Process for extracting lithium from lithium battery scrap
By combining pyrolysis and multi-step immersion washing with phosphoric acid solution, along with purification using iron-aluminum composite metal oxide/hydroxide adsorbents, the problems of poor selectivity and high cost in traditional lithium battery waste recycling have been solved, achieving efficient and low-cost lithium recycling.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YIDING SHANGHAI INFORMATION TECH CO LTD
- Filing Date
- 2025-10-10
- Publication Date
- 2026-05-12
AI Technical Summary
In existing lithium battery waste recycling processes, the traditional inorganic strong acid leaching method has poor selectivity, resulting in high reagent consumption, high operating costs, large amounts of wastewater generation, and potential secondary pollution.
Lithium battery waste was pyrolyzed at 350-400℃ in an inert atmosphere. It was then subjected to a first immersion in a mixed solution of phosphoric acid, sodium citrate, and sodium persulfate, followed by a second immersion in a phosphoric acid solution. Subsequently, the waste was purified by adjusting the pH value and adding an adsorbent. An iron-aluminum composite metal oxide/hydroxide adsorbent was prepared for purification.
It achieves a high lithium recovery rate, simplifies the process, reduces acid consumption and operating costs, reduces wastewater generation, and improves the purity of lithium products.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium extraction technology and relates to a process for extracting lithium from lithium battery waste. Background Technology
[0002] Currently, the main recycling processes for spent lithium-ion batteries include hydrometallurgy and pyrometallurgy. Hydrometallurgy is the most widely researched and applied method, becoming mainstream due to its high recovery rate and good product purity. Its core steps are typically "acid leaching-purification-extraction-precipitation". However, traditional hydrometallurgical processes still face many challenges in practical applications. Existing technologies, especially the acid leaching stage, have a series of problems that urgently need to be solved: for example, traditional inorganic strong acid (such as sulfuric acid and hydrochloric acid) leaching methods have poor selectivity, require multi-step solvent extraction or selective precipitation to achieve metal separation, and suffer from problems such as high reagent consumption, high operating costs, and large amounts of wastewater generation. Furthermore, the extractant may cause secondary pollution.
[0003] Therefore, how to avoid the above problems and provide a method with a simple process flow that can achieve a high lithium recovery rate is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0004] The purpose of this invention is to provide a process for extracting lithium from lithium battery waste. The process of this invention can avoid the problems of using strong inorganic acids and poor selectivity. The process flow is simple and can achieve a high lithium recovery rate.
[0005] The objective of this invention can be achieved through the following technical solutions:
[0006] A process for extracting lithium from lithium battery waste includes the following steps:
[0007] S1. Pyrolyze the lithium battery waste at 350~400℃ under an inert atmosphere for 1~2 hours, and obtain the pretreated material after stripping.
[0008] S2, Lithium Leaching: The pretreated material is mixed with the primary leaching solution and stirred at 200 rpm for 60-90 min in an 80℃ water bath to obtain a mixture. After filtration, a lithium salt-rich leaching solution and leaching residue are obtained. The leaching residue is leached a second time with a 3-4.5 mol / L phosphoric acid solution and mixed with the above lithium salt-rich leaching solution to obtain a lithium-rich leaching solution.
[0009] S3. Lithium solution purification and concentration: After purifying and removing impurities from the lithium-rich leachate, it is evaporated and concentrated to obtain concentrated lithium solution, which can be used to synthesize lithium salts.
[0010] Further, in step S1, the primary immersion solution is a mixed solution of phosphoric acid solution, sodium citrate and sodium persulfate.
[0011] Furthermore, the concentration of the phosphoric acid solution is 2~4 mol / L.
[0012] Furthermore, the mass ratio of sodium citrate, sodium persulfate and pretreated materials is (0.5~0.8):1:(5~10).
[0013] Furthermore, the ratio of the pretreated material to the phosphoric acid solution is 1:(20~25)g / mL.
[0014] Furthermore, in step S2, the conditions for the second immersion are to maintain the temperature at 60~80℃ for 60~90 minutes.
[0015] Furthermore, in step S3, the purification and impurity removal process is as follows:
[0016] Add NaOH or LiOH solution to the lithium-rich leachate to adjust the pH to 5.0-6.0, and add 2% polyacrylamide by mass of the lithium-rich leachate. After standing and settling, filter by pressure or vacuum to obtain a clear liquid and filter residue. Add sodium hydroxide solution to the clear liquid to adjust the pH to 9-10. After standing and settling, filter to obtain refined lithium liquid.
[0017] Furthermore, in step S3, the lithium-rich leachate can be purified by adding an adsorbent, the preparation process of which is as follows:
[0018] Mixture A is obtained by dissolving ferric chloride hexahydrate and aluminum chloride hexahydrate in deionized water at a molar ratio of 3:1. Mixture B is obtained by dissolving disodium ethylenediaminetetraacetate and sodium hydroxide powder in deionized water at a molar ratio of 1:(12~15). Mixture A and mixture B are mixed in a volume ratio of 1:1 under stirring, aged at a constant temperature of 60~100℃ for 12h, filtered, washed with deionized water at 60℃, and dried to obtain product A.
[0019] Product A was dispersed in deionized water with ultrasonic assistance, and sodium polyacrylate and polyvinyl alcohol were added. The mixture was stirred at 400 rpm for 60-90 min, shaped into a mold, and then freeze-dried under vacuum to obtain the adsorbent.
[0020] Furthermore, after use, the adsorbent can be dispersed in 50 mL of 0.01 mol / L Na-EDTA eluent, sonicated for 10 min, rinsed with deionized water, and dried for continued use.
[0021] Furthermore, the mass ratio of product A, sodium alginate, sodium polyacrylate, polyvinyl alcohol, and deionized water is (0.2~0.5):(1~1.5):0.1:(0.5~1):50.
[0022] The beneficial effects of this invention are:
[0023] (1) This invention involves two immersions of lithium battery waste. First, the waste is immersed in a mixed solution of phosphoric acid, sodium citrate and sodium persulfate. The synergistic effect of the three substances reduces acid consumption and cost. Then, the leaching residue is immersed in a phosphoric acid solution to further dissolve the lithium in the lithium-containing mineral phase or impurity inclusions that could not be dissolved in the first water immersion. The solutions from the two immersions are combined and purified by adjusting the pH of the solution in stages. The resulting lithium recovery rate is high.
[0024] (2) At the same time, in order to remove impurities from lithium-rich leachate while retaining lithium metal in the solution to the greatest extent, a method of purification by adding lithium adsorbent is provided. First, iron-aluminum composite metal oxide / hydroxide is generated through co-precipitation and aging process, and then surface treatment is performed by sodium alginate, sodium polyacrylate and polyvinyl alcohol to obtain an adsorbent with huge specific surface area and rich surface functional groups, which can effectively remove impurity metal ions in lithium-rich leachate. Detailed Implementation
[0025] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.
[0026] Current processes mostly use strong acids to leach all the metals in lithium battery black powder in one go. Subsequent separation requires cumbersome solvent extraction or precipitation steps, resulting in long processes, high costs, and a lot of wastewater.
[0027] Therefore, the present invention provides a process for extracting lithium from lithium battery waste, comprising the following steps:
[0028] S1. Pyrolyze the lithium battery waste at 350~400℃ under an inert atmosphere for 1~2 hours, and obtain the pretreated material after stripping.
[0029] S2, Lithium Leaching: The pretreated material is mixed with the primary leaching solution and stirred at 200 rpm for 60-90 min in an 80℃ water bath to obtain a mixture. After filtration, a lithium salt-rich leaching solution and leaching residue are obtained. The leaching residue is leached a second time with a 3-4.5 mol / L phosphoric acid solution and mixed with the above lithium salt-rich leaching solution to obtain a lithium-rich leaching solution.
[0030] S3. Lithium solution purification and concentration: After purifying and removing impurities from the lithium-rich leachate, it is evaporated and concentrated to obtain concentrated lithium solution, which can be used to synthesize lithium salts.
[0031] The present invention first pyrolyzes the material at 300~400℃ under an inert atmosphere for 1~2 hours to completely remove residual electrolyte and binder. After peeling, positive electrode powder is obtained, which is the pretreated material.
[0032] Traditional processes use acid to leach all metals in a single step, resulting in a solution with extremely complex composition, requiring multiple extraction and precipitation steps for separation. This invention avoids the preparation of such a complex solution. The pretreated powder is first leached with a primary leaching solution, reducing acid consumption and cost. After the primary leaching, the leaching residue is leached a second time with a phosphoric acid solution. Phosphoric acid is a moderately strong acid that can dissolve lithium in lithium-containing mineral phases or impurity inclusions that were not dissolved in the first water leaching. It acts as both an acid leaching reagent and a highly efficient precipitant, forming extremely insoluble phosphate precipitates with specific high-valence metal ions dissolved in the leaching residue. The solutions from the two leaching processes are combined, purified, and then evaporated and concentrated to obtain a concentrated lithium solution, which can be used to synthesize lithium salts.
[0033] In one specific embodiment, in step S1, the primary immersion solution is a mixed solution of phosphoric acid solution, sodium citrate and sodium persulfate.
[0034] The primary leaching solution used in this invention employs phosphoric acid solution as the main solvent, in which sodium persulfate is responsible for oxidative decomposition, and sodium citrate is responsible for complexation and locking. Through synergistic action, they achieve highly efficient and selective lithium leaching in phosphoric acid. In the primary leaching solution, lithium exists in the form of free Li⁺, and sodium citrate can react with the dissolved Co. 2 ⁺、Ni 2 ⁺、Mn 2 ⁺ and other compounds form stable water-soluble complexes, effectively inhibiting the hydrolysis and precipitation of these impurity metals. This morphological difference makes it possible to achieve more refined separation techniques and make it easier to completely separate lithium from impurity metals.
[0035] In one specific embodiment, the concentration of the phosphoric acid solution is 2-4 mol / L.
[0036] For example, the concentration of the phosphoric acid solution may be 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, or any combination of two of these values.
[0037] Sodium citrate is stable and efficient under acidic conditions, has excellent compatibility with phosphoric acid systems, and its complexation effect remains effective at low pH levels, achieving efficient and selective leaching at the same phosphoric acid concentration, thus reducing acid consumption and cost.
[0038] In one specific embodiment, the mass ratio of sodium citrate, sodium persulfate and pretreated material is (0.5~0.8):1:(5~10).
[0039] For example, the mass ratio of sodium citrate, sodium persulfate and pretreated materials can be 0.5:1:5, 0.6:1:6, 0.7:1:7, 0.8:1:8, 0.8:1:10 or any two of these values.
[0040] At this ratio, sodium persulfate can fully disrupt the lattice structure of the cathode powder to release lithium ions, while avoiding the cost waste and subsequent impurity removal burden caused by excessive amounts. The three factors work synergistically to greatly reduce the concentration of impurity metals in the leachate while ensuring a high lithium recovery rate.
[0041] In one specific embodiment, the ratio of the pretreated material to the phosphoric acid solution is 1:(20~25)g / mL.
[0042] In one specific implementation, in step S2, the conditions for the secondary immersion are to maintain the temperature at 60-80°C for 60-90 minutes.
[0043] Using a temperature of 60~80℃ can effectively enhance the dissolution of encapsulated or sparingly soluble lithium compounds in the residue by the phosphoric acid solution, significantly improving the secondary recovery rate of lithium. At the same time, this temperature range can avoid excessive volatilization loss of phosphoric acid and large-scale dissolution of impurities caused by high temperature, ensuring the purity of the leachate.
[0044] In one specific implementation, the purification and impurity removal process in step S3 is as follows:
[0045] Add NaOH or LiOH solution to the lithium-rich leachate to adjust the pH to 5.0-6.0, and add 2% polyacrylamide by mass of the lithium-rich leachate. After standing and settling, filter by pressure or vacuum to obtain a clear liquid and filter residue. Add sodium hydroxide solution to the clear liquid to adjust the pH to 9-10. After standing and settling, filter to obtain refined lithium liquid.
[0046] In purifying and removing impurities from lithium-rich leachate, this invention first adjusts the pH of the solution to 5.0-6.0. Within this pH range, Fe... 3 ⁺ and Al 3 Li⁺ will completely form Fe(OH)₃ and Al(OH)₃ colloidal precipitates, while Li⁺ will hardly form any precipitate. To prevent colloids from passing through the filter and to promote precipitate growth, a small amount of flocculant polyacrylamide can be added. After settling, plate and frame filtration or vacuum filtration is performed to obtain a clear liquid and a filter residue containing iron and aluminum. Using LiOH can avoid introducing new alkali metal impurities (Na⁺), ensuring the purity of subsequent lithium products. Further adjusting the solution pH to 9-10 allows trace impurity ions remaining in the leachate to efficiently form hydroxide precipitates, while lithium ions remain stably present in the solution.
[0047] In one specific embodiment, in step S3, the lithium-rich leachate can also be purified by adding an adsorbent, the preparation process of which is as follows:
[0048] Mixture A is obtained by dissolving ferric chloride hexahydrate and aluminum chloride hexahydrate in deionized water at a molar ratio of 3:1. Mixture B is obtained by dissolving disodium ethylenediaminetetraacetate and sodium hydroxide powder in deionized water at a molar ratio of 1:(12~15). Mixture A and mixture B are mixed in a volume ratio of 1:1 under stirring, aged at a constant temperature of 60~100℃ for 12h, filtered, washed with deionized water at 60℃, and dried to obtain product A.
[0049] Product A was dispersed in deionized water with ultrasonic assistance, and sodium alginate, sodium polyacrylate and polyvinyl alcohol were added. The mixture was stirred at 400 rpm for 60-90 min, shaped into a mold and then freeze-dried under vacuum to obtain the adsorbent.
[0050] Traditional purification methods primarily rely on adjusting the pH of the lithium-rich solution. While this approach is simple, easy to implement, and achieves a high impurity removal rate, the lithium-rich solution still contains a variety of impurity ions. Simply adjusting the pH can easily lead to the formation of polymetallic hydroxides, resulting in the incorporation and loss of metallic lithium during the process. Therefore, to remove impurities while retaining a greater amount of metallic lithium in the solution, purification can be achieved by adding a lithium adsorbent.
[0051] Product A, generated through co-precipitation and aging, is an iron-aluminum composite metal oxide / hydroxide with a large specific surface area and abundant surface functional groups. Adding sodium alginate, sodium polyacrylate, and polyvinyl alcohol to product A, followed by vacuum freeze-drying, imparts macroscopic morphology and mechanical strength to the adsorbent while preserving its porous structure. Sodium polyacrylate, acting as a dispersant, rapidly absorbs and locks in a large amount of water through its numerous hydrophilic groups, significantly increasing the viscosity of the mixed slurry and preventing the sedimentation of product A nanoparticles, ensuring their uniform distribution in the three-dimensional network. Simultaneously, it also synergistically enhances the overall adsorption capacity of the final adsorbent through the interaction of its carboxyl groups with impurity ions. Polyvinyl alcohol, acting as a binder, possesses long molecular chains and excellent film-forming properties and mechanical strength. It intertwines with polymers such as sodium alginate through hydrogen bonds, effectively enhancing the toughness and durability of the adsorbent, avoiding the drawbacks of excessive brittleness and easy powdering after drying, allowing the molded adsorbent to withstand water flow impacts and be reused. Freeze-drying prevents the collapse of the pore structure, ensuring a high specific surface area. This structure avoids the problems of easy loss and difficulty in recycling when using nanoparticles directly, and possesses excellent mechanical strength and recyclability. Sodium alginate provides the main network framework required for shaping, giving the adsorbent good biocompatibility and biodegradability.
[0052] The prepared adsorbent can specifically adsorb residual cobalt, nickel, manganese and other impurity ions in the leachate, while its adsorption capacity for lithium ions is extremely low, thus significantly improving the purity of the solution. By directly adding the adsorbent to the lithium-rich leachate purification process, the adsorbent can be easily separated from the liquid phase, greatly simplifying the subsequent lithium solution purification process and reducing operating costs and time.
[0053] In one specific embodiment, after use, the adsorbent can be dispersed in 50 mL of 0.01 mol / L Na-EDTA eluent, sonicated for 10 min, rinsed with deionized water, and dried for continued use.
[0054] The adsorbent captures Co through surface coordination. 2 ⁺、Ni 2 ⁺、Mn 2 Impurity metal ions such as ⁺. EDTA is an extremely strong metal chelating agent; the stability constant of the complexes it forms with these metal ions is much higher than the binding energy between the functional groups on the adsorbent surface and these ions. Therefore, EDTA can effectively "steal" and complex these metal ions, causing them to desorb from the adsorbent surface and enter the solution.
[0055] In one specific embodiment, the mass ratio of product A, sodium alginate, sodium polyacrylate, polyvinyl alcohol, and deionized water is (0.2~0.5):(1~1.5):0.1:(0.5~1):50.
[0056] The invention provided by the present invention will be further described in detail below through specific embodiments.
[0057] It should be noted that, unless otherwise specified, the raw materials used in the following embodiments can be obtained by commercial purchase or conventional methods, and the experimental methods without specific conditions are all conventional methods and conditions well known in the art.
[0058] Example 1
[0059] S1. Pyrolyze the lithium battery waste at 350℃ under an inert atmosphere for 1 hour, and obtain the pretreated material after stripping.
[0060] S2, Lithium Leaching: The pretreated material is added to a mixed solution of phosphoric acid, sodium citrate and sodium persulfate, and stirred at 200 rpm for 60 min in an 80°C water bath to obtain a mixed solution. After filtration, a lithium salt-rich leachate and a leachate residue are obtained. The leachate residue is kept at 60°C for 60 min with a 3 mol / L phosphoric acid solution and then mixed with the above lithium salt-rich leachate to obtain a lithium-rich leachate.
[0061] S3. Lithium solution purification and concentration: Add LiOH solution to the lithium-rich leachate, adjust the pH of the solution to 5.0~6.0, and add 2% polyacrylamide by mass of the lithium-rich leachate. After standing and settling, filter by pressure or vacuum to obtain clear liquid and filter residue. Add sodium hydroxide solution to the clear liquid to adjust the pH of the solution to 9~10. After standing and settling, filter to obtain refined lithium solution. Evaporate and concentrate to obtain concentrated lithium solution. Concentrated lithium solution can be used to synthesize lithium salts.
[0062] The concentration of the phosphoric acid solution is 2 mol / L, and the mass ratio of sodium citrate, sodium persulfate and pretreated material is 0.5:1:5; the ratio of pretreated material to phosphoric acid solution is 1:20 g / mL.
[0063] Example 2
[0064] S1. Pyrolyze the lithium battery waste at 360℃ under an inert atmosphere for 1.5 hours, and obtain the pretreated material after stripping.
[0065] S2, Lithium Leaching: The pretreated material is added to a mixed solution of phosphoric acid, sodium citrate and sodium persulfate, and stirred at 200 rpm for 70 min in an 80°C water bath to obtain a mixed solution. After filtration, a lithium salt-rich leachate and a leachate residue are obtained. The leachate residue is kept at 70°C for 70 min with a 3.5 mol / L phosphoric acid solution and mixed with the above lithium salt-rich leachate to obtain a lithium-rich leachate.
[0066] S3. Lithium solution purification and concentration: Add LiOH solution to the lithium-rich leachate, adjust the pH of the solution to 5.0~6.0, and add 2% polyacrylamide by mass of the lithium-rich leachate. After standing and settling, filter by pressure or vacuum to obtain clear liquid and filter residue. Add sodium hydroxide solution to the clear liquid to adjust the pH of the solution to 9~10. After standing and settling, filter to obtain refined lithium solution. Evaporate and concentrate to obtain concentrated lithium solution. Concentrated lithium solution can be used to synthesize lithium salts.
[0067] The concentration of the phosphoric acid solution is 3 mol / L, and the mass ratio of sodium citrate, sodium persulfate and pretreated material is 0.6:1:8; the ratio of pretreated material to phosphoric acid solution is 1:22 g / mL.
[0068] Example 3
[0069] S1. Pyrolyze the lithium battery waste at 400℃ under an inert atmosphere for 2 hours, and obtain the pretreated material after stripping.
[0070] S2, Lithium Leaching: The pretreated material is added to a mixed solution of phosphoric acid, sodium citrate and sodium persulfate, and stirred at 200 rpm for 90 min in an 80°C water bath to obtain a mixed solution. After filtration, a lithium salt-rich leachate and a leachate residue are obtained. The leachate residue is kept at 80°C for 90 min with a 4.5 mol / L phosphoric acid solution and mixed with the above lithium salt-rich leachate to obtain a lithium-rich leachate.
[0071] S3. Lithium solution purification and concentration: Add LiOH solution to the lithium-rich leachate, adjust the pH of the solution to 5.0~6.0, and add 2% polyacrylamide by mass of the lithium-rich leachate. After standing and settling, filter by pressure or vacuum to obtain clear liquid and filter residue. Add sodium hydroxide solution to the clear liquid to adjust the pH of the solution to 9~10. After standing and settling, filter to obtain refined lithium solution. Evaporate and concentrate to obtain concentrated lithium solution. Concentrated lithium solution can be used to synthesize lithium salts.
[0072] The concentration of the phosphoric acid solution is 4 mol / L, and the mass ratio of sodium citrate, sodium persulfate and pretreated material is 0.8:1:10; the ratio of pretreated material to phosphoric acid solution is 1:25 g / mL.
[0073] Example 4
[0074] This embodiment is basically the same as Embodiment 1, except that step S3 in this embodiment is as follows: an adsorbent is added to the lithium-rich leachate for purification, and the preparation process of the adsorbent is as follows:
[0075] Mixture A was prepared by dissolving ferric chloride hexahydrate and aluminum chloride hexahydrate in deionized water at a molar ratio of 3:1. Mixture B was prepared by dissolving disodium ethylenediaminetetraacetate and sodium hydroxide powder in deionized water at a molar ratio of 1:12. Mixture A and mixture B were mixed in a volume ratio of 1:1 under stirring and aged at 60°C for 12 hours. After filtration, washing with deionized water at 60°C, and drying, product A was obtained.
[0076] Product A was dispersed in deionized water with ultrasonic assistance, and sodium alginate, sodium polyacrylate and polyvinyl alcohol were added. The mixture was stirred at 400 rpm for 60 min. After molding, the adsorbent was obtained by vacuum freeze drying. The mass ratio of product A, sodium alginate, sodium polyacrylate, polyvinyl alcohol and deionized water was 0.2:1:0.1:0.5:50.
[0077] After adsorption, the purified lithium liquid is obtained by filtration, and then concentrated by evaporation to obtain concentrated lithium liquid. The concentrated lithium liquid can be used to synthesize lithium salts.
[0078] Example 5
[0079] This embodiment is basically the same as Embodiment 1, except that step S3 in this embodiment is as follows: an adsorbent is added to the lithium-rich leachate for purification, and the preparation process of the adsorbent is as follows:
[0080] Mixture A was obtained by dissolving ferric chloride hexahydrate and aluminum chloride hexahydrate in deionized water at a molar ratio of 3:1. Mixture B was obtained by dissolving disodium ethylenediaminetetraacetate and sodium hydroxide powder in deionized water at a molar ratio of 1:13. Mixture A and mixture B were mixed in a volume ratio of 1:1 under stirring, aged at 80°C for 12 hours, filtered, washed with deionized water at 60°C, and dried to obtain product A.
[0081] Product A was dispersed in deionized water with ultrasonic assistance, and sodium alginate, sodium polyacrylate and polyvinyl alcohol were added and stirred at 400 rpm for 70 min. After molding, the adsorbent was obtained by vacuum freeze drying. The mass ratio of product A, sodium alginate, sodium polyacrylate, polyvinyl alcohol and deionized water was 0.3:1.2:0.1:0.8:50.
[0082] After adsorption, the purified lithium liquid is obtained by filtration, and then concentrated by evaporation to obtain concentrated lithium liquid. The concentrated lithium liquid can be used to synthesize lithium salts.
[0083] Example 6
[0084] This embodiment is basically the same as Embodiment 1, except that step S3 in this embodiment is as follows: an adsorbent is added to the lithium-rich leachate for purification, and the preparation process of the adsorbent is as follows:
[0085] Mixture A was prepared by dissolving ferric chloride hexahydrate and aluminum chloride hexahydrate in deionized water at a molar ratio of 3:1. Mixture B was prepared by dissolving disodium ethylenediaminetetraacetate and sodium hydroxide powder in deionized water at a molar ratio of 1:15. Mixture A and mixture B were mixed in a volume ratio of 1:1 under stirring and aged at 100℃ for 12 hours. After filtration, washing with deionized water at 60℃, and drying, product A was obtained.
[0086] Product A was dispersed in deionized water with ultrasonic assistance, and sodium alginate, sodium polyacrylate, and polyvinyl alcohol were added. The mixture was stirred at 400 rpm for 90 min. After molding, the adsorbent was obtained by vacuum freeze drying. The mass ratio of product A, sodium alginate, sodium polyacrylate, polyvinyl alcohol and deionized water was 0.5:1.5:0.1:1:50.
[0087] The ratio of adsorbent mass to lithium-rich solution volume is 1 g / 250 mL. After adsorption, the purified lithium solution is obtained by filtration, and then concentrated by evaporation to obtain concentrated lithium solution. The concentrated lithium solution can be used to synthesize lithium salts.
[0088] Comparative Example 1
[0089] Comparative Example 1 is basically the same as Example 1, except that the first immersion solution in this comparative example is a mixed solution of phosphoric acid solution and sodium persulfate.
[0090] Comparative Example 2
[0091] Comparative Example 2 is basically the same as Example 1, except that the first immersion solution in this comparative example is a mixed solution of phosphoric acid solution and sodium citrate.
[0092] Comparative Example 3
[0093] Comparative Example 3 is basically the same as Example 1, except that the first immersion solution in this comparative example is a phosphoric acid solution.
[0094] Comparative Example 4
[0095] Comparative Example 4 is basically the same as Example 1, except that no second immersion was performed in this comparative example.
[0096] Comparative Example 5
[0097] Comparative Example 5 is basically the same as Example 1, except that polyacrylamide was not added in step S3 of this comparative example.
[0098] Comparative Example 6
[0099] Comparative Example 6 is basically the same as Example 4, except that sodium polyacrylate was not added during the preparation of the adsorbent in this comparative example.
[0100] Comparative Example 7
[0101] Comparative Example 7 is basically the same as Example 4, except that polyvinyl alcohol was not added during the preparation of the adsorbent in this comparative example.
[0102] Comparative Example 8
[0103] Comparative Example 8 is basically the same as Example 4, except that sodium polyacrylate and polyvinyl alcohol were not added during the preparation of the adsorbent in this comparative example.
[0104] Performance testing:
[0105] Waste lithium cobalt oxide battery electrodes were used for testing. Based on the lithium content in the lithium cobalt oxide electrode powder, the lithium ion concentration in the refined lithium solution, and the volume of the refined lithium solution, the lithium recovery rate was calculated. The results are shown in Table 1.
[0106] Table 1
[0107] Group Lithium recovery rate / % Example 1 95.8 Example 2 96.2 Example 3 96.8 Example 4 97.3 Example 5 97.8 Example 6 98.2 Comparative Example 1 91.2 Comparative Example 2 86.2 Comparative Example 3 80.8 Comparative Example 4 92.3 Comparative Example 5 92.0 Comparative Example 6 91.7 Comparative Example 7 93.5 Comparative Example 8 87.6
[0108] Based on the above data, it can be seen that the present invention can achieve efficient lithium recovery from lithium battery waste.
[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A process for extracting lithium from lithium battery waste, characterized in that, Includes the following processes: S1. Pyrolyze the lithium battery waste at 350~400℃ under an inert atmosphere for 1~2 hours, and obtain the pretreated material after stripping. S2. Lithium Leaching: The pretreated material is mixed with the primary leaching solution and stirred at 200 rpm for 60-90 min in an 80°C water bath to obtain a mixed solution. After filtration, a lithium-rich leaching solution and leaching residue are obtained. The leaching residue is leached a second time with a 3-4.5 mol / L phosphoric acid solution and mixed with the above lithium-rich leaching solution to obtain a lithium-rich leaching solution. The primary leaching solution is a mixed solution of phosphoric acid solution, sodium citrate and sodium persulfate. S3. Lithium Solution Purification and Concentration: After purifying and removing impurities from the lithium-rich leachate, the solution is evaporated and concentrated to obtain a concentrated lithium solution, which can be used to synthesize lithium salts. The lithium-rich leachate is purified by adding an adsorbent, the preparation process of which is as follows: Mixture A is obtained by dissolving ferric chloride hexahydrate and aluminum chloride hexahydrate in deionized water at a molar ratio of 3:
1. Mixture B is obtained by dissolving disodium ethylenediaminetetraacetate and sodium hydroxide powder in deionized water at a molar ratio of 1:(12~15). Mixture A and mixture B are mixed in a volume ratio of 1:1 under stirring, aged at a constant temperature of 60~100℃ for 12h, filtered, washed with deionized water at 60℃, and dried to obtain product A. Product A was dispersed in deionized water with ultrasonic assistance, and sodium alginate, sodium polyacrylate and polyvinyl alcohol were added. The mixture was stirred at 400 rpm for 60-90 min, shaped into a mold and then freeze-dried under vacuum to obtain the adsorbent.
2. The process for extracting lithium from lithium battery waste according to claim 1, characterized in that, The concentration of the phosphoric acid solution is 2~4 mol / L.
3. The process for extracting lithium from lithium battery waste according to claim 1, characterized in that, The mass ratio of sodium citrate, sodium persulfate and pretreated materials is (0.5~0.8):1:(5~10).
4. The process for extracting lithium from lithium battery waste according to claim 1, characterized in that, The ratio of the pretreated material to the phosphoric acid solution is 1:(20~25)g / mL.
5. The process for extracting lithium from lithium battery waste according to claim 1, characterized in that, In step S2, the conditions for the second immersion are to maintain the temperature at 60~80℃ for 60~90 minutes.
6. The process for extracting lithium from lithium battery waste according to claim 1, characterized in that, After use, the adsorbent can be dispersed in 50 mL of 0.01 mol / L Na-EDTA eluent, sonicated for 10 min, rinsed with deionized water, and dried for continued use.
7. The process for extracting lithium from lithium battery waste according to claim 1, characterized in that, The mass ratio of product A, sodium alginate, sodium polyacrylate, polyvinyl alcohol, and deionized water is (0.2~0.5):(1~1.5):0.1:(0.5~1):50.