CN220090988U - Production line for recycling lithium hexafluorophosphate fluorine-containing tail gas - Google Patents
Production line for recycling lithium hexafluorophosphate fluorine-containing tail gas Download PDFInfo
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- CN220090988U CN220090988U CN202321704755.0U CN202321704755U CN220090988U CN 220090988 U CN220090988 U CN 220090988U CN 202321704755 U CN202321704755 U CN 202321704755U CN 220090988 U CN220090988 U CN 220090988U
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- -1 lithium hexafluorophosphate fluorine Chemical compound 0.000 title claims abstract description 23
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 21
- 238000004064 recycling Methods 0.000 title claims abstract description 13
- 238000005406 washing Methods 0.000 claims abstract description 118
- 239000007788 liquid Substances 0.000 claims abstract description 90
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 51
- 238000001704 evaporation Methods 0.000 claims abstract description 26
- 230000008020 evaporation Effects 0.000 claims abstract description 25
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 19
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 19
- 238000004065 wastewater treatment Methods 0.000 claims abstract description 17
- 238000005507 spraying Methods 0.000 claims abstract description 3
- 238000000926 separation method Methods 0.000 claims description 22
- 238000006243 chemical reaction Methods 0.000 claims description 20
- 239000012452 mother liquor Substances 0.000 claims description 16
- 239000007787 solid Substances 0.000 claims description 14
- 239000002562 thickening agent Substances 0.000 claims description 10
- 238000002425 crystallisation Methods 0.000 claims description 5
- 230000008025 crystallization Effects 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 5
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 4
- 238000004806 packaging method and process Methods 0.000 claims description 4
- 239000012295 chemical reaction liquid Substances 0.000 claims description 3
- 238000003860 storage Methods 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 2
- 239000012153 distilled water Substances 0.000 abstract description 3
- 239000000126 substance Substances 0.000 abstract description 3
- 239000002351 wastewater Substances 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 59
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 29
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 27
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 27
- 238000000034 method Methods 0.000 description 14
- 239000002912 waste gas Substances 0.000 description 10
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 7
- KEQGZUUPPQEDPF-UHFFFAOYSA-N 1,3-dichloro-5,5-dimethylimidazolidine-2,4-dione Chemical compound CC1(C)N(Cl)C(=O)N(Cl)C1=O KEQGZUUPPQEDPF-UHFFFAOYSA-N 0.000 description 6
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 6
- XTHPWXDJESJLNJ-UHFFFAOYSA-N chlorosulfonic acid Substances OS(Cl)(=O)=O XTHPWXDJESJLNJ-UHFFFAOYSA-N 0.000 description 6
- 238000007599 discharging Methods 0.000 description 6
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 description 6
- 229910017855 NH 4 F Inorganic materials 0.000 description 5
- 238000005457 optimization Methods 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 239000011575 calcium Substances 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- 235000019270 ammonium chloride Nutrition 0.000 description 3
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 3
- 229910001634 calcium fluoride Inorganic materials 0.000 description 3
- 239000001506 calcium phosphate Substances 0.000 description 3
- 229910000389 calcium phosphate Inorganic materials 0.000 description 3
- 235000011010 calcium phosphates Nutrition 0.000 description 3
- 239000000428 dust Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 238000005086 pumping Methods 0.000 description 3
- 231100000419 toxicity Toxicity 0.000 description 3
- 230000001988 toxicity Effects 0.000 description 3
- 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 description 3
- 239000004254 Ammonium phosphate Substances 0.000 description 2
- 229910004261 CaF 2 Inorganic materials 0.000 description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 238000003915 air pollution Methods 0.000 description 2
- 229910000148 ammonium phosphate Inorganic materials 0.000 description 2
- 235000019289 ammonium phosphates Nutrition 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- 239000003518 caustics Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000006115 defluorination reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000000110 cooling liquid Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 150000004673 fluoride salts Chemical class 0.000 description 1
- 238000003682 fluorination reaction Methods 0.000 description 1
- UQSQSQZYBQSBJZ-UHFFFAOYSA-N fluorosulfonic acid Chemical compound OS(F)(=O)=O UQSQSQZYBQSBJZ-UHFFFAOYSA-N 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000007794 irritation Effects 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 210000004400 mucous membrane Anatomy 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- OBCUTHMOOONNBS-UHFFFAOYSA-N phosphorus pentafluoride Chemical compound FP(F)(F)(F)F OBCUTHMOOONNBS-UHFFFAOYSA-N 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000012429 reaction media Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Abstract
The utility model relates to the technical field of chemical tail gas treatment, and particularly discloses a production line for recycling lithium hexafluorophosphate fluorine-containing tail gas, which comprises a tail gas treatment unit and a wastewater treatment unit, wherein the tail gas treatment unit comprises a primary alkaline washing tower, a secondary alkaline washing tower and a water washing tower, tail gas inlets are formed in the tops of the primary alkaline washing tower and the secondary alkaline washing tower, and tail gas outlets are formed in the bottoms of the primary alkaline washing tower and the secondary alkaline washing tower; the bottom of the water washing tower is provided with a buffer tank, the top of the buffer tank is provided with a tail gas inlet, water is accumulated in the buffer tank, the top of the water washing tank is provided with an exhaust fan, the primary alkaline washing tower and the secondary alkaline washing tower are internally provided with ammonia water spraying devices, washing liquid generated by washing the tail gas is pumped into a wastewater treatment unit, the tail gas treatment unit adopts a mode of two-stage ammonia water washing and one-stage water washing for treatment, washing liquid is recycled, and the use amount of the washing liquid is saved; the washing circulating liquid generated in the tail gas treatment unit is treated by adopting a wastewater treatment unit, the wastewater treatment unit is used for treating wastewater by adopting an MVR evaporation system, and hot steam and distilled water generated in the MVR evaporation system are recycled, so that the resource consumption of wastewater treatment is saved.
Description
Technical Field
The utility model relates to the technical field of chemical tail gas treatment, in particular to a production line for recycling lithium hexafluorophosphate fluorine-containing tail gas.
Background
The industrial production of lithium hexafluorophosphate mainly uses the method of hydrofluoric acid solvent, which is to dissolve lithium halide in anhydrous hydrogen fluoride and then introduce high-purity PF 5 And (3) reacting the gases to generate lithium hexafluorophosphate crystals, and separating and drying to obtain a lithium hexafluorophosphate product. In the process, a large amount of HF, HCl, PF is produced 5 The HF gas is a toxic gas with pungent smell; HCl is a colorless, irritating-smelling gas; PF (physical filter) 5 Colorless malodorous gas under normal temperature and pressure, which has strong irritation to skin, eyes and mucous membrane, and three tail gases are harmful to environment andthe human body is harmful, and the human body can be discharged after being treated. The method for treating the lithium hexafluorophosphate process tail gas mainly comprises the following steps: (1) The novel tail gas recovery device is designed, the novel tail gas recovery device comprises a heat exchanger, a dust remover and a water scrubber, wherein the heat exchanger comprises a heat exchanger outer shell and a heat exchanger inner shell, an exhaust gas inlet and an exhaust gas outlet are formed in the heat exchanger inner shell, cooling liquid is filled between the outer shell and the inner shell, the dust remover is connected with the exhaust gas outlet, the water scrubber is provided with a water scrubber inlet and a water scrubber outlet, and the water scrubber inlet is connected with the dust remover, so that the separation efficiency is high; however, the type of the equipment is more, the electric demister is connected with the water scrubber, and the corona wires are required to pass through direct-current high-voltage power of 45-48 kilovolts, so that the danger coefficient is higher.
(2) Absorbing phosphorus pentafluoride by adopting an organic solvent carbon tetrachloride or benzene; the chloride salt solution absorbs hydrogen fluoride in the tail gas and reacts to generate fluoride salt precipitate; the hydrogen chloride is subjected to multistage absorption by water to prepare industrial grade hydrochloric acid; the tail gas is comprehensively utilized, the separation efficiency is improved, but the obtained byproduct has lower fluorination quality, is difficult to remove by using an organic solvent and has certain toxicity.
(3) The hydrogen fluoride in the tail gas is absorbed by chlorosulfonic acid reaction, the hydrogen chloride in the tail gas is absorbed by sulfur trioxide to generate chlorosulfonic acid, the treatment device is a first-stage absorption tower, the inside of the treatment device adopts circulating liquid chlorosulfonic acid as a reaction medium to absorb HF, the second-stage absorption tower is a reaction container of sulfur trioxide and HCl, and the produced chlorosulfonic acid and fluorosulfonic acid are important chemical raw materials, so that the recycling of mixed acid is realized; however, chlorosulfonic acid and sulfur trioxide are introduced into the method as strong oxidants, and react with metals in humid air to corrode the metals, thereby compromising the utilization rate of equipment and causing leakage and toxicity.
In summary, in the existing mode for treating the tail gas containing fluorine of lithium hexafluorophosphate, the mode one has the problems of high equipment energy consumption and high potential safety hazard; the second mode has the problems that byproducts are difficult to treat and the solvent is used to have toxicity; the third mode has the problem that the used reagent has great loss to the equipment.
Disclosure of Invention
The utility model aims to provide a production line for recycling lithium hexafluorophosphate tail gas, which aims to solve the problems of high danger coefficient, large environmental pollution and large energy loss during recycling of lithium hexafluorophosphate tail gas.
In order to solve the problems, the technical scheme is as follows:
the production line comprises a tail gas treatment unit and a wastewater treatment unit, wherein the tail gas treatment unit comprises a primary alkaline washing tower, a secondary alkaline washing tower and a water washing tower, tail gas inlets are formed in the tops of the primary alkaline washing tower and the secondary alkaline washing tower, and tail gas outlets are formed in the bottoms of the primary alkaline washing tower and the secondary alkaline washing tower; a buffer tank is arranged at the bottom of the water washing tower, a tail gas inlet is arranged at the top of the buffer tank, water is accumulated in the buffer tank, an exhaust fan is arranged at the top of the water washing tank, ammonia water spraying devices are arranged in the primary alkaline washing tower and the secondary alkaline washing tower, and a washing liquid generated by washing the tail gas is pumped into a wastewater treatment unit.
The basic principle of the technical scheme is as follows: the tail gas of the lithium hexafluorophosphate device enters a first-stage alkaline washing tower from the top of the first-stage alkaline washing tower, and HF, HCl, PF in the tail gas is mainly discharged in the first-stage alkaline washing tower 5 Alkaline washing with ammonia water, wherein HF and HCl are neutralized with ammonia water to produce water, PF 5 React with water to generate phosphoric acid and hydrofluoric acid, and react with ammonia water to generate ammonium phosphate and NH 4 F, in the process, PF 5 All hydrolysis is carried out, and at this time, 79 percent of HF and about 90 percent of HCl in the tail gas can be removed; the waste gas of HF and HCl which are not completely absorbed by ammonia water in the primary alkaline washing tower enters the secondary alkaline washing tower through the tower of the secondary alkaline washing tower, and ammonia water is also adopted for further absorption, wherein HF and HCl react with ammonia water to generate NH 4 F and NH 4 Cl, HF and HCl are almost removed, the washing liquid is returned to the first-stage alkaline washing tower from the tower bottom, the washing circulating liquid produced in the first-stage alkaline washing tower is discharged into the wastewater treatment unit, and after two-stage alkaline washing, HF, HCl, PF in the tail gas 5 Basically absorbed, the waste gas after the two-stage alkali washing enters a water washing tower to be washed by tap water, so that a small amount of NH carried in the waste gas can be removed 3 Removing, and returning the washing liquid to the second-stage alkaline washing tower to make HF in the tail gas less than or equal to 9mg +.m3 and HCl are less than or equal to 100mg/m3, reach the discharge standard, and are discharged from the top of the water scrubber to the outside.
The beneficial effects of the technical scheme are that:
1. compared with the prior novel tail gas recovery equipment in which a water scrubber is connected with a high-risk electric demister, the technical scheme has the advantages that a large amount of HF and HCl gas in the tail gas is absorbed by two-stage alkaline washing, the water scrubber does not need to be connected with the electric demister, and the safety of the whole process is high;
2. compared with the existing method for removing the tail gas by adopting an organic solvent, the technical scheme adopts a mode of two-stage ammonia water washing and one-stage water washing to treat the tail gas, and HF, HCl, PF in the tail gas is firstly washed by alkali twice 5 Washing and absorbing, countercurrent absorption of tail gas and absorbing liquid, and taking the washing liquid of the second-stage alkaline washing as the absorbing liquid of the first-stage washing, thereby not only greatly saving the consumption of ammonia water, but also ensuring the recovery rate of hydrogen chloride in the tail gas to be more than 98 percent, and removing HF, HCl, PF by alkaline washing 5 Then absorbing and washing a small amount of NH in the tail gas by water 3 Ensuring that the tail gas reaches the standard and is discharged, and treating the tail gas or the generated wastewater by a special wastewater treatment unit;
3. compared with the existing method for treating tail gas by chlorosulfonic acid, the technical scheme adopts ammonia water which does not have strong oxidability, has small loss to equipment and prolongs the service life of the equipment.
The first preferred scheme is as follows: as a further optimization of the basic scheme, the wastewater treatment unit is sequentially connected with a reaction tank, a first centrifugal machine, an MVR evaporation system and a mother liquor tank, washing circulating liquid is discharged into the reaction tank to perform impurity removal reaction by using calcium chloride solution, reaction liquid in the reaction tank is discharged into the first centrifugal machine to perform solid-liquid separation, liquid after the solid-liquid separation is discharged into the MVR evaporation system, solids after the solid-liquid separation are subjected to two-stage water washing, primary mother liquor generated by the first-stage water washing is also discharged into the MVR evaporation system, and secondary mother liquor generated by the second-stage water washing is discharged into the mother liquor tank; the MVR evaporation system comprises a buffer tank, an MVR evaporator and a separator which are sequentially connected, wherein the buffer tank is used for converging liquid separated by the first centrifugal machine and mother liquid after separated solid water washing, liquid in the buffer tank is pumped to the MVR evaporator for evaporation and crystallization to form concentrated liquid, and the mother liquid tank is used for storing the mother liquid after solid-liquid separation of the concentrated liquid.
The first preferable scheme has the beneficial effects that: the main component of the washing circulating liquid is ammonium phosphate and NH 4 F、H 4 Cl, adopting calcium chloride to carry out defluorination and dephosphorization treatment on the washing circulating liquid, effectively removing fluorine and calcium in the circulating liquid, simultaneously and not introducing other ions, carrying out two-stage water washing on calcium fluoride and calcium phosphate after solid-liquid separation, wherein the chloride ion content is less than or equal to 100ppm, and finally, the solid water content of the calcium fluoride and the calcium phosphate is less than or equal to 15%, and directly sending the calcium fluoride and the calcium phosphate to a waste residue treatment unit; compared with the traditional technology that the concentrated liquid is directly subjected to centrifugal separation by adopting MVR evaporation, the temperature of the concentrated liquid is still higher, the solubility of ammonium chloride is increased along with the temperature rise, and compared with the material still containing a large amount of ammonium salt, the concentrated liquid still contains a significant separation effect after MVR evaporation, and the energy consumption is low.
And a second preferred scheme is as follows: as a further optimization of the first preferred scheme, the top end of the water scrubber is communicated with an exhaust fan, and the air outlet end of the exhaust fan is connected with a chimney.
The second preferred scheme has the beneficial effects that: the tail gas treated in the water scrubber can be rapidly pumped out from the chimney to be discharged outside through the exhaust fan.
And a preferred scheme III: as a further optimization of the second preferred aspect, a PH adjusting tank is arranged between the first centrifuge and the buffer tank, and the PH adjusting tank is used for adjusting the liquid separated by the first centrifuge.
The beneficial effects of the preferred scheme III are that: the ammonia water is contained in the liquid subjected to solid-liquid separation by the first centrifugal machine, the PH of the liquid is regulated to be 2-4 to be acidic, and the air pollution caused by volatilization of ammonia gas when the MVR evaporator performs evaporation concentration crystallization is avoided.
The preferable scheme is as follows: as a further optimization of the third preferred scheme, a preheater is arranged between a buffer tank and an MVR evaporator in the MVR evaporation system, a thickener is communicated behind the separator, a second centrifugal machine is communicated behind the thickener, a liquid outlet end of the second centrifugal machine is communicated with a mother liquor tank, and a solid outlet end of the second centrifugal machine is communicated with a dryer; the liquid in the buffer tank is preheated by the preheater and then discharged into the MVR evaporator for evaporation, concentration and crystallization, then enters the separator for solid-liquid separation, enters the thickener for concentration after separation and then is centrifuged by the centrifugal machine, the solid outlet end of the centrifugal machine is fixedly discharged into the dryer for drying and packaging, and the liquid at the liquid outlet end of the centrifugal machine is discharged into the mother liquid tank for storage.
The beneficial effects of the fourth preferred scheme are as follows: the liquid entering the MVR evaporator for evaporation and concentration is preheated by the preheater, so that the activity of the liquid is increased, the concentration of the liquid separated by the separator is improved by the thickener, and the follow-up centrifugal separation of the centrifugal machine is more thorough.
The preferable scheme is as follows: as a further optimization of the fourth preferred mode, the air outlet end of the MVR evaporator is communicated with a compressor, the temperature of the secondary steam generated at the air outlet end of the MVR evaporator is increased after the secondary steam is compressed by the compressor, and the secondary steam with the increased temperature flows back into the MVR evaporator to be used as a heat source of the evaporator.
The fifth preferred scheme has the beneficial effects that: the evaporator originally needs the secondary steam condensed by cooling water, the pressure and the saturation temperature of the secondary steam are increased after the secondary steam is compressed by a compressor, the enthalpy value is increased, and the secondary steam is sent into an evaporator heater to serve as a heat source to heat feed liquid, so that the latent heat of the secondary steam is utilized, which is equivalent to 10-effect evaporation, and compared with the traditional multi-effect evaporation, the secondary steam can save about 70% of standard coal.
Drawings
FIG. 1 is a schematic diagram of a production line according to an embodiment of the present utility model;
FIG. 2 is a schematic process flow diagram of an embodiment of the present utility model.
Reference numerals in the drawings of the specification include: the first stage caustic wash column 11, the second stage caustic wash column 12, the water wash column 13, the fan 14, the chimney 15, the reaction tank 21, the first centrifuge 22, the PH adjustment tank 23, the MVR evaporation system 24 (framed in dashed lines), the mother liquor tank 25, the dryer 26, the compressor 27, the surge tank 241, the preheater 242, the MVR evaporator 243, the separator 244, the thickener 245, and the second centrifuge 246.
Detailed Description
The following is a further detailed description of the embodiments:
an example is substantially as shown in figure 1:
the utility model provides a lithium hexafluorophosphate fluorine-containing tail gas recycle's production line, as shown in fig. 1, by tail gas treatment unit and waste water treatment unit constitution, tail gas treatment unit has first-level alkaline wash tower 11, second grade alkaline wash tower 12 and water scrubber 13 from left to right intercommunication in proper order, and water scrubber 13 top intercommunication has exhaust fan 14, and exhaust fan 14's air outlet end is connected with chimney 15. The bottom end of the primary alkaline washing tower 11 is communicated with a wastewater treatment unit.
The wastewater treatment unit is sequentially communicated with a reaction tank 21, a first centrifugal machine 22, a PH adjusting tank 23, an MVR evaporation system (shown by a broken line frame in figure 1) and a mother liquor tank 25 from left to right; the MVR evaporation system comprises a buffer tank 241, a preheater 242, an MVR evaporator 243, a separator 244, a thickener 245 and a second centrifuge 246 which are sequentially communicated from left to right, wherein the liquid outlet end of the second centrifuge 246 is communicated with the mother liquor tank 25, the solid outlet end of the second centrifuge 246 is communicated with a dryer 26, and the air outlet end of the MVR evaporator 243 is communicated with a compressor 27.
The specific implementation process is as follows:
as shown in fig. 2, the tail gas of the lithium hexafluorophosphate device is preheated to 20 ℃, enters the primary alkaline washing tower from the top of the primary alkaline washing tower (not shown in fig. 1) through a spray tower (not belonging to the production line), and HF, HCl, PF in the tail gas is mainly discharged from the primary alkaline washing tower 5 Alkaline washing with 10% ammonia water, during which PF is used 5 All hydrolysis is carried out, and at this time, 79 percent of HF and about 90 percent of HCl in the tail gas can be removed;
the method comprises the steps of enabling HF and HCl waste gas which are not completely absorbed by ammonia water in a primary alkaline washing tower to enter the secondary alkaline washing tower through the tower top of the secondary alkaline washing tower, further absorbing by 10% ammonia water, wherein HF and HCl are basically removed, washing liquid in the secondary alkaline washing tower is returned to the primary alkaline washing tower from the tower bottom, washing circulating liquid produced in the primary alkaline washing tower is discharged into a wastewater treatment unit, and HF, HCl, PF in tail gas is obtained after two-stage alkaline washing 5 Is substantially absorbed;
the waste gas after the two-stage alkaline washing is washed by tap water in a water washing tower, a small amount of NH3 carried in the waste gas can be removed, the washing liquid is returned to the two-stage alkaline washing tower, HF is less than or equal to 9mg/m3 and HCl is less than or equal to 100mg/m3 in the waste gas, the waste gas reaches the emission standard, and the exhaust fan rapidly pumps the waste gas treated in the water washing tower out of a chimney and discharges the waste gas to the outside.
The chemical reaction equation involved in the exhaust gas treatment process is as follows:
1、HF+NH 3 ·H 2 O＝NH 4 F+H 2 O
2、HCl+NH H O＝NH Cl+H O
3、PF 5 +4H 2 O＝H 3 PO 4 +5HF
4、H 3 PO 4 +3NH H O＝(NH 4 ) 3 PO 4 +3H O
as can be seen from the above reaction equation, the main component of the washing cycle is (NH) 4 ) 3 PO 4 、NH 4 F、NH 4 Pumping Cl and washing circulating liquid into a reaction tank through a diaphragm pump, adding 60% calcium chloride slurry into the reaction tank for defluorination and dephosphorization reaction, and adding PO in the washing circulating liquid 4 3- 、F - And (5) removing.
The chemical reaction equation involved in the treatment process of the washing circulating liquid is as follows:
1、2(NH 4 ) 3 PO 4 +3CaCl 2 →Ca 3 (PO 4 ) 2 +6NH 4 Cl
2、CaCl 2 +2NH 4 F→CaF 2 +2NH 3 .H 2 O
the reaction liquid in the reaction tank is discharged into a first centrifugal machine for solid-liquid separation, and the liquid separated by the first centrifugal machine contains NH as known from the reaction equation 3 .H 2 O, discharging the mixture into a PH adjusting tank to adjust the PH to 3, so as to avoid NH during subsequent evaporation 3 Volatilizing to cause air pollution; solids after separation by the first centrifuge (Cap-containing 2 And Ca 3 (PO 4 ) 2 ) Washing with distilled water in a water washing tank (not shown in FIG. 1) to obtain liquid with pH of 3, discharging into a buffer tank, pumping the liquid into a preheater, preheating to above 60deg.C, pumping preheated liquid into MVR evaporator, steamingConcentrating and crystallizing, recovering distilled water generated when the MVR evaporator is used for two-stage washing, evaporating and concentrating, cooling and crystallizing, enabling a solid-liquid mixture after cooling and crystallizing to enter a separator for solid-liquid separation, concentrating and lifting the concentration of the separated liquid in a thickener, discharging the separated solid into a dryer for drying and packaging, centrifuging the concentrated and lifted concentration liquid through a second centrifugal machine, discharging ammonium chloride solid at the solid outlet end of the second centrifugal machine into the dryer for drying and packaging, and discharging ammonium chloride meeting the industrial grade standard of qualified products in the specification GB/T2946-2018, wherein the liquid at the liquid outlet end of the second centrifugal machine is discharged into a mother liquid tank for storage.
The primary mother liquor from the first water wash is also discharged into a buffer tank and treated as described above with a liquid having a pH of 3.
Discharging the second-stage mother liquor generated by the second-stage water washing into a mother liquor tank to generate CaF 2 .Ca 3 (PO 4 ) 2 Recycling and selling.
The production line adopts a mode of two-stage dilute ammonia water washing and one-stage water washing to treat the tail gas, and HF, HCl, PF in the tail gas is firstly washed by alkali twice 5 Washing and absorbing, countercurrent absorption of tail gas and absorbing liquid, and taking the washing liquid of the second-stage alkaline washing as the absorbing liquid of the first-stage washing, thereby not only greatly saving the consumption of ammonia water, but also ensuring the recovery rate of hydrogen chloride in the tail gas to be more than 98 percent, and removing HF, HCl, PF by alkaline washing 5 Then absorbing and washing a small amount of NH in the tail gas by water 3 Ensuring that the tail gas reaches the standard and is discharged.
The foregoing is merely exemplary embodiments of the present utility model, and specific structures and features that are well known in the art are not described in detail herein. It should be noted that modifications and improvements can be made by those skilled in the art without departing from the structure of the present utility model, and these should also be considered as the scope of the present utility model, which does not affect the effect of the implementation of the present utility model and the utility of the patent. The protection scope of the present utility model is subject to the content of the claims, and the description of the specific embodiments and the like in the specification can be used for explaining the content of the claims.
Claims (6)
1. The utility model provides a lithium hexafluorophosphate fluorine-containing tail gas recycle's production line, includes tail gas treatment unit and wastewater treatment unit, its characterized in that: the tail gas treatment unit comprises a first-stage alkaline washing tower, a second-stage alkaline washing tower and a water washing tower, wherein the top parts of the first-stage alkaline washing tower and the second-stage alkaline washing tower are provided with tail gas inlets, and the bottoms of the first-stage alkaline washing tower and the second-stage alkaline washing tower are provided with tail gas outlets; a buffer tank is arranged at the bottom of the water washing tower, a tail gas inlet is arranged at the top of the buffer tank, water is accumulated in the buffer tank, an exhaust fan is arranged at the top of the water washing tank, ammonia water spraying devices are arranged in the primary alkaline washing tower and the secondary alkaline washing tower, and a washing liquid generated by washing the tail gas is pumped into a wastewater treatment unit.
2. The production line for recycling lithium hexafluorophosphate tail gas according to claim 1, wherein the production line comprises the following steps: the wastewater treatment unit is sequentially connected with a reaction tank, a first centrifugal machine, an MVR evaporation system and a mother liquor tank, washing circulating liquid is discharged into the reaction tank to perform impurity removal reaction by using calcium chloride solution, reaction liquid in the reaction tank is discharged into the first centrifugal machine to perform solid-liquid separation, liquid after the solid-liquid separation is discharged into the MVR evaporation system, solids after the solid-liquid separation are subjected to two-stage washing, primary mother liquor generated by the first-stage washing is also discharged into the MVR evaporation system, and secondary mother liquor generated by the second-stage washing is discharged into the mother liquor tank; the MVR evaporation system comprises a buffer tank, an MVR evaporator and a separator which are sequentially communicated from left to right, wherein the buffer tank is used for converging liquid separated by the first centrifugal machine and mother liquid after separated solid water washing, liquid in the buffer tank is pumped to the MVR evaporator for evaporative crystallization to form concentrated liquid, and the mother liquid tank is used for storing the mother liquid after solid-liquid separation of the concentrated liquid.
3. The production line for recycling lithium hexafluorophosphate tail gas according to claim 1, wherein the production line comprises the following steps: the top end of the water washing tower is communicated with an exhaust fan, and the air outlet end of the exhaust fan is connected with a chimney.
4. The production line for recycling lithium hexafluorophosphate tail gas according to claim 2, wherein the production line comprises the following steps: and a PH adjusting tank is arranged between the first centrifugal machine and the buffer tank and is used for adjusting the liquid separated by the first centrifugal machine.
5. The production line for recycling lithium hexafluorophosphate tail gas according to claim 2, wherein the production line comprises the following steps: a preheater is arranged between the buffer tank and the MVR evaporator in the MVR evaporation system, a thickener is communicated behind the separator, a second centrifugal machine is communicated behind the thickener, a liquid outlet end of the second centrifugal machine is communicated with the mother liquor tank, and a solid outlet end of the second centrifugal machine is communicated with a dryer; the liquid in the buffer tank is preheated by the preheater and then discharged into the MVR evaporator for evaporation, concentration and crystallization, then enters the separator for solid-liquid separation, enters the thickener for concentration after separation and then is centrifuged by the centrifugal machine, the solid outlet end of the centrifugal machine is fixedly discharged into the dryer for drying and packaging, and the liquid at the liquid outlet end of the centrifugal machine is discharged into the mother liquid tank for storage.
6. The production line for recycling lithium hexafluorophosphate tail gas according to claim 5, wherein the production line comprises: the air outlet end of the MVR evaporator is communicated with a compressor, the temperature of the secondary steam generated at the air outlet end of the MVR evaporator is increased after the secondary steam is compressed by the compressor, and the secondary steam with the increased temperature flows back into the MVR evaporator to be used as a heat source of the evaporator.
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