Calcium fluoride composite inducer and calcium fluoride induction purification system and method

Abstract

The invention discloses a calcium fluoride composite inducer and a calcium fluoride induction purification system and method.The calcium fluoride composite inducer is prepared from 50-100 parts of styrene, 100-150 parts of formaldehyde polymer, 0.1-0.5 part of polyacrylamide, 2-4 parts of tetrafluoroethylene resin and 300-400 parts of water; fluorine-containing wastewater enters the calcium fluoride induction purification system to be treated through a calcium fluoride induction purification method, on the basis of a two-stage fluorine removal process, calcium fluoride in a first-stage fluorine removal reaction tank is adsorbed through a calcium fluoride composite inducer, and the calcium fluoride composite inducer is separated from other impurity sludge through a first-stage hydraulic separator; the calcium fluoride is separated from the calcium fluoride composite inducer through a first-stage hydraulic separator, a high-purity calcium fluoride product is formed through filter pressing, the calcium fluoride composite inducer can be reused, the calcium fluoride obtained through the method is high in purity, the induction process is simple and safe, and the treatment cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, in particular to a calcium fluoride composite inducer and a calcium fluoride induction purification system and method. Background Art

[0002] The photovoltaic industry market continues to expand, generating a large amount of fluoride-containing wastewater. According to the existing two-stage defluorination process, a large amount of sludge containing calcium fluoride will be produced. Calcium fluoride can produce hydrofluoric acid, and can also be used as a common additive in metallurgy, aluminum smelting and other industries. It can also be used to burn bricks and concrete, etc. It is called the "second rare earth" and has broad application prospects. However, depending on the production process of the enterprise, the sludge generated after wastewater treatment contains impurities such as silicon dioxide, calcium carbonate, calcium oxide and metal oxides in addition to calcium fluoride, resulting in a low purity of calcium fluoride in the fluoride-containing waste residue and low utilization value.

[0003] Therefore, many environmental protection organizations have studied the methods of purifying low-purity calcium fluoride sludge, mainly including flotation and chemical methods. Flotation is often used to extract calcium fluoride from fluorite ore. The added flotation agent can make calcium fluoride adsorb to the microbubbles in the water, so that it floats to the surface of the liquid. However, the muddy water mixed suspension produced after actual treatment also contains impurities such as silicon dioxide. The composition structure of these impurities is different from the properties of the mineral surface, which has a certain impact on the purity of calcium fluoride.

[0004] The chemical method is an integrated process that combines two or more methods of strong acid treatment, strong alkali and calcination treatment. Strong acid and strong alkali are used to remove calcium-containing impurities in sludge, and calcination treatment can decompose organic matter in sludge at high temperature. This method has a high purification efficiency, but the process is complicated. Strong acids such as HF and HCl with extremely low pH are used, which pose certain safety hazards during operation and storage. Some solutions will also have heating reactions during strong acid and strong alkali treatment, which can easily cause secondary fluorine pollution and safety risks. The high coal consumption or high natural gas consumption of high-temperature calcination processes will increase costs and release harmful greenhouse gases.

[0005] Therefore, the existing methods generally have the defects of high cost, high energy consumption, long time consumption, complex process, and certain safety hazards. Therefore, it is necessary to develop a safe and efficient purification path. Summary of the invention

[0006] In order to overcome the above-mentioned defects, the present invention provides a calcium fluoride composite inducer and a calcium fluoride induction purification system and method. The calcium fluoride composite inducer is used to carry out a two-stage defluorination process to defluorinate fluoride-containing wastewater, which can improve the purity of calcium fluoride, and the induction process flow during the defluorination process is simple and the treatment cost is low.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a calcium fluoride composite inducer, comprising the following components in parts by weight:

[0008] 50-100 parts of styrene, 100-150 parts of oxymethylene polymer, 0.1-0.5 parts of polyacrylamide, 2-4 parts of tetrafluoroethylene resin and 300-400 parts of water.

[0009] As a further improvement of the present invention, the particle size of the calcium fluoride composite inducer is 100-150 um.

[0010] As a further improvement of the present invention, the calcium fluoride composite inducer is a porous structure with a molecular gap of 20-30 um and a porosity of 50%.

[0011] A calcium fluoride induction purification method comprises the following steps:

[0012] Step 1: treating the fluorine-containing wastewater with a two-stage defluorination process. In the two-stage defluorination process, a calcium fluoride composite inducer is added to the fluorine-containing wastewater undergoing a defluorination reaction, and the calcium fluoride composite inducer adsorbs the calcium fluoride sludge generated by the defluorination reaction of the fluorine-containing wastewater;

[0013] Step 2: After the defluorination reaction is completed, the calcium fluoride composite inducer adsorbed with calcium fluoride sludge and other impurity sludge are sent to the primary hydraulic diverter for sludge separation. The calcium fluoride composite inducer adsorbed with calcium fluoride sludge is heavier than other impurity sludge, and then flows out from the bottom of the primary hydraulic diverter and enters the calcium fluoride collection tank. Other impurity sludge flows out from the upper part of the primary hydraulic diverter along with the water flow and enters the primary defluorination flocculation tank. The primary defluorination flocculation tank can be the original flocculation tank in the two-stage defluorination process.

[0014] Step 3: adding APAM to the first flocculation tank for polymerization reaction, and removing other impurity sludge by precipitation; at the same time, the separated calcium fluoride composite inducer adsorbed with calcium fluoride sludge enters the secondary hydraulic separator for separation of the calcium fluoride composite inducer and the calcium fluoride sludge;

[0015] Step 4: The separated calcium fluoride composite inducer is reused; the separated calcium fluoride sludge enters a flocculation sedimentation tank, which is an additional flocculation sedimentation tank in addition to the original two-stage defluorination process, and APAM is added to the flocculation sedimentation tank for flocculation reaction, and the calcium fluoride sludge is collected by precipitation and dehydrated to form usable high-purity calcium fluoride sludge.

[0016] On the basis of the conventional two-stage defluorination process, by adding the calcium fluoride composite inducer of the present invention, the calcium fluoride formed by the combination of fluoride ions in the wastewater and calcium ions in the calcium source can be fully adsorbed, and then the calcium fluoride can be separated from other impurity sludges in the wastewater, so as to avoid other impurity sludges from mixing into the calcium fluoride sludge, thereby ensuring the purity of the calcium fluoride sludge. The calcium fluoride sludge of the present invention is also separated from the calcium fluoride composite inducer, so that the calcium fluoride inducer can be recycled, thus saving the calcium fluoride induction cost and further ensuring the purity of the calcium fluoride sludge.

[0017] As a further improvement of the present invention, the staged defluorination process uses at least one of lime and calcium chloride as a calcium source. Lime can be added alone, calcium chloride can be added alone, or lime and calcium chloride can be used together. The ratio of calcium chloride to lime can be adjusted according to the reaction pH and the chloride ion concentration requirements in the discharge.

[0018] As a further improvement of the present invention, the two-stage defluorination process includes a primary defluorination system and a secondary defluorination system, the primary defluorination system includes a primary defluorination reaction tank for supplying a calcium source and fluorine-containing wastewater for defluorination reaction, and the calcium fluoride composite inducer is added into the primary defluorination reaction tank. Calcium fluoride formed by the combination of fluoride ions in the wastewater and calcium ions in the calcium source can be quickly adsorbed by the calcium fluoride composite inducer, so that defluorination reaction and adsorption are carried out simultaneously, which is beneficial to improving the wastewater treatment efficiency. Of course, after the fluoride ions in the wastewater and the calcium ions in the calcium source are fully reacted, the calcium fluoride composite inducer can be added to adsorb calcium fluoride. This is an equivalent replacement scheme that can be easily thought of by those skilled in the art based on this patent, and it also belongs to the protection scope of this patent.

[0019] As a further improvement of the present invention, the amount of lime added to the primary defluorination reaction tank is controlled by pH to maintain the pH in the primary defluorination reaction tank at 6.5-7.5.

[0020] As a further improvement of the present invention, the rotation speed of the first-stage hydraulic separator is 200-500 r / min, the rotation speed of the second-stage hydraulic separator is 2000-2500 r / min, and the separation time is 1-5 min.

[0021] As a further improvement of the present invention, in the step 1, while the fluorine-containing wastewater is undergoing a defluorination reaction, the fluorine-containing wastewater is stirred, and under the hydraulic action generated by the stirring, calcium fluoride and other impurity sludge are in a fully separated state, and the calcium fluoride composite inducer fully adsorbs the calcium fluoride in the sludge. As the defluorination reaction proceeds, fluorine and calcium in the water combine to form calcium fluoride, and other impurities are also generated. In this process, under the hydraulic action generated by the stirring, calcium fluoride and other impurities are in a relatively fully separated state, and the composite resin in the calcium fluoride composite inducer adsorbs the calcium fluoride in the sludge, and other impurity sludge will not be adsorbed by the calcium fluoride composite inducer.

[0022] As a further improvement of the present invention, in step 4, the calcium fluoride sludge collected by precipitation is pumped into a filter press by a pump, and is dehydrated by filter pressing to form usable high-purity calcium fluoride sludge.

[0023] A calcium fluoride induced purification system comprises a primary defluorination system, a secondary defluorination system (10) and a calcium fluoride induced separation system, wherein:

[0024] The primary defluorination system comprises a primary defluorination reaction tank (1), a primary hydraulic separator (2), a primary defluorination flocculation tank (3) and a primary defluorination sedimentation tank (4);

[0025] The calcium fluoride induced separation system comprises a calcium fluoride collection tank (5), a secondary hydraulic separator (6), a flocculation sedimentation tank (7), an inducer collection tank (8) and a filter press (9);

[0026] The primary defluorination reaction tank is provided with a wastewater inlet pipe, a calcium source dosing device and a calcium fluoride composite inducer dosing device, fluorine-containing wastewater can enter the primary defluorination reaction tank through the wastewater inlet pipe, the calcium source dosing device and the calcium fluoride composite inducer dosing device can respectively add a calcium source and a calcium fluoride composite inducer to the primary defluorination reaction tank in a quantitative manner, the water outlet of the primary defluorination reaction tank is connected with the water inlet of the primary hydraulic separator, the primary hydraulic separator can separate the calcium fluoride sludge from other impurity sludges, the bottom separation port of the primary hydraulic separator is connected with the mud inlet of the calcium fluoride collection tank, and the primary hydraulic separator The first-stage hydraulic separator discharges the separated calcium fluoride sludge into the calcium fluoride collection tank. The separation port above the first-stage hydraulic separator is connected to the water inlet of the first-stage defluorination flocculation tank. The first-stage hydraulic separator discharges the wastewater after the first-stage defluorination reaction together with other impurity sludge into the first-stage defluorination flocculation tank. The first-stage defluorination flocculation tank is provided with a flocculant dosing device. The flocculant dosing device can quantitatively add APAM to the first-stage defluorination flocculation tank for polymerization reaction. The outlet of the first-stage defluorination flocculation tank is connected to the water inlet of the first-stage defluorination sedimentation tank. The first-stage defluorination sedimentation tank can sediment other impurity sludge after the polymerization reaction. The water outlet of the primary defluorination sedimentation tank is connected with the water inlet of the secondary defluorination system. The secondary defluorination system can perform a defluorination reaction on the wastewater after the primary defluorination reaction to remove the remaining fluoride ions in the wastewater. The calcium fluoride collection tank is connected with the inlet of the secondary hydraulic separator through a pipeline. The calcium fluoride composite inducer adsorbed with calcium fluoride sludge collected in the calcium fluoride collection tank can be pumped into the secondary hydraulic separator. The secondary hydraulic separator can separate the calcium fluoride sludge from the calcium fluoride composite inducer. The bottom separation port of the secondary hydraulic separator is connected with the inducer collection tank. The secondary hydraulic separator The bottom separation port of the device sends the separated calcium fluoride composite inducer into the inducer collection tank for collection. The inducer collection tank is connected with the calcium fluoride composite inducer dosing device through a pipeline to supply the calcium fluoride composite inducer. The upper separation port of the secondary hydraulic separator is connected with the inlet of the flocculation sedimentation tank. The flocculation sedimentation tank is also provided with a flocculant dosing device. The flocculant dosing device can quantitatively add APAM into the flocculation sedimentation tank for flocculation reaction precipitation. The sedimentation discharge port of the flocculation sedimentation tank is connected with the mud inlet of the filter press. The filter press can filter and dehydrate the water-containing calcium fluoride sludge.

[0027] The invention has the following beneficial effects: the calcium fluoride composite inducer of the invention uses styrene-formaldehyde polymer as a crystal core, polyacrylamide as a wrapping layer, and tetrafluoroethylene resin as a skeleton; the polyacrylamide can form a swelling layer in water, so that the molecular gap of the inducer becomes larger, which is conducive to the adsorption of calcium fluoride; the tetrafluoroethylene polymer wraps the swelling layer and the core material in the fluorine-containing wastewater to maintain the structural stability of the inducer; the calcium fluoride composite inducer is added into the first-stage defluorination reaction tank of the two-stage defluorination system; the composite resin in the calcium fluoride composite inducer quickly adsorbs the calcium fluoride formed by the reaction of fluoride ions in the wastewater with calcium ions of the calcium source; and then the composite inducer combined with the calcium fluoride sludge is separated by a first-stage hydraulic diverter. The invention can effectively separate the sludge from other impurities, and then separate the calcium fluoride sludge and the composite inducer through a secondary hydraulic diverter. The invention has good induction performance for calcium fluoride in the sludge through the calcium fluoride composite inducer, and can obtain high-purity calcium fluoride with high utilization value after induction. The invention adopts the calcium fluoride composite inducer to guide calcium fluoride, which can reduce the complicated induction process flow and greatly reduce the treatment cost. The calcium fluoride composite inducer of the invention has the regeneration ability and can be repeatedly used, saving the induction cost. The calcium fluoride composite inducer is used to induce the calcium fluoride process, which reduces the sludge output after fluoride removal and reduces the sludge disposal cost. The treatment conditions of the calcium fluoride composite inducer of the invention are mild and do not contain safety hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the calcium fluoride induced purification system of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0030] Embodiment: A calcium fluoride composite inducer comprises the following components in parts by weight:

[0031] 50-100 parts of styrene, 100-150 parts of oxymethylene polymer, 0.1-0.5 parts of polyacrylamide, 2-4 parts of tetrafluoroethylene resin and 300-400 parts of water.

[0032] After the above components are mixed, a granular product is formed through a granulation process, and the particle size of the granular calcium fluoride composite inducer is 100-150um.

[0033] The calcium fluoride composite inducer has a porous structure, a molecular gap of 20-30um, and a porosity of 50%.

[0034] During induction, styrene-formaldehyde polymer is used as the crystal core, polyacrylamide is used as the wrapping layer, and tetrafluoroethylene resin is used as the skeleton. Polyacrylamide can form a swelling layer in water, which makes the molecular gap of the inducer larger and is conducive to the adsorption of calcium fluoride; tetrafluoroethylene polymer wraps the swelling layer and the core material in fluoride-containing wastewater to maintain the structural stability of the inducer.

[0035] The waste acid and waste alkali water generated in the production process of a photovoltaic enterprise are discharged into the primary defluorination reaction tank for mixing. The pH of the mixed wastewater is 3, the fluorine content is between 900-1000ppm, the silicon content is between 100-200ppm, and the hydraulic retention time is 1h;

[0036] The above-mentioned fluorine-containing wastewater is treated with the aforementioned calcium fluoride composite inducer and two-stage defluorination process. The calcium fluoride induction purification method has the following specific steps:

[0037] (1) First, add a certain amount of lime milk to the primary defluorination reaction tank to control the reaction pH to 6.5-7.5; then add calcium chloride to keep the calcium-fluorine molar ratio between 0.65-0.75 for reaction;

[0038] (2) After step (1) starts running, the fluoride ions in the mixed wastewater combine with the calcium ions in the lime milk to generate calcium fluoride; at the same time, a calcium fluoride composite inducer is added to the primary defluorination reaction tank, and the stirring speed of the stirrer is controlled to be 50-100 r / min, so that the calcium fluoride composite inducer is fully in contact with the calcium fluoride generated in the water body;

[0039] (3) After the operation of step (2), the calcium fluoride composite inducer combined with the calcium fluoride sludge is discharged into the primary hydraulic diverter together with the water body. The rotation speed of the primary hydraulic diverter is maintained at 300r / min. As the primary hydraulic diverter operates, the calcium fluoride composite inducer combined with the calcium fluoride sludge with a larger particle size is separated from the water body and falls to the bottom of the primary hydraulic diverter for collection; other impurity sludge and wastewater overflow from the diversion weir and enter the primary defluorination flocculation tank. APAM is added to the primary defluorination flocculation tank. The other impurity sludge in the water body sinks to the bottom of the primary defluorination sedimentation tank. The clarified supernatant flows out from the outlet of the primary defluorination sedimentation tank and enters the secondary defluorination system;

[0040] (4) The calcium fluoride composite inducer combined with calcium fluoride sludge collected in step (3) is discharged into a secondary hydraulic diverter, the speed of the secondary hydraulic diverter is maintained at 2000r / min, and the separation time is set to 5min, so that the calcium fluoride and the calcium fluoride composite inducer are separated, and the regeneration function of the calcium fluoride composite inducer is realized;

[0041] (5) The calcium fluoride sludge-water mixture separated in step (4) enters a flocculation sedimentation tank, and APAM is added to the flocculation sedimentation tank for flocculation and sedimentation. The sludge precipitated to the bottom is then pumped to a filter press for filtration to form a calcium fluoride filter cake. At this time, the purity of calcium fluoride reaches 93.2%;

[0042] (6) The composite inducer separated in step (4) enters the inducer collection pool and is pumped to the primary defluorination reaction pool for repeated use.

[0043] The calcium fluoride induced purification system used in the above calcium fluoride induced purification method comprises a primary defluorination system, a secondary defluorination system 10 and a calcium fluoride induced separation system, wherein:

[0044] The primary defluorination system includes a primary defluorination reaction tank 1, a primary hydraulic separator 2, a primary defluorination flocculation tank 3 and a primary defluorination sedimentation tank 4;

[0045] The calcium fluoride induced separation system includes a calcium fluoride collection tank 5, a secondary hydraulic separator 6, a flocculation sedimentation tank 7, an inducer collection tank 8 and a filter press 9;

[0046] The primary defluorination reaction tank 1 is provided with a wastewater inlet pipe, a calcium source dosing device and a calcium fluoride composite inducer dosing device. Fluoride-containing wastewater can enter the primary defluorination reaction tank 1 through the wastewater inlet pipe. The calcium source dosing device and the calcium fluoride composite inducer dosing device can respectively add a calcium source and a calcium fluoride composite inducer to the primary defluorination reaction tank 1 in a quantitative manner. The water outlet of the primary defluorination reaction tank 1 is connected with the water inlet of the primary hydraulic separator. The primary hydraulic separator 2 can separate the calcium fluoride sludge from other impurity sludges. The bottom separation port of the primary hydraulic separator 2 is connected with the mud inlet of the calcium fluoride collection tank 5. The primary hydraulic separator 2 The separated and treated calcium fluoride sludge is discharged into the calcium fluoride collection tank 5, the upper separation port of the primary hydraulic separator 2 is connected with the water inlet of the primary defluorination flocculation tank 3, the primary hydraulic separator 2 discharges the wastewater after the primary defluorination reaction together with other impurity sludge into the primary defluorination flocculation tank 3, the primary defluorination flocculation tank 3 is provided with a flocculant dosing device, the flocculant dosing device can quantitatively add APAM to the primary defluorination flocculation tank 3 for polymerization reaction, the water outlet of the primary defluorination flocculation tank 3 is connected with the water inlet of the primary defluorination sedimentation tank 4, the primary defluorination sedimentation tank 4 can collect the other impurity sludge after the polymerization reaction The water outlet of the primary defluorination sedimentation tank 4 is connected with the water inlet of the secondary defluorination system 10. The secondary defluorination system 10 can remove the remaining fluorine ions in the wastewater after the primary defluorination reaction by defluorination reaction again. The calcium fluoride collection tank 5 is connected with the inlet of the secondary hydraulic separator 6 through a pipeline. The calcium fluoride composite inducer adsorbed with calcium fluoride sludge collected in the calcium fluoride collection tank 5 can be pumped into the secondary hydraulic separator 6. The secondary hydraulic separator 6 can separate the calcium fluoride sludge from the calcium fluoride composite inducer. The bottom separation port of the secondary hydraulic separator 6 is connected with the inducer collection tank 8. The secondary hydraulic separator The bottom separation port of the device 6 sends the separated calcium fluoride composite inducer to the inducer collection tank 8 for collection. The inducer collection tank 8 is connected with the calcium fluoride composite inducer dosing device through a pipeline to supply the calcium fluoride composite inducer. The upper separation port of the secondary hydraulic separator 6 is connected with the inlet of the flocculation sedimentation tank 7. The flocculation sedimentation tank 7 is also provided with a flocculant dosing device. The flocculant dosing device can quantitatively add APAM into the flocculation sedimentation tank 7 for flocculation reaction precipitation. The sedimentation discharge port of the flocculation sedimentation tank 7 is connected with the mud inlet of the filter press 9. The filter press 9 can filter and dehydrate the water-containing calcium fluoride sludge.

Claims

1. A calcium fluoride composite inducing agent, characterized in that: The composition comprises the following components in parts by weight: 50-100 parts of styrene, 100-150 parts of oxymethylene polymer, 0.1-0.5 parts of polyacrylamide, 2-4 parts of tetrafluoroethylene resin and 300-400 parts of water.

2. The calcium fluoride composite inducing agent according to claim 1, characterized in that: The particle size of the calcium fluoride composite inducer is 100-150um, the calcium fluoride composite inducer is a porous structure, the molecular gap is 20-30um, and the porosity is 50%.

3. A method for induced purification of calcium fluoride using the calcium fluoride composite inducer according to claims 1-3, characterized in that: The following steps are involved: Step 1: treating the fluorine-containing wastewater with a two-stage defluorination process. In the two-stage defluorination process, a calcium fluoride composite inducer is added to the fluorine-containing wastewater undergoing a defluorination reaction, and the calcium fluoride composite inducer adsorbs the calcium fluoride sludge generated by the defluorination reaction of the fluorine-containing wastewater; Step 2: After the defluorination reaction is completed, the calcium fluoride composite inducer adsorbed with calcium fluoride sludge and other impurity sludge are sent to the primary hydraulic diverter for sludge separation. The calcium fluoride composite inducer adsorbed with calcium fluoride sludge is heavier than other impurity sludge, and then flows out from the bottom of the primary hydraulic diverter and enters the calcium fluoride collection tank. Other impurity sludge flows out from the upper part of the primary hydraulic diverter along with the water flow and enters the primary defluorination flocculation tank; Step 3: adding APAM to the first flocculation tank for polymerization reaction, and removing other impurity sludge by precipitation; at the same time, the separated calcium fluoride composite inducer adsorbed with calcium fluoride sludge enters the secondary hydraulic separator for separation of the calcium fluoride composite inducer and the calcium fluoride sludge; Step 4: The separated calcium fluoride composite inducer is reused; the separated calcium fluoride sludge enters a flocculation sedimentation tank, and APAM is added to the flocculation sedimentation tank for flocculation reaction, and the calcium fluoride sludge is collected by sedimentation and dehydrated to form usable high-purity calcium fluoride sludge.

4. The calcium fluoride induction purification method according to claim 3, characterized in that: The staged defluorination process uses at least one of lime and calcium chloride as a calcium source.

5. The calcium fluoride induction purification method according to claim 4, characterized in that: The two-stage defluorination process includes a primary defluorination system and a secondary defluorination system. The primary defluorination system includes a primary defluorination reaction tank for supplying a calcium source and performing defluorination reaction with fluorine-containing wastewater. The calcium fluoride composite inducer is added into the primary defluorination reaction tank.

6. The calcium fluoride induction purification method according to claim 4, characterized in that: The amount of lime added to the primary defluorination reaction tank is controlled by pH to maintain the pH in the primary defluorination reaction tank at 6.5-7.

5.

7. The calcium fluoride induction purification method according to claim 3, characterized in that: The rotation speed of the first-stage hydraulic separator is 200-500 r / min, the rotation speed of the second-stage hydraulic separator is 2000-2500 r / min, and the separation time is 1-5 min.

8. The calcium fluoride induction purification method according to claim 3, characterized in that: In the step 1, while the fluorine-containing wastewater is undergoing a defluorination reaction, the fluorine-containing wastewater is stirred. Under the hydraulic action generated by the stirring, calcium fluoride and other impurity sludge are in a fully separated state, and the calcium fluoride composite inducer fully adsorbs the calcium fluoride in the sludge.

9. The calcium fluoride induction purification method according to claim 3, characterized in that: In the step 4, the calcium fluoride sludge collected by precipitation is pumped into a filter press, and is dehydrated by filter pressing to form usable high-purity calcium fluoride sludge.

10. A calcium fluoride induction purification system used in the calcium fluoride induction purification method according to claim 3, characterized in that: It comprises a primary defluorination system, a secondary defluorination system (10) and a calcium fluoride induced separation system, wherein: The primary defluorination system comprises a primary defluorination reaction tank (1), a primary hydraulic separator (2), a primary defluorination flocculation tank (3) and a primary defluorination sedimentation tank (4); The calcium fluoride induced separation system comprises a calcium fluoride collection tank (5), a secondary hydraulic separator (6), a flocculation sedimentation tank (7), an inducer collection tank (8) and a filter press (9); The primary defluorination reaction tank is provided with a wastewater inlet pipe, a calcium source dosing device and a calcium fluoride composite inducer dosing device, fluorine-containing wastewater can enter the primary defluorination reaction tank through the wastewater inlet pipe, the calcium source dosing device and the calcium fluoride composite inducer dosing device can respectively add a calcium source and a calcium fluoride composite inducer to the primary defluorination reaction tank in a quantitative manner, the water outlet of the primary defluorination reaction tank is connected with the water inlet of the primary hydraulic separator, the primary hydraulic separator can separate the calcium fluoride sludge from other impurity sludges, the bottom separation port of the primary hydraulic separator is connected with the mud inlet of the calcium fluoride collection tank, and the primary hydraulic separator The first-stage hydraulic separator discharges the separated calcium fluoride sludge into the calcium fluoride collection tank. The separation port above the first-stage hydraulic separator is connected to the water inlet of the first-stage defluorination flocculation tank. The first-stage hydraulic separator discharges the wastewater after the first-stage defluorination reaction together with other impurity sludge into the first-stage defluorination flocculation tank. The first-stage defluorination flocculation tank is provided with a flocculant dosing device. The flocculant dosing device can quantitatively add APAM to the first-stage defluorination flocculation tank for polymerization reaction. The outlet of the first-stage defluorination flocculation tank is connected to the water inlet of the first-stage defluorination sedimentation tank. The first-stage defluorination sedimentation tank can sediment other impurity sludge after the polymerization reaction. The water outlet of the primary defluorination sedimentation tank is connected with the water inlet of the secondary defluorination system. The secondary defluorination system can perform a defluorination reaction on the wastewater after the primary defluorination reaction to remove the remaining fluoride ions in the wastewater. The calcium fluoride collection tank is connected with the inlet of the secondary hydraulic separator through a pipeline. The calcium fluoride composite inducer adsorbed with calcium fluoride sludge collected in the calcium fluoride collection tank can be pumped into the secondary hydraulic separator. The secondary hydraulic separator can separate the calcium fluoride sludge from the calcium fluoride composite inducer. The bottom separation port of the secondary hydraulic separator is connected with the inducer collection tank. The secondary hydraulic separator The bottom separation port of the device sends the separated calcium fluoride composite inducer into the inducer collection tank for collection. The inducer collection tank is connected with the calcium fluoride composite inducer dosing device through a pipeline to supply the calcium fluoride composite inducer. The upper separation port of the secondary hydraulic separator is connected with the inlet of the flocculation sedimentation tank. The flocculation sedimentation tank is also provided with a flocculant dosing device. The flocculant dosing device can quantitatively add APAM into the flocculation sedimentation tank for flocculation reaction precipitation. The sedimentation discharge port of the flocculation sedimentation tank is connected with the mud inlet of the filter press. The filter press can filter and dehydrate the water-containing calcium fluoride sludge.

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