A method for producing high-purity lithium carbonate from waste refractory saggars using anion exchange.

Abstract

The present invention provides an optimized method for recovering high-purity lithium carbonate from a lithium-containing composite oxide deposited on the eroded surface of a waste refractory crucible to be discarded. Therefore, by using the method for producing high-purity lithium carbonate from the waste refractory crucible of the present invention, not only can the discarded waste refractory crucible be recycled to produce high-purity lithium carbonate that can be used in the manufacture of lithium secondary batteries, but it is also expected that the positive electrode active material, iron oxide, alumina, silicate, and calcium carbonate obtained incidentally in the manufacturing process can be recycled.

Description

[Technical Field]

[0001] The present invention relates to a method for producing high-purity lithium carbonate from waste refractory saggars using anion exchange. More specifically, the present invention relates to a method for producing high-purity lithium carbonate with a purity of 99.9% or higher by crushing and dissolving waste refractory saggars, followed by solid-liquid separation, wet magnetic separation, anion exchange, carbonation, pressurized carbonic acid dissolution, and heat fractional precipitation reactions. [Background technology]

[0002] The positive electrode active material for lithium secondary batteries is manufactured by firing at high temperatures in refractory saggers (also known as firing saggers) made from oxide ceramics mainly composed of SiO2, Al2O3, and MgO. Because these refractory saggers are repeatedly used for high-temperature firing of lithium-containing composite oxides, which are the raw materials for the positive electrode active material, their surfaces are eroded over time, and lithium hydroxide, lithium carbonate, and the positive electrode active material are deposited in the eroded areas. Finally, refractory saggers whose surfaces have been eroded by lithium hydroxide, lithium carbonate, etc., have reduced heat resistance and are discarded. It is said that the amount of waste refractory saggers generated in South Korea is about 9,000 tons per year, but with the recent surge in demand for lithium-ion secondary batteries, coupled with the progress of the popularization of mobile devices and electric vehicles, the amount of waste refractory saggers generated is expected to increase sharply.

[0003] As described above, refractory saggars are used in the manufacture of positive electrode active materials, and during the high-temperature firing process, they are eroded by lithium-containing composite oxides and lose their function. Therefore, if lithium-containing composite oxides deposited in the eroded areas of discarded refractory saggars, which are discarded after repeated high-temperature firing of lithium-containing composite oxides reduces their heat resistance, can be recovered in the form of high-purity lithium sulfate, lithium carbonate, or lithium phosphate, it is expected that they can be reused in the production of lithium-ion secondary batteries, thereby reducing production costs. However, there is absolutely no known method for recovering high-purity lithium compounds from discarded refractory saggars.

[0004] All references cited herein, including publications, patent applications, and patents, are incorporated herein by reference to the same extent as each individual reference is specifically identified and referred to, and to the same extent as all of its contents are described herein. [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a method for producing high-purity lithium carbonate with a purity of 99.9 or higher from waste refractory saggars that are discarded after being used in high-temperature firing during the production of positive electrode active materials for lithium secondary batteries.

[0006] Other objects and technical features of the present invention are presented more specifically in the following detailed description of the invention, claims, and drawings. [Means for solving the problem]

[0007] The present invention comprises the first step of crushing waste refractory saggars to produce waste refractory saggar pulverized material, the second step of adding an alkaline leaching agent and water to the waste refractory saggar pulverized material and reacting them to produce a waste refractory saggar pulverized material dissolution reaction slurry, the third step of primary solid-liquid separation of the waste refractory saggar pulverized material dissolution reaction slurry, the fourth step of passing the filtrate obtained as a liquid phase using the primary solid-liquid separation through an anion exchange resin to carry out an anion exchange reaction, the fifth step of carrying out a carbonation reaction on the filtrate obtained as a liquid phase through the anion exchange reaction to produce a carbonation reaction solution, and the second step of secondary carbonation reaction solution The present invention provides a method for producing high-purity lithium carbonate from waste refractory saggars using anion exchange, comprising: a sixth step of solid-liquid separation; a seventh step of performing a pressurized carbonic acid dissolution reaction on the solid phase obtained using the secondary solid-liquid separation; an eighth step of tertiary solid-liquid separation of the reaction solution from the pressurized carbonic acid dissolution reaction; a ninth step of performing a thermal fractional precipitation reaction on the filtrate obtained as a liquid phase using the tertiary solid-liquid separation; a tenth step of quaternary solid-liquid separation of the reaction solution from the thermal fractional precipitation reaction; and an eleventh step of drying the solid phase obtained using the quaternary solid-liquid separation to obtain high-purity lithium carbonate.

[0008] The slurry for the dissolution reaction of the spent refractory saggar is characterized by adding 5 to 50 parts by weight of an alkaline leaching agent, such as calcium hydroxide, calcium oxide, or magnesium hydroxide, to 100 parts by weight of spent refractory saggar crushed to 200# (mesh) or less, mixing with 350 parts by weight of water, and reacting this mixture for 30 to 120 minutes under a temperature of 50 to 80°C. The anion exchange resin is an anion exchange resin produced by adsorbing trimethylammonium or dimethylethanolamine onto a styrene-based resin having a gel structure, and the anion exchange reaction is characterized by passing the filtrate obtained as a liquid phase using the primary solid-liquid separation method through an anion exchange column filled with the anion exchange resin at a flow rate of 0.1 to 1 m / sec.

[0009] The carbonation reaction is characterized by introducing the permeate from the anion exchange reaction into a pressure reaction vessel (or sealed container), injecting one selected from carbon dioxide, carbonated water, and lithium bicarbonate aqueous solution into the permeate and reacting until the pH reaches 7, and then allowing the reaction to be terminated by allowing it to remain at a temperature of 80-100°C for 20 minutes or more. The pressurized carbonation dissolution reaction is characterized by mixing 100 parts by weight of water and 2-12 parts by weight of lithium carbonate obtained as a solid phase using the secondary solid-liquid separation in a pressure reaction vessel (or sealed container), and then dissolving the lithium carbonate by blowing in carbon dioxide (CO2) at a temperature of 0-20°C and stirring for 30-120 minutes while maintaining the carbon dioxide pressure in the reaction vessel at 1-25 bar.

[0010] The aforementioned heat fractional precipitation reaction is characterized by heating the concentrated solution obtained using the reverse osmotic pressure concentration for 20 minutes or more under a temperature of 80 to 100°C to precipitate lithium carbonate, and the lithium carbonate produced by the above method is characterized by having a purity of 99.9% or higher.

[0011] The present invention comprises a 12th step of crushing waste refractory saggars to produce waste refractory saggar pulverized material, a 13th step of adding an alkaline leaching agent and water to the waste refractory saggar pulverized material and reacting them to produce a waste refractory saggar pulverized material dissolution reaction slurry, a 14th step of performing primary solid-liquid separation of the waste refractory saggar pulverized material dissolution reaction slurry, and after producing a suspension from the solid phase obtained using the primary solid-liquid separation, performing primary wet magnetic separation to perform a first magnetic deposition. Step 15: Obtain a material and a first non-magnetic material; Step 16: After producing the first non-magnetic material as a suspension, perform secondary wet magnetic separation to obtain a second magnetic material and a second non-magnetic material; Step 17: Add water and a leaching agent to the second non-magnetic material and react them to produce a lithium leaching reaction solution; Step 18: Adjust the pH of the lithium leaching reaction solution to 6-8 to produce a neutralization reaction solution; Step 17: The present invention provides a method for producing high-purity lithium carbonate from a waste refractory saggar, comprising: a 19th step of quintuple solid-liquid separation; a 20th step of reverse osmotic concentration of the filtrate obtained as a liquid phase using the quintuple solid-liquid separation; a 21st step of carbonation reaction of the concentrated liquid obtained using the reverse osmotic concentration step; a 22nd step of sextent solid-liquid separation of the reaction solution from the carbonation reaction; a 23rd step of pressurized carbonic acid dissolution reaction of lithium carbonate obtained as a solid phase using the sextent solid-liquid separation; a 24th step of tertiary solid-liquid separation of the reaction solution from the pressurized carbonic acid dissolution reaction; a 25th step of thermal fractional precipitation reaction of the filtrate obtained as a liquid phase using the tertiary solid-liquid separation; a 26th step of quaternary solid-liquid separation of the reaction solution from the thermal fractional precipitation reaction; and a 27th step of drying the solid phase obtained using the quaternary solid-liquid separation to obtain high-purity lithium carbonate.

[0012] The aforementioned slurry for dissolving the spent refractory saggar is characterized by adding 5 to 50 parts by weight of an alkaline leaching agent, such as calcium hydroxide, calcium oxide, or magnesium hydroxide, to 100 parts by weight of spent refractory saggar crushed to 200# (mesh) or less, mixing with 350 parts by weight of water, and reacting this mixture for 30 to 120 minutes under a temperature of 50 to 80°C. The leaching agent used for leaching the second non-magnetic material is characterized by being an acid leaching agent containing one or more of sulfuric acid, nitric acid, and hydrochloric acid, or an alkaline leaching agent containing one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, and magnesium hydroxide.

[0013] The aforementioned reverse osmotic concentration process is carried out using a batch-type reverse osmotic equipment, with the upper limit of the pump's operating pressure set to 50 kg / cm². 2 The method is characterized by setting the filtrate to a certain level and concentrating it until the lithium concentration of the filtrate obtained as the liquid phase using the tertiary solid-liquid separation reaches 10,000 to 70,000 mg / L. The pressurized carbonate dissolution reaction is characterized by mixing 100 parts by weight of water and 2 to 12 parts by weight of lithium carbonate obtained as the solid phase using the secondary solid-liquid separation in a pressure reaction vessel (or sealed container), and then dissolving the lithium carbonate by blowing in carbon dioxide (CO2) under a temperature of 0 to 20°C and stirring for 30 to 120 minutes while maintaining the carbon dioxide pressure in the reaction vessel at 1 to 25 bar.

[0014] The aforementioned heat fractional precipitation reaction is characterized by heating the concentrated solution obtained using the reverse osmotic pressure concentration method to 80-100°C for 20 minutes or more to precipitate lithium carbonate, and the lithium carbonate produced by the above method is characterized by having a purity of 99.9% or higher. [Effects of the Invention]

[0015] The present invention provides an optimized method for recovering high-purity lithium carbonate from a lithium-containing composite oxide deposited on the eroded surface of a waste refractory crucible to be discarded. Therefore, by using the method for producing high-purity lithium carbonate from the waste refractory crucible of the present invention, not only can the discarded waste refractory crucible be reused to produce high-purity lithium carbonate that can be used in the production of lithium secondary batteries, but it is also expected that the cathode active material, iron oxide, alumina, silicate, and calcium carbonate obtained incidentally in the production process can be reused.

Brief Description of the Drawings

[0016] [Figure 1] A method for producing high-purity lithium carbonate from the waste refractory crucible of the present invention is schematically shown. [Figure 2] The results of analyzing the constituent minerals of the waste refractory crucible of the present invention by X-ray diffraction (XRD) are shown. [Figure 3] A scanning electron microscope (SEM) photograph of the waste refractory crucible pulverized material, which shows the overall particle size distribution and the surface structure of the particles.

Embodiments for Carrying Out the Invention

[0017] The present invention relates to a method for producing high-purity lithium carbonate from a waste refractory crucible using anion exchange. As the refractory crucible is repeatedly used, it is eroded and destroyed by lithium hydroxide, lithium carbonate, etc. The present invention aims to recover lithium carbonate, which is a high-value-added lithium compound, from the waste refractory crucible that is discarded without being reused, with high purity. The waste refractory crucible is a ceramic container used for firing the cathode active material for secondary batteries, and mainly contains SiO2, Al2O3, and MgO. Table 1 shows the composition of the waste refractory crucible used for sintering NCA (sample name: SG1) and NCM (sample name: SG2), which are cathode materials.

[0018]

Table 1

[0019] As a result of the analysis, it was confirmed that the lithium (Li) contents of SG1 and SG2 were 2.1% and 0.88% respectively, and the higher one. When this was converted to the content of lithium carbonate, it was confirmed that it corresponded to SG1 = 11.17% and SG2 = 4.68%. Also, it was confirmed that the contents of nickel and cobalt were 0.13 to 0.16% and 0.01 to 0.02% respectively, and it was confirmed that the value to be recovered was sufficiently high.

[0020] The waste refractory crucible is composed of mullite, cordierite, alumina, quartz, magnesium aluminate, lithium silicate, lithium aluminum oxide, lithium aluminum silicate, etc. Among the constituent components of the waste refractory crucible, the substances causing the destruction of the refractory crucible are lithium silicate, lithium aluminum oxide, lithium aluminum silicate, etc.

[0021] The present invention comprises the first step of crushing waste refractory saggars to produce waste refractory saggar pulverized material, the second step of adding an alkaline leaching agent and water to the waste refractory saggar pulverized material and reacting them to produce a waste refractory saggar pulverized material dissolution reaction slurry, the third step of primary solid-liquid separation of the waste refractory saggar pulverized material dissolution reaction slurry, the fourth step of passing the filtrate obtained as a liquid phase using the primary solid-liquid separation through an anion exchange resin to carry out an anion exchange reaction, the fifth step of carrying out a carbonation reaction on the filtrate obtained as a liquid phase through the anion exchange reaction to produce a carbonation reaction solution, and the second step of secondary carbonation reaction solution The present invention provides a method for producing high-purity lithium carbonate from waste refractory saggars using anion exchange, comprising: a sixth step of solid-liquid separation; a seventh step of performing a pressurized carbonic acid dissolution reaction on the solid phase obtained using the secondary solid-liquid separation; an eighth step of tertiary solid-liquid separation of the reaction solution from the pressurized carbonic acid dissolution reaction; a ninth step of performing a thermal fractional precipitation reaction on the filtrate obtained as a liquid phase using the tertiary solid-liquid separation; a tenth step of quaternary solid-liquid separation of the reaction solution from the thermal fractional precipitation reaction; and an eleventh step of drying the solid phase obtained using the quaternary solid-liquid separation to obtain high-purity lithium carbonate.

[0022] The slurry for the dissolution reaction of the spent refractory saggar is characterized by adding 5 to 50 parts by weight of an alkaline leaching agent, such as calcium hydroxide, calcium oxide, or magnesium hydroxide, to 100 parts by weight of spent refractory saggar crushed to 200# (mesh) or less, mixing with 350 parts by weight of water, and reacting this mixture for 30 to 120 minutes under a temperature of 50 to 80°C. The anion exchange resin is an anion exchange resin produced by adsorbing trimethylammonium or dimethylethanolamine onto a styrene-based resin having a gel structure, and the anion exchange reaction is characterized by passing the filtrate obtained as a liquid phase using the primary solid-liquid separation method through an anion exchange column filled with the anion exchange resin at a flow rate of 0.1 to 1 m / sec.

[0023] The carbonation reaction is characterized by introducing the permeate from the anion exchange reaction into a pressure reaction vessel (or sealed container), injecting one selected from carbon dioxide, carbonated water, and lithium bicarbonate aqueous solution into the permeate and reacting until the pH reaches 7, and then allowing the reaction to be terminated by allowing it to remain at a temperature of 80-100°C for 20 minutes or more. The pressurized carbonation dissolution reaction is characterized by mixing 100 parts by weight of water and 2-12 parts by weight of lithium carbonate obtained as a solid phase using the secondary solid-liquid separation in a pressure reaction vessel (or sealed container), and then dissolving the lithium carbonate by blowing in carbon dioxide (CO2) at a temperature of 0-20°C and stirring for 30-120 minutes while maintaining the carbon dioxide pressure in the reaction vessel at 1-25 bar.

[0024] The aforementioned heat fractional precipitation reaction is characterized by heating the concentrated solution obtained using the reverse osmotic pressure concentration under a temperature of 80 to 100°C for 20 minutes or more to precipitate lithium carbonate, and the high-purity lithium carbonate is characterized by having a purity of 99.9% or higher.

[0025] The following describes in detail, step by step, the method for producing high-purity lithium carbonate from waste refractory saggars using anion exchange according to the present invention.

[0026] (1) First process: Crushing of waste refractory saggars The waste refractory saggars are crushed into a powder of 200# or less. However, there is a problem with the low crushing efficiency when crushing the waste refractory saggars all at once. Therefore, it is preferable to first coarsely crush them to 1 mm or less using a jaw crusher, and then to crush them to 200# (mesh) or less using a ball mill. The waste refractory saggars have high compressive strength but are susceptible to impact. While an impact crusher can be used to crush the waste refractory saggars, it produces crushed particles with sharp surfaces and high hardness, leading to increased wear on the crusher's parts and higher costs. Therefore, in this invention, a jaw crusher, which has easily replaceable parts and is inexpensive, is used in the primary crushing process, and a ball mill is used in the secondary crushing process. Preferably, to improve crushing efficiency, an intermediate crusher such as an impact crusher may be placed before the secondary crushing process.

[0027] (2) Second process: Dissolution process of crushed waste refractory saggars The pulverized waste refractory saggar material obtained using the first step contains lithium-containing substances such as lithium hydroxide, lithium carbonate, lithium silicate, lithium aluminum oxide, or lithium aluminum silicate. Most of these lithium-containing substances are water-soluble, but some substances, including lithium aluminum silicate, have low solubility in water and are difficult to dissolve with water alone. To solve this problem, the present invention applies a waste refractory saggar material dissolution step in which the pulverized waste refractory saggar material is mixed with water and an alkaline leaching agent, which is a mixture of one or more selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, or alkaline earth metal hydroxides, and then heated. The waste refractory saggar material dissolution step of the present invention has the advantage of a high lithium recovery rate because, since it is heated and dissolved together with the alkaline leaching agent, even lithium aluminum silicate, which has low solubility in water, can be decomposed and dissolved. The decomposition and dissolution reactions of lithium-containing substances with low solubility tend to become more reactive in proportion to the alkali concentration and temperature. For this reason, using an alkaline leaching agent containing alkali metal salts increases the concentrations of silicon and aluminum, requiring a separate process to remove them. Conversely, using a leaching agent produced from an alkali earth metal oxide or hydroxide with water promotes the decomposition of lithium aluminum silicate and helps maintain low concentrations of silicon and aluminum in the solution, as it reacts with lithium carbonate, which has relatively low solubility, to produce lithium hydroxide, which has high solubility, and sparingly soluble carbonates, thus improving the lithium leaching rate. Therefore, in the waste refractory saggar dissolution process of the present invention, calcium hydroxide, calcium oxide, or magnesium hydroxide is used as a leaching agent to promote lithium extraction, and the amount added is preferably 5 to 50 parts by weight based on 100 parts by weight of waste refractory saggars.The aforementioned dissolution process of crushed waste refractory saggars takes more than 6 hours to complete at temperatures below 20°C, completes within 2 hours at 50°C, and completes within 30 minutes at 80°C. Furthermore, while the reaction completes within 10 minutes at temperatures near 100°C, there is a problem of significant energy loss due to water evaporation. Therefore, the preferred dissolution process of crushed waste refractory saggars according to the present invention involves a reaction period of 30 to 120 minutes at temperatures between 50 and 80°C.

[0028] In short, the preferred waste refractory saggar dissolution process of the present invention involves heating a slurry of waste refractory saggars containing 5 to 50 parts by weight of calcium hydroxide, calcium oxide, or magnesium hydroxide as a leaching agent to 100 parts by weight of waste refractory saggars ground to 200# (mesh) or less, to a temperature of 50 to 80°C and reacting for 30 to 120 minutes. For reference, if alkali metal hydroxide water equivalent to 5 to 50% of the amount used is further added along with alkaline earth metal hydroxide (or oxide) under the same conditions, the leaching rate and leaching rate of lithium will be increased by approximately 5%. The above method is suitable when the increased process cost can be tolerated.

[0029] (3) Third step: Primary solid-liquid separation step The dissolved reaction solution of the pulverized waste refractory saggar is subjected to solid-liquid separation (primary solid-liquid separation). For this primary solid-liquid separation, a sedimentation tank, filter press, screw filter, centrifuge, etc., can be used, and the efficiency can be increased by combining two or more of these. The solid phase obtained by the primary solid-liquid separation contains a positive electrode active material and a refractory composition, and the liquid phase (filtrate) is lithium (Li + ), aluminum (Al(OH)4 - ), silicon (H2SiO4 2-) is included. The filtrate is introduced into an anion exchange step and a carbonation step to produce high-purity lithium carbonate, and the solid phase is introduced into a multi-stage magnetic separation step, a lithium leaching step and a carbonation reaction step to recover the lithium contained therein as lithium carbonate, and the recovered lithium carbonate is introduced into a pressurized carbon dioxide dissolution step performed after the anion exchange step and carbonation step of the filtrate to produce high-purity lithium carbonate. Below, the process for producing high-purity lithium carbonate using the filtrate will be described first, and then the process for producing high-purity lithium carbonate using the solid phase will be described.

[0030] (4) Fourth step: Anion exchange step The filtrate obtained in the primary solid-liquid separation step is a strongly alkaline aqueous lithium hydroxide solution with a pH of 12 or higher. The aqueous lithium hydroxide solution contains Al(OH)4 along with lithium hydroxide. - H2SiO4 2- and Ca 2+ It contains impurities such as the above. In the present invention, an anion exchange step is performed in which the material is passed through an anion exchange resin in order to remove the above impurities. The anion exchange resin may be a resin that can be used in a strongly basic region, and preferably, a styrene-based resin having a gel structure to which trimethylammonium or dimethylethanolamine is adsorbed and OH - It is preferable that the functional group is included. The anion exchange step can be carried out in an ion exchange column in which the height of the anion exchange resin layer is 80 cm or more, and can be carried out under room temperature conditions while the lithium hydroxide aqueous solution is flowed at a flow rate of 0.1 to 1 m / sec. It is preferable to use a continuous ion exchange column in which the ion exchange column is in contact with the treatment solution in a countercurrent manner, and the resin used for a certain period of time is regenerated and put back in. When the filtrate (lithium hydroxide aqueous solution) obtained in the primary solid-liquid separation step is injected into the ion exchange column, the impurities remain bound to the anion exchange resin, and the lithium hydroxide aqueous solution is obtained as a flow-through, thus achieving high purity.

[0031] An anion exchange resin used for a certain period of time is regenerated by desorbing the adsorbed anions. The backwash solution produced at this time is sent to the second step, the waste refractory saggar pulverization step, for reuse, and the regenerated anion exchange resin is sent to the anion exchange tower for reuse. At this time, water and slaked lime may be further added to the backwash solution before being introduced into the waste refractory saggar pulverization step.

[0032] (5) Fifth step: Primary carbonation reaction step The liquid that passes through the ion exchange column is an aqueous lithium hydroxide solution from which impurities have been removed. In the present invention, a primary carbonation reaction step is performed to obtain lithium carbonate (Li2CO3) from the lithium hydroxide. The primary carbonation reaction step can be performed by a first carbonation method (see Chemical Formula 1) in which carbon dioxide (CO2) gas is injected into the aqueous lithium hydroxide solution; a second carbonation method (see Chemical Formula 2) in which the aqueous lithium hydroxide solution is mixed with carbonated water; a third carbonation method (see Chemical Formula 3) in which the aqueous lithium hydroxide solution is mixed with an aqueous lithium bicarbonate solution; a fourth carbonation method (see Chemical Formula 4) in which the aqueous lithium hydroxide solution is mixed with an aqueous sodium carbonate solution; or a fifth carbonation method (see Chemical Formula 5) in which the aqueous lithium hydroxide solution is mixed with an aqueous potassium carbonate solution.

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] The fourth and fifth carbonation methods described above may generate impurities such as sodium and potassium, respectively, which necessitates further steps to remove these impurities. Therefore, in the present invention, the first, second, or third carbonation method, which does not raise concerns about the generation of such impurities, is used, and preferably the first carbonation method, which involves injecting carbon dioxide gas, is used.

[0039] According to an embodiment of the present invention, the first carbonation method involves adding 1 L of a lithium hydroxide aqueous solution concentrated to a concentration of 2 mol / L to a pressure reaction vessel with a capacity of 1.5 L, and stirring while blowing in carbon dioxide gas at a flow rate of 1 L / min, thereby completing the lithium carbonate production reaction in about 22 minutes. The concentration of the lithium hydroxide aqueous solution in this reaction is preferably 0.5 to 5 mol / L. If the concentration of the lithium hydroxide aqueous solution is lower than 0.5 mol / L, the amount of lithium carbonate produced will be too small, reducing the process efficiency. If the concentration is higher than 5 mol / L, the viscosity of the aqueous solution will be too high, resulting in impurities not being removed. The first carbonation method of the present invention is an exothermic reaction, and when reacting an aqueous solution at 20°C, the temperature at the end of the reaction will be approximately 35°C. Therefore, no additional heating is required during the reaction period. However, as the temperature increases, the solubility of lithium carbonate decreases, which not only increases the yield of lithium carbonate but also speeds up the crystal growth rate, resulting in an improvement in purity due to recrystallization. For this reason, it is preferable to carry out the reaction so that the final reaction solution temperature is 80-100°C.

[0040] The carbonation reaction solution of the present invention is strongly alkaline with a pH of 12 or higher at the beginning of the reaction, and as the reaction progresses, the pH gradually decreases and converges to pH 7. The formation of lithium carbonate ends at around pH 9, and at pH levels lower than pH 9, lithium carbonate is redissolved as lithium bicarbonate. Therefore, it is preferable for the carbonation reaction to end when the pH is in the range of 8 to 10. However, even if the reaction proceeds until the pH of the reaction solution reaches 7, the generated lithium bicarbonate is recovered in subsequent steps, so the yield does not decrease. Rather, it is more preferable to allow the reaction to proceed until the pH of the reaction solution reaches 7, as this has the advantage of minimizing membrane damage in the subsequent reverse osmotic concentration step.

[0041] In short, the primary carbonation reaction step of the present invention involves adding an aqueous lithium hydroxide solution with a concentration of 0.5 to 5 mol / L to a pressure reaction vessel (or a sealed container), injecting carbon dioxide gas to react until the pH reaches 7, then heating the reaction solution to 80 to 100°C and allowing it to remain at that temperature for 20 minutes or more to complete the carbonation reaction.

[0042] The second carbonation method of the present invention can use carbonated water produced by injecting carbon dioxide gas at a pressure of 5 to 20 bar at a temperature of 5 to 10°C or lower, and preferably uses carbonated water produced by injecting carbon dioxide gas at a pressure of 10 bar at a temperature of 5°C or lower. Carbonated water produced by injecting carbon dioxide gas at a pressure of 10 bar at a temperature of 5°C or lower contains approximately 0.68 mol of dissolved carbon dioxide.

[0043] According to an embodiment of the present invention, 1 L of carbonated water and 500 mL of a 2.72 mol lithium hydroxide aqueous solution are mixed and reacted at a temperature of 20°C for 30 minutes, then heated to 100°C, aged for 10 minutes, and filtered to obtain approximately 39 g of high-purity lithium carbonate. In this reaction as well, it is preferable to adjust the pH of the aqueous solution to approximately 7 at the end of the reaction.

[0044] The third carbonation method of the present invention is a method using an aqueous lithium bicarbonate (LiHCO3) solution, and can be an aqueous lithium bicarbonate solution produced by reacting lithium carbonate with carbonated water or an aqueous lithium bicarbonate solution produced by reacting lithium carbonate with carbon dioxide in a pressure vessel. It is preferable to use an aqueous lithium bicarbonate solution produced by reacting lithium carbonate with carbon dioxide in a pressure vessel, because reacting lithium carbonate with carbon dioxide in a pressure vessel allows for a rapid increase in the concentration of lithium bicarbonate in the aqueous solution.

[0045] (6) Sixth step: Secondary solid-liquid separation step Solid-liquid separation is performed on the carbonation reaction solution to obtain solid lithium carbonate and liquid filtrate. The filtrate contains approximately 1,500 to 2,000 mg / L of lithium ions and is introduced into the lithium phosphate manufacturing process to produce high-purity lithium phosphate.

[0046] (7) Step 7: Pressurized carbon dioxide dissolution process The solid-phase lithium carbonate obtained in the aforementioned secondary solid-liquid separation process contains trace amounts of silicon and aluminum as impurities. When water is added to the lithium carbonate to produce a suspension, and then carbon dioxide (CO2) is injected, the lithium carbonate dissolves as lithium bicarbonate, while the silicon and aluminum impurities remain undissolved. Solid-liquid separation allows for the removal of these impurities. Specifically, when lithium carbonate and carbon dioxide come into contact, the pH of the reaction solution converges to 6-8 over time, causing the lithium carbonate to dissolve as lithium bicarbonate. At this time, the undissolved aluminum impurities (Al(OH)3), silicon impurities (SiO2), and calcium carbonate (CaCO3) are removed as solid phases using the solid-liquid separation process.

[0047] For the pressurized carbon dioxide dissolution process, the slurry concentration can be adjusted so that the amount of lithium carbonate is 2 to 12 parts by weight per 100 parts by weight of water. If the amount of lithium carbonate in the slurry is less than 2 parts by weight, the process efficiency decreases. If the amount of lithium carbonate in the slurry is more than 12 parts by weight, the time required for the lithium carbonate to dissolve completely increases, and the incompletely dissolved lithium carbonate is removed along with impurities, resulting in a decrease in yield. The solubility of lithium carbonate in carbonated water increases as the temperature decreases. The pressurized carbon dioxide dissolution process of the present invention is preferably carried out under temperature conditions of 0 to 20°C. The time required for the dissolution reaction of lithium carbonate to be completed varies depending on the pressure of the carbon dioxide gas; at 10 bar or higher, it is completed within 30 minutes, and at 1 bar, it takes about 2 hours. The pressurized carbon dioxide dissolution process can also be used in a process in which lithium carbonate produced from the solid phase of the primary solid-liquid separation process is introduced to produce high-purity lithium carbonate. The process in which the solid phase of the primary solid-liquid separation process is produced as lithium carbonate and introduced into the pressurized carbon dioxide dissolution process will be described in detail below.

[0048] (8) Eighth step: Tertiary solid-liquid separation step A tertiary solid-liquid separation step is used to separate the lithium bicarbonate aqueous solution produced using the pressurized carbonic acid dissolution step from insoluble substances such as Al(OH)3, SiO2, and CaCO3. Using this solid-liquid separation, the insoluble substances are obtained as the solid phase, and the lithium bicarbonate aqueous solution is obtained as the liquid phase.

[0049] (9) Step 9: Primary heating fractional sedimentation step The lithium bicarbonate aqueous solution obtained in the tertiary solid-liquid separation step is heated to precipitate lithium carbonate. The precipitation process is represented by chemical formula 6.

[0050] [ka]

[0051] When the reaction temperature is low and the pressure is high, the dissolution reaction of lithium carbonate proceeds and lithium bicarbonate is produced. When the reaction temperature is high and the pressure is low, lithium bicarbonate precipitates as lithium carbonate. Although lithium carbonate precipitates with just vigorous stirring or aeration, this reaction has the disadvantage of being very slow. Therefore, in the present invention, lithium carbonate is precipitated by heating the reaction solution to 80-100°C while stirring. The precipitation reaction rate of lithium carbonate varies depending on the temperature and pressure; the higher the temperature and the lower the pressure, the faster the reaction. According to an embodiment of the present invention, if an aqueous solution with a lithium carbonate (LiHCO3) concentration of 2 mol / L is heated to 100°C, the precipitation reaction is completed within 20 minutes.

[0052] (10) Tenth step: Quaternary solid-liquid separation step By performing solid-liquid separation on the reaction solution in which lithium carbonate has been recrystallized using the aforementioned heating fractional precipitation step, precipitated lithium carbonate is obtained as a solid phase. The obtained lithium carbonate is high-purity lithium carbonate with a purity of 99.9%. The aqueous solution obtained as the liquid phase (filtrate) from the solid-liquid separation can be introduced into a reverse osmosis concentration step and used for the production of high-purity lithium phosphate.

[0053] (11) Step 11: Drying process The high-purity lithium carbonate obtained by the aforementioned quaternary solid-liquid separation is dried to produce a high-purity lithium carbonate product (purity of 99.9% or higher).

[0054] The present invention comprises a 12th step of crushing waste refractory saggars to produce waste refractory saggar pulverized material, a 13th step of adding an alkaline leaching agent and water to the waste refractory saggar pulverized material and reacting them to produce a waste refractory saggar pulverized material dissolution reaction slurry, a 14th step of performing primary solid-liquid separation of the waste refractory saggar pulverized material dissolution reaction slurry, and after producing a suspension from the solid phase obtained using the primary solid-liquid separation, performing primary wet magnetic separation to perform a first magnetic deposition. Step 15: Obtain a material and a first non-magnetic material; Step 16: After producing the first non-magnetic material as a suspension, perform secondary wet magnetic separation to obtain a second magnetic material and a second non-magnetic material; Step 17: Add water and a leaching agent to the second non-magnetic material and react them to produce a lithium leaching reaction solution; Step 18: Adjust the pH of the lithium leaching reaction solution to 6-8 to produce a neutralization reaction solution; Step 17: The present invention provides a method for producing high-purity lithium carbonate from a waste refractory saggar, comprising: a 19th step of quintuple solid-liquid separation; a 20th step of reverse osmotic concentration of the filtrate obtained as a liquid phase using the quintuple solid-liquid separation; a 21st step of carbonation reaction of the concentrated liquid obtained using the reverse osmotic concentration step; a 22nd step of sextent solid-liquid separation of the reaction solution from the carbonation reaction; a 23rd step of pressurized carbonic acid dissolution reaction of lithium carbonate obtained as a solid phase using the sextent solid-liquid separation; a 24th step of tertiary solid-liquid separation of the reaction solution from the pressurized carbonic acid dissolution reaction; a 25th step of thermal fractional precipitation reaction of the filtrate obtained as a liquid phase using the tertiary solid-liquid separation; a 26th step of quaternary solid-liquid separation of the reaction solution from the thermal fractional precipitation reaction; and a 27th step of drying the solid phase obtained using the quaternary solid-liquid separation to obtain high-purity lithium carbonate.

[0055] The waste refractory crucible pulverized material dissolution reaction slurry is prepared by adding 5 to 50 parts by weight of calcium hydroxide, calcium oxide, or magnesium hydroxide, which is an alkali leaching agent, to 100 parts by weight of the waste refractory crucible pulverized material pulverized to 200# (mesh) or less, mixing 350 parts by weight of water, and reacting this at a temperature of 50 to 80 °C for 30 to 120 minutes. The leaching agent used for leaching the second non-magnetic deposit is an acid leaching agent containing one or more of sulfuric acid, nitric acid, and hydrochloric acid, or an alkali leaching agent containing one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, and magnesium hydroxide.

[0056] The reverse osmosis pressure concentration step is carried out using a batch reverse osmosis pressure equipment, and the upper limit of the operating pressure of the pump is set to 50 kg / cm 2 and the filtrate obtained as a liquid phase using the above-mentioned three-stage solid-liquid separation is concentrated until the lithium concentration becomes 10,000 to 70,000 mg / L. The pressurized carbon dioxide dissolution reaction is carried out by mixing 100 parts by weight of water and 2 to 12 parts by weight of lithium carbonate obtained as a solid phase using the above-mentioned second-stage solid-liquid separation in a pressure reaction vessel (or a closed vessel), and then blowing carbon dioxide gas (CO2) under a temperature condition of 0 to 20 °C while maintaining the pressure of the carbon dioxide gas in the reaction vessel at 1 to 25 bar and stirring for 30 minutes to 120 minutes to dissolve the lithium carbonate.

[0057] The heating and fractional precipitation reaction is characterized by heating the concentrated liquid obtained using the reverse osmosis pressure concentration to 80 to 100 °C for 20 minutes or more to precipitate lithium carbonate. The high-purity lithium carbonate is characterized by having a purity of 99.9% or more.

[0058] Hereinafter, the process of producing high-purity lithium carbonate using the solid phase obtained by the primary solid-liquid separation step, which is the third step, will be described.

[0059] (12) The 12th step: The primary wet magnetic separation step The primary wet magnetic separation step Wet magnetic separation is performed on the solid phase obtained using the primary solid-liquid separation, which is the third step described above. The primary wet magnetic separation step is preferably performed after adding water to the solid phase to produce a slurry. The water can be of industrial quality, and if the water quality is the same, the water used in the process can be reused. The purpose of the primary wet magnetic separation is to remove iron fragments (iron oxide) and iron scale that have been mixed in by abrasion during the crushing of the waste refractory saggars. Since the iron fragments and iron scale have very strong magnetizing ability, they can be removed as magnetic deposits at a magnetic flux density of approximately 100 to 500 gauss. Below 200 gauss, most of the iron fragments and iron scale are removed as magnetic deposits, but above 200 gauss, the amount of positive electrode active material mixed in along with the iron fragments and iron scale increases. Therefore, when wet magnetic separation is performed above 200 gauss, a separate magnetic separation may be required for the mixed positive electrode active material. The magnetic material separated using the primary wet magnetic separation process includes iron pieces and iron scale, while the non-magnetic material includes positive electrode active material, alumina, silica, magnesium aluminate, aluminum silicate, and lithium aluminum silicate.

[0060] (13) Step 13: Secondary wet magnetic separation process The secondary wet magnetic separation step of the present invention aims to separate positive electrode active material, including nickel oxide and cobalt oxide, from non-magnetic material obtained in the primary wet magnetic separation step, and alumina, silica, magnesium aluminate, aluminum silicate, and lithium aluminum silicate. The positive electrode active material contained in the non-magnetic material has weak magnetic or paramagnetic properties. Therefore, a magnet with a high magnetic flux density is required to recover the positive electrode active material as magnetic material. The secondary wet magnetic separation step of the present invention can use a high-gradient magnetic separator with a magnetic flux density of 10,000 gauss or more, and preferably a high-gradient magnetic separator with a magnetic flux density of 30,000 gauss or more. Furthermore, it is preferable that the high-gradient magnetic separator has a structure in which a slurry containing the particles to be separated is flowed between magnetized magnetic media. The concentration of solid matter in the slurry may be 1 to 10%. If the concentration of the solids is less than 1%, the amount of water used increases, leading to an increase in unnecessary storage tanks and a rise in energy costs. If the concentration of the solids exceeds 10%, the sorting efficiency decreases significantly. Using the secondary wet magnetic separation process, the positive electrode active material is separated as magnetic material, and the remaining composition of the waste refractory saggars from which the water-soluble lithium has been removed, such as alumina, silica, magnesium aluminate, aluminum silicate, and lithium aluminum silicate, is separated as non-magnetic material. The amount of lithium contained in lithium aluminum silicate, a sparingly soluble lithium compound that remains in the solid phase of the primary solid-liquid separation process after water leaching, is approximately 1,000 to 6,000 mg per 1 kg of crushed waste refractory saggar material.

[0061] (14) Step 14: Lithium leaching and neutralization reaction step When the sparingly soluble lithium compounds contained in the non-magnetic material from the secondary wet magnetic separation step are reacted with a leaching agent, a leached solution and leaching residue containing eluted lithium are obtained. The leaching agent may be an acid leaching agent containing one or more of sulfuric acid, nitric acid, and hydrochloric acid, or an alkaline leaching agent containing one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, and magnesium hydroxide.

[0062] When leaching lithium from poorly soluble lithium compounds using the aforementioned leaching agent, there is a problem in that it is difficult to raise the leaching rate to 95% or higher if the reaction solution temperature is below 100°C. To solve this, if the reaction temperature is raised to 100-200°C and the reaction pressure to 2-16 bar and the mixture is stirred thoroughly for more than one hour, the poorly soluble lithium compound is decomposed, and lithium can be recovered with a leaching rate of 95% or higher.

[0063] According to embodiments of the present invention, the amount of acid leaching agent added is preferably such that the pH of the reaction solution becomes 1 to 2 after the leaching reaction. When sulfuric acid is used, it can be used in amounts of 5 to 50 parts by weight per 100 parts by weight of the non-magnetic material. Preferably, 50 parts by weight of sulfuric acid is added to 100 parts by weight of the non-magnetic material, and the slurry is mixed with 350 parts by weight of water. This slurry is placed in a sealed reaction vessel, and the leaching reaction is carried out for 3 hours under a temperature of 150°C, resulting in the leaching of 97% or more of lithium. When acid is used, the insoluble matter is mostly oxides containing silicon or aluminum.

[0064] When using an alkaline leaching agent, the amount of alkaline leaching agent added is preferably 5 to 50 parts by weight per 100 parts of non-magnetic material, the reaction temperature is preferably 100 to 200°C, and the reaction time is preferably 1 to 10 hours. Alkali leaching agents are more effective when mixed with alkali metals and alkaline earth metals than when used alone. Specifically, it is preferable to mix 2 to 20 parts of alkali metal hydroxide and 3 to 30 parts of alkaline earth metal hydroxide per 100 parts of non-magnetic material.

[0065] Once the predetermined leaching time has elapsed and leaching is complete, the heating of the reaction vessel is stopped and the temperature of the reaction solution is allowed to drop below 100°C before adding the neutralizing agent. For acid leaching agents, alkali metal or alkaline earth metal hydroxides are used as neutralizing agents, and sulfuric acid is used as a neutralizing agent for alkaline leaching agents. The amount of neutralizing agent used is such that the pH of the reaction solution becomes 6-8 after the neutralization reaction is complete. When using alkaline leaching agents, they may be added to the secondary solid-liquid separation without the aforementioned neutralization reaction step.

[0066] (15) 15th step: Fifth solid-liquid separation step To separate the lithium aqueous solution and precipitate produced using the neutralization reaction step described above, a secondary solid-liquid separation step is performed on the neutralization reaction solution. When solid-liquid separation is performed on the neutralization reaction solution, the lithium aqueous solution is obtained as a liquid phase, and impurities are obtained as a solid phase. The impurities include silica and aluminum hydroxide, among others.

[0067] For alkali leaching reaction solutions that have not undergone the neutralization reaction step, a secondary solid-liquid separation step is performed to separate the lithium aqueous solution from the precipitate. When solid-liquid separation is performed on the alkali leaching reaction solution, the lithium aqueous solution is obtained as a liquid phase, and impurities are obtained as a solid phase. These impurities include silica and aluminum hydroxide. The liquid phase is introduced into the fourth step, an anion exchange step, to produce high-purity lithium carbonate.

[0068] (16) Step 16: Primary reverse osmotic concentration step The lithium concentration in the liquid phase (lithium aqueous solution) obtained by quintuple solid-liquid separation of the neutralization reaction solution is 300 to 3,000 mg / L. Recovering lithium at this concentration without concentration is inefficient. Therefore, in this invention, the lithium aqueous solution is concentrated to increase the lithium concentration before recovery. A method using a reverse osmosis filter, which has low energy costs, is preferably used for the concentration. The reverse osmosis filter in this invention is preferably a less expensive batch-type reverse osmosis system, rather than an expensive multi-stage counter-flow reverse osmosis system used in large-scale desalination processes. The lithium aqueous solution can be concentrated to a lithium concentration of 10,000 to 70,000 mg / L. Concentrating to a lower concentration than 10,000 mg / L results in excessively high energy costs for the subsequent evaporation concentration process, while concentrating to a higher concentration than 70,000 mg / L results in excessively high energy costs for applying high reverse osmotic pressure, eliminating any differentiation from the evaporation method. Preferably, the concentration can be set to 50,000 mg / L. To concentrate the lithium until the concentration reaches 50,000 mg / L, a water level adjustment sensor can be used, and the upper limit of the pump's operating pressure can be set to 50 kg / cm². 2 It can be operated with the settings configured accordingly. The treated water obtained in the primary reverse osmotic concentration process can be used as water for the 12th step, the primary wet sorting step.

[0069] (17) Step 17: Secondary carbonation reaction step A secondary carbonation reaction step is performed in which lithium carbonate (Li2CO3) is recovered by contacting the lithium-concentrated water obtained using the primary reverse osmosis concentration step with an aqueous carbonate solution containing carbonate ions. The reaction between lithium-concentrated water and the aqueous carbonate solution is represented by the following chemical formula 7.

[0070] [ka]

[0071] The carbonate aqueous solution from the carbonation reaction can be produced using one or more substances selected from sodium carbonate, potassium carbonate, and ammonium carbonate. The aqueous solution preferably has a concentration of 0.5 to 5 mol / L, and the reaction temperature is preferably 30 to 100°C. Lithium carbonate produced at temperatures below 30°C presents difficulties in the solid-liquid separation process due to its fine particle size, resulting not only in a high impurity content but also in a low lithium recovery rate.

[0072] (18) 18th step: Sixth solid-liquid separation step The slurry after the secondary carbonation reaction step is separated into solid and liquid phases to obtain solid lithium carbonate and liquid filtrate. Since the lithium carbonate may contain impurities, it is introduced into the seventh step, a pressurized carbonation dissolution step, to further increase its purity and produce high-purity lithium carbonate. The filtrate contains approximately 1,500 to 2,000 mg / L of lithium ions along with the impurities. If the impurity content in the filtrate is 5,000 mg / L or less, it is reintroduced into the seventeenth step, a secondary carbonation reaction step, to produce lithium carbonate. If the impurity content in the filtrate exceeds 5,000 mg / L, it is introduced into a phosphate precipitation step to produce high-purity lithium phosphate.

[0073] The specific embodiments described herein are merely representative of preferred aspects or examples of the present invention and do not limit the scope of the invention. It will be apparent to those skilled in the art that variations and other uses of the present invention do not depart from the scope of the invention as described in the claims herein. [Industrial applicability]

[0074] By utilizing the method for producing high-purity lithium carbonate from waste refractory saggars of the present invention, it is possible not only to reuse discarded waste refractory saggars to produce high-purity lithium carbonate that can be used in the manufacture of lithium secondary batteries, but also to reuse and industrially utilize the positive electrode active material, iron oxide, alumina, silicate, and calcium carbonate that are incidentally obtained during the manufacturing process.

Claims

1. The first step is to crush the waste refractory saggars to produce crushed waste refractory saggar material, A second step involves adding an alkaline leaching agent and water to the aforementioned pulverized waste refractory saggar and then reacting them to produce a slurry of dissolved waste refractory saggar, A third step involves primary solid-liquid separation of the slurry from the dissolved waste refractory saggar. A fourth step involves passing the filtrate obtained as a liquid phase using the primary solid-liquid separation method through an anion exchange resin to carry out an anion exchange reaction. A fifth step involves carrying out a carbonation reaction on the permeate from the anion exchange reaction to produce a carbonation reaction solution, A sixth step involves separating the carbonation reaction solution into a secondary solid-liquid solution, A seventh step involves carrying out a pressurized carbonic acid dissolution reaction on the solid phase obtained using the secondary solid-liquid separation described above, An eighth step involves separating the reaction solution of the pressurized carbon dioxide dissolution reaction into a tertiary solid-liquid solution, A ninth step involves performing a heating fractional precipitation reaction on the filtrate obtained as a liquid phase using the aforementioned tertiary solid-liquid separation, A tenth step involves performing a quaternary solid-liquid separation of the reaction solution from the aforementioned heating fractional precipitation reaction, An eleventh step involves drying the solid phase obtained using the above-mentioned quaternary solid-liquid separation to obtain high-purity lithium carbonate, A method for producing high-purity lithium carbonate from waste refractory saggars using anion exchange.

2. The method for producing high-purity lithium carbonate from waste refractory saggars using anion exchange, as described in claim 1, is characterized in that the slurry for dissolving waste refractory saggars is produced by adding 5 to 50 parts by weight of an alkaline leaching agent, such as calcium hydroxide, calcium oxide, or magnesium hydroxide, to 100 parts by weight of waste refractory saggars crushed to 200# (mesh) or less, mixing with 350 parts by weight of water, and reacting this mixture for 30 to 120 minutes under a temperature of 50 to 80°C.

3. The anion exchange resin is an anion exchange resin produced by adsorbing trimethylammonium or dimethylethanolamine onto a styrene resin having a gel structure, and the anion exchange reaction is carried out by passing the filtrate obtained as a liquid phase using the primary solid-liquid separation at a flow rate of 0.1 to 1 m / sec through an anion exchange column filled with the anion exchange resin, as described in claim 1, for producing high-purity lithium carbonate from waste refractory saggars using anion exchange.

4. A method for producing high-purity lithium carbonate from a waste refractory saggar according to claim 1, characterized in that the carbonation reaction is carried out by introducing the permeate of the anion exchange reaction into a pressure reaction vessel (or a sealed container), injecting one or more selected from carbon dioxide, carbonated water, and lithium bicarbonate aqueous solution into the permeate and allowing the reaction to proceed until the pH reaches 7, and then allowing the reaction to proceed for 20 minutes or more under temperature conditions of 80 to 100°C to terminate the reaction.

5. The pressurized carbon dioxide dissolution reaction involves mixing 100 parts by weight of water with 2 to 12 parts by weight of lithium carbonate obtained as a solid phase using the secondary solid-liquid separation method in a pressure reaction vessel (or sealed container), and then dissolving carbon dioxide (CO2) under a temperature of 0 to 20°C. 2 A method for producing high-purity lithium carbonate from a waste refractory saggar according to claim 1, characterized by dissolving the lithium carbonate by stirring for 30 to 120 minutes while blowing in a gas and maintaining the pressure of the carbon dioxide gas in the reaction vessel at 1 to 25 bar.

6. The method for producing high-purity lithium carbonate from a waste refractory saggar using anion exchange, as described in claim 1, characterized in that the heating fractional precipitation reaction is performed by heating the filtrate obtained as a liquid phase using the tertiary solid-liquid separation in the eighth step for 20 minutes or more under a temperature of 80 to 100°C to precipitate lithium carbonate.

7. The method for producing high-purity lithium carbonate from a waste refractory saggar according to claim 1, characterized in that the high-purity lithium carbonate has a purity of 99.9% or higher.

8. The twelfth step involves crushing waste refractory saggars to produce crushed waste refractory saggar material, A thirteenth step involves adding an alkaline leaching agent and water to the aforementioned pulverized waste refractory saggar and then reacting them to produce a slurry of dissolved waste refractory saggar, A 14th step involves primary solid-liquid separation of the slurry from the dissolved waste refractory saggar. A 15th step involves preparing a suspension from the solid phase obtained using the primary solid-liquid separation, and then performing primary wet magnetic separation to obtain a first magnetic material and a first non-magnetic material. A 16th step involves producing the first non-magnetic material as a suspension, followed by secondary wet magnetic separation to obtain a second magnetic material and a second non-magnetic material. A 17th step involves adding water and a leaching agent to the second non-magnetic material and then reacting them to produce a lithium leaching reaction solution, A 18th step involves adjusting the pH of the lithium leaching reaction solution to 6-8 to produce a neutralization reaction solution, A 19th step involves performing a fifth solid-liquid separation of the neutralization reaction solution, A 20th step involves performing reverse osmotic concentration on the filtrate obtained as a liquid phase using the aforementioned quintuple solid-liquid separation, A 21st step involves carrying out a carbonation reaction on the concentrated solution obtained using the reverse osmotic pressure concentration step, A 22nd step involves performing a sixth solid-liquid separation of the reaction solution from the carbonation reaction, A 23rd step involves carrying out a pressurized carbonic acid dissolution reaction on lithium carbonate obtained as a solid phase using the aforementioned sixth-order solid-liquid separation, A 24th step involves separating the reaction solution of the pressurized carbon dioxide dissolution reaction into a tertiary solid-liquid solution, A 25th step involves performing a heating fractional precipitation reaction on the filtrate obtained as a liquid phase using the tertiary solid-liquid separation described above, A 26th step involves performing a quaternary solid-liquid separation of the reaction solution from the aforementioned heating fractional precipitation reaction, A 27th step involves drying the solid phase obtained using the quaternary solid-liquid separation to obtain high-purity lithium carbonate, A method for producing high-purity lithium carbonate from waste refractory saggars, including [the specified material].

9. The method for producing high-purity lithium carbonate from waste refractory saggars according to claim 8, characterized in that the slurry for dissolving waste refractory saggars is produced by adding 5 to 50 parts by weight of an alkaline leaching agent, such as calcium hydroxide, calcium oxide, or magnesium hydroxide, to 100 parts by weight of waste refractory saggars crushed to 200# (mesh) or less, mixing with 350 parts by weight of water, and reacting this mixture for 30 to 120 minutes under a temperature of 50 to 80°C.

10. A method for producing high-purity lithium carbonate from a waste refractory saggar according to claim 8, characterized in that the leaching agent used for leaching the second non-magnetic material is an acid leaching agent containing one or more of sulfuric acid, nitric acid, and hydrochloric acid, or an alkaline leaching agent containing one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, and magnesium hydroxide.

11. The aforementioned reverse osmotic concentration process is carried out using a batch-type reverse osmotic equipment, with the upper limit of the pump's operating pressure set to 50 kg / cm². 2 A method for producing high-purity lithium carbonate from a waste refractory saggar according to claim 8, characterized by setting the parameters to such a value and concentrating the filtrate obtained as a liquid phase using the fifth solid-liquid separation of step 19 until the lithium concentration of the filtrate is 10,000 to 70,000 mg / L.

12. The pressurized carbon dioxide dissolution reaction involves mixing 100 parts by weight of water and 2 to 12 parts by weight of lithium carbonate obtained as a solid phase using the sixth solid-liquid separation in step 22 in a pressure reaction vessel (or sealed container), and then dissolving carbon dioxide (CO2) under a temperature of 0 to 20°C. 2 A method for producing high-purity lithium carbonate from a waste refractory saggar according to claim 8, characterized by dissolving the lithium carbonate by stirring for 30 to 120 minutes while blowing in a gas and maintaining the pressure of the carbon dioxide gas in the reaction vessel at 1 to 25 bar.

13. The method for producing high-purity lithium carbonate from waste refractory saggars according to claim 8, characterized in that the heat fractionation precipitation reaction involves heating the concentrated solution obtained using the reverse osmotic pressure concentration to 80 to 100°C for 20 minutes or more to precipitate lithium carbonate.

14. The method for producing high-purity lithium carbonate from a waste refractory saggar according to claim 8, characterized in that the high-purity lithium carbonate has a purity of 99.9% or higher.

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