CN115432683B - Method for preparing high-compaction battery-level ferric phosphate under low-temperature condition - Google Patents
Method for preparing high-compaction battery-level ferric phosphate under low-temperature condition Download PDFInfo
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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 62
- 238000000034 method Methods 0.000 title claims abstract description 43
- 239000005955 Ferric phosphate Substances 0.000 title claims abstract description 40
- 229940032958 ferric phosphate Drugs 0.000 title claims abstract description 40
- 229910000399 iron(III) phosphate Inorganic materials 0.000 title claims abstract description 40
- 238000005056 compaction Methods 0.000 title claims abstract description 24
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 184
- 239000002253 acid Substances 0.000 claims abstract description 97
- 238000006243 chemical reaction Methods 0.000 claims abstract description 77
- 229910052742 iron Inorganic materials 0.000 claims abstract description 72
- 238000004062 sedimentation Methods 0.000 claims abstract description 66
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims abstract description 57
- 239000008139 complexing agent Substances 0.000 claims abstract description 57
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 54
- 239000006228 supernatant Substances 0.000 claims abstract description 53
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 52
- 230000003647 oxidation Effects 0.000 claims abstract description 52
- 238000002360 preparation method Methods 0.000 claims abstract description 45
- 238000007599 discharging Methods 0.000 claims abstract description 30
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 29
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 29
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 26
- 238000005406 washing Methods 0.000 claims abstract description 13
- 238000001035 drying Methods 0.000 claims abstract description 11
- 238000001914 filtration Methods 0.000 claims abstract description 10
- 238000001354 calcination Methods 0.000 claims abstract description 9
- 238000003860 storage Methods 0.000 claims description 53
- 239000000463 material Substances 0.000 claims description 42
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 26
- 239000012530 fluid Substances 0.000 claims description 23
- 229910000398 iron phosphate Inorganic materials 0.000 claims description 21
- 239000013049 sediment Substances 0.000 claims description 18
- 238000012546 transfer Methods 0.000 claims description 14
- 230000001502 supplementing effect Effects 0.000 claims description 11
- 238000004064 recycling Methods 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- -1 amine trimethylene phosphate Chemical class 0.000 claims description 7
- 239000003054 catalyst Substances 0.000 claims description 4
- VWCFCFOIUSKKSC-UHFFFAOYSA-N ethane-1,2-diamine;2-hydroxy-1,3,2$l^{5}-dioxaphosphepane 2-oxide Chemical compound NCCN.OP1(=O)OCCCCO1 VWCFCFOIUSKKSC-UHFFFAOYSA-N 0.000 claims description 4
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 claims description 2
- 150000001412 amines Chemical class 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 claims description 2
- IEDVJHCEMCRBQM-UHFFFAOYSA-N trimethoprim Chemical compound COC1=C(OC)C(OC)=CC(CC=2C(=NC(N)=NC=2)N)=C1 IEDVJHCEMCRBQM-UHFFFAOYSA-N 0.000 claims 1
- 229960001082 trimethoprim Drugs 0.000 claims 1
- 238000006073 displacement reaction Methods 0.000 abstract description 6
- 150000003839 salts Chemical class 0.000 abstract description 3
- 238000007664 blowing Methods 0.000 abstract 1
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 14
- 239000000243 solution Substances 0.000 description 9
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 7
- 239000012535 impurity Substances 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- DPTATFGPDCLUTF-UHFFFAOYSA-N phosphanylidyneiron Chemical compound [Fe]#P DPTATFGPDCLUTF-UHFFFAOYSA-N 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 230000000536 complexating effect Effects 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- 239000011574 phosphorus Substances 0.000 description 4
- 239000001488 sodium phosphate Substances 0.000 description 4
- 229910000162 sodium phosphate Inorganic materials 0.000 description 4
- 235000011008 sodium phosphates Nutrition 0.000 description 4
- 125000000383 tetramethylene group Chemical group [H]C([H])([*:1])C([H])([H])C([H])([H])C([H])([H])[*:2] 0.000 description 4
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 4
- 229910019142 PO4 Inorganic materials 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000002202 Polyethylene glycol Substances 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 description 2
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 description 2
- 229910000388 diammonium phosphate Inorganic materials 0.000 description 2
- 235000019838 diammonium phosphate Nutrition 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 239000012065 filter cake Substances 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 2
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000006012 monoammonium phosphate Substances 0.000 description 2
- 235000019837 monoammonium phosphate Nutrition 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 235000011007 phosphoric acid Nutrition 0.000 description 2
- 229920001223 polyethylene glycol Polymers 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- XFNJVJPLKCPIBV-UHFFFAOYSA-N trimethylenediamine Chemical compound NCCCN XFNJVJPLKCPIBV-UHFFFAOYSA-N 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- MQNVHUZWFZKETG-UHFFFAOYSA-N P1(OCCCCCO1)=O.NCCNCCN Chemical compound P1(OCCCCCO1)=O.NCCNCCN MQNVHUZWFZKETG-UHFFFAOYSA-N 0.000 description 1
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- SNCZNSNPXMPCGN-UHFFFAOYSA-N butanediamide Chemical compound NC(=O)CCC(N)=O SNCZNSNPXMPCGN-UHFFFAOYSA-N 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000012527 feed solution Substances 0.000 description 1
- 229910001448 ferrous ion Inorganic materials 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- WRIRWRKPLXCTFD-UHFFFAOYSA-N malonamide Chemical compound NC(=O)CC(N)=O WRIRWRKPLXCTFD-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910000403 monosodium phosphate Inorganic materials 0.000 description 1
- 235000019799 monosodium phosphate Nutrition 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- RGSFGYAAUTVSQA-UHFFFAOYSA-N pentamethylene Natural products C1CCCC1 RGSFGYAAUTVSQA-UHFFFAOYSA-N 0.000 description 1
- 125000004817 pentamethylene group Chemical group [H]C([H])([*:2])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[*:1] 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- AOHJOMMDDJHIJH-UHFFFAOYSA-N propylenediamine Chemical compound CC(N)CN AOHJOMMDDJHIJH-UHFFFAOYSA-N 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 description 1
- YPPQYORGOMWNMX-UHFFFAOYSA-L sodium phosphonate pentahydrate Chemical compound [Na+].[Na+].[O-]P([O-])=O YPPQYORGOMWNMX-UHFFFAOYSA-L 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/37—Phosphates of heavy metals
- C01B25/375—Phosphates of heavy metals of iron
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/10—Solid density
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
A method for preparing high-compaction battery-grade ferric phosphate under a low-temperature condition belongs to the technical field of inorganic ferric salt preparation. The preparation method is characterized by comprising the following preparation steps: 1) Preparing mixed acid with the nitric acid and phosphoric acid in an acid preparation tank (10) according to a molar ratio of 9-15:1, wherein the total mass concentration of the mixed acid is 20-30%; 2) Iron powder or iron filings and mixed acid are added into a displacement reaction tank (1) for reaction; overflow port at top of displacement reaction tank (1) overflows supernatant from flowing into ozone oxidation tank (3) that lets in excessive ozone, ozone oxidation tank (3) blowing gets into sedimentation tank (8), adds complexing agent to sedimentation tank (8) simultaneously, and the supernatant of sedimentation tank (8) recycles, and the deposit is after discharging from deposit export (801), is obtained after washing, filtration, drying, calcination.
Description
Technical Field
A method for preparing high-compaction battery-grade ferric phosphate under a low-temperature condition belongs to the technical field of inorganic ferric salt preparation.
Background
The method for preparing the lithium iron phosphate by taking the ferric phosphate as a precursor is currently the main stream production process of lithium iron phosphate manufacturers, and the obtained lithium iron phosphate has the advantages of high specific capacity, high purity, high compaction density and the like. The production process has the advantages of simple process, low cost and the like. The main preparation method of the iron phosphate at present mainly comprises the following two steps:
The first method is as follows: ferric nitrate or ferric chloride is used as an iron source, and one or more of diammonium hydrogen phosphate, monoammonium phosphate, phosphoric acid or disodium hydrogen phosphate is used as a phosphorus source to react to prepare the ferric phosphate. However, the ferric salt cannot meet the current low-cost ferric phosphate market requirement due to the excessively high cost, and the route is gradually abandoned by manufacturers; the second method is to use ferrous sulfate (ferrous sulfate can be prepared from by-products of ferric sulfate and titanium dioxide) as an iron source, one or more of diammonium hydrogen phosphate, monoammonium phosphate, phosphoric acid or sodium dihydrogen phosphate as a phosphorus source, and prepare ferric phosphate by adding hydrogen peroxide for oxidation, which is a main stream process of a ferric phosphate manufacturer at present, however, the process inevitably has by-product ammonium salt (ammonium sulfate), a large amount of sulfate radicals are easy to adsorb on the surface of ferric phosphate and difficult to wash, a large amount of water is often needed in the washing process for reducing the sulfur content in the ferric phosphate, the environmental protection treatment cost is high, the existence of excessive sulfur can influence the performance of the lithium iron phosphate to a certain extent, and sulfur dioxide gas is released in the process of preparing the lithium iron phosphate, so that the environment is polluted.
Chinese patent CN105480960 discloses a method for preparing iron phosphate, which comprises placing iron in phosphoric acid solution, heating to perform iron-dissolving reaction to obtain reaction solution containing Fe (H 2PO4)2), adding hydrogen peroxide to the reaction solution to perform oxidation reaction, adding polyethylene glycol while continuing stirring to react Fe (H 2PO4)2) to generate iron phosphate, adding distilled water to the iron phosphate solution to perform hydrolysis reaction, performing solid-liquid separation on the hydrolyzed feed solution, washing the solid phase until the pH value reaches near neutral, spin-drying to obtain solid iron phosphate, and sequentially drying and dehydrating the spin-dried solid iron phosphate to form dehydrated iron phosphate; the preparation method takes pure iron as a raw material, takes phosphoric acid as a phosphorus source, and can avoid the introduction of impurities, but adopts hydrogen peroxide as an oxidant, when the hydrogen peroxide is mixed with a phosphoric acid solution containing ferrous, a system formed under stirring is a homogeneous system, but the hydrogen peroxide is added in a trickle mode, the feeding process is easily influenced by fluid flow to form a certain concentration gradient, the generation rate of ferric phosphate particles in a region with high concentration of the hydrogen peroxide is higher than that in a region with low concentration of the hydrogen peroxide, the reaction system is converted into liquid-solid phase reaction from homogeneous phase reaction, the formation of ferric phosphate solid phase can cause uneven mass transfer between solid-liquid phase substances, the particle size of the ferric phosphate particles is caused to be different due to the difference of the oxidation reaction rate, the generated ferric phosphate particle size is caused to have uneven distribution, the compaction density is lower, the generated ferric phosphate is not used for preparing a high-performance lithium battery, in addition, the polyethylene glycol dispersant added by the method remains in a product, the purity of the product can be reduced, and the pH value is adjusted by adding water, the water consumption is also large.
In addition, chinese patent CN201811137344.1 discloses a preparation method of high-purity high-compaction battery grade ferric phosphate, which comprises the steps of firstly reacting a certain amount of iron and 15-35% phosphoric acid at 40-100 ℃ to generate a phosphoric acid solution containing ferrous ions, then heating feed liquid to 60-100 ℃, adding a complexing agent, introducing ozone to oxidize for 3.5-7.5 hours to obtain ferric phosphate slurry, filtering the slurry, repeatedly washing and filtering a filter cake until the filter cake is neutral, drying the collected solid for 2-4 hours, and calcining at 400-600 ℃ for 2-4 hours to obtain the required ferric phosphate, wherein the complexing agent is one or more of ethylenediamine, triethanolamine, 2-hydroxyethylamine, 1, 2-propylenediamine, 1, 3-propylenediamine, succinamide and malonamide. The iron phosphate obtained by the method has the iron-phosphorus ratio of 0.96-0.99, the D95 granularity of 78-150 nanometers and the compacted density of 2.40-2.50 g/cc, and other impurities are not basically introduced except the complexing agent in the preparation method. However, the preparation method needs multiple times of heating, the reaction time of each step is as long as several hours, the production efficiency is lower in actual industrial production, the energy consumption is higher, and the preparation method is not suitable for large-scale industrialized popularization.
Disclosure of Invention
The invention aims to solve the technical problems that: overcomes the defects of the prior art and provides a method for preparing high-compaction battery-grade ferric phosphate under the low-temperature conditions with high production efficiency and low energy consumption.
The technical scheme adopted for solving the technical problems is as follows: the method for preparing the high-compaction battery-level ferric phosphate under the low-temperature condition is characterized by comprising the following preparation steps:
1) Preparing mixed acid: preparing mixed acid with the nitric acid and phosphoric acid in a mixed acid tank according to a molar ratio of 9-15:1, wherein the total mass concentration of the mixed acid is 20% -30%;
2) And (3) preparation of ferrous iron: iron powder or scrap iron is pre-arranged in an iron material storage tank at the top of the replacement reaction tank, and is added into the replacement reaction tank at a constant speed through a discharging air-closure device at a discharge hole of the iron material storage tank; the mixed acid prepared in the step 1) is pumped into a replacement reaction tank to react with iron powder or scrap iron;
3) Oxidation of ferrous iron: overflow port at top of the replacement reaction tank overflows supernatant fluid to the ozone oxidation tank, and excessive ozone is introduced while stirring in the ozone oxidation tank;
4) Sedimentation of materials: discharging the ozone oxidation tank into a sedimentation tank, adding a complexing agent into the sedimentation tank, and completing natural sedimentation in the sedimentation tank; returning supernatant of the sedimentation tank to the acid preparation tank for recycling; and discharging the sediment of the sedimentation tank from a sediment outlet, and washing, filtering, drying and calcining the sediment to obtain the catalyst.
Compared with pure phosphoric acid, the mixed acid prepared by nitric acid and phosphoric acid in a certain proportion and iron powder or reaction scrap iron has the concentration of H + which is far higher than that of PO 4 3+, is favorable for the shift reaction in ferrous preparation, and can reach a faster reaction rate at normal temperature.
The displacement reaction tank designed in the invention adopts a continuous feeding and continuous discharging mode, realizes continuous proceeding of the ferrite reaction process, and is beneficial to automation of industrial implementation. Adding complexing agent into a settling tank after ferrous iron is oxidized, and settling and separating.
After the PO 4 3+ in the settling tank has settled, the concentration of PO 4 3+ itself can drop to a very low level, creating an environment for the nitric acid solution in the settling tank. Because iron phosphate is insoluble in nitric acid, the environment is more conducive to settling and the resulting iron phosphate has a greater compacted density.
The nitric acid and excessive iron ions in the supernatant in the sedimentation tank are returned to the acid matching tank for recycling. Because nitric acid is basically not lost in the whole preparation process, the acid preparation can be completed again only by supplementing phosphoric acid. The nitric acid in the invention achieves the effect similar to a catalyst, and only accelerates the reaction rate without loss; and the sedimentation of the ferric phosphate can be promoted by utilizing the characteristic that the ferric phosphate is insoluble in nitric acid.
Preferably, in the method for preparing the high-compaction battery-grade ferric phosphate under the low-temperature condition, the molar ratio of nitric acid to phosphoric acid in the mixed acid in the step 1) is 11-12:1, and the total mass concentration of the mixed acid is 23% -26%. The preferable proportion of the mixed acid can ensure the reaction rate better, ensure the complexing rate of phosphorus during sedimentation and improve the single yield.
In the preferred method for preparing the high-compaction battery-level ferric phosphate under the low-temperature condition, a filter screen is arranged in the replacement reaction tank, and a discharge hole of the iron material storage tank extends below the filter screen through a discharging pipe. A filter screen is arranged in the replacement reaction tank to prevent unreacted iron powder or scrap iron from entering a subsequent device from supernatant.
Preferably, the molar ratio of H + to Fe in unreacted iron powder or iron filings in the reaction system in the replacement reaction tank is kept at 15:4-6. In the invention, the absolute excess of H + relative to iron is kept in the whole process, the reaction rate is improved by improving the concentration of H +, and the efficient preparation can be kept without heating. And Fe 3+ can be kept excessive relative to PO 4 3+, so that the forward progress of the complexing reaction is facilitated, the reaction rate of PO 4 3+ is improved, and the compacted higher ferric phosphate product obtained by precipitation is promoted.
The molar ratio of H + to Fe in the reaction system needs to be determined by periodic sampling measurement from the inside of the substitution reaction tank, and the rate of adding iron or acid is adjusted. Because nitric acid is recycled, iron and a filter screen are used for preventing the nitric acid and the iron from entering the next process, the excessive amount of the nitric acid and the iron is mainly required to be kept in a reaction system, the specific proportion is not required to be very accurate, and the nitric acid and the iron are only required to be kept in a certain range, and the specific proportion is not required to be kept.
In the preferred method for preparing the high-compaction battery-level ferric phosphate under the low-temperature condition, a supernatant temporary storage tank is arranged in front of the ozone oxidation tank, and overflow ports at the top of the replacement reaction tank overflow supernatant into the supernatant temporary storage tank, and then the supernatant is fed into the ozone oxidation tank in batches from the supernatant temporary storage tank. The supernatant continuously extracted from the top of the reaction tank is replaced, and the ozone oxidation tank can be subjected to more thorough oxidation within the accumulation time of the supernatant in the supernatant temporary storage tank, so that the oxidation rate of ferrous iron is ensured. The addition of the supernatant temporary storage tank makes the invention more suitable for industrial application.
The ozone oxidation tank is connected with the sedimentation tank through a discharge pipeline, a venturi feeder is arranged on the discharge pipeline, and a complexing agent storage tank is connected with a feed inlet of the venturi feeder; the complexing agent enters a discharging pipeline through a Venturi feeder. The venturi feeder is utilized to realize unpowered automatic addition of the complexing agent, and the method is suitable for industrial production.
Preferably, the method for preparing the high-compaction battery-grade ferric phosphate under the low-temperature condition is characterized in that a venturi feeder and a pipeline mixer are sequentially arranged on the discharge pipeline, and the complexing agent enters the discharge pipeline through the venturi feeder and then enters a sedimentation tank for sedimentation after being mixed with materials discharged by the ozone oxidation tank through the pipeline mixer. The complexing agent and the material are mixed uniformly by a pipeline mixer and then enter a sedimentation tank for sedimentation, the particle size of the sediment is more uniform, and the compactness of the obtained ferric phosphate product is higher.
The acid preparation tank is connected with a water supplementing pipeline and an acid supplementing pipeline, and the acid supplementing pipeline is connected to a connecting pipeline of the acid preparation tank and the acid transfer pump through a pump front tee joint; the outlet pipeline of the acid transfer pump is connected with a circulating pipeline through a rear tee joint of the pump, the circulating pipeline is connected with a back acid tank, and valves are arranged on all sections of pipelines connected with the front tee joint of the pump and the rear tee joint of the pump. The pipeline design on the acid transfer pump can enable the acid transfer pump to supply acid for a subsequent replacement reaction tank and also can be used for supplementing acid for an acid preparation tank. The acid supply rate of the displacement reaction tank can be adjusted through the control of the valve size. Meanwhile, the acid transfer pump can also realize the mixing function for the self-circulation of the acid mixing tank.
The complexing agent is one or more than two of ethylenediamine tetramethylene phosphate (EDTMPS), diethylenetriamine pentamethylene phosphonate (DETPMPS) and amine trimethoyl phosphate in any proportion; the adding amount of the complexing agent is 0.1-0.2% of the discharging mass of the ozone oxidation tank. The complexing agent selected by the invention can be suitable for the low pH acid environment, the dosage is small, the sedimentation of ferric phosphate is thorough, and the single conversion rate is high. When the product is washed, hot water can be used for washing, and after washing liquid is collected, the cooling crystallization can recycle part of complexing agent.
More preferably, the complexing agent is ethylenediamine tetramethylene phosphate and amine trimethylene phosphate according to a mass ratio of 10: 1-7 of a compound complexing agent; the adding amount of the complexing agent is 0.13-0.16% of the discharging mass of the ozone oxidation tank. The preferable compounding complexing agent ratio has better adaptability to the low pH acid environment and better complexing effect.
Compared with the prior art, the method for preparing the high-compaction battery-level ferric phosphate under the low-temperature condition has the following beneficial effects: compared with pure phosphoric acid, the mixed acid prepared by nitric acid and phosphoric acid in a certain proportion and iron powder or reaction scrap iron has the concentration of H + which is far higher than that of PO 4 3+, is favorable for the shift reaction in ferrous preparation, and can reach a faster reaction rate at normal temperature.
The displacement reaction tank designed in the invention adopts a continuous feeding and continuous discharging mode, realizes continuous proceeding of the ferrite reaction process, and is beneficial to automation of industrial implementation. Adding complexing agent into a settling tank after ferrous iron is oxidized, and settling and separating. After the PO 4 3+ in the settling tank has settled, the concentration of PO 4 3+ itself can drop to a very low level, creating an environment for the nitric acid solution in the settling tank. Because iron phosphate is insoluble in nitric acid, the environment is more conducive to settling and the resulting iron phosphate has a greater compacted density. The nitric acid and excessive iron ions in the supernatant in the sedimentation tank are returned to the acid matching tank for recycling. Because nitric acid is basically not lost in the whole preparation process, the acid preparation can be completed again only by supplementing phosphoric acid. The nitric acid in the invention achieves the effect similar to a catalyst, and only accelerates the reaction rate without loss; and the sedimentation of the ferric phosphate can be promoted by utilizing the characteristic that the ferric phosphate is insoluble in nitric acid.
In the invention, the absolute excess of H + relative to iron is kept in the whole process, the reaction rate is improved by improving the concentration of H +, and the efficient preparation can be kept without heating. And Fe 3+ can be kept excessive relative to PO 4 3+, so that the forward progress of the complexing reaction is facilitated, the reaction rate of PO 4 3+ is improved, and the compacted higher ferric phosphate product obtained by precipitation is promoted.
Drawings
FIG. 1 is a schematic flow chart of a method of preparing high-compaction battery grade iron phosphate at low temperature according to the present invention.
Wherein, 1, a replacement reaction tank 101, a filter screen 2, an iron material storage tank 201, a discharging air-lock 3, an ozone oxidation tank 4, an ozone generator 5, a complexing agent storage tank 6, a venturi feeder 7, a pipeline mixer 8, a sedimentation tank 801, a sediment outlet 9, a clear liquid pump 10, an acid distribution tank 1001, a water supplementing pipeline 1002, an acid supplementing pipeline 11 and an acid transfer pump.
Detailed Description
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present application. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and the terms "comprising" and "having" and any variation thereof are intended to cover a non-exclusive inclusion, e.g., a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other.
The invention will be further described with reference to fig. 1 in conjunction with the specific embodiment, wherein embodiment 1 is the best mode.
Example 1
1) Preparing mixed acid: preparing mixed acid of nitric acid and phosphoric acid in a molar ratio of 12:1 in an acid preparation tank 10, wherein the total mass concentration of the mixed acid is 25%;
2) And (3) preparation of ferrous iron: iron powder or scrap iron is preloaded into an iron material storage tank 2 at the top of a replacement reaction tank 1, a filter screen 101 is arranged in the replacement reaction tank 1, a discharge port of the iron material storage tank 2 extends below the filter screen 101 through a blanking pipe, and the iron powder or scrap iron is added into the replacement reaction tank 1 at a constant speed through a discharge air closer 201 at the discharge port of the iron material storage tank 2; the mixed acid prepared in the step 1) is pumped into a replacement reaction tank 1 through an acid transfer pump 11 to react with iron powder or scrap iron, and the molar ratio of H + to Fe in unreacted iron powder or scrap iron is kept between 15:4.5 and 5 by controlling the feeding rate of the mixed acid and the iron in a reaction system;
3) Oxidation of ferrous iron: the overflow port at the top of the replacement reaction tank 1 overflows the supernatant fluid to flow into a supernatant fluid temporary storage tank, the supernatant fluid is fed into an ozone oxidation tank 3 from the supernatant fluid temporary storage tank in batches, and excessive ozone is introduced by an ozone generator 4 while stirring in the ozone oxidation tank 3 to oxidize ferrous iron;
4) Sedimentation of materials: ozone oxidation jar 3 passes through the discharge pipeline and connects sedimentation tank 8, is equipped with venturi feeder 6 on the discharge pipeline, is connected with complexing agent storage tank 5 on the feed inlet of venturi feeder 6, prestores ethylenediamine tetramethylene sodium phosphate and amine sodium trimethylene phosphate in complexing agent storage tank 5 according to mass ratio 10: 4a complexing agent compounded; the complexing agent enters a discharging pipeline through a Venturi feeder 6, and the adding amount of the complexing agent is 0.15% of the single discharging mass of the ozone oxidation tank 3; then the mixture and the materials are mixed by a material mixer 7 and then enter a sedimentation tank 8 together to finish natural sedimentation; supernatant of the sedimentation tank 8 is pumped back to the acid preparation tank 10 by the supernatant pump 9 for recycling; the sediment of the sedimentation tank 8 is discharged from a sediment outlet 801 and is obtained after washing, filtering, drying and calcining. The obtained battery grade ferric phosphate has the iron content of 29.4%, the iron-phosphorus ratio of 0.996, the total residual impurity content of less than 0.006%, the D95 granularity of 126 nanometers and the compacted density of 2.51 grams per cubic centimeter.
Example 2
1) Preparing mixed acid: preparing mixed acid of nitric acid and phosphoric acid in a mixed acid tank 10 according to a molar ratio of 12:1, wherein the total mass concentration of the mixed acid is 23%;
2) And (3) preparation of ferrous iron: iron powder or scrap iron is preloaded into an iron material storage tank 2 at the top of a replacement reaction tank 1, a filter screen 101 is arranged in the replacement reaction tank 1, a discharge port of the iron material storage tank 2 extends below the filter screen 101 through a blanking pipe, and the iron powder or scrap iron is added into the replacement reaction tank 1 at a constant speed through a discharge air closer 201 at the discharge port of the iron material storage tank 2; the mixed acid prepared in the step 1) is pumped into a replacement reaction tank 1 through an acid transfer pump 11 to react with iron powder or scrap iron, and the molar ratio of H + to Fe in unreacted iron powder or scrap iron is kept between 15:5 and 5.5 by controlling the feeding rate of the mixed acid and the iron in a reaction system;
3) Oxidation of ferrous iron: the overflow port at the top of the replacement reaction tank 1 overflows the supernatant fluid to flow into a supernatant fluid temporary storage tank, the supernatant fluid is fed into an ozone oxidation tank 3 from the supernatant fluid temporary storage tank in batches, and excessive ozone is introduced by an ozone generator 4 while stirring in the ozone oxidation tank 3 to oxidize ferrous iron;
4) Sedimentation of materials: ozone oxidation jar 3 passes through the discharge pipeline and connects sedimentation tank 8, is equipped with venturi feeder 6 on the discharge pipeline, is connected with complexing agent storage tank 5 on the feed inlet of venturi feeder 6, prestores ethylenediamine tetramethylene sodium phosphate and amine sodium trimethylene phosphate in complexing agent storage tank 5 according to mass ratio 10:7, complexing agent compounded; the complexing agent enters a discharging pipeline through a Venturi feeder 6, and the adding amount of the complexing agent is 0.13% of the discharging mass of the ozone oxidation tank 3; then the mixture and the materials are mixed by a material mixer 7 and then enter a sedimentation tank 8 together to finish natural sedimentation; supernatant of the sedimentation tank 8 is pumped back to the acid preparation tank 10 by the supernatant pump 9 for recycling; the sediment of the sedimentation tank 8 is discharged from a sediment outlet 801 and is obtained after washing, filtering, drying and calcining. The obtained battery grade ferric phosphate is measured, the iron-phosphorus ratio is 0.994, the total residual impurity amount is less than 0.006 percent, the D95 granularity is 127 nanometers, and the compaction density is 2.48 grams/cubic centimeter.
Example 3
1) Preparing mixed acid: preparing mixed acid of nitric acid and phosphoric acid in a molar ratio of 11:1 in an acid preparation tank 10, wherein the total mass concentration of the mixed acid is 26%;
2) And (3) preparation of ferrous iron: iron powder or scrap iron is preloaded into an iron material storage tank 2 at the top of a replacement reaction tank 1, a filter screen 101 is arranged in the replacement reaction tank 1, a discharge port of the iron material storage tank 2 extends below the filter screen 101 through a blanking pipe, and the iron powder or scrap iron is added into the replacement reaction tank 1 at a constant speed through a discharge air closer 201 at the discharge port of the iron material storage tank 2; the mixed acid prepared in the step 1) is pumped into a replacement reaction tank 1 through an acid transfer pump 11 to react with iron powder or scrap iron, and the molar ratio of H + to Fe in unreacted iron powder or scrap iron is kept between 15:5 and 5.5 by controlling the feeding rate of the mixed acid and the iron in a reaction system;
3) Oxidation of ferrous iron: the overflow port at the top of the replacement reaction tank 1 overflows the supernatant fluid to flow into a supernatant fluid temporary storage tank, the supernatant fluid is fed into an ozone oxidation tank 3 from the supernatant fluid temporary storage tank in batches, and excessive ozone is introduced by an ozone generator 4 while stirring in the ozone oxidation tank 3 to oxidize ferrous iron;
4) Sedimentation of materials: ozone oxidation jar 3 passes through the discharge pipeline and connects sedimentation tank 8, is equipped with venturi feeder 6 on the discharge pipeline, is connected with complexing agent storage tank 5 on the feed inlet of venturi feeder 6, prestores ethylenediamine tetramethylene sodium phosphate and amine sodium trimethylene phosphate in complexing agent storage tank 5 according to mass ratio 10: 1a complexing agent compounded; the complexing agent enters a discharging pipeline through a Venturi feeder 6, and the adding amount of the complexing agent is 0.16% of the discharging mass of the ozone oxidation tank 3; then the mixture and the materials are mixed by a material mixer 7 and then enter a sedimentation tank 8 together to finish natural sedimentation; supernatant of the sedimentation tank 8 is pumped back to the acid preparation tank 10 by the supernatant pump 9 for recycling; the sediment of the sedimentation tank 8 is discharged from a sediment outlet 801 and is obtained after washing, filtering, drying and calcining. The obtained battery grade ferric phosphate is measured, the iron-phosphorus ratio is 0.991, the total residual impurity amount is less than 0.006 percent, the D95 granularity is 129 nanometers, and the compacted density is 2.46 grams per cubic centimeter.
Example 4
1) Preparing mixed acid: preparing mixed acid of nitric acid and phosphoric acid in a molar ratio of 9:1 in an acid preparation tank 10, wherein the total mass concentration of the mixed acid is 30%;
2) And (3) preparation of ferrous iron: iron powder or scrap iron is preloaded into an iron material storage tank 2 at the top of a replacement reaction tank 1, a filter screen 101 is arranged in the replacement reaction tank 1, a discharge port of the iron material storage tank 2 extends below the filter screen 101 through a blanking pipe, and the iron powder or scrap iron is added into the replacement reaction tank 1 at a constant speed through a discharge air closer 201 at the discharge port of the iron material storage tank 2; the mixed acid prepared in the step 1) is pumped into a replacement reaction tank 1 through an acid transfer pump 11 to react with iron powder or scrap iron, and the molar ratio of H + to Fe in unreacted iron powder or scrap iron is kept between 15:4 and 4.5 by controlling the feeding rate of the mixed acid and the iron in a reaction system;
3) Oxidation of ferrous iron: the overflow port at the top of the replacement reaction tank 1 overflows the supernatant fluid to flow into a supernatant fluid temporary storage tank, the supernatant fluid is fed into an ozone oxidation tank 3 from the supernatant fluid temporary storage tank in batches, and excessive ozone is introduced by an ozone generator 4 while stirring in the ozone oxidation tank 3 to oxidize ferrous iron;
4) Sedimentation of materials: the ozone oxidation tank 3 is connected with a sedimentation tank 8 through a discharge pipeline, a venturi feeder 6 is arranged on the discharge pipeline, a complexing agent storage tank 5 is connected to a feed inlet of the venturi feeder 6, and an ethylenediamine tetramethylene sodium phosphate complexing agent is pre-stored in the complexing agent storage tank 5; the complexing agent enters a discharging pipeline through a Venturi feeder 6, and the adding amount of the complexing agent is 0.1% of the discharging mass of the ozone oxidation tank 3; then the mixture and the materials are mixed by a material mixer 7 and then enter a sedimentation tank 8 together to finish natural sedimentation; supernatant of the sedimentation tank 8 is pumped back to the acid preparation tank 10 by the supernatant pump 9 for recycling; the sediment of the sedimentation tank 8 is discharged from a sediment outlet 801 and is obtained after washing, filtering, drying and calcining. The obtained battery grade ferric phosphate has the advantages that the iron-phosphorus ratio is 0.989, the total residual impurity amount is less than 0.006%, the D95 granularity is 134 nanometers, and the compacted density is 2.41 grams/cubic centimeter.
Example 5
1) Preparing mixed acid: preparing mixed acid of nitric acid and phosphoric acid in a molar ratio of 15:1 in an acid preparation tank 10, wherein the total mass concentration of the mixed acid is 20%;
2) And (3) preparation of ferrous iron: iron powder or scrap iron is preloaded into an iron material storage tank 2 at the top of a replacement reaction tank 1, a filter screen 101 is arranged in the replacement reaction tank 1, a discharge port of the iron material storage tank 2 extends below the filter screen 101 through a blanking pipe, and the iron powder or scrap iron is added into the replacement reaction tank 1 at a constant speed through a discharge air closer 201 at the discharge port of the iron material storage tank 2; the mixed acid prepared in the step 1) is pumped into a replacement reaction tank 1 through an acid transfer pump 11 to react with iron powder or scrap iron, and the molar ratio of H + to Fe in unreacted iron powder or scrap iron is kept at 15:5.5-6 by controlling the feeding rate of the mixed acid and the iron in a reaction system;
3) Oxidation of ferrous iron: the overflow port at the top of the replacement reaction tank 1 overflows the supernatant fluid to flow into a supernatant fluid temporary storage tank, the supernatant fluid is fed into an ozone oxidation tank 3 from the supernatant fluid temporary storage tank in batches, and excessive ozone is introduced by an ozone generator 4 while stirring in the ozone oxidation tank 3 to oxidize ferrous iron;
4) Sedimentation of materials: the ozone oxidation tank 3 is connected with the sedimentation tank 8 through a discharge pipeline, a venturi feeder 6 is arranged on the discharge pipeline, a complexing agent storage tank 5 is connected to a feed inlet of the venturi feeder 6, and a diethylenetriamine penta-methylene sodium phosphonate complexing agent is pre-stored in the complexing agent storage tank 5; the complexing agent enters a discharging pipeline through a Venturi feeder 6, and the adding amount of the complexing agent is 0.2% of the discharging mass of the ozone oxidation tank 3; then the mixture and the materials are mixed by a material mixer 7 and then enter a sedimentation tank 8 together to finish natural sedimentation; supernatant of the sedimentation tank 8 is pumped back to the acid preparation tank 10 by the supernatant pump 9 for recycling; the sediment of the sedimentation tank 8 is discharged from a sediment outlet 801 and is obtained after washing, filtering, drying and calcining. The obtained battery grade ferric phosphate has the advantages that the iron-phosphorus ratio is 0.987, the total residual impurity amount is less than 0.006%, the D95 granularity is 130 nanometers, and the compacted density is 2.43 g/cc.
Comparative example 1
The process flow and process conditions were the same as in example 1, except that: the molar ratio of nitric acid to phosphoric acid in the mixed acid prepared in the step 1) is 1:1, and the total mass concentration of the mixed acid is still 25%. In this case, the amount of phosphoric acid was increased, the reaction rate in the displacement reaction tank 1 was significantly reduced, the concentration of phosphoric acid in the sedimentation tank 8 was also increased, the sedimentation rate and sedimentation rate were affected, and the single yield was reduced, and the resulting iron phosphate D95 had a particle size of 278 nm and a compacted density of 1.78 g/cc.
Comparative example 2
The process flow and process conditions were the same as in example 1, except that: the complexing agent used in step 4) is the same amount of ethylenediamine. In this case, the complexing agent ethylenediamine is not suitable for the low pH environment in the sedimentation tank 8, the complexing effect is not obvious, and the yield is low. The resulting iron phosphate D95 particle size was 196 nm and the compacted density was 2.13 g/cc.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the invention in any way, and any person skilled in the art may make modifications or alterations to the disclosed technical content to the equivalent embodiments. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (8)
1. The method for preparing the high-compaction battery-grade ferric phosphate under the low-temperature condition is characterized by comprising the following preparation steps:
1) Preparing mixed acid: preparing mixed acid with the nitric acid and phosphoric acid in an acid preparation tank (10) according to a molar ratio of 9-15:1, wherein the total mass concentration of the mixed acid is 20-30%;
2) And (3) preparation of ferrous iron: iron powder or scrap iron is pre-arranged in an iron material storage tank (2) at the top of a replacement reaction tank (1), and is added into the replacement reaction tank (1) at a constant speed through a discharging air-closure device (201) at a discharge hole of the iron material storage tank (2); the mixed acid prepared in the step 1) is pumped into a replacement reaction tank (1) to react with iron powder or scrap iron, wherein the molar ratio of H + to Fe in unreacted iron powder or scrap iron is kept to be 15:4-6 in a reaction system in the replacement reaction tank (1);
3) Oxidation of ferrous iron: overflow ports at the top of the replacement reaction tank (1) overflow supernatant fluid and flow into the ozone oxidation tank (3), and excessive ozone is introduced while stirring in the ozone oxidation tank (3);
4) Sedimentation of materials: discharging the ozone oxidation tank (3) into a sedimentation tank (8), adding a complexing agent into the sedimentation tank (8), and completing natural sedimentation in the sedimentation tank (8); the complexing agent is one or more than two of ethylenediamine tetramethylene phosphate, diethylenetriamine pentamethylenephosphonate and amine trimethoprim; the adding amount of the complexing agent is 0.1-0.2% of the discharging mass of the ozone oxidation tank (3); returning the supernatant of the sedimentation tank (8) to the acid preparation tank (10) for recycling; and discharging the sediment of the sedimentation tank (8) from a sediment outlet (801), and washing, filtering, drying and calcining the sediment to obtain the catalyst.
2. The method for preparing high-compaction battery grade iron phosphate at low temperature according to claim 1, wherein:
the molar ratio of nitric acid to phosphoric acid in the mixed acid in the step 1) is 11-12:1, and the total mass concentration of the mixed acid is 23-26%.
3. The method for preparing high-compaction battery grade iron phosphate at low temperature according to claim 1, wherein:
a filter screen (101) is arranged in the replacement reaction tank (1), and a discharge hole of the iron material storage tank (2) extends to below the filter screen (101) through a discharging pipe.
4. The method for preparing high-compaction battery grade iron phosphate at low temperature according to claim 1, wherein:
The device is characterized in that a supernatant temporary storage tank is arranged in front of the ozone oxidation tank (3), and overflow ports at the top of the replacement reaction tank (1) overflow supernatant into the supernatant temporary storage tank, and then the supernatant is fed into the ozone oxidation tank (3) in batches from the supernatant temporary storage tank.
5. The method for preparing high-compaction battery grade iron phosphate at low temperature according to claim 1, wherein:
The ozone oxidation tank (3) is connected with the sedimentation tank (8) through a discharge pipeline, a venturi feeder (6) is arranged on the discharge pipeline, and a complexing agent storage tank (5) is connected to a feed inlet of the venturi feeder (6); the complexing agent enters a discharging pipeline through a Venturi feeder (6).
6. The method for preparing high-compaction battery grade iron phosphate according to claim 5, wherein:
The discharging pipeline is provided with a Venturi feeder (6) and a pipeline mixer (7) in sequence, and the complexing agent enters the discharging pipeline through the Venturi feeder (6) and then enters a sedimentation tank (8) for sedimentation after being mixed with materials placed in the ozone oxidation tank (3) through the pipeline mixer (7).
7. The method for preparing high-compaction battery grade iron phosphate at low temperature according to claim 1, wherein:
The acid preparation tank (10) is connected with a water supplementing pipeline (1001) and an acid supplementing pipeline (1002), and the acid supplementing pipeline (1002) is connected to a connecting pipeline of the acid preparation tank (10) and the acid transfer pump (11) through a front tee joint of the pump; the outlet pipeline of the acid transfer pump (11) is connected with a circulating pipeline through a pump rear tee joint, the circulating pipeline is connected with a back acid tank (10), and valves are arranged on all sections of pipelines connected with the pump front tee joint and the pump rear tee joint.
8. The method for preparing high-compaction battery grade iron phosphate at low temperature according to claim 1, wherein:
the complexing agent is ethylenediamine tetramethylene phosphate and amine trimethylene phosphate according to the mass ratio of 10: 1-7 of a compound complexing agent; the adding amount of the complexing agent is 0.13-0.16% of the discharging mass of the ozone oxidation tank (3).
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