阅读说明：本技术 一种废旧锂离子电池正极材料回收方法 (Method for recycling anode material of waste lithium ion battery ) 是由 蔡伟平 范鑫铭 陈志勇 王潇晗 骆伟光 于 2020-12-09 设计创作，主要内容包括：本发明属于锂离子电池回收技术领域,公开了一种废旧锂离子电池正极材料回收方法,包括以下步骤：S1、将废旧锂离子电池进行预处理得到正极材料；S2、将正极材料与石墨粉混合后,在惰性气氛中进行加热还原反应,得到固体产物；S3、将固体产物进行筛分,分别得到炉渣粉末和金属合金；S4、将炉渣粉末加酸溶解,过滤得到锂盐溶液；S5、在锂盐溶液中加入碱试剂调节pH7-11,然后加入碳酸盐进行沉淀,得到碳酸锂沉淀。本发明实现了镍钴锰等金属与锂的高效分离,其中镍钴锰等金属的回收率大于99％,锂金属回收率大于95％,该回收方法具有工艺简单、回收效率高、适合规模化应用等优点。(The invention belongs to the technical field of lithium ion battery recovery, and discloses a method for recovering a waste lithium ion battery anode material, which comprises the following steps: s1, pretreating the waste lithium ion battery to obtain a positive electrode material; s2, mixing the anode material with graphite powder, and carrying out heating reduction reaction in an inert atmosphere to obtain a solid product; s3, screening the solid product to respectively obtain slag powder and metal alloy; s4, adding acid to the slag powder for dissolving, and filtering to obtain a lithium salt solution; s5, adding an alkali reagent into the lithium salt solution to adjust the pH value to 7-11, and then adding carbonate to precipitate to obtain lithium carbonate precipitate. The method realizes the high-efficiency separation of metals such as nickel, cobalt and manganese and lithium, wherein the recovery rate of the metals such as nickel, cobalt and manganese is more than 99%, and the recovery rate of the lithium metal is more than 95%.)

1. A method for recovering a waste lithium ion battery anode material is characterized by comprising the following steps:

s1, pretreating the waste lithium ion battery to obtain a positive electrode material;

s2, mixing the anode material with graphite powder, and carrying out heating reduction reaction in an inert atmosphere to obtain a solid product;

s3, screening the solid product to respectively obtain slag powder and metal alloy;

s4, adding acid to the slag powder for dissolving, and filtering to obtain a lithium salt solution;

s5, adding an alkali reagent into the lithium salt solution to adjust the pH value to 7-11, and then adding carbonate to precipitate to obtain lithium carbonate precipitate.

2. The method for recycling the positive electrode material of the waste lithium battery as claimed in claim 1, wherein: the pretreatment in S1 includes heat treatment of the positive electrode material; the heat treatment is heating for 2-4h at the temperature of 300-500 ℃ in an inert atmosphere.

3. The method for recycling the positive electrode material of the waste lithium battery as claimed in claim 2, wherein: the waste gas generated by the heat treatment is absorbed and treated by an active agent; the active agent comprises at least one of activated carbon, silica gel, zeolite, mineral clay and activated alumina.

4. The method for recycling the anode material of the waste lithium ion battery according to claim 1, wherein the method comprises the following steps: the active material of the positive electrode material in S1 includes LiCoO₂、LiNiO₂、LiMnO₂、LiNi_xMn_1-xO₂(0<x<1)、LiNi_xCo_yMn_1-x-yO₂(0<x、y<1) At least one of them.

5. The method for recycling the positive electrode material of the waste lithium battery as claimed in claim 1, wherein: the adding amount of the graphite powder in the S2 is 1.02-1.08 times of the reaction equivalent of the graphite powder and the active substance of the anode material.

6. The method for recycling the positive electrode material of the waste lithium battery as claimed in claim 1, wherein: the heating reduction reaction in S2 is carried out for 3-5h at 1400-1600 ℃.

7. The method for recycling the positive electrode material of the waste lithium battery as claimed in claim 1, wherein: the acid in S4 comprises at least one of hydrochloric acid, sulfuric acid and nitric acid.

8. The method for recycling the positive electrode material of the waste lithium battery as claimed in claim 1, wherein: the alkali reagent in S5 comprises at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide.

9. The method for recycling the positive electrode material of the waste lithium battery as claimed in claim 1, wherein: the carbonate in S5 includes at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium carbonate and ammonium bicarbonate.

10. The method for recycling the positive electrode material of the waste lithium battery as claimed in claim 1, wherein: the carbonate in S5 is added in an amount of CO₃ ^2-With Li in said lithium salt solution⁺1-1.05 times of reaction equivalent.

Technical Field

The invention relates to the technical field of lithium ion battery recovery, in particular to a method for recovering a waste lithium ion battery anode material.

Background

With the wider application of lithium ion batteries and the popularization of electric vehicles, the number of waste lithium batteries is also rapidly increased. The waste lithium ion battery is recycled, so that the loss of a large amount of valuable metal resources such as nickel, cobalt, manganese and lithium capable of being recycled is prevented, the resource shortage is relieved, the sustainable development of the lithium battery industry is promoted, and the pollution of the waste lithium ion battery to the environment is reduced.

In the prior art, the processes for recovering the lithium ion battery anode material mainly comprise a hydrometallurgy process and a pyrometallurgy process. The hydrometallurgical process mainly comprises the steps of leaching metal ions from an electrode material into a solution by using an acid-base solution, and recovering the metal ions from the leachate in the forms of salt, oxide and the like by means of ion exchange, precipitation, extraction and the like, wherein a large amount of acid liquor, alkali liquor and organic solvent are required to be used in the wet recovery process, so that the yield of three wastes is very high, secondary pollution to the environment is easily caused, and meanwhile, the process is complicated, the efficiency is low, the cost is high, and the economic benefit is very low; the pyrometallurgical process is to treat the battery material at high temperature to oxidize and decompose organic matters and convert metal elements into oxides, and has relatively simple technological process but no selective recovery of valuable metals.

However, because of the secondary pollution and high cost of the lithium ion battery, the recycling technology of the waste lithium ion battery has not been widely applied, and therefore, how to provide a method for separating and recovering nickel, cobalt, manganese and lithium from the waste lithium ion battery, which has a simple process and a high recovery rate and is suitable for large-scale production, is a problem that research and development technicians in the field are urgently required to solve.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention mainly aims to provide the method for recovering the waste lithium ion battery anode material, wherein the method adopts a combination of pyrometallurgy and hydrometallurgy to respectively recover nickel, cobalt, manganese and lithium, and has the advantages of high recovery efficiency, simple process, suitability for large-scale application and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for recovering a waste lithium ion battery anode material comprises the following steps:

s1, pretreating the waste lithium ion battery to obtain a positive electrode material;

s2, mixing the anode material with graphite powder, and carrying out heating reduction reaction in an inert atmosphere to obtain a solid product;

s3, screening the solid product to respectively obtain slag powder and metal alloy;

s4, adding acid to the slag powder for dissolving, and filtering to obtain a lithium salt solution;

s5, adding an alkali reagent into the lithium salt solution to adjust the pH value to 7-11, and then adding carbonate to precipitate to obtain lithium carbonate precipitate.

Preferably, the pretreatment in S1 includes disassembling and separating the waste lithium ion battery to obtain the positive electrode material.

Preferably, the pretreatment in S1 includes heat treatment of the positive electrode material to remove the binder attached to the positive electrode material and the remaining electrolyte solution.

Preferably, the heat treatment is carried out for 2-4h under the conditions of 300-500 ℃ in an inert atmosphere, and preferably for 2h under the conditions of 400 ℃.

Preferably, the inert atmosphere comprises at least one of nitrogen, argon, and the like.

Preferably, the waste gas generated by the heat treatment can be treated by absorbing with an active agent; the active agent comprises at least one of activated carbon, silica gel, zeolite, mineral clay, activated alumina, and the like.

Preferably, after the heat treatment, the positive electrode material is crushed and sieved to recover a current collector aluminum foil.

Preferably, the active material of the positive electrode material in S1 includes LiCoO₂、LiNiO₂、LiMnO₂、LiNi_xMn_1-xO₂(0<x<1)、LiNi_xCo_yMn_1-x-yO₂(0<x、y<1) And the like.

Preferably, the mixing in S2 may be ball milling.

Preferably, the rotation speed of the ball milling is 300-; the ball milling time is 60-120 min; the ball-milling ball material mass ratio is 15:1-20: 1; the grinding balls for ball milling are zirconia balls or alumina balls with the diameter of 1-4 cm.

Preferably, the addition amount of the graphite powder in S2 is 1.02 to 1.08 times the reaction equivalent of the graphite powder with the active material of the positive electrode material.

Preferably, the inert atmosphere in S2 includes at least one of nitrogen, argon, and the like.

Preferably, the heating reduction reaction in S2 is carried out at 1400 ℃ and 1600 ℃ for 3-5h, preferably at 1500 ℃ for 3 h.

Preferably, the heating rate of the heating reduction reaction in S2 is 10-15 deg.C/min.

Preferably, the reaction product can be naturally cooled to room temperature after the heating reduction reaction in S2; more preferably, programmed cooling, i.e. cooling at a cooling rate of 1 ℃/min, may be employed.

Preferably, the graphite powder in S2 is a high-purity graphite powder.

Preferably, CO gas is also generated in the heating reduction reaction in S2, and the CO can be recycled by using a gas recycling system.

Preferably, the screening in S3 may be performed using a vibrating screen.

Preferably, the acid in S4 may include at least one of hydrochloric acid, sulfuric acid, nitric acid, and the like.

Preferably, the acid concentration in S4 is 0.1-1 mol/L.

Preferably, the solid-to-liquid ratio of the slag powder to the acid solution in S4 is 1:5 to 1: 20.

Preferably, the alkali agent in S5 may include at least one of lithium hydroxide, sodium hydroxide, potassium hydroxide, and the like.

Preferably, the carbonate in S5 may include at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium carbonate, ammonium bicarbonate, and the like.

Preferably, the carbonate is added in an amount of CO in S5₃ ^2-With Li in said lithium salt solution⁺1-1.05 times of reaction equivalent.

Preferably, the precipitation in S5 may be followed by aging at 60-100 ℃ for 0.5-3 h.

Preferably, the lithium carbonate precipitate obtained in S5 may be washed with water.

Compared with the prior art, the invention has the following advantages and technical effects:

(1) the method provided by the invention can be used for recovering valuable metals in the anode material of the waste lithium battery and realizing the high-efficiency separation of metals such as nickel, cobalt and manganese and lithium, wherein the recovery rate of the metals such as nickel, cobalt and manganese is more than 99%, and the recovery rate of the lithium metal is more than 95%.

(2) The recovery method provided by the invention is compatible with the existing industrial equipment, such as an alternating current electric arc furnace and a direct current electric arc furnace.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a process flow chart of a method for recovering a waste lithium ion battery positive electrode material according to embodiment 1 of the present invention.

Detailed Description

The present invention will be described in further detail below with reference to specific embodiments and specific examples, but the embodiments of the present invention are not limited thereto. All the raw materials and reagents used in the present invention are commercially available raw materials and reagents, unless otherwise specified.

S1, pretreatment of waste lithium ion batteries

The lithium ion battery mainly comprises a negative plate, a diaphragm and a positive plate, wherein the positive plate takes an aluminum foil as a current collector, positive materials (active materials, conductive agents and binder PVDF) are coated on two sides of the positive plate, valuable metals of the positive materials of the waste lithium ion batteries are recycled, and the lithium ion batteries need to be pretreated to obtain the positive materials.

In one embodiment, the pre-treatment comprises deep discharge of spent lithium ion batteries. Because the waste lithium ion battery usually has residual electricity, which may be rapidly released in the disassembling and crushing processes to cause combustion, explosion and the like, the waste lithium ion battery needs to be deeply discharged to improve the safety of the recovery process. In one embodiment, the deep discharge may be performed by a cryogenic freezing method, in which the waste lithium ion battery is frozen at a very low temperature to inactivate the lithium ion battery and then disassembled, and specifically, the waste lithium ion battery is disassembled after being inactivated by being placed in liquid nitrogen. In another embodiment, the waste lithium ion battery is discharged by using a charging and discharging device, and then is put into a sodium chloride salt solution to short the anode and the cathode, so that deep discharge is completed.

In one embodiment, the pre-treatment comprises heat treating the positive electrode material; the heat treatment is heating for 2-4h at the temperature of 300-500 ℃ in an inert atmosphere, preferably heating for 2h at the temperature of 400 ℃; the inert atmosphere comprises at least one of nitrogen, argon, and the like. Since PVDF has thermal decomposition performance and can be decomposed at the temperature of 500 ℃ below zero (300-.

Further, in order to prevent air from being contaminated by volatilized binders and the like, an active agent is used in one embodiment to absorb exhaust gas generated by the heat treatment. The active agent comprises at least one of activated carbon, silica gel, zeolite, mineral clay, activated alumina, and the like.

In one embodiment, the positive electrode material is crushed and sieved after the heat treatment to remove the aluminum foil of the current collector. After heat treatment, the binder volatilizes, and the positive electrode material falls off from the current collector aluminum foil, so that the current collector aluminum foil can be separated by adopting a crushing and screening mode and recovered.

In one embodiment, the active material of the positive electrode material includes LiCoO₂、LiNiO₂、LiMnO₂、LiNi_xMn_1-xO₂(0<x<1)、LiNi_xCo_yMn_1-x-yO₂(0<x、y<1) And the like.

S2, heating reduction reaction of positive electrode material

The invention adopts high-temperature heating reduction reaction to separate nickel, cobalt, manganese and lithium in the anode material, in the reduction reaction process, metal elements such as nickel, cobalt, manganese and the like are reduced into metal simple substances to form alloy, the lithium element is extremely active, the metal elements can not be reduced into simple substances or alloy in the reduction reaction and only exist in an oxide state, thereby realizing the separation of nickel, cobalt, manganese and lithium, and the reaction formula of the reduction reaction is as follows:

where M is Ni, Mn, Co, or the like.

In one embodiment, the heating reduction reaction is performed under an inert atmosphere comprising at least one of nitrogen, argon, and the like. If the oxygen in the air is not shielded, the oxygen can participate in the heating reduction reaction, for example, the reducing agent adopted in the invention is graphite powder, and the graphite powder and the oxygen can be combusted at high temperature to generate carbon dioxide, so that the reaction is carried out under the inert atmosphere, the oxidation combustion of the graphite powder is avoided, and simultaneously, the chemical reactions generated by all chemical substances are different under the aerobic and anaerobic conditions, and the final recovery efficiency of the nickel, cobalt, manganese and lithium is obviously influenced.

In one embodiment, the positive electrode material and the graphite powder are completely mixed by ball milling. The rotating speed of the ball milling is 300-600 r/min; the ball milling time is 60-120 min; the ball-milling ball material mass ratio is 15:1-20: 1; the grinding balls for ball milling are zirconia balls or alumina balls with the diameter of 1-4 cm.

In one embodiment, the heating reduction reaction is carried out at 1400 ℃ and 1600 ℃ for 3-5h, preferably at 1500 ℃ for 3 h. Under the condition, the active substances of the cathode material can fully perform reduction reaction with graphite powder, and the recovery efficiency of metals such as nickel, cobalt, manganese and the like is obviously improved.

In one embodiment, a gas recovery system is used for recovering CO gas generated in the heating reduction reaction, wherein CO is a reducing agent commonly used in metal smelting, and a plurality of metal oxides can be reduced into elemental metal under high-temperature conditions. Further, in order to improve economic efficiency, the recovered CO gas may be used for the heating reduction reaction of the cathode material.

S3, screening the solid product to respectively obtain slag powder and metal alloy;

in one embodiment, the screening may be performed using a vibrating screen. In step S2, after the positive electrode material is heated and reduced, the metal elements such as nickel, cobalt and manganese are reduced to form a bulk metal alloy, and the lithium element forms an oxide to form a powdery slag with the excess graphite powder, so that the nickel, cobalt and manganese metal alloy and the slag can be separated by direct sieving.

S4 preparation of lithium salt solution

The slag powder is a mixture of lithium oxide and graphite powder, and the lithium oxide is easily dissolved in acid, so the lithium oxide is dissolved by the acid to generate a lithium salt solution, and then the lithium salt solution is filtered, so that the graphite powder is separated.

In one embodiment, the acid may include at least one of hydrochloric acid, sulfuric acid, nitric acid, and the like; the concentration of the acid is 0.1-1 mol/L. Wherein, the generated lithium chloride, lithium sulfate and lithium nitrate can be dissolved in water to form a lithium salt solution.

In one embodiment, the solid-to-liquid ratio of the slag powder to the acid solution is from 1:5 to 1: 20.

S5 preparation of carbonate

Adding an alkaline agent to the lithium salt solution to adjust the pH of the solution to 7-11, one for neutralizing excess acid in preparation for the next addition of carbonate, and one for adding impurity metal ions such as Al in the lithium salt solution³⁺、Cu²⁺、Ca²⁺、Fe³⁺、Fe²⁺、Zn²⁺、Cd²⁺Etc. are precipitated in the form of hydroxide, thereby increasing the purity of the lithium carbonate precipitate that is ultimately produced. In one embodiment, the alkaline agent may include at least one of lithium hydroxide, sodium hydroxide, potassium hydroxide, and the like; preferably, the alkaline agent may be sodium hydroxide. Sodium hydroxide is commonly known as caustic soda, caustic soda and caustic soda, is a common chemical product, and has the characteristics of low price and easy obtainment.

The invention adopts carbonate to precipitate lithium salt solution to generate lithium carbonate precipitate. In one embodiment, the carbonate may include at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium carbonate, ammonium bicarbonate, and the like; the carbonate is added in an amount of CO₃ ^2-With Li in said lithium salt solution⁺1-1.05 times of reaction equivalent.

Furthermore, in order to improve the precipitation efficiency of the lithium carbonate, the lithium carbonate is aged for 0.5 to 3 hours at the temperature of between 60 and 100 ℃ after precipitation, and the solubility of the lithium carbonate in hot water is low, so that the temperature of a reaction system is improved, the precipitation efficiency of the lithium carbonate can be improved, and meanwhile, the aging can reduce impurities occluded in the lithium carbonate, improve the purity of lithium carbonate precipitation, and can enable lithium carbonate precipitation crystals to grow, increase the particle size of the crystals, and ensure that the particle size distribution of the lithium carbonate precipitation crystals is relatively uniform.

In one embodiment, the obtained lithium carbonate precipitate may be washed with water, and the washed lithium carbonate precipitate may be sold as a product.

The following is a specific example to further illustrate the method for recycling the waste lithium ion battery cathode material, wherein the waste lithium ion battery cathode material adopted in the example contains 8.2% of Li, 19.5% of Ni, 20.4% of Co and 19.6% of Mn.

Example 1

S1, deeply discharging, disassembling and separating the waste lithium ion battery to obtain a positive plate, heating for 2 hours at 400 ℃ in an argon atmosphere, crushing, screening, and removing a current collector aluminum foil to obtain a positive electrode material;

s2, performing ball milling on the positive electrode material and graphite powder at the rotating speed of 400r/min for 80min (controlling the adding amount of the graphite powder to be 1.05 times of the reaction equivalent of the active substances of the graphite powder and the positive electrode material), heating to 1600 ℃ at the heating rate of 15 ℃/min in the argon atmosphere, reacting for 3h under the condition, and naturally cooling to room temperature to obtain CO gas and solid products;

s3, screening the solid product by using a vibrating screen to respectively obtain slag powder and metal alloy;

s4, adding 0.5mol/L hydrochloric acid into the slag powder to dissolve (solid-liquid ratio is 1:10), and filtering to obtain a lithium salt solution;

s5, adding sodium hydroxide into lithium salt solution to adjust pH8, and then adding sodium carbonate to precipitate (controlling the addition of CO as carbonate)₃ ^2-With Li in lithium salt solution⁺1.05 times of reaction equivalent), and aging for 2 hours at 60 ℃ after precipitation to obtain lithium carbonate precipitate.

FIG. 1 is a flow chart of the process of example 1.

Example 2

S1, deeply discharging, disassembling and separating the waste lithium ion battery to obtain a positive plate, heating for 1h at 450 ℃ in an argon atmosphere, crushing, screening, and removing a current collector aluminum foil to obtain a positive electrode material;

s2, performing ball milling on the positive electrode material and graphite powder at the rotating speed of 300r/min for 120min (controlling the adding amount of the graphite powder to be 1.02 times of the reaction equivalent of the graphite powder and active substances of the positive electrode material), heating to 1400 ℃ at the heating rate of 10 ℃/min in an argon atmosphere, reacting for 3.5h under the condition to obtain CO gas and solid products, and recovering the CO gas by adopting a gas recovery device;

s3, screening the solid product by using a vibrating screen to respectively obtain slag powder and metal alloy;

s4, adding 0.1mol/L hydrochloric acid into the slag powder to dissolve (the solid-liquid ratio is 1:20), and filtering to obtain a lithium salt solution;

s5, adding sodium hydroxide into lithium salt solution to adjust pH9, and then adding sodium carbonate to precipitate (controlling the addition of CO as carbonate)₃ ^2-With Li in lithium salt solution⁺1.05 times of reaction equivalent), and aging for 1h at 80 ℃ after precipitation to obtain lithium carbonate precipitate.

Example 3

S1, deeply discharging, disassembling and separating the waste lithium ion battery to obtain a positive plate, heating for 3 hours at 350 ℃ in an argon atmosphere, crushing, screening, and removing a current collector aluminum foil to obtain a positive electrode material;

s2, performing ball milling on the positive electrode material and graphite powder at the rotating speed of 600r/min for 60min (controlling the adding amount of the graphite powder to be 1.08 times of the reaction equivalent of the graphite powder and active substances of the positive electrode material), heating to 1550 ℃ at the heating rate of 15 ℃/min in the argon atmosphere, reacting for 4h under the condition to obtain CO gas and solid products, and recovering the CO gas by adopting a gas recovery device;

s3, screening the solid product by using a vibrating screen to respectively obtain slag powder and metal alloy;

s4, adding 0.5mol/L hydrochloric acid into the slag powder to dissolve (solid-liquid ratio is 1:10), and filtering to obtain a lithium salt solution;

s5, adding sodium hydroxide into lithium salt solution to adjust pH10, and then adding sodium carbonate to precipitate (controlling the addition of CO as carbonate)₃ ^2-With Li in lithium salt solution⁺1 time of reaction equivalent), and aging for 2 hours at 60 ℃ after precipitation to obtain lithium carbonate precipitate.

Example 4

S1, deeply discharging, disassembling and separating the waste lithium ion battery to obtain a positive plate, heating for 1.5 hours at 500 ℃ in an argon atmosphere, then crushing, screening, and removing a current collector aluminum foil to obtain a positive electrode material;

s2, ball-milling the positive electrode material and graphite powder for 100min at the rotating speed of 400r/min (controlling the adding amount of the graphite powder to be 1.03 times of the reaction equivalent of the active substances of the graphite powder and the positive electrode material), heating to 1500 ℃ at the heating rate of 15 ℃/min in the argon atmosphere, reacting for 3h under the condition to obtain CO gas and solid products, and recovering the CO gas by adopting a gas recovery device;

s3, screening the solid product by using a vibrating screen to respectively obtain slag powder and metal alloy;

s4, adding 1mol/L hydrochloric acid into the slag powder to dissolve (solid-liquid ratio is 1:5), and filtering to obtain a lithium salt solution;

s5, adding sodium hydroxide into lithium salt solution to adjust pH11, and then adding sodium carbonate to precipitate (controlling the addition of CO as carbonate)₃ ^2-With Li in lithium salt solution⁺1.03 times of reaction equivalent), and aging for 0.5h at 100 ℃ after precipitation to obtain lithium carbonate precipitate.

Comparative example 1

S1, deeply discharging, disassembling and separating the waste lithium ion battery to obtain a positive plate, heating for 2 hours at 400 ℃ in an argon atmosphere, crushing, screening, and removing a current collector aluminum foil to obtain a positive electrode material;

s2, mixing the positive electrode material with graphite powder (the adding amount of the graphite powder is controlled to be 1.05 times of the reaction equivalent of the active substances of the graphite powder and the positive electrode material), heating to 1600 ℃ at a heating rate of 15 ℃/min, and reacting for 1.5h under the condition to obtain a solid product;

s3, screening the solid product by using a vibrating screen to respectively obtain slag powder and metal alloy;

s4, adding 0.5mol/L hydrochloric acid into the slag powder to dissolve (solid-liquid ratio is 1:10), and filtering to obtain a lithium salt solution;

s5 in lithium salt solutionAdding sodium hydroxide to adjust pH8, adding sodium carbonate to precipitate (controlling the amount of carbonate added to CO)₃ ^2-With Li in lithium salt solution⁺1.05 times of reaction equivalent), and aging for 2 hours at 60 ℃ after precipitation to obtain lithium carbonate precipitate.

Comparative example 2

S1, deeply discharging, disassembling and separating the waste lithium ion battery to obtain a positive plate, heating for 2 hours at 400 ℃ in an argon atmosphere, crushing, screening, and removing a current collector aluminum foil to obtain a positive electrode material;

s2, mixing the positive electrode material with graphite powder (the adding amount of the graphite powder is controlled to be 0.9 times of the reaction equivalent of the active substances of the graphite powder and the positive electrode material), heating to 1600 ℃ at a heating rate of 15 ℃/min in an argon atmosphere, and reacting for 3h under the condition to obtain CO gas and solid products;

s3, screening the solid product by using a vibrating screen to respectively obtain slag powder and metal alloy;

s4, adding 0.5mol/L hydrochloric acid into the slag powder to dissolve (solid-liquid ratio is 1:10), and filtering to obtain a lithium salt solution;

s5, adding sodium hydroxide into lithium salt solution to adjust pH8, and then adding sodium carbonate to precipitate (controlling the addition of CO as carbonate)₃ ^2-With Li in lithium salt solution⁺0.9 times of reaction equivalent), and aging for 2 hours at 60 ℃ after precipitation to obtain lithium carbonate precipitate.

Ni, Co, Mn, and Li contents in the metal alloys prepared in examples 1 to 4 and comparative examples 1 to 2 and lithium carbonate precipitates were measured, and Ni, Co, Mn, and Li recovery rates were calculated, and the results are shown in Table 1.

TABLE 1 recovery of Ni, Co, Mn, Li

As can be seen from the data in Table 1, in the method for recovering the anode material of the waste lithium ion battery, the recovery rate of nickel, cobalt and manganese can reach more than 99%, and the recovery rate of lithium can reach more than 95%Compared with the example 1, the conditions of the heating reduction reaction are different in the comparative example 1 (the comparative example 1 is not carried out under the inert atmosphere condition, and the heating reduction reaction time is 1.5h), and the data show that the different conditions of the heating reduction reaction have obvious influence on the recovery efficiency of nickel, cobalt, manganese and lithium, that is, the chemical reactions generated by chemical substances are different under the aerobic and anaerobic conditions, that is, the time of the heating reduction reaction is obviously related to whether the substances in the positive electrode material are fully reacted, that is, the mixing degree of the graphite powder and the positive electrode material is obviously related to whether the substances in the positive electrode material are fully reacted, and that the recovery rate of the elements in the example 1 is obviously different from that in the comparative example 1. Comparative example 2 compared with example 1, the amount of graphite powder added was different and was directly related to whether the heating reduction reaction was sufficient, when the amount of graphite powder added as a reducing agent was insufficient, the active material portion of the positive electrode material was not reduced, which directly resulted in a decrease in the amount of metal alloy produced, and when the heating reduction reaction was sufficiently performed, lithium oxide was produced, which easily reacted with an acid, and when the reaction was insufficient, the active material of the positive electrode material such as LiMO was produced₂The (M is Ni, Co or Mn) is more severe for the conditions of acid leaching lithium, and affects the purity of the finally generated lithium carbonate precipitate.

The above embodiments are the best mode for carrying out the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be regarded as equivalent substitutions and are included in the scope of the present invention.