A kind of rare earth extraction separates the combination treatment method of containing ammonium chloride waste waterTechnical field
The invention belongs to environmental engineering and technical field of chemical engineering, particularly a kind for the treatment of process of waste water.
Technical background
In Rare Earths Countercurrent Extraction Process, produce a large amount of containing ammonium chloride waste water, pollution component in water is taking chlorination ammonium salt as main, change in concentration scope is between 400.0-150000.0mg/l, calcium ions and magnesium ions 440.0-3500.0mg/l, fluorion 1.0-50.0mg/l, other heavy metal ion accumulative total 5.0-100.0mg/l, the organic pollutant 20.0-3000.0mg/l such as oils extraction agent, COD500.0-5000.0mg/l, this waste water complicated, cannot effectively administer by conventional water technology and technology.
Known rare-earth smelting separating technology adopts the ammoniacal liquor (NH of technical grade3h2o), bicarbonate of ammonia (NH4hCO3), heavy alkali (NaHCO3), soda ash (Na2cO3), sodium hydroxide (NaOH), hydrochloric acid (HCl) and special extraction agent etc. be as selecting smelting medicament.Use ammoniacal liquor during as saponifying agent and while using ammonium salt as rare earth metal precipitation agent, can produce the ammonium chloride waste-water of the high, normal, basic concentration of large discharge capacity, although can utilize advanced evaporating and concentrating process and device the ammonium chloride evaporative crystallization in waste water out, but running cost is too high, be difficult to bear.Meanwhile, owing to containing the impurity such as calcium ions and magnesium ions and oiliness extraction agent in waste water, very easily cause in evaporative process producing dirt, have a strong impact on vaporization efficiency and quality product, even cause whole water treatment equipment system operation paralysis.Therefore,, to producing the ammonium chloride waste-water of different concns in Rare Earths Countercurrent Extraction Process, first carry out that removal of impurities is processed and necessary low cost concentrates minimizing processing and is absolutely necessary.From the angle of recycling, the ammonium chloride waste-water producing in rare earth extraction separation of produced is carried out to the comprehensive regulation, process desalination pure water is back to production technique by purification of waste water on the one hand, on the other hand the ammonium chloride containing in waste water is extracted as agrochemical raw material, become the challenging technical barrier of domestic and international extracting and separating rear earth industry.
Summary of the invention
The object of the invention is to be to provide the combination treatment method of the ammonium chloride waste-water that a kind of energy consumption is low, running cost is low, simple to operate, waste water reclamation rate is high, the Rare Earth Separation of non-secondary pollution discharge of wastewater produces.The present invention is mainly desalination and the concentrated minimizing processing of different concns ammonium chloride waste-water being carried out to seriation by specific order and processing target, finally be met the ammonium chloride product of Agricultural Fertilizer standard by evaporative crystallization processing, and realize recycle and zero release that desalination is purified waste water.
Technical scheme of the present invention is as follows:
(1) Wastewater Pretreatment
According to the concentration difference of waste water containing ammonium chloride, waste water is shunted to disposal; Classify by concentration: the ammonium salt waste water of the high density of the ammonium salt waste water of the low concentration of ammonium chloride concentration≤3.5%, the intermediate concentration ammonium chloride waste-water of ammonium chloride concentration 3.5%-8.0% and ammonium chloride concentration >=8.0-15.0%, the ammonium salt waste water of different concns is entered respectively in different waste water and equalizing tank in, carry out oil removal, homogeneous, Air Exposure at equalizing tank; Again waste water is carried out electricity flocculation breakdown of emulsion, oil removal by air bubbling and adds the oil removing of the activity charcoal powder degree of depth, then enter agitating reaction pond add ammonia regulate pH value to 7.0-7.5, add the soluble phosphates such as ammonium hydrogen phosphate, go the heavy metal ion such as calcium-magnesium removing by generating calcium phosphate precipitation, ammonium salt waste water enters coagulative precipitation tank, fully sedimentation ageing, supernatant liquor passes through multi-medium filtering, activated carbon filtration and the pre-treatment of UF ultra-filtration filters again, and the waste water of above-mentioned processing is sent into the further pre-treatment of NF nano-filtration membrane equipment.
(2) electrodialysis (ED) and seawater desalination reverse osmosis film (SWRO) combined treatment of low concentration ammonium chloride wastewater in
The ammonium chloride waste-water of middle lower concentration is carried out after above-mentioned pre-treatment, ammonium chloride concentration is that the middle concentration waste water of 3.5%-8.0% first feeds electrodialysis (ED) device and carries out concentration, and the fresh water water outlet of separating out enters seawater desalination reverse osmosis film (SWRO) device again; The low concentration wastewater of concentration≤3.5% is introduced into seawater desalination reverse osmosis film (SWRO) device and carries out desalting treatment, and the dense water water outlet of the concentration 5.0-7.0% that seawater desalination reverse osmosis (SWRO) is discharged enters electrodialysis (ED) device again and carries out concentration; Ammonium salt waste water finally makes concentrated solution ammonium chloride concentration be promoted to 14.0-15.0% after processing by electrodialysis and reverse osmosis equipment combination process, and the volume of concentrated solution is down to the 10.0-50.0% of raw wastewater volume, send subsequent processing to carry out evaporation concentration processing; The fresh water that seawater desalination reverse osmosis film (SWRO) device opposite side is discharged is that the desalination rate of recovery of purifying waste water is 50-70%, and the desalination that this seawater desalination reverse osmosis film (SWRO) device gives is purified waste water and returned to production system reuse or further after desalting and purifying processing, return to production system recycle.
(3) the evaporative crystallization processing of high strength ammonium-chloride wastewater and concentrated solution
By above-mentioned with the concentrated ammonium chloride concentrated solution obtaining of electrodialysis (ED) equipment and the merging of pretreated high strength ammonium-chloride wastewater, after being 4.5 with salt acid for adjusting pH value, feed steam mechanical compression cycle evaporation (MVR) equipment or multiple-effect evaporation (EM) equipment and carry out evaporation concentration processing, while being concentrated into state of saturation, ammonium chloride salt solution is cooled to 30-50 DEG C, a part of chlorination ammonium salt is separated out with the form of solid crystal, after the ammonium chloride of crystallization is dry with centrifuge dewatering, make ammonium chloride product, ammonium chloride filtrate is after mother liquor preheating, to turn back to vapo(u)rization system to continue concentration, after the distilled water condensation of MVR evaporation equipment or multifunctional evaporating equipment output, direct or further desalting and purifying returns to production system recycle after processing.
(4) purify waste water and the distilled water of MVR evaporation equipment or multiple-effect evaporation (EM) equipment output with the desalination that seawater desalination reverse osmosis film (SWRO) device gives above-mentioned, adopt ordinary RO membrane (RO) to install further desalting and purifying processing, make the higher industrial pure water recycle that Rare Earth Production requires that meets; The dense water of saliferous that ordinary RO membrane (RO) device produces returns to a processing unit again and continues desalting treatment.
The present invention compared with prior art tool has the following advantages:
1, technical maturity is stable, processing cost is lower, production equipment is compact, easily simple to operately be automated control.
2, high, the stable effluent quality of waste water reclamation rate, non-secondary pollution discharge of wastewater, having realized the zero release of waste water administers, utilize chemical precipitation and membrane concentration pretreatment combination size treatment process middle low concentration ammonium chloride wastewater to be concentrated and isolated the technique pure water that can meet reuse standard, in effectively reducing in low concentration ammonium chloride wastewater processing costs, reduce the volume of waste water evaporation concentration, reduce the heat energy consumption of waste water vaporizer, and reduced the frequency that fouling of evaporator cleans, strengthen the effects of energy conservation and environmental protection of waste water treatment process.
3, when waste water obtains effectively administering, the desalination of reclaiming reusable edible is purified waste water, pure water and agricultural ammonium chloride product for technique, the cost that can balance out wastewater treatment obtains economic return, can solve various concentration ammonium chloride waste-waters and other problems that similarly trade effluent is difficult to low cost, resource utilization recycling with it that rare-earth smelting produces.
Brief description of the drawings
Fig. 1 is the process flow diagram of combination treatment method of the present invention.
Fig. 2 is the process flow diagram of the embodiment of the present invention 1.
Fig. 3 is the process flow diagram of the embodiment of the present invention 2.
Fig. 4 is the process flow diagram of the embodiment of the present invention 3.
In Fig. 1, the ammonium chloride waste-water of different concns is entered respectively in different waste water and equalizing tank in, in pond, carry out oil removal, homogeneous, Air Exposure, again waste water is carried out to electricity flocculation breakdown of emulsion and air floatation machine dosing oil removing, then waste water enters pneumatic blending reaction tank, add ammoniacal liquor, the medicaments such as the soluble phosphates such as ammonium hydrogen phosphate are removed the calcium ions and magnesium ions in solution, then waste water enters coagulative precipitation tank and precipitates and isolates after solid slag, in pond, keep ageing in 2-3 hour that the insoluble substance in water is fully separated out, supernatant liquor enters multi-medium filtering again, activated carbon filtration, UF ultrafiltration and NF nanofiltration membrane are filtered pretreatment process, carry out concentration by first feed electrodialysis (ED) equipment through the ammonium chloride waste-water of pre-treatment ammonium chloride concentration 3.5-8.0%, the fresh water water outlet of separating out enters seawater desalination reverse osmosis film (SWRO) equipment again, the ammonium chloride waste-water of concentration≤3.5% is introduced into seawater desalination reverse osmosis film (SWRO) equipment and carries out desalting treatment, desalination is purified waste water and is returned to production system reuse, and the dense water water outlet that gives concentration 5.0-7.0% enters electrodialysis (ED) equipment again and carries out concentration.When the concentrated dialysis water outlet containing ammonium chloride concentration of electrodialysis (ED) equipment is promoted to 14.0-15.0%, be 4.5 by ammonium chloride concentrated solution with hydrochloric acid adjust pH, with sending into MVR evaporation equipment after steam preheating or heat exchange or multifunctional evaporating equipment is proceeded evaporation concentration processing, the distilled water of output is desalination and purifies waste water and can be used as rare earth production technology water circulation use after heat exchange condensation; Or need to continue with common reverse osmosis (RO) equipment, to the deep desalting of purifying waste water, to make the technique pure water of requirements at the higher level according to production technique.The saturated ammonium chloride concentrated solution that vapo(u)rization system is discharged enters crystallizer after lowering the temperature by interchanger and carries out crystallization, and the chlorination ammonium salt crystallization whizzer of separating out dries also and sells as agrochemical after drying and dehydrating; After isolating the mother liquor of ammonium chloride crystals and distilled water heat exchange, turn back to vapo(u)rization system circulating and evaporating concentration.
Embodiment
Embodiment 1:
The NH4Cl waste water of concentration 3.5% is entered to wastewater equalization pond, and in equalizing tank, carries out oil removal, after homogeneous, aeration, continues to process in the following order (as shown in Figure 2):
A, carry out electricity flocculation breakdown of emulsion, air floatation machine dosing oil removal treatment, remove oily matter and suspended impurity in waste water;
B, waste water enter pneumatic blending reaction tank, with adding Secondary ammonium phosphate and activity charcoal powder in waste water, the calcium ions and magnesium ions in precipitate and separate waste water and heavy metal ion after ammoniacal liquor adjusting pH value 7.0-7.5; Waste water enters coagulative precipitation tank and ageing pond continues to process;
C, passing through more medium filter---active carbon filtering device adsorbs and filtration treatment;
D, UF ultrafiltration membrane treatment are removed the insoluble finely ground particles in waste water;
E, by NF nano-filtration membrane equipment remove high price zwitterion residual in waste water, part is removed monovalence zwitterion; The dope of discharging is back to intermediate regulations pond, produces water and feeds next processing unit;
F, water inlet are fed by the water outlet of NF nano-filtration membrane equipment, process through reverse osmosis membrane (SWRO) device, and dialysis water outlet is that desalination is purified waste water and sent the reuse of water unit; Concentrated solution concentration is increased to 5.0-7.0%, feeds next processing unit and continues concentration;
G, water inlet are installed dense water by seawater desalination reverse osmosis film (SWRO) and are fed, process through electrodialysis (ED) device, the light liquid of discharging turns back to (f) reverse osmosis membrane (SWRO) device, and it is concentrated that the 14.0-15.0% concentrated solution that electrodialysis (ED) device is discharged gives next processing unit to continue;
The light liquid that h, reverse osmosis membrane (SWRO) device give is that desalination is purified waste water, and enters common reverse osmosis (RO) device continuation desalination purification and obtains the reuse of technique pure water; The dense water that common reverse osmosis (RO) device produces turns back to anti-sea water desaltination permeable membrane (SWRO) device and continues concentration;
I, the concentrated solution of a upper processing unit (g) ammonium chloride concentration 14.0-15.0% is regulated to pH value is that 4.5 use MVR evaporation equipments or multifunctional evaporating equipment carry out evaporation concentration and crystallization treatment, obtains that desalination is purified waste water and ammonia chloride crystal.
Embodiment 2:
The NH4Cl waste water that contains of concentration 5.5% is entered to the wastewater equalization pond of independent setting, and in equalizing tank, carries out oil removal, homogeneous, aeration, then process in the following order (as shown in Figure 3):
A, carry out electricity flocculation breakdown of emulsion, air floatation machine oil removal treatment, remove oily matter, calcium ions and magnesium ions and suspended substance in waste water;
B, waste water enter agitating reaction pond processing, to add carbon ammonium to regulate pH value be 7.0, continue to add soluble phosphate, activity charcoal powder to remove calcium ions and magnesium ions, oily matter and heavy metal ion in waste water in waste water, and waste water enters coagulative precipitation tank and isolates throw out and other solid impurities;
C, waste water after 3 hours, enter more medium filter in coagulative precipitation tank sedimentation---and active carbon filtering device carries out degree of depth absorption and filtration treatment;
D, UF ultrafiltration membrane treatment are removed the insoluble finely ground particles in waste water;
E, remove residual high price zwitterion in waste water by NF nano-filtration membrane equipment; The dope of discharging is back in equalizing tank, and nanofiltration water outlet feeds electrodialysis process;
F, NF nano-filtration membrane equipment processing water outlet enter electrodialysis (ED) device and carry out desalination and concentration, discharge≤2% light liquid of this equipment feeds seawater desalination reverse osmosis film (SWRO) device, after the containing ammonium chloride concentrated solution concentrate to 14.0% that electrodialysis (ED) device is discharged, send into next processing unit and continue concentrated;
The fresh water that g, electrodialysis (ED) device are discharged enters seawater desalination reverse osmosis film (SWRO) device, and the desalination that seawater desalination reverse osmosis film (SWRO) gives is purified waste water and sent production system reuse; When dense water saltiness >=3.5%, return to electrodialysis (ED) device (f) and continue concentrated;
H, the 14.0% chlorination ammonium salt concentrated solution that electrodialysis (ED) device is discharged, after regulating pH value to be 4.0, send into MVR evaporation equipment and carry out evaporation concentration and crystallization with hcl acidifying; Obtain that desalination is purified waste water and ammonia chloride crystal;
I, with whizzer, the above-mentioned ammonium chloride crystals thing making is dewatered and dries after, make agricultural ammonium chloride finished product.
Embodiment 3:
By concentration 15% enter the wastewater equalization pond of independent setting containing NH4Cl waste water, and in equalizing tank, carry out oil removal, cool, homogeneous, Air Exposure, then process in the following order (as shown in Figure 4):
A, carry out electricity flocculation breakdown of emulsion, oil removal by air bubbling processing, remove oily matter, calcium ions and magnesium ions and suspended substance in waste water;
B, waste water enter agitating reaction pond, after adding ammoniacal liquor to regulate pH value 7.0-7.5, in waste water, add soluble phosphate and activated carbon powder to remove calcium ions and magnesium ions, oily matter and heavy metal ion, enter coagulative precipitation tank and carry out precipitation reaction, keep sufficient residence time ripening;
C, passing through more medium filter---active carbon filtering device carries out degree of depth absorption and filtration treatment;
D, UF ultrafiltration membrane treatment are removed the insoluble finely ground particles in waste water;
E, by NF nano-filtration membrane equipment remove high price zwitterion residual in waste water, part is removed monovalence zwitterion; The dope of discharging is back to equalizing tank, produces water and feeds next processing unit;
F, the water outlet of NF nano-filtration membrane equipment regulate behind pH value≤4.5 with hcl acidifying, feed MVR evaporation equipment and carry out evaporation concentration and crystallization; Obtain that desalination is purified waste water and ammonia chloride crystal.