Method for recovering lithium from black mass obtained from waste batteries

Abstract

The present invention relates to a method for recovering lithium from black mass obtained from waste batteries, wherein the black mass contains aluminum and lithium, the method comprising the steps of: roasting, at 300-1,000°C, the black mass together with a volatile agent containing chlorine, so as to separate out volatile substances and obtain a residue, the roasting being used to selectively separate out, preferentially to lithium, aluminum as a volatile substance; water-leaching the residue so as to obtain an aqueous solution containing lithium; and recovering lithium from the aqueous solution.

Description

Method for recovering lithium from black mass obtained from waste batteries

[0001] The present invention relates to a method for recovering lithium from black mass obtained from waste batteries.

[0002] The demand for and prices of key minerals are rising due to the expansion of the lithium-ion battery market and the energy transition. Furthermore, the demand for key minerals is projected to increase more than fourfold by 2040 due to the transition to clean energy, with lithium predicted to see the largest increase in demand among key minerals at 42-fold.

[0003] As such, while the demand for essential raw materials for eco-friendly technologies, such as lithium, cobalt, and nickel, continues to increase, their production and smelting processes face significant constraints due to high carbon emissions and environmental burdens. Among these, lithium presents the most vulnerable issues, leading to an increasing need for the development of production technologies that meet ESG requirements.

[0004] Following a recent proposal by the European Chemicals Agency, the EU Committee on the Classification of Hazardous Substances is reviewing the inclusion of lithium in the hazardous substance classification system; if the classification is finalized, it is expected that additional costs will be incurred to comply with stricter processing and storage standards than before.

[0005] In the process of manufacturing lithium compounds from lithium raw materials, the key step determining profitability is the lithium concentrate production step. Concentration technologies such as acid leaching of solid raw materials, heating / concentration of lithium solutions, membrane separation, electrodialysis, and solvent extraction have been proposed. However, these technologies involve the use of excessive amounts of acid / alkali solvents, high process costs, and, in particular, significant problems regarding environmental pollution. Consequently, there is a growing demand for eco-friendly technologies that can replace them.

[0006] Among these, circular resource recycling technology is attracting attention, and active technological development is underway for the recycling of waste lithium-ion batteries, the volume of which is expected to surge in the future. Generally, waste lithium-ion battery recycling technology selectively recovers valuable metals such as Ni and Co by applying solvent extraction methods following acid leaching of the black mass discharged after discharge and crushing, and finally recovers them from the discharged lithium waste liquid by applying solvent extraction or precipitation methods.

[0007] However, these conventional methods are constrained by the high burden of treating discharged waste liquid (NaOH / Na2SO4 sol.) during the lithium recovery process, leading to an increasing demand for alternative technologies.

[0008] The object of the present invention is to provide a method for recovering lithium from black mass obtained from waste batteries.

[0009] The objective of the present invention is achieved by a method for recovering lithium from black mass obtained from waste batteries, wherein the black mass comprises aluminum and lithium, and the black mass and a volatile agent comprising chlorine are roasted together at 300°C to 1000°C to separate volatile substances and obtain a residue, wherein aluminum is selectively separated as a volatile substance relative to lithium by roasting; the residue is leached with water to obtain an aqueous solution containing lithium; and the lithium is recovered from the aqueous solution.

[0010] In the above roasting process, at least a portion of the aluminum can be converted into aluminum chloride and volatilized.

[0011] The above volatile agent may include an aqueous hydrochloric acid solution.

[0012] The above black mass may contain 1 to 10 weight percent of aluminum and 0.5 to 8 weight percent of lithium.

[0013] In the above roasting, the molar ratio of hydrochloric acid to aluminum may be 1.5 to 2.2.

[0014] In the above roasting, the molar concentration of the aqueous hydrochloric acid solution is 2 to 6, and the solid-to-liquid ratio (g / L) of the black mass and the aqueous hydrochloric acid solution may be 800 to 1200.

[0015] The above roasting is performed at 600°C to 800°C for 30 minutes to 2 hours, and the volatilization rate of aluminum defined by the following formula 1 may be 70% or more.

[0016] Aluminum Volatility Rate = 100 - (Aluminum content of residue / Aluminum content of black mass) * 100 - Equation 1

[0017] The separation factor of aluminum to lithium defined by the following Equation 2 can be 8 or greater.

[0018] Separation factor = (Aluminum content of black mass / Aluminum content of residue) / (Lithium content of black mass / Lithium content of residue) - Equation 2.

[0019] The solid-to-liquid ratio (g / L) of the above water leaching may be 500 to 1000.

[0020] The above roasting is performed at 650°C to 750°C, the molar ratio of hydrochloric acid to aluminum is 1.7 to 1.9, the molar concentration of the aqueous hydrochloric acid solution is 2 to 4, the volatility of aluminum is 85% or more, and the separation factor of aluminum to lithium may be 10 or more.

[0021] According to the present invention, a method for recovering lithium from black mass obtained from waste batteries is provided.

[0022] FIG. 1 is a flowchart of a lithium recovery method according to one embodiment of the present invention, and

[0023] Figures 2a and 2b are thermodynamic data on the formation of aluminum chloride according to aluminum and chloride components, and

[0024] Figure 3 shows the content of each component of the water washing solution of the residue according to the roasting temperature in an experimental example according to the present invention, and

[0025] Figure 4 shows the content of each component according to the solid-liquid ratio during water washing of the residue in an experimental example according to the present invention, and

[0026] Figure 5 is an XRD analysis graph of lithium carbonate obtained in an experimental example according to the present invention.

[0027] Unlike black mass leaching and solvent extraction methods, processes are being considered to separate lithium components by converting them into lithium carbonate, lithium oxide, or lithium chloride through carbonation, reduction, or chlorination reactions of the black mass, followed by water leaching.

[0028] However, the lithium recovery rate is subject to varying limitations depending on the content of aluminum components (aluminum, alumina, aluminum hydroxide, etc.) contained in the black mass. This is because the reaction between the lithium and aluminum components during the dry conversion reaction of the lithium components in the black mass forms Li-Al-O, an insoluble lithium compound, which reduces the lithium recovery rate during the water leaching process.

[0029] To improve this, aluminum components contained in black mass are separated through pretreatment processes such as flotation; however, water-soluble lithium components contained in black mass also dissolve in the flotation solution, which presents a limitation in that the recovery rate of lithium components from black mass is reduced.

[0030] The present invention provides a method capable of improving the recovery rate of lithium components in a process in which aluminum components from black mass are converted into aluminum chloride through a dry reaction (chlorination reaction) and removed by volatilization / separation or water leaching, and lithium components contained in black mass are converted into lithium chloride or lithium carbonate / hydroxide.

[0031] The present invention will be described in more detail below with reference to the drawings.

[0032] The attached drawings are merely examples illustrated to further explain the technical concept of the present invention, and therefore the concept of the present invention is not limited to the attached drawings.

[0033] A method for recovering lithium according to an embodiment of the present invention will be described with reference to FIG. 1.

[0034] First, the black mass is roasted (S10).

[0035] In the following description, % represents weight % unless otherwise noted.

[0036] Black mass can be obtained from various types of waste batteries, such as NCM-based waste batteries.

[0037] Black mass contains aluminum and lithium. Specifically, it may contain 1 to 10 weight%, 2 to 8 weight%, or 3 to 6 weight% of aluminum and 0.5 to 8 weight%, 1 to 6 weight%, or 2 to 4 weight% of lithium. Alternatively, the aluminum content may be 1 to 3 times, 1 to 2 times, or 1.3 to 1.8 times the lithium content.

[0038] In addition, the black mass may further contain nickel, cobalt, manganese, iron, etc. Nickel may be 10 to 20 weight%, cobalt 2 to 8 weight%, manganese 2 to 8 weight%, and iron 0.1 to 2 weight%.

[0039] In the roasting process, black mass and a volatile agent containing chlorine are heated together. The roasting temperature is 300°C to 1000°C, 600°C to 800°C, or 650°C to 750°C, and the roasting time may be 10 minutes to 10 hours, 20 minutes to 6 hours, or 30 minutes to 2 hours.

[0040] Volatile agents containing chlorine include ammonium chloride and hydrochloric acid, and in particular, hydrochloric acid can be used.

[0041] The molar ratio of hydrochloric acid (chlorine) / aluminum may be 1.5 to 2.2 or 1.7 to 1.9.

[0042] The solid-to-liquid ratio (g / L) of black mass and hydrochloric acid aqueous solution can be 800 to 1200 or 900 to 1100.

[0043] By roasting, aluminum is converted into aluminum chloride, volatilizes, and a residue is obtained.

[0044] The aluminum volatility (%) defined by the following Equation 1 may be 70% or more, 75% or more, 80% or more, or 85% or more. The upper limit of the aluminum volatility (%) may be 90%, 95%, or 99%.

[0045] Aluminum Volatility Rate = 100 - (Aluminum content of residue / Aluminum content of black mass) * 100 - Equation 1

[0046] In the roasting according to the present invention, aluminum is selectively volatilized in greater quantities than lithium.

[0047] The separation factor of aluminum to lithium defined by the following Equation 2 may be 5 or more, 8 or more, 10 or more, 12 or more, or 15 or more. The upper limit of the separation factor may be 20, 30, or 50.

[0048] Separation factor = (Aluminum content of black mass / Aluminum content of residue) / (Lithium content of black mass / Lithium content of residue) - Equation 2.

[0049] As such, in the roasting step of the present invention, most of the aluminum volatilizes, and the volatilization of lithium is suppressed. In the roasting step, at least a portion of the lithium contained in the black mass can be converted into lithium chloride.

[0050] Afterwards, the residue is rinsed with water (S20).

[0051] An aqueous solution containing lithium, specifically lithium chloride, is obtained through water leaching.

[0052] The solid-to-liquid ratio (g / L) of the water leaching can be 400 to 1200 or 500 to 1000.

[0053] Finally, lithium is recovered from the aqueous solution (S30).

[0054] Lithium can be recovered in the form of lithium carbonate, but is not limited thereto. In this case, based on the Li content contained in the lithium solution recovered after water leaching, Na2CO3 can be used as the carbonate and mixed under conditions of a Li / CO3 molar ratio of 1 to 3, and a carbonation reaction can be carried out at 40 to 80°C for 4 to 15 hours and at 100 to 500 RPM.

[0055] The present invention will be explained in detail below through experimental examples.

[0056] <Preparation Example 1>

[0057] The aluminum chloride formation temperature varies slightly depending on the aluminum components (aluminum metal and alumina, etc.) contained in the black mass. As shown in Figures 2a and 2b, it was confirmed that aluminum chloride is easily formed when aluminum metal reacts with hydrochloric acid or ammonium chloride, while it is determined that a reaction temperature of 700°C or higher is required for alumina.

[0058] <Preparation Example 2>

[0059] The black mass used in the experiment was powder recovered after discharging, crushing / grinding, and classification of NCM-based waste batteries. As shown in Table 1, the lithium and aluminum component contents were approximately 4.2% and 3.1%, respectively.

[0060]

[0061]

[0062] <Example 1>

[0063] Ammonium chloride was used as a reactant to remove aluminum components contained in black mass, and a salt roasting reaction was performed at 800°C for 4 hours with mixing according to Cl / Al molar ratios. Ar gas was supplied at a flow rate of 100 mL / min to maintain an inert atmosphere inside the reactor, and after the reaction was completed, the content values ​​of the product before and after washing were confirmed through ICP analysis.

[0064] As a result of conducting the experiment at 800℃, it was confirmed that the Al content decreased rapidly when the molar ratio of Cl / Al was 24 or higher, as shown in Table 2.

[0065] From this, it can be seen that a relatively large amount of NH4Cl is required during the mixing process to improve the contact rate of Al / Cl due to the low apparent density of BM.

[0066] As a result of analyzing the content of samples washed with DI water, it was confirmed that the lithium component was also converted into lithium chloride and mixed in during the washing process, and it is determined that a separation / purification step from the aluminum component is required during the subsequent lithium component separation process.

[0067] Table 2

[0068]

[0069] <Example 2>

[0070] When chlorination was performed using a mixture of black mass and ammonium chloride (Cl / Al molar ratio: 24), an inert atmosphere was maintained by supplying Ar gas at a flow rate of 200 mL / min, and the reaction was carried out at a reaction temperature of 900℃ and 1000℃ for 4 hours.

[0071] As shown in Table 3, as the reaction temperature increased, the residual lithium content decreased, while the aluminum content was observed to increase slightly. This suggests that as the reaction temperature increases, Li and Al components are converted into chlorides and vaporized, making separation possible; however, it is believed that the separation efficiency decreases because Li and Al components react at high temperatures to form high-temperature stable Li-Al-O.

[0072] Although chlorides such as Me-Cl (Me: Ca, Mg, Al, Fe, etc.) and PVC can also be used during the chlorination roasting reaction, it is judged that the subsequent leaching and purification processes will be somewhat burdensome due to residual components after the reaction.

[0073] Table 3

[0074]

[0075] <Example 3>

[0076] We intended to volatilize and separate the aluminum components contained in the black mass by mixing and roasting it with hydrochloric acid using black mass containing approximately 4.4% and 3.0% lithium and aluminum. The black mass and hydrochloric acid were mixed using a 3M hydrochloric acid solution such that the solid (g) / liquid (L) ratio was 1000, and the roasting reaction was carried out under an inert atmosphere for 4 hours at a roasting temperature in the range of 300 to 900℃.

[0077] The composition of the black mass used in the following experiments is as shown in Table 4.

[0078] Table 4

[0079]

[0080] From the analysis of the residue content after the roasting reaction shown in Table 5, it was confirmed that as the reaction temperature increased, the residual aluminum content decreased, while the lithium content remained similar. However, when the reaction temperature reached 900℃, the lithium content decreased, which is considered to be the result of the volatilization of lithium chloride formed in the chlorination reaction.

[0081] Table 5

[0082]

[0083] <Example 4>

[0084] The roasting reaction residue was mixed with distilled water to achieve a solid (g) / liquid (L) ratio of 100, and after washing and drying, the residue content was analyzed. From the analysis results shown in Table 6, the residual lithium content decreased as the reaction temperature increased above 300℃; this suggests that the lithium chloride conversion rate is higher as the reaction temperature increases. In the case of aluminum content, a small range of change was observed before and after washing, which is considered to be the aluminum component remaining after conversion to aluminum chloride and volatilization separation.

[0085] Table 6

[0086]

[0087] <Example 5>

[0088] Black mass and hydrochloric acid were mixed using a 3M hydrochloric acid solution to achieve a solid (g) / liquid (L) ratio of 1000, and after roasting in an inert atmosphere at a temperature range of 300 to 900°C for 4 hours, the residue was mixed with distilled water and stirred to achieve a solid (g) / liquid (L) ratio of 100 to proceed with water leaching and recover the solution.

[0089] From the experimental results shown in Table 7 and Figure 3, the lithium content in the rinse solution of the residue after the reaction increased as the chlorination reaction temperature increased, and the highest lithium content was observed at 700°C. Figure 3 shows the case where the black mass (g) / 3M HCl (L) ratio is 1000 and the resultant (g) / H2O (L) ratio is 100. However, when the reaction temperature increased above 700°C, the lithium content recovered from the residue after water leaching decreased, which is attributed to the partial volatilization of the lithium chloride component formed by the chlorination reaction or a decrease in recovery rate due to the formation of the insoluble lithium component, Li-Al-O.

[0090] Table 7

[0091]

[0092] Considering the residue content after the chlorination reaction of the black mass / hydrochloric acid mixture, the residue content after washing, and the lithium content, aluminum content, and cathode material component (Ni, Co, Mn) content in the washing solution, it is determined that a reaction temperature of 700°C is appropriate.

[0093] <Example 6>

[0094] Black mass and hydrochloric acid were mixed using a 3M hydrochloric acid solution such that the solid (g) / liquid (L) ratio was 1000, and a roasting reaction was carried out under an inert atmosphere at 700°C for 1 to 4 hours.

[0095] <Example 7>

[0096] After the roasting reaction, distilled water was mixed and stirred with the residue to achieve a solid (g) / liquid (L) ratio of 100 to proceed with water leaching.

[0097] <Example 8>

[0098] The roasting reaction residue was leached with water, the solution was recovered, and the content of each component was analyzed.

[0099] Table 8 shows the content of residue components by time of chlorination reaction, Table 9 shows the content of residue components after rinsing by time of chlorination reaction, and Table 10 shows the content of components contained in the solution of the chlorination reaction and residue rinsing.

[0100] From the experimental results, it was confirmed that the residual lithium and aluminum components were similar in the chlorination reaction time range of 1 to 4 hours, and it was observed that the lithium and aluminum components contained in the residual samples after the chlorination reaction and washing also remained at similar values. As a result of analyzing the components contained in the solution recovered after the chlorination reaction and washing, aluminum was not detected, and from the analysis of the lithium content, the highest lithium content was observed under conditions of 700°C for 1 hour.

[0101] Table 8

[0102]

[0103] Table 9

[0104]

[0105]

[0106]

[0107] <Example 9>

[0108] Black mass and hydrochloric acid were mixed using a 1 to 5 M hydrochloric acid solution such that the solid (g) / liquid (L) ratio was 1000, and a roasting reaction was carried out under an inert atmosphere at 700°C for 4 hours.

[0109] <Example 10>

[0110] After the roasting reaction according to hydrochloric acid concentration, distilled water was mixed and stirred to make the solid (g) / liquid (L) ratio 100, and water leaching was carried out.

[0111] <Example 11>

[0112] The roasting reaction residue was leached with water, the solution was recovered, and the content of each component was analyzed.

[0113] Table 11 shows the content of residue components according to the concentration of hydrochloric acid in the chlorination reaction, Table 12 shows the content of residue components after rinsing according to the concentration of hydrochloric acid in the chlorination reaction, and Table 13 shows the content of components contained in the solution of the chlorination reaction and residue rinse.

[0114] From the experimental results, it was observed that under the same mixing conditions, the residual aluminum content decreased as the hydrochloric acid concentration increased up to 3M, but increased at 4M or higher. In the case of lithium and aluminum content after washing the roasting reaction residue, it was confirmed that they were somewhat similar; however, regarding the lithium content in the washing solution, the highest value was observed when a 3M hydrochloric acid solution was mixed, and it was confirmed that no aluminum component was detected.

[0115] It is determined that when black mass and hydrochloric acid are mixed under conditions where the solid (g) / liquid (L) ratio is 1000, using 3M hydrochloric acid results in the highest lithium recovery rate during the lithium component separation process.

[0116]

[0117]

[0118] Table 12

[0119]

[0120]

[0121]

[0122] <Example 12>

[0123] Black mass and hydrochloric acid were mixed using a 3M hydrochloric acid solution to achieve a solid (g) / liquid (L) ratio of 1000, and a roasting reaction was carried out under an inert atmosphere at 700°C for 4 hours.

[0124] <Example 13>

[0125] After the roasting reaction, distilled water was mixed and stirred to extract the residue so that the solid (g) / liquid (L) ratio was 5 to 1000.

[0126] <Example 14>

[0127] The solution was recovered after water leaching of the roasting reaction residue according to solid / liquid ratios, and the content of each component was analyzed.

[0128] From the experimental results shown in Figure 4, it was observed that as the solid / liquid ratio of water leaching increased, the lithium ion concentration contained in the recovered solution also increased linearly, and it was determined that it is possible to produce a high-concentration lithium chloride solution. Na, K, Si, etc. were detected as impurity components contained in the solution, but it was confirmed that the amount of contamination was negligible.

[0129] <Example 15>

[0130] Black mass was mixed with a 3M hydrochloric acid solution to achieve a solid (g) / liquid (L) ratio of 1000, and a roasting reaction was carried out under an inert atmosphere at 700°C for 4 hours. After the roasting reaction, the residue was mixed and stirred with distilled water to achieve a solid (g) / liquid (L) ratio of 1000, and the solution was recovered after water leaching.

[0131] The reaction conditions and analysis results are as shown in Table 14.

[0132]

[0133]

[0134] <Example 16>

[0135] To produce lithium carbonate, the black mass roasting product (solid / liquid ratio 1000, 3M HCl, 700°C for 4 hours) was leached with water under conditions of a solid / liquid ratio of 1000. Based on the Li content contained in the recovered lithium solution, Na2CO3 was used as the carbonate, and the mixture was mixed under conditions of a Li / CO3 molar ratio of 2. A carbonation reaction was then carried out at 60°C for 8 hours at 300 RPM. After separating the precipitate and washing with hot water, purified lithium carbonate powder was prepared, and the structure of the lithium carbonate was confirmed through XRD analysis as shown in Figure 5. Through ICP analysis of the reaction filtrate, the residual lithium ion concentration was observed to be approximately 1981 ppm, and a lithium recovery rate of approximately 90.7% was confirmed by calculating the change in concentration values ​​before and after the carbonation reaction.

Claims

1. A method for recovering lithium from black mass obtained from waste batteries, The above black mass contains aluminum and lithium, and A step of obtaining a residue by roasting the above black mass and a volatile agent containing chlorine together at 300°C to 1000°C to separate volatile substances, wherein aluminum is selectively separated as a volatile substance compared to lithium by roasting; The step of leaching the above residue with water to obtain an aqueous solution containing lithium; and A method comprising the step of recovering lithium from the above aqueous solution.

2. In Paragraph 1, In the above roasting facility, A method in which at least a portion of aluminum is converted into aluminum chloride and volatilized.

3. In Paragraph 2, The above volatile agent is a method comprising an aqueous hydrochloric acid solution.

4. In Paragraph 3, A method in which the above black mass contains 1 to 10 weight percent of aluminum and 0.5 to 8 weight percent of lithium.

5. In Paragraph 4, In the above roasting facility, A method in which the molar ratio of hydrochloric acid to aluminum is 1.5 to 2.

2.

6. In Paragraph 5, In the above roasting facility, The molar concentration of the above aqueous hydrochloric acid solution is 2 to 6, and A method in which the solid-to-liquid ratio (g / L) of black mass and aqueous hydrochloric acid solution is 800 to 1200.

7. In Paragraph 6, The above roasting is performed at 600℃ to 800℃ for 30 minutes to 2 hours, and The volatility of aluminum defined by the following Equation 1 is 70% or more, and Aluminum Volatility Rate = 100 - (Aluminum content of residue / Aluminum content of black mass) * 100 - Equation 1 A method in which the separation factor of aluminum to lithium defined by the following Equation 2 is 8 or greater: Separation factor = (Aluminum content of black mass / Aluminum content of residue) / (Lithium content of black mass / Lithium content of residue) - Equation 2.

8. In Paragraph 6, A method in which the solid-liquid ratio (g / L) of the above-mentioned water leaching is 500 to 1000.

9. In Paragraph 7, The above roasting is performed at 650°C to 750°C, and The molar ratio of hydrochloric acid to aluminum is 1.7 to 1.9, and The molar concentration of the above aqueous hydrochloric acid solution is 2 to 4, and The volatility of aluminum is over 85%, and A method in which the separation factor of aluminum to lithium is 10 or higher.

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