A device for treating fluorine-containing wastewater

Abstract

The utility model provides a kind of fluorine-containing wastewater treatment device, comprising: the inlet of sodium fluorosilicate synthetic device in high-fluorine wastewater treatment unit is connected with high-fluorine wastewater collection pool and sodium chloride storage pool respectively, the outlet of sodium fluorosilicate synthetic device is connected with multistage thickening unit, wherein the supernatant outlet of first stage thickening device is connected with transfer tank, precipitate outlet is connected with next stage thickening device, and the precipitate outlet of last stage thickening device is connected with sodium fluorosilicate storage tank;The bottom inlet of fluidized bed crystallizer in low-fluorine wastewater treatment unit is connected with low-fluorine wastewater mixing tank and calcium source mixing tank respectively, the outlet of transfer tank and low-fluorine wastewater collection pool is connected with low-fluorine wastewater mixing tank, and the lower outlet of fluidized bed crystallizer is connected with calcium fluoride storage tank.The treatment device provided by the utility model can treat high-fluorine wastewater and low-fluorine wastewater respectively using different process methods, reduce the generation of fluorine-containing sludge, and obtain high-purity sodium fluorosilicate and calcium fluoride products.

Description

Technical Field

[0001] This utility model relates to the field of fluoride-containing wastewater treatment technology, and specifically to a device for treating fluoride-containing wastewater. Background Technology

[0002] In recent years, with the rapid development of smart devices, the demand for glass panels has increased significantly, especially in touch displays, optical components, and high-end manufacturing. This has not only driven the development of the glass cover industry but also brought challenges to wastewater treatment, particularly the treatment of fluoride-containing wastewater. Fluoride-containing wastewater mainly originates from the wet thinning process of glass etching using hydrofluoric acid (HF). The resulting fluoride-containing wastewater has a complex composition, containing not only high concentrations of fluoride ions but also a large amount of silicides (such as fluorosilicic acid or fluorosilicates), making it difficult to treat. This not only makes it difficult for traditional calcium salt methods to completely remove fluoride but also, if not treated properly, can easily generate silica gel, ultimately affecting the efficiency of subsequent treatment.

[0003] Currently, common fluoride-containing wastewater treatment systems mainly employ a primary fluoride removal system or a combination of a primary and a secondary fluoride removal system to reduce the concentration of fluoride ions in the wastewater. For example, CN217498899U discloses a fluoride-containing wastewater treatment device, including: a primary fluoride removal process device and a secondary fluoride removal process device; the primary fluoride removal process device includes a primary reaction tank, a primary coagulation tank, a primary flocculation tank, and a primary sedimentation tank connected in sequence; the secondary fluoride removal process device includes a secondary reaction tank, a secondary flocculation tank, and a secondary sedimentation tank connected in sequence; a sludge pipe is provided at the bottom of the secondary sedimentation tank, a return sludge pump is provided on the sludge pipe, and a return sludge pipe is provided at the outlet of the return sludge pump, which is connected to the feed inlet of the primary coagulation tank. Although this device reduces the amount of aluminum salt used in the secondary defluorination process, it cannot solve the problem of large sludge volume. Furthermore, using only calcium salts can only precipitate some fluorosilicic acid or fluorosilicates. The calcium fluorosilicate produced by the reaction has high solubility and is easily hydrolyzed in water. At the same time, the calcium fluorosilicate produced, as an impurity, will affect the purity of calcium fluoride and reduce the economic value of the product.

[0004] Therefore, for the fluoride-containing wastewater generated in the glass cover industry, how to reduce sludge production while improving fluoride utilization is a technical problem that needs to be solved. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a treatment device for fluoride-containing wastewater. The treatment device can treat high-fluoride wastewater and low-fluoride wastewater using different processes, reduce the generation of fluoride-containing sludge, and obtain high-purity sodium fluorosilicate and calcium fluoride products, which has high economic and social benefits.

[0006] To achieve the objective of this utility model, the following technical solution is adopted:

[0007] This utility model provides a treatment device for fluoride-containing wastewater, the treatment device including a high-fluoride wastewater treatment unit, a low-fluoride wastewater treatment unit, a high-fluoride wastewater collection tank and a low-fluoride wastewater collection tank;

[0008] The high-fluoride wastewater treatment unit includes a sodium fluorosilicate synthesis device. The inlet of the sodium fluorosilicate synthesis device is connected to a high-fluoride wastewater collection tank and a sodium chloride storage tank, respectively. The outlet of the sodium fluorosilicate synthesis device is connected to a multi-stage thickening unit. The supernatant outlet of the first-stage thickening device in the multi-stage thickening unit is connected to a transfer tank. The precipitate outlet of the first-stage thickening device is connected to the next-stage thickening device. The precipitate outlet of the last-stage thickening device in the multi-stage thickening unit is connected to a sodium fluorosilicate storage tank.

[0009] The outlets of the transfer tank and the low-fluoride wastewater collection tank are connected to the low-fluoride wastewater mixing tank. The low-fluoride wastewater treatment unit includes a fluidized bed crystallizer. The bottom inlet of the fluidized bed crystallizer is connected to the low-fluoride wastewater mixing tank, the calcium chloride storage tank, and the calcium hydroxide storage tank, respectively. The upper outlet of the fluidized bed crystallizer is connected to the effluent tank. The outlet of the effluent tank is connected to the bottom inlet of the fluidized bed crystallizer via a circulation pipeline. The lower outlet of the fluidized bed crystallizer is connected to the calcium fluoride storage tank.

[0010] This invention addresses the treatment of fluoride-containing wastewater generated in the glass cover industry. Specifically, it categorizes wastewater into high-fluoride and low-fluoride wastewater based on fluoride concentration, treating each separately. High-fluoride wastewater refers to wastewater with high acidity, high hydrofluoric acid concentration, and high fluorosilicic acid concentration, while low-fluoride wastewater refers to wastewater with high acidity, low hydrofluoric acid concentration, and low fluorosilicic acid concentration. The invention includes a high-fluoride wastewater treatment unit. Sodium chloride and the high-fluoride wastewater are synthesized into sodium fluorosilicate in a sodium fluorosilicate synthesis device, thus achieving effective utilization of fluorosilicic acid. Furthermore, the supernatant outlet of the first-stage thickening device after sodium fluorosilicate synthesis is connected to a low-fluoride wastewater mixing tank via a transfer tank. This allows for the full utilization of fluoride ions in the high-fluoride wastewater, mixing it with the low-fluoride wastewater in the mixing tank. Mixing methods, such as air agitation, further facilitate the subsequent utilization of fluoride ions. This invention incorporates a fluidized bed crystallizer, in which seed crystals are pre-added, and fluoride-containing wastewater and calcium source form calcium fluoride products in the fluidized bed crystallizer, thereby achieving effective utilization of fluoride ions.

[0011] The treatment device provided by this utility model, through the synergistic effect of the high-fluoride wastewater treatment unit and the low-fluoride wastewater treatment unit, can not only effectively utilize the fluorosilicic acid in the high-fluoride wastewater, but also recover the fluoride ions in the high-fluoride wastewater and mix them with the low-fluoride wastewater for resource utilization of the fluoride ions, ultimately obtaining high-purity sodium fluorosilicate and calcium fluoride products.

[0012] In this invention, the sodium fluorosilicate synthesis apparatus is not particularly limited and can be any reaction vessel or reactor used in the art for synthesizing sodium fluorosilicate from fluorosilicic acid and sodium chloride. The sodium fluorosilicate synthesis apparatus is equipped with a heat exchange device to provide the heat required for the reaction. The sodium fluorosilicate synthesis apparatus is generally equipped with a stirring device to ensure a more complete reaction.

[0013] In this invention, the thickening device can be a commonly used thickening device in the art, such as a thickener.

[0014] Preferably, the processing device includes a water collection tank; the supernatant outlet of the last stage thickening device in the multi-stage thickening unit is connected to the water collection tank.

[0015] Preferably, the multi-stage thickening unit includes a first-stage thickening device and a second-stage thickening device connected sequentially along the moving direction of sodium fluorosilicate; the precipitate outlet of the first-stage thickening device is connected to the second-stage thickening device.

[0016] In this invention, sodium chloride and high-fluoride wastewater are used to generate sodium fluorosilicate suspension in a sodium fluorosilicate synthesis device. The suspension then enters a first-stage thickening device for sedimentation. The supernatant overflows through the overflow port of the first-stage thickening device into a transfer tank, and the precipitate enters a second-stage thickening device. Water can be added to the second-stage thickening device to stir and wash the precipitate. After settling and stratification, the supernatant overflows through the overflow port of the second-stage thickening device into a collection tank, and the washed precipitate enters a sodium fluorosilicate storage tank.

[0017] Preferably, the inlet of the sodium chloride storage tank is connected to the sodium chloride dissolving tank; the inlet of the sodium chloride dissolving tank is connected to both the water collection tank and the sodium chloride silo.

[0018] In this invention, water from a collection tank and sodium chloride are used to generate a sodium chloride solution in a sodium chloride dissolving tank. The sodium chloride dissolving tank is generally equipped with a stirring device to achieve uniform mixing.

[0019] Preferably, the calcium chloride storage tank and the calcium hydroxide storage tank are connected to the bottom inlet of the fluidized bed crystallizer via a mixer.

[0020] In this invention, the feed solutions from the calcium chloride storage tank and the calcium hydroxide storage tank are mixed evenly in a mixer to obtain a calcium source. The calcium source (calcium hydroxide and calcium chloride) and fluoride-containing wastewater are introduced into the fluidized bed crystallizer from bottom to top according to a certain calcium / fluoride molar ratio. The power for the introduction can be provided by a pump.

[0021] Preferably, the inlet of the calcium chloride storage tank is connected to the calcium chloride dilution tank; the inlet of the calcium chloride dilution tank is connected to the calcium chloride storage tank.

[0022] Preferably, the inlet of the calcium chloride dilution tank is also connected to a water collection tank and / or an outlet pool.

[0023] In this invention, the calcium chloride storage tank typically pre-stores a calcium chloride solution of a certain concentration. The calcium chloride dilution tank can be diluted with water from an outlet pool and / or a collection pool to obtain a calcium chloride solution of the desired concentration, which is then stored in the calcium chloride storage tank, improving water recycling. The calcium chloride dilution tank is generally equipped with a stirring device to ensure more uniform mixing.

[0024] Preferably, the inlet of the calcium hydroxide storage tank is connected to the calcium hydroxide dissolving tank; the inlet of the calcium hydroxide dissolving tank is connected to the calcium hydroxide silo.

[0025] Preferably, the inlet of the calcium hydroxide dissolving tank is also connected to a water collection tank and / or an outlet pool.

[0026] In this invention, calcium hydroxide and water from an outlet tank and / or collection tank are used to form a calcium hydroxide slurry of a certain concentration in a calcium hydroxide dissolving tank. The calcium hydroxide dissolving tank may be equipped with an overflow pipe, through which the slurry overflows into a calcium hydroxide storage tank. In this invention, a stirring device may be installed in the calcium hydroxide dissolving tank to ensure more thorough mixing of the materials.

[0027] In this embodiment, part of the water in the effluent pool is recycled back to the fluidized bed crystallizer, part is used to prepare calcium chloride solution and calcium hydroxide slurry, and part of the water is discharged.

[0028] Preferably, the outlet of the sodium fluorosilicate storage tank is connected to the dehydration device; the liquid phase outlet of the dehydration device is connected to the water collection tank; the solid phase outlet of the dehydration device is connected to the drying device; the solid phase outlet of the drying device is connected to the sodium fluorosilicate product storage tank; and the condensate outlet of the drying device is connected to the water collection tank.

[0029] In this invention, the solid material after being processed by the dehydration device is conveyed to the drying device for drying. The conveying method can be a screw conveyor, and then it enters the sodium fluorosilicate product storage tank for packaging and storage.

[0030] In this invention, the dehydration device can be a commonly used dehydration device in the art, such as a centrifuge or a plate and frame filter press.

[0031] The operation process of the treatment device provided by this utility model for treating fluoride-containing wastewater is as follows:

[0032] High-concentration fluoride-containing wastewater is collected in a high-fluoride wastewater collection tank, with hydrofluoric acid concentrations of 50,000-100,000 mg / L and fluorosilicic acid concentrations of 50,000-150,000 mg / L. Low-concentration fluoride-containing wastewater is collected in a low-fluoride wastewater collection tank, with hydrofluoric acid concentrations of 500-5,000 mg / L and fluorosilicic acid concentrations of 500-2,000 mg / L.

[0033] The water from the collection tank and the sodium chloride from the sodium chloride silo are mixed in a sodium chloride dissolving tank to prepare a sodium chloride solution with a concentration of 10-26.47%, which is then stored in a sodium chloride storage tank.

[0034] Store a commercially available 30% calcium chloride solution in a calcium chloride storage tank. Prepare a 10-30% calcium chloride solution by mixing it with water from a collection tank and / or an outlet pool in a calcium chloride dilution tank and store it in a calcium chloride storage pool.

[0035] The calcium hydroxide stored in the calcium hydroxide silo and the water in the collection tank and / or outlet pool are used to prepare a calcium hydroxide slurry with a concentration of 1-10% in the calcium hydroxide dissolving tank, and then stored in the calcium hydroxide storage tank.

[0036] Sodium fluorosilicate is synthesized in a sodium fluorosilicate synthesis unit by combining high-fluoride wastewater from a high-fluoride wastewater collection tank and sodium chloride solution from a sodium chloride storage tank. The molar ratio of sodium chloride to fluorosilicic acid is controlled at (4-5):1, the reaction time is 0.5-2 hours, and the reaction temperature is 45-70℃, resulting in a sodium fluorosilicate suspension. The sodium fluorosilicate suspension is then fed into a first-stage thickening unit for precipitation. The supernatant overflows into a transfer tank, and the precipitate enters a second-stage thickening unit. Water is added to the second-stage thickening unit to agitate and wash the precipitate. After settling and stratification, the supernatant enters a collection tank. The washed precipitate enters a sodium fluorosilicate storage tank, then a dehydration unit for filtration, followed by a drying unit for drying. Finally, the precipitate is transferred to a sodium fluorosilicate product storage tank for packaging and storage. The filtrate from the dehydration unit and the condensate from the drying unit enter the collection tank. The water in the collection tank is used to dissolve sodium chloride, calcium hydroxide, or dilute calcium chloride solution.

[0037] Seed crystals are pre-added to the fluidized bed crystallizer to provide a nucleus basis for crystallization and promote uniform crystal growth. Wastewater from the transfer tank and the low-fluoride wastewater collection tank is mixed in the low-fluoride wastewater mixing tank to control the fluoride ion concentration at 200-2000 mg / L. The feed solutions from the calcium chloride storage tank and the calcium hydroxide storage tank are mixed evenly by a mixer and then sent to the fluidized bed crystallizer. At the same time, the wastewater from the low-fluoride wastewater mixing tank and the circulating water from the effluent tank are also sent to the fluidized bed crystallizer to control the calcium / fluoride molar ratio at (1.2-2.2):1. The effluent from the upper outlet of the fluidized bed crystallizer enters the effluent tank, and the calcium fluoride product produced from the lower outlet enters the calcium fluoride storage tank.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The treatment device provided by this utility model is for the treatment of fluoride-containing wastewater generated by the glass panel etching and thinning process. It can treat the fluoride-containing wastewater without adding coagulation or flocculant, thus saving the cost of the agent.

[0040] (2) The treatment device provided by this utility model divides fluoride-containing wastewater into high-fluoride treatment units and low-fluoride wastewater treatment units according to different fluoride concentrations. It can recover fluorosilicic acid from high-fluoride wastewater in the sodium fluorosilicate synthesis unit, and the purity of the obtained sodium fluorosilicate meets the indicators of superior grade in the national standard GB / T 23936-2018. Fluorinated bed crystallizer is used to recover fluoride ions from fluoride-containing wastewater, and the purity of the obtained calcium fluoride product reaches more than 95%, which has high economic value and application prospects. In addition, the effluent from the effluent tank has been tested and found to have a good defluorination effect, which can reduce the concentration of fluoride ions to below 20 mg / L.

[0041] (3) The processing device provided by this utility model has a high degree of automation, is easy to operate, simple to manage, and has low maintenance costs. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the processing device provided in Embodiment 1 of this utility model.

[0043] In the diagram: 1-Sodium chloride silo; 2-Sodium chloride dissolving tank; 3-Sodium chloride storage tank; 4-High-fluoride wastewater collection tank; 5-Sodium fluorosilicate synthesis unit; 6-First-stage thickening unit; 7-Second-stage thickening unit; 8-Collection tank; 9-Sodium fluorosilicate storage tank; 10-Dehydration unit; 11-Drying unit; 12-Sodium fluorosilicate product storage tank; 13-Transfer tank; 14-Low-fluoride wastewater collection tank; 15-Low-fluoride wastewater mixing tank; 16-Fluorescent bed crystallizer; 17-Effluent tank; 18-Calcium chloride storage tank; 19-Calcium chloride dilution tank; 20-Calcium chloride storage tank; 21-Calcium hydroxide silo; 22-Calcium hydroxide dissolving tank; 23-Calcium hydroxide storage tank; 24-Mixer; 25-Calcium fluoride storage tank. Detailed Implementation

[0044] It should be understood that in the description of this utility model, the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0045] It should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0046] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] This embodiment provides a device for treating fluoride-containing wastewater, such as... Figure 1 As shown, the treatment device includes a high-fluoride wastewater treatment unit, a low-fluoride wastewater treatment unit, a high-fluoride wastewater collection tank 4, and a low-fluoride wastewater collection tank 14.

[0049] The high-fluoride wastewater treatment unit includes a sodium fluorosilicate synthesis device 5. The inlet of the sodium fluorosilicate synthesis device 5 is connected to the high-fluoride wastewater collection tank 4 and the sodium chloride storage tank 3, respectively. The outlet of the sodium fluorosilicate synthesis device 5 is connected to the first-stage thickening device 6. The precipitate outlet of the first-stage thickening device 6 is connected to the second-stage thickening device 7. The supernatant outlet of the first-stage thickening device 6 is connected to the transfer tank 13. The precipitate outlet of the second-stage thickening device 7 is connected to the sodium fluorosilicate storage tank 9. The treatment device also includes a water collection tank 8. The supernatant outlet of the second-stage thickening device 7 is connected to the water collection tank 8.

[0050] The outlets of the transfer tank 13 and the low-fluoride wastewater collection tank 14 are connected to the low-fluoride wastewater mixing tank 15. The low-fluoride wastewater treatment unit includes a fluidized bed crystallizer 16. The bottom inlet of the fluidized bed crystallizer 16 is connected to the low-fluoride wastewater mixing tank 15, the calcium chloride storage tank 20, and the calcium hydroxide storage tank 23, respectively. The upper outlet of the fluidized bed crystallizer 16 is connected to the effluent tank 17. The outlet of the effluent tank 17 is connected to the bottom inlet of the fluidized bed crystallizer 16 via a circulation pipeline. The lower outlet of the fluidized bed crystallizer 16 is connected to the calcium fluoride storage tank 25.

[0051] The inlet of the sodium chloride storage tank 3 is connected to the sodium chloride dissolving tank 2, and the inlet of the sodium chloride dissolving tank 2 is connected to the water collection tank 8 and the sodium chloride silo 1, respectively. The calcium chloride storage tank 20 and the calcium hydroxide storage tank 23 are connected to the bottom inlet of the fluidized bed crystallizer 16 via the mixer 24. The inlet of the calcium chloride storage tank 20 is connected to the calcium chloride dilution tank 19, and the inlet of the calcium chloride dilution tank 19 is connected to the calcium chloride storage tank 18, the water collection tank 8, and the effluent pool 17, respectively. The inlet of the calcium hydroxide storage tank 23 is connected to the calcium hydroxide dissolving tank 22, and the inlet of the calcium hydroxide dissolving tank 22 is connected to the calcium hydroxide silo 21, the water collection tank 8, and the effluent pool 17, respectively.

[0052] The outlet of the sodium fluorosilicate storage tank 9 is connected to the dehydration device 10, the liquid phase outlet of the dehydration device 10 is connected to the water collection tank 8, the solid phase outlet of the dehydration device 10 is connected to the drying device 11, the solid phase outlet of the drying device 11 is connected to the sodium fluorosilicate product storage tank 12, and the condensate outlet of the drying device 11 is connected to the water collection tank 8.

[0053] The operation process of the treatment device provided in the embodiment for treating fluoride-containing wastewater is as follows:

[0054] High-concentration fluoride-containing wastewater was collected in high-fluoride wastewater collection tank 4, with a hydrofluoric acid concentration of 70,000 mg / L and a fluorosilicic acid concentration of 110,000 mg / L. Low-concentration fluoride-containing wastewater was collected in low-fluoride wastewater collection tank 14, with a hydrofluoric acid concentration of 800 mg / L and a fluorosilicic acid concentration of 600 mg / L.

[0055] The water from the collection tank 8 and the sodium chloride from the sodium chloride silo 1 are mixed in the sodium chloride dissolving tank 2 to prepare a 20% sodium chloride solution, which is then stored in the sodium chloride storage tank 3.

[0056] A commercially available 30% calcium chloride solution is stored in a calcium chloride storage tank 18. The solution is then mixed with water from a collection tank 8 and an outlet tank 17 in a calcium chloride dilution tank 19 to prepare a 20% calcium chloride solution, which is then stored in a calcium chloride storage tank 20.

[0057] The calcium hydroxide stored in the calcium hydroxide silo 21, the water collected in the water tank 8 and the water outlet tank 17 are mixed in the calcium hydroxide dissolving tank 22 to prepare a calcium hydroxide slurry with a concentration of 5%, and then stored in the calcium hydroxide storage tank 23.

[0058] Sodium fluorosilicate is synthesized in a sodium fluorosilicate synthesis unit 5 using high-fluoride wastewater from a high-fluoride wastewater collection tank 4 and sodium chloride solution from a sodium chloride storage tank 3. The molar ratio of sodium chloride to fluorosilicic acid is controlled at 4.5:1, the reaction time is 1 hour, and the reaction temperature is 50°C, resulting in a sodium fluorosilicate suspension. The sodium fluorosilicate suspension is then fed into a first-stage thickening unit 6 for precipitation. The supernatant overflows into a transfer tank 13, and the precipitate enters a second-stage thickening unit 7. Water is added to the second-stage thickening unit 7 to agitate and wash the precipitate. After settling and stratification, the supernatant enters a collection tank 8, and the washed precipitate enters a sodium fluorosilicate storage tank 9. It then enters a dehydration unit 10 for filtration, followed by drying in a drying unit 11. Finally, it is sent to a sodium fluorosilicate product storage tank 12 for packaging and storage. The filtrate from the dehydration unit 10 and the condensate from the drying unit 11 enter the collection tank 8. The water in the collection tank 8 is used to dissolve sodium chloride and calcium hydroxide, and to dilute the calcium chloride solution.

[0059] Seed crystals are pre-added to the fluidized bed crystallizer 16 to provide a nucleus basis for crystallization and promote uniform crystal growth. Wastewater from the transfer tank 13 and the low-fluoride wastewater collection tank 14 is mixed in the low-fluoride wastewater mixing tank 15 to control the fluoride ion concentration at 1000 mg / L. The feed solutions from the calcium chloride storage tank 20 and the calcium hydroxide storage tank 23 are mixed evenly by the mixer 24 and then fed into the fluidized bed crystallizer 16. At the same time, wastewater from the low-fluoride wastewater mixing tank 15 and circulating water from the effluent tank 17 are also fed into the fluidized bed crystallizer 16, controlling the calcium / fluoride molar ratio at 2:1. The effluent from the upper outlet of the fluidized bed crystallizer 16 enters the effluent tank 17, and the calcium fluoride product produced at the lower outlet enters the calcium fluoride storage tank 25. Part of the water in the effluent tank 17 is recycled back to the fluidized bed crystallizer 16, part is used to prepare calcium chloride solution and calcium hydroxide slurry, and part is discharged.

[0060] After treatment using the treatment device provided in this embodiment, the fluoride ion concentration in the effluent from the effluent tank 17 can be reduced to below 20 mg / L, the purity of the calcium fluoride product reaches over 95%, and the sodium fluorosilicate product meets the superior grade indicators in the national standard GB / T 23936-2018.

[0061] The above description is only a specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model fall within the protection and disclosure scope of the present utility model.

Claims

1. A device for treating fluoride-containing wastewater, characterized in that, The treatment device includes a high-fluoride wastewater treatment unit, a low-fluoride wastewater treatment unit, a high-fluoride wastewater collection tank, and a low-fluoride wastewater collection tank. The high-fluoride wastewater treatment unit includes a sodium fluorosilicate synthesis device. The inlet of the sodium fluorosilicate synthesis device is connected to a high-fluoride wastewater collection tank and a sodium chloride storage tank, respectively. The outlet of the sodium fluorosilicate synthesis device is connected to a multi-stage thickening unit. The supernatant outlet of the first-stage thickening device in the multi-stage thickening unit is connected to a transfer tank. The precipitate outlet of the first-stage thickening device is connected to the next-stage thickening device. The precipitate outlet of the last-stage thickening device in the multi-stage thickening unit is connected to a sodium fluorosilicate storage tank. The outlets of the transfer tank and the low-fluoride wastewater collection tank are connected to the low-fluoride wastewater mixing tank. The low-fluoride wastewater treatment unit includes a fluidized bed crystallizer. The bottom inlet of the fluidized bed crystallizer is connected to the low-fluoride wastewater mixing tank, the calcium chloride storage tank, and the calcium hydroxide storage tank, respectively. The upper outlet of the fluidized bed crystallizer is connected to the effluent tank. The outlet of the effluent tank is connected to the bottom inlet of the fluidized bed crystallizer via a circulation pipeline. The lower outlet of the fluidized bed crystallizer is connected to the calcium fluoride storage tank.

2. The fluoride-containing wastewater treatment device according to claim 1, characterized in that, The processing device includes a water collection tank; The supernatant outlet of the last stage thickening device in the multi-stage thickening unit is connected to the collection tank.

3. The fluoride-containing wastewater treatment device according to claim 1, characterized in that, The multi-stage thickening unit includes a first-stage thickening device and a second-stage thickening device connected sequentially along the moving direction of sodium fluorosilicate. The precipitate outlet of the first-stage thickening device is connected to the second-stage thickening device.

4. The fluoride-containing wastewater treatment device according to claim 2, characterized in that, The inlet of the sodium chloride storage tank is connected to the sodium chloride dissolving tank; The inlet of the sodium chloride dissolving tank is connected to the water collection tank and the sodium chloride silo, respectively.

5. The treatment apparatus for fluoride-containing wastewater according to claim 1, characterized in that, The calcium chloride and calcium hydroxide storage tanks are connected to the bottom inlet of the fluidized bed crystallizer via a mixer.

6. The fluoride-containing wastewater treatment apparatus according to claim 2, characterized in that, The inlet of the calcium chloride storage tank is connected to the calcium chloride dilution tank; The inlet of the calcium chloride dilution tank is connected to the calcium chloride storage tank.

7. The fluoride-containing wastewater treatment apparatus according to claim 6, characterized in that, The inlet of the calcium chloride dilution tank is also connected to a collection tank and / or an outlet pool.

8. The fluoride-containing wastewater treatment apparatus according to claim 2, characterized in that, The inlet of the calcium hydroxide storage tank is connected to the calcium hydroxide dissolving tank; The inlet of the calcium hydroxide dissolving tank is connected to the calcium hydroxide silo.

9. The fluoride-containing wastewater treatment apparatus according to claim 8, characterized in that, The inlet of the calcium hydroxide dissolving tank is also connected to a water collection tank and / or an outlet pool.

10. The fluoride-containing wastewater treatment apparatus according to claim 2, characterized in that, The outlet of the sodium fluorosilicate storage tank is connected to the dehydration device; The liquid phase outlet of the dehydration device is connected to a water collection tank; The solid phase outlet of the dehydration device is connected to the drying device; The solid phase outlet of the drying device is connected to the sodium fluorosilicate product storage tank. The condensate outlet of the drying device is connected to a water collection tank.

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