Method and device for recovering fluorine from acid-washed quartz sand wastewater

Abstract

The application discloses a method and device for recovering fluorine from pickling quartz sand wastewater, and the method comprises the following steps: allowing the wastewater to enter a first reaction tank, and adding a first solution and a second solution into the first reaction tank to react with the wastewater, so that the pH value of the mixed solution in the first reaction tank is 8.5-9.5; allowing the mixed solution to enter a first sedimentation tank, and transferring the first sludge at the lower part of the first sedimentation tank after standing and depositing; allowing the mixed solution in the first sedimentation tank to enter a second reaction tank, and adding a second solution and a reactant into the second reaction tank to react with the mixed solution, so that the pH value of the mixed solution in the second reaction tank is 7-8; allowing the mixed solution in the second reaction tank to enter a second sedimentation tank, and recycling the second sludge and water in the second sedimentation tank after standing and depositing. The method for recovering fluorine from pickling quartz sand wastewater can effectively recycle the wastewater.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method and apparatus for recovering fluoride from acid-washed quartz sand wastewater. Background Technology

[0002] In related technologies, although natural quartz sand is mainly composed of silicon dioxide, it often contains impurities such as iron, aluminum, titanium, calcium, and other metal oxides, as well as silicate minerals (such as mica and feldspar), organic matter, and clay. These impurities can affect the performance of the final product; therefore, acid washing of the quartz sand is necessary. The quartz sand acid washing process includes feeding, acid introduction, heating, acid discharge, and washing. After acid washing of quartz sand, the wastewater contains a large amount of impurities such as fluoride ions, oxalate ions, and metal ions; therefore, it is necessary to treat and recycle the wastewater. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for recovering fluoride from acid-washed quartz sand wastewater, which enables effective recycling and reuse of the wastewater.

[0004] This invention also proposes a device for recovering fluoride from acid-washed quartz sand wastewater.

[0005] A method for recovering fluoride from acid-washed quartz sand wastewater according to a first aspect of the present invention includes the following steps: Wastewater is introduced into the first reaction tank, and a first solution and a second solution are simultaneously added to the first reaction tank to react with the wastewater, so that the pH value of the mixture in the first reaction tank is 8.5~9.5; The mixture is allowed to enter the first sedimentation tank, and after settling, the first sludge at the bottom of the first sedimentation tank is transferred. The mixture in the first sedimentation tank is introduced into the second reaction tank, and the second solution and reactants are added to the second reaction tank to react with the mixture, so that the pH value of the mixture in the second reaction tank is 7~8; The mixture in the second reaction tank is allowed to enter the second sedimentation tank. After settling, the second sludge and water in the second sedimentation tank are recycled.

[0006] The method for recovering fluoride from acid-washed quartz sand wastewater according to embodiments of the present invention has at least the following beneficial effects: After the wastewater enters the first reaction tank, a first solution and a second solution are added to react with the wastewater, which can make the pH value of the mixed solution 8.5~9.5. In this way, the acidity of the wastewater can be effectively changed. Then, the mixed solution after reaction continues to enter the first sedimentation tank. After the mixed solution settles, the first sludge at the bottom of the first sedimentation tank can be transferred. Then, the mixed solution enters the second reaction tank, and a second solution and reactants are added to the second reaction tank to react with the mixed solution, making the pH value of the mixed solution in the second reaction tank 7~8. At this time, the pH value of the mixed solution tends to be normal. Then, the mixed solution enters the second sedimentation tank. After settling, the second sludge and water in the second sedimentation tank are recycled. In this way, the second sludge and water generated after the wastewater undergoes reaction and sedimentation can be recycled. Specifically, the method for recovering fluoride from acid-washed quartz sand wastewater can effectively recycle and reuse wastewater.

[0007] According to some embodiments of the present invention, a method for recovering fluoride from acid-washed quartz sand wastewater, wherein the first solution is prepared by mixing water, diatomaceous earth, and potassium hydroxide in a ratio of 50:3:3.5.

[0008] The method for recovering fluoride from acid-washed quartz sand wastewater according to some embodiments of the present invention further includes the step of adding the water in the second sedimentation tank to the preparation of the first solution.

[0009] According to some embodiments of the present invention, a method for recovering fluoride from acid-washed quartz sand wastewater, wherein the second solution is prepared by mixing water and solid polyacrylamide in a ratio of 500:1.

[0010] The method for recovering fluoride from acid-washed quartz sand wastewater according to some embodiments of the present invention further includes the step of preparing the second solution in advance, and then allowing the wastewater to enter the first reaction tank.

[0011] According to some embodiments of the present invention, a method for recovering fluoride from acid-washed quartz sand wastewater includes calcium chloride and oxalic acid as reactants.

[0012] A fluoride recovery device for acid-washed quartz sand wastewater according to a second aspect embodiment of the present invention is used in the fluoride recovery method for acid-washed quartz sand wastewater according to any one of the first aspect embodiments, the fluoride recovery device for acid-washed quartz sand wastewater comprising: First reaction tank; The first sedimentation tank is located next to the first reaction tank, and the height of the first sedimentation tank is lower than the height of the first reaction tank. The second reaction tank is located next to the first sedimentation tank, and the height of the second reaction tank is lower than the height of the first sedimentation tank. The second sedimentation tank is located next to the second reaction tank, and the height of the second sedimentation tank is lower than the height of the second reaction tank.

[0013] The fluoride recovery device for acid-washed quartz sand wastewater according to an embodiment of the present invention has at least the following beneficial effects: After the wastewater enters the first reaction tank, a first solution and a second solution are added to react with the wastewater, which can make the pH value of the mixed liquid 8.5~9.5. This effectively changes the acidity of the wastewater. Since the height of the first sedimentation tank is lower than the height of the first reaction tank, the mixed liquid can overflow from the first reaction tank into the first sedimentation tank, and then continue to enter the first sedimentation tank after reaction. After the mixed liquid settles, the first sludge at the bottom of the first sedimentation tank can be transferred. Since the height of the second reaction tank is lower than the height of the first sedimentation tank,... Therefore, the mixed liquid can overflow from the first reaction tank into the first sedimentation tank, and a second solution and reactants are added to the second reaction tank to react with the mixed liquid, so that the pH value of the mixed liquid in the second reaction tank is 7-8. At this time, the pH value of the mixed liquid tends to be normal. Since the height of the second sedimentation tank is lower than that of the second reaction tank, the mixed liquid can overflow from the second reaction tank into the second sedimentation tank. After settling, the second sludge and water in the second sedimentation tank are recycled. In this way, the second sludge and water generated after the wastewater undergoes reaction and sedimentation can be recycled. Specifically, the acid washing quartz sand wastewater fluoride recovery device can effectively recycle and reuse wastewater.

[0014] According to some embodiments of the present invention, the fluoride recovery device for acid-washed quartz sand wastewater further includes two stirring devices, one of which is disposed in the first reaction tank and the other of which is disposed in the second reaction tank.

[0015] According to some embodiments of the present invention, the fluoride recovery device for acid-washed quartz sand wastewater further includes a filter press connected to the first sedimentation tank, and the filter press is used to treat the first sludge.

[0016] According to some embodiments of the present invention, the fluoride recovery device for acid-washed quartz sand wastewater further includes online pH meters, with two online pH meters respectively installed in the first reaction tank and the second reaction tank.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of a fluoride recovery device for acid-washed quartz sand wastewater according to some embodiments of the present invention.

[0019] Figure label: The device for recovering fluoride from acid-washed quartz sand wastewater consists of a 10-unit first reaction tank, a 100-unit first sedimentation tank, a 200-unit first reaction tank, a 300-unit second sedimentation tank, a 400-unit second sedimentation tank, and a 500-unit filter press. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0022] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0023] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0024] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0025] In related technologies, although natural quartz sand is mainly composed of silicon dioxide, it often contains impurities such as iron, aluminum, titanium, calcium, and other metal oxides, as well as silicate minerals (such as mica and feldspar), organic matter, and clay. These impurities affect the performance of the final product; therefore, acid washing of the quartz sand is necessary. The quartz sand acid washing process includes feeding, acid introduction, heating, acid discharge, and washing. After acid washing of quartz sand, the wastewater contains a significant amount of impurities such as fluoride ions, oxalate ions, and metal ions. Therefore, it is necessary to treat and recycle the wastewater. To this end, this application proposes a method for recovering fluoride from acid-washed quartz sand wastewater.

[0026] Please refer to Figure 1 In some embodiments, the method for recovering fluoride from acid-washed quartz sand wastewater includes the following steps: Wastewater is introduced into the first reaction tank 100, and a first solution and a second solution are simultaneously added to the first reaction tank 100 to react with the wastewater, so that the pH value of the mixed solution in the first reaction tank 100 is 8.5~9.5; Let the mixed liquor enter the first sedimentation tank 200, let it settle, and then transfer the first sludge from the bottom of the first sedimentation tank 200. The mixture in the first sedimentation tank 200 is introduced into the second reaction tank 300, and a second solution and reactants are added to the second reaction tank 300 to react with the mixture, so that the pH value of the mixture in the second reaction tank 300 is 7~8. The mixed liquid in the second reaction tank 300 is allowed to enter the second sedimentation tank 400. After settling, the second sludge and water in the second sedimentation tank 400 are recycled.

[0027] Specifically, after the wastewater enters the first reaction tank 100, a first solution and a second solution are added to react with the wastewater, which can make the pH value of the mixed liquid 8.5~9.5. This can effectively change the acidity of the wastewater. Then, the mixed liquid after reaction continues to enter the first sedimentation tank 200. After the mixed liquid settles, the first sludge at the bottom of the first sedimentation tank 200 can be transferred. Then, the mixed liquid enters the second reaction tank 300, where a second solution and reactants are added to react with the mixed liquid, making the pH value of the mixed liquid in the second reaction tank 300 7~8. At this time, the pH value of the mixed liquid tends to be normal. Then, the mixed liquid enters the second sedimentation tank 400. After settling, the second sludge and water in the second sedimentation tank 400 are recycled. In this way, the second sludge and water generated after the wastewater reaction and sedimentation can be recycled and reused. Specifically, the method for recovering fluoride from acid-washed quartz sand wastewater can effectively recycle and reuse wastewater.

[0028] Furthermore, in the step of "allowing wastewater to enter the first reaction tank 100, and simultaneously adding the first solution and the second solution to the first reaction tank 100 to react with the wastewater, so that the pH value of the mixture in the first reaction tank 100 is 8.5~9.5", in order to improve the reaction efficiency of the wastewater and the first and second solutions, and thus save time, the mixture of wastewater, the first solution and the second solution can be stirred by a stirring device in this step, thereby improving the reaction efficiency of the wastewater and the first and second solutions. Similarly, in the step of "allowing the mixture in the first sedimentation tank 200 to enter the second reaction tank 300, and adding the second solution and reactants to the second reaction tank 300 to react with the mixture, so that the pH value of the mixture in the second reaction tank 300 is 7~8", in order to improve the reaction efficiency of the mixture and reactants, and the second solution, and thus save time, the reaction mixture of the mixture, reactants and the second solution can be stirred by a stirring device in this step, thereby improving the reaction efficiency of the mixture, reactants and the second solution. Furthermore, by setting up the first reaction tank 100 and the first sedimentation tank 200 in this application, the reaction process and the sedimentation process can be separated. The reaction process itself is not conducive to sedimentation, making it difficult to separate the precipitate. However, by setting up the first sedimentation tank 200, the precipitate and the mixed liquor can be effectively separated. Similarly, by setting up the second reaction tank 300 and the second sedimentation tank 400, the reaction process and the sedimentation process can be separated. The reaction process itself is not conducive to sedimentation, making it difficult to separate the precipitate. However, by setting up the second sedimentation tank 400, the precipitate and the mixed liquor can be effectively separated.

[0029] To elaborate further, in the step of "allowing the mixed liquid in the first sedimentation tank 200 to enter the second reaction tank 300, and adding the second solution and reactants to the mixed liquid in the second reaction tank 300 to make the pH value of the mixed liquid in the second reaction tank 300 7~8", when the pH value of the mixed liquid is 7~8, water with a pH value of 7~8 is neutral to weakly alkaline, which can be recycled and reused, for example, for use in irrigating plants or for use in production.

[0030] Furthermore, the steps of the method for recovering fluoride from acid-washed quartz sand wastewater can be as follows: First, the wastewater enters the first reaction tank 100. A first solution and a second solution are added to the first reaction tank 100 via metering pumps. For example, 50 kg of the first solution is added to 1 ton of wastewater, and 14 kg of the second solution is added to 1 ton of wastewater. The pH value of the wastewater is adjusted from 2.2 to approximately 9 using a stirring device. The pH value can be detected using an online pH meter, and the stirring time can be 10 minutes. The second solution can flocculate precipitates and fine sand in the wastewater caused by pH changes. Second, the mixed liquid in the first reaction tank 100 is allowed to enter the first sedimentation tank 200. At this time, the fine sand and iron-aluminum ion precipitates are flocculated by PAM and become clumps, which fall rapidly to the bottom of the first sedimentation tank 200 under gravity. The first sludge can be pumped away by a slurry pump and then sent to a filter press 500. The water in the sludge is squeezed out by pressure, forming blocky sludge. The mixed liquid at the top of the first sedimentation tank 200 enters the second reaction tank 300. After the first treatment, the wastewater has a pH of 9.2, a fluoride ion content of 370 ppm, and an oxalate ion content of 10 ppm. Finally, the clarified mixture in the first sedimentation tank 200 is introduced into the second reaction tank 300. At this point, the mixture contains hydroxide and fluoride ions. Then, calcium chloride and oxalic acid are added to the second reaction tank 300 via a metering feeder. Calcium chloride can precipitate fluoride ions, and oxalic acid can adjust the pH value. Specifically, 0.8 kg of calcium chloride is added per ton of wastewater to precipitate fluoride ions, and 0.1 kg of oxalic acid is added per ton of wastewater to adjust the pH of the system and promote the formation of calcium fluoride. The second solution is then added to the second reaction tank 300 for mixing and precipitation. At this point, the main component of the precipitated second sludge is calcium fluoride. Calcium fluoride can be recovered, for example, by pumping it into a filter press 500 for dewatering to form solid calcium fluoride blocks. The water in the upper part of the second sedimentation tank 400 is recycled for reuse. At this point, the fluoride ion content in the water is 12 ppm, and the oxalate ion content is 10 ppm. The water can be recycled.

[0031] Furthermore, in some embodiments, the first solution is prepared by mixing water, diatomaceous earth, and potassium hydroxide in a ratio of 50:3:3.5. Specifically, the first solution can function as a pH adjuster, a physical adsorbent, and a flocculation aid, thereby treating the wastewater. These raw materials are relatively inexpensive, making the method for recovering fluoride from acid-washed quartz sand wastewater cost-effective.

[0032] Furthermore, in some embodiments, the method for recovering fluoride from acid-washed quartz sand wastewater further includes the step of adding water from the second sedimentation tank 400 to the preparation of the first solution. Specifically, the first solution requires water for reaction, and the water in the second sedimentation tank 400 meets the standards for production water. Therefore, the water in the second sedimentation tank 400 can be reasonably utilized for recycling, thereby saving costs.

[0033] Furthermore, in some embodiments, the second solution is prepared by mixing water and solid polyacrylamide in a ratio of 500:1. Specifically, after being prepared into a polyacrylamide solution using solid polyacrylamide, the polyacrylamide solution has a highly efficient flocculation and thickening effect. Thus, the polyacrylamide solution can promote the rapid aggregation and sedimentation of suspended particles in wastewater through adsorption bridging, thereby quickly forming the first sludge and the second sludge for treatment.

[0034] Furthermore, in some embodiments, the method for recovering fluoride from acid-washed quartz sand wastewater also includes the step of preparing a second solution in advance before allowing the wastewater to enter the first reaction tank 100. Specifically, in order to improve wastewater treatment efficiency, the second solution can be prepared in advance, avoiding the need to prepare the second solution only when treating the wastewater, which can greatly save time.

[0035] Furthermore, in some embodiments, the reactants include calcium chloride and oxalic acid. Specifically, oxalic acid can further adjust the pH value to meet the acceptable standard, and calcium chloride can participate in the reaction of the mixture to form calcium fluoride for recycling.

[0036] Please refer to Figure 1In some embodiments, the fluoride recovery device 10 for pickled quartz sand wastewater is used in any of the above embodiments for fluoride recovery from pickled quartz sand wastewater. The fluoride recovery device 10 includes: a first reaction tank 100, a first sedimentation tank 200, a second reaction tank 300, and a second sedimentation tank 400. The first reaction tank 100 has a space for treating wastewater, used for reacting the wastewater with a first solution and a second solution. The first reaction tank 100 can be constructed of concrete, or it can be made of stainless steel or alloy. The shape of the first reaction tank 100 can be a cube or a cuboid. The first sedimentation tank 200 is located beside the first reaction tank 100, and its height is lower than that of the first reaction tank 100. Specifically, the height of the first sedimentation tank 200 is lower than that of the first reaction tank 100, so that when the mixture overflows from the first reaction tank 100, the mixture can be transferred to the first sedimentation tank 200. Since the reaction in the first reaction tank 100 requires a stirring device to accelerate the reaction, sedimentation is inconvenient. Therefore, the mixed liquid can be allowed to settle in the first sedimentation tank 200. The first sedimentation tank 200 can be shaped like a cube or cuboid at the top and a cone at the bottom, which facilitates sedimentation and discharge of the first sludge. The second reaction tank 300 is located beside the first sedimentation tank 200, and its height is lower than that of the first sedimentation tank 200. Specifically, the second reaction tank 300 has a space for treating wastewater, used for the reaction of wastewater, reactants, and the second solution. The second reaction tank 300 can be constructed of concrete, stainless steel, or alloy. Its shape can be cube or cuboid. Because its height is lower than that of the first sedimentation tank 200, when the mixed liquid overflows from the first sedimentation tank 200, it can be transferred to the second reaction tank 300. The second sedimentation tank 400 is located beside the second reaction tank 300, and its height is lower than that of the second reaction tank 300. Since the reaction in the second reaction tank 300 requires a stirring device to accelerate the reaction, sedimentation is inconvenient; therefore, the mixed liquor can settle in the second sedimentation tank 400. The shape of the second sedimentation tank 400 can be a cube or cuboid at the top and a cone at the bottom, which facilitates sedimentation and discharge of the second sludge.

[0037] Specifically, after the wastewater enters the first reaction tank 100, it reacts with the first and second solutions, which adjusts the pH of the mixed solution to 8.5-9.5. This effectively changes the acidity of the wastewater. Since the height of the first sedimentation tank 200 is lower than that of the first reaction tank 100, the mixed solution can overflow from the first reaction tank 100 into the first sedimentation tank 200. The reacted mixed solution then continues to enter the first sedimentation tank 200. After settling, the first sludge at the bottom of the first sedimentation tank 200 can be transferred. Because the height of the second reaction tank 300 is lower than that of the first sedimentation tank 200, the mixed solution can overflow from the first reaction tank 100... The wastewater overflows into the first sedimentation tank 200, and a second solution and reactants are added to the second reaction tank 300 to react with the mixed liquid, making the pH value of the mixed liquid in the second reaction tank 300 7~8. At this time, the pH value of the mixed liquid tends to be normal. Since the height of the second sedimentation tank 400 is lower than that of the second reaction tank 300, the mixed liquid can overflow from the second reaction tank 300 into the second sedimentation tank 400. After settling, the second sludge and water in the second sedimentation tank 400 are recycled. In this way, the second sludge and water generated after the wastewater undergoes reaction and sedimentation can be recycled. Specifically, the acid washing quartz sand wastewater fluoride recovery device 10 can effectively recycle and reuse wastewater.

[0038] Furthermore, in some embodiments, the fluoride recovery device 10 for acid-washed quartz sand wastewater also includes two stirring devices, one of which is located in the first reaction tank 100 and the other in the second reaction tank 300. Specifically, the stirring device includes a drive component and a stirring paddle. The drive component can be a motor, which rotates and connects to the stirring paddle. The motor drives the stirring paddle to rotate, thereby stirring, which can accelerate the reaction speed and improve the efficiency of wastewater treatment.

[0039] Further, please refer to Figure 1 In some embodiments, the fluoride recovery device 10 for acid-washed quartz sand wastewater also includes a filter press 500 connected to a first sedimentation tank 200. The filter press 500 is used to treat the first sludge. Specifically, the filter press 500 can remove water from the first sludge, thereby turning the first sludge into a solid, which saves space occupied by the first sludge and facilitates its transfer and disposal. Furthermore, the filter press 500 can also be connected to a second sedimentation tank 400 to treat the second sludge.

[0040] Furthermore, in some embodiments, the fluoride recovery device 10 for acid-washed quartz sand wastewater also includes online pH meters, with two online pH meters respectively installed in the first reaction tank 100 and the second reaction tank 300. Specifically, the online pH meters can detect the pH value of the mixture in the first reaction tank 100 and the second reaction tank 300 in real time, thereby promptly reminding the operator. For example, when the pH value of the mixture reaches the required level, it can remind the operator to promptly transfer the mixture or stop adding the first solution, the second solution, and the reactants, thereby saving materials.

[0041] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for recovering fluoride from acid-washed quartz sand wastewater, characterized in that, Includes the following steps: Wastewater is introduced into the first reaction tank, and a first solution and a second solution are simultaneously added to the first reaction tank to react with the wastewater, so that the pH value of the mixture in the first reaction tank is 8.5~9.5; The mixture is allowed to enter the first sedimentation tank, and after settling, the first sludge at the bottom of the first sedimentation tank is transferred. The mixture in the first sedimentation tank is introduced into the second reaction tank, and the second solution and reactants are added to the second reaction tank to react with the mixture, so that the pH value of the mixture in the second reaction tank is 7~8; The mixture in the second reaction tank is allowed to enter the second sedimentation tank. After settling, the second sludge and water in the second sedimentation tank are recycled.

2. The method for recovering fluoride from acid-washed quartz sand wastewater according to claim 1, characterized in that, The first solution was prepared by mixing water, diatomaceous earth, and potassium hydroxide in a ratio of 50:3:3.

5.

3. The method for recovering fluoride from acid-washed quartz sand wastewater according to claim 2, characterized in that, It also includes the step of adding the water from the second sedimentation tank to the preparation of the first solution.

4. The method for recovering fluoride from acid-washed quartz sand wastewater according to claim 1, characterized in that, The second solution was prepared by mixing water and solid polyacrylamide in a ratio of 500:

1.

5. The method for recovering fluoride from acid-washed quartz sand wastewater according to claim 4, characterized in that, It also includes the step of preparing the second solution in advance, and then allowing the wastewater to enter the first reaction tank.

6. The method for recovering fluoride from acid-washed quartz sand wastewater according to claim 1, characterized in that, The reactants include calcium chloride and oxalic acid.

7. A device for recovering fluoride from acid-washed quartz sand wastewater, used in the method for recovering fluoride from acid-washed quartz sand wastewater according to any one of claims 1 to 6, characterized in that, The fluoride recovery device for acid-washed quartz sand wastewater includes: First reaction tank; The first sedimentation tank is located next to the first reaction tank, and the height of the first sedimentation tank is lower than the height of the first reaction tank. The second reaction tank is located next to the first sedimentation tank, and the height of the second reaction tank is lower than the height of the first sedimentation tank. The second sedimentation tank is located next to the second reaction tank, and the height of the second sedimentation tank is lower than the height of the second reaction tank.

8. The fluoride recovery device for acid-washed quartz sand wastewater according to claim 7, characterized in that, It also includes two stirring devices, one of which is located in the first reaction tank and the other of which is located in the second reaction tank.

9. The fluoride recovery device for acid-washed quartz sand wastewater according to claim 7, characterized in that, It also includes a filter press connected to the first sedimentation tank, the filter press being used to treat the first sludge.

10. The fluoride recovery device for acid-washed quartz sand wastewater according to claim 7, characterized in that, It also includes online pH meters, with two online pH meters respectively installed in the first reaction tank and the second reaction tank.

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