METHOD FOR SAFE PYROLYSIS AND IMPURITY REMOVAL OF WASTE LITHIUM BATTERY AND APPLICATION

Abstract

A method for removing impurities from a waste lithium battery safely through pyrolysis. The method may include: (1) performing primary roasting on electrode fragments of a waste lithium battery, quenching, and then layered screening to obtain a current collector fragment and an electrode material; (2) mixing and grinding the electrode material and a grinding aid, soaking the mixture in an alkali liquor, filtering and taking out filter residues to obtain electrode powder, and (3) performing secondary roasting on the electrode powder to obtain a positive electrode material.

Claims

1. A method for removing impurities from a waste lithium battery safely through pyrolysis, comprising the following steps of: (1) performing primary roasting on electrode fragments of a waste lithium battery, quenching, and then layered screening to obtain a current collector fragment and an electrode material; wherein in step (1), an ultrasonic vibrating screen is used for screening, and a mesh number of a parent net of the ultrasonic vibrating screen is 16 meshes or 20 meshes, a mesh number of a transition net of the ultrasonic vibrating screen is one of 100 meshes, 140 meshes or 200 meshes, and a mesh number of a sub-net of the ultrasonic vibrating screen is one of 500 meshes, 540 meshes or 600 meshes: (2) mixing and grinding the electrode material and a grinding aid, soaking the mixture in an alkali liquor, filtering and taking out filter residues to obtain electrode powder; and (3) performing secondary roasting on the electrode powder to obtain a positive electrode material: wherein the secondary roasting is performed at a temperature of 600 C. to 1000 C., and lasts for 60 minutes to 90 minutes, and the secondary roasting is performed in an atmosphere of air or oxygen.

2. The method of claim 1, wherein in step (1), the primary roasting is performed at a temperature of 420 C. to 600 C., and lasts for 45 minutes to 90 minutes, and the primary roasting is performed in an atmosphere of air or oxygen.

3. (canceled)

4. The method of claim 1, wherein in step (1), the quenching is to spray a freeze spray to cool the electrode fragment of the waste lithium battery to a temperature less than 50 C. within 90 seconds; and the freeze spray is cold air with a temperature less than 15 C.

5. The method of claim 1, wherein in step (2), the grinding aid is at least one of white carbon black, opal powder or quartz powder.

6. The method of claim 1, wherein in step (2), a mass ratio of the grinding aid to the electrode material is (0.1 to 0.5): 100.

7. The method of claim 1, wherein in step (2), the alkali liquor is one of sodium hydroxide, magnesium hydroxide, potassium hydroxide or calcium hydroxide.

8. The method of claim 1, wherein in step (2), an OH.sup. concentration of the alkali liquor is 0.01 mol/L to 0.2 mol/L.

9. (canceled)

10. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0040] The present disclosure will be further explained with reference to the accompanying drawings and embodiments hereinafter, wherein:

[0041] FIG. 1 is a process flow chart of Embodiment 1 of the present disclosure.

DETAILED DESCRIPTION

[0042] The concepts and the technical effects produced of the present disclosure will be clearly and completely described in conjunction with the embodiments and the accompanying drawings so as to sufficiently understand the objects, the features and the effects of the present disclosure. Obviously, the described embodiments are merely some embodiments of the present disclosure, rather than all the embodiments. Other embodiments obtained by those skilled in the art without going through any creative effort shall all fall within the protection scope of the present disclosure.

Embodiment 1

[0043] A method removing impurities from a waste lithium battery safely through pyrolysis of this embodiment comprises the following steps of:

[0044] (1) recycling a waste lithium battery, discharging and performing primary crushing to obtain waste electrode fragments with a length and width of 2 cm to 3 cm and a mass of 7.34 kg, placing the waste electrode fragments in a heating furnace for primary roasting for 45 minutes under the conditions of 586 C. and introducing oxygen, moving the roasted waste electrode fragments into a mesh basket and spraying cold air at 10 C. for quenching, selecting an ultrasonic vibrating screen for screening (16 meshes for a parent net, 100 meshes for a transition net, and 540 meshes for a sub-net), wherein the parent net collected current collector fragments, the transition net collected material fragments containing impurities, and the sub-net collected coarse particle electrode materials containing more impurities;

[0045] (2) washing and drying the current collector fragments trapped by the parent net, collecting the current collector fragment, crushing the electrode material fragments trapped by the transition net and the coarse particle electrode materials trapped by the sub-net into fine particles by a crusher, screening with the transition net and the sub-net of the ultrasonic vibrating screen for the second time, in the second screening, trapping and collecting the coarse current collector particles by the transition net, and using the coarse particle electrode material trapped by the sub-net for crushing into fine particles by the crusher again, and then screening the fine particles through the sub-net to obtain the electrode material;

[0046] (3) feeding white carbon black and the electrode material in a mass ratio of 0.41:100 into an oscillating ball mill with a number of revolutions of 540 rpm for grinding for 87 minutes, soaking in a sodium hydroxide solution with an OH.sup. concentration of 0.031 mol/L for 12 minutes, and filtering to obtain a filtrate and a filter residue, wherein the filtrate could be used for soaking the electrode powder again when being supplemented with alkali, and washing the filter residue with water and then drying the filter residue to obtain electrode powder; and

[0047] (4) moving the electrode powder to a heating furnace, and then roasting in the heating furnace at 755 C. for 87 minutes under the condition of introducing air to obtain 5.37 kg of positive electrode material.

[0048] FIG. 1 is a process flow chart of Embodiment 1 of the present disclosure. It can be seen from FIG. 1 that the waste lithium battery is discharged and subjected to primary crushing to obtain the waste electrode fragments, and then subjected to primary roasting, cooling and screening, and then laminated and screened by using the ultrasonic vibrating screen, i.e., screened and graded by the three layers of nets comprising the parent net, the transition net and the sub-net, and then removed from impurities through the dilute alkali, filtered and subjected to secondary roasting to obtain the electrode powder.

Embodiment 2

[0049] A method removing impurities from a waste lithium battery safely through pyrolysis of this embodiment comprises the following steps of:

[0050] (1) recycling a waste lithium battery, discharging and performing primary crushing to obtain waste electrode fragments with a length and width of 2 cm to 3 cm and a mass of 8.79 kg, placing the waste electrode fragments in a heating furnace for primary roasting for 69 minutes under the conditions of 550 C. and introducing oxygen, moving the roasted waste electrode fragments into a mesh basket and spraying cold air at 10 C. for quenching, selecting an ultrasonic vibrating screen for screening (20 meshes for a parent net, 100 meshes for a transition net, and 540 meshes for a sub-net), wherein the parent net collected current collector fragments, the transition net collected material fragments containing impurities, and the sub-net collected coarse particle electrode materials containing more impurities;

[0051] (2) washing and drying the current collector fragments trapped by the parent net, collecting the current collector fragment, crushing the electrode material fragments trapped by the transition net and the coarse particle electrode materials trapped by the sub-net into fine particles by a crusher, screening with the transition net and the sub-net of the ultrasonic vibrating screen for the second time, in the second screening, trapping and collecting the coarse current collector particles by the transition net, and using the coarse particle electrode material trapped by the sub-net for crushing into fine particles by the crusher again, and then screening the fine particles through the sub-net to obtain the electrode material;

[0052] (3) feeding white carbon black and the electrode material in a mass ratio of 0.27:100 into an oscillating ball mill with a number of revolutions of 480 rpm for grinding for 104 minutes, soaking in a dilute sodium hydroxide solution with an OH.sup. concentration of 0.157 mol/L for 10 minutes, and filtering to obtain a filtrate and a filter residue, wherein the filtrate could be used for soaking the electrode powder again when being supplemented with alkali, and washing the filter residue with water and then drying the filter residue to obtain electrode powder; and

[0053] (4) moving the electrode powder to a heating furnace, and then roasting in the heating furnace at 695 C. for 78 minutes under the condition of introducing air to obtain 6.64 kg of positive electrode material.

Embodiment 3

[0054] A method removing impurities from a waste lithium battery safely through pyrolysis of this embodiment comprises the following steps of:

[0055] (1) recycling a waste lithium battery, discharging and performing primary crushing to obtain waste electrode fragments with a length and width of 2 cm to 3 cm and a mass of 3.37 kg, placing the waste electrode fragments in a heating furnace for primary roasting for 57 minutes under the conditions of 580 C. and introducing oxygen, moving the roasted waste electrode fragments into a mesh basket and spraying cold air at 10 C. for quenching, selecting an ultrasonic vibrating screen for screening (20 meshes for a parent net, 100 meshes for a transition net, and 600 meshes for a sub-net), wherein the parent net collected current collector fragments, the transition net collected material fragments containing impurities, and the sub-net collected coarse particle electrode materials containing more impurities;

[0056] (2) washing and drying the current collector fragments trapped by the parent net, collecting the current collector fragment, crushing the electrode material fragments trapped by the transition net and the coarse particle electrode materials trapped by the sub-net into fine particles by a crusher, screening with the transition net and the sub-net of the ultrasonic vibrating screen for the second time, in the second screening, trapping and collecting the coarse current collector particles by the transition net, and using the coarse particle electrode material trapped by the sub-net for crushing into fine particles by the crusher again, and then screening the fine particles through the sub-net to obtain the electrode material;

[0057] (3) feeding white carbon black and the electrode material in a mass ratio of 3:100 into an oscillating ball mill with a number of revolutions of 540 rpm for grinding for 76 minutes, soaking in a dilute sodium hydroxide solution with an OH.sup. concentration of 0.138 mol/L for 15 minutes, and filtering to obtain a filtrate and a filter residue, wherein the filtrate could be used for soaking the electrode powder again when being supplemented with alkali, and washing the filter residue with water and then drying the filter residue to obtain electrode powder; and

[0058] (4) moving the electrode powder to a heating furnace, and then roasting in the heating furnace at 845 C. for 67 minutes under the condition of introducing air to obtain 6.31 kg of positive electrode material.

Embodiment 4

[0059] A method removing impurities from a waste lithium battery safely through pyrolysis of this 20 embodiment comprises the following steps of:

[0060] (1) recycling a waste lithium battery, discharging and performing primary crushing to obtain waste electrode fragments with a length and width of 2 cm to 3 cm and a mass of 7.83 kg, placing the waste electrode fragments in a heating furnace for primary roasting for 68 minutes under the conditions of 490 C. and introducing oxygen, moving the roasted waste electrode fragments into a mesh basket and spraying cold air at 10 C. for quenching, selecting an ultrasonic vibrating screen for screening (16 meshes for a parent net, 200 meshes for a transition net, and 600 meshes for a sub-net), wherein the parent net collected current collector fragments, the transition net collected material fragments containing impurities, and the sub-net collected coarse particle electrode materials containing more impurities;

[0061] (2) washing and drying the current collector fragments trapped by the parent net, collecting the current collector fragment, crushing the electrode material fragments trapped by the transition net and the coarse particle electrode materials trapped by the sub-net into fine particles by a crusher, screening with the transition net and the sub-net of the ultrasonic vibrating screen for the second time, in the second screening, trapping and collecting the coarse current collector particles by the transition net, and using the coarse particle electrode material trapped by the sub-net for crushing into fine particles by the crusher again, and then screening the fine particles through the sub-net to obtain the electrode material;

[0062] (3) feeding opal powder and the electrode material in a mass ratio of 0.14:100 into an oscillating ball mill with a number of revolutions of 540 rpm for grinding for 69 minutes, soaking in a dilute potassium hydroxide solution with an OH.sup. concentration of 0.175 mol/L for 15 minutes, and filtering to obtain a filtrate and a filter residue, wherein the filtrate could be used for soaking the electrode powder again when being supplemented with alkali, and washing the filter residue with water and then drying the filter residue to obtain electrode powder; and

[0063] (4) moving the electrode powder to a heating furnace, and then roasting in the heating furnace at 755 C. for 75 minutes under the condition of introducing air to obtain 5.64 kg of positive electrode material.

Comparative Example 1

[0064] A method removing impurities from a waste lithium battery safely through pyrolysis of this comparative example comprises the following steps of:

[0065] (1) recycling a waste lithium battery, discharging and performing primary crushing to obtain waste electrode fragments with a length and width of 2 cm to 3 cm and a mass of 7.45 kg, placing the waste electrode fragments in a heating furnace for cooling at normal temperature for 53 minutes under the conditions of 615 C. and introducing oxygen, selecting an ultrasonic vibrating screen for screening (16 meshes for a parent net, 140 meshes for a transition net, and 500 meshes for a sub-net), wherein the parent net collected current collector fragments, the transition net collected material fragments containing impurities, and the sub-net collected coarse particle electrode materials containing more impurities;

[0066] (2) washing and drying the current collector fragments trapped by the parent net, collecting the current collector fragment, crushing the electrode material fragments trapped by the transition net and the coarse particle electrode materials trapped by the sub-net into fine particles by a crusher, screening with the transition net and the sub-net of the ultrasonic vibrating screen for the second time, in the second screening, trapping and collecting the coarse current collector particles by the transition net, and using the coarse particle electrode material trapped by the sub-net for crushing into fine particles by the crusher again, and then screening the fine particles through the sub-net to obtain the electrode material;

[0067] (3) feeding white carbon black and the electrode material in a mass ratio of 0.43:100 into an oscillating ball mill with a number of revolutions of 480 rpm for grinding for 72 minutes, soaking in a dilute sodium hydroxide solution with an OH.sup. concentration of 0.076 mol/L for 14 minutes, and filtering to obtain a filtrate and a filter residue, wherein the filtrate could be used for soaking the electrode powder again when being supplemented with alkali, and washing the filter residue with water and then drying the filter residue to obtain electrode powder; and

[0068] (4) moving the electrode powder to a heating furnace, and then roasting in the heating furnace at 850 C. for 74 minutes under the condition of introducing air to obtain 5.64 kg of positive electrode material.

Comparative Example 2

[0069] A method removing impurities from a waste lithium battery safely through pyrolysis of this comparative example comprises the following steps of.

[0070] (1) recycling a waste lithium battery, discharging and performing primary crushing to obtain waste electrode fragments with a length and width of 2 cm to 3 cm and a mass of 8.07 kg, placing the waste electrode fragments in a heating furnace for primary roasting for 45 minutes under the conditions of 585 C. and introducing oxygen, moving the roasted waste electrode fragments into a mesh basket and spraying cold air at 10 C. for quenching, selecting an ultrasonic vibrating screen for screening (16 meshes for a parent net, 200 meshes for a transition net, and 600 meshes for a sub-net), wherein the parent net collected current collector fragments, the transition net collected material fragments containing impurities, and the sub-net collected coarse particle electrode materials containing more impurities;

[0071] (2) washing and drying the current collector fragments trapped by the parent net, collecting the current collector fragment, crushing the electrode material fragments trapped by the transition net and the coarse particle electrode materials trapped by the sub-net into fine particles by a crusher, screening with the transition net and the sub-net of the ultrasonic vibrating screen for the second time, in the second screening, trapping and collecting the coarse current collector particles by the transition net, and using the coarse particle electrode material trapped by the sub-net for crushing into fine particles by the crusher again, and then screening the fine particles through the sub-net to obtain the electrode material;

[0072] (3) feeding the electrode material into an oscillating ball mill with a number of revolutions of 540 rpm for grinding for 78 minutes, soaking in a dilute potassium hydroxide solution with an OH-concentration of 0.094 mol/L for 15 minutes, and filtering to obtain a filtrate and a filter residue, wherein the filtrate could be used for soaking the electrode powder again when being supplemented with alkali, and washing the filter residue with water and then drying the filter residue to obtain electrode powder; and

[0073] (4) moving the electrode powder to a heating furnace, and then roasting in the heating furnace at 780 for 87 minutes under the condition of introducing air to obtain 6.24 kg of positive electrode material.

TABLE-US-00001 TABLE 1 Detection values of aluminum and carbon in electrode materials of Embodiments 1, 2, 3 and 4 and Comparative Examples 1 and 2 Aluminum Aluminum Carbon Carbon content content content content before after after after dilute alkali dilute alkali primary secondary Treatment treatment treatment roasting roasting group (%) (%) (%) (%) Embodiment1 0.78 0.051 0.67 0.017 Embodiment 2 0.33 0.046 0.45 0.013 Embodiment 3 0.61 0.048 0.88 0.018 Embodiment 4 0.69 0.031 0.71 0.015 Comparative 0.91 0.21 0.83 0.023 Example 1 Comparative 0.78 0.15 0.91 0.031 Example 2

[0074] It can be seen from Table 1 that the positive electrode materials obtained through removing impurities by pyrolysis through the methods of Embodiments 1 to 4 of the present disclosure have low aluminum content, while the method of Comparative Example 1 is slow cooling at normal temperature, which is not conducive to the small curling degree of the current collector fragment, resulting in that the notch between the current collector fragment and the electrode material of the waste lithium battery is reduced, and the electrode material of the waste lithium battery after screening is not easy to fall off, so that the aluminum content before the dilute alkali treatment is high. In Comparative Example 2, no grinding aid is added, which will cause an agglomeration phenomenon that is unfavorable to particle dispersion, resulting in a larger particle size which is unfavorable to dispersion of carbonized scabs by roasting the binders, conductive agents, and organic solvents, and thus unfavorable to reaction between aluminum and dilute alkali, resulting in aluminum residue after the dilute alkali treatment.

[0075] The embodiments of the present disclosure are described in detail, but the present disclosure is not limited to the above embodiments, and various changes may also be made within the knowledge scope of those of ordinary skills in the art without departing from the purpose of the present disclosure. In addition, in case of no conflict, the embodiments in the application and the features in the embodiments may be combined with each other.