Method for leaching valuable metals from spent cathode material

Abstract

This invention belongs to the field of waste battery recycling, specifically relating to a method for leaching valuable metals from waste cathode materials. Waste cathode materials containing metal M are placed in a leaching solution containing components A and B for leaching treatment. Subsequently, oil and water are separated to obtain an aqueous phase A and an oil phase. The oil phase is back-extracted to obtain a regenerated phase enriched with component A and a back-extraction solution. The aqueous phase A and the back-extraction solution are combined to obtain a leaching solution enriched with metal M. Component A is a solution of formula 1; component B is an inorganic sodium salt. This invention's process has excellent leaching effect and also excellent cyclic leaching effect.

Description

Technical Field

[0001] This invention relates to the field of battery material recycling, specifically to the field of recycling waste cathode materials. Background Technology

[0002] Due to the limited cycle life of lithium-ion batteries and their high nickel content, they have become a source of nickel-containing hazardous waste. With the large-scale mining of metal minerals, enriching valuable metals from the ternary cathode materials of spent lithium batteries is an inevitable trend for achieving the harmless and resource-based treatment of lithium battery waste.

[0003] Currently, the main methods for extracting valuable metals from ternary cathode materials of spent lithium batteries are pyrometallurgy, hydrometallurgy, and bioleaching. For example, Chinese patent document CN116154346A discloses a method for regenerating spent lithium battery cathode materials. The process steps include: S1: adding acid to the spent lithium battery cathode material and carrying out a selective lithium extraction reaction at 160-240℃, separating the filtrate and filter residue 1, wherein the filter residue 1 is a nickel-cobalt-manganese compound and the filtrate is a lithium salt solution; S2: mixing lithium source 1, transition metal source, and additive solution to obtain a mixture 1, and then mixing it with the filter residue 1 obtained in S1 and carrying out a hydrothermal reaction, separating the reaction products to obtain filter residue 2 and filtrate; S3: ball milling the filter residue 2 obtained in S2 with lithium source 2, and calcining the resulting mixture to obtain recycled lithium battery cathode material. For example, Chinese patent document CN116102080A discloses a method using carbothermal reduction treatment of waste positive and negative electrode materials. Sodium is separated from the metal through water leaching. The sodium in the leaching solution is evaporated and crystallized to obtain sodium carbonate. The metal leaching residue after water leaching is separated into a high-purity nickel-manganese-iron solution and leaching residue through acid leaching. A precursor is prepared using the nickel-manganese-iron solution, and then the precursor is mixed with sodium carbonate and sintered in a muffle furnace to obtain NaNi with excellent electrochemical performance. 0.4 Fe 0.2 Mn 0.4 O2 cathode material.

[0004] Existing methods mostly suffer from drawbacks such as high energy consumption, high pollution, long processing time, limited effectiveness in leaching low-content valuable metals, difficulty in reusing leaching agents, and significant pressure on waste treatment. Therefore, it is necessary to provide a highly efficient and environmentally friendly method for extracting valuable metals from waste lithium-ion battery ternary cathode materials. Summary of the Invention

[0005] In view of the problems of unsatisfactory metal recovery rate and large amount of waste generated from existing waste cathode materials, the primary objective of this invention is to provide a leaching method for valuable metals in waste cathode materials, aiming to provide an organometallic leaching method that allows for the recycling of leaching agents while also ensuring excellent leaching performance.

[0006] A method for leaching valuable metals from waste cathode materials involves placing waste cathode materials containing metal M into a leaching solution containing components A and B for leaching treatment, followed by oil-water separation to obtain an aqueous phase A and an oil phase. The oil phase is then back-extracted to obtain a regenerated phase (regenerated leaching solvent) enriched with component A and a back-extraction solution. The aqueous phase A and the back-extraction solution are combined to obtain a leaching solution enriched with metal M.

[0007] Component A is a solution of Formula 1 (liquid Formula 1);

[0008]

[0009] Component B is an inorganic sodium salt;

[0010] During the leaching process, the pH of the system is controlled to be above 3;

[0011] The M includes at least one of Ni, Co, Mn, and Li.

[0012] This invention innovatively demonstrates that by using components A and B to leach waste cathode materials, and further coordinating with the combined pH control during the leaching stage, a synergistic effect can be achieved. This allows for the attainment of excellent leaching performance of metal M without the need for transformation of the waste cathode materials. More importantly, the leaching components described in this invention possess excellent recycling and regeneration capabilities.

[0013] In this invention, the waste cathode material contains Li, and also contains at least one of Ni, Co, and Mn. For example, it can be material stripped from waste lithium-ion battery cathode sheets, wherein the active material is an oxidized lithium salt of at least one of nickel, cobalt, and manganese metals.

[0014] In this invention, the waste positive electrode material is also permitted to contain at least one of the following: conductive agent, binder, electrolyte, and separator.

[0015] In this invention, there are no special requirements for the content of active material in the waste cathode material. Considering the processing cost and process value, the content of metal M is above 20 wt.%, and can be further 30-50 wt.%. This invention can still show excellent extraction effect for waste cathode materials with low metal content.

[0016] In this invention, the waste cathode material is pre-ground and sieved;

[0017] Preferably, the grinding time is 30-60 minutes;

[0018] Preferably, the sieve used for sieving is a 100-mesh sieve.

[0019] In this invention, the combination of component A, component B, and pH during the leaching stage is key to achieving efficient extraction of waste cathode materials without transformation, while also ensuring excellent cycle stability.

[0020] In this invention, component A is obtained by reacting compounds of formula a and formula b;

[0021]

[0022] The A- is an anion, preferably Cl-. - NO3 - At least one of Ac-;

[0023] The B+ is a cation, preferably Li. + Na + K + At least one of them.

[0024] Preferably, the molar ratio of formula a and formula b is 1:0.95 to 1.05;

[0025] In this invention, the solvent used in the reaction stage is an aqueous solvent; water can be used to consider processing costs. The temperature during the reaction stage can be 50–90°C. The reaction time can be 3–4 hours.

[0026] In this invention, component B is at least one of sodium chloride and sodium nitrate.

[0027] In this invention, the weight ratio of component A to component B in the leaching solution is 1 to 1.5:1, preferably 1.3 to 1.4:1;

[0028] The leaching solution may also contain water.

[0029] For example, in this invention, liquid form 1 (component A) and aqueous solution of component B can be mixed to form the leaching solution.

[0030] Preferably, the concentration of component B in the leaching solution is not particularly required, for example, it can be 0.5 to 1.5 mol / L.

[0031] In this invention, during the leaching stage, the pH of the leaching process is adjusted to 3-10.5 by alkaline solution, preferably 7-10, and more preferably 8.5-9.5. Studies have shown that under the preferred ratio, a better metal co-leaching effect can be obtained.

[0032] Preferably, the alkaline solution is an aqueous solution of an alkali metal hydroxide.

[0033] In this invention, the temperature during the leaching stage is above 40°C, preferably 50–100°C;

[0034] Preferably, the leaching time is more than 1 hour, further can be 2.5 to 20 hours, and even more can be 3 to 12 hours.

[0035] In this invention, the stripping agent in the stripping process is an acid solution, preferably an aqueous solution of an inorganic acid;

[0036] Preferably, the concentration of the solute in the acid solution is 0.5–5 M.

[0037] In this invention, the regenerated phase is used as component A and recycled back to the leaching process. For example, the regenerated phase can be used directly as the leaching solution, or the content of the components can be adjusted as needed before being used as the leaching solution in the next batch of waste cathode materials.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] This invention innovatively uses components A and B to leach waste cathode materials, and further combines this with the joint control of pH during the leaching stage to achieve synergy. This allows for excellent leaching of metal M without the need to transform the waste cathode materials. More importantly, the leaching components described in this invention have excellent recycling and regeneration capabilities.

[0040] In this invention, for waste cathode materials with low content and no transformation, a leaching rate of over 90% can still be obtained under relatively mild conditions, and the leaching solution in the process can be recycled and exhibits excellent cycle extraction stability.

[0041] The solution of Formula 1 in this invention has good regeneration and recycling performance. In addition, the leaching process requires low heat of reaction and low energy consumption.

[0042] This invention has higher chemical stability, is less volatile and less corrosive, and releases no toxic gases; Attached Figure Description

[0043] Figure 1 Here are SEM images of the waste ternary cathode material before and after leaching under different pH conditions in Example 4;

[0044] Figure 1 a is a scanning electron microscope image of the waste ternary cathode material before leaching. Figure 1 be are scanning electron microscope images of the dried waste ternary cathode material in Example 4 at pH conditions of 3, 5, 7 and 9, respectively.

[0045] Figure 2 The following are FTIR images of the Formula 1 solution before and after leaching under different pH conditions in Example 4;

[0046] Figure 3Raman Graphs of Formula 1 solution before and after leaching in Example 4;

[0047] Figure 4 The image shows the FTIR images of the solution in Example 4 before and after regeneration. Detailed Implementation Plan

[0048] In this invention, the active materials in the waste cathode materials are, for example, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, NCM ternary materials, etc. In the following examples, NCM ternary active materials are used as typical examples.

[0049] In this invention, the waste cathode material can be obtained by processing lithium-ion battery cathode sheets in a certain proportion. There are no special requirements for the content of active materials. In addition, the waste cathode material is also allowed to contain conductive agents, binders and other components permitted in conventional cathode materials.

[0050] In the following cases, unless otherwise stated, the following recycled lithium-ion cathode materials were used:

[0051] Take 0.1g of actual waste lithium-ion battery cathode material, put it into 20mL of concentrated sulfuric acid and concentrated nitric acid mixed solution, stir and heat at 80℃ for 1h, cool to room temperature to obtain the treated digestion solution, and measure the concentration of nickel ions, cobalt ions, manganese ions and lithium ions contained therein. The specific mass fraction is shown in Table 1.

[0052] Table 1. Mass fraction of nickel, cobalt, manganese, and lithium after digestion of waste ternary lithium-ion cathode materials.

[0053] Metal types Ni Co Mn Li Quality fraction (%) 23.44 5.17 7.60 4.05

[0054] A typical embodiment of the present invention includes the following steps:

[0055] Step 1: After pretreatment such as sieving and grinding, the waste NCM ternary lithium battery cathode material is obtained as the waste ternary lithium battery cathode material to be leached.

[0056] Step 2: The waste ternary lithium battery cathode material treated in Step 1 is added to the leaching system of component A-component B solution for reaction, and the concentrations of nickel ions, cobalt ions, manganese ions, and lithium ions in the aqueous phase are measured. The pH of the leaching stage is 3-10.5, preferably 7-10, more preferably 8.5-9.5. The leaching reaction temperature is 50-100℃, more preferably 60℃-90℃, even more preferably 84-86℃, and the reaction time is more than 1 hour, more preferably 2.5-20 hours, and even more preferably 3-12 hours.

[0057] Step 3: Add back-extraction agent to the organic phase obtained after leaching in Step 2 to react, separate the supernatant to obtain recyclable leaching agent, measure the concentration of nickel ions, cobalt ions, manganese ions and lithium ions in the aqueous phase (back-extraction solution), and calculate the total leaching rate.

[0058] Preferably, in step 1, the waste ternary lithium battery cathode material is passed through a 100-mesh sieve and ground for 30-60 minutes until it is fully ground and uniform.

[0059] Preferably, in step 2, component A is a solution based on the structure of formula 1, which can be obtained by reacting typical formula a-1 (in formula a, A- is Cl-) and formula b-1 (in formula b, B+ is Li+), and the molar ratio of formula a-1 to formula b-1 is 1:1, the reaction temperature is 60-80℃, the reaction time is 3-4h, and the stirring speed during the reaction is 200-500r / min.

[0060] In the following examples, unless otherwise stated, as typical examples, the leaching solvents are all mixtures of component A solution and component B (in the form of sodium nitrate) solution, the concentration of component B solution is 1M, and the weight ratio of component A to component B is 1.3 to 1.4:1.

[0061] There are no special requirements for the liquid-to-solid ratio in the leaching process. Considering cost, the liquid-to-solid ratio can be above 15 ml / g. In the following cases, unless otherwise stated, it refers to 18-20 ml / g.

[0062] Back-extraction can be implemented based on existing principles and methods. For example, back-extraction can be single-stage or multi-stage countercurrent back-extraction. There are no special requirements for the O / A volume ratio in the back-extraction process. For example, it can be 1:1 to 10. The following cases are typical examples, where the O / A volume ratio can be 1:4 to 6.

[0063] Example 1

[0064] Step 1: Grind the above-mentioned waste NCM ternary lithium battery cathode material through a 100-mesh sieve for 40-50 minutes to obtain the waste ternary lithium battery cathode material to be leached.

[0065] Step 2: The waste ternary lithium battery cathode material treated in Step 1 is added to the leaching solvent for leaching reaction. During the leaching reaction, the pH of the leaching reaction stage is controlled at 9 using 1M sodium hydroxide alkaline solution, the leaching temperature is 85℃ (leaching temperature T), and the time is 3.0h (leaching time t). The solution is then separated and further separated into oil and water to obtain the clear aqueous phase (leaching solution a) and the organic phase.

[0066] Step 3: Add a back-extraction agent (1.5M HCl) to the organic phase obtained after leaching in Step 2 to carry out a back-extraction reaction. Separate the supernatant (back-extraction solution, leachate b) to obtain recyclable leaching agent. The temperature of the back-extraction stage is 85℃, and the time is 1.5h. Leachate a and leachate b are combined, and the total leaching rate of metal elements is calculated. The results are shown in Table 2.

[0067] Table 2

[0068] Metal types Ni Co Mn Li Leaching rate (%) 100.00 93.98 99.96 100.00

[0069] Example 2

[0070] Compared to Example 1, the only difference is that the leaching temperature T in step 2 is changed to 60°C, 70°C, or 80°C. Other operations and parameters are the same as in Example 1.

[0071] The total leaching rates of Ni, Co, Mn, and Li were calculated according to the method in Example 1, and the results are shown in Table 3.

[0072] Table 3

[0073]

[0074] Example 3

[0075] Compared with Example 1, the only difference is that the temperature in step 2, the leaching stage, is 80°C, and the leaching time is changed to 1 h, 5.0 h, 7.5 h, and 10.0 h. The total leaching rate is calculated according to the scheme of Example 1, and the results are shown in Table 4.

[0076] Table 4

[0077]

[0078] Example 4

[0079] Compared to Example 1, the only difference is that the leaching stages are 3, 5, 7, 9, and 10 respectively; all other operations and parameters are the same as in Example 1. Leaching rate data for each condition are shown in Table 5.

[0080] Table 5

[0081]

[0082] The waste ternary cathode material before leaching and the dried waste ternary cathode material from Example 4 were compared. Both materials were subjected to electron microscopy (EMS) scanning, and a suitable scanning angle was determined. Specific EMS scanning results are detailed below. Figure 1As shown, (a) is a scanning electron microscope image of the waste ternary cathode material before leaching, and (b)-(e) are scanning electron microscope images of the dried waste ternary cathode material after being dried under pH conditions of 3, 5, 7 and 9 in Example 4 (i.e., Example 1).

[0083] As can be seen from the comparison of scanning electron microscope images, the particle size of the waste ternary cathode material after leaching is significantly smaller than that before leaching, indicating that the liquid of Formula 1 can effectively leach the waste ternary cathode material.

[0084] The liquids of Formula 1 extracted under different pH conditions in Example 4 were compared, and the specific results are as follows: Figure 2 As shown, (a) is the infrared spectrum of the original Formula 1 liquid, (b) is the infrared spectrum of the Formula 1 liquid after leaching at pH=3, (c) is the infrared spectrum of the Formula 1 liquid after leaching at pH=5, (d) is the infrared spectrum of the Formula 1 liquid after leaching at pH=7, and (e) is the infrared spectrum of the Formula 1 liquid after leaching at pH=9.

[0085] It can be seen that the liquid of Formula 1 before leaching was at 1742.78 cm⁻¹ -1 The corresponding functional group -COOH changed position after leaching, shifting to the right to 1732.09 cm. -1 This indicates that the -COOH functional group in the liquid of Formula 1 undergoes structural changes before and after leaching, which may be due to the leaching of valuable metals in the waste ternary cathode material by the liquid of Formula 1.

[0086] Raman spectroscopy was performed on the liquid of Formula 1 in Example 4, and the results are as follows: Figure 3 As shown, (a) is the Raman spectrum of Formula b-1, (b) is the Raman spectrum of Formula a-1, (c) is the Raman spectrum of the liquid of Formula 1, and (d) is the Raman spectrum of the leached liquid of Formula 1.

[0087] It can be seen that at 3620cm -1 Up to 3500cm -1 The peaks between the two peaks represent the OH functional groups of carboxyl molecules. The leached liquid of Formula 1 shifts towards higher wavelengths, indicating that the OH functional groups in the carboxyl molecules interact with the surrounding environment, changing the energy of the molecular vibration mode. This demonstrates that liquid Formula 1 leaches the waste ternary cathode material.

[0088] Example 5

[0089] Compared to Example 4, the only difference is that the organic phase obtained from the back-extraction is recycled back to step 2 to continue participating in the leaching process. The leaching conditions in the recycling stage are the same as those in the first leaching stage.

[0090] The loop process is as follows:

[0091] 1 st New Leaching Agent - Step 2 - Step 3 - 1 st Regenerated leachate;

[0092] 2 nd :1 st Regenerated Leaching Agent - Step 2 - Step 3 - 2 nd Regenerated leachate;

[0093] 3 rd :2 nd Regenerated Leaching Agent - Step 2 - Step 3 - 3 rd Regenerated leachate;

[0094] 4 th 3 rd Regenerated Leaching Agent - Step 2 - Step 3 - 4 th Regenerated leachate;

[0095] The leaching conditions for different steps, such as the content of components in the leaching solution (which can be supplemented by newly prepared component A and component B, ensuring that the internal proportions of each leaching stage are the same), temperature, pH, and time, are the same.

[0096] The cycling data under different extraction pH conditions were recorded, and the results are shown in Table 6 below:

[0097] Table 6

[0098] pH=5 Ni Co Mn Li <![CDATA[1 st ]]> 82.80％ 69.24％ 86.09％ 87.93％ <![CDATA[2 nd ]]> 68.98％ 66.92％ 63.09％ 87.41％ <![CDATA[3 rd ]]> 66.08％ 62.87％ 60.27％ 89.76％ pH=7 Ni Co Mn Li <![CDATA[1 st ]]> 100.00％ 90.59％ 99.31％ 93.27％ <![CDATA[2 nd ]]> 71.46％ 71.74％ 69.87％ 91.60％ <![CDATA[3 rd ]]> 77.89％ 54.96％ 76.94％ 69.72％ pH = 9 Ni Co Mn Li <![CDATA[1 st ]]> 100.00％ 93.98％ 99.96％ 100.00％ <![CDATA[2 nd ]]> 97.87％ 64.06％ 88.63％ 86.16％ <![CDATA[3 rd ]]> 89.73％ 62.45％ 48.68％ 67.73％ <![CDATA[4 th ]]> 67.18％ 31.47％ 0.20％ 59.72％

[0099] The solution of Formula 1 from Example 5, compared before and after multiple cycles at pH=9, is shown in the following figures. Figure 4 As shown, (a) is the infrared image before leaching in Example 5, (b) is the infrared image after one leaching cycle, (c) is the infrared image after two leaching cycles, (d) is the infrared image after three leaching cycles, and (e) is the infrared image after four leaching cycles.

[0100] It can be seen that before leaching, the functional group -COOH corresponds to 1742.78 cm⁻¹ and the functional group -CF₃ corresponds to 1137.71 cm⁻¹ in the solution of Formula 1. After 4 cycles, the position and intensity of the functional groups did not change significantly, indicating that the solution of Formula 1 can be regenerated after back-extraction and can be recycled multiple times.

[0101] Comparative Example 1

[0102] Compared with Example 1, the only difference is that the solution of Formula 1 in the leaching solvent is replaced with component 1 or component 2, while sodium nitrate and other components, as well as the operation and parameters, are the same as in Example 1.

[0103] Ingredient 1:

[0104] Ingredient 2:

[0105]

[0106]

[0107] Comparative Example 2

[0108] The only difference from Example 1 is that solute B is missing from the leaching solution; all other operations and parameters are the same as in Example 1. The total metal leaching rate is:

[0109] Metal types Ni Co Mn Li Leaching rate (%) 12.48 55.22 49.80 63.70

Claims

1. A method for leaching valuable metals from waste cathode materials, characterized in that, Waste cathode material containing metal element M is placed in a leaching solution containing components A and B for leaching treatment. Then, oil and water are separated to obtain aqueous phase A and oil phase. The oil phase is back-extracted to obtain a regenerated phase enriched with component A and back-extraction solution. Aqueous phase A and back-extraction solution are combined to obtain a leaching solution enriched with metal element M. Component A is a solution of Formula 1; Formula 1 Component B is at least one of sodium chloride and sodium nitrate; In the leachate solution, the weight ratio of component A to component B is 1~1.5:1; The M includes Li, and also includes at least one of Ni, Co, and Mn; During the leaching stage, the pH is adjusted to 7-10 using alkaline solution. The leaching temperature is 50~100℃; The leaching time is 2.5 to 20 hours.

2. The leaching method for valuable metals in waste cathode materials as described in claim 1, characterized in that, The waste cathode material is the material stripped from waste lithium-ion battery cathode sheets, and the active material in the waste cathode material is an oxidized lithium salt of at least one of nickel, cobalt, and manganese.

3. The leaching method for valuable metals in waste cathode materials as described in claim 2, characterized in that, The waste cathode material also includes at least one of the following: conductive agent, binder, electrolyte, and separator.

4. The leaching method for valuable metals in waste cathode materials as described in claim 2, characterized in that, The content of metal M in the waste cathode material is above 20 wt.%.

5. The leaching method for valuable metals in waste cathode materials as described in claim 4, characterized in that, The content of metal M in the waste cathode material is 30~50 wt.%.

6. The leaching method for valuable metals in waste cathode materials as described in claim 1, characterized in that, The waste cathode material is pre-ground and sieved; The grinding time is 30 min-60 min; The sieve used for sieving is a 100-mesh sieve.

7. The leaching method for valuable metals in waste cathode materials as described in claim 1, characterized in that, Component A is obtained by reacting compounds of formula a and formula b. Formula a Formula b; The A mentioned - For Cl - NO3 - Ac - At least one of the anions; The B mentioned above + For Li + Na + K + At least one of the cations.

8. The leaching method for valuable metals in waste cathode materials as described in claim 7, characterized in that, The molar ratio of formula a and formula b is 1:0.95~1.05; The solvent used in the reaction stage is an aqueous solvent; The temperature during the reaction stage is 50~90℃; The reaction time is 3-4 hours.

9. The leaching method for valuable metals in waste cathode materials as described in claim 1, characterized in that, In the leachate solution, the weight ratio of component A to component B is 1.3~1.4:

1.

10. The leaching method for valuable metals in waste cathode materials as described in claim 1, characterized in that, During the leaching stage, the pH is adjusted to 8.5-9.5 using alkaline solution.

11. The leaching method for valuable metals in waste cathode materials as described in claim 1, characterized in that, The alkaline solution is an aqueous solution of an alkali metal hydroxide.

12. The leaching method for valuable metals in waste cathode materials as described in claim 1, characterized in that, The leaching time is 3 to 12 hours.

13. The leaching method for valuable metals in waste cathode materials as described in claim 1, characterized in that, The stripping agent in the stripping process is acid.

14. The leaching method for valuable metals in waste cathode materials as described in claim 13, characterized in that, The stripping agent in the stripping process is an aqueous solution of an inorganic acid.

15. The leaching method for valuable metals in waste cathode materials as described in claim 13, characterized in that, The concentration of the solute in the acid solution is 0.5~5M.

16. The leaching method for valuable metals in waste cathode materials as described in claim 1, characterized in that, The regenerated phase is used as component A and recycled back to the leaching process.

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