CN116835558A - Preparation method for synthesizing lithium iron phosphate by using waste lithium battery and product - Google Patents
Preparation method for synthesizing lithium iron phosphate by using waste lithium battery and product Download PDFInfo
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- CN116835558A CN116835558A CN202310862042.5A CN202310862042A CN116835558A CN 116835558 A CN116835558 A CN 116835558A CN 202310862042 A CN202310862042 A CN 202310862042A CN 116835558 A CN116835558 A CN 116835558A
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- iron phosphate
- lithium iron
- lithium
- waste
- battery
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- 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 126
- 239000002699 waste material Substances 0.000 title claims abstract description 68
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 43
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 43
- 238000002360 preparation method Methods 0.000 title claims abstract description 37
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 28
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 69
- 238000000034 method Methods 0.000 claims abstract description 45
- 229910052742 iron Inorganic materials 0.000 claims abstract description 22
- 239000011574 phosphorus Substances 0.000 claims abstract description 20
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 20
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 19
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims abstract description 17
- 229910052808 lithium carbonate Inorganic materials 0.000 claims abstract description 17
- 239000000243 solution Substances 0.000 claims description 42
- 229910052782 aluminium Inorganic materials 0.000 claims description 41
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 41
- 238000006243 chemical reaction Methods 0.000 claims description 34
- 239000007788 liquid Substances 0.000 claims description 34
- 239000000843 powder Substances 0.000 claims description 33
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 28
- 229910052799 carbon Inorganic materials 0.000 claims description 27
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 26
- 238000001354 calcination Methods 0.000 claims description 23
- 238000002386 leaching Methods 0.000 claims description 23
- 239000011575 calcium Substances 0.000 claims description 20
- 239000011777 magnesium Substances 0.000 claims description 20
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 18
- 239000012065 filter cake Substances 0.000 claims description 18
- 238000005406 washing Methods 0.000 claims description 18
- 239000000706 filtrate Substances 0.000 claims description 17
- 238000004537 pulping Methods 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 229910052791 calcium Inorganic materials 0.000 claims description 14
- 239000003638 chemical reducing agent Substances 0.000 claims description 14
- 229910052749 magnesium Inorganic materials 0.000 claims description 14
- 235000010323 ascorbic acid Nutrition 0.000 claims description 13
- 229960005070 ascorbic acid Drugs 0.000 claims description 13
- 239000011668 ascorbic acid Substances 0.000 claims description 13
- 229910052979 sodium sulfide Inorganic materials 0.000 claims description 13
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 claims description 13
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 12
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 11
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 11
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 230000032683 aging Effects 0.000 claims description 8
- 238000002425 crystallisation Methods 0.000 claims description 8
- 230000008025 crystallization Effects 0.000 claims description 8
- 239000008139 complexing agent Substances 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 7
- 238000001914 filtration Methods 0.000 claims description 7
- 238000001694 spray drying Methods 0.000 claims description 7
- 238000000227 grinding Methods 0.000 claims description 6
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 6
- 239000011347 resin Substances 0.000 claims description 6
- 229920005989 resin Polymers 0.000 claims description 6
- HRZFUMHJMZEROT-UHFFFAOYSA-L sodium disulfite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])(=O)=O HRZFUMHJMZEROT-UHFFFAOYSA-L 0.000 claims description 6
- 229940001584 sodium metabisulfite Drugs 0.000 claims description 6
- 235000010262 sodium metabisulphite Nutrition 0.000 claims description 6
- 229940079101 sodium sulfide Drugs 0.000 claims description 6
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 claims description 6
- 229940001474 sodium thiosulfate Drugs 0.000 claims description 6
- 235000019345 sodium thiosulphate Nutrition 0.000 claims description 6
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 238000001179 sorption measurement Methods 0.000 claims description 5
- 239000000725 suspension Substances 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 4
- 239000012266 salt solution Substances 0.000 claims description 4
- 239000002002 slurry Substances 0.000 claims description 4
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 claims description 3
- 235000010299 hexamethylene tetramine Nutrition 0.000 claims description 3
- 239000004312 hexamethylene tetramine Substances 0.000 claims description 3
- LJCNRYVRMXRIQR-OLXYHTOASA-L potassium sodium L-tartrate Chemical compound [Na+].[K+].[O-]C(=O)[C@H](O)[C@@H](O)C([O-])=O LJCNRYVRMXRIQR-OLXYHTOASA-L 0.000 claims description 3
- 229940074439 potassium sodium tartrate Drugs 0.000 claims description 3
- 235000011006 sodium potassium tartrate Nutrition 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 23
- 238000011084 recovery Methods 0.000 abstract description 19
- 238000004519 manufacturing process Methods 0.000 abstract description 13
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 abstract description 9
- 229910000398 iron phosphate Inorganic materials 0.000 abstract description 6
- 230000015572 biosynthetic process Effects 0.000 abstract description 5
- 238000003786 synthesis reaction Methods 0.000 abstract description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 4
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 4
- 239000010949 copper Substances 0.000 description 32
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 25
- 229910052802 copper Inorganic materials 0.000 description 25
- 239000012535 impurity Substances 0.000 description 16
- 238000000197 pyrolysis Methods 0.000 description 11
- 229910001385 heavy metal Inorganic materials 0.000 description 10
- 239000007791 liquid phase Substances 0.000 description 8
- 239000000047 product Substances 0.000 description 7
- -1 iron phosphate slag Chemical compound 0.000 description 5
- 238000007885 magnetic separation Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 4
- 239000005955 Ferric phosphate Substances 0.000 description 4
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- 229940032958 ferric phosphate Drugs 0.000 description 4
- 239000008103 glucose Substances 0.000 description 4
- 229910000399 iron(III) phosphate Inorganic materials 0.000 description 4
- 239000002893 slag Substances 0.000 description 4
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 3
- 229910019142 PO4 Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 238000004806 packaging method and process Methods 0.000 description 3
- 239000007790 solid phase Substances 0.000 description 3
- 239000002912 waste gas Substances 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- ZFXVRMSLJDYJCH-UHFFFAOYSA-N calcium magnesium Chemical compound [Mg].[Ca] ZFXVRMSLJDYJCH-UHFFFAOYSA-N 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 239000002910 solid waste Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 1
- 229930006000 Sucrose Natural products 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- OMZSGWSJDCOLKM-UHFFFAOYSA-N copper(II) sulfide Chemical compound [S-2].[Cu+2] OMZSGWSJDCOLKM-UHFFFAOYSA-N 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 229910001448 ferrous ion Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- DPTATFGPDCLUTF-UHFFFAOYSA-N phosphanylidyneiron Chemical compound [Fe]#P DPTATFGPDCLUTF-UHFFFAOYSA-N 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000009270 solid waste treatment Methods 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000005720 sucrose Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/45—Phosphates containing plural metal, or metal and ammonium
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Secondary Cells (AREA)
Abstract
The application relates to the technical field of lithium ion battery recovery, in particular to a preparation method and a product for synthesizing lithium iron phosphate by utilizing waste lithium batteries. Compared with the current recovery process for extracting lithium carbonate, the process directly prepares the lithium iron phosphate, realizes the recovery of all the components of phosphorus, iron and lithium, avoids the waste of phosphorus and iron resources, improves the recovery efficiency and the economic value, avoids the great waste of electric power and heat sources caused by the synthesis of the lithium carbonate and the iron phosphate, and has the advantages of lower production cost, shorter recovery process flow and higher production efficiency.
Description
Technical Field
The application relates to the technical field of lithium ion battery recovery, in particular to a preparation method for synthesizing lithium iron phosphate by utilizing waste lithium batteries and a product.
Background
With the popularization of portable products such as mobile phones, notebook computers, digital products and the like, rechargeable batteries such as lithium ion batteries have become consumer products required for daily life of people; particularly, with the explosive application of the lithium iron phosphate battery in the fields of electric automobiles and energy storage, the quantity of scrapped batteries generated therewith is increased in geometric multiples. The waste lithium battery contains a large amount of heavy metals, organic matters and the like, and if the waste lithium battery is discarded at will without effective treatment, serious and durable pollution is caused to surrounding environments such as soil, underground water and the like, and the waste lithium battery has great potential hazard to ecology and human health. Therefore, the recovery and the recycling of the waste lithium batteries become important problems which are essentially faced by the sustainable development of the environment protection and battery industry in China.
At present, the recovery process of the waste lithium iron phosphate battery generally takes extracted lithium as a main material and prepares battery-grade lithium carbonate as a final product, but the battery-grade lithium carbonate needs a large amount of electric power and heat sources in the drying and crushing processes, so that a large amount of energy waste is caused. In addition, a large amount of solid waste containing phosphorus iron, such as iron phosphate slag, is generated in the process of obtaining the battery-grade lithium carbonate, part of manufacturers directly discard the iron phosphate slag, and serious damage is caused to the environment, and even if some manufacturers discard the iron phosphate slag after environmental protection treatment, the iron phosphate slag is also a great waste of phosphorus and iron resources.
In view of the foregoing, it is necessary to provide a solution to the above-mentioned problems.
Disclosure of Invention
In order to solve the problems in the prior art, the application provides the preparation method for synthesizing the lithium iron phosphate by using the waste lithium battery, which can recycle the total components of phosphorus, iron and lithium in the waste lithium iron phosphate battery, avoids the waste of phosphorus and iron resources and does not generate a large amount of waste to pollute the environment.
In order to achieve the above purpose, the present application adopts the following technical scheme:
a preparation method for synthesizing lithium iron phosphate by using waste lithium batteries comprises the following steps:
s1, crushing, pyrolyzing and magnetically separating waste lithium iron phosphate batteries to obtain battery powder;
s2, adding the battery powder obtained in the step S1 into aluminum removal liquid to remove aluminum until the aluminum content is less than or equal to 100PPM, and washing to obtain the battery powder after aluminum removal;
s3, pulping the battery powder obtained in the step S2 after aluminum removal, continuously adding sulfuric acid in a reducing atmosphere for reaction, and separating filter residues when the pH is 1-3 to obtain a leaching solution;
s4, adding iron powder into the leaching solution obtained in the step S3 twice until Cu in the filtrate 2+ Less than or equal to 100PPM; then adding sodium sulfide into the filtrate to Cu in the filtrate 2+ Less than or equal to 10PPM; removing calcium and magnesium to obtain a primary preparation solution;
s5, detecting the proportion of phosphorus, iron and lithium in the primary preparation liquid obtained in the step S4, and adjusting the mole ratio of the phosphorus, the iron and the lithium to be 1: (0.99-1.0): (1.1-1.5), and simultaneously adding ascorbic acid to maintain the pH value to be 4.0-7.0; heating for crystallization, keeping the pH value of the reaction solution to be 5.0-7.0, aging after the reaction is finished, filtering, and washing to obtain a lithium iron phosphate filter cake; drying and calcining to finish the preparation from the waste lithium iron phosphate battery to the lithium iron phosphate.
Preferably, in the step S1, before crushing the waste lithium iron phosphate battery, the waste lithium iron phosphate battery is immersed in a conductive metal salt solution with the concentration of 0.5-5.0% for discharging for 24-72 hours.
Preferably, in the step S2, the aluminum removal liquid comprises 0.1-5% of a first reducing agent, 0.1-10% of a complexing agent, 1-10% of hydroxide and the balance of water in percentage by mass; the first reducing agent is at least one of ascorbic acid, sodium thiosulfate, sodium metabisulfite and sodium sulfide, the complexing agent is at least one of ethylenediamine tetraacetic acid, potassium sodium tartrate, hexamethylenetetramine and triethanolamine, and the hydroxide is sodium hydroxide and/or potassium hydroxide.
Preferably, in the step S3, a second reducing agent with the mass ratio of 0.1-2% is added to form a reducing atmosphere; the second reducing agent is at least one of iron powder, ascorbic acid, sodium thiosulfate, sodium metabisulfite and sodium sulfide.
Preferably, in step S4, the reaction conditions for adding iron powder in two steps are: the first reaction is carried out for 3 to 5 hours at the temperature of 30 to 70 ℃ and the pH value of 1.0 to 1.8, and the second reaction is carried out at the temperature of 40 to 70 ℃; the reaction is carried out for 3 to 5 hours at the pH value of 1.8 to 2.6.
Preferably, in step S4, ca and Mg are removed by using a filter column containing a resin having characteristic of Ca and Mg, and Ca is contained in the filtrate 2+ ≤50PPM,Mg 2+ Less than or equal to 50PPM to obtain the primary liquid.
Preferably, in the step S5, the mixture is heated to 95-110 ℃ for crystallization, and lithium carbonate suspension and/or lithium hydroxide solution are/is added dropwise to keep the pH value of the reaction solution at 5.0-7.0, and the reaction time is 3-5 h; the aging time is 0.5-2 h; washing until the conductivity of the washing water is 50-200 mu S/M, and obtaining a lithium iron phosphate filter cake.
Preferably, the preparation method for synthesizing the lithium iron phosphate by using the waste lithium battery further comprises the following steps:
s6, mixing the lithium iron phosphate filter cake obtained in the step S5 with a carbon source, pulping, and spray-drying to obtain a mixture of lithium iron phosphate powder and the carbon source; calcining in vacuum under protective atmosphere, grinding, and preparing the waste lithium iron phosphate battery into lithium iron phosphate.
Preferably, in step S6, the mass ratio of the lithium iron phosphate filter cake to the carbon source slurry is: carbon source: water=1 (0.05-0.2): (2-4); the calcination temperature is 700-850 ℃ and the calcination time is 18-24 h.
The application also provides the lithium iron phosphate prepared by the method for synthesizing the lithium iron phosphate by using the waste lithium battery.
The beneficial effects of the application are as follows: according to the recovery process provided by the application, the primary solution containing phosphorus ions, ferrous ions and lithium ions is obtained through sequential treatment of crushing, pyrolysis, magnetic separation, aluminum removal, leaching, primary copper removal, reduction of ferric iron, trace copper removal, heavy metal removal, calcium and magnesium removal, and then solution preparation and crystallization are carried out, so that the battery-grade lithium iron phosphate with the impurities meeting the requirements can be generated, a large amount of waste is not generated in the recovery process, and the influence of the production process on the environment is greatly reduced. Compared with the current recovery process for extracting lithium carbonate, the process directly prepares the lithium iron phosphate, realizes the recovery of all the components of phosphorus, iron and lithium, avoids the waste of phosphorus and iron resources, improves the recovery efficiency and the economic value, avoids the great waste of electric power and heat sources caused by the synthesis of the lithium carbonate and the iron phosphate, and has the advantages of lower production cost, shorter recovery process flow and higher production efficiency.
Drawings
Fig. 1 is a flowchart of a preparation method for synthesizing lithium iron phosphate by using waste lithium batteries.
Fig. 2 is a second flowchart of a preparation method for synthesizing lithium iron phosphate by using waste lithium batteries.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The first aspect of the present application is to provide a method for synthesizing lithium iron phosphate by using waste lithium batteries, as shown in fig. 1, comprising the following steps:
s1, crushing, pyrolyzing and magnetically separating waste lithium iron phosphate batteries to obtain battery powder;
s2, adding the battery powder obtained in the step S1 into aluminum removal liquid to remove aluminum until the aluminum content is less than or equal to 100PPM, and washing to obtain the battery powder after aluminum removal;
s3, pulping the battery powder obtained in the step S2 after aluminum removal, continuously adding sulfuric acid in a reducing atmosphere for reaction, and separating filter residues when the pH is 1-3 to obtain a leaching solution;
s4, adding iron powder into the leaching solution obtained in the step S3 twice until Cu in the filtrate 2+ Less than or equal to 100PPM; then adding sodium sulfide into the filtrate to Cu in the filtrate 2+ Less than or equal to 10PPM; removing calcium and magnesium to obtain a primary preparation solution;
s5, detecting the proportion of phosphorus, iron and lithium in the primary preparation liquid obtained in the step S4, and adjusting the mole ratio of the phosphorus, the iron and the lithium to be 1: (0.99-1.0): (1.1-1.5), and simultaneously adding ascorbic acid to maintain the pH value to be 4.0-7.0; heating for crystallization, keeping the pH value of the reaction solution to be 5.0-7.0, aging after the reaction is finished, filtering, and washing to obtain a lithium iron phosphate filter cake; drying and calcining to finish the preparation from the waste lithium iron phosphate battery to the lithium iron phosphate.
Compared with the recovery process for extracting lithium carbonate at present through the treatment procedures, the process of the application has at least the following advantages: the whole process has the advantages that all components of phosphorus, iron and lithium are recovered together, so that the waste of phosphorus and iron resources is avoided, and the recovery efficiency and the economic value are improved; the process avoids the synthesis of lithium carbonate and ferric phosphate, which is equivalent to avoiding the waste of a large amount of electric power and heat sources caused by drying and crushing in the synthesis process, and has lower production cost; the method has the advantages that a large amount of waste is not produced in the process, and meanwhile, a large amount of salt-containing wastewater generated by synthesizing lithium carbonate and anhydrous ferric phosphate is avoided in the process, so that the influence of the production process on the environment is greatly reduced; the recovery process flow is shorter, and the production efficiency is higher.
In some embodiments, in step S1, the waste lithium iron phosphate battery is immersed in a conductive metal salt solution with the concentration of 0.5-5.0% for discharging for 24-72 hours before being crushed. The conductive metal salt solution can be sodium carbonate solution or sodium chloride solution, and is conductive by utilizing electrolyte in the solution, so that the battery is short-circuited to achieve the purpose of discharging, the residual electric quantity in the battery is released, and the safety of subsequent pyrolysis is ensured. In addition, the discharge cabinet or other discharge modes can be used for discharging, so that the safety of the subsequent process production is ensured.
In some embodiments, in step S1, the battery is broken into primary broken, which aims to simply and roughly decompose the battery, so as to reduce the volume of the battery, and ensure that each component in the battery is fully destroyed and pyrolyzed in the subsequent pyrolysis process. And separating the diaphragm paper and a small amount of plastic shells by using an electrostatic separator after primary crushing so as to facilitate subsequent more sufficient pyrolysis and reduce waste gas generated by pyrolysis of organic matters. Of course, the crushing can also be directly fine crushing, and the pyrolysis is more sufficient, but based on the consideration of the production cost, the application preferably comprises the steps of primary crushing, pyrolysis and fine crushing, and screening after the fine crushing, so that the battery powder to be treated can be obtained, and the efficiency is higher during the fine crushing, and the loss of the battery powder is smaller. The broken pollutant is mainly noise of breaking equipment, and the environmental pollution degree is small.
In some embodiments, in step S1, the pyrolysis is performed in a rotary kiln at a temperature of 500-800 ℃, the pyrolyzed battery can obtain a mixture of metal and battery powder, and most of volatile organic solvents (such as carbonates) and binders become gases and are transferred to an exhaust gas treatment system, but part of carbonates and binders PVDF are carbonized due to rapid decomposition, and the mixture is sent to subsequent processes along with raw materials. In addition, the waste gas treatment system is connected with the crushing procedure, and system dust generated in the crushing procedure is purified in the waste gas treatment system and then discharged.
In some embodiments, in step S1, the magnetic separation aims to screen out iron sheets, copper sheets and aluminum sheets therein, and reduce the impurity content in the battery powder, so as to ensure the smooth progress of subsequent leaching, impurity removal and other procedures.
In some embodiments, in the step S2, the aluminum removal liquid comprises 0.1-5% of a first reducing agent, 0.1-10% of a complexing agent, 1-10% of hydroxide and the balance of water in percentage by mass; the first reducing agent is at least one of ascorbic acid, sodium thiosulfate, sodium metabisulfite and sodium sulfide, the complexing agent is at least one of ethylenediamine tetraacetic acid (EDTA), potassium sodium tartrate, hexamethylenetetramine and triethanolamine, and the hydroxide is sodium hydroxide and/or potassium hydroxide.
The aluminum is removed by adopting the aluminum removing liquid according to the principle that aluminum is dissolved in alkali liquor, the reaction temperature is controlled to be 25-60 ℃, the aluminum removing liquid has high aluminum removing efficiency, the quality of phosphorus, iron and lithium in battery powder can be ensured, the loss is reduced, the reaction is carried out until the aluminum content is lower than 100PPM, and the reaction time can be 30-90 min. And then washing and press-filtering to obtain the cell powder after aluminum removal.
According to the application, before leaching, the aluminum is removed by adopting the aluminum removal liquid, so that the aluminum can be selectively and more efficiently removed from the battery powder, and then leaching is performed, and the inventor finds that the process sequence is more beneficial to the subsequent impurity removal efficiency, the content of impurities such as copper, zinc, heavy metals and the like is reduced below a limit range value, the impurity rate of lithium iron phosphate is low, and the product consistency is higher.
Preferably, the solid-to-liquid ratio of the battery powder to the aluminum removal liquid for pulping is 1: (5-15). Specific examples may be 1:5, 1:6, 1:7, 1: 8. 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, or 1:15. The pulping solid-liquid ratio of the two is controlled within the range, so that aluminum in the battery powder can be effectively dissolved, and when the aluminum content in the battery powder is 10-100PPM, the leaching process requirement of lithium iron phosphate can be met.
In some embodiments, in step S3, a second reducing agent is added in an amount of 0.1 to 2% by mass to form a reducing atmosphere; the second reducing agent is at least one of iron powder, ascorbic acid, sodium thiosulfate, sodium metabisulfite and sodium sulfide. Preferably, the second reducing agent is iron powder to reduce the amount of impurities in the leachate.
Leaching in a reducing atmosphere with pH value controlled between 1-3 to ensure that most of iron in the leaching solution exists in the form of ferrous iron, and the generated leaching solution mainly contains Fe 2+ 、PO4 3- 、Li + And contains a small amount of Cu 2+ 、Fe 3+ 、Ca 2+ 、Mg 2+ Heavy metal plasma. In the leaching process, sulfuric acid is required to be continuously added, the sulfuric acid is gradually consumed along with the progress of the reaction, and the sulfuric acid is required to be added at any time according to the pH of the solution in the later stage of the reaction so as to keep the pH at 1-3. After leaching, the leaching solution is subjected to solid-liquid separation by a filter press, and filter residues (carbon black residues) are subjected to solid waste treatment.
In some embodiments, in step S4, the reaction conditions for adding iron powder in two portions are: reacting for 3-5 h at 30-70 ℃ and pH=1.0-1.8 for the first time; the second reaction is carried out for 3 to 5 hours at the temperature of 40 to 70 ℃ and the pH value of 1.8 to 2.6.
According to the application, a three-step copper removal method is adopted, firstly, the copper content is reduced to be within 30-100PPM through two steps of iron powder addition, then, the copper content is reduced to be below 10PPM through the third copper removal by adding sodium sulfide, and the inventor finds that the copper content can be well reduced to be below 10PPM through the three steps of working procedures, and the copper content can be reduced to be 50-100 PPM at most in the prior copper removal process in the lithium iron phosphate process, so that further copper removal is very difficult.
Preferably, the reaction temperature of the iron powder added for the second time is higher than that of the iron powder added for the first time, meanwhile, the pH value is adjusted, the replacement reaction of the iron powder and copper is further carried out forward, more copper can be replaced, meanwhile, the iron powder and a small amount of ferric iron in the leaching solution are reacted and converted into ferrous iron, the purpose of removing ferric iron impurities is achieved, and the product quality of lithium iron phosphate is ensured.
And in the third step, sodium sulfide is added, so that not only can trace copper be further removed to generate copper sulfide precipitate, but also sulfide precipitate of other heavy metals can be generated, and the final removal effect can reach Cu 2+ ≤10PPM,Zn 2+ Less than or equal to 10PPM, and the total sum of other heavy metals is less than 50PPM. However, if the copper removal of the first two steps is omitted, sodium sulfide is directly added to remove copper and other heavy metals, copper cannot be reduced to below 10PPM after the whole reaction is completed, the removal effect of other heavy metals is not better than the excellent effect, and a large amount of sodium impurities can be brought in to influence the quality of the subsequent lithium iron phosphate.
In some embodiments, in step S4, calcium and magnesium are removed to Ca in the filtrate using a filter column containing a calcium and magnesium-specific adsorption resin 2+ ≤50PPM,Mg 2+ Less than or equal to 50PPM to obtain the primary liquid.
After the copper removal process, calcium and magnesium are removed from the filtrate continuously, and the purpose of removing calcium and magnesium can be achieved by adopting the adsorption resin, and Ca 2+ Can be reduced to below 50PPM, mg 2+ Can be reduced to below 50PPM.
According to the process sequence of aluminum removal, leaching, three-step copper removal and calcium and magnesium removal, finally, the impurities in the leaching solution can be reduced to be below the required content of the battery, and the Fe-containing alloy is obtained 2+ 、PO4 3- 、Li + The primary liquid preparation of the waste lithium iron phosphate battery is completed, and the extremely important treatment procedure in the recovery treatment of the waste lithium iron phosphate battery is completed. The lithium iron phosphate synthesized by adopting the primary preparation liquid has low impurity phase and good quality, and completely meets the requirements of battery-grade lithium iron phosphate.
In some embodiments, in step S5, heating to 95-110 ℃ for crystallization, and dropwise adding lithium carbonate suspension and/or lithium hydroxide solution to keep the pH value of the reaction solution at 5.0-7.0, wherein the reaction time is 3-5 h; the aging time is 0.5-2 h; washing until the conductivity of the washing water is 50-200 mu S/M, and obtaining a lithium iron phosphate filter cake.
In the preparation process of lithium iron phosphate, ascorbic acid is also added as a reducing agent, and the ascorbic acid is of a ring structure with an acidic group, so that the pH range in the solution can be maintained, the stability of ferrous iron in the solution is ensured, the process of synthesizing lithium iron phosphate in a liquid phase is ensured, and the quality of the lithium iron phosphate is ensured.
In addition, the impurity removing efficiency of the application is high, the impurity content of the primary liquid is low, the solution after impurity removing generated by different batches of raw materials can be mixed together to be used as the primary liquid, the impurity content in the primary liquid after mixing also meets the requirement, and the preparation efficiency can be improved to a greater extent by liquid phase synthesis.
After the preparation of the solution is completed, crystallizing at 95-110 ℃, and simultaneously dropwise adding lithium carbonate suspension and/or lithium hydroxide solution to keep the pH value of the reaction solution at 5.0-7.0, wherein the synthesized lithium iron phosphate has better phase. Compared with the existing method for preparing lithium iron phosphate by calcining lithium carbonate and a ferric phosphate compound, the method directly adopts liquid phase to synthesize the lithium iron phosphate on the basis of primary liquid preparation, avoids a great deal of waste of electric power and heat sources caused by synthesizing the lithium carbonate and the ferric phosphate, has lower production cost, does not generate a great deal of waste, and has more environment-friendly overall production process and more accords with the modern production requirements.
After aging, a centrifuge or a filter press can be used for dehydration or filter pressing, and the final conductivity of the washing water is controlled to be 50-200 mu S/M through washing for multiple times so as to control sulfate radical, sodium ion and potassium ion within the range of battery-level lithium iron phosphate.
In some embodiments, the preparation method for synthesizing lithium iron phosphate by using waste lithium batteries, as shown in fig. 2, further comprises the following steps:
s6, mixing the lithium iron phosphate filter cake obtained in the step S5 with a carbon source, pulping, and spray-drying to obtain a mixture of lithium iron phosphate powder and the carbon source; calcining in vacuum under protective atmosphere, grinding, and preparing the waste lithium iron phosphate battery into lithium iron phosphate.
The pure lithium iron phosphate has poor conductivity, and after the lithium iron phosphate is synthesized in a liquid phase, the pure lithium iron phosphate is pulpified and mixed with a carbon source, and then the mixture is calcined, so that the surface of the lithium iron phosphate is coated with a carbon layer to improve the conductivity of the lithium iron phosphate, and meanwhile, the stability of the structure of the lithium iron phosphate is ensured. Compared with the preparation method of pure solid phase, namely calcining and synthesizing lithium iron phosphate, mixing and calcining the lithium iron phosphate with carbon source solid phase, the preparation method of the application comprises the steps of mixing liquid phase and calcining, wherein the carbon source uniformly wraps the lithium iron phosphate, the final product has better quality, and the electrochemical performance is better when the lithium iron phosphate is applied to batteries. In addition, the method for synthesizing the lithium iron phosphate by adopting the liquid phase is adopted at the beginning, so that the liquid phase mixing with the carbon source is more convenient, a large amount of energy sources are not needed, and excessive waste liquid is not generated.
Specifically, the carbon source may be glucose, sucrose or reduced starch. The protective atmosphere may be nitrogen.
In some embodiments, in step S6, the pulping mass ratio of the lithium iron phosphate filter cake to the carbon source is: carbon source: water=1 (0.05-0.2): (2-4); the calcination temperature is 700-850 ℃ and the calcination time is 18-24 h. This fraction of lithium iron phosphate is the amount of lithium iron phosphate in the lithium iron phosphate filter cake.
Before being mixed with a carbon source, the water content of the lithium iron phosphate filter cake can be detected, then water and the carbon source are added according to the mass ratio of pulping, the pulping is carried out according to the ratio of the range, and the uniformity of the mixing of the carbon source and the lithium iron phosphate is better. And after pulping, spray drying the slurry through spray drying equipment to obtain a dry mixture of uniformly mixed lithium iron phosphate and carbon sources, and pumping the mixture of the lithium iron phosphate and the carbon sources to a calcining kiln through a vacuum feeding machine, wherein the lithium iron phosphate with a uniform carbon coating can be obtained after calcining under the calcining condition.
The second aspect of the application aims to provide lithium iron phosphate prepared by the preparation method for synthesizing lithium iron phosphate by using waste lithium batteries.
The prepared lithium iron phosphate impurity meets the requirement of application in batteries, can be directly used as a battery anode material, is recycled to produce battery-grade lithium iron phosphate, has no resale of intermediate phosphorus, iron and lithium resources, and has more objective enterprise profits; and the process flow is short, the operability of enterprises is high, and the practicability is better.
Example 1
A preparation method for synthesizing lithium iron phosphate by using waste lithium batteries comprises the following steps:
1) Placing the waste lithium iron phosphate battery in a 1% sodium carbonate solution for 48 hours, and after the discharge is finished, primarily crushing the waste lithium iron phosphate battery to reduce the volume of the waste lithium iron phosphate battery; then separating out diaphragm paper and a small amount of plastic shells by using an electrostatic separator;
2) Transferring the waste lithium iron phosphate battery subjected to primary crushing into a rotary kiln for pyrolysis, wherein the pyrolysis temperature is 800 ℃; carrying out fine crushing, screening and magnetic separation again after pyrolysis to obtain battery powder; wherein the iron sheet, the copper sheet and the aluminum sheet obtained by magnetic separation can be directly sold;
3) Adding the obtained battery powder into aluminum removal liquid at a solid-to-liquid ratio of 1:6 for pulping, wherein the aluminum removal liquid comprises ascorbic acid with a mass ratio of 1%, complexing agent EDTA with a mass ratio of 2%, sodium hydroxide with a mass ratio of 5% and the rest water, controlling the temperature to be 25-60 ℃, reacting for 30-90 minutes until the content of detected aluminum is 10-100PPM qualified, and then washing and press-filtering to obtain the battery powder after aluminum removal;
4) Pulping the obtained battery powder after aluminum removal, conveying the battery powder to a leaching process through a pipeline, continuously adding sulfuric acid in a reducing atmosphere of iron powder with the mass ratio of 1% for reaction, adding sulfuric acid at any time according to the pH value of the solution, and finally completing the reaction when the pH value is controlled to be 1-3 to generate Fe 2+ 、PO4 3- 、Li + Contains a small amount of Cu 2+ 、Fe 3+ 、Ca 2+ 、Mg 2+ Plasma leachate, and trace heavy metals; separating filter residues by a filter press to obtain a leaching solution, and treating the filter residues (carbon black residues) as solid wastes;
5) Adding iron powder into the obtained leaching solution twice, wherein the reaction conditions for adding the iron powder for the first time are as follows: reacting for 4 hours at the temperature of 30-70 ℃ and the pH value of 1.0-1.8; the reaction conditions for adding the iron powder for the first time are as follows: reacting for 4 hours at the temperature of 40-70 ℃ and the pH value of 1.8-2.6; controlling the copper content of the filtrate to be within 30-100PPm after solid-liquid separation, and obtaining sponge copper from the filter cake; then continue to filtrateAdding sodium sulfide into the filtrate under stirring 2+ ≤10PPM，Zn 2+ Less than or equal to 10PPM, and the total amount of other heavy metals is less than 50PPM; then the filtrate is filtered by a filter column containing calcium-magnesium characteristic adsorption resin to finally obtain Ca 2+ ≤50PPM，Mg 2+ A primary liquid preparation of less than or equal to 50PPM;
6) Detecting the proportion of phosphorus, iron and lithium in the primary preparation liquid, and adjusting the mole ratio of the phosphorus, the iron and the lithium to be 1: (0.99-1.0): (1.1-1.5), and simultaneously adding ascorbic acid to maintain the pH value to be 4.0-7.0; the solution with the mixture ratio is transferred into a crystallization kettle, stirred uniformly at the rotation speed of 100 revolutions per minute, heated to 95-110 ℃, and the pH value of the synthetic solution is always controlled to be 5.0-7.0 by dropwise adding lithium carbonate suspension, and the reaction is completed after 4 hours of reaction; aging for 1h, and dehydrating by using a filter press; washing for multiple times until the final conductivity of the washing water is 50-200 mu S/M, thus obtaining a lithium iron phosphate filter cake; drying, calcining at 700-850 ℃ for 20 hours, grinding, packaging after the inspection is qualified, and completing the preparation from the waste lithium iron phosphate battery to the lithium iron phosphate.
Example 2
Unlike embodiment 1, this embodiment further includes the steps of:
7) Detecting the moisture in the lithium iron phosphate filter cake according to dry lithium iron phosphate: glucose: water=1 (0.05-0.2): (2-4) proportioning and pulping; spray drying the qualified slurry by using spray drying equipment after pulping to obtain a mixture of lithium iron phosphate powder and glucose;
8) Pumping the mixture of the dried lithium iron phosphate powder and glucose to a calcining kiln through a vacuum feeding machine, and calcining at 700-850 ℃ in the atmosphere of nitrogen protection for 20 hours; and finally grinding the calcined qualified lithium iron phosphate, packaging after the calcined lithium iron phosphate is qualified, and finishing the preparation from the waste lithium iron phosphate battery to the lithium iron phosphate.
The remainder is the same as embodiment 1 and will not be described here again.
Example 3
Unlike embodiment 1, this embodiment further includes the steps of:
and (3) after drying the lithium iron phosphate filter cake, adding a carbon source, mixing with the lithium iron phosphate solid phase, calcining, grinding, packaging after the test is qualified, and thus, completing the preparation from the waste lithium iron phosphate battery to the lithium iron phosphate.
The remainder is the same as embodiment 1 and will not be described here again.
Comparative example 1
Unlike example 1, this comparative example, after magnetic separation to obtain battery powder, was leached with sulfuric acid to obtain a leachate; then adding iron powder for copper removal, and removing copper-containing filter residues after filtering; adding 5% sodium hydroxide to remove aluminum, and filtering; and then, the filtrate is filtered by a filter column containing the calcium-magnesium characteristic adsorption resin, and the calcium and magnesium are removed to obtain the primary preparation liquid.
The remainder is the same as embodiment 1 and will not be described here again.
The lithium iron phosphate obtained in examples 1 to 3 and comparative example 1 was used as a positive electrode material in a secondary battery, the negative electrode material was graphite, the separator was a polyethylene separator coated with a ceramic separator on one side, and the electrolyte was Ethylene Carbonate (EC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC) in a volume ratio of 1:1:1, and the preparation method of the secondary battery was described in the prior art, and will not be repeated here.
The specific capacity of the obtained battery 1C was measured after 100 cycles of the lower cycle, and the results are shown in table 1 below.
TABLE 1
From the test results, the lithium iron phosphate prepared by the recovery process has better specific capacity and completely meets the requirements of battery application. In addition, as can be seen from the comparison of examples 2 to 3, the carbon layer is coated more uniformly by using the liquid phase mixed carbon source, and the battery has more excellent specific capacity after 100 cycles.
In the description of embodiments of the application, a particular feature, structure, material, or characteristic may be combined in any suitable manner in one or more embodiments or examples.
In the description of the embodiments of the present application, it is to be understood that "-" and "-" denote the same ranges of the two values, and the ranges include the endpoints. For example, "A-B" means a range greater than or equal to A and less than or equal to B. "A-B" means a range of greater than or equal to A and less than or equal to B.
In the description of embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, meaning that three relationships may exist, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. The preparation method for synthesizing the lithium iron phosphate by using the waste lithium battery is characterized by comprising the following steps of:
s1, crushing, pyrolyzing and magnetically separating waste lithium iron phosphate batteries to obtain battery powder;
s2, adding the battery powder obtained in the step S1 into aluminum removal liquid to remove aluminum until the aluminum content is less than or equal to 100PPM, and washing to obtain the battery powder after aluminum removal;
s3, pulping the battery powder obtained in the step S2 after aluminum removal, continuously adding sulfuric acid in a reducing atmosphere for reaction, and separating filter residues when the pH is 1-3 to obtain a leaching solution;
s4, adding iron powder into the leaching solution obtained in the step S3 twice until Cu in the filtrate 2+ Less than or equal to 100PPM; then adding sodium sulfide into the filtrate to Cu in the filtrate 2+ Less than or equal to 10PPM; removing Ca and Mg to obtain primary liquid；
S5, detecting the proportion of phosphorus, iron and lithium in the primary preparation liquid obtained in the step S4, and adjusting the mole ratio of the phosphorus, the iron and the lithium to be 1: (0.99-1.0): (1.1-1.5), and simultaneously adding ascorbic acid to maintain the pH value to be 4.0-7.0; heating for crystallization, keeping the pH value of the reaction solution to be 5.0-7.0, aging after the reaction is finished, filtering, and washing to obtain a lithium iron phosphate filter cake; drying and calcining to finish the preparation from the waste lithium iron phosphate battery to the lithium iron phosphate.
2. The method for synthesizing lithium iron phosphate by using waste lithium batteries according to claim 1, wherein in the step S1, before the waste lithium iron phosphate batteries are crushed, the waste lithium iron phosphate batteries are immersed in a conductive metal salt solution with the concentration of 0.5-5.0% for discharging for 24-72 hours.
3. The method for synthesizing lithium iron phosphate by utilizing waste lithium batteries according to claim 1, wherein in the step S2, the aluminum removal liquid comprises 0.1-5% of a first reducing agent, 0.1-10% of a complexing agent, 1-10% of hydroxide and the balance of water by mass; the first reducing agent is at least one of ascorbic acid, sodium thiosulfate, sodium metabisulfite and sodium sulfide, the complexing agent is at least one of ethylenediamine tetraacetic acid, potassium sodium tartrate, hexamethylenetetramine and triethanolamine, and the hydroxide is sodium hydroxide and/or potassium hydroxide.
4. The method for synthesizing lithium iron phosphate by using waste lithium batteries according to claim 1, wherein in the step S3, a second reducing agent with a mass ratio of 0.1-2% is added to form a reducing atmosphere; the second reducing agent is at least one of iron powder, ascorbic acid, sodium thiosulfate, sodium metabisulfite and sodium sulfide.
5. The method for synthesizing lithium iron phosphate by using waste lithium batteries according to any one of claims 1 to 4, wherein in the step S4, the reaction conditions of adding iron powder in two steps are: reacting for 3-5 h at 30-70 ℃ and pH=1.0-1.8 for the first time; the second reaction is carried out for 3 to 5 hours at the temperature of 40 to 70 ℃ and the pH value of 1.8 to 2.6.
6. The method for synthesizing lithium iron phosphate by using waste lithium batteries as claimed in claim 1, wherein in the step S4, a filter column containing a characteristic adsorption resin of calcium and magnesium is used for removing calcium and magnesium until Ca in the filtrate 2+ ≤50PPM,Mg 2+ Less than or equal to 50PPM to obtain the primary liquid.
7. The method for synthesizing lithium iron phosphate by using waste lithium batteries according to claim 1, wherein in the step S5, the solution is heated to 95-110 ℃ for crystallization, and lithium carbonate suspension and/or lithium hydroxide solution are added dropwise to keep the pH value of the reaction solution at 5.0-7.0, and the reaction time is 3-5 hours; the aging time is 0.5-2 h; washing until the conductivity of the washing water is 50-200 mu S/M, and obtaining a lithium iron phosphate filter cake.
8. The method for synthesizing lithium iron phosphate by using waste lithium batteries according to claim 1 or 7, further comprising the steps of:
s6, mixing the lithium iron phosphate filter cake obtained in the step S5 with a carbon source, pulping, and spray-drying to obtain a mixture of lithium iron phosphate powder and the carbon source; calcining in vacuum under protective atmosphere, grinding, and preparing the waste lithium iron phosphate battery into lithium iron phosphate.
9. The method for synthesizing lithium iron phosphate by using waste lithium batteries according to claim 8, wherein in the step S6, the mass ratio of the lithium iron phosphate filter cake to the carbon source slurry is: carbon source: water=1 (0.05-0.2): (2-4); the calcination temperature is 700-850 ℃ and the calcination time is 18-24 h.
10. A lithium iron phosphate prepared by the method for preparing lithium iron phosphate by using waste lithium batteries according to any one of claims 1 to 9.
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