A method for recycling waste battery powder

Abstract

This disclosure provides a method for recycling waste battery powder, the recycling method comprising the following steps: (1) roasting the waste battery powder and then extracting lithium by water leaching to obtain a lithium-rich solution and lithium extraction slag; (2) screening the lithium extraction slag to obtain a metal mixture and flotation material, mixing the flotation material, flake graphite and solvent, adjusting the mass concentration and adding a collector and a frother to obtain a slurry; (3) performing flotation treatment on the slurry, screening to obtain flotation foam and cathode material, screening the flotation foam to obtain high-purity graphite and recovering the flake graphite; (4) repairing the high-purity graphite to obtain battery-grade graphite, and performing wet recycling of the cathode material to obtain battery-grade metal material. This disclosure uses flake graphite as a carrier, realizing rapid and effective separation of graphite and cathode powder, and the flake graphite can also be recovered after recycling, realizing the recycling and reuse of the carrier.

Description

Technical Field

[0001] This disclosure belongs to the field of resource recycling technology and relates to a method for recycling waste battery powder. Background Technology

[0002] Thanks to the government's strong support for the new energy industry, the power battery industry has developed rapidly. According to statistics, in the past five years, the cumulative production of power batteries has reached 1005 GWh, with an average annual growth of 66.7%, while the cumulative amount of retired power batteries has reached 1.007 million tons, with an average annual growth of 73.5%.

[0003] In 2023, 481,900 tons of power batteries are expected to be retired, the vast majority of which are used ternary lithium batteries. This figure is projected to reach 1,370,100 tons by 2027, with a market value exceeding 100 billion yuan. Retired power batteries have both economic and environmental implications; improper disposal will pollute the atmosphere, soil, and water.

[0004] CN112635867A discloses a method for recycling graphite materials from waste lithium batteries. The method uses a combination of physical methods, including scrubbing, magnetic separation, gravity separation, pyrolysis, and flotation, to recycle graphite materials. By stirring and scrubbing the mixed powder of positive and negative electrode materials obtained from the crushing and sorting of waste power lithium batteries, the adhesion between the negative electrode material and other substances is reduced, which is beneficial to improving the subsequent high-gradient strong magnetic separation effect.

[0005] CN115872400A discloses a method for graphite recycling based on leaching residue from waste lithium batteries, comprising the following steps: pre-treating lithium batteries to obtain electrolyte; subjecting the electrolyte to a first hydrolysis reaction, mixing the graphite-containing leaching residue with the solution after the first hydrolysis reaction, and then performing impurity removal treatment to obtain a mixed slurry; subjecting the mixed slurry to a second hydrolysis reaction, and subjecting the mixed slurry after the second hydrolysis reaction to flotation treatment to obtain flotation products and a first residual solution; and post-treating the flotation products to obtain graphite.

[0006] The positive and negative electrode materials in ternary lithium batteries are classified as fine particles in mineral processing. The flotation method described above is difficult to achieve satisfactory results in recovering fine and ultrafine minerals. Summary of the Invention

[0007] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0008] The purpose of this disclosure is to provide a method for recycling waste battery powder. Based on the difference in specific gravity and wettability between graphite and cathode powder, this disclosure uses flake graphite as a carrier and uses a conventional flotation machine for flotation, which achieves rapid and effective separation of graphite and cathode powder. After recycling, the flake graphite can also be recovered, realizing the recycling and reuse of the carrier.

[0009] To achieve this objective, the present disclosure adopts the following technical solution:

[0010] In a first aspect, this disclosure provides a method for recycling waste battery powder, the recycling method comprising the following steps:

[0011] (1) After roasting the waste battery powder, lithium is extracted by water leaching to obtain a lithium-rich solution and lithium extraction residue.

[0012] (2) The lithium extraction slag is screened to obtain a metal mixture and flotation material respectively. The flotation material, flake graphite and solvent are mixed, and after adjusting the mass concentration, a collector and a foaming agent are added to obtain a slurry.

[0013] (3) The slurry is subjected to flotation treatment, and flotation foam and positive electrode material are obtained by screening. The flotation foam is screened to obtain high-purity graphite and recover flake graphite.

[0014] (4) The high-purity graphite is repaired to obtain battery-grade graphite, and the cathode material is wet-processed to obtain battery-grade metal salt.

[0015] This disclosure utilizes carrier flotation, employing flake graphite as a carrier to float graphite. For the recovery of fine particles, it can effectively improve the grade and recovery rate of graphite. After recovery, the carrier particles flake graphite can be effectively recovered by utilizing the particle size difference between battery materials and flake graphite, realizing the reuse of the carrier. During the recovery process, a conventional flotation machine is used for flotation, which can achieve rapid and effective separation of graphite and cathode powder.

[0016] In one embodiment, the calcination temperature in step (1) is 600-700°C, for example: 600°C, 620°C, 650°C, 680°C or 700°C.

[0017] In one embodiment, the calcination treatment time is 2 to 3 hours, for example: 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, or 3 hours.

[0018] In the calcination process described in this disclosure, the carbon originally present in the battery powder is used as a reducing agent to achieve carbothermic reduction of lithium, while simultaneously achieving deep removal of electrolyte and binder from the battery powder.

[0019] In one embodiment, the water immersion lithium extraction in step (1) includes water immersion and pressurized water immersion.

[0020] In one embodiment, the solid-liquid ratio of the water-immersion lithium extraction is 1:(8-10), for example: 1:8, 1:8.5, 1:9, 1:9.5 or 1:10, etc.

[0021] This disclosure employs a stepwise water leaching method for lithium extraction, controlling the solid-liquid ratio of the water leaching process to be 1:(8-10), which can increase the lithium leaching rate to over 85%.

[0022] In one embodiment, the size of the sieve in step (2) is 0.1 to 0.3 mm, for example: 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm or 0.3 mm, etc.

[0023] In one embodiment, the metal mixture comprises a mixture of copper foil and aluminum foil.

[0024] This disclosure uses sieving to control the size of the sieve to 0.1-0.3 mm, which can separate copper-aluminum foil and positive and negative electrode materials. The mixture of copper and aluminum foil is retained on the upper part of the screen during the sieving process (i.e., the oversize product), while the positive and negative electrode materials fall to the bottom of the screen (i.e., the undersize product).

[0025] In one embodiment, the mass of the flake graphite in step (2) is 10% to 60% of the mass of the flotation material, for example: 10%, 20%, 30%, 40% or 60%, etc., and can be selected as 20% to 40%.

[0026] In the waste battery powder recycling method disclosed herein, the amount of flake graphite added affects the recycling effect. Controlling the mass of flake graphite at 20-40% of the flotation material mass results in a better recycling effect. If the amount of flake graphite added is too high, the graphite recovery rate will increase, but the grade will decrease slightly, and the carrier reuse rate will decrease. If the amount of flake graphite added is too low, both the graphite recovery rate and grade will decrease.

[0027] In one embodiment, the size of the flake graphite is 200 to 400 mesh, for example: 200 mesh, 250 mesh, 300 mesh, 350 mesh or 400 mesh, etc.

[0028] This disclosure uses 200-400 mesh flake graphite as a carrier for flotation. The flake graphite can adsorb fine graphite particles, thereby improving the grade and recovery rate of graphite.

[0029] In one embodiment, the solvent includes water.

[0030] In one embodiment, the mass concentration in step (2) is 5% to 15%, for example: 5%, 8%, 10%, 12% or 15%, etc.

[0031] In the waste battery powder recycling method described in this disclosure, the mass concentration after adding flake graphite and solvent in step (2) will affect the recycling effect. The recycling effect is better when the mass concentration is controlled at 5-15%. If the mass concentration is too high, the recovery rate of graphite will increase, the grade will decrease, and the reuse rate of the carrier will decrease. If the mass concentration is too low, both the recovery rate and grade of graphite will decrease.

[0032] In one embodiment, the collector in step (2) comprises diesel fuel.

[0033] In one embodiment, the collector is added at a rate of 200-300g (e.g., 200g, 220g, 250g, 280g, or 300g, etc.) per ton of flotation material.

[0034] In one embodiment, the foaming agent comprises pine oil.

[0035] In one embodiment, the amount of frother added is 150-250g (e.g., 150g, 180g, 200g, 220g or 250g, etc.) per ton of flotation material.

[0036] This disclosure enables the flotation of materials and impurities by adding appropriate amounts of collectors and frothers.

[0037] In one embodiment, the high-purity graphite in step (3) has a purity >98%.

[0038] In one embodiment, the recovery rate of the high-purity graphite is >80%.

[0039] In one embodiment, the reusability of the flake graphite in step (3) is >98%.

[0040] In one embodiment, the wet recovery in step (4) includes acid leaching, impurity removal and extraction.

[0041] Compared with the prior art, this disclosure has the following beneficial effects:

[0042] (1) Based on the difference in specific gravity and wettability between graphite and cathode powder, this disclosure uses flake graphite as a carrier and uses a conventional flotation machine for flotation, which realizes the rapid and effective separation of graphite and cathode powder. After recycling, the flake graphite can also be recovered, realizing the recycling and reuse of the carrier.

[0043] (2) The recycling method described in this disclosure can achieve a graphite recovery rate of over 80% and a graphite grade of over 98%, which can be directly used in battery materials. The reuse rate of the carrier flake graphite can also reach over 98%, thus realizing the recycling and reuse of the carrier.

[0044] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0045] The accompanying drawings are used to provide a further understanding of the technical solutions in this paper and form part of the specification. They are used together with the embodiments of this application to explain the technical solutions in this paper and do not constitute a limitation on the technical solutions in this paper.

[0046] Figure 1 This is a process flow diagram of the recycling method according to an embodiment of this disclosure. Detailed Implementation

[0047] The technical solutions of this disclosure will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of this disclosure and should not be construed as specific limitations thereof.

[0048] The composition of the waste ternary lithium battery powder used in the embodiments and comparative examples of this disclosure is as follows:

[0049] The composition of the cathode material is as follows: carbon 45.64%, lithium 3.46%, nickel 21.53%, cobalt 2.76%, manganese 3.22%, copper foil 1.89%, and aluminum foil 0.19%. The specific gravity of the anode material is 2.28, and the D90 is 14.85μm. The specific gravity of the cathode material is 4.70, and the D90 is 5.27μm.

[0050] Example 1

[0051] This embodiment provides a method for recycling waste battery powder, and the process flow diagram of the recycling method is as follows: Figure 1 As shown, the method specifically includes the following steps:

[0052] (1) Using the carbon source in the battery powder itself, calcining at 650℃ in an inert protective atmosphere for 2.5h to achieve carbothermic reduction of Li, while achieving deep removal of electrolyte and binder in the battery powder. Lithium extraction is carried out stepwise by water immersion + pressurized water immersion with a solid-liquid ratio of 1:9 and a leaching rate of 85.61%, resulting in a lithium-rich solution and lithium extraction residue.

[0053] (2) The lithium extraction slag is screened with a screen size of 0.2 mm. The material on the screen is a mixture of copper and aluminum foil, and the material under the screen is flotation material. 30% by mass of 400-mesh flake graphite is added to the flotation material to adjust the mass concentration to 5%. 300 g / t of diesel oil collector and 200 g / t of pine oil foaming agent are added and the mixture is stirred to obtain a slurry.

[0054] (3) The slurry is subjected to flotation treatment, and flotation foam and positive electrode material (underflow) are obtained by screening. The flotation foam is screened, and high-purity graphite is obtained by utilizing the particle size difference between flake graphite and battery-grade material, and the carrier particles (flake graphite) are recovered. The carrier reuse rate is 98.13%, the graphite grade is 98.22%, and the recovery rate is 82.89%.

[0055] (4) The high-purity graphite is repaired to obtain battery-grade graphite. The sieved flotation underflow (positive electrode material) is subjected to acid leaching, impurity removal and extraction processes to obtain nickel sulfate, cobalt sulfate and manganese sulfate products.

[0056] Example 2

[0057] This embodiment provides a method for recycling waste battery powder, and the process flow diagram of the recycling method is as follows: Figure 1 As shown, the method specifically includes the following steps:

[0058] (1) Using the carbon source in the battery powder itself, calcining at 600℃ in an inert protective atmosphere for 3h to achieve carbothermic reduction of Li, while achieving deep removal of electrolyte and binder in the battery powder. Lithium extraction is carried out stepwise by water immersion + pressurized water immersion with a solid-liquid ratio of 1:10 and a leaching rate of 85.86%, resulting in a lithium-rich solution and lithium extraction residue.

[0059] (2) The lithium extraction slag is screened with a screen size of 0.1 mm. The material on the screen is a mixture of copper and aluminum foil, and the material under the screen is flotation material. 60% by mass of 325-mesh flake graphite is added to the flotation material to adjust the mass concentration to 5%. 300 g / t of diesel oil collector and 200 g / t of pine oil foaming agent are added and the mixture is stirred to obtain a slurry.

[0060] (3) The slurry is subjected to flotation treatment, and flotation foam and positive electrode material (underflow) are obtained by screening. The flotation foam is screened, and high-purity graphite is obtained by utilizing the particle size difference between flake graphite and battery-grade material, and the carrier particles (flake graphite) are recovered. The carrier reuse rate is 98.85%, the graphite grade is 98.32%, and the recovery rate is 80.78%.

[0061] (4) The high-purity graphite is repaired to obtain battery-grade graphite. The sieved flotation underflow (positive electrode material) is subjected to acid leaching, impurity removal and extraction processes to obtain nickel sulfate, cobalt sulfate and manganese sulfate products.

[0062] Example 3

[0063] This embodiment provides a method for recycling waste battery powder, and the process flow diagram of the recycling method is as follows: Figure 1 As shown, the method specifically includes the following steps:

[0064] (1) Using the carbon source in the battery powder itself, calcining at 700℃ in an inert protective atmosphere for 2h to achieve carbothermic reduction of Li, while achieving deep removal of electrolyte and binder in the battery powder. Lithium extraction is carried out stepwise by water immersion + pressurized water immersion with a solid-liquid ratio of 1:8 and a leaching rate of 85.32%, resulting in a lithium-rich solution and lithium extraction residue.

[0065] (2) The lithium extraction slag is screened with a screen size of 0.1 mm. The material on the screen is a mixture of copper and aluminum foil, and the material under the screen is flotation material. 10% by mass of 200-mesh flake graphite is added to the flotation material to adjust the mass concentration to 15%. 300 g / t of collector diesel oil and 200 g / t of foaming agent pine oil are added and the mixture is stirred to obtain a slurry.

[0066] (3) The slurry is subjected to flotation treatment, and flotation foam and positive electrode material (underflow) are obtained by screening. The flotation foam is screened, and high-purity graphite is obtained by utilizing the particle size difference between flake graphite and battery-grade material, and the carrier particles (flake graphite) are recovered. The carrier reuse rate is 99.26%, the graphite grade is 98.11%, and the recovery rate is 83.52%.

[0067] (4) The high-purity graphite is repaired to obtain battery-grade graphite. The sieved flotation underflow (positive electrode material) is subjected to acid leaching, impurity removal and extraction processes to obtain nickel sulfate, cobalt sulfate and manganese sulfate products.

[0068] Example 4

[0069] The only difference between this embodiment and Embodiment 1 is that the mass of flake graphite is 10% of the mass of the flotation material; all other conditions and parameters are exactly the same as in Embodiment 1.

[0070] Example 5

[0071] The only difference between this embodiment and Embodiment 1 is that the mass of flake graphite is 60% of the mass of the flotation material; all other conditions and parameters are exactly the same as in Embodiment 1.

[0072] Example 6

[0073] The only difference between this embodiment and embodiment 1 is that the mass concentration in step (2) is 3%, while the other conditions and parameters are exactly the same as in embodiment 1.

[0074] Example 7

[0075] The only difference between this embodiment and embodiment 1 is that the mass concentration in step (2) is 20%, while the other conditions and parameters are exactly the same as in embodiment 1.

[0076] Comparative Example 1

[0077] The only difference between this comparative example and Example 1 is that flake graphite is not added; all other conditions and parameters are exactly the same as in Example 1.

[0078] Comparative Example 2

[0079] The only difference between this comparative example and Example 1 is that flake graphite is not added, and the flotation equipment uses a flotation column that can generate micron-sized bubbles for flotation. All other conditions and parameters are exactly the same as in Example 1.

[0080] Comparative Example 3

[0081] The only difference between this comparative example and Example 1 is that the flake graphite is replaced with a flocculant to flocculate the fine particles into clusters for flotation. All other conditions and parameters are exactly the same as in Example 1.

[0082] Performance testing:

[0083] The recovery rates, grades, and carrier recovery rates of graphite obtained by the recovery methods described in the examples and comparative examples are shown in Table 1.

[0084] Table 1

[0085] Graphite recovery rate (%) Graphite grade (%) Carrier reuse rate (%) Example 1 82.89 98.32 98.85 Example 2 80.78 98.22 98.13 Example 3 83.52 98.11 99.26 Example 4 80.21 98.02 99.02 Example 5 83.01 98.17 98.30 Example 6 81.46 98.25 98.75 Example 7 83.21 98.03 98.01 Comparative Example 1 73.08 96.35 / Comparative Example 2 78.29 97.13 / Comparative Example 3 79.93 96.88 /

[0086] As can be seen from Table 1, as obtained from Examples 1-3, the recovery rate of graphite obtained by the recycling method described in this disclosure can reach more than 80%, and the grade of graphite can reach more than 98%, which can be directly used in battery materials. The reuse rate of carrier flake graphite can also reach more than 98%, realizing the recycling and reuse of the carrier.

[0087] A comparison of Examples 1 and 4-5 shows that in the waste battery powder recycling method described in this disclosure, the amount of flake graphite added affects the recycling effect. Controlling the mass of flake graphite at 20-40% of the flotation material mass results in a better recycling effect. If the amount of flake graphite added is too high, the graphite recovery rate will increase, but the grade will decrease slightly, and the carrier reuse rate will decrease. If the amount of flake graphite added is too low, both the graphite recovery rate and grade will decrease.

[0088] Comparing Examples 1 and 6-7, it can be seen that in the waste battery powder recycling method of this disclosure, the mass concentration after adding flake graphite and solvent in step (2) will affect the recycling effect. The recycling effect is better when the mass concentration is controlled at 5-15%. If the mass concentration is too high, the graphite recovery rate will increase, the grade will decrease, and the carrier reuse rate will decrease. If the mass concentration is too low, both the graphite recovery rate and grade will decrease.

[0089] As can be seen from the comparison of Example 1 and Comparative Examples 1-3, the present disclosure uses carrier flotation, using flake graphite as a carrier to float graphite. For the recovery of fine particles, it can effectively improve the grade and recovery rate of graphite. After recovery, the carrier particles flake graphite can be effectively recovered by utilizing the particle size difference between battery materials and flake graphite, realizing the reuse of the carrier. In the recovery process, a conventional flotation machine is used for flotation, which can achieve rapid and effective separation of graphite and cathode powder.

Claims

1. A method for recycling waste battery powder, the recycling method comprising the following steps: (1) After roasting the waste battery powder, lithium is extracted by water leaching to obtain a lithium-rich solution and lithium extraction residue. (2) The lithium extraction slag is screened to obtain a metal mixture and flotation material respectively. The flotation material, flake graphite and solvent are mixed, and after adjusting the mass concentration, a collector and a foaming agent are added to obtain a slurry. (3) The slurry is subjected to flotation treatment, and the flotation foam and positive electrode material are obtained by screening. The flotation foam is screened to obtain high-purity graphite and recover flake graphite. (4) The high-purity graphite is repaired to obtain battery-grade graphite, and the cathode material is wet-processed to obtain battery-grade metal salt. The mass concentration in step (2) is 5-15%.

2. The recycling method as described in claim 1, wherein, The roasting temperature in step (1) is 600-700℃.

3. The recycling method as described in claim 1, wherein, The roasting process takes 2 to 3 hours.

4. The recycling method as described in claim 1, wherein, The water immersion lithium extraction in step (1) includes water immersion and pressurized water immersion.

5. The recycling method as described in claim 1, wherein, The solid-liquid ratio of the lithium extraction by water leaching is 1:(8-10).

6. The recycling method as described in claim 1, wherein, The size of the sieve in step (2) is 0.1 to 0.3 mm.

7. The recycling method as described in claim 1, wherein, The metal mixture includes a mixture of copper foil and aluminum foil.

8. The recycling method as described in claim 1, wherein, The mass of the flake graphite in step (2) is 10-60% of the mass of the flotation material.

9. The recycling method as described in claim 1, wherein, The mass of the flake graphite in step (2) is 20-40% of the mass of the flotation material.

10. The recycling method as described in claim 1, wherein, The size of the flake graphite is 200-400 mesh.

11. The recycling method as described in claim 1, wherein, The solvent includes water.

12. The recycling method as described in claim 1, wherein, The collector in step (2) includes diesel fuel.

13. The recycling method as described in claim 1, wherein, The collector is added at a rate of 200-300g per ton of flotation material.

14. The recycling method as described in claim 1, wherein, The foaming agent includes pine oil.

15. The recycling method as described in claim 1, wherein, The amount of frother added is 150-250g per ton of flotation material.

16. The recycling method as described in claim 1, wherein, The grade of the high-purity graphite in step (3) is >98%.

17. The recycling method as described in claim 1, wherein, The recovery rate of the high-purity graphite is >80%.

18. The recycling method as described in claim 1, wherein, The reusability of the flake graphite in step (3) is >98%.

19. The recycling method as described in claim 1, wherein, The wet recovery process described in step (4) includes acid leaching, impurity removal, and extraction.

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