CN117625996A - Method for recycling lithium from lithium iron phosphate battery positive electrode waste powder - Google Patents
Method for recycling lithium from lithium iron phosphate battery positive electrode waste powder Download PDFInfo
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 243
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 242
- 239000002699 waste material Substances 0.000 title claims abstract description 69
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims abstract description 68
- 238000000034 method Methods 0.000 title claims abstract description 63
- 239000000843 powder Substances 0.000 title claims abstract description 55
- 238000004064 recycling Methods 0.000 title claims abstract description 20
- 239000007788 liquid Substances 0.000 claims abstract description 90
- 239000010949 copper Substances 0.000 claims abstract description 75
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 59
- 229910052802 copper Inorganic materials 0.000 claims abstract description 58
- 239000002893 slag Substances 0.000 claims abstract description 42
- 238000004090 dissolution Methods 0.000 claims abstract description 35
- JRBRVDCKNXZZGH-UHFFFAOYSA-N alumane;copper Chemical compound [AlH3].[Cu] JRBRVDCKNXZZGH-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000000746 purification Methods 0.000 claims abstract description 21
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 18
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000002002 slurry Substances 0.000 claims abstract description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 15
- 230000001376 precipitating effect Effects 0.000 claims abstract description 14
- 238000001914 filtration Methods 0.000 claims abstract description 12
- 230000032683 aging Effects 0.000 claims abstract description 11
- 239000012535 impurity Substances 0.000 claims abstract description 11
- 125000004122 cyclic group Chemical group 0.000 claims abstract description 8
- 229910000398 iron phosphate Inorganic materials 0.000 claims abstract description 8
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims abstract description 8
- 238000001556 precipitation Methods 0.000 claims abstract description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 53
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical group OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 28
- 239000002253 acid Substances 0.000 claims description 24
- 238000000926 separation method Methods 0.000 claims description 15
- 239000011734 sodium Substances 0.000 claims description 15
- 238000005868 electrolysis reaction Methods 0.000 claims description 11
- 238000002386 leaching Methods 0.000 claims description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 8
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 7
- 239000010439 graphite Substances 0.000 claims description 6
- 229910002804 graphite Inorganic materials 0.000 claims description 6
- 239000012528 membrane Substances 0.000 claims description 6
- 239000007800 oxidant agent Substances 0.000 claims description 6
- 159000000000 sodium salts Chemical class 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- 239000010936 titanium Substances 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- 229910018119 Li 3 PO 4 Inorganic materials 0.000 claims description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- 230000001590 oxidative effect Effects 0.000 claims description 5
- 239000012141 concentrate Substances 0.000 claims description 4
- 238000005470 impregnation Methods 0.000 claims description 3
- 239000002244 precipitate Substances 0.000 claims description 3
- 238000011084 recovery Methods 0.000 abstract description 18
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 8
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 8
- 238000009388 chemical precipitation Methods 0.000 abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 230000008021 deposition Effects 0.000 description 5
- 229910003002 lithium salt Inorganic materials 0.000 description 5
- 159000000002 lithium salts Chemical class 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 4
- 238000011033 desalting Methods 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000010405 anode material Substances 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 230000008929 regeneration Effects 0.000 description 3
- 238000011069 regeneration method Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 238000009854 hydrometallurgy Methods 0.000 description 2
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical class [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 229910010710 LiFePO Inorganic materials 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- -1 lithium copper aluminum Chemical compound 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 235000011118 potassium hydroxide Nutrition 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007430 reference method Methods 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000011257 shell material Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 235000017550 sodium carbonate Nutrition 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/84—Recycling of batteries or fuel cells
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- Manufacture And Refinement Of Metals (AREA)
- Secondary Cells (AREA)
Abstract
The invention belongs to the field of lithium ion batteries, and relates to a method for recycling lithium from lithium iron phosphate battery positive electrode waste powder, which comprises the following steps: selectively dissolving lithium from the waste anode powder of the lithium iron phosphate battery to obtain a lithium dissolution solution and iron phosphate slag; copper and aluminum impurities are removed from the lithium dissolution liquid, so that lithium purification liquid and lithium-containing copper and aluminum slag are obtained; precipitating and separating lithium from the lithium purification liquid; dispersing the lithium-containing copper aluminum slag in water, and then sequentially aging, acid-dissolving and filtering the obtained slurry to obtain Al (OH) 3 And electrolyzing the lithium-containing copper-rich liquid to obtain the lithium-containing copper-poor liquid and metallic copper, and returning the lithium-containing copper-poor liquid to the lithium dissolution liquid for cyclic treatment. The method provided by the invention can be adoptedLithium loss caused by removing copper and aluminum impurities through precipitation is further eliminated on the basis of recovering lithium through chemical precipitation, so that effective recovery of lithium is realized, and the method has a great application prospect.
Description
Technical Field
The invention belongs to the field of lithium ion batteries, and particularly relates to a method for recycling lithium from waste lithium iron phosphate battery anode powder.
Background
Lithium iron phosphate (LiFePO) 4 After first report in 1997, the simple LFP) material is a lithium ion battery anode material with good application prospect and has huge development space in the fields of electric commercial vehicles, special vehicles and energy storage by the characteristics of environmental friendliness, abundant raw material sources, low price, high specific capacity, excellent cycle performance and thermal stability. Under the dual drive of policy and market, new energy automobile markets in China have undergone explosive growth in the past 10 years. Starting from the popularization plan of the first new energy automobile in ten cities and thousand vehicles, the lithium iron phosphate battery is put into the field of new energy automobiles in China earlier. Generally, the service life of the lithium iron phosphate battery is 5-8 years, and the first new energy automobile power storage battery is old. The new power battery 'retired tide' is coming, and the lithium ion battery also quickly enters a large number of scrapping and recycling stages. The waste lithium ion battery contains a large amount of valuable metal components, electrolyte, diaphragm, shell material and the like, and if the waste lithium ion battery is improperly treated, serious threat is brought to the environment. The recycling of the waste lithium iron phosphate battery not only can reduce the pollution of the waste lithium ion battery to the environment, but also can bring considerable economic benefit.
The existing retired lithium iron phosphate battery recycling technology is mainly divided into three categories of cascade utilization, disassembly-separation recycling and metallurgical recycling according to the recycling cycle of materials. The step utilization is to disassemble, disassemble and detect retired power batteries for secondary recycling, and is used for scenes such as communication base stations, energy storage, low-speed electric vehicles and the like, so that the use value of the power batteries is maximized. The disassembly-separation recovery technology is to discharge and disassemble the scrapped battery, and the scrapped battery is separated according to the types of battery materials, so that the separation of plastics, metal shells, copper foils, aluminum foils and electrode materials is realized, the high-value electrode material is obtained, and the resource regeneration is realized through a pyrometallurgical recovery technology of a fire method or a wet method. Metallurgical recovery is the calcination of spent batteries in a furnace to decompose compounds therein, after which the metal alloy is obtained by reduction and hydrometallurgical steps.
The lithium iron phosphate positive electrode material is the core material with the highest value in the lithium iron phosphate power battery, and accounts for about 30-40% of the cost of the battery. The recovery technology for the waste lithium iron phosphate anode material is mainly divided into two aspects of a solid phase regeneration technology and a hydrometallurgy technology. The solid phase regeneration technology is to add lithium salt, carbon source and the like into waste lithium iron phosphate anode powder to adjust chemical composition, and then to realize the restoration of the composition and structure of the lithium iron phosphate material through the procedures of ball milling, sintering and the like. The hydrometallurgy technology is used for recovering valuable components such as lithium, iron, phosphorus and the like in the waste lithium iron phosphate anode material by a chemical method. The economic value of lithium is highest in the waste lithium iron phosphate materials, and many researches focus on the recovery of lithium.
For example, CN113666397a discloses a method for economically recycling lithium from waste lithium iron phosphate materials by acid process, which comprises mixing waste lithium iron phosphate powder, concentrated sulfuric acid and water into slurry, introducing air into the slurry, aerating and stirring, adding hydrogen peroxide to continue stirring when aeration is stopped, filtering, separating iron phosphate and PVDF, adding calcium carbonate to the filtrate to adjust pH, adding lime to adjust pH, filtering, adding saturated lithium carbonate to the filtrate, filtering, introducing carbon dioxide into the filtrate for sedimentation, filtering, washing and drying to obtain lithium carbonate. However, the method generally can only recover about 90% of lithium, and the rest lithium still exists in the waste material, which not only causes resource waste, but also affects the environment.
Disclosure of Invention
The invention aims to overcome the defect of lower lithium yield when the existing method is used for recovering lithium from waste lithium iron phosphate battery positive electrode waste powder, and provides a method for recovering lithium from the waste lithium iron phosphate battery positive electrode waste powder, which can improve the lithium yield.
After intensive and extensive researches, the inventor of the invention finds that the prior art generally adopts a chemical precipitation mode to remove copper and aluminum from the waste anode powder of the waste lithium iron phosphate battery so as to realize the recovery of lithium, but the recovery rate of the lithium generally only reaches about 90 percent, and the main reason is that lithium is entrained in copper-aluminum slag, so that lithium loss is caused; dispersing the lithium-containing copper-aluminum slag in water, sequentially aging, acid-dissolving and filtering the obtained slurry, and then electrolyzing the obtained lithium-containing copper-rich liquid to obtain a lithium-containing copper-poor liquid, wherein the lithium-containing copper-poor liquid is returned to the lithium-dissolving liquid for cyclic treatment, so that lithium in the lithium-containing copper slag can be effectively recovered. Based on this, the present invention has been completed.
Specifically, the method for recovering lithium from the lithium iron phosphate battery positive electrode waste powder provided by the invention comprises the following steps:
s1, selectively dissolving lithium from waste anode powder of a lithium iron phosphate battery to obtain a lithium dissolution solution and iron phosphate slag;
s2, removing copper and aluminum impurities from the lithium leaching solution to obtain a lithium purifying solution and lithium-containing copper and aluminum slag;
s3, precipitating and separating lithium from the lithium purification liquid; dispersing the lithium-containing copper aluminum slag in water, and then sequentially aging, acid-dissolving and filtering the obtained slurry to obtain Al (OH) 3 And electrolyzing the lithium-containing copper-rich liquid to obtain the lithium-containing copper-poor liquid and metallic copper, and returning the lithium-containing copper-poor liquid to the lithium dissolution liquid for cyclic treatment.
In a preferred embodiment, in step S1, the method for selectively leaching lithium from the lithium iron phosphate battery positive electrode waste powder includes solid-liquid separation after the lithium iron phosphate battery positive electrode waste powder is subjected to a common impregnation treatment by an acid solution and an oxidant.
In a preferred embodiment, in step S1, the acid solution is a sulfuric acid solution.
In a preferred embodiment, in step S1, the sulfuric acid solution has a concentration of 10 to 30wt%.
In a preferred embodiment, in step S1, the sulfuric acid solution is used in an amount such that the pH of the system is between 1.5 and 4.0.
In a preferred embodiment, in step S1, the oxidizing agent is hydrogen peroxide.
In a preferred embodiment, in step S1, the hydrogen peroxide and Fe in the lithium iron phosphate battery positive electrode waste powder 2+ The molar ratio of (2) is 0.6-1.0.
In a preferred embodiment, in step S2, the method for removing copper and aluminum impurities from the lithium dissolution solution comprises solid-liquid separation after adjusting the pH value of the lithium dissolution solution to 4.0 to 10.0.
In a preferred embodiment, in step S3, the method for precipitating and separating lithium from the lithium purification liquid comprises concentrating the lithium purification liquid to a concentration of 10g/L or more, and then adding CO to the concentrated liquid 2 And/or Na 2 CO 3 So that lithium is as Li 2 CO 3 Precipitating the form or adding Na to the concentrate 3 PO 4 So that lithium is as Li 3 PO 4 The form precipitates out.
In a preferred embodiment, in step S3, the lithium-containing copper aluminum slag is dispersed in water in such an amount that the solid content of the resulting slurry is 15 to 50wt%.
In a preferred embodiment, in step S3, the aging conditions include a temperature of 30 to 100 ℃ for a time of 1 to 5 hours.
In a preferred embodiment, in step S3, the acid solution used for the acid dissolution is a sulfuric acid solution and/or a nitric acid solution; h in the acid solution + And Cu in the lithium-containing copper aluminum slag 2+ The molar ratio of (2.4-4.0): 1.
In a preferred embodiment, in step S3, the electrolysis conditions include copper as a cathode, graphite or titanium as an anode, and a current density of 0.1 to 1.0A/dm 2 The electrolysis time is 10 min-2 h.
In a preferred embodiment, the method for recovering lithium from the lithium iron phosphate battery positive electrode waste powder further comprises the step of carrying out tail liquid treatment on the tail liquid obtained after lithium is precipitated and separated from the lithium purification liquid to remove sodium salt, and returning the obtained lithium-rich liquid to the lithium dissolution liquid for recycling treatment.
In a preferred embodiment, the tail liquid treatment method is a thermal method or a membrane method.
The method provided by the invention can further eliminate lithium loss caused by removing copper and aluminum impurities by precipitation on the basis of recovering lithium by adopting chemical precipitation, realizes effective recovery of lithium, and has great application prospect. In addition, the method for recycling lithium from the lithium iron phosphate battery positive electrode waste powder provided by the invention can be used for additional auxiliaryCopper and Al (OH) producing metal 3 The effective utilization of resources is realized.
Drawings
Fig. 1 is a schematic diagram showing the recovery of lithium from lithium iron phosphate battery positive electrode waste powder according to the present invention.
Detailed Description
As shown in fig. 1, the method for recovering lithium from lithium iron phosphate battery positive electrode waste powder provided by the invention comprises the following steps:
s1, selectively dissolving lithium from waste anode powder of a lithium iron phosphate battery to obtain a lithium dissolution solution and iron phosphate slag;
s2, removing copper and aluminum impurities from the lithium leaching solution to obtain a lithium purifying solution and lithium-containing copper and aluminum slag;
s3, precipitating and separating lithium from the lithium purification liquid; dispersing the lithium-containing copper aluminum slag in water, and then sequentially aging, acid-dissolving and filtering the obtained slurry to obtain Al (OH) 3 And electrolyzing the lithium-containing copper-rich liquid to obtain the lithium-containing copper-poor liquid and metallic copper, and returning the lithium-containing copper-poor liquid to the lithium dissolution liquid for cyclic treatment.
In a preferred embodiment, in step S1, the method for selectively leaching lithium from the lithium iron phosphate battery positive electrode waste powder includes solid-liquid separation after the lithium iron phosphate battery positive electrode waste powder is subjected to a common impregnation treatment by an acid solution and an oxidant. The acid solution may be at least one of sulfuric acid solution, hydrochloric acid solution, phosphoric acid solution and nitric acid solution, and is preferably sulfuric acid solution. The concentration of the sulfuric acid solution is preferably 10 to 30wt%, such as 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, or any value therebetween. The sulfuric acid solution is preferably used in such an amount that the pH of the system is 1.5 to 4.0, and the specific pH may be 1.5, 2.5, 3.5, 4.0 or any value in between. The oxidant is preferably hydrogen peroxide. The dosage of the hydrogen peroxide is H 2 O 2 /Fe 2+ The molar ratio is preferably 0.6 to 1.0, namely H in hydrogen peroxide 2 O 2 Fe in the waste powder of the positive electrode of the lithium iron phosphate battery 2+ The molar ratio of (2) is 0.6-1.0, such as 0.6, 0.7, 0.8, 0.9, 1.0 or any value therebetween.
In a preferred embodiment, in step S2, the method for removing copper and aluminum impurities from the lithium dissolution solution includes solid-liquid separation after adjusting the pH of the lithium dissolution solution to 4.0 to 10.0, and the specific pH may be 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0 or any value therebetween. After the pH value is regulated to 4.0-10.0, copper and aluminum in the lithium leaching solution can be precipitated in the form of hydroxide, and the lithium purification solution and lithium-containing copper-aluminum slag can be obtained after solid-liquid separation. The pH may be adjusted to 4.0 to 10.0 by adding, for example, an acid solution or an alkali solution to the system, wherein the acid solution may be at least one of sulfuric acid solution, hydrochloric acid solution, phosphoric acid solution, nitric acid solution, etc., and the alkali solution may be at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, ammonia water, etc.
In the present invention, in step S3, the method of precipitating and separating lithium from the lithium purification liquid may be, for example, adding CO directly to the lithium purification liquid 2 、Na 2 CO 3 、Na 3 PO 4 To precipitate lithium, but at this time lithium deposition efficiency is low. In a preferred form, the method for precipitation separation of lithium from the lithium purification liquid comprises concentrating the lithium purification liquid to a concentration of above 10g/L, and adding CO to the concentrate 2 And/or Na 2 CO 3 So that lithium is as Li 2 CO 3 Precipitating the form or adding Na to the concentrate 3 PO 4 So that lithium is as Li 3 PO 4 The form precipitates out. The inventors of the present invention found that concentration of the lithium purified solution to a concentration of 10g/L or more, specifically to 10g/L, 12g/L, 14g/L, 16g/L, 18g/L, 20g/L, 22g/L, 24g/L, 26g/L, 28g/L, 30g/L or any value therebetween, can be performed before precipitation, and at this time, the lithium deposition efficiency can be remarkably improved. In addition, with Na 3 PO 4 The efficiency of lithium precipitation as a precipitant is significantly higher than that of CO 2 And/or Na 2 CO 3 The efficiency of lithium precipitation as a precipitant.
In the invention, the content of lithium in the lithium-containing copper-aluminum slag is related to the content of copper and aluminum impurities in the waste powder of the positive electrode of the lithium iron phosphate battery, and the higher the impurity content isWhen the pH value is regulated and controlled to precipitate copper and aluminum, the higher the lithium amount adsorbed by the slag is, and the slag becomes high-lithium-content copper-aluminum slag; if lithium in the copper aluminum slag is not recovered, the lithium yield can be obviously reduced, and the waste of high-value lithium metal is caused. In order to recover lithium from the lithium-containing copper slag, the lithium-containing copper aluminum slag is dispersed in water, and the obtained slurry is aged, acid-dissolved and filtered in sequence to obtain Al (OH) 3 And electrolyzing the lithium-containing copper-rich liquid to obtain the lithium-containing copper-poor liquid and metallic copper, and returning the lithium-containing copper-poor liquid to the lithium dissolution liquid for cyclic treatment. Wherein, when the lithium-containing copper aluminum slag is dispersed in water, the water is preferably used in such an amount that the solid content of the resulting slurry is 15 to 50wt%, such as 15wt%, 20wt%, 30wt%, 40wt%, 50wt%, or any value therebetween. The aging conditions preferably include a temperature of 30 to 100 ℃, such as 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃,90 ℃, 100 ℃, or any value therebetween; the time is 1-5 h, such as 1h, 2h, 3h, 4h, 5h or any value between them. The acid solution used for the acid dissolution can be sulfuric acid solution and/or nitric acid solution. The dosage of the acid liquor is H + /Cu 2+ The molar ratio is preferably 2.4 to 4.0, i.e. H in the acid solution + And Cu in lithium copper aluminum slag 2+ The molar ratio of (2) is preferably 2.4 to 4.0, such as 2.4, 3.0, 3.5, 4.0 or any value therebetween. The conditions of the electrolysis preferably include copper as a cathode; graphite or titanium is used as an anode; the current density is 0.1-1.0A/dm 2 Such as 0.1A/dm 2 、0.2A/dm 2 、0.5A/dm 2 、0.75A/dm 2 、1.0A/dm 2 Or any value therebetween; the electrolysis time is 10 min-2 h, such as 10min, 30min, 1h, 1.5h, 2h or any value between them. The electrolytic treatment can convert the lithium-containing copper-rich solution into a lithium-containing copper-depleted solution, and the lithium-containing copper-depleted solution can be returned to the lithium dissolution solution for recycling treatment. After electrolysis, 85-98% of Cu is deposited on the cathode in a metal form, and the ratio of the deposition yield of Cu in the metal form to the total Cu amount is the Cu deposition rate. The Cu deposition rate is related to the concentration of the lithium-containing copper-rich liquid, when the Cu concentration in the lithium-containing copper-rich liquid is as high as 2000ug/mL, the Cu content can be reduced to 200ug/mL after electrolysis, and 90% of Cu is deposited on the cathode in a metal form; when (when)When the lithium-containing copper-rich solution is concentrated to a Cu content of 5000ug/mL or more, about 96% of Cu is deposited as metal on the cathode.
In a preferred embodiment, the method for recovering lithium from the lithium iron phosphate battery positive electrode waste powder further comprises the step of carrying out tail liquid treatment on the tail liquid obtained after lithium is precipitated and separated from the lithium purification liquid, and returning the obtained lithium-rich liquid to the lithium dissolution liquid for recycling treatment. Wherein the tail liquid treatment method mainly comprises desalting treatment, i.e. salt (such as Na) 2 SO 4 The sodium salts, etc.), the removal method may specifically be a thermal method or a membrane method, and is specifically known to those skilled in the art, and will not be described herein.
The present invention will be described in detail by examples.
In the following examples and comparative examples, lithium recovery was calculated according to the following formula:
lithium recovery = (m1+m2)/(m-m') ×100%
Wherein m1 is the amount of lithium species in the recovered lithium salt; m2 is the amount of lithium species in the lithium-containing copper-depleted solution; m is the amount of lithium substance in the lithium iron phosphate battery positive electrode waste powder; m' is the amount of lithium species in the tail solution. The content of Li is determined according to the lithium content detection method specified in national standard GB/T30835-2014 carbon for lithium ion batteries conforming to lithium iron phosphate cathode material.
Example 1 this example is illustrative of the method for recovering lithium from lithium iron phosphate battery positive electrode waste powder provided by the present invention
S1, adding hydrogen peroxide with the concentration of 27.5% and sulfuric acid solution with the concentration of 20wt% into lithium iron phosphate battery positive electrode waste powder, uniformly stirring, and standing for 3 hours to obtain a lithium dissolution solution and iron phosphate slag, wherein the dosage of the sulfuric acid solution is based on the pH value of a system of 3.0, and the dosage of the hydrogen peroxide is equal to Fe in the lithium iron phosphate battery positive electrode waste powder 2+ The molar ratio of (2) was 1.0.
S2, adjusting the pH value of the lithium leaching solution to 8.0, and then carrying out solid-liquid separation to obtain lithium purification liquid and lithium-containing copper aluminum slag.
S3, concentrating the lithium purified solution until the concentration reaches 18g/L, and thenAdding Na into the concentrated solution 3 PO 4 So that lithium is as Li 3 PO 4 And precipitating in a form to obtain lithium salt (Li salt), desalting the obtained tail liquid by adopting a membrane method to remove sodium salt to obtain a lithium-rich liquid, and returning the lithium-rich liquid to the lithium dissolution liquid for recycling treatment. Dispersing lithium-containing copper aluminum slag in water to obtain slurry with solid content of 25wt%, aging at 30deg.C for 5 hr, adding sulfuric acid solution with concentration of 15wt% into the system, acid dissolving for 30min, and adding sulfuric acid solution according to the amount of H + Counting Cu in lithium-containing copper aluminum slag 2+ The molar ratio of (2) is 3.2, and filtering is carried out after the acid dissolution is completed to obtain Al (OH) 3 A lithium-containing copper-rich solution. Electrolyzing the lithium-containing copper-rich liquid, wherein copper is used as a cathode, graphite or titanium is used as an anode in the electrolysis process, and the current density is controlled to be 0.5A/dm 2 And (3) electrolyzing for 1h to obtain a lithium-containing copper-depleted solution and metallic copper, wherein the lithium-containing copper-depleted solution is returned to the lithium dissolution solution for cyclic treatment. The total recovery of lithium was 95.8%.
Example 2 this example is illustrative of the method for recovering lithium from lithium iron phosphate battery positive electrode waste powder provided by the present invention
S1, adding hydrogen peroxide with the concentration of 27.5% and sulfuric acid solution with the concentration of 30wt% into lithium iron phosphate battery positive electrode waste powder, uniformly stirring, and standing for 0.5h to obtain a lithium dissolution solution and iron phosphate slag, wherein the dosage of the sulfuric acid solution is based on the pH value of a system of 4, and the dosage of the hydrogen peroxide is equal to the dosage of Fe in the lithium iron phosphate battery positive electrode waste powder 2+ The molar ratio of (2) was 0.6.
S2, adjusting the pH value of the lithium leaching solution to 6.0, and then carrying out solid-liquid separation to obtain lithium purification liquid and lithium-containing copper aluminum slag.
S3, concentrating the lithium purified solution until the concentration reaches 12g/L, and then adding CO into the concentrated solution 2 So that lithium is as Li 2 CO 3 And precipitating in a form to obtain lithium salt (Li salt), desalting the obtained tail liquid by adopting a membrane method to remove sodium salt to obtain a lithium-rich liquid, and returning the lithium-rich liquid to the lithium dissolution liquid for recycling treatment. Dispersing the lithium-containing copper aluminum slag in water to obtain slurry with the solid content of 15wt%, aging the slurry at 80 ℃ for 3 hours, and adding sulfuric acid with the concentration of 25wt% into the systemAcid-dissolving the solution for 45min, and the dosage of sulfuric acid solution is H + Counting Cu in lithium-containing copper aluminum slag 2+ The molar ratio of (2) is 4.0, and filtering is carried out after the acid dissolution is completed to obtain Al (OH) 3 A lithium-containing copper-rich solution. Electrolyzing the lithium-containing copper-rich liquid, wherein copper is used as a cathode, graphite or titanium is used as an anode in the electrolysis process, and the current density is controlled to be 0.1A/dm 2 And (3) electrolyzing for 2 hours to obtain a lithium-containing copper-depleted solution and metallic copper, wherein the lithium-containing copper-depleted solution is returned to the lithium dissolution solution for cyclic treatment. The total recovery of lithium was 94.8%.
Example 3 this example is illustrative of the method for recovering lithium from lithium iron phosphate battery positive electrode waste powder provided by the present invention
S1, adding hydrogen peroxide with the concentration of 27.5% and sulfuric acid solution with the concentration of 10wt% into lithium iron phosphate battery positive electrode waste powder, uniformly stirring, and standing for 2 hours to obtain a lithium dissolution solution and iron phosphate slag, wherein the dosage of the sulfuric acid solution is based on the pH value of a system being 2.0, and the dosage of the hydrogen peroxide is equal to Fe in the lithium iron phosphate battery positive electrode waste powder 2+ The molar ratio of (2) was 0.8.
S2, adjusting the pH value of the lithium leaching solution to 10, and then carrying out solid-liquid separation to obtain a lithium purifying solution and lithium-containing copper aluminum slag.
S3, concentrating the lithium purified solution until the concentration reaches 22g/L, and then adding Na into the concentrated solution 2 CO 3 So that lithium is as Li 2 CO 3 And precipitating in a form to obtain lithium salt (Li salt), desalting the obtained tail liquid by adopting a membrane method to remove sodium salt to obtain a lithium-rich liquid, and returning the lithium-rich liquid to the lithium dissolution liquid for recycling treatment. Dispersing lithium-containing copper aluminum slag in water to obtain slurry with solid content of 20wt%, aging the slurry at 50deg.C for 4 hr, adding 10wt% sulfuric acid solution into the system for acid dissolution for 60min, and mixing the sulfuric acid solution with the amount of H + Counting Cu in lithium-containing copper aluminum slag 2+ The molar ratio of (2) is 2.4, and filtering is carried out after the acid dissolution is completed to obtain Al (OH) 3 A lithium-containing copper-rich solution. Electrolyzing the lithium-containing copper-rich liquid, wherein copper is used as a cathode, graphite or titanium is used as an anode in the electrolysis process, and the current density is controlled to be 1.0A/dm 2 Electrolyzing for 30min to obtain a lithium-containing copper-depleted solution and metallic copper, wherein the lithium-containing copper-depleted solution is returned to the lithium dissolutionAnd (5) circulating treatment in the liquid. The total recovery of lithium was 95.3%.
Example 4 this example is illustrative of the method for recovering lithium from lithium iron phosphate battery positive electrode waste powder provided by the present invention
Lithium was recovered from lithium iron phosphate battery positive electrode waste powder in the same manner as in example 1, except that in step S3, na was added 3 PO 4 The same weight part of Na is adopted 2 CO 3 Instead, the remaining conditions were the same as in example 1. The results showed that the total recovery of lithium was 94.5%.
Example 5 this example is illustrative of the method for recovering lithium from lithium iron phosphate battery positive electrode waste powder provided by the present invention
Lithium was recovered from the lithium iron phosphate battery positive electrode waste powder in the same manner as in example 1, except that in the process of precipitating and separating lithium from the lithium purification liquid in step S3, the lithium purification liquid was not concentrated but directly added with Na 3 PO 4 So that lithium is as Li 3 PO 4 The form precipitated and the rest of the conditions were the same as in example 1. The results showed that the total recovery of lithium was 95.0%.
Comparative example 1 this example is intended to illustrate a reference method for recovering lithium from lithium iron phosphate battery positive electrode waste powder
Lithium was recovered from the positive electrode waste powder of a lithium iron phosphate battery in the same manner as in example 1, except that the step of recovering lithium from the lithium-containing copper-aluminum slag was not included, and the other conditions were the same as in example 1. The results showed that the total recovery of lithium was 91.0%.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations may be made in the above embodiments by those skilled in the art without departing from the spirit and principles of the invention.
Claims (10)
1. A method for recovering lithium from lithium iron phosphate battery positive electrode waste powder, which is characterized by comprising the following steps:
s1, selectively dissolving lithium from waste anode powder of a lithium iron phosphate battery to obtain a lithium dissolution solution and iron phosphate slag;
s2, removing copper and aluminum impurities from the lithium leaching solution to obtain a lithium purifying solution and lithium-containing copper and aluminum slag;
s3, precipitating and separating lithium from the lithium purification liquid; dispersing the lithium-containing copper aluminum slag in water, and then sequentially aging, acid-dissolving and filtering the obtained slurry to obtain Al (OH) 3 And electrolyzing the lithium-containing copper-rich liquid to obtain the lithium-containing copper-poor liquid and metallic copper, and returning the lithium-containing copper-poor liquid to the lithium dissolution liquid for cyclic treatment.
2. The method for recovering lithium from lithium iron phosphate battery positive electrode waste powder according to claim 1, wherein in the step S1, the method for selectively dissolving lithium from the lithium iron phosphate battery positive electrode waste powder comprises the steps of subjecting the lithium iron phosphate battery positive electrode waste powder to co-impregnation treatment by an acid solution and an oxidant, and then carrying out solid-liquid separation;
preferably, the acid solution is a sulfuric acid solution;
preferably, the concentration of the sulfuric acid solution is 10-30wt%;
preferably, the sulfuric acid solution is used in an amount such that the pH of the system is between 1.5 and 4.0;
preferably, the oxidant is hydrogen peroxide;
preferably, fe in the hydrogen peroxide and the waste anode powder of the lithium iron phosphate battery 2+ The molar ratio of (2) is 0.6-1.0.
3. The method for recovering lithium from lithium iron phosphate battery positive electrode waste powder according to claim 1, wherein in the step S2, the method for removing copper and aluminum impurities from the lithium dissolution solution comprises solid-liquid separation after adjusting the pH value of the lithium dissolution solution to 4.0 to 10.0.
4. The method for recovering lithium from lithium iron phosphate battery positive electrode waste powder as claimed in claim 1, wherein in step S3, the method for precipitating and separating lithium from the lithium purification liquid comprises concentrating the lithium purification liquid to a concentration of 10g/L or more, and concentratingCO is added into the liquid 2 And/or Na 2 CO 3 So that lithium is as Li 2 CO 3 Precipitating the form or adding Na to the concentrate 3 PO 4 So that lithium is as Li 3 PO 4 The form precipitates out.
5. The method for recovering lithium from lithium iron phosphate battery positive electrode waste powder according to claim 1, wherein in step S3, when the lithium-containing copper aluminum slag is dispersed in water, the amount of water is such that the solid content of the obtained slurry is 15 to 50wt%.
6. The method for recovering lithium from lithium iron phosphate battery positive electrode waste powder according to claim 1, wherein in the step S3, the aging condition includes a temperature of 30 to 100 ℃ for 1 to 5 hours.
7. The method for recovering lithium from lithium iron phosphate battery positive electrode waste powder according to claim 1, wherein in the step S3, the acid solution used for the acid dissolution is sulfuric acid solution and/or nitric acid solution; h in the acid solution + And Cu in the lithium-containing copper aluminum slag 2+ The molar ratio of (2) to (4) 0.
8. The method for recovering lithium from lithium iron phosphate battery positive electrode waste powder according to claim 1, wherein in step S3, the electrolysis conditions include copper as a cathode, graphite or titanium as an anode, and a current density of 0.1 to 1.0A/dm 2 The electrolysis time is 10 min-2 h.
9. The method for recovering lithium from lithium iron phosphate battery positive electrode waste powder according to claim 1, further comprising the step of subjecting a tail liquid obtained after precipitation and separation of lithium from a lithium purification liquid to tail liquid treatment to remove sodium salt, and returning the obtained lithium-rich liquid to a lithium dissolution liquid for recycling treatment.
10. The method for recovering lithium from lithium iron phosphate battery positive electrode waste powder according to claim 9, wherein the tail liquid treatment method is a thermal method or a membrane method.
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