JP2012200666A - Li SOLUTION RECOVERY APPARATUS AND Li SOLUTION RECOVERY METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for recovering lithium from a solution obtained by leaching a fired product including a positive electrode material of a lithium ion secondary battery with water, and containing ions of lithium and fluorine, sulfuric acid, etc., by continuously and simultaneously purifying and concentrating lithium.SOLUTION: An electrolytic cell is partitioned between an insoluble anode and a cathode with a plurality of diaphragms to keep concentration differences between cations and anions in the partitioned chambers, and while uniform concentration is kept in each chamber, a concentration gradient of ions is maintained from the anode side to the cathode side. A stock solution is supplied to a chamber near the middle to extract a lithium ion concentrate from a chamber nearest the cathode of high lithium ion concentration, and to discharge an impurity concentrate from a chamber nearest the anode of high impurity ion concentration.

Description

  The present invention relates to a Li solution recovery apparatus and a Li solution recovery method, and relates to an apparatus and method for efficiently recovering concentrated Li ions and the like by purifying and concentrating cations and anions in a liquid by electrolysis. . In particular, the present invention relates to an apparatus and method for purifying and concentrating lithium from a solution obtained by dissolving a fired product containing a positive electrode material of a lithium ion secondary battery with water or an acid.

Lithium-ion secondary batteries are secondary batteries that are lighter, have higher capacity, and have higher electromotive force than conventional lead-acid batteries and nickel-cadmium secondary batteries, and are widely used in mobile devices such as mobile phones and laptop computers. in use.
As a positive electrode material of such a lithium ion secondary battery, for example, lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ) or the like is used, and these include lithium which is a rare valuable material. It is. Therefore, it is desired to recover these valuable substances from the used lithium ion secondary battery and to recycle them as a positive electrode material for the lithium ion secondary battery.

Here, when the positive electrode material of the lithium ion secondary battery is fired, lithium becomes lithium oxide (Li ₂ O), and when this fired product is leached with water, lithium hydroxide (LiOH), in water, lithium ions and hydroxides It is known to elute as ions.
However, when lithium ion secondary battery waste is to be recycled, leaching with water described above elutes fluorine and sulfuric acid as impurities simultaneously with lithium. As the electrolyte, for example, LiPF ₆ is used as the electrolyte. In sulfuric acid, it is considered that S derived from an electrolyte additive such as (CF ₃ SO ₂ ) ₂ NLi and (C ₂ F ₅ SO ₂ ) ₂ NLi is leached as sulfuric acid.
Further, the lithium content is not so much with respect to the weight of the battery or the positive electrode material, and the concentration of the liquid from which lithium is leached is relatively low. For these reasons, a purification step and a concentration step for removing impurities are required, and a more efficient purification and concentration method is required at a lower cost. Moreover, the process which can be refine | purified and concentrated continuously from a viewpoint of industrial utilization is desired.

  As a method for removing and concentrating impurities, for example, in Patent Document 1, a lithium-containing solution in which battery waste is dissolved is filtered, and a solution containing a soluble lithium salt is replaced with a cation exchange membrane in the anode chamber and the cathode chamber. A method of refining using a partitioned electrolytic cell has been proposed. In this method, a lithium-containing solution in which battery waste is dissolved is provided in an anode chamber, lithium ions are selectively electrophoresed into the cathode chamber across a porous cation exchange membrane, and lithium is added to the cathode chamber. It is a technique to concentrate.

  However, in this proposal, it is a process of supplying lithium to the anode chamber and taking it out of the cathode chamber. Therefore, it is possible to separate cations and anions in batch processing, but it is possible to continuously supply liquid. It is not suitable for extraction. In the case of continuous supply, it is necessary to continuously discharge the anion concentrate from the anode side and continuously extract the cation concentrate from the cathode side. However, in this proposal, when the lithium-containing liquid is supplied to the anode chamber, the lithium diffuses and is extracted while the lithium concentration in the anode chamber is increased, and is discharged while the lithium concentration on the discharge side is increased. Lithium recovery rate decreases. Moreover, although it is possible to solve the problem by taking a sufficiently long residence time, a large amount of electric energy is used accordingly, which is not economical. In addition, there is a possibility that a plurality of the proposed tanks may be prepared and repeated several times, but this is not economical because a plurality of electrode plates and electrolytic tanks are required.

In addition, in this proposal, since a cation exchange membrane is used, if the operation is repeated, sufficient contact of the cation (cation) exchange membrane cannot be obtained, and it is necessary to frequently exchange the membrane, which is consumed. In some cases, there is a problem that the cost is high.
In addition, when only concentration is performed without migration, evaporative concentration, for example, can be considered. In addition to requiring a large amount of energy for evaporation, impurities are also concentrated at the same time. There is a problem that a lot is mixed.
There is also a method of performing purification and concentration separately, but since the number of steps becomes two and the equipment increases, and energy is required in each step, the cost naturally increases in this case.

  Therefore, the present situation is that it is desired to provide a method for recovering lithium capable of continuously purifying and concentrating lithium at a low cost from a solution in which lithium is eluted.

Special table 2001-508925

  An object of the present invention is to solve the above-described problems and achieve the following objects. In other words, the present invention provides lithium lithium by purifying and concentrating lithium from a solution containing lithium obtained by leaching a fired product containing a positive electrode material of a lithium ion secondary battery in water, fluorine, sulfuric acid, and the like. It is an object of the present invention to provide an apparatus and method capable of recovering a lysate.

Means for solving the problems are as follows. That is,
In the Li solution recovery apparatus of the present invention, the cation and the anion in the Li dissolution undiluted solution supplied to the electrolytic cell are migrated to the cathode side and the anode side, respectively, by applying a direct current to the electrolytic cell, and the Li concentration is different. A Li solution recovery device for recovering a solution,
The electrolytic cell is partitioned by a liquid-permeable partition and has a Li-dissolved stock solution supply chamber, an anode chamber, and a cathode chamber, and the Li-dissolved stock solution supply chamber is located between the anode chamber and the cathode chamber, An insoluble anode and a cathode are disposed in the chamber and the cathode chamber, respectively.
Supply means for supplying the Li-dissolved stock solution to the Li-dissolved stock solution supply chamber, and recovery means for recovering solutions having different Li concentrations from the anode chamber and the cathode chamber, respectively.

Moreover, the suitable form of the Li solution collection | recovery apparatus of this invention is 1st. WHEREIN: The said electrolytic cell is divided into 5 chambers-10 chambers by the liquid-permeable partition.
Second, the cathode chamber is partitioned into a plurality of cathode chambers by a liquid-permeable partition that is substantially parallel to the liquid-permeable partition that partitions the Li-dissolved stock solution supply chamber and the cathode chamber.
Third, the anode chamber is partitioned into a plurality of anode chambers by a liquid-permeable partition that is substantially parallel to the liquid-permeable partition that partitions the Li-dissolved stock solution supply chamber and the anode chamber.
Fourth, the anion contains at least one of fluorine ion and sulfate ion.
Fifth, the Li dissolution stock solution is a solution obtained by firing a waste lithium ion battery and dissolving lithium as a lithium cation.
Sixth, the air permeability of the liquid-permeable partition wall is 10 to 1000 cm ³ / cm ² · min.

On the other hand, the Li solution recovery method of the present invention uses the above-described Li solution recovery apparatus, supplies a Li dissolution stock solution to the Li dissolution stock solution supply chamber, energizes a direct current to the electrolytic cell, the anode chamber, It is characterized by recovering solutions having different Li concentrations from the cathode chamber.
Preferably, both the supply of the Li dissolution stock solution and the recovery of solutions having different Li concentrations are performed continuously.

  Details of means for solving the above-described problems will be described. When the ions in the liquid are separated and purified by electrophoretic migration, the lithium ions migrate toward the cathode and concentrate in the cathode chamber. Impurities such as fluorine ions and sulfate ions migrate toward the anode and concentrate in the anode chamber. These are natural, but when this operation is carried out continuously, it is simply divided into an electrolytic cell without a liquid-permeable partition wall, or two chambers, a cathode chamber and an anode chamber, with a liquid-permeable partition wall therebetween. In the electrolytic cell, when supply and discharge are repeated continuously, the concentration gradient of cations and anions cannot be maintained and separation is impossible. Therefore, continuous purification and concentration cannot be performed.

  On the other hand, in the present invention, the electrolytic cell is partitioned by a liquid-permeable partition and has a Li-dissolved stock solution supply chamber, an anode chamber, and a cathode chamber, and the Li-dissolved stock solution supply chamber is between the anode chamber and the cathode chamber. By being positioned, the concentration difference between the cation and the anion is maintained in each partitioned chamber, and the concentration gradient of ions can be maintained from the anode side to the cathode side while maintaining a uniform concentration in each chamber. As a result, among the chambers partitioned by the liquid-permeable partition wall, the Li-dissolved stock solution is supplied to a chamber in the vicinity of the middle of the Li-dissolved solution that is close to the lithium-ion concentration. The impurity concentrate is discharged from the anode chamber having high concentrations of fluorine ions and sulfate ions, which are impurities, so that lithium can be continuously purified and concentrated to recover a lithium concentrate having a low impurity concentration. Thereby, purification and concentration of lithium can be performed simultaneously and continuously from a solution containing lithium, fluorine, sulfuric acid and the like obtained by leaching a fired product containing a positive electrode material of a lithium ion secondary battery in water. A lithium recovery method can be provided.

  According to the present invention, conventional problems can be solved, and continuously from a solution containing lithium, fluorine, sulfuric acid and the like obtained by leaching a fired product containing a positive electrode material of a lithium ion secondary battery in water. In addition, a method capable of recovering lithium can be provided by simultaneously performing purification and concentration of lithium.

Example 1 (longitudinal sectional view) of a schematic diagram of an apparatus for purifying and concentrating a lithium solution. Example 2 (transverse view, plan view) of a schematic diagram of an apparatus for purifying and concentrating a lithium solution. The schematic diagram (longitudinal sectional view) which shows the outline of the test method and apparatus of Example 1. FIG. 3 is a graph showing the lithium ion concentration in each chamber of Example 1. 3 is a graph showing the fluorine ion concentration in each chamber of Example 1. 3 is a graph showing the sulfate ion concentration in each chamber of Example 1. The schematic diagram (longitudinal sectional view) which shows the outline of the test method and apparatus of Example 2. FIG. 6 is a graph showing the lithium ion concentration in each chamber of Example 2. 6 is a graph showing the fluorine ion concentration in each chamber of Example 2. 6 is a graph showing the sulfate ion concentration in each chamber of Example 2. The schematic diagram (longitudinal sectional view) which shows the outline of the test method and apparatus of Example 3. FIG. 10 is a graph showing the lithium ion concentration in each chamber of Example 3. 6 is a graph showing the fluorine ion concentration in each chamber of Example 3. 6 is a graph showing the sulfate ion concentration in each chamber of Example 3. The schematic diagram (longitudinal sectional view) which shows the outline of the test method and apparatus of Comparative Example 1. The schematic diagram (longitudinal sectional view) which shows the outline of the test method and apparatus of Comparative Example 2. The graph which shows the lithium ion density | concentration of each chamber of the comparative example 2. FIG. The graph which shows the fluorine ion density | concentration of each chamber of the comparative example 2. FIG. The graph which shows the sulfate ion density | concentration of each chamber of the comparative example 2. FIG. The schematic diagram (longitudinal sectional view) which shows the outline of the test method and apparatus of Comparative Example 3. The graph which shows the lithium ion density | concentration of each chamber of the comparative example 3. 10 is a graph showing the fluorine ion concentration in each chamber of Comparative Example 3. 10 is a graph showing the sulfate ion concentration in each chamber of Comparative Example 3. The schematic diagram (longitudinal sectional view) which shows the outline of the test method and apparatus of Comparative Example 4. The graph which shows the lithium ion density | concentration of each chamber of the comparative example 4. 10 is a graph showing the fluorine ion concentration in each chamber of Comparative Example 4. 10 is a graph showing the sulfate ion concentration in each chamber of Comparative Example 4.

  In the Li solution recovery apparatus of the present invention, a lithium ion solution obtained by leaching lithium with water from a fired product containing a positive electrode material of a lithium ion secondary battery can be used as a Li solution solution.

As a method of continuously purifying and concentrating lithium, a direct current is applied to the electrode using an electrolytic cell that is divided into three or more chambers by a liquid-permeable partition and provided with a cathode and an anode as described above. As long as the lithium can be purified and concentrated simultaneously and continuously from the solution in which lithium is dissolved, there is no particular limitation, and it can be appropriately selected according to the purpose.
For example, a lithium refining and concentrating tank having an anode and a cathode uses a tank in which the anode and the cathode are partitioned by a liquid-permeable partition in three or more chambers, and the cathode and the cathode are energized between the anode and the cathode. It is preferable to concentrate the lithium ions in the cathode chamber in which is present.
When refining and concentrating lithium continuously, the Li dissolution stock solution may be supplied to any chamber other than the anode chamber and the cathode chamber of each chamber partitioned by a partition into three or more chambers, Of each chamber partitioned by the liquid-permeable partition, it is preferable to supply the Li-dissolved stock solution to a tank close to the lithium ion concentration of the Li-dissolved stock solution.
The concentrated and purified liquid is preferably extracted from the cathode chamber having a high lithium ion concentration, and the impurity concentrated solution is preferably discharged from the anode chamber having a high fluorine ion and sulfate ion concentration. Thereby, it is possible to continuously purify and concentrate lithium and recover a lithium concentrate having a low impurity concentration.

The kind of the liquid-permeable partition used for separating the anode chamber and the cathode chamber is not particularly limited as long as it can pass lithium ions in the liquid, and can be appropriately selected according to the purpose. It is preferable that F ⁻ and SO ₄ ²⁻ can pass through on the anode side. For example, a filter cloth, an ion exchange membrane, an RO membrane, an NF membrane, an ultrafiltration membrane, a microfiltration membrane, an ion exchange resin, and the like can be mentioned. A filter cloth is preferable from the viewpoint of low cost.

The material of the filter cloth is not particularly limited, and examples thereof include polypropylene and polyethylene, but it is preferable that the liquid is made of polypropylene having resistance to both acidity and alkalinity.
The weaving method of the filter cloth is not particularly limited, and examples thereof include double weave, satin weave and twill weave. Since the air permeability of the filter cloth varies depending on the weaving method, fiber material, and thickness, the air permeability may be appropriate.
The air permeability of the liquid-permeable partition wall is preferably 10 to 1000 cm ³ / cm ² · min, more preferably 20 to 600 cm ³ / cm ² · min. If the air permeability is lower than 10 cm ³ / cm ² · min, the electrolysis voltage increases and the cost of purification increases. If the air permeability is higher than 1000 cm ³ / cm ² · min, ions in water easily diffuse and the concentration difference between the chambers It becomes difficult to maintain.

There is no restriction | limiting in particular as a shape of the apparatus which refine | purifies and concentrates the said lithium simultaneously, According to the objective, it can select suitably. For example, as shown in FIG. 1, it is preferable to have a cathode and an anode in an electrolytic cell, separate the anode and the cathode with a partition, and further partition the anode chamber and the cathode chamber with a gas-permeable partition.
Moreover, as shown in FIG. 2, it can implement also in the structure where an anode or a cathode is located in the center of a tank, an air permeable partition is arrange | positioned on a concentric circle, and the inside of a tank or the tank itself becomes a counter electrode.

  As described above, the electrolytic cell is divided into three or more chambers by the air-permeable partition. It is preferable to partition into 3 to 100 rooms, more preferably 5 to 10 rooms. If the number of chambers is less than three, when the liquid supply and discharge are repeated continuously, the concentration gradient of cations and anions cannot be maintained and separation becomes impossible. Therefore, it may not be possible to carry out purification and concentration continuously. When the number of chambers is 100 or more, the electrolysis voltage increases and the purification cost may increase.

  When the lithium is purified and concentrated at the same time, the liquidity of the solution in which lithium, fluorine, and sulfuric acid are dissolved is preferably pH 5 to 14, more preferably alkaline, and even more preferably pH 8 to 13.5. It is. When the pH is lower than 5, when aluminum is present as an impurity, aluminum is present as a cation, so that it may migrate to the cathode in the same manner as lithium ions and separation may be insufficient. On the other hand, if the pH is higher than 14, the device may be corroded.

-Positive electrode material for lithium ion secondary battery-
As the positive electrode material of a lithium ion secondary battery is not particularly limited, can be appropriately selected depending on the purpose, for example, lithium cobalt oxide (LiCoO _2), and lithium manganate (LiMn ₂ O ₄₎ be used as the it can.
As the positive electrode material, it is preferable to use a material obtained from a used lithium ion secondary battery because lithium can be recycled.

-Firing product containing positive electrode material for lithium ion secondary battery used as raw material-
It is preferable to use a fired product containing a positive electrode material of a lithium ion secondary battery as a lithium recycling raw material of the lithium ion secondary battery using the purification and concentration method of the present invention. There is no restriction | limiting in particular as an atmosphere which bakes this baked material, According to baking conditions etc., it can select suitably, For example, an air atmosphere, an oxidizing atmosphere, an inert atmosphere, a reducing atmosphere etc. are mentioned. The atmosphere is preferably aerated during firing.
Here, the air atmosphere means an atmosphere using air (air) of 21 vol% oxygen and 78 vol% nitrogen.
The oxidizing atmosphere means an atmosphere containing 1 vol% to 21 vol% of oxygen in an inert atmosphere such as nitrogen or argon, and an atmosphere containing 1 vol% to 5 vol% of oxygen is preferable.
The inert atmosphere means an atmosphere made of nitrogen or argon.
The reducing atmosphere means an atmosphere containing CO, H ₂ , H ₂ S, SO ₂ and the like in an inert atmosphere such as nitrogen or argon.

The firing is preferably performed using a firing furnace. There is no restriction | limiting in particular as said baking furnace, According to the objective, it can select suitably, For example, batch type furnaces, such as a rotary kiln, a fluidized bed furnace, a tunnel furnace, a muffle, a cupola, a stalker furnace, etc. are mentioned. Since firing can be performed even in an air atmosphere, a commonly used firing furnace such as a rotary kiln furnace can be used, and the selection range of the firing furnace is widened.
The firing temperature is not particularly limited and may be appropriately selected depending on the purpose. It is more preferably 400 ° C. or higher in an air atmosphere, 600 ° C. or higher in an inert atmosphere, and 400 ° C. or higher in an oxidizing atmosphere. The upper limit temperature is preferably 1200 ° C. or lower.
If the firing temperature is less than 400 ° C., for example, the crystal structure of the positive electrode of the lithium ion secondary battery cannot be destroyed, so lithium may not be eluted. If it exceeds 1,200 ° C., a large amount of energy is required. In addition, since the fired product is sintered, a pulverization step may be required.

The current density applied between the electrodes when the lithium is simultaneously purified and concentrated is preferably 5 A / m ² to 500 A / m ^2, more preferably 10 A / m ² to 300 A / m ² . If it is lower than 5 A / m ^2, it may take a long time to migrate lithium ions, and if it is 500 A / m ² or more, a large amount of energy is used for generation of hydrogen and oxygen, so that efficiency is lowered.

  The distance between the anode and the cathode when the lithium is purified and concentrated at the same time can be arbitrarily set as long as the distance is from 0.5 cm to 100 cm. 1 cm to 50 cm is more preferable. If the length is shorter than 0.5 cm, there is a risk of short-circuiting due to a short circuit. If the length is longer than 100 cm, the voltage increases and the power consumption increases, which is not economical.

(Recovery method of lithium carbonate)
When recovering lithium carbonate, a liquid concentrated and purified by the method of simultaneously purifying and concentrating the lithium of the present invention can be used.
There is no restriction | limiting in particular as the collection method of the said lithium carbonate, According to the objective, it can select suitably, For example, (1) The method of drying naturally, (2) The method of drying and solidifying by heating, (3) Carbonic acid And (4) precipitation and separation with carbonate, and the like can be recovered as lithium carbonate.
In particular, the method (3) is preferred, and the liquid purified and concentrated by the method of the present invention can be precipitated as lithium carbonate by blowing carbonic acid into a pH range of 5-9. When the pH is less than 5, the amount of precipitated lithium carbonate may decrease, and when the pH exceeds 9, carbonic acid may be insufficient. Moreover, since lithium carbonate has lower solubility in water at higher temperatures, it is desirable to heat the lithium carbonate. The heating temperature is preferably from 80 ° C to 100 ° C. If the temperature is lower than 80 ° C., the yield of lithium carbonate decreases.

  The lithium recovery method uses a solution obtained by leaching lithium from a fired product containing a positive electrode material of a lithium ion secondary battery as a stock solution, and separates impurities in the solution using the purification and concentration method of the present invention. In the step of crystallizing lithium carbonate from the concentrated liquid obtained, lithium can be efficiently recovered, and the lithium ion secondary battery can be recycled.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Separation of lithium battery positive electrode material>
Obtained by firing a commercially available lithium ion secondary battery for personal computers (a ternary positive electrode material using a positive electrode made of cobalt, manganese, nickel oxide and graphite for the negative electrode) at 700 ° C. in an air atmosphere for 1 hour. The fired product was crushed with a hammer crusher. The crushed material is screened with a test sieve. A positive electrode material powder having a sieve opening of 1 mm or less was obtained. Firing was performed in a box furnace (manufactured by KOYO LINDBERG).

<Preparation of lithium solution>
30 kg of the obtained positive electrode material was immersed in 100 L of water to obtain a solution in which lithium ions were dissolved. The composition of the solution is shown in Table 1.

<Analysis of lithium in solution>
About the lithium density | concentration in a solution, it analyzed with the high frequency plasma emission spectroscopic analyzer (Nippon Jarrell-Ash Co., Ltd. product, iCAP-6300), and computed lithium density | concentration.

<Analysis of fluorine and sulfuric acid in solution>
The concentration of fluorine and sulfuric acid in the solution was analyzed by ion chromatography (manufactured by Dionex) and the concentration was calculated.

[Example 1]
Using a test electrolytic cell for refining and concentrating lithium as shown in FIG. 3, a continuous system test for refining and concentrating was performed as follows.
A polypropylene filter cloth (Shikishima Canvas Co., Ltd., P91C) was used as the liquid-permeable partition wall for separating the anode and the cathode. Using four membranes, the electrolytic cell was divided into five chambers, and the chambers at both ends were made the cathode chamber and the anode chamber, respectively, and the respective electrodes were arranged. The anode was an electrode in which titanium oxide was coated with platinum, and the cathode was a titanium electrode. The distance between the electrodes was 24 cm.
First, 25 liters (referred to as 1) of stock solution was poured into the Li dissolution stock solution supply chamber of the electrolytic cell, and a 5 A direct current (voltage was 8 volts) was passed between the electrodes for 16 hours, and each of the compartments separated by a diaphragm was used. A lithium ion concentration gradient was created in the chamber. Thereafter, the stock solution was changed to No. 1 shown in FIG. No. 3 in the cathode chamber was supplied to the third chamber at 26 ml / min. The lithium concentrate was collected from chamber 5 at 13 ml / min. The operation of discharging a concentrated solution of fluorine and sulfate ions from one chamber out of the system at 13 ml / min was continuously performed. The liquid residence time in the tank at this time was 16 hours.
The lithium, fluorine, and sulfate ion concentrations in each chamber over time were recorded. The results are shown in Table 2. In addition, the No. of each room. No. shown in FIG. The notation.

  Regarding the results in Table 2, the ion concentrations of lithium, fluorine, and sulfuric acid in each chamber over time are shown in FIGS. 4 to 6, respectively. No. on the anode side even after 48 hours had passed since the start of continuous flow. No. 1 on the room and cathode side. The difference in ion concentration in the five chambers was maintained. This indicates that the concentrated liquid can be obtained with a constant liquid quality, and the liquid can be continuously supplied and extracted.

[Example 2]
Using a test electrolytic cell for purification and concentration of lithium shown in FIG. 7, a continuous system test for purification and concentration was performed as follows. As shown in FIG. 7, six diaphragms were used as the liquid-permeable partition walls, and seven chambers partitioned by the diaphragm were used. No. 4 for recovery of lithium concentrate. The test was performed under the same conditions as in Example 1 except that the number of chambers was 7 (cathode chamber).
The results are shown in Table 3. In addition, the No. of each room. No. shown in FIG. The notation.

  Regarding the results in Table 3, the ion concentrations of lithium, fluorine, and sulfuric acid in each chamber over time are shown in FIGS. Even when 48 hours passed from the start of continuous flow, the ion and anode ion concentration gradient was maintained. This indicates that the concentrated liquid can be obtained with a constant liquid quality, and the liquid can be continuously supplied and extracted.

[Example 3]
Using a test electrolytic cell for purification and concentration of lithium shown in FIG. 11, a continuous system test for purification and concentration was performed as follows. The electrolytic cell partition was tested under the same conditions as in Example 1 except that the electrolytic cell was divided into three chambers using two liquid-permeable partition membranes. The ion concentration of lithium, fluorine and sulfuric acid in each chamber over time was recorded. The results are shown in Table 4. In addition, the No. of each room. No. shown in FIG. The notation.

  Regarding the results of Table 4, the ion concentrations of lithium, fluorine, and sulfuric acid in each chamber over time are shown in FIGS. At the time of water flow for 8 hours, which is the initial stage of liquid flow, No. Although the lithium was concentrated in the third chamber (cathode chamber) and the fluorine and sulfate ions were concentrated in the No. 1 chamber (anode chamber), the concentration difference was small compared to Examples 1 and 2. Furthermore, when the continuous liquid flow was continued, the concentration gradient that had been formed disappeared with time, and each chamber gradually approached the concentration close to the stock solution. From this, it can be seen that there is an effect of obtaining the concentrated liquid with a constant liquid quality, but the effect is less than in Examples 1 and 2.

[Comparative Example 1]
Using a test electrolytic cell for refining and concentrating lithium shown in FIG. 15, a continuous system test for refining and concentrating was performed as follows. The test was performed under the same conditions as in Example 1 except that the liquid-permeable partition was not used and the cathode chamber and the anode chamber were not partitioned by the diaphragm.
The results are shown in Table 5.

  From the results in Table 5, it was confirmed that when the cathode chamber and the anode chamber were not partitioned by the liquid-permeable partition wall, the concentration gradient could not be made and concentration and purification could not be performed.

[Comparative Example 2]
Using a test electrolytic cell for purification and concentration of lithium shown in FIG. 16, a continuous system test for purification and concentration was performed as follows. As shown in FIG. 16, one diaphragm is used as the liquid-permeable partition, and two rooms are separated by the diaphragm. No. 1, no recovery of lithium concentrate. The test was performed under the same conditions as in Example 1 except that the number of chambers was 2 (cathode chamber).
The results are shown in Table 6. In addition, the No. of each room. No. shown in FIG. The notation.

  As for the results in Table 6, the ion concentrations of lithium, fluorine, and sulfuric acid in each chamber over time are shown in FIGS. As time elapses from the start of continuous flow, the ion concentration gradient in the cathode chamber and the anode chamber decreases. In particular, with regard to lithium as a recovery target, the concentration gradient between the cathode chamber and the anode chamber was greatly reduced as compared with Examples 1 to 3 at 48 hours after the start of continuous flow. This indicates that the concentrated solution cannot be obtained continuously with a constant liquid quality.

[Comparative Example 3]
Using a test electrolytic cell for purification and concentration of lithium shown in FIG. 20, a continuous system test for purification and concentration was performed as follows. No. of stock solution supply. The test was performed under the same conditions as in Comparative Example 2 except that the number of rooms was two.
The results are shown in Table 7. In addition, the No. of each room. No. shown in FIG. The notation.

  With respect to the results in Table 7, the ion concentrations of lithium, fluorine, and sulfuric acid in each chamber over time are shown in FIGS. As time elapses from the start of continuous flow, the ion concentration gradient in the cathode chamber and the anode chamber decreases. In particular, with regard to lithium as a recovery target, the concentration gradient between the cathode chamber and the anode chamber was greatly reduced as compared with Examples 1 to 3 at 48 hours after the start of continuous flow. This indicates that the concentrated solution cannot be obtained continuously with a constant liquid quality.

[Comparative Example 4]
Using a test electrolytic cell for purification and concentration of lithium shown in FIG. 24, a continuous system test for purification and concentration was performed as follows. First, two electrolytic tanks having the same structure as that used in Comparative Examples 2 and 3 and having a half capacity were prepared and arranged in series so as to allow continuous water flow. Inject 12.5 liters of stock solution into the Li dissolution stock solution supply chamber of each electrolytic cell, energize a 2.5 A direct current (voltage is 8 volts) between the two electrodes for 16 hours, and put lithium in each chamber partitioned by a diaphragm. An ion concentration gradient was created. Thereafter, the stock solution was changed to No. 1 shown in FIG. No. 1 which is a cathode chamber is supplied to one chamber at 26 ml / min. The concentrated solution obtained by recovering the lithium concentrated solution from the second chamber at 19.5 ml / min was used as the No. 2 anode chamber in the second tank. No. 3 which is supplied to the third chamber and is the anode chamber of the first tank. The concentrated solution of fluorine and sulfate ions from the first chamber was 6.5 ml / min. The operation of discharging the concentrated liquid of fluorine and sulfate ions from the four chambers out of the 13 ml / min system was continuously performed. The liquid residence time in the tank at this time was 8 hours in each tank. The power consumption of the apparatus of Comparative Example 4 was almost the same as in Example 1, and the recovered amount of the concentrated liquid was also the same.
The lithium, fluorine, and sulfate ion concentrations in each chamber over time were recorded. The results are shown in Table 8. In addition, the No. of each room. No. shown in FIG. The notation.

  As for the results in Table 8, the ion concentrations of lithium, fluorine, and sulfuric acid in each chamber over time are shown in FIGS. 25 to 27, respectively. As time elapses from the start of continuous liquid flow, both the ion concentration gradients in the cathode chamber and the anode chamber decrease. In particular, with respect to lithium that is the object of recovery, No. was obtained at 48 hours after the start of continuous liquid flow. 1 chamber (cathode chamber) and The concentration gradient in the four chambers (anode chamber) was greatly reduced as compared with Examples 1 to 3. In the apparatus shown in Comparative Example 4, the number of partition walls separating the tank for supplying the stock solution and the tank for recovering the lithium concentrate is the same as in Example 1, and the power consumption is the same. However, it turns out that the concentration efficiency is good. Furthermore, the structure as in Comparative Example 4 is not economical because it requires a plurality of devices such as a rectifier for flowing current, a pump for feeding liquid, and electrodes.

  The recovery method for continuously purifying and concentrating lithium according to the present invention is capable of purifying and concentrating lithium more efficiently than conventional methods, and enables continuous treatment that could not be realized in the past. In addition, the lithium ion secondary battery can be reused by an efficient recovery method.

1 anode 2 cathode 3 diaphragm (liquid-permeable partition)
4 Electrolyzer body 5 DC power supply

Claims (9)

A Li solution recovery device that recovers solutions with different Li concentrations by causing the cations and anions in the Li dissolution stock solution supplied to the electrolytic cell to migrate to the cathode side and the anode side by direct current flow to the electrolytic cell, respectively. There,
The electrolytic cell is partitioned by a liquid-permeable partition and has a Li-dissolved stock solution supply chamber, an anode chamber, and a cathode chamber, and the Li-dissolved stock solution supply chamber is located between the anode chamber and the cathode chamber, An insoluble anode and a cathode are disposed in the chamber and the cathode chamber, respectively.
A Li solution recovery apparatus comprising: a supply unit that supplies the Li dissolution stock solution to the Li dissolution stock solution supply chamber; and a recovery unit that recovers solutions having different Li concentrations from the anode chamber and the cathode chamber, respectively.   The Li solution recovery apparatus according to claim 1, wherein the electrolytic cell is partitioned into 5 to 10 chambers by the liquid-permeable partition wall.   3. The Li solution recovery according to claim 1, wherein the cathode chamber is partitioned into a plurality of cathode chambers by a liquid-permeable partition that is substantially parallel to the liquid-permeable partition that partitions the Li-dissolved stock solution supply chamber and the cathode chamber. apparatus.   4. The anode chamber according to claim 1, wherein the anode chamber is partitioned into a plurality of anode chambers by a liquid-permeable partition that is substantially parallel to the liquid-permeable partition that partitions the Li-dissolved stock solution supply chamber and the anode chamber. Li solution recovery device.   The Li solution collection | recovery apparatus in any one of Claims 1-4 in which the said anion contains at least 1 type of a fluorine ion and a sulfate ion.   The Li solution recovery apparatus according to any one of claims 1 to 5, wherein the Li dissolution stock solution is a solution obtained by firing a waste lithium ion battery and dissolving lithium as a lithium cation. The Li solution collection | recovery apparatus in any one of Claims 1-6 whose air permeability of the said liquid-permeable partition is 10-1000 cm < ³ > / cm < ² > * min.   Using the Li solution recovery apparatus according to any one of claims 1 to 7, a Li-dissolved stock solution is supplied to the Li-dissolved stock solution supply chamber, a direct current is passed through the electrolytic cell, and the anode chamber and the cathode Li solution recovery method for recovering solutions having different Li concentrations from the chamber.   Using the Li solution recovery apparatus according to any one of claims 1 to 7, the Li dissolution stock solution is continuously supplied to the Li dissolution stock solution supply chamber, a direct current is supplied to the electrolytic cell, and the anode chamber A Li solution recovery method for continuously recovering solutions having different Li concentrations from the cathode chamber.

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