Method for Separating and Recovering Cathode Material, Anode Material and Lithium from Waste Lithium-Ion Batteries

Abstract

The present invention relates to a method for separating and recovering a cathode metal, a negative electrode material, and lithium from a spent lithium-ion battery, comprising the steps of: mixing black mass of the spent lithium-ion battery with calcium carbonate (CaCO3) and then heat-treating the mixture to obtain a heat-treated product; separating the mixed solution, obtained by diluting the heat-treated product with process water, into a floating product, a precipitate, and a process solution by flotation; and recovering graphite from the floating product, a cathode material from the precipitate, and lithium from the process solution. According to the method of the present invention, a graphite negative electrode material used in the spent lithium-ion battery, a cathode material such as nickel, cobalt, and manganese, and a lithium metal used as a charge carrier can all be separated and recovered with high yield in a single process.

Description

Technology Field

[0001] This research was conducted with funding from the Ministry of Environment and supported by the Korea Environmental Industry & Technology Institute's Used Battery Safety Management and Remanufacturing Distribution Circulation Technology Development Project (Development of Used Battery Pretreatment Technology and Global Localization Technology for Reducing Emissions of Environmental Pollutants such as Harmful Gases and Wastewater, RS-2025-02172969).

[0002] The present invention relates to a method for separating and recovering cathode metal, anode material, and lithium from spent lithium-ion batteries. More specifically, the invention relates to a method for simultaneously recovering cathode metal, anode material, and lithium from spent lithium-ion batteries with a high recovery rate and high purity by mixing black mass and calcium carbonate, then heat-treating the mixture, and then separating the heat-treated mixture into a floating material, a precipitate, and a process solution by flotation. Background Technology

[0003] With the recent proliferation of electric vehicles and large electronic devices, the volume of used lithium-ion batteries is increasing rapidly; accordingly, research on technologies to efficiently recover valuable metals, including lithium, from spent lithium-ion batteries is actively underway.

[0004] For example, U.S. Patent Publication No. US2024 / 0170749A1 discloses a method for precipitating and recovering lithium carbonate (Li2CO3) by heating a lithium-containing solution recovered from a used lithium-ion battery and utilizing the inverse temperature characteristics of lithium solubility.

[0005] In addition, International Patent Publication No. WO2019 / 060996A1 and European Patent Publication No. EP 3688834 A1 propose a method of separating transition metals by crushing and solvent-treating spent lithium-ion batteries and then undergoing an acid leaching process, and precipitating lithium carbonate from the remaining solution by injecting sodium carbonate (Na2CO3) and heating.

[0006] German Patent Publication DE102018117237A1 discloses a hydrometallurgy process in which an acid leaching solution is prepared from black mass of spent lithium-ion batteries, transition metals are separated by stepwise precipitation, and lithium is finally recovered as lithium carbonate.

[0007] Meanwhile, Korean registered patent No. 10-2757061 proposes a method to obtain a high-purity lithium compound by using a solvent extractant such as a β-diketone series to suppress impurities from a lithium-containing solution, and thereby to produce lithium carbonate.

[0008] International Patent Publication No. WO2021 / 226719A1 discloses a technology for acid-leaching a black mass containing an electrode active material, saturating the filtrate with lithium, and precipitating and recovering lithium by a carbonation reaction.

[0009] In addition, European Patent Publication No. EP4427856A1 discloses a technology for selectively recovering graphite from black mass, and a method for separating graphite and metal components by combining ozone pretreatment and flotation processes. This serves as an upstream technology for the lithium recovery process and can contribute to the efficient separation of cathode materials, anode materials, and lithium components.

[0010] The methods described above all relate to the recovery of specific materials, such as lithium ions or cathode materials (graphite), from spent lithium-ion batteries; however, if additional materials other than the target substances are to be recovered, separate reactions or processes must be added. Accordingly, there is an ongoing need to develop a method capable of simultaneously recovering cathode materials, cathode materials, and lithium from spent lithium-ion batteries. Prior art literature

[0011] US Patent Publication No. US2024 / 0170749A1 (Published May 23, 2024) International Patent Publication No. WO2019 / 060996A1 (Published April 4, 2019) European Patent Publication No. EP 3688834 A1 (Published August 14, 2024) German Patent Publication No. DE102018117237A1 (Published January 23, 2020) Republic of Korea Registered Patent No. 10-2757061 (Published January 21, 2025) International Patent Publication No. WO2021 / 226719A1 (Published November 18, 2021) European Patent Publication No. EP4427856A1 (Published September 11, 2024) The problem to be solved

[0012] The objective of the present invention is to overcome the problems of the aforementioned prior art and to provide a method for simultaneously separating and recovering cathode metal, anode material, and lithium from spent lithium-ion batteries with a high recovery rate and high purity. means of solving the problem

[0013] To achieve the above objective, the present invention provides a separation and recovery method for separating and recovering a positive electrode metal, a negative electrode material, and lithium from a spent lithium-ion battery, comprising the steps of: mixing the black mass of the spent lithium-ion battery with calcium carbonate (CaCO3) and then heat-treating it to obtain a heat-treated product; separating the mixed solution, which is obtained by diluting the heat-treated product with process water, into a floating product, a precipitate, and a process solution by flotation; and recovering graphite from the floating product, the positive electrode material from the precipitate, and lithium from the process solution.

[0014] The positive electrode material of the above lithium-ion battery comprises a lithium metal oxide or a lithium iron phosphate-based compound; the charge carrier is an aqueous solution containing lithium ions; and the negative electrode material may comprise graphite.

[0015] The residual impurity content of the above black mass may be 7% by weight or less.

[0016] The number of moles of calcium carbonate (CaCO3) mixed with the black mass may be 0.6 to 1 times the number of moles of lithium present in the black mass.

[0017] The above heat treatment can be performed at a temperature of 400 to 600°C.

[0018] The method further includes a step of magnetically separating the heat-treated material between the heat treatment and the flotation separation, wherein the magnetic separation can separate the metal contained in the anode material that has become ferromagnetic by the heat treatment.

[0019] The concentration of the black mass in the above mixed solution may be 10 to 20 weight percent.

[0020] The concentration of lithium ions in the above process solution may be 2,000 to 3,000 ppm.

[0021] A collector and a foaming agent may be added to the above mixed solution.

[0022] The above-mentioned catcher may be a non-polar oil.

[0023] The additional amount of the above collector may be 0.1 to 1 part by weight based on 100 parts by weight of graphite content in the mixture.

[0024] The above foaming agent may be methylisobutylcarbinol.

[0025] The additional amount of the foaming agent may be 0.1 to 1 part by weight based on 100 parts by weight of graphite content in the mixture.

[0026] The pH of the above mixed solution may be 10 or less.

[0027] A process of filtering the process solution, adding process water to the remaining precipitate to leach out the lithium salt, and then filtering may be added one or more times.

[0028] To achieve the above objective, the present invention provides a separation and recovery method for separating and recovering lithium from a spent lithium-ion battery, comprising the steps of: mixing black mass of a spent lithium-ion battery with calcium carbonate (CaCO3) and then heat-treating to obtain a heat-treated mixture; separating a process solution from a mixed solution obtained by diluting the heat-treated mixture with process water, excluding suspended solids and precipitates; and recovering lithium from the process solution.

[0029] To achieve the above objective, the present invention provides a separation and recovery method for separating and recovering lithium from a spent lithium-ion battery, comprising the steps of: mixing black mass of the spent lithium-ion battery with calcium carbonate (CaCO3) and then heat-treating to form a heat-treated mixture; magnetically separating the heat-treated mixture; separating a process solution from a mixed solution obtained by diluting the heat-treated mixture with process water after magnetic separation, excluding suspended solids and precipitates; and recovering lithium from the process solution. Effects of the invention

[0030] According to the method of the present invention, graphite anode material, cathode material such as nickel, cobalt, and manganese, and lithium metal used as a charge carrier can all be separated and recovered from waste lithium-ion batteries with high yield in a single process. Brief explanation of the drawing

[0031] FIG. 1 is a block diagram illustrating each process of the recovery method of the present invention. Figure 2 shows the results of thermogravimetric analysis of black mass prepared in the example under a nitrogen atmosphere. Figure 3 is the result of X-ray diffraction analysis of a black mass obtained by heat-treating the black mass (A) prepared in the example at temperatures of 400°C (B), 500°C (C), and 600°C (D) for 1 hour in a nitrogen atmosphere. Figure 4 shows the free energy (Gibb's free energy, ΔG) of lithium carbonation reactions occurring during the heat treatment process as a function of temperature. oThese are graphs showing the changes. Figure 5 shows graphs representing the magnetic separation results for heat-treated materials. Figure 6 shows the results of electron microscope observations of the black mass (A) after heat treatment and the suspended matter (B) and precipitate (C) after flotation in the example. Figure 7 shows the X-ray diffraction analysis results for the black mass after heat treatment (A) and the precipitate after flotation (B) of the example. Figure 8 is a graph showing the molar ratio of lithium and nickel in the precipitate collected according to the time of flotation of the black mass before heat treatment, the black mass after heat treatment, and the black mass after heat treatment. Figure 9 is an electron microscope image showing the cathode material particles in the heat-treated black mass and the cathode material particles in the flotation sediment. Figure 10 shows the X-ray diffraction analysis results of the precipitate recovered by heat-treating the process filtrate of black mass flotation after heat treatment. Specific details for implementing the invention

[0032] A method for separating and recovering a positive electrode metal, lithium metal, and a negative electrode material from a spent lithium-ion battery according to the present invention will be described below with reference to the attached drawings.

[0033] FIG. 1 is a block diagram illustrating each process of the recovery method of the present invention. Referring to FIG. 1, the recovery method according to the present invention comprises the steps of: mixing black mass of a spent lithium-ion battery with calcium carbonate (CaCO3) and then heat treating (S1); separating the mixed solution, which is obtained by diluting the heat-treated mixture with process water, into a floating substance, a precipitate, and a process solution by flotation (S2); and recovering graphite from the floating substance, a cathode material from the precipitate, and lithium from the process solution (S3).

[0035] The first step of the recovery method of the present invention is a step (S1) of mixing the black mass of a spent lithium-ion battery with calcium carbonate (CaCO3) and then heat-treating it.

[0036] In the present invention, the lithium-ion battery for which the positive electrode material, graphite, and lithium ions are to be recovered comprises a positive electrode material composed of a lithium metal oxide or a lithium iron phosphate-based compound, a charge carrier being an aqueous solution containing lithium ions, and a negative electrode material composed of graphite.

[0037] In the present invention, black mass refers to a mixed powder of electrode active materials obtained from spent lithium-ion batteries after physical pretreatment (grinding, classification, etc.).

[0038] Electrolyte (primarily organic solvents and electrolytes such as LiPF6) remains inside the cell pouches of spent lithium-ion batteries. Therefore, if crushing or heat treatment processes are performed immediately, there is a risk of explosion and fire due to the generation of electrolyte vapors and gases; thus, the electrolyte must be safely removed in advance.

[0039] The removal of the electrolyte is typically carried out under low-pressure and high-temperature conditions. Vacuum conditions are applied to lower the oxygen concentration, thereby reducing the risk of fire, while simultaneously allowing for the rapid evacuation of solvent vapors. High-temperature conditions are used to stably remove volatile byproducts while preventing the decomposition or incomplete evaporation of the electrolyte components.

[0040] The removal of the electrolyte is performed, for example, at a pressure of 10 Torr or less and a temperature of 150°C or higher. The lithium-ion battery electrolyte contains EC (ethylene carbonate, bp 248℃), DEC (diethyl carbonate, bp 127℃), DMC (dimethyl carbonate, bp 90℃) etc. are mixed. At temperatures below 150℃, the amount of residual substances such as EC and DEC with high boiling points is large, so the removal efficiency decreases.

[0041] Under the above conditions, more than 90% of the electrolyte is removed. If the removal of the electrolyte is not more than 90%, there is a risk of battery explosion and fire during the next step, the grinding or heat treatment process.

[0042] Cell pouches from which the electrolyte has been removed are crushed and then classified to prepare black mass (BM) from which impurities (Al, Cu, etc.) have been removed.

[0043] In the present invention, mechanical crushing methods such as knife mills, hammer mills, and ball mills may be applied for crushing. After the crushing process, a black mass is obtained in which the cathode material powder (NCM, LCO, etc.), graphite, and current collector metal (Al, Cu) are mixed. In the crushing process, the metal foil (Al foil, Cu foil) remains as large crumpled pieces, and the active material is broken into small pieces.

[0044] Subsequently, the crushed mixture is classified through mesh screening in the classification process to filter out large impurities (foreign substances), including metal foil (Al, Cu), etc.

[0045] In one embodiment of the present invention, the residual impurity content of the black mass is preferably controlled to 7% or less, more preferably 5% or less, and even more preferably 3% or less. The impurity content can be controlled by the degree of grinding in the grinding process or by selecting the mesh size of the sieve used in the classification process. If the residual impurity content exceeds 7%, there is a problem in that the efficiency of the lithium carbonation reaction is reduced as oxidation and melting reactions of the metal surface occur during the heat treatment process described later, which interferes with or competes with the reaction with CaO and CO2.

[0047] The above-mentioned prepared black mass is mixed with calcium carbonate (CaCO3) and then heat-treated.

[0048] In this stage, the binder (Polyvinylidene fluoride: PVDF) used to combine the cathode and anode materials is removed, and at the same time, the lithium present in the black mass is carbonated through a series of reactions described below.

[0050] (1) Decarboxylation of calcium carbonate: CaCO3(s) → CaO(s) + CO2(g)

[0051] (2) Carbonation of lithium metal oxides: LiMO2(s) + CO2(g) * Li2CO3(s) + M(s)

[0052] (2-1) Li2O(s) + CO2(g) → Li2CO3(s)

[0053] (2-2) 2LiMO2(s) + 3CO(g) → 2M(s) + Li2CO3(s) + 2CO2(g)

[0054] (2-3) 6LiMO2(g) + 5C →6M(s) + 3Li2CO3(s) + CO2(g) + CO(g)

[0055] (3) Impurity stabilization reaction: 2F + CaO(g) →CaF2(s)

[0057] The above reaction is preferably carried out under an inert atmosphere, such as nitrogen gas or argon gas.

[0058] In reaction (1), limestone is decomposed into quicklime (CaO) and carbon dioxide (CO2) at high temperature, and the generated carbon dioxide reacts with lithium in the subsequent reaction (2) to produce lithium carbonate (chemical species only are indicated, ignoring chemical equivalents). The carbonation reaction of reaction (2) is substantially the sum of reactions (2-1) to (2-3), and the generated lithium carbonate is water-soluble.

[0059] Additionally, in reaction (3), fluoride ions (F) in the black mass react with quicklime to be fixed as stable insoluble CaF₂.

[0060] The formation of CaF2 inhibits the formation of LiF generated during the heat treatment of black mass. The reason is 500 o C and 600 o Standard Gibbs free energy of formation of CaF2 and LiF in C (G o f) This is because CaF2 is -1,070 (kJ / mol) and -1,0563 (kJ / mol), and LiF is -534 (kJ / mol) and -525 (kJ / mol). Inhibiting the formation of LiF can improve the formation rate of Li2CO3 from Li.

[0061] In one embodiment of the present invention, the amount of calcium carbonate (CaCO3) mixed with the black mass is 0.6 to 1 times the number of moles of lithium present in the black mass on a molar basis. If the amount of calcium carbonate (CaCO3) does not reach 0.6 times the number of moles of lithium, it reacts with the black mass organic carbon and some graphite to produce lithium carbonate (Equation 2-3). On the other hand, if the amount of calcium carbonate (CaCO3) exceeds 1 time the number of moles of lithium present in the black mass, the excess CaCO3 does not fully react even after heat treatment and remains as residual CaCO3 or CaO; this unnecessary residue is mixed into the black mass and filtrate, leading to a problem where the impurity content increases. Residual Ca 2+ When ions dissolve into the process solution, in the concentration process described later, Ca 2+ The purity of the finally recovered Li2CO3 is reduced due to the co-precipitation of ions.

[0062] In one embodiment of the present invention, the heat treatment is performed at a temperature of 400 to 600°C. The (1) decarbonation of calcium carbonate and (2) carbonation reaction of lithium metal oxide by the heat treatment are temperature-dependent reactions. If the heat treatment temperature is below 400°C, the decomposition of CaCO3 does not occur sufficiently, resulting in a shortage of CaO and CO2, and consequently, the lithium conversion reaction (carbonation reaction) does not proceed smoothly. Furthermore, the decomposition of the PVDF polymer used as a binder does not occur completely, resulting in a shortage of carbon sources for the progress of the reaction (2-3). On the other hand, if the heat treatment temperature exceeds 600°C, carbon components and aggregates are generated through the melting reaction of the cathode material, which causes a decrease in the recovery rate of the cathode material in the subsequent flotation process.

[0063] In another embodiment of the present invention, a magnetic separation step may be performed after heat treatment and before flotation. Some metals of the anode material, such as nickel, may be converted into ferromagnetic materials as they are reduced at high temperatures during the heat treatment process. Additionally, magnetic separation may be performed after flotation. By performing magnetic separation before or after flotation, some metals can be separated.

[0064] The second step in the recovery method of the present invention is a step (S2) of adding process water (water) to the heat-treated material to mix the mixture solution and separating the mixture into suspended matter, precipitate, and process solution.

[0065] The present invention is characterized by separating the mixture into a floating substance, a precipitate, and a process solution by adding bubbles to a mixed solution in a slurry state, to which water is added to the mixture heat-treated in the above-described S1 step. Flotation is a wet separation method that separates mixed solid particles by utilizing the difference in hydrophobicity of the particle surface in mineral processing and recycling processes.

[0066] In one embodiment of the present invention, it is preferable that the amount of black mass in the mixed solution be controlled to 10 to 20 weight percent. If the amount of black mass in the mixed solution is less than 10 weight percent, the frequency of particle-bubble collisions decreases, which lowers the recovery rate of graphite and reduces the efficiency of reagents (collectors and foaming agents), leading to an increase in process costs. On the other hand, if it exceeds 20 weight percent, the slurry viscosity increases, resulting in poor bubble formation, reduced separation efficiency between graphite and cathode material, and increased processing load in the filtration and washing processes.

[0067] In one embodiment of the present invention, the concentration of lithium ions in the mixed solution during the flotation process is preferably 2,000 to 3,000 ppm. If the lithium ion concentration is less than 2,000 ppm, the lithium recovery rate decreases and the concentration efficiency drops. On the other hand, if it exceeds 3,000 ppm, the processing load of the filtration process increases due to the co-precipitation of impurities, and the purity of the final lithium product decreases.

[0068] In the present invention, the floating of graphite can be promoted by adding a frother and a collector to the mixed solution.

[0069] A foaming agent is added to form and maintain fine and stable bubbles in the liquid phase during the flotation process. For example, alcohol-based foaming agents such as methyl isobutyl carbinol (MIBC), isoamyl alcohol, and α-terpineol are preferred for use in the process of the present invention. The amount of foaming agent added in the flotation process according to the present invention is preferably 10 to 100 ppm based on the total amount of the mixed solution. If the amount of foaming agent added is less than 10 ppm, bubble generation is insufficient, resulting in larger and more unstable bubbles, which lowers the graphite adhesion efficiency and consequently causes a problem of a low recovery rate. On the other hand, if it exceeds 100 ppm, excessive bubble stabilization leads to the formation of highly viscous froth, which increases the co-floating of unnecessary particles and causes a problem of reduced processing efficiency in the filtration and washing processes.

[0070] The collector acts to ensure that the graphite is stably attached to the bubbles by adsorbing to the surface of the graphite particles and enhancing their hydrophobicity. For this purpose, non-polar hydrocarbons such as kerosene, paraffin oil, diesel oil, and naphtha may be used as collectors. In the flotation process according to the present invention, the amount of collector added is preferably 0.1 to 1 weight percent based on the weight of the graphite in the black mass. If the amount of collector added is less than 0.1 weight percent, the hydrophobicity of the graphite particle surface is not sufficiently enhanced, resulting in reduced bubble attachment efficiency and, consequently, a problem of reduced graphite recovery rate. On the other hand, if it exceeds 1 weight percent, the non-selective flotation of unnecessary particles (such as cathode materials) increases due to excessive hydrophobicity, and the foam becomes excessively viscous, leading to a problem of reduced processing efficiency in the filtration and washing processes.

[0071] The mixed solution, with a black mass concentration of 10 to 20 weight percent, is strongly basic with a pH of about 11 to 12. According to repeated experiments by the inventors, it was confirmed that lowering the pH of the mixed solution increases the buoyancy of graphite.

[0072] In one embodiment of the present invention, it is preferable that the pH of the mixed solution obtained by diluting the heat-treated material with water be adjusted to 11 or lower. The pH may be adjusted, for example, using an inorganic acid such as sulfuric acid or hydrochloric acid.

[0074] Separation of floating matter can be carried out by methods known in the art, such as scraping off the upper foam layer using a scraper, rotary arm, etc., or sucking up the foam using a vacuum suction device or a low-pressure pump.

[0075] After the suspended solids are separated, the remaining process solution and precipitate can be separated by simple separation means such as filtering.

[0076] The third step of the recovery method of the present invention is a step (S3) of recovering graphite from the suspended matter, a cathode material from the precipitate, and lithium from the process solution.

[0077] In the present invention, graphite is recovered from the floating material. Since graphite has hydrophobic properties, it rises to the upper foam layer along with bubbles. When the foam layer is collected and washed, graphite, which is the cathode material, is recovered with high purity (S3-1).

[0078] The process solution and precipitate remaining after the graphite is recovered can be separated by methods such as filtration. In the process solution from which the precipitate has been filtered, lithium is leached and dissolved in the form of carbonate (Li2CO3). When this is heated and concentrated or precipitated with a sparingly soluble lithium salt and filtered, powdered lithium carbonate is recovered (S3-2).

[0079] The process solution can be filtered and the remaining precipitate washed to recover solid cathode materials, such as nickel, chromium, manganese, etc. (S3-3).

[0081] In a preferred embodiment of the present invention, a process of adding process water again to the suspended solids and precipitates remaining after filtering the process solution to leach lithium carbonate and then filtering may be added one or more times. Specifically, the recovery rate of lithium salt can be increased by repeating the process of adding process water again to the suspended solids and precipitates remaining after filtering the process solution to leach lithium salt and then filtering.

[0082] Since the solubility of lithium carbonate (Li2CO3), the form in which lithium is recovered, in water is not high (1.29 g / 100 mL at 25°C), some Li2CO3 may be included in addition to graphite anode material or cathode material such as nickel, cobalt, and manganese in the suspended solids and precipitates, and if a process to recover lithium salt from the precipitates is added, the recovery rate of Li2CO3 can be increased.

[0084] According to the present invention, graphite anode material used in spent lithium-ion batteries, cathode materials such as nickel, cobalt, and manganese, and lithium metal used as a charge carrier can all be recovered with high yield in a single process.

[0086] The present invention will be explained in more detail below through examples. The following examples are presented to aid understanding and are merely illustrative of the invention; the scope of the invention is not limited to these examples.

[0088] Examples

[0089] (1) Preparation of Black Mass

[0090] The spent lithium-ion battery (graphite anode, Co-Ni-Mn cathode, lithium salt charge carrier) was dried under conditions of 10 Torr and 160°C to remove the electrolyte.

[0091] Waste lithium-ion batteries from which the electrolyte had been removed were crushed to obtain a black mass mixed with cathode material powder (NCM, LCO, etc.), graphite, and current collector metals (Al, Cu).

[0092] The mixture was classified through a 100-mesh sieve (opening size 149 μm) to remove metal foil, etc., and a black mass with a residual impurity content of 5 wt% or less was prepared (the molar ratio of Li, Ni, Mo, and Co was 1:0.6:0.2:0.2).

[0093] Figure 2 shows the results of thermogravimetric analysis of the black mass prepared in the example under a nitrogen atmosphere. In Figure 2, the red line represents the TG measurement results of the prepared black mass, and the black lines represent the DTA measurement results. From Figure 2, it can be confirmed that the PVDF binder polymer present in the black mass undergoes thermal decomposition at temperatures ranging from 250°C to 400°C or lower, and that graphite does not decompose in nitrogen. The PVDF (C2H2F2) binder separates into carbon (C) and fluorine (HF). The carbon reacts with lithium to form lithium carbonate, and the fluorine reacts with added calcium to form fluorite (CaF2).

[0095] (2) Heat treatment

[0096] FIG. 3 is the result of X-ray diffraction analysis of a black mass obtained by heat-treating the black mass (A) prepared in the example at temperatures of 400°C (B), 500°C (C), and 600°C (D) for 1 hour in a nitrogen atmosphere. From FIG. 3, it can be seen that lithium carbonate is generated in the black mass under the above conditions.

[0098] Figure 4 shows the free energy (Gibb's free energy, ΔG) of lithium carbonation reactions occurring during the heat treatment process as a function of temperature. o These are graphs showing the changes. Figure 4 explains that the reaction (Equation 2-3) in which lithium metal oxide reacts with organic carbon to produce lithium carbonate among the carbonation reaction equations of lithium metal oxides occurs spontaneously under the above temperature conditions.

[0100] (3) Magnetic separation

[0101] Process water was added to the heat-treated material to create a slurry, and the grade and recovery rate of the cathode material recovered through magnetic separation were measured. The solid content of the slurry was 5, 10, and 20 wt%, respectively, and the magnetic force was 1,000 G, 2,000 G, and 5,000 G. The results of the magnetic separation are shown in Figure 5. The grade was over 90%, and as the magnetic force increased, the recovery rate of the cathode material increased and the grade decreased.

[0103] (3) Flotation and recovery of cathode material, lithium, and anode material

[0104] Process water was added to the heat-treated material, and methyl isobutylcarbinol and kerosene were added at concentrations of 60 ppm and 0.3 parts by weight, respectively, and then thoroughly mixed to obtain a slurry with a black mass content of 20% by weight.

[0106] The slurry obtained above was stirred in a specific flotation separator, and after 30 minutes of mixing, air was introduced to float the graphite. The foam of the floating material at the top was separated with a scraper, washed with water, and then dehydrated to recover the graphite (recovery rate 96%).

[0108] After recovering the graphite, the remaining process solution and precipitate were filtered to separate them, and then the process solution was evaporated and concentrated to recover lithium in the form of lithium carbonate (Li2CO3).

[0110] Figure 6 shows the results of electron microscope observations of the black mass (A) after heat treatment, the floating material (B) and the precipitate (C) after flotation in the example. Referring to Figure 6, it can be seen that graphite and cathode material are separated from the black mass after the flotation process.

[0112] Figure 7 shows the results of X-ray diffraction analysis of the black mass after heat treatment (A) and the precipitate after flotation (B) of the example. From Figure 7, it can be confirmed that the diffraction peaks caused by lithium carbonate salts have disappeared from the cathode material, which is the precipitate after flotation of the black mass after heat treatment. From this, it can be seen that lithium carbonate salts have been eluted into the flotation process solution.

[0114] Figure 8 is a graph showing the molar ratio of lithium and nickel in the precipitate collected according to the time of flotation of the black mass before heat treatment, the black mass after heat treatment, and the black mass after heat treatment. The graph shows the molar ratio of lithium and nickel in the black mass before heat treatment, the heat-treated black mass, and the flotation precipitate after heat treatment. From this, it can be confirmed that the molar ratio of lithium and nickel in the cathode material in the black mass before and after heat treatment was maintained at 1 to 0.6, while the molar ratio of lithium and nickel in the cathode material in the flotation precipitate was 0.1 to 0.6, indicating that more than 90% of the lithium dissolved in the flotation process water.

[0116] Figure 9 is an electron microscope image showing cathode material particles in heat-treated black mass and cathode material particles in flotation precipitate. As can be seen in Figure 9, many pores are observed on the surface of the cathode material particles in the flotation precipitate. These are believed to be pores created as lithium carbonate dissolves out.

[0118] Figure 10 shows the results of X-ray diffraction analysis of a solid material obtained by evaporating and concentrating the flotation process solution. From Figure 10, it can be confirmed that the recovered lithium is mainly composed of lithium carbonate (Li2CO3) and that some lithium hydroxide (LiOH) is present.

[0120] Finally, the precipitate was washed with water to recover the cathode material (Ni, Mo, Co). Through the above process, the recovery rate of the cathode material and graphite was over 96%, and the lithium recovery rate was 90%.

Claims

Claim 1 A method for recovering a positive electrode metal, a negative electrode material, and lithium from a spent lithium-ion battery, comprising the steps of: mixing the black mass of the spent lithium-ion battery with calcium carbonate and then heat-treating it to obtain a heat-treated product containing lithium carbonate; separating a process solution from a mixed solution obtained by diluting the heat-treated product with process water, excluding suspended solids and precipitates; and recovering lithium carbonate from the process solution. Claim 2 A recovery method according to claim 1, wherein the positive electrode material of the spent lithium-ion battery comprises a lithium metal oxide or a lithium iron phosphate-based compound; the charge carrier is an aqueous solution containing lithium ions; and the negative electrode material comprises graphite. Claim 3 A recovery method according to paragraph 2, characterized in that the residual impurity content of the black mass is 7% by weight or less. Claim 4 A recovery method according to claim 3, characterized in that the number of moles of calcium carbonate (CaCO3) mixed with the black mass is 0.6 to 1 times the number of moles of lithium present in the black mass. Claim 5 A recovery method according to any one of claims 2 to 4, characterized in that the heat treatment is performed at a temperature of 400 to 600℃. Claim 6 delete Claim 7 A recovery method according to claim 5, characterized in that the concentration of the black mass in the mixed solution is 10 to 20 weight%. Claim 8 A recovery method according to claim 7, characterized in that the concentration of lithium ions in the process solution is 2,000 to 3,000 ppm. Claim 9 A recovery method according to claim 7, characterized by adding a collector and a foaming agent to the above-mentioned mixed solution. Claim 10 A recovery method according to claim 9, characterized in that the collector is a non-polar oil. Claim 11 A recovery method according to claim 9, characterized in that the additional amount of the collector is 0.1 to 1 part by weight based on 100 parts by weight of graphite content in the mixed solution. Claim 12 A recovery method according to claim 9, characterized in that the foaming agent is methylisobutylcarbinol. Claim 13 A recovery method according to claim 9, characterized in that the additional amount of the foaming agent is 0.1 to 1 part by weight based on 100 parts by weight of graphite content in the mixed solution. Claim 14 A recovery method according to claim 9, characterized in that the pH of the mixed solution is 10 or less. Claim 15 A recovery method according to claim 1, characterized by adding process water to the precipitate remaining after filtering the process solution to leach the lithium salt and then filtering it one or more times. Claim 16 A method for separating and recovering a positive electrode metal, a negative electrode material, and lithium from a spent lithium-ion battery, comprising: a step of mixing the black mass of the spent lithium-ion battery with calcium carbonate and then heat-treating it to obtain a heat-treated product containing lithium carbonate; a step of separating a mixed solution obtained by diluting the heat-treated product with process water into a floating material, a precipitate, and a process solution; and a step of recovering graphite from the floating material, a positive electrode material from the precipitate, and lithium carbonate from the process solution. Claim 17 A separation and recovery method according to claim 16, characterized in that the amount of calcium carbonate mixed with the black mass is 0.6 to 1 times the number of moles of lithium present in the black mass. Claim 18 A separation and recovery method according to claim 17, characterized in that the heat treatment is performed at a temperature of 400 to 600°C. Claim 19 A separation and recovery method characterized in that, in any one of claims 16 to 18, the concentration of lithium ions in the process solution is 2,000 to 3,000 ppm. Claim 20 A separation and recovery method according to claim 19, characterized in that the pH of the above-mentioned mixed solution is 10 or less. Claim 21 A separation and recovery method according to claim 20, characterized in that a process of adding process water to the precipitate remaining after filtering the above process solution to leach out the lithium salt and then filtering is added one or more times. Claim 22 A method for recovering lithium from a spent lithium-ion battery, comprising the steps of: mixing the black mass of the spent lithium-ion battery with calcium carbonate and then heat-treating to obtain a heat-treated product containing lithium carbonate; separating a process solution excluding suspended matter and precipitate from a mixed solution obtained by diluting the heat-treated product with process water; and recovering lithium carbonate from the process solution; wherein the heat treatment is performed under temperature conditions of 400 to 600°C.

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