CN113023952A - Rare earth molten salt electrolysis fluorine-containing wastewater treatment method - Google Patents

Rare earth molten salt electrolysis fluorine-containing wastewater treatment method Download PDF

Info

Publication number
CN113023952A
CN113023952A CN202110314201.9A CN202110314201A CN113023952A CN 113023952 A CN113023952 A CN 113023952A CN 202110314201 A CN202110314201 A CN 202110314201A CN 113023952 A CN113023952 A CN 113023952A
Authority
CN
China
Prior art keywords
fluorine
containing wastewater
calcium
rare earth
molten salt
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202110314201.9A
Other languages
Chinese (zh)
Inventor
李亮亮
张永健
崔红岩
钟希辉
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujian Changting Jinlong Rare Earth Co Ltd
Original Assignee
Fujian Changting Jinlong Rare Earth Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fujian Changting Jinlong Rare Earth Co Ltd filed Critical Fujian Changting Jinlong Rare Earth Co Ltd
Priority to CN202110314201.9A priority Critical patent/CN113023952A/en
Publication of CN113023952A publication Critical patent/CN113023952A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • 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
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
    • C02F1/56—Macromolecular compounds
    • 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
    • C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
    • C02F1/583—Treatment of water, waste water, or sewage by removing specified dissolved compounds by removing fluoride or fluorine compounds
    • 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
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • 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
    • 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
    • C02F2101/12—Halogens or halogen-containing compounds
    • C02F2101/14—Fluorine or fluorine-containing compounds

Landscapes

  • 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)
  • Removal Of Specific Substances (AREA)

Abstract

The invention relates to a method for treating fluorine-containing wastewater by electrolyzing rare earth molten salt, which adopts continuous operation of a double calcium method, coagulation, flocculation and precipitation and can control the concentration of fluorine ions in the high-concentration fluorine-containing wastewater to be below 8 mg/L. On one hand, the method thoroughly solves the problem of easy pipe blockage in industrial production and can realize continuous long-time operation; on the other hand, the efficiency of removing the fluorine ions is further improved, and the treatment cost is reduced. The invention has the advantages of simple process flow, high defluorination efficiency, low treatment cost and easy sludge sedimentation, and is particularly suitable for industrial production.

Description

Rare earth molten salt electrolysis fluorine-containing wastewater treatment method
Technical Field
The invention belongs to the technical field of rare earth materials, relates to a method for treating wastewater generated in rare earth molten salt electrolysis production, and particularly relates to a process for treating high-concentration fluorine-containing wastewater.
Background
The electrolytic rare earth takes rare earth fluoride as molten salt, in the electrolytic process, part of fluoride can volatilize out along with electrolytic flue gas, after dust removal by a dust removal system, the flue gas enters a spray tower, fluorine-containing waste gas is dissolved into aqueous hydrogen fluoride or aqueous sodium fluoride through a water washing and alkali washing process and enters a wastewater treatment station, part of unorganized discharged fluoride can be washed by rainwater to enter an initial rainwater collecting tank of a plant area, and finally enters the wastewater treatment station, the concentration of fluorine ions in the produced wastewater is higher and is mostly more than 5000mg/L, and according to the discharge standard of rare earth industrial pollutants (GB 26451 and 2011), the maximum allowable value of the discharged fluoride (measured by F) of sewage of a newly-built enterprise is 8 mg/L.
In general, when the fluorine-containing concentration of the wastewater is high, a calcium salt precipitation method, namely a lime precipitation method, can be adopted. The lime precipitation method is a classical process for treating high-concentration fluorine-containing wastewater, and calcium ions and fluorine ions are utilized to generate CaF2 precipitate so as to remove the fluorine ions. The lime is cheap and the treatment method is simple, but the problems of poor treatment effect, difficult standard reaching of the concentration of fluorine ions in the effluent, low effective utilization rate of the lime and the like exist. The main reason is that lime has low solubility and is generally added in the form of lime milk, and the generated CaF2 precipitate is coated on the outer surface of lime particles, so that lime cannot be further dissolved, and sufficient calcium ions are difficult to provide in the solution. Solubility product constant K of calcium fluoride at 25 DEG Csp＝3.98×10-11，When the molar ratio of Ca/F is 2:1 according to the stoichiometric number, the equilibrium concentration of the fluorine ions is 8.17 mg/L. However, in actual wastewater, other anions, such as Cl, are present-、NO3 -、SO4 2-Etc., which increase the solubility of calcium fluoride in water. Therefore, according to the homoionic effect, if a lower fluoride ion concentration (less than 10mg/L) is to be obtained, an excessive amount of calcium salt precipitator needs to be added. However, in the actual wastewater treatment process, even if excessive lime is added, the concentration of the fluorine ions in the effluent can only be reduced to about 15-20 mg/L due to the existence of other influencing factors.
On the other hand, the tube blockage phenomenon often occurs in the reaction vessel in the industrial production, which results in the increase of the cost.
Disclosure of Invention
The fluorine-containing wastewater is electrolyzed by rare earth molten salt, the fluorine content is about 3000-20000mg/L, and two technical problems exist in the prior art: firstly, the lime precipitation method defluorination process cannot reach the emission standard of 8 mg/L; secondly, the problem of pipe blockage often occurs in industrial production, which affects production and increases cost. Aiming at the removal of fluoride, the invention adopts a combined process of 'double calcium method + flocculation + coagulation + precipitation' to stabilize the fluorine content of the wastewater to be below 8mg/L and meet the requirement of environmental protection. Meanwhile, the invention thoroughly solves the problem of pipe blockage in industrial production and can realize continuous long-time operation.
In order to achieve the purpose, the invention provides a method for treating fluorine-containing wastewater generated by electrolyzing rare earth molten salt, which comprises the following steps:
(1) collecting the fluorine-containing wastewater, sending the fluorine-containing wastewater to a sedimentation tank, preliminarily settling suspended matters in the wastewater, and clarifying the water;
(2) sending the effluent of the sedimentation tank to a pH regulator, adding a calcium hydroxide solution or a calcium hydroxide solution and solid flake caustic soda or calcium hydroxide, solid flake caustic soda and solid calcium chloride, reacting for 30-40min, starting stirring, and controlling the pH value to be 8-10;
(3) and (3) delivering the effluent of the pH regulator to a calcium chloride reactor, wherein according to the molar ratio of fluorine ions to calcium ions of 1: (0.8-0.9) adding a calcium chloride solution, and starting stirring to promote further reaction of fluorine ions and calcium ions;
(4) delivering the effluent of the calcium chloride reactor to a polyaluminium chloride (PAC) reactor, adding a polyaluminium chloride solution for coagulation reaction, and stirring for 10-15 min;
(5) delivering the effluent of the polyaluminium chloride reactor to a Polyacrylamide (PAM) reactor, adding a polyacrylamide solution for flocculation reaction, wherein the reaction time is 10-15min, and the stirring mode is mechanical stirring;
(6) and (3) sending the effluent of the polyacrylamide reactor to a sedimentation tank, wherein the sedimentation time is 10-15 min. Suspended particles are separated from water by gravity, and supernatant is stored in a clear water tower and discharged after reaching the standard.
Further, the calcium chloride is added in the step (2) according to the molar ratio of the fluorine ions to the calcium ions of 1 (0.5-0.6).
Further, the concentration range of the calcium hydroxide in the step (2) is 5-10g/L, and the concentration of the calcium chloride in the step (3) is 50-150 g/L.
Further, the concentration of the solution prepared by the polyaluminium chloride in the step (4) is 5-30 g/L; the concentration of the solution of the polyacrylamide in the step (5) is 0.3-1.5 g/L.
Further, the polyaluminium chloride in the step (4) can be replaced by flocculating agents such as aluminium sulfate, ferric sulfate, and poly activated silica gel.
Further, the polyacrylamide in the step (5) can be replaced by a coagulant aid such as polyacrylic acid, amphoteric polyacrylamide and the like.
Further, in the steps (2) to (4), pneumatic stirring is adopted, and mechanical stirring is assisted; and (5) mechanically stirring.
Further, the sedimentation tank in the step (1) adopts vertical flow sedimentation.
Compared with the prior art, the invention has the following beneficial technical effects:
(1) thoroughly solves the problem of pipe blockage in industrial production.
(2) From the actual production, the wastewater with large fluorine ion fluctuation and high fluorine ion content can be stably treated.
(3) Aiming at high-concentration fluorinion in the wastewater, the method uses a certain-concentration calcium hydroxide solution and solid caustic soda flakes to be added for adjusting the pH, and simultaneously adds solid calcium chloride, thereby achieving the purposes of adjusting the pH and initially reacting the fluorinion. The addition of calcium hydroxide solution in proper proportion can enhance the sedimentation performance of sludge, avoid sludge expansion and reduce the back-end treatment pressure.
(4) The water quality is balanced through the sedimentation tank, the fluctuation of fluorinion, suspended matters and the like in the water is reduced, and the relatively stable water quality is kept. Because the content of the rare earth in the precipitate is higher, the precipitated mud can be recycled, and the resources are saved.
(5) The pH regulator, the calcium chloride reactor and the polyaluminium chloride (PAC) reactor disturb the water body to generate velocity gradient or vortex by means of pneumatic stirring and mechanical stirring, so that particles are mutually collided and coalesced. A plurality of compressed air discharge ports are arranged at the bottom of the reactor at equal intervals, and the holes are upwards obliquely opened to ensure that the solution can be quickly turned over. Compared with the method only using mechanical stirring, the combined use of the pneumatic stirring and the mechanical stirring leads the related chemical reaction to be faster, the reaction to be more sufficient and quicker, the adverse problems of precipitation, pipe blockage and the like can not occur in the container, and the industrialized continuous operation can be realized.
(6) And a Polyacrylamide (PAM) treatment link is added, so that the settling speed of the sludge is further accelerated, and the water quality is clarified.
The effluent of the process flow can meet relevant discharge standards, meets the environmental protection requirement, and has relatively simple wastewater treatment flow, stable treatment result and strong operability.
Drawings
FIG. 1 is a process flow diagram of the fluorine-containing wastewater treatment method of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following drawings and specific examples so that those skilled in the art can better understand the present invention and can practice the present invention, but the examples are not intended to limit the present invention.
The fluorine-containing wastewater is electrolyzed by rare earth molten salt, the fluorine content is about 3000-20000mg/L, and the pH value is between 2 and 5 by adopting a potential analysis method for testing. The daily wastewater treatment capacity was about 10 cubic meters and the operating time was 10 hours per day. The fluorine-containing wastewater treatment method comprises the following specific steps:
step 1: and (3) collecting the fluorine-containing wastewater, sending the fluorine-containing wastewater to a sedimentation tank, preliminarily settling suspended matters in the wastewater, and clarifying the water quality.
Step 2: and (3) sending the effluent of the sedimentation tank to a pH value regulator, adding a calcium hydroxide solution and flaky sodium hydroxide, wherein the mass concentration of the added calcium hydroxide is 5-10g/L, and the influence of different calcium hydroxide concentrations on the defluorination effect is small in production. The addition of the calcium hydroxide solution in a proper proportion can enhance the sedimentation performance of the sludge and avoid the sludge bulking. The sodium hydroxide is added in a solid form, and mainly plays a role in assisting in adjusting the pH value, particularly when the pH value of the fluorine-containing wastewater is lower than 3. Compressed air is introduced into the regulator for stirring, so that the solubility of the calcium hydroxide and the flake caustic soda is improved, and mechanical stirring is added when necessary. The reaction time is 30-40min, the reaction cannot be fully carried out due to insufficient time, the reaction is more sufficient when the reaction time is longer, but 30-40min is the optimal choice in consideration of industrial efficiency.
The traditional process for adjusting the pH value of a solution by adding calcium hydroxide or caustic soda flakes in wastewater cannot well ensure the pH value of the solution, has large pH value fluctuation, and is mainly characterized in that fluorine-containing wastewater is weakly acidic wastewater, the process of weak acid ionization H + is slow, sufficient time is needed for sufficient ionization, and the fluorine-containing wastewater is pumped into a calcium chloride reactor by a water pump after the pH value is adjusted to be stable. Meanwhile, the pH value is adjusted by using the calcium hydroxide solution and the flake caustic soda in combination, so that the pH value of the wastewater can be adjusted, and the concentration of fluorine ions in the water can be further reduced.
When the concentration of fluoride ions is over 5000mg/L before wastewater treatment, calcium chloride solid is added according to the proportion that the molar ratio of fluoride ions to calcium ions is 1 (0.5-0.6), because the reaction of fluoride ions with high concentration needs longer time, if the fluoride ions are added only in the calcium chloride reaction tank in the step 3, the reaction time is not enough, and the flow rate of the calcium chloride solution is not well controlled. Calcium chloride is added in advance through the step 2, so that the fluorine ions are reduced to be below a certain concentration, and the subsequent treatment steps are stably carried out. After step 2, the concentration of fluoride ions can be reduced by more than 50%.
And step 3: the effluent of the pH value regulator is sent to a calcium chloride reactor, and 50-150g/L of calcium chloride solution is prepared. Calcium chloride is added according to the molar ratio of fluoride ions to calcium ions of 1 (0.8-0.9), and the reaction is carried out through pneumatic stirring, mechanical stirring is added when necessary, so that the fluoride ions and the calcium ions are fully reacted, the reaction time is 10-15min, the reaction time is insufficient, the defluorination effect is better when the reaction time is too long, and the efficiency of the whole wastewater treatment is not facilitated.
And 4, step 4: and (3) delivering the water discharged from the calcium chloride reactor to a PAC reactor, wherein the concentration of the added polyaluminum chloride solution is 5-30g/L, stirring the water body by using pneumatic stirring and mechanical stirring to generate a velocity gradient or vortex so as to promote the particles to collide and coalesce with each other, and the reaction time is 10-15 min.
In the factory production process, the aim of removing fluorine can be achieved by mechanical stirring and pneumatic stirring in the steps 2-4, but the problems of precipitation and pipe blockage can be easily caused by continuous treatment only by mechanical stirring.
And 5: and (3) delivering the effluent of the PAC reactor to a PAM reactor, adding polyacrylamide with the concentration of 0.3-1.5g/L, and mechanically stirring to form larger floccules on the particles for 10-15 min.
Step 6: and (4) delivering the PAM effluent to a sedimentation tank, mixing and flocculating to form flocculating constituents with larger particle sizes in suspended matters in water, and settling in a settling unit for 10-15 min. Suspended particles are separated from water by gravity, supernatant liquid is sent to a clean water pool, and fluorine ions are reduced to be within 8 mg/L. And finally pumping the sludge into a sludge tank and performing pressure filtration by a pressure filter.
Example 1
Fluorine-containing wastewater generated in the factory production process: the fluoride ion concentration is 7681mg/L and the pH is 3. The daily wastewater treatment capacity was about 10 cubic meters and the operating time was 10 hours per day. The fluorine-containing wastewater treatment method comprises the following specific steps:
step 1: the fluorine-containing wastewater is collected and sent to a sedimentation tank (the capacity is 8 cubic meters), suspended matters in the wastewater are preliminarily settled, and the water quality is clarified.
Step 2: and (3) sending the effluent of the sedimentation tank to a pH value regulator, adding a calcium hydroxide solution and flake sodium hydroxide, wherein the mass concentration of the added calcium hydroxide is 5g/L, adding 25kg of flake caustic soda and 25kg of calcium chloride solid, and introducing compressed air into the regulator for stirring, wherein the pressure of the compressed air is more than 0.2 MPa. In order to ensure that the fluorine ions and the calcium ions are fully reacted, mechanical stirring can be increased, the stirring speed is 100r/min, and the reaction time is 30-40 min. After this step was performed, the fluoride ion concentration was detected to decrease to 3850mg and the pH was 9.06.
And step 3: delivering the effluent of the pH value regulator to a calcium chloride reactor, adding calcium chloride according to the molar ratio of fluoride ions to calcium ions of 1 (0.8-0.9), preparing 500L of 10% calcium chloride solution, starting pneumatic stirring at the stirring speed of 0.8m3And/min. In order to ensure that the fluorine ions and the calcium ions are fully reacted, mechanical stirring can be added, and the stirring speed is 100 r/min. The method is carried out through pneumatic stirring and mechanical stirring, so that the fluorine ions and the calcium ions are ensured to fully react, and the reaction time is 10-15 min. At this time, the detected fluorine ion concentration was 85mg/L, and the pH was 8.85.
And 4, step 4: and (3) delivering the water discharged from the calcium chloride reactor to a PAC (polyaluminium chloride) reactor, wherein the concentration of the added polyaluminium chloride solution is 15g/L, and disturbing the water body to generate a velocity gradient or vortex by virtue of pneumatic stirring and mechanical stirring so as to promote particles to collide and coalesce with each other, wherein the reaction time is 10-15 min. After this step was carried out, the fluoride ion concentration was detected to decrease to 40mg/L and the pH was 8.09.
And 5: and (3) delivering the effluent of the PAC reactor to a PAM reactor, adding polyacrylamide with the concentration of 0.7g/L, mechanically stirring at the stirring speed of 100r/min to form larger floccules on particles, reacting for 10-15min, and reducing the fluorine ions to 10mg/L through testing, wherein the pH value is 7.95.
Step 6: and (4) delivering the PAM effluent to a sedimentation tank, mixing and flocculating to form flocculating constituents with larger particle sizes in suspended matters in water, and settling in a settling unit for 10-15 min. Suspended particles are separated from water by gravity, and the supernatant is sent to a clean water tank, and the fluorine ions are reduced to be within 8mg/L through detection. And finally pumping the sludge into a sludge tank and performing pressure filtration by a pressure filter.
Example 2
Fluorine-containing wastewater generated in the factory production process: the fluoride ion concentration is 3010mg/L, and the pH is 4.5. The daily wastewater treatment capacity was about 10 cubic meters and the operating time was 10 hours per day. The fluorine-containing wastewater treatment method comprises the following specific steps:
step 1: the fluorine-containing wastewater is collected and sent to a sedimentation tank (the capacity is 8 cubic meters), suspended matters in the wastewater are preliminarily settled, and the water quality is clarified.
Step 2: and (3) delivering the effluent of the sedimentation tank to a pH regulator, adding a calcium hydroxide solution and flake caustic soda, wherein the mass concentration of the added calcium hydroxide is 5g/L, adding 12kg of flake caustic soda, introducing compressed air into the regulator for stirring, wherein the pressure of the compressed air is more than 0.2Mpa, so that the solubility of the calcium hydroxide and the flake caustic soda is improved, and the reaction time is 30-40 min. Because the concentration of the fluorinion is lower than 5000mg/L, calcium chloride is not added in the pH regulator. The pH was 9.28.
And step 3: and (3) delivering the effluent of the pH regulator to a calcium chloride reactor, adding calcium chloride according to the molar ratio of fluoride ions to calcium ions of 1 (0.8-0.9), preparing 500L of 10% calcium chloride solution, and performing pneumatic stirring and mechanical stirring to ensure that the fluoride ions and the calcium ions are fully reacted for 10-15 min. After step 3, the fluoride ion was reduced to 60mg/L, and the pH was 8.82.
And 4, step 4: and (2) delivering the water discharged from the calcium chloride reactor to a PAC (polyaluminium chloride) reactor, wherein the concentration of the added polyaluminium chloride solution is 15g/L, stirring by using a pneumatic stirring machine and a mechanical stirring machine, disturbing a water body to generate a velocity gradient or vortex, promoting particles to collide with each other and coalesce, reacting for 10-15min, reducing the fluorine ions to 30mg/L, and adjusting the pH value to 8.15.
And 5: and (3) delivering the effluent of the PAC reactor to a PAM reactor, adding polyacrylamide with the solution concentration of 0.7g/L, mechanically stirring to form larger floccules on particles, reacting for 10-15min, reducing the fluorine ions to 9mg/L, and adjusting the pH value to 7.91.
Step 6: and (4) delivering the PAM effluent to a sedimentation tank, mixing and flocculating to form flocculating constituents with larger particle sizes in suspended matters in water, and settling in a settling unit for 10-15 min. Suspended particles are separated from water by gravity, supernatant liquid is sent to a clean water tank, and the detected fluorine ions are reduced to 4mg/L to reach the discharge standard. And finally pumping the sludge into a sludge tank and performing pressure filtration by a pressure filter.
Example 3
Fluorine-containing wastewater generated in the factory production process: the fluoride ion concentration was 13265mg/L, pH 2. The daily wastewater treatment capacity of the waste is about 10 cubic meters, and the daily operation time is 10 hours. The fluorine-containing wastewater treatment method comprises the following specific steps:
step 1: the fluorine-containing wastewater is collected and sent to a sedimentation tank (the capacity is 8 cubic meters), suspended matters in the wastewater are preliminarily settled, and the water quality is clarified.
Step 2: and (3) sending the effluent of the sedimentation tank to a pH regulator, adding a calcium hydroxide solution and caustic soda flakes, wherein the mass concentration of the added calcium hydroxide is 8g/L, adding 25kg of caustic soda flakes, introducing compressed air into the regulator, stirring, and reacting for 30-40min, wherein the pressure of the compressed air is more than 0.2 MPa. Meanwhile, calcium chloride solid is added according to the molar ratio of the fluoride ions to the calcium ions of 1 (0.5-0.6), and the fluoride ion concentration is reduced to 5450mg after the step 2. The pH was 9.52.
And step 3: and (3) delivering the effluent of the pH regulator to a calcium chloride reactor, adding calcium chloride according to the molar ratio of fluoride ions to calcium ions of 1 (0.8-0.9), preparing 500L of 10% calcium chloride solution, and performing pneumatic stirring and mechanical stirring to ensure that the fluoride ions and the calcium ions are fully reacted for 10-15 min. After the step 3, the fluorine ions can be reduced to 90mg/L, and the pH value is 9.21.
And 4, step 4: and (2) delivering the water discharged from the calcium chloride reactor to a PAC (polyaluminium chloride) reactor, wherein the concentration of the added polyaluminium chloride solution is 15g/L, stirring by using a pneumatic stirring machine and a mechanical stirring machine, disturbing a water body to generate a velocity gradient or vortex, promoting particles to collide with each other and coalesce, reacting for 10-15min, reducing the fluorine ions to 45mg/L, and adjusting the pH value to 8.02.
And 5: and (3) delivering the effluent of the PAC reactor to a PAM reactor, adding polyacrylamide with the solution concentration of 0.7g/L, mechanically stirring to form larger floccules on particles, reacting for 10-15min, reducing the fluorine ions to 8mg/L, and adjusting the pH value to 8.0.
Step 6: and (4) delivering the PAM effluent to a sedimentation tank, mixing and flocculating to form flocculating constituents with larger particle sizes in suspended matters in water, and settling in a settling unit for 10-15 min. Suspended particles are separated from water by gravity, supernatant liquid is sent to a clean water tank, and fluoride ions are reduced to 3mg/L to reach the discharge standard. And finally pumping the sludge into a sludge tank and performing pressure filtration by a pressure filter.
The processing data of 11 months in 2020 is intercepted, and the fluorine ion processing qualification rate is 100% which can be analyzed from table 1.
TABLE 1.2020 monthly 11 wastewater treatment data
Figure BDA0002991086320000111
Figure BDA0002991086320000121
TABLE 2 Effect of calcium hydroxide concentration on defluorination in step 2
Figure BDA0002991086320000122
TABLE 3 Effect of calcium chloride concentration variation on defluorination in step 3
Figure BDA0002991086320000123
TABLE 4 Effect of PAC concentration variation on defluorination in step 4
Figure BDA0002991086320000124
TABLE 5 Effect of PAM concentration variation on defluorination in step 5
Figure BDA0002991086320000131
As can be seen from tables 2 to 5, the change in the concentration of each substance used in steps 2 to 5 has a small influence on the effect of removing fluoride ions from wastewater, and the concentration of each substance is selected mainly from the viewpoint of time cost and plant efficiency.
While the invention has been described with reference to specific embodiments and features, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the scope of the present invention should not be limited to the embodiments disclosed, but includes various alternatives and modifications without departing from the present invention, which are encompassed by the claims.

Claims (8)

1. A method for treating fluorine-containing wastewater by rare earth molten salt electrolysis is characterized by comprising the following steps:
(1) collecting the fluorine-containing wastewater, sending the fluorine-containing wastewater to a sedimentation tank, preliminarily settling suspended matters in the wastewater, and clarifying the water;
(2) sending the effluent of the sedimentation tank to a pH regulator, adding a calcium hydroxide solution or a calcium hydroxide solution and solid flake caustic soda or calcium hydroxide, solid flake caustic soda and solid calcium chloride, reacting for 30-40min, starting stirring, and controlling the pH value to be 8-10;
(3) and (3) delivering the effluent of the pH regulator to a calcium chloride reactor, wherein according to the molar ratio of fluorine ions to calcium ions of 1: (0.8-0.9) adding a calcium chloride solution, and starting stirring to promote further reaction of fluorine ions and calcium ions;
(4) delivering the effluent of the calcium chloride reactor to a polyaluminium chloride (PAC) reactor, adding a polyaluminium chloride solution for coagulation reaction, and stirring for 10-15 min;
(5) delivering the effluent of the polyaluminium chloride reactor to a Polyacrylamide (PAM) reactor, adding a polyacrylamide solution for flocculation reaction, wherein the reaction time is 10-15min, and the stirring mode is mechanical stirring;
(6) and (3) sending the effluent of the polyacrylamide reactor to a sedimentation tank, settling for 10-15min, separating suspended particles from water by using gravity, storing the supernatant in a clear water tower, and discharging after reaching the standard.
2. The method for treating fluorine-containing wastewater by rare earth molten salt electrolysis according to claim 1, characterized by comprising the following steps: in the step 2, the calcium chloride is added according to the molar ratio of the fluorine ions to the calcium ions of 1 (0.5-0.6).
3. The method for treating fluorine-containing wastewater by rare earth molten salt electrolysis according to claim 1, characterized by comprising the following steps: the concentration range of the calcium hydroxide in the step 2 is 5-10g/L, and the concentration of the calcium chloride in the step 3 is 50-150 g/L.
4. The method for treating fluorine-containing wastewater by rare earth molten salt electrolysis according to claim 1, characterized by comprising the following steps: the concentration of the solution prepared by the polyaluminium chloride in the step 4 is 5-30 g/L; the concentration of the polyacrylamide solution in the step 5 is 0.3-1.5 g/L.
5. The method for treating fluorine-containing wastewater by rare earth molten salt electrolysis according to claim 1, characterized by comprising the following steps: the polyaluminium chloride in the step 4 can be replaced by flocculating agents such as aluminum sulfate, ferric sulfate, poly active silica gel and the like.
6. The method for treating fluorine-containing wastewater by rare earth molten salt electrolysis according to claim 1, characterized by comprising the following steps: the polyacrylamide in the step 5 can be replaced by coagulant aids such as polyacrylic acid, amphoteric polyacrylamide and the like.
7. The method for treating fluorine-containing wastewater by rare earth molten salt electrolysis according to claim 1, characterized by comprising the following steps: in the step 2-4, pneumatic stirring is adopted, and mechanical stirring is assisted; and step 5, adopting mechanical stirring.
8. The method for treating fluorine-containing wastewater by rare earth molten salt electrolysis according to claim 1, characterized by comprising the following steps: and (2) adopting vertical flow type sedimentation in the sedimentation tank in the step (1).
CN202110314201.9A 2021-03-24 2021-03-24 Rare earth molten salt electrolysis fluorine-containing wastewater treatment method Pending CN113023952A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110314201.9A CN113023952A (en) 2021-03-24 2021-03-24 Rare earth molten salt electrolysis fluorine-containing wastewater treatment method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110314201.9A CN113023952A (en) 2021-03-24 2021-03-24 Rare earth molten salt electrolysis fluorine-containing wastewater treatment method

Publications (1)

Publication Number Publication Date
CN113023952A true CN113023952A (en) 2021-06-25

Family

ID=76473391

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110314201.9A Pending CN113023952A (en) 2021-03-24 2021-03-24 Rare earth molten salt electrolysis fluorine-containing wastewater treatment method

Country Status (1)

Country Link
CN (1) CN113023952A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114835335A (en) * 2022-03-22 2022-08-02 西安隆基乐叶光伏科技有限公司 System and method for removing fluorine and controlling calcium of wastewater containing nitrogen and fluorine in battery process
CN115959750A (en) * 2022-12-26 2023-04-14 伊沃环境科技(南京)有限公司 Efficient polycrystalline silicon waste water defluorination system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06134471A (en) * 1992-10-23 1994-05-17 Kawasaki Steel Corp Method for removing fluorine from waste water containing fluorine
JP2003117564A (en) * 2001-10-12 2003-04-22 Nippon Steel Corp Method for treating fluorine-containing waste water
WO2010092946A1 (en) * 2009-02-13 2010-08-19 株式会社神鋼環境ソリューション Method for processing waste water containing fluorine and silicon, method for producing calcium fluoride, and facility for processing fluorine-containing waste water
CN109626642A (en) * 2018-12-27 2019-04-16 北京翰祺环境技术有限公司 Fluorine-contained wastewater treatment system and fluorine-containing wastewater treatment method
CN110304754A (en) * 2019-03-19 2019-10-08 中国电子系统工程第二建设有限公司 A kind of high-concentration fluorine-containing waste water deep treatment method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06134471A (en) * 1992-10-23 1994-05-17 Kawasaki Steel Corp Method for removing fluorine from waste water containing fluorine
JP2003117564A (en) * 2001-10-12 2003-04-22 Nippon Steel Corp Method for treating fluorine-containing waste water
WO2010092946A1 (en) * 2009-02-13 2010-08-19 株式会社神鋼環境ソリューション Method for processing waste water containing fluorine and silicon, method for producing calcium fluoride, and facility for processing fluorine-containing waste water
CN109626642A (en) * 2018-12-27 2019-04-16 北京翰祺环境技术有限公司 Fluorine-contained wastewater treatment system and fluorine-containing wastewater treatment method
CN110304754A (en) * 2019-03-19 2019-10-08 中国电子系统工程第二建设有限公司 A kind of high-concentration fluorine-containing waste water deep treatment method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114835335A (en) * 2022-03-22 2022-08-02 西安隆基乐叶光伏科技有限公司 System and method for removing fluorine and controlling calcium of wastewater containing nitrogen and fluorine in battery process
CN114835335B (en) * 2022-03-22 2024-01-19 西安隆基乐叶光伏科技有限公司 System and method for removing fluorine and controlling calcium from nitrogen-containing fluorine-containing wastewater in battery technology
CN115959750A (en) * 2022-12-26 2023-04-14 伊沃环境科技(南京)有限公司 Efficient polycrystalline silicon waste water defluorination system

Similar Documents

Publication Publication Date Title
CN110668540B (en) High-salinity wastewater precipitation desalination recycling process
CN106430786B (en) Desulfurization wastewater treatment method and device
CN107915354A (en) A kind of desulfurization wastewater zero-emission and resource utilization device and method
CN109384332A (en) A kind of method of coal burning flue gas desulfurization wastewater treatment
CN113023952A (en) Rare earth molten salt electrolysis fluorine-containing wastewater treatment method
CN212450783U (en) Sewage treatment system for removing silicon and hardness
US20160176739A1 (en) Water treatment device and water treatment method
CN111892142A (en) Silicon removal agent, silicon removal and hardness removal sewage treatment system and method
CN106865826A (en) The method that desulfurization wastewater is recycled
CN111268830A (en) System and process for advanced treatment and recycling of fluorine-containing wastewater in electronic industry
CN111217484A (en) Desulfurization wastewater recycling treatment method
CN109368897A (en) A kind of milk of lime process recycles the system and application method of calcium ions and magnesium ions in desulfurization wastewater
CN110963598A (en) Treatment method for uranium conversion alkaline fluorine-containing wastewater
US10358355B2 (en) Aluminum hydroxide coagulant recovery from water/wastewater treatment sludge
CN111153531A (en) Liquid crystal display panel production plant fluorine-containing wastewater treatment device and process
CN114409141A (en) Method for hardness removal of coal gasification ash water
CN112811665A (en) Softening device and softening method for high-hardness incoming water
CN107021535A (en) The processing method of desulfurization wastewater
CN111233208A (en) Desulfurization waste water resource recovery system
CN215975294U (en) Processing apparatus of concentrated water and sodium chloride evaporation mother liquor receive filtering
CN116395875A (en) High-chlorine desulfurization wastewater zero-emission system and process
CN116444099A (en) Method for ultralow emission of fluorine content of external drainage water in titanium white production
CN214115166U (en) High-efficiency fluorine and ammonia removing system
CN106673292B (en) Coal gasification ash water pretreatment method
CN111099774A (en) Desulfurization wastewater treatment method and system

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
WD01 Invention patent application deemed withdrawn after publication
WD01 Invention patent application deemed withdrawn after publication

Application publication date: 20210625