JP2014235945A - Method for concurrently recovering lithium salt for electrolyte use and organic solvent from waste electrolytic solution, and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for concurrently recovering a lithium salt for electrolyte use and an organic solvent, which can be preferably reused for lithium batteries and lithium ion batteries, from waste electrolytic solution resulting from a trouble in a manufacturing process of the lithium batteries and the lithium ion batteries, and from waste electrolytic solution collected from used batteries while suppressing the production of a lithium salt insoluble to organic solvent; and a device which allows such a method to be implemented.SOLUTION: A method for concurrently recovering a lithium salt for electrolyte use and an organic solvent from waste electrolytic solution comprises the steps below in a process for heating and condensing, by an evaporator, the waste electrolytic solution containing the organic solvent and the lithium salt serving as electrolyte of lithium batteries and/or lithium ion batteries thereby causing the lithium salt to crystallize and concurrently, condensing, by a condenser, the organic solvent evaporated by the evaporator and recovering the condensed organic solvent: mutually communicating the evaporator and the condenser thereby forming a sealable system; evaporating the organic solvent by heating the waste electrolytic solution while controlling the amount of emission of uncondensed gas in the condenser to outside the system in the evaporator; and condensing, by the condenser, the organic solvent evaporated by the evaporator.

Description

  The present invention relates to a method for simultaneously recovering a lithium salt for an electrolyte and an organic solvent from a waste electrolyte solution of a lithium battery or a lithium ion battery, and an apparatus suitable for the recovery.

  In recent years, as the lithium-ion battery market has rapidly expanded from electronic devices such as mobile phones and personal computers to cars, it has occurred due to problems in the manufacturing process of used lithium batteries, lithium-ion batteries, or lithium batteries and lithium-ion batteries. It is expected that the number of defective batteries will increase rapidly in the future. In view of the effective use of resources, various methods for recovering and recycling valuable materials from these defective batteries and / or used batteries have been proposed. To date, no effective proposal has been found for a method for simultaneously recovering a lithium salt for electrolyte and an organic solvent from a waste electrolyte recovered from a used battery.

  On the other hand, as a method for recovering and recycling valuable materials from defective batteries and / or used lithium ion batteries that occur due to troubles in the manufacturing process of lithium ion batteries, for example, used waste lithium ion batteries are baked and sieved in a high-temperature oven. There is a method of generating metal ash containing metal and metal oxide to recover metal (Patent Document 1). However, in this method, since lithium is recovered as a carbonate, the electrolyte itself cannot be recovered and the organic solvent cannot be recovered. Moreover, as a lithium salt for electrolyte, a fluorine fluorine compound is mainly used. When baking in a high temperature oven, there may be a problem of generating harmful gases such as hydrogen fluoride as decomposition products of the electrolyte.

In Patent Document 2, a saturated solution composed of LiPF ₆ that is a lithium salt constituting an electrolyte used in a lithium battery or a lithium ion secondary battery and dimethyl carbonate or diethyl carbonate is evaporated, concentrated, and crystallized. A method is described in which LiPF ₆ is purified by degassing the filtered crystals at a temperature of 60 to 90 ° C. under reduced pressure. Here, LiPF ₆ has a property of dissociating according to the reaction formula of the following formula (1), and has a vapor pressure of 2 Torr (about 0.26 kPa) or more in a temperature range of 60 to 70 ° C., so that the reduced pressure drying is 50 to 70 ° C. It is described that the vapor pressure is 6 Torr (about 0.8 kPa) or higher at 90 ° C. or higher.

Patent Document 3 evaporation in the range of -20 ° C. to 150 DEG ° C. The solvent from the solution comprising LiPF ₆ and dimethyl carbonate method for producing LiPF ₆ to be concentrated crystallizing LiPF ₆ is described. However, even if this production method is applied as a means for simultaneously recovering the lithium salt for electrolyte and the organic solvent from the waste electrolyte solution, as described in Patent Document 2, it is not a little when the organic solvent containing LiPF ₆ is heated. When LiPF ₆ is dissociated and the temperature exceeds 60 ° C., decomposition becomes significant. Therefore, there is a problem that LiF that is insoluble in the organic solvent that is an impurity remains in the crystallized LiPF ₆ to lower the purity of LiPF ₆ .

  In addition, lithium salts that are insoluble in organic solvents for batteries, not limited to LiF, promote clogging of the filter medium in the filtration process for lithium battery and / or lithium ion battery electrolytes, and have a serious adverse effect on the electrolyte production process. give. For this reason, these impurities are strictly controlled in the electrolyte manufacturing process.

JP 2003-157913 A JP-A-11-147705 Japanese Patent Laid-Open No. 10-316410

  The present invention suppresses the production of lithium salts that are insoluble in organic solvents from waste electrolytes generated from troubles in the manufacturing process of lithium batteries and / or lithium ion batteries and / or waste electrolytes recovered from used batteries. However, it is an object to provide a method for simultaneously separating and recovering an electrolyte lithium salt and an organic solvent that can be suitably reused for the lithium battery and / or lithium ion battery, and an apparatus that can implement the method. And

The gist of the present invention is as follows:
[1] A waste electrolyte containing an organic solvent and a lithium salt as an electrolyte of a lithium battery and / or a lithium ion battery is heated and concentrated in an evaporator to crystallize the lithium salt, and at the same time, the evaporation is performed in a condenser. When condensing and recovering the organic solvent evaporated in the vessel,
The evaporator and the condenser are communicated to form a single sealable system,
The organic solvent evaporated by heating the waste electrolyte in the evaporator and evaporating the organic solvent while controlling the discharge amount of the non-condensable gas in the condenser to the outside of the system. A method of simultaneously recovering a lithium salt for electrolyte and an organic solvent from a waste electrolyte, characterized by condensing
[2] The amount of non-condensable gas discharged from the condenser to the outside of the system is controlled to 10% by mass or less of the initial amount of the electrolyte in the waste electrolyte. A method of simultaneously recovering a lithium salt and an organic solvent;
[3] The lithium salt for electrolyte from the waste electrolyte solution according to [1] or [2], wherein the condenser is provided with an exhaust means capable of discharging non-condensable gas and / or uncondensed gas out of the system. A method of simultaneously recovering an organic solvent,
[4] The method for simultaneously recovering the lithium salt for electrolyte and the organic solvent from the waste electrolyte solution according to [3], wherein the exhaust means is further provided with means for capturing uncondensed gas and extracting non-condensable gas ,
[5] The electrolyte lithium salt and the organic solvent are simultaneously obtained from the waste electrolyte solution according to any one of [1] to [4], wherein the non-condensable gas and / or the non-condensed gas in the condenser is refluxed into the evaporator. How to recover,
[6] The waste electrolyte solution according to any one of [1] to [5], wherein the lithium salt is LiPF ₆ or LiBF ₄ and PF ₅ or BF ₃ is added into the system from outside the system. A method for simultaneously recovering lithium salt for electrolyte and organic solvent from
[7] After discharging the used lithium battery and / or the lithium ion battery, which is composed of a battery member containing and / or adhering an electrolyte solution containing at least an organic solvent and a lithium salt for electrolyte. The battery according to any one of [1] to [6], which is a liquid obtained by disassembling, adding an organic solvent not containing the electrolyte lithium salt to the battery member, and extracting the electrolytic solution into the organic solvent. A method of simultaneously recovering a lithium salt for electrolyte and an organic solvent from a waste electrolyte;
[8] Any of the above [1] to [7], wherein a low boiling point organic solvent and / or an organic solvent capable of forming a minimum boiling point azeotrope with a high boiling point solvent component in the waste electrolyte is added to the evaporator. A method of simultaneously recovering a lithium salt for electrolyte and an organic solvent from the waste electrolyte solution according to claim 1,
[9] An evaporator that heats a waste electrolytic solution containing an organic solvent and a lithium salt that is an electrolyte of a lithium battery and / or a lithium ion battery to evaporate the organic solvent and crystallize the lithium salt;
A condenser for condensing and recovering the organic solvent evaporated in the evaporator;
A connecting pipe that connects the evaporator and the condenser to form a single sealable system;
The condenser has exhaust means capable of discharging non-condensable gas and / or uncondensed gas in the condenser to the outside of the system;
Waste electrolysis characterized by having control means for controlling the discharge amount of non-condensable gas in the system to the outside by the exhaust means while condensing the organic solvent evaporated in the evaporator in the condenser An apparatus for simultaneously recovering lithium salt for electrolyte and organic solvent from liquid,
[10] The apparatus for simultaneously recovering the lithium salt for electrolyte and the organic solvent from the waste electrolyte solution according to [9], wherein the exhaust means captures uncondensed gas and further extracts non-condensable gas.
[11] A reflux means for refluxing non-condensable gas and / or uncondensed gas in the condenser into the evaporator,
An adding means for adding PF ₅ or BF ₃ into the system from outside the system;
The apparatus further comprises any one or more of solvent supply means for supplying an organic solvent capable of forming a low boiling point organic solvent and / or a high boiling point solvent component in the waste electrolyte solution and a minimum boiling point azeotrope to the evaporator. The present invention relates to an apparatus for simultaneously recovering a lithium salt for electrolyte and an organic solvent from the waste electrolyte solution according to [10].

According to the method of the present invention, by suppressing the production of the insoluble lithium salt, an electrolyte that can be suitably reused for the battery from the waste electrolyte solution at low cost without performing a particularly sophisticated and complicated purification. The lithium salt and the organic solvent can be separated and recovered at the same time.
Among them, in the method of the present invention, non-condensable gas and / or uncondensed gas in the condenser is refluxed into the evaporator, or PF ₅ or BF ₃ is added into the system from outside the system. Or by supplying a low boiling point organic solvent and / or an organic solvent capable of forming a minimum boiling point azeotrope with a high boiling point solvent component in the waste electrolyte to the evaporator. Therefore, it is possible to efficiently recover a high-quality lithium salt.

Moreover, by using the apparatus of the present invention, it is possible to efficiently recover the lithium salt for electrolyte and the organic solvent from the waste electrolyte solution.
Among them, the apparatus of the present invention includes a reflux means for refluxing non-condensable gas and / or uncondensed gas in the condenser into the evaporator, and PF ₅ or BF ₃ from the outside of the system into the system. Any one of an addition means for adding to the solvent, an organic solvent having a low boiling point and / or a solvent supply means for supplying an organic solvent capable of forming a minimum boiling azeotrope with the high boiling point solvent component in the waste electrolyte. By further providing at least one, the production of insoluble lithium salt can be remarkably suppressed, and high-quality lithium salt can be efficiently recovered.

FIG. 1 is a schematic explanatory view showing an example of an embodiment of the apparatus of the present invention. FIG. 2 is a schematic explanatory view showing an example of another embodiment of the apparatus of the present invention. FIG. 3 is a schematic explanatory view showing an example of another embodiment of the apparatus of the present invention. FIG. 4 is a schematic explanatory view showing an example of another embodiment of the apparatus of the present invention. FIG. 5 is a schematic explanatory view showing an example of another embodiment of the apparatus of the present invention. FIG. 6 is a schematic explanatory view showing an example of another embodiment of the apparatus of the present invention.

  Embodiments of the present invention will be described in detail below, but the description is an example of embodiments of the present invention, and the present invention is not limited to these and can be implemented with any modifications.

1. Recovery method The method of the present invention is a method of simultaneously recovering a lithium salt for electrolyte and an organic solvent from a waste electrolyte, and a waste electrolyte containing an organic solvent and a lithium salt that is an electrolyte of a lithium battery and / or a lithium ion battery. In condensing and recovering the organic solvent evaporated in the evaporator at the same time as condensing the lithium salt by heating and concentrating in an evaporator,
The evaporator and the condenser are communicated to form a single sealable system,
The waste electrolyte is heated in the evaporator to evaporate the organic solvent while controlling the discharge amount of the non-condensable gas in the condenser to the outside of the system, and the organic solvent evaporated in the evaporator is condensed in the condenser. It is characterized by making it.

  The waste electrolyte referred to in the present invention is a waste electrolyte generated in troubles in the production process of a lithium battery and / or a lithium ion battery and / or a waste electrolyte recovered from these used batteries, It contains lithium salt for use and organic solvent. There is no restriction | limiting in particular about content of the lithium salt and organic solvent in these waste electrolyte solutions.

  Regarding the method of recovering the waste electrolyte from the used battery, the used lithium battery and / or lithium ion comprising a battery member containing and / or adhering to an electrolyte containing at least an organic solvent and a lithium salt for electrolyte The battery is discharged and then disassembled, and an extraction organic solvent not containing the electrolyte lithium salt is added to the battery member, and the electrolyte solution is extracted into the organic solvent and recovered.

  The battery may be disassembled as long as the battery member containing and / or adhering to the electrolyte solution containing at least an organic solvent and an electrolyte lithium salt can be disassembled so as to be in contact with the organic solvent. Examples of the battery member include a positive electrode, a negative electrode, a separator, a positive electrode can, and a negative electrode can.

  In the extraction, the disassembled battery member may be immersed in an organic solvent for extraction. Moreover, you may make the said organic solvent flow as needed. As a flow method, the organic solvent is heated and refluxed, the organic solvent is forced to flow using a fluid device such as a pump or a stirring blade, and the organic solvent is vibrated using a vibrating element. And a method of applying centrifugal force to the member containing the waste electrolyte. These flow methods may be used individually or in combination of a plurality of methods. However, a method of applying vibration or a method of applying centrifugal force is effective as a method of extracting the electrolyte solution impregnated in the member.

  The organic solvent for extraction is not particularly limited as long as it is a solvent that can dissolve the waste electrolyte solution. However, when an organic solvent used for a lithium battery and / or a lithium ion battery is used, the recovered electrolyte is used. Even if an organic solvent for extraction remains in the solvent, it is preferable because it does not adversely affect the battery. Among them, diethyl carbonate, ethyl methyl carbonate or dimethyl carbonate has a relatively low boiling point, and is extracted from a solution extracted as a solvent for extraction. Dimethyl carbonate having the lowest boiling point is particularly preferred because it can be easily recovered by distillation and reused.

The lithium salt for the electrolyte contained in the waste electrolyte solution is not particularly limited as long as it is a lithium salt that dissolves in an organic solvent and exhibits conductivity, and examples thereof include LiPF ₆ , LiBF ₄ , and LiClO _4. However, when the lithium salt itself and / or a solution in which the lithium salt is dissolved in an organic solvent are heated, it decomposes to generate a gas generated by the decomposition in the vapor of the organic solvent and to generate the insoluble lithium salt. Lithium salts are preferred. In particular, LiPF ₆ or LiBF ₄ can be more preferably applied because it dissociates considerably when heated and has a vapor pressure of several kPa when it reaches 60 ° C. or higher, and the salt is significantly decomposed.

  Examples of the organic solvent contained in the waste electrolyte include cyclic carbonates such as ethylene carbonate, propylene carbonate, and vinylene carbonate, and chains such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, depending on the use environment or purpose of use of the battery. Cyclic esters such as linear carbonates, γ-butyrolactone, chain esters such as methyl acetate, cyclic ethers such as tetrahydrofuran, chain ethers such as 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl At least selected from the group consisting of sulfur-containing compounds such as sulfoxide and sulfolane, fluorine-containing carbonates, fluorine-containing ethers, fluorine-containing lactones, fluorine-containing esters, and fluorine-containing chlorine-containing ethers. 2 or more types The combined organic solvent is used, but the present invention is applicable without limitation to these organic solvents.

The water contained in the waste electrolyte is preferably 100 ppm or less, more preferably 10 ppm or less, and most preferably 1 ppm or less. When moisture is present, the lithium salt of the electrolyte reacts with moisture during heating and concentration in an evaporator described later, and an insoluble lithium salt that is different from the target LiPF ₆ or LiBF ₄ in an organic solvent, hydrofluoric acid, phosphoric acid, Alternatively, it is not preferable because the purity of the lithium salt for electrolyte recovered by generating other acid is lowered. Examples of insoluble lithium salts include lithium oxyfluorophosphate such as LiF, LiOH, Li ₂ CO ₃ , Li ₃ PO ₄ , and Li ₂ PO ₃ F, lithium hydroxyfluoroborate, and lithium borate.

  For this reason, when the waste electrolyte contains 100 ppm or more of water, it is preferably heated and concentrated after purification for reducing the water content. As the purification method, usual dehydration means such as extraction, adsorption, dehydration distillation and the like can be performed alone or in combination. In particular, when purifying by adsorption, an adsorbent such as molecular sieve or activated carbon can be preferably used.

In the method of the present invention, the waste electrolyte is treated in one sealable system in which an evaporator and a condenser are communicated.
Here, “one system that can be sealed” is one system in which the evaporator and the condenser communicate so that the organic solvent gas generated in the evaporator can be supplied into the condenser. Gases of organic solvent, lithium salt crystallized by evaporator, organic solvent condensed by condenser and non-condensable gas and / or uncondensed gas can be discharged to the outside of evaporator and condenser as necessary It means that it can be sealed. For example, as shown in FIG. 1, the aspect by which the evaporator and the condenser are connected by the communicating pipe | tube is mentioned. Further, this system is configured so that a solution of an organic solvent in which a lithium salt is dissolved, PF ₅ or BF ₃ can be supplied from outside the system.

  In the present invention, before the concentration by heating, an inert gas is supplied into the system in advance to exclude air and the like, and then the inert gas is excluded from the system by reducing the pressure, etc. It can be recovered efficiently. In addition, if the inert gas remains in the system, it causes an increase in the evaporation temperature in the heating and concentration process or a decrease in the condensation temperature in the condensation process, and a higher temperature heating medium or a lower temperature cooling medium is required. .

In addition, it is preferable that the waste electrolyte is supplied to the evaporator after moisture in the system is completely removed. The presence of moisture in the system is not preferable because it may induce electrolyte decomposition. Therefore, the moisture contained in an inert gas such as N ₂ used as an atmospheric gas in the purging of the system or removal of the precipitated crystals and filtration is preferably 100 ppm or less, more preferably 10 ppm or less, and 1 ppm or less. Is particularly preferred.

  Further, it is preferable that the waste electrolytic solution is filtered in advance to remove solid impurities and then supplied to the evaporator. The purity of the lithium salt for electrolyte recovered after the solid impurities are purified by filtration is improved. Any filtering means may be used as long as it can filter out solid impurities in the waste electrolyte, and the material, the size of the sieve, the size of the filtering device, and the like are not particularly limited.

In the present invention, the waste electrolyte is supplied to the evaporator in the system and concentrated by heating. By concentrating the waste electrolyte by heating, the organic solvent is vaporized and the lithium salt concentration is increased and crystallizes in the waste electrolyte.
However, if the temperature of the waste electrolyte rises too much, the lithium salt tends to decompose. For example, LiPF ₆ decomposes into LiF and PF ₅ as shown in the above formula (1), and the generated PF ₅ may cause decomposition of the organic solvent.
Therefore, in the present invention, the heat concentration in the evaporator is preferably set in the range of −20 ° C. to 150 ° C. from the viewpoint of crystallization while suppressing the decomposition of the lithium salt as described above. C. to 120.degree. C. is more preferable, and 20.degree. C. to 100.degree. C. is particularly preferable.

  The evaporator used in the present invention may be any one that can be applied to any one of batch, semi-batch, and continuous operation methods. In the batch or semi-batch method, the waste electrolyte may be concentrated until it completely evaporates to dryness, but the heating efficiency decreases due to the reduction of the heat transfer area and the lithium salt is deposited on the heat transfer surface. It is preferable to stop the concentration with the solvent remaining in order to fix the crystals.

  The evaporator is not particularly limited as long as it has a function of heating the waste electrolyte and evaporating the organic solvent. A tank type evaporator equipped with a jacket type heat exchanger and a heat exchanger are mounted inside the tank. A tank-type evaporator, an evaporator that supplies a waste electrolyte solution to a heat exchanger, and performs concentration by heating are preferably used. Of course, stirring the waste electrolyte in the evaporator by using a stirrer, bubbling with gas or using a liquid feeding means improves the heat transfer performance of the evaporator, and the lithium salt on the heat transfer surface. Effective in reducing crystal adhesion

The evaporator is preferably provided with a take-out port for taking out crystals deposited by evaporation of the waste electrolyte or a solution containing the crystals out of the system. More preferably, the outlet is connected via a valve to a system that supplies a filtration device for separating crystals from the solution.
A specific configuration of the evaporator will be described later.

  For waste electrolytes containing organic solvents with a high boiling point and / or a high melting point, the evaporation temperature becomes high even if the present invention is applied by ordinary means. It may be necessary to perform an operation. Further, after completion of concentration, the high-melting organic solvent may solidify at room temperature, and it may be difficult to filter lithium salt crystals. Alternatively, the high-boiling organic solvent remains attached to the lithium salt crystals even if it is filtered at a high temperature to prevent coagulation. Therefore, even if it is dried as a post-treatment to remove the high-boiling organic solvent, the temperature is high. In addition, problems such as decomposition of the lithium salt crystals may occur during drying.

  In order to avoid the above problem, when the waste electrolyte containing the organic solvent having a high boiling point and / or a high melting point is heated and concentrated, a solvent having a low boiling point from outside the system may be used batchwise or continuously or a combination of both. Is preferably supplied to the evaporator, and the solvent composition in the evaporator is gradually heated and concentrated so as to be richer in low-boiling components than the initial composition. The supply amount of the low-boiling organic solvent is preferably equal to or less than the amount of the evaporated solvent and not less than the mass obtained by subtracting the mass of the high-boiling solvent component from the low-boiling solvent component in the evaporated organic solvent.

  The organic solvent having a low boiling point supplied from outside the system is preferably an organic solvent used for a lithium battery and / or a lithium ion battery, more preferably diethyl carbonate or ethyl methyl carbonate, and particularly preferably dimethyl carbonate. Of course, the low-boiling point solvent supplied from outside the system may be used after purifying the organic solvent recovered in the condenser by the above-mentioned operation by distillation, extraction, adsorption, or a combination of these operations.

Further, the waste electrolytic solution containing the organic solvent having a high boiling point and / or a high melting point may be concentrated by adding at least a component capable of forming a minimum boiling azeotrope with the high boiling solvent component. . The component to be added is preferably an organic solvent used in an electrolyte solution of a lithium battery and / or a lithium ion battery, or a compound that does not affect the characteristics of the battery. Specifically, when the high boiling point solvent component is ethylene carbonate or propylene carbonate, examples of the component capable of forming the lowest boiling point azeotrope include ethylene glycol and propylene glycol.
The lowest boiling azeotrope is a mixture of a high boiling solvent component and a component capable of forming the lowest boiling azeotrope, and means a mixture having a boiling point lower than that of the mixed solvent.
In the present invention, a high boiling point solvent component and a component capable of forming the lowest boiling point azeotrope are supplied to the evaporator, and after the high boiling point solvent component is distilled off as the lowest boiling point azeotrope, the evaporation is further performed. The content containing the lithium salt in the evaporator may be easily dried by further adding and mixing another organic solvent capable of forming the lowest boiling azeotrope with the supplied component remaining in the evaporator. .

Also the case for electrolyte lithium salt of the waste electrolyte solution is LiPF ₆ or LiBF _4, and the decomposition of LiPF ₆ or LiBF ₄ is further suppressed be added respectively PF ₅ or BF ₃ from the outside of the system, the insoluble lithium salt Production is reduced.

The timing of adding PF ₅ or BF ₃ from the outside of the system is preferably performed before or during heating and concentration, and more preferably before heating the evaporator. The place of addition may be in the evaporator or in the condenser, or may be added by connecting a means for adding PF ₅ or BF ₃ to a connecting pipe connecting the evaporator and the condenser. As the adding means, an adding device in which a measuring device such as a gas flow meter and a flow rate adjusting device such as a valve or a gas flow device such as a compressor and a blower are appropriately combined can be used.

The amount of PF ₅ or BF ₃ added from outside the system is preferably 10% by mass or less of the initial amount of the electrolyte contained in the waste electrolyte. If the amount exceeds 10% by mass of the initial amount of the electrolyte, the amount of expensive PF ₅ or BF ₃ used is increased and the cost is increased, and the reaction between PF ₅ or BF ₃ and the organic solvent is promoted, so that the organic solvent deteriorates and deteriorates. It is not preferable.

Furthermore, when the lithium salt for electrolyte is LiPF ₆ or LiBF ₄ , the filtration of the precipitated crystals taken out from the evaporator and the drying after the filtration are performed in a gas atmosphere containing PF ₅ or BF ₃ , respectively. The production of insoluble lithium salt is further reduced, which is more preferable.

Among them, it is preferable to perform the filtration with each of the drying after filtration in a gas atmosphere containing PF ₅ or BF ₃ 0.1 to 5 mol%. If PF ₅ or BF ₃ is less than 0.1 mol%, the effect is small, and if it exceeds 5 mol%, the consumption of expensive PF ₅ or BF ₃ increases, which is not preferable.

  Next, the organic solvent gas generated in the evaporator is supplied to a condenser communicated with the evaporator.

  The communication state between the evaporator and the condenser may be, for example, by connecting a vaporized organic solvent outlet in the evaporator and a vaporized organic solvent supply port in the condenser. The connecting pipe used for the connection may be any material that does not erode by the organic solvent, and the size, shape, etc. of the connecting pipe are not particularly limited.

The condenser is used to cool an organic solvent gas below the boiling point to form a liquid.
The condenser is not particularly limited as long as it has a function of cooling the evaporated solvent vapor to condense the organic solvent, and is a tank type condenser equipped with a jacket type heat exchanger or heat for introducing and condensing the solvent vapor. A condenser in which an exchanger and a storage tank for storing the condensed organic solvent are connected is preferably used.
A specific configuration of the condenser will be described later.

As described above, in the condenser, the organic solvent evaporated by the evaporator is condensed and recovered, but non-condensable gas and uncondensed gas are also confirmed as gases that are not condensed by the condenser.
In the present invention, “non-condensable gas” is defined as a gas having a vapor pressure of 13 kPa or higher at −80 ° C. generated by decomposition of the electrolyte, and captures uncondensed gas described later to extract non-condensable gas. Unless special separation operation is performed, it exists in a state mixed with uncondensed gas. In addition, “uncondensed gas” is defined as a gas that is not condensed in a condenser but is condensed in a lower temperature condensing environment, and most of it occupies the vapor pressure at the condensation temperature of the evaporated organic solvent. Gas.
Note that the types of non-condensable gas and non-condensable gas cannot be unconditionally limited depending on the type of battery. For example, examples of the non-condensable gas include PF ₅ and BF ₃ , and examples of non-condensable gas. Examples thereof include solvent gases such as dimethyl carbonate and diethyl carbonate.

  In the present invention, by controlling the condensation temperature so as to keep the operating pressure and / or the evaporation temperature in the system at a desired value, the non-condensable gas and / or the uncondensed gas is discharged from the system and / or from the condenser. It can be carried out without reflux to the evaporator, but if for some reason it cannot be controlled to a desired value, the non-condensed gas and / or uncondensed gas is discharged out of the system and / or refluxed to the evaporator. It is preferable. The reflux amount of the non-condensable gas and / or uncondensed gas in the condenser to the evaporator or the discharge amount of the non-condensable gas and / or uncondensed gas to the outside of the system is the operating pressure and / or evaporation temperature in the system. Can be determined in a steady or variable manner in conjunction with the condensation temperature so as to maintain the desired value.

  The method of the present invention has one feature in that the discharge amount of the non-condensable gas in the condenser to the outside of the system is controlled. Thus, there exists an advantage of suppressing the production | generation of the said insoluble lithium salt by adjusting the discharge | emission amount of the non-condensable gas out of the system. The adjustment of the discharge amount of the non-condensable gas is performed by an exhaust unit that can discharge the non-condensable gas and / or the non-condensable gas provided in the condenser. The exhaust means will be described later.

  The amount of non-condensable gas discharged outside the system is preferably 10% by mass or less, more preferably 5% by mass or less, and most preferably 0% by mass with respect to the initial amount of the electrolyte in the waste electrolyte solution. When the discharge amount exceeds 10% by mass of the initial amount of the electrolyte, the yield of crystallized lithium salt for electrolyte decreases, and a large amount of insoluble lithium salt is mixed in the electrolyte, so that it can be used as an electrolyte. Is not preferable because it requires a high degree of purification operation, and the organic solvent remaining in the evaporator is also significantly altered, causing coloration or increase in viscosity, and crystallized crystals are colored, or filtration becomes difficult. Problems are also triggered.

  The initial amount of the electrolyte refers to the amount of electrolyte in the waste electrolyte solution supplied to the evaporator. The initial amount of the electrolyte can be determined by measuring the concentration in the waste electrolyte solution by a weight method and the content of the lithium salt by a method such as mass spectrometry or emission spectrometry. The discharge amount of non-condensable gas to the outside of the system is measured in a gas state, but it is preferable to use a mass flow meter because the discharge amount can be directly measured by mass. When a volumetric flow meter is used, the discharge amount can be converted into mass from the density and the volumetric flow rate. In addition, each pipe is connected using a flexible joint, and the solvent is measured by weighing the evaporator, the condenser, and the non-condensable gas by using a scale to capture the non-condensable gas directly. It is also possible to measure the amount of evaporation and the amount of noncondensable gas discharged outside the system.

  The amount of non-condensable gas and / or uncondensed gas discharged or refluxed is measured through a commonly used flow meter such as a mass flow meter, thermal flow meter, or differential pressure flow meter. However, the desired amount can be controlled manually or automatically batchwise or continuously.

  Examples of the exhaust means for discharging the non-condensed gas and / or uncondensed gas provided in the condenser to the outside of the system include a valve connected to the condenser and / or an air supply means connected to the exhaust pipe to the outside of the system. It can be used suitably. The valve is not particularly limited as long as it has a function of discharging the non-condensable gas and / or non-condensed gas out of the system, and a normal globe valve or the like is preferably used in combination with a gas flow meter. When it is necessary to control the discharge, it is preferable to use a valve having an excellent flow rate adjusting function such as a needle valve. The air supply means is not particularly limited as long as it has a function of discharging the non-condensable gas and / or uncondensed gas to the outside of the system, and the gas flow device such as a vacuum pump, a blower, a compressor, etc. operates at an operating pressure or a displacement amount. It can be used as appropriate according to the use environment.

  As an example of a method for controlling the recirculation amount of the non-condensed gas and / or uncondensed gas using the air supply means or the discharge amount outside the system, the evaporation amount and the evaporation temperature are supplied to the evaporator so as to have desired values. Control the temperature and supply amount of the heating medium to be supplied and simultaneously control the temperature and supply amount of the cooling medium to be supplied to the condenser, and measure the flow rate with a flow meter installed in the reflux pipe and / or the exhaust pipe. A method using a flow rate adjusting valve installed on the discharge side of the means, a method using a flow rate adjusting valve installed on a bypass pipe connecting the discharge side and the suction side of the air supply means, or a method combining both of them is there.

Further, in the condenser, the non-condensable gas exists in a mixed gas state with the non-condensed gas, but when the proportion of the amount of the non-condensed gas is larger, the non-condensed gas is mixed without being separated. It can be said that the recovery efficiency is low because the loss of uncondensed gas increases when the gas is discharged. Therefore, as a means for exhausting the non-condensable gas with less loss, by processing the mixed gas using a means for capturing the non-condensed gas and extracting the non-condensed gas, by recovering the non-condensed gas from the mixed gas, For example, only the remaining non-condensable gas is discharged out of the system.
As a means for capturing the non-condensable gas and extracting the non-condensable gas, for example, a non-condensable gas and / or a non-condensable gas trap provided on the outlet side of the non-condensed gas is separated and extracted. It is possible to adjust by opening and closing the valve provided at the discharge port of the non-condensable gas and / or the non-condensed gas while introducing only the condensed gas into the flow meter arranged on the downstream side and measuring the flow rate of the non-condensable gas. Can be mentioned. As an example of the uncondensed gas trap, a cooler of −80 ° C. or lower may be provided, and at least two series of condensers operating at an operating temperature of −80 ° C. or lower and −80 ° C. or higher are connected in series, The exhaust means may be provided in a subsequent condenser of −80 ° C. or lower. In addition, while monitoring the amount of non-condensable gas mixed with uncondensed gas with a gas analyzer such as a gas chromatograph or Fourier transform infrared spectrometer (FT-IR), the amount of non-condensable gas discharged can be determined as desired. The amount of uncondensed gas discharged to the outside of the system can be adjusted by a flow rate adjusting device such as a valve so that the amount becomes equal to the amount.

  The organic solvent condensed by the condenser as described above, and the organic solvent derived from the non-condensed gas captured by the means for capturing the non-condensed gas may be used as they are as a solvent for organic synthesis or as a raw material. Although it may be used as a fuel, it is preferably purified and used again as a solvent for a lithium ion battery.

  As a method for purifying the recovered organic solvent, a purification method suitable for each organic solvent, for example, general purification methods such as adsorption, filtration, extraction, crystallization, and distillation can be applied singly or in combination.

  In the method of the present invention, the non-condensable gas and / or the non-condensable gas may be recirculated into the evaporator separately from the discharge of the non-condensable gas and / or the non-condensed gas to the outside of the system as described above. Good. As such a reflux means, a means for capturing the non-condensable gas and extracting the non-condensable gas may be used to separate and reflux the non-condensable gas in the condenser from the non-condensed gas. The mixed gas containing the non-condensable gas and the non-condensed gas may be refluxed as it is without being separated. Thus, the non-condensable gas and / or the non-condensed gas that is not condensed in the condenser is refluxed to the evaporator, thereby having an advantage of suppressing an increase in system pressure and evaporation temperature and a decrease in condensation temperature. As a specific reflux means, the non-condensable gas and / or uncondensed gas outlet provided in the condenser and a tubular material for supplying waste electrolyte to the evaporator are connected via a reflux pipe. Thus, the non-condensable gas and / or uncondensed gas may be supplied into the evaporator. If the evaporator is large, the reflux pipe may be connected to the supply port for the non-condensable gas and / or uncondensed gas provided in the evaporator.

  In the reflux means, an air supply means may be used. The air supply means is not particularly limited, but the operating pressure of the gas flow device such as a vacuum pump, blower, compressor, etc. from the condenser to the reflux pipe for refluxing the uncondensed gas and / or uncondensed gas to the evaporator. Or it is good to select and install suitably according to use environment, such as recirculation | reflux amount. As a matter of course, a vent valve may be provided on the discharge side of the reflux gas flow device so that both the reflux air supply means and the exhaust means are used.

In addition, the said reflux pipe should just be connected in the evaporator. From the viewpoint of enhancing the reflux effect, the end of the reflux tube may be inserted into the waste electrolyte in the evaporator and heated and concentrated while bubbling. However, the reflux tube may be blocked or the concentrated solution may flow back into the tube. You need to be careful. Moreover, said the return pipe may be connected to the addition means PF ₅ or BF _3.

  In the method of the present invention, the operating pressure in the evaporator and the condenser can be less than atmospheric pressure or higher than atmospheric pressure, but is preferably adjusted to a range of 0.1 to 500 kPa, The range of 1-100 kPa is more preferable. If the pressure is adjusted to less than 0.1 kPa, the degree of decompression is large, so expensive equipment for decompression is required, which may increase the equipment cost, and the condensation temperature of the evaporated organic solvent is lowered and the refrigerant supplied to the condenser If the temperature of the medium is not lowered by using a refrigerator or the like, problems such as the occurrence of efficient condensation occur, which is not preferable.

  Further, when the pressure is adjusted to exceed 500 kPa, the degree of pressurization is high, so expensive equipment for high pressure is required, resulting in an increase in equipment cost, and further, the evaporation temperature of the organic solvent is increased to increase the temperature as a heating source. This causes problems such as the need for a heating medium.

  Moreover, it is preferable to perform heat concentration of a waste electrolyte solution in the temperature range in which the partial pressure of the decomposition product by the heat | fever of the electrolyte contained in the said waste electrolyte solution shows the pressure of 0.0001 kPa-27 kPa. If the heat concentration is carried out at less than 0.0001 kPa, the vapor pressure of the solvent is decreased, and the operation pressure may be less than the appropriate operation pressure of 0.1 kPa. If the heating concentration exceeds 27 kPa, the vapor pressure of the organic solvent increases, and the operating pressure may exceed 500 kPa in the appropriate operating pressure range. The pressure can be measured with a pressure gauge provided in the condenser.

2. Apparatus Next, an embodiment of the apparatus of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing an outline of the overall configuration of an apparatus 1 according to the present invention.

  The apparatus 1 is an example of an apparatus that can simultaneously recover the lithium salt for electrolyte and the organic solvent from the waste electrolyte by efficiently carrying out the method of the present invention.

  The apparatus 1 includes an evaporator 2, a condenser 3, and a connecting pipe 4 that allows the evaporator 2 and the condenser 3 to communicate with each other. The evaporator 2 is connected to the condenser 3 so that the organic solvent gas generated in the evaporator 2 is supplied to the condenser 3 through the connecting pipe 4 to form a sealable system. Yes.

  The evaporator 2 heats and concentrates the waste electrolyte of the lithium battery and / or lithium ion battery to evaporate the organic solvent and crystallize the lithium salt as the electrolyte.

The evaporator 2 has a volume capable of accommodating a waste electrolyte, a strength capable of withstanding the pressure or pressure reduction of a vaporized organic solvent, a supply port 5 for supplying the waste electrolyte, and waste electrolysis inside the evaporator. A heating means 6 for heating the liquid to a predetermined temperature, an outlet 7 for taking out the crystallized lithium salt, and an outlet 8 for discharging the vaporized organic solvent are provided. There are no particular limitations on the position, size, shape, and the like of each of these parts, and any common position, size, shape, or the like according to the purpose may be used.
The system can be sealed by providing valves 9a and 9b at the supply port 5 and the take-out port 7 provided in the evaporator 2, respectively. A discharge port 8 for discharging the vaporized organic solvent is connected to the connecting pipe 4.

  The heating means 6 may be any means that can heat the evaporator 2 with a heating medium. The type of the heating medium is not particularly limited as long as the waste electrolyte supplied to the evaporator 2 can be heated to a desired temperature. Further, as shown in FIG. 1, the heating temperature may be adjusted by providing a valve 9d for adjusting the supply amount of the heating medium.

  The temperature of the waste electrolyte supplied to the evaporator 2 can be measured with a thermometer 10. The thermometer 10 should just be installed so that the temperature of a waste electrolyte solution can be measured efficiently, for example, should just be arrange | positioned in the position which can contact a waste electrolyte solution.

The evaporator 2 may be provided with a supply port 24 for supplying an inert gas such as N ₂ . In this case, in order to efficiently discharge the inert gas from the evaporator 2, a discharge port 11 may be provided and discharged from here.
In addition, in order to prevent leakage of the organic solvent during the heat concentration, it is necessary to provide a valve 9f on the pipe connected to the discharge port 11.

  Since the lithium salt crystallized by heating and concentrating in the evaporator 2 is precipitated in the waste electrolyte solution of the evaporator 2, the valve 9 b is opened from the outlet 7 provided at the lower part of the evaporator 2. It can be taken out. The extracted lithium salt can be separated from the waste electrolyte by filtering.

  The organic solvent vaporized by the evaporator 2 is supplied from the discharge port 8 to the condenser 3 through the connecting pipe 4.

  In the condenser 3, the organic solvent evaporated in the evaporator 2 is condensed and recovered.

  The condenser 3 has a volume capable of accommodating the vaporized organic solvent, a supply port 12 for supplying the vaporized organic solvent, a cooling means 13 for liquefying the vaporized organic solvent inside the condenser 3, and a liquefied organic solvent. A discharge port 14 for discharging the solvent, a discharge port 15 for discharging non-condensable gas and / or uncondensed gas, and an exhaust means 16 capable of discharging the non-condensed gas and / or non-condensed gas out of the system are provided. The position, size, shape, and the like of each part are not particularly limited, and may be a common sense position, size, shape, or the like according to each purpose. It should be noted that the system can be hermetically sealed by providing valves 9g and 9h on the pipes connected to the discharge ports 14 and 15 provided in the condenser 3, respectively. A discharge port 15 for discharging the non-condensable gas and / or the non-condensed gas is connected to the exhaust means 16.

  The said cooling means 13 should just be what can cool the vaporized organic solvent in the condenser 3 with a cooling medium. The kind of the cooling medium is not particularly limited as long as the vaporized organic solvent supplied to the condenser 3 can be cooled to a desired temperature. Further, as shown in FIG. 1, the cooling temperature may be adjusted by providing a valve 9i for adjusting the supply amount of the cooling medium.

  The pressure in the condenser 3 can be measured with a pressure gauge 17. The pressure gauge 17 can communicate with the condenser 3 by opening the valve 9j to measure the pressure.

  Further, the condenser 3 may be provided with a discharge port 18 for efficiently discharging the inert gas supplied from the evaporator 2, and the inert gas may be discharged to the outside from here. In order to prevent leakage of the organic solvent and non-condensable gas and / or uncondensed gas during condensation, it is necessary to provide a valve 9k on the pipe connected to the discharge port 18.

  Since the organic solvent liquefied by condensing in the condenser 3 is collected at the bottom of the condenser 3, it can be taken out by opening the valve 9 g from the outlet 14 installed at the lower part of the condenser 3.

  The non-condensable gas and / or uncondensed gas that is not condensed in the condenser 3 is supplied to an exhaust means 16 that can discharge the non-condensable gas and / or non-condensed gas out of the system through a pipe from a discharge port 15. The In this case, the system can be sealed by the valve 9h provided in the pipe and other related valves.

  As the exhaust means 16, an air supply means can be preferably used. The air supply means is not particularly limited as long as it has a function of discharging the non-condensable gas and / or uncondensed gas to the outside of the system. For example, a gas flow device such as a vacuum pump, a blower, a compressor, etc. Or it can use suitably according to use environment, such as displacement.

  The exhaust means 16 adjusts the exhaust amount of non-condensable gas and / or uncondensed gas from the exhaust pipe 20 to the outside of the system using a valve 9l. This displacement can be accurately measured by a flow meter 19a disposed downstream of the non-condensable gas trap 25 provided downstream of the valve 9l. Alternatively, when the non-condensable gas is discharged together with the non-condensed gas without using the non-condensed gas trap, the gas analyzer 27 provided on the pipe connected to the discharge port 15 via the valve 9u is not used. The mixed gas containing the condensed gas and the non-condensable gas is sampled, and the concentration of the non-condensable gas mixed with the non-condensable gas is measured and monitored, and the valves 9t and 9r provided at the inlet and outlet of the non-condensable gas trap 25 are closed. When the valve 9s provided in the bypass pipe 26 that bypasses the non-condensable gas trap 25 is opened, the exhaust amount of non-condensable gas and / or uncondensed gas to the outside of the system can be adjusted using the valve 9l as described above. it can. A globe valve or the like is preferably used as the valve 9l. However, when it is particularly necessary to precisely control the discharge, it is preferable to use a valve having a superior flow rate adjusting function such as a needle valve.

In the present invention, while the organic solvent evaporated in the evaporator 2 is condensed in the condenser 3, the exhaust means 16 discharges the amount of non-condensable gas in the system out of the waste electrolyte. It is preferable to control to 10% by mass or less of the initial amount of the electrolyte.
The initial amount of the electrolyte refers to the content of the electrolyte in the waste electrolyte supplied to the evaporator 2 via the valve 9a, and the amount of noncondensable gas discharged from the system in the condenser 3 is the exhaust means. The amount measured by the flow meter 19a connected to 16 corresponds to this.
As described above, the initial amount of the electrolyte can be determined by measuring the concentration in the waste electrolyte solution by a weight method and measuring the lithium content by a method such as mass spectrometry or emission spectrometry. The amount of non-condensable gas and / or uncondensed gas discharged outside the system is measured in a gas state in the flow meter 19a, but it is preferable to use a mass flow meter because the discharge amount can be directly measured by mass. When a volumetric flow meter is used, the discharge amount can be converted into mass from the density and the volumetric flow rate. Although not shown, each pipe is connected using a flexible joint, and the evaporator 2, the condenser 3 and the uncondensed gas trap 25 are directly weighed using a scale, thereby evaporating and non-condensing. The amount of gas and / or uncondensed gas discharged out of the system can also be measured.

In the apparatus shown in FIG. 1, the control means for controlling the discharge amount of the non-condensable gas out of the system is the exhaust means 16, the valve 9 l provided in the exhaust pipe 20 downstream of the exhaust means 16, and the uncondensed gas trap 25. The flow meter 19a may be adjusted by opening and closing the valve 9l while confirming the flow rate of the non-condensable gas with the flow meter 19a.
Needless to say, when the non-condensable gas is discharged out of the system via the non-condensed gas trap 25, it is possible to directly control the discharge amount of the non-condensed gas out of the system.

  As another control means, there is a reflux means for refluxing the non-condensable gas and / or uncondensed gas from the exhaust means 16 to the evaporator 2. Specifically, as shown in FIG. 1, a reflux pipe 21a for connecting the exhaust means 16 and the distiller 2 may be provided. The flow rate can be adjusted by providing the return pipe 21a with a valve 9m. This flow rate can be accurately measured by a flow meter 19b provided downstream of the valve 9m. Furthermore, the system can be hermetically sealed by providing a valve 9q in the vicinity of the inlet of the reflux pipe 21a or the evaporator 2 to be connected. Moreover, what is necessary is just to provide the edge part of the reflux pipe 21a in the evaporator 2 as the supply port 28 of a non-condensable gas and / or a non-condensable gas.

  Further, as another control means, one end of another reflux pipe 21b is connected to the downstream side of the uncondensed gas trap 25, and the other end is connected to the flow meter 19b, whereby only non-condensable gas is refluxed. It is good also as a structure. In this case, adjustment may be performed by opening and closing the valve 9v installed in the reflux pipe 21b while confirming the flow rate of the non-condensable gas with the flow meter 19b.

  As a method for controlling the recirculation amount and / or discharge amount of the non-condensable gas and / or uncondensed gas using the exhaust means 16 in the apparatus 1, the evaporation amount and the evaporation temperature are set to desired values. The temperature and supply amount of the heating medium supplied to the evaporator 2 so as to become the same, and the temperature and supply amount of the cooling medium supplied to the condenser 3 at the same time, and the flow meter 19b installed in the reflux pipe 21a; And / or a method in which the flow rate adjusting valves 9m and 9l installed on the discharge side of the exhaust means 16 are measured while measuring the respective flow rates with a flow meter 19a installed in the exhaust pipe 20, or the discharge side and suction of the exhaust means 16 For example, there may be mentioned a method performed by a flow rate adjusting valve 9n installed in the bypass pipe 22 connected on the side, or a method performed by combining both.

Further, by further providing a gas analyzer 27 provided via a valve 9u on the pipe connected to the discharge port 15 of the condenser 3, the discharge amount of the non-condensable gas can be adjusted more accurately.
Specifically, when only non-condensable gas is discharged out of the system, the gas analyzer 27 measures the concentration of non-condensable gas mixed with uncondensed gas, and the flow meter 19a By opening and closing the valve 9l while checking the flow rate, the amount of non-condensable gas discharged out of the system can be controlled more accurately.
Further, as shown in FIG. 1, even when the mixed gas is directly discharged out of the system using the bypass pipe 26 without closing the valves 9t and 9r and passing through the uncondensed gas trap 25, the gas analyzer 27 does not. While measuring the concentration of the non-condensable gas mixed with the condensed gas and confirming the flow rate of the mixed gas with the flow meter 19a, the valve 9l is opened and closed to move the non-condensable gas contained in the mixed gas out of the system. The amount of discharge can be controlled.

  Further, when the non-condensable gas and / or the non-condensable gas in the condenser 3 is recirculated into the evaporator 2, the suction side is connected to the non-condensed gas and / or the non-condensed gas outlet 15 through the pipe. 16, while the discharge side measures the flow rate of the non-condensed gas and / or uncondensed gas with a flow meter 19 b disposed in the reflux pipe 21 a using a system connected to the reflux pipe 21 a. The valve 9m for adjusting the flow rate is opened or closed, or the valve 9n for adjusting the flow rate installed in the bypass pipe 22 connecting the discharge side and the suction side of the exhaust means 16 is opened and closed, and the discharge gas of the exhaust means 16 is again sucked in The amount of reflux can be controlled by bypassing or both.

Further, an addition means 23 for adding PF ₅ or BF ₃ from the outside of the system may be connected to the reflux pipe 21a.
The adding means 23 is configured to be a valve 9o for adjusting the flow rate of PF ₅ or BF ₃ , a flow meter 19c, and a valve 9p for supplying PF ₅ or BF ₃ in order from the supply side.
In addition, as another aspect of this addition means 23, you may connect to any of the said evaporator 2, the condenser 3, and the connection pipe 4. As shown in FIG.

  Further, a solvent supply means for supplying the evaporator 2 with an organic solvent having a low boiling point separately from the waste electrolyte and / or an organic solvent capable of forming a minimum boiling azeotrope with the high boiling point solvent component in the waste electrolyte. May be provided. As the solvent supply means, a container having a low boiling point organic solvent and / or an organic solvent capable of forming a minimum boiling point azeotrope with the high boiling point solvent component in the waste electrolyte (see FIG. (Not shown) and the supply port 5 of the evaporator 2 may be connected. Alternatively, a new supply port for these solvents may be provided in the evaporator 2.

  There is no particular limitation on the material of each part constituting the apparatus 1 as described above, and steel, aluminum, copper, stainless steel, high alloy steel such as Hastelloy, or composite material obtained by lining such as fluororesin Can be used as appropriate depending on the environment.

  Moreover, what is necessary is just to adjust according to the method of this invention as conditions which operate each part of the said apparatus 1. FIG.

  Moreover, if it is the apparatus 1 shown in FIG. 1, although it is possible to implement all the methods of this invention, according to the control method of the discharge | emission amount of the non-condensable gas in the condenser 3 out of the system, an apparatus The configuration may be selected as appropriate.

For example, if the non-condensable gas and / or uncondensed gas in the condenser is discharged outside the apparatus, the apparatus 1a shown in FIG. 2 and the apparatus 1b shown in FIG. 3 may be used. Comparing the configuration with the apparatus 1 shown in FIG. 1, the apparatus 1a is an apparatus having no reflux means and an adding means for adding PF ₅ or BF ₃ into the system from outside the system, and the apparatus 1b is an apparatus having no reflux means. . Further, if the mixed gas containing the non-condensable gas and the non-condensable gas is discharged, the non-condensable gas trap 25 may be further removed from the device 1a shown in FIG. 2 like the device 1c having the configuration shown in FIG. .

Further, when the non-condensable gas and the non-condensed gas are refluxed, the apparatus 1d shown in FIG. 5 may be used. Compared with the configuration of the apparatus 1 shown in FIG. 1, the apparatus 1d does not have a bypass pipe 22, an uncondensed gas trap 25 that is a means for discharging noncondensable gas and / or uncondensed gas to the outside of the apparatus, a flow meter 19a, and the like. Device.
Further, when only non-condensable gas is refluxed, the apparatus 1e shown in FIG. 6 may be used. Compared with the configuration of the device 1 shown in FIG. 1, the device 1e is a device that does not have the flow meter 19a and the bypass pipes 22 and 26.

  In addition to the devices 1a to 1e, the configurations can be appropriately combined according to the necessary processing.

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these contents, and the devices, materials, temperatures, and the like described in the examples are illustrative examples and are appropriately changed. be able to.

Examples 1-4
In order to verify the effectiveness of the present invention, LiPF ₆ was added to a mixed solvent consisting of 26.8 kg (25 liters) of DMC (dimethyl carbonate) and 24.4 kg (25 liters) of DEC (diethyl carbonate) as a simulated waste electrolyte A. A solution (13.8%) dissolved in 2 kg was prepared. The water content of the simulated waste electrolyte A and the concentration of the insoluble lithium salt were 10 ppm or less.

After purging the inside of the apparatus 1 shown in FIG. 1 with N ₂ , the inside of the system is evacuated with a vacuum pump to a vacuum level of 0.13 kPa, and 10 kg each is sampled from the simulated waste electrolyte A and each of Examples 1 to In order to be used for No. 4, the evaporator 2 was charged through a filter having an opening of 0.5 μm.
The evaporator 2 is connected to the pipe by a flexible joint so that the weight of the evaporator 2 can be measured by a scale.

  Next, a cooling medium of 10 ° C. is supplied to the condenser 3, and simultaneously, a heating medium of 120 ° C. is supplied to the evaporator 2, and the flow rates of the cooling medium and the heating medium so that the temperature of the evaporator 2 becomes 30 ° C. to 100 ° C. The solvent vapor that had been distilled off was condensed in the condenser 3 while being concentrated while heating. At the same time, the exhaust device of the exhaust means 16 is started, the discharge amount adjusting valve 9l is opened, and the mass is measured by the mass flow meter 19a via the uncondensed gas trap 25 (heat exchanger supplied with a cooling medium at −80 ° C.). However, non-condensable gas was discharged out of the system.

When the evaporation amount of the simulated waste electrolyte A in the evaporator 2 reached 7.5 kg, the supply of the heating medium was stopped and the system was cooled to room temperature, and then the supply of the cooling medium was stopped. During this time, the amount of noncondensable gas discharged out of the system was 85 g in Example 1 and 60 g in Example 2. As Example 3, in addition to the above operation, heating and concentration were performed while PF ₅ was continuously added to the evaporator 2 via the PF ₅ addition means 23. The amount of PF ₅ added is 50 g, the amount of non-condensable gas discharged out of the system is 60 g as in Example 2, and the amount of evaporation of the simulated waste electrolyte is 7.5 kg.

Further, in place of the operations of the first embodiment, the second embodiment, and the third embodiment, in the fourth embodiment, the exhaust device of the exhaust means 16 is started, the valve 9m is opened, and the non-condensable gas and the uncondensed gas are detected by the mass flow meter 19b. The mixed gas is recirculated to the evaporator 2 at a rate of 100 g / hour while measuring the flow rate of the mixed gas containing, and discharge of non-condensable gas to the outside of the system and addition of PF ₅ from the outside to the evaporator 2 Did not.

Subsequently, after the inside of the system is brought to atmospheric pressure while being sealed with N ₂ , an atmosphere gas inlet is connected to the upper side of the filter plate, and a filter having an outlet is connected to the take-out port 7 to connect N ₂ as the atmosphere gas. The slurry containing LiPF ₆ precipitated while flowing at a rate of 5 liters / minute was filtered at room temperature for 30 minutes. Next, LiPF ₆ filtered off in an N ₂ atmosphere was transferred to a container, and dried at 100 ° C. for 5 hours while N ₂ was circulated in the container at a rate of 1 liter / minute to obtain LiPF ₆ crystals. It was. In the series of operations, N ₂ having a water content of 10 ppm or less was used. These results are shown in Table 1.

From the results shown in Table 1, LiPF ₆ can be efficiently recovered while suppressing the generation of insoluble lithium salt by adjusting the amount of noncondensable gas discharged outside the system in any of Examples 1 to 4. You can see that

Subsequently, 300 g of LiPF ₆ crystals obtained in Examples 1 to 4 were collected and dissolved in 900 g of anhydrous HF, and the solution was cooled to −20 ° C. and purified by recrystallization. The slurry containing crystals precipitated by recrystallization was transferred to a filter equipped with an inlet of the atmospheric gas above the filter plate and an outlet below, and precipitated while flowing N ₂ as an atmospheric gas at a rate of 500 ml / min. The slurry containing LiPF ₆ was filtered for 10 minutes at room temperature. Next, under a N ₂ atmosphere, the LiPF ₆ separated by filtration was transferred to a container, and dried at 60 ° C. for 5 hours while N ₂ was passed through the container at a rate of 500 ml / min. The results are shown in Table 2.

From the results shown in Table 2, it can be seen that in Examples 1 to 4, LiPF ₆ in which the content of the insoluble lithium salt is remarkably reduced can be obtained using a simple method of recrystallization.

  In addition, although Examples 1-4 performed the process using the apparatus 1 shown in FIG. 1, the apparatus of another structure is also possible. For example, the first and second embodiments may use the apparatus 1a shown in FIG. 2, the third embodiment may use the apparatus 1b shown in FIG. 3, and the fourth embodiment uses the apparatus 1d shown in FIG. May be.

Example 5, Comparative Example 1
After purging the inside of the apparatus shown in FIG. 1 with N ₂ , the inside of the system is evacuated to a vacuum level of 0.13 kPa with a vacuum pump, and 5 kg each from the simulated waste electrolyte A prepared in Examples 1 to 4 above. The aliquots were fed into the evaporator 2 through a filter having an opening of 0.5 μm for use in Example 5 and Comparative Example 1, respectively.
The evaporator 2 is connected to the pipe by a flexible joint so that the weight of the evaporator 2 can be measured by a scale.

  Next, a cooling medium of 10 ° C. is supplied to the condenser 3, and simultaneously, a heating medium of 120 ° C. is supplied to the evaporator 2, and the flow rates of the cooling medium and the heating medium so that the temperature of the evaporator 2 becomes 30 ° C. to 100 ° C. The solvent vapor that had been distilled off was condensed in the condenser 3 while being concentrated while heating. At the same time, the exhaust device of the exhaust means 16 is started, and the gas analyzer 27 and the mass flow meter 19a are used to measure the concentration of the non-condensable gas mixed with the uncondensed gas and the mass of the mixed gas to be exhausted. The amount adjusting valve 9 l was opened and closed, and the mixed gas containing non-condensable gas was discharged out of the system through the bypass pipe 26.

  When the evaporation amount of the simulated waste electrolyte A reached 3.75 kg, the supply of the heating medium was stopped and the system was cooled to room temperature, and then the supply of the cooling medium was stopped. During this time, the amount of noncondensable gas discharged out of the system was 55 g in Example 5 and 105 g in Comparative Example 1.

Subsequently, after the inside of the system is brought to atmospheric pressure while being sealed with N ₂ , an atmosphere gas inlet is connected to the upper side of the filter plate, and a filter having an outlet is connected to the take-out port 7 to connect N ₂ as the atmosphere gas. The slurry containing LiPF ₆ precipitated while flowing at a rate of 2.5 liters / minute was filtered at room temperature for 30 minutes. Then, N transferred to LiPF ₆ was filtered off in a container under ₂ atmosphere, the crystals of LiPF ₆ where the N ₂ in the container was dried for 5 hours at 100 ° C. while circulating at a rate of 0.5 liters / minute Obtained. In these series of operations, N ₂ having a water content of 10 ppm or less was used. These results are shown in Table 3.

From the results of Table 3, in Example 5 in which the discharge amount of non-condensable gas to the outside of the system was suppressed to less than 10%, it is obtained as compared with Comparative Example 1 in which the discharge amount was adjusted to exceed 10%. The amount of LiPF ₆ can be recovered about 1.5 times more, and the concentration of insoluble lithium salt contained in LiPF ₆ is suppressed to about one third, so that there is more high-quality LiPF ₆ It can be said that it has been recovered.
In Comparative Example 1, the yield of the lithium salt for electrolyte crystallized as described above is reduced, and a large amount of insoluble lithium salt is mixed in the electrolyte, and the organic solvent remaining in the evaporator is also remarkable. The crystallized crystals were colored.

  In addition, although Example 5 performed the process using the apparatus 1 shown in FIG. 1, for example, it can implement also using the apparatus 1c shown in FIG.

Example 6
When 7.5 kg of the organic solvent recovered in the condenser 3 and the organic solvent recovered in the uncondensed gas trap 25 in Example 1 was distilled, 4.0 kg of DMC having a purity of 99.9% or more was obtained. Similarly, 2.5 kg of DEC of 99.9% or more was obtained.
Therefore, it can be seen that the recovered organic solvent is of high quality and can be used as a raw material for battery production as it is.

Example 7
As a simulated waste electrolyte B, a solution (12.7%) in which 4.9 kg of LiPF ₆ was dissolved in a mixed solvent composed of 10.7 kg of DMC, 9.8 kg of DEC, and 13.2 kg of EC (ethylene carbonate) was prepared. The water content of the simulated waste electrolyte B and the concentration of the insoluble lithium salt were 10 ppm or less.

After purging the inside of the apparatus 1 shown in FIG. 1 with N ₂ , the inside of the system is evacuated to a vacuum level of 0.13 kPa with a vacuum pump, and 10 kg is separated from the simulated waste electrolyte B, and the opening is 0.5 μm. The evaporator 2 was charged through a filter.
The evaporator 2 is connected to the pipe by a flexible joint so that the weight of the evaporator 2 can be measured by a scale.

  Next, a cooling medium of 20 ° C. is supplied to the condenser 3, and simultaneously, a heating medium of 140 ° C. is supplied to the evaporator 2, and the flow rates of the cooling medium and the heating medium so that the temperature of the evaporator 2 is 60 ° C. to 120 ° C. The solvent vapor that had been distilled off was condensed in the condenser 3 while being concentrated while heating. At the same time, the exhaust device of the exhaust means 16 was started, the discharge amount adjusting valve 9l was opened, and the non-condensable gas was discharged outside the system while measuring the mass with the mass flow meter 19a via the uncondensed gas trap 25.

  Further, since the evaporation was not recognized even when the temperature of the evaporator 2 was adjusted to 120 ° C. from the time when the evaporation amount of the simulated waste electrolyte B reached 5 kg, the evaporation concentration was temporarily stopped, and the inside of the condenser 3 was stopped. After discharging the recovered organic solvent out of the system, 70 kg of ethylene glycol capable of forming a low-boiling azeotrope with EC from the supply port 5 of the waste electrolyte through the valve 9a is continuously supplied to the evaporator 2. Evaporation concentration was started again at an evaporation temperature of 80 ° C. to 120 ° C. while feeding.

  When the total amount of evaporation reached 77.5 kg, the supply of ethylene glycol was stopped, and subsequently 60 kg of toluene was continuously supplied from the waste electrolyte supply port 5 through the valve 9a to the evaporator 2 at 60 ° C. Evaporation concentration was continued at an evaporation temperature of ˜100 ° C. After stopping the supply of toluene, the contents of the evaporator 2 are dried to further solidify until no weight reduction is observed, the supply of the heating medium is stopped, the system is cooled to room temperature, and then the cooling medium The supply of was stopped. During this time, the total amount of noncondensable gas discharged out of the system was 60 g.

When 1.2 kg of the dried crystals in the evaporator 2 were taken out and analyzed, the concentration of the lithium salt which was identified as LiPF ₆ but insoluble in the organic solvent was 1.2% by weight. Subsequently, 300 g was collected from the recovered LiPF ₆ crystals, dissolved in 900 g of anhydrous HF, and recrystallized. The precipitated crystals were filtered and dried at 60 ° C. under N ₂ atmosphere to obtain 135 g of crystals. The concentration of lithium salt insoluble in the organic solvent for electrolyte in the obtained LiPF ₆ crystal was 600 ppm, and no coloration of the crystal was observed. Therefore, it can be said that the obtained LiPF ₆ is of high quality with a low concentration of insoluble lithium salt. In addition, the said refinement | purification operation was performed similarly to the said Examples 1-4.
Moreover, although Example 7 performed the process using the apparatus 1 shown in FIG. 1, it can implement also using the apparatus 1a shown in FIG. 2, for example.

Reference Example 60 mm long, 100 mm wide, 20 μm thick aluminum current collector with lithium cobaltate coated on each side 80 μm of polyvinylidene fluoride as a binder and 60 mm long, 100 mm wide, 15 μm thick copper current collector A mixed solvent comprising 30% by volume of EC, 10% by volume of DMC, 40% by volume of EMC (ethyl methyl carbonate), and 20% by volume of DEC after drying a negative electrode coated with 92.5 μm on one side using polyvinylidene fluoride as a binder on both sides of the body An electrolytic solution in which 1 mol of LiPF ₆ was dissolved in 1 liter was impregnated with 1.33 g of the positive electrode and the negative electrode together. The positive electrode and negative electrode impregnated with the electrolytic solution were transferred to a container, 20 g of DMC was newly added, and 37 kHz ultrasonic waves were applied to the container for 10 minutes. After the application, the positive electrode and the negative electrode were taken out and the solution remaining in the container was analyzed. Table 4 shows the recovery rate of each component extracted in the solution with respect to the analysis result and the amount of impregnation.

  From the results of Table 4, it can be seen that the organic solvent and the lithium salt impregnated in the battery member can be efficiently extracted by immersing the disassembled battery member in an appropriate organic solvent.

1 1a 1b 1c 1d 1e Recovery device 2 Evaporator 3 Condenser 4 Connecting pipe 5 Waste electrolyte supply port 6 Waste electrolyte heating means 7 Crystallized lithium salt outlet 8 Evaporated organic solvent outlet 9 Valve 10 Thermometer 11 Discharge port 12 Supply port for vaporized organic solvent 13 Cooling means for vaporized organic solvent 14 Discharge port for liquefied organic solvent 15 Discharge port for non-condensable gas and / or uncondensed gas 16 Non-condensable gas and / or Or exhaust means for uncondensed gas 17 pressure gauge 18 outlet 19 flow meter 20 exhaust pipe 21a reflux pipe 21b reflux pipe 22 bypass pipe 23 PF ₅ or BF ₃ addition means 24 inert gas supply port 25 uncondensed gas trap 26 Bypass pipe 27 Gas analyzer 28 Non-condensable gas and / or uncondensed gas supply port

Claims (11)

A waste electrolyte containing an organic solvent and a lithium salt as an electrolyte of a lithium battery and / or a lithium ion battery is heated and concentrated in an evaporator to crystallize the lithium salt, and at the same time, evaporated in the evaporator in a condenser. When the collected organic solvent is condensed and recovered,
The evaporator and the condenser are communicated to form a single sealable system,
The organic solvent evaporated by heating the waste electrolyte in the evaporator and evaporating the organic solvent while controlling the discharge amount of the non-condensable gas in the condenser to the outside of the system. A method for simultaneously recovering a lithium salt for an electrolyte and an organic solvent from a waste electrolyte solution characterized by condensing water.   2. The lithium salt for electrolyte and the organic material from the waste electrolyte solution according to claim 1, wherein the discharge amount of the non-condensable gas in the condenser is controlled to 10% by mass or less of the initial amount of the electrolyte in the waste electrolyte solution. A method of simultaneously collecting the solvent.   The method for simultaneously recovering an electrolyte lithium salt and an organic solvent from a waste electrolyte solution according to claim 1 or 2, wherein the condenser is provided with an exhaust means capable of discharging non-condensable gas and / or uncondensed gas out of the system. .   4. The method for simultaneously recovering an electrolyte lithium salt and an organic solvent from a waste electrolyte solution according to claim 3, further comprising means for capturing uncondensed gas and extracting non-condensable gas in the exhaust means.   The method for simultaneously recovering a lithium salt for an electrolyte and an organic solvent from a waste electrolyte solution according to any one of claims 1 to 4, wherein uncondensed gas and / or uncondensed gas in the condenser is refluxed into the evaporator. The lithium salt for electrolyte from the waste electrolyte solution according to any one of claims 1 to 5, wherein the lithium salt is LiPF ₆ or LiBF ₄ and PF ₅ or BF ₃ is added to the system from outside the system. A method of simultaneously recovering an organic solvent.   Disposing the used lithium battery and / or lithium ion battery after discharging the used lithium battery and / or the battery member containing and / or adhering an electrolyte solution containing at least an organic solvent and an electrolyte lithium salt, It is a liquid obtained by adding the organic solvent which does not contain the said lithium salt for electrolytes to a battery member, and extracting the said electrolyte solution in this organic solvent, The lithium for electrolytes from the waste electrolyte solution in any one of Claims 1-6 A method of simultaneously recovering salt and organic solvent.   The waste electrolysis according to any one of claims 1 to 7, wherein a low boiling organic solvent and / or an organic solvent capable of forming a minimum boiling azeotrope with a high boiling solvent component in the waste electrolyte is added to the evaporator. A method of simultaneously recovering a lithium salt for electrolyte and an organic solvent from a liquid. An evaporator that heats a waste electrolyte containing an organic solvent and a lithium salt that is an electrolyte of a lithium battery and / or a lithium ion battery to evaporate the organic solvent and crystallize the lithium salt;
A condenser for condensing and recovering the organic solvent evaporated in the evaporator;
A connecting pipe that connects the evaporator and the condenser to form a single sealable system;
The condenser has exhaust means capable of discharging non-condensable gas and / or uncondensed gas in the condenser to the outside of the system;
Waste electrolysis characterized by having control means for controlling the discharge amount of non-condensable gas in the system to the outside by the exhaust means while condensing the organic solvent evaporated in the evaporator in the condenser A device that simultaneously recovers lithium salt for electrolyte and organic solvent from the liquid.   The apparatus for simultaneously recovering an electrolyte lithium salt and an organic solvent from a waste electrolyte solution according to claim 9, further comprising means for capturing uncondensed gas and extracting non-condensable gas in the exhaust means. A reflux means for refluxing non-condensable gas and / or uncondensed gas in the condenser into the evaporator;
An adding means for adding PF ₅ or BF ₃ into the system from outside the system;
The apparatus further comprises any one or more of solvent supply means for supplying the evaporator with a low boiling point organic solvent and / or an organic solvent capable of forming a minimum boiling point azeotrope with the high boiling point solvent component in the waste electrolyte. Item 11. An apparatus for simultaneously recovering a lithium salt for electrolyte and an organic solvent from the waste electrolyte solution according to Item 10.

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