Method for extracting lithium from waste ternary lithium battery

Abstract

The invention discloses a method for extracting lithium from a waste ternary lithium battery. The method comprises the following steps: obtaining waste ternary lithium battery powder; obtaining waste ternary lithium battery powder; the method comprises the following steps: adding waste ternary lithium battery powder into alkali liquor, and carrying out impurity removal reaction to obtain impurity-removed powder; carrying out reduction roasting on the impurity-removed powder to obtain roasted battery powder; adding the roasted battery powder into water, carrying out lithium extraction reaction, and filtering to obtain a lithium-containing solution and water leaching residues; the water leaching residues are subjected to acid leaching treatment, and a metal-rich product and regenerated graphite are obtained; mixing the lithium-containing solution with a carbonizer, and heating for reaction to obtain lithium carbonate; according to the method, the lithium recovery rate is finally increased by removing the impurities step by step, destroying the lattice structure and optimizing the leaching conditions, the impurities are few, and the method can be suitable for battery powder with a wide range of impurities.

Description

Technical Field

[0001] The present invention relates to the technical field of waste battery recycling, and in particular to a method for extracting lithium from waste ternary lithium batteries. Background Art

[0002] Spent ternary lithium batteries contain a variety of recyclable resources, such as lithium, manganese, nickel, and cobalt. With the rapid development of the new energy vehicle industry, the number of spent ternary lithium batteries has exploded. Efficiently recovering these valuable metals has become a key issue in resource recycling. However, due to the complexity of battery structures and the diversity of material components, achieving efficient separation and recovery of these metal elements still faces numerous technical challenges.

[0003] During the recycling process, battery powder is destroyed during mechanical crushing, and impurity elements are distributed among the positive and negative electrode powders. This physical structural disruption causes the active material to intermingle with components such as the current collector and binder, forming a complex multiphase system. In particular, during the crushing process, mechanical forces can cause powders of different components to break and deform to varying degrees, altering their surface properties. Furthermore, during industrial production, battery powders inevitably adhere to each other. This adhesion phenomenon primarily stems from the melting and resolidification of the organic binder in the electrode material during crushing, as well as electrostatic adsorption between metal powders. These factors combine to make lithium and valuable metal recovery difficult, severely impacting the efficiency of subsequent separation and purification processes. Currently, the most commonly used recovery method is acid leaching, which has low lithium recovery rates, low purity, and limited applicability. For example, while effective for recovering battery powders with specific impurity levels, the recovery rate decreases significantly after replacing used battery powder. Traditional acid leaching processes typically use inorganic acids such as sulfuric acid and hydrochloric acid as leaching agents. Although this allows for initial lithium extraction, it is difficult to avoid the co-dissolution of other metal ions during the leaching process, resulting in poor lithium selectivity. Furthermore, because lithium ions have similar properties to other cations in the solution, the subsequent separation and purification process requires multiple extraction and precipitation steps, which not only increases process complexity but also results in lithium loss. Furthermore, the aqueous lithium extraction process is prone to introducing new impurities, affecting the purity of the final product.

[0004] Therefore, developing an efficient and selective lithium recovery method is of great significance for improving the recovery rate and purity of lithium, reducing recycling costs, and realizing the resource utilization of waste ternary lithium batteries. Summary of the Invention

[0005] In view of this, the present application provides a method for extracting lithium from waste ternary lithium batteries, which is used to solve the problem of how to improve the yield and purity of lithium recovered from waste ternary lithium batteries.

[0006] In order to achieve the above technical objectives, this application adopts the following technical solutions: In a first aspect, the present application provides a method for extracting lithium from waste ternary lithium batteries, comprising the following steps: Obtain waste ternary lithium battery powder; Adding waste ternary lithium battery powder into alkaline solution to carry out impurity removal reaction to obtain impurity-removed powder; The impurity-removed powder is subjected to reduction roasting to obtain roasted battery powder; The calcined battery powder is added to water to carry out lithium extraction reaction, filtered to obtain a lithium-containing solution and water-leached residue; the lithium-containing solution is mixed with a carbonizing agent, heated for reaction, and lithium carbonate is obtained.

[0007] Preferably, before adding the waste ternary lithium battery powder to the alkaline solution, the waste ternary lithium battery powder is also ball-milled; the waste ternary lithium battery powder is prepared by a waste battery crushing and screening process; and / or the waste ternary lithium battery powder is subjected to a pyrolysis or non-pyrolysis process; the composition of the waste ternary lithium battery powder must meet the following mass percentage requirements: aluminum (Al) ≤5%, copper (Cu) ≤5%, fluorine (F) ≤6%.

[0008] Preferably, the concentration of the alkali solution is 1-10 wt %.

[0009] Preferably, the temperature of the impurity removal reaction is 60-80° C. and the time is 2-4 hours.

[0010] Preferably, the reduction roasting temperature is 400-700° C., the roasting time is 40-120 min, and the heating rate is 5-20° C. / min.

[0011] Preferably, the reducing agent used in the reduction roasting is one or more of 5% to 10% hydrogen, graphite, coke, activated carbon, and sulfuric acid.

[0012] Preferably, the liquid-to-solid ratio of the calcined battery powder to water is (30-80) mL:1 g.

[0013] Preferably, the temperature of the lithium extraction reaction is 50-100° C., and the time is 40-180 min.

[0014] Preferably, the water leaching residue is subjected to acid leaching to obtain metal-rich products and regenerated graphite.

[0015] Preferably, the carbonizing agent includes one or more of CO2, Na2CO3, and NaHCO3; the heating reaction temperature is 80-90°C and the time is 1-3 hours.

[0016] The beneficial effects of the present application are as follows: the present application achieves a lithium recovery rate of ≥90% for battery powder with different impurity contents by removing impurities, destroying the lattice structure, and optimizing the leaching conditions in steps, and the purity is significantly higher than that of the traditional acid leaching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the process flow chart of this application; Figure 2 is the amount of solid lithium residue and lithium removal rate of different processes; Figure 3 is the solid fluorine residue and fluorine removal rate of different processes; Figure 4 is the amount of solid aluminum residue and aluminum removal rate of different processes. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] The present application provides a method for extracting lithium from waste ternary lithium batteries, comprising the following steps: S1. Obtain waste ternary lithium battery powder; S2. The waste ternary lithium battery powder is added to the alkali solution to perform a decontamination reaction to obtain a decontamination powder; S3. The impurity-removing powder is subjected to reduction roasting to obtain a roasted battery powder; S4. The calcined battery powder was added to water for lithium extraction reaction, filtered to obtain a lithium-containing solution and leaching residue; S5. Mix the lithium-containing solution with a carbonizing agent, and heat them for reaction to obtain lithium carbonate.

[0020] In some embodiments, before adding the waste ternary lithium battery powder to the alkaline solution, the waste ternary lithium battery powder is also ball-milled.

[0021] The process of the method for extracting lithium from waste ternary lithium batteries of the present application is as follows: first, the waste lithium ternary lithium-ion batteries are crushed into waste ternary lithium battery powder to improve the efficiency of subsequent processing; secondly, impurities such as aluminum and fluorine in the waste ternary lithium battery powder are selectively removed by alkali washing (such as Al reacts with NaOH to form soluble NaAlO2, and LiF decomposes into Li⁺ and F⁻); then, through reduction roasting, the lattice structure of the ternary material is destroyed by thermal reduction (such as LiCoO→CoO +Li2O), releasing lithium as a soluble oxide (Li2O); then, water leaching is used to selectively leach lithium (Li2O + H2O→2LiOH), while Ni, Co, and Mn remain in the water leaching residue in the form of oxides; finally, lithium is precipitated into lithium carbonate by carbonization, and the water leaching residue is used to recover valuable metals by acid leaching.

[0022] This application achieves a lithium recovery rate of more than 90% by removing impurities, destroying the lattice structure, and optimizing the leaching conditions in steps, and the purity is significantly higher than that of the traditional acid leaching process.

[0023] In some embodiments, the concentration of the alkali solution is 1-10 wt %.

[0024] In this embodiment, the alkali solution includes but is not limited to one of a NaOH solution, a KOH solution, or a Ca(OH)2 solution. Preferably, the alkali solution is a NaOH solution. Limiting the concentration of the alkali solution is beneficial for balancing cost and reaction efficiency, and avoiding excessive corrosion of the material due to excessive concentration.

[0025] In some embodiments, the temperature of the impurity removal reaction is 60-90° C., and the time is 2-4 hours.

[0026] In this embodiment, the temperature of the impurity removal reaction is within a limited range, which has the following advantages: 1. Optimized reaction kinetics: Within this temperature range, the dissolution rate of impurities such as aluminum and fluorine by the alkali solution is significantly improved, and the lithium leaching reaction activity is enhanced; 2. Impurity removal efficiency: High temperature promotes the destruction of aluminum oxide film (such as the reaction of Al2O3 with NaOH to form NaAlO2) and accelerates the decomposition of fluorides (such as LiF), thereby improving the impurity removal rate; 3. Avoiding overreaction: If the temperature is too high (>90°C), it will cause excessive damage to the material structure and lead to excessive Li loss; if the temperature is too low (<60°C), the reaction rate is insufficient, and the impurity removal rate and lithium leaching rate are significantly reduced. At 60-90°C, the reaction rate can be accelerated to ensure efficient impurity removal.

[0027] In some embodiments, the reduction calcination temperature is 400-800° C., the calcination time is 40-120 min, and the heating rate is 5-20° C. / min.

[0028] In this embodiment, the reduction calcination temperature is 400-800°C, which is higher than the decomposition temperature of lithium oxide (about 300°C) but lower than the reduction temperature of transition metal oxides (such as CoO needs to be >700°C) to avoid interference from metal reduction.

[0029] In some embodiments, the reducing agent used in the reduction roasting is one or more of 5% to 10% hydrogen, graphite, coke, activated carbon, and sulfuric acid.

[0030] In this embodiment, an inert atmosphere includes, but is not limited to, one or more of N2 and Ar, which helps prevent oxidation of the material and maintain a reducing environment. If an air atmosphere is selected, carbon will inevitably react with oxygen in the air atmosphere to produce carbon dioxide, consuming the carbon source. The use of organic carbon as a reducing agent can provide reducing conditions without introducing new impurities.

[0031] In some embodiments, the liquid-to-solid ratio of the calcined battery powder to water is (30-80) mL:1 g.

[0032] In this embodiment, the liquid-to-solid ratio is within a limited range, which can ensure that lithium is fully dissolved and reduce the co-dissolution of impurity metals in the liquid phase.

[0033] In some embodiments, the temperature of the lithium extraction reaction is 50-100° C., preferably, the temperature is 60-80° C., and the time is 40-180 min.

[0034] In this embodiment, the temperature of the lithium extraction reaction is within a limited range, which is beneficial to improving the solubility and diffusion rate of lithium.

[0035] In some embodiments, the method further comprises subjecting the water leaching residue to acid leaching to obtain metal-rich products and regenerated graphite.

[0036] In some embodiments, the carbonizing agent includes one or more of CO2, Na2CO3, and NaHCO3; the heating reaction temperature is 80-90°C and the time is 1-3 hours.

[0037] In this embodiment, the heating temperature is within a limited range, which is beneficial to accelerating the growth of lithium carbonate crystal nuclei and improving the purity of the precipitate.

[0038] The present invention is further described below through specific examples.

[0039] Source of raw materials: By mass, the chemical composition of the waste ternary lithium battery powder used in Examples 1-15 and Comparative Examples 1-7 is shown in the composition of "Battery Powder" in Table 1, and the chemical composition of the waste ternary lithium battery powder used in Example 16 is shown in the composition of "Battery Powder 1" in Table 1.

[0040] Table 1 Chemical composition of cathode materials of waste ternary lithium batteries

[0041] Examples 1-15 A method for extracting lithium from waste ternary lithium batteries comprises the following steps: S1. Discharge, crush, and physically separate the used lithium ternary lithium-ion batteries to obtain battery powder; S2. Add a certain amount of waste ternary lithium battery powder to 250 ml of 1 wt% NaOH solution, stir at 300 rpm, and heat in an 80°C oil bath for 2 h to obtain a cleaned powder. S3 in an argon-hydrogen mixed atmosphere, the impurity-removing powder was added to graphite in a ratio of 7:3, placed in a tube furnace, and reduction roasted. The reduction roasting conditions are shown in Table 2 to obtain a calcined battery powder; S4. The calcined battery powder was added to water at a liquid-solid ratio of 50ml: 1g, and the lithium extraction reaction was carried out at 50-100 ° C for 100min. After filtration, a lithium-containing solution and leaching residue were obtained; the leaching residue was placed in a 0.5 L acid leaching tank for acid leaching, and after solid-liquid separation, a nickel-cobalt solution and regenerated graphite were obtained; S5. Mix the lithium-containing solution with a carbonizing agent, and heat to 80°C for 1 hour to obtain lithium carbonate.

[0042] Table 2 Reduction roasting conditions of Examples 1-15

[0043] Example 16 A method for extracting lithium from waste ternary lithium batteries. Other contents are the same as those in Example 6, except that the battery powder is replaced with battery powder 1.

[0044] Comparative Example 1 A method for extracting lithium from waste ternary lithium batteries, the other contents of which are the same as those of Example 4, except that it only includes steps S1 and S3, and the roasting temperature of step S3 is 400°C.

[0045] Comparative Example 2 A method for extracting lithium from waste ternary lithium batteries, the other contents of which are the same as those of Example 4, except that it only includes steps S1 and S3, and the roasting temperature of step S3 is 600°C.

[0046] Comparative Example 3 A method for extracting lithium from waste ternary lithium batteries, the other contents of which are the same as those of Example 4, except that it only includes steps S1 and S2.

[0047] Comparative Example 4 A method for extracting lithium from waste ternary lithium batteries, the other contents are the same as those in Example 4, except that the roasting temperature is 400°C.

[0048] Comparative Example 5 A method for extracting lithium from waste ternary lithium batteries, the other contents are the same as those of Example 4, except that the roasting treatment in step S3 is performed first, and then the alkaline washing treatment in step S2 is performed, and the roasting temperature is 400°C.

[0049] Comparative Example 6 A method for extracting lithium from waste ternary lithium batteries, the other contents of which are the same as those of Example 4, except that the roasting treatment in step S3 is performed first, and then the alkaline washing treatment in step S2 is performed.

[0050] Comparative Example 7 A method for extracting lithium from waste ternary lithium batteries, the other contents are the same as those of Example 4, except that step S2 is not included.

[0051] Testing and Evaluation The lithium leaching rates of the lithium-containing solutions of Examples 1-15 were tested, and the results are shown in Table 3.

[0052] Table 3 Lithium leaching rate of Examples 1-15

[0053] It can be seen that the lithium leaching rate of the solution of the present application is high, and the effect is better when calcined at 700°C.

[0054] The solid lithium residue and lithium removal rate of the waste ternary lithium batteries of Example 4 and Comparative Examples 1-7 were tested. Figure 2 As shown; the solid fluorine residue and fluorine removal rate of the waste ternary lithium batteries of test example 4 and comparative examples 1-7 are shown. Figure 3 As shown; the solid aluminum residue and aluminum removal rate of the waste ternary lithium batteries of test example 4 and comparative examples 1-7 are shown. Figure 4 shown.

[0055] Depend on Figure 2-4 It can be seen that the recovery rate of lithium extraction using the roasting process alone is not high and there are many impurities. It is difficult to remove impurities such as Al and F through a simple roasting heat treatment method. Instead, it promotes the conversion of impurities into insoluble substances, which is not conducive to subsequent leaching and lithium extraction. The F element can be removed preferentially through alkaline washing, and the Al removal rate can be further improved through subsequent roasting. The "alkaline washing + roasting" process is better than the "roasting + alkaline washing" process, which is conducive to the subsequent selective leaching of lithium.

[0056] It can be seen from Example 16 that the method of the present application has good compatibility and good lithium extraction effect for ternary powders with different impurity contents and different sources.

[0057] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for extracting lithium from waste ternary lithium batteries, characterized in that: The following steps are involved: Obtain waste ternary lithium battery powder; Adding the waste ternary lithium battery powder into an alkaline solution to carry out an impurity removal reaction to obtain an impurity-removed powder; performing reduction roasting on the impurity-removed powder to obtain roasted battery powder; adding the calcined battery powder into water to carry out lithium extraction reaction, filtering to obtain a lithium-containing solution and water-leached residue; The lithium-containing solution is mixed with a carbonizing agent and heated for reaction to obtain lithium carbonate.

2. The method for extracting lithium from waste ternary lithium batteries according to claim 1, characterized in that: Before adding the waste ternary lithium battery powder to the alkaline solution, the waste ternary lithium battery powder is also ball-milled; the waste ternary lithium battery powder is prepared by a waste battery crushing and screening process; and / or the waste ternary lithium battery powder is subjected to a pyrolysis or non-pyrolysis process; the composition of the waste ternary lithium battery powder must meet the following mass percentage requirements: aluminum (Al) ≤5%, copper (Cu) ≤5%, fluorine (F) ≤6%.

3. The method for extracting lithium from waste ternary lithium batteries according to claim 1, characterized in that: The concentration of the alkali solution is 1-10 wt %.

4. The method for extracting lithium from waste ternary lithium batteries according to claim 1, characterized in that: The temperature of the impurity removal reaction is 60-90° C. and the time is 2-4 hours.

5. The method for extracting lithium from waste ternary lithium batteries according to claim 1, characterized in that: The reduction roasting temperature is 400-800° C., the roasting time is 40-120 min, and the heating rate is 5-20° C. / min.

6. The method for extracting lithium from waste ternary lithium batteries according to claim 1, characterized in that: The reducing agent used in the reduction roasting is one or more of 5% to 10% hydrogen, graphite, coke, activated carbon, and sulfuric acid.

7. The method for extracting lithium from waste ternary lithium batteries according to claim 1, characterized in that: The liquid-to-solid ratio of the calcined battery powder to water is (30-80) mL:1 g.

8. The method for extracting lithium from waste ternary lithium batteries according to claim 1, characterized in that: The temperature of the lithium extraction reaction is 50-100° C., and the time is 40-180 minutes.

9. The method for extracting lithium from waste ternary lithium batteries according to claim 1, characterized in that: The method also includes subjecting the water-leached residue to acid leaching to obtain metal-rich products and regenerated graphite.

10. The method for extracting lithium from waste ternary lithium batteries according to claim 1, characterized in that: The carbonizing agent includes one or more of CO2, Na2CO3, and NaHCO3; the heating reaction temperature is 80-90°C and the reaction time is 1-3 hours.

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