CN115692907A - Method for removing copper and aluminum from lithium iron phosphate waste - Google Patents
Method for removing copper and aluminum from lithium iron phosphate waste Download PDFInfo
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- CN115692907A CN115692907A CN202211364260.8A CN202211364260A CN115692907A CN 115692907 A CN115692907 A CN 115692907A CN 202211364260 A CN202211364260 A CN 202211364260A CN 115692907 A CN115692907 A CN 115692907A
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- leaching
- copper
- aluminum
- iron phosphate
- lithium
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- 239000010949 copper Substances 0.000 title claims abstract description 167
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 154
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 154
- 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 96
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 87
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 239000002699 waste material Substances 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title claims abstract description 66
- 238000002386 leaching Methods 0.000 claims abstract description 211
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 173
- 239000000243 solution Substances 0.000 claims abstract description 46
- 239000002253 acid Substances 0.000 claims abstract description 39
- 235000021110 pickles Nutrition 0.000 claims abstract description 39
- 230000002378 acidificating effect Effects 0.000 claims abstract description 25
- 230000008569 process Effects 0.000 claims abstract description 21
- 230000001590 oxidative effect Effects 0.000 claims abstract description 18
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 13
- 230000001681 protective effect Effects 0.000 claims abstract description 10
- 239000012670 alkaline solution Substances 0.000 claims abstract description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 25
- 239000007789 gas Substances 0.000 claims description 18
- 239000007787 solid Substances 0.000 claims description 17
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 12
- 239000003513 alkali Substances 0.000 claims description 12
- 229910052757 nitrogen Inorganic materials 0.000 claims description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 8
- 150000007522 mineralic acids Chemical class 0.000 claims description 8
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 4
- 229910002651 NO3 Inorganic materials 0.000 claims description 4
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 4
- 229960002089 ferrous chloride Drugs 0.000 claims description 4
- 239000011790 ferrous sulphate Substances 0.000 claims description 4
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 4
- 239000001257 hydrogen Substances 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 4
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical group [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 4
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 4
- 229910017604 nitric acid Inorganic materials 0.000 claims description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 3
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 1
- 229910052744 lithium Inorganic materials 0.000 abstract description 100
- 229910052742 iron Inorganic materials 0.000 abstract description 93
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 90
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 71
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 abstract description 59
- 239000011574 phosphorus Substances 0.000 abstract description 59
- 238000011084 recovery Methods 0.000 abstract description 16
- 239000012298 atmosphere Substances 0.000 abstract description 15
- 229910052751 metal Inorganic materials 0.000 abstract description 11
- 239000002184 metal Substances 0.000 abstract description 11
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 abstract description 10
- 239000005751 Copper oxide Substances 0.000 abstract description 9
- 229910000431 copper oxide Inorganic materials 0.000 abstract description 9
- 230000003647 oxidation Effects 0.000 abstract description 8
- 238000007254 oxidation reaction Methods 0.000 abstract description 8
- 238000004090 dissolution Methods 0.000 abstract description 7
- 230000009286 beneficial effect Effects 0.000 abstract description 4
- 150000002739 metals Chemical class 0.000 abstract description 3
- 230000009467 reduction Effects 0.000 abstract description 3
- 239000010926 waste battery Substances 0.000 abstract description 2
- 230000005764 inhibitory process Effects 0.000 abstract 1
- 239000000463 material Substances 0.000 description 44
- 230000000052 comparative effect Effects 0.000 description 30
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 28
- 239000011737 fluorine Substances 0.000 description 28
- 229910052731 fluorine Inorganic materials 0.000 description 28
- 238000006115 defluorination reaction Methods 0.000 description 25
- 239000002994 raw material Substances 0.000 description 23
- 238000002441 X-ray diffraction Methods 0.000 description 15
- 239000000126 substance Substances 0.000 description 10
- 230000002829 reductive effect Effects 0.000 description 9
- 238000005406 washing Methods 0.000 description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000012535 impurity Substances 0.000 description 8
- 239000002893 slag Substances 0.000 description 8
- 230000008901 benefit Effects 0.000 description 7
- 238000001354 calcination Methods 0.000 description 7
- 238000004064 recycling Methods 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 6
- 229910021641 deionized water Inorganic materials 0.000 description 6
- 239000003792 electrolyte Substances 0.000 description 6
- 238000001914 filtration Methods 0.000 description 6
- 238000003756 stirring Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 238000003723 Smelting Methods 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 229910002804 graphite Inorganic materials 0.000 description 4
- 239000010439 graphite Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 239000005749 Copper compound Substances 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 150000001880 copper compounds Chemical class 0.000 description 3
- 239000011889 copper foil Substances 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- GNTCPDPNMAMZFW-UHFFFAOYSA-N ferrous phosphide Chemical compound [Fe]=P#[Fe] GNTCPDPNMAMZFW-UHFFFAOYSA-N 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052756 noble gas Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- JJLJMEJHUUYSSY-UHFFFAOYSA-L Copper hydroxide Chemical compound [OH-].[OH-].[Cu+2] JJLJMEJHUUYSSY-UHFFFAOYSA-L 0.000 description 1
- 239000005750 Copper hydroxide Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910018119 Li 3 PO 4 Inorganic materials 0.000 description 1
- 229910012425 Li3Fe2 (PO4)3 Inorganic materials 0.000 description 1
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 229910001956 copper hydroxide Inorganic materials 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910001386 lithium phosphate Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 150000002835 noble gases Chemical class 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Images
Classifications
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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
-
- 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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- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a method for removing copper and aluminum from lithium iron phosphate waste, belonging to the field of waste battery recovery, comprising the following steps: roasting: roasting the waste under a non-oxidizing gas; alkaline leaching: leaching the roasted waste material with an alkaline solution to obtain alkaline leaching residue; in the alkaline leaching process, protective gas is introduced or a reducing agent is added; acid leaching: and leaching the alkaline leaching residue by using an acid solution to obtain a pickle liquor. The method can inhibit the oxidation of elemental copper and promote the reduction of copper oxide into elemental copper by roasting in a non-oxidizing atmosphere, thereby being beneficial to the subsequent inhibition of the dissolution of copper and improving the leaching selectivity; when the method is matched with alkaline leaching, protective gas is introduced or a reducing agent is added to further inhibit the dissolution of metal copper, so that the whole process of the metal copper is maintained in an elemental state, the leaching rate of iron, lithium and phosphorus is improved during acidic leaching to reduce the leaching rate of copper, and finally, the aluminum and the copper are deeply separated from the iron, the lithium and the phosphorus, the purity of a pickle liquor is improved, and the comprehensive recovery rate of valuable metals can be improved.
Description
Technical Field
The invention relates to a method for removing copper and aluminum from a lithium iron phosphate waste material, belonging to the field of waste battery recovery.
Background
The lithium iron phosphate battery has the advantages of high working voltage, high stability, long cycle life, good safety performance and the like, and is one of the most important matched battery systems of new energy automobiles. From 2014, the new energy steam production and sales volume in China are rapidly increased and still vigorously developed at present, the service life of the lithium iron phosphate battery is about 6 years to 10 years, and a large amount of production and use means a large amount of waste in the future.
The existing waste lithium iron phosphate battery treatment process comprises battery pretreatment and recovery of valuable components in various materials (electrolyte, lithium iron phosphate anode waste materials and the like), and the process is very challenging. The pretreatment of the battery comprises battery discharge, electrolyte collection, shelling, battery core disassembly, separation of graphite and copper foil on a negative plate, and separation of lithium iron phosphate materials and aluminum foil on a positive plate.
The energy consumption of the treatment technology for recycling the waste lithium iron phosphate batteries is high, the smelting process is complex, and the smelting recycling is difficult to realize effective economic benefits. In order to improve the recovery benefits and shorten the recovery process of the waste lithium iron phosphate batteries, most battery recovery units directly crush discharged batteries or crush battery cells with shells removed to obtain lithium iron phosphate waste, and then recover elements such as Li, fe and the like from the waste. Although the treatment efficiency is higher, the problems of difficult removal of impurities such as copper and aluminum, large loss of lithium and iron and the like are also caused.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a method for removing copper and aluminum from a lithium iron phosphate waste material, which can still deeply remove copper and aluminum from the lithium iron phosphate waste material under fewer pretreatment steps.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a method for removing copper and aluminum from lithium iron phosphate waste comprises the following steps:
roasting: roasting the waste under a non-oxidizing gas;
alkaline leaching: leaching the roasted waste material with an alkaline solution to obtain alkaline leaching residue; in the alkaline leaching process, at least one of two protection conditions of introducing protective gas and adding a reducing agent is adopted for protection;
acid leaching: and leaching the alkaline leaching residue by using an inorganic acid solution to obtain an acid leaching solution.
The method for removing copper and aluminum from the lithium iron phosphate waste is suitable for the directly crushed lithium iron phosphate battery, the crushed battery core after the shell of the lithium iron phosphate battery is removed, and the waste obtained after the lithium iron phosphate electrode containing at least one impurity of copper and aluminum is crushed.
The method for removing copper and aluminum from the lithium iron phosphate waste provided by the application can efficiently remove copper and aluminum impurities, and is also beneficial to simplifying the overall recovery process of the waste lithium iron phosphate battery, improving the pretreatment efficiency of the battery and improving the comprehensive recovery rate of valuable elements such as lithium, iron and copper.
In some preferred embodiments, the non-oxidizing gas comprises at least one of hydrogen, carbon monoxide, nitrogen, noble gases. The roasting has the function of removing residual electrolyte in the raw materials, so that fluorine elements are prevented from entering a system in the subsequent leaching process, and the environmental pollution and the smelting cost are reduced. Meanwhile, the inert atmosphere or the nitrogen atmosphere during roasting can protect elemental copper from being oxidized at high temperature, copper oxide can be reduced into copper elemental substance through carbothermic reaction, the elemental copper is maintained in an elemental state in the whole process by matching with a protection means during alkaline leaching, the dissolution of copper during subsequent acidic leaching is inhibited, and the leaching selectivity is improved. When the non-oxidizing gas contains hydrogen or carbon monoxide, the reaction of copper compounds in the raw materials is more facilitated to generate elemental copper, and the leaching selectivity is further improved.
In some preferred embodiments, the protective gas comprises at least one of nitrogen and a noble gas.
In some preferred embodiments, the reducing agent is selected from the group consisting of ferrous sulfate, ferrous nitrate, ferrous chloride, and iron powder. The protective gas is introduced during alkaline leaching to effectively inhibit the oxidation of metal copper, and if a reducing agent is added, the oxidation of elemental copper can be further inhibited or the reduction of valuable copper into elemental copper can be promoted, so that the selectivity of subsequent acidic leaching is improved, and the leaching rates of iron, lithium and phosphorus during subsequent acidic leaching are improved to reduce the leaching rate of copper. The amount of the reducing agent added is 1.0 to 2.0 times the total molar amount of copper in the roasted scrap.
In some preferred embodiments, the calcination temperature is 300 ℃ to 800 ℃ and the calcination time is 1h to 9h, and the shorter the calcination time, the higher the calcination temperature is required. If the roasting temperature is too high, the volatilization loss of lithium element can be caused; meanwhile, lithium iron phosphate reacts with carbon to generate ferrous phosphide and lithium phosphate, and the ferrous phosphide is easy to be incompletely leached during acid leaching, so that iron loss is caused.
In some preferred embodiments, the alkaline solution is at least one selected from sodium hydroxide and potassium hydroxide, and the concentration of OH used in alkaline leaching is 1mol/L-3mol/L - An alkali solution of (2). If the dosage of the alkali solution is too high or the concentration is too high or the alkaline leaching time is too long, the final lithium element loss is more.
In some preferred embodiments, the alkaline leaching has a liquid-solid ratio of 9.0-17.3: 1.0 and an alkaline leaching time of 1-3 hours.
In some preferred embodiments, the treatment temperature of the alkaline leach is from 20 ℃ to 60 ℃.
In some preferred embodiments, the inorganic acid solution is at least one selected from sulfuric acid, hydrochloric acid and nitric acid, and the inorganic acid solution is used in acidic leaching and contains 1mol/L-5.6mol/L H + The inorganic acid solution of (2).
In some preferred embodiments, the liquid-solid ratio of the acidic leaching is 11.7-24.8: 1.0, and the acidic leaching time is 1-4 h.
In some preferred embodiments, the treatment temperature of the acidic leach is from 20 ℃ to 60 ℃. The temperature of the acidic leaching process should not be too high, otherwise it may cause the dissolution of traces of copper into the solution by oxidation. In order to increase the leaching rate, when higher leaching temperatures are used, the copper can be prevented from oxidizing leaching into the solution by adding a reducing agent, introducing an inert gas or introducing a reducing gas, but care is taken to avoid introducing new impurities into the pickle liquor.
The beneficial effects of the invention are: the method for removing copper and aluminum from the lithium iron phosphate waste adopts a non-oxidizing atmosphere roasting-alkaline leaching-acidic leaching process, can treat the lithium iron phosphate waste by fewer pretreatment steps, inhibits the oxidation of elemental copper and promotes the reduction of copper oxide into elemental copper in the non-oxidizing atmosphere, is favorable for inhibiting the dissolution of copper subsequently, and improves the leaching selectivity; and protective gas is introduced or a reducing agent is added to further inhibit the oxidation of metal copper when alkaline leaching is matched, so that the whole process of elemental copper is maintained in an elemental state, the leaching rate of iron, lithium and phosphorus is improved during acid leaching, the leaching rate of copper is reduced, finally, aluminum and copper are deeply separated from iron, lithium and phosphorus, the purity of pickle liquor is improved, and the comprehensive recovery rate of valuable metals can be improved.
Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the application. The objectives and other advantages of the application may be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
FIG. 1 is an XRD analysis pattern of the calcine of example 4.
FIG. 2 is an XRD analysis pattern of the calcined material of comparative example 1.
Fig. 3 is an XRD analysis pattern of the lithium iron phosphate waste 3.
FIG. 4 is an XRD analysis pattern of the acid leaching residue of example 5.
FIG. 5 is an XRD analysis pattern of the acid-leached residue of comparative example 2.
Fig. 6 is an XRD analysis pattern of the calcined material of comparative example 4.
FIG. 7 is an XRD analysis pattern of the acid-leached residue of example 19.
FIG. 8 is an XRD analysis pattern of acid-leached residue of comparative example 5.
Fig. 9 is a flowchart of a method for removing copper and aluminum from a lithium iron phosphate scrap according to an embodiment of the present application.
Detailed Description
The battery core of the lithium iron phosphate battery comprises a pole piece, electrolyte, a diaphragm and the like, wherein the negative pole piece is a copper foil coated with graphite, and the positive pole piece is an aluminum foil coated with lithium iron phosphate. The waste lithium iron phosphate battery treatment process comprises the steps of battery pretreatment and recovery of valuable components in various materials, wherein the pretreatment comprises discharging, electrolyte collection, shelling, battery core disassembly, separation of graphite and copper foil on a negative electrode piece, separation of a lithium iron phosphate material and aluminum foil on a positive electrode piece, and then recovery of graphite, copper, aluminum, phosphorus, iron and lithium. The waste lithium iron phosphate battery has long pretreatment process, particularly when small-volume batteries such as 18650 batteries are treated, the pretreatment efficiency is low, the cost is high, and the recovery benefit of the waste lithium iron phosphate battery is seriously reduced. If after discharging, the battery is directly crushed into particles or the whole battery core is crushed into particles after the battery shell is disassembled, and then the valuable components are recovered by a chemical method, so that the recovery process of the waste lithium iron phosphate battery is greatly shortened, and the benefit of recovering the waste lithium iron phosphate battery is favorably improved. However, the existing method for recovering valuable components has the defects of poor removal effect of copper and aluminum impurities, large loss of phosphorus, iron and lithium elements, high energy consumption and the like.
Referring to fig. 9, an embodiment of the present application provides a method for removing copper and aluminum from a lithium iron phosphate waste, where the method is applicable to obtaining a waste after a lithium iron phosphate battery is directly crushed, is applicable to obtaining a waste after a battery cell after a lithium iron phosphate battery case is removed is crushed, and is applicable to crushing a lithium iron phosphate electrode containing at least one impurity among copper and aluminum, and includes the following steps:
s1: roasting: the scrap is calcined under a non-oxidizing gas.
S2: alkaline leaching: leaching the roasted waste material by using an alkali solution to obtain alkali leaching residue.
S3: acid leaching: and leaching the alkaline leaching residue by using an inorganic acid solution to obtain a pickle liquor.
The step S1 has the functions of removing residual electrolyte in the raw materials, preventing fluorine from entering a system in the subsequent leaching process, being beneficial to reducing environmental pollution and smelting cost, simultaneously preventing simple substance copper from being oxidized and reducing copper oxides into simple substance copper, and leaving Cu, al, fe, li and P in a roasting material. And in the step S2, at least one of protective conditions of introducing protective gas and adding a reducing agent is adopted for protection, solid aluminum and aluminum compounds in the step are dissolved into alkaline leaching solution, cu, fe, li and P are left in alkaline leaching residues, and the alkaline leaching solution can be directly used for extracting and recovering aluminum elements. In the step S3, valuable Fe, li and P are dissolved into the pickle liquor, elemental copper is not dissolved and remained in the pickle slag, so that high-purity Fe, li and P pickle liquor is obtained, the pickle liquor can be directly used for extracting and recycling lithium, iron and phosphorus elements, and the pickle slag can be used for recycling copper elements.
The test raw materials are from a certain smelter and comprise the following components:
(1) Crushing and screening the positive plate obtained by disassembling the discharged waste lithium iron phosphate battery to obtain the lithium iron phosphate positive waste, and measuring the chemical composition of the lithium iron phosphate positive waste: 30.51% of Fe, 3.82% of Li, 17.44% of P, 0.67% of Al, 0.12% of Cu, 1.48% of F, 0.011% of Si and 0.14% of Ni, wherein the molar ratio of Li to Fe to P is 1.00: 0.99: 1.02, and the mark is lithium iron phosphate waste 1.
(2) Crushing and screening the positive plate obtained by disassembling the discharged waste lithium iron phosphate battery to obtain the lithium iron phosphate positive waste, and measuring the chemical composition of the lithium iron phosphate positive waste: 31.83% of Fe, 4.06% of Li, 18.18% of P, 0.32% of Al, 0.07% of Cu, 0.20% of F, 0.027% of Si and 0.11% of Ni, wherein the molar ratio of Li, fe and P is 1.00: 0.97: 1.00, and the mark is lithium iron phosphate waste 2.
(3) Directly crushing the whole discharged waste lithium iron phosphate battery to obtain the high-impurity waste lithium iron phosphate, wherein the chemical composition of the waste lithium iron phosphate battery is as follows: 15.68% of Fe, 2.05% of Li, 8.96% of P, 1.12% of Al, 6.52% of Cu, 5.22% of F, 0.25% of Si and 0.14% of Ni, wherein the molar ratio of Li, fe and P is 1.00: 0.95, and the mark is lithium iron phosphate waste 3.
(4) The whole waste lithium iron phosphate battery after discharging is crushed and sieved to obtain the high-impurity waste lithium iron phosphate material, and the chemical composition of the waste lithium iron phosphate material is as follows: 13.55% of Fe, 1.84% of Li, 7.74% of P, 0.98% of Al, 6.05% of Cu, 3.52% of F, 0.18% of Si and 0.12% of Ni, wherein the molar ratio of Li, fe and P is 1.00: 0.92: 0.94, and the mark is lithium iron phosphate waste 4.
Example 1
Weighing 30g of the lithium iron phosphate waste 1 as a raw material, placing the raw material in a tubular atmosphere furnace, introducing nitrogen at the speed of 50ml/min, roasting at 600 ℃ for 3 hours, and cooling to room temperature to obtain a roasted material; then placing 1.5mol/L sodium hydroxide solution and roasting materials into a reaction kettle for alkaline leaching, wherein the liquid-solid ratio is 17.3: 1, the leaching temperature is 40 ℃, the leaching time is 3 hours, the stirring rate is 200r/min, nitrogen is introduced into the kettle during leaching, the nitrogen introduction rate is 100ml/min, and after the leaching is finished, filtering and washing with deionized water are carried out to obtain alkaline leaching residues and alkaline leaching liquid; and then placing 2.8mol/L sulfuric acid solution and alkaline leaching residue in a reaction kettle for acidic leaching, wherein the liquid-solid ratio is 11.7: 1, the leaching temperature is 40 ℃, the leaching time is 3.5h, the stirring speed is 400r/min, and after leaching is finished, filtering and washing with deionized water to obtain acid leaching solution (containing washing liquid) and acid leaching residue. The contents of fluorine element in the roasted material and copper element, aluminum, phosphorus, lithium and iron element in the pickle liquor are detected, the removal rates of aluminum and copper are respectively 94.6% and 99.7% (the removal rate of a certain element =100% -the total content of the element in the pickle liquor ÷ the total content of the element in the raw material × 100%) through calculation, the leaching rates of lithium, iron and phosphorus element are respectively 94.5% Li, 98.8% Fe and 97.2% P (the leaching rate of a certain element = the content of the element in the pickle liquor ÷ the total content of the element in the raw material × 100%), and the defluorination rate is 89.4% (the defluorination rate =100% -the total content of the fluorine element in the roasted material ÷ the total content of the fluorine element in the raw material × 100%).
Example 2
The lithium iron phosphate waste 2 was treated by the method of example 1, wherein the roasting temperature was 300 ℃, the roasting time was 6 hours, the alkaline leaching temperature was 50 ℃, the alkaline leaching time was 1 hour, and other conditions were unchanged. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 96.4 percent and 99.8 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 92.9 percent of Li, 98.7 percent of Fe and 97.9 percent of P respectively, and the defluorination rate is 86.4 percent.
Example 3
Weighing 30g of the lithium iron phosphate waste 1 as a raw material, placing the raw material in a tubular atmosphere furnace, introducing argon at the rate of 30ml/min, roasting at 750 ℃ for 3 hours, and cooling to room temperature to obtain a roasted material; then, placing 1mol/L sodium hydroxide solution and a roasting material in a reaction kettle for alkaline leaching, wherein the liquid-solid ratio is 10.4: 1, the leaching temperature is 60 ℃, the leaching time is 2 hours, the stirring speed is 250r/min, argon is introduced into the kettle during leaching, the argon introduction speed is 60ml/min, and after leaching, filtering and washing with deionized water are carried out to obtain alkaline leaching residues and alkaline leaching solution; and then placing 2mol/L sulfuric acid solution and alkaline leaching residue in a reaction kettle for acidic leaching, wherein the liquid-solid ratio is 13.1: 1, the leaching temperature is 50 ℃, the leaching time is 1h, the stirring speed is 400r/min, and after the leaching is finished, filtering and washing with deionized water to obtain acid leaching solution (containing washing liquid) and acid leaching residue. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 95.8 percent and 98.3 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 91.4 percent of Li, 98.0 percent of Fe and 96.6 percent of P respectively, and the defluorination rate is 92.2 percent.
Example 4
The lithium iron phosphate waste 3 is treated by the method of the embodiment 1, wherein the roasting time is 6 hours, 3mol/L hydrochloric acid is adopted in the acid leaching, the liquid-solid ratio is 11.8: 1, and other conditions are not changed. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 92.0 percent and 98.2 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 92.1 percent of Li, 98.3 percent of Fe and 96.4 percent of P respectively, and the defluorination rate is 94.5 percent.
Comparative example 1
The lithium iron phosphate scrap 3 was treated by the method of example 4, in which nitrogen gas was not introduced during firing (i.e., firing in an air atmosphere), and other conditions were not changed. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 92.8 percent and 3.2 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 93.8 percent of Li, 92.5 percent of Fe and 93.3 percent of P respectively, and the defluorination rate is 3.7 percent.
Fig. 3 is an XRD pattern of the lithium iron phosphate scrap 3. XRD analysis was performed on the calcines of example 4 and comparative example 1, and the results are shown in FIGS. 1 and 2, and comparing FIGS. 1 to 3, the characteristic peak of Cu in the calcine of example 4 is significantly higher in intensity than the characteristic peak of Cu in the raw material, and Cu is not present 2 Characteristic OThe peak shows that the non-oxidizing atmosphere roasting can effectively reduce copper oxide into metal copper, and the metal copper is not dissolved and remains in acid leaching residue during acid leaching, so that the effect of removing copper by acid leaching is greatly improved. In the calcined material of comparative example 1, part of the lithium iron phosphate was decomposed into Li 3 Fe 2 (PO 4 ) 3 And alpha-Fe 2 O 3 The characteristic peak of Cu disappears and Cu 2 Enhanced intensity of characteristic O peak, wherein alpha-Fe is leached in acid 2 O 3 Cu as a poorly soluble substance 2 O is a readily soluble compound, so that the leaching rate of iron is reduced and the copper content in the pickle liquor is increased.
Example 5
The lithium iron phosphate waste 3 was treated according to the method of example 3, wherein the roasting time was 3h, the alkaline leaching temperature was 20 ℃, and other conditions were unchanged. Detecting the contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in pickle liquor, calculating the removal rates of aluminum and copper to be 93.5 percent and 98.5 percent respectively, the leaching rates of lithium, iron and phosphorus to be 92.7 percent of Li, 98.4 percent of Fe and 94.0 percent of P respectively, and the defluorination rate to be 95.2 percent.
Comparative example 2
The lithium iron phosphate scrap 3 was treated by the method of example 5, in which argon gas was not introduced during firing (i.e., firing in an air atmosphere), and the other conditions were not changed. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 92.2 percent and 4.5 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 92.5 percent of Li, 87.5 percent of Fe and 93.7 percent of P respectively, and the defluorination rate is 95.6 percent.
XRD analysis was performed on the acid-leached residues of example 5 and comparative example 2, and the results are shown in FIGS. 4 and 5. As can be seen from comparison between FIGS. 4 and 5, the acid-leached residues of example 5 mainly contain C and Cu, and the characteristic peaks of copper are particularly clear and have high strength, whereas the acid-leached residues of comparative example 2 mainly contain alpha-Fe in addition to C 2 O 3 And no Cu. This is because the copper oxide is reduced to metallic copper when the raw material is baked in a non-oxidizing atmosphere, and copper does not remain dissolved in slag during acid leaching, thereby effectively removing copper. When the raw material is calcined in the air (oxidizing atmosphere), part of iron is oxidized to generate insoluble alpha-Fe 2 O 3 Iron loss is caused by remaining in slag during acid leaching; and copper existing in the form of simple substance in the raw material is oxidized into copper oxide, and the oxidized copper is leached into the solution together in the acid leaching, so that the copper removal rate and the iron leaching rate are low in comparative example 2.
The distribution ratios (in percentage) of copper, aluminum, iron, lithium and phosphorus in the alkaline leach solution, the acid leach solution and the acid leach residue in example 5 and comparative example 2 were analyzed and calculated, and the calculation results are shown in table 1. It should be noted that theoretically, the sum of the distribution ratios of a certain element in the alkali leaching solution, the acid leaching solution and the acid leaching slag should be 100%, but the error exists in the single detection, and the result after the single detection is processed, for example: in comparative example 2, the distribution ratio of Li in the alkali leaching solution = total amount of lithium contained in the obtained alkali leaching solution ÷ total amount of lithium in the raw material × 100%, two bits after the decimal point remain, and errors of a plurality of single terms are accumulated, so that the sum slightly deviates from 100%.
TABLE 1 (unit:%)
As can be seen from Table 1, about 10% of lithium was incorporated into the alkaline leach solution in each of example 5 and comparative example 2, due to diffusion of elemental lithium into the alkaline solution during leaching. The leaching rate of iron is higher in example 5 than in comparative example 2, while the partition ratio of copper in the pickling solution is much lower than in comparative example 2, because example 5 is calcined in a non-oxidizing atmosphere, so that the copper oxide is reduced to metallic copper that is insoluble in acid, thereby avoiding copper dissolution into the solution, which is consistent with the analysis results of fig. 4 and 5.
Example 6
The lithium iron phosphate scrap 4 was treated in the same manner as in example 1, wherein the calcination time was 6 hours and the other conditions were unchanged. Detecting the contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in pickle liquor, calculating the removal rates of aluminum and copper to be 92.5 percent and 97.7 percent respectively, the leaching rates of lithium, iron and phosphorus to be 93.3 percent of Li, 98.2 percent of Fe and 94.7 percent of P respectively, and the defluorination rate to be 93.3 percent.
Comparative example 3
The lithium iron phosphate waste 4 was treated as in example 6, wherein no nitrogen was introduced during alkaline leaching, and other conditions were unchanged. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 91.6 percent and 95.8 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 92.8 percent of Li, 97.5 percent of Fe and 93.1 percent of P respectively, and the defluorination rate is 92.2 percent.
The copper removal rate in comparative example 3 was slightly lower than that of example 6 because in the alkaline leaching, when no nitrogen was fed, a trace amount of copper was converted into soluble copper oxide or copper hydroxide, and in the subsequent acidic leaching, this portion of copper compound was dissolved, resulting in a slight decrease in the copper removal rate.
Example 7
The lithium iron phosphate waste 4 was treated by the method of example 6, in which the gas introduced during calcination was hydrogen, the introduction rate was 25ml/min, the acid leaching temperature was 25 ℃, and the other conditions were the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 93.1 percent and 97.2 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 93.5 percent of Li, 98.4 percent of Fe and 95.3 percent of P respectively, and the defluorination rate is 93.0 percent.
Example 8
The lithium iron phosphate waste 3 was treated by the method of example 4, wherein the roasting temperature was 700 ℃, the roasting time was 5 hours, the gas introduced for roasting was nitrogen, the introduction rate was 150ml/min, the leaching agent used for acidic leaching was 1.5mol/L nitric acid, the liquid-solid ratio was 17.5: 1, and the other conditions were the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 93.3 percent and 98.5 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 92.6 percent of Li, 98.8 percent of Fe and 92.3 percent of P respectively, and the defluorination rate is 92.7 percent.
Example 9
Weighing 30g of lithium iron phosphate waste 1 as a raw material, placing the raw material in a crucible, introducing nitrogen at a rate of 200ml/min, roasting at 800 ℃ for 1h, and cooling to room temperature to obtain a roasted material; then, placing 1mol/L potassium hydroxide solution and the roasted material in a reaction kettle for alkaline leaching, wherein the liquid-solid ratio is 10.5: 1, the leaching temperature is 30 ℃, the leaching time is 3 hours, the stirring speed is 300r/min, nitrogen is introduced into the kettle during leaching, the nitrogen introduction speed is 40ml/min, and after leaching, filtering and washing with deionized water are carried out to obtain alkaline leaching residues and alkaline leaching solution; and then placing 1.5mol/L sulfuric acid solution and alkaline leaching residue in a reaction kettle for acidic leaching, wherein the liquid-solid ratio of acidic leaching is 14.5: 1, the leaching temperature is 20 ℃, the leaching time is 3h, the stirring rate is 400r/min, and after the leaching is finished, filtering and washing with deionized water to obtain acid leaching solution (containing washing liquid) and acid leaching residue. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 94.5 percent and 98.8 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 93.2 percent of Li, 98.1 percent of Fe and 93.5 percent of P respectively, and the defluorination rate is 90.1 percent.
Comparative example 4
The lithium iron phosphate scrap 1 was treated by the method of example 9, wherein the roasting temperature was 850 ℃, the roasting time was 8 hours, and the other conditions were the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 92.2 percent and 97.3 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 88.9 percent of Li, 93.2 percent of Fe and 93.2 percent of P respectively, and the defluorination rate is 92.7 percent.
Comparative example 4 shows lower leaching rates of lithium and iron than example 9 because lithium is lost by volatilization during high-temperature calcination, and lithium iron phosphate reacts with carbon to form Fe 2 Phosphates of P and lithium, fe 2 P dissolves relatively slowly in acid, resulting in incomplete leaching in acid leaching. XRD analysis was performed on the calcined material obtained in comparative example 4, and the results are shown in fig. 6: cu has obvious characteristic peak, and LiFePO 4 Disappearance of characteristic peaks, fe 2 P、Li 4 P 2 O 7 And Li 3 PO 4 Characteristic peaks of (1) Fe in acidic leaching 2 P leaching is incomplete, thus resulting in a reduced iron leaching rate.
Example 10
The lithium iron phosphate scrap 4 was treated in the same manner as in example 2, except that the calcination time was 9 hours. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 93.7 percent and 98.0 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 94.5 percent of Li, 97.6 percent of Fe and 94.8 percent of P respectively, and the defluorination rate is 88.1 percent.
Example 11
The lithium iron phosphate waste 4 was treated by the method of example 4, wherein 3mol/L potassium hydroxide solution was used for alkaline leaching, the liquid-solid ratio of alkaline leaching was 9.0: 1, and the other conditions were the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 92.2 percent and 97.3 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 88.3 percent of Li, 98.2 percent of Fe and 91.7 percent of P respectively, and the defluorination rate is 92.4 percent.
Example 12
The lithium iron phosphate waste 3 was treated by the method of example 4, in which 1mol/L sodium hydroxide solution was used for alkaline leaching, and the other conditions were the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 91.7 percent and 97.6 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 95.7 percent of Li, 98.7 percent of Fe and 94.0 percent of P respectively, and the defluorination rate is 92.5 percent.
Comparing example 4, example 11 and example 12, it was found that the higher the alkali solution concentration in the alkaline leaching process, the lower the lithium leaching rate. This is because lithium in the calcine will be partially dispersed in the alkali liquor during alkaline leaching, causing loss of lithium, and the higher the concentration of alkali liquor, the greater its loss. Therefore, the leaching rate of lithium element was the highest in example 12, and the leaching rate was the lowest in example 4 and example 11.
Example 13
The lithium iron phosphate waste 3 was treated by the method of example 1, in which ferrous sulfate was mixed with the calcine before alkaline leaching, the amount of ferrous sulfate added was 1.1 times the total molar amount of copper in the calcine, and then alkaline leaching was performed, with the other conditions being the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 93.6 percent and 98.4 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 94.4 percent of Li, 97.5 percent of Fe and 95.1 percent of P respectively, and the defluorination rate is 93.3 percent.
Example 14
The lithium iron phosphate waste 3 was treated by the method of example 1, in which ferrous chloride was mixed with the calcine before alkaline leaching, the amount of ferrous chloride added was 1.0 times the total molar amount of copper in the calcine, and then alkaline leaching was performed, with the other conditions being the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 92.7 percent and 99.1 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 94.8 percent of Li, 98.3 percent of Fe and 93.4 percent of P respectively, and the defluorination rate is 91.7 percent.
Example 15
The lithium iron phosphate waste 3 was treated by the method of example 1, in which the ferrous nitrate was mixed with the calcine before alkaline leaching, the amount of ferrous nitrate added was 1.1 times the total molar amount of copper in the calcine, and then alkaline leaching was performed, with the other conditions being the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 93.3 percent and 98.6 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 94.2 percent of Li, 97.1 percent of Fe and 93.8 percent of P respectively, and the defluorination rate is 92.0 percent.
Example 16
The lithium iron phosphate waste 3 was treated by the method of example 1, in which iron powder was mixed with the calcine before alkaline leaching, the amount of iron powder added was 2.0 times the total molar amount of copper in the calcine, and then alkaline leaching was performed, with the other conditions being the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 94.0 percent and 98.6 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 93.6 percent of Li, 96.7 percent of Fe and 92.6 percent of P respectively, and the defluorination rate is 91.4 percent.
Example 17
The lithium iron phosphate waste 3 was treated by the method of example 16, in which 1mol/L hydrochloric acid solution was used for the acid leaching, the liquid-solid ratio was 17.0: 1, the acid leaching temperature was 30 ℃, the acid leaching time was 4 hours, and the other conditions were the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 92.8 percent and 99.2 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 94.7 percent of Li, 98.5 percent of Fe and 92.1 percent of P respectively, and the defluorination rate is 91.8 percent.
Example 18
The lithium iron phosphate waste 3 was treated by the method of example 16, wherein 1.8mol/L nitric acid solution was used for the acidic leaching, the liquid-solid ratio of the acidic leaching was 17.6: 1, the temperature of the acid leaching was 60 ℃, and the other conditions were the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 92.6 percent and 97.5 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 93.3 percent of Li, 97.1 percent of Fe and 94.3 percent of P respectively, and the defluorination rate is 93.1 percent.
Comparing example 4 with example 18, the copper removal rate in example 18 is slightly lower than in example 4, because in acid leaching, trace amounts of metallic copper may be oxidized by raising the temperature, thereby dissolving this copper into the solution.
Example 19
The lithium iron phosphate waste 3 was treated by the method of example 16, in which 1 mol/sulfuric acid solution was used for the acidic leaching, the liquid-solid ratio of the acidic leaching was 24.8: 1, and the other conditions were the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 93.6 percent and 98.2 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 90.8 percent of Li, 97.5 percent of Fe and 93.7 percent of P respectively, and the defluorination rate is 91.5 percent.
Comparative example 5
The lithium iron phosphate scrap 3 was treated by the method of example 19, in which the raw material was directly subjected to alkaline leaching-acidic leaching without roasting, and the alkaline leaching and acidic leaching conditions were the same. The contents of fluorine elements in the roasted material and copper, aluminum, phosphorus, lithium and iron elements in the pickle liquor are detected, the removal rates of aluminum and copper are calculated to be 94.1 percent and 9.3 percent respectively, the leaching rates of lithium, iron and phosphorus elements are 92.1 percent of Li, 98.3 percent of Fe and 93.2 percent of P respectively, and the defluorination rate is 0 percent.
Comparing comparative example 5 with comparative examples 1 and 2, it was found that the copper removal rate in comparative example 5 was significantly higher than in comparative examples 1 and 2 because a part of the copper in the raw material was present in the form of metallic copper (see fig. 3), which remained in the slag during leaching, so that the copper removal rate was higher than in comparative examples 1 and 2.
XRD analysis was performed on the acid-leached residues of example 19 and comparative example 5, and the results are shown in FIGS. 7 and 8. The acid-leached residue of example 19 had the same composition as that of comparative example 5, but the strength of the Cu characteristic peak was significantly higher than that of the acid-leached residue of comparative example 5, because the raw material inherently contained part of metallic copper, which remained in the residue during acid leaching; in contrast, after the raw material of example 19 is calcined in a non-oxidizing atmosphere, the copper oxide in the raw material is reduced to metallic copper, so that the copper is basically retained in the slag during acid leaching, and therefore, the copper content in the slag is increased, and the characteristic peak intensity of Cu is shown to be increased on an XRD (X-ray diffraction) spectrum.
The method adopts a non-oxidizing atmosphere roasting-alkaline leaching-acidic leaching process to treat the lithium iron phosphate waste, inhibits the oxidation of elemental copper in a non-oxidizing atmosphere, reduces a copper compound into metallic copper, reduces the dissolution of the copper in the subsequent steps, and improves the leaching selectivity; and protective gas is introduced or a reducing agent is added during alkaline leaching, so that the oxidation of metal copper can be effectively inhibited, the selectivity of subsequent acidic leaching is further improved, and the copper is maintained in a metal copper state in the whole process, so that the leaching rate of iron, lithium and phosphorus is improved, the leaching rate of copper is reduced, finally, aluminum and copper are deeply separated from iron, lithium and phosphorus, the purity of a pickle liquor is improved, and the comprehensive recovery rate of valuable metals is improved.
The novel process is suitable for recycling various lithium iron phosphate wastes, can improve the pretreatment efficiency of the waste lithium iron phosphate batteries, shortens the recycling process (low requirement on pretreatment) of the waste lithium iron phosphate batteries, and can be used for recycling the waste lithium iron phosphate batteries of various models and specifications. The process realizes the enrichment and open circuit of copper and aluminum during the high-efficiency copper and aluminum removal, and the leaching solution can directly recover valuable elements without F - The wastewater is discharged, and the comprehensive recovery rate of valuable elements is high.
In the description of the present specification, reference to the terms "one embodiment," "certain embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (10)
1. The method for removing copper and aluminum from the lithium iron phosphate waste is characterized by comprising the following steps:
roasting: roasting the waste under a non-oxidizing gas;
alkaline leaching: leaching the roasted waste material with an alkaline solution to obtain alkaline leaching residue; in the alkaline leaching process, at least one of two protection conditions of introducing protective gas and adding a reducing agent is adopted for protection;
acid leaching: and leaching the alkaline leaching residue by using an inorganic acid solution to obtain a pickle liquor.
2. The method for removing copper and aluminum from lithium iron phosphate scrap according to claim 1, wherein the non-oxidizing gas comprises at least one of hydrogen, carbon monoxide, nitrogen and rare gases.
3. The method for removing copper and aluminum from lithium iron phosphate waste material according to claim 1, wherein the reducing agent is selected from ferrous sulfate, ferrous nitrate, ferrous chloride and iron powder, and the addition amount of the reducing agent is 1.0-2.0 times of the total molar amount of copper in the roasted waste material.
4. The method for removing copper and aluminum from the lithium iron phosphate waste material as claimed in claim 1, wherein the roasting temperature is 300-800 ℃ and the roasting time is 1-9 h.
5. The method for removing copper and aluminum from lithium iron phosphate waste material according to claim 1, wherein the alkali solution is at least one selected from sodium hydroxide and potassium hydroxide, and a total OH content of 1mol/L-3mol/L is used in alkaline leaching - An alkali solution of (2).
6. The method for removing copper and aluminum from the lithium iron phosphate waste material as claimed in claim 5, wherein the alkaline leaching has a liquid-solid ratio of 9.0-17.3: 1.0, and the leaching time is 1h-3h.
7. The method for removing copper and aluminum from lithium iron phosphate waste material according to claim 1, wherein the treatment temperature of the alkaline leaching is 20-60 ℃.
8. The method for removing copper and aluminum from lithium iron phosphate waste material according to claim 1, wherein the inorganic acid solution is at least one selected from sulfuric acid, hydrochloric acid and nitric acid, and the total content of 1mol/L-5.6mol/L H is used in acid leaching + The inorganic acid solution of (2).
9. The method for removing copper and aluminum from the lithium iron phosphate waste material as recited in claim 8, wherein the liquid-solid ratio of the acidic leaching is 11.7-24.8: 1.0, and the acidic leaching time is 1h-4h.
10. The method for removing copper and aluminum from lithium iron phosphate waste material according to claim 1, wherein the treatment temperature of the acidic leaching is 20-60 ℃.
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