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CN-118324135-B - Method for recycling graphite from waste lithium ion battery carbon slag and regenerated graphite

CN118324135BCN 118324135 BCN118324135 BCN 118324135BCN-118324135-B

Abstract

The invention discloses a method for recycling graphite from waste lithium ion battery carbon residues and regenerated graphite, and relates to the technical field of lithium battery recycling. The method comprises the steps of carrying out heat treatment on carbon residues after acid leaching of waste lithium ion batteries, dissociating inorganic impurities and organic impurities in the carbon residues into substances with smaller particles in the heat treatment process, facilitating removal in subsequent procedures, carrying out scattering treatment on pyrolytic carbon residues obtained by the heat treatment, screening to obtain small-particle materials, removing redundant large-particle impurities, grinding and classifying to obtain graphite coarse powder with the particle size Dv50 of 12-15 mu m, wherein ash impurities are mainly concentrated in fine powder, and ash can be effectively removed after classification. The heat treatment-scattering, screening-grinding and grading linkage technical means provided by the invention does not need to additionally add chemical reagents, only relies on a plurality of physical technical means, not only can achieve the effect of removing ash impurities, but also can effectively remove amorphous carbon, and the method is simple and feasible, safe and environment-friendly.

Inventors

  • FAN XIA
  • RUAN DINGSHAN
  • ZHOU YOU
  • LI QIANG
  • LI CHANGDONG
  • LIN MINGJIAN

Assignees

  • 湖南邦普循环科技有限公司
  • 广东邦普循环科技有限公司

Dates

Publication Date
20260505
Application Date
20240415

Claims (18)

  1. 1. A method for recovering graphite from waste lithium ion battery carbon slag, comprising the steps of: Carrying out heat treatment on carbon residues obtained after acid leaching of waste lithium ion batteries to obtain pyrolytic carbon residues, carrying out scattering treatment on the pyrolytic carbon residues in a high-speed mixing mode, placing the pyrolytic carbon residues in a vibrating screen with the mesh number of 150-300 meshes for sieving treatment, removing excessive large particulate impurities by sieving, and grinding and grading the sieved carbon residues to obtain graphite coarse powder with the particle size Dv50 of 12-15 mu m; the heat treatment mode is at least one selected from electric furnace heat treatment and microwave heat treatment, wherein the heat treatment temperature is controlled to be 450-1000 ℃ in the electric furnace heat treatment process, and the microwave power is controlled to be 400-1500W in the microwave heat treatment process; the grinding means is at least one selected from mechanical impact grinding, air flow grinding and ball milling, and the particle diameter Dv50 of the ground material is controlled to be 11-15 mu m, wherein the classification is that the material is sequentially processed by a classifier and a cyclone separator; When the graphite coarse powder is prepared by adopting a mechanical impact grinding method, controlling the main machine frequency of the mechanical impact grinding to be 20Hz-50Hz; when the graphite coarse powder is prepared by adopting an air flow grinding method, the pressure of grinding gas is controlled to be 0.15MPa-0.50MPa, and the frequency of a main machine is controlled to be 20Hz-50Hz; when the graphite coarse powder is prepared by adopting a ball milling method, the ball-material ratio is controlled to be (3-5): 1, and the ball milling time is 3-10 min.
  2. 2. The method according to claim 1, wherein the mixing speed is controlled to be 500rpm-2000rpm and the stirring time is controlled to be 3min-30min during the break-up treatment.
  3. 3. The method according to claim 1, wherein the frequency of the classifier is 25Hz-50Hz, the wind pressure of the cyclone separator is 5000Pa-7500Pa, and the wind volume of the cyclone separator is 250m 3 /min-400m 3 /min.
  4. 4. The method according to claim 1, wherein the heat treatment is performed under an inert atmosphere.
  5. 5. The method according to claim 1, wherein the heat treatment time is 2 to 5 hours during the electric furnace heat treatment.
  6. 6. The method of claim 1, wherein the carbon residue is dried prior to microwave heat treatment.
  7. 7. The method according to claim 6, wherein the time of the microwave treatment is controlled to be 5min to 30min during the microwave heat treatment.
  8. 8. The method according to claim 6, wherein the drying temperature is controlled to be 80 ℃ to 200 ℃ and the drying time is controlled to be 10h to 30h during the drying treatment.
  9. 9. The method of claim 1, wherein the graphite coarse powder is mixed with a carbon source and the resulting mixture is graphitized.
  10. 10. The method of claim 9, wherein the carbon source is selected from at least one of pitch, petroleum coke, and needle coke.
  11. 11. The method according to claim 9, wherein the mass ratio of the total amount of the carbon source to the graphite coarse powder is (2-10): 100.
  12. 12. The method according to claim 11, wherein the mass ratio of the total amount of the carbon source to the graphite coarse powder is (3-5): 100.
  13. 13. The method of claim 9, wherein the carbon source comprises at least pitch; when the carbon source is a mixture of asphalt and petroleum coke, controlling the mass ratio of the asphalt to the petroleum coke to be 1 (0.1-1.0); When the carbon source is a mixture of pitch and needle coke, controlling the mass ratio of pitch to needle coke to be 1 (0.1-1.0); when the carbon source is a mixture of asphalt, petroleum coke and needle coke, the mass ratio of the asphalt to the total amount of the petroleum coke and the needle coke is controlled to be 1 (0.1-1.0).
  14. 14. The method according to claim 9, wherein the carbon source has a particle size Dv50 of 3 μm to 6 μm.
  15. 15. The method of claim 14, wherein the carbon source has a particle size Dv50 of 3 μιη to 4 μιη.
  16. 16. The method according to claim 9, wherein the graphite coarse powder is mixed with the carbon source at a high speed, and the stirring speed is controlled to be 500rpm-2000rpm, and the mixing time is 5min-30min.
  17. 17. The method according to claim 9, wherein the graphitization treatment is performed at a temperature of 2400 ℃ to 3100 ℃ and for a holding time of 1h to 72h.
  18. 18. The method of claim 17, wherein the graphitization treatment is performed at a temperature of 2500 ℃ to 2800 ℃ for a period of 2 hours to 4 hours.

Description

Method for recycling graphite from waste lithium ion battery carbon slag and regenerated graphite Technical Field The invention relates to the technical field of lithium battery recovery, in particular to a method for recovering graphite from waste lithium ion battery carbon residues and regenerated graphite. Background With the proliferation of mobile electronics and Electric Vehicles (EVs), there is an increasing demand for secondary energy storage, mainly Lithium Ion Batteries (LIBs). As LIBs consumption increases, the demand for battery materials and production increases, but natural resources are limited. The recovery of LIBs requires the development of a sustainable closed-loop route, particularly with respect to reducing environmental risks and increasing profits for the enterprise. However, the treatment focus of enterprises at present is still to recover high-value metals, and no targeted effective recovery means exists for the waste carbon residue which is mainly carbon and contains a small amount of residual cathode materials and a small amount of electrolyte after the high-value metals are recovered by adopting wet acid leaching, extraction and other means. If the waste carbon residue is not treated and recycled, the waste of resources is caused, and in addition, the unreasonable treatment of the waste carbon residue can have serious influence on the environment. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a method for recycling graphite from waste lithium ion battery carbon residues and regenerated graphite, and aims to recycle high-purity graphite from waste lithium ion battery carbon residues, so that the electrochemical performance of a graphite finished product is effectively improved. The invention is realized in the following way: In a first aspect, the invention provides a method for recovering graphite from waste lithium ion battery carbon residue, comprising: and carrying out heat treatment on carbon residues obtained after acid leaching of the waste lithium ion batteries to obtain pyrolytic carbon residues, carrying out scattering treatment on the pyrolytic carbon residues, screening small-particle materials with the particle size smaller than 150-300 meshes, and grinding and grading the small-particle materials to obtain graphite coarse powder with the particle size Dv50 of 12-15 mu m. In an alternative embodiment, the process of obtaining the small-particle material comprises the steps of carrying out scattering treatment on pyrolytic carbon residues in a high-speed mixing mode, and screening out the small-particle material by placing the scattered material in a vibrating screen with the mesh number of 150-300 meshes; Preferably, during the break-up treatment, the mixing speed is controlled to be 500rpm-2000rpm, and the stirring time is 3min-30min. In an alternative embodiment, the means of milling is selected from at least one of mechanical impact milling, air flow milling and ball milling, and the particle size Dv50 of the milled material is controlled to be 11 μm to 15 μm; classification is to treat the materials sequentially through a classifier and a cyclone separator. In an alternative embodiment, when graphite meal is prepared by mechanical impact milling or air flow milling, the apparatus employed is equipped with a classifier and cyclone; preferably, when the graphite coarse powder is prepared by adopting a mechanical impact grinding method, controlling the frequency of a main machine of the mechanical impact grinding to be 20Hz-50Hz, the frequency of a classifier to be 25Hz-50Hz, the wind pressure of a cyclone separator to be 5000Pa-7500Pa, and the wind quantity of the cyclone separator to be 250m 3/min-400m3/min; Preferably, when graphite coarse powder is prepared by adopting an air flow grinding method, the pressure of grinding air is controlled to be 0.15MPa-0.50MPa, the frequency of a main machine is controlled to be 20Hz-50Hz, the frequency of a classifier is controlled to be 25Hz-50Hz, the air pressure of a cyclone separator is controlled to be 5000Pa-7500Pa, and the air quantity of the cyclone separator is controlled to be 250m 3/min-400m3/min. In an alternative embodiment, when graphite coarse powder is prepared by a ball milling method, the graphite coarse powder is sequentially processed by an air classifier and a cyclone separator after the ball milling process; Preferably, in the ball milling treatment process, the ball-material ratio is controlled to be (3-5): 1, and the ball milling time is 3-10 min; preferably, after ball milling treatment, the frequency of the air classifier is controlled to be 25Hz-50Hz, the air pressure of the cyclone separator is controlled to be 5000Pa-7500Pa, and the air quantity of the cyclone separator is controlled to be 250m 3/min-400m3/min. In an alternative embodiment, the heat treatment mode is at least one selected from electric furnace heat treatment and microwave