CN110776128B - Rare earth wastewater treatment and recovery process - Google Patents
Rare earth wastewater treatment and recovery process Download PDFInfo
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- CN110776128B CN110776128B CN201810855112.3A CN201810855112A CN110776128B CN 110776128 B CN110776128 B CN 110776128B CN 201810855112 A CN201810855112 A CN 201810855112A CN 110776128 B CN110776128 B CN 110776128B
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 90
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 77
- 238000011084 recovery Methods 0.000 title claims abstract description 32
- 238000004065 wastewater treatment Methods 0.000 title claims abstract description 12
- 238000001728 nano-filtration Methods 0.000 claims abstract description 90
- 239000002351 wastewater Substances 0.000 claims abstract description 73
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 claims abstract description 29
- 239000000706 filtrate Substances 0.000 claims abstract description 28
- 238000000108 ultra-filtration Methods 0.000 claims abstract description 21
- 238000001914 filtration Methods 0.000 claims abstract description 19
- -1 rare earth ions Chemical class 0.000 claims abstract description 17
- 239000006004 Quartz sand Substances 0.000 claims abstract description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000007788 liquid Substances 0.000 claims abstract description 7
- 239000012528 membrane Substances 0.000 claims description 75
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 53
- 238000000034 method Methods 0.000 claims description 26
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 24
- 230000008569 process Effects 0.000 claims description 23
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 18
- 229910021529 ammonia Inorganic materials 0.000 claims description 17
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 15
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 claims description 13
- 229910000162 sodium phosphate Inorganic materials 0.000 claims description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 239000003513 alkali Substances 0.000 claims description 12
- 238000010521 absorption reaction Methods 0.000 claims description 11
- 230000004907 flux Effects 0.000 claims description 11
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- 239000011148 porous material Substances 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 7
- 230000002745 absorbent Effects 0.000 claims description 6
- 239000002250 absorbent Substances 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 6
- 229910052564 epsomite Inorganic materials 0.000 claims description 6
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 claims description 6
- 239000002033 PVDF binder Substances 0.000 claims description 5
- 239000004743 Polypropylene Substances 0.000 claims description 5
- 239000000835 fiber Substances 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 5
- 239000012982 microporous membrane Substances 0.000 claims description 5
- 235000006408 oxalic acid Nutrition 0.000 claims description 5
- 229920002401 polyacrylamide Polymers 0.000 claims description 5
- 229920001155 polypropylene Polymers 0.000 claims description 5
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 5
- 238000005086 pumping Methods 0.000 claims description 5
- 238000004064 recycling Methods 0.000 claims description 5
- 239000013049 sediment Substances 0.000 claims description 5
- 238000004062 sedimentation Methods 0.000 claims description 5
- 239000002585 base Substances 0.000 claims 1
- CVTZKFWZDBJAHE-UHFFFAOYSA-N [N].N Chemical compound [N].N CVTZKFWZDBJAHE-UHFFFAOYSA-N 0.000 abstract description 8
- 238000009287 sand filtration Methods 0.000 abstract description 4
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 239000002699 waste material Substances 0.000 abstract description 3
- 238000009776 industrial production Methods 0.000 abstract description 2
- 238000012545 processing Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 13
- 239000000126 substance Substances 0.000 description 8
- 238000011161 development Methods 0.000 description 4
- 238000001471 micro-filtration Methods 0.000 description 4
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 238000003723 Smelting Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000009388 chemical precipitation Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005374 membrane filtration Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/16—Nature of the water, waste water, sewage or sludge to be treated from metallurgical processes, i.e. from the production, refining or treatment of metals, e.g. galvanic wastes
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention discloses a rare earth wastewater treatment and recovery process, wherein the rare earth wastewater is filtered by a quartz sand filter, a microporous filter and an ultrafiltration device, and then the rare earth and nitrogen ammonia are enriched, recovered, absorbed by nitrogen ammonia and the like, so that the enrichment of rare earth ions and nitrogen ammonia in the rare earth wastewater, the recovery of the rare earth ions and nitrogen ammonia and the standard-reaching discharge of the wastewater are realized; according to the invention, the enrichment of rare earth and nitrogen ammonia in the waste liquid is realized through the nanofiltration device, the processing load of rare earth and nitrogen ammonia recovery is reduced, the recovery energy consumption is reduced, and the recovery efficiency and recovery rate are improved; ammonia nitrogen is recovered through air stripping and dosing of the filtrate, so that the recovery rate of ammonia nitrogen is improved; the invention realizes the stability of the whole filtering system through three-stage filtration of quartz sand filtration, microporous filtration and ultrafiltration; the rare earth wastewater treatment and recovery process is simple to operate, low in treatment cost and easy to realize industrial production.
Description
Technical Field
The invention relates to the field of rare earth wastewater treatment, in particular to a rare earth wastewater treatment and recovery process.
Background
Although the rare earth resources in China are wide in distribution, abundant in reserves and complete in rare earth types, a solid foundation is laid for the development of the rare earth industry in China, in the development process, the rare earth industry in China has many problems, a large amount of wastewater is generated in the rare earth smelting process, the wastewater contains a large amount of rare earth elements and ammonia nitrogen, if the rare earth is not effectively treated in time, the waste of precious rare earth resources is caused, and the serious environmental pollution is caused. The rare earth wastewater has large amount, complex components and a large amount of pollutants, the problem of wastewater pollution in rare earth smelting is prominent day by day, and the rare earth wastewater becomes an important influence factor for restricting the development of rare earth industry. The further development of the rare earth industry needs to solve the problems of the recovery of rare earth in rare earth wastewater and the treatment of wastewater as early as possible.
The invention patent CN 102260000B provides an ammonium chloride rare earth wastewater treatment and recycling process, the process enriches ammonia nitrogen in wastewater through DEP microfiltration and DEP nanofiltration, and then carries out electrolysis, the process easily causes the reduction or blockage of the filtration rate of a DEP microfiltration membrane and a DEP nanofiltration membrane in the process of enriching the nitrogen and the ammonia, and the energy consumption is larger when the ammonia nitrogen wastewater is electrolyzed.
The invention patent CN 101987767B provides a method for producing high ammonia nitrogen high salinity wastewater by membrane integrated treatment of rare earth, after pretreatment of wastewater, the wastewater is primarily filtered by a disc filter, enters a stripping device, and enters a membrane separation device after being recovered with removed ammonia gas, wherein produced water is recycled, and concentrated solution returns to the previous stripping device to recover the removed ammonia gas, and then returns to the membrane separation step again. The membrane group used by the invention needs to be frequently replaced, the cost is high, and the rare earth element in the wastewater can not be recovered.
The rare earth process wastewater has large production amount, the ammonia nitrogen and rare earth contained in the rare earth process wastewater have high concentration, the rare earth ammonia nitrogen wastewater is treated by a plurality of methods, each method is used for treating the rare earth ammonia nitrogen wastewater independently, and the quality of the treated effluent cannot meet the relevant standard limit value or the operating cost is too high.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a process for treating and recycling rare earth wastewater, which has the advantages of low treatment cost, high ammonia nitrogen removal and high rare earth recovery.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a process for treating and recycling rare earth wastewater comprises the following steps:
(1) treating the rare earth wastewater by a quartz sand filter, a microporous filter and an ultrafiltration device in sequence to obtain rare earth wastewater without solid suspended matters and small granular substances;
(2) carrying out nanofiltration on the wastewater obtained by the treatment of the step (1) to obtain a concentrated solution and a filtered solution;
(3) and (3) recovering rare earth: adding the concentrated solution into a sedimentation tank, adding sulfuric acid to adjust the pH value to 2-3, then adding oxalic acid to generate sediment in the concentrated solution, and filtering to obtain precipitated rare earth;
(4) ammonia nitrogen recovery: adding a certain amount of alkali into the filtered solution, adjusting the pH value of the filtered solution to 9-10, heating the filtered solution to 35-45 ℃, pumping the filtered solution into a stripping tower, controlling the pressure in the tower to be 0.01-0.05MPa, controlling the stripping gas-liquid ratio to be (4000 plus 5000):1, controlling the stripping time to be 2-4h, introducing the stripped ammonia gas into an ammonia gas absorption tower, and selecting an ammonia gas absorbent in the ammonia gas absorption tower as sulfuric acid; adding MgSO (MgSO) into the filtrate after stripping4·7H2O and NaH2PO4·2H2O, removing ammonia nitrogen in the filtrate;
(5) mixing the concentrated solution and the filtered solution treated in the steps (3) and (4), and treating by a nanofiltration device to obtain standard wastewater;
adjusting the pH of the wastewater treated in the step (1) to 3-4 by acid or alkali, and then performing the operation of the step (2);
the membrane group of the nanofiltration device in the step (2) is three-stage nanofiltration, wherein the aperture of the first-stage nanofiltration membrane is 3-4nm, the aperture of the second-stage nanofiltration membrane is 1.5-3nm, and the aperture of the third-stage nanofiltration membrane is 1-2 nm;
the aperture of the nanofiltration membrane of the nanofiltration device in the step (5) is 1-2 nm;
furthermore, the pore diameter of the microporous membrane of the microporous filter is 0.1-0.4 μm, and the material is polypropylene material; the aperture of the ultrafiltration membrane of the ultrafiltration device is 0.01-0.03 mu m, and the material is polyvinylidene fluoride material.
Further, the nanofiltration membrane of the nanofiltration device in the step (2) is made of polyacrylamide, and is enhanced by fiber embedding, and the contact angle is 20-40 degrees.
Further, the nanofiltration device in the step (2) has a membrane flux of 3-5L/m2H; the pressure is 0.25-0.4MPa, the temperature is 10-50 deg.C, and the temperature is preferablyIs 25-30 ℃.
Further, the nanofiltration membrane in the step (2) requires that the number of pores with limited pore size accounts for more than 85% of the number of pores of the whole nanofiltration membrane.
Further, in the step (4), the alkali is at least one of NaOH and KOH.
Further, the MgSO4·7H2O and NaH2PO4·2H2The molar weight of O added is the same; the MgSO4·7H2The molar weight of the added O is the same as the molar weight of the nitrogen and the ammonia in the filtered solution after the stripping in the step (4).
According to the invention, large granular substances and suspended substances, small granular substances and solid suspended substances, microorganisms and the like in the wastewater can be removed through three-stage filtration of quartz sand filtration, microporous filtration and ultrafiltration, so that substances visible to naked eyes are basically removed, the whole filtration system can be more stable through the three-stage filtration, and a more stable wastewater environment (pressure) is provided for the next nanofiltration.
The nanofiltration device consists of three stages of nanofiltration membranes with different membrane apertures, so that the wastewater can be rapidly filtered, the rare earth ions with larger sizes preferentially enter the concentrated solution at the first stage of nanofiltration membrane, the smaller rare earth ions enter the concentrated solution at the second stage of nanofiltration membrane, the filtration pressure of the nanofiltration membranes is reduced during the operation of the device, the filtration pressure of 0.25-0.4MPa is selected, the separation of the rare earth ions and ammonia nitrogen ions can be well realized, the mechanical damage of the membranes is reduced, and the service life of the membranes is prolonged.
The pH value of the wastewater is adjusted to 3-4 during nanofiltration, so that the interception of rare earth ions on the nanofiltration membrane can be well realized, the device can stably operate for a long time under the pH value, and the change of the membrane flux is small. The temperature of the wastewater has great influence on the size of trapped substances, the trapping rate of the filter membrane is reduced when the temperature is too high, and the nanofiltration membrane is easy to collapse and damage; if the temperature is too low, the rejection rate of the filter membrane can be increased, so that the filtration pressure is increased, and if the pressure is too high, the mechanical damage of the nanofiltration membrane can occur, so that the temperature is preferably 25-30 ℃.
In the ammonia nitrogen recovery step, the ammonia absorption tower uses sulfuric acid as an absorbent, and the sulfuric acid is combined with the blown ammonia to form ammonium sulfate.
Adding MgSO (MgSO) into the filtrate after stripping4·7H2O and NaH2PO4·2H2O, and NH4 +React to form MgNH4PO4·6H2And (3) precipitating, removing ammonia nitrogen in the filtrate, and when the pH value is 9-10, the solubility of the precipitate is relatively low, so that the precipitate is easy to realize.
Due to the adoption of the technical scheme, the invention has the beneficial effects that:
the invention realizes the enrichment of rare earth ions and nitrogen and ammonia in the rare earth wastewater, the recovery of the rare earth ions and the nitrogen and ammonia and the standard-reaching discharge of the wastewater; according to the invention, the enrichment of rare earth and nitrogen ammonia in the waste liquid is realized through the nanofiltration device, the processing load of rare earth and nitrogen ammonia recovery is reduced, the recovery energy consumption is reduced, and the recovery efficiency and recovery rate are improved; ammonia nitrogen is recovered through air stripping and dosing of the filtrate, so that the recovery rate of ammonia nitrogen is improved; the invention realizes the stability of the whole filtering system through three-stage filtration of quartz sand filtration, microporous filtration and ultrafiltration; the rare earth wastewater treatment and recovery process is simple to operate, low in treatment cost and easy to realize industrial production.
Detailed Description
The present invention will be further described with reference to examples, but the present invention is not limited to these examples.
Ammonia nitrogen concentration of rare earth wastewater treated by examples and comparative examples: 10176mg/L, rare earth concentration: 41.29mg/L, COD: 179 mg/L.
Example 1
A rare earth wastewater treatment and recovery process comprises the following steps:
(1) treating the rare earth wastewater by a quartz sand filter, a microporous filter and an ultrafiltration device in sequence to obtain rare earth wastewater without solid suspended matters and small particulate matters;
the pore diameter of the microporous membrane of the microporous filter is 0.1-0.2 mu m, and the material is a polypropylene material; the aperture of the ultrafiltration membrane of the ultrafiltration device is 0.01-0.02 mu m, and the material is polyvinylidene fluoride material.
(2) Adjusting the pH value of the wastewater to 3 by acid or alkali, and then obtaining concentrated solution and filtered solution by a nanofiltration device;
the membrane group of the nanofiltration device is three-stage nanofiltration, wherein the aperture of a first-stage nanofiltration membrane is 3-4nm, the aperture of a second-stage nanofiltration membrane is 1.5-3nm, and the aperture of a third-stage nanofiltration membrane is 1-2 nm;
the nanofiltration membrane of the nanofiltration device is made of polyacrylamide and is enhanced by fiber embedding, and the contact angles of the three-stage nanofiltration membrane are 23 degrees, 31 degrees and 40 degrees respectively;
the nanofiltration device has a membrane flux of 3L/m2H; the pressure is 0.25MPa, the temperature is 25 ℃,
(3) and (3) recovering rare earth: and adding the concentrated solution into a sedimentation tank, adding sulfuric acid to adjust the pH value to 3, then adding oxalic acid to generate sediment in the concentrated solution, and filtering to obtain the precipitated rare earth.
(4) Ammonia nitrogen recovery: adding a certain amount of alkali (NaOH) into the filtrate, adjusting the pH value of the filtrate to 10, heating the filtrate to 45 ℃, pumping the filtrate into a stripping tower, introducing stripped ammonia into an ammonia absorption tower, wherein the pressure in the tower is 0.05MPa, the stripping gas-liquid ratio is 5000:1, and the stripping time is 4h, and the ammonia absorbent selected by the ammonia absorption tower is sulfuric acid; adding MgSO (MgSO) into the filtrate after stripping4·7H2O and NaH2PO4·2H2O, removing ammonia nitrogen in the filtrate;
the MgSO4·7H2O and NaH2PO4·2H2The molar weight of O added is the same; monitoring the content of nitrogen and ammonia in the filtrate after stripping in real time, and adding MgSO4·7H2The molar weight of O is the same as that of ammonia nitrogen in the wastewater.
(5) And (4) mixing the concentrated solution and the filtered solution treated in the steps (3) and (4), and treating by using a nanofiltration device with a nanofiltration membrane aperture of 1-2nm to obtain the standard-reaching wastewater.
In the step (2) of the present example, the nanofiltration device has a membrane flux of 3L/m2H; the pressure is 0.25MPa, the waste water temperature is 25 ℃, the operation time is 15 days, and 3L/m is ensured2H membrane flux, no large pressure change.
Example 2
A rare earth wastewater treatment and recovery process comprises the following steps:
(1) treating the rare earth wastewater by a quartz sand filter, a microporous filter and an ultrafiltration device in sequence to obtain rare earth wastewater without solid suspended matters and small particulate matters;
the pore diameter of the microporous membrane of the microporous filter is 0.2-0.3 mu m, and the material is a polypropylene material; the aperture of the ultrafiltration membrane of the ultrafiltration device is 0.02-0.03 mu m, and the material is polyvinylidene fluoride material.
(2) Adjusting the pH value of the wastewater to 3.5 by acid or alkali, and then obtaining concentrated solution and filtered solution by a nanofiltration device;
the membrane group of the nanofiltration device is three-stage nanofiltration, wherein the aperture of a first-stage nanofiltration membrane is 3-4nm, the aperture of a second-stage nanofiltration membrane is 1.5-3nm, and the aperture of a third-stage nanofiltration membrane is 1-2 nm;
the nanofiltration membrane of the nanofiltration device is made of polyacrylamide and is enhanced by fiber embedding, and the contact angles of the three-stage nanofiltration membrane are respectively 23 degrees, 31 degrees and 40 degrees;
the nanofiltration device has a membrane flux of 5L/m2H; the pressure is 0.4MPa, the temperature is 10 ℃,
(3) and (3) recovering rare earth: and adding the concentrated solution into a sedimentation tank, adding sulfuric acid to adjust the pH value to 2.5, then adding oxalic acid to generate sediment in the concentrated solution, and filtering to obtain the precipitated rare earth.
(4) Ammonia nitrogen recovery: adding a certain amount of alkali (KOH) into the filtrate, adjusting the pH value of the filtrate to 9.5, heating the filtrate to 35 ℃, pumping the filtrate into a stripping tower, introducing ammonia gas stripped from the stripping tower into an ammonia gas absorption tower, wherein the pressure in the tower is 0.01MPa, the gas-liquid ratio of stripping is 4500:1, and the stripping time is 2 hours, and the ammonia gas absorbent selected by the ammonia gas absorption tower is sulfuric acid; adding MgSO (MgSO) into the filtrate after stripping4·7H2O and NaH2PO4·2H2O, removing ammonia nitrogen in the filtrate;
the MgSO4·7H2O and NaH2PO4·2H2The molar weight of O added is the same; monitoring the content of nitrogen and ammonia in the filtrate after stripping in real time, and adding MgSO4·7H2Molar weight of O and mol of ammonia nitrogen in wastewaterThe amounts were the same.
(5) And (4) mixing the concentrated solution and the filtered solution treated in the steps (3) and (4), and treating by using a nanofiltration device with a nanofiltration membrane aperture of 1-2nm to obtain the standard-reaching wastewater.
Example 3
A rare earth wastewater treatment and recovery process comprises the following steps:
(1) treating the rare earth wastewater by a quartz sand filter, a microporous filter and an ultrafiltration device in sequence to obtain rare earth wastewater without solid suspended matters and small granular substances;
the pore diameter of the microporous membrane of the microporous filter is 0.3-0.4 mu m, and the material is a polypropylene material; the aperture of the ultrafiltration membrane of the ultrafiltration device is 0.01-0.02 mu m, and the material is polyvinylidene fluoride material.
(2) Adjusting the pH value of the wastewater to 4 by acid or alkali, and then obtaining concentrated solution and filtered solution by a nanofiltration device;
the membrane group of the nanofiltration device is three-stage nanofiltration, wherein the aperture of a first-stage nanofiltration membrane is 3-4nm, the aperture of a second-stage nanofiltration membrane is 1.5-3nm, and the aperture of a third-stage nanofiltration membrane is 1-2 nm;
the nanofiltration membrane of the nanofiltration device is made of polyacrylamide and is enhanced by fiber embedding, and the contact angles of the three-stage nanofiltration membrane are respectively 23 degrees, 31 degrees and 40 degrees;
the membrane flux of the nanofiltration device is 4L/m2H; the pressure is 0.3MPa, the temperature is 50 ℃,
(3) and (3) recovering rare earth: and adding the concentrated solution into a sedimentation tank, adding sulfuric acid to adjust the pH value to 2, then adding oxalic acid to generate sediment in the concentrated solution, and filtering to obtain the precipitated rare earth.
(4) Ammonia nitrogen recovery: adding a certain amount of alkali (NaOH) into the filtrate, adjusting the pH value of the filtrate to 9, heating the filtrate to 40 ℃, pumping the filtrate into a stripping tower, introducing ammonia gas stripped from the tower into an ammonia gas absorption tower, wherein the pressure in the tower is 0.03MPa, the gas-liquid ratio of the stripping is 4000:1, and the stripping time is 3 hours, and the ammonia gas absorbent selected from the ammonia gas absorption tower is sulfuric acid; adding MgSO (MgSO) into the filtrate after stripping4·7H2O and NaH2PO4·2H2O, removing ammonia in filtrateNitrogen;
the MgSO4·7H2O and NaH2PO4·2H2The molar weight of O added is the same; monitoring the nitrogen and ammonia content in the filtered solution after stripping in real time, and adding MgSO4·7H2The molar weight of O is the same as that of ammonia nitrogen in the wastewater.
(5) And (4) mixing the concentrated solution and the filtered solution treated in the steps (3) and (4), and treating by using a nanofiltration device with a nanofiltration membrane aperture of 1-2nm to obtain the standard-reaching wastewater.
Comparative example 1
The process for treating and recovering rare earth wastewater is the same as that in example 1, except that the wastewater in the step (1) is directly subjected to microfiltration and ultrafiltration without passing through a quartz sand filter.
The microporous filter was clogged after 2 days of operation.
Comparative example 2
The process for treating and recovering rare earth wastewater is the same as that in example 1, except that in step (1), the wastewater is not subjected to ultrafiltration, but is subjected to quartz sand filtration and microfiltration.
The nanofiltration device in the step (2) of the comparative example has the membrane flux of 3L/m2H, the pressure is 0.25MPa, the operation is stable for 3 days under the wastewater temperature of 25 ℃, and 3L/m is ensured2H membrane flux, pressure reached 0.8MPa after 7 days of operation.
Comparative example 3
The process for treating and recovering rare earth wastewater is the same as that of example 1, except that the pH of the wastewater is adjusted to 6 by an acid or an alkali in the step (2).
Comparative example 4
The process for treating and recovering the rare earth wastewater is the same as that in the example 1, the difference is that the nanofiltration device only carries out nanofiltration membrane filtration once in the step (2), and the aperture of the nanofiltration membrane is 1-2 nm.
The nanofiltration device in the step (2) of the comparative example has the membrane flux of 3L/m2H, the pressure reached 0.7MPa after 5 days of operation at a wastewater temperature of 25 ℃.
Comparative example 5
The process for treating and recovering the rare earth wastewater is the same as that in the example 1, the difference is that the nanofiltration device only carries out nanofiltration membrane filtration once in the step (2), and the aperture of the nanofiltration membrane is 3-4 nm.
Comparative example 6
The process for treating and recovering rare earth wastewater is the same as that in example 1, except that the nitrogen and ammonia recovery in the step (4) is carried out by blowing only without adding MgSO4·7H2O and NaH2PO4·2H2And O, carrying out chemical precipitation of ammonia nitrogen.
Comparative example 7
The process for treating and recovering rare earth wastewater is the same as that in example 1, except that the nitrogen and ammonia recovery in step (4) is carried out without stripping, and only MgSO (MgSO) is added4·7H2O and NaH2PO4·2H2And O, carrying out chemical precipitation of ammonia nitrogen.
Comparative example 8
The process for treating and recovering rare earth wastewater is the same as that of example 1, except that the pH of the filtrate in the step (4) is adjusted to 8.
Comparative example 9
The process for treating and recovering rare earth wastewater is the same as that of example 1, except that the nanofiltration operation of step (5) is not performed.
The results of treating the recovered rare earth wastewater by adopting the processes of the above examples and comparative examples are respectively as follows:
the above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention; those skilled in the art can make various changes, modifications and alterations without departing from the scope of the invention, and all equivalent changes, modifications and alterations to the disclosed technology are equivalent embodiments of the present invention; meanwhile, any changes, modifications, and evolutions of the equivalent changes of the above embodiments according to the actual techniques of the present invention are still within the protection scope of the technical solution of the present invention.
Claims (4)
1. The rare earth wastewater treatment and recovery process is characterized by comprising the following steps:
(1) treating the rare earth wastewater by a quartz sand filter, a microporous filter and an ultrafiltration device in sequence to obtain rare earth wastewater without solid suspended matters and small particulate matters;
(2) carrying out nanofiltration on the wastewater obtained by the treatment of the step (1) to obtain a concentrated solution and a filtered solution;
(3) and (3) recovering rare earth: adding the concentrated solution into a sedimentation tank, adding sulfuric acid to adjust the pH value to 2-3, then adding oxalic acid to generate sediment in the concentrated solution, and filtering to obtain precipitated rare earth;
(4) ammonia nitrogen recovery: adding a certain amount of alkali into the filtered solution, adjusting the pH value of the filtered solution to 9-10, heating the filtered solution to 35-45 ℃, pumping the filtered solution into a stripping tower, controlling the pressure in the tower to be 0.01-0.05MPa, controlling the stripping gas-liquid ratio to be (4000 plus 5000):1, controlling the stripping time to be 2-4h, introducing the ammonia gas stripped out into an ammonia gas absorption tower, and selecting an ammonia gas absorbent in the ammonia gas absorption tower as sulfuric acid; adding MgSO (MgSO) into the filtrate after stripping4·7H2O and NaH2PO4·2H2O, removing ammonia nitrogen in the filtrate;
(5) mixing the concentrated solution and the filtered solution treated in the steps (3) and (4), and treating by a nanofiltration device to obtain standard-reaching wastewater;
adjusting the pH of the wastewater treated in the step (1) to 3-4 by acid or alkali, and then performing the operation of the step (2);
the membrane group of the nanofiltration device in the step (2) is three-stage nanofiltration, wherein the aperture of the first-stage nanofiltration membrane is 3-4nm, the aperture of the second-stage nanofiltration membrane is 1.5-3nm, and the aperture of the third-stage nanofiltration membrane is 1-2 nm; the rare earth ions with larger sizes preferentially enter the concentrated solution at the first stage of the nanofiltration membrane, and the rare earth ions with smaller sizes enter the concentrated solution at the second stage of the nanofiltration membrane;
the aperture of the nanofiltration membrane of the nanofiltration device in the step (5) is 1-2 nm;
the nanofiltration membrane of the nanofiltration device in the step (2) is made of polyacrylamide, and is enhanced by fiber embedding, and the contact angle is 20-40 degrees;
the membrane flux of the nanofiltration device in the step (2) is 3-5L/m2H; the pressure is 0.25-0.4MPa, and the temperature is 10-50 ℃;
the nanofiltration membrane in the step (2) requires that the number of the holes with limited aperture size accounts for more than 85% of the number of the holes of the whole nanofiltration membrane.
2. The process for treating and recycling rare earth wastewater according to claim 1, wherein the microporous membrane of the microporous filter has a pore size of 0.1-0.4 μm and is made of polypropylene; the aperture of the ultrafiltration membrane of the ultrafiltration device is 0.01-0.03 mu m, and the material is polyvinylidene fluoride material.
3. The process for treating and recycling rare earth wastewater according to claim 1, wherein the base in step (4) is at least one of NaOH and KOH.
4. The process for treating and recovering rare earth wastewater as claimed in claim 1, wherein the MgSO4·7H2O and NaH2PO4·2H2The molar weight of O added is the same; the MgSO4·7H2The molar weight of the added O is the same as the molar weight of the nitrogen and the ammonia in the filtered solution after the stripping in the step (4).
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| WO2014044527A1 (en) * | 2012-09-18 | 2014-03-27 | Siemens Aktiengesellschaft | Method for obtaining at least one rare earth metal chloride and a rare earth metal |
| CN104724847A (en) * | 2013-12-18 | 2015-06-24 | 上海凯鑫分离技术有限公司 | Ion type rare earth mine runoff wastewater comprehensive treatment method |
| CN105293772A (en) * | 2015-11-17 | 2016-02-03 | 中国地质大学（武汉） | Method for recovering of rare earth and resource utilization of ammonia nitrogen from rare earth processing and smelting wastewater |
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| WO2014044527A1 (en) * | 2012-09-18 | 2014-03-27 | Siemens Aktiengesellschaft | Method for obtaining at least one rare earth metal chloride and a rare earth metal |
| CN104724847A (en) * | 2013-12-18 | 2015-06-24 | 上海凯鑫分离技术有限公司 | Ion type rare earth mine runoff wastewater comprehensive treatment method |
| CN105293772A (en) * | 2015-11-17 | 2016-02-03 | 中国地质大学（武汉） | Method for recovering of rare earth and resource utilization of ammonia nitrogen from rare earth processing and smelting wastewater |
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