Production method and device of producing lithium carbonate

Abstract

To provide a production method and a production device of lithium carbonate, capable of acquiring lithium carbonate with good quality, while reducing a carbon dioxide discharge amount and a use cost.SOLUTION: A production method of lithium carbonate comprises: a carbon dioxide generation step for adding inorganic acid to a raw material including carbonate, for generating carbon dioxide; a carbon dioxide collection step for collecting the carbon dioxide; and a lithium carbonate generation step for adding the collected carbon dioxide to lithium-containing liquid for acquiring lithium carbonate. A production device of lithium carbonate comprises: a reaction tank for using a raw material including carbonate, and inorganic acid, for generating carbon dioxide; a carbon dioxide collection device for collecting the carbon dioxide; and a lithium carbonate generation tank for supplying carbon dioxide to the lithium-containing liquid from the carbon dioxide collection device, for generating lithium carbonate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing lithium carbonate and an apparatus for producing lithium carbonate. [Background technology]

[0002] In recent years, there has been a demand for reducing greenhouse gas emissions from electric vehicles and the lithium-ion batteries used in them throughout their entire life cycle, from sourcing the raw materials for the product to disposal and recycling.

[0003] When recovering resources such as lithium from lithium-ion batteries, it is common to use a recycled raw material called black mass, which is obtained by sintering and pulverizing lithium-ion batteries.

[0004] As a method for recovering lithium from black mass, for example, Patent Document 1 focuses on the lithium aluminate contained in black mass and discloses a method for recovering lithium by leaching black mass containing lithium aluminate in an acidic solution.

[0005] Patent Document 2 discloses a method in which an active material powder obtained by pulverizing a lithium ion battery is burned, the carbon in the active material powder is burned and converted into carbon dioxide, and then the burned active material powder is wet-dissolved to recover lithium. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6998241 [Patent Document 2] Patent Publication No. 2022-168616 Summary of the Invention [Problem to be solved by the invention]

[0007] The lithium recovery method disclosed in Patent Document 1 discloses that after recovering lithium, lithium is carbonated to obtain lithium carbonate. However, the method does not take into consideration the reduction of greenhouse gases such as carbon dioxide in the process of obtaining lithium carbonate.

[0008] Patent Document 2 discloses that carbon dioxide obtained by burning carbon in an active material powder is introduced into a lithium-containing solution obtained by wet dissolution to obtain lithium carbonate. In other words, a method for reducing carbon dioxide emissions by utilizing carbon dioxide generated by burning carbon in an active material powder as a carbonate source for obtaining lithium carbonate is being studied.

[0009] However, the active material powder obtained by crushing the lithium ion battery contains a large amount of impurities, and the gas components generated when the active material powder is burned contain not only carbon dioxide but also hydrogen fluoride, nitrogen oxides, sulfur compounds, etc. The hydrogen fluoride, nitrogen oxides, and sulfur compounds in the gas components are easily taken in as impurities, which causes a problem of reducing the purity of the lithium carbonate.

[0010] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a method for producing lithium carbonate and an apparatus for producing lithium carbonate, which can obtain high-quality lithium carbonate while reducing carbon dioxide emission and usage costs. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention is characterized by having any one of the following aspects. (1) a carbon dioxide generating step of generating carbon dioxide by adding an inorganic acid to a raw material containing a carbonate; A carbon dioxide recovery step of recovering the carbon dioxide; and a lithium carbonate production step of adding the recovered carbon dioxide to a lithium-containing liquid to obtain lithium carbonate.

[0012] (2) The method for producing lithium carbonate according to (1), wherein in the carbon dioxide recovery step, gaseous carbon dioxide is absorbed in an alkaline solution to recover the carbon dioxide.

[0013] (3) The method for producing lithium carbonate according to (1), wherein the carbon dioxide recovery step involves capturing gaseous carbon dioxide to recover the carbon dioxide.

[0014] (4) The method for producing lithium carbonate according to any one of (1) to (3), wherein the raw material contains a lithium compound.

[0015] (5) The method for producing lithium carbonate according to any one of (1) to (3), wherein the raw material is a lithium ion battery sintered powder obtained by sintering and pulverizing a lithium ion battery.

[0016] (6) The method for producing lithium carbonate according to any one of (1) to (5), wherein the inorganic acid is at least one selected from the group consisting of sulfuric acid, hydrochloric acid, and nitric acid.

[0017] (7) The method for producing lithium carbonate according to any one of (1) to (5), wherein in the carbon dioxide generation step, the temperature condition is in the range of 10° C. or higher and 40° C. or lower, and the pH condition is pH 6 or lower.

[0018] (8) a reaction vessel in which carbon dioxide is generated using a carbonate-containing raw material and an inorganic acid; A carbon dioxide capture device that captures the carbon dioxide; and a lithium carbonate production tank that supplies carbon dioxide from the carbon dioxide capture device to a lithium-containing liquid to produce lithium carbonate.

[0019] (9) The apparatus for producing lithium carbonate according to (8), wherein the carbon dioxide capture device is a device for capturing gaseous carbon dioxide.

[0020] (10) The apparatus for producing lithium carbonate according to (8), wherein the carbon dioxide capture device is a device that captures carbon dioxide by causing an alkaline solution to absorb gaseous carbon dioxide. Effect of the Invention

[0021] According to the present invention, it is possible to provide a method for producing lithium carbonate and an apparatus for producing lithium carbonate, which can produce high-quality lithium carbonate while reducing the amount of carbon dioxide emission and the usage cost. [Brief description of the drawings]

[0022] [Figure 1] 1 is a flow chart showing a step-by-step method for producing lithium carbonate according to one embodiment of the present invention. [Diagram 2] FIG. 1 is a schematic configuration diagram of an apparatus for producing lithium carbonate according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, a lithium carbonate manufacturing method and an apparatus for manufacturing lithium carbonate according to an embodiment of the present invention will be described with reference to the drawings. Note that each embodiment shown below is specifically described to better understand the gist of the invention, and does not limit the present invention unless otherwise specified.

[0024] (Method of producing lithium carbonate) As shown in FIG. 1 , the method for producing lithium carbonate of the present embodiment at least includes a carbon dioxide generation step S1 of generating carbon dioxide by adding an inorganic acid to a raw material containing a carbonate, a carbon dioxide recovery step S2 of recovering the carbon dioxide, and a lithium carbonate production step S5 of adding the recovered carbon dioxide to a lithium-containing liquid to obtain lithium carbonate. In the method for producing lithium carbonate of the present embodiment, the carbon dioxide generation step S1 may be a leaching step in which lithium ions are leached from a raw material containing carbonate. In this case, the method for producing lithium carbonate of the present embodiment may include a solid-liquid separation step S3 in which a leachate generated in the carbon dioxide generation step S1 is separated from a leachate residue, and an impurity removal step S5 in which impurities are removed from the leachate separated in the solid-liquid separation step S3.

[0025] The lithium carbonate production method of the present embodiment is preferably carried out by an apparatus for producing lithium carbonate 10 shown in Fig. 2. The apparatus for producing lithium carbonate 10 used in the present embodiment has at least a reaction tank (leaching tank) 11, a carbon dioxide capture device 13, and a lithium carbonate production tank 14. The apparatus for producing lithium carbonate 10 of the present embodiment may have a solid-liquid separation tank 12.

[0026] (Carbon dioxide generation process: S1) In the carbon dioxide generation step S1, an inorganic acid is added to a raw material containing carbonate to generate carbon dioxide. In this embodiment, the raw material may contain a lithium compound, and the carbonate may be a lithium compound. The carbonate may be, for example, one or more selected from the group consisting of lithium carbonate, cobalt carbonate, nickel carbonate, aluminum carbonate, and calcium carbonate.

[0027] More specifically, examples of raw materials containing carbonate include lithium ion battery sintered powder (black mass) formed from used lithium ion batteries collected as recycled raw materials, and lithium ion battery sintered powder (black mass) formed from scrap generated in the manufacturing process of lithium ion batteries.

[0028] The positive electrode active material of a lithium-ion battery contains lithium compounds such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium manganese oxide (LiMn2O4). The negative electrode active material may contain lithium compounds such as lithium titanate. Furthermore, the electrolyte may contain lithium compounds such as lithium hexafluorophosphate (LiPF6) and lithium tetrafluoroborate (LiBF4).

[0029] Among these lithium compounds, lithium compounds combined with trivalent cobalt, nickel, or manganese (such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium manganese oxide (LiMn2O4)) are difficult to dissolve in inorganic acids that become divalent ions, such as sulfuric acid. Therefore, it is preferable to heat and pyrolyze the lithium compound bonded with trivalent cobalt, nickel, or manganese, and convert the lithium in the lithium compound with trivalent cobalt, nickel, or manganese into the form of lithium carbonate. During the pyrolysis process, the lithium in the lithium compound bonded with trivalent cobalt, nickel, or manganese reacts with the carbon dioxide generated during the pyrolysis process to generate lithium carbonate (Li2CO3). In addition, the lithium compound derived from the electrolyte also reacts with the carbon dioxide generated during the pyrolysis process to generate lithium carbonate (Li2CO3).

[0030] First method: In a first method for obtaining a lithium ion battery calcined powder (black mass) containing lithium carbonate (Li2CO3), a used lithium ion battery is directly placed in a pyrolysis furnace after discharging, and is preferably heated in a non-oxidizing atmosphere such as a superheated steam atmosphere or nitrogen atmosphere at a temperature range of, for example, about 400°C to 600°C for 30 minutes to 5 hours to pyrolyze the lithium ion battery. When the pyrolysis of the lithium ion battery is performed under the above-mentioned conditions of atmosphere, temperature, and time, it is preferable because the aluminum contained in the lithium ion battery becomes embrittled without melting.

[0031] In the pyrolysis of the lithium ion battery of this embodiment, the exterior case of the lithium ion battery is melted or embrittled to separate and recover, and the binder is decomposed to make the positive electrode active material and the current collector separable from each other. Furthermore, in the pyrolysis of the lithium ion battery of this embodiment, the lithium compound bonded to trivalent cobalt, nickel, or manganese in the positive electrode active material is pyrolyzed to generate a pyrolyzate. Then, the carbon dioxide generated during the pyrolysis reacts with the lithium in the pyrolyzate to generate lithium carbonate (Li2CO3).

[0032] Next, the pyrolyzed product of the lithium ion battery is crushed. The electrode active material after pyrolysis is crushed into fine first crushed products having a particle size of approximately less than 1 mm. For example, a shear crusher such as a biaxial shear crusher or an impact crusher such as a hammer mill can be used alone or in combination to crush the material.

[0033] Next, the crushed material of the pyrolyzed product of the lithium ion battery is classified using a sieve with an appropriate mesh size, for example, into fine particles of less than 1 mm, preferably 0.5 mm or less, and coarse particles larger than the fine particles. For classification, for example, a vibrating sieve with a mesh size of 0.1 mm to 1.0 mm, preferably 0.1 mm to 0.5 mm, may be used. By such classification, the metal lumps of the exterior case and the metal foil derived from the current collector contained in the coarse particles can be separated from the pyrolyzed product of the electrode active material contained in the fine particles.

[0034] By the above steps, a lithium ion battery sintered powder (black mass) containing the lithium carbonate of this embodiment and having a particle size of 1 mm or less can be obtained. The proportion of lithium carbonate contained in the black mass is, for example, about 1% by mass or more and 10% by mass or less, which is suitable for generating carbon dioxide.

[0035] Second method: In the second method for obtaining lithium ion battery calcined powder (black mass) containing lithium carbonate (Li2CO3), first, a used lithium ion battery is immersed in salt water to remove the internal charge of the lithium ion battery. The lithium ion battery from which the internal charge has been removed is then dried and crushed to obtain second crushed pieces of a size that allows the positive electrode active material inside the lithium ion battery to be accurately separated from the exterior case. For example, a uniaxial crusher can be used for the crushing process. The concentration of the salt water for removing the internal charge of the lithium ion battery is not particularly limited. The size of the screen openings of the uniaxial crusher is preferably 6 mm to 10 mm in diameter. When the size of the screen openings is within this range, the positive electrode active material in the lithium ion battery can be sufficiently separated from the exterior case.

[0036] Next, the positive electrode active material is recovered from the second crushed material by classification using a sieve with an appropriate mesh size. For example, the positive electrode active material inside the lithium ion battery and the exterior case contained in the second crushed material can be classified by sieving using a vibrating sieve with a mesh size of 0.25 mm to 2.8 mm.

[0037] Another method for separating used lithium ion batteries into the positive electrode active material inside the lithium ion battery and the exterior case is to use an immersion crushing device that is immersed in an immersion liquid. Specifically, used lithium ion batteries are crushed using an immersion crushing device, and lightweight crushed materials such as the exterior case (plastic part) of the crushed lithium ion battery are suspended, metals containing the positive electrode active material are precipitated, and the precipitate is collected to collect the positive electrode active material. The immersion liquid is preferably an aqueous solution containing at least one selected from sodium hydroxide, calcium hydroxide, and lithium hydroxide, and has a pH of at least 8. When the immersion liquid contains at least one salt selected from sodium hydroxide, calcium hydroxide, and lithium hydroxide, the residual charge in the lithium ion battery can be released in the immersion liquid.

[0038] As described above, the positive electrode active material recovered using the uniaxial crusher or immersion crusher is placed in a pyrolysis furnace and heated, preferably in a superheated steam atmosphere or a non-oxidizing atmosphere such as nitrogen, for example, at a temperature range of about 400°C to 600°C for about 1 hour to 2 hours, to cause the lithium in the lithium compound bonded to trivalent cobalt, nickel, or manganese to react with the carbon dioxide generated during the pyrolysis process, thereby generating lithium carbonate (Li2CO3). When the pyrolysis of the positive electrode active material is carried out under the above-mentioned conditions of atmosphere, temperature and time, metals such as aluminum contained in the positive electrode active material are embrittled without being melted, which is preferable.

[0039] The pyrolysate containing lithium carbonate (Li2CO3) can be classified using a sieve with appropriate mesh size in the same manner as in the first method, to obtain a lithium-ion battery fired powder (black mass) containing the lithium carbonate of this embodiment and having a particle size of 1 mm or less.

[0040] The second method of obtaining black mass containing lithium carbonate (Li2CO3) is preferred because it allows for greater reduction in the amount of exhaust gas.

[0041] Third method: In the third method for obtaining lithium-ion battery sintered powder (black mass) containing lithium carbonate (Li2CO3), black mass is obtained from scrap generated during the lithium-ion battery manufacturing process, such as pieces of sheet-like positive electrode material or black powder, which is defective lithium-ion batteries.

[0042] For example, black mass can be obtained by thermally decomposing, crushing, and classifying scraps generated in the manufacturing process of lithium ion batteries in the same manner as in the first method. Alternatively, black mass can be obtained by crushing scraps generated in the manufacturing process of lithium ion batteries using a uniaxial crusher or an immersion crushing device in the same manner as in the second method, recovering the positive electrode active material from the crushed material, thermally decomposing the positive electrode active material, and classifying it.

[0043] In the carbon dioxide generation step S1 of this embodiment, for example, lithium ion battery fired powder (black mass) containing lithium carbonate as a carbonate salt obtained by any of the above-mentioned first to third methods is used as a raw material.

[0044] In this embodiment, the black mass is placed in a resin reaction tank (leaching tank) 11, and water and an inorganic acid are added to the reaction tank 11, after which the reaction tank 11 is stirred and shaken. Note that the black mass may be finely pulverized or crushed by attrition in order to improve the reaction efficiency in the reaction tank 11.

[0045] As the inorganic acid, it is preferable to use one or more acids selected from the group consisting of sulfuric acid, hydrochloric acid, and nitric acid. In the reaction tank 11, the raw materials black mass, water, and inorganic acid are mixed, and the pH is adjusted to a level at which lithium carbonate dissolves. The pH at which lithium carbonate dissolves is preferably, for example, about pH 6 or less, and more preferably in the range of pH 2 to pH 5. At pH 6 or less, lithium carbonate dissolves and carbon dioxide is generated. On the other hand, at a pH less than 2, the solubility of lithium carbonate does not change, and the amount of carbon dioxide generated does not change either. When lithium carbonate dissolves, one or more reactions selected from the decomposition reactions represented by the following formulas (1) to (3) proceed, and carbon dioxide is generated (carbon dioxide generation step S1). Li2CO3+H2SO4→Li2SO4(liquid phase)+H2O(liquid phase)+CO2(gas) (1) Li2CO3+2HCl→2LiCl(liquid phase)+H2O(liquid phase)+CO2(gas) (2) Li2CO3+2HNO3→2LiNO3(liquid phase)+H2O(liquid phase)+CO2(gas) (3)

[0046] The carbon dioxide generation step is preferably carried out at about room temperature (10 to 40° C., preferably 18 to 25° C.). In the conventional method of burning the carbon in the active material powder in lithium-ion batteries to generate carbon dioxide, the reaction temperature is high and hydrogen fluoride, nitrogen oxides (NO X) and sulfur compounds are generated at the same time, so when the gas components obtained by the conventional method are used in the subsequent lithium carbonate production step, there is a problem that the quality of the lithium carbonate is reduced. As described above, the gas generated in the carbon dioxide generation step S1 of this embodiment is a non-combustible gas, and therefore does not contain hydrogen fluoride, nitrogen oxides (NO X ), and does not contain sulfur compounds.

[0047] Within the range of temperature conditions in the carbon dioxide generation step S1 of this embodiment, the gas generated when black mass, water, and inorganic acid are mixed to generate carbon dioxide contains carbon dioxide, hydrogen, oxygen, etc. On the other hand, if the temperature is below room temperature, a problem occurs in that carbon dioxide is difficult to generate. The component composition of the gas generated in the carbon dioxide generation step S1 of this embodiment is, for example, carbon dioxide: 95 vol.% to 98 vol.%, hydrogen: 1 vol.% to 2 vol.%, and the balance: oxygen. The gas components can be measured by gas chromatography.

[0048] The reaction time in the reaction tank 11 may be, for example, in the range of 30 minutes to 20 hours. If the reaction time is less than 30 minutes, there is a concern that the lithium carbonate contained in the black mass will not react sufficiently with the inorganic acid. Also, if the reaction time is more than 20 hours, there is a concern that the reaction will not proceed any further and the treatment efficiency will decrease.

[0049] As described above, the components contained in the gas obtained in the carbon dioxide generation step S1 of this embodiment are carbon dioxide, oxygen, hydrogen, etc. Oxygen and hydrogen do not generate impurities in the lithium carbonate production step S5. Therefore, when the carbon dioxide obtained in the carbon dioxide generation step S1 of this embodiment is used as a carbon dioxide source in the subsequent lithium carbonate production step S5, high-quality lithium carbonate can be obtained without removing impurities in the gas.

[0050] In the carbon dioxide generation step S1 of this embodiment, leaching of the lithium compound into the liquid phase simultaneously proceeds. For example, lithium carbonate contained in black mass reacts with inorganic acid and migrates to the leachate (liquid phase) in the form of lithium sulfate, lithium chloride, lithium nitrate, etc. Next, a calcium compound is added to neutralize the solution in order to separate it from cobalt and nickel. Since the calcium compound added during neutralization is dissolved, and black mass contains lithium fluoride in addition to lithium carbonate, the leachate contains impurities such as calcium and fluorine. On the other hand, the leaching residue (solid phase) obtained after leaching contains carbon, cobalt, nickel, etc. contained in the black mass.

[0051] (Carbon dioxide capture process: S2) Next, in the carbon dioxide capture step S2, the carbon dioxide generated in the carbon dioxide generation step S1 is captured. As the carbon dioxide capture device 13 for capturing carbon dioxide, either a gas capture device that captures and captures carbon dioxide in a gaseous state, or an alkaline solution tank that absorbs and captures gaseous carbon dioxide with an alkaline solution can be used.

[0052] When gaseous carbon dioxide is collected by the gas collection device 13, the carbon dioxide can be used as it is in the subsequent lithium carbonate production step S5. Therefore, carbon dioxide is supplied from the gas collection device to the lithium carbonate production tank 14 through a gas supply pipe (not shown).

[0053] When carbon dioxide is captured using an alkaline solution tank, an aqueous sodium hydroxide solution is used as the alkaline solution, and carbon dioxide (gas) is introduced into the aqueous sodium hydroxide solution to capture carbon dioxide. The preferred concentration of the aqueous sodium hydroxide solution for capturing carbon dioxide is 1 mol / L or more and 18 mol / L or less. When carbon dioxide is introduced into an aqueous solution of sodium hydroxide, carbon dioxide is recovered as sodium hydrogen carbonate, as shown in the following equations (4) and (5). CO2+2NaOH→Na2CO3+H2O (4) Na2CO3+CO2+H2O→2NaHCO3(5)

[0054] (Solid-liquid separation process: S3) In the solid-liquid separation step S3 of this embodiment, the leachate (liquid phase) and the leach residue (solid phase) obtained in the carbon dioxide generation step S1 are separated. The solid-liquid separation may be carried out, for example, by filtering the solid-liquid mixture obtained in the carbon dioxide generation step S1 using a filtration device to separate the solid phase from the liquid phase. By such a solid-liquid separation step S3, it is possible to obtain a solid phase consisting of carbon, cobalt, nickel, etc. contained in the black mass, and a leachate (liquid phase) in which lithium carbonate is dissolved in the form of lithium sulfate, lithium chloride, or lithium nitrate.

[0055] The solid phase obtained by the solid-liquid separation step S3 can then be leached using sulfuric acid or the like to leach and recover each metal from insoluble substances such as carbon (graphite) contained in the solid phase.

[0056] (Impurity removal process: S4) In the impurity removal step S4 of this embodiment, impurities are removed from the leachate (liquid phase) separated in the solid-liquid separation step S3. In this embodiment, the lithium-ion battery sintered powder (black mass) is leached with one or more inorganic acids selected from the group consisting of sulfuric acid, hydrochloric acid, and nitric acid, and impurities such as calcium ions and fluoride ions are present in the leachate. If calcium ions are present in the leachate, they react with carbon dioxide to produce calcium carbonate in the subsequent lithium carbonate production step S5, lowering the purity of the lithium carbonate. Also, if fluoride ions are present in the leachate, lithium fluoride is produced in the subsequent lithium carbonate production step S5, lowering the purity of the lithium carbonate. Therefore, in this embodiment, it is desirable to remove impurities such as calcium ions and fluoride ions from the leachate (liquid phase) separated in the solid-liquid separation step S3.

[0057] In the impurity removing step S4, it is preferable to first remove fluoride ions from the leachate. Methods for removing fluoride ions include the calcium fluoride method, in which a calcium salt is added to the leachate to precipitate calcium fluoride (CaF2) and separate the fluoride ions as a solid, and the adsorption method, in which the fluoride ions are adsorbed onto aluminum hydroxide, or both.

[0058] In the calcium fluoride method, one or more calcium salts selected from calcium chloride, calcium carbonate, calcium hydroxide, and calcium sulfate can be used. By adding any of the above calcium salts to a leachate containing fluoride ions, calcium fluoride (CaF2) is precipitated and precipitated. This reaction can reduce the fluoride ion concentration in the leachate.

[0059] In the adsorption method, fluoride ions are removed from the leachate by adsorbing fluoride ions onto the surface of aluminum hydroxide in a leachate containing fluoride ions, and the aluminum hydroxide precipitate with the adsorbed fluoride ions is separated, thereby reducing the fluoride ion concentration in the leachate. In the adsorption method, aluminum sulfate or aluminum chloride may be added to the leachate containing fluoride ions. The leachate of this embodiment contains lithium ions, and when aluminum sulfate or aluminum chloride is added, aluminum hydroxide is precipitated. At this time, the pH of the leachate is preferably in the range of pH 6 to pH 8. If the pH is in the range of pH 6 to pH 8, fluoride ions can be adsorbed onto the aluminum hydroxide while reducing the solubility of the precipitated aluminum hydroxide, and the purity of the lithium carbonate obtained in the subsequent lithium carbonate production step S5 can be increased. If the pH of the leaching solution is outside the range of pH 6 or more and pH 8 or less, aluminum ions remain in the leaching solution, which has an undesirable effect on the subsequent lithium carbonate production step S5.

[0060] In the impurity removal step S4 of this embodiment, sodium carbonate (Na2CO3) may be further added to the leachate after removing the fluoride ions. When sodium carbonate is added to the leachate, calcium ions in the leachate react with sodium carbonate, calcium carbonate (CaCO3) precipitates, and the calcium ions can be separated as a solid content. By separating the calcium ions in this way, the calcium ion concentration in the leachate can be reduced, and the purity of the lithium carbonate obtained in the subsequent lithium carbonate production step S5 can be increased.

[0061] The leachate separated in the solid-liquid separation step S3 contains heavy metal ions (Fe 3+ , Mn 2+ , Ni 2+ , Co 2+ When the leachate contains heavy metal ions, the concentration of heavy metal ions in the leachate can be reduced by precipitating or adsorbing the heavy metal ions using any of the above-mentioned calcium fluoride method, adsorption method, and calcium carbonate production method.

[0062] (Lithium carbonate production process: S5) In the lithium carbonate production step S5 of the present embodiment, the carbon dioxide recovered in the carbon dioxide recovery step S2 is introduced into the leachate from which impurities have been removed in the impurity removal step S4 to precipitate lithium carbonate, and the lithium carbonate precipitate is separated, thereby obtaining lithium carbonate. That is, the leaching solution is used as the lithium-containing solution.

[0063] In the lithium carbonate production step S5 of this embodiment, the carbon dioxide recovered in the carbon dioxide recovery step S2 is used as a carbon dioxide source. The carbon dioxide recovered in the carbon dioxide recovery step S2 is the carbon dioxide contained in the gas generated in the preceding carbon dioxide generation step S1. The gas generated in the carbon dioxide generation step S1 of this embodiment contains oxygen, hydrogen, and the like in addition to carbon dioxide. However, the gas also contains hydrogen fluoride, nitrogen oxides (NO X ), and does not contain components such as sulfur compounds. Therefore, in the lithium carbonate production step S5 of the present embodiment, impurities are not produced, and high-quality lithium carbonate can be obtained.

[0064] Furthermore, in the lithium carbonate production step S5 of the present embodiment, carbon dioxide generated when the lithium compound contained in the black mass is leached into a liquid phase using an inorganic acid is used as a carbon dioxide source. This makes it possible to reduce the amount of carbon dioxide emitted into the atmosphere when recycling lithium-ion batteries and to reduce the cost of carbon dioxide when producing lithium carbonate.

[0065] In the lithium carbonate production step S5 of the present embodiment, it is preferable to introduce the gaseous carbon dioxide recovered using the gas collection device in the carbon dioxide recovery step S2 directly into the leachate in which any one of lithium sulfate, lithium chloride, and lithium nitrate is dissolved, through a gas supply pipe. When lithium carbonate is precipitated using gaseous carbon dioxide, components that affect the reaction for precipitating lithium carbonate are not introduced into the leaching solution, and lithium carbonate of higher quality can be produced.

[0066] In the lithium carbonate production step S5, the carbon dioxide recovered with the aqueous sodium hydroxide solution in the carbon dioxide recovery step S2 may be used as a carbon dioxide source. In this case, the carbon dioxide recovered with the aqueous sodium hydroxide solution obtained in the carbon dioxide recovery step S2 may be added to the leachate in which any one of lithium sulfate, lithium chloride, and lithium nitrate is dissolved. In this method, carbon dioxide can be collected and stored in the sodium hydroxide aqueous solution (alkaline solution tank), so that carbon dioxide is prevented from being discharged as a gas. Also, in this method, the reaction to produce lithium carbonate proceeds more quickly than in the method of introducing gaseous carbon dioxide. Therefore, the cost of carbon dioxide in the production of lithium carbonate can be reduced more effectively.

[0067] In the lithium carbonate production step S5 of the present embodiment, as the carbon dioxide source, only gaseous carbon dioxide recovered using a gas collection device may be used, only carbon dioxide recovered using an aqueous sodium hydroxide solution may be used, or both of them may be used.

[0068] In the above-described embodiment, lithium ion battery sintered powder (black mass) formed using lithium ion batteries recovered as recycled raw materials is used as the carbonate-containing raw material, but other materials such as incineration residue, dust, sludge, etc. may also be used. In the above-described embodiment, the leachate obtained by leaching black mass with an inorganic acid is used as the lithium-containing liquid for obtaining lithium carbonate. However, a lithium-containing liquid generated when a positive electrode end material or an electrolyte is leached with an acid may be used.

[0069] (Lithium carbonate manufacturing equipment) 2, the lithium carbonate manufacturing apparatus 10 of the present embodiment has at least a reaction tank (leaching tank) 11, a carbon dioxide capture device 13, and a lithium carbonate production tank 14. The lithium carbonate manufacturing apparatus 10 of the present embodiment may further have a solid-liquid separation tank 12. The reaction tank (leaching tank) 11 of this embodiment may be any reaction tank capable of generating carbon dioxide from a raw material containing carbonate using one or more inorganic acids selected from the group consisting of sulfuric acid, hydrochloric acid, and nitric acid. The carbon dioxide capture device 13 may be either or both of a gas capture device and an alkaline solution tank. The solid-liquid separation tank 12 may be a separation device, for example, a filtration device, which separates the solid-liquid mixture generated in the reaction tank (leaching tank) 11 into solid and liquid. The lithium carbonate production tank 14 may have a carbon dioxide supplying means for supplying the carbon dioxide captured by the carbon dioxide capture device 13, and a leaching solution supplying means for supplying the leaching solution separated in the solid-liquid separation tank 12 and in which any of lithium sulfate, lithium chloride, and lithium nitrate is dissolved, and may be any reaction tank capable of producing lithium carbonate. [Industrial Applicability]

[0070] According to the method for producing lithium carbonate and the apparatus for producing lithium of the present invention, it is possible to obtain high-quality lithium carbonate while reducing the emission of carbon dioxide and the usage cost, and thus it is possible to contribute to the reduction of greenhouse gases. [Explanation of symbols]

[0071] 10: Lithium carbonate manufacturing equipment 11: Reaction tank (leaching tank) 12: Solid-liquid separation tank 13: Carbon dioxide capture device 14: Lithium carbonate generation tank

Claims

1. a carbon dioxide generating step of generating carbon dioxide by adding an inorganic acid to a raw material containing a carbonate; A carbon dioxide recovery step of recovering the carbon dioxide; and a lithium carbonate production step of adding the recovered carbon dioxide to a lithium-containing liquid to obtain lithium carbonate, The method for producing lithium carbonate, wherein the raw material contains a lithium compound.

2. 2. The method for producing lithium carbonate according to claim 1, wherein in the carbon dioxide recovery step, gaseous carbon dioxide is absorbed in an alkaline solution to recover the carbon dioxide.

3. The method for producing lithium carbonate according to claim 1, wherein the carbon dioxide recovery step recovers the carbon dioxide by capturing gaseous carbon dioxide.

4. 2. The method for producing lithium carbonate according to claim 1, wherein the raw material is a lithium ion battery sintered powder obtained by sintering and pulverizing a lithium ion battery.

5. 2. The method for producing lithium carbonate according to claim 1, wherein the inorganic acid is at least one selected from the group consisting of sulfuric acid, hydrochloric acid, and nitric acid.

6. 2. The method for producing lithium carbonate according to claim 1, wherein in the carbon dioxide generation step, the temperature condition is in the range of 10° C. or more and 40° C. or less, and the pH condition is pH 6 or less.

7. a reaction vessel for generating carbon dioxide using a raw material containing a carbonate and a lithium compound and an inorganic acid; A carbon dioxide capture device that captures the carbon dioxide; and a lithium carbonate production tank that supplies the carbon dioxide from the carbon dioxide capture device to a lithium-containing liquid to produce lithium carbonate.

8. The apparatus for producing lithium carbonate according to claim 7, wherein the carbon dioxide capture device is a device for capturing gaseous carbon dioxide.

9. A reaction vessel for generating carbon dioxide using a raw material containing a carbonate and an inorganic acid; A carbon dioxide capture device that captures the carbon dioxide; a lithium carbonate generation tank that supplies the carbon dioxide from the carbon dioxide capture device to a lithium-containing liquid to generate lithium carbonate, The apparatus for producing lithium carbonate, wherein the carbon dioxide capture device is a device that captures gaseous carbon dioxide by causing an alkaline solution to absorb the carbon dioxide.

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