Efficient defluorination built-in crystallizer based on transformation project

Abstract

A diluter is fixed on the side wall of a coagulating basin, fluorine-containing wastewater and a calcium-containing medicament can enter a barrel structure of the diluter from top to bottom through a liquid inlet pipeline, and flow downwards along the barrel structure of the diluter to enter the coagulating basin; the stirrer can stir liquid in the coagulating basin, the crystal reflux device can reflux crystal precipitates at the bottom of the sedimentation basin into the coagulating basin to continue to participate in crystallization, the crystal discharging device can regularly discharge the crystal precipitates at the bottom of the coagulating basin into the cyclone separator, and the cyclone separator can perform cyclone separation on large-particle crystals and small-particle crystals. Large-particle crystals are discharged from a crystal outlet in the lower end of the cyclone separator, small-particle crystals are discharged from a water outlet in the upper end of the cyclone separator along with water flow and enter the coagulating basin, the coagulating basin and the sedimentation basin of a coagulating sedimentation process can be transformed into a crystallization fluidized bed process, the calcium fluoride crystal recovery rate is increased, and the medicament cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a high-efficiency defluoridation built-in crystallizer based on a retrofit project. Background Technology

[0002] Fluorine plays a crucial role in modern industry and is an indispensable raw material for the photovoltaic industry. Fluorite, the only natural source of fluorine, is a rare and non-renewable mineral. In an environment of resource scarcity, efficient fluorine recovery is particularly critical.

[0003] With industry development and technological advancements, fluidized bed and high-efficiency mixed reactor technologies are being widely applied in the defluorination field. These new processes often offer higher fluorine recovery efficiency, lower energy consumption, and better environmental performance. Companies that fail to adopt these advanced technologies will gradually find themselves at a disadvantage in market competition. However, the design and construction of existing tanks are often incompatible with the requirements of these new processes. For example, some new fluorine recovery processes require more precise temperature control, more stable flow regulation, and more efficient gas-liquid separation, conditions that existing tanks inherently lack, making them unsuitable for these new processes. Adopting new processes requires significant investment in site construction, equipment purchase, and material procurement, and the long construction period can disrupt normal fluorine recovery production, leading to economic losses. Meanwhile, existing tanks are either left idle or dismantled, resulting in substantial resource waste. Furthermore, with the rapid pace of technological advancements, factories need to upgrade their processes, further exacerbating the waste caused by continuous process updates. Summary of the Invention

[0004] To overcome the above shortcomings, the present invention provides a high-efficiency defluorination built-in crystallizer based on the renovation project. This high-efficiency defluorination built-in crystallizer based on the renovation project can upgrade and renovate the original tank, improve the fluoride recovery rate, and the renovation is simple and low in cost.

[0005] The technical solution adopted by this invention to solve its technical problem is: a high-efficiency defluorination built-in crystallizer based on a renovation project, including a coagulation tank and a sedimentation tank. The mixed liquid in the coagulation tank can be discharged into the sedimentation tank for sedimentation treatment. The upper side wall of the sedimentation tank is provided with an outlet for discharging the upper clear water. It also includes a diluent, a stirrer, a crystal reflux device, a crystal discharge device, and a cyclone separator. At least one diluent is fixedly installed on the side wall of the coagulation tank. The diluent includes a cylindrical structure with openings at the top and bottom and an inlet pipe installed at the upper end of the cylindrical structure. Fluoride-containing wastewater and calcium-containing reagents can enter the cylindrical structure of the diluent from top to bottom through the inlet pipe and flow along the cylinder of the diluent. The liquid flows downwards into the coagulation tank. An agitator is installed inside the coagulation tank to agitate the liquid. The inlet of the crystal reflux device is located at the bottom of the sedimentation tank, and the outlet is located above the opening of the coagulation tank. The crystal reflux device can return the crystal sediment from the bottom of the sedimentation tank to the coagulation tank to continue crystallization. The crystal discharge device can periodically discharge the crystal sediment from the bottom of the coagulation tank into the hydrocyclone separator. The hydrocyclone separator can separate large crystal particles from water and small crystal particles through hydrocyclone separation. Large crystal particles are discharged from the crystal outlet at the bottom of the hydrocyclone separator, while small crystal particles are discharged with the water flow from the drain outlet at the top of the hydrocyclone separator and enter the coagulation tank through the drainage pipe.

[0006] Fluoride-containing wastewater and calcium-containing reagents enter the diluent through the inlet pipe. While being diluted by the liquid in the diluent, the wastewater and reagents continue to flow downwards, eventually entering the coagulation tank through the bottom of the diluent. After sufficient reaction in the coagulation tank, the wastewater and reagents enter the sedimentation tank. The calcium fluoride crystals produced by the reaction settle to the bottom of the sedimentation tank. The supernatant leaves the system through the outlet, while the calcium fluoride crystals return to the coagulation tank through the crystal return device. New calcium fluoride produced in the coagulation tank adheres to the surface of small calcium fluoride crystals, causing them to grow and settle. After settling to the bottom of the coagulation tank, the calcium fluoride crystals enter the hydrocyclone separator through the crystal discharge device for hydrocyclone separation. Larger calcium fluoride crystals leave the system through the crystal outlet at the bottom of the hydrocyclone and can be further dewatered to form calcium fluoride crystal products. Smaller calcium fluoride crystals return to the coagulation tank through the drain outlet at the top of the hydrocyclone to continue growing as seed crystals.

[0007] As a further improvement of the present invention, there are multiple diluents, which are evenly distributed on the inner wall of the coagulation tank. Fluoride-containing wastewater and calcium-containing reagents enter different diluents for dilution. Ideally, there are four diluents, distributed at the four corners of the coagulation tank. Depending on the influent flow rate and concentration, 2-3 diluents are used to dilute the fluoride-containing wastewater, and 1-2 diluents are used to dilute the calcium-containing reagents.

[0008] As a further improvement of the present invention, the upper end of the diluent is lower than the set height of the liquid level at the outlet of the sedimentation tank. A propeller is installed inside the diluent, which can push the liquid entering the diluent from the top downwards. The top of the diluent's cylindrical structure is preferably 10 cm lower than the outlet of the sedimentation tank. The propeller drives 3-10 times the inlet flow rate of dilution water into the diluent for dilution. The propeller can be a paddle type, propeller type, turbine type, rotor type, or ribbon type.

[0009] As a further improvement of the present invention, the agitator is located at the center of the coagulation tank. The agitator includes a stirring motor, a stirring shaft, and stirring blades. The stirring motor drives the stirring shaft to rotate. Two layers of stirring blades are fixedly installed on the stirring shaft at intervals. The stirring blades have an airfoil structure, with the upper and lower stirring blades arranged symmetrically. The bottom of the lower stirring blade is one-third the height of the total height of the coagulation tank from the bottom of the tank. By using symmetrical double-layer stirring blades, the mixture in the coagulation tank is horizontally stirred while simultaneously being tumbled vertically, ensuring thorough mixing of the fluoride-containing wastewater and the calcium-containing reagent. This also keeps small calcium fluoride crystals suspended in the coagulation tank, facilitating the adhesion of newly formed calcium fluoride to their surface. The lower stirring blades are positioned at a sufficient distance from the bottom of the coagulation tank to prevent large calcium fluoride crystals settled at the bottom from being disturbed.

[0010] As a further improvement of the present invention, a central cylinder is fixedly installed in the sedimentation tank at the center of the sedimentation tank. The lower end of the central cylinder is open, and there is a set distance between the lower end of the central cylinder and the bottom surface of the sedimentation tank. An overflow port is provided on the upper side wall of the coagulation tank. The height of the overflow port is lower than the height of the sedimentation tank outlet by a set distance. The overflow port of the coagulation tank is connected to the upper end of the central cylinder in the sedimentation tank through an overflow pipe. The mixed liquid in the coagulation tank can enter the central cylinder of the sedimentation tank through the overflow pipe. The mixed liquid in the coagulation tank directly enters the central cylinder in the middle of the sedimentation tank through the overflow port and the overflow pipe. The calcium fluoride crystals in the mixed liquid will sink rapidly when they hit the side wall of the central cylinder and eventually accumulate at the center of the bottom of the sedimentation tank.

[0011] As a further improvement of the present invention, the lower end of the central cylinder forms a flared mouth with a gradually increasing opening.

[0012] As a further improvement of the present invention, the crystal reflux device includes a reflux pipe and a reflux pump. The bottom of the sedimentation tank forms a pointed bottom structure and is also equipped with a three-way pipe. One end of the three-way pipe is connected to the center of the pointed bottom structure of the sedimentation tank through a pipe. The second end of the three-way pipe is connected to a sediment discharge pipe. The third end of the three-way pipe is connected to one end of the reflux pipe, and the other end of the reflux pipe extends above the opening of the coagulation tank. The second and third ends of the three-way pipe are respectively equipped with control valves to control the opening and closing of the pipes. When the control valve in the third end of the three-way pipe is open, the reflux pump can pump the crystal sediment at the bottom of the sedimentation tank into the coagulation tank along the reflux pipe. The crystal reflux device can discharge calcium fluoride crystals directly from the sedimentation tank through the sediment discharge pipe, or it can supplement calcium fluoride crystals into the coagulation tank as seed crystals through the reflux pipe. The control valves in the second and third ends of the three-way pipe are preferably interconnected, and only one of them can be opened. The control valve in the third end of the three-way pipe is preferably linked to the reflux pump, that is, when the control valve in the third end of the three-way pipe is opened, the reflux pump automatically starts.

[0013] As a further improvement of the present invention, the crystal removal device includes an air-lift crystal removal pipe and an air inlet pipe. One end of the air-lift crystal removal pipe extends into the bottom of the coagulation tank, and the other end of the air-lift crystal removal pipe is connected to the inlet of a hydrocyclone separator. An inclined air inlet nozzle is provided on the side wall of one end of the air-lift crystal removal pipe, and the air inlet nozzle is connected to the air inlet pipe. The airflow in the air inlet pipe enters the air-lift crystal removal pipe through the air inlet nozzle and flows towards the other end of the air-lift crystal removal pipe, thereby creating a negative pressure at one end of the air-lift crystal removal pipe. The negative pressure at one end of the air-lift crystal removal pipe can adsorb the crystal precipitates deposited at the bottom of the coagulation sedimentation tank. The air-lift crystal removal pipe lifts the calcium fluoride crystals deposited at the bottom of the coagulation tank to the hydrocyclone separator through negative pressure. The crystal removal device can also be implemented using a pump and pipeline. The above structure is easy to install and does not damage the original structure of the coagulation tank.

[0014] As a further improvement of the present invention, a crystal-absorbing ring is fixedly installed at the bottom of the coagulation tank. A predetermined gap exists between the lower side of the crystal-absorbing ring and the bottom of the coagulation tank. The crystal-absorbing ring has several evenly spaced crystal-absorbing ports, and one end of the crystal-absorbing ring is connected to the air-lift crystal discharge pipe. The crystal-absorbing ring can be a circular ring structure, with the center of the ring structure coinciding with the center of the coagulation tank. The diameter of the circular ring structure is optimally three-quarters of the width of the coagulation tank. The crystal-absorbing ring can be a single ring or a multi-ring interconnected structure.

[0015] As a further improvement of the present invention, a pressure reducing valve is provided on the air-lift crystal discharge pipe, a flow control valve is provided at the inlet of the hydrocyclone, and regulating switches are respectively installed on the water outlet at the upper end and the crystal outlet at the lower end of the hydrocyclone. These regulating switches can adjust the flow rates at the water outlet at the upper end and the crystal outlet at the lower end of the hydrocyclone. The above structure allows adjustment of the feed flow rate of the hydrocyclone, the discharge rate at the crystal outlet of the hydrocyclone, and the return flow rate at the water outlet of the hydrocyclone.

[0016] The beneficial technical effects of this invention are as follows: This invention transforms the traditional coagulation and sedimentation processes into a crystallization fluidized bed process by adding prefabricated components to the coagulation and sedimentation tanks. This results in larger calcium fluoride crystals extracted from fluoride-containing wastewater, lower water content, and higher recovery rates. During the modification process, only a diluent, agitator, and crystal removal device need to be installed in the coagulation tank. The modifications to the existing coagulation and sedimentation tanks are minimal, the modification speed is fast, and it does not involve changes to the main structure. Workers are already familiar with the operating characteristics and procedures of the existing coagulation and sedimentation tanks, reducing operational difficulties caused by significant changes in equipment and processes, and ensuring production continuity. Furthermore, the existing coagulation and sedimentation tanks have been validated through long-term production; the modification only requires addressing key aspects. Optimization effectively avoids the technical risks that may arise from completely new designs and construction, thereby ensuring the stable operation of the fluoride recovery system. This invention significantly reduces construction costs by renovating existing coagulation and sedimentation tanks, avoiding the high expenses associated with land acquisition, foundation treatment, and main structure construction required for new tanks. Funds can then be concentrated on upgrading core fluoride recovery technology and equipment. This invention upgrades existing coagulation and sedimentation tanks, saving not only time and money but also increasing the fluoride recovery rate while reducing reagent costs. Furthermore, by arranging diluents within the coagulation tank, this invention adjusts the flow ratios of influent, dosing, and dilution water, solving the problem of high-load influent impact and the need to use large amounts of tap water for reagent preparation. Attached Figure Description

[0017] Figure 1 This is a three-dimensional diagram illustrating the structural principle of the present invention;

[0018] Figure 2 This is a front view illustrating the structural principle of the present invention;

[0019] Figure 3 This is a top view illustrating the structural principle of the present invention;

[0020] Figure 4 This is a perspective view of the coagulation tank body of the present invention;

[0021] Figure 5 This is a perspective view of the sedimentation tank of the present invention;

[0022] Figure 6 This is a perspective view of the diluent of the present invention;

[0023] Figure 7 This is a perspective view of the stirrer of the present invention;

[0024] Figure 8 for Figure 7 Enlarged view of section A in the middle;

[0025] Figure 9 This is a perspective view of the crystal reflux device of the present invention;

[0026] Figure 10 for Figure 9 Enlarged view of section B in the middle;

[0027] Figure 11 This is a perspective view of the cyclone separator of the present invention;

[0028] Figure 12 This is a perspective view of the crystal arranging device of the present invention;

[0029] Figure 13 for Figure 12 Enlarged view of section C.

[0030] Explanation of reference numerals in the attached figures:

[0031] Coagulation tank---30; Sedimentation tank---10; Outlet---102; Diluter---60; Agitator---40; Crystal reflux device---20; Crystal discharge device---70; Cyclone separator---50; Cylinder structure---602; Inlet pipe---601; Crystal outlet---503; Drain outlet---502; Propeller---603; Agitator shaft---401; Agitator blades---402; Central cylinder---101; Overflow port---301; Reflux pipe---201; Pointed bottom structure---202; Air lift crystal discharge pipe---701; Crystal suction ring---702; Crystal suction port---7021. Detailed Implementation

[0032] Example 1: A high-efficiency defluorination built-in crystallizer based on a renovation project. A diluent 60 is installed at each of the four corners of the coagulation tank 3. Each diluent 60 includes a cylindrical structure 602 with openings at the top and bottom, and an inlet pipe 601 installed at the upper end of the cylindrical structure 602. An internal propeller 603 is installed inside the cylindrical structure 602 of the diluent 60. A double-layered agitator 40 is installed in the middle of the coagulation tank 3. The lower end of the air-lift crystal-discharging pipe 701 of the crystal-discharging device 70 extends into the bottom of the coagulation tank 3. A crystal-absorbing ring 702 is installed at the lower end of the air-lift crystal-discharging pipe 701. A central cylinder 101 is installed in the middle of the sedimentation tank 10. The overflow port 301 of the coagulation tank 3 is connected to the upper end of the central cylinder 101 through an overflow pipe. Fluoride wastewater and calcium-containing reagents pass through the diluents 60... The liquid inlet pipe 601 at the top enters the diluent 60, and then enters the coagulation tank 3 through the lower part of the diluent 60. After the fluoride-containing wastewater and calcium-containing reagent react fully in the coagulation tank 3, the overflow enters the sedimentation tank 10. The supernatant in the sedimentation tank 10 leaves the system through the outlet 102. The calcium fluoride crystals settle to the bottom of the sedimentation tank 10. The calcium fluoride crystals at the bottom of the sedimentation tank 10 enter the coagulation tank 3 through the crystal return device 20. The calcium fluoride crystals generated in the coagulation tank 3 settle to the bottom of the coagulation tank 3. The crystal discharge device 70 uses negative pressure to send them along the air-lift crystal discharge pipe 701 into the hydrocyclone separator 50. Large calcium fluoride crystals are discharged through the crystal outlet 503 at the lower end of the hydrocyclone, and smaller calcium fluoride crystals return to the coagulation tank 3 through the drain outlet 502 at the top of the hydrocyclone.

[0033] 1500ppm low-concentration fluoride-containing wastewater enters the three diluents 60 above the coagulation tank 3 via inlet pipes 601 at a total flow rate of 300 CMD. Each diluent 60 has a built-in paddle propeller 603 driving a flow rate of 500 CMD and 100 CMD of influent water to mix in a large proportion within the cylindrical structure 602 of the diluent 60. Simultaneously, the mixture reacts with a small amount of calcium-containing reagent in the dilution water to form calcium fluoride crystals. 30000ppm calcium-containing reagent is introduced into the coagulation tank 3 via... An inlet pipe 601 above a diluter 60 enters the diluter 60 at a total flow rate of 15 CMD. The diluter 60 has a built-in paddle propeller 603 that drives a flow rate of 135 CMD and 15 CMD of calcium-containing agent to be diluted in a large proportion within a cylindrical structure 602. At the same time, it reacts with a small amount of fluoride ions in the dilution water to generate calcium fluoride crystals. The fluoride-containing wastewater and calcium-containing agent enter the coagulation tank 3 through the bottom of the diluter 60. The fluoride-containing wastewater and calcium-containing agent are fully reacted under the agitation of the double-layer stirring fan blades 402 in the coagulation tank 3. The reacted water (total fluoride 100 ppm, calcium ions 200 ppm) and smaller calcium fluoride crystals overflow into sedimentation tank 10. Material separation occurs through the central cylinder 101. The supernatant (total fluoride 10 ppm, calcium ions 80 ppm) leaves the system through outlet 102. The smaller calcium fluoride crystals settle to the bottom of sedimentation tank 10 and are enriched by crystal reflux device 20. They are then returned to coagulation tank 3 at a flow rate of 48 CMD to continue the reaction. The calcium fluoride crystals produced in coagulation tank 3 settle naturally by gravity to the area of ​​the crystal suction ring 702 of the crystal removal device. They are then air-lifted into hydrocyclone separator 50 at a flow rate of 30 CMD. Larger calcium fluoride crystals leave the system through crystal outlet 503 at the bottom of the hydrocyclone at a flow rate of 5 CMD, while smaller calcium fluoride crystals return to coagulation tank 3 through drain outlet 502 at the top of the hydrocyclone at a flow rate of 25 CMD.

[0034] Example 2: A high-efficiency defluorination built-in crystallizer based on a modification project, with the same structure as Example 1.

[0035] 20,000 ppm high-concentration fluoride-containing wastewater enters diluter 60 at a total flow rate of 100 CMD through inlet pipes 601 located above two diluter 60s diagonally opposite each other in coagulation tank 3. Each diluter 60 has a built-in paddle propeller 603 driving a flow rate of 1,000 CMD and 50 CMD of inlet water to mix in a large proportion within the cylindrical body structure 602 of the diluter 60. Simultaneously, the mixture reacts with a small amount of calcium-containing reagent in the dilution water to form calcium fluoride crystals. 30,000 ppm of calcium-containing reagent is introduced through another... The inlet pipes 601 above the two diluters 60 at opposite corners enter the diluters 60 at a total flow rate of 70 CMD. The paddle propeller 603 built into the diluters 60 drives the calcium-containing agent with a flow rate of 630 CMD and 70 CMD to be diluted to a large proportion within the cylindrical structure 602 of the diluters 60. At the same time, it reacts with a small amount of fluoride ions in the dilution water to generate calcium fluoride crystals. The fluoride-containing wastewater and the calcium-containing agent enter the coagulation tank 3 through the bottom of the diluters 60, where they react fully under the stirring of the double-layer stirring fan blades 402. The reacted water (total fluoride 400 ppm, calcium ions 600 ppm) and smaller calcium fluoride crystals overflow into sedimentation tank 10. Material separation occurs through the central cylinder 101. The supernatant (total fluoride 15 ppm, calcium ions 100 ppm) leaves the system through outlet 102. The smaller calcium fluoride crystals settle to the bottom of sedimentation tank 10 and are enriched by crystal reflux device 20. They are then returned to coagulation tank 3 at a flow rate of 96 CMD to continue the reaction. The calcium fluoride crystals produced in coagulation tank 3 naturally settle by gravity to the area of ​​crystal suction ring 702 in the crystal removal device. They are then air-lifted into hydrocyclone separator 50 at a flow rate of 100 CMD. Larger calcium fluoride crystals leave the system through crystal outlet 503 at the bottom of the hydrocyclone at a flow rate of 20 CMD, while smaller calcium fluoride crystals return to coagulation tank 3 through drain outlet 502 at the top of the hydrocyclone at a flow rate of 80 CMD.

Claims

1. A high-efficiency defluoridation built-in crystallizer based on a renovation project, comprising a coagulation tank (30) and a sedimentation tank (10), wherein the mixed liquid in the coagulation tank can be discharged into the sedimentation tank for sedimentation treatment, and the upper side wall of the sedimentation tank is provided with an outlet (102) for discharging the upper clear water, characterized in that: It also includes a diluent (60), a stirrer (40), a crystal reflux device (20), a crystal removal device (70), and a cyclone separator (50). At least one diluent is fixedly installed on the side wall of the coagulation tank. The diluent includes a cylindrical structure (602) with openings at the top and bottom and an inlet pipe (601) installed at the upper end of the cylindrical structure. Fluorine-containing wastewater and calcium-containing reagents can enter the cylindrical structure of the diluent from top to bottom through the inlet pipe and flow downwards along the cylindrical structure of the diluent into the coagulation tank. The stirrer is installed in the coagulation tank and can stir the liquid in the coagulation tank. The inlet of the reflux device is located at the bottom of the sedimentation tank, and the outlet of the crystal reflux device is located above the opening of the coagulation tank. The crystal reflux device can return the crystal sediment at the bottom of the sedimentation tank to the coagulation tank to continue to participate in crystallization. The crystal discharge device can periodically discharge the crystal sediment at the bottom of the coagulation tank into the hydrocyclone separator. The hydrocyclone separator can separate large crystal particles from water and small crystal particles by hydrocyclone separation. Large crystal particles are discharged from the crystal outlet (503) at the bottom of the hydrocyclone separator, and small crystal particles are discharged with the water flow from the drain outlet (502) at the top of the hydrocyclone separator and enter the coagulation tank through the drainage pipe.

2. The high-efficiency defluorination built-in crystallizer based on the renovation project according to claim 1, characterized in that: The diluents are multiple and are evenly distributed on the inner wall of the coagulation tank. Fluorine-containing wastewater and calcium-containing reagents enter different diluents for dilution.

3. The high-efficiency defluorination built-in crystallizer based on the renovation project according to claim 1, characterized in that: The upper end of the diluent is lower than the set height of the liquid level at the outlet of the sedimentation tank. A propeller (603) is installed inside the diluent, which can push the liquid entering the diluent from the top downwards.

4. The high-efficiency defluorination built-in crystallizer based on the renovation project according to claim 1, characterized in that: The agitator is located at the center of the coagulation tank. The agitator includes an agitator motor, an agitator shaft (401), and agitator blades (402). The agitator motor drives the agitator shaft to rotate. Two layers of agitator blades are fixedly installed on the agitator shaft at intervals. The agitator blades are airfoil structures. The upper agitator blades and the lower agitator blades are symmetrically arranged vertically. The bottom of the lower agitator blades is one-third the height of the total height of the coagulation tank from the bottom of the tank.

5. The high-efficiency defluorination built-in crystallizer based on the renovation project according to claim 1, characterized in that: A central cylinder (101) is fixedly installed in the sedimentation tank at the center of the sedimentation tank. The lower end of the central cylinder is open, and there is a set distance between the lower end of the central cylinder and the bottom surface of the sedimentation tank. An overflow port (301) is provided on the upper side wall of the coagulation tank. The height of the overflow port is lower than the height of the sedimentation tank outlet by a set distance. The overflow port of the coagulation tank is connected to the upper end of the central cylinder in the sedimentation tank through an overflow pipe. The mixed liquid in the coagulation tank can enter the central cylinder of the sedimentation tank through the overflow pipe.

6. The high-efficiency defluorination built-in crystallizer based on the renovation project according to claim 5, characterized in that: The lower end of the central cylinder forms a funnel-shaped opening that gradually increases in size.

7. The high-efficiency defluorination built-in crystallizer based on the renovation project according to claim 1, characterized in that: The crystal reflux device includes a reflux pipe (201) and a reflux pump. The bottom of the sedimentation tank forms a pointed bottom structure (202) and is also equipped with a three-way pipe. One end of the three-way pipe is connected to the center of the pointed bottom structure of the sedimentation tank through a pipe. The second end of the three-way pipe is connected to a sediment discharge pipe. The third end of the three-way pipe is connected to one end of the reflux pipe. The other end of the reflux pipe extends above the opening of the coagulation tank. The second and third ends of the three-way pipe are respectively equipped with control valves to control the opening and closing of the pipes. When the control valve in the third end of the three-way pipe is open, the reflux pump can pump the crystal sediment at the bottom of the sedimentation tank into the coagulation tank along the reflux pipe.

8. The high-efficiency defluorination built-in crystallizer based on the renovation project according to claim 1, characterized in that: The crystal removal device includes an air-lift crystal removal pipe (701) and an air inlet pipe. One end of the air-lift crystal removal pipe extends into the bottom of the coagulation tank, and the other end of the air-lift crystal removal pipe is connected to the inlet of the cyclone separator. An inclined air inlet is provided on the side wall of one end of the air-lift crystal removal pipe. The air inlet is connected to the air inlet pipe. The airflow in the air inlet pipe enters the air-lift crystal removal pipe through the air inlet and flows towards the other end of the air-lift crystal removal pipe, so that a negative pressure is formed at one end of the air-lift crystal removal pipe. The negative pressure at one end of the air-lift crystal removal pipe can adsorb the crystal precipitates deposited at the bottom of the coagulation sedimentation tank.

9. The high-efficiency defluorination built-in crystallizer based on the renovation project according to claim 8, characterized in that: A crystal-absorbing ring (702) is fixedly installed at the bottom of the coagulation tank. There is a set gap between the lower side of the crystal-absorbing ring and the bottom of the coagulation tank. Several crystal-absorbing ports (7021) are evenly spaced on the crystal-absorbing ring. The crystal-absorbing ring is connected to one end of the air-lift crystal discharge tube.

10. The high-efficiency defluorination built-in crystallizer based on the renovation project according to claim 8, characterized in that: The air-lift crystal discharge tube is equipped with a pressure reducing valve, the inlet of the cyclone separator is equipped with a flow control valve, and the water outlet at the upper end and the crystal outlet at the lower end of the cyclone separator are respectively equipped with regulating switches, which can adjust the flow rate of the water outlet at the upper end and the crystal outlet at the lower end of the cyclone separator.

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