Photovoltaic acid wastewater treatment method and system for recycling high-purity calcium fluoride

Abstract

The invention discloses a photovoltaic acidic wastewater treatment method and system for recycling high-purity calcium fluoride, which comprises the following steps: separately collecting dilute acid wastewater and concentrated acid wastewater in a dilute acid wastewater collecting pool and a concentrated acid wastewater collecting pool respectively, and preparing a lime solution with the mass percent concentration of 5-10% in a lime solution pool, the method comprises the following steps: conveying a lime solution into a multi-stage solid particle separator to separate out a light lime solution and a heavy lime solution, carrying out a defluorination precipitation reaction on the light lime solution and dilute acid wastewater in a dilute acid wastewater defluorination reaction tank, and carrying out a defluorination precipitation reaction on the heavy lime solution and concentrated acid wastewater in a concentrated acid wastewater defluorination reaction tank, according to the method, the utilization rate of the lime is greatly increased, meanwhile, the phenomenon that lime particles are wrapped by calcium fluoride due to insufficient reaction power can be effectively prevented, and therefore the purity of the calcium fluoride product is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a photovoltaic acidic wastewater treatment method and system for recovering high-purity calcium fluoride. Background Art

[0002] Photovoltaic cell production processes such as pickling, etching, and cleaning generate large amounts of acidic, fluorinated wastewater. Typically, this type of wastewater is treated by collecting the various acidic, fluorinated wastewaters and combining them with other alkaline wastewaters in a comprehensive regulating tank for comprehensive treatment. Because the wastewater from the regulating tank is generally acidic, lime emulsion is typically added to neutralize and remove fluorine. This involves adding lime solution to the wastewater, causing the added calcium and fluoride in the water to form calcium fluoride precipitates. While this method can reduce the amount of alkali used, it also has significant drawbacks: silicon from the alkaline water is introduced into the sludge during the defluorination precipitation process. Furthermore, the acidity of the fluorinated wastewater decreases after the alkaline water is added, resulting in low lime utilization efficiency during the reaction with lime. This significantly reduces the purity of the calcium fluoride sludge (only 50%-70%) and its resource value.

[0003] The lime production process generally includes multiple steps, including raw material preparation, calcination, and digestion. Selected limestone is crushed and screened before being sent to a calciner for high-temperature calcination, breaking it down into calcium oxide and carbon dioxide. The calcined quicklime is then mixed with water and digested in a digester to produce calcium hydroxide (slaked lime). Production is then completed through grinding, screening, and packaging. Due to issues with raw materials and production process control, the lime product may contain impurities (primarily calcium carbonate) and large lime particles.

[0004] For lime defluoridation and calcium fluoride recovery, due to the limited acidity of the wastewater, the large lime particles mentioned above do not have time to dissolve and disperse during the reaction process and are wrapped by the calcium fluoride generated on the surface of the particles and carried into the precipitate. In addition, the calcium carbonate particles in the lime are also easily entrained in the precipitate during the reaction, thereby reducing the purity and quality of the calcium fluoride precipitate. Summary of the Invention

[0005] In order to overcome the above-mentioned defects, the present invention provides a photovoltaic acidic wastewater treatment method and system for recovering high-purity calcium fluoride. The photovoltaic acidic wastewater treatment method and system for recovering high-purity calcium fluoride can greatly improve the utilization rate of lime and ensure that the purity of the calcium fluoride product is above 90%.

[0006] The present invention adopts a technical solution to solve the technical problem: a method for treating photovoltaic acidic wastewater for recovering high-purity calcium fluoride, comprising the following steps:

[0007] Step 1: Collect dilute acid wastewater and concentrated acid wastewater separately;

[0008] Step 2: Prepare a lime solution with a mass percentage concentration of 5%-10%;

[0009] Step 3: transporting the lime solution into a multi-stage solid particle separator for separation to obtain a light lime solution with a particle size of 240-600 mesh and a heavy lime solution with a particle size below 240 mesh containing large lime particles and calcium carbonate particles as impurities;

[0010] Step 4: Using the obtained light lime solution in a defluorination precipitation reaction of dilute acid wastewater, and using the obtained heavy lime solution in a defluorination precipitation reaction of concentrated acid wastewater, to finally obtain calcium fluoride precipitate with a purity of more than 90%.

[0011] The lime solution is separated into light lime and heavy lime by utilizing the difference in particle density and particle size in a multi-stage solid particle separator. The obtained light lime solution is used for defluorination precipitation reaction treatment of dilute acid wastewater, and the obtained heavy lime solution is used for defluorination precipitation reaction treatment of concentrated acid wastewater. The acidity of dilute acid wastewater is relatively low, and the kinetic energy during acid-base reaction is relatively small. The lime particles in the light lime solution are relatively small, and the contact area when contacting the dilute acid wastewater is large, resulting in better mass transfer and more complete reaction. The acidity of concentrated acid wastewater is high, and the kinetic energy during acid-base reaction is strong. It has a strong dissolving ability for large particles of lime or calcium carbonate impurities, and can also prevent the formation of calcium fluoride wrapping around lime particles due to insufficient reaction kinetics. The above defluorination method effectively improves the utilization rate of lime, thereby ensuring the purity of calcium fluoride.

[0012] As a further improvement of the present invention, the light lime solution and the dilute acid wastewater are subjected to a defluorination reaction in a dilute acid wastewater defluorination reaction tank according to a set flow ratio, and the heavy lime solution and the concentrated acid wastewater are subjected to a defluorination reaction in a concentrated acid wastewater defluorination reaction tank according to a set flow ratio. The mixture formed after the reactions in the dilute acid wastewater defluorination reaction tank and the concentrated acid wastewater defluorination reaction tank are completed is pumped into the same sedimentation tank for sedimentation treatment, and a calcium fluoride precipitate with a purity of more than 90% is discharged from the bottom of the sedimentation tank.

[0013] As a further improvement of the present invention, after the lime solution is prepared in the lime solution tank, it is pumped into the multi-stage solid particle separator at a set flow rate. The lime solution pump transports the prepared lime solution in the lime solution tank to the inlet of the multi-stage solid particle separator and enters the multi-stage solid particle separator at a predetermined flow rate. Light lime and heavy lime are separated by utilizing the differences in particle density and particle size. The flow rate of the lime solution entering the multi-stage solid particle separator is adjusted based on the type of solid particle separator and the particle size of the lime solution.

[0014] A photovoltaic acidic wastewater treatment system for recovering high-purity calcium fluoride comprises a dilute acid wastewater collection tank, a concentrated acid wastewater collection tank, a lime solution tank, a multi-stage solid particle separator, a dilute acid wastewater defluoridation reaction tank, a concentrated acid wastewater defluoridation reaction tank, a sedimentation tank, a lime solution lifting pump, a dilute acid wastewater lifting pump, a concentrated acid wastewater lifting pump, a light lime dosing pump, a heavy lime dosing pump, a first drainage pump and a second drainage pump. The dilute acid wastewater collection tank and the concentrated acid wastewater collection tank are respectively used to collect dilute acid wastewater and concentrated acid wastewater, and the dilute acid wastewater collection tank is connected to the dilute acid wastewater defluoridation reaction tank through a pipeline, and the concentrated acid wastewater collection tank is connected to the concentrated acid wastewater defluoridation reaction tank through a pipeline. The dilute acid wastewater lifting pump and the concentrated acid wastewater lifting pump can respectively pump the dilute acid wastewater and the concentrated acid wastewater into the dilute acid wastewater defluoridation reaction tank and the concentrated acid wastewater defluoridation reaction tank. The solution tank is used to prepare lime solution. The lime solution tank is connected to the inlet of the multi-stage solid particle separator through a pipeline. The lime solution lifting pump can pump the prepared lime solution in the lime solution tank into the multi-stage solid particle separator at a set flow rate. The multi-stage solid particle separator can separate small particles of lime from large particles of lime and calcium carbonate particles in the lime solution to form light lime solution and heavy lime solution. The light lime dosing pump and the heavy lime dosing pump can respectively pump the light lime solution and the heavy lime solution into the dilute acid wastewater defluoridation reaction tank and the concentrated acid wastewater defluoridation reaction tank in a quantitative manner. The first drainage pump and the second drainage pump can respectively pump the fully reacted mixed liquid in the dilute acid wastewater defluoridation reaction tank and the concentrated acid wastewater defluoridation reaction tank into the sedimentation tank. A water outlet is provided at the upper end of the sedimentation tank, and a calcium fluoride sludge discharge outlet is provided at the bottom of the sedimentation tank.

[0015] The dilute acid wastewater collection pool and the concentrated acid wastewater collection pool are used to collect dilute acid wastewater and concentrated acid wastewater respectively, and the collected dilute acid wastewater and concentrated acid wastewater are pumped into the dilute acid wastewater defluorination reaction pool and the concentrated acid wastewater defluorination reaction pool at a certain flow rate through the dilute acid wastewater lifting pump and the concentrated acid wastewater lifting pump at a certain flow rate for defluorination reaction. Lime and water are mixed in the lime solution pool according to the set ratio. The prepared lime solution is pumped into the multi-stage solid particle separator at a certain flow rate by the lime solution lifting pump for separation. The separated light Lime floats and heavy lime sinks. The light lime dosing pump and the heavy lime dosing pump quantitatively pump the separated light lime solution and heavy lime solution into the dilute acid wastewater defluoridation reaction tank and the concentrated acid wastewater defluoridation reaction tank respectively. The dilute acid wastewater reacts with the light lime to form calcium fluoride, and the concentrated acid wastewater reacts with the heavy lime to form calcium fluoride. Finally, the calcium fluoride is precipitated in the sedimentation tank to form high-purity calcium fluoride sludge. The high-purity calcium fluoride sludge can be further cleaned and dehydrated to obtain high-purity calcium fluoride product.

[0016] As a further improvement of the present invention, the multi-stage solid particle separator has a two-stage or three-stage solid particle separation structure. The multiple separations of the lime solution ensure that the separated light lime contains no heavy lime particles, thus preventing calcium fluoride from encapsulating lime particles due to insufficient reaction kinetics in the dilute acid wastewater defluoridation reaction tank, thereby improving the purity of the calcium fluoride product.

[0017] As a further improvement of the present invention, the multi-stage solid particle separator includes a primary solid particle separator, a secondary solid particle separator, a primary purification collection tank and an intermediate pump. The inlet of the primary solid particle separator is connected to the lime solution tank through a pipeline. The primary solid particle separator can separate the lime solution entering it according to particle size. The light lime solution outlet at the upper end of the primary solid particle separator is connected to the primary purification collection tank through a pipeline. The heavy lime solution outlet at the lower end of the primary solid particle separator can discharge the heavy lime solution. The primary purification collection tank is provided with a stirrer, which can stir and homogenize the mixed liquid in the primary purification collection tank. The primary purification collection tank is connected to the inlet of the secondary solid particle separator through a pipeline. The intermediate pump can pump the mixed liquid in the primary purification collection tank into the secondary solid particle separator at a set flow rate. The secondary solid particle separator can further separate the mixed liquid entering it according to particle size. The light lime solution outlet at the upper end of the secondary solid particle separator can discharge the light lime solution, and the heavy lime solution outlet at the lower end of the secondary solid particle separator can discharge the heavy lime solution.

[0018] After the lime solution is separated by the first-stage solid particle separator, a small amount of heavy lime particles will be mixed in the separated light lime solution. After it is collected and stirred and homogenized in the first-stage purification collection pool, it is sent to the second-stage solid particle separator at a certain flow rate for secondary separation to separate the mixed heavy lime particles. After two separations, it is helpful to ensure that the heavy lime particles in the light lime solution are fully removed. If the light lime solution still contains a large amount of heavy lime particles after two-stage separation, a third-stage solid particle separator can be added. In this way, after multi-stage separation, the light lime and heavy lime in the lime solution can be fully separated.

[0019] As a further improvement of the present invention, a heavy lime solution collection tank is further provided. The heavy lime solution outlets at the lower ends of the primary solid particle separator and the secondary solid particle separator are both connected to the heavy lime solution collection tank, into which the heavy lime solution is discharged. The heavy lime solution collection tank is connected to the concentrated acid wastewater defluorination reaction tank via a pipeline to supply heavy lime solution. The heavy lime solution separated by each solid particle separator is uniformly collected in the heavy lime solution collection tank and used uniformly for the concentrated acid wastewater defluorination reaction.

[0020] As a further improvement of the present invention, the heavy lime solution collection tank is further provided with an agitator capable of stirring the mixed solution in the heavy lime solution collection tank, forming a pointed-bottom sedimentation tank structure at the bottom of the heavy lime solution collection tank, so that large lime particles in the heavy lime solution can precipitate and accumulate at the bottom of the heavy lime solution collection tank. A heavy lime dosing pump can pump the large lime particles accumulated at the bottom of the heavy lime solution collection tank into the concentrated acid wastewater defluoridation reaction tank. The separated heavy lime solution is stirred by the agitator in the heavy lime solution collection tank to achieve homogenization of the heavy lime solution. At the same time, a small amount of light lime particles that are doped will float up, while the heavy lime particles will sink to the bottom of the heavy lime solution collection tank.

[0021] As a further improvement to the present invention, a secondary purification collection tank is further provided. The light lime solution outlet at the upper end of the secondary solid particle separator is connected to the secondary purification collection tank via a pipeline. A stirrer is also provided within the secondary purification collection tank to homogenize the mixed solution within the secondary purification collection tank. A light lime dosing pump is configured to pump the homogenized light lime solution within the secondary purification collection tank into the dilute acid wastewater defluoridation reaction tank. The light lime solution separated by the secondary solid particle separator is collected within the secondary purification collection tank, stirred homogenously by the stirrer, and ultimately fed to the dilute acid wastewater defluoridation reaction tank at a stable light lime concentration for reaction.

[0022] As a further improvement of the present invention, the primary solid particle separator and the secondary solid particle separator are one of a high-density sedimentation tank, a bell-type grit chamber and a hydrocyclone.

[0023] The beneficial effects of the present invention are as follows: the present invention abandons the conventional mode of mixed treatment of acidic fluorine-containing wastewater and alkaline wastewater, and treats the acidic fluorine-containing wastewater separately, thereby avoiding the influence of silicon in the alkaline water on the purity of the calcium fluoride product. At the same time, the present invention further performs quality separation treatment on the dilute acid wastewater and the concentrated acid wastewater, realizes the classification of lime particles through a multi-stage solid particle separator, reacts light lime with the dilute acid wastewater to remove fluorine, and reacts heavy lime and calcium carbonate impurities with the concentrated acid wastewater to remove fluorine, thereby achieving full reaction of lime, greatly improving the utilization rate of lime, and effectively preventing the formation of calcium fluoride covering lime particles due to insufficient reaction power, thereby ensuring that the purity of the calcium fluoride product can reach more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of a photovoltaic acidic wastewater treatment system for recovering high-purity calcium fluoride according to the present invention;

[0025] Figure 2This is a system principle diagram of the present invention in which lime solution passes through a multi-stage solid particle separator for particle separation.

[0026] Figure numerals: dilute acid wastewater collection tank---1; concentrated acid wastewater collection tank---2; lime solution tank---3; multi-stage solid particle separator---4; dilute acid wastewater defluoridation reaction tank---5; concentrated acid wastewater defluoridation reaction tank---6; sedimentation tank---7; lime solution lifting pump---8; light lime dosing pump---9; heavy lime dosing pump---10; primary solid particle separator---11; secondary solid particle separator---12; primary purification collection tank---13; intermediate pump---14; agitator---15; heavy lime solution collection tank---16; secondary purification collection tank---17. DETAILED DESCRIPTION

[0027] The following describes specific embodiments of the present invention in detail. It should be noted that the embodiments described here are only some embodiments of the present invention, not all embodiments. Based on the following embodiments, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Example: A photovoltaic enterprise in Sichuan produces 200-300m3 of wastewater every day during its production process. 3 Concentrated acid wastewater (fluorine concentration is 12000 ~ 25000 mg / L) and 4300 ~ 5000m 3 The dilute acid wastewater (fluoride concentration is 165-403 mg / L) is collected separately in the concentrated acid wastewater collection pool 2 and the dilute acid wastewater collection pool 1.

[0029] The lime method is used to remove fluoride and recover fluoride from the above wastewater.

[0030] The lime solution is prepared by mixing slaked lime in the lime silo with tap water. The concentration of the lime solution is controlled at 6.2% to 8.5%, and the lime solution is stored in the lime solution tank 3.

[0031] The prepared lime solution is classified by using a multi-stage solid particle separator. The multi-stage solid particle separator selects a two-stage cyclone separator. First, the lime solution is pumped into the first cyclone separator by a lime solution lift pump 8. The first-stage feed pressure is controlled in the range of 0.15-0.2 MPa. Light lime solution (200-600 mesh) is obtained at the top outlet of the first cyclone separator and stored in the first purification collection tank 13, while heavy lime solution (less than 200 mesh) containing large lime particles and calcium carbonate particles enters the heavy lime solution collection tank 16. The light lime solution in the first purification collection tank 13 is sent to the second cyclone separator by an intermediate pump 14. The second-stage feed pressure is controlled in the range of 0.2-0.3 MPa. Light lime solution (240-600 mesh) is obtained at the top outlet of the second cyclone separator and stored in the second purification collection tank 17. Heavy lime solution (200-240 mesh) containing a small amount of large lime particles separated by the second cyclone separator enters the heavy lime solution collection tank 16.

[0032] The obtained light lime solution is used in the defluorination precipitation reaction of dilute acid wastewater, and the reaction pH is controlled at 6.0-7.0; the obtained heavy lime solution is used in the defluorination precipitation reaction of concentrated acid wastewater, and the reaction pH is controlled at 5.0-5.5.

[0033] After the reaction is completed, the purity of the calcium fluoride precipitated from the dilute acid wastewater defluoridation is measured to be 92.3% to 95.4%, and the purity of the calcium fluoride precipitated from the concentrated acid wastewater defluoridation is measured to be 90.3% to 92.7%.

Claims

1. A method for treating photovoltaic acidic wastewater for recovering high-purity calcium fluoride, characterized by: The following steps are involved: Step 1: Collect dilute acid wastewater and concentrated acid wastewater separately; Step 2: Prepare a lime solution with a mass percentage concentration of 5%-10%; Step 3: transporting the lime solution into a multi-stage solid particle separator for separation to obtain a light lime solution with a particle size of 240-600 mesh and a heavy lime solution with a particle size below 240 mesh containing large lime particles and calcium carbonate particles as impurities; Step 4: Using the obtained light lime solution in a defluorination precipitation reaction of dilute acid wastewater, and using the obtained heavy lime solution in a defluorination precipitation reaction of concentrated acid wastewater, to finally obtain calcium fluoride precipitate with a purity of more than 90%.

2. The photovoltaic acidic wastewater treatment method for recovering high-purity calcium fluoride according to claim 1, characterized in that: The light lime solution and the dilute acid wastewater are subjected to a defluorination reaction in a dilute acid wastewater defluorination reaction tank according to a set flow ratio, and the heavy lime solution and the concentrated acid wastewater are subjected to a defluorination reaction in a concentrated acid wastewater defluorination reaction tank according to a set flow ratio. After the reactions in the dilute acid wastewater defluorination reaction tank and the concentrated acid wastewater defluorination reaction tank are completed, the mixture formed is pumped into the same sedimentation tank for sedimentation treatment, and calcium fluoride precipitate with a purity of more than 90% is discharged from the bottom of the sedimentation tank.

3. The photovoltaic acidic wastewater treatment method for recovering high-purity calcium fluoride according to claim 1, characterized in that: After the lime solution is prepared in the lime solution pool, it is pumped into the multi-stage solid particle separator at a set flow rate.

4. A photovoltaic acidic wastewater treatment system for recovering high-purity calcium fluoride used in the photovoltaic acidic wastewater treatment method for recovering high-purity calcium fluoride according to any one of claims 1 to 3, characterized in that: It includes a dilute acid wastewater collection tank, a concentrated acid wastewater collection tank, a lime solution tank, a multi-stage solid particle separator, a dilute acid wastewater defluoridation reaction tank, a concentrated acid wastewater defluoridation reaction tank, a sedimentation tank, a lime solution lifting pump, a dilute acid wastewater lifting pump, a concentrated acid wastewater lifting pump, a light lime dosing pump, a heavy lime dosing pump, a first drainage pump and a second drainage pump. The dilute acid wastewater collection tank and the concentrated acid wastewater collection tank are respectively used to collect dilute acid wastewater and concentrated acid wastewater, and the dilute acid wastewater collection tank is connected to the dilute acid wastewater defluoridation reaction tank through a pipeline, and the concentrated acid wastewater collection tank is connected to the concentrated acid wastewater defluoridation reaction tank through a pipeline. The dilute acid wastewater lifting pump and the concentrated acid wastewater lifting pump can respectively pump the dilute acid wastewater and the concentrated acid wastewater into the dilute acid wastewater defluoridation reaction tank and the concentrated acid wastewater defluoridation reaction tank. The lime solution tank is used to prepare lime solution. The lime solution pool is connected to the inlet of the multi-stage solid particle separator through a pipeline. The lime solution lifting pump can pump the prepared lime solution in the lime solution pool into the multi-stage solid particle separator at a set flow rate. The multi-stage solid particle separator can separate the small particles of lime from the large particles of lime and the calcium carbonate particles in the lime solution to form light lime solution and heavy lime solution. The light lime dosing pump and the heavy lime dosing pump can respectively pump the light lime solution and the heavy lime solution into the dilute acid wastewater defluoridation reaction tank and the concentrated acid wastewater defluoridation reaction tank in a quantitative manner. The first drainage pump and the second drainage pump can respectively pump the fully reacted mixed liquid in the dilute acid wastewater defluoridation reaction tank and the concentrated acid wastewater defluoridation reaction tank into the sedimentation tank. A water outlet is provided at the upper end of the sedimentation tank, and a calcium fluoride sludge discharge outlet is provided at the bottom of the sedimentation tank.

5. The photovoltaic acidic wastewater treatment method for recovering high-purity calcium fluoride according to claim 4, characterized in that: The multi-stage solid particle separator is a two-stage or three-stage solid particle separation structure.

6. The photovoltaic acidic wastewater treatment system for recovering high-purity calcium fluoride according to claim 4, characterized in that: The multi-stage solid particle separator includes a primary solid particle separator, a secondary solid particle separator, a primary purification collection tank and an intermediate pump. The inlet of the primary solid particle separator is connected to the lime solution tank through a pipeline. The primary solid particle separator can separate the lime solution entering it according to particle size. The light lime solution outlet at the upper end of the primary solid particle separator is connected to the primary purification collection tank through a pipeline. The heavy lime solution outlet at the lower end of the primary solid particle separator can discharge the heavy lime solution. A stirrer is provided in the primary purification collection tank. The stirrer can stir and homogenize the mixed liquid in the primary purification collection tank. The primary purification collection tank is connected to the inlet of the secondary solid particle separator through a pipeline. The intermediate pump can pump the mixed liquid in the primary purification collection tank into the secondary solid particle separator at a set flow rate. The secondary solid particle separator can further separate the mixed liquid entering it according to particle size. The light lime solution outlet at the upper end of the secondary solid particle separator can discharge the light lime solution, and the heavy lime solution outlet at the lower end of the secondary solid particle separator can discharge the heavy lime solution.

7. The photovoltaic acidic wastewater treatment system for recovering high-purity calcium fluoride according to claim 6, characterized in that: A heavy lime solution collecting pool is also provided. The heavy lime solution outlet at the lower end of the first-stage solid particle separator and the heavy lime solution outlet at the lower end of the second-stage solid particle separator are both connected to the heavy lime solution collecting pool. The heavy lime solution is discharged into the heavy lime solution collecting pool. The heavy lime solution collecting pool is connected to the concentrated acid wastewater defluorination reaction pool through a pipeline to supply heavy lime solution.

8. The photovoltaic acidic wastewater treatment system for recovering high-purity calcium fluoride according to claim 7, characterized in that: The heavy lime solution collection tank is further provided with an agitator, which can stir the mixed liquid in the heavy lime solution collection tank. A pointed-bottom sedimentation tank structure is formed at the bottom of the heavy lime solution collection tank, and large lime particles in the heavy lime solution can be precipitated and accumulated at the bottom of the heavy lime solution collection tank. The heavy lime dosing pump can pump the large lime particles accumulated at the bottom of the heavy lime solution collection tank into the concentrated acid wastewater defluoridation reaction tank.

9. The photovoltaic acidic wastewater treatment system for recovering high-purity calcium fluoride according to claim 6, characterized in that: A secondary purification collection pool is also provided. The light lime solution outlet at the upper end of the secondary solid particle separator is connected to the secondary purification collection pool through a pipeline. An agitator is also provided in the secondary purification collection pool. The agitator can stir the mixed liquid in the secondary purification collection pool to make it homogeneous. The light lime dosing pump can pump the homogeneous light lime solution in the secondary purification collection pool into the dilute acid wastewater defluorination reaction pool.

10. The method for treating photovoltaic acidic wastewater for recovering high-purity calcium fluoride according to claim 6, characterized in that: The primary solid particle separator and the secondary solid particle separator are one of a high-density sedimentation tank, a bell-type grit chamber and a hydrocyclone.

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