JP5872788B2 - Lithium carbonate manufacturing method and lithium carbonate manufacturing apparatus - Google Patents

Description

  The present invention relates to a lithium carbonate production method and a lithium carbonate production apparatus capable of efficiently producing high purity lithium carbonate.

  Lithium carbonate is used as a raw material for lithium secondary batteries and electrolyte materials used in blending materials such as heat-resistant glass and optical glass, ceramic materials, mobile phones, and laptop computers.

  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. Mobile devices such as mobile phones and notebook computers It is widely used in secondary batteries for electric vehicles, and the demand is expected to increase in the future.

As the positive electrode material of such a lithium ion secondary battery, for example, lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), and the like are used, and lithium, which is a rare valuable substance, is used. include. 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.

  In general, lithium carbonate is produced by crystallization, but since it is a rare metal, a high recovery rate in the production process is desired. Furthermore, as described above, in applications as electronic materials, impurities may deteriorate electrical characteristics, and higher purity lithium carbonate is required.

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 has been understood by the present inventors' previous studies that ions are eluted as ions.
However, when waste of lithium ion secondary batteries is to be recycled, there is a problem that fluorine and sulfuric acid are eluted as impurities simultaneously with lithium due to the above-described leaching with water. As the electrolyte, for example, LiPF ₆ is used as the electrolyte, which is attributed to this. It is considered that sulfuric acid is leached as S derived from electrolyte additives such as (CF ₃ SO ₂ ) ₂ NLi becomes sulfuric acid. In addition, the lithium content is not so large 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, when recovering lithium in the liquid as lithium carbonate, a recovery method with higher yield and less impurities is desired.

As a conventional method for recovering lithium carbonate, for example, Patent Document 1 discloses a method for improving the yield of lithium carbonate by heating an aqueous solution containing lithium by crystallization to 90 ° C. or more and blowing carbon dioxide gas. Proposed. Patent Document 2 proposes a method of increasing the purity of lithium carbonate by heating a lithium-containing aqueous solution separated by filtration to 30 ° C. to 100 ° C. and blowing carbon dioxide gas.
However, these proposed methods make use of the fact that the solubility of lithium carbonate decreases as the temperature rises. If the lithium concentration in the liquid is lower than the solubility of lithium carbonate, lithium can be recovered. There is a problem that you can not. Further, in order to increase the lithium concentration in the liquid, a method of concentrating by a technique such as evaporation to increase the lithium concentration of the solution is conceivable. In addition, when recycling as described above is performed using a method of concentrating the lithium concentration in the liquid, impurities such as fluorine and sulfuric acid eluted simultaneously with lithium contained in the lithium ion secondary battery are also concentrated at the same time. As a result, there arises a problem that the purity of the recovered product is lowered.
From the viewpoint of recycling, lithium is desired to be recycled because the production country is overseas and the production scale is small and there is a supply risk in response to the recent increase in usage. On the other hand, the price of lithium carbonate is not as high as about 500 yen per kg. Therefore, it is preferable that the recycling process is simple, low cost, and high recovery rate.

  Accordingly, the present situation is that it is desired to provide a lithium carbonate production method and a lithium carbonate production apparatus capable of efficiently producing high purity lithium carbonate from a solution containing lithium ions and carbonate ions.

Japanese Patent Laid-Open No. 61-251511 JP-A-2005-26088

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention can efficiently produce high purity lithium carbonate from a solution containing lithium ions and carbonate ions, and in particular, lithium obtained by leaching a fired product containing a positive electrode material of a lithium ion secondary battery in water. Another object of the present invention is to provide a lithium carbonate production method and a lithium carbonate production apparatus capable of producing lithium carbonate with high yield and high purity from a solution containing impurities such as fluorine and sulfuric acid.

Means for solving the problems are as follows. That is,
<1> A method for producing lithium carbonate, characterized in that lithium carbonate is precipitated by energizing a solution containing lithium ions and carbonate ions.
<2> The method for producing lithium carbonate according to <1>, wherein energization is performed at a current density of 0.5 A / dm ^{2 to} 50 A / dm ² .
<3> The method for producing lithium carbonate according to any one of <1> to <2>, wherein a solution containing lithium ions and carbonate ions is heated.
<4> The method for producing lithium carbonate according to <3>, wherein the heating is performed at a temperature of 70 ° C. or higher.
<5> The method for producing lithium carbonate according to any one of <1> to <4>, wherein carbon dioxide is supplied to a solution containing at least lithium ions to obtain a solution containing lithium ions and carbonate ions.
<6> The method for producing lithium carbonate according to <5>, wherein the solution containing at least lithium ions is a liquid obtained by calcining a waste lithium ion secondary battery and leaching lithium into water.
<7> The method for producing lithium carbonate according to any one of <1> to <6>, wherein the precipitated lithium carbonate is solid-liquid separated.
<8> having an energizing means for energizing a solution containing lithium ions and carbonate ions to precipitate lithium carbonate;
A crystallization tank for storing a solution containing lithium ions and carbonate ions;
An apparatus for producing lithium carbonate, comprising: a cathode and an anode for energizing a solution containing the lithium ions and carbonate ions.
<9> The lithium carbonate production apparatus according to <8>, further including a heating unit that heats a solution containing lithium ions and carbonate ions.
<10> The lithium carbonate production apparatus according to <9>, wherein the cathode is integrated with the heating unit.
<11> The lithium carbonate production apparatus according to any one of <8> to <10>, further including carbon dioxide supply means for supplying carbon dioxide to a solution containing at least lithium ions.
<12> The lithium carbonate production apparatus according to any one of <8> to <11>, wherein the cathode is an inner wall of a crystallization tank.
<13> The lithium carbonate production apparatus according to any one of <8> to <12>, further including a separation unit configured to solid-liquid separate lithium carbonate deposited in the vicinity of the cathode and the cathode.
<14> The production of lithium carbonate according to any one of <11> to <13>, wherein the solution containing at least lithium ions is a liquid obtained by calcining a waste lithium ion secondary battery and leaching lithium into water. Device.

  According to the present invention, conventional problems can be solved, high-purity lithium carbonate can be efficiently produced from a solution containing lithium ions and carbonate ions, and in particular, a fired product containing a positive electrode material for a lithium ion secondary battery. To provide a lithium carbonate production method and a lithium carbonate production apparatus capable of producing lithium carbonate with high yield and high purity from a solution containing impurities such as fluorine and sulfuric acid obtained by leaching water into water Can do.

FIG. 1A is a top view showing an example of the lithium carbonate production apparatus of the present invention. FIG. 1B is a side view showing an example of the lithium carbonate production apparatus of the present invention. FIG. 2 is a graph showing changes in lithium concentration in the liquid over time in Example 1 and Comparative Example 1. FIG. 3 is a graph showing changes in lithium concentration in the liquid over time in Example 3 and Comparative Example 2.

(Lithium carbonate manufacturing method and lithium carbonate manufacturing apparatus)
The method for producing lithium carbonate of the present invention includes an energizing step of energizing a solution containing lithium ions and carbonate ions, preferably a heating step of heating a solution containing lithium ions and carbonate ions, and at least containing lithium ions. A carbon dioxide supply step of supplying carbon dioxide to the solution to obtain a solution containing lithium ions and carbonate ions, and further including other steps as necessary. Each of these steps may be performed before and after, may be performed simultaneously, may be performed repeatedly, or may be performed intermittently.
The lithium carbonate production apparatus of the present invention has an energization means, preferably a heating means and a carbon dioxide supply means, and further comprises other means as required.
Hereinafter, the lithium carbonate production method and lithium carbonate production apparatus of the present invention will be described in detail.

<Energization process and energization means>
The energizing step is a step of energizing a solution containing lithium ions and carbonate ions, and is performed by energizing means.
The energizing means includes a crystallization tank for storing a solution containing the lithium ions and carbonate ions, and a cathode and an anode for energizing the solution containing the lithium ions and carbonate ions, and other if necessary. The member is provided.

-Solution containing lithium ions and carbonate ions-
The solution containing lithium ions and carbonate ions is not particularly limited as long as it contains lithium ions and carbonate ions at a concentration at which lithium carbonate can be deposited by energization, and may be appropriately selected according to the purpose. it can.
The concentration of lithium ions during energization is preferably 1,500 mg / L or more, more preferably 3,000 mg / L or more.
The concentration of carbonate ions during energization is preferably 1,000 mg / L or more, more preferably 1,450 mg / L or more.

  The solution containing lithium ions and carbonate ions is not particularly limited as long as it contains lithium ions and carbonate ions, and can be appropriately selected according to the purpose. For example, a solution containing at least lithium ions A solution obtained by supplying carbon dioxide can be suitably used. The supply of carbon dioxide will be described in the carbon dioxide supply step described later.

  The solution containing at least lithium ions is not particularly limited as long as it contains lithium ions, and can be appropriately selected according to the purpose. For example, (i) a positive electrode material of a lithium ion secondary battery is sulfuric acid (Ii) Lithium ion secondary battery positive electrode material after dissolution, cobalt and nickel removed liquid, (iii) Waste lithium ion secondary battery was baked, and lithium was leached into water Liquid, (iv) hot spring water, (v) salt lake water, and the like. Among these, (iii) a liquid obtained by firing a waste lithium ion secondary battery and leaching lithium into water is particularly preferable.

(Iii) A method for preparing a liquid obtained by firing a waste lithium ion secondary battery and leaching lithium in water will be described below.
The positive electrode material of the lithium ion secondary battery in the fired product including the positive electrode material of the lithium ion secondary battery used as a raw material is not particularly limited and can be appropriately selected according to the purpose. However, lithium cobalt oxide (LiCoO ₂ ), And at least one of lithium manganate (LiMn ₂ O ₄ ).
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.

There is no restriction | limiting in particular as an atmosphere which bakes the said baked product, 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% oxygen and 78% nitrogen.
The oxidizing atmosphere means an atmosphere containing 1% by mass to 21% by mass of oxygen in an inert atmosphere such as nitrogen or argon, and an atmosphere containing 1% by mass to 5% by mass 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, for example, 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 1,200 ° C. or lower.
When 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 ions may not be eluted. In addition to the necessity, the baked product is sintered, so that a pulverization step may be required.

-Crystallization tank, anode, and cathode-
The crystallization tank is not particularly limited as long as it has a cathode and an anode in the tank or a part or all of the tank, and can be appropriately selected according to the purpose. What constitutes the inner wall is preferred. When the cathode itself is the inner wall of the crystallization tank, lithium ions migrate to the inner wall of the crystallization tank, which increases the local lithium ion concentration in the vicinity of the cathode and the cathode, thereby efficiently depositing lithium carbonate. be able to.
In addition, you may give the density | concentration gradient of the lithium ion by electricity supply by separating a cathode and an anode with a diaphragm. Further, it is possible to use a structure in which an anode or a cathode is disposed in the center of the crystallization tank, a diaphragm is disposed on a concentric circle, and the inside of the crystallization tank or the crystallization tank itself is a counter electrode.

-Energization-
The energization is preferably performed in a state where a solution containing lithium ions and carbonate ions is heated, and energization may be started while the temperature of the solution is raised.
When energizing the solution containing lithium ions and carbonate ions, the current density applied between the cathode and the anode is preferably 0.5 A / dm ^{2 to} 50 A / dm ² , and 1 A / dm ^{2 to} 30 A / dm ^2. Is more preferable. When the current density is lower than 0.5 A / dm ² , migration of lithium ions may take time, and when it exceeds 50 A / dm ² , much energy is used for generation of hydrogen and oxygen. Efficiency may be reduced.
The distance between the anode and the cathode is preferably 0.5 cm to 20 m, more preferably 1 cm to 5 m. If the distance is less than 0.5 cm, there is a risk of short-circuit due to a short circuit. If the distance exceeds 20 m, the voltage increases and power consumption increases, which is not economical.

<Heating step and heating means>
The heating step is a step of heating the solution containing the lithium ions and carbonate ions, and is performed by a heating means.

The heating is preferably performed before energization, at the same time as energization, or immediately after energization (while the lithium concentration gradient is maintained), but in order to reduce the power consumption of energization, to the vicinity of the solubility of lithium carbonate beforehand. In order to raise the temperature, it is preferable to carry out before energization.
The heating temperature is not particularly limited as long as the solubility of lithium carbonate is saturated or higher, and can be appropriately selected according to the purpose. Specifically, 70 ° C or higher is preferable, and 80 ° C or higher is more preferable. 80 ° C. to 100 ° C. is particularly preferable. When the heating temperature is less than 70 ° C., the solubility of lithium carbonate increases, and the recovery rate of lithium carbonate may decrease.
There is no restriction | limiting in particular as a heating means to heat the solution containing the said lithium ion and carbonate ion, According to the objective, it can select suitably, For example, a heater etc. are mentioned.
The cathode is integrated with a heating means, that is, by using a heater as a cathode, a concentration gradient and a temperature gradient can be produced in the vicinity of the cathode and the cathode, and lithium carbonate can be efficiently crystallized. Moreover, in order to make it easy to collect | recover the lithium carbonate crystallized in the cathode and the cathode vicinity, without dissolving again, you may provide a heater in the cathode lower part of a crystallization tank bottom face, and the cathode vicinity lower part.
Here, the vicinity of the cathode means a range up to a distance of 1 cm from the cathode.

<Carbon dioxide supply process and carbon dioxide supply means>
The carbon dioxide supply step is a step of supplying carbon dioxide to the solution containing the lithium ions and carbonate ions, and is performed by carbon dioxide supply means.

The method for supplying carbon dioxide into the solution containing at least lithium ions is not particularly limited and can be appropriately selected according to the purpose. For example, by blowing carbon dioxide into a crystallization tank. There are a method of supplying carbon dioxide and a method of supplying carbon dioxide by carbon dioxide generated by introducing carbonate into the solution.
The carbon dioxide can be supplied before energization, at the same time as energization, or immediately after energization (while the lithium concentration gradient is maintained). It may be repeated. In the case where carbon dioxide is blown after the energization is stopped, it is preferable to perform the blowing operation of carbon dioxide while the concentration gradient of the solution containing at least lithium ions is maintained.
The carbon dioxide is preferably supplied near the cathode and in the vicinity of the cathode from the viewpoint of increasing the purification efficiency of lithium carbonate.
Here, the vicinity of the cathode means a range up to a distance of 1 cm from the cathode.
In order to improve the reaction efficiency between lithium ions and carbonate ions, it is preferable to stir the solution containing the lithium ions and carbonate ions using a stirrer and to circulate the solution in the tank using a pump.

  5-13 are preferable and 6-10 are more preferable as for the pH of the solution in the process which energizes the solution containing the said lithium ion and carbonate ion and precipitates lithium carbonate. If the pH is less than 5, the amount of carbonate used and the amount of carbon dioxide blown may be excessive, which is not economical. On the other hand, if the pH exceeds 13, the amount of carbonate used and the amount of carbon dioxide blown may be insufficient, and the yield may decrease.

<Other processes and other means>
Separation means for solid-liquid separation of the cathode and lithium carbonate deposited in the vicinity of the cathode is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include filtration, centrifugation and thickener.
In addition, when the said cathode is an inner wall of a crystallization tank, it is preferable to have a scraping member which scrapes off the lithium carbonate deposited on the cathode. Examples of the scraping member include a scraper.

Here, FIG. 1A and FIG. 1B are schematic views showing an example of the lithium carbonate production apparatus of the present invention. The lithium carbonate production apparatus includes a crystallization tank body 4 that stores a solution containing lithium ions and carbonate ions, an anode 1 that is located in the center of the crystallization tank, a cathode 2 that is an inner wall of the crystallization tank, A heating means 3 for heating a solution containing lithium ions, a power source 5 for energizing between the anode 1 and the cathode 2, and a scraper 6 for scraping off lithium carbonate deposited on the cathode 2 which is the inner wall of the crystallization tank are provided. . In addition, although illustration is abbreviate | omitted, the cooler which cools the solution containing lithium ion and carbonate ion is provided in the crystallization tank.
In the lithium carbonate manufacturing method using this lithium carbonate manufacturing apparatus, first, the power source 5 is operated and the anode 1 and the cathode 2 are energized, so that the lithium ions in the solution containing lithium ions and carbonate ions can be obtained. Since the lithium ion concentration increases in the vicinity of the cathode 2 and the solution containing lithium ions and carbonate ions is heated by the heating means 3 and the solubility of lithium carbonate decreases, the carbonic acid carbonate is present in the vicinity of the cathode and the cathode. Lithium is deposited. Thereafter, the temperature is controlled by the heating means 5 and the cooler so that the liquid temperature becomes constant. Lithium carbonate deposited on the cathode 2 which is the inner wall of the crystallization tank can be scraped and recovered by rotating a scraper 6 as scraping means.
On the other hand, since impurities such as fluorine and sulfuric acid in the solution containing lithium ions and carbonate ions move to the anode 1 side by energization, the impurities can be removed and the purity of lithium carbonate is improved.

  According to the method for producing lithium carbonate and the apparatus for producing lithium carbonate of the present invention, high-purity lithium carbonate can be efficiently produced from a solution containing lithium ions and carbonate ions. In particular, when a solution obtained by leaching lithium from a fired product containing a positive electrode material of a lithium ion secondary battery can be used, lithium ions can be concentrated on the cathode side while separating impurities in the solution, By crystallizing, high-purity lithium carbonate can be produced efficiently, 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.

Example 1
<Preparation of lithium-containing solution using reagent>
A solution was prepared by dissolving lithium hydroxide monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) in distilled water so that the lithium concentration was 3,210 mg / L.

<Analysis of lithium in solution>
The lithium concentration in the solution was analyzed by a high-frequency plasma emission spectroscopic analyzer (Thermo Fisher Scientific Co., Ltd., iCAP-6300), and the lithium concentration was calculated.

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

A lithium-containing liquid using 1.75 L of the above reagent was poured into a crystallization tank in which an anode and a cathode were arranged, and carbon dioxide gas was aerated at 0.4 l / min until the pH reached 8.5. Thereafter, the ventilation of carbon dioxide gas was stopped and heating was started. When the liquid temperature exceeded 50 ° C., a current of 10 A was passed between the anode and the cathode to start energization. The distance between the electrodes at this time was 5 cm, the current density was 33.3 A / dm ² , and the voltage was 8V. In addition, an electrode obtained by coating platinum on titanium oxide is used for the anode, and a commercially available titanium water heater (GTNH-1105, manufactured by Izumi Denki Co., Ltd., 100 V, 500 W) is used for the cathode. Was used for both purposes. A water cooling cooler was also provided in the crystallization tank.
The temperature was controlled with the heater and cooler so that the liquid temperature was kept constant at 85 ° C., and after 90 minutes had elapsed from the start of heating, the obtained lithium carbonate was subjected to solid-liquid separation. When crystallization was completed and the lithium concentration of the filtrate after solid-liquid separation was measured, it was 1,652 mg / L. The yield of lithium carbonate (in terms of lithium) by this crystallization operation was 48.5% when calculated from the difference between the lithium concentration (3,210 mg / L) of the original lithium-containing liquid and the lithium concentration of the filtrate. . Table 1 shows the transition of the lithium ion concentration in the solution with the passage of time after the start of heating and the yield of lithium carbonate (in terms of lithium). Moreover, the lithium concentration transition in the liquid over time is shown in FIG.
Moreover, the power consumption in the energization operation in this step was 107 Wh because the current was energized for 80 minutes at a current of 10 A and a voltage of 8 V.

(Example 2)
Lithium carbonate was obtained in the same manner as in Example 1 except that the current was 0.5 A and the current density was 1.67 A / dm ² . The yield of lithium carbonate (in terms of lithium) by this crystallization operation was 36.7% as calculated from the difference between the lithium concentration of the original lithium-containing liquid (3,210 mg / L) and the lithium concentration of the filtrate. . Table 1 shows the transition of the lithium ion concentration in the solution with the passage of time after the start of heating and the yield of lithium carbonate (in terms of lithium).
Moreover, the power consumption in the energization operation in this step was 2 Wh because the current was energized for 80 minutes at a current of 0.5 A and a voltage of 3 V.

(Comparative Example 1)
In Example 1, crystallization was performed under the same conditions as in Example 1 except that no electrode was provided in the crystallization tank, only a heater was used instead of the cathode, and no energization was performed. The results are shown in Table 1 and FIG. When crystallization was completed and the lithium concentration of the filtrate after solid-liquid separation was measured, it was 2,531 mg / L. The yield of lithium carbonate (in terms of lithium) by this crystallization operation was 21.2% as calculated from the difference in lithium concentration (3,210 mg / L) of the original lithium-containing liquid and the lithium concentration of the filtrate. .
Since the yield in Comparative Example 1 was low, in order to obtain the same yield as in Example 1, it was necessary to concentrate 1.5 times. When this was concentrated by heating, it took another 60 minutes in addition to the reaction time of 90 minutes of Comparative Example 1 with a 500 W heater to concentrate 1.5 times, and the power consumption was 500 Wh. From this, it was confirmed that Example 1 crystallizing while energizing was extremely advantageous in terms of cost compared to the normal concentrated crystallization of Comparative Example 1.

(Example 3)
<Separation of positive electrode materials for lithium ion secondary batteries as recycled materials>
A commercially available lithium-ion secondary battery for personal computers (a positive electrode is made of a ternary positive electrode material made of cobalt, manganese, nickel oxide, and a negative electrode is made of graphite) is fired at 700 ° C. in an air atmosphere for 1 hour. The obtained 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 using recycled materials>
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 2.

Crystallization was carried out using a lithium solution (composition shown in Table 2) prepared using the above-mentioned recycled raw material (used lithium ion secondary battery), and the liquid temperature was controlled at 80 ° C. with a heater and a cooler. Was crystallized in the same manner as in Example 1.
After 60 minutes from the start of heating, crystallization was completed, and the lithium concentration of the filtrate after solid-liquid separation was measured and found to be 2,308 mg / L. The yield of lithium carbonate (in terms of lithium) by this crystallization operation was calculated from the difference between the lithium concentration (2,909 mg / L) of the original lithium-containing liquid and the lithium concentration of the filtrate, and was 20.7%. there were. Table 3 shows the transition of the lithium ion concentration in the solution with the passage of time after the start of heating of Lithium in the solution with the passage of time after the start of heating, and the yield of lithium carbonate. Moreover, the lithium concentration transition in the liquid over time is shown in FIG. Moreover, when the impurity concentration in the obtained lithium carbonate was measured, the fluorine content was 0.21% by mass and the sulfuric acid was 0.17% by mass. The results are shown in Table 4.

(Comparative Example 2)
In Example 3, lithium carbonate was produced in the same manner as in Example 3, except that no electrode was provided in the crystallization tank, only a heater was used instead of the cathode, and no energization was performed. The results are shown in Table 3 and FIG. When the crystallization was completed and the lithium concentration of the filtrate after solid-liquid separation was measured, it was 2,791 mg / L. The yield of lithium carbonate (in terms of lithium) by this crystallization treatment was 4.1% as calculated from the difference between the lithium concentration of the original lithium-containing liquid (2,909 mg / L) and the lithium concentration of the filtrate. . Moreover, when the impurity concentration in the obtained lithium carbonate was measured, fluorine content was 0.25 mass% and sulfuric acid was 0.4 mass%. The results are shown in Table 4.

From the results of Table 3, FIG. 3, and Table 4, it was found that the lithium carbonate yield of Example 3 was higher in the lithium leaching solution leached from the fired product of the used lithium ion secondary battery. In addition, the lower yield of Example 3 compared to Example 1 is considered to be due to the difference in liquid temperature and the difference in impurity concentration.
Moreover, it was confirmed that the fluorine content and sulfuric acid content, which are impurities of the lithium carbonate obtained in Example 3, were lower than those in Comparative Example 2. This is considered to be due to the fact that in Example 3 where crystallization is performed by energization, impurities such as fluorine and sulfuric acid migrate near the anode and the concentration near the cathode decreases. Thus, according to the present invention, it has been found that not only the yield of lithium carbonate is improved, but also the impurity concentration can be reduced when applied to lithium recycling from a waste lithium ion secondary battery.

  The method for producing lithium carbonate and the apparatus for producing lithium carbonate of the present invention can efficiently produce high purity lithium carbonate from a solution containing lithium ions and carbonate ions, and in particular, firing including a positive electrode material of a lithium ion secondary battery. Lithium carbonate can be produced in high yield and purity from lithium obtained by leaching an object into water and a solution containing impurities such as fluorine and sulfuric acid, and the lithium ion secondary battery can be reused. .

1 Anode 2 Cathode (Inner Crystal Wall)
3 Heating means 4 Crystallization tank body 5 Power supply 6 Scraper

Claims (14)

  A solution containing lithium ions and carbonate ions is stored in a crystallization tank provided with an anode and a cathode, and a solution containing lithium ions and carbonate ions is energized to deposit lithium carbonate at and near the cathode. The manufacturing method of lithium carbonate characterized by including an electricity supply process. The method for producing lithium carbonate according to claim 1, wherein energization is performed at a current density of 0.5 A / dm ^{2 to} 50 A / dm ² .   The method for producing lithium carbonate according to claim 1, wherein a solution containing lithium ions and carbonate ions is heated.   The method for producing lithium carbonate according to claim 3, wherein the heating is performed at a temperature of 70 ° C. or higher.   The method for producing lithium carbonate according to claim 1, wherein carbon dioxide is supplied to a solution containing at least lithium ions to obtain a solution containing lithium ions and carbonate ions.   The method for producing lithium carbonate according to claim 5, wherein the solution containing at least lithium ions is a liquid obtained by calcining a waste lithium ion secondary battery and leaching lithium into water.   The method for producing lithium carbonate according to claim 1, wherein the precipitated lithium carbonate is subjected to solid-liquid separation. An anode and a cathode ;
A crystallization tank provided with the anode and the cathode ;
Energizing a solution containing lithium ions and carbonate ions stored in the crystallization tank, and energizing means for depositing lithium carbonate in the cathode and the vicinity thereof ;
An apparatus for producing lithium carbonate, comprising:   The apparatus for producing lithium carbonate according to claim 8, further comprising a heating unit that heats a solution containing lithium ions and carbonate ions.   The lithium carbonate manufacturing apparatus according to claim 9, wherein the cathode is integrated with the heating means.   The apparatus for producing lithium carbonate according to any one of claims 8 to 10, further comprising carbon dioxide supply means for supplying carbon dioxide to a solution containing at least lithium ions.   The apparatus for producing lithium carbonate according to claim 8, wherein the cathode is an inner wall of a crystallization tank.   The apparatus for producing lithium carbonate according to any one of claims 8 to 12, further comprising a separation means for solid-liquid separation of the lithium carbonate deposited in the vicinity of the cathode and the cathode.   The lithium carbonate production apparatus according to any one of claims 11 to 13, wherein the solution containing at least lithium ions is a liquid obtained by firing a waste lithium ion secondary battery and leaching lithium into water.