CN115124165B - Comprehensive utilization method of oxalic acid wastewater - Google Patents
Comprehensive utilization method of oxalic acid wastewater Download PDFInfo
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- CN115124165B CN115124165B CN202210772132.0A CN202210772132A CN115124165B CN 115124165 B CN115124165 B CN 115124165B CN 202210772132 A CN202210772132 A CN 202210772132A CN 115124165 B CN115124165 B CN 115124165B
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- China
- Prior art keywords
- oxalic acid
- iron
- filtrate
- acid wastewater
- value
- Prior art date
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- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 title claims abstract description 593
- 235000006408 oxalic acid Nutrition 0.000 title claims abstract description 208
- 239000002351 wastewater Substances 0.000 title claims abstract description 175
- 238000000034 method Methods 0.000 title claims abstract description 101
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 266
- 229910052742 iron Inorganic materials 0.000 claims abstract description 118
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 70
- 150000003839 salts Chemical class 0.000 claims abstract description 37
- 239000003513 alkali Substances 0.000 claims abstract description 25
- 238000001704 evaporation Methods 0.000 claims abstract description 21
- 238000009854 hydrometallurgy Methods 0.000 claims abstract description 9
- 239000000706 filtrate Substances 0.000 claims description 129
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 57
- 238000006243 chemical reaction Methods 0.000 claims description 56
- 238000001914 filtration Methods 0.000 claims description 48
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 claims description 47
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 41
- 229940062993 ferrous oxalate Drugs 0.000 claims description 38
- OWZIYWAUNZMLRT-UHFFFAOYSA-L iron(2+);oxalate Chemical compound [Fe+2].[O-]C(=O)C([O-])=O OWZIYWAUNZMLRT-UHFFFAOYSA-L 0.000 claims description 38
- 239000002699 waste material Substances 0.000 claims description 38
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 33
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 31
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 31
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 31
- 150000002910 rare earth metals Chemical class 0.000 claims description 31
- 239000002893 slag Substances 0.000 claims description 30
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 27
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 27
- 239000011259 mixed solution Substances 0.000 claims description 26
- 239000000243 solution Substances 0.000 claims description 25
- 239000007788 liquid Substances 0.000 claims description 23
- 238000004064 recycling Methods 0.000 claims description 21
- 239000002253 acid Substances 0.000 claims description 18
- 229910001172 neodymium magnet Inorganic materials 0.000 claims description 17
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 16
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 claims description 14
- 229910001447 ferric ion Inorganic materials 0.000 claims description 14
- 239000012535 impurity Substances 0.000 claims description 13
- 229910052751 metal Inorganic materials 0.000 claims description 11
- 239000002184 metal Substances 0.000 claims description 11
- 238000001556 precipitation Methods 0.000 claims description 11
- 238000001035 drying Methods 0.000 claims description 10
- 230000001105 regulatory effect Effects 0.000 claims description 10
- 238000003916 acid precipitation Methods 0.000 claims description 7
- 230000001276 controlling effect Effects 0.000 claims description 7
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims description 7
- 238000012545 processing Methods 0.000 claims description 6
- 239000002585 base Substances 0.000 claims description 5
- 229960004887 ferric hydroxide Drugs 0.000 claims description 5
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 claims description 5
- 238000000926 separation method Methods 0.000 claims description 5
- MULYSYXKGICWJF-UHFFFAOYSA-L cobalt(2+);oxalate Chemical compound [Co+2].[O-]C(=O)C([O-])=O MULYSYXKGICWJF-UHFFFAOYSA-L 0.000 claims description 4
- 229960002089 ferrous chloride Drugs 0.000 claims description 4
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 229910017052 cobalt Inorganic materials 0.000 claims description 3
- 239000010941 cobalt Substances 0.000 claims description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 3
- 239000003814 drug Substances 0.000 claims description 3
- 238000004043 dyeing Methods 0.000 claims description 3
- 239000011790 ferrous sulphate Substances 0.000 claims description 3
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 3
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 3
- 238000009856 non-ferrous metallurgy Methods 0.000 claims description 3
- 229920003023 plastic Polymers 0.000 claims description 3
- 239000004033 plastic Substances 0.000 claims description 3
- UMPKMCDVBZFQOK-UHFFFAOYSA-N potassium;iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[K+].[Fe+3] UMPKMCDVBZFQOK-UHFFFAOYSA-N 0.000 claims description 3
- 238000007639 printing Methods 0.000 claims description 3
- 230000035484 reaction time Effects 0.000 claims description 3
- 229910000640 Fe alloy Inorganic materials 0.000 claims description 2
- 229910001021 Ferroalloy Inorganic materials 0.000 claims description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 2
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 2
- 239000010842 industrial wastewater Substances 0.000 claims description 2
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 2
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims description 2
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 claims description 2
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 2
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 claims description 2
- 150000002739 metals Chemical class 0.000 claims description 2
- 239000013049 sediment Substances 0.000 claims description 2
- 239000011734 sodium Substances 0.000 claims description 2
- 229910052708 sodium Inorganic materials 0.000 claims description 2
- 239000012670 alkaline solution Substances 0.000 claims 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims 1
- 230000008020 evaporation Effects 0.000 abstract description 15
- 230000009286 beneficial effect Effects 0.000 abstract description 10
- 238000011161 development Methods 0.000 abstract description 7
- 210000001503 joint Anatomy 0.000 abstract description 6
- 238000006386 neutralization reaction Methods 0.000 description 25
- 239000006227 byproduct Substances 0.000 description 23
- 230000008901 benefit Effects 0.000 description 19
- 239000004571 lime Substances 0.000 description 19
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 18
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 18
- 235000011941 Tilia x europaea Nutrition 0.000 description 18
- 239000002244 precipitate Substances 0.000 description 17
- 235000011121 sodium hydroxide Nutrition 0.000 description 15
- 239000002994 raw material Substances 0.000 description 13
- 230000000694 effects Effects 0.000 description 12
- -1 rare earth metal ions Chemical class 0.000 description 12
- 239000000203 mixture Substances 0.000 description 11
- 238000000605 extraction Methods 0.000 description 9
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 8
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 8
- 239000001110 calcium chloride Substances 0.000 description 8
- 229910001628 calcium chloride Inorganic materials 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 230000019771 cognition Effects 0.000 description 7
- 238000006303 photolysis reaction Methods 0.000 description 7
- 238000005265 energy consumption Methods 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- 229910000859 α-Fe Inorganic materials 0.000 description 6
- SKEUTFNJHQAPGY-UHFFFAOYSA-N iron;oxalic acid Chemical compound [Fe].OC(=O)C(O)=O SKEUTFNJHQAPGY-UHFFFAOYSA-N 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 238000007405 data analysis Methods 0.000 description 4
- ZDYUUBIMAGBMPY-UHFFFAOYSA-N oxalic acid;hydrate Chemical compound O.OC(=O)C(O)=O ZDYUUBIMAGBMPY-UHFFFAOYSA-N 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 235000011118 potassium hydroxide Nutrition 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 3
- 235000019270 ammonium chloride Nutrition 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 238000005286 illumination Methods 0.000 description 3
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000004065 wastewater treatment Methods 0.000 description 3
- BZSXEZOLBIJVQK-UHFFFAOYSA-N 2-methylsulfonylbenzoic acid Chemical compound CS(=O)(=O)C1=CC=CC=C1C(O)=O BZSXEZOLBIJVQK-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000002306 biochemical method Methods 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- VEPSWGHMGZQCIN-UHFFFAOYSA-H ferric oxalate Chemical compound [Fe+3].[Fe+3].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O VEPSWGHMGZQCIN-UHFFFAOYSA-H 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 2
- NQXWGWZJXJUMQB-UHFFFAOYSA-K iron trichloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].Cl[Fe+]Cl NQXWGWZJXJUMQB-UHFFFAOYSA-K 0.000 description 2
- FLTRNWIFKITPIO-UHFFFAOYSA-N iron;trihydrate Chemical compound O.O.O.[Fe] FLTRNWIFKITPIO-UHFFFAOYSA-N 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000010979 pH adjustment Methods 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 244000025254 Cannabis sativa Species 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 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
- 238000009835 boiling Methods 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 229940032296 ferric chloride Drugs 0.000 description 1
- 229940044631 ferric chloride hexahydrate Drugs 0.000 description 1
- 229960005191 ferric oxide Drugs 0.000 description 1
- 229940032950 ferric sulfate Drugs 0.000 description 1
- 229910001448 ferrous ion Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- TUJKJAMUKRIRHC-UHFFFAOYSA-N hydroxyl Chemical compound [OH] TUJKJAMUKRIRHC-UHFFFAOYSA-N 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 235000012204 lemonade/lime carbonate Nutrition 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012074 organic phase Substances 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B3/00—General features in the manufacture of pig-iron
- C21B3/04—Recovery of by-products, e.g. slag
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B23/00—Obtaining nickel or cobalt
- C22B23/04—Obtaining nickel or cobalt by wet processes
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B59/00—Obtaining rare earth metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/006—Wet processes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
- C02F1/32—Treatment of water, waste water, or sewage by irradiation with ultraviolet light
- C02F1/325—Irradiation devices or lamp constructions
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/70—Treatment of water, waste water, or sewage by reduction
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/70—Treatment of water, waste water, or sewage by reduction
- C02F1/705—Reduction by metals
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/722—Oxidation by peroxides
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/16—Nature of the water, waste water, sewage or sludge to be treated from metallurgical processes, i.e. from the production, refining or treatment of metals, e.g. galvanic wastes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/02—Specific form of oxidant
- C02F2305/026—Fenton's reagent
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Abstract
The invention discloses a comprehensive utilization method of oxalic acid wastewater, which comprises the following steps: (1) adding iron into oxalic acid wastewater; the molar ratio of the added iron to oxalic acid is n (Fe), n (Ox) is less than or equal to 4:3; (2) adding alkali into the oxalic acid wastewater to adjust the pH value to be within a range of 1.0-8.0; finally, the reuse water is obtained. The invention can obviously reduce the discharge of subsequent salt, is beneficial to realizing green circular economy and has obvious social value. The COD in the reuse water treated by the method can be reduced to 100mg/L, and the salt can be recovered by subsequent seamless butt joint evaporation. The invention provides a new solution for green development and comprehensive utilization of wastewater in hydrometallurgy industry, and has remarkable popularization value.
Description
Technical Field
The invention relates to a comprehensive utilization method of oxalic acid wastewater, in particular to a treatment method of oxalic acid wastewater generated by precipitation of rare earth metal ions by oxalic acid. Belongs to the technical field of comprehensive recovery of resources and wastewater treatment.
Background
Oxalic acid, the name oxalic acid, is the simplest dibasic acid, is an anhydrous transparent crystal or powder, and is tasty acid, easily soluble in ethanol and water, and insoluble in benzene. Oxalic acid and its salts are widely used in nonferrous metallurgy, metal processing, medicine, printing and dyeing, plastics and other industries. Along with the rapid development of the industry in China, the yield and the consumption of oxalic acid are continuously increased. The hydrometallurgical industry generates a great amount of wastewater containing oxalic acid (and/or oxalic acid radical) (hereinafter referred to as oxalic acid wastewater) to be treated each year, and if the wastewater is improperly treated, serious environmental pollution is caused, and valuable resources are seriously wasted.
Comprehensive utilization of oxalic acid wastewater is a problem to be solved in the industry, and many professional technicians have conducted intensive researches on the comprehensive utilization of oxalic acid wastewater. Mainly comprises lime neutralization method, evaporation method and extraction method.
The lime neutralization method has simple operation and low cost, neutralizes acid in the wastewater to ensure that the wastewater reaches the discharge standard, but a large amount of waste residues generated by the method also pollute the environment and are difficult to treat; if rare earth is recovered from the waste residue, the recovery process is redundant, the energy consumption is high, and a large amount of chemical raw materials are required to be consumed again; the acid in the wastewater is not effectively recovered, so that resource waste is caused.
Lime neutralization is a widely used method for treating oxalic acid wastewater in practice by adding lime or calcium carbonate (CN 101979336a, etc.) to the wastewater. The method is simple and convenient to operate and low in cost, but generates a large amount of high-salt wastewater containing Ca 2+ and other impurities, and also generates a large amount of neutralization waste residues which need to be additionally treated, so that the treatment cost is increased, and various valuable resources are not fully utilized.
The evaporation method (see CN101935762A, etc.) is to utilize the difference of boiling points of hydrochloric acid and oxalic acid, and control the temperature of the evaporator to make the hydrochloric acid and water form azeotrope to evaporate, thereby realizing the recovery of hydrochloric acid and oxalic acid in oxalic acid wastewater. The method can recover oxalic acid, hydrochloric acid and nonferrous metals to a certain extent, and realizes better economic and social benefits while comprehensively utilizing wastes. However, the method is not easy to industrialize, has large energy consumption, large equipment corrosion, high cost and difficult production control.
The extraction method is to separate oxalic acid and hydrochloric acid by using a proper extractant, thereby realizing the comprehensive utilization of waste. The Chinese patent application with publication number of CN105624403A discloses a technical scheme of extracting oxalic acid in waste acid, precipitating oxalic acid in a back-extracted organic phase by adopting a metal salt solution, fully recycling oxalic acid in the waste acid, recycling all useful components such as acid, metal oxalate, water and the like, and recycling all oxalic acid, hydrochloric acid and water to achieve the effect of zero emission of wastewater treatment. However, the extractant such as TOPO and P350 used in the method has high price, high production cost, unstable process and some environmental protection problems such as higher COD.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a comprehensive utilization method of oxalic acid wastewater, which comprises the following steps:
(1) Adding iron into oxalic acid wastewater; adding iron and oxalic acid (oxalic acid root is calculated by oxalic acid, and the following is the same) in a molar ratio of n (Fe) to n (H 2C2O4) is less than or equal to 4:3;
(2) Adding alkali into the oxalic acid wastewater to adjust the pH value to be within a range of 1.0-8.0; the method can also comprise the steps of solid-liquid separation after the step (2), wherein the solid-liquid separation mode can be one or more of filtration, centrifugation, sedimentation and supernatant taking;
finally, the reuse water is obtained.
Preferably, the iron added in step (1) may be in the form of one or more of zero valent iron, ferrous iron, ferric iron, and ferric iron.
The zero-valent iron comprises one or more of elemental iron and ferroalloy; the ferrous iron comprises one or more of oxide, alkali, salt and complex; ferric iron comprises one or more of oxides, bases, salts, complexes; the high iron comprises one or more of oxide, salt and acid.
Preferably, the ferrous iron can be one or more of ferrous oxide, ferrous hydroxide, ferrous chloride, and ferrous sulfate.
Preferably, the ferric iron may be one or more of ferric hydroxide, ferric oxide, ferric chloride, ferric sulfate.
Preferably, the high iron may be one or more of sodium ferrate and potassium ferrate.
Preferably, in the step (1), the molar ratio of iron to oxalic acid is 0.5.ltoreq.n (Fe): n (H 2C2O4). Ltoreq.1.
Preferably, if the iron in the step (1) is ferric iron or high iron, the adding mode should be divided into two times: initial addition and subsequent addition.
Preferably, in the step (1), the initial molar amount of iron is less than 1/3 of the molar amount of oxalic acid, and the subsequent addition can be one or more of dropwise addition and batch addition.
Preferably, the pH of step (2) is in the range of 4-6. In another preferred embodiment, the pH of step (2) is in the range of 1.5 to 6.5.
The alkali in the step (2) can be one or more of sodium hydroxide, ammonia water and potassium hydroxide.
Preferably, the alkali is sodium hydroxide, ammonia water or potassium hydroxide solution, and the concentration range is as follows: not less than 10mol/L.
In the present invention, steps (1) to (2) may be repeated after the ferrous oxalate precipitate is filtered out, and/or Fenton may be followed.
Preferably, in the step (2), when the concentration of oxalic acid radical in oxalic acid wastewater is reduced to about 5mmol/L, filtering and collecting precipitate.
Preferably, the concentration of residual oxalic acid in the reuse water is less than or equal to 6.25mmol/L. More preferably, the concentration of residual oxalic acid in the recycled water is less than or equal to 2.33mmol/L.
And (3) subsequent Fenton grafting can be carried out to ensure that the concentration of residual oxalic acid is less than or equal to 0.67mmol/L.
According to the method disclosed by the invention, the oxalic acid wastewater after being treated can be used as Fenton-like raw materials.
When the iron source is one or more of ferric iron and high iron, the method further comprises the step (3): and (3) irradiating the mixed solution with visible light or ultraviolet light. The illumination source may be sunlight. Preferably visible light with a wavelength of less than 570nm, more preferably ultraviolet light.
Preferably, the oxalic acid wastewater of the invention is wastewater produced in nonferrous metallurgy, metal processing, medicine, printing and dyeing and plastic industries. The iron is iron slag obtained after recycling rare earth from neodymium iron boron waste.
Still preferably, the oxalic acid wastewater is industrial wastewater in hydrometallurgy and metal processing industries.
More preferably, the oxalic acid wastewater is rare earth and cobalt nonferrous metal production wastewater.
A preferable technical scheme of the invention is as follows:
step (1): dissolving neodymium iron boron waste materials with oxalic acid precipitation rare earth waste water to recover iron slag after rare earth;
Step (2): adding ammonia water into oxalic acid precipitation rare earth wastewater to adjust the pH value, and filtering to obtain filtrate I;
step (3): slowly dropwise adding the ferric ion solution in the step (1) into the filtrate I in the sun, and controlling the pH value by using ammonia water in the process; filtering to obtain filter residue I and filtrate II;
Step (4): and regulating the pH value of the filtrate II after Fenton, filtering to obtain filter residue II and filtrate III, wherein the filter residue II can be used as an iron source for recycling, and the filtrate III reaches the emission standard.
Wherein, in the step (2), the concentration of ammonia water is 28 weight percent, and the pH is adjusted to 5; in the step (3), ammonia water is used for controlling the pH value to be stabilized between 4 and 6; in the process, the mixed solution turns green and then yellow, and bubbles and precipitation are generated; drying the obtained filter residue I to obtain ferrous oxalate with the purity of 96.95%; in the step (4), the pH value of the filtrate II is regulated to be 6.5 after Fenton, filter residues II and filtrate III are obtained through filtration, and in the Fenton reaction, the pH value is regulated to be 5, the concentration of hydrogen peroxide is 30%, and the reaction time is 2 hours.
Another embodiment of the invention is:
step (1): iron-precipitating post-liquid for recycling waste water; adding 10mol/L sodium hydroxide into the oxalic acid wastewater, adjusting the pH to 3, and filtering to obtain filtrate I;
Step (2): dissolving neodymium iron boron waste materials in oxalic acid waste water to obtain iron slag after rare earth is recovered, obtaining solution containing ferric ions, adding sodium hydroxide to adjust the pH value to 1.5, and filtering to obtain filtrate II;
step (3): adding sodium hydroxide into the filtrate II to adjust the pH to 3, placing the filtrate I under 570nm light, and adding the filtrate II into the filtrate I in portions, wherein the volume of the filtrate II is not 1/3 of that of the filtrate II; the mixed solution turns yellow gradually and bubbles and sediment are generated in the reaction process; filtering to obtain filtrate III and residue I;
step (4): the pH of filtrate III was adjusted after fenton=6.5; filtering to obtain filtrate IV and filter residue II, and drying the filter residue I to obtain the ferrous oxalate with the purity of 97%.
The main reaction involved in the invention is as follows:
Fe+2H+→Fe2++H2↑ (7)
H2O2+Fe2+→Fe3+OH-+·OH (9)
Fe3++3OH-→Fe(OH)3↓ (11)
4Fe2+O2+4H+→4F3++2H2O (12)
Fe+2Fe3+→3Fe2+ (13)
3H++Fe(OH)3→Fe3++3H2O (14)
in a preferred technical scheme of the invention, when the iron source is one or more of ferric iron and ferric iron, the method comprises the following steps:
(1) Adding iron into oxalic acid wastewater; n (Fe) is n (H 2C2O4) is less than or equal to 4:3;
(2) Adding alkali into the oxalic acid wastewater to adjust the pH value to be within a range of 1.0-8.0;
The reuse water is obtained.
The above steps relate to equations (1), (2), (3), (5), (6), (8), (15).
In a preferred embodiment of the present invention, the reaction (4) is involved by illuminating the basic-added solution obtained in step (2). The illumination source may be sunlight. Preferably visible light with a wavelength of less than 570nm, more preferably ultraviolet light.
In a preferred embodiment of the invention, the residual oxalic acid concentration of the recycled water is less than or equal to 6.25mmol/L. Preferably not more than 2.33mmol/L, more preferably not more than 0.67mmol/L of residual oxalic acid can be obtained by subsequent Fenton.
In a preferred embodiment of the invention, the reuse water may be evaporated to recover salts.
In a preferred embodiment of the present invention, in the step (1), preferably 0.5.ltoreq.n (Fe): n (H 2C2O4). Ltoreq.1, more preferably n (Fe): n (H 2C2O4) is 1:1, or 1:2, 2:3. in a preferred embodiment of the invention, when the iron is ferric or ferric, staged addition of base is used, as follows:
a, adding alkali into the iron-containing solution obtained in the step (1) to ensure that the pH value of the iron-containing solution is between 1.5 and 2;
Recovering rare earth oxalate, cobalt and other metal salts.
B, continuing the addition of base to a pH in the range of 3-8, preferably 4-7, more preferably 4-6.
In a preferred embodiment of the present invention, a certain amount of the alkaline-added liquid obtained in the step (2) is added to a certain amount of oxalic acid wastewater to be treated, and the specific method is as follows:
a, treating a certain amount of oxalic acid wastewater in the steps (1) and (2) to obtain an alkali-added liquid;
b, adding the alkaline added liquid in the step a into a certain amount of oxalic acid wastewater to be treated.
Among them, the mixed solution in b is preferably irradiated with light. Preferably, the adding mode of the liquid after adding the alkali in the step b is divided into two times, more preferably, half of the liquid after adding the alkali firstly and the rest half of the liquid are added dropwise.
Preferably, a certain amount of oxalic acid wastewater to be treated in the step b can be firstly added with alkali to adjust the pH value to 5, and the impurities are firstly removed through solid-liquid separation;
2) When the iron source is one or more of zero-valent iron or ferrous iron, the method comprises the steps of: :
(1) Adding iron into oxalic acid wastewater; n (Fe) is n (H 2C2O4) is less than or equal to 4:3;
(2) Adding alkali into the oxalic acid wastewater to adjust the pH value to be within a range of 1.0-8.0;
The reuse water is obtained.
The above steps relate to equations (5), (6) and (8). In particular, in the case of zero-valent iron, equations (7) and (13) are involved.
In a preferred embodiment of the present invention, n (Fe) in the step (1) is represented by n (H 2C2O4) which is 1:5. in a preferred embodiment of the present invention, the pH in step (2) is in the range of 4 to 6.
In a preferred embodiment of the invention, the reuse water is followed by Fenton to reduce the residual oxalate concentration to 0.83mmol/L. Reaction formulae (9), (10) and (11) are involved.
The beneficial effects of this scheme are as follows:
Compared with the traditional lime neutralization method, if the pH of the end point is controlled to be 7, the technical scheme consumes acid in the wastewater by iron resources such as iron slag and the like, and leaves the water body through a ferrous oxalate (FeC 2O4·2H2 O) byproduct form, so that the alkali consumption can be saved by treating the wastewater containing oxalic acid. Can obviously reduce the discharge of subsequent salt, is beneficial to realizing green circular economy and has obvious social value. And measuring and calculating the annual output of the waste iron slag by 7.8 ten thousand tons and 390 ten thousand cubic meters of oxalic acid wastewater according to the output of the rare earth and the output of the neodymium iron boron magnet. According to the scheme, low-value iron resources such as iron slag (about 500 yuan/ton) and the like after rare earth is recycled by using neodymium iron boron waste materials are used for treating oxalic acid waste water, the purpose of treating waste by waste is achieved, and a high-value ferrous oxalate byproduct (about 5000 yuan/ton) is prepared. The high-value utilization of iron resources is realized, the unit iron value is obviously improved, a large amount of treatment cost of neutralization slag and the like is saved, and the method has obvious economic benefit. The evaporation method and the extraction method can better realize the resource utilization of the wastewater, but related equipment, auxiliary materials and the like greatly improve the treatment cost. How to treat COD and recycle salt in high-salt oxalic acid wastewater with low cost is a technical problem which is long and is not solved all the time, and the scheme provides a new solution for green development of hydrometallurgy industry and comprehensive utilization of wastewater, the COD in the treated recycled water can be reduced to 100mg/L, and the salt can be recycled by seamless butt joint evaporation. The scheme has obvious social and economic benefits, low cost, easily controlled process and easy realization of industrialization, and has obvious popularization value.
The reuse water treated by the scheme can be evaporated to recover salt to prepare condensate water, and the condensate water can be directly reused or directly discharged; can also be used as Fenton-like raw material for treating high COD wastewater such as extraction wastewater, carbon precipitation wastewater and the like. Enriches the application of the reuse water and widens the application channel of oxalate in the wastewater. The iron resource can be directly converted to generate ferrous oxalate byproducts with high added value for sale, ferrite raw materials such as ferric oxide, ferrous oxide and the like can also be indirectly prepared, and the high-value comprehensive utilization of the iron resource can be realized. The traditional lime neutralization method not only needs energy consumption for calcium chloride evaporation, but also has lower added value of the obtained calcium chloride, and the salts such as ammonium chloride, potassium chloride and the like contained in the recycled water treated by the technical scheme have low evaporation cost, high added value and easy industrialization realization, thereby realizing comprehensive utilization of chloride ions.
The biochemical method is a method of treating organic matters in water by using microorganisms. Oxalic acid BOD 5/COD >0.3, and good biodegradability. However, oxalic acid wastewater generally contains a large amount of salts at the same time, and is not suitable for a biochemical method. According to the scheme, the green chemical method is adopted, so that the high-salt high-COD oxalic acid wastewater treatment and the comprehensive utilization of related resources can be realized. Fenton oxidation is used as a high-grade oxidation technology, wherein generated hydroxyl radicals have high oxidation potential, and indifferent oxidation of organic matters can be realized. But the reaction speed of the hydroxyl radical is very slow when the wastewater containing oxalic acid is treated, the treatment efficiency is very low, the process control is very complex, and the cost is very high. The solution scheme for rapidly, efficiently, simply and easily controlling, stably treating oxalic acid wastewater with low cost has good market prospect.
The raw materials and the auxiliary materials selected by the scheme have the advantages of wide sources, safety, stability, easy obtainment and the like. The process is flexible and stable, and is easy to industrialize and engineer. The method can recycle rare earth oxalate, cobalt oxalate and other high-value oxalate while treating oxalic acid wastewater, thereby recycling resources to produce economic value and improving the purity of byproducts.
According to the scheme, iron element can be added to form ferrous oxalate precipitation (precipitation) with oxalic acid, ferric iron can form ferric oxalate complex with good photochemical activity with oxalic acid, oxalic acid radical leaves the water body in a CO 2 mode through photodecomposition, meanwhile, conversion from ferric iron to ferrous iron is completed, and oxalic acid radical is continuously precipitated. The Fenton-like system can be formed by matching with hydrogen peroxide, more efficient Fenton-like can be formed by adding illumination elements, and finally impurities in water can be adsorbed after the Fenton-like system leaves the water in a hydroxide form. Iron plays a variety of roles in the comprehensive utilization of oxalic acid wastewater, and breaks through the inherent cognition of iron.
The scheme realizes the short-process comprehensive utilization of oxalic acid, hydrochloric acid and iron resources to a certain extent, is environment-friendly in operation, does not need strong acid and alkali resistant equipment, can not bring other environmental protection problems while realizing the comprehensive utilization of waste water, and can radically solve the comprehensive treatment problem of oxalic acid waste water in the hydrometallurgy industry at one time.
Drawings
FIG. 1 is a schematic view of a process flow according to an embodiment
Detailed Description
Example 1
The concentration of oxalic acid in the rare earth wastewater [ oxalic acid radical (Ox 2-) is 0.246mol/L calculated by oxalic acid (Ox) (the same applies below),The iron slag (main component is Fe (OH) 3) after the rare earth is recovered by dissolving the NdFeB waste material to obtain 1L solution [ n (Fe) =0.326 mol ] containing ferric ions.
And (2) adding ammonia water (28 wt%) into 2.6L of oxalic acid precipitation rare earth wastewater to adjust the pH value to 5, and filtering to remove a small amount of solid impurities (the impurities are mainly oxalic acid rare earth through detection, and timely recovery is carried out to be beneficial to improving the overall rare earth yield) so as to obtain filtrate I.
Slowly dropwise adding the ferric ion solution in the step (1) into the filtrate I in the sun, and controlling the pH to be about 5 by using ammonia water in the process. In the process, the mixed solution turns green and then yellow, and bubbles and precipitation are generated. When the concentration of oxalic acid radical (calculated by oxalic acid, the same applies hereinafter) in the mixed solution is reduced to 6mmol/L (reaching the recycling standard), filtering is carried out, and filter residue I and filtrate II are obtained. The obtained residue I was dried to obtain 53.08g of ferrous oxalate having a purity of 96.95%.
And the pH value of the filtrate II is regulated to be 6.5 after Fenton (pH value=5, hydrogen peroxide consumption is 3.4mL (30% H 2O2) and time is 2 h), filter residue II and filtrate III are obtained through filtration, the filter residue II can be used as an iron source for recycling, the recovery amount of the filter residue II is 6.11g, and the main components are ferric hydroxide and water for direct recycling. The concentration of the oxalic acid radical in the filtrate III is detected to be 2.67mmol/L, and the discharge standard is reached. The data analysis and process flow chart is shown in figure 1.
Compared with the traditional lime neutralization method, if the pH of the end point is controlled to be 7, the slaked lime is needed for treating 1L of oxalic acid precipitation rare earth wastewaterIf the base is aqueous ammonia, 2.1mol is required. In the scheme, as the iron slag is used for consuming acid in the wastewater and leaves the water body through the ferrous oxalate (FeC 2O4·2H2 O) byproduct form, the use amount of ammonia water can be saved by 0.23mol (=53.08 x 96.95%/180/3.6 x 3) by treating 1L oxalic acid precipitation rare earth wastewater. Can obviously reduce the discharge of subsequent salt, is beneficial to realizing green circular economy and has obvious social value.
According to the scheme, the oxalic acid wastewater is treated by using low-value iron slag (about 500 yuan/ton) after rare earth is recovered from neodymium iron boron waste, so that the purpose of treating waste by waste is achieved, and a high-value ferrous oxalate byproduct (about 5000 yuan/ton) is prepared. Realizes the high-value utilization of iron resources, and improves the unit iron value by at least 15 times. Compared with the traditional lime neutralization method, the method omits a large amount of neutralization slag treatment cost and has obvious economic benefit.
How to treat COD and recycle salt in high-salt oxalic acid wastewater with low cost is a technical problem which is long desired to be solved but is not solved all the time, and the scheme provides a new solution for green development of hydrometallurgy industry and comprehensive utilization of wastewater. COD in the oxalic acid wastewater treated by the scheme can be reduced to 43.7mg/L, and the salt content (ammonium chloride meter) of 0.23 mol/(L wastewater) is reduced, so that the salt can be recovered by seamless butt joint evaporation. The scheme has obvious social and economic benefits, low cost, easily controlled process and easy realization of industrialization, and has obvious popularization value.
The auxiliary materials such as ammonia water, iron slag and the like selected in the embodiment have the advantages of wide sources, safety, stability, easy obtainment and the like. The process is flexible and stable, and is easy to industrialize and engineer.
The method can recycle rare earth oxalate of high value while treating oxalic acid wastewater, thereby not only recycling resources to produce economic value, but also improving the purity of byproducts.
In the embodiment, ferric iron is added to form an oxalic acid iron complex with good photochemical activity with oxalic acid (reactions (1), (2) and (3)), the oxalic acid radical leaves the water body in a CO2 form through photodecomposition, the conversion from ferric iron to ferrous iron is completed (reaction 4), the oxalic acid radical is continuously precipitated (reaction 8), and the oxalic acid radical is matched with hydrogen peroxide to form a Fenton system (reaction 9), so that the oxalic acid radical content is further reduced (reaction 10). Iron plays a variety of roles in the comprehensive utilization of oxalic acid wastewater, and breaks through the inherent cognition of iron.
Example-Fenton front oxalate material balance table, illustrating the mode, proportion and removal efficiency of oxalic acid leaving the water:
Example two
The concentration of oxalic acid radical is 0.333mol/L,Ammonia water (10 mol/L) is added into 200L of wastewater to adjust the pH value to 5, the filtrate I is obtained by filtration, and filter residues are recovered (the impurity is mainly oxalic acid rare earth by detection and is timely recovered, thereby being beneficial to improving the overall rare earth yield).
To the filtrate I was added 18.1kg of ferric chloride hexahydrate solids such that n (Fe): n (H 2C2O4) =1:1, the solution turned green, and the mixture was placed in sunlight, and the mixture turned yellow gradually with the generation of bubbles and precipitates.
And filtering after the reaction to obtain filtrate II and filter residue I. The quality of the filter residue I after drying is 5.32kg (detected as ferrous oxalate with the purity of 98 percent), and the concentration of oxalic acid radical in the filtrate II detected is 5mmol/L, so that the recycling standard is reached. Ferrous oxalate is burnt for 2 hours at 200 ℃ to obtain iron oxide, and the iron oxide reaches YHT5 iron oxide standard through detection, so that ferrite can be prepared.
The filtrate II treated by the embodiment can be evaporated to recover salt to prepare condensed water which can be directly recycled or directly discharged;
the filtrate II can also be used as Fenton-like raw material to treat extraction wastewater, carbon precipitation wastewater and other wastewater. Enriches the application of the reuse water and widens the application channel of oxalate in the wastewater.
The iron resource of the embodiment can be directly converted to generate ferrous oxalate byproducts with high added value for sale, and ferrite raw materials such as ferric oxide, ferrous oxide and the like can also be prepared, so that the high-value comprehensive utilization of the iron resource can be realized.
The traditional lime neutralization method not only requires energy consumption for calcium chloride evaporation, but also has low added value of the obtained calcium chloride. The ammonium chloride salt contained in the recycled water treated by the method has low evaporation cost and high added value, and can realize comprehensive utilization of chloride ions.
The method can recycle rare earth oxalate of high value while treating oxalic acid wastewater, thereby not only recycling resources to produce economic value, but also improving the purity of byproducts.
Ferric iron and oxalic acid can form an oxalic acid iron complex with good photochemical activity (reactions (1), (2) and (3)) by adding the scheme, oxalic acid radicals leave a water body in the form of CO 2 through photodecomposition, meanwhile, the conversion from ferric iron to ferrous iron is finished (reaction (4)), and oxalic acid radicals are continuously precipitated (reaction (8)). Iron plays a variety of roles in the comprehensive utilization of oxalic acid wastewater, and breaks through the inherent cognition of iron.
Example III
According to the invention of CN105732359a, the wastewater after solid-liquid separation was post-treated (detected oxalate concentration 0.16mol/L, pH =6) in example 1 (5).
To 1000mL of this wastewater was added 8.9g of ferrous sulfate heptahydrate, and the mixture was stirred with oxygen gas, and a yellow precipitate was formed. Filtering the mixture with the precipitate to obtain filtrate I and filter residue.
The concentration of oxalic acid radical in the filtrate I is detected to be 2.33mmol/L, the pH=7 is regulated by adding ammonia water (25 wt%) after Fenton (pH=6, the dosage of 30% hydrogen peroxide is 2.4mL and the time is 2 h), and the filtrate II is obtained by filtering, wherein the concentration of oxalic acid radical in the filtrate II is 0.83mmol/L, and the emission standard is reached.
And drying the filter residue to obtain ferrous oxalate with the purity of 98%.
The ferrous oxalate precipitate generated in the embodiment can be collected as a byproduct for sale, can be decomposed at 200 ℃ and then used as an iron source for recycling, and can also be indirectly prepared into ferrite raw materials such as ferric oxide, ferrous oxide and the like.
The auxiliary materials such as ferrous sulfate, ammonia water, sulfuric acid and the like selected in the embodiment have the advantages of wide sources, safety, stability, easy obtainment and the like. The process is flexible and stable, and is easy to industrialize and engineer.
In this example, ferrous iron is added to form ferrous oxalate precipitate with oxalic acid (reaction (8)), and the ferrous iron can be converted into ferric iron under the condition of oxygen introduction and participate in iron circulation (reaction (4)). Ferrous iron in the filtrate I is matched with hydrogen peroxide to form a Fenton system (reaction (9)), and finally leaves the water body in a hydroxide form (reaction (11)) and can adsorb impurities in the water. Iron plays a variety of roles in the comprehensive utilization of oxalic acid wastewater, and breaks through the inherent cognition of iron.
Example IV
According to the invention of CN112340918A, the filtrate and the washing liquid (the concentration of oxalic acid radical is 0.2mol/L and the concentration of hydrogen ion is 2.7 mol/L) are recycled.
Adding ammonia water (12 mol/L) into 500mL of grass wastewater to adjust the pH to 5, and filtering to obtain filtrate I. In addition, 500mL of the waste water is taken to dissolve iron slag (the main component is Fe (OH) 3) after the rare earth is recovered from the NdFeB waste material, so as to obtain a solution containing ferric ions (the concentration is 0.392 mol/L), ammonia water is added to adjust the pH value to 1.5, and the filtrate II is obtained by filtering. Adding 1/3 of the filtrate II into the filtrate I to obtain a mixed solution, and filling the rest part of the filtrate II into a hanging bottle. The mixed solution is placed under the sun, the liquid in the hanging bottle is slowly dripped into the mixed solution, and the pH is controlled to be about 5 (ammonia water is used). The mixture gradually turns yellow during the reaction and bubbles and precipitates are generated. When the concentration of oxalic acid radical in the mixed solution is reduced to 5.3mmol/L, filtering to obtain filtrate III and filter residue I. The filtrate III was adjusted to ph=6.5 after Fenton (ph=5, 30% hydrogen peroxide usage=6.7 mL, time 2 h). Filtering to obtain filter residue II and filtrate IV, wherein the concentration of oxalic acid radical in the obtained filtrate IV is 2.8mmol/L. And taking 500mL of filtrate IV, evaporating, and suction filtering to obtain ammonium sulfate crystals with water content of 5%. The pH=6.6 of the obtained condensate water, the ammonia nitrogen 55.95mg/L and the COD <50mg/L. 18.68g (97% purity ferrous oxalate) of residue I after drying.
In the invention content recovery step of CN112340918A, concentrated sulfuric acid is added into filtrate and washing liquid to increase the acid concentration to 18-20%, and then the filtrate and washing liquid are recovered to an acid washing tank for use. For controlling the water balance, the wastewater needs to be treated by 4-5m 3 per 1t of steel to be treated.
Compared with the traditional lime neutralization method, if the pH of the end point is controlled to be 7, in the embodiment, since the iron slag is used for consuming acid in the wastewater, and the wastewater leaves the water body in the form of a ferrous oxalate (FeC 2O4·2H2 O) byproduct, the wastewater containing oxalic acid is treated, so that the consumption of ammonia water/(L oxalic acid water) can be saved by 0.303 mol. Can obviously reduce the discharge of subsequent salt, is beneficial to realizing green circular economy and has obvious social value.
In the embodiment, the oxalic acid wastewater is treated by using the low-value iron slag (about 500 yuan/ton) obtained after rare earth is recovered from the neodymium iron boron waste, so that the purpose of treating waste by waste is achieved, and a high-value ferrous oxalate byproduct (about 5000 yuan/ton) is prepared. Realizes the high-value utilization of iron resources, and improves the unit iron value by at least 15 times. Compared with the traditional lime neutralization method, the method omits a large amount of neutralization slag treatment cost and has obvious economic benefit.
How to treat COD and recycle salt in high-salt oxalic acid wastewater with low cost is a technical problem which is long desired to be solved but is not solved all the time, and the embodiment provides a new solution for green development of hydrometallurgy industry and comprehensive utilization of wastewater. COD in the recycled water treated by the method can be reduced to 44.8mg/L, and salt is recovered by subsequent seamless butt joint evaporation. The scheme has obvious social and economic benefits, low cost, easily controlled process and easy realization of industrialization, and has obvious popularization value.
In the embodiment, the ferric iron adding mode of firstly partial and then dropwise adding is adopted, and compared with the whole-process dropwise adding scheme, the treatment time of the wastewater is shortened, and the method is a preferable ferric iron adding mode.
Ferric iron is added to form an oxalic acid iron complex with good photochemical activity with oxalic acid, oxalic acid radicals leave a water body in the form of CO 2 through photodecomposition, the conversion of ferric iron to ferrous iron is completed (reactions (1), (2) and (3)), and ferrous iron obtained through conversion can precipitate oxalic acid radicals to form ferrous oxalate with high added value (reaction (8)). Under the condition that an iron source is not required to be additionally added, the ferrous iron in the filtrate III is directly matched with hydrogen peroxide to form a Fenton system, and the ferrous iron plays a role of a catalyst (reaction (9)). Finally, the iron in the water body subjected to pH adjustment leaves the water body in the form of high-activity ferric hydroxide (reaction (11)), and a large amount of impurities can be adsorbed. In conclusion, iron plays a variety of roles in comprehensive utilization of oxalic acid wastewater, has obvious technical effects, and impacts general knowledge of industries on iron.
Example five
Adding 1L of oxalic acid wastewater with oxalic acid radical concentration of 0.333mol/L and hydrogen ion concentration of 2.7mol/L into deoiled iron shavings (zero-valent iron) to obtain mixed solution containing ferrous ions (0.44 mol/L), and continuously adding caustic soda flakes to ensure that the pH value of the mixed solution is=1. And yellow precipitate is generated in the reaction process, sodium chlorate is added, and when the concentration of oxalic acid radical in the mixed solution is reduced to 6.25mmol/L, the mixed solution is filtered to obtain filtrate I and filter residue I, wherein the filtrate I reaches the recycling standard. 45.25g (ferrous oxalate with 95% purity) of filter residue I is dried.
The iron shavings (about 2800 yuan/ton) produced by the mechanical processing of the embodiment treat the oxalic acid wastewater by using low-value iron resources, thereby not only achieving the purpose of treating waste by waste, but also preparing a high-value ferrous oxalate byproduct (about 5000 yuan/ton). Realizes the high-value utilization of iron resources, and the unit iron value is obviously improved. Compared with the traditional lime neutralization method, the method omits a large amount of treatment cost such as neutralization slag and the like, and has remarkable economic benefit.
Compared with the traditional lime neutralization method, if the pH of the end point is controlled to be 7, the embodiment consumes acid in the wastewater by using iron shaving, and leaves the water body in the form of a ferrous oxalate (FeC 2O4·2H2 O) byproduct, so that the consumption of 0.65 mol/(L of oxalic acid water) of sodium hydroxide can be saved by treating the oxalic acid-containing wastewater. Can obviously reduce the discharge of subsequent salt, is beneficial to realizing green circular economy and has obvious social value.
The iron shavings, sodium hydroxide and sodium chlorate auxiliary materials selected in the embodiment have the advantages of wide sources, safety, stability, easy obtainment and the like. The process is flexible and stable, and is easy to industrialize and engineer.
Example six
According to the invention of CN113652550A, the iron-precipitating post-liquid (the concentration of oxalic acid radical is detected to be 0.347mol/L and the concentration of hydrogen ions is detected to be 2.49 mol/L) for recycling the wastewater in the embodiment 1. Taking 1L of oxalic acid wastewater, adding sodium hydroxide (10 mol/L) to adjust the pH to 3, and filtering to obtain filtrate I. And additionally taking 1L of oxalic acid wastewater to dissolve iron slag (the main component is Fe (OH) 3) after the rare earth is recovered from neodymium iron boron waste materials, obtaining a solution containing ferric ions (the concentration is 0.55 mol/L), adding sodium hydroxide to adjust the pH value to 1.5, and filtering to obtain filtrate II. And adding sodium hydroxide into the filtrate II to adjust the pH to 3, placing the filtrate I under 570nm light, and adding the filtrate II into the filtrate I five times, wherein the volume of the filtrate II is not 1/3 of that of the filtrate II. The mixture gradually turns yellow during the reaction and bubbles and precipitates are generated. And when the concentration of oxalic acid radical in the mixed solution is reduced to 1.3mmol/L, filtering to obtain filtrate III and filter residue I, and adjusting the pH value of the filtrate III to be 6.5 after Fenton. Filtering to obtain filtrate IV and filter residue II, wherein the concentration of oxalic acid radical in the filtrate IV is 0.67mmol/L. The quality of the residue I after drying is 73.27g (purity 97% ferrous oxalate). The data analysis is shown in the following table.
Compared with the traditional lime neutralization method, if the pH of the end point is controlled to be 7, in the embodiment, since the iron slag is used for consuming acid in the wastewater, and the wastewater leaves the water body in the form of a ferrous oxalate (FeC 2O4·2H2 O) byproduct, the sodium hydroxide consumption can be saved by 0.59 mol/(L of oxalic acid water) in the treatment of the oxalic acid-containing wastewater. Can obviously reduce the discharge of subsequent salt, is beneficial to realizing green circular economy and has obvious social value.
In the embodiment, the oxalic acid wastewater is treated by using the low-value iron slag (about 500 yuan/ton) obtained after rare earth is recovered from the neodymium iron boron waste, so that the purpose of treating waste by waste is achieved, and a high-value ferrous oxalate byproduct (about 5000 yuan/ton) is prepared. Realizes the high-value utilization of iron resources, and improves the unit iron value by at least 15 times. Compared with the traditional lime neutralization method, the method omits a large amount of neutralization slag treatment cost and has obvious economic benefit.
How to treat COD and recycle salt in high-salt oxalic acid wastewater with low cost is a technical problem which is long desired to be solved but is not solved all the time, and the scheme provides a new solution for green development of hydrometallurgy industry and comprehensive utilization of wastewater. COD in the recycled water treated by the scheme can be reduced to 10.8mg/L, and salt can be recovered by seamless butt joint evaporation in the follow-up process. The scheme has obvious social and economic benefits, low cost, easily controlled process and easy realization of industrialization, and has obvious popularization value.
Ferric iron is added to form an oxalic acid iron complex with good photochemical activity with oxalic acid, oxalic acid radicals leave a water body in the form of CO 2 through photodecomposition, the conversion of ferric iron to ferrous iron is completed (reactions (1), (2) and (3)), and ferrous iron obtained through conversion can precipitate oxalic acid radicals to form ferrous oxalate with high added value (reaction (8)). Under the condition that other iron sources are not required to be added additionally, the ferrous iron in the filtrate III is directly matched with hydrogen peroxide to form a Fenton system, and the ferrous iron plays a role of a catalyst (reaction (9)). Finally, the iron in the water body subjected to pH adjustment leaves the water body in the form of high-activity ferric hydroxide (reaction (11)), and a large amount of impurities are adsorbed. In conclusion, iron plays a variety of roles in comprehensive utilization of oxalic acid wastewater, has obvious technical effects, and impacts general knowledge of industries on iron.
Example seven
Taking 1L of oxalic acid wastewater with the same composition as in the first embodiment, adding potassium hydroxide (11 mol/L) to adjust the pH to 8, and filtering to obtain filtrate I. And dissolving potassium ferrate in 1L of oxalic acid wastewater to obtain a solution containing ferric ions (the concentration is 0.25 mol/L), adding potassium hydroxide to adjust the pH to 1.5, and filtering to obtain a filtrate II. Adding potassium hydroxide into the filtrate II to adjust the pH to 8, taking 1/3 of the filtrate I to obtain a mixed solution, and filling the rest part of the filtrate II into a hanging bottle. And (3) placing the mixed solution under ultraviolet light, and slowly dripping the liquid in the hanging bottle into the mixed solution. The mixture gradually turns yellow during the reaction and bubbles and precipitates are generated. And (3) filtering to obtain filtrate III and filter residue I when the concentration of oxalic acid radical in the mixed solution is reduced to 5mmol/L, and regulating the pH value of the filtrate III to be 6.5 after Fenton. Filtering to obtain filter residue II and filtrate IV, wherein the concentration of oxalic acid radical in the filtrate IV is 2.33mmol/L, and the discharge requirement is met. The quality of the filter residue I after drying is 45.24g (98% ferrous oxalate).
The filtrate IV treated by the embodiment can be evaporated to recover salt to prepare condensed water which can be directly recycled or directly discharged; the filtrate IV can also be used as Fenton-like raw material for treating extraction wastewater, carbon precipitation wastewater and other wastewater. Enriches the application of the reuse water and widens the application channel of oxalate in the wastewater.
The iron resource of the embodiment can be directly converted to generate ferrous oxalate byproducts with high added value for sale, and ferrite raw materials such as ferric oxide, ferrous oxide and the like can also be indirectly prepared, so that the high-value comprehensive utilization of the iron resource can be realized.
The traditional lime neutralization method not only requires energy consumption for calcium chloride evaporation, but also has low added value of the obtained calcium chloride. The potassium chloride salt contained in the reuse water treated by the embodiment has low evaporation cost and high added value, and realizes the comprehensive utilization of chloride ions.
The embodiment can recycle rare earth oxalate and rare earth hydroxide while treating oxalic acid wastewater (while preparing filtrate I and filtrate II), thereby not only recycling resources to generate economic value, but also improving the purity of byproducts.
How to treat COD and recycle salt in high-salt oxalic acid wastewater with low cost is a technical problem which is long desired to be solved but is not solved all the time, and the scheme provides a new solution for green development of hydrometallurgy industry and comprehensive utilization of wastewater. COD in the recycled water treated by the scheme can be reduced to 37.28mg/L, and salt can be recovered by subsequent seamless butt joint evaporation. The scheme has obvious social and economic benefits, low cost, easily controlled process and easy realization of industrialization, and has obvious popularization value.
In this example, the iron source is added to be converted into ferric iron through a series of reactions, ferric iron can form ferric oxalate complex with good photochemical activity with oxalic acid, oxalic acid radical leaves the water body in the form of CO 2 through photodecomposition, meanwhile, conversion from ferric iron to ferrous iron is completed (reaction (4)), and ferrous iron continues to precipitate oxalic acid radical (reaction (8)). Iron plays a variety of roles in the comprehensive utilization of oxalic acid wastewater, and breaks through the inherent cognition of iron.
Example eight
Taking 1L of oxalic acid wastewater with the same composition as in the first embodiment, adding sodium hydroxide (5 mol/L) to adjust the pH to 3, and filtering to obtain filtrate I. And additionally taking 1L of oxalic acid wastewater to dissolve iron slag (the main component is Fe (OH) 3) after the rare earth is recovered from neodymium iron boron waste materials, obtaining a solution containing ferric ions (the concentration is 0.739 mol/L), adding sodium hydroxide to adjust the pH value to 1.5, and filtering to obtain filtrate II. And adding sodium hydroxide into the filtrate II to adjust the pH to 3, placing the filtrate I into indoor visible light, and adding the filtrate II into the filtrate I at one time. The mixture gradually turns yellow during the reaction and bubbles and precipitates are generated. Filtering to obtain filtrate III and residue I when the concentration of oxalic acid radical in the mixed solution is unchanged for a long time, and drying the residue I to obtain the product with the mass of 8.15g (ferrous oxalate with the purity of 96%). The data analysis is shown in the following table.
Example nine
Adding iron slag (main component is Fe (OH) 3) with recovered rare earth from neodymium iron boron waste into oxalic acid waste water 300L with the same composition as that of the first embodiment to obtain a solution containing ferric ions (concentration is 0.17 mol/L), adding ammonia water (9 mol/L) to adjust pH to 2, and filtering to obtain filtrate I. Ammonia water is added into the filtrate I to adjust the pH value to 4, and the filtrate I is placed in the sun for reaction, wherein the filtrate I gradually turns yellow and bubbles and precipitation are generated during the reaction. And when the concentration of oxalic acid radical in the filtrate I is reduced to 5.3mmol/L, filtering to obtain filtrate II and filter residue I, and adjusting the pH value of the filtrate II to be 6.5 after Fenton (pH value=4, hydrogen peroxide consumption of 0.44L and reaction time of 2 h). Filtering to obtain filter residue II and filtrate III, wherein the concentration of oxalic acid radical in the filtrate III is 2.64mmol/L. The data analysis is shown in the following table. And evaporating 500mL of filtrate III to obtain ammonium chloride crystals (moisture content is 5%), wherein COD (chemical oxygen demand) of condensed water is less than 50mg/L, and ammonia nitrogen is 55.95mg/L. Mixing filtrate III50L with 500L extraction wastewater with COD=2360 mg/L, adding ammonia water to adjust the pH to 7, and adding 26.3g of ferric trichloride hexahydrate and 30% hydrogen peroxide to 7.53L to obtain a mixed solution. Hydrochloric acid is added in the reaction process of the mixed solution in the sun to stabilize the pH at about 7. And (3) bubbling out in the reaction process, ending the reaction when the COD of the mixed solution is reduced to below 100mg/L, and filtering to remove iron to obtain filtrate IV. The residue I was dried to obtain 7.92kg of ferrous oxalate (purity 97%).
Compared with the traditional lime neutralization method, if the pH of the end point is controlled to be 7, in the embodiment, since the iron slag is used for consuming acid in the wastewater, and the wastewater leaves the water body in the form of a ferrous oxalate (FeC 2O4·2H2 O) byproduct, the wastewater containing oxalic acid is treated, so that the consumption of ammonia water/(L oxalic acid water) can be saved by 0.42 mol. Can obviously reduce the discharge of subsequent salt, is beneficial to realizing green circular economy and has obvious social value.
According to the scheme, low-value iron resources such as iron slag (about 500 yuan/ton) and the like after rare earth is recycled by using neodymium iron boron waste materials are used for treating oxalic acid waste water, the purpose of treating waste by waste is achieved, and a high-value ferrous oxalate byproduct (about 5000 yuan/ton) is prepared. Realizes the high-value utilization of iron resources, and the unit iron value is obviously improved. Compared with the traditional lime neutralization method, the method omits a large amount of treatment cost such as neutralization slag and the like, and has remarkable economic benefit.
COD in the recycled water treated by the method can be reduced to 42.24mg/L, and salt can be recovered by seamless butt-joint evaporation. The scheme has obvious social and economic benefits, low cost, easily controlled process and easy realization of industrialization, and has obvious popularization value.
The filtrate III treated by the embodiment is evaporated to recover salt to prepare condensed water which can be directly recycled or directly discharged; and the filtrate III is used as Fenton-like raw material to treat extraction wastewater. Enriches the application of the reuse water and widens the application channel of oxalate in the wastewater.
The traditional lime neutralization method not only requires energy consumption for calcium chloride evaporation, but also has low added value of the obtained calcium chloride. The ammonium chloride salt contained in the reuse water treated by the technical scheme has low evaporation cost and high added value, and realizes the comprehensive utilization of chloride ions.
The iron slag, ammonia water and other auxiliary materials selected in the embodiment have the advantages of wide sources, safety, stability, easy obtainment and the like. The process is flexible and stable, and is easy to industrialize and engineer.
The rare earth oxalate can be recovered while the oxalic acid wastewater is treated, so that the economic value of resources is recovered, and the purity of byproducts is improved.
In the embodiment, ferric iron is added to form an oxalic acid iron complex with good photochemical activity with oxalic acid (reactions (1), (2) and (3)), oxalic acid radical leaves the water body in the form of CO 2 through photodecomposition, meanwhile, conversion from ferric iron to ferrous iron is completed (reaction (4)), the ferrous iron continuously precipitates oxalic acid radical, and then the oxalic acid radical is matched with hydrogen peroxide to form Fenton systems (reactions (9) and (10)), and finally, the oxalic acid radical leaves the water body in the form of hydroxide (reaction (11)), so that impurities in water can be adsorbed. Iron plays a variety of roles in the comprehensive utilization of oxalic acid wastewater, and breaks through the inherent cognition of iron.
Examples ten
In the cobalt oxalate precipitating waste liquid, the mass concentration of Co 2+ is about 1g/L hydrochloric acid, the concentration of oxalic acid is 1.0mol/L and the concentration of oxalic acid is 0.2mol/L, and the impurity is trace. Taking 1L of oxalic acid wastewater, adding ammonia water (10.5 mol/L) to adjust the pH to 4, and filtering out precipitated impurities to obtain filtrate I. 13.13g of ferrous chloride tetrahydrate is added into the filtrate I, air is introduced, ammonia water is supplemented to maintain the pH at about 4, yellow precipitate is filtered to obtain filtrate II and filter residue I, and the concentration of oxalic acid radical of the filtrate II is 1.67mmol/L. The filter residue I is washed and dried and then weighed to 11.76g (purity 96% ferrous oxalate). The filtrate II treated by the embodiment can be evaporated to recover salt to prepare condensed water which can be directly recycled or directly discharged; the filtrate II can also be used as Fenton-like raw material for treating extraction wastewater, carbon precipitation wastewater and other wastewater. Enriches the application of the reuse water and widens the application channel of oxalate in the wastewater.
The iron resource of the embodiment can be directly converted to generate ferrous oxalate byproducts with high added value for sale, and ferrite raw materials such as ferric oxide, ferrous oxide and the like can also be indirectly prepared, so that the high-value comprehensive utilization of the iron resource can be realized.
The ferrous chloride and ammonia water auxiliary materials selected in the embodiment have the advantages of wide sources, safety, stability, easy obtainment and the like. The process is flexible and stable, and is easy to industrialize and engineer.
According to the embodiment, the oxalic acid wastewater is treated to prepare the filtrate I, and meanwhile, high-value oxalate such as cobalt oxalate can be recovered, so that the economic value of resources is recovered, and the purity of byproducts is improved.
In this example, ferrous iron is added to form ferrous oxalate precipitate with oxalic acid (reaction (8)), and the ferrous iron can be converted into ferric iron and participate in iron circulation under the condition of air ventilation (reaction (4)). Iron plays a variety of roles in the comprehensive utilization of oxalic acid wastewater, and breaks through the inherent cognition of iron.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Claims (23)
1. The comprehensive utilization method of the oxalic acid wastewater is characterized by comprising the following steps of:
(1) Adding iron into oxalic acid wastewater under a light source; the molar ratio of the added iron to the oxalic acid is 0.5-1, n (Fe) is less than or equal to n (H 2C2O4); in the process, alkali is used for regulating the pH value to be within the range of 1.0-8.0, filtering is carried out, filter residue I and filtrate II are obtained, and reuse water with residual oxalic acid concentration less than or equal to 5mmol/L is obtained;
(2) The pH value of the filtrate II is regulated after Fenton or Fenton-like treatment, filter residues II and filtrate III are obtained through filtration, the filter residues II can be used as an iron source for recycling, and the filtrate III reaches the emission standard;
The alkali can be one or more of sodium hydroxide, ammonia water and potassium hydroxide;
the iron can be added in the form of one or more of zero-valent iron, ferrous iron, ferric iron and ferric iron;
The zero-valent iron comprises one or more of elemental iron and ferroalloy;
the ferrous iron comprises one or more of oxide, alkali, salt and complex;
ferric iron comprises one or more of oxides, bases, salts, complexes;
the high iron comprises one or more of oxide, salt and acid.
2. The method for comprehensively utilizing the oxalic acid wastewater according to claim 1, which is characterized in that,
The ferrous iron is one or more of ferrous oxide, ferrous hydroxide, ferrous chloride and ferrous sulfate;
ferric iron is one or more of ferric hydroxide, ferric oxide, ferric chloride and ferric sulfate;
the high iron may be one or more of sodium ferrate and potassium ferrate.
3. The method for comprehensively utilizing the oxalic acid wastewater according to claim 1, wherein if iron is ferric iron or high iron in the step (1), the adding mode is divided into two times: initial addition and subsequent addition.
4. The method for comprehensive utilization of oxalic acid wastewater according to claim 1, wherein in the step (1), the initial molar amount of iron is less than 1/3 of the molar amount of oxalic acid, and the subsequent adding mode can be one or more of dropwise adding and batch adding.
5. The method for comprehensive utilization of oxalic acid wastewater according to claim 1, wherein the pH in the step (1) is 1.5-6.5.
6. The method for comprehensively utilizing the oxalic acid wastewater according to claim 1, wherein the concentration range of the alkali is as follows: not less than 10mol/L.
7. The method for comprehensively utilizing the oxalic acid wastewater according to claim 1, wherein the concentration of residual oxalic acid in the reuse water is less than or equal to 2.33mmol/L.
8. The method for comprehensively utilizing oxalic acid wastewater according to claim 1, wherein the concentration of residual oxalic acid is less than or equal to 0.67mmol/L after subsequent Fenton.
9. The method for comprehensively utilizing the oxalic acid wastewater according to claim 1, wherein when iron is ferric iron or high iron, alkali is added in sections, and the method is as follows:
a, adding alkali into the iron-containing solution obtained in the step (1) to ensure that the pH value of the iron-containing solution is between 1.5 and 2;
Recovering rare earth and cobalt oxalate;
b, continuing to add alkali to ensure that the pH range is 3-8.
10. The method for comprehensively utilizing oxalic acid wastewater according to claim 1, wherein a certain amount of the alkaline-added liquid obtained in the step (1) is added into a certain amount of oxalic acid wastewater to be treated, and the method comprises the following steps:
a, treating a certain amount of oxalic acid wastewater in the step (1) to obtain an alkali-added liquid;
b, adding the alkaline added liquid in the step a into a certain amount of oxalic acid wastewater to be treated.
11. The method for comprehensively utilizing the oxalic acid wastewater according to claim 10, wherein the mixed solution in the step b is irradiated with light; b, adding the alkali into the solution in a mode of adding the alkali into the solution twice in sequence; firstly adding one half of the alkaline solution and dripping the rest half of the alkaline solution; b, adding alkali into a certain amount of oxalic acid wastewater to be treated to adjust the pH value to 5, and removing impurities through solid-liquid separation.
12. The method for comprehensive utilization of oxalic acid wastewater according to claim 1, comprising the step of evaporating reuse water to recover salt.
13. The method for comprehensively utilizing oxalic acid wastewater according to claim 1, wherein the light source can be sunlight, visible light or ultraviolet light with wavelength less than 570 nm.
14. The method for comprehensive utilization of oxalic acid wastewater according to any one of claims 1 to 13, wherein the oxalic acid wastewater is wastewater produced in nonferrous metallurgy, metal processing, medicine, printing and dyeing and plastics industries.
15. The method for comprehensive utilization of oxalic acid wastewater according to any one of claims 1 to 13, wherein the oxalic acid wastewater is industrial wastewater in hydrometallurgy and metal processing industries.
16. The method for comprehensively utilizing oxalic acid wastewater according to any one of claims 1-13, wherein the oxalic acid wastewater is waste water from production of rare earth and cobalt nonferrous metals.
17. The method for comprehensive utilization of oxalic acid wastewater according to any one of claims 1 to 13, wherein the iron is iron slag obtained after recycling rare earth from neodymium iron boron waste.
18. The method for comprehensively utilizing the oxalic acid wastewater according to claim 1, which is characterized by comprising the following steps:
step (1): dissolving neodymium iron boron waste materials with oxalic acid precipitation rare earth waste water to recover iron slag after rare earth;
Step (2): adding ammonia water into oxalic acid precipitation rare earth wastewater to adjust the pH value, and filtering to obtain filtrate I;
Step (3): slowly dropwise adding the ferric ion solution in the step (1) into the filtrate I in the sun, and controlling the pH value by using ammonia water in the process; filtering to obtain filter residue I and filtrate II;
step (4): and regulating the pH value of the filtrate II after Fenton, filtering to obtain filter residue II and filtrate III, wherein the filter residue II can be used as an iron source for recycling, and the filtrate III reaches the emission standard.
19. The method for comprehensive utilization of oxalic acid wastewater according to claim 18, wherein,
The concentration of ammonia water in the step (2) is 28 weight percent, and the pH value is adjusted to 5;
In the step (3), ammonia water is used for controlling the pH value to be stabilized between 4 and 6; in the process, the mixed solution turns green and then yellow, and bubbles and precipitation are generated; drying the obtained filter residue I to obtain ferrous oxalate with the purity of 96.95%;
In the step (4), the pH value of the filtrate II is regulated to be 6.5 after Fenton, filter residues II and filtrate III are obtained through filtration,
In the Fenton reaction, the pH=5, the concentration of hydrogen peroxide is 30%, and the reaction time is 2 hours.
20. The method for comprehensively utilizing the oxalic acid wastewater according to claim 1, which is characterized by comprising the following steps:
Step (1): iron-precipitating post-liquid for recycling waste water; adding 10mol/L sodium hydroxide into the oxalic acid wastewater, adjusting the pH to 3, and filtering to obtain filtrate I;
Step (2): dissolving neodymium iron boron waste materials in oxalic acid waste water to obtain iron slag after rare earth is recovered, obtaining solution containing ferric ions, adding sodium hydroxide to adjust the pH value to 1.5, and filtering to obtain filtrate II;
step (3): adding sodium hydroxide into the filtrate II to adjust the pH to 3, placing the filtrate I under 570nm light, and adding the filtrate II into the filtrate I in portions, wherein the volume of the filtrate II is not 1/3 of that of the filtrate II; the mixed solution turns yellow gradually and bubbles and sediment are generated in the reaction process; filtering to obtain filtrate III and residue I;
Step (4): the pH of filtrate III was adjusted after fenton=6.5; filtering to obtain filtrate IV and filter residue II, and drying the filter residue I to obtain the ferrous oxalate with the purity of 97%.
21. The method for comprehensive utilization of oxalic acid wastewater according to claim 1, wherein the pH range of step (1) is 4-6.
22. The method for comprehensive utilization of oxalic acid wastewater according to claim 9, wherein,
B, continuing to add alkali to ensure that the pH range is 4-7.
23. The method for comprehensive utilization of oxalic acid wastewater according to claim 9, wherein,
B, continuing to add alkali to ensure that the pH range is 4-6.
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