CN118306960A - Method for preparing battery-grade ferric phosphate from pyrite cinder - Google Patents
Method for preparing battery-grade ferric phosphate from pyrite cinder Download PDFInfo
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- CN118306960A CN118306960A CN202410591226.7A CN202410591226A CN118306960A CN 118306960 A CN118306960 A CN 118306960A CN 202410591226 A CN202410591226 A CN 202410591226A CN 118306960 A CN118306960 A CN 118306960A
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- Prior art keywords
- pyrite cinder
- distilled water
- ferric phosphate
- impurity
- ferric
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- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 title claims abstract description 113
- 239000003818 cinder Substances 0.000 title claims abstract description 83
- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical compound [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 title claims abstract description 79
- 239000005955 Ferric phosphate Substances 0.000 title claims abstract description 78
- 229940032958 ferric phosphate Drugs 0.000 title claims abstract description 78
- 229910000399 iron(III) phosphate Inorganic materials 0.000 title claims abstract description 78
- 239000011028 pyrite Substances 0.000 title claims abstract description 78
- 229910052683 pyrite Inorganic materials 0.000 title claims abstract description 78
- 238000000034 method Methods 0.000 title claims abstract description 62
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 164
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 126
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 68
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 66
- 238000006243 chemical reaction Methods 0.000 claims abstract description 65
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 63
- 239000012535 impurity Substances 0.000 claims abstract description 54
- 238000000498 ball milling Methods 0.000 claims abstract description 45
- 229910052742 iron Inorganic materials 0.000 claims abstract description 27
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 25
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 25
- 239000002253 acid Substances 0.000 claims abstract description 15
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 11
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims abstract description 9
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims abstract description 8
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000011574 phosphorus Substances 0.000 claims abstract description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 6
- 239000012153 distilled water Substances 0.000 claims description 108
- 238000005406 washing Methods 0.000 claims description 85
- 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 claims description 81
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 81
- 239000000706 filtrate Substances 0.000 claims description 68
- 238000001914 filtration Methods 0.000 claims description 58
- 239000012065 filter cake Substances 0.000 claims description 57
- 238000001035 drying Methods 0.000 claims description 51
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 45
- 238000000227 grinding Methods 0.000 claims description 44
- 239000000463 material Substances 0.000 claims description 44
- 239000002893 slag Substances 0.000 claims description 40
- 238000003756 stirring Methods 0.000 claims description 38
- 229910000398 iron phosphate Inorganic materials 0.000 claims description 33
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 32
- 230000007935 neutral effect Effects 0.000 claims description 26
- 238000001354 calcination Methods 0.000 claims description 25
- 238000010992 reflux Methods 0.000 claims description 22
- 239000003513 alkali Substances 0.000 claims description 21
- 238000001816 cooling Methods 0.000 claims description 19
- 238000010438 heat treatment Methods 0.000 claims description 19
- 238000007873 sieving Methods 0.000 claims description 19
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 18
- 238000004321 preservation Methods 0.000 claims description 18
- 238000000926 separation method Methods 0.000 claims description 18
- 239000002002 slurry Substances 0.000 claims description 18
- 238000007865 diluting Methods 0.000 claims description 16
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- 229910052593 corundum Inorganic materials 0.000 claims description 6
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 6
- 239000000377 silicon dioxide Substances 0.000 claims description 6
- 229910001385 heavy metal Inorganic materials 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 238000001556 precipitation Methods 0.000 claims description 5
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims description 4
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims description 4
- 235000011130 ammonium sulphate Nutrition 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 229910052681 coesite Inorganic materials 0.000 claims description 3
- 239000010431 corundum Substances 0.000 claims description 3
- 229910052906 cristobalite Inorganic materials 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 3
- 229910000358 iron sulfate Inorganic materials 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 238000002161 passivation Methods 0.000 claims description 3
- 239000002904 solvent Substances 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 229910052682 stishovite Inorganic materials 0.000 claims description 3
- 229910052905 tridymite Inorganic materials 0.000 claims description 3
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 3
- 239000004480 active ingredient Substances 0.000 claims description 2
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 2
- 238000010907 mechanical stirring Methods 0.000 claims description 2
- 238000002386 leaching Methods 0.000 abstract description 29
- 230000008569 process Effects 0.000 abstract description 24
- 230000008901 benefit Effects 0.000 abstract description 6
- 238000004064 recycling Methods 0.000 abstract description 6
- 239000011790 ferrous sulphate Substances 0.000 abstract description 5
- 235000003891 ferrous sulphate Nutrition 0.000 abstract description 5
- 229910000359 iron(II) sulfate Inorganic materials 0.000 abstract description 5
- 239000002994 raw material Substances 0.000 abstract description 5
- 235000021110 pickles Nutrition 0.000 abstract description 4
- 238000007796 conventional method Methods 0.000 abstract description 3
- 238000009776 industrial production Methods 0.000 abstract description 2
- 230000001376 precipitating effect Effects 0.000 abstract description 2
- 239000012670 alkaline solution Substances 0.000 abstract 1
- 238000007605 air drying Methods 0.000 description 15
- 238000002360 preparation method Methods 0.000 description 13
- 238000010521 absorption reaction Methods 0.000 description 10
- 239000002245 particle Substances 0.000 description 10
- 239000013078 crystal Substances 0.000 description 9
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 9
- 230000000694 effects Effects 0.000 description 7
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 6
- 230000005284 excitation Effects 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 230000001105 regulatory effect Effects 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 229960004887 ferric hydroxide Drugs 0.000 description 4
- 239000008394 flocculating agent Substances 0.000 description 4
- 239000011019 hematite Substances 0.000 description 4
- 229910052595 hematite Inorganic materials 0.000 description 4
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 4
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 230000009257 reactivity Effects 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- -1 for example Chemical compound 0.000 description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 239000002075 main ingredient Substances 0.000 description 3
- 238000004137 mechanical activation Methods 0.000 description 3
- 235000010755 mineral Nutrition 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- DJHGAFSJWGLOIV-UHFFFAOYSA-K Arsenate3- Chemical compound [O-][As]([O-])([O-])=O DJHGAFSJWGLOIV-UHFFFAOYSA-K 0.000 description 2
- 229910000616 Ferromanganese Inorganic materials 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- 150000004645 aluminates Chemical class 0.000 description 2
- 229940000489 arsenate Drugs 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000000084 colloidal system Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002329 infrared spectrum Methods 0.000 description 2
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- DPTATFGPDCLUTF-UHFFFAOYSA-N phosphanylidyneiron Chemical compound [Fe]#P DPTATFGPDCLUTF-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- 235000021317 phosphate Nutrition 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 description 2
- 229910021489 α-quartz Inorganic materials 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910002589 Fe-O-Fe Inorganic materials 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- SOXJQKKNADFEOW-UHFFFAOYSA-L S(=O)(=O)([O-])[O-].[Fe+2].[Li+] Chemical compound S(=O)(=O)([O-])[O-].[Fe+2].[Li+] SOXJQKKNADFEOW-UHFFFAOYSA-L 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000002894 chemical waste Substances 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 238000009854 hydrometallurgy Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- BMTOKWDUYJKSCN-UHFFFAOYSA-K iron(3+);phosphate;dihydrate Chemical compound O.O.[Fe+3].[O-]P([O-])([O-])=O BMTOKWDUYJKSCN-UHFFFAOYSA-K 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000007885 magnetic separation Methods 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000002064 nanoplatelet Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 229920002401 polyacrylamide Polymers 0.000 description 1
- BITYAPCSNKJESK-UHFFFAOYSA-N potassiosodium Chemical compound [Na].[K] BITYAPCSNKJESK-UHFFFAOYSA-N 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Landscapes
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention discloses a method for preparing battery grade ferric phosphate by using pyrite cinder. The method adopts alkaline solution to assist ball milling to excite and mechanically activate pyrite cinder, and the pyrite cinder is cured to promote the impurity to be converted into soluble component or passivated into component which is difficult to be dissolved in acid to be stripped with ferric oxide, and then the impurity is removed by water leaching; and then directly precipitating with sulfuric acid as an iron source, phosphoric acid as a phosphorus source and ammonia water as a neutralizer to prepare the battery grade ferric phosphate. The method realizes the efficient removal of harmful impurities in the process of preparing the battery-grade ferric phosphate by taking the pyrite cinder as the raw material, reduces the complex processes of removing the impurities by adjusting the pH value of the pickle liquor or reducing the pickle liquor into ferrous sulfate and the like in the conventional method, and realizes the efficient and high-value recycling utilization of the pyrite cinder. The method has the advantages of simple process, mild reaction conditions, simple operation and control and easy realization of large-scale industrial production.
Description
Technical Field
The invention relates to the field of high-value recycling of chemical solid dangerous wastes, in particular to a method for preparing battery-grade ferric phosphate by using pyrite cinder.
Background
Lithium iron phosphate is a second generation lithium ion battery anode material and occupies a significant position in the current new energy industry. With the rapid development of new energy industry in recent years, the demand of lithium iron phosphate in China is expected to increase to tens of millions of tons by 2030. In the face of such great demands, the search for iron sources with abundant sources and low price has important practical significance. In the current process for producing lithium iron phosphate, the solid phase method process using ferric phosphate as an iron-phosphorus source precursor has the largest proportion, and the physical and chemical properties such as the elemental composition, the particle morphology and the like of the ferric phosphate have great influence on the electrochemical performance of the finally prepared lithium iron phosphate. The chemical structure of the ferric phosphate has strong dependence on the preparation method, and the ferric phosphate compounds with different crystal structures, sizes and morphologies can be obtained by different preparation methods. According to the crystal structure, the method can be divided into isophosphoric ferromanganese ore type, amorphous type, orthogonal type, monoclinic type, alpha-quartz crystal system and the like; the electrochemical activity sequence is that the isophosphoric ferro-manganese ore type is more than amorphous and more than orthogonal and more than monoclinic and more than alpha-quartz crystal system, wherein, the ferric phosphate with amorphous structure is mainly prepared by adopting a coprecipitation method.
The pyrite cinder (PyC) is solid waste produced in the process of producing sulfuric acid by roasting pyrite, and the main phases are Fe 2O3、SiO2、Al2O3, gangue and the like, wherein the Fe content is up to 30% -50%. In addition, pyC contains a relatively large amount of Al, zn, cu, mn or other valuable metals. The annual production of PyC in China is 1100-1200 ten thousand tons, which occupies 30％(W.Li,S.Wang,Y.Han,Z.Tang,Y.Zhang.Recovery ofiron from pyrite cinder by suspension magnetization roasting-magnetic separation method:Process optimization and mechanism study.Sep.Purif.Technol.,2024,332:125652;T.Jiang,Y.Tu,Z.Su,M.Lu,S.Liu,J.Liu,F.Gu,Y.Zhang.Anovel value-added utilizationprocess forpyrite cinder:Selective recovery ofCu/Co and synthesis ofironphosphate.Hydrometallurgy,2020,193:105314). of national chemical waste residues, so that the PyC is a high-quality iron source with rich sources and high content, and can be completely used as an inexpensive iron source for preparing iron phosphate/lithium iron phosphate with huge demand. However, since PyC is produced by roasting pyrite at high temperature, fe 2O3 in the pyrite is mutually piled and agglomerated with impurity components, inert gangue, siO 2 and the like, so that the surface of Fe 2O3 is often coated with the inert components such as gangue, siO 2 and the like to reduce the reactivity of the Fe 2O3 and make the Fe 2O3 difficult to extract, And impurities such as Al, zn, mn, pb, cr, ca, mg and the like are easy to leach along with the Fe leaching, so that the content of the Fe-containing solution impurities obtained by leaching is high. The iron-containing solution obtained by the method is used as an iron source to prepare ferric phosphate, the impurity content is often seriously out of standard, and the preparation requirement of lithium iron phosphate is difficult to meet. Therefore, the key to preparing iron phosphate/lithium iron phosphate with PyC as the iron source is the control of impurities. The common impurity content control methods mainly comprise the following two methods: (1) Ferric iron in the PyC is converted into ferrous iron, and after impurity removal in the process, the ferrous iron is converted into ferric phosphate by using an oxidant such as H 2O2 and the like and phosphate, for example, ferric iron in the PyC is extracted by acid and then reduced and converted into ferrous sulfate with higher purity; Or dissolving silicon dioxide in PyC with alkali, then leaching with acid, reducing into ferrous solution with iron powder, and removing impurities with nonionic flocculant (CN 109368610A); or calcining and reducing PyC and a carbon source into ferrous iron in an inert atmosphere, leaching by dilute phosphoric acid, and purifying a leaching solution (CN 114684801A) by adjusting the pH value and adding a flocculating agent; (2) Firstly extracting iron in PyC, then converting into ferric hydroxide, and then reacting with phosphoric acid to convert into ferric phosphate, for example, firstly extracting the iron of the PyC with acid, then adding iron powder for reduction, adding alkali to adjust and control the pH value to remove impurities, adding an oxidant and adjusting and controlling the pH value to convert ferrous iron into ferric hydroxide (CN 114906830A); Or leaching PyC with strong acid, adjusting pH with urea or ammonia water to remove impurity elements in the reaction solution, and converting iron into ferric hydroxide colloid (CN 108706561A). Obviously, the first method converts ferric iron into ferrous iron, ferrous sulfate is prepared by crystallization or the aim of impurity removal is achieved by regulating and controlling the pH value of the solution and adding a flocculating agent, the impurity removal process is complicated, alkali and flocculating agent are needed to be consumed, and particularly H 2O2 with high risk and high price is needed to be added in the later stage, so that the process is complex, the cost is high, the risk of the preparation process is high, and the safety management requirement is high; In the second method, the pH value of the solution is regulated by adding alkali to remove impurities, so that alkali is consumed, the condition requirement is high when the pH value of the reaction solution is regulated, the pH value of the reaction solution is not easy to accurately control, insufficient impurity removal or iron loss in the reaction solution is easy to cause, and impurities are easily wrapped by the solution and converted into ferric hydroxide precipitate or colloid, so that the actual purification (impurity removal) effect is poor. Therefore, development of an efficient impurity removal method, simplification of the preparation process, and reduction of the preparation cost are needed.
Disclosure of Invention
In view of the above problems existing in the prior art that pyrite cinder (PyC) is used as an iron source to prepare ferric phosphate, the invention provides a method for preparing battery grade ferric phosphate by using pyrite cinder, which comprises the steps of alkali excitation, mechanical activation, curing, impurity removal, acid leaching, precipitation and the like, and is characterized in that: (1) The strong alkali solution is used as a solvent to excite and mechanically activate pyrite cinder by ball milling, and then the pyrite cinder is cured to promote the conversion of impurities into soluble components or passivation into components which are difficult to be acid-soluble so as to be stripped from ferric oxide, so that the removal rate of impurity components and the activity and leaching rate of the ferric oxide in the subsequent acid leaching process can be obviously improved; (2) The pyrite cinder after impurity removal is leached by sulfuric acid to obtain ferric sulfate, and the ferric sulfate is directly precipitated with phosphoric acid without impurity removal to be converted into battery grade ferric phosphate, so that the preparation process is simplified, the quality of products is improved, and the preparation cost is reduced.
The method for preparing battery grade ferric phosphate by using pyrite cinder provided by the invention comprises the following steps:
(1) Mixing the pyrite cinder subjected to grinding and sieving with an alkali solution according to the mass volume ratio of 1g to 1.0-1.2 mL, adding the mixture into a ball milling tank, and performing ball milling for 1-4 h;
(2) After ball material separation, the obtained slurry is put into a muffle furnace to be cured for 1 to 2 hours at the temperature of 100 to 120 ℃ in the air atmosphere, and then the temperature is raised to 150 to 300 ℃ to be cured for 2 to 4 hours; after natural cooling, adding distilled water according to 2-3 times of the mass of the cured material, fully stirring for 1.5-2 hours, filtering, and washing with distilled water to be neutral; drying the filter cake to constant weight to obtain impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding a sulfuric acid solution with the mass percentage concentration of 45-55% and the impurity-removed burned slag into a reactor according to the mass ratio of the sulfuric acid volume to the impurity-removed burned slag of 1.6-2.4 mL to 1g, carrying out reflux reaction for 4-5.5 h at the temperature of 110-125 ℃, adding distilled water again for continuous reaction for 0.5-1 h, filtering, collecting filtrate to obtain ferric sulfate solution, and collecting and utilizing filter residues, wherein the filter residues are used as building materials and the like;
(4) Diluting the ferric sulfate solution obtained in the step (3) into 0.1-0.3 mol/L ferric sulfate solution by using distilled water; then taking industrial phosphoric acid to dilute into a phosphoric acid solution with the concentration of 0.1-0.3 mol/L by distilled water according to the mol ratio of phosphorus to iron of 1-1.2:1; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5-1 h at 70-90 ℃, then adjusting the pH to 1.5-2.5 with alkali, continuing to perform heat preservation reaction for 1.5-2 h, filtering, washing a filter cake to be nearly neutral with distilled water, and collecting filtrate and washing water for centralized treatment;
(5) And (3) drying the filter cake obtained in the step (4) to obtain ferric phosphate dihydrate, grinding, placing in a muffle furnace, heating to 500-600 ℃ at 1-5 ℃/min, and calcining for 2-4 h to obtain the anhydrous ferric phosphate.
Further, in the step (1), the mass percentage of the active ingredients of the pyrite cinder is Fe2O357.19～78.64％,Al2O32.00～8.47％,SiO23.35～13.82％,CaO 1.00～10.25％,MgO 0.62～3.53％;, and the pyrite cinder is ground and sieved to be a 60-80-mesh sieve.
In the step (1), the alkali is sodium hydroxide or potassium hydroxide, and a solution with the mass percent concentration of 10-30% is prepared.
Further, in the step (1), grinding media are added into the ball mill according to the mass ratio of the ball materials of 8-12:1, wherein the grinding media are stainless steel balls, corundum balls or zirconia balls; the diameter of the big ball is 10mm, the diameter of the small ball is 2mm, and the mass ratio of the big ball to the small ball in the grinding medium is 1:5-8; ball milling is carried out at the rotating speed of 450-550 r/min.
Further, in the step (1), the drying is performed in a forced air drying oven, and the drying temperature is 80-100 ℃.
Further, in the step (2), the reflux reaction is performed under stirring conditions, and the stirring speed is 200-300 r/min.
Further, in the step (4), the mass percentage concentration of the industrial phosphoric acid is 85%; the alkali is ammonia water, and the mass percentage concentration is 15-20%.
Further, in the step (3) and the step (4), the reactor is provided with a mechanical stirring and reflux condensing device.
Further, in the step (5), the drying is performed in a forced air drying oven, the drying temperature is 110-130 ℃, and the drying time is 6-12 hours.
Further, the filtrate and the washing water collected in the step (2) are firstly regulated and controlled to pH value of 7.0-8.5 by sulfuric acid, al in the filtrate and washing water is converted into aluminum hydroxide to be separated and removed, and then a chelating flocculant is added to remove heavy metal ions in the filtrate and washing water; the filtrate and the washing water collected in the step (4) are firstly adjusted to pH value of 4.5-5.5 by ammonia water, and then are evaporated, concentrated, cooled and crystallized to recover the ammonium sulfate.
According to the measurement, the quality index of the anhydrous iron phosphate obtained by the invention can reach or be superior to the technical standard of iron phosphate for batteries (HG/T4701-2021).
Grinding and sieving PyC, mixing the PyC with a strong alkali solution, performing ball milling to excite and mechanically activate the PyC, and performing water leaching, filtering and washing to obtain impurity-removed pyrite cinder; and then, directly acid leaching with sulfuric acid to remove impurities from pyrite cinder to obtain purer ferric sulfate which is used as an iron source generated by ferric phosphate, then adding phosphoric acid which is used as a phosphorus source, and regulating and controlling the pH value of a reaction system by ammonia water to directly convert ferric iron into battery-grade ferric phosphate. The invention provides an effective method for efficiently removing harmful impurities in the process of preparing battery-grade ferric phosphate by taking pyrite cinder as a raw material, reduces complex processes of adjusting the pH value of the pickle liquor to remove the impurities or reducing the pickle liquor into ferrous sulfate and the like in the conventional method, realizes the efficient and high-value recycling utilization of the pyrite cinder, opens up a raw material path with rich and low sources for the mass production of ferric phosphate, and plays an important role in promoting the rapid development of new energy industries taking lithium iron sulfate as a material and improving economic benefits.
Compared with the prior art, the invention has the following beneficial effects:
(1) The strong alkali solution is used as a ball milling solvent, so that multiple functions of a wetting agent, a dispersing agent and an exciting agent can be achieved, excitation and activation effects of components in the PyC are improved, and impurities originally coated and mixed in the PyC particles are converted into soluble components by combining curing treatment, so that the impurities are further promoted to be converted into the soluble components or passivated into components which are difficult to be dissolved in acid and are stripped from ferric oxide, the reactivity of the ferric oxide is improved, the leaching difficulty of the iron is reduced, the extraction efficiency is improved, and the impurity content in an extracting solution is remarkably reduced. Compared with the conventional method, the method has the advantages that the process for converting the iron of the PyC into the high-purity ferrous sulfate is simpler, and the efficiency is higher; compared with the method of adjusting the pH value of the leaching liquid and assisting other heavy metal trapping agents and flocculating agents to remove impurities, the method has the advantages of simpler process, easier control and better impurity removal effect.
(2) The battery grade ferric phosphate is prepared by directly precipitating the ferric sulfate obtained by directly acid leaching and impurity removing pyrite cinder with sulfuric acid as an iron source, phosphoric acid as a phosphorus source and ammonia water as a neutralizer, and the battery grade ferric phosphate is not required to be subjected to complicated impurity removing process, and has the advantages of simple preparation process, easy operation control and low impurity content of products, and can reach or even be superior to the technical index of the battery grade ferric phosphate.
(3) The ferric sulfate obtained by direct acid leaching of sulfuric acid is used as an iron source to prepare ferric phosphate, and H 2O2 is not needed to be added, so that the preparation cost is reduced, the use of dangerous chemicals is avoided, the safety of the preparation process is improved, and the management cost is reduced.
(4) The preparation method has the advantages of simple preparation process, simple and convenient operation and mild reaction conditions; the three wastes are less, waste water generated in the impurity removal process and the process of preparing the ferric phosphate by a precipitation method is effectively treated, valuable components are fully recovered, and the process is environment-friendly; the required equipment is conventional equipment, and industrial production is easy to realize.
(5) The invention opens up a new method and a new way for preparing the iron phosphate/lithium iron phosphate with huge demand by taking the pyrite cinder as an iron source, realizes the high-value recycling utilization of the pyrite cinder, can also reduce the production cost of the iron phosphate/lithium iron phosphate, and has wide application prospect.
Drawings
FIG. 1 is a block diagram of a process for preparing battery grade iron phosphate from pyrite cinder in accordance with the present invention.
FIG. 2 is a scanning electron microscope image of the original pyrite cinder and the impurity-removed pyrite cinder in the present invention: and (a) - (b) correspond to scanning electron microscope pictures of different magnifications of the original pyrite cinder, and (c) - (d) correspond to scanning electron microscope pictures of different magnifications of the impurity-removed pyrite cinder.
FIG. 3 is an X-ray diffraction pattern and scanning electron microscope of the iron phosphate of the present invention: in fig. 3A, (a), (b), and (c) correspond to the X-ray diffraction patterns of the iron phosphate obtained in example 1, example 3, and example 5, respectively; in FIG. 3B, (a), (B) and (c) correspond to sample physical charts of the iron phosphate obtained in example 1, example 3 and example 5, respectively; FIG. 3C is a scanning electron microscope image of the iron phosphate obtained in example 5.
Fig. 4 is an infrared spectrum of iron phosphate in the present invention: (a), (b) and (c) correspond to the iron phosphates obtained in examples 1,3 and 5, respectively.
Detailed Description
The invention will be described in further detail with reference to the drawings and specific examples, but the scope of the invention claimed is not limited to the examples.
Examples 1 to 16 are examples of the removal of the pyrite cinder and the production of battery grade iron phosphate, example 17 is an example of the treatment of the impurity-removed filtrate and the washing water collected in the step (2) and the recycling of valuable components, and example 18 is an example of the treatment of the filtrate and the washing water produced in the step (4) for producing iron phosphate.
The process flow diagram of the invention is shown in figure 1, and the main components of the pyrite cinder used in the examples are shown in table 1.
TABLE 1 main ingredients of pyrite cinder
Example 1
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 31mL of NaOH solution with the mass percentage concentration of 10% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the mass ratio of 10:1, and ball milling is carried out for 2 hours at the rotating speed of 450 r/min;
(2) After ball separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 110 ℃ in air atmosphere, and then the temperature is raised to 300 ℃ to be cured for 2 hours; naturally cooling, adding distilled water according to 2 times of the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to be neutral; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 20.8231g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 48.5mL of sulfuric acid solution with the mass percent concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 4.5h at the stirring speed of 250r/min and the temperature of 110 ℃, adding 15mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 59mL of ferric sulfate solution with the concentration of 2.82 mol/L;
(4) 35.46mL of the ferric sulfate solution obtained in the step (3) is diluted to the concentration of 0.2mol/L by distilled water; 6.83mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 1h at 70 ℃, then adjusting the pH value to 1.5 by using 15% ammonia water in percentage by mass, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.4506g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 2 hours to obtain 14.9807g anhydrous ferric phosphate.
Table 2 shows the main element contents of the ICP-OE test of the iron sulfate solution obtained by leaching pyrite cinder which is not subjected to impurity removal by the method and is subjected to sulfuric acid leaching under the same process conditions, and Table 3 shows the component detection results of the iron phosphate prepared under the same conditions by adopting the two iron sulfate solutions as iron sources.
TABLE 2 main ingredients of pyrite cinder leaching solution
TABLE 3 main ingredients of iron phosphate prepared from different iron sources
Other element content
As can be seen from Table 2, the content of other elements except iron in the ferric sulfate solution obtained by directly leaching the pyrite cinder by removing impurities and then sulfuric acid by adopting the method is obviously lower than that of the ferric sulfate solution obtained by directly leaching the pyrite cinder without removing impurities by adopting sulfuric acid. The main reason is that through strong alkali excitation, ball milling mechanical activation and curing treatment, al, zn, si, pb, as and the like are promoted to be converted into soluble salts, such as aluminate, zincate, sodium (potassium) silicate, plumbate, arsenate and the like, which are easily dissolved into filtrate and washing water in the water leaching process; while other elements are prone to passivation during the treatment process, such as Zr, mo, mn, V, sb, sn, etc., and are difficult to leach out and remain in the residue during the subsequent acid leaching. After the treatment, not only the activity of the ferric oxide in the cinder is increased, but also the ferric oxide originally wrapped by gangue and silicon dioxide is stripped out, so that the activity, leaching rate and leaching speed are increased.
As can be seen from Table 3, the technical indexes of the anhydrous ferric phosphate prepared by taking the ferric sulfate solution obtained by acid leaching of the impurity-removed cinder as an iron source are all up to or superior to those of the anhydrous ferric phosphate for batteries (HG/T4701-2021), while the anhydrous ferric phosphate prepared by taking the ferric sulfate solution obtained by direct acid leaching of the pyrite cinder without impurity removal as an iron source only has partial indexes, such as iron-phosphorus ratio, na, K, mn, ti, magnetic substances, tap density, granularity, specific surface area and the like, which reach technical standards, and the technical indexes such as phosphorus content, calcium content, magnesium content, copper content, zinc content, manganese content, aluminum content, moisture content and the like, which all do not reach the technical requirements of HG/T4701-2021. In addition, the content of other impurity elements in the iron phosphate prepared from the iron phosphate obtained by impurity removal is also obviously lower than that of the iron phosphate obtained without impurity removal. Therefore, the iron phosphate for the battery prepared by taking pyrite cinder as an iron source is required to be subjected to impurity removal by adopting an effective method.
Fig. 2 is an SEM image of raw pyrite cinder and the decontaminated pyrite cinder. As can be seen from fig. 2 (a) - (b), the raw sample without any treatment consisted of blocks or plate-like particles of the next-order composition varying from several hundred nanometers to several micrometers, which were tightly connected to each other and had a smooth and even surface. The block or flake particles are mainly various minerals such as hematite (ferric oxide), gangue, gypsum, etc., which are closely stacked and agglomerated with each other into irregular shapes of 10 μm or more. The reason for forming the structure is probably that after the pyrite is subjected to a high-temperature roasting process, a large amount of sulfur-containing gas is generated to escape along with the conversion of FeS 2, the mineral structure is obviously changed, and the generated Fe 2O3 is fused and wrapped with inert components such as residual gangue, silicon dioxide and the like, so that the reactivity of the Fe 2O3 is low and the Fe 2O3 is difficult to extract. Fig. 2 (c) - (d) are SEM images of the impurity-removed samples, and it can be seen that after ball milling, alkali excitation and curing, part of the particles, such as Al, zn, as, si, are converted into soluble salts, and the structure of the particles piled up by various minerals and impurities is destroyed, so that the originally agglomerated sintered slag particles are effectively separated and dispersed, thereby exposing the hematite coated by the impurity stack, such as SiO 2 and gangue, and increasing the specific surface area of the sintered slag particles, and providing more reaction sites for subsequent leaching reactions. Fig. 2 (d) is a further enlarged image of the impurity-removed cinder, and it can be seen that compared with the original sample, the surface of the impurity-removed cinder appears to be coarser and more discontinuous, which is attributable to that NaOH reacts with impurities such As SiO 2, al, as, zn and the like on the surface of cinder particles in the curing reaction process after being uniformly mixed with the cinder, so As to generate soluble silicate, aluminate, arsenate, zincate and the like, and etch the surface of the cinder particles, thereby further exposing the hematite (iron oxide) wrapped therein, and effectively promoting the peeling of the hematite and the inert components and increasing the reactivity thereof.
Example 2
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 3 hours at the rotating speed of 500 r/min;
(2) After ball separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 110 ℃ in air atmosphere, and then the temperature is raised to 250 ℃ to be cured for 3 hours; naturally cooling, adding distilled water according to 2.5 times of the mass of the cured material, fully stirring for 1.5h, filtering, and washing with distilled water to neutrality; drying the filter cake in a forced air drying oven at 80 ℃ to constant weight to obtain 21.5309g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 42mL of sulfuric acid solution with the mass percentage concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5h at the stirring speed of 250r/min and the temperature of 120 ℃, adding 20mL of distilled water, continuing to react for 0.5h, filtering, and collecting filtrate to obtain 55mL of ferric sulfate solution with the concentration of 2.80 mol/L;
(4) 35.70mL of the ferric sulfate solution obtained in the step (3) is diluted to the concentration of 0.2mol/L by distilled water; 6.83mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 1h at 80 ℃, then adjusting the pH value to 2.0 by using 15% ammonia water in percentage by mass, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 7 hours at 120 ℃ to obtain 18.3905g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 3 ℃/min, and calcining for 4 hours to obtain 14.6514g anhydrous ferric phosphate.
Example 3
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 28mL of NaOH solution with the mass percentage concentration of 30% are added into a ball milling tank, 211.72g of zirconia balls (35 g of big balls and 176.72g of small balls) are added according to the ball material mass ratio of 8:1, and ball milling is carried out for 4 hours at the rotating speed of 550 r/min;
(2) After ball separation, the obtained slurry is put into a muffle furnace to be cured for 1h at 120 ℃ in air atmosphere, and then the temperature is raised to 300 ℃ to be cured for 4h; naturally cooling, adding distilled water 3 times the mass of the cured material, fully stirring for 1.5h, filtering, and washing with distilled water to neutrality; drying the filter cake in a blast drying oven at 100 ℃ to constant weight to obtain 21.0346g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 42.1mL of sulfuric acid solution with the mass percent concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5h at the stirring speed of 250r/min and the temperature of 125 ℃, adding 20mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 55mL of ferric sulfate solution with the concentration of 2.79 mol/L;
(4) Taking 35.84mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 6.83mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 1h at 70 ℃, then adjusting the pH to 2.5 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 1.5h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 10 hours at 120 ℃ to obtain 18.4208g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 1 ℃/min, and calcining for 2 hours to obtain 14.7211g anhydrous ferric phosphate.
Example 4
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 27mL of KOH solution with the mass percentage concentration of 40% are added into a ball milling tank, 317.58g of stainless steel balls (45 g of big ball and 272.58g of small ball) are added according to the mass ratio of 12:1, and ball milling is carried out for 4 hours at the rotating speed of 500 r/min;
(2) After ball material separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 100 ℃ in air atmosphere, and then the temperature is raised to 150 ℃ to be cured for 4 hours; naturally cooling, adding distilled water according to 2 times of the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to be neutral; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 21.4864g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 35mL of sulfuric acid solution with the mass percentage concentration of 55% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 4.5h at the stirring speed of 300r/min and the temperature of 125 ℃, adding 25mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 51mL of ferric sulfate solution with the concentration of 2.75 mol/L;
(4) Taking 36.36mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution with distilled water until the concentration is 0.2mol/; 7.51mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 1h at 80 ℃, then adjusting the pH to 2.5 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 1.5h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 12 hours at 120 ℃ to obtain 18.3505g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 600 ℃ at 5 ℃/min, and calcining for 3.5 hours to obtain 14.6203g anhydrous ferric phosphate.
Example 5
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of corundum balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 1h at the rotating speed of 500 r/min;
(2) After ball separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 110 ℃ in air atmosphere, and then the temperature is raised to 250 ℃ to be cured for 3 hours; naturally cooling, adding distilled water 3 times the mass of the cured material, fully stirring for 1.5h, filtering, and washing with distilled water to neutrality; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 21.6704g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 35mL of sulfuric acid solution with the mass percentage concentration of 45% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5h at the stirring speed of 250r/min and the temperature of 120 ℃, adding 25mL of distilled water, continuing to react for 0.5h, filtering, and collecting filtrate to obtain 50mL of ferric sulfate solution with the concentration of 2.75 mol/L;
(4) Taking 36.36mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 8.19mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2.5 by using 15% ammonia water in percentage by mass, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 7 hours at 120 ℃ to obtain 18.5601g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at a speed of 4 ℃/min, and calcining for 4 hours to obtain 15.0207g anhydrous ferric phosphate.
Example 6
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 3 hours at the rotating speed of 500 r/min;
(2) After ball material separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 100 ℃ in air atmosphere, and then the temperature is raised to 300 ℃ to be cured for 3 hours; naturally cooling, adding distilled water 3 times the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to neutrality; drying the filter cake in a blast drying oven at 100 ℃ to constant weight to obtain 21.2995g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 35mL of sulfuric acid solution with the mass percentage concentration of 52.5% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5h at the stirring speed of 250r/min and the temperature of 110 ℃, adding 25mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 52mL of ferric sulfate solution with the concentration of 2.74 mol/L;
(4) Taking 36.50mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 7.51mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2 by using 15% ammonia water in percentage by mass, continuing to perform heat preservation reaction for 1.5h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 10 hours at 120 ℃ to obtain 18.5811g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 3 hours to obtain 15.0604g anhydrous ferric phosphate.
Example 7
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of KOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 4 hours at the rotating speed of 500 r/min;
(2) After the ball materials are separated, the obtained slurry is put into a muffle furnace to be cured for 1.5 hours at 120 ℃ in air atmosphere, and then the temperature is raised to 300 ℃ to be cured for 3 hours; naturally cooling, adding distilled water 3 times the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to neutrality; drying the filter cake in a blast drying oven at 100 ℃ to constant weight to obtain 21.4532g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 35mL of sulfuric acid solution with the mass percentage concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5h at the stirring speed of 250r/min and the temperature of 120 ℃, adding 25mL of distilled water, continuing to react for 0.5h, filtering, and collecting filtrate to obtain 51mL of ferric sulfate solution with the concentration of 2.75 mol/L;
(4) Taking 36.40mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 7.51mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 1.5h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 10 hours at 120 ℃ to obtain 18.5506g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 600 ℃ at 5 ℃/min, and calcining for 2 hours to obtain 15.0121g anhydrous ferric phosphate.
Example 8
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 4 hours at the rotating speed of 500 r/min;
(2) After ball separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 110 ℃ in air atmosphere, and then the temperature is raised to 300 ℃ to be cured for 2 hours; naturally cooling, adding distilled water 3 times the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to neutrality; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 20.9005g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 35mL of sulfuric acid solution with the mass percentage concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5h at the stirring speed of 250r/min and the temperature of 125 ℃, adding 25mL of distilled water, continuing to react for 0.5h, filtering, and collecting filtrate to obtain 54mL of ferric sulfate solution with the concentration of 2.71 mol/L;
(4) Taking 36.90mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 7.51mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 1.5h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.4504g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 4 hours to obtain 14.8014g anhydrous ferric phosphate.
Example 9
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 3 hours at the rotating speed of 500 r/min;
(2) After ball material separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 100 ℃ in air atmosphere, and then the temperature is raised to 200 ℃ to be cured for 4 hours; naturally cooling, adding distilled water according to 2 times of the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to be neutral; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 21.4555g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 35mL of sulfuric acid solution with the mass percentage concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5.5h at the stirring speed of 250r/min and the temperature of 120 ℃, adding 20mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 50mL of ferric sulfate solution with the concentration of 2.85 mol/L;
(4) Taking 35.00mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution with distilled water until the concentration is 0.2mol/L; 8.17mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2.5 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.4303g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 2 hours to obtain 15.1021g anhydrous ferric phosphate.
Example 10
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 4 hours at the rotating speed of 500 r/min;
(2) After ball separation, the obtained slurry is put into a muffle furnace to be cured for 1h at 120 ℃ in air atmosphere, and then the temperature is raised to 250 ℃ to be cured for 3h; naturally cooling, adding distilled water according to 2 times of the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to be neutral; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 21.6957g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 35mL of sulfuric acid solution with the mass percentage concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5.5h at the stirring speed of 250r/min and the temperature of 115 ℃, adding 20mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 52mL of ferric sulfate solution with the concentration of 2.82 mol/L;
(4) Taking 35.50mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 8.20mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2.5 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.4808g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 4 hours to obtain 14.9005g anhydrous ferric phosphate.
Example 11
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of KOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 3 hours at the rotating speed of 500 r/min;
(2) After ball material separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 100 ℃ in air atmosphere, and then the temperature is raised to 300 ℃ to be cured for 2 hours; naturally cooling, adding distilled water according to 2 times of the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to be neutral; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 22.1204g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 35mL of sulfuric acid solution with the mass percentage concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5.5h at the stirring speed of 250r/min and the temperature of 120 ℃, adding 25mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 55mL of ferric sulfate solution with the concentration of 2.72 mol/L;
(4) Taking 36.70mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 8.18mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 1.5 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.3501g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 4 hours to obtain 14.7103g anhydrous ferric phosphate.
Example 12
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 3 hours at the rotating speed of 500 r/min;
(2) After ball separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 110 ℃ in air atmosphere, and then the temperature is raised to 150 ℃ to be cured for 4 hours; naturally cooling, adding distilled water according to 2 times of the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to be neutral; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 21.8509g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 35mL of sulfuric acid solution with the mass percentage concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5.5h at the stirring speed of 250r/min and the temperature of 115 ℃, adding 25mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 53mL of ferric sulfate solution with the concentration of 2.74 mol/L;
(4) Taking 36.50mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 8.19mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2.5 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.6107g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 4 hours to obtain 15.0501g anhydrous ferric phosphate.
Example 13
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 3 hours at the rotating speed of 500 r/min;
(2) After ball separation, the obtained slurry is put into a muffle furnace to be cured for 1h at 110 ℃ in air atmosphere, and then the temperature is raised to 200 ℃ to be cured for 1h; naturally cooling, adding distilled water 3 times the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to neutrality; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 21.1463g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 42.3mL of sulfuric acid solution with the mass percent concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5.5h at the stirring speed of 250r/min and the temperature of 125 ℃, adding 20mL of distilled water for continuous reaction for 0.5h, then filtering, and collecting filtrate to obtain 58mL of ferric sulfate solution with the concentration of 2.69 mol/L;
(4) Taking 37.20mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 7.51mL of industrial phosphoric acid is diluted into 0.2mol/L phosphoric acid solution by distilled water; adding diluted ferric sulfate solution and phosphoric acid into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.4504g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 2 hours to obtain 14.9101g anhydrous ferric phosphate.
Example 14
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 3 hours at the rotating speed of 500 r/min;
(2) After ball material separation, the obtained slurry is put into a muffle furnace to be cured for 1h at 110 ℃ in air atmosphere, and then is heated to 200 ℃ to be cured for 2h; naturally cooling, adding distilled water 3 times the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to neutrality; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 21.5567g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 42.3mL of sulfuric acid solution with the mass percent concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5.5h at the stirring speed of 250r/min and the temperature of 120 ℃, adding 20mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 57mL of ferric sulfate solution with the concentration of 2.71 mol/L;
(4) Taking 37.00mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution with distilled water until the concentration is 0.2mol/; 7.53mL of industrial phosphoric acid is diluted with distilled water to obtain a phosphoric acid solution with the concentration of 0.2 mol/L; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.3811g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 4 hours to obtain 14.7303g anhydrous ferric phosphate.
Example 15
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of KOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added according to the ball material mass ratio of 10:1, and ball milling is carried out for 4 hours at the rotating speed of 500 r/min;
(2) After ball material separation, the obtained slurry is put into a muffle furnace to be cured for 1h at 110 ℃ in air atmosphere, and then the temperature is raised to 200 ℃ to be cured for 3h; naturally cooling, adding distilled water 3 times the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to neutrality; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 22.2133g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 42.3mL of sulfuric acid solution with the mass percent concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5.5h at the stirring speed of 250r/min and the temperature of 125 ℃, adding 20mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 54mL of ferric sulfate solution with the concentration of 2.80 mol/L;
(4) Taking 35.70mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution to the concentration of 0.2mol/L by using distilled water; 7.51mL of industrial phosphoric acid is diluted with distilled water to obtain a phosphoric acid solution with the concentration of 0.2mol/L; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5h at 90 ℃, then adjusting the pH to 2by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.4205g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 4 hours to obtain 14.7413g anhydrous ferric phosphate.
Example 16
(1) 26.465G of pyrite cinder subjected to grinding and sieving and 29mL of NaOH solution with the mass percentage concentration of 20% are added into a ball milling tank, 264.65g of zirconia balls (40 g of big balls and 224.65g of small balls) are added into a grinding medium according to the ball material mass ratio of 10:1, and ball milling is carried out for 3 hours at the rotating speed of 500 r/min;
(2) After ball material separation, the obtained slurry is put into a muffle furnace to be cured for 2 hours at 110 ℃ in air atmosphere, and then the temperature is raised to 200 ℃ to be cured for 4 hours; naturally cooling, adding distilled water 3 times the mass of the cured material, fully stirring for 2 hours, filtering, and washing with distilled water to neutrality; drying the filter cake in a forced air drying oven at 90 ℃ to constant weight to obtain 21.1059g of impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding 42.3mL of sulfuric acid solution with the mass percent concentration of 50% and the impurity-removed burned slag into a reactor, carrying out reflux reaction for 5.5h at the stirring speed of 250r/min and the temperature of 120 ℃, adding 20mL of distilled water for continuous reaction for 0.5h, filtering, and collecting filtrate to obtain 56mL of ferric sulfate solution with the concentration of 2.74 mol/L;
(4) Taking 36.50mL of the ferric sulfate solution obtained in the step (3), and diluting the ferric sulfate solution with distilled water until the concentration is 0.2mol/; 7.51mL of industrial phosphoric acid is diluted with distilled water to obtain a phosphoric acid solution with the concentration of 0.2mol/L; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 1h at 90 ℃, then adjusting the pH to 2 by using ammonia water with the mass percent concentration of 20%, continuing to perform heat preservation reaction for 2h, filtering, washing a filter cake to be nearly neutral by using distilled water, and collecting filtrate and washing water for centralized treatment;
(5) Placing the filter cake obtained in the step (4) in a blast drying oven to be dried for 6 hours at 120 ℃ to obtain 18.3604g of ferric phosphate dihydrate; grinding, placing in a muffle furnace, heating to 550 ℃ at 5 ℃/min, and calcining for 4 hours to obtain 14.6510g anhydrous ferric phosphate.
Example 17
Respectively taking 500mL of filtrate and washing water collected in the step (2) in each embodiment, adding 6mol/L sulfuric acid to adjust the pH value of the solution to 7.0-8.5, and filtering, separating and recovering precipitates such as Al (OH) 3; adding a heavy metal chelating flocculant with the mass percentage concentration of 5% into the filtrate until precipitation is not increased, removing various metal ions, particularly heavy metal ions, then adding a proper amount of cationic polyacrylamide to promote further increase of flocculation, generating brown-black precipitation, filtering and separating, collecting filter residues, drying, and concentrating as smelting raw materials to recover various metals through smelting.
Example 18
Respectively taking 500mL of filtrate and washing water collected in the step (4) in each embodiment, adding 15% -20% ammonia water to adjust the pH value to 4.5-5.5, evaporating and concentrating until a film is easily generated at the interface between the solution and air, stopping heating, cooling and crystallizing, filtering, and drying a filter cake (crystal) in a vacuum drying oven at 60 ℃ to constant weight to obtain an ammonium sulfate byproduct; the filtrate is combined with the filtrate and washing water collected in the next round for recycling the ammonium sulfate.
FIG. 3A is an X-ray diffraction pattern of the iron phosphate obtained in example 1 (a), example 3 (b) and example 5 (c). As can be seen from fig. 3A (a), the uncalcined iron phosphate has no distinct characteristic diffraction peak, indicating that the uncalcined iron phosphate of example 1 (i.e., iron phosphate dihydrate) is of amorphous structure. In example 3, the iron phosphate product was calcined at high temperature for 2 hours, and the peak shape was changed, and diffraction peaks were formed at the (100) and (102) planes (FIG. 3A (b)). Fig. 3A (c) is a test result of the iron phosphate of example 5 after calcination for 4 hours, and the diffraction peak thereof at 25.8 ° is enhanced, indicating a further improvement in the crystallinity of the iron phosphate. This result is consistent with FePO 4 standard card (JCPDS No. 50-1635). Fig. 3B shows sample physical graphs of example 1 (a) (not calcined), example 3 (B) and example 5 (c), with the color of the iron phosphate product gradually changing from yellow to pale white as the calcination time was prolonged. FIG. 3C is an SEM image of the iron phosphate prepared in example 5, and the calcined iron phosphate has a nano-platelet structure of 82-361 nm.
FIG. 4 is the Fourier infrared spectra (FT-IR) of the samples of example 1 (a), example 3 (b) and example 5 (c). As can be seen from FIG. 4, absorption peaks are present at wavenumbers 3420, 1620, 1030, 636, 593cm -1; Wherein, example 1 (a) has strong absorption peaks at 3420cm -1 and 1620cm -1, which are respectively the stretching vibration (V OH) and bending vibration (delta OH) peaks of crystal water or free water carried by the uncalcined ferric phosphate; Whereas the intensities of the absorption peaks at 3420cm -1 and 1620cm -1 were significantly reduced with the increase in calcination time for examples 3 (b) and 5 (c), indicating a further decrease in the crystal water and free water content carried in the sample with the increase in calcination time. The absorption peaks at 1030cm -1 and 636cm -1 can be attributed to the stretching and bending vibration peaks, respectively, of the P-O bonds in the phosphate. The absorption peak shape of the uncalcined iron phosphate sample at 1030cm -1 is not apparent from the intensity of the absorption peak; after calcining for 2 hours, the peak shape of the absorption peak is changed, but the peak intensity is not changed greatly; however, as the calcination time was prolonged to 4 hours, the absorption peak shape was significantly changed and the strength was greatly increased. The main reason is probably that the ferric phosphate dihydrate gradually removes the crystal water at 550 ℃ to be changed into anhydrous FePO 4, and the crystal form structure is changed, which is consistent with the X-ray diffraction result. In addition, the weak absorption peaks at 593cm -1 of example 1 (a), example 3 (b) and example 5 (c) are deformation vibration peaks of the Fe-O-Fe group in the iron phosphate, and the peak shape thereof also appears with an increase in the degree of dehydration. The spectrogram of fig. 4 shows that the prepared ferric phosphate has clear absorption peak and no impurity peak, and shows that the method for preparing the battery grade ferric phosphate by directly utilizing ferric sulfate obtained by sulfuric acid leaching as an iron source after the alkaline excitation, mechanical activation, curing and impurity removal is feasible by taking pyrite cinder as a raw material.
The foregoing is merely a preferred embodiment of the invention, and various modifications and changes may be made thereto by those skilled in the art in light of the above teachings, for example, combinations of ratios and process conditions may be made within the scope of the invention as defined by the appended claims, and similar such changes and modifications are intended to fall within the spirit of the invention.
Claims (10)
1. A method for preparing battery grade ferric phosphate by using pyrite cinder is characterized in that a strong alkali solution is used as a solvent, the pyrite cinder is excited and mechanically activated by ball milling, and then the pyrite cinder is cured to promote the conversion of impurities into soluble components or passivation into components which are difficult to be dissolved in acid so as to be stripped from ferric oxide; the pyrite cinder after impurity removal is leached by sulfuric acid to obtain ferric sulfate, and the ferric sulfate is directly converted into battery grade ferric phosphate by precipitation with phosphoric acid without impurity removal.
2. The method for preparing battery grade iron phosphate by using pyrite cinder according to claim 1, comprising the steps of:
(1) Mixing the pyrite cinder subjected to grinding and sieving with an alkali solution according to the mass volume ratio of 1g to 1.0-1.2 mL, adding the mixture into a ball milling tank, and performing ball milling for 1-4 h;
(2) After ball material separation, the obtained slurry is put into a muffle furnace to be cured for 1 to 2 hours at the temperature of 100 to 120 ℃ in the air atmosphere, and then the temperature is raised to 150 to 300 ℃ to be cured for 2 to 4 hours; after natural cooling, adding distilled water according to 2-3 times of the mass of the cured material, fully stirring for 1.5-2 hours, filtering, and washing with distilled water to be neutral; drying the filter cake to constant weight to obtain impurity-removed burned slag, and collecting filtrate and washing water for centralized treatment;
(3) Adding a sulfuric acid solution with the mass percentage concentration of 45-55% and the impurity-removed burned slag into a reactor according to the mass ratio of the sulfuric acid volume to the impurity-removed burned slag of 1.6-2.4 mL to 1g, carrying out reflux reaction for 4-5.5 h at the temperature of 110-125 ℃, adding distilled water again for continuous reaction for 0.5-1 h, filtering, collecting filtrate to obtain an iron sulfate solution, and collecting and utilizing filter residues;
(4) Diluting the ferric sulfate solution obtained in the step (3) into 0.1-0.3 mol/L ferric sulfate solution by using distilled water; then taking industrial phosphoric acid to dilute into a phosphoric acid solution with the concentration of 0.1-0.3 mol/L by distilled water according to the mol ratio of phosphorus to iron of 1-1.2:1; adding diluted ferric sulfate solution and phosphoric acid solution into a reactor at the same speed, reacting for 0.5-1 h at 70-90 ℃, then adjusting the pH to 1.5-2.5 with alkali, continuing to perform heat preservation reaction for 1.5-2 h, filtering, washing a filter cake to be nearly neutral with distilled water, and collecting filtrate and washing water for centralized treatment;
(5) And (3) drying the filter cake obtained in the step (4) to obtain ferric phosphate dihydrate, grinding, placing in a muffle furnace, heating to 500-600 ℃ at 1-5 ℃/min, and calcining for 2-4 h to obtain the anhydrous ferric phosphate.
3. The method for preparing battery grade ferric phosphate by using pyrite cinder according to claim 2, wherein in the step (1), the mass percentage of the active ingredients of the pyrite cinder is Fe2O3 57.19～78.64％,Al2O3 2.00～8.47％,SiO23.35～13.82％,CaO 1.00～10.25％,MgO 0.62～3.53％;, and the pyrite cinder is ground and sieved to a 60-80 mesh sieve.
4. The method for preparing battery grade ferric phosphate by using pyrite cinder according to claim 2, wherein in the step (1), the alkali is sodium hydroxide or potassium hydroxide, and a solution with the mass percent concentration of 10-30% is prepared.
5. The method for preparing battery grade ferric phosphate by using pyrite cinder according to claim 2, wherein in the step (1), grinding medium is added into the mixture according to the ball mass ratio of 8-12:1, and the grinding medium is stainless steel balls, corundum balls or zirconia balls; the diameter of the big ball is 10mm, the diameter of the small ball is 2mm, and the mass ratio of the big ball to the small ball in the grinding medium is 1:5-8; ball milling is carried out at the rotating speed of 450-550 r/min.
6. The method for preparing battery grade iron phosphate from pyrite cinder according to claim 2, wherein in the step (2), the reflux reaction is performed under stirring condition, and the stirring speed is 200-300 r/min.
7. The method for preparing battery grade ferric phosphate by using pyrite cinder according to claim 2, wherein in the step (4), the mass percentage concentration of the industrial phosphoric acid is 85%; the alkali is ammonia water, and the mass percentage concentration of the alkali is 15-20%.
8. The method for preparing battery grade ferric phosphate by using pyrite cinder according to claim 2, wherein in the step (3) and the step (4), the reactor is provided with a mechanical stirring and reflux condensing device.
9. The method for preparing battery grade ferric phosphate by using pyrite cinder according to claim 2, wherein the drying of the step (2) and the step (5) are carried out in a blast drying box, the drying temperature of the filter cake of the step (2) is 80-100 ℃, the drying temperature of the filter cake of the step (5) is 110-130 ℃ and the drying time is 6-12 h.
10. The method for preparing battery grade ferric phosphate by using pyrite cinder according to claim 2, wherein the filtrate and the washing water collected in the step (2) are firstly adjusted and controlled to pH value of 7.0-8.5 by sulfuric acid, al is converted into aluminum hydroxide for separation and removal, and then a chelating flocculant is added to remove heavy metal ions; the filtrate and the washing water collected in the step (4) are firstly adjusted to pH value of 4.5-5.5 by ammonia water, and then are evaporated, concentrated, cooled and crystallized to recover the ammonium sulfate.
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