaching rate of Li is constant after the leaching time of 5 minutes or more, and the reaction is completed. On the other hand, when the leaching time is 45 minutes or more, the leaching of Al is 1% or more and cannot be ignored. As described above, the leaching time can be appropriately selected from 5 minutes to 45 minutes.

The leachate thus obtained is applied to the drum surface by spraying it into a heated carbon dioxide atmosphere or by spraying it onto a rotating drum at about 200 ° C. placed in a carbon dioxide atmosphere. The obtained leachate was dried and peeled to obtain lithium carbonate powder.
Further, carbon dioxide was passed through the leachate to obtain a lithium carbonate precipitate.

This example shows an example using solutions of various pH (hydrogen ion index) to which sulfuric acid, nitric acid, or sodium hydrogen sulfite was added instead of deionized water in Example 1. FIG. 3 is a plot of leaching rates of lithium, manganese, aluminum, and cobalt against pH. Here, the pH on the horizontal axis in the figure is the equilibrium pH after leaching. The point where the equilibrium pH is about 11 is when deionized water having a pH of 7 is used, and the equilibrium pH is highest in this example. As is clear from these figures, by using a leachate having an equilibrium pH of 8.6 or more regardless of the type of acid used, the leaching rate of manganese and cobalt can be suppressed to 1% or less. The leaching rate can be suppressed to 8% or less. Further, by using a leaching solution having an equilibrium pH of 10 or more, the leaching rate of any metal ion of manganese, cobalt, and aluminum can be suppressed to 1% or less.

The transition of the lithium leaching rate with respect to the other elements described above is high as shown in FIG. 3 (a), and in the leachate having an equilibrium pH of 8.6 or more, the lithium content is the same as in Example 1. The leach rate is about 89%.

In this example, an example will be described in which cobalt is recovered from the residue after leaching lithium by performing the same process as in Example 1 or 2.

An acid was allowed to act on the residue obtained by filtration after treatment with deionized water as described in Example 1. At this time, the leaching rate and purity of cobalt with respect to the type and addition amount of the acid were as shown in FIG.
(Equation 1) Cobalt leaching rate = (weight of Co ions dissolved in acid) / (total weight of Co contained in residue) × 100
(Equation 2) Cobalt purity = (weight of Co ions dissolved in acid) / (weight of all metal ions dissolved in acid) × 100
Here, the horizontal axis of FIGS. 4 (a), (b), and (c) indicates the number of moles of hydrogen ions that can be released by the acid, normalized by the number of moles of cobalt contained in the residue. That is, since sulfuric acid and nitric acid are divalent and monovalent acids, respectively, they are indicated by twice the number of moles of sulfuric acid and one time the number of moles of nitric acid. As the acid, a comparison was made using sulfuric acid having no redox action and nitric acid having an oxidizing action. For comparison, a sodium hydrogen sulfite aqueous solution having alkaline and reducing action and solutions of various pH (hydrogen ion index) of EDTA (ethylenediaminetetraacetic acid) having a chelating action were also used. In the case of a sodium hydrogen sulfite aqueous solution, it is shown in terms of the number of moles of sodium hydrogen sulfate relative to the number of moles of cobalt contained in the residue. In the case of EDTA, the horizontal axis in FIG. 4 (a), (b), (c), and (d), black circles indicate leaching rate and white circles indicate purity.

From the figure, by adding more than twice the number of moles of cobalt in both sulfuric acid and nitric acid, the leaching rate reaches almost the maximum value, achieving a leaching rate of 60% or more and a purity of 90% or more. Nitric acid having an oxidizing action achieved a leaching rate and purity of 90% or more. On the other hand, in the sodium hydrogen sulfite aqueous solution which is a reducing and alkaline solution, the leaching rate was less than 30%. From the above, it is desirable that the cobalt leaching solution is acidic, and it is desirable that it also has oxidizing properties. In the EDTA aqueous solution that is a chelating agent, the leaching rate of cobalt was 50% or more and the purity was 90% or more in a neutral or acidic region having a pH of 8 or less.

The cobalt leachate obtained by allowing nitric acid 4.5 times the number of moles of cobalt contained in the residue to act was neutralized with an aqueous sodium hydroxide solution to obtain a precipitate of cobalt hydroxide.

In this example, an example in which a chelating agent is added to a leachate obtained by the same lithium leaching process as described in Examples 1 to 3 and then solvent extraction is performed to recover high-purity lithium. To do.

After adding ethylenediaminetetraacetic acid (hereinafter referred to as EDTA) as a chelating agent to a mixed aqueous solution containing 0.01 mol / dm ^{3 of} lithium chloride, aluminum chloride, and iron chloride to a concentration of 0.1 mol / dm ³ , the pH is The pH was adjusted with hydrochloric acid to be in the range of 3-7. Here, the mixed aqueous solution is a solution simulating the filtrate after treatment with deionized water described in Example 1. The filtrate after treatment with deionized water described in Example 1 is alkaline and the 0.3 mol / dm ³ lithium chloride aqueous solution is neutral, but the pH is adjusted after the chelating agent is added, so the same Can be treated as a solution. To a solution 15cm ³ after pH adjustment, the kerosene containing the metal ion extractant 15cm ³ was added, mixture was allowed to fully contact with vigorous stirring and allowed to stand until separation into two layers. Any of the following was used as the metal ion extractant. That is, one is D2EHPA [generic name: di-2-ethylhexyl phosphate] (0.5 mol / dm ³ ) and tri-n-butyl phosphate (hereinafter TBP, 0.1 mol / dm ³ ) manufactured by Daihachi Chemical. Is added (hereinafter referred to as extractant I), and the other is PC-88A [generic name: 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester] (0.5 mol / dm ³ ) manufactured by Daihachi Chemical Co., Ltd. (0.1 mol / dm ³ ) added (hereinafter referred to as extractant II).

After separating into two layers, each of the aqueous phase and the oil phase was collected, and the concentration of contained metal ions was measured by atomic absorption method, and the extraction rate into the oil phase was determined. (In this embodiment, taking out metal ions from the aqueous phase toward the oil phase is called extraction.)
(Expression 3) Extraction rate = (Weight of target metal ions in oil phase) / (Weight of target metal ions in water phase) x 100
The results are shown in FIGS. FIG. 5 shows the results when the extractant I is used, and FIG. 6 shows the results when the extractant II is used. In both figures, (a) is the extraction rate into the oil phase, and (b) is the purity of lithium in the oil phase. When the extractant I is used (FIG. 5), the extraction rate of lithium increases as the pH increases, and is as high as 80% at pH = 4.2 and as high as 96% at pH = 4.8. However, the extraction rate of both iron and aluminum is less than 0.1%, and the purity of lithium in the oil phase (the weight of lithium with respect to the total weight of lithium, aluminum, and iron) is 99% as shown in FIG. That's it. When the pH reaches 4.9, iron extraction is confirmed, and the lithium purity of the oil phase decreases to 80%.
When the extractant II is used (FIG. 6), the lithium extraction rate also increases with an increase in pH, which is about 25% at pH = 4.5 and about 55% at pH = 5. In this pH range, the extraction rate of both iron and aluminum is less than 0.1%, and the purity of lithium in the oil phase is 99% or more as shown in FIG. When the pH exceeds 5, extraction of iron is confirmed, and the lithium purity of the oil phase decreases. Thus, by adding a chelating agent, selective extraction of lithium becomes possible, and separation is possible even if aluminum or iron is mixed in the filtrate after treatment with deionized water described in Example 1. is there.

The result of examining the action of the chelating agent in more detail will be described with reference to FIGS. The aqueous solution of lithium chloride in 0.3 mol / dm ^3, the chelating agent is added to a concentration of 0.1 mol / dm ^3, and evaluate the impact of chelating agent on the extraction rate of lithium. As the chelating agent, oxalic acid, citric acid, EDTA, or Tiron [generic name: 1,2-dihydroxy-3,5-benzodisulfonic acid disodium monohydrate] manufactured by Dojindo Laboratories was used. For comparison, a study was also conducted without adding a chelating agent. After that, it was brought into contact with kerosene containing the extractant I or the extractant II, the lithium extraction reaction was advanced, and the lithium ion concentration in the solution after the reaction was measured. As shown in FIG. 7, as compared with the case where no chelating agent was added, no significant difference was observed in the lithium extraction rate when any chelating agent was added.

For aluminum and iron, add any of the above chelating agents to a solution containing either of them at a concentration of 5 × 10 ⁻³ mol / dm ³ , adjust the pH, and extract in the same way as the above lithium extraction The extraction reaction was allowed to proceed in contact with kerosene containing Agent I or II. 8 and 9 are diagrams showing the extraction rates of aluminum and iron, respectively. In each figure, (a) and (b) are the results using Extractant I and Extractant II, respectively. In any combination of metal ions and extraction agents, there is a pH range where extraction is suppressed. For example, when iron ions are extracted with the extractant II (FIG. 9B), when the chelating agent is not added, the pH is approximately 100% in the range of 2 to 6.5. However, the extraction rate when oxalic acid is added is suppressed to 20% or less at a pH of 5 or less. Even with other chelating agents, the citric acid has a pH of 5.6 or more, and Tiron has a pH of 5.3 or more. At pH 6.2 or lower, the extraction rate is suppressed to 20% or lower. Moreover, when the pH range in which the extraction rate is suppressed to 1% or less when EDTA is used as the chelating agent is described for each combination of metal ions and the extractant, a combination of aluminum and the extractant I (FIG. 8 (a)). ) 6 or less, the combination of aluminum and extractant II (FIG. 8B) is 4.6 or less, and the combination of iron and extractant I (FIG. 9A) is 5.1 or less, iron and extractant II. In the combination (FIG. 9B), it is 5.6 or less. This pH region substantially coincides with the region where the extraction of aluminum and iron is suppressed in FIGS. As described above, as a result of the chelating agent preferentially acting on iron or aluminum, lithium can be selectively extracted from a mixed solution of lithium, aluminum, and iron.

FIG. 10 shows the effect of the extractant on the extraction of lithium. The pH to be extracted can be freely selected by the operator. However, when operating at a higher pH, dibenzoylmethane, which is a β-diketone-based extractant [generic name: 1,3-diphenyl- 1,3-propanedione] may be used.

FIG. 11 shows the effect of TBP [generic name: tri-n-butyl phosphate] on the extraction of lithium. Even if TBP is not added, lithium can be extracted. However, when the pH is increased, a third phase different from the aqueous phase and the oil phase is generated, and it becomes difficult to recover the elements contained in the phase. Therefore, it is desirable to add TBP.

In this example, the same solvent extraction process as described in Example 4 was performed on the leachate obtained by the lithium leaching process similar to that described in Examples 1 to 3, and then, An example in which high-purity lithium is recovered by performing a crystallization peeling operation on the obtained oil phase will be described.

FIG. 12 shows an apparatus 500 for performing crystallization peeling. The lower part of the peeling tank 501 has a conical shape, and is connected to the filter 521 and the oil phase recovery tank 551 through a branch cock 511. The peeling tank 501 is also provided with a stirrer 502 and blades 503 that are rotationally driven by the stirrer. The peeling tank 501 also has an inlet 504 for introducing an oil phase obtained by the solvent extraction device 600 and an inlet 505 for introducing an aqueous phase having a crystallization peeling function.

The oil phase obtained by performing the solvent extraction process in the solvent extraction apparatus 600 in the same manner as described in Example 4 is charged from the charging port 504, and the crystallization stripping solution stored in the crystallization stripping solution tank 552 is sent. When the liquid pump 572 was charged from the charging port 505 and stirring was started with the blade 503, white turbidity was observed in the aqueous phase. When the stirring was stopped after a certain period of time and the mixture was allowed to stand, it was separated into three phases of a white precipitate, an aqueous phase and an oil phase in order from the bottom. Thereafter, the white cock is introduced into the filter 521 by carefully opening the branch cock 511. A vacuum pump 522 and a leak valve 523 are connected to the filter in an arrangement as shown in the figure, and the mass transfer speed from the separation tank 501 is optimally controlled by setting the pressure inside the filter 521 to an appropriate pressure reduction. In addition, the filter cloth 525 provided in the filter 521 can efficiently separate the precipitate and the aqueous phase. After the precipitate has been completely transferred to the filter by visual observation, the aqueous phase is moved, and after collecting the fine precipitate by filtration as much as possible, the branch cock 511 is switched to introduce the oil phase into the oil phase recovery tank 551. The crystallization peeling operation is completed when all the oil phases have moved.

Thereafter, the filter cloth 525 is taken out and subjected to appropriate washing and drying, whereby the lithium compound is recovered as a dried solid. Further, the filtrate collected in the filter 521 is moved to the crystallization peeling liquid tank 552 by the liquid feeding pump 571. The crystallization peeling tank 552 is connected to a solid carbonate feeding mechanism (counter ion supply mechanism) 591 via a valve 582, and the crystallization peeling liquid recovered after the crystallization peeling treatment is an appropriate amount of carbonate. Then, it is used again as a crystallization stripping solution. The oil phase in the oil phase recovery tank 551 is transferred to the solvent extraction device 600 by the liquid feed pump 573 and used as an extraction solvent.

Here, the composition change in the oil phase crystallization peeling apparatus 500 obtained by the solvent extraction apparatus 600 is as follows. First, the oil phase before being put into the peeling tank 501 contains an organic solvent such as kerosene as a main component, for example, the extractant I or the extractant II described in Example 4, and lithium ions. This oil phase comes into contact with the crystallization peeling solution in the peeling tank 501. The crystallization stripping solution contains a lithium salt to be deposited and a compound other than the lithium salt (hereinafter referred to as a stripping aid) of the same ion as the lithium counter ion in the lithium salt at an appropriate concentration. For example, when the lithium salt to be deposited is lithium carbonate, the counter ion is a carbonate ion, and the stripping aid includes, for example, a carbonate such as sodium carbonate, a bicarbonate such as sodium bicarbonate, Carbonate ions and hydrogen carbonate ions generated by dissolving carbon dioxide in water can be used. In addition, the above-described appropriate concentration will be described using an example in which lithium carbonate is used. The value calculated by the product of the square of the lithium ion activity present in the solution and the carbonate ion activity is the solubility product of lithium carbonate. Is almost equal to When such a crystallization stripping solution and the oil phase come into contact with each other, lithium ions in the oil phase move to the water phase. This lithium ion movement tries to increase the lithium ion activity of the aqueous phase, but the product of the square of the value and the counter ion activity has already almost reached the solubility product of the lithium compound to be deposited. It cannot be present in the aqueous phase as an ion and is precipitated as a lithium salt crystal. The oil phase lithium moves to the water phase until it reaches equilibrium with the lithium concentration in the water phase, and most of the transferred lithium is precipitated, completing the crystallization peeling reaction. The oil phase after crystallization peeling contains some lithium, but can be used again as an extraction solvent. Since the extraction rate of lithium is very high as shown in Example 4, even if lithium is already contained in the extraction solvent, it does not hinder the next extraction.

On the other hand, the composition change of the crystallization stripping solution is as follows. The crystallization stripping solution before being put into the stripping tank 501 contains the stripping aid containing the main component water, the lithium salt to be deposited, and the same ion as the counter ion of lithium in the lithium salt. . In the stripping tank 501, when the oil phase obtained by solvent extraction comes into contact with the crystallization stripping solution, lithium ions try to move from the oil phase to the crystallization stripping solution, but the square of the lithium ion activity of the aqueous phase. Since the product of the counter ion activity has already substantially reached the solubility product of the lithium salt to be precipitated, crystals of the lithium salt are precipitated. The oil phase lithium moves to the water phase until it reaches equilibrium with the lithium concentration in the water phase, and most of the transferred lithium is precipitated, completing the crystallization peeling reaction. Thus, the lithium concentration in the crystallization stripping solution before and after crystallization stripping is substantially constant. However, since the lithium transferred from the oil phase forms a precipitate together with the counter ion, the concentration of the counter ion decreases corresponding to the amount of lithium transferred. Therefore, the crystallization stripping solution after the stripping reaction can be used again as a crystallization stripping solution after increasing the concentration of the counter ion by adding an appropriate amount of the stripping aid.
As a result of repeating the above operations, lithium can be recovered with very high efficiency.

An example of a process flow for recovering a lithium salt and a cobalt salt from the lithium ion batteries disclosed in Examples 1 to 5 is collectively shown in FIG. When water extraction 10 is performed in the same manner as in Example 1 on the sieved product 5 obtained after subjecting the waste battery 1 to roasting / pulverization 2 including vacuum roasting, pulverization, and sieving. A residue (including Co) 111 and a solution (mainly leaching Li) 211 are obtained. At this time, only lithium is leached in the solution 211, but some aluminum and iron are also included. Therefore, by performing the solvent extraction 220 in the same manner as in Example 4, the oil phase 221 mainly containing lithium and the water phase 222 containing aluminum and iron are separated. By performing the crystallization separation 230 described in Example 5 on the oil phase 221, the oil phase 231 is separated into a precipitate (Li salt is precipitated) 232 and an aqueous phase 233. The oil phase 231 is used again for the solvent extraction 220 as an extraction solvent, and the aqueous phase 233 is used for the crystallization peeling 230 as a crystallization peeling liquid after adding the counter ion.

When the selective dissolution 120 using an acid is performed on the residue 111 obtained by the water extraction 10 in the same manner as in Example 3, it is separated into a residue 121 containing iron or manganese and a solution 122 containing cobalt or aluminum. it can. Solvent extraction 130 is performed on the solution 122 under the condition that cobalt is preferentially extracted from aluminum, whereby the oil phase 131 containing cobalt and the aqueous phase 132 containing aluminum are separated. When crystallization separation 140 is performed on the oil phase 131 using an acid or the like, the oil phase 141 is separated into an oil phase 141 containing almost no cobalt and an aqueous phase 142 containing cobalt. Thereafter, by performing precipitation 150 in which an alkali such as an aqueous sodium hydroxide solution is added to the aqueous phase 142, for example, cobalt can be recovered as a precipitate 151 such as cobalt hydroxide.

DESCRIPTION OF SYMBOLS 1 Waste battery 2 Roasting and grinding | pulverization process 5 Product under sieve 10 Water extraction process 111,121 Residue 120 Selective dissolution process 122 Solution 130,220 Solvent extraction process 131,141,221,231 Oil phase 132,142,152,222, 233 Water phase 140,230 Crystallization peeling treatment 150 Precipitation treatment 151,232 Precipitation 211 Solution 500 Crystallization peeling device 501 Stripping tank 502 Stirrer 503 Blade 504,505 Input 511 Branch cock 521 Filter 522 Vacuum pump 523 Leak valve 525 Filtration Cloth 551 Oil phase recovery tank 552 Crystallization stripping solution tank 571, 572, 573 Feed pump 581, 582, 583 Valve 591 Solid carbonate charging mechanism (counter ion supply mechanism)

Claims (12)

A method for recycling waste lithium-ion batteries,
Refining the roasted powder by baking, pulverizing, and sieving the lithium ion battery at a temperature of 500 ° C. or less and under a reduced pressure of 10 Pa or less;
Deionized water or an acid whose pH has been adjusted is allowed to act on the obtained roasted powder so that the equilibrium pH of the solution after leaching of lithium is 8.6 or more. And a step of obtaining a leachate from which lithium is selectively leached. The method for recycling a lithium ion battery according to claim 1, wherein the acid whose pH is adjusted is at least one of sulfuric acid, nitric acid, and sodium hydrogen sulfite. The leachate obtained in the leaching step is sprayed into a heated carbon dioxide atmosphere or dried by spraying onto a substrate at an appropriate temperature placed in the carbon dioxide atmosphere to obtain a lithium carbonate powder. The method for recycling a lithium ion battery according to claim 1, further comprising a step. 2. The method for recycling a lithium ion battery according to claim 1, further comprising a step of aeration of carbon dioxide through the leachate obtained in the leaching step to obtain a precipitation of lithium carbonate. 2. The resource of a lithium ion battery according to claim 1, further comprising a step of obtaining a leachate in which cobalt contained in the residue is leached by causing an acidic aqueous solution to act on the residue obtained in the leaching step. Method. 6. The method for recycling a lithium ion battery according to claim 5, wherein the acidic aqueous solution is nitric acid or an oxidizing acid. The method for recycling a lithium ion battery according to claim 4, further comprising the step of neutralizing the leachate from which cobalt has been leached with an aqueous sodium hydroxide solution to obtain a precipitate of cobalt hydroxide. The solvent extraction step of extracting lithium ions contained in the leaching solution into an oil phase by allowing a solvent extraction solution containing a chelating agent to act on the leaching solution obtained in the leaching step. 2. A method for recycling a lithium ion battery according to 1. The method for recycling a lithium ion battery according to claim 8, wherein the solvent extract is kerosene containing a chelating agent and a metal ion extractant. Further, a crystallization peeling step is performed in which an aqueous solution of a lithium salt is allowed to act on the oil phase obtained in the solvent extraction step to back extract lithium ions contained in the oil phase into an aqueous phase and precipitate the lithium salt. The method for recycling a lithium ion battery according to claim 8, comprising: A chelating agent is added to a leachate obtained by selectively leaching lithium in the roasted powder by allowing deionized water or acid to act on the roasted powder obtained by roasting, pulverizing and sieving a lithium ion battery. The oil phase obtained by extracting the lithium ions contained in the leachate by the action of the solvent extract containing selenium is introduced from the solvent extractor, and at the same time, the aqueous phase having the function of crystallization separation is introduced, and the mixture is stirred. A peeling tank that is allowed to stand and separate into three phases of precipitation, aqueous phase and oil phase;
A filter that decompresses the inside with a vacuum pump, introduces a precipitate and an aqueous phase from the peeling tank through a branch cock, and efficiently separates the precipitate and the aqueous phase with a filter cloth;
An oil phase recovery tank that collects and stores the oil phase in the peeling tank and supplies it as an extraction solvent to the solvent extraction device;
The filtrate separated from the filter is collected and stored, and an appropriate amount of stripping aid is introduced from the counter-ion supply mechanism, and the stored filtrate is again supplied to the stripping tank as a crystallization stripping solution. A liquid tank,
A crystallization peeling apparatus comprising a counter ion supply mechanism for feeding a peeling aid to the crystallization peeling liquid tank. The aqueous phase having the function of crystallization peeling includes water as a main component, a lithium salt having a saturated concentration, and a compound (peeling aid) other than a lithium salt containing the same ion as the counter ion of lithium in the lithium salt. Have
The crystallization peeling apparatus according to claim 11, wherein the solvent extract is kerosene containing a chelating agent and a metal ion extractant.

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