Patent Application
20240021902
The present disclosure belongs to the technical field of battery recycling, and specifically relates to a method for recovering an aluminum residue with a controlled particle size, and use thereof.
Battery positive electrode sheet scraps include aluminum-based current collectors, active substances such as lithium iron phosphate (LFP, LiFePO4) and lithium nickel manganese cobalt oxide (LNMCO, LiNixCoyMn1-x-yO2, where x+y=1, 0<x<1, 0<y<1), binders, conductive additives, etc., where Ni, Mn, Co, Li, Al, etc. are metals with potential recycling value.
Currently, the recycling of battery positive electrode sheet scraps mainly includes: subjecting the positive electrode sheet scraps to a series of treatments such as coarse crushing, physical sieving, and fine crushing to obtain a granular material of the positive electrode sheet scraps; and subjecting the granular material to acid extraction, alkali extraction, and valuable metal recovery. However, the positive electrode sheet scrap particles include a small amount of aluminum residue particles and other impurity particles that have a small particle size, and the mixing of the impurity particles with active substance and binder particles of positive electrode sheet scraps leads to high recycling difficulty. Therefore, a recovery rate of aluminum residue particles in positive electrode sheet scrap particles should be increased as much as possible to reduce the generation of flammable and explosive hydrogen from aluminum in a subsequent recovery process of valuable metals and improve the purity of recovered metals such as Ni, Co, and Li and the safety during extraction.
The present disclosure is intended to solve at least one of the technical problems existing in the prior art. In view of this, the present disclosure provides a method for recovering an aluminum residue with a controlled particle size, and use thereof. In the present disclosure, when fine crushing is conducted at a low temperature, the binding performance of a binder is significantly reduced, and positive electrode active substances and the binder are in a brittle state and are easily broken, but an aluminum residue still has some toughness. Different embrittlement temperatures of different materials allow selective crushing at a low temperature. Positive electrode active particles, binder particles, and aluminum residue particles obtained after crushing each have a narrow particle size range, which improves a recovery rate of the aluminum residue in the positive electrode sheet scrape particles and the safety during a recovery process of metals from a positive electrode scrape powder.
To achieve the above objective, the present disclosure adopts the following technical solutions:
The present disclosure provides a method for recovering an aluminum residue with a controlled particle size, including the following steps:
Preferably, in step (1), the granular material may have a particle size of 0.01 μm to 500 μm.
Preferably, in step (1), the liquid nitrogen may be added at an amount of 5% to 30% of a mass of the positive electrode sheet of the waste power battery.
Preferably, in step (2), the roasting may be conducted in an inert gas atmosphere; and further preferably, an inert gas of the inert gas atmosphere may be one from the group consisting of He, Ne, and Ar.
Preferably, in step (2), the roasting may be conducted at 350° C. to 500° C. for 30 min to min.
Preferably, in step (2), a heating rate for the roasting may be controlled at 10° C./min to and further preferably, the heating rate for the roasting may be controlled at 10° C./min to 15° C./min.
Preferably, in step (2), the alkaline solution may be at least one from the group consisting of Mg(OH)2, NaOH, and Ca(OH)2.
Preferably, in step (2), the gaseous binder may be polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE).
Preferably, in step (2), a grinder used in the grinding may have a treatment capacity of <100 kg/h and a rotational speed of 120 rpm to 180 rpm.
Preferably, in steps (3) and (4), a shaker used in the shaking may have a shaking frequency of 5 Hz to 20 Hz and a shaking amplitude of 0.5 cm to 2 cm, and the shaking may be conducted for 5 min to 10 min.
Preferably, in steps (3) and (4), during shaking, the waste positive electrode sheet powder may be kept immersed in water in a container.
Preferably, in steps (3) and (4), the water may be deionized water.
Preferably, steps (3) and (4) may be repeated 1 to 10 times until the aluminum residue particles and the positive electrode active powder in the particles are completely separated and collected.
The present disclosure also provides use of the method described above in valuable metal recovery.
In the present disclosure, aluminum residue particle impurities in a waste positive electrode sheet granular material still have some ductility and toughness at a low temperature (−196° C.) or a high temperature (350° C. to 500° C.), while positive electrode active substances in waste positive electrode particles become loose and have very low adhesion after being treated at a low temperature or a high temperature. Positive electrode active substance particles, binder particles, and aluminum residue particles obtained after fine crushing at a low temperature each have a narrow particle size range, which creates conditions for subsequent separation and recovery. During a heating process, the binder is volatilized in gaseous form and recovered, and a residue is then cooled and ground by a grinder under an appropriate pressure, where positive electrode active particles are easily ground into a positive electrode active powder with a smaller particle size, but the particle size of most aluminum residue particles remains unchanged. The Brazil nut effect is utilized: During a shaking process, small particles gradually seep through gaps among large particles to a lower part, such that the small particles are easy to fill in a lower layer below the large particles and the large particles accumulate in an upper layer. When the positive electrode active powder and aluminum residue particles with different particle sizes in the container are shaken at a specified shaking frequency, aluminum residue particles with a large particle size float in a surface layer, and the positive electrode sheet active powder sinks to a bottom layer; and then waste positive electrode sheet granular materials in the middle and upper layers are collected and shaken for the second time to separate and collect the aluminum residue and the positive electrode active powder, thereby effectively separating and collecting the positive electrode active powder and the coarse-grained aluminum residue in the waste positive electrode sheet granular material.
Compared with the prior art, the present disclosure has the following beneficial effects.
1. In the present disclosure, when fine crushing is conducted at a low temperature, the binding performance of a binder is significantly reduced, and positive electrode active substances and the binder are in a brittle state and are easily broken, but an aluminum residue still has some toughness. Different embrittlement temperatures of different materials allow selective crushing at a low temperature. Positive electrode active particles, binder particles, and aluminum residue particles obtained after crushing each have a narrow particle size range, which creates conditions for subsequent separation and recovery.
2. During the high-temperature roasting process of the present disclosure, the gaseous binder generated is adsorbed by the alkaline solution, which can not only achieve the recycling of the binder, but also immediately remove the binder in the waste positive electrode sheet particles to avoid interference of the binder for subsequent recovery processes.
3. In the present disclosure, after the high-temperature roasting, the positive electrode active particles are easily ground into a positive electrode active powder, and the particle size of most aluminum residue particles remains unchanged; and then the Brazil nut effect is used to accurately separate and recover an aluminum residue particle layer and a positive electrode active powder layer through two times of shaking and stratification, which avoids the sieving with a mesh screen and the inclusion of aluminum residue particles in a positive electrode active powder obtained after sieving, thereby improving the separation and recovery efficiency.
4. In the present disclosure, in the first shaking and the second shaking, deionized water is added in the container mainly for the following reasons: The water has a specified buoyant force, which can partially compensate the gravity of the positive electrode active powder and the aluminum residue particles, thereby accelerating the seepage flow between the two particles. The addition of the water can avoid the generation of dust in the container during the shaking, such that there will be no adverse consequences such as dust diffusion and dust explosion.
5. In the present disclosure, the shaking frequency, shaking amplitude, and shaking time of a shaker used in the first shaking and the second shaking, and the volume of a filled material in the container and the volume of added deionized water in the first shaking can be set as fixed values, such that a thickness of a contact layer between the aluminum residue particle layer and the positive electrode active powder layer in the container after the first shaking and a thickness of a critical layer between the aluminum residue particle layer and the positive electrode active powder layer after the second shaking are all fixed values, which avoids the re-determination of a layer thickness when steps (4) to (5) are repeated.
The sole figure is a flowchart of the method for recovering an aluminum residue with a controlled particle size according to an example of the present disclosure.
The concepts and technical effects of the present disclosure are clearly and completely described below in conjunction with examples, so as to allow the objectives, features and effects of the present disclosure to be fully understood. Apparently, the described examples are merely some rather than all of the examples of the present disclosure. All other examples obtained by those skilled in the art based on the examples of the present disclosure without creative efforts should fall within the protection scope of the present disclosure.
A method for recovering an aluminum residue with a controlled particle size was provided, including the following specific steps:
A method for recovering an aluminum residue with a controlled particle size was provided, including the following specific steps:
A method for recovering an aluminum residue with a controlled particle size was provided, including the following specific steps:
A method for recovering an aluminum residue was provided, including the following specific steps:
This comparative example was different from Example 1 in that the shaking in steps (4) and (5) was not conducted, and the waste positive electrode sheet particles were directly ground and sieved to obtain a positive electrode active powder and aluminum residue particles.
A method for recovering an aluminum residue with a controlled particle size was provided, including the following specific steps:
This comparative example was different from Example 1 in that, in step (1), the operation of adding liquid nitrogen to conduct fine crushing was not conducted.
Comparative analysis of Examples 1, 2, and 3 with the comparative examples:
Table 1 shows the mass percentages of aluminum residue in the positive electrode active powders recovered in Examples 1, 2, and 3 and Comparative Examples 1 and 2 and the aluminum residue particle size distribution percentages in 0 μm to 10 μm, 10 μm to 50 μm, 50 μm to 100 μm, and 100 μm to 500 μm. In Comparative Examples 1 and 2, liquid nitrogen and shaking treatments were not adopted, and only sieving was conducted with a conventional mesh screen to obtain a positive electrode active powder and aluminum residue particles. Mass percentage of aluminum residue in positive electrode active powder=mass of aluminum residue in a recovered positive electrode active powder/mass of the recovered positive electrode active powder*100%. Aluminum in the positive electrode active powder was determined by flame atomic absorption spectrometry (FAAS), and a particle size of the aluminum residue was determined with a laser particle size analyzer.
It can be seen from Table 1 that, compared with that in Comparative Examples 1 and 2, the positive electrode active powders prepared in Examples 1, 2, and 3 had extremely-small aluminum residue mass percentages (0.55%, 0.71%, and 0.42%, respectively), indirectly proving that a recovery rate of aluminum residue after the shaking was very high; in Examples 1, 2, and 3, the aluminum residue particle size distribution percentages in 0 μm to 50 μm were only of 7.86%, 6.31%, and 9.43%, respectively, but in Comparative Examples 1 and 2, the aluminum residue particle size distribution percentages in 0 μm to 50 μm were up to 13.53% and 19.75%, respectively; in Examples 1, 2, and 3, the aluminum residue particle size distribution percentages in 100 μm to 500 μm were of 73.88%, 76.82%, and 73.89% respectively (the largest), which were 23.52%, 26.46%, and 23.53% higher than the average aluminum residue particle size distribution percentages of Comparative Examples 1 and 2 in 100 μm to 500 μm, respectively; and compared with the comparative examples, in Examples 1, 2, and 3, the aluminum residue particle size distribution percentages in 100 μm to 500 μm were higher, indicating that the particle size of an aluminum residue was effectively controlled to improve the recovery efficiency of an aluminum residue.
The sole figure is a flowchart of the method for recovering an aluminum residue with a controlled particle size according to an example of the present disclosure, and it can be seen from the figure that, in the preparation of waste positive electrode sheet particles from a waste positive electrode sheet, liquid nitrogen is added to conduct fine crushing; and then the waste positive electrode sheet particles are subjected to roasting, grinding, two times of shaking for stratification to obtain an aluminum residue and a positive electrode active powder.
The examples of present disclosure are described in detail with reference to the accompanying drawings, but the present disclosure is not limited to the above examples. Within the scope of knowledge possessed by those of ordinary skill in the technical field, various changes can also be made without departing from the purpose of the present disclosure. In addition, the examples in the present disclosure or features in the examples may be combined with each other in a non-conflicting situation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202110373899.1 | Apr 2021 | CN | national |
The present application is a continuation application of PCT application No. PCT/CN2021/142524 filed on Dec. 29, 2021, which claims the benefit of Chinese Patent Application No. 202110373899.1 filed on Apr. 7, 2021. The contents of all of the aforementioned applications are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2021/142524 | Dec 2021 | US |
| Child | 18373950 | US |
