CN118183975A - Method for treating sludge in sodium fluosilicate wastewater - Google Patents
Method for treating sludge in sodium fluosilicate wastewater Download PDFInfo
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- CN118183975A CN118183975A CN202410151125.8A CN202410151125A CN118183975A CN 118183975 A CN118183975 A CN 118183975A CN 202410151125 A CN202410151125 A CN 202410151125A CN 118183975 A CN118183975 A CN 118183975A
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- 239000010802 sludge Substances 0.000 title claims abstract description 197
- 239000002351 wastewater Substances 0.000 title claims abstract description 56
- 239000011734 sodium Substances 0.000 title claims abstract description 53
- 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 title claims abstract description 51
- 229910052708 sodium Inorganic materials 0.000 title claims abstract description 51
- 238000000034 method Methods 0.000 title claims abstract description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 67
- 238000006243 chemical reaction Methods 0.000 claims abstract description 53
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 52
- 239000011737 fluorine Substances 0.000 claims abstract description 52
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims abstract description 36
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 34
- 239000011574 phosphorus Substances 0.000 claims abstract description 34
- 239000002893 slag Substances 0.000 claims abstract description 27
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims abstract description 21
- 229910001634 calcium fluoride Inorganic materials 0.000 claims abstract description 21
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical group O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 claims abstract description 16
- 239000001506 calcium phosphate Substances 0.000 claims abstract description 15
- 229910000389 calcium phosphate Inorganic materials 0.000 claims abstract description 15
- 235000011010 calcium phosphates Nutrition 0.000 claims abstract description 15
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 claims abstract description 15
- 230000001502 supplementing effect Effects 0.000 claims abstract description 12
- 238000004537 pulping Methods 0.000 claims abstract description 3
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 claims abstract 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 184
- 239000002253 acid Substances 0.000 claims description 114
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 92
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 58
- 239000002002 slurry Substances 0.000 claims description 50
- 239000010865 sewage Substances 0.000 claims description 49
- 238000003825 pressing Methods 0.000 claims description 44
- 238000003860 storage Methods 0.000 claims description 44
- 239000012141 concentrate Substances 0.000 claims description 41
- 238000003756 stirring Methods 0.000 claims description 35
- 238000010521 absorption reaction Methods 0.000 claims description 34
- 239000000203 mixture Substances 0.000 claims description 31
- 230000001105 regulatory effect Effects 0.000 claims description 31
- 239000000463 material Substances 0.000 claims description 30
- 239000007791 liquid phase Substances 0.000 claims description 28
- 238000004062 sedimentation Methods 0.000 claims description 23
- 238000000926 separation method Methods 0.000 claims description 22
- 239000000706 filtrate Substances 0.000 claims description 20
- 238000011085 pressure filtration Methods 0.000 claims description 18
- 239000012071 phase Substances 0.000 claims description 16
- 229910019142 PO4 Inorganic materials 0.000 claims description 14
- 239000010452 phosphate Substances 0.000 claims description 14
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 14
- 239000007787 solid Substances 0.000 claims description 14
- 239000007790 solid phase Substances 0.000 claims description 13
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 12
- 239000000920 calcium hydroxide Substances 0.000 claims description 12
- 235000011116 calcium hydroxide Nutrition 0.000 claims description 12
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 8
- 230000035484 reaction time Effects 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 4
- 239000011575 calcium Substances 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 3
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 2
- 230000001376 precipitating effect Effects 0.000 claims description 2
- 238000004064 recycling Methods 0.000 abstract description 6
- 239000002920 hazardous waste Substances 0.000 abstract description 3
- 238000005406 washing Methods 0.000 abstract description 3
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 239000002910 solid waste Substances 0.000 abstract description 2
- 239000000126 substance Substances 0.000 abstract description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 48
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 25
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 25
- 239000007789 gas Substances 0.000 description 15
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 description 11
- 230000001276 controlling effect Effects 0.000 description 9
- 238000001914 filtration Methods 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 239000007788 liquid Substances 0.000 description 8
- 238000011084 recovery Methods 0.000 description 8
- 239000007921 spray Substances 0.000 description 7
- 229910004074 SiF6 Inorganic materials 0.000 description 5
- 239000006096 absorbing agent Substances 0.000 description 5
- 239000010440 gypsum Substances 0.000 description 5
- 229910052602 gypsum Inorganic materials 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000004065 wastewater treatment Methods 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 229910004014 SiF4 Inorganic materials 0.000 description 2
- -1 sodium fluorosilicate Chemical compound 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000002075 main ingredient Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- XJKVPKYVPCWHFO-UHFFFAOYSA-N silicon;hydrate Chemical compound O.[Si] XJKVPKYVPCWHFO-UHFFFAOYSA-N 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
Landscapes
- Treatment Of Sludge (AREA)
Abstract
The invention discloses a method for treating sludge in sodium fluosilicate wastewater, which comprises the steps of removing fluorine and phosphorus from sodium fluosilicate wastewater, treating sludge containing calcium fluoride, calcium phosphate and calcium sulfate by washing with water, re-pulping and the like, returning the sludge to a reaction tank of a phosphorus chemical device, recovering fluorine and phosphorus elements in the sludge, and returning sludge residues and phosphogypsum residues to a slag field after hazardous waste calcium fluoride is eliminated. The invention converts calcium fluoride in the sludge into solid waste calcium sulfate, and eliminates the risk of hazardous waste environmental protection. The system is used for supplementing water, recycling and recycling in steps, recovering fluorine and phosphorus elements in the sludge, and reducing the sludge treatment cost.
Description
Technical Field
The invention belongs to the field of wastewater and sludge treatment, and particularly relates to a method for treating sludge in sodium fluosilicate wastewater.
Background
In the sodium fluosilicate production process, the production wastewater is traditionally treated by adding slaked lime to convert fluorine, phosphorus and sulfate in the sodium fluosilicate wastewater into calcium fluoride, calcium phosphate and calcium sulfate precipitate, separating and press-filtering, and then piling up. The process has the following treatment defects: firstly, adding slaked lime to remove fluorine, phosphorus and acid from sodium fluosilicate wastewater to adjust pH can generate a large amount of calcium fluoride, calcium phosphate and calcium sulfate sludge, and the sludge is directly sent to a gypsum slag yard for stockpiling treatment, and the calcium fluoride is dangerous waste, so that once exceeding a specified value, the disposal risk is very high. And secondly, fluorine and phosphorus element loss has influence on production cost.
Disclosure of Invention
The invention solves the wastewater treatment problem of the sodium fluosilicate production process and solves the dangerous waste problem of calcium fluoride generated in the sodium fluosilicate wastewater treatment process; solves the problem of fluorine and phosphorus element loss in the sodium fluosilicate wastewater treatment process.
The invention is realized by the following technical scheme:
a method for treating sludge in sodium fluosilicate wastewater comprises the following steps:
S1, adding sodium fluosilicate sewage into a reaction material, and then heating and stirring to react to obtain a mixture of calcium fluoride, calcium phosphate and calcium sulfate; precipitating and separating the mixture to obtain sludge and wastewater from which fluorine and phosphorus are removed;
s2, carrying out filter pressing on the sludge obtained in the step S1 to obtain primary filter-pressed sludge and primary filter-pressed filtrate, and stirring and repulping the primary filter-pressed sludge to obtain a filter material;
s3, supplementing water to the filter material obtained in the step S2 to obtain primary slurry, and performing filter pressing on the primary slurry to obtain filter-pressed secondary sludge and secondary filter liquor, wherein the secondary slurry is obtained by performing filter pressing on the secondary sludge, supplementing water and re-pulping;
S4, fully stirring and mixing the secondary slurry, concentrate and sulfuric acid obtained in the step S3, and fully reacting to obtain a gas-phase mixture and a liquid-phase mixture;
s5, heating the gas phase mixture obtained in the step S4, and spraying and countercurrent absorbing with water to obtain fluosilicic acid solution; separating slag acid of the liquid phase mixture to obtain dilute acid and solid phosphogypsum; concentrating the diluted acid to obtain the concentrated acid.
Wherein, the components and the content of the sodium fluosilicate sewage are as follows: cl - is 4000mg/L, F - is 15000 mg/L, na + is 6000 mg/L, and NH 3 -N is 0.234 mg/L; total nitrogen 18.2 mg/L; total phosphorus 6.84 is mg/L; SO 4 2- is 18000 mg/L; sulfide is 0.01mg/L, and COD is 300mg/L.
Preferably, in the step S1, the components and contents of the wastewater from which fluorine and phosphorus are removed are as follows: the Cl - is 3500-3800 mg/L, the F - is 7.5-10 mg/L, the Na + is 4000-5200 mg/L, the total nitrogen is 15-16 mg/L, the total phosphorus is 2-5 mg/L, the SO 4 2- is 3000-6000 mg/L, and the COD is 1000-1800 mg/L.
Preferably, in the step S2, the components and contents of the primary filter pressing filtrate are as follows: 300-500 mg/L of Cl -, 9-10 mg/L of F-, 1200-1500 mg/L of Na +, 12-15 mg/L of TN, 3-5 mg/L of TP, 1500-2000 mg/L of SO 4 2- and 200-300 mg/L of COD.
Preferably, in the step S2, the components and mass percentages of the filter material are: 40-60% of water, 25-38% of calcium sulfate, 8-15% of calcium fluoride, 0.5-1% of calcium phosphate and 5-10% of other impurities.
Preferably, in the step S3, the components and contents of the secondary pressure filtration filtrate are as follows: cl - is 100-200 mg/L, F-is 6-9 mg/L, na + is 500-1000 mg/L, and TN is 8-10 mg/L; TP is 2-3 mg/L, SO 4 2- is 200-500 mg/L, and COD is 200-250 mg/L.
Preferably, in the step S3, the components and mass fractions of the secondary slurry are as follows: 40-60% of water, 25-38% of calcium sulfate, 8-15% of calcium fluoride, 0.5-1% of calcium phosphate and 5-10% of other impurities.
Preferably, in the step S5, the solid phosphogypsum comprises the following components in mass percent: 20-30% of water, 65-75% of calcium sulfate, 0.5-1.5% of fluoride, 0.5-1.5% of total phosphorus and 5-10% of other impurities.
Preferably, in the step S5, the mass fraction of the fluorosilicic acid solution after water absorption is 10-15%.
Preferably, in the step S5, the mass fraction of phosphoric acid in the concentrated acid is more than or equal to 46%, and the solid content is less than or equal to 4%.
In the step S1, the reaction material is one or more of Ca (OH) 2、CaO、CaCO3.
In the step S1, the sodium fluosilicate sewage is prepared by the following steps of: reaction material=1:1.5 to 2.5.
The heating temperature in the step S1 is 35-45 ℃, the reaction time is 3-4 hours, and the stirring speed is 1-9 rpm.
Preferably, the mixture precipitation time in the step S1 is 7-9 hours.
And the pressure filtration pressure of the sludge in the step S2 is 0.4-0.5 mpa, the pressure filtration time is 2-4h, and the stirring speed is 1-9 rpm.
In the step S3, the water amount is calculated according to the mass ratio: filter material=0.5-2:1, and the water content of primary slurry is 50-60%.
In the step S3, the pressure of primary slurry filter pressing is 0.4-0.5 mpa, and the filter pressing time is 2-4h.
In the step S4, the secondary slurry is prepared by mass ratio: concentrate: sulfuric acid = 0.5-1%:1.3:1.
Preferably, in the step S4, the stirring speed is 1 to 9rpm.
Preferably, the concentrate P 2O5 in step S4 has a grade of 31.5%.
In the step S5, the gas phase mixture is HF and SiF 4.
Preferably, the water spraying density in the step S5 is 25-50m 3/m2 h, and the heating temperature is 20-40 ℃.
Preferably, the temperature of the dilute acid concentration in the step S5 is 80.5+/-5.5 ℃, and the concentration vacuum pressure is-85+/-4 kPa.
The sludge treatment system comprises a sodium fluosilicate sewage tank, a slaked lime tank, a sewage regulating tank, a sludge sedimentation tank, a sludge primary filter press dehydrator, a sludge primary repulping tank, a sludge secondary filter press, a sludge secondary repulping tank, a phosphoric acid concentrate tank, a phosphoric acid reaction tank, a slag acid separation device, a dilute acid concentration device and a fluosilicic acid storage tank;
the water outlet of the sodium fluosilicate sewage tank is connected with the inlet of the sewage regulating tank; the outlet of the slaked lime tank is connected with the inlet of the sewage regulating tank; the sludge outlet of the sewage regulating tank is connected with the inlet of the sludge sedimentation tank; the solid phase outlet of the sludge sedimentation tank is connected with a sludge primary filter press dehydrator; the solid phase outlet of the sludge primary filter pressing dehydrator is connected with a sludge primary reslurry tank; the sludge primary re-slurry tank is connected with a sludge secondary filter press; the sludge secondary filter press is connected with a sludge secondary reslurry tank; the sludge secondary reslurry tank is connected with a phosphate concentrate tank; the phosphoric acid concentrate tank is connected with the phosphoric acid reaction tank; the sulfuric acid tank is connected with a phosphoric acid reaction tank; the gas phase outlet in the phosphoric acid reaction tank is connected with a fluosilicic acid storage tank; the liquid phase outlet in the phosphoric acid reaction tank is connected with a slag acid separation device; the liquid phase outlet of the slag acid separation device is connected with a dilute acid concentration inlet; the fluosilicic acid outlet of the dilute acid concentration device is connected with a fluosilicic acid storage tank.
Preferably, a liquid phase outlet of the sludge sedimentation tank is connected with a sodium fluosilicate sewage treatment device.
Preferably, a liquid phase outlet of the sludge primary filter press dehydrator is connected with a sewage regulating tank.
Preferably, the primary repulping water supplementing tank is connected with the inlet of the sludge primary repulping tank.
Preferably, the liquid phase outlet of the sludge secondary filter press is connected with the inlet of the sewage regulating tank and the inlet of the sludge primary repulping tank.
Preferably, the phosphoric acid secondary repulping water tank is connected with a sludge secondary repulping tank.
Preferably, the solid phase outlet of the slag acid separation device is connected with the phosphogypsum tank.
Preferably, the phosphoric acid outlet after the dilute acid concentration device is connected with a phosphoric acid storage tank.
Preferably, a dilute phosphoric acid storage tank is connected between the liquid phase outlet of the slag acid separation device and the inlet of the dilute acid concentration device.
Preferably, a fluorine absorption device is connected between the gas phase outlet in the phosphoric acid reaction tank and the fluosilicic acid storage tank.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the method for treating sludge in sodium fluosilicate wastewater, the concentration of the recovered fluosilicic acid is more than or equal to 10%, the fluorine recovery rate is more than 80%, and dangerous waste calcium fluoride in the sludge is converted into solid waste calcium sulfate, so that the environmental protection risk is eliminated.
2. The invention recovers fluorine and phosphorus elements in the sludge and reduces the production cost.
3. After the existing sodium fluosilicate wastewater is defluorinated and dephosphorized, the sludge containing calcium fluoride, calcium phosphate and calcium sulfate is subjected to water washing, slurry re-treatment and the like and then is sent back to a reaction tank of a phosphorus chemical device, fluorine and phosphorus elements in the sludge are recovered, and after hazardous waste calcium fluoride is eliminated, sludge residues and phosphogypsum residues are returned to a slag yard.
Drawings
FIG. 1 is a process diagram of the treatment of sludge in sodium fluorosilicate wastewater;
FIG. 2 is a block diagram of an apparatus for a sludge system in sodium fluorosilicate wastewater;
Reference numerals: the device comprises a sodium fluosilicate sewage tank 1, a slaked lime tank 2, a sewage regulating tank 3, a sludge sedimentation tank 4, a sodium fluosilicate sewage treatment device 5, a sludge primary filter press dehydrator 6, a sludge primary repulping tank 7, a primary repulping water supplementing tank 8, a sludge secondary filter press 9, a sludge secondary repulping tank 10, a phosphoric acid secondary repulping water tank 11, a phosphoric acid concentrate tank 12, a phosphoric acid reaction tank 13, a fluorine absorption device 14, a slag acid separation device 15, an phosphogypsum tank 16, a dilute phosphoric acid storage tank 17, a dilute acid concentration device 18, a phosphoric acid storage tank 19, a fluosilicic acid storage tank 20 and a sulfuric acid tank 21.
Detailed Description
For a further understanding of the invention and its features, examples of the invention are set forth to illustrate, but are not to be construed as limiting the scope of the invention.
As shown in fig. 2, the sludge treatment system in sodium fluosilicate wastewater comprises a sodium fluosilicate sewage tank 1, a slaked lime tank 2, a sewage regulating tank 3, a sludge sedimentation tank 4, a sodium fluosilicate sewage treatment device 5, a sludge primary filter press dehydrator 6, a sludge primary repulping tank 7, a primary repulping water supplementing tank 8, a sludge secondary filter press 9, a sludge secondary repulping tank 10, a phosphoric acid secondary repulping water tank 11, a phosphoric acid concentrate tank 12, a phosphoric acid reaction tank 13, a fluorine absorption device 14, a slag acid separation device 15, a phosphogypsum tank 16, a dilute phosphoric acid storage tank 17, a dilute acid concentration device 18, a phosphoric acid storage tank 19, a fluosilicic acid storage tank 20 and a sulfuric acid tank 21.
Adding sewage in a sodium fluosilicate sewage tank 1 and Ca (OH) 2 in a slaked lime tank 2 into a sewage regulating tank 3, reacting to generate a mixture of calcium fluoride, calcium phosphate and calcium sulfate, conveying the mixture into a sludge sedimentation tank 4 through an outlet of the sewage regulating tank 3, and obtaining sludge and wastewater from which fluorine and phosphorus are removed after the sludge sedimentation tank 4 is subjected to sedimentation; the wastewater from which fluorine and phosphorus are removed enters a sodium fluosilicate sewage treatment device 5 for subsequent treatment through a liquid phase outlet of a sludge sedimentation tank 4.
The sludge enters a sludge primary filter press dehydrator 6 from a solid phase outlet of a sludge sedimentation tank 4, the sludge primary filter press dehydrator 6 is used for filter pressing and dehydrating the sludge to obtain filter pressing primary sludge, and the filter pressing primary sludge is sent into a sludge primary reslurry tank 7 to be stirred into filter materials.
And the primary filter-pressing filtrate filtered by the primary filter-pressing dehydrator 6 of the sludge enters the sewage regulating tank 3 through the liquid phase outlet for recycling. The filter material in the sludge primary repulping tank 7 and the water in the primary repulping water supplementing tank 8 are stirred to obtain primary slurry, and the primary slurry is sent into the sludge secondary filter press 9.
After the primary slurry in the sludge secondary filter press 9 is subjected to filter pressing, filter-pressed secondary sludge is obtained, and then the filter-pressed secondary sludge is sent into a sludge secondary reslurry tank 10 through a solid phase outlet of the sludge secondary filter press 9, and the filter-pressed secondary sludge is fully reslurried with water in a phosphoric acid secondary reslurry water tank 11 in the sludge secondary reslurry tank 10, so that secondary slurry is obtained.
The secondary pressure filtration filtrate filtered by the pressure filtration of the sludge secondary pressure filter 9 is returned to the sewage regulating tank 3 and the sludge primary repulping tank 7; the secondary slurry is sent into a phosphate concentrate tank 12, mixed with concentrate in the phosphate concentrate tank 12, fully stirred in the phosphate concentrate tank 12, sent into a phosphoric acid reaction tank 13, and sent into the phosphoric acid reaction tank 13 for reaction through a sulfuric acid tank 21.
The calcium fluoride reacts with sulfuric acid to generate hydrogen fluoride and calcium sulfate, part of generated hydrogen fluoride enters a gas phase to become hydrogen fluoride gas, and the other part of hydrogen fluoride is dissolved in liquid-phase phosphoric acid to become liquid; the calcium phosphate can react with sulfuric acid to generate phosphoric acid, so that phosphorus recovery is realized. After the reaction, the vapor phase hydrogen fluoride generated in the phosphoric acid reaction tank 13 enters the fluorine absorber 14, reacts with silicon tetrafluoride, water, and the like in the fluorine absorber 14 to generate fluosilicic acid, and the fluosilicic acid is returned to the fluosilicic acid tank 20. The fluorine absorption device 14 adopts spray countercurrent absorption, the absorption solvent in the device is water, and the solute is hydrogen fluoride and silicon tetrafluoride. The liquid phase generated in the phosphoric acid reaction tank 13 enters a slag acid separation device 15, the liquid separated by the slag acid separation device 15 enters a dilute phosphoric acid storage tank 17, and the solid phosphogypsum tank 16 separated by the slag acid separation device 15 is sent to a gypsum temporary storage field. The dilute phosphoric acid storage tank 17 is conveyed to a dilute acid concentration device 18 to concentrate phosphoric acid to obtain concentrated acid. During the phosphoric acid concentration process, part of fluosilicic acid in the phosphoric acid solution is decomposed into SiF 4 and HF and escapes into steam; the SiF 4 that escapes from the flash chamber is absorbed by the fluorine absorber 14 with water to become H 2SiF6, and the SiO 2 hydrate is precipitated. The concentrated acid enters a phosphoric acid storage tank 19, and the fluosilicic acid separated by the dilute acid concentration device 18 enters a fluosilicic acid storage tank 20 through the fluorine absorption device 14.
The treatment process diagram of sludge in sodium fluosilicate wastewater is shown in fig. 1, and the alternative scheme of the patent is as follows:
scheme 1, the sludge in this patent may not be limited to the rephosphoric acid concentrate tank, but may also be directly fed into the phosphoric acid reaction tank.
Scheme 2, mud washing filter-pressing in this patent can not be limited to the secondary, can carry out the multistage filter-pressing of many times reslurry according to actual conditions.
The main components and the contents of sodium fluosilicate wastewater in the sodium fluosilicate wastewater tank 1 are shown in table 1:
NH 3 -N is the nitrogen content of ammonia in the wastewater; TP is the total phosphorus content in the wastewater, and TN is the total nitrogen content in the wastewater.
TABLE 1 sodium fluosilicate wastewater main component list
Example 1
The sludge treatment method of the embodiment comprises the following steps:
Step (1), the ratio of the sewage in the sodium fluosilicate sewage tank 1 to the reaction material Ca (OH) 2 in the slaked lime tank 2 is 1:1.5 after the wastewater is added into the wastewater regulating tank 3, the temperature of the wastewater regulating tank 3 is controlled to be 40 ℃, the reaction time is controlled to be 4 hours, the stirring speed is controlled to be 1rpm, stirring is continuously carried out, after full reaction, a mixture of calcium fluoride, calcium phosphate and calcium sulfate is generated, the mixture is conveyed into the sludge sedimentation tank 4 through an outlet of the wastewater regulating tank 3, after 8 hours of sedimentation, the sludge and wastewater with fluorine and phosphorus removed are obtained, the wastewater with fluorine and phosphorus removed enters the sodium fluosilicate wastewater treatment device 5 through a liquid phase outlet of the sludge sedimentation tank 4, and the main components of the wastewater with fluorine and phosphorus removed are shown in table 2.
Step (2), the sludge enters a primary sludge press-filtering dehydrator 6 from a solid phase outlet of a sludge sedimentation tank 4, the primary sludge is press-filtered and dehydrated by the primary sludge press-filtering dehydrator 6 under the pressure of 0.4-0.5 mpa for 2-4h, primary sludge is press-filtered and dehydrated, the primary sludge is sent into a primary sludge reslurry tank 7 to be stirred into a filter material, and the main components of the filter material are shown in table 3:
And the primary filter-pressing filtrate filtered by the primary filter-pressing dehydrator 6 of the sludge enters the sewage regulating tank 3 through the liquid phase outlet for recycling. The main components of the filtrate obtained by the primary pressure filtration are shown in Table 4.
The filter material in the sludge primary reslurry tank 7 and the water in the primary reslurry water supplementing tank 8 are continuously stirred at the stirring speed of 2rpm according to the water consumption which is 0.5-1 time of the mass of the filter material, so as to obtain primary slurry with the water content of 50-60%, and the primary slurry is sent into the sludge secondary filter press 9.
Step (3), after the primary slurry in the sludge secondary filter press 9 is fed at the feeding pressure of 0.4-0.5Mpa and the filter pressing time of 2-4h, obtaining filter pressing secondary sludge, then sending the filter pressing secondary sludge into a sludge secondary reslurry tank 10 through a solid phase outlet of the sludge secondary filter press 9, reslurrying the filter pressing secondary sludge in the sludge secondary reslurry tank 10 and water in a phosphoric acid secondary reslurry water tank 11, wherein the water ratio of the filter pressing secondary sludge to the phosphoric acid secondary reslurry water tank 11 is 2 in terms of mass ratio: 3, stirring at a stirring rate of 2rpm, continuously stirring, and fully reslurrying to obtain secondary slurry. The main components of the secondary slurry are shown in table 5.
The secondary pressure filtration filtrate filtered by the pressure filtration of the sludge secondary pressure filter 9 is returned to the sewage regulating tank 3 and the sludge primary repulping tank 7; the main components of the secondary pressure filtration filtrate are shown in table 6.
And (4) delivering the secondary slurry into a phosphate concentrate tank 12, mixing the secondary slurry with concentrate in the phosphate concentrate tank 12, and continuously stirring at a stirring speed of 2rpm in the phosphate concentrate tank 12, wherein the solid content of the concentrate slurry is more than 65%, and the grade of concentrate P 2O5 is 31.5%.
After sufficient stirring, the mixture was fed into the phosphoric acid reaction tank 13, and sulfuric acid was fed into the phosphoric acid reaction tank 13 through the sulfuric acid tank 21 to carry out a reaction. Wherein the temperature of the phosphoric acid reaction tank 13 is 70-85 ℃, the reaction time is 8h, and the mass ratio of the secondary slurry is as follows: concentrate: the mass ratio of the sulfuric acid is 0.5-1%:1.3:1.
The calcium fluoride reacts with sulfuric acid added into the sulfuric acid tank 21 to generate hydrogen fluoride and calcium sulfate, a part of generated hydrogen fluoride enters a gas phase to become hydrogen fluoride gas, and the other part of generated hydrogen fluoride is dissolved in liquid-phase phosphoric acid to become liquid; the calcium phosphate can react with sulfuric acid to generate phosphoric acid, so that phosphorus recovery is realized.
After the full reaction in the step (5), the gas phase hydrogen fluoride and silicon tetrafluoride generated in the phosphoric acid reaction tank 13 enter the fluorine absorption device 14, fluosilicic acid is generated after absorption in water in the fluorine absorption device 14, and then the fluosilicic acid returns to the fluosilicic acid storage tank 20.
The absorption solvent in the fluorine absorption device 14 is water, and the solute is hydrogen fluoride or silicon tetrafluoride. Adopting spray countercurrent absorption, controlling the circulation volume to control the spray density to be 25-50m 3/m2 & h, controlling the absorption temperature to be 20-35 ℃ and not more than 40 ℃ generally, and controlling the specific gravity of the fluosilicic acid solution to be more than 1.1 g/cm < 3 >; in the fluorine absorbing device 14, the mass fraction of the fluorosilicic acid solution in the water after absorbing the hydrogen fluoride and the silicon tetrafluoride is 10-15%.
Principle of fluorine absorption reaction: during phosphoric acid concentration, the fluosilicic acid in the phosphoric acid solution partially breaks down into SiF 4 and HF and escapes in the vapor: siF 4 and HF escaping from the flash chamber of H 2SiF6= SiF4 ++2HF +.The H 2SiF6 is produced when the SiF 4 and HF are absorbed by water introduced into the fluorine absorber.
The liquid phase generated in the phosphoric acid reaction tank 13 enters a slag acid separation device 15, the liquid separated by the slag acid separation device 15 enters a dilute phosphoric acid storage tank 17, and the solid phosphogypsum tank 16 separated by the slag acid separation device 15 is sent to a gypsum temporary storage field. The main components of phosphogypsum are shown in Table 7.
The dilute phosphoric acid storage tank 17 is conveyed to the dilute acid concentration device 18 to obtain concentrated acid, the temperature of the dilute acid concentration device 18 is 80.5+/-5.5 ℃, the concentration vacuum pressure is-85+/-4 kPa (the pressure represented by negative pressure), and the concentration reaction principle adopts a Stokes phosphoric acid concentration flow. According to the difference of boiling points of the dilute phosphoric acid solution under different pressures, indirect heating is adopted to boil and evaporate water in a vacuum state to concentrate the phosphoric acid.
The concentrated acid enters a phosphoric acid storage tank 19, the concentration of the concentrated acid in the phosphoric acid storage tank 19 is more than or equal to 46 percent (the concentration of the concentrated acid is phosphoric acid mass fraction), and the solid content is less than or equal to 4 percent; the separated fluosilicic acid enters into a fluosilicic acid storage tank 20, the fluosilicic acid concentration in the fluosilicic acid storage tank 20 is more than or equal to 10%, and the recovery rate of fluorine can reach 80%.
Example 2
Step (1), the mass ratio of the sewage in the sodium fluosilicate sewage tank 1 to the CaO in the reaction materials in the slaked lime tank 2 is 1:2, after the sewage is added into the sewage regulating tank 3, the temperature of the sewage regulating tank 3 is controlled to be 40 ℃, the reaction time is controlled to be 4 hours, the stirring speed is controlled to be 1rpm, stirring is continuously carried out, after the mixture is fully reacted, the mixture is generated into a mixture of calcium fluoride, calcium phosphate, calcium sulfate and the like, the mixture is conveyed into the sludge sedimentation tank 4 through an outlet of the sewage regulating tank 3, after 8 hours of sedimentation, the sludge and wastewater with fluorine and phosphorus removed are obtained, the wastewater with fluorine and phosphorus removed enters the sodium fluosilicate sewage treatment device 5 through a liquid phase outlet of the sludge sedimentation tank 4, and the main components of the wastewater with fluorine and phosphorus removed are shown in table 2.
And (2) the sludge enters a primary sludge press-filtering dehydrator 6 from a solid phase outlet of a sludge sedimentation tank 4, the press-filtering time is 2-4h under 0.4 mpa-0.5 mpa, the primary sludge is obtained after the sludge is press-filtered and dehydrated by the primary sludge press-filtering dehydrator 6, and the primary sludge is sent into a primary sludge reslurry tank 7 to be stirred into a filter material, wherein the main components and mass fractions of the filter material are shown in table 3.
And the primary filter-pressing filtrate filtered by the primary filter-pressing dehydrator 6 of the sludge enters the sewage regulating tank 3 through the liquid phase outlet for recycling. The main components of the primary filter pressing filtrate are shown in table 4:
The filter material in the sludge primary reslurry tank 7 and the water in the primary reslurry water supplementing tank 8 are continuously stirred at the stirring speed of 2rpm according to the water consumption which is 1-1.5 times of the mass of the filter material, so as to obtain primary slurry with the water content of 50% -6%, and the primary slurry is sent into the sludge secondary filter press 9.
Step (3), after the primary slurry in the sludge secondary filter press 9 is above 0.4-0.5Mpa and the filter pressing time is 2-4h, filter pressing secondary sludge is obtained, the filter pressing secondary sludge is sent into a sludge secondary reslurry tank 10 through a solid phase outlet of the sludge secondary filter press 9, the filter pressing secondary sludge is reslurried with water in a phosphoric acid secondary reslurry water tank 11 in the sludge secondary reslurry tank 10, and the water ratio of the filter pressing secondary sludge to the phosphoric acid secondary reslurry water tank 11 is 1 in terms of mass ratio: 2 stirring speed is 2rpm, stirring is continued, and secondary slurry is obtained after full reslurry. The main components and mass fractions of the secondary slurry are shown in table 5.
The secondary pressure filtration filtrate filtered by the pressure filtration of the sludge secondary pressure filter 9 is returned to the sewage regulating tank 3 and the sludge primary repulping tank 7; the main components of the secondary pressure filtration filtrate are shown in table 6.
And (4) delivering the secondary slurry into a phosphate concentrate tank 12, mixing the secondary slurry with concentrate in the phosphate concentrate tank 12, and continuously stirring at a stirring speed of 1rpm in the phosphate concentrate tank 12. Wherein the solid content of the concentrate slurry is more than 65%, and the grade of the concentrate P 2O5 is 31.5%.
After sufficient stirring, the mixture was fed into the phosphoric acid reaction tank 13, and sulfuric acid was fed into the phosphoric acid reaction tank 13 through the sulfuric acid tank 21 to carry out a reaction. Wherein the temperature of the phosphoric acid reaction tank 13 is 70-85 ℃, the reaction time is 8h, and the mass ratio of the secondary slurry is as follows: concentrate: mass ratio of sulfuric acid = 0.5-1%:1.3:1.
The calcium fluoride reacts with sulfuric acid added into the sulfuric acid tank 21 to generate hydrogen fluoride and calcium sulfate, a part of generated hydrogen fluoride enters a gas phase to become hydrogen fluoride gas, and the other part of generated hydrogen fluoride is dissolved in liquid-phase phosphoric acid to become liquid; the calcium phosphate can react with sulfuric acid to generate phosphoric acid, so that phosphorus recovery is realized.
After the full reaction in the step (5), the gas phase hydrogen fluoride and silicon tetrafluoride generated in the phosphoric acid reaction tank 13 enter the fluorine absorption device 14, fluosilicic acid is generated after absorption in water in the fluorine absorption device 14, and then the fluosilicic acid returns to the fluosilicic acid storage tank 20.
The absorption solvent in the fluorine absorption device 14 is water, and the solute is hydrogen fluoride or silicon tetrafluoride. Adopting spray countercurrent absorption, controlling the circulation volume to control the spray density to be 25-50m 3/m2 & h, controlling the absorption temperature to be 20-35 ℃ and not more than 40 ℃ generally, and controlling the specific gravity of the fluosilicic acid solution to be more than 1.1 g/cm < 3 >; in the fluorine absorbing device 14, the mass fraction of the fluosilicic acid solution after absorption is 10-15%.
The liquid phase generated in the phosphoric acid reaction tank 13 enters a slag acid separation device 15, the liquid separated by the slag acid separation device 15 enters a dilute phosphoric acid storage tank 17, and the solid phosphogypsum tank 16 separated by the slag acid separation device 15 is sent to a gypsum temporary storage field. The main components and contents of phosphogypsum are shown in Table 7.
The dilute phosphoric acid storage tank 17 is conveyed to the dilute acid concentration device 18 to obtain concentrated acid, the temperature of the dilute acid concentration device 18 is 80.5+/-5.5 ℃, and the concentration vacuum pressure is-85+/-4 kPa. Principle of fluorine absorption reaction: during phosphoric acid concentration, the fluosilicic acid in the phosphoric acid solution partially breaks down into SiF 4 and HF and escapes in the vapor: siF 4 and HF escaping from the flash chamber of H 2SiF6= SiF4 ++2HF +.The H 2SiF6 is produced when the SiF 4 and HF are absorbed by water introduced into the fluorine absorber.
The concentrated acid enters a phosphoric acid storage tank 19, the concentration of the concentrated acid in the phosphoric acid storage tank 19 is more than or equal to 46%, and the solid content is less than or equal to 4%; the separated fluosilicic acid enters into a fluosilicic acid storage tank 20, the fluosilicic acid concentration in the fluosilicic acid storage tank 20 is more than or equal to 10%, and the recovery rate of fluorine can reach 82%.
Example 3
Step (1), the mixture ratio of the sewage in the sodium fluosilicate sewage tank 1 and the reactant CaCO 3 in the slaked lime tank 2 is 1:2.5 ; after the wastewater is added into the wastewater regulating tank 3, the temperature of the wastewater regulating tank 3 is controlled to be 40 ℃, the reaction time is controlled to be 4 hours, the continuous stirring speed is controlled to be 1rpm, after the mixture is fully reacted, the mixture is conveyed into the sludge settling tank 4 through an outlet of the wastewater regulating tank 3, after 8 hours of settling, the sludge and wastewater with fluorine and phosphorus removed are obtained, the wastewater with fluorine and phosphorus removed enters the sodium fluosilicate wastewater treatment device 5 through a liquid phase outlet of the sludge settling tank 4, and the main components of the wastewater with fluorine and phosphorus removed are shown in table 2.
And (2) the sludge enters a primary sludge press-filtering dehydrator 6 from a solid phase outlet of a sludge sedimentation tank 4, the press-filtering time is 2-4h at more than 0.4 mpa-0.5 mpa, the primary sludge is obtained after the sludge is press-filtered and dehydrated by the primary sludge press-filtering dehydrator 6, and the primary sludge is sent into a primary sludge reslurry tank 7 to be stirred into a filter material, and the mass fractions of main components and each component of the filter material are shown in table 3.
And the primary filter-pressing filtrate filtered by the primary filter-pressing dehydrator 6 of the sludge enters the sewage regulating tank 3 through the liquid phase outlet for recycling. The main components of the primary press filtrate are shown in table 4.
The filter material in the sludge primary repulping tank 7 and the water in the primary repulping water supplementing tank 8 are continuously stirred at the stirring speed of 2rpm according to the water consumption which is 1.5-2 times of the mass of the filter material, so as to obtain primary slurry with the water content of 50% -60%, and the primary slurry is sent into the sludge secondary filter press 9.
Step (3), after the primary slurry in the sludge secondary filter press 9 is above 0.4-0.5Mpa and the filter pressing time is 2-4h, filter pressing secondary sludge is obtained, the filter pressing secondary sludge is sent into a sludge secondary reslurry tank 10 through a solid phase outlet of the sludge secondary filter press 9, the filter pressing secondary sludge is reslurried with water in a phosphoric acid secondary reslurry water tank 11 in the sludge secondary reslurry tank 10, and the water ratio of the filter pressing secondary sludge to the phosphoric acid secondary reslurry water tank 11 is 1 in terms of mass ratio: 2.5 stirring speed is 2rpm, stirring is continued, and secondary slurry is obtained after full reslurry. The mass fractions of the main components and the components of the secondary slurry are shown in table 5.
The secondary pressure filtration filtrate filtered by the pressure filtration of the sludge secondary pressure filter 9 is returned to the sewage regulating tank 3 and the sludge primary repulping tank 7; the main components and contents of the secondary pressure filtration filtrate are shown in Table 6.
And (4) delivering the secondary slurry into a phosphate concentrate tank 12, mixing the secondary slurry with concentrate in the phosphate concentrate tank 12, and continuously stirring at a stirring speed of 1rpm in the phosphate concentrate tank 12. Wherein the solid content of the concentrate slurry is more than 65%, and the grade of the concentrate P 2O5 is 31.5%.
After sufficient stirring, the mixture was fed into the phosphoric acid reaction tank 13, and sulfuric acid was fed into the phosphoric acid reaction tank 13 through the sulfuric acid tank 21 to carry out a reaction. Wherein the temperature of the phosphoric acid reaction tank 13 is 70-85 ℃, the reaction time is 8h, and the mass ratio of the secondary slurry is as follows: concentrate: the mass ratio of the sulfuric acid is 0.5-1%:1.3:1.
The calcium fluoride reacts with sulfuric acid added into the sulfuric acid tank 21 to generate hydrogen fluoride and calcium sulfate, a part of generated hydrogen fluoride enters a gas phase to become hydrogen fluoride gas, and the other part of generated hydrogen fluoride is dissolved in liquid-phase phosphoric acid to become liquid; the calcium phosphate can react with sulfuric acid to generate phosphoric acid, so that phosphorus recovery is realized.
After the full reaction in the step (5), the gas phase hydrogen fluoride and silicon tetrafluoride generated in the phosphoric acid reaction tank 13 enter the fluorine absorption device 14, fluosilicic acid is generated after absorption in water in the fluorine absorption device 14, and then the fluosilicic acid returns to the fluosilicic acid storage tank 20.
The absorption solvent in the fluorine absorption device 14 is water, and the solute is hydrogen fluoride or silicon tetrafluoride. Adopting spray countercurrent absorption, controlling the circulation volume to control the spray density to be 25-50m 3/m2 & h, controlling the absorption temperature to be 20-35 ℃ and not more than 40 ℃ generally, and controlling the specific gravity of the fluosilicic acid solution to be more than 1.1 g/cm < 3 >; in the fluorine absorbing device 14, the mass fraction of the fluosilicic acid solution after absorption is 10-15%.
The liquid phase generated in the phosphoric acid reaction tank 13 enters a slag acid separation device 15, the liquid separated by the slag acid separation device 15 enters a dilute phosphoric acid storage tank 17, and the solid phosphogypsum tank 16 separated by the slag acid separation device 15 is sent to a gypsum temporary storage field. The main components and contents of phosphogypsum are shown in Table 7.
The dilute phosphoric acid storage tank 17 is conveyed to the dilute acid concentration device 18 to obtain concentrated acid, the temperature of the dilute acid concentration device 18 is 80.5+/-5.5 ℃, and the concentration vacuum pressure is-85+/-4 kPa.
The concentrated acid enters a phosphoric acid storage tank 19, the mass fraction of phosphoric acid in the phosphoric acid storage tank 19 is more than or equal to 46%, and the solid content is less than or equal to 4%; the separated fluosilicic acid enters into a fluosilicic acid storage tank 20, the fluosilicic acid concentration in the fluosilicic acid storage tank 20 is more than or equal to 10%, and the recovery rate of fluorine can reach 85%.
TABLE 2 essential components of wastewater from which fluorine and phosphorus were removed
TABLE 3 Main component list of filter materials
TABLE 4 Primary Filter-pressing filtrate composition Table
TABLE 5 Primary composition of secondary slurry
TABLE 6 Table of the major Components of the filtrate from the secondary pressure filtration
TABLE 7 phosphogypsum main ingredient list
The embodiments described above are only some, but not all, of the embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Claims (10)
1. The sludge treatment method for sodium fluosilicate wastewater is characterized by comprising the following steps:
S1, adding sodium fluosilicate sewage into a reaction material, and then heating and stirring to react to obtain a mixture of calcium fluoride, calcium phosphate and calcium sulfate; precipitating and separating the mixture to obtain sludge and wastewater from which fluorine and phosphorus are removed;
s2, carrying out filter pressing on the sludge obtained in the step S1 to obtain primary filter-pressed sludge and primary filter-pressed filtrate, and stirring and repulping the primary filter-pressed sludge to obtain a filter material;
s3, supplementing water to the filter material obtained in the step S2 to obtain primary slurry, and performing filter pressing on the primary slurry to obtain filter-pressed secondary sludge and secondary filter liquor, wherein the secondary slurry is obtained by performing filter pressing on the secondary sludge, supplementing water and re-pulping;
S4, fully stirring and mixing the secondary slurry, concentrate and sulfuric acid obtained in the step S3, and fully reacting to obtain a gas-phase mixture and a liquid-phase mixture;
S5, heating the gas-phase mixture obtained in the step S4, and spraying and countercurrent absorbing water to obtain fluosilicic acid solution; separating slag acid of the liquid phase mixture to obtain dilute acid and solid phosphogypsum; concentrating the diluted acid to obtain the concentrated acid.
2. The method for treating sludge in sodium fluosilicate wastewater according to claim 1, wherein in the step S1, the reaction material is one or more of Ca (OH) 2、CaO、CaCO3.
3. The method for treating sludge in sodium fluosilicate wastewater according to claim 1, wherein in the step S1, the sodium fluosilicate wastewater is prepared by the following steps: reaction material=1:1.5 to 2.5.
4. The method for treating sludge in sodium fluosilicate wastewater according to claim 1, wherein the heating temperature in the step S1 is 35-45 ℃, the reaction time is 3-4 hours, and the stirring speed is 1-9 rpm.
5. The method for treating sludge in sodium fluosilicate wastewater according to claim 1, wherein the pressure filtration pressure of the sludge in the step S2 is 0.4 mpa-0.5 mpa, the pressure filtration time is 2-4h, and the stirring speed is 1-9 rpm.
6. The method for treating sludge in sodium fluosilicate wastewater according to claim 1, wherein in the step S3, the water amount is calculated by mass ratio: filter material=0.5-2:1, and the water content of primary slurry is 50-60%.
7. The method for treating sludge in sodium fluosilicate wastewater according to claim 1, wherein in the step S3, the primary slurry filter-pressing pressure is 0.4mpa to 0.5mpa, and the filter-pressing time is 2 to 4 hours.
8. The method for treating sludge in sodium fluosilicate wastewater according to claim 1, wherein in the step S4, the secondary slurry is prepared by the following mass ratio: concentrate: sulfuric acid = 0.5-1%:1.3:1.
9. The method for treating sludge in sodium fluosilicate wastewater according to claim 1, wherein in the step S5, the gas phase mixture is HF and SiF 4.
10. The sludge treatment system of the sludge treatment method in sodium fluosilicate wastewater according to claims 1-9, which is characterized by comprising a sodium fluosilicate sewage tank (1), a slaked lime tank (2), a sewage regulating tank (3), a sludge sedimentation tank (4), a sludge primary filter press dehydrator (6), a sludge primary repulping tank (7), a sludge secondary filter press (9), a sludge secondary repulping tank (10), a phosphoric acid concentrate tank (12), a phosphoric acid reaction tank (13), a slag acid separation device (15), a dilute acid concentration device (18) and a fluosilicic acid storage tank (20);
the water outlet of the sodium fluosilicate sewage tank (1) is connected with the inlet of the sewage regulating tank (3); the outlet of the slaked lime tank (2) is connected with the inlet of the sewage regulating tank (3); the sludge outlet of the sewage regulating tank (3) is connected with the inlet of the sludge sedimentation tank (4); the solid phase outlet of the sludge sedimentation tank (4) is connected with a sludge primary filter press dehydrator (6); the solid phase outlet of the sludge primary filter pressing dehydrator (6) is connected with a sludge primary reslurry tank (7); the sludge primary repulping tank (7) is connected with a sludge secondary filter press (9); the sludge secondary filter press (9) is connected with a sludge secondary reslurry tank (10); the sludge secondary reslurry tank (10) is connected with the phosphate concentrate tank (12); the phosphoric acid concentrate tank (12) is connected with the phosphoric acid reaction tank (13); the sulfuric acid tank (21) is connected with the phosphoric acid reaction tank (13); the gas phase outlet in the phosphoric acid reaction tank (13) is connected with a fluosilicic acid storage tank (20); the liquid phase outlet in the phosphoric acid reaction tank (13) is connected with a slag acid separation device (15); the liquid phase outlet of the slag acid separation device (15) is connected with the inlet of the dilute acid concentration (18); the fluosilicic acid outlet of the dilute acid concentration device (18) is connected with a fluosilicic acid storage tank (20) through a fluosilicic acid absorption device (14).
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