CN108467049B - System for retrieve ammonia in follow tombarthite separation waste liquid - Google Patents
System for retrieve ammonia in follow tombarthite separation waste liquid Download PDFInfo
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- CN108467049B CN108467049B CN201810577493.3A CN201810577493A CN108467049B CN 108467049 B CN108467049 B CN 108467049B CN 201810577493 A CN201810577493 A CN 201810577493A CN 108467049 B CN108467049 B CN 108467049B
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 355
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 156
- 239000007788 liquid Substances 0.000 title claims abstract description 68
- 239000002699 waste material Substances 0.000 title claims abstract description 56
- 238000000926 separation method Methods 0.000 title claims abstract description 42
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 120
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 120
- 238000006243 chemical reaction Methods 0.000 claims abstract description 65
- 239000000463 material Substances 0.000 claims abstract description 59
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 28
- 150000002910 rare earth metals Chemical class 0.000 claims abstract description 27
- 238000004064 recycling Methods 0.000 claims abstract description 18
- 238000010521 absorption reaction Methods 0.000 claims description 90
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 83
- 238000001704 evaporation Methods 0.000 claims description 44
- 230000008020 evaporation Effects 0.000 claims description 43
- 239000000292 calcium oxide Substances 0.000 claims description 41
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 41
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 40
- 230000007704 transition Effects 0.000 claims description 31
- 238000001816 cooling Methods 0.000 claims description 29
- 239000007921 spray Substances 0.000 claims description 25
- 239000011344 liquid material Substances 0.000 claims description 15
- 239000012530 fluid Substances 0.000 claims description 12
- 230000000087 stabilizing effect Effects 0.000 claims description 5
- 238000000034 method Methods 0.000 abstract description 34
- 238000011084 recovery Methods 0.000 abstract description 28
- 239000002351 wastewater Substances 0.000 abstract description 20
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 abstract description 8
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 166
- 239000000243 solution Substances 0.000 description 106
- 235000019270 ammonium chloride Nutrition 0.000 description 83
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 48
- 239000001110 calcium chloride Substances 0.000 description 48
- 229910001628 calcium chloride Inorganic materials 0.000 description 48
- 239000002893 slag Substances 0.000 description 28
- 239000011259 mixed solution Substances 0.000 description 22
- 208000028659 discharge Diseases 0.000 description 17
- 238000005086 pumping Methods 0.000 description 14
- 230000000694 effects Effects 0.000 description 12
- 230000008569 process Effects 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 9
- 238000005507 spraying Methods 0.000 description 9
- 238000003756 stirring Methods 0.000 description 9
- 239000012141 concentrate Substances 0.000 description 8
- 230000009467 reduction Effects 0.000 description 6
- 238000004821 distillation Methods 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 239000002912 waste gas Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- 238000006073 displacement reaction Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000006467 substitution reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 230000036632 reaction speed Effects 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 2
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 2
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 2
- 239000001099 ammonium carbonate Substances 0.000 description 2
- -1 ammonium ions Chemical class 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000004134 energy conservation Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 238000012797 qualification Methods 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000003541 multi-stage reaction Methods 0.000 description 1
- 238000007127 saponification reaction Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/02—Preparation, purification or separation of ammonia
- C01C1/022—Preparation of aqueous ammonia solutions, i.e. ammonia water
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/02—Preparation, purification or separation of ammonia
- C01C1/026—Preparation of ammonia from inorganic compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Treating Waste Gases (AREA)
- Removal Of Specific Substances (AREA)
Abstract
The invention discloses a system for recycling ammonia from rare earth separation waste liquid, which comprises a solution tank I, an energy-saving concentrator, a solution tank II and the like; the solution outlet of the solution tank I is connected with the material concentration inlet of the energy-saving concentrator through a pipeline, the material concentration outlet of the energy-saving concentrator is connected with the solution inlet of the solution tank II through a pipeline, and the solution outlet of the solution tank II is connected with the material inlet of the reaction tank through a pipeline. The ammonia is recovered by the system, so that the recovery rate of the ammonia is more than or equal to 99.5%, the concentration of the finally obtained ammonia water reaches 8.0-10.0mol/L, and the recovery is efficient and thorough; meanwhile, the ammonia nitrogen content in the wastewater finally discharged by the method is less than or equal to 5.0ppm and is far less than 15.0ppm of the national first-level discharge standard, so that low discharge and low pollution are realized; in addition, the method is used for operation, and the consumption of the steam only needs 0.8-1.0 ton/ton of ammonia water, so that the steam amount required for operation is greatly saved, and the energy is saved.
Description
Technical Field
The invention belongs to the field of rare earth separation resource recovery, and particularly relates to a system for recovering ammonia from rare earth separation waste liquid.
Background
China is a large country for producing rare earth, the annual rare earth yield exceeds 25 ten thousand tons, and the exploitation and processing amounts are huge. In the existing rare earth wet separation process, ammonia water saponification and ammonium bicarbonate precipitation are generally adopted in the rare earth extraction and rare earth precipitation process sections respectively, wherein the used ammonia water and ammonium bicarbonate auxiliary materials cause the waste liquid after rare earth element separation to contain ammonium chloride, and the waste liquid is a source of ammonia nitrogen pollution in the rare earth separation waste liquid. The waste liquid discharge causes serious environmental pollution and causes huge resource loss because a large amount of ammonia is wasted, so that the recovery of ammonia in the rare earth separation waste liquid has important significance.
At present, the methods for recovering ammonia in rare earth separation waste liquid mainly comprise the following steps. A method for recovering ammonium chloride as described in the patent application publication No. CN1224694A, which is to recover ammonium chloride by direct concentration, evaporation and crystallization, but the method has not been popularized because of the low concentration of ammonium chloride in the waste liquid, which results in high processing cost; a recycling method as described in the patent application publication No. CN1504413A is to add a recycling agent into an ammonium chloride solution to recycle ammonia water and hydrochloric acid by evaporation, but the recycling method is not industrially applied because the concentration of the recycled ammonia water and hydrochloric acid is too low and has no value; in addition, the patent document with publication number of CN101475194B also discloses a method for recovering ammonia from low-concentration ammonium chloride wastewater, which is to add alkaline substances into the low-concentration ammonium chloride wastewater so as to generate ammonia water and chloride salt, and then separate and concentrate the ammonia water to obtain the ammonia water with use value.
Aiming at the problems, the problems are difficult to be solved well under the existing conditions, so that breakthrough improvement on the recovery process of ammonia in the rare earth industrial waste liquid is needed.
Disclosure of Invention
(1) Technical problem to be solved
Aiming at the defects existing in the prior art, the invention provides a high-efficiency energy-saving environment-friendly system for recycling ammonia from rare earth separation waste liquid, the ammonia is recycled through the system, the recycling rate of the ammonia is more than or equal to 99.5%, the concentration of finally obtained ammonia water reaches 8.0-10.0mol/L, and the recycling is efficient and thorough; meanwhile, the ammonia nitrogen content in the wastewater finally discharged by the method is less than or equal to 5.0ppm and is far less than 15.0ppm of the national first-level discharge standard, so that low discharge and low pollution are realized; in addition, the method is used for operation, and the consumption of the steam only needs 0.8-1.0 ton/ton of ammonia water, so that the steam amount required for operation is greatly saved, and the energy is saved.
(2) Technical proposal
In order to solve the technical problems, the invention provides a system for recycling ammonia from rare earth separation waste liquid, which comprises a solution tank I, an energy-saving concentrator, a solution tank II, a solid-liquid separation device, a reaction tank, a calcium oxide storage tank, an automatic feeding device, a water jet vacuum pump I, a vacuum ammonia absorption tank I, a spray absorption tower, an ammonia water storage tank, a tubular heat exchanger, an evaporation tower, a cooling device, an ammonia water vacuum transition tank, a water jet vacuum pump II and a vacuum ammonia absorption tank II; the solution outlet of the solution tank I is connected to the material concentration inlet of the energy-saving concentrator through a pipeline, the material concentration outlet of the energy-saving concentrator is connected to the solution inlet of the solution tank II through a pipeline, the solution outlet of the solution tank II is connected to the material inlet of the reaction tank through a pipeline, the material inlet of the reaction tank is also connected with a calcium oxide storage tank through a pipeline, an automatic feeding device for automatically feeding calcium oxide is arranged on the pipeline between the material inlet of the reaction tank and the calcium oxide storage tank, the gaseous material outlet of the reaction tank is connected to the suction end of the water jet vacuum pump I through a pipeline, the discharge end of the water jet vacuum pump I is connected to the material inlet of the vacuum ammonia absorption tank I through a pipeline, the gaseous material outlet of the vacuum ammonia absorption tank I is connected to the inlet of the spray absorption tower through a pipeline, and the liquid material outlet of the vacuum ammonia absorption tank I is connected to the inlet of the ammonia water storage tank through a pipeline; the liquid material outlet of the reaction tank is connected to the cold fluid inlet of the tube array heat exchanger through a pipeline, the cold fluid outlet of the tube array heat exchanger is connected to the material inlet of the evaporation tower through a pipeline, the gaseous material outlet of the evaporation tower is connected to the hot fluid inlet of the tube array heat exchanger through a pipeline, the hot fluid outlet of the tube array heat exchanger is connected to the material inlet of the cooling device through a pipeline, the material outlet of the cooling device is connected to the inlet of the ammonia water vacuum transition tank through a pipeline, the liquid material outlet of the ammonia water vacuum transition tank is connected to the material inlet of the ammonia water storage tank through a pipeline, the gaseous material outlet of the ammonia water vacuum transition tank is connected to the suction end of the water jet vacuum pump II through a pipeline, the discharge end of the water jet vacuum pump II is connected to the material inlet of the vacuum ammonia absorption tank II through a pipeline, the gaseous material outlet of the vacuum ammonia absorption tank II is connected to the inlet of the spray absorption tower through a pipeline, and the liquid material outlet of the vacuum ammonia absorption tank II is connected to the inlet of the ammonia water storage tank through a pipeline; the liquid material outlet of the evaporation tower is connected with an auxiliary heat inlet of the energy-saving concentrator through a pipeline, and the auxiliary heat outlet of the energy-saving concentrator is connected with a solid-liquid separation device through a pipeline.
Preferably, the evaporation tower is provided with a steam pressure stabilizing valve. The steam pressure stabilizing valve can adjust the steam pressure, so that the stability of the steam pressure is guaranteed, the steam can be saved, and the effects of energy conservation and loss reduction are achieved.
Preferably, the gaseous material outlet of the evaporation tower is connected with an anti-overflow groove drainage device through a pipeline, and the other end of the anti-overflow groove drainage device is connected with the material inlet of the reaction tank. The anti-overflow groove drainage device can prevent the evaporation tower from bringing the calcium oxide waste residues into the tube heat exchanger and subsequent equipment during overflow, thereby preventing the calcium oxide waste residues from blocking the cooling device and the pipeline and ensuring the safe and continuous operation of the system.
When the system for recovering ammonia from the rare earth separation waste liquid is used for operation, the operation steps of the system can be in one-to-one correspondence with the following method for recovering ammonia from the rare earth separation waste liquid, and the following method is operated by the system, so that the ammonia is recovered efficiently, energy-saving and environment-friendly.
Aiming at the system for recovering ammonia from the rare earth separation waste liquid, the invention provides a method for recovering ammonia from the rare earth separation waste liquid, which is suitable for the system in use, and comprises the following specific steps:
step one, stirring uniformly; fully stirring and mixing the low-concentration ammonium chloride solution recovered from the rare earth extraction and/or rare earth precipitation process to ensure that the concentration and the pH value of the solution are consistent;
the recycled low-concentration ammonium chloride solution is fully and uniformly stirred, so that the consistency of the concentration and the pH value of the ammonium chloride solution is ensured, the stability of the reaction can be improved when the ammonium chloride solution reacts with calcium oxide in the third step, the consumption of the calcium oxide is saved, and the discharge qualification rate of components in the wastewater discharged in the fifth step is finally improved.
Step two, heating and concentrating; pumping the low-concentration ammonium chloride solution with the concentration consistent with the pH value obtained in the step one into an energy-saving concentrator, heating and concentrating to obtain a high-concentration ammonium chloride solution, and controlling the concentration of ammonium chloride in the high-concentration ammonium chloride solution to be 2.6-3.6mol/L;
the method is used for heating and concentrating the low-concentration ammonium chloride solution to obtain the high-concentration ammonium chloride solution, the temperature of the solution is increased, the specific concentration of the concentrated ammonium chloride is controlled to be 2.6-3.6mol/L, the reaction rate of the solution in the subsequent reaction can be improved to a certain extent, and the recovery rate of ammonia can be improved to the greatest extent.
In addition, the energy-saving environment-friendly effect is achieved by fully utilizing the heat in the calcium chloride water slag waste liquid in the fifth step and combining an energy-saving concentrator to heat and concentrate the low-concentration ammonium chloride solution.
Step three, substitution reaction; pumping the high-concentration ammonium chloride solution obtained in the second step into a reaction tank, uniformly adding calcium oxide into the reaction tank, and carrying out displacement reaction on the high-concentration ammonium chloride solution and the calcium oxide to obtain a mixed solution of ammonia water and calcium chloride, wherein the reaction releases heat and generates ammonia gas;
the step makes the high concentration ammonium chloride solution with certain temperature fully react with calcium oxide, and fully releases heat in the reaction to obtain the mixed solution of ammonia water and calcium chloride with higher temperature, and the high temperature generated by the mixed solution is utilized to separate certain ammonia gas from the solution.
Step four, ammonia gas is recovered once; vacuumizing the reaction tank by adopting a water jet vacuum pump I, pumping the ammonia gas generated in the step three of the reaction tank into a vacuum ammonia absorption tank I, absorbing the ammonia gas by using water in the vacuum ammonia absorption tank I to obtain ammonia water, conveying the obtained ammonia water into an ammonia water storage tank for storage, conveying the ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank I into a spray absorption tower, and carrying out spray absorption by using an ammonium chloride solution;
the reaction tank is vacuumized through the water jet vacuum pump I, and ammonia is absorbed through water in the vacuum ammonia absorption tank I, so that negative pressure is formed on the reaction tank, and the ammonia is fully separated out and enters the vacuum ammonia absorption tank I, so that the reaction speed in the reaction tank and the absorption speed in the vacuum ammonia absorption tank I are improved, the solubility of ammonium ions in the solution is greatly reduced, the flow rate of the ammonia is enhanced, the recovery rate of the ammonia is maximally improved, and the ammonia content in waste gas is reduced; the ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank I is sprayed and absorbed in the spraying absorption tower through an ammonium chloride solution, so that the very small amount of ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank I is completely recycled, the ammonia in the waste gas is thoroughly eliminated, and the complete harmless emission of the tail gas is realized; in addition, the ammonium chloride solution is used for spraying and absorbing, the weak acidity of the ammonium chloride solution is utilized, so that the spraying and absorbing effect can be ensured, the subsequent recycling can be realized through absorbing ammonia, and the recycling is efficient and thorough.
Step five, recycling ammonia gas secondarily; conveying the mixed solution of ammonia water and calcium chloride obtained in the step three into a tube array heat exchanger for heat exchange and temperature rise, and then adding the mixed solution of ammonia water and calcium chloride into an evaporation tower for distillation, concentration and separation to obtain ammonia steam and calcium chloride water slag waste liquid; the calcium chloride water slag waste liquid is conveyed into an energy-saving concentrator in the second step, the energy-saving concentrator is utilized to heat and concentrate the low-concentration ammonium chloride solution through the temperature of the calcium chloride water slag waste liquid, and then the calcium chloride water slag waste liquid is conveyed into a solid-liquid separation device for solid-liquid separation, so as to obtain discharged waste slag and discharged waste water; conveying ammonia steam back to the tube nest heat exchanger of the step for heat exchange and cooling, conveying the ammonia steam to a cooling device for cooling, and conveying the cooled ammonia steam to an ammonia water vacuum transition tank to obtain ammonia water and ammonia gas; the obtained ammonia water is conveyed into an ammonia water storage tank for storage; and vacuumizing the ammonia water vacuum transition tank by using a water jet vacuum pump II, pumping ammonia gas in the ammonia water vacuum transition tank into a vacuum ammonia absorption tank II, absorbing the ammonia gas by using water in the vacuum ammonia absorption tank II to obtain ammonia water, conveying the obtained ammonia water into an ammonia water storage tank for storage, and conveying ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank II into a spray absorption tower for spray absorption by using an ammonium chloride solution.
The heat exchange between different mediums can be realized by the tube nest heat exchanger and the energy-saving concentrator, in the step, the temperature of the mixed solution of the ammonia water and the calcium chloride entering the tube nest heat exchanger is lower, the temperature of the ammonia steam obtained in the evaporation tower is higher, when the ammonia water and the calcium chloride enter the tube nest heat exchanger, the mixed solution of the ammonia water and the calcium chloride and the ammonia steam are not mixed, only the heat exchange between the ammonia water and the calcium chloride is realized, namely the heat of the ammonia steam is transferred to the mixed solution of the ammonia water and the calcium chloride, so that the ammonia steam is subjected to heat exchange and temperature reduction to realize preliminary cooling, and then is subjected to deep cooling, and meanwhile, the mixed solution of the ammonia water and the calcium chloride is subjected to heat exchange and temperature rise, so that the heat in the ammonia steam is fully utilized, and the energy-saving effect is realized.
In the second step, the temperature of the low-concentration ammonium chloride solution entering the energy-saving concentrator is low, the temperature of the calcium chloride water slag waste liquid obtained in the evaporation tower is higher, and the low-concentration ammonium chloride solution and the calcium chloride water slag waste liquid enter the energy-saving concentrator to realize heat exchange, namely, the calcium chloride water slag waste liquid transfers heat to the low-concentration ammonium chloride solution, so that the temperature of the calcium chloride water slag waste liquid is reduced, the calcium chloride water slag waste liquid is subjected to solid-liquid separation, the temperature of the low-concentration ammonium chloride solution is increased, and the energy-saving concentrator is utilized to heat and concentrate the low-concentration ammonium chloride solution, so that the heat in the calcium chloride water slag waste liquid is fully utilized, and the energy-saving effect is further realized.
In the fifth step, the mixed solution of ammonia water and calcium chloride is added into an evaporation tower for distillation, concentration and separation, so that ammonia vapor and calcium chloride water slag waste liquid are obtained, ammonia separation is realized, ammonia vapor is conveyed into an ammonia water vacuum transition tank through cooling of a tube array heat exchanger and a cooling device, the ammonia water vacuum transition tank is vacuumized through a water jet vacuum pump II, ammonia gas is absorbed through water in a vacuum ammonia absorption tank II, and because the pipeline passages of the ammonia water vacuum transition tank, the cooling device, the tube array heat exchanger, the vacuum ammonia absorption tank II, the evaporation tower and other devices are communicated, the communicated devices form negative pressure, so that the absorption speed in the ammonia water vacuum transition tank and the vacuum ammonia absorption tank I is improved, the heat transfer efficiency of the cooling device and the tube array heat exchanger is enhanced, the cooling speed is improved, especially when the negative pressure is formed in the evaporation tower to improve the vacuum degree in the ammonia water vacuum transition tank, the flow rate of the ammonia gas and the ammonia ion content in the liquid are greatly reduced, the recovery rate of ammonia and the device productivity are improved, in addition, the boiling point of the liquid is greatly reduced, the consumption of the ammonia gas in the evaporation tower is reduced, the energy saving effect is further improved, and the high recovery rate is realized; meanwhile, ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank II is sprayed and absorbed in the spraying absorption tower through an ammonium chloride solution, so that the very small amount of ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank II is completely recycled, ammonia in waste gas is thoroughly eliminated, and the tail gas is completely discharged harmlessly; in addition, the ammonium chloride solution is used for spraying and absorbing, the weak acidity of the ammonium chloride solution is utilized, so that the spraying and absorbing effect can be ensured, the subsequent recycling can be realized through absorbing ammonia, and the recycling is efficient and thorough.
Preferably, in the second step, the concentration of ammonium chloride in the high concentration ammonium chloride solution is controlled to 3.2mol/L. Under the concentration, the reaction rate of the solution and calcium oxide can be improved to the maximum extent, the operation effect of the method is improved, the ammonia recovery efficiency in the subsequent reaction is realized optimally, and the overall high efficiency of recovering ammonia from the rare earth separation waste liquid is ensured.
Preferably, in step three, calcium oxide is added uniformly to the reaction tank by an automatic feeding device. Therefore, the addition amount of the calcium oxide is balanced and stable, the reaction of the calcium oxide and the high-concentration ammonium chloride solution is stable and complete, and the discharge qualification rate and the stability of the finally discharged waste residue and the discharged waste water component are greatly improved.
Preferably, in step three, the reaction tank is a multistage reaction tank. Therefore, the reaction effect of the calcium oxide and the high-concentration ammonium chloride solution can be gradually improved, and the reaction speed is increased, so that the operation efficiency of recovering ammonia from the rare earth separation waste liquid by the method is integrally improved.
The low-concentration ammonium chloride solution is placed in a solution tank I, the low-concentration ammonium chloride solution is heated and concentrated through an energy-saving concentrator, the high-concentration ammonium chloride solution is obtained and placed in a solution tank II, calcium oxide is stored in a calcium oxide storage tank, and automatic continuous feeding is carried out in a reaction tank through an automatic feeding device.
(3) Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
firstly, the system fully stirs and mixes the low-concentration ammonium chloride solution, and then concentrates and reacts, so that the reaction rate of the solution in the subsequent reaction can be improved to a certain extent under the concentration condition, and the recovery rate and the productivity of ammonia can be improved to the greatest extent.
Secondly, the system is used for vacuumizing the reaction tank through the water jet vacuum pump I, collecting overflowed ammonia in the reaction tank through the vacuum ammonia absorption tank I, vacuumizing the evaporation tower, the tube array heat exchanger and the pipeline through the water jet vacuum pump II, collecting ammonia steam in the evaporation tower, and then combining the communication between corresponding equipment pipeline passages through the ammonia water vacuum transition tank and the vacuum ammonia absorption tank II, so that devices such as the reaction tank and the evaporation tower form negative pressure, ammonia is fully separated out and enters the vacuum ammonia absorption tank I and the vacuum ammonia absorption tank II, the reaction speed in each device and the absorption speed of the ammonia are improved, the heat transfer efficiency of the cooling device and the tube array heat exchanger is enhanced, especially when the vacuum degree in the evaporation tower is improved by forming the negative pressure, the flow rate of the steam and the ammonia is enhanced, the content of ammonium ions in the solution is greatly reduced, the recovery rate and the equipment capacity of the ammonia are improved to the maximum extent, the recovery rate of the ammonia is more than or equal to 99.5%, the finally obtained ammonia concentration reaches 8.0-10.0mol/L, and the system is efficient and thorough.
And secondly, the system improves the recovery rate of ammonia to the greatest extent by forming negative pressure, correspondingly, reduces the ammonia content in the waste gas and the waste liquid to the greatest extent, separates and discharges calcium chloride water slag waste liquid solid and liquid, sprays and absorbs ammonia which is not absorbed by water in the vacuum ammonia absorption tank I and the vacuum ammonia absorption tank II in the spraying absorption tower through an ammonium chloride solution, thereby thoroughly eliminating the ammonia in the waste gas, realizing the complete harmless discharge of the tail gas, and realizing low discharge and pollution by the method, wherein the ammonia nitrogen content in the waste water finally discharged by the method is less than or equal to 5.0ppm and is far less than 15.0ppm of the national primary discharge standard.
Finally, the system forms negative pressure in each device and pipeline by the action of the water jet vacuum pump I and the water jet vacuum pump II, and simultaneously utilizes the principle of reducing the atmospheric pressure and the boiling point of liquid, thereby reducing the steam consumption required by the operation of the evaporation tower, further improving the ammonia recovery rate to the maximum extent and achieving high efficiency and energy saving; meanwhile, the waste heat of the process materials is respectively utilized by the energy-saving concentrator and the tube array heat exchanger, so that the energy-saving and environment-friendly effects are further realized, the operation is carried out by the method, the consumption of steam only needs 0.8-1.0 ton/ton of ammonia water, the steam amount required by the operation is greatly saved, and the energy is saved.
In general, ammonia is recovered through the system, so that the recovery rate of the ammonia is more than or equal to 99.5%, the concentration of finally obtained ammonia water reaches 8.0-10.0mol/L, and the recovery is efficient and thorough; meanwhile, the ammonia nitrogen content in the wastewater finally discharged by the method is less than or equal to 5.0ppm and is far less than 15.0ppm of the national first-level discharge standard, so that low discharge and low pollution are realized; in addition, the method is used for operation, and the consumption of the steam only needs 0.8-1.0 ton/ton of ammonia water, so that the steam amount required for operation is greatly saved, and the energy is saved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for the description of the embodiments or the prior art will be briefly described, and it is apparent that the drawings in the following description are only one embodiment of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a process flow diagram of a method for recovering ammonia in an embodiment of the invention.
FIG. 2 is a schematic diagram of an ammonia recovery system in accordance with an embodiment of the present invention.
The marks in the drawings are: 1-solution tank I, 2-energy-saving concentrator, 3-solution tank II, 4-solid-liquid separation device, 5-reaction tank, 6-calcium oxide storage tank, 7-automatic feeding device, 8-water jet vacuum pump I, 9-vacuum ammonia absorption tank I, 10-spray absorption tower, 11-ammonia water storage tank, 12-tubular heat exchanger, 13-evaporation tower, 14-cooling device, 15-ammonia water vacuum transition tank, 16-water jet vacuum pump II, 17-vacuum ammonia absorption tank II.
Detailed Description
In order that the manner in which the above-recited features, advantages, objects and advantages of the present invention are obtained will become readily apparent, a more particular description of the invention briefly summarized below may be had by reference to the embodiments thereof which are illustrated in the appended drawings, wherein it is apparent that the embodiments described are merely some, but not all, of the embodiments of the invention.
A system for recycling ammonia from rare earth separation waste liquid is shown in fig. 2, and fig. 2 is a schematic structural diagram of the embodiment, wherein the system comprises a solution tank I1, an energy-saving concentrator 2, a solution tank II 3, a solid-liquid separation device 4, a reaction tank 5, a calcium oxide storage tank 6, an automatic feeding device 7, a water jet vacuum pump I8, a vacuum ammonia absorption tank I9, a spray absorption tower 10, an ammonia water storage tank 11, a tube heat exchanger 12, an evaporation tower 13, a cooling device 14, an ammonia water vacuum transition tank 15, a water jet vacuum pump II 16 and a vacuum ammonia absorption tank II 17; the solution outlet of the solution tank I1 is connected to the material concentration inlet of the energy-saving concentrator 2 through a pipeline, the material concentration outlet of the energy-saving concentrator 2 is connected to the solution inlet of the solution tank II 3 through a pipeline, the solution outlet of the solution tank II 3 is connected to the material inlet of the reaction tank 5 through a pipeline, the material inlet of the reaction tank 5 is also connected with a calcium oxide storage tank 6 through a pipeline, an automatic feeding device 7 for automatically feeding calcium oxide is arranged on the pipeline between the material inlet of the reaction tank 5 and the calcium oxide storage tank 6, the gaseous material outlet of the reaction tank 5 is connected to the suction end of the water jet vacuum pump I8 through a pipeline, the discharge end of the water jet vacuum pump I8 is connected to the material inlet of the vacuum ammonia absorption tank I9 through a pipeline, the gaseous material outlet of the vacuum ammonia absorption tank I9 is connected to the inlet of the spray absorption tower 10 through a pipeline, and the liquid material outlet of the vacuum ammonia absorption tank I9 is connected to the inlet of the ammonia water storage tank 11 through a pipeline; the liquid material outlet of the reaction tank 5 is connected to the cold fluid inlet of the tube nest heat exchanger 12 through a pipeline, the cold fluid outlet of the tube nest heat exchanger 12 is connected to the material inlet of the evaporation tower 13 through a pipeline, the gaseous material outlet of the evaporation tower 13 is connected to the hot fluid inlet of the tube nest heat exchanger 12 through a pipeline, the hot fluid outlet of the tube nest heat exchanger 12 is connected to the material inlet of the cooling device 14 through a pipeline, the material outlet of the cooling device 14 is connected to the inlet of the ammonia water vacuum transition tank 15 through a pipeline, the liquid material outlet of the ammonia water vacuum transition tank 15 is connected to the material inlet of the ammonia water storage tank 11 through a pipeline, the gaseous material outlet of the ammonia water vacuum transition tank 15 is connected to the suction end of the water jet vacuum pump II 16 through a pipeline, the gaseous material outlet of the vacuum ammonia suction pump II 17 is connected to the inlet of the spray absorption tower 10 through a pipeline, and the liquid material outlet of the vacuum ammonia suction tank II 17 is connected to the inlet of the ammonia water storage tank 11 through a pipeline; the liquid material outlet of the evaporation tower 13 is connected with the auxiliary heat inlet of the energy-saving concentrator 2 through a pipeline, and the auxiliary heat outlet of the energy-saving concentrator 2 is connected with the solid-liquid separation device 4 through a pipeline. In this case, as a preferred embodiment, a vapor pressure stabilizing valve is mounted on the evaporation tower 13. The steam pressure stabilizing valve can adjust the steam pressure, so that the stability of the steam pressure is guaranteed, the steam can be saved, and the effects of energy conservation and loss reduction are achieved. As a preferred embodiment, the gaseous material outlet of the evaporation tower 13 is connected with an anti-overflow drain device through a pipeline, and the other end of the anti-overflow drain device is connected with the material inlet of the reaction tank 5. The anti-overflow drain device can prevent the evaporation tower 13 from bringing the calcium oxide waste slag into the tubular heat exchanger 12 and subsequent equipment during overflow, thereby preventing the calcium oxide waste slag from blocking the cooling device 14 and the pipeline and ensuring the safe and continuous operation of the system.
When the high-efficiency energy-saving environment-friendly ammonia recovery system is used for operation, the specific operation process is respectively carried out according to the following three embodiments, the devices of the three embodiments in the use process are in one-to-one correspondence with the system, and the three embodiments respectively draw conclusions.
Example 1
As shown in fig. 1, fig. 1 is a process flow chart of the present embodiment, and the specific steps are as follows:
step one, stirring uniformly; and (3) placing ammonium chloride wastewater which is discharged in the rare earth processing and extracting production and has the concentration range of 1.7-2.1mol/L and the acidity range of 0.2-0.3mol/L into a solution tank I1, and uniformly stirring to obtain a solution with the concentration consistent with the pH value.
Step two, heating and concentrating; pumping the low-concentration ammonium chloride solution with the concentration consistent with the pH value obtained in the first step into an energy-saving concentrator 2, heating and concentrating the solution to obtain a high-concentration ammonium chloride solution, and placing the high-concentration ammonium chloride solution into a solution tank II 3, so that the concentration of ammonium chloride in the high-concentration ammonium chloride solution is controlled to be 3.6mol/L.
Step three, substitution reaction; pumping the high-concentration ammonium chloride solution obtained in the second step into a reaction tank 5, uniformly adding calcium oxide into the reaction tank 5, storing the calcium oxide in a calcium oxide storage tank 6, automatically and continuously feeding the high-concentration ammonium chloride solution into the reaction tank 5 through an automatic feeding device 7, performing displacement reaction on the high-concentration ammonium chloride solution and the calcium oxide to obtain a mixed solution of ammonia water and calcium chloride, and releasing heat of reaction and generating ammonia gas.
Step four, ammonia gas is recovered once; and (3) vacuumizing the reaction tank 5 by adopting a water jet vacuum pump I8, pumping the ammonia generated in the step three by the reaction tank 5 into a vacuum ammonia absorption tank I9, absorbing the ammonia by using water in the vacuum ammonia absorption tank I9 to obtain ammonia water, conveying the obtained ammonia water into an ammonia water storage tank for storage, conveying the ammonia which is not absorbed by water in the vacuum ammonia absorption tank I9 into a spray absorption tower 10, and carrying out spray absorption by using an ammonium chloride solution.
Step five, recycling ammonia gas secondarily; the mixed solution of ammonia water and calcium chloride obtained in the third step is conveyed into a tube array heat exchanger 12 for heat exchange and temperature rise, and then the mixed solution of ammonia water and calcium chloride is added into an evaporation tower 13 for distillation, concentration and separation, and the feeding speed of the mixed solution of ammonia water and calcium chloride into the evaporation tower 13 is controlled to be 15.0m 3 Obtaining ammonia steam and calcium chloride water slag waste liquid; the calcium chloride water slag waste liquid is conveyed into an energy-saving concentrator 2 in the second step, the energy-saving concentrator 2 is utilized to heat and concentrate the low-concentration ammonium chloride solution through the temperature of the calcium chloride water slag waste liquid, and then the calcium chloride water slag waste liquid is conveyed into a solid-liquid separation device 4 for solid-liquid separation, so as to obtain discharged waste residues and discharged waste water; the ammonia vapor is conveyed back to the tube-in-tube heat exchanger 12 of the step for heat exchange and temperature reduction, and then the ammonia vapor is conveyedCooling in a cooling device 14, and conveying ammonia vapor into an ammonia water vacuum transition tank 15 after cooling to obtain ammonia water and ammonia gas; the obtained ammonia water is conveyed into an ammonia water storage tank 11 for storage; vacuumizing the ammonia water vacuum transition tank 15 by using a water jet vacuum pump II 16, pumping ammonia gas in the ammonia water vacuum transition tank 15 into a vacuum ammonia absorption tank II 17, absorbing the ammonia gas by using water in the vacuum ammonia absorption tank II 17 to obtain ammonia water, conveying the obtained ammonia water into an ammonia water storage tank 11 for storage, conveying ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank II 17 into a spray absorption tower 10, and spraying and absorbing by using an ammonium chloride solution; the temperature remote temperature controller in the evaporation tower under the action of the water jet vacuum pump II 16 shows that the temperature is 95.0-98.0 ℃, and the vacuum degree in the tower is 0.02+/-0.01 Mpa.
The operation of recovering ammonia is specifically carried out through the above process, and the data of each corresponding recovery and emission are calculated, and the corresponding conclusion is obtained: the recovery rate of ammonia is 99.7%, the concentration of the finally obtained ammonia water is 8.5mol/L, and the recovery is efficient and thorough; the ammonia nitrogen content in the final discharged wastewater is 4.0ppm which is far less than 15.0ppm of the national first-level discharge standard, thus realizing low emission and low pollution; in addition, in the operation, the consumption of steam is 0.9 ton/ton of ammonia water as a whole, which greatly saves the steam amount required for the operation and saves energy.
Example 2
As shown in fig. 1, fig. 1 is a process flow chart of the present embodiment, and the specific steps are as follows:
step one, stirring uniformly; ammonium chloride wastewater with the concentration range of 1.8-2.3mol/L and the acidity range of 0.2-2.3mol/L discharged in rare earth processing and extraction production and ammonium chloride wastewater with the concentration range of 0.4-1.0mol/L and the acidity of neutral and slightly alkaline discharged in precipitation production are placed in a solution tank I1 and are uniformly stirred to obtain a solution with the concentration consistent with the pH value, and the concentration of the ammonium chloride wastewater after uniform stirring is 1.9+/-0.1 mol/L and the acidity is 0.3+/-0.05 mol/L.
Step two, heating and concentrating; pumping the low-concentration ammonium chloride solution with the concentration consistent with the pH value obtained in the first step into an energy-saving concentrator 2, heating and concentrating the solution to obtain a high-concentration ammonium chloride solution, and placing the high-concentration ammonium chloride solution into a solution tank II 3, so that the concentration of ammonium chloride in the high-concentration ammonium chloride solution is controlled to be 3.2mol/L.
Step three, substitution reaction; pumping the high-concentration ammonium chloride solution obtained in the second step into a reaction tank 5, uniformly adding calcium oxide into the reaction tank 5, storing the calcium oxide in a calcium oxide storage tank 6, automatically and continuously feeding the high-concentration ammonium chloride solution into the reaction tank 5 through an automatic feeding device 7, performing displacement reaction on the high-concentration ammonium chloride solution and the calcium oxide to obtain a mixed solution of ammonia water and calcium chloride, and releasing heat of reaction and generating ammonia gas.
Step four, ammonia gas is recovered once; and (3) vacuumizing the reaction tank 5 by adopting a water jet vacuum pump I8, pumping the ammonia generated in the step three by the reaction tank 5 into a vacuum ammonia absorption tank I9, absorbing the ammonia by using water in the vacuum ammonia absorption tank I9 to obtain ammonia water, conveying the obtained ammonia water into an ammonia water storage tank for storage, conveying the ammonia which is not absorbed by water in the vacuum ammonia absorption tank I9 into a spray absorption tower 10, and carrying out spray absorption by using an ammonium chloride solution.
Step five, recycling ammonia gas secondarily; the mixed solution of ammonia water and calcium chloride obtained in the third step is conveyed into a tube array heat exchanger 12 for heat exchange and temperature rise, and then the mixed solution of ammonia water and calcium chloride is added into an evaporation tower 13 for distillation, concentration and separation, and the feeding speed of the mixed solution of ammonia water and calcium chloride into the evaporation tower 13 is controlled to be 19.0m 3 Obtaining ammonia steam and calcium chloride water slag waste liquid; the calcium chloride water slag waste liquid is conveyed into an energy-saving concentrator 2 in the second step, the energy-saving concentrator 2 is utilized to heat and concentrate the low-concentration ammonium chloride solution through the temperature of the calcium chloride water slag waste liquid, and then the calcium chloride water slag waste liquid is conveyed into a solid-liquid separation device 4 for solid-liquid separation, so as to obtain discharged waste residues and discharged waste water; the ammonia steam is conveyed back to the tubular heat exchanger 12 of the step for heat exchange and temperature reduction, then the ammonia steam is conveyed to the cooling device 14 for cooling, and the ammonia steam is conveyed to the ammonia water vacuum transition tank 15 after being cooled, so as to obtain ammonia water and ammonia gas; the obtained ammonia water is conveyed into an ammonia water storage tank 11 for storage; using water jetsThe air pump II 16 vacuumizes the ammonia water vacuum transition tank 15, pumps ammonia gas in the ammonia water vacuum transition tank 15 into the vacuum ammonia absorption tank II 17, absorbs the ammonia gas in the vacuum ammonia absorption tank II 17 by water to obtain ammonia water, then conveys the obtained ammonia water into the ammonia water storage tank 11 for storage, conveys ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank II 17 into the spray absorption tower 10, and sprays and absorbs the ammonia gas by an ammonium chloride solution; the temperature remote temperature controller in the evaporation tower under the action of the water jet vacuum pump II 16 shows that the temperature is 95.0-98.0 ℃, and the vacuum degree in the tower is 0.02+/-0.01 Mpa.
The operation of recovering ammonia is specifically carried out through the above process, and the data of each corresponding recovery and emission are calculated, and the corresponding conclusion is obtained: the recovery rate of ammonia is 99.9%, the concentration of the finally obtained ammonia water is 9.8mol/L, and the recovery is efficient and thorough; the ammonia nitrogen content in the final discharged wastewater is 3.0ppm which is far less than 15.0ppm of the national first-level discharge standard, thus realizing low emission and low pollution; in addition, in the operation, the consumption of steam is 0.8 ton/ton of ammonia water as a whole, which greatly saves the steam amount required for the operation and saves energy.
Example 3
As shown in fig. 1, fig. 1 is a process flow chart of the present embodiment, and the specific steps are as follows:
step one, stirring uniformly; and (3) placing ammonium chloride wastewater which is discharged in the rare earth processing precipitation production and has the concentration range of 0.4-1.0mol/L and the acidity of neutral and slightly alkaline into a solution tank I1, and uniformly stirring to obtain a solution with the concentration consistent with the pH value.
Step two, heating and concentrating; pumping the low-concentration ammonium chloride solution with the concentration consistent with the pH value obtained in the first step into an energy-saving concentrator 2, heating and concentrating the solution to obtain a high-concentration ammonium chloride solution, and placing the high-concentration ammonium chloride solution into a solution tank II 3, so that the concentration of ammonium chloride in the high-concentration ammonium chloride solution is controlled to be 2.6mol/L.
Step three, substitution reaction; pumping the high-concentration ammonium chloride solution obtained in the second step into a reaction tank 5, uniformly adding calcium oxide into the reaction tank 5, storing the calcium oxide in a calcium oxide storage tank 6, automatically and continuously feeding the high-concentration ammonium chloride solution into the reaction tank 5 through an automatic feeding device 7, performing displacement reaction on the high-concentration ammonium chloride solution and the calcium oxide to obtain a mixed solution of ammonia water and calcium chloride, and releasing heat of reaction and generating ammonia gas.
Step four, ammonia gas is recovered once; vacuumizing the reaction tank 5 by adopting a water jet vacuum pump I8, pumping the ammonia gas generated in the step three by the reaction tank 5 into a vacuum ammonia absorption tank I9, absorbing the ammonia gas by using water in the vacuum ammonia absorption tank I9 to obtain ammonia water, conveying the obtained ammonia water into an ammonia water storage tank for storage, conveying the ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank I9 into a spray absorption tower 10, and carrying out spray absorption by using an ammonium chloride solution;
step five, recycling ammonia gas secondarily; the mixed solution of ammonia water and calcium chloride obtained in the third step is conveyed into a tube array heat exchanger 12 for heat exchange and temperature rise, and then the mixed solution of ammonia water and calcium chloride is added into an evaporation tower 13 for distillation, concentration and separation, and the feeding speed of the mixed solution of ammonia water and calcium chloride into the evaporation tower 13 is controlled to be 15.0m 3 Obtaining ammonia steam and calcium chloride water slag waste liquid; the calcium chloride water slag waste liquid is conveyed into an energy-saving concentrator 2 in the second step, the energy-saving concentrator 2 is utilized to heat and concentrate the low-concentration ammonium chloride solution through the temperature of the calcium chloride water slag waste liquid, and then the calcium chloride water slag waste liquid is conveyed into a solid-liquid separation device 4 for solid-liquid separation, so as to obtain discharged waste residues and discharged waste water; the ammonia steam is conveyed back to the tubular heat exchanger 12 of the step for heat exchange and temperature reduction, then the ammonia steam is conveyed to the cooling device 14 for cooling, and the ammonia steam is conveyed to the ammonia water vacuum transition tank 15 after being cooled, so as to obtain ammonia water and ammonia gas; the obtained ammonia water is conveyed into an ammonia water storage tank 11 for storage; the ammonia water vacuum transition tank 15 is vacuumized by a water jet vacuum pump II 16, ammonia gas in the ammonia water vacuum transition tank 15 is pumped into a vacuum ammonia absorption tank II 17, water is used for absorbing the ammonia gas in the vacuum ammonia absorption tank II 17 to obtain ammonia water, the obtained ammonia water is conveyed into an ammonia water storage tank 11 for storage, ammonia gas which is not absorbed by water in the vacuum ammonia absorption tank II 17 is conveyed into a spray absorption tower 10, and spraying is carried out through an ammonium chloride solutionLeaching and absorbing; the temperature remote temperature controller in the evaporation tower under the action of the water jet vacuum pump II 16 shows that the temperature is 95.0-98.0 ℃, and the vacuum degree in the tower is 0.02+/-0.01 Mpa.
The operation of recovering ammonia is specifically carried out through the above process, and the data of each corresponding recovery and emission are calculated, and the corresponding conclusion is obtained: the recovery rate of ammonia is 99.8%, the concentration of the finally obtained ammonia water is 9.2mol/L, and the recovery is efficient and thorough; the ammonia nitrogen content in the final discharged wastewater is 3.0ppm which is far less than 15.0ppm of the national first-level discharge standard, thus realizing low emission and low pollution; in addition, in the operation, the consumption of steam is 0.9 ton/ton of ammonia water as a whole, which greatly saves the steam amount required for the operation and saves energy.
Having described the main technical features and fundamental principles of the present invention and related advantages, it will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, but may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The above detailed description is, therefore, to be taken in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present disclosure describes embodiments in terms of various embodiments, not every embodiment is described in terms of a single embodiment, but rather that the descriptions of embodiments are merely provided for clarity, and that the descriptions of embodiments in terms of various embodiments are provided for persons skilled in the art on the basis of the description.
Claims (1)
1. The system for recycling ammonia from rare earth separation waste liquid is characterized by comprising a solution tank I (1), an energy-saving concentrator (2), a solution tank II (3), a solid-liquid separation device (4), a reaction tank (5), a calcium oxide storage tank (6), an automatic feeding device (7), a water jet vacuum pump I (8), a vacuum ammonia absorption tank I (9), a spray absorption tower (10), an ammonia water storage tank (11), a tubular heat exchanger (12), an evaporation tower (13), a cooling device (14), an ammonia water vacuum transition tank (15), a water jet vacuum pump II (16) and a vacuum ammonia absorption tank II (17); the solution outlet of the solution tank I (1) is connected to the material concentration inlet of the energy-saving concentrator (2) through a pipeline, the material concentration outlet of the energy-saving concentrator (2) is connected to the solution inlet of the solution tank II (3) through a pipeline, the solution outlet of the solution tank II (3) is connected to the material inlet of the reaction tank (5) through a pipeline, the material inlet of the reaction tank (5) is also connected with a calcium oxide storage tank (6) through a pipeline, an automatic feeding device (7) for automatically feeding calcium oxide is arranged on the pipeline between the material inlet of the reaction tank (5) and the calcium oxide storage tank (6), the gaseous material outlet of the reaction tank (5) is connected to the suction end of the water jet vacuum pump I (8) through a pipeline, the discharge end of the water jet vacuum pump I (8) is connected to the material inlet of the vacuum ammonia absorption tank I (9) through a pipeline, the gaseous material outlet of the vacuum ammonia absorption tank I (9) is connected to the inlet of the spray absorption tower (10) through a pipeline, and the liquid material outlet of the vacuum ammonia absorption tank I (9) is connected to the inlet of the ammonia water storage tank (11) through a pipeline; the liquid material outlet of the reaction tank (5) is connected to the cold fluid inlet of the tube array heat exchanger (12) through a pipeline, the cold fluid outlet of the tube array heat exchanger (12) is connected to the material inlet of the evaporation tower (13) through a pipeline, the gaseous material outlet of the evaporation tower (13) is connected to the hot fluid inlet of the tube array heat exchanger (12) through a pipeline, the hot fluid outlet of the tube array heat exchanger (12) is connected to the material inlet of the cooling device (14) through a pipeline, the material outlet of the cooling device (14) is connected to the inlet of the ammonia water vacuum transition tank (15) through a pipeline, the liquid material outlet of the ammonia water vacuum transition tank (15) is connected to the material inlet of the ammonia water storage tank (11) through a pipeline, the gaseous material outlet of the ammonia water vacuum transition tank (15) is connected to the suction end of the water jet vacuum pump II (16) through a pipeline, the gaseous material outlet of the vacuum ammonia absorption tank II (17) is connected to the material inlet of the spray tower (10) through a pipeline, and the gaseous material outlet of the vacuum ammonia absorption tank II (17) is connected to the liquid material inlet of the ammonia storage tank (11) through a pipeline; the liquid material outlet of the evaporation tower (13) is connected with the auxiliary heat inlet of the energy-saving concentrator (2) through a pipeline, and the auxiliary heat outlet of the energy-saving concentrator (2) is connected with the solid-liquid separation device (4) through a pipeline;
wherein, a steam pressure stabilizing valve is arranged on the evaporation tower (13);
the gaseous material outlet of the evaporation tower (13) is connected with an anti-overflow groove drainage device through a pipeline, and the other end of the anti-overflow groove drainage device is connected with the material inlet of the reaction tank (5).
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| CN105417823A (en) * | 2015-12-25 | 2016-03-23 | 周振喜 | Method of recycling ammonia from low-concentration ammonium chloride waste water |
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| CN208429871U (en) * | 2018-06-07 | 2019-01-25 | 全南县新资源稀土有限责任公司 | A kind of system recycling ammonia from Rare Earth Separation waste liquid |
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| JPS60212288A (en) * | 1984-04-05 | 1985-10-24 | Mitsubishi Metal Corp | Treatment of waste water containing ammonium ion and fluorine ion |
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