Process for the recovery and purification of lithium

Abstract

The present invention relates to the recovery and purification of lithium from lithium-containing sources, such as lithium-ion battery materials, using ion exchange. A solution of lithium-containing salts is passed through an acidic cation exchange resin, and a lithium raffinate and a mixture of other elements, such as metals like nickel, cobalt, and manganese, are recovered as a product. The lithium raffinate can then be processed into other lithium products, such as lithium carbonate and lithium hydroxide.

Description

Technical Field

[0001] This invention relates to the recovery and purification of lithium from lithium-containing sources (such as lithium-ion battery materials). Background Technology

[0002] With increasing consumer demand for appliances and automobiles and growing technological sophistication, lithium-ion batteries (LIBs) are playing an increasingly important role in mobile energy storage. Although LIBs were invented in 1985, recent trends in energy density and production costs indicate a significant increase in demand. Currently, the most common type of LIB used in electric vehicles is based on NCM (nickel, cobalt, and manganese) or NCA (nickel, cobalt, and aluminum) as the positive electrode material and graphite as the negative electrode material. Despite their effectiveness, the current price of raw materials makes the deployment of these technologies quite expensive, and the mining and processing of battery-grade chemicals also generates significant GHG emissions.

[0003] In recent years, efforts to reduce the production cost of lithium batteries (LIBs) and emissions from LIB production through recycling have increased significantly. Several recycling pathways exist, including pyrometallurgical and hydrometallurgical pathways for metal recovery and separation. Currently, most recycled batteries are fed into existing pyrometallurgical facilities, such as furnaces. Hydrometallurgical pathways or combinations thereof are currently being established and tested worldwide, and lithium leaching after reduction roasting is an emerging lithium recovery technology. This technology is a first-step lithium recovery method that requires high temperatures (>500°C) and expensive reducing agents (such as hydrogen or coal), which significantly increases the process's CO2 footprint.

[0004] Primary lithium production is concentrated in South America, where lithium-rich brine is pumped into large-scale evaporation ponds, where it is concentrated by solar evaporation. This process takes up to two years. The lithium concentrate is then processed into lithium carbonate, and finally converted into lithium hydroxide through a conversion reaction with lime and evaporative crystallization. The emergence of low-cobalt cathode materials has facilitated the use of hydroxides as a lithium source, as they are more easily processed from solid ores.

[0005] JP2019125464A discloses a lithium recovery method in which lithium is recovered from wastewater during the manufacturing process of a lithium-containing and calcium-based lithium secondary battery cathode material. The method includes: an aspiration step in which the wastewater from the manufacturing process is contacted with a plurality of ion exchange resins connected in series; and an elution step after the aspiration step in which the plurality of ion exchange resins are separated and an eluent is contacted with each ion exchange resin.

[0006] WO2019 / 160982 discloses a method for extracting lithium from liquid sources such as natural and synthetic brine, leachates of clay and minerals, and recovered products.

[0007] A novel method for recovering and purifying lithium from lithium-containing sources has been invented. The method according to the invention is a one-step purification and separation pathway, wherein the lithium-containing solution is purified using chromatographic separation. This method can be used to recover and purify any lithium-containing solution, such as LIB recovery or processing fluids from primary lithium production. Compared to currently known processes, the method according to the invention is low-emission, simple, and produces high-purity lithium intermediates suitable for battery-grade lithium production. Summary of the Invention

[0008] This invention relates to the recovery and purification of lithium from lithium-containing sources (such as lithium-ion battery materials) using ion exchange. A lithium-containing salt solution is passed through an acidic cation exchange resin, and a mixture of the lithium raffinate and other elements (such as metals like nickel, cobalt, and manganese) is recovered as a product. The lithium raffinate can then be processed into other lithium products, such as lithium carbonate and lithium hydroxide.

[0009] More specifically, the present invention relates to a method for recovering and purifying lithium from lithium-containing materials, comprising the steps of: passing a process solution containing lithium salts and other elements through an acidic cation exchange resin; collecting the lithium raffinate; optionally rinsing the residual lithium with a monohydric hydroxide to obtain lithium hydroxide; eluting other elements from the acidic cation exchange resin with a strong acid solution to obtain an eluent, and regenerating the acidic cation exchange resin with a monohydric hydroxide solution.

[0010] According to one embodiment of the present invention, the lithium-containing material is a lithium-ion battery material.

[0011] According to another embodiment of the present invention, the lithium salt is lithium sulfate.

[0012] According to another embodiment of the present invention, the pH of the process solution is 3 to 5.5.

[0013] According to a further embodiment of the present invention, the monohydric hydroxide is sodium hydroxide.

[0014] According to a further embodiment of the invention, sulfuric acid is used as a strong acid in the acid solution.

[0015] According to one embodiment of the present invention, the acidic cation exchange resin is a weakly acidic cation with carboxylic acid as the functional group.

[0016] According to another embodiment of the present invention, the process solution is passed through at a rate of 0.5 to 6 BVs / h. Attached Figure Description

[0017] Figure 1 A flowchart illustrating the method according to the present invention.

[0018] Figure 2 The relative concentration curves of the elements in Example 1.

[0019] Figure 3 Penetration curves of columns 1, 2 and 3 in Example 6.

[0020] Figure 4 The penetration curves of columns 1 to 6 in Example 7. Detailed Implementation

[0021] definition

[0022] The black substance is a mixture of positive and negative electrode active materials that are separated from the battery assembly.

[0023] BV or BVs indicates bed volume; the volume of a resin bed when it is loaded into a column.

[0024] DC indicates dry content.

[0025] ICP-MS stands for Inductively Coupled Plasma Mass Spectrometry

[0026] LIB is a lithium-ion battery.

[0027] MP-AES stands for Microwave Plasma Atomic Emission Spectrometer.

[0028] NCA is a cathode material based on nickel, cobalt, and aluminum.

[0029] NCM is a cathode material based on nickel, cobalt, and manganese.

[0030] WAC is a weak acid cation.

[0031] SAC is a strong acid cation.

[0032] This invention relates to the recovery and purification of lithium from lithium-containing sources. The raw material, i.e., the lithium-containing source, can be, for example, lithium-ion battery (LIB) materials or any other lithium-containing source, such as substandard materials or byproducts of primary lithium production.

[0033] In primary lithium production from brine and ore, common impurities are calcium, magnesium, and potassium, which can be processed using various hydrometallurgical methods. Calcium hydroxide is used as a hydroxide source in the lithium carbonate conversion reaction. Because these elements are difficult to prevent co-precipitation during lithium precipitation or crystallization, a certain amount of lithium product is considered unsuitable for battery materials. The lithium content in these materials is highly variable, and for this process, according to the present invention, pretreatment with sulfuric acid, hydrochloric acid, or other suitable acids is performed to convert it into a lithium-containing salt solution. Any potentially insoluble impurities are filtered out.

[0034] Typically, the lithium content in any battery material is directly related to the amount of other cathode elements present in the material, such as nickel, cobalt, manganese (NCM-based), or aluminum (NCA-based). The black residue is expected to contain 3–4 wt% lithium. In a typical LIB hydrometallurgical recovery process, this black residue undergoes a leaching step to dissolve soluble elements, after which insoluble materials (e.g., graphite) can be separated by filtration. While the resulting filtrate is expected to contain 2.5–4.5 g / L of lithium, the lithium content may be higher, depending on the black residue or leaching step parameters.

[0035] As used in the context of this invention, the term "process solution" refers to a lithium salt solution with a pH of 3 to 5.5, preferably 4 to 4.5. If necessary, the pH of the lithium salt solution can be adjusted using a monohydric hydroxide or an acid already present in the solution.

[0036] The filtrate obtained from the filtration step of the above leaching process is a typical lithium salt solution. The metallic composition of this solution can vary depending on the raw materials, such as the presence of cathode elements or impurities, and may contain aluminum and manganese, as well as other elements such as iron, magnesium, and calcium, depending on the source materials.

[0037] Now refer to Figure 1 The flowchart illustrates the recycling and purification process according to the present invention in detail.

[0038] In the first step of the chromatographic separation of the recovery and purification process according to the invention, a process solution containing lithium salts and other elements such as nickel, cobalt, and manganese (depending on the elements present in the feed) at a pH of 3–5.5, preferably 4–4.5, is passed through an acidic cation exchange resin bed, such as a carboxylic acid or sulfonic acid resin bed. Lithium raffinate is collected starting at 0–1 BVs, preferably 0.5–1 BVs, while other elements remain in the resin until the working exchange capacity is reached. The working exchange capacity can be predetermined by calculating the resin capacity based on the element content of the initial feed. Alternatively, the working exchange capacity can be detected online by visual inspection or using spectroscopic methods, such as UV or other methods known to those skilled in the art. For a typical process solution containing 20–30 g / L of elements (i.e., the sum of lithium and other elements), lithium raffinate is collected at 0–3 BVs, preferably 0.5–2 BVs. The temperature during chromatographic separation can be 20–100°C, preferably 25–50°C, and the column pressure can be from ambient pressure to 10 bar, preferably 1–5 bar.

[0039] The lithium raffinate contains lithium salts and monobasic salts produced by chromatographic separation. As an optional step, the raffinate can be circulated several times in a resin bed to further improve the purity and concentration of lithium in the raffinate. The resulting raffinate can then be processed using known hydrometallurgical methods into other lithium products, such as lithium carbonate or lithium hydroxide.

[0040] Optionally, an aqueous monohydric hydroxide, such as sodium hydroxide, is used to flush out residual lithium from the column, i.e., from the resin loaded with other elements and residual lithium, to produce a lithium hydroxide solution. The concentration of the monohydric hydroxide used in this step is 0.25–2 wt%, preferably 0.5–1 wt%.

[0041] Another step (not in) Figure 1 (As shown in the diagram) Alternatively, a monohydric hydroxide solution can be added to the lithium raffinate, and the raffinate-hydrolysate solution can be used for rinsing to improve the purity and concentration of lithium in the raffinate. The solution leaving the column after rinsing contains lithium salt, lithium hydroxide, and the monohydric salt produced by chromatographic separation.

[0042] In the second step, other elements are eluted from the resin using a strong acid solution of 1–4 BVs, such as a 10–25 wt% sulfuric acid or hydrochloric acid solution, preferably 15–20 wt%. Other suitable strong acids with similar concentrations may also be used. The resulting eluent contains nickel, cobalt, manganese, and / or aluminum in the form of salts, such as sulfates or chlorides, depending on the strong acid used. The feed rate of the acid solution is 1–6 BVs / h, preferably 2–4 BVs / h.

[0043] The eluent can then be processed into different products using conventional hydrometallurgical methods such as solvent exchange, precipitation, and ion exchange.

[0044] The resin bed is washed with 0.5 to 2 BVs, preferably 1 to 1.5 BVs, of water to remove residual eluent.

[0045] In the final step, the resin is regenerated using a 2–25 wt%, preferably 5–20 wt%, solution of a monohydric hydroxide (such as sodium hydroxide or lithium hydroxide), which is fed through the resin bed at a rate of 1–6 BVs / h, preferably 2–4 BVs / h. After this step, the resin bed can be reused.

[0046] The number of columns connected in series can be 1 to 10, preferably 2 to 6. Other techniques, such as simulating a moving bed, can also be applied to this invention.

[0047] Example

[0048] In Examples 1-8 below, hydrogen peroxide was used as a reducing agent to dissolve the black substance containing the NCM-based cathode material in sulfuric acid to obtain a lithium salt solution. The metal composition is shown in Table 1.

[0049] Table 1. Metal composition of lithium salt solutions.

[0050] element mg / kg Co 10200 Li 2550 Mn 1480 Ni 8850

[0051] Example 1

[0052] 40 ml of Finex CA16G-Na resin with carboxylic acid function was packed into a 25 mm diameter column (YMC Eco). The bed height was measured to be 575 mm. The pH of the lithium salt solution was adjusted to 3.5 with sodium hydroxide (NaOH) to obtain the process solution. 700 ml of the process solution was pumped through the resin bed at a rate of 1 BVs / h, followed immediately by the addition of 500 ml of 20% sulfuric acid (H2SO4), and then water was added until a clear solution was collected. Samples were collected every 50 ml. The metal content of the samples was analyzed by MP-AES and expressed as a relative concentration curve (sample concentration (c) vs. original concentration in the process solution (c0)). The curve is shown below. Figure 2 As shown.

[0053] When the lithium concentration was increased to approximately 1.5 times its original value, clear chromatographic separation of lithium was observed. Within the range of 0.8 BV to 2 BVs, 80% of the lithium was separated from the other elements.

[0054] Example 2

[0055] 40 ml of Finex CA16G-Na resin with carboxylic acid function was packed into a 30 mm diameter column. The bed height was measured to be 80 mm. The pH of the lithium-containing solution (containing dissolved battery materials) was increased to pH 4 with sodium hydroxide to obtain the process solution. 38 ml of the pH-adjusted process solution was circulated through the resin bed at a rate of 3 BVs / h for 3 hours. The lithium extraction residue was collected, the resin bed was washed with 2 BVs of water, and then eluted with 1.5 BVs of 20% sulfuric acid (H2SO4). The metal content of the sample was analyzed using MP-AES (Agilent Technologies), and the yield was calculated (see Table 2).

[0056] Table 2. Metal yield of the solution in Example 2.

[0057] sample Co Li Mn Ni Lithium Extraction Residue 0％ 60％ 0％ 0％ Elution solution 100％ 40％ 99％ 100％ total 100％ 100％ 99％ 100％

[0058] The chromatographic separation of lithium was clearly demonstrated, which allowed for the recovery of at least 60% of the lithium present in the lithium-containing salt leachate.

[0059] Example 3

[0060] 40 ml of Finex CA16G-Na resin with carboxylic acid function was packed into a 30 mm diameter column. The bed height was measured to be 80 mm. The pH of the leaching solution, i.e., the lithium salt solution, was increased to 3.1 with NaOH, and 41 ml of this process solution was passed through the resin bed at a rate of 3 BVs / h. The lithium leaching residue was collected and analyzed by MP-AES.

[0061] The resin bed was washed with two bed volumes of water, followed by rinsing with 1 BV of 20% NaOH solution. The rinsing solution was collected and analyzed by MP-AES. Finally, the resin was eluted with 1.5 BV of 20 wt% H₂SO₄, and the resin was collected and analyzed by MP-AES. The metal yields for all samples were calculated and are shown in Table 3.

[0062] Table 3. Metal yield of the solution in Example 3

[0063] sample Co Li Ni Lithium Extraction Residue 0％ 16％ 0％ lithium hydroxide solution 0％ 84％ 0％ Elution solution 100％ 0％ 100％ total 100％ 100％ 100％

[0064] Example 4

[0065] 40 ml of Finex CA16G-Na resin with carboxylic acid function was packed into a 30 mm diameter column. The bed height was measured to be 80 mm. The pH of the lithium salt solution was increased to 3 with NaOH, and 50 ml of the process solution was passed through the resin bed at a rate of 3 BVs / h. The lithium raffinate was collected and analyzed by MP-AES.

[0066] The resin bed was washed with 2 bed volumes of water, followed by rinsing with 1 BV of 5% NaOH solution. The rinsing solution was collected and analyzed by MP-AES. Finally, the resin was eluted with 1.5 BV of 20 wt% H₂SO₄, and the eluent was collected and analyzed by MP-AES.

[0067] The metal yields for all samples were calculated and are shown in Table 4.

[0068] Table 4. Metal yield of the solution in Example 4.

[0069]

[0070]

[0071] Example 5

[0072] Three columns were each packed with 4300 mL of Finex CA16G-Na resin. The pH of the leachate was adjusted to 4.4 with NaOH. The process solution was pumped through the series of columns at a rate of 1.6 BV / h, with samples taken every 1 liter after each column. All samples were analyzed by MP-AES.

[0073] Dissolve 161 g NaOH in 20 L of lithium raffinate, and wash the column with this mixture at a rate of 1.6 BV / h (optional step, not included in the text). Figure 1 (As shown in the figure). Samples were taken every 1 liter and analyzed by MP-AES. In the final step, the column was eluted with 1.5 BVs of 20 wt% H2SO4 at a rate of 4 BV / h. The results are shown in Table 5.

[0074] Table 5. Metal yield of the solution in Example 5.

[0075] 1. Column Co Li Mn Ni Lithium Extraction Residue 36％ 68％ 37％ 34％ lithium hydroxide solution 2％ 19％ 2％ 1％ Elution solution 53％ 9％ 45％ 51％

[0076] 2. Column Co Li Mn Ni Lithium Extraction Residue 3％ 43％ 3％ 3％ lithium hydroxide solution 0％ 36％ 1％ 1％ Elution solution 36％ 9％ 38％ 33％

[0077] 3. Column Co Li Mn Ni Lithium Extraction Residue 0％ 16％ 0％ 0％ lithium hydroxide solution 0％ 44％ 0％ 0％ Elution solution 5％ 18％ 7％ 4％

[0078] Example 6

[0079] Three columns were packed with 4300 mL of Finex CA16G-Na resin, and the pH of the dissolved black substance was increased to 4 with NaOH. The process solution was pumped through the columns in series at a rate of 2 BV / h, with samples taken every 1 L after each column. All samples were analyzed by MP-AES. The columns were washed with 1 BV of water, and as a final step, eluted with 1.5 BV of 20 wt% H₂SO₄. Breakthrough curves are shown below. Figure 3 As shown.

[0080] The chromatographic effect becomes more pronounced as the column length increases because lithium moves through the column more rapidly and penetrates earlier than nickel, cobalt, and manganese. Therefore, it is possible to collect a lithium fraction free of other metals.

[0081] Example 7

[0082] Three columns were packed with 4300 mL of Finex CA16G-Na resin, and the pH of the lithium salt solution was increased to 4 with NaOH. The process solution was pumped through the series-connected columns at a rate of 4 BV / h, with samples taken every 1 liter after each column. All samples were analyzed by MP-AES. The columns were washed with 1 BV of water, and as a final step, eluted with 1.5 BV of 20 wt% H₂SO₄. Breakthrough curves are shown below. Figure 4 As shown.

[0083] Based on these results, it can be concluded that other elements, such as nickel, cobalt, and manganese, bind more strongly to the resin, allowing lithium to leave the column earlier, thus ensuring that the lithium fraction without other metals reaches the end of the last column.

[0084] Example 8

[0085] The black substance containing the NCM cathode material was dissolved in hydrochloric acid and filtered. The pH of the filtrate was increased to 4.2 with NaOH to form the process solution. 50 ml of the process solution was passed through 40 ml of Finex CA16G-Na resin at a rate of 2 BV / h. 50 ml of the lithium extraction residue was collected and the resin was eluted with 1 BV 10% HCl.

[0086] Table 6. Metal yield of the solution in Example 8

[0087] sample Co Li Mn Ni residual liquid 15％ 75％ 16％ 15％ Elution solution 75％ 21％ 75％ 76％ total 90％ 95％ 91％ 90％

Claims

1. A method for recovering and purifying lithium from lithium-containing materials, comprising the steps of: a) Passing a process solution containing lithium salts and other elements through an acidic cation exchange resin, wherein the pH of the process solution is 3 to 5.5 and the process solution passes through the acidic cation exchange resin at a rate of 0.5 to 6 BV / h during chromatographic separation. b) Collect the lithium extract residue at 0–1 BVs, while the other elements remain in the cation exchange resin until the working exchange capacity is reached. c) Rinse the residual lithium with a monohydric hydroxide to obtain lithium hydroxide. d) Elute the other elements from the acidic cation exchange resin with a strong acid solution of 1-4 BVs to obtain an eluent, wherein, The strong acid solution is fed at a rate of 1~6 BVs / h. e) Wash the acidic cation exchange resin with 0.5~2 BVs of water to remove residual eluent, and f) Regenerate the acidic cation exchange resin with a 2-25 wt% monohydric hydroxide solution, wherein the 2-25 wt% monohydric hydroxide solution is fed through the acidic cation exchange resin at a rate of 1-6 BVs / h.

2. The method for recovering and purifying lithium according to claim 1, wherein, The lithium-containing material is a lithium-ion battery material.

3. The method for recovering and purifying lithium according to any one of claims 1 or 2, wherein, The lithium salt is lithium sulfate.

4. The method for recovering and purifying lithium according to any one of claims 1-3, wherein, The monohydric hydroxide is sodium hydroxide.

5. The method for recovering and purifying lithium according to any one of claims 1-4, wherein, The strong acid mentioned is sulfuric acid.

6. The method for recovering and purifying lithium according to any one of claims 1-5, wherein, The acidic cation exchange resin is a weakly acidic cation with carboxylic acid as its functional group.

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