CN116750735A - Wet phosphoric acid purification method - Google Patents
Wet phosphoric acid purification method Download PDFInfo
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- CN116750735A CN116750735A CN202310580105.8A CN202310580105A CN116750735A CN 116750735 A CN116750735 A CN 116750735A CN 202310580105 A CN202310580105 A CN 202310580105A CN 116750735 A CN116750735 A CN 116750735A
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- phosphoric acid
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- extractant
- wet process
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- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 title claims abstract description 434
- 229910000147 aluminium phosphate Inorganic materials 0.000 title claims abstract description 217
- 238000000034 method Methods 0.000 title claims abstract description 106
- 238000000746 purification Methods 0.000 title claims abstract description 40
- 238000000605 extraction Methods 0.000 claims abstract description 105
- 239000000725 suspension Substances 0.000 claims abstract description 37
- 238000002425 crystallisation Methods 0.000 claims abstract description 33
- 230000008025 crystallization Effects 0.000 claims abstract description 33
- 238000005406 washing Methods 0.000 claims abstract description 27
- 239000012535 impurity Substances 0.000 claims abstract description 24
- 150000001768 cations Chemical class 0.000 claims abstract description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910052751 metal Inorganic materials 0.000 claims abstract description 13
- 239000002184 metal Substances 0.000 claims abstract description 13
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 8
- 239000011777 magnesium Substances 0.000 claims abstract description 8
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 8
- 229910052742 iron Inorganic materials 0.000 claims abstract description 7
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims description 50
- 239000007788 liquid Substances 0.000 claims description 48
- 239000002904 solvent Substances 0.000 claims description 44
- 239000013078 crystal Substances 0.000 claims description 33
- 239000012452 mother liquor Substances 0.000 claims description 22
- 238000002156 mixing Methods 0.000 claims description 21
- 239000003085 diluting agent Substances 0.000 claims description 19
- -1 amino, carboxyl Chemical group 0.000 claims description 18
- 239000003795 chemical substances by application Substances 0.000 claims description 16
- 239000011259 mixed solution Substances 0.000 claims description 16
- OJMIONKXNSYLSR-UHFFFAOYSA-N phosphorous acid Chemical compound OP(O)O OJMIONKXNSYLSR-UHFFFAOYSA-N 0.000 claims description 16
- 238000000926 separation method Methods 0.000 claims description 15
- 238000006243 chemical reaction Methods 0.000 claims description 14
- 239000003337 fertilizer Substances 0.000 claims description 14
- 238000002844 melting Methods 0.000 claims description 12
- 230000008018 melting Effects 0.000 claims description 12
- 239000000706 filtrate Substances 0.000 claims description 11
- 239000000047 product Substances 0.000 claims description 11
- 239000002002 slurry Substances 0.000 claims description 11
- 238000003756 stirring Methods 0.000 claims description 11
- 229910019142 PO4 Inorganic materials 0.000 claims description 10
- 239000010452 phosphate Substances 0.000 claims description 10
- 238000004537 pulping Methods 0.000 claims description 10
- 238000007865 diluting Methods 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 7
- 239000007787 solid Substances 0.000 claims description 7
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 6
- 229910052731 fluorine Inorganic materials 0.000 claims description 6
- 239000011737 fluorine Substances 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- ZSIAUFGUXNUGDI-UHFFFAOYSA-N hexan-1-ol Chemical compound CCCCCCO ZSIAUFGUXNUGDI-UHFFFAOYSA-N 0.000 claims description 6
- 238000004062 sedimentation Methods 0.000 claims description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 5
- 239000000654 additive Substances 0.000 claims description 5
- 239000011575 calcium Substances 0.000 claims description 5
- 229910052791 calcium Inorganic materials 0.000 claims description 5
- KBPLFHHGFOOTCA-UHFFFAOYSA-N 1-Octanol Chemical compound CCCCCCCCO KBPLFHHGFOOTCA-UHFFFAOYSA-N 0.000 claims description 4
- BBMCTIGTTCKYKF-UHFFFAOYSA-N 1-heptanol Chemical compound CCCCCCCO BBMCTIGTTCKYKF-UHFFFAOYSA-N 0.000 claims description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 4
- PHTQWCKDNZKARW-UHFFFAOYSA-N isoamylol Chemical compound CC(C)CCO PHTQWCKDNZKARW-UHFFFAOYSA-N 0.000 claims description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 3
- AMQJEAYHLZJPGS-UHFFFAOYSA-N N-Pentanol Chemical compound CCCCCO AMQJEAYHLZJPGS-UHFFFAOYSA-N 0.000 claims description 3
- 239000007983 Tris buffer Substances 0.000 claims description 3
- 239000000460 chlorine Substances 0.000 claims description 3
- 229910052801 chlorine Inorganic materials 0.000 claims description 3
- HSZCIIHXQDBPOI-UHFFFAOYSA-N fluorourea Chemical compound NC(=O)NF HSZCIIHXQDBPOI-UHFFFAOYSA-N 0.000 claims description 3
- 150000003013 phosphoric acid derivatives Chemical class 0.000 claims description 3
- 238000004064 recycling Methods 0.000 claims description 3
- 239000000243 solution Substances 0.000 claims description 3
- 125000003698 tetramethyl group Chemical group [H]C([H])([H])* 0.000 claims description 3
- CNUJLMSKURPSHE-UHFFFAOYSA-N trioctadecyl phosphite Chemical compound CCCCCCCCCCCCCCCCCCOP(OCCCCCCCCCCCCCCCCCC)OCCCCCCCCCCCCCCCCCC CNUJLMSKURPSHE-UHFFFAOYSA-N 0.000 claims description 3
- OPNUROKCUBTKLF-UHFFFAOYSA-N 1,2-bis(2-methylphenyl)guanidine Chemical compound CC1=CC=CC=C1N\C(N)=N\C1=CC=CC=C1C OPNUROKCUBTKLF-UHFFFAOYSA-N 0.000 claims description 2
- CCZMQYGSXWZFKI-UHFFFAOYSA-N 1-chloro-4-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=C(OP(Cl)(Cl)=O)C=C1 CCZMQYGSXWZFKI-UHFFFAOYSA-N 0.000 claims description 2
- YZBOZNXACBQJHI-UHFFFAOYSA-N 1-dichlorophosphoryloxyethane Chemical compound CCOP(Cl)(Cl)=O YZBOZNXACBQJHI-UHFFFAOYSA-N 0.000 claims description 2
- KUQZVISZELWDNZ-UHFFFAOYSA-N 3-aminopropyl dihydrogen phosphate Chemical compound NCCCOP(O)(O)=O KUQZVISZELWDNZ-UHFFFAOYSA-N 0.000 claims description 2
- OSBJUINXNAJWND-UHFFFAOYSA-N CC1=CC=CC=C1OP(=O)(O)Cl Chemical compound CC1=CC=CC=C1OP(=O)(O)Cl OSBJUINXNAJWND-UHFFFAOYSA-N 0.000 claims description 2
- JKIJEFPNVSHHEI-UHFFFAOYSA-N Phenol, 2,4-bis(1,1-dimethylethyl)-, phosphite (3:1) Chemical compound CC(C)(C)C1=CC(C(C)(C)C)=CC=C1OP(OC=1C(=CC(=CC=1)C(C)(C)C)C(C)(C)C)OC1=CC=C(C(C)(C)C)C=C1C(C)(C)C JKIJEFPNVSHHEI-UHFFFAOYSA-N 0.000 claims description 2
- ZAFAJHDHPYDVCN-UHFFFAOYSA-N butanoic acid;phosphoric acid Chemical compound OP(O)(O)=O.CCCC(O)=O ZAFAJHDHPYDVCN-UHFFFAOYSA-N 0.000 claims description 2
- ITVPBBDAZKBMRP-UHFFFAOYSA-N chloro-dioxido-oxo-$l^{5}-phosphane;hydron Chemical compound OP(O)(Cl)=O ITVPBBDAZKBMRP-UHFFFAOYSA-N 0.000 claims description 2
- HPXRVTGHNJAIIH-UHFFFAOYSA-N cyclohexanol Chemical compound OC1CCCCC1 HPXRVTGHNJAIIH-UHFFFAOYSA-N 0.000 claims description 2
- 229910052736 halogen Inorganic materials 0.000 claims description 2
- 150000002367 halogens Chemical group 0.000 claims description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 2
- 239000003350 kerosene Substances 0.000 claims description 2
- MIABSAQIFYEDJP-UHFFFAOYSA-N perfluorodecyl phosphate Chemical compound OP(O)(=O)OCCC(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)F MIABSAQIFYEDJP-UHFFFAOYSA-N 0.000 claims description 2
- 125000001424 substituent group Chemical group 0.000 claims description 2
- 238000006467 substitution reaction Methods 0.000 claims description 2
- 125000003396 thiol group Chemical group [H]S* 0.000 claims description 2
- SJHCUXCOGGKFAI-UHFFFAOYSA-N tripropan-2-yl phosphite Chemical compound CC(C)OP(OC(C)C)OC(C)C SJHCUXCOGGKFAI-UHFFFAOYSA-N 0.000 claims description 2
- WGKLOLBTFWFKOD-UHFFFAOYSA-N tris(2-nonylphenyl) phosphite Chemical compound CCCCCCCCCC1=CC=CC=C1OP(OC=1C(=CC=CC=1)CCCCCCCCC)OC1=CC=CC=C1CCCCCCCCC WGKLOLBTFWFKOD-UHFFFAOYSA-N 0.000 claims description 2
- BHYQWBKCXBXPKM-UHFFFAOYSA-N tris[3-bromo-2,2-bis(bromomethyl)propyl] phosphate Chemical compound BrCC(CBr)(CBr)COP(=O)(OCC(CBr)(CBr)CBr)OCC(CBr)(CBr)CBr BHYQWBKCXBXPKM-UHFFFAOYSA-N 0.000 claims description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 claims 2
- 229910052785 arsenic Inorganic materials 0.000 claims 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims 1
- 230000000996 additive effect Effects 0.000 claims 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 claims 1
- 229910052708 sodium Inorganic materials 0.000 claims 1
- 239000011734 sodium Substances 0.000 claims 1
- 239000002253 acid Substances 0.000 abstract description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 7
- 239000000463 material Substances 0.000 abstract description 5
- 239000002994 raw material Substances 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 3
- 238000010790 dilution Methods 0.000 abstract description 2
- 239000012895 dilution Substances 0.000 abstract description 2
- 239000012071 phase Substances 0.000 description 21
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical compound O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 description 18
- 239000006185 dispersion Substances 0.000 description 16
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 12
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 10
- 238000001914 filtration Methods 0.000 description 9
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 8
- 239000002245 particle Substances 0.000 description 7
- 239000002367 phosphate rock Substances 0.000 description 7
- 238000004945 emulsification Methods 0.000 description 6
- 125000002091 cationic group Chemical group 0.000 description 5
- 239000000395 magnesium oxide Substances 0.000 description 5
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 4
- 235000006408 oxalic acid Nutrition 0.000 description 4
- 229920002401 polyacrylamide Polymers 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000000638 solvent extraction Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 description 1
- 238000009388 chemical precipitation Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000009775 high-speed stirring Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000008301 phosphite esters Chemical class 0.000 description 1
- 150000003014 phosphoric acid esters Chemical class 0.000 description 1
- CKRORYDHXIRZCH-UHFFFAOYSA-N phosphoric acid;dihydrate Chemical compound O.O.OP(O)(O)=O CKRORYDHXIRZCH-UHFFFAOYSA-N 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 229910052979 sodium sulfide Inorganic materials 0.000 description 1
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D11/00—Solvent extraction
- B01D11/04—Solvent extraction of solutions which are liquid
- B01D11/0488—Flow sheets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D36/00—Filter circuits or combinations of filters with other separating devices
- B01D36/04—Combinations of filters with settling tanks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/02—Crystallisation from solutions
-
- 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
- C01B25/18—Phosphoric acid
- C01B25/234—Purification; Stabilisation; Concentration
-
- 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
- C01B25/18—Phosphoric acid
- C01B25/234—Purification; Stabilisation; Concentration
- C01B25/237—Selective elimination of impurities
- C01B25/2372—Anionic impurities, e.g. silica or boron compounds
-
- 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
- C01B25/18—Phosphoric acid
- C01B25/234—Purification; Stabilisation; Concentration
- C01B25/237—Selective elimination of impurities
- C01B25/238—Cationic impurities, e.g. arsenic compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D11/00—Solvent extraction
- B01D2011/002—Counter-current extraction
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
Abstract
The application provides a method for removing impurities by adopting double extraction physics and combining a suspension crystallization process technology to be applied to the field of wet phosphoric acid purification. The main steps are pre-extraction, namely, wet phosphoric acid is firstly subjected to removal of metal cations such as iron, magnesium, aluminum and the like by adopting a high-selectivity cation extractant. Concentrating the decationized acid. The obtained extracted acid is subjected to suspension crystallization, washing and dilution to obtain the high-purity food-grade phosphoric acid. The application adopts a wet process phosphoric acid purifying process route of double extraction and physical suspension crystallization impurity removal. The metal cations are removed in an extraction mode in the pretreatment, so that the method can be suitable for a high-impurity system of raw material acid, in particular to phosphoric acid of a high-aluminum high-magnesium system in a semi-water two-water wet phosphoric acid process. The post-purification can produce phosphoric acid with different quality according to the process requirement, meanwhile, the low-temperature crystallization process scheme can reduce the dependence on materials, and the requirements can be met by common domestic 316L or 2205.
Description
Technical Field
The application belongs to the technical field of wet phosphoric acid purification by a sulfuric acid method, and relates to a purification method for obtaining high-purity wet phosphoric acid.
Background
At present, the basic reserve of phosphorite in China is 32.4 hundred million tons, and it has been ascertained that phosphorite resources are distributed in 27 provinces (autonomous regions), but the distribution is centralized, and the distribution is mainly in five provinces of Hubei, sichuan, guizhou, yunnan and Hunan, the total reserve of phosphorite resources in five provinces exceeds 80%, but with the consumption of phosphorite resources, most of the phosphorite resources exhibit low grade characteristics, and the utilization of low grade phosphorite resources is greatly dependent on the technical level of wet phosphoric acid. The wet phosphoric acid has the characteristics of low-grade phosphorite utilization and low process energy consumption compared with the hot phosphoric acid, but has the inherent defects of high impurity content of phosphoric acid and high purification difficulty.
With the rise of new energy, the demand for high-purity phosphoric acid is increasing, so that the purification of phosphoric acid is particularly urgent. The phosphoric acid purifying method has a plurality of chemical precipitation, solvent extraction, crystallization, ion exchange and the like, and the solvent extraction is taken as a main flow process route in China at present, wherein the extraction process taking Vat Fu as a main flow process can continuously and industrially produce food grade phosphoric acid, and the Sichuan Dai and Hua Shi solvent extraction purifying processes meet the industrial phosphoric acid requirement.
Analysis of the wet phosphoric acid produced by collophanite in the Hubei area shows that the content of the iron-magnesium-aluminum sesquioxide in the acid is high, the MER value (the ratio of the sum of the percentage contents of the sesquioxide in the phosphoric acid to the percentage content of phosphorus pentoxide) is as high as 8 percent, and when dilute phosphoric acid is concentrated, the iron-magnesium-aluminum ion influence causes high acid viscosity, high energy consumption during concentration, difficult acid concentration and larger influence on the subsequent extraction efficiency improvement.
Disclosure of Invention
In order to solve the problems, the main purpose is to provide an extraction and suspension crystallization impurity removal technical route aiming at the defects existing in the prior extraction technology. Can effectively remove impurities under the condition of high impurity content of wet-process phosphoric acid to obtain high-purity wet-process purified phosphoric acid. The whole process has high extraction rate and low yield of raffinate acid, and is suitable for the new production technology of large-scale production.
The technical scheme comprises the following two procedures in series connection, and the technical method comprises the following steps:
1. and (3) a purification procedure:
(1) Step 1, pre-sedimentation: and (3) delivering the crude phosphoric acid into a settling tank, settling by adding a settling agent to obtain clear acid, overflowing the clear acid into a clear liquid tank, performing filter pressing solid-liquid separation on the lower silt acid, delivering the solid to a fertilizer workshop to produce fertilizer, and returning clear liquid to the clear liquid tank.
(2) Step 2, pre-extraction: and (3) sending the clear liquid obtained in the step (1) and the pre-extractant into an extraction tower, and carrying out extraction reaction in a countercurrent contact mode to obtain a light phase 1 and a heavy phase 1.
(3) Step 3, desolventizing: and (3) desolventizing the light phase 1 obtained in the step (2) to obtain cationic salt, and producing fertilizer or further purifying.
(4) Step 4, desolventizing: concentrating the heavy phase 1 obtained in the step 2 to obtain 61-65% concentrated phosphoric acid.
2. Post-purification procedure:
(1) Step 1, suspension crystallization: gradually cooling and crystallizing the concentrated phosphoric acid with 61-65% of phosphorus pentoxide content obtained in the step 4 in the purification procedure, wherein the crystallization level is 2-4, and obtaining high-purity phosphoric acid crystals and mother liquor.
(2) Step 2, centrifugal filtration washing: washing the phosphoric acid crystal obtained in the step 1 of the post-purification process by adopting dilute phosphoric acid (such as dilute phosphoric acid with the mass concentration of 10-15 percent), and centrifugally filtering to obtain the high-purity phosphoric acid crystal with the phosphorus pentoxide content of 70 percent or more.
(3) Step 3, dilution: and (3) diluting the high-purity phosphoric acid crystal with the phosphorus pentoxide content of 70% or more obtained in the step (2) of the post-purification working procedure by desalted water to obtain the phosphoric acid with the phosphorus pentoxide content of 55% or more, or diluting to obtain the phosphoric acid with the phosphorus pentoxide content of 61.5% or more.
(4) Step 4, mother liquor treatment: and (2) returning the phosphoric acid mother liquor obtained in the step (1) in the post-purification step, namely the filtrate obtained in the step (2), to an extraction step to participate in extraction, so as to realize serialization.
The application has the beneficial effects that
1. According to the process scheme, sulfate radicals are removed without adding ore pulp in pretreatment, the operation is convenient to manage on site, phosphogypsum is not generated, and the acid loss is low.
2. The process has high extraction rate and less byproduct raffinate.
3. The reaction process does not need to add sodium sulfide for dearsenification, sodium ions are not introduced, the on-site system scaling cleaning is effectively reduced, and meanwhile, the on-site safety risk is reduced.
4. The metal cations are removed in an extraction mode in the pretreatment, so that the method can be suitable for a high-impurity system of raw material acid, in particular to phosphoric acid of a high-aluminum high-magnesium system in a semi-water two-water wet phosphoric acid process.
5. The post-purification can produce phosphoric acid with different quality according to the process requirement, meanwhile, the low-temperature crystallization process scheme can reduce the dependence on materials, and the requirements can be met by common domestic 316L or 2205.
6. After a large amount of metal cations are removed in the pre-extraction process, the viscosity of the acid is reduced, the steam consumption can be saved when the concentration of phosphoric acid is improved, and meanwhile, the removal of fluorine is facilitated due to the improvement of the acid concentration.
Drawings
FIG. 1 is a process flow diagram of an embodiment of the present application.
Detailed Description
The wet phosphoric acid purifying process includes extracting coarse phosphoric acid, suspension crystallizing to obtain purified phosphoric acid, and the specific technological process includes the following steps:
(1) In a closed environment, contacting and extracting crude phosphoric acid with an extracting agent to obtain purified phosphoric acid;
(2) Pulping the purified phosphoric acid at a temperature rise, and introducing the purified phosphoric acid into a suspension crystallizer for suspension crystallization to obtain slurry;
(3) Carrying out solid-liquid separation on the slurry obtained in the step (2) to obtain phosphoric acid crystals;
(4) And (3) washing and melting the phosphoric acid crystals obtained in the step (3) by using a washing liquid, and cooling to obtain a purified phosphoric acid product.
Extracting clear liquid obtained after the crude phosphoric acid is settled by a settling agent (polyacrylamide);
the closed environment is used for increasing the site safety risk and the solvent consumption while minimizing the exposure of the solvent to the air.
And recycling filtrate of the mixture formed after sedimentation after filtration into clear liquid to participate in extraction, and outputting the solid as phosphate.
The crude phosphoric acid in the step (1) is clear acid obtained by settling the crude phosphoric acid with the mass concentration of 30-50%. The clear liquid has a mass concentration of 30-50%, more preferably 35-50%, and more preferably 46-50%, and the wet phosphoric acid concentration is P 2 O 5 Comprises metal cation impurities of sesquioxide which are difficult to remove, wherein the metal cation impurities comprise 0.4-0.8 percent of ferric oxide, 1.5-3.5 percent of magnesium oxide, 1.5-3.5 percent of aluminum oxide, 0.7-1.1 percent of fluoride ion, 0.2-0.4 percent of chlorine and SO 4 2- 3.0-6.0％。
The content of the metal cations which are difficult to remove in the process directly leads to the quality of the wet-process phosphoric acid to be an unqualified product in the food field and the industrial field. The content of the metal cations in the phosphoric acid which is difficult to remove causes the viscosity of the phosphoric acid to be pure within a certain range (15-25 m.pas), and the viscosity can be continuously increased or has certain fluctuation with the prolonged storage time, but the viscosity is not reduced. What is more troublesome to those skilled in the art is that the presence of this viscosity significantly increases the steam usage of the phosphoric acid concentration process. For example, from a wet phosphoric acid concentration of 46-50% and a sesquioxide content of less than 1.0%, a steam amount of 0.40-0.50t/m is required per volume of dilute acid concentration when concentrating to 58-62% 3 (steam consumption); whereas the amount of steam required for concentration per volume of dilute acid is 0.53-0.63t/m at a sesquioxide content of more than 2.0% and less than 4.0% 3 The method comprises the steps of carrying out a first treatment on the surface of the And the steam amount required for concentration per volume of dilute acid is 0.55-0.75t/m when the sesquioxide content is more than 4.0% and less than 6.0% 3 . The sesquioxide comprises the technology in the fieldThe most basic detection indexes of operators are ferric oxide, magnesium oxide and aluminum oxide. Those skilled in the art generally take these three together as influencing factors that influence the properties of the product.
It is further unacceptable to those skilled in the art that the presence of this viscosity also results in the appearance of fluorine content during the phosphoric acid concentration process. This is because the wet process phosphoric acid contains a certain amount of fluorine content, and fluorine-containing precipitates formed during the concentration process further affect the quality of the wet process phosphoric acid.
The extractant comprises any one or more of phosphate, phosphite and substituted phosphate, and the substituent comprises any one of halogen substitution, amino, carboxyl, sulfhydryl and hydroxyl.
The pre-extractant is selected from any one of bis (2, 2-trifluoroethyl) phosphite, tris (2, 2-trifluoroethyl) phosphite, triisopropyl phosphite, tristearyl phosphite, trimethylolpropane phosphite, tris (nonylphenyl) phosphite and tris (2, 4-di-tert-butylphenyl) phosphite;
or any one selected from 4-chlorophenyl dichlorophosphate, phenyl tetramethylene hexafluorophosphate, mono [2- (perfluorooctyl) ethyl ] phosphate, O-tolyl chlorophosphate, dehydrated- (O-carboxyphenyl) chlorophosphate, tetramethyl fluorourea hexafluorophosphate, tris (tribromoneopentyl) phosphate, ethyl dichlorophosphate, 3-aminopropyl monophosphate, butyrate phosphate and dodecyl phosphate diethanolamine phosphate.
The phosphoric acid ester or phosphite ester or substituted phosphoric acid ester compound disclosed by the application does not influence the physicochemical property of phosphoric acid in the phosphoric acid contact process, does not cause pollution to the phosphoric acid environment, and is dissolved in the solvent of the application rapidly and with high selectivity because metal cations in phosphoric acid are stripped from the phosphoric acid environment in the solvent environment with excessive mass relative to phosphoric acid.
The pre-extractant of the application does not only comprise the solvent, as long as the phosphate, phosphite and substituted phosphate which can realize the pre-extraction effect of the application are all effective protection ranges of the application.
The extractant is diluted by a diluent to obtain a mixed solution with the mass concentration of 0.1-50wt%, or preferably diluted by the diluent to obtain a mixed solution with the mass concentration of 1-40wt%, or preferably diluted by the diluent to obtain a mixed solution with the mass concentration of 10-30 wt%.
The concentration of the solvent in the mixed solution relative to the diluent is that under the condition of the concentration range of the solvent (or the pre-extractant), the high-efficiency extraction can be realized, and the diluent mainly plays a role in dispersing the pre-extractant, and further realizes the dispersion of the solvent in the phosphoric acid environment, so that the high-efficiency extraction of phosphoric acid is realized.
The diluent is selected from any one or more of n-butanol, isoamyl alcohol, amyl alcohol, cyclohexanol, hexanol, heptanol, octanol and sulfonated kerosene.
In the extractant configured as above, the crude phosphoric acid is contacted and extracted with at least one solvent, and under the solvent condition, the compound containing the metal cation impurity in the phosphoric acid is subjected to rapid and high-selective separation under the phosphoric acid concentration condition and the solvent condition, so that the compound containing the metal cation impurity is removed. The high selectivity means that the selectivity to the solvent is 90% -100% under the phosphoric acid concentration condition and the solvent condition, and further, the selectivity to the solvent is 95% -100%. The rapid selectivity means 1 to 400s, further rapid selectivity means 1 to 300s selectivity means 1 to 120s, further rapid selectivity means 1 to 60s, further rapid selectivity means 1 to 45s, or preferably rapid selectivity means 1 to 30s, or preferably rapid selectivity means 1 to 20s.
The pre-extraction agent is diluted by a diluent to obtain a mixed solution with the volume concentration of 0.1-50wt%; it is further preferable that the solvent is diluted with a diluent to obtain a mixed solution with a mass concentration of 1-40 wt%; it is further preferred that the solvent is diluted with a diluent to obtain a mixed solution having a mass concentration of 3 to 30 wt%.
The process of diluting the pre-extracting agent by adopting the diluent is to add the pre-extracting agent into the diluent, and then mix and dissolve the pre-extracting agent for 1-60min at the rotating speed of 400-1000 r/min; it is further preferable that the rotation speed in the process of mixing is 500r/min-1000r/min, and the mixing time is 5-40min; it is further preferable that the rotational speed in the mixing process is 500r/min, 600r/min, 700r/min, 800r/min, 900r/min, or 1000r/min, and the overspeed mixing time is 5-30min.
The technical condition of high-speed mixing is adopted in the process of mixing the solvent and the diluent, which is one of key technical characteristics for realizing extraction efficiency. The inventors have found during the test that the phosphate or phosphite or halophosphite does indeed give a corresponding mixing in the diluent, but this mixing is only a static mixing, but after the high speed stirring according to the application the resulting mixture is found to be a mutual embedded mixing. The color developed was substantially cloudy or oil milky without stirring or at low speeds of 350r/min and below, whereas the resulting mixture was clear with the present application after the overdrive mixing. Thus, the novel mixed liquor formed by the application can realize higher efficiency of extracting phosphoric acid and separating metal ions.
In the extraction process in the step (1), countercurrent contact extraction is carried out on the crude phosphoric acid and at least one pre-extractant, wherein the mass ratio of the crude phosphoric acid to the at least one pre-extractant is 1:1-10; it is further preferred that the mass ratio of crude phosphoric acid to at least one pre-extractant is 1:1-6; it is further preferred that the mass ratio of crude phosphoric acid to at least one pre-extractant is 1:1-4. The amount of the solvent is slightly excessive compared with the amount of the wet-process phosphoric acid as much as possible, so that the effective contact degree of the wet-process phosphoric acid in the extractant is increased, and the extraction is facilitated to be complete. In the case of complete contact of the extractant with the wet phosphoric acid, a relatively low ratio of the two, for example 1:1, is also possible.
The extraction process of the application can realize the remarkable reduction of metal ions in one extraction, and realize the reduction of workload, and the extraction of the part which is not completely extracted can be performed again in the actual operation process. Meanwhile, the minimum amount of the extractant can realize the extraction with the wet phosphoric acid in the same mass ratio, and the extractant can be amplified to 2-3 times of the phosphoric acid for more sufficient extraction, but the actual effect is basically equivalent to the effect of the same mass.
The extraction reaction temperature of the crude phosphoric acid and at least one solvent in the extraction process is 20-60 ℃ and the pressure is 0.1-0.6MPa; it is further preferred that the countercurrent contact is carried out at a temperature of 30-50deg.C and a pressure of 0.1-0.6MPa for the extraction reaction of the crude phosphoric acid with at least one solvent; it is further preferred that the countercurrent contact is carried out at a temperature of 30 to 45℃and a pressure of 0.1 to 0.6MPa for the extraction reaction of the crude phosphoric acid with at least one solvent.
The extraction reaction temperature is in the range of 20-60 ℃, more preferably 20-50 ℃, still more preferably 30-45 ℃ before or during the contact extraction of the crude phosphoric acid and the extractant. The prior method is that the crude phosphoric acid and the extractant are preheated to the corresponding temperature and then are subjected to contact extraction. Among them, crude phosphoric acid and an extractant are subjected to contact extraction at a preset extraction ambient temperature of 20 to 60 ℃, more preferably 20 to 50 ℃, still more preferably 30 to 45 ℃.
Under the extraction conditions, the crude phosphoric acid and the extractant are in an atomized state in the countercurrent contact extraction process. The emulsification dispersion adopts any one of pipeline dispersion, emulsification pump dispersion and turntable tower dispersion. The particle size of the atomized state formed in the dispersion of the fine particles is 10 μm to 500. Mu.m. Further preferably 50 μm to 350. Mu.m. Still more preferably 100 μm to 200. Mu.m.
The particle size of the particles is 10 μm to 500 μm, or 50 μm to 350 μm, or 100 μm to 200 μm, respectively, and does not refer to the particle size in a solid state, but refers to particles formed after pipe dispersion, emulsification pump dispersion, or turntable column dispersion, which are formed like water droplets due to the structure of the apparatus and the operation thereof, such as the pore size of the apparatus during dispersion, and/or due to rotation.
The degree of particulate dispersion of the at least one wet process phosphoric acid and the at least one solvent may be the same or different. The use of a particulate dispersion scheme and varying degrees of dispersion does increase the specific surface area of the contacting process.
The contact extraction reaction process is continuous, namely, at least one wet phosphoric acid and at least one solvent are converted into flow relation continuity in a mass relation and enter an extraction environment, the phenomenon of light phase-heavy phase (oil phase-water phase) is realized after the contact extraction reaction is carried out in the environment, the extraction process is further completed, and the next process of realizing products and post-treatment is carried out.
In the technical scheme of the application, the volume fraction of the light phase no-load solvent purifying extractant is 1-100%, preferably the volume fraction of the no-load solvent in the purifying extractant is 5-95%, and more preferably the volume fraction of the no-load solvent in the purifying extractant is 10-90%. In some embodiments, the empty solvent comprises 70-99%, more preferably 70-90%, even more preferably 80-90% by volume of the clean-up extractant for cost savings.
In order to save the enterprise cost, the light-phase no-load solvent realizes continuous operation, and the unavoidable no-load solvent can cause the problems of damage, impurity pollution and the like in the operation process. In order to realize the stability and the circulating effectiveness of the phosphoric acid index obtained by extraction, part of fresh extractant is supplemented in the circulating process of the no-load solvent, the formula proportion of the fresh extractant and the extractant in the raw materials is supplemented within 1-30% (volume fraction), and synchronous regeneration is carried out to remove impurities. Such as SO in the phosphoric acid index obtained by extraction 4 2- When the ion content exceeds 50ppm, SO is more preferable 4 2- When the ion content exceeds 35ppm, SO is more preferable 4 2- When the ion content exceeds 15ppm, fresh extractant is added during the circulation of the empty solvent.
Concentrating the heavy phase generated after extraction to obtain cation-removed phosphoric acid with the mass fraction of 53-55%; removing cations such as calcium, magnesium and aluminum by adding 30% of dilute sulfuric acid by mass fraction, adding 10% of oxalic acid to remove impurity cationic iron to obtain an empty pre-extractant, and adding 1-30% of fresh pre-extractant by volume fraction into the obtained pre-extractant for continuous pre-extraction; the separated cation salt is used for producing fertilizer additives.
And (3) concentrating in the step (2) to obtain the cation-removed phosphoric acid with the mass fraction of 61-65%, cooling to 10-20 ℃ and pulping, and stirring at 10-50r/min in the pulping process.
In the step (3), the pulpified phosphoric acid is cooled to 25-30 ℃ and then is introduced into a suspension crystallizer, the suspension crystallization process is cooled to 10-20 ℃ by adopting a gradient, the stirring speed in the suspension crystallization process is 10-100r/min, more preferably 10-50r/min, the gradient cooling stage number is 2-4, and the gradient cooling stage number is equal gradient and/or non-equal gradient cooling.
In the application, after the pulping process, the obtained high-purity phosphoric acid is subjected to gradient or non-gradient cooling in a suspension crystallizer under the stirring condition, phosphoric acid crystal particles are suspended in the mother liquor and slowly grow in the mother liquor, and lamellar and blocky phosphoric acid crystal blocks are not formed under the stirring condition as in a static crystallization mode, but a large amount of fine crystal slurry is formed in the suspension mother liquor. During the gradual decrease in temperature, the crystals in the suspension slowly stabilize and form dense crystalline particles, removing impurity components.
In the application, high-concentration, namely 53-65% of phosphoric acid with cations removed is adopted for heating and slurrying, and supersaturated solution of liquid phase is easier to form in the solution in the step (1), thereby being beneficial to realizing crystallization in a suspension crystallizer after slurrying.
The suspension crystallization equipment comprises a stirring and solid-liquid separation device, and the product from the suspension crystallization equipment is directly subjected to solid-liquid separation to separate the obtained fine crystal product from mother liquor.
The gradient cooling stage number is 2, the temperature of the pulpified phosphoric acid is reduced to 25 ℃ and then reduced to (10-15) +/-0.5 ℃ at 0.1-2.0 ℃/min, and the temperature is kept for 1-20min;
then cooling to (1-5) +/-0.5 ℃ at 0.1-2.0 ℃/min, and preserving heat for 1-10min.
The gradient cooling stage number is 3, the temperature of the pulpified phosphoric acid is reduced to 25 ℃ and then reduced to (15-20) +/-0.5 ℃ at 0.1-2.0 ℃/min, and the temperature is kept for 1-20min;
then cooling to (10-15) +/-0.5 ℃ at 0.1-2.0 ℃/min, and preserving heat for 1-20min;
then cooling to (1-5) +/-0.5 ℃ at 0.1-1.0 ℃/min, and preserving heat for 1-10min.
The gradient cooling stage number is 4, the temperature of the pulpified phosphoric acid is reduced to 25 ℃ and then reduced to (15-20) +/-0.5 ℃ at 0.1-2.0 ℃/min, and the temperature is kept for 1-20min;
then cooling to (10-15) +/-0.5 ℃ at 0.1-2.0 ℃/min, and preserving heat for 1-20min;
then cooling to (5-10) +/-0.5 ℃ at 0.1-1.0 ℃/min, and preserving heat for 1-20min;
then cooling to (1-5) +/-0.5 ℃ at 0.1-1.0 ℃/min, and preserving heat for 1-10min.
Gradually cooling down in a suspension crystallizer. The process of crystallization in a plurality of suspension crystallization devices means that the crystallization is carried out by cooling at a certain temperature in one device, then the crystallization is carried out by transferring the crystallization into another device and cooling the crystallization relative to the previous device, and the like.
In the experiments carried out, it was found that the finer grains formed were larger after the multistage crystallization process. If the gradient cooling stage number is 4, the granularity is 800-1250 μm; when the gradient cooling stage number is 3, the granularity is 500-850 μm; when the gradient cooling stage number is 2, the granularity is 350-550 μm. The larger the granularity is, the easier the solid-liquid separation is performed in the washing process, and the crystallization product is reduced to enter the phosphoric acid mother liquor.
And (3) recycling the phosphoric acid mother liquor obtained after the solid-liquid separation in the step (3) into clear liquid for extraction.
In the step (4), the obtained phosphoric acid crystal is washed by adopting pure phosphoric acid with the mass concentration of 10-15% as a washing liquid; the filtrate from the washing process is returned to step (1) for extraction.
And (4) heating and melting in a melting tank to 30-35 ℃ to obtain a purified phosphoric acid product.
By adopting the technical scheme of extraction and recrystallization, the viscosity of phosphoric acid is 5-10 m.pas, and Fe is realized 2 O 3 、MgO、Al 2 O 3 The content of Fe is less than 10ppm 2 O 3 、MgO、Al 2 O 3 The content of Fe is less than 5ppm 2 O 3 、MgO、Al 2 O 3 The content is less than 3ppm.
For a better understanding of the present application, the following examples are further illustrated by the following description of the present application, using wet process phosphoric acid dihydrate crude phosphoric acid as raw material phosphoric acid, the crude phosphoric acid index is shown in table 1, but the present application is not limited to the following examples.
TABLE 1 phosphoric acid parameter index
Example 1
The wet phosphoric acid purification process is carried out by adopting the process and the crude phosphoric acid with the number of 3, and the specific steps are as follows:
preparation of the pre-extractant: tristearyl phosphite was added to hexanol to prepare a mixed solution having a mass concentration of 16wt%, and the mixed solution was subjected to super-speed mixing at 600r/min for 11min to obtain an extraction solvent.
1. And (3) a purification procedure:
(1) Step 1, pre-sedimentation: and (3) conveying the crude phosphoric acid with the number of 3 into a settling tank, settling for 2 hours by adding a settling agent (polyacrylamide) to obtain clear acid, overflowing the clear acid into a clear liquid tank, performing filter pressing solid-liquid separation on the lower silt acid, conveying the solid to a fertilizer workshop to produce fertilizer, and returning clear liquid to the clear liquid tank.
(2) Step 2, pre-extraction: the temperature in the extraction tower is 40+/-5 ℃, the pressure in the extraction tower is 0.5-0.6MPa, the clear liquid obtained in the step 1 and the pre-extractant are respectively preheated to 40+/-5 ℃, then respectively enter the extraction tower from the upper part and the lower part of the extraction tower together for countercurrent contact extraction, a turntable tower is adopted for emulsification and dispersion in the extraction process, the volume ratio of wet phosphoric acid to the extraction solvent is 1:2.5, the contact extraction time is 5min, and the light phase 1 and the heavy phase 1 are collected after the extraction reaction is completed.
(3) Step 3, desolventizing: adding 30% of dilute sulfuric acid with the mass fraction of 30% into the light phase 1 obtained in the step 2 to remove cations such as calcium, magnesium and aluminum, adding 10% of oxalic acid to remove impurity cationic iron to obtain an empty pre-extractant, and adding 12% of fresh pre-extractant into the obtained pre-extractant for continuous pre-extraction; the separated cation salt is used for producing fertilizer additives.
(4) Step 4, desolventizing: concentrating the heavy phase 1 obtained in the step 2 to obtain 61-55% of concentrated phosphoric acid.
2. Post-purification procedure:
(1) Step 1, suspension crystallization: cooling the concentrated phosphoric acid with 61-65% of phosphorus pentoxide content obtained in the step 4 of the purification procedure to 30-35 ℃, and pulping and mixing uniformly under 150 r/min; cooling the pulpified phosphoric acid to 25-30 ℃, introducing the cooled phosphoric acid into a suspension crystallizer, and performing suspension crystallization at the stirring speed of 30r/min to obtain slurry, wherein the built-in material of the suspension crystallizer equipment is domestic 316L.
The gradient cooling stage number is 3, the temperature of the pulpified phosphoric acid is reduced to 25 ℃, then reduced to 15+/-0.5 ℃ at 0.5 ℃ per minute, and the temperature is kept for 10 minutes; then cooling to 10+/-0.5 ℃ at 0.3 ℃/min, and preserving heat for 10min; then cooling to 3+/-0.5 ℃ at 0.3 ℃/min, and preserving heat for 10min.
(2) Step 2, centrifugal filtration washing: carrying out solid-liquid separation on the slurry obtained in the step (1) to obtain phosphoric acid crystals and phosphoric acid mother liquor, washing the phosphoric acid crystals by adopting high-purity phosphoric acid with the mass fraction of 10%, wherein the high-purity phosphoric acid is phosphoric acid with the impurity content of less than 50ppb, obtaining high-purity phosphoric acid crystals with the content of 98-99% through centrifugal filtration, and returning filtrate in the washing process and filtered filtrate to the step (1) of the purification process to realize serialization; washing with washing liquid, heating to 30-35 deg.c in a melting tank for melting, and diluting to 60-85% concentration or direct extraction.
(3) Step 3, mother liquor treatment: and (3) sending the separated phosphoric acid mother liquor into a cyclone for fine crystal recovery, sending the recovered fine crystals into the step (1) of the purification procedure, and discharging the fine crystal mother liquor as waste liquid.
Example 2
The wet phosphoric acid purification process is carried out by adopting the process and the crude phosphoric acid with the number of 3, and the specific steps are as follows:
preparation of the pre-extractant: and adding the tetramethyl fluorourea hexafluorophosphate into n-butanol to prepare a mixed solution with the mass concentration of 13wt%, and performing overspeed mixing on the mixed solution at the rotating speed of 600r/min for 11min to obtain an extraction solvent.
1. And (3) a purification procedure:
(1) Step 1, pre-sedimentation: and (3) conveying the crude phosphoric acid with the number of 3 into a settling tank, settling for 2 hours by adding a settling agent (polyacrylamide) to obtain clear acid, overflowing the clear acid into a clear liquid tank, performing filter pressing solid-liquid separation on the lower silt acid, conveying the solid to a fertilizer workshop to produce fertilizer, and returning clear liquid to the clear liquid tank.
(2) Step 2, pre-extraction: the temperature in the extraction tower is 40+/-5 ℃, the pressure in the extraction tower is 0.5-0.6MPa, the clear liquid obtained in the step 1 and the pre-extractant are respectively preheated to 40+/-5 ℃, then respectively enter the extraction tower from the upper part and the lower part of the extraction tower together for countercurrent contact extraction, a turntable tower is adopted for emulsification and dispersion in the extraction process, the volume ratio of wet phosphoric acid to the extraction solvent is 1:2, the contact extraction time is 5min, and the light phase 1 and the heavy phase 1 are collected after the extraction reaction is completed.
(3) Step 3, desolventizing: adding 30% of dilute sulfuric acid with the mass fraction of 30% into the light phase 1 obtained in the step 2 to remove cations such as calcium, magnesium and aluminum, adding 10% of oxalic acid to remove impurity cationic iron to obtain an empty pre-extractant, and adding 6% of fresh pre-extractant into the obtained pre-extractant for continuous pre-extraction; the separated cation salt is used for producing fertilizer additives.
(4) Step 4, desolventizing: concentrating the heavy phase obtained in the step 2 to obtain 61-55% of concentrated phosphoric acid.
2. Post-purification procedure:
(1) Step 1, suspension crystallization: cooling the concentrated phosphoric acid with 61-65% of phosphorus pentoxide content obtained in the step 4 of the purification procedure to 30-35 ℃, and pulping and mixing uniformly under 150 r/min; cooling the pulpified phosphoric acid to 25-30 ℃, introducing the cooled phosphoric acid into a suspension crystallizer, and performing suspension crystallization at the stirring speed of 30r/min to obtain slurry, wherein the built-in material of the suspension crystallizer equipment is domestic 316L.
The gradient cooling stage number is 3, the temperature of the pulpified phosphoric acid is reduced to 25 ℃, then the temperature is reduced to 20+/-0.5 ℃ at 1.0 ℃/min, and the temperature is kept for 10min; then cooling to 10+/-0.5 ℃ at 1.0 ℃/min, and preserving heat for 10min; then cooling to 3+/-0.5 ℃ at 0.5 ℃/min, and preserving heat for 10min.
(2) Step 2, centrifugal filtration washing: carrying out solid-liquid separation on the slurry obtained in the step (1) to obtain phosphoric acid crystals and phosphoric acid mother liquor, washing the phosphoric acid crystals by adopting high-purity phosphoric acid with the mass fraction of 10%, wherein the high-purity phosphoric acid is phosphoric acid with the impurity content of less than 50ppb, obtaining high-purity phosphoric acid crystals with the content of 98-99% through centrifugal filtration, and returning filtrate in the washing process and filtered filtrate to the step (1) of the purification process; washing with washing liquid, heating to 30-35 deg.c in a melting tank for melting, and diluting to 60-85% concentration or direct extraction.
(3) Step 3, mother liquor treatment: and (3) sending the separated phosphoric acid mother liquor into a cyclone for fine crystal recovery, sending the recovered fine crystal into the step (1) of the purification procedure, and discharging the fine crystal mother liquor as waste liquid.
Example 3
The wet phosphoric acid purification process is carried out by adopting the process and the crude phosphoric acid with the number of 3, and the specific steps are as follows:
preparation of the pre-extractant: tris (2, 2-trifluoroethyl) phosphite is added into amyl alcohol to prepare a mixed solution with the mass concentration of 11.8wt%, and the mixed solution is subjected to overspeed mixing for 11min at the rotating speed of 600r/min to obtain an extraction solvent.
1. And (3) a purification procedure:
(1) Step 1, pre-sedimentation: and (3) conveying the crude phosphoric acid with the number of 1 into a settling tank, settling for 2 hours by adding a settling agent (polyacrylamide) to obtain clear acid, overflowing the clear acid into a clear liquid tank, performing filter pressing solid-liquid separation on the lower silt acid, conveying the solid to a fertilizer workshop to produce fertilizer, and returning clear liquid to the clear liquid tank.
(2) Step 2, pre-extraction: the temperature in the extraction tower is 40+/-5 ℃, the pressure in the extraction tower is 0.5-0.6MPa, the clear liquid obtained in the step 1 and the pre-extractant are respectively preheated to 40+/-5 ℃, then respectively enter the extraction tower from the upper part and the lower part of the extraction tower together for countercurrent contact extraction, a turntable tower is adopted for emulsification and dispersion in the extraction process, the volume ratio of wet phosphoric acid to the extraction solvent is 1:2.3, the contact extraction time is 5min, and the light phase 1 and the heavy phase 1 are collected after the extraction reaction is completed.
(3) Step 3, desolventizing: adding 30% of dilute sulfuric acid with the mass fraction of 30% into the light phase 1 obtained in the step 2 to remove cations such as calcium, magnesium and aluminum, adding 10% of oxalic acid to remove impurity cationic iron to obtain an empty pre-extractant, and adding 10% of fresh pre-extractant into the obtained pre-extractant for continuous pre-extraction; the separated cation salt is used for producing fertilizer additives.
(4) Step 4, desolventizing: concentrating the heavy phase obtained in the step 2 to obtain 61-55% of concentrated phosphoric acid.
2. Post-purification procedure:
(1) Step 1, suspension crystallization: cooling the concentrated phosphoric acid with 61-65% of phosphorus pentoxide content obtained in the step 4 of the purification procedure to 30-35 ℃, and pulping and mixing uniformly under 150 r/min; cooling the pulpified phosphoric acid to 25-30 ℃, introducing the cooled phosphoric acid into a suspension crystallizer, and performing suspension crystallization at the stirring speed of 30r/min to obtain slurry, wherein the built-in material of the suspension crystallizer equipment is domestic 316L.
The gradient cooling stage number is 3, the temperature of the pulpified phosphoric acid is reduced to 25 ℃, then the temperature is reduced to 20+/-0.5 ℃ at 1.0 ℃/min, and the temperature is kept for 8min; then cooling to 10+/-0.5 ℃ at a speed of 5.0 ℃/min, and preserving heat for 8min; then cooling to 3+/-0.5 ℃ at 0.5 ℃/min, and preserving heat for 8min.
(2) Step 2, centrifugal filtration washing: carrying out solid-liquid separation on the slurry obtained in the step (1) to obtain phosphoric acid crystals and phosphoric acid mother liquor, washing the phosphoric acid crystals by adopting high-purity phosphoric acid with the mass fraction of 10%, wherein the high-purity phosphoric acid is phosphoric acid with the impurity content of less than 50ppb, obtaining high-purity phosphoric acid crystals with the content of 98-99% through centrifugal filtration, and returning filtrate in the washing process and filtered filtrate to the step (1) of the purification process to realize serialization; washing with washing liquid, heating to 30-35 deg.c in a melting tank for melting, and diluting to 60-85% concentration or direct extraction.
(3) Step 3, mother liquor treatment: and (3) sending the separated phosphoric acid mother liquor into a cyclone for fine crystal recovery, sending the recovered fine crystals into the step (1) of the purification procedure, and discharging the fine crystal mother liquor as waste liquid.
Note that the yield of the present application refers to the product acid/feed phosphoric acid and is characterized by the efficiency of phosphoric acid purification.
Claims (19)
1. The wet phosphoric acid purifying process features that coarse phosphoric acid is extracted and suspension crystallized to obtain purified phosphoric acid, and the specific process includes the following steps:
(1) In a closed environment, contacting and extracting crude phosphoric acid with an extracting agent to obtain purified phosphoric acid;
(2) Pulping the purified phosphoric acid at a temperature rise, and introducing the purified phosphoric acid into a suspension crystallizer for suspension crystallization to obtain slurry;
(3) Carrying out solid-liquid separation on the slurry obtained in the step (2) to obtain phosphoric acid crystals;
(4) And (3) washing and melting the phosphoric acid crystals obtained in the step (3) by using a washing liquid, and cooling to obtain a purified phosphoric acid product.
2. The method for purifying wet process phosphoric acid according to claim 1, wherein the crude phosphoric acid in step (1) has a concentration of 30 to 50%, preferably 40 to 50%, preferably 46 to 50%, by P 2 O 5 Wherein the impurities include fluorine, chlorine, sulfate, iron, aluminum, sodium, calcium, magnesium, and arsenic, and the content of fluorine is 0.7-1.1%, chlorine is 0.2-0.4%, and SO 4 2- 3.0-6.0%、Fe 2 O 3 0.4-0.8%、Al 2 O 3 1.5-3.5%、NaO 0.3-0.4%、CaO 0.3-0.4%、MgO 1.5-3.5%、As 10-30ppm。
3. The wet process phosphoric acid purification process according to claim 2, wherein the clear solution obtained by settling the crude phosphoric acid in step (1) is extracted;
the filtrate of the mixture formed after sedimentation is recycled to the clear liquid to participate in extraction, and the solid is produced as phosphate;
the extractant comprises any one or more of phosphate, phosphite and substituted phosphate, and the substituent comprises any one of halogen substitution, amino, carboxyl, sulfhydryl and hydroxyl.
4. A wet process phosphoric acid purification process according to claim 3, wherein said pre-extractant is selected from the group consisting of any one of bis (2, 2-trifluoroethyl) phosphite, tris (2, 2-trifluoroethyl) phosphite, triisopropylphosphite, tristearylphosphite, trimethylolpropane phosphite, tris (nonylphenyl) phosphite, tris (2, 4-di-t-butylphenyl) phosphite;
or any one selected from 4-chlorophenyl dichlorophosphate, phenyl tetramethylene hexafluorophosphate, mono [2- (perfluorooctyl) ethyl ] phosphate, O-tolyl chlorophosphate, dehydrated- (O-carboxyphenyl) chlorophosphate, tetramethyl fluorourea hexafluorophosphate, tris (tribromoneopentyl) phosphate, ethyl dichlorophosphate, 3-aminopropyl monophosphate, butyrate phosphate and dodecyl phosphate diethanolamine phosphate.
5. The wet process phosphoric acid purification process according to claim 4, wherein the solvent is diluted with a diluent to obtain a mixed solution with a mass concentration of 0.1-50 wt%; it is further preferable that the solvent is diluted with a diluent to obtain a mixed solution with a mass concentration of 1-40 wt%; it is further preferred that the solvent is diluted with a diluent to obtain a mixed solution having a mass concentration of 3 to 30 wt%.
6. The process for extracting impurities from wet-process phosphoric acid according to claim 5, wherein the diluent is selected from any one or more of n-butanol, isoamyl alcohol, amyl alcohol, cyclohexanol, hexanol, heptanol, octanol, and sulfonated kerosene.
7. A wet process phosphoric acid purification method according to claim 6, wherein,
the process of diluting the pre-extracting agent by adopting the diluent is to add the pre-extracting agent into the diluent, and then mix and dissolve the pre-extracting agent for 1-60min at the rotating speed of 400-1000 r/min; it is further preferable that the rotation speed in the process of mixing is 500r/min-1000r/min, and the mixing time is 1-40min; it is further preferable that the rotational speed in the mixing process is 500r/min, 600r/min, 700r/min, 800r/min, 900r/min, or 1000r/min, and the overspeed mixing time is 5-30min.
8. The method for purifying phosphoric acid by wet process according to claim 7, wherein the phosphoric acid by wet process and the at least one pre-extractant are subjected to countercurrent contact extraction in the step (1), wherein the mass ratio of the phosphoric acid by wet process to the at least one pre-extractant is 1:1-10; it is further preferred that the mass ratio of wet phosphoric acid to at least one pre-extractant is 1:1-6; it is further preferred that the mass ratio of wet phosphoric acid to at least one pre-extractant is 1:1-4.
9. The method for purifying phosphoric acid by wet process according to claim 8, wherein the extraction reaction temperature of the crude phosphoric acid and the at least one solvent in the extraction process is 20 to 60 ℃ and the pressure is 0.1 to 0.6MPa;
it is further preferred that the countercurrent contact is carried out at a temperature of 20-50deg.C and a pressure of 0.1-0.6MPa for the extraction reaction of the crude phosphoric acid with at least one solvent;
it is further preferred that the countercurrent contact is carried out at a temperature of 30 to 45℃and a pressure of 0.1 to 0.6MPa for the extraction reaction of the crude phosphoric acid with at least one solvent.
10. The method for purifying wet-process phosphoric acid according to claim 9, wherein the heavy phase decationized phosphoric acid produced after the pre-extraction is concentrated to obtain decationized concentrated phosphoric acid with a mass fraction of 53-55%; and adding a stripping agent into the light phase to separate out metal cations, and obtaining an empty pre-extraction agent for recycling.
11. The method for purifying phosphoric acid by wet process according to claim 10, wherein the empty solvent accounts for 1 to 100% of the volume of the pre-extractant; in the preferred scheme, the back extraction liquid accounts for 5-95% of the volume of the pre-extractant; in the preferred scheme, the back extraction liquid accounts for 10-90% of the volume of the pre-extractant;
the phosphate mixture formed in the heavy phase after back extraction is used as fertilizer additive or separated and purified to obtain metal cation salt.
12. The wet process phosphoric acid purification method according to claim 11, wherein the concentration in the step (2) is carried out to obtain 53-55% by mass of the cation-removed phosphoric acid, the temperature is reduced to 30-35 ℃ for pulping, and stirring is carried out at 10-100r/min, preferably 10-50r/min during the pulping.
13. The wet process phosphoric acid purification method according to claim 12, wherein in the step (3), the pulpified phosphoric acid is cooled to 25-30 ℃ and then is introduced into a suspension crystallizer, the suspension crystallization process is cooled to 10-20 ℃ by adopting a gradient, the stirring speed in the suspension crystallization process is 10-50r/min, the gradient cooling stage number is 2-4, and the gradient cooling is equal gradient and/or non-equal gradient cooling.
14. The method for purifying phosphoric acid by wet process according to claim 13, wherein the gradient cooling stage number is 2, the slurried phosphoric acid is cooled to 25 ℃ and then cooled to (10-15) ± 0.5 ℃ at 0.1-2.0 ℃/min, and the temperature is kept for 1-20min;
then cooling to (1-5) +/-0.5 ℃ at 0.1-2.0 ℃/min, and preserving heat for 1-10min.
15. The method for purifying phosphoric acid by wet process according to claim 13, wherein the gradient cooling stage number is 3, the slurried phosphoric acid is cooled to 25 ℃ and then cooled to (15-20) ± 0.5 ℃ at 0.1-2.0 ℃/min, and the temperature is kept for 1-20min;
then cooling to (10-15) +/-0.5 ℃ at 0.1-2.0 ℃/min, and preserving heat for 1-20min;
then cooling to (1-5) +/-0.5 ℃ at 0.1-1.0 ℃/min, and preserving heat for 1-10min.
16. The method for purifying wet process phosphoric acid according to claim 13, wherein the gradient cooling stage number is 4, the slurried phosphoric acid is cooled to 25 ℃ and then cooled to (15-20) ± 0.5 ℃ at 0.1-2.0 ℃/min, and the temperature is kept for 1-20min;
then cooling to (10-15) +/-0.5 ℃ at 0.1-2.0 ℃/min, and preserving heat for 1-20min;
then cooling to (5-10) +/-0.5 ℃ at 0.1-1.0 ℃/min, and preserving heat for 1-20min;
then cooling to (1-5) +/-0.5 ℃ at 0.1-1.0 ℃/min, and preserving heat for 1-10min.
17. The method for purifying phosphoric acid by wet process according to claim 16, wherein the phosphoric acid mother liquor obtained after the solid-liquid separation in the step (3) is recycled to the clear liquid for extraction.
18. The method for purifying phosphoric acid by wet process according to claim 17, wherein the phosphoric acid crystals obtained in the step (4) are washed with 10 to 15% by mass of pure phosphoric acid as a washing liquid; the filtrate from the washing process is returned to step (1) for extraction.
19. The method for purifying phosphoric acid by wet process according to claim 1, wherein in the step (4), the purified phosphoric acid product is obtained by heating and melting in a melting tank at a temperature of 30 to 35 ℃.
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