CN117566706A - Method for recycling phosphorus-iron compound from waste lithium iron phosphate battery - Google Patents
Method for recycling phosphorus-iron compound from waste lithium iron phosphate battery Download PDFInfo
- Publication number
- CN117566706A CN117566706A CN202311536238.1A CN202311536238A CN117566706A CN 117566706 A CN117566706 A CN 117566706A CN 202311536238 A CN202311536238 A CN 202311536238A CN 117566706 A CN117566706 A CN 117566706A
- Authority
- CN
- China
- Prior art keywords
- iron
- aluminum
- value
- phosphorus
- phosphate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 87
- DPTATFGPDCLUTF-UHFFFAOYSA-N phosphanylidyneiron Chemical compound [Fe]#P DPTATFGPDCLUTF-UHFFFAOYSA-N 0.000 title claims abstract description 57
- 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 52
- 239000002699 waste material Substances 0.000 title claims abstract description 45
- 238000004064 recycling Methods 0.000 title description 7
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 125
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 120
- 239000007788 liquid Substances 0.000 claims abstract description 103
- 238000001556 precipitation Methods 0.000 claims abstract description 90
- 238000000926 separation method Methods 0.000 claims abstract description 65
- 238000002386 leaching Methods 0.000 claims abstract description 63
- 239000002893 slag Substances 0.000 claims abstract description 54
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 42
- 239000010949 copper Substances 0.000 claims abstract description 42
- 229910052802 copper Inorganic materials 0.000 claims abstract description 42
- 238000005406 washing Methods 0.000 claims abstract description 35
- 230000001105 regulatory effect Effects 0.000 claims abstract description 31
- 239000000706 filtrate Substances 0.000 claims abstract description 26
- 239000000843 powder Substances 0.000 claims abstract description 26
- 239000002253 acid Substances 0.000 claims abstract description 24
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 24
- 239000011574 phosphorus Substances 0.000 claims abstract description 24
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 21
- 230000001590 oxidative effect Effects 0.000 claims abstract description 20
- 238000001035 drying Methods 0.000 claims abstract description 18
- 239000007800 oxidant agent Substances 0.000 claims abstract description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 232
- 239000000243 solution Substances 0.000 claims description 126
- 229910052742 iron Inorganic materials 0.000 claims description 107
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims description 85
- 238000007254 oxidation reaction Methods 0.000 claims description 52
- 230000003647 oxidation Effects 0.000 claims description 50
- 229910000398 iron phosphate Inorganic materials 0.000 claims description 49
- 239000005955 Ferric phosphate Substances 0.000 claims description 40
- 229940032958 ferric phosphate Drugs 0.000 claims description 40
- 229910000399 iron(III) phosphate Inorganic materials 0.000 claims description 40
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 39
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 30
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 28
- 239000002244 precipitate Substances 0.000 claims description 17
- 239000007787 solid Substances 0.000 claims description 17
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 15
- 239000002002 slurry Substances 0.000 claims description 15
- 150000001875 compounds Chemical class 0.000 claims description 14
- 239000003638 chemical reducing agent Substances 0.000 claims description 11
- 125000004122 cyclic group Chemical group 0.000 claims description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 8
- 238000006386 neutralization reaction Methods 0.000 claims description 7
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 6
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 5
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 5
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 4
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 4
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 4
- 239000000920 calcium hydroxide Substances 0.000 claims description 4
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 4
- 239000000292 calcium oxide Substances 0.000 claims description 4
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 4
- 229910001386 lithium phosphate Inorganic materials 0.000 claims description 4
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 4
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 claims description 4
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 3
- 229910052979 sodium sulfide Inorganic materials 0.000 claims description 3
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 claims description 3
- 238000002347 injection Methods 0.000 claims description 2
- 239000007924 injection Substances 0.000 claims description 2
- 239000010926 waste battery Substances 0.000 claims description 2
- 239000003002 pH adjusting agent Substances 0.000 claims 1
- ILRRQNADMUWWFW-UHFFFAOYSA-K aluminium phosphate Chemical compound O1[Al]2OP1(=O)O2 ILRRQNADMUWWFW-UHFFFAOYSA-K 0.000 abstract description 11
- 238000011084 recovery Methods 0.000 abstract description 10
- JRBRVDCKNXZZGH-UHFFFAOYSA-N alumane;copper Chemical compound [AlH3].[Cu] JRBRVDCKNXZZGH-UHFFFAOYSA-N 0.000 abstract description 7
- 230000001276 controlling effect Effects 0.000 abstract 1
- 238000003756 stirring Methods 0.000 description 38
- -1 phosphonic acid group cation Chemical class 0.000 description 28
- 239000012065 filter cake Substances 0.000 description 26
- 238000006243 chemical reaction Methods 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 17
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 16
- 229910052760 oxygen Inorganic materials 0.000 description 16
- 239000001301 oxygen Substances 0.000 description 16
- 238000000975 co-precipitation Methods 0.000 description 15
- 238000001914 filtration Methods 0.000 description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 13
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 13
- 239000000047 product Substances 0.000 description 12
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 10
- 229910001431 copper ion Inorganic materials 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- 229910001448 ferrous ion Inorganic materials 0.000 description 9
- 239000012535 impurity Substances 0.000 description 9
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 8
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 8
- 229910052799 carbon Inorganic materials 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 229910001416 lithium ion Inorganic materials 0.000 description 7
- 238000002360 preparation method Methods 0.000 description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 6
- 239000003513 alkali Substances 0.000 description 6
- 238000006073 displacement reaction Methods 0.000 description 6
- 229910052744 lithium Inorganic materials 0.000 description 6
- 229910001447 ferric ion Inorganic materials 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 5
- KCZFLPPCFOHPNI-UHFFFAOYSA-N alumane;iron Chemical compound [AlH3].[Fe] KCZFLPPCFOHPNI-UHFFFAOYSA-N 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000004062 sedimentation Methods 0.000 description 4
- 239000004254 Ammonium phosphate Substances 0.000 description 3
- 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 3
- 238000005273 aeration Methods 0.000 description 3
- 229910000148 ammonium phosphate Inorganic materials 0.000 description 3
- 235000019289 ammonium phosphates Nutrition 0.000 description 3
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 150000007522 mineralic acids Chemical class 0.000 description 3
- 238000010979 pH adjustment Methods 0.000 description 3
- 238000005554 pickling Methods 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 238000002203 pretreatment Methods 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- 239000003570 air Substances 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 description 2
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 150000002505 iron Chemical class 0.000 description 2
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000006012 monoammonium phosphate Substances 0.000 description 2
- 235000019837 monoammonium phosphate Nutrition 0.000 description 2
- 229910000403 monosodium phosphate Inorganic materials 0.000 description 2
- 235000019799 monosodium phosphate Nutrition 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 239000013049 sediment Substances 0.000 description 2
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- LWIHDJKSTIGBAC-UHFFFAOYSA-K tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 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 1
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-L Phosphate ion(2-) Chemical compound OP([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-L 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- 229940001007 aluminium phosphate Drugs 0.000 description 1
- CYUOWZRAOZFACA-UHFFFAOYSA-N aluminum iron Chemical compound [Al].[Fe] CYUOWZRAOZFACA-UHFFFAOYSA-N 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- 229920001429 chelating resin Polymers 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- UATXJGCWVXKVBN-UHFFFAOYSA-L dihydrogen phosphate iron(2+) Chemical compound [Fe+2].OP(O)([O-])=O.OP(O)([O-])=O UATXJGCWVXKVBN-UHFFFAOYSA-L 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-M dihydrogenphosphate Chemical compound OP(O)([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-M 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- AOBAVABSFWTQIX-UHFFFAOYSA-L hydrogen phosphate;iron(2+) Chemical compound [Fe+2].OP([O-])([O-])=O AOBAVABSFWTQIX-UHFFFAOYSA-L 0.000 description 1
- 238000009854 hydrometallurgy Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- VXWSFRMTBJZULV-UHFFFAOYSA-H iron(3+) sulfate hydrate Chemical compound O.[Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O VXWSFRMTBJZULV-UHFFFAOYSA-H 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- KVMMIDQDXZOPAB-UHFFFAOYSA-N isoquinoline-3-carboxylic acid Chemical class C1=CC=C2C=NC(C(=O)O)=CC2=C1 KVMMIDQDXZOPAB-UHFFFAOYSA-N 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910000402 monopotassium phosphate Inorganic materials 0.000 description 1
- 235000019796 monopotassium phosphate Nutrition 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 229940085991 phosphate ion Drugs 0.000 description 1
- 235000011007 phosphoric acid Nutrition 0.000 description 1
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 description 1
- SIOXPEMLGUPBBT-UHFFFAOYSA-N picolinic acid Chemical class OC(=O)C1=CC=CC=N1 SIOXPEMLGUPBBT-UHFFFAOYSA-N 0.000 description 1
- 229910000160 potassium phosphate Inorganic materials 0.000 description 1
- 235000011009 potassium phosphates Nutrition 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- LOAUVZALPPNFOQ-UHFFFAOYSA-N quinaldic acid Chemical class C1=CC=CC2=NC(C(=O)O)=CC=C21 LOAUVZALPPNFOQ-UHFFFAOYSA-N 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000001488 sodium phosphate Substances 0.000 description 1
- 229910000162 sodium phosphate Inorganic materials 0.000 description 1
- 235000011008 sodium phosphates Nutrition 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000000967 suction filtration Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- VITRLXDSBBVNCZ-UHFFFAOYSA-K trichloroiron;hydrate Chemical compound O.Cl[Fe](Cl)Cl VITRLXDSBBVNCZ-UHFFFAOYSA-K 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
- 238000005303 weighing Methods 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
- C01B25/37—Phosphates of heavy metals
- C01B25/375—Phosphates of heavy metals of iron
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/18—Stationary reactors having moving elements inside
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/54—Reclaiming serviceable parts of waste accumulators
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
-
- 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
Abstract
The embodiment of the application provides a method for recovering a phosphorus-iron compound from a waste lithium iron phosphate battery, which comprises the following steps: acid leaching, copper removal and aluminum removal are carried out on waste lithium iron phosphate battery powder, the iron-phosphorus ratio of the obtained copper-aluminum removal solution is regulated, the pH value is regulated to be 0.4-1.2 in the first round, an oxidant is added, solid-liquid separation is carried out, the pH value of filtrate is regulated to be 1.5-2.0 in the second round, the oxidant is continuously added, the solid-liquid separation is carried out to obtain phosphorus iron slag and final filtrate, the phosphorus iron slag is combined, and the phosphorus iron compound is obtained after washing and drying. According to the method, the purity and the recovery rate of the phosphorus iron compound can be improved by controlling the pH value of the copper-removing aluminum solution, the aluminum content in the phosphorus iron compound precipitated under the low pH value is extremely low, and then the pH value is adjusted to be high, so that the precipitation of aluminum phosphate can be avoided due to the low phosphorus concentration, the purity of the phosphorus iron compound can be ensured to be high, and the yield of the phosphorus iron compound is high.
Description
Technical Field
The application relates to the technical field of battery material preparation, in particular to a method for recycling a phosphorus-iron compound from waste lithium iron phosphate batteries.
Background
The lithium iron phosphate battery has the characteristics of high specific capacity, stable structure, safe performance, long service life and the like, and is widely applied to the field of new energy. However, the service life cycle of the lithium ion battery is generally 3-5 years, more and more lithium ion batteries are retired and scrapped along with the time, and the subsequent retirement amount is estimated by relevant institutions to be increased continuously. How to properly deal with these retired batteries becomes a current hot spot problem.
The current mainstream treatment mode of the waste lithium iron phosphate battery is to selectively leach out valuable elements such as lithium, copper and the like or to dissolve all the elements in the waste lithium iron phosphate battery by a hydrometallurgy mode, and then to recover the valuable elements step by step. Because the lithium iron phosphate positive electrode powder in the waste lithium iron phosphate battery is adhered to the aluminum foil, the lithium iron phosphate positive electrode powder or the battery powder inevitably contains higher aluminum content in the process of leaching valuable elements, so that the leaching solution contains higher-concentration aluminum, and the aluminum concentration in the ferric phosphate prepared by a subsequent liquid phase method is higher.
In current practice, the dealumination process may be divided into pre-treatment or post-treatment. The pretreatment method mainly comprises the steps of soaking battery powder in alkaline solution such as sodium hydroxide and the like to remove aluminum before acid leaching, and removing aluminum by utilizing the characteristic that sodium metaaluminate is soluble under strong alkalinity. However, the sodium metaaluminate solution prepared by the method is not well treated, needs to be added with acid to prepare aluminum hydroxide and the like in the subsequent process, has large solution quantity and complex process in the production process, and removes aluminum by the method, and because the common lithium iron phosphate powder contains carbon Which readily adsorbs aluminum in solution, resulting in an undesirable aluminum removal effect of the process. Post-treatment is typically performed by removing aluminum from the leachate, for example, by removing aluminum with resin or removing aluminum by precipitation, for example, CN113800494a discloses a method for selectively recovering aluminum from the acid leaching solution of waste lithium iron phosphate battery material, which employs phosphonic acid group cation chelate resin for selectively adsorbing and separating aluminum from the acid leaching solution of waste lithium iron phosphate battery material. The method can selectively extract aluminum, but the cationic chelating resin has large dosage, and new impurity ions are introduced, so that the dosage of acid and alkali for adsorption and desorption is extremely large, the production cost is greatly increased, and the method cannot be applied to industrial production. In addition, an organic complex is used for precipitation and aluminum removal, for example, CN 113880063A discloses an aluminum removal method for phosphorus iron slag after lithium extraction of waste lithium iron phosphate, and picolinic acid compounds, quinolinecarboxylic acid compounds and isoquinoline-3-carboxylic acid compounds are selected as aluminum removal agents. Although these organic aluminum scavengers effectively remove aluminum impurities, the aluminum scavengers cannot be recycled, and the resulting organic complex precipitate can only be treated in the form of waste residue, thus greatly reducing the economic utility value. In addition, a method for comprehensively utilizing waste lithium iron phosphate cathode materials is disclosed by neutralization precipitation, such as CN116477591A, and the method can effectively separate and recycle copper, iron, lithium and other useful metal elements in the waste lithium iron phosphate cathode materials through combining two-stage leaching, reduction copper removal, neutralization precipitation aluminum removal, oxidation precipitated iron, carbonate precipitated lithium and other processes, wherein a neutralizing agent is added in one step to adjust the pH value for removing aluminum, but the aluminum removal mode has limited effect, the obtained aluminum removal solution still contains a certain amount of aluminum, and in the subsequent oxidation precipitated iron step, the method is usually carried out under acidic conditions, because the ion product constant of the iron phosphate and the aluminum phosphate is very close (the Ksp of the iron phosphate is about 1.3 x 10) -22 The Ksp of aluminum phosphate is about 9.84 x 10 -21 ) Therefore, the phenomenon of co-precipitation of iron and aluminum is very easy to occur in the process of preparing the iron phosphate by adopting an oxidation and precipitation method of singly adjusting the pH value, and the phenomenon is also a main reason that the aluminum content in the iron phosphate product prepared by adopting the waste lithium iron phosphate battery in the prior art is too high.
Above, although there are various methods for removing aluminum from waste battery powder at present, various defects exist, and aluminum in general solution is difficult to be treated cleanly, so that the aluminum content in the subsequently prepared ferric phosphate cannot meet the market demand, therefore, a method capable of solving the problem of exceeding the standard of aluminum content in the ferric phosphate and stably producing the ferric phosphate is sought to have important significance.
Disclosure of Invention
In a first aspect, embodiments of the present application provide a method for recovering a phosphorus iron compound from a spent lithium iron phosphate battery, the method comprising:
s1: acid leaching is carried out on the waste lithium iron phosphate battery powder, and leaching liquid is obtained after solid-liquid separation;
s2: copper and aluminum removal treatment is carried out on the leaching solution, and copper and aluminum removal solution is obtained after solid-liquid separation;
s3: and (3) regulating the iron-phosphorus ratio of the copper-removing aluminum solution, performing first-round regulation to the pH value of 0.4-1.2, adding an oxidant, performing solid-liquid separation to obtain ferrophosphorus slag and filtrate, performing second-round regulation to the pH value of 1.5-2.0 on the filtrate, continuously adding the oxidant, performing solid-liquid separation to obtain ferrophosphorus slag and final filtrate, merging the ferrophosphorus slag, washing and drying to obtain the ferrophosphorus compound. In the step, the pH value is adjusted for the first time and the oxidant is added, so that most of phosphorus and iron can be precipitated, the phosphorus content in the solution is greatly reduced, and further in the process of adjusting the pH value for the second time, the aluminum precipitation is also greatly reduced due to the extremely low phosphorus content, so that the aluminum content in the obtained phosphorus-iron compound is extremely low.
In an alternative embodiment of the present application, the iron to phosphorus ratio in step S3 is (0.96-1.02): 1.
In an alternative embodiment of the present application, the secondary adjustment of pH in step S3 is a stepwise adjustment performed in order of low pH to high pH.
In an alternative embodiment, the regulator for adjusting the pH value in step S3 is at least one of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid; the regulator for regulating the pH value of the secondary wheel is at least one selected from sodium hydroxide, ammonia water, lithium phosphate, lithium carbonate, sodium carbonate, calcium hydroxide or calcium oxide.
In an alternative embodiment of the present application, the oxidant in step S3 is added continuously.
In an alternative embodiment of the present application, the copper removal in step S2 is performed by replacing copper with iron powder.
In an alternative embodiment of the present application, the removing aluminum in step S2 uses a neutralization precipitation to remove aluminum, where the conditions of the neutralization precipitation to remove aluminum are: and on the premise of excessive reducing agent, regulating the pH value to 2.5-3.5.
In an alternative embodiment of the present application, the reducing agent is iron powder.
In an alternative embodiment of the present application, the reducing agent further includes at least one of sodium sulfide and sodium persulfate.
In an alternative embodiment of the present application, the iron content of the final filtrate in step S3 is less than 1g/L.
In an alternative embodiment of the present application, the method for recovering a phosphorus iron compound from a waste lithium iron phosphate battery further includes step S4: and (3) preparing slurry by utilizing the phosphorus iron compound, regulating the pH value of the slurry to be not less than 2.3, and washing and drying the obtained precipitate to obtain the hydrated ferric phosphate.
In a second aspect, the disclosure provides a cyclic oxidation precipitation system for implementing the step S3 described in the first aspect, including an oxidation iron precipitation tank, a solid-liquid separation device, and a solid slag washing tank, where the oxidation iron precipitation tank is provided with a cyclic oxidation system; the liquid inlet of the solid-liquid separation equipment is communicated with the lower part of the oxidation iron precipitation tank, the liquid outlet of the solid-liquid separation equipment is communicated with the top of the oxidation iron precipitation tank, and the slag discharging port of the solid-liquid separation equipment is communicated with the solid slag washing tank.
In an optional embodiment of the present application, the cyclic oxidation system includes a circulating pump and a venturi tube, wherein, the inlet of the circulating pump with oxidation heavy iron tank lower part UNICOM, the liquid outlet of the circulating pump with venturi tube's jet orifice UNICOM, venturi tube's liquid outlet with oxidation heavy iron tank's top UNICOM.
In a third aspect, embodiments provide a method of obtaining hydrated iron phosphate as described in the first aspect.
In an alternative embodiment of the present application, the aluminum content in the hydrated iron phosphate is less than or equal to 58ppm.
In a fourth aspect, embodiments of the present application provide a use of the method of the first aspect for treating spent batteries.
The beneficial effects are that:
the inventor of the application finds that when ferrous iron is oxidized at a lower pH value, ferric iron can generate sediment in preference to aluminum ions, so that phosphorus iron compound sediment with extremely low aluminum content (less than 100 ppm) can be obtained, wherein the aluminum content can meet the requirement of battery-grade ferric phosphate; however, at lower pH values (especially pH values less than 1.2), the iron phosphate still has considerable solubility, making it difficult to precipitate completely, which directly affects the recovery of the iron phosphate, so, in order to greatly reduce the aluminum content in the iron phosphate compound and maximize the recovery of the iron phosphate compound, the present application performs iron precipitation by using staged pH adjustment, i.e. by first round adjustment of pH to a lower range (0.4-1.2), at which time the iron preferentially precipitates aluminum, obtaining high purity iron phosphate compound precipitates (i.e. the iron phosphate slag, possibly containing iron phosphate, iron monohydrogen phosphate, iron dihydrogen phosphate, etc.), during which a large amount of phosphate ions react with the iron ions to be precipitated, and the concentration of phosphate ions remaining in the solution is greatly reduced; the second round of iron precipitation is then carried out by adjusting the pH by the secondary round to a relatively high range (1.5-2.0) where the solubility of the iron phosphate is very low and the remaining iron ions precipitate almost entirely in the form of iron phosphate to form new iron phosphate compounds (the composition being based on iron phosphate), whereas in this stage the co-precipitation of aluminium becomes very weak as the phosphate ion concentration has fallen to very low levels, ensuring maximum recovery of iron phosphate compounds with very little aluminium precipitation.
In order to achieve better iron precipitation effect, the first-round adjustment pH value and the second-round adjustment pH value can be step-by-step adjustment, namely, the pH value is adjusted to a specific pH value within a preset range, solid-liquid separation is carried out after the iron concentration in the solution is stabilized, the filtrate enters the next-step pH value adjustment, the circulation is carried out until the adjustment of the first-round adjustment is finished, the specific steps can be determined according to actual conditions, fine grading precipitation of iron ions is achieved, each solid-liquid separation can effectively promote the precipitation reaction of the next-step more thoroughly, the iron precipitation effect of each-round pH value adjustment can be exerted to the greatest extent, further improvement of the recovery rate of the iron phosphate compounds is facilitated, and particularly, the iron content in the final filtrate subjected to all pH value adjustment can be less than 1g/L.
The aluminum impurity contained in the iron phosphate compound obtained by the method provided by the application is extremely low, the purity is higher, and the requirement on the aluminum content in the battery-level iron phosphate can be completely met.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained from these drawings without inventive effort for a person skilled in the art.
For a more complete understanding of the present application and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts throughout the following description.
Fig. 1 is a schematic structural diagram of an iron precipitation device in a system for preparing a phosphorus iron compound according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses, to other embodiments, and all other embodiments, which may be contemplated by those skilled in the art to which the application pertains without inventive faculty, are contemplated as falling within the scope of the application.
Reference herein to "an embodiment" or "an implementation" means that a particular feature, structure, or characteristic described in connection with the embodiment or implementation may be included in at least one embodiment of the present application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
For the aluminum removal process in the treatment process of the waste lithium iron phosphate battery, a pretreatment or post-treatment method is generally adopted, if the pretreatment method is adopted, a large amount of sodium metaaluminate solution can be generated, and the aluminum removal effect is not ideal due to the existence of carbon powder; if a post-treatment method is adopted, the production cost can be increased, or new impurities can be introduced. At present, although the above drawbacks can be overcome to some extent, the present application found that, since the solubility of iron phosphate and aluminum phosphate is actively close, co-precipitation is easily formed between them, and thus there is still no better solution for how to avoid the introduction of aluminum impurities into iron phosphate and still ensure the yield of iron phosphate.
In the method for preparing the phosphorus-iron compound by using the waste lithium iron phosphate battery, provided by the application, only in the iron precipitation step, the pH value of the solution is adjusted, so that the phosphorus in the solution always keeps low pH value or low concentration, iron-aluminum coprecipitation can be avoided, the finally obtained phosphorus-iron compound can meet the requirement of battery-grade iron phosphate, the yield of the phosphorus-iron compound is higher, and the increase of cost is avoided.
The embodiment of the application provides a method for recovering a phosphorus-iron compound from a waste lithium iron phosphate battery, which comprises the following steps:
S1: acid leaching is carried out on the waste lithium iron phosphate battery powder, and leaching liquid is obtained after solid-liquid separation;
s2: copper and aluminum removal treatment is carried out on the leaching solution, and copper and aluminum removal solution is obtained after solid-liquid separation;
s3: and (3) regulating the iron-phosphorus ratio of the copper-removing aluminum solution, performing first-round regulation to the pH value of 0.4-1.2, adding an oxidant, performing solid-liquid separation to obtain ferrophosphorus slag and filtrate, performing second-round regulation to the pH value of 1.5-2.0 on the filtrate, continuously adding the oxidant, performing solid-liquid separation to obtain ferrophosphorus slag and final filtrate, merging the ferrophosphorus slag, washing and drying to obtain the ferrophosphorus compound.
The pH value of 0.4-1.2 can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, etc., and the pH value of 1.5-2 can be 1.6, 1.7, 1.8, 1.9, etc.
The application provides a preparation method of a phosphorus iron compound, in particular to a method for recycling and preparing a phosphorus iron compound capable of meeting the requirements of battery-grade ferric phosphate from waste lithium iron phosphate batteries. In the method provided by the application, the waste lithium iron phosphate battery powder is subjected to acid leaching, copper removal, aluminum removal and iron precipitation, so that the phosphorus iron compound meeting the requirements of battery-grade iron phosphate can be obtained. In the step of iron precipitation, the pH value of the solution is firstly adjusted to be in a low pH value environment, ferrous ions are oxidized and precipitated under the low pH value, the aluminum content in the obtained phosphorus iron compound is extremely low, and then the pH value is adjusted to be high, at the moment, the phosphate radical concentration is low, and the generation of aluminum phosphate precipitation can be avoided, so that the aluminum-iron coprecipitation can be avoided to a great extent through the method provided by the application, and the battery-grade iron phosphate with extremely high purity is obtained. Meanwhile, the method provided by the disclosure is simple in preparation process, and the yield of the phosphorus-iron compound is higher, so that the method has a better application prospect.
For step S1: and (3) carrying out acid leaching on the waste lithium iron phosphate battery powder, and carrying out solid-liquid separation to obtain leaching liquid.
The lithium iron phosphate battery powder can be carbon-containing iron phosphate slag or non-carbon-containing iron phosphate slag, and particularly can be iron phosphate slag left after waste lithium iron phosphate positive electrode materials collected from waste lithium ion batteries pass through a lithium element recovery process, and generally contains carbon powder and impurities such as partial aluminum oxide, copper oxide and the like. The collected iron phosphate slag may be crushed to form iron phosphate slag powder before acid leaching treatment for better acid leaching.
In a specific embodiment of the present application, the acid leaching may be performed by using an inorganic acid, and specifically, the step of leaching the waste lithium iron phosphate battery powder to obtain a leachate includes: the iron phosphate slag and the inorganic acid liquid are mixed according to the liquid-solid ratio of 1 (4-10), such as 1:5, 1:6, 1:7 and 1: mixing 8, 1:9, and the like, continuously leaching for 6-12h, such as 7h, 8h, 9h, 10h, 11h, and the like under the conditions of 40-90 ℃, such as 45 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ and the like, and then performing filter pressing for solid-liquid separation to obtain carbon powder and leaching liquid. Wherein, the unit of liquid-solid ratio is mL: the inorganic acid solution is at least one selected from hydrochloric acid solution, sulfuric acid solution and phosphoric acid solution, and for example, 2.2-2.6mol/L sulfuric acid solution, such as 2.3mol/L sulfuric acid solution, 2.4mol/L sulfuric acid solution, 2.5mol/L sulfuric acid solution and the like, is mixed with the iron phosphate slag according to the liquid-solid ratio for acid leaching, so that iron, copper, aluminum and the like in the iron phosphate slag can be leached out with high efficiency.
Further, in the acid leaching treatment process, the leaching rate can be increased with the aid of stirring at a stirring speed of 100-300rpm/min, for example, 150rpm/min, 200rpm/min, 250rpm/min and the like, the leaching rate is 99.5% or more as the leaching end point, the leaching solution obtained by filtering the iron-copper-aluminum-containing phosphatic iron can be understood as an initial leaching solution, and the carbon-containing iron phosphate slag is filtered at this time to obtain a solid carbon-containing powder filter residue.
For step S2: carrying out copper removal and aluminum removal treatment on the leaching solution, and carrying out solid-liquid separation to obtain copper-aluminum removal solution, wherein the copper-aluminum removal solution comprises the following components:
s21 (displacement decoppering): adding a measured part of iron powder into the leaching solution to carry out a displacement reaction to obtain a copper removal solution;
s22 (neutralization precipitation dealumination): adding a reducing agent into the copper removal solution, regulating the pH value to 2.5-3.5 by using a pH regulator, and carrying out precipitation and solid-liquid separation to obtain the copper removal aluminum solution.
In a specific embodiment of the present application, the step of adding a metered portion of iron powder to the leachate to perform a displacement reaction to obtain a copper removal solution includes: according to the mole ratio of copper ions and iron powder contained in the leaching solution being 1 (1.2-1.5), such as 1:1.3, 1:1.4, iron powder is added into the leaching solution, substitution reaction is carried out under the conditions of 40-90 ℃, such as 45 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ and the like, and the copper removal solution is obtained by filtration.
In a specific embodiment of the present application, the reaction time of the displacement reaction is about 1-5 hours, for example, 2 hours, 3 hours, 4 hours, etc., specifically, the displacement reaction may be performed under stirring conditions of 100-300r/min, for example, 150rpm/min, 200rpm/min, 250rpm/min, etc., and after the reaction is finished, the copper simple substance may be removed by a suction filtration separation method, etc.
The purpose of adding the iron powder is to remove copper ions contained in the leaching solution in a displacement reaction mode, the copper ions can be precipitated in a copper simple substance mode, the iron powder is selected because the iron powder is used as a reducing agent, the introduction of other elements can be avoided, and the addition of excessive iron powder can ensure the complete reaction of the copper ions and avoid the generation of ferric ions, so that the iron ions in the solution are always in a divalent state.
In a specific embodiment of the present application, adding an excessive amount of reducing agent to the copper removal solution and adjusting the pH to 2.5-3.5 by using a pH adjustor, and performing precipitation and solid-liquid separation to obtain the copper removal aluminum solution, wherein the steps of: iron powder, sodium sulfide or sodium persulfate and the like are added into the copper removal solution as reducing agents, and meanwhile, pH value of the solution is regulated to be 2.5-3.5 by utilizing pH regulators, such as 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4 and the like, aluminum precipitation reaction and solid-liquid separation are carried out, so that the copper removal aluminum solution is obtained.
In an embodiment, the iron powder is added in an amount of 0.1 to 0.5wt%, for example, 0.2wt%, 0.3wt%, 0.4wt%, etc., and the pH adjustor is selected from alkaline substances such as sodium hydroxide, ammonia water, lithium phosphate, lithium carbonate, sodium carbonate, calcium hydroxide, calcium oxide, etc., and the aluminum precipitation reaction may be performed under stirring conditions of 40 to 90 ℃, for example, 45 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, etc., for 1 to 5 hours, for example, 2 hours, 3 hours, 4 hours, etc., specifically, 100 to 300r/min, for example, 150rpm/min, 200rpm/min, 250rpm/min, etc., so that aluminum is better precipitated.
In a specific embodiment of the present application, the copper removal solution is subjected to an aluminum precipitation reaction that removes not only a substantial amount of aluminum, but also other metals that may be presentImpurity ions, for example, if titanium (Ti) ions are present, the above-described conditional precipitation of aluminum essentially completely precipitates the titanium ions out, if Ca is also present 2+ 、Mg 2+ And plasma can realize partial precipitation, and the impurity ions are removed in the aluminum precipitation process, so that the purity of the subsequent ferrophosphorus compound product can be further improved, and the product quality is improved.
For step S3: and (3) regulating the iron-phosphorus ratio of the copper-removing aluminum solution, performing first-round regulation to the pH value of 0.4-1.2, adding an oxidant, performing solid-liquid separation to obtain ferrophosphorus slag and filtrate, performing second-round regulation to the pH value of 1.5-2.0 on the filtrate, continuously adding the oxidant, performing solid-liquid separation to obtain ferrophosphorus slag and final filtrate, merging the ferrophosphorus slag, washing and drying to obtain the ferrophosphorus compound.
K based on ferric phosphate sp ＝1.3×10 -22 It is known that, in theory, the copper-removing aluminum solution has partial precipitation and is not completely dissolved under the condition that the pH value is 0.4-1.2, so that if the iron precipitation reaction is carried out within the pH value range of 0.4-1.2, iron phosphate cannot be completely precipitated, waste of the iron phosphate is caused, and the production cost is increased. And K of aluminium phosphate sp ＝9.84×10 -21 The solubility product constants of the ferric phosphate and the aluminum phosphate are very close, so that the ferric phosphate and the aluminum phosphate are extremely easy to co-precipitate, and the solubility product constants are also the main reason for the excessive aluminum content in the preparation of the ferric phosphate by utilizing the waste lithium iron phosphate battery at present.
However, the application finds that although the iron phosphate cannot be completely precipitated under the condition of the pH value of 0.4-1.2, the iron phosphate is prepared by oxidizing ferrous iron within the pH value range, and the aluminum content in the obtained iron phosphate is extremely low and can reach 100ppm or even below 60ppm, so that the requirement of the battery-grade iron phosphate is satisfied. The reason for this is presumably because the phosphate ions obtained by ionization of phosphoric acid at low pH are not high, and because the aluminum removal step has been performed in the present application, aluminum in solution is at a relatively low level, which causes ferrous iron to precipitate only as ferric phosphate rather than as aluminum phosphate during oxidation, thus effectively avoiding iron aluminum co-precipitation.
Based on this, the application provides a method for precipitating iron, first, the pH value is adjusted to be 0.4-1.2, in the range of 0.4-1.2, part of ferrous iron in the solution is continuously precipitated in the form of ferrophosphorus slag (possibly containing ferric phosphate, ferric hydrogen phosphate, ferric dihydrogen phosphate and the like) in the oxidation process, and aluminum impurities contained in the ferrophosphorus slag are extremely low, solid-liquid separation is carried out, the precipitated ferrophosphorus slag is separated, at the moment, the total phosphorus concentration in the solution is at a low level, and then after the pH value is adjusted to be 1.5-2.0 through the secondary wheel, the solubility product condition of aluminum phosphate precipitation is not met, so that the ferrophosphorus slag (the component is mainly composed of ferric phosphate) can be continuously precipitated and aluminum contained in the solution cannot be co-precipitated with iron ions, and the prepared ferrophosphorus compound can be ensured to completely meet the requirement on the aluminum content in battery-level ferric phosphate.
In a specific embodiment of the present application, the secondary adjustment of pH in step S3 is a stepwise adjustment performed in order of low pH to high pH. The adjustment mode can realize fine grading precipitation of iron ions, solid-liquid separation of each round can effectively promote the subsequent precipitation reaction to be more thorough, further plays the effect of iron precipitation of each round of pH value adjustment to the maximum extent, and is beneficial to further improving the recovery rate of the iron phosphate compound.
In the specific embodiment of the present application, the first round of adjustment of the pH value of the copper-removing aluminum solution to be 0.4-1.2 and the oxidation reaction of ferrous ions may be performed step by step, including but not limited to one or more times of adjustment, where the pH value of the last adjustment is higher than the pH value of the previous adjustment, and this adjustment method can ensure that when the pH value is in the range of 0.4-1.2, the precipitation of iron ions is performed to consume as much phosphate ions as possible, and finally the pH value is adjusted to be 1.5-2.0, where the total phosphorus content in the solution is low enough to make aluminum form aluminum phosphate precipitates, and the basically generated precipitates are all phosphorus iron compounds.
In the specific embodiment of the present application, the process of adjusting the pH value of the copper-removing aluminum solution to 1.5-2.0 by the secondary wheel may also be performed step by step, including but not limited to one or more times of adjustment, where the pH value of the subsequent adjustment is higher than that of the previous adjustment.
In a specific embodiment of the present application, for the step S3, the iron to phosphorus ratio is (0.96-1.02): 1, e.g., 0.97:1, 0.98:1, 0.99:1, 1:1, 1.01:1, etc. The sequence of the step of adjusting the pH value and the step of adjusting the iron-phosphorus ratio in the application is not strictly specified, and the pH value of the copper-removing aluminum solution is ensured to be 0.4-1.2 and the iron-phosphorus ratio is (0.96-1.02): 1 mainly before ferrous oxide.
Further, in the above-mentioned process of adjusting the ratio of phosphorus to iron, the adjustment may be performed by using a trivalent iron salt or a phosphorus source, the trivalent iron salt being selected from at least one of anhydrous ferric sulfate, ferric sulfate hydrate, anhydrous ferric chloride, ferric chloride hydrate, and ferric nitrate; the phosphorus source is at least one selected from phosphoric acid, monoammonium phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, monoammonium phosphate, sodium dihydrogen phosphate, sodium phosphate, potassium phosphate and ammonium phosphate.
Further, in the step S3, the regulator for regulating the pH value in the first round is at least one selected from sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid; the regulator for regulating the pH value of the secondary wheel is at least one selected from sodium hydroxide, ammonia water, lithium phosphate, lithium carbonate, sodium carbonate, calcium hydroxide or calcium oxide.
Further, the oxidant is added continuously in step S3.
In the specific embodiment of the application, the oxidant used in the oxidation reaction of ferrous ions can be selected from air or oxygen, air or oxygen is introduced into the regulated copper-removing aluminum solution, the solution is fully contacted with the air or oxygen by utilizing aeration equipment, ferrous ions are fully oxidized into ferric ions, in the process, the copper-removing aluminum solution is circulated through a circulating pump, a venturi tube and an oxidation ferric precipitation tank, the air or oxygen is fully mixed with the solution to perform aeration treatment, so that ferrous ions in the solution are oxidized into ferric ions due to the existence of oxygen, and then the ferric ions are subjected to ferric precipitation treatment under certain conditions, so that high-purity ferric phosphate dihydrate can be obtained, and the air or oxygen is used as the oxidant without adding the oxidant in the reaction kettle, so that the high-purity ferric phosphate dihydrate can be obtained at low cost.
Specifically, the process of adjusting the pH value to 1.5-2.0 to form solid precipitate can be carried out at 40-90 ℃, such as 45 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ and the like for 3-5 hours, such as 3.5 hours, 4.0 hours, 4.5 hours and the like, specifically can be carried out under the stirring condition of 100-300r/min, such as 150rpm/min, 200rpm/min, 250rpm/min and the like for 3-5 hours, and finally, the ferric phosphate dihydrate is obtained by filtration and separation.
Further, the iron precipitation reaction in step S3 may be performed in a cyclic oxidation precipitation system, as shown in fig. 1, where the cyclic oxidation precipitation system includes an oxidation iron precipitation tank, a solid-liquid separation device, and a solid slag washing tank, and the oxidation iron precipitation tank is provided with a cyclic oxidation system; the liquid inlet of the solid-liquid separation device is communicated with the lower part of the oxidation iron precipitation tank, the liquid outlet of the solid-liquid separation device is communicated with the top of the oxidation iron precipitation tank, and the slag outlet of the solid-liquid separation device is communicated with the solid slag washing tank.
In the concrete embodiment of this application, circulation oxidation precipitation system has still included circulating pump and venturi, and wherein, the inlet and the oxidation of circulating pump sink iron groove lower part UNICOM, the liquid outlet and the jet orifice UNICOM of venturi of circulating pump, the liquid outlet and the top UNICOM of oxidation of venturi sink iron groove.
In a cyclic oxidation precipitation system, copper-aluminum removal solution is internally circulated through a circulation pump, a venturi tube and an oxidation iron precipitation tank, wherein air (oxidant) can be introduced into the venturi suction tube through at least one opening, and a liquid phase stream can be introduced into the venturi jet tube through at least one opening. The venturi tube comprises a venturi jet tube and a venturi suction tube, so that the solution is mixed with air sucked by the venturi suction tube when flowing through the venturi tube and then is ejected from the venturi jet tube, so that gas and liquid are fully mixed to perform aeration treatment, and ferrous ions in the solution are completely changed into ferric ions due to the existence of oxygen in the air.
In the specific embodiment of the application, after the iron precipitation reaction is carried out, the iron content of the obtained final filtrate is less than 1g/L.
Further, the specific embodiment of the present application further includes step S4: and (3) preparing slurry by utilizing the phosphorus iron compound, regulating the pH value of the slurry to be not less than 2.3, and washing and drying the obtained precipitate to obtain the hydrated ferric phosphate.
In a specific embodiment of the present application, after the iron phosphate compound is obtained in step S3, a step of post-treating the iron phosphate compound to obtain hydrated iron phosphate is further included. Specifically: preparing slurry by using the ferrophosphorus compound, adjusting the pH value of the slurry to be not less than 2.3, such as 2.5, 3, 3.5, 4, 5, 6, 7 and the like, washing the slurry, performing heat treatment at 300-800 ℃ to obtain hydrated ferric phosphate, and roasting the hydrated ferric phosphate for 2-12h, such as 3h, 4h, 5h, 6h, 8h, 10h, 11h and the like at 300-800 ℃, such as 400 ℃, 500 ℃, 600 ℃, 700 ℃ and the like, and performing post-treatment (such as crushing) after roasting and combining to obtain the battery-grade hydrated ferric phosphate.
Further, the hydrated ferric phosphate prepared by the preparation method of the embodiment of the application can be further processed into anhydrous ferric phosphate, and the preparation method further comprises the step of performing carbothermal reduction after mixing the anhydrous ferric phosphate with a lithium source and a carbon source to obtain lithium iron phosphate. The prepared hydrated ferric phosphate can be used as a positive electrode active material of a lithium ion battery to generate lithium iron phosphate. The lithium source may be lithium carbonate, lithium nitrate, or the like, and the carbon source may be an organic substance such as glucose. The lithium iron phosphate-based lithium iron phosphate is prepared by the preparation method of the embodiment of the application, and is low in cost and high in purity, so that the cost of the lithium iron phosphate serving as the positive electrode active material can be reduced.
In a second aspect, the present disclosure provides a cyclic oxidation precipitation system for implementing step S3 of the first aspect, as shown in fig. 1, including an oxidation-precipitation iron tank, a solid-liquid separation device, a solid slag washing tank, a circulating pump, and a venturi tube, wherein the oxidation-precipitation iron tank is provided with the cyclic oxidation system; the liquid inlet of the solid-liquid separation device is communicated with the lower part of the oxidation iron sedimentation tank, the liquid outlet of the solid-liquid separation device is communicated with the top of the oxidation iron sedimentation tank, the slag outlet of the solid-liquid separation device is communicated with the solid slag washing tank, the liquid inlet of the circulating pump is communicated with the lower part of the oxidation iron sedimentation tank, the liquid outlet of the circulating pump is communicated with the jet orifice of the venturi tube, and the liquid outlet of the venturi tube is communicated with the top of the oxidation iron sedimentation tank.
In a third aspect, embodiments provide a method of obtaining hydrated iron phosphate as described in the first aspect.
In an alternative embodiment of the present application, the aluminum content in the hydrated iron phosphate is less than or equal to 58ppm, such as 50ppm, 45ppm, 40ppm, etc.
According to the method, the phosphorus in the iron precipitation reaction is controlled to keep low concentration or low pH value, so that iron-aluminum coprecipitation can be avoided to the greatest extent, and therefore, the content of aluminum impurities in the finally prepared hydrated ferric phosphate is extremely low, and the application requirements of battery-level ferric phosphate are satisfied sufficiently.
In a fourth aspect, embodiments of the present application provide a use of the method of the first aspect for treating spent batteries.
The following description is made with reference to specific embodiments.
Example 1
The embodiment provides a method for recycling a phosphorus-iron compound from a waste lithium iron phosphate battery, which comprises the following steps:
s1 (acid leaching step):
1000g of waste lithium iron phosphate battery powder and 2.5mol/L sulfuric acid are mixed according to a solid-to-liquid ratio of 4:1, and then stirred at 80 ℃ at 300rpm/min, and stirred and leached for 12 hours; and taking the leaching rate of lithium ions of more than 99% as a leaching end point, and filtering after the acid leaching is finished to obtain leaching liquid and carbon powder.
S21 (copper removal step):
1000mL of leaching solution (copper ion concentration is 4.8 g/L) is taken, 5.1g of reduced iron powder is added, stirring is carried out for 2 hours at room temperature (25-30 ℃), the stirring speed is 150rpm/min, copper ions are recovered in the form of copper simple substance products after the reaction is finished, and excessive iron powder is dissolved in the pickling solution to obtain copper removal solution, wherein the copper removal solution comprises the following components: the ferrous ion concentration is 34.2g/L, the aluminum ion concentration is 4.3g/L, and the phosphorus ion concentration is 18.6g/L.
S22 (aluminum removal step):
taking 800mL of the copper-removed solution, adding 6g of reduced iron powder, stirring at room temperature at a stirring speed of 200rpm/min, then adding sodium hydroxide solution, adjusting the pH to 2.5, and stirring for 120min in total. Filtering after the reaction is finished to obtain aluminum slag and copper-aluminum removing solution.
S3 (iron deposition step):
taking 600mL of solution after aluminum removal, adding 12.7g of phosphoric acid with 85% content to regulate the iron-phosphorus ratio to 1:1.02, simultaneously adding 2.5mol/L of sulfuric acid to regulate the pH value to 1.0 in a first round, continuously introducing oxygen, stirring for 30min at 70 ℃, wherein the stirring speed is 300rpm/min, filtering to perform solid-liquid separation when the total iron concentration in the solution is no longer changed, collecting and washing a filter cake, returning the filter cake to a container, adding liquid alkali to regulate the pH value in a second round, firstly regulating the pH value to 1.5, continuing introducing oxygen to precipitate, keeping the total iron concentration in the solution unchanged, performing solid-liquid separation, washing a filter cake, returning the filter cake, repeatedly regulating the pH value to 2.0, and obtaining the filter cake and the filter cake after the total iron concentration in the solution is no longer changed. And combining the three filter cakes, washing and drying to obtain the low-aluminum-content ferrophosphorus compound.
S4 (conversion step):
and (3) preparing slurry by utilizing the phosphorus iron compound, regulating the pH value of the slurry to be 2.5, and washing and drying the obtained precipitate to obtain the ferric phosphate dihydrate.
The S3 (iron precipitation step) is carried out in a circulating oxidation precipitation system, the circulating oxidation precipitation system comprises an oxidation iron precipitation tank, solid-liquid separation equipment and a solid slag washing tank, wherein a circulating oxidation system is arranged on the oxidation iron precipitation tank and comprises a circulating pump and a venturi tube, a liquid inlet of the circulating pump is communicated with the lower part of the oxidation iron precipitation tank, a liquid outlet of the circulating pump is communicated with an injection port of the venturi tube, and a liquid outlet of the venturi tube is communicated with the top of the oxidation iron precipitation tank; the liquid inlet of the solid-liquid separation equipment is communicated with the lower part of the oxidation iron precipitation tank, the liquid outlet of the solid-liquid separation equipment is communicated with the top of the oxidation iron precipitation tank, and the slag discharging port of the solid-liquid separation equipment is communicated with the solid slag washing tank. The cyclic oxidative precipitation system is also used in the remaining embodiments of the present invention.
Example 2
The embodiment provides a method for recycling a phosphorus-iron compound from a waste lithium iron phosphate battery, which comprises the following steps:
s1 (acid leaching step):
1000g of waste lithium iron phosphate battery powder and 2.5mol/L sulfuric acid are mixed according to a solid-to-liquid ratio of 4:1, and then stirred at 80 ℃ at 300rpm/min, and stirred and leached for 12 hours; and taking the leaching rate of lithium ions of more than 99% as a leaching end point, and filtering after the acid leaching is finished to obtain leaching liquid and carbon powder.
S21 (copper removal step):
1000mL of leaching solution (copper ion concentration is 4.8 g/L) is taken, 5.1g of reduced iron powder is added, stirring is carried out for 2 hours at room temperature (25-30 ℃), the stirring speed is 150rpm/min, copper ions are recovered in the form of copper simple substance products after the reaction is finished, and excessive iron powder is dissolved in the pickling solution to obtain copper removal solution, wherein the copper removal solution comprises the following components: the ferrous ion concentration is 34.2g/L, the aluminum ion concentration is 4.3g/L, and the phosphorus ion concentration is 18.6g/L.
S22 (aluminum removal step):
taking 800mL of the copper-removed solution, adding 6g of reduced iron powder, stirring at room temperature at a stirring speed of 200rpm/min, then adding sodium hydroxide solution, adjusting the pH to 2.5, and stirring for 120min in total. Filtering after the reaction is finished to obtain aluminum slag and copper-aluminum removing solution.
S3 (iron deposition step):
taking 600mL of solution after aluminum removal, adding 12.7g of phosphoric acid with 85% content to regulate the iron-phosphorus ratio to 1:1.02, then adding 2.5mol/L of sulfuric acid to carry out first-round pH value regulation, firstly regulating the pH value to 1.2, continuously introducing oxygen, stirring for 30min at 70 ℃, wherein the stirring speed is 300rpm/min, filtering to carry out solid-liquid separation when the total iron concentration in the solution is not changed, collecting and washing a filter cake, and returning filtrate to a container again; then adding liquid alkali into the filtrate to carry out secondary round adjustment of the pH value to 2.0, wherein the specific operation method can refer to the secondary round adjustment of the pH value method in the embodiment 1, so as to obtain the final filtrate and a filter cake. And combining the filter cakes twice, washing and drying to obtain the low-aluminum-content ferrophosphorus compound.
S4 (conversion step):
and (3) preparing slurry by utilizing the ferrophosphorus compound, regulating the pH value of the slurry to be 2.3, and washing and drying the obtained precipitate to obtain the ferric phosphate dihydrate.
Example 3
The embodiment provides a method for recycling a phosphorus-iron compound from a waste lithium iron phosphate battery, which comprises the following steps:
s1 (acid leaching step):
1000g of waste lithium iron phosphate battery powder and 2.5mol/L sulfuric acid are mixed according to a solid-to-liquid ratio of 4:1, and then stirred at 80 ℃ at 300rpm/min, and stirred and leached for 12 hours; and taking the leaching rate of lithium ions of more than 99% as a leaching end point, and filtering after the acid leaching is finished to obtain leaching liquid and carbon powder.
S21 (copper removal step):
1000mL of leaching solution (copper ion concentration is 4.8 g/L) is taken, 5.1g of reduced iron powder is added, stirring is carried out for 2 hours at room temperature (25-30 ℃), the stirring speed is 150rpm/min, copper ions are recovered in the form of copper simple substance products after the reaction is finished, and excessive iron powder is dissolved in the pickling solution to obtain copper removal solution, wherein the copper removal solution comprises the following components: the ferrous ion concentration is 34.2g/L, the aluminum ion concentration is 4.3g/L, and the phosphorus ion concentration is 18.6g/L.
S22 (aluminum removal step):
taking 800mL of the copper-removed solution, adding 6g of reduced iron powder, stirring at room temperature at a stirring speed of 200rpm/min, then adding sodium hydroxide solution, adjusting the pH to 2.5, and stirring for 120min in total. Filtering after the reaction is finished to obtain aluminum slag and copper-aluminum removing solution.
S3 (iron deposition step):
taking 600mL of solution after aluminum removal, adding 12.7g of phosphoric acid with the content of 85% to regulate the iron-phosphorus ratio to 1.02:1, adding 2.5mol/L of sulfuric acid to regulate the pH value to 0.8 in the first round, continuously introducing oxygen, stirring for 30min at 70 ℃, stirring at the speed of 300rpm/min, filtering to perform solid-liquid separation when the total iron concentration in the solution is no longer changed, collecting and washing a filter cake, returning the filter cake to a container, adding liquid alkali to perform secondary round to regulate the pH value, firstly regulating the pH value to 1.5, continuing introducing oxygen to precipitate, keeping the total iron in the solution unchanged, performing solid-liquid separation, washing a filter cake, returning the filter cake, repeatedly regulating the pH value to 2.0, keeping the total iron in the solution unchanged, performing solid-liquid separation, and obtaining a final filter cake and a filter cake. And combining the three filter cakes, washing and drying to obtain the low-aluminum-content ferrophosphorus compound.
S4 (conversion step):
and (3) preparing slurry by utilizing the ferrophosphorus compound, regulating the pH value of the slurry to be 2.4, and washing and drying the obtained precipitate to obtain the ferric phosphate dihydrate.
Comparative example 1
The comparative example provides a method for recovering a phosphorus-iron compound from a waste lithium iron phosphate battery.
The difference from example 1 is that step S3 is:
Taking 600mL of solution after aluminum removal, adding 12.7g of phosphoric acid with 85% content to regulate the iron-phosphorus ratio to 1:1.02, then adding 2.5mol/L of sulfuric acid to regulate the pH value to 1.0, continuously introducing oxygen, stirring for 30min at 70 ℃, wherein the stirring speed is 300rpm/min, and after the total iron in the solution is not changed, carrying out solid-liquid separation, washing a filter cake and returning filtrate. Continuously adding 6.2g of phosphoric acid with the content of 85%, regulating the iron-phosphorus ratio to 1.02, adding liquid alkali, repeatedly regulating the pH value to 2.0, and carrying out solid-liquid separation until the total iron in the solution is unchanged, thereby obtaining filtrate and filter cake. And combining the three filter cakes, washing and drying to obtain the low-aluminum-content ferrophosphorus compound.
In the comparative example, although the pH value of the first round and the pH value of the second round are adjusted, phosphoric acid is supplemented before the pH value of the second round, namely the phosphorus content in the solution is recovered, and then the pH value of the second round is adjusted to precipitate iron, so that the aim of comparing the influence of the phosphorus content in the solution on the aluminum and iron precipitation process is achieved.
Comparative example 2
The comparative example provides a method for recovering a phosphorus-iron compound from a waste lithium iron phosphate battery.
The difference from example 1 is that step S3 is:
taking 600mL of solution after aluminum removal, adding 12.7g of phosphoric acid with 85% content to regulate the iron-phosphorus ratio to 1:1.02, then adding 2.5mol/L of sulfuric acid to regulate the pH value to 1.0, continuously introducing oxygen, stirring for 30min at 70 ℃, wherein the stirring speed is 300rpm/min, adding liquid alkali to regulate the pH value to 2.0 after the ferric iron in the solution is completely oxidized into ferric iron, filtering to perform solid-liquid separation, obtaining filtrate and filter cake, and drying the filter cake after washing to obtain the ferrophosphorus compound.
In the comparative example, solid-liquid separation is not carried out in the first round of pH value adjustment, and then the reaction liquid directly enters into the secondary round of pH value adjustment, namely, the phosphorus iron slag is not separated after the reaction of the first round of pH value adjustment is finished, and then the secondary round of pH value adjustment iron precipitation is directly carried out, so that the aim of comparing the influence of solid-liquid separation operation on the aluminum and iron precipitation process is achieved.
Comparative example 3
The comparative example provides a method for recovering a phosphorus-iron compound from a waste lithium iron phosphate battery.
The difference from example 1 is that step S3 is:
taking 600mL of solution after aluminum removal, adding 12.7g of phosphoric acid with 85% content to regulate the iron-phosphorus ratio to 1:1.02, adding 2.5mol/L of sulfuric acid to regulate the pH value to 2.0, continuously introducing oxygen, stirring for 30min at 70 ℃, wherein the stirring speed is 300rpm/min, filtering to perform solid-liquid separation when the total iron concentration in the solution is no longer changed, collecting a filter cake, washing, returning the filter cake to a container, regulating the pH value to 2.0, continuing introducing oxygen to precipitate, separating out the precipitate, washing the filter cake after the total iron in the solution is not changed, and drying to obtain the iron-phosphorus compound.
In the comparative example, the pH value is adjusted to be 2.0 which is higher when the pH value of the first round is adjusted, at the moment, the iron is settled in the first round, then the pH value is repeatedly adjusted to be the pH value for the secondary iron settlement, namely, the iron settlement is directly carried out at the higher pH value, and the aim of comparing the influence of the pH value of the solution on the coprecipitation process of aluminum and iron is achieved.
Comparative example 4
The present comparative example provides a method for preparing iron phosphate from waste lithium iron phosphate batteries with reference to CN116477591a, as follows:
(1) Acid leaching: in the first stage of leaching process, 290mL (mass fraction 98.3%) of concentrated sulfuric acid is poured into 3700mL of deionized water to prepare a leaching agent, 1000g of waste lithium iron phosphate positive electrode powder is slowly added into the leaching agent, stirring is carried out for 3.0h at 30 ℃, and solid-liquid separation is carried out to obtain a first stage of leaching solution (subsequent experimental raw materials) and a first stage of leaching slag (carrying out second stage leaching);
(2) Copper and aluminum removal: weighing 200mL of a first-stage leaching mixed solution, adding 1.2g of simple substance iron, stirring at 50 ℃ for 30min, and filtering to obtain filtrate, namely copper-removing solution;
respectively adding 2.1g of sodium hydroxide and 3.0g of iron simple substance into the copper-removed solution, immediately sealing and stirring, heating to 70 ℃ in a water bath after the sodium hydroxide is completely dissolved and uniformly stirred, stirring for 4.0h, and then carrying out solid-liquid separation to obtain a solution which is the aluminum-removed solution;
(3) And (3) iron deposition: 1000mL of mixed solution after aluminum removal is measured, ammonium phosphate is added into the solution after aluminum removal according to the ratio of the total iron to the total phosphorus substances in the solution after aluminum removal of 1:1.02, stirring is carried out until the ammonium phosphate solid is completely dissolved, the pH value is regulated to 0.8 by 1:1 dilute sulfuric acid, hydrogen peroxide solution with the theoretical dosage of 1.2 times is slowly added dropwise, the temperature is raised to 70 ℃ after the oxidation is complete, stirring is carried out at constant temperature for 24 hours, the suspension of hydrated ferric phosphate is obtained, and the precipitated Fe is obtained through liquid-solid separation 3+ And (5) the post-solution and a hydrated ferric phosphate filter cake, and drying the hydrated ferric phosphate to obtain the ferric phosphate.
In the comparative example, only a single pH adjustment was performed with sulfuric acid, i.e., iron precipitation was performed only in an environment with a low pH, in order to compare the influence of the pH adjustment on the yield of phosphorus and iron.
Performance testing
Elemental analysis and yield calculations were performed on the hydrated iron phosphate obtained in examples and comparative examples, and the results are shown in table 1:
TABLE 1
According to the embodiment and the performance test, the phosphorus iron compound prepared by the method provided by the application has extremely high purity and extremely low aluminum content, can meet the requirements of battery-grade ferric phosphate, has higher phosphorus iron yield, and avoids the waste of raw materials and the increase of cost.
As is clear from the comparison between the examples and the comparative example 1, the phosphorus content in the solution has a great influence on the coprecipitation of aluminum and iron during the iron precipitation step, and a great amount of aluminum precipitation can not be generated only in the environment of low phosphorus content by adjusting the pH value, so that iron can be selectively precipitated, and the yield and purity of the phosphorus-iron compound are improved. As can be seen from the comparison between the examples and the comparative example 2, the present application can avoid the influence of the obtained ferrophosphorus slag on the subsequent steps by adopting the manner of sinking iron at a proper pH value and performing solid-liquid separation in time, so that the iron-sinking reaction of each step obtains the best effect, because the obtained ferrophosphorus slag may contain ferric phosphate, ferric phosphate and other meta-acid precipitates during the first round of pH value adjustment process, if the obtained ferrophosphorus slag is not separated in time, the obtained ferrophosphorus slag can be redissolved during the subsequent round of pH value adjustment process, so that the phosphorus content in the solution cannot be effectively reduced, further the occurrence of iron-aluminum coprecipitation is caused, the aluminum content of the obtained ferrophosphorus slag is higher, and the obtained ferric phosphate meeting the battery level requirement is difficult to obtain later. As is clear from the comparison between the examples and the comparative example 3, the pH value has a larger influence on the coprecipitation process of aluminum and iron, and if iron is precipitated at a higher pH value (e.g. 2.0), the coprecipitation is easy to occur due to the similar iron and aluminum ion product constants, so that the aluminum content in the obtained iron-phosphorus compound product is higher, and the occurrence of the coprecipitation cannot be avoided even if the solid-liquid separation is performed in time in the iron precipitation process. And it is apparent from the comparison of examples and comparative example 4 that, although the co-precipitation of aluminum can be effectively prevented by performing the iron precipitation at a lower pH, it is unavoidable that a part of the iron precipitation is incomplete if the iron precipitation is performed only at a lower pH, and the recovery rate of the ferrophosphorus is seriously affected if the precipitation recovery is not further performed.
Therefore, the method provided by the application can not only effectively avoid coprecipitation of aluminum, but also ensure that ferrophosphorus is recovered to the maximum extent, and realize high-quality and high-benefit recovery of the waste lithium iron phosphate battery.
The above describes in detail the method for recovering the phosphorus iron compound from the waste lithium iron phosphate battery provided in the embodiment of the present application, and specific examples are applied herein to illustrate the principles and embodiments of the present application, and the above description of the examples is only used to help understand the method and core ideas of the present application; meanwhile, those skilled in the art will have variations in the specific embodiments and application scope in light of the ideas of the present application, and the present description should not be construed as limiting the present application in view of the above.
Claims (12)
1. A method for recovering a phosphorus-iron compound from a waste lithium iron phosphate battery, the method comprising:
s1: acid leaching is carried out on the waste lithium iron phosphate battery powder, and leaching liquid is obtained after solid-liquid separation;
s2: copper and aluminum removal treatment is carried out on the leaching solution, and copper and aluminum removal solution is obtained after solid-liquid separation;
s3: and (3) regulating the iron-phosphorus ratio of the copper-removing aluminum solution, performing first-round regulation to the pH value of 0.4-1.2, adding an oxidant, performing solid-liquid separation to obtain ferrophosphorus slag and filtrate, performing second-round regulation to the pH value of 1.5-2.0 on the filtrate, continuously adding the oxidant, performing solid-liquid separation to obtain ferrophosphorus slag and final filtrate, merging the ferrophosphorus slag, washing and drying to obtain the ferrophosphorus compound.
2. The method according to claim 1, wherein the iron to phosphorus ratio in step S3 is (0.96-1.02): 1.
3. The method according to claim 1, wherein the secondary wheel adjusting the pH in step S3 is a stepwise adjustment in order of pH from low to high.
4. The method according to claim 1, wherein the first-pass pH-adjusting agent in step S3 is at least one selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid; the regulator for regulating the pH value of the secondary wheel is at least one selected from sodium hydroxide, ammonia water, lithium phosphate, lithium carbonate, sodium carbonate, calcium hydroxide or calcium oxide.
5. The method according to claim 1, wherein the oxidant is added continuously in step S3.
6. The method according to claim 1, wherein the copper removal in step S2 is performed by replacing copper with iron powder;
and (2) removing aluminum by adopting a neutralization precipitation, wherein the neutralization precipitation is performed under the following conditions: on the premise of excessive reducing agent, the pH value is regulated to 2.5-3.5;
the reducing agent is iron powder; or the reducing agent comprises iron powder, and the reducing agent further comprises at least one of sodium sulfide and sodium persulfate.
7. The method according to any one of claims 1-6, wherein the final filtrate in step S3 has an iron content of less than 1g/L.
8. The method according to any one of claims 1-6, further comprising step S4: and (3) preparing slurry by utilizing the phosphorus iron compound, regulating the pH value of the slurry to be not less than 2.3, and washing and drying the obtained precipitate to obtain the hydrated ferric phosphate.
9. A circulating oxidation precipitation system for implementing the step S3 of any one of claims 1 to 8, and is characterized by comprising an oxidation iron precipitation tank, a solid-liquid separation device and a solid slag washing tank, wherein the oxidation iron precipitation tank is provided with a circulating oxidation system; the liquid inlet of the solid-liquid separation equipment is communicated with the lower part of the oxidation iron precipitation tank, the liquid outlet of the solid-liquid separation equipment is communicated with the top of the oxidation iron precipitation tank, and the slag discharging port of the solid-liquid separation equipment is communicated with the solid slag washing tank.
10. The cyclic oxidation precipitation system of claim 9, comprising a circulation pump and a venturi, wherein a liquid inlet of the circulation pump is in communication with a lower portion of the iron oxide precipitation tank, a liquid outlet of the circulation pump is in communication with an injection port of the venturi, and a liquid outlet of the venturi is in communication with a top portion of the iron oxide precipitation tank.
11. A hydrated iron phosphate obtained by the process of claim 8 wherein the hydrated iron phosphate has an aluminum content of less than or equal to 58ppm.
12. Use of a method according to any one of claims 1 to 8 for the treatment of waste batteries.
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