Method for preparing high-purity lithium carbonate from waste saggar by utilizing anion exchange

Abstract

The invention provides an optimization method for recovering high-purity lithium carbonate from lithium-containing composite oxide deposited on the eroded surface of a waste sagger. Therefore, by adopting the method for preparing the high-purity lithium carbonate from the waste saggar, the waste saggar can be recycled to prepare the high-purity lithium carbonate capable of being used for preparing the lithium secondary battery, and moreover, the lithium carbonate can be used for preparing the lithium secondary battery. Cathode active materials, iron oxide, aluminum oxide, silicate and calcium carbonate obtained as by-products during the preparation process are expected to be recycled.

Description

Technical Field

[0001] The present invention relates to a method for preparing high-purity lithium carbonate from waste saggers by using anion exchange. In detail, the present invention relates to the following method: after the waste saggers are crushed and dissolved, solid-liquid separation, wet magnetic separation, anion exchange, carbonation, pressurized carbonic acid dissolution and heating step-by-step precipitation reaction are performed to prepare high-purity lithium carbonate with a purity of more than 99.9%. Background Art

[0002] The positive electrode active material of lithium secondary batteries is composed of SiO 2 、Al 2 O 3 , MgO as the main components of oxide ceramics by high-temperature firing. The above-mentioned sagger is used for repeated high-temperature firing of lithium-containing composite oxides as raw materials for positive electrode active materials. Therefore, over time, its surface is corroded, and lithium hydroxide, lithium carbonate and positive electrode active materials are deposited in the above-mentioned corroded parts. Finally, the sagger whose surface is corroded by the above-mentioned lithium hydroxide, lithium carbonate, etc. is discarded due to reduced heat resistance. The amount of waste saggers generated in South Korea is about 9,000 tons per year, but due to the popularization of mobile devices and electric vehicles, the demand for lithium secondary batteries has increased dramatically, and thus, the amount of waste saggers generated will also increase sharply.

[0003] As mentioned above, the sagger is used to prepare the positive electrode active material, and during the high-temperature sintering process, it is corroded by the lithium-containing composite oxide and loses its function. Therefore, if the lithium-containing composite oxide deposited in the eroded part can be recovered in the form of high-purity lithium sulfate, lithium carbonate or lithium phosphate from the waste sagger that has been discarded due to repeated high-temperature sintering of the lithium-containing composite oxide and reduced heat resistance, it is expected to be recycled and reused in the production process of lithium-ion secondary batteries to save production costs. However, the method of recovering high-purity lithium compounds from waste saggers is still unclear.

[0004] Patent documents and reference documents mentioned in the present specification are hereby incorporated by reference into the present specification to the same extent as if the respective documents were expressly designated individually by reference. Summary of the invention

[0005] Problems to be solved by the invention

[0006] The object of the present invention is to provide a method for recovering high-purity lithium carbonate having a purity of 99.9% or more from waste saggers discarded after high-temperature calcination when preparing positive electrode active materials for lithium secondary batteries.

[0007] Other objects and technical features of the present invention will be more specifically presented through the detailed description of the invention, the claims and the accompanying drawings.

[0008] Solutions for solving problems

[0009] The present invention provides a method for preparing high-purity lithium carbonate from waste saggers, which comprises: a first step of preparing a waste sagger crushed material by crushing the waste saggers; a second step of adding an alkali leaching agent and water to the waste sagger crushed material and reacting them to prepare a waste sagger crushed material dissolution reaction slurry; a third step of performing a first solid-liquid separation on the waste sagger crushed material dissolution reaction slurry; a fourth step of performing anion exchange reaction on a liquid phase filtrate obtained by the first solid-liquid separation through an anion exchange resin; a fifth step of performing a carbonation reaction on a liquid phase filtrate obtained by the anion exchange reaction. to prepare a carbonation reaction liquid; in step 6, performing a second solid-liquid separation on the carbonation reaction liquid; in step 7, performing a pressurized carbonation dissolution reaction on the solid phase obtained by the second solid-liquid separation; in step 8, performing a third solid-liquid separation on the reaction liquid of the pressurized carbonation dissolution reaction; in step 9, performing a heating step-by-step precipitation reaction on the liquid phase filtrate obtained by the third solid-liquid separation; in step 10, performing a fourth solid-liquid separation on the reaction liquid of the heating step-by-step precipitation reaction; and in step 11, drying the solid phase obtained by the fourth solid-liquid separation to obtain high-purity lithium carbonate.

[0010] The above-mentioned waste sagger crushed material dissolution reaction slurry is prepared by adding 5 to 50 parts by weight of calcium hydroxide, calcium oxide or magnesium hydroxide as an alkaline leaching agent relative to 100 parts by weight of the waste sagger crushed material with a size of 200 or less, mixing 350 parts by weight of water, and reacting it at a temperature of 50° C. to 80° C. for 30 to 120 minutes. The above-mentioned anion exchange resin is an anion exchange resin prepared by allowing a styrene resin having a gel structure to adsorb trimethyl ammonium or dimethyl ethanolamine. The above-mentioned anion exchange reaction is performed by passing the liquid phase filtrate obtained by the above-mentioned first solid-liquid separation through an anion exchange tower filled with the above-mentioned anion exchange resin at a flow rate of 0.1 m / sec to 1 m / sec.

[0011] In the carbonation reaction, the liquid through the anion exchange reaction is put into a pressure reaction vessel (or a closed container), and one selected from carbon dioxide, carbonated water and lithium bicarbonate aqueous solution is injected into the liquid through to react until the pH value reaches 7, and then the reaction is stopped at a temperature of 80° C. to 100° C. for more than 20 minutes to terminate the reaction. In the pressurized carbonation dissolution reaction, 100 parts by weight of water and 2 parts by weight to 12 parts by weight of the solid-phase lithium carbonate obtained by the second solid-liquid separation are mixed in the pressure reaction vessel (or a closed container), and then carbonic acid gas (CO 2) is blown into the liquid at a temperature of 0° C. to 20° C. 2) to maintain the carbon dioxide gas pressure in the reaction container at 1 bar to 25 bar, and stir for 30 minutes to 120 minutes to dissolve the above lithium carbonate.

[0012] In the above-mentioned heating step-by-step precipitation reaction, the concentrated solution obtained by the above-mentioned reverse osmosis concentration is heated at a temperature of 80°C to 100°C for more than 20 minutes to precipitate lithium carbonate. The purity of the lithium carbonate prepared by the above-mentioned preparation method is more than 99.9%.

[0013] The present invention provides a method for preparing high-purity lithium carbonate from waste saggers, which comprises: a 12th step of preparing a waste sagger crushed material by crushing the waste sagger; a 13th step of adding an alkali leaching agent and water to the waste sagger crushed material and reacting them to prepare a waste sagger crushed material dissolution reaction slurry; a 14th step of performing a first solid-liquid separation on the waste sagger crushed material dissolution reaction slurry; a 15th step of preparing a solid phase obtained by the first solid-liquid separation into a suspension, and then performing a first wet magnetic separation process to obtain a first magnetic adsorbent and a first non-magnetic adsorbent; a 16th step of preparing the first non-magnetic adsorbent into a suspension, and then performing a second wet magnetic separation process to obtain a second magnetic adsorbent and a second non-magnetic adsorbent; a 17th step of adding water and a leaching agent to the second non-magnetic adsorbent and reacting them to prepare a lithium leaching reaction solution; a 18th step of separating the lithium leaching reaction solution from the p The H value is adjusted to 6 to 8 to prepare a neutralization reaction liquid; step 19, performing the fifth solid-liquid separation on the above neutralization reaction liquid; step 20, performing reverse osmosis concentration on the liquid filtrate obtained by the above fifth solid-liquid separation; step 21, performing a carbonation reaction on the concentrated liquid obtained by the above reverse osmosis concentration process; step 22, performing the sixth solid-liquid separation on the reaction liquid of the above carbonation reaction; step 23, performing a pressurized carbonic acid dissolution reaction on the solid lithium carbonate obtained by the above sixth solid-liquid separation; step 24, performing the third solid-liquid separation on the reaction liquid of the above pressurized carbonic acid dissolution reaction; step 25, performing a heating step-by-step precipitation reaction on the liquid filtrate obtained by the above third solid-liquid separation; step 26, performing the fourth solid-liquid separation on the reaction liquid of the above heating step-by-step precipitation reaction; and step 27, drying the solid phase obtained by the above fourth solid-liquid separation to obtain high-purity lithium carbonate.

[0014] The above-mentioned waste sagger crushed material dissolution reaction slurry is prepared by adding 5 to 50 parts by weight of calcium hydroxide, calcium oxide or magnesium hydroxide as an alkaline leaching agent to 100 parts by weight of the waste sagger crushed material with a size of less than 200# (mesh), mixing with 350 parts by weight of water, and reacting it at a temperature of 50°C to 80°C for 30 to 120 minutes. The leaching agent used in the leaching of the above-mentioned second non-magnetic adsorbent is an acid leaching agent including one or more of sulfuric acid, nitric acid and hydrochloric acid; or an alkaline leaching agent including one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide and magnesium hydroxide.

[0015] The above reverse osmosis concentration process uses a batch reverse osmosis device and sets the upper limit of the pump working pressure to 50kg / cm 2 The lithium concentration of the liquid phase filtrate obtained by the third solid-liquid separation is 10000 mg / L to 70000 mg / L. In the pressurized carbonic acid dissolution reaction, 100 parts by weight of water and 2 parts by weight to 12 parts by weight of the solid phase lithium carbonate obtained by the second solid-liquid separation are mixed in a pressure reaction vessel (or a closed container), and then carbonic acid gas (CO) is blown into the pressure reaction vessel at a temperature of 0°C to 20°C. 2 ) to maintain the carbon dioxide gas pressure in the reaction container at 1 bar to 25 bar, and stir for 30 minutes to 120 minutes to dissolve the above lithium carbonate.

[0016] In the above-mentioned heating step-by-step precipitation reaction, the concentrated solution obtained by the above-mentioned reverse osmosis concentration is heated at a temperature of 80°C to 100°C for more than 20 minutes to precipitate lithium carbonate. The purity of the lithium carbonate prepared by the above-mentioned preparation method is more than 99.9%.

[0017] Effects of the Invention

[0018] The present invention provides an optimized method for recovering high-purity lithium carbonate from lithium-containing composite oxides deposited on the eroded surface of discarded old saggers. Therefore, by adopting the method for preparing high-purity lithium carbonate from waste saggers of the present invention, the discarded old saggers can be recycled to prepare high-purity lithium carbonate that can be used to prepare lithium secondary batteries, and the positive electrode active material, iron oxide, aluminum oxide, silicate and calcium carbonate obtained as by-products in the preparation process can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The method for preparing high-purity lithium carbonate from waste saggers of the present invention is schematically shown.

[0020] Figure 2 The results of analyzing the mineral components of the waste sagger of the present invention using XRD are shown.

[0021] Figure 3 The following is a scanning electron microscope (SEM) image of the waste sagger crushed material showing the overall particle size distribution and the structure of the particle surface. DETAILED DESCRIPTION

[0022] The present invention relates to a method for preparing high-purity lithium carbonate from waste saggers by using anion exchange. The saggers are corroded and destroyed by lithium hydroxide or lithium carbonate as they are repeatedly used. The purpose of the present invention is to recover lithium carbonate, a lithium compound with high added value, with high purity from waste saggers that have never been recovered and discarded. The waste saggers are fired ceramic containers for positive electrode active materials for secondary batteries, and the main component is SiO 2 、Al 2 O 3 Table 1 shows the components of the used saggers used for sintering positive electrode materials NCA (sample name: SG1) and NCM (sample name: SG2).

[0023] Components SG1(NCA) SG2(NCM) <![CDATA[Li 2 O(as Li)]]> 4.52(2.1)％ 1.89(0.88)％ NiO 0.13％ 0.16％ <![CDATA[Co 3 THE 4 ]]> 0.01％ 0.02％ <![CDATA[SiO 2 ]]> 49.38％ 30.73％ <![CDATA[Al 2 THE 3 ]]> 38.25％ 51.38％ CaO 0.48％ 0.52％ MgO 5.37％ 13.63％ <![CDATA[Fe 2 THE 3 ]]> 0.33％ 0.54％ <![CDATA[Na 2 The]]> 0.32％ 0.12％ <![CDATA[K 2 The]]> 0.30％ 0.19％ Others (etc.) 0.91％ 0.82％

[0024] The analysis results confirmed that the lithium (Li) content of SG1 and SG2 was 2.1% and 0.88% respectively, which was high. If converted into lithium carbonate content, it was equivalent to SG1 = 11.17% and SG2 = 4.68%. In addition, the nickel and cobalt contents were also confirmed to be 0.13% to 0.16% and 0.01% to 0.02% respectively, which were confirmed to have sufficient recovery value.

[0025] The above-mentioned waste sagger is composed of mullite, cordierite, alumina, quartz, magnesium aluminate, lithium silicate, lithium aluminum oxide, lithium aluminum silicate, etc. Among the components of the above-mentioned waste sagger, the substances that cause the sagger to be destroyed are lithium silicate, lithium aluminum oxide, lithium aluminum silicate, etc.

[0026] The present invention provides a method for preparing high-purity lithium carbonate from waste saggers, which comprises: a first step of preparing a waste sagger crushed material by crushing the waste sagger; a second step of adding an alkali leaching agent and water to the waste sagger crushed material and reacting the waste sagger crushed material to prepare a waste sagger crushed material dissolution reaction slurry; a third step of performing a first solid-liquid separation on the waste sagger crushed material dissolution reaction slurry; a fourth step of performing anion exchange reaction on a liquid phase filtrate obtained by the first solid-liquid separation through an anion exchange resin; and a fifth step of performing a carbonation reaction on a liquid phase filtrate obtained by the anion exchange reaction. to prepare a carbonation reaction liquid; in step 6, performing a second solid-liquid separation on the above-mentioned carbonation reaction liquid; in step 7, performing a pressurized carbonation dissolution reaction on the solid phase obtained by the above-mentioned second solid-liquid separation; in step 8, performing a third solid-liquid separation on the reaction liquid of the above-mentioned pressurized carbonation dissolution reaction; in step 9, performing a heating step-by-step precipitation reaction on the liquid phase filtrate obtained by the above-mentioned third solid-liquid separation; in step 10, performing a fourth solid-liquid separation on the reaction liquid of the above-mentioned heating step-by-step precipitation reaction; and in step 11, drying the solid phase obtained by the above-mentioned fourth solid-liquid separation to obtain high-purity lithium carbonate.

[0027] The above-mentioned waste sagger crushed material dissolution reaction slurry is prepared by adding 5 to 50 parts by weight of calcium hydroxide, calcium oxide or magnesium hydroxide as an alkaline leaching agent relative to 100 parts by weight of the waste sagger crushed material with a size of 200 or less, mixing 350 parts by weight of water, and reacting it at a temperature of 50° C. to 80° C. for 30 to 120 minutes. The above-mentioned anion exchange resin is an anion exchange resin prepared by allowing a styrene resin having a gel structure to adsorb trimethyl ammonium or dimethyl ethanolamine. The above-mentioned anion exchange reaction is performed by passing the liquid phase filtrate obtained by the above-mentioned first solid-liquid separation through an anion exchange tower filled with the above-mentioned anion exchange resin at a flow rate of 0.1 m / sec to 1 m / sec.

[0028] In the carbonation reaction, the liquid through the anion exchange reaction is put into a pressure reaction vessel (or a closed container), and one selected from carbon dioxide, carbonated water and lithium bicarbonate aqueous solution is injected into the liquid through to react until the pH value reaches 7, and then the reaction is stopped at a temperature of 80° C. to 100° C. for more than 20 minutes to terminate the reaction. In the pressurized carbonation dissolution reaction, 100 parts by weight of water and 2 parts by weight to 12 parts by weight of the solid-phase lithium carbonate obtained by the second solid-liquid separation are mixed in the pressure reaction vessel (or a closed container), and then carbonic acid gas (CO 2) is blown into the liquid at a temperature of 0° C. to 20° C. 2) to maintain the carbon dioxide gas pressure in the reaction container at 1 bar to 25 bar, and stir for 30 minutes to 120 minutes to dissolve the above lithium carbonate.

[0029] In the above-mentioned heating step-wise precipitation reaction, the concentrated solution obtained by the above-mentioned reverse osmosis concentration is heated at a temperature of 80°C to 100°C for more than 20 minutes to precipitate lithium carbonate. The purity of the above-mentioned high-purity lithium carbonate is more than 99.9%.

[0030] Embodiments of the present invention

[0031] Hereinafter, the method for preparing high-purity lithium carbonate from waste saggers by an anion exchange process of the present invention will be described in detail according to the process.

[0032] (1) Process 1: Waste sagger crushing process

[0033] The waste sagger is crushed into powder of less than 200#. When the above-mentioned waste sagger is micronized at one time, there is a problem of too low crushing efficiency. Therefore, preferably, after a jaw crusher is used for primary crushing to be less than 1mm, a ball mill is used for secondary crushing to be less than 200# (mesh). Although the above-mentioned waste sagger has high compression strength, it has the characteristic of poor impact resistance. The crushing of the above-mentioned waste sagger can be applied to an impact crusher, but the crushed particles with a high hardness front surface are produced, which leads to an increase in the wear of the crusher parts, thereby increasing the cost. Therefore, in the present invention, a jaw crusher with easy replacement of parts and low cost is used in the primary crushing process, and a ball mill is used in the secondary crushing process. Preferably, in order to improve the crushing efficiency, a heavy crusher such as an impact crusher can be configured before the secondary crushing process.

[0034] Process 2: Dissolution of crushed waste saggers

[0035] The waste sagger pulverized by the first process contains lithium-containing substances such as lithium hydroxide, lithium carbonate, lithium silicate, lithium aluminum oxide or lithium aluminum silicate. Most of the above-mentioned lithium-containing substances are water-soluble, but some substances including lithium aluminum silicate have low solubility in water, and thus have the problem of being difficult to dissolve with water alone. In order to solve the above-mentioned problem, the present invention applies a waste sagger pulverized material dissolution process in which the above-mentioned waste sagger pulverized material is mixed with an alkali leaching agent selected from the group consisting of one or more of alkali metal hydroxides, alkali metal carbonates or alkaline earth metal hydroxides and water, and then heated. In the waste sagger pulverized material dissolution process of the present invention, the waste sagger pulverized material is heated together with the above-mentioned alkali leaching agent for dissolution, so that lithium aluminum silicate and the like with low solubility in water can also be decomposed and dissolved, thereby having the advantage of increasing the recovery rate of lithium. The decomposition and dissolution reaction of the lithium-containing material with low solubility has a tendency to increase reactivity in proportion to the concentration and temperature of the alkali. If an alkaline leaching agent containing an alkali metal salt is used for this purpose, the concentration of silicon and aluminum increases, so a separate process for removing them is required. In contrast, if a leaching agent prepared from an oxide or hydroxide of an alkaline earth metal and water is used, soluble silicon or aluminum and insoluble salts are formed, and therefore, the following advantages are provided: the decomposition of lithium aluminum silicate is promoted, and it helps to keep the concentration of silicon and aluminum in the solution low, and reacts with lithium carbonate with low solubility to generate lithium hydroxide and insoluble carbonate with high solubility, thereby improving the leaching rate of lithium. Therefore, in the waste sagger crushing material dissolution process of the present invention, calcium hydroxide, calcium oxide or magnesium hydroxide is used as a leaching agent to promote lithium extraction, and its addition amount is based on 100 parts by weight of the waste sagger, preferably 5 to 50 parts by weight. It has been confirmed that the above-mentioned waste sagger crushed material dissolution process takes more than 6 hours to complete the reaction at a temperature below 20°C; at a temperature of 50°C, the reaction is completed within 2 hours; at a temperature of 80°C, the reaction is completed within 30 minutes. In addition, at about 100°C, the reaction is completed within 10 minutes, but there is a problem of a large amount of energy loss due to the evaporation of water. Therefore, the preferred waste sagger crushed material dissolution process of the present invention reacts at a temperature of 50°C to 80°C for 30 minutes to 120 minutes.

[0036] In summary, in the preferred waste sagger crushing material dissolution process of the present invention, the waste sagger crushing material slurry containing 5 to 50 parts by weight of calcium hydroxide, calcium oxide or magnesium hydroxide as a leaching agent relative to 100 parts by weight of the waste sagger crushing material crushed to 200# (mesh) or less is heated to 50°C to 80°C, and reacted for 30 to 120 minutes. For reference, under the same conditions, adding 5% to 50% of the alkali metal hydroxide equivalent to the amount used together with the alkaline earth metal hydroxide (or oxide) will increase the leaching rate and leaching rate of lithium by about 5%. The above method becomes the preferred method when the increase in process costs can be tolerated.

[0037] (3) The third process: the first solid-liquid separation process

[0038] The dissolving reaction liquid of the above-mentioned waste sagger crushed material is subjected to solid-liquid separation (first solid-liquid separation). The first solid-liquid separation uses a sedimentation tank, a filter press, a spiral filter, a centrifuge, etc., or a combination of two or more of them, so as to improve its efficiency. The solid phase obtained by the above-mentioned first solid-liquid separation includes the positive electrode active material and the refractory composition, and the liquid phase (filtrate) includes lithium (Li + ), aluminum (Al(OH) 4 - ), Silicon (H 2 SiO 4 2- ). The filtrate is put into anion exchange process and carbonation process to prepare high-purity lithium carbonate, the solid phase is put into a multi-stage magnetic separation process, a lithium leaching process and a carbonation reaction process, so as to recover the lithium contained inside as lithium carbonate, and the recovered lithium carbonate is put into the pressurized carbonic acid dissolution process performed after the anion exchange process and carbonation process of the filtrate, so as to prepare high-purity lithium carbonate. Below, the high-purity lithium carbonate preparation process using the filtrate is first described, and then the high-purity lithium carbonate preparation process using the solid phase is described.

[0039] Process 4: Anion Exchange Process

[0040] The filtrate obtained in the first solid-liquid separation process is a strongly alkaline lithium hydroxide aqueous solution with a pH of more than 12. The lithium hydroxide aqueous solution contains lithium hydroxide and Al(OH) 4 - , H 2 SiO 4 2- and Ca 2+In the present invention, in order to remove the above impurities, an anion exchange process is performed by passing it through an anion exchange resin. The anion exchange resin can be a resin that can be used in a strong base field. Preferably, a styrene resin having a gel structure is used to adsorb trimethyl ammonium or dimethyl ethanolamine to include OH - The above-mentioned anion exchange process can be performed in an ion exchange tower with a height of more than 80 cm of the above-mentioned anion exchange resin layer, and can be performed at room temperature by flowing the above-mentioned lithium hydroxide aqueous solution at a flow rate of 0.1m / sec to 1m / sec. The above-mentioned ion exchange tower is preferably a continuous ion exchange tower designed to contact with the treatment solution in a countercurrent manner and to regenerate the resin used for a certain period of time before being put into use. If the filtrate (lithium hydroxide aqueous solution) obtained in the above-mentioned first solid-liquid separation process is injected into the above-mentioned ion exchange tower, the above-mentioned impurities are combined with the anion exchange resin and left, and the lithium hydroxide aqueous solution is obtained as a flow-through, thereby improving the purity.

[0041] The anion exchange resin is used for a certain period of time to desorb and regenerate the adsorbed anions, and the backwash solution generated at this time is sent to the waste sagger crushing material dissolution process as the second process for reuse, and the regenerated anion exchange resin is transferred to the anion exchange tower for reuse. At this time, water and slaked lime can be added to the conventional backwash solution and put into the waste sagger crushing material dissolution process.

[0042] (5) Process 5: Primary Carbonation Reaction Process

[0043] The liquid passing through the ion exchange tower is a lithium hydroxide aqueous solution from which impurities have been removed. In the present invention, in order to obtain lithium carbonate (Li 2 CO 3 ), and a carbonation reaction process is performed. The above-mentioned carbonation reaction process can be applied to: injecting carbon dioxide (CO) into the lithium hydroxide aqueous solution 2 ) gas to perform a first carbonation method (refer to Chemical Formula 1); a second carbonation method (refer to Chemical Formula 2) to perform a second carbonation method (refer to Chemical Formula 2) to perform a third carbonation method (refer to Chemical Formula 3) to perform a third carbonation method (refer to Chemical Formula 3) to perform a fourth carbonation method (refer to Chemical Formula 4) to perform a fourth carbonation method (refer to Chemical Formula 4) to perform a fifth carbonation method (refer to Chemical Formula 5) to perform a fifth carbonation method (refer to Chemical Formula 5) to perform a third carbonation method (refer to Chemical Formula 5) to perform a third carbonation method (refer to Chemical Formula 5) to perform a third carbonation method (refer to Chemical Formula 5) to perform a third carbonation method (refer to Chemical Formula 5) to perform a third carbonation method (refer to Chemical Formula 3 ...

[0044] [Chemical formula 1]

[0045] 2LiOH+CO 2→Li 2 CO 3 +H 2 O

[0046] [Chemical formula 2]

[0047] 2LiOH+H 2 CO 3 →Li 2 CO 3 +2H 2 O

[0048] [Chemical formula 3]

[0049] LiOH+LiHCO 3 →Li 2 CO 3 +H 2 O

[0050] [Chemical formula 4]

[0051] 2LiOH+Na 2 CO 3 →Li 2 CO 3 +2NaOH

[0052] [Chemical formula 5]

[0053] 2LiOH+K 2 CO 3 →Li 2 CO 3 +2KOH

[0054] The 4th carbonating method and the 5th carbonating method in the above-mentioned carbonating method have the worry of producing impurities such as sodium and potassium respectively, therefore, have the problem of needing to remove the above-mentioned impurities by additional process.Therefore, the present invention uses the first carbonating method, the second carbonating method or the 3rd carbonating method that do not produce the above-mentioned impurity worry, preferably, uses the first carbonating method that injects carbon dioxide gas.

[0055] According to an embodiment of the present invention, in the first carbonation method, 1 liter of lithium hydroxide aqueous solution concentrated to 2 mol / L concentration is put into a 1.5 liter pressure reaction tank, and carbon dioxide gas is blown in at a flow rate of 1L / minute and stirred, and the lithium carbonate generation reaction ends in about 22 minutes. In this reaction, the concentration of lithium hydroxide aqueous solution is preferably 0.5mol / L to 5mol / L. If the concentration of lithium hydroxide aqueous solution is lower than 0.5mol / L, the amount of lithium carbonate generated is too small to reduce the process efficiency, and if the concentration is greater than 5mol / L, the viscosity of the aqueous solution is too high and there is a problem of being unable to remove impurities. The first carbonation method of the present invention is an exothermic reaction, and when a 20°C aqueous solution is reacted, the temperature at the end of the reaction is about 35°C. Therefore, no additional heating operation is required during the reaction, but if the temperature rises, the solubility of lithium carbonate is reduced, which not only improves the yield of lithium carbonate, but also makes the crystal growth rate faster, thereby producing the effect of recrystallization leading to an increase in purity, and therefore, the final reaction liquid temperature is preferably 80°C to 100°C.

[0056] Carbonation reaction liquid of the present invention is the strong alkali state of more than pH 12 in the initial stage of reaction, reduces gradually along with the carrying out of reaction, and converges to pH 7.The generation of Quilonum Retard is completed at pH 9 or so, and under the pH state lower than pH 9, Quilonum Retard is dissolved into lithium bicarbonate (lithium bicarbonate) again.Therefore, it is good that carbonation reaction finishes between pH 8 to 10.But, even if the pH value that reaction proceeds to reaction solution becomes 7, the lithium bicarbonate generated is recovered in subsequent process, therefore has yield and can not reduce, on the contrary in the reverse osmosis concentration process that performs afterwards, makes the advantage of film damaged minimization, so it is also preferred that the pH value that reaction proceeds to reaction solution becomes 7.

[0057] In summary, in the primary carbonation reaction process of the present invention, a lithium hydroxide aqueous solution with a concentration of 0.5 mol / L to 5 mol / L is added to a pressure reaction vessel (or a closed container), and carbonic acid gas is injected thereto to react until the pH value becomes 7, and then the temperature of the reaction solution is heated to 80°C to 100°C, and the carbonation reaction is terminated by staying at this temperature for more than 20 minutes.

[0058] The second carbonation method of the present invention can use carbonated water prepared by injecting carbonic acid gas at a temperature of 5°C to 10°C or less at a pressure of 5 bar to 20 bar, preferably, carbonated water prepared by injecting carbonic acid gas at a temperature of 5°C or less at a pressure of 10 bar. Carbonated water prepared by injecting carbonic acid gas at a temperature of 5°C or less at a pressure of 10 bar contains about 0.68 mol of carbon dioxide dissolved therein.

[0059] According to an embodiment of the present invention, 1L of the carbonated water and 500ml of 2.72mol lithium hydroxide aqueous solution are mixed, reacted at 20°C for 30 minutes, heated to 100°C, and aged for 10 minutes, and then filtered to obtain about 39g of high-purity lithium carbonate. When the reaction is completed, the pH value of the aqueous solution is preferably adjusted to 7.

[0060] The third carbonation method of the present invention is to use lithium bicarbonate (LiHCO 3 ) aqueous solution, a lithium bicarbonate aqueous solution prepared by reacting lithium carbonate and carbonated water or a lithium bicarbonate aqueous solution prepared by reacting lithium carbonate and carbon dioxide in a pressure vessel can be used. The lithium bicarbonate aqueous solution prepared by reacting lithium carbonate and carbon dioxide in a pressure vessel is preferably used because if lithium carbonate and carbon dioxide are reacted in a pressure vessel, the concentration of lithium bicarbonate in the aqueous solution can be rapidly increased.

[0061] (6) Process 6: Second solid-liquid separation process

[0062] The carbonation reaction liquid is subjected to solid-liquid separation to obtain solid lithium carbonate and liquid filtrate. The filtrate contains about 1500 mg / L to 2000 mg / L of lithium ions, which is put into a lithium phosphate preparation process to prepare high-purity lithium phosphate.

[0063] (7) Process 7: Pressurized Carbonate Dissolution Process

[0064] The solid lithium carbonate obtained in the second solid-liquid separation process contains trace amounts of silicon and aluminum as impurities. If water is added to the lithium carbonate to prepare a suspension and then carbon dioxide gas (CO 2 ), the lithium carbonate is dissolved into lithium bicarbonate, and the silicon and aluminum impurities are not dissolved and remain. Therefore, if solid-liquid separation is performed, the impurities can be removed. In detail, if lithium carbonate is in contact with carbonic acid gas, the pH of the reaction solution converges to 6 to 8 over time, and the lithium carbonate is dissolved as lithium bicarbonate. On the contrary, the undissolved aluminum impurities (Al(OH) 3 ), silicon impurities (SiO 2 ) and calcium carbonate (CaCO 3 ) is removed in the solid phase through a solid-liquid separation process.

[0065] In order to perform the above-mentioned pressurized carbonic acid dissolution process, the slurry concentration can be adjusted so that the lithium carbonate becomes 2 to 12 parts by weight relative to 100 parts by weight of water. If the lithium carbonate of the above-mentioned slurry is less than 2 parts by weight, the process efficiency is reduced. If the lithium carbonate of the above-mentioned slurry is greater than 12 parts by weight, the time required to completely dissolve the lithium carbonate becomes longer, and the lithium carbonate that is not completely dissolved is removed together with the impurities, thereby causing the problem of reduced yield. The solubility of lithium carbonate in carbonated water increases with decreasing temperature. Preferably, the pressurized carbonic acid dissolution process of the present invention should be performed at a temperature of 0°C to 20°C. The time when the dissolution reaction of lithium carbonate ends varies according to the pressure of the carbonic acid gas, and ends within 30 minutes at more than 10 bars, and takes about 2 hours at 1 bar. The above-mentioned pressurized carbonic acid dissolution process can also be used for the following process: lithium carbonate prepared in a solid phase by the first solid-liquid separation process is put into the process of preparing lithium carbonate in the solid phase and putting it into the above-mentioned pressurized carbonic acid dissolution process. The following content describes in detail the process in which the solid phase of the above-mentioned first solid-liquid separation process is prepared as lithium carbonate and put into the above-mentioned pressurized carbonic acid dissolution process.

[0066] (8) Process 8: The third solid-liquid separation process

[0067] The lithium bicarbonate aqueous solution and impurity Al(OH) prepared by the pressurized carbonic acid dissolution process are removed by the third solid-liquid separation process. 3 、SiO 2 、CaCO 3 By the above solid-liquid separation, an insoluble matter is obtained as a solid phase, and a lithium bicarbonate aqueous solution is obtained as a liquid phase.

[0068] (9) Process No. 9: One-step heating precipitation process

[0069] The lithium bicarbonate aqueous solution obtained in the third solid-liquid separation process is heated to precipitate lithium carbonate. The precipitation process is represented by Chemical Formula 6.

[0070] [Chemical formula 6]

[0071]

[0072] If the reaction temperature is low and the pressure is high, lithium carbonate dissolution reaction is carried out to generate lithium bicarbonate. If the reaction temperature is high and the pressure is low, lithium bicarbonate is precipitated as lithium carbonate. In the above reaction, lithium carbonate can be precipitated only by simple vigorous stirring or aeration, but it has the disadvantage of being very slow. Therefore, in the present invention, the reaction solution is heated to 80°C to 100°C while stirring to precipitate lithium carbonate. The precipitation reaction rate of lithium carbonate varies according to temperature and pressure. The higher the temperature and the lower the pressure, the faster the reaction rate. According to an embodiment of the present invention, if lithium carbonate (LiHCO 3 ) The precipitation reaction can be completed within 20 minutes by heating an aqueous solution with a concentration of 2 mol / L to 100°C.

[0073] (10) Process 10: The fourth solid-liquid separation process

[0074] If the reaction solution for recrystallizing lithium carbonate is subjected to solid-liquid separation by the above-mentioned heating step-by-step precipitation process, the precipitated lithium carbonate is obtained as a solid phase. The lithium carbonate obtained as above is a high-purity lithium carbonate with a purity of 99.9%. The aqueous solution obtained as a liquid phase (filtrate) from the above-mentioned solid-liquid separation can be put into a reverse osmosis concentration process to prepare lithium phosphate.

[0075] (11) Process 11: Drying process

[0076] The high-purity lithium carbonate obtained from the fourth solid-liquid separation is dried to obtain a high-purity lithium carbonate (purity above 99.9%) product.

[0077] The present invention provides a method for preparing high-purity lithium carbonate from waste saggers, which comprises: a 12th step of preparing a waste sagger crushed material by crushing the waste sagger; a 13th step of adding an alkali leaching agent and water to the waste sagger crushed material and reacting them to prepare a waste sagger crushed material dissolution reaction slurry; a 14th step of performing a first solid-liquid separation on the waste sagger crushed material dissolution reaction slurry; a 15th step of preparing a solid phase obtained by the first solid-liquid separation into a suspension, and then performing a first wet magnetic separation process to obtain a first magnetic adsorbent and a first non-magnetic adsorbent; a 16th step of preparing the first non-magnetic adsorbent into a suspension, and then performing a second wet magnetic separation process to obtain a second magnetic adsorbent and a second non-magnetic adsorbent; a 17th step of adding water and a leaching agent to the second non-magnetic adsorbent and reacting them to prepare a lithium leaching reaction solution; a 18th step of separating the lithium leaching reaction solution from the p The H value is adjusted to 6 to 8 to prepare a neutralization reaction liquid; step 19, performing the fifth solid-liquid separation on the above neutralization reaction liquid; step 20, performing reverse osmosis concentration on the liquid filtrate obtained by the above fifth solid-liquid separation; step 21, performing a carbonation reaction on the concentrated liquid obtained by the above reverse osmosis concentration process; step 22, performing the sixth solid-liquid separation on the reaction liquid of the above carbonation reaction; step 23, performing a pressurized carbonic acid dissolution reaction on the solid lithium carbonate obtained by the above sixth solid-liquid separation; step 24, performing the third solid-liquid separation on the reaction liquid of the above pressurized carbonic acid dissolution reaction; step 25, performing a heating step-by-step precipitation reaction on the liquid filtrate obtained by the above third solid-liquid separation; step 26, performing the fourth solid-liquid separation on the reaction liquid of the above heating step-by-step precipitation reaction; and step 27, drying the solid phase obtained by the above fourth solid-liquid separation to obtain high-purity lithium carbonate.

[0078] The above-mentioned waste sagger crushed material dissolution reaction slurry is prepared by adding 5 to 50 parts by weight of calcium hydroxide, calcium oxide or magnesium hydroxide as an alkaline leaching agent to 100 parts by weight of the waste sagger crushed material with a size of less than 200# (mesh), mixing with 350 parts by weight of water, and reacting it at a temperature of 50°C to 80°C for 30 to 120 minutes. The leaching agent used in the leaching of the above-mentioned second non-magnetic adsorbent is an acid leaching agent including one or more of sulfuric acid, nitric acid and hydrochloric acid; or an alkaline leaching agent including one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide and magnesium hydroxide.

[0079] The above reverse osmosis concentration process uses a batch reverse osmosis device and sets the upper limit of the pump working pressure to 50kg / cm 2 The lithium concentration of the liquid phase filtrate obtained by the third solid-liquid separation is 10000 mg / L to 70000 mg / L. In the pressurized carbonic acid dissolution reaction, 100 parts by weight of water and 2 parts by weight to 12 parts by weight of the solid phase lithium carbonate obtained by the second solid-liquid separation are mixed in a pressure reaction vessel (or a closed container), and then carbonic acid gas (CO) is blown into the pressure reaction vessel at a temperature of 0°C to 20°C. 2 ) to maintain the carbon dioxide gas pressure in the reaction container at 1 bar to 25 bar, and stir for 30 minutes to 120 minutes to dissolve the above lithium carbonate.

[0080] In the above-mentioned heating step-wise precipitation reaction, the concentrated solution obtained by the above-mentioned reverse osmosis concentration is heated at a temperature of 80°C to 100°C for more than 20 minutes to precipitate lithium carbonate. The purity of the above-mentioned high-purity lithium carbonate is more than 99.9%.

[0081] Next, a process for producing high-purity lithium carbonate using the solid phase obtained from the first solid-liquid separation process as the third process will be described.

[0082] (12) Process 12: First wet magnetic separation process

[0083] The solid phase obtained by the first solid-liquid separation as the third process is subjected to a wet magnetic separation. The first wet magnetic separation process is preferably performed by adding water to the solid phase to prepare a slurry. The water only needs to be of industrial quality. If the water quality is the same, the water used in the process can also be reused. The purpose of the wet magnetic separation is to remove iron flakes (iron oxide) or iron scales mixed in due to wear during the grinding of the waste sagger. The iron flakes or iron scales have very strong magnetization, so they can be removed as magnetic adsorbents at a magnetic flux density of about 100 to 500 gauss. Below 200 gauss, most of the iron flakes and iron scales as magnetic adsorbents are removed, but in the case of more than 200 gauss, the mixing rate of iron flakes and iron scales as magnetic adsorbents and positive active materials is increased. Therefore, in the case of wet magnetic separation at more than 200 gauss, a separate magnetic separation of the mixed positive active materials is required. The magnetically adsorbed materials separated by the first wet magnetic separation process include iron flakes and iron scales, and the non-magnetically adsorbed materials include positive electrode active materials, aluminum oxide, silicon dioxide, magnesium aluminate, aluminum silicate and lithium aluminum silicate.

[0084] (13) Process 13: Second wet magnetic separation process

[0085] The purpose of the second wet magnetic separation process of the present invention is to separate positive electrode active materials including nickel oxide and cobalt oxide, etc. and aluminum oxide, silicon dioxide, magnesium aluminate, aluminum silicate and lithium aluminum silicate from the non-magnetic adsorbents of the first wet magnetic separation process. The positive electrode active materials included in the above non-magnetic adsorbents have the properties of weak magnetism or paramagnetism. Therefore, in order to recover the above positive electrode active materials as magnetic adsorbents, a magnet with a high magnetic flux density is required. The second wet magnetic separation process of the present invention can use a high gradient magnetic separator with a magnetic flux density of more than 10,000 gauss, and preferably, a high gradient magnetic separator with a magnetic flux density of more than 30,000 gauss can be used. In addition, the above high gradient magnetic separator preferably has a structure that allows the slurry including the particles to be separated to flow between the magnetized magnetic media. The solid concentration of the above slurry can be 1% to 10%. If the concentration of the above solid matter is less than 1%, as the amount of water used increases, there are problems such as an increase in unnecessary storage tanks and an increase in energy costs. If the concentration of the above solid matter is greater than 10%, there is a problem of significantly reduced sorting efficiency. The positive electrode active material is sorted out as a magnetic adsorbent through the above-mentioned second wet magnetic separation process, and the remaining waste sagger composition of alumina, silicon dioxide, magnesium aluminate, aluminum silicate and lithium aluminum silicate (lithium aluminum silicate) are sorted out as non-magnetic adsorbents. After water leaching, the amount of lithium contained in the lithium aluminum silicate as a sparingly soluble lithium compound remaining in the solid phase of the first solid-liquid separation process is about 1000 mg to 6000 mg per 1 kg of waste sagger crushed material.

[0086] (14) Process 14: Lithium leaching and neutralization reaction process

[0087] If the sparingly soluble lithium compound included in the non-magnetic adsorbent of the second wet magnetic separation process is reacted with a leaching agent, a leaching solution and a leaching residue from which lithium is eluted are obtained. The leaching agent may be an acid leaching agent including one or more of sulfuric acid, nitric acid and hydrochloric acid, or an alkaline leaching agent including one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide and magnesium hydroxide.

[0088] When using the above-mentioned leaching agent to leach lithium from a sparingly soluble lithium compound, if the temperature of the reaction solution is below 100° C., it is difficult to increase the leaching rate to more than 95%. To solve the above problem, if the reaction temperature is set to 100° C. to 200° C. and the reaction pressure is set to 2 bar to 16 bar and the mixture is stirred for more than 1 hour, the sparingly soluble lithium compound can be decomposed to recover lithium at a leaching rate of more than 95%.

[0089] According to an embodiment of the present invention, the amount of acid leaching agent added is preferably an amount that makes the pH value of the reaction solution become 1 to 2 after the leaching reaction. In the case of using sulfuric acid, 5 to 50 parts by weight can be used relative to 100 parts by weight of the above-mentioned non-magnetic adsorbent. Preferably, a slurry of 50 parts by weight of sulfuric acid and 350 parts by weight of water is added to a closed container relative to 100 parts by weight of the above-mentioned non-magnetic adsorbent, and the leaching reaction is performed at a temperature of 150°C for 3 hours, so that more than 97% of lithium can be leached. In the case of using acid, most of the insoluble substances are oxides including silicon or aluminum.

[0090] In the case of using an alkaline leaching agent for leaching, the amount of the alkaline leaching agent added is 5 to 50 parts by weight relative to 100 parts by weight of the non-magnetic adsorbent, the reaction temperature is 100°C to 200°C, and the reaction time is preferably 1 hour to 10 hours. Compared with the case of using an alkaline leaching agent alone, it is more effective to use a mixture of alkali metals and alkaline earth metals. Specifically, it is preferred to use 2 to 20 parts of alkali metal hydroxides and 3 to 30 parts of alkaline earth metal hydroxides relative to 100 parts of the non-magnetic adsorbent.

[0091] If the leaching is completed after the specified leaching time, the heating of the reaction tank is stopped to make the temperature of the reaction solution below 100°C, and a neutralizer is added. For the neutralizer of the acid leaching agent, an alkali metal or alkaline earth metal hydroxide is used, and for the neutralizer of the alkaline leaching agent, sulfuric acid is used. The amount of the neutralizer used is an amount that makes the pH value of the reaction solution 6 to 8 after the neutralization reaction is completed. In the case of using an alkaline leaching agent, the second solid-liquid separation can be carried out without the above-mentioned neutralization reaction process.

[0092] (15) Process 15: The fifth solid-liquid separation process

[0093] In order to separate the lithium aqueous solution and the precipitate generated by the neutralization reaction process, a second solid-liquid separation process is performed on the neutralization reaction solution. If the neutralization reaction solution is subjected to solid-liquid separation, a liquid lithium aqueous solution is obtained, and solid impurities are obtained. The impurities include silicon dioxide and aluminum hydroxide.

[0094] For the alkaline leaching reaction liquid that has not been subjected to the above-mentioned neutralization reaction process, a second solid-liquid separation process is performed to separate the lithium aqueous solution and the precipitate. If the above-mentioned alkaline leaching reaction liquid is subjected to solid-liquid separation, a liquid-phase lithium aqueous solution is obtained, and solid-phase impurities are obtained. The above-mentioned impurities include silicon dioxide and aluminum hydroxide. The liquid phase is put into the anion exchange process as the fourth process to prepare high-purity lithium carbonate.

[0095] (16) Process 16: Single reverse osmosis concentration process

[0096] The concentration of lithium contained in the liquid phase (lithium aqueous solution) obtained by the fifth solid-liquid separation of the neutralization reaction solution is 300 mg / L to 3000 mg / L. When the lithium contained in the above concentration is recovered without concentration, the efficiency is too low. Therefore, in the present invention, lithium recovery is performed after the lithium concentration is increased by concentrating the above lithium aqueous solution. As the above concentration method, it is preferred to use a reverse osmosis filter with low energy costs. The reverse osmosis filter of the present invention preferably uses a cheaper batch reverse osmosis device rather than the expensive multi-stage countercurrent reverse osmosis device used in the large-capacity desalination process. The concentration of the above lithium aqueous solution can be performed in a manner that the lithium concentration becomes 10000 mg / L to 70000 mg / L. If it is concentrated to a concentration lower than 10000 mg / L, the energy cost of the evaporation concentration process as a subsequent process is too much. If the lithium is concentrated to a concentration higher than 70000 mg / L, the energy cost consumed when applying a high reverse osmotic pressure is too much, so that the difference with the evaporation method disappears. Preferably, the concentration can be carried out until the lithium concentration reaches 50,000 mg / L. In order to concentrate until the lithium concentration reaches 50,000 mg / L, a water level adjustment sensor can be used, and the upper limit of the operating pressure of the pump can be set to 50 kg / cm 2 The treated water obtained in the above-mentioned primary reverse osmosis concentration process can be used as water for the primary wet separation process of the above-mentioned twelfth process.

[0097] (17) Process 17: Secondary Carbonation Reaction Process

[0098] The lithium carbonate (LiCO) is recovered by contacting the lithium concentrated water obtained by the above-mentioned primary reverse osmosis concentration process with a carbonate aqueous solution containing carbonate ions. 2 CO 3 The reaction of lithium concentrated water and carbonate aqueous solution is represented by the following chemical formula 7.

[0099] [Chemical formula 7]

[0100] Li 2 SO 4 +Na 2 CO 3 →Li 2 CO 3 +Na 2 SO 4

[0101] The carbonate aqueous solution for the carbonation reaction can be prepared by using one or more selected from sodium carbonate, potassium carbonate and ammonium carbonate, the concentration of the aqueous solution is preferably 0.5 mol / L to 5 mol / L, and the reaction temperature is preferably 30° C. to 100° C. The particle size of lithium carbonate generated at a temperature lower than 30° C. is tiny, which not only makes it difficult to carry out a solid-liquid separation process, but also has a high impurity content and a problem of reduced lithium recovery rate.

[0102] (18) Process 18: The sixth solid-liquid separation process

[0103] The slurry at the end of the secondary carbonation reaction process is subjected to solid-liquid separation to obtain lithium carbonate of the solid phase and the filtrate of the liquid phase. The lithium carbonate may contain impurities, and therefore, in order to further improve the purity, it is put into the pressurized carbonic acid dissolution process of the 7th process to be prepared as high-purity lithium carbonate. The filtrate contains about 1500mg / L to 2000mg / L of lithium ions together with the impurities. When the impurity content of the filtrate is below 5000mg / L, it is put into the secondary carbonation reaction process of the 17th process again to prepare lithium carbonate, and when the impurity content of the filtrate is greater than 5000mg / L, it is put into the phosphoric acid precipitation process to prepare high-purity lithium phosphate.

[0104] The specific embodiments described in this specification represent preferred embodiments or examples of the present invention, and the scope of the present invention is not limited thereto. It is obvious to those skilled in the art that modifications and other uses of the present invention will not exceed the scope of the invention described in the claims of this specification.

[0105] Industrial Applicability

[0106] By adopting the method for preparing high-purity lithium carbonate from waste saggers of the present invention, the discarded waste saggers can be recycled to prepare high-purity lithium carbonate that can be used to prepare lithium secondary batteries, and the positive electrode active material, iron oxide, aluminum oxide, silicate and calcium carbonate obtained as by-products in the preparation process can be recycled.

Claims

1. A method for preparing high-purity lithium carbonate from waste saggers, comprising: Step 1, preparing a waste sagger crushed material by crushing the waste sagger; In the second step, an alkali leaching agent and water are added to the crushed waste sagger, and the mixture is reacted to prepare a dissolution reaction slurry of the crushed waste sagger; Step 3, performing a first solid-liquid separation on the dissolution reaction slurry of the waste sagger crushed material; Step 4, performing anion exchange reaction on the liquid phase filtrate obtained by the first solid-liquid separation through anion exchange resin; Step 5, performing a carbonation reaction on the liquid obtained by the anion exchange reaction to prepare a carbonation reaction liquid; Step 6, performing a second solid-liquid separation on the carbonation reaction liquid; Step 7, performing a pressurized carbonic acid dissolution reaction on the solid phase obtained by the second solid-liquid separation; Step 8, performing a third solid-liquid separation on the reaction liquid of the pressurized carbonic acid dissolution reaction; Step 9, performing a heating stepwise precipitation reaction on the liquid phase filtrate obtained by the third solid-liquid separation; Step 10, performing a fourth solid-liquid separation on the reaction solution of the heating stepwise precipitation reaction; as well as In step 11, the solid phase obtained by the fourth solid-liquid separation is dried to obtain high-purity lithium carbonate.

2. The method for preparing high-purity lithium carbonate from waste saggers according to claim 1, characterized in that: The waste sagger crushed material dissolution reaction slurry is prepared by adding 5 to 50 parts by weight of calcium hydroxide, calcium oxide or magnesium hydroxide as an alkaline leaching agent to 100 parts by weight of the waste sagger crushed material with a size of 200 or less, mixing with 350 parts by weight of water, and reacting it at a temperature of 50° C. to 80° C. for 30 to 120 minutes.

3. The method for preparing high-purity lithium carbonate from waste saggers according to claim 1, characterized in that: The anion exchange resin is an anion exchange resin prepared by allowing a styrene resin having a gel structure to adsorb trimethylamine or dimethylethanolamine, and the anion exchange reaction is performed by passing the liquid filtrate obtained by the first solid-liquid separation through an anion exchange tower filled with the anion exchange resin at a flow rate of 0.1 m / sec to 1 m / sec.

4. The method for preparing high-purity lithium carbonate from waste saggers according to claim 1, characterized in that: In the carbonation reaction, the anion exchange reaction liquid is put into a pressure reaction vessel (or a closed container), and one or more selected from carbon dioxide, carbonated water and lithium bicarbonate aqueous solution are injected into the liquid to react until the pH value reaches 7, and then the reaction is terminated by staying at a temperature of 80° C. to 100° C. for more than 20 minutes.

5. The method for preparing high-purity lithium carbonate from waste saggers according to claim 1, characterized in that: In the pressurized carbonic acid dissolution reaction, after mixing 100 parts by weight of water and 2 parts by weight to 12 parts by weight of solid lithium carbonate obtained by the second solid-liquid separation in a pressure reaction vessel (or a closed container), carbonic acid gas (CO2) is blown into the pressure vessel at a temperature of 0°C to 20°C to maintain the carbonic acid gas pressure in the reaction vessel at 1 bar to 25 bar, and the lithium carbonate is dissolved by stirring for 30 minutes to 120 minutes.

6. The method for preparing high-purity lithium carbonate from waste saggers according to claim 1, characterized in that: In the heating stepwise precipitation reaction, the concentrated solution obtained by the reverse osmosis concentration is heated at a temperature of 80° C. to 100° C. for more than 20 minutes to precipitate lithium carbonate.

7. The method for preparing high-purity lithium carbonate from waste saggers according to claim 1, characterized in that: The purity of the high-purity lithium carbonate is above 99.9%.

8. A method for preparing high-purity lithium carbonate from waste saggers, comprising: Step 12, preparing the waste sagger crushed material by crushing the waste sagger; Step 13, after adding an alkali leaching agent and water to the waste sagger crushed material, the alkali leaching agent and water are reacted to prepare a waste sagger crushed material dissolution reaction slurry; Step 14, performing a first solid-liquid separation on the dissolution reaction slurry of the crushed waste sagger; Step 15, after preparing the solid phase obtained by the first solid-liquid separation into a suspension, performing a wet magnetic separation to obtain a first magnetically adsorbed substance and a first non-magnetic adsorbed substance; Step 16, after preparing the first non-magnetic adsorbent into a suspension, performing a second wet magnetic separation to obtain a second magnetic adsorbent and a second non-magnetic adsorbent; Step 17, adding water and a leaching agent to the second non-magnetic adsorbent and reacting them to prepare a lithium leaching reaction solution; Step 18, adjusting the pH value of the lithium leaching reaction solution to 6 to 8 to prepare a neutralization reaction solution; Step 19, performing a fifth solid-liquid separation on the neutralization reaction liquid; Step 20, performing reverse osmosis concentration on the liquid filtrate obtained by the fifth solid-liquid separation; Step 21, performing a carbonation reaction on the concentrated liquid obtained by the reverse osmosis concentration process; Step 22, performing a sixth solid-liquid separation on the reaction liquid of the carbonation reaction; Step 23, performing a pressurized carbonic acid dissolution reaction on the solid-phase lithium carbonate obtained by the sixth solid-liquid separation; Step 24, performing a third solid-liquid separation on the reaction liquid of the pressurized carbonic acid dissolution reaction; Step 25, performing a heating stepwise precipitation reaction on the liquid phase filtrate obtained by the third solid-liquid separation; Step 26, performing a fourth solid-liquid separation on the reaction solution of the heating stepwise precipitation reaction; as well as In step 27, the solid phase obtained by the fourth solid-liquid separation is dried to obtain high-purity lithium carbonate.

9. The method for preparing high-purity lithium carbonate from waste saggers according to claim 8, characterized in that: The waste sagger crushed material dissolution reaction slurry is prepared by adding 5 to 50 parts by weight of calcium hydroxide, calcium oxide or magnesium hydroxide as an alkaline leaching agent to 100 parts by weight of the waste sagger crushed material with a size of 200 or less, mixing with 350 parts by weight of water, and reacting it at a temperature of 50° C. to 80° C. for 30 to 120 minutes.

10. The method for preparing high-purity lithium carbonate from waste saggers according to claim 8, characterized in that: The leaching agent used in the leaching of the second non-magnetic adsorbent is an acid leaching agent including one or more of sulfuric acid, nitric acid and hydrochloric acid; or an alkaline leaching agent including one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide and magnesium hydroxide.

11. The method for preparing high-purity lithium carbonate from waste saggers according to claim 8, characterized in that: The reverse osmosis concentration process uses a batch reverse osmosis device and sets the upper limit of the pump working pressure to 50kg / cm 2 The filtrate is concentrated until the lithium concentration of the liquid phase filtrate obtained by the third solid-liquid separation reaches 10,000 mg / L to 70,000 mg / L.

12. The method for preparing high-purity lithium carbonate from waste saggers according to claim 8, characterized in that: In the pressurized carbonic acid dissolution reaction, after mixing 100 parts by weight of water and 2 parts by weight to 12 parts by weight of solid lithium carbonate obtained by the second solid-liquid separation in a pressure reaction vessel or a closed container, carbonic acid gas, i.e., CO2, is blown into the pressure vessel at a temperature of 0°C to 20°C to maintain the carbonic acid gas pressure in the reaction vessel at 1 bar to 25 bar, and stirring is performed for 30 minutes to 120 minutes to dissolve the lithium carbonate.

13. The method for preparing high-purity lithium carbonate from waste saggers according to claim 8, characterized in that: In the heating stepwise precipitation reaction, the concentrated solution obtained by the reverse osmosis concentration is heated at a temperature of 80° C. to 100° C. for more than 20 minutes to precipitate lithium carbonate.

14. The method for preparing high-purity lithium carbonate from waste saggers according to claim 8, characterized in that: The purity of the high-purity lithium carbonate is above 99.9%.

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