Fluorine resource recovery system for fluorine-containing wastewater

Abstract

The utility model relates to a fluorine resource recovery system for fluorine-containing waste water, which can be used for carrying out scientific classification and comprehensive treatment on high-purity quartz sand pickling waste liquid and rinsing waste water by arranging a pickling fluorine-containing waste water treatment module and a rinsing fluorine-containing waste water treatment module. According to the treatment mode, near-zero emission of the dangerous waste liquid or solid waste is achieved, the outsourcing treatment cost is effectively reduced, fluorine resources in the waste liquid or waste water can be efficiently recycled, high-purity sodium fluosilicate, calcium fluoride and other high-added-value products are produced, and extra economic benefits are brought to enterprises.

Description

Technical Field

[0001] The utility model relates to the technical field of water treatment, in particular to a fluorine resource recovery system for fluorine-containing wastewater. Background Art

[0002] High-purity quartz sand, due to its high stability and compressive strength, has become a core raw material for the production of quartz crucibles and plays a vital role in the photovoltaic and semiconductor industries. However, the purification process for high-purity quartz sand is complex and delicate, involving multiple steps such as magnetic separation, pickling, and flotation. Among these steps, pickling is particularly critical, using hydrofluoric acid to effectively remove metallic impurities from the quartz sand surface.

[0003] While the pickling process is crucial for improving the purity of quartz sand, it also produces two different types of wastewater: high-concentration fluorinated waste acid and low-concentration fluorinated rinse wastewater. While the volume of high-concentration fluorinated waste acid is relatively small, its pH is extremely low and it is rich in fluosilicic and hydrofluoric acids, making it more difficult to treat and potentially posing a greater threat to the environment. In contrast, low-concentration fluorinated rinse wastewater is larger in volume, has a lower pH, and contains relatively small amounts of fluoride, but its total amount is still significant.

[0004] Currently, the industry faces obvious limitations and challenges in its treatment methods for these two types of wastewater. High-concentration fluorine-containing waste acid is usually considered hazardous waste, and companies need to pay high fees for external treatment. This not only increases the company's operating costs, but may also cause secondary pollution to the environment due to improper treatment. On the other hand, although low-concentration fluorine-containing rinse wastewater can meet emission standards after treatment with traditional lime precipitation or other chemicals, this method consumes a lot of chemicals, and the resulting calcium fluoride sludge contains more impurities and a high water content, making it difficult to reuse. It is usually also treated as solid waste for external treatment.

[0005] Clearly, current treatment methods are not only costly but also wasteful and environmentally risky. Therefore, addressing the challenges encountered in high-purity quartz sand pickling wastewater treatment, such as high chemical consumption, expensive secondary pollution treatment, and wasted fluorine resources, there is an urgent need to develop a system that can effectively recover high-value-added fluorine resources. Such a system would not only reduce wastewater treatment costs but also enable resource recycling, thereby promoting sustainable development of the industry. Summary of the Invention

[0006] This application aims to solve the problems existing in the treatment process of high-purity quartz sand pickling wastewater, aiming to reduce the consumption of reagents, reduce the cost of secondary pollution disposal, and effectively recover and utilize fluorine resources in the wastewater.

[0007] To achieve the above objectives, this application is implemented through the following technical solutions:

[0008] The present application provides a fluorine resource recovery system for fluorine-containing wastewater, which is applied to a high-purity quartz sand production line, comprising:

[0009] A pickling fluorine-containing wastewater treatment module is used to treat high-concentration pickling fluorine-containing wastewater, comprising a first grit settling unit, a first regulating unit, a first by-product forming unit, a first solid-liquid separation unit, a first filtrate collecting unit, and a first solid collecting unit, wherein:

[0010] The inlet pipe of the first sand settling unit is connected to the outlet of the pickling process and is used to collect the high-concentration fluorine-containing wastewater discharged from the pickling process.

[0011] The first regulating unit pipeline is connected to the water outlet of the first grit unit, and is used to receive and regulate the high-concentration fluorine-containing wastewater discharged from the first grit unit.

[0012] The first by-product forming unit includes a reactor and a first dosing device. The inlet of the reactor is connected to the first regulating unit through a first pump, and is used to receive and treat the high-concentration fluorine-containing wastewater discharged from the first regulating unit. The first dosing device is connected to the reactor and is used to add drugs to the reactor to form the first by-product.

[0013] The inlet of the first solid-liquid separation unit is connected to the reactor via a second pump, and is used to receive and separate the first solid-liquid mixture discharged from the reactor after the reaction.

[0014] The inlet pipe of the first filtrate collecting unit is connected to the liquid outlet of the first solid-liquid separation unit for receiving the first waste liquid discharged from the first solid-liquid separation unit.

[0015] The first solid collecting unit is used to collect the first by-product separated by the first solid-liquid separation unit;

[0016] The rinsing fluorine-containing wastewater treatment module is used to treat low-concentration rinsing fluorine-containing wastewater, including a second grit settling unit, a second regulating unit, a second by-product forming unit, a second solid-liquid separation unit, a second solid collecting unit, and a second filtrate collecting unit, wherein:

[0017] The inlet pipe of the second sand settling unit is connected to the outlet of the rinsing process and is used to collect the low-concentration fluorine-containing wastewater discharged from the rinsing process.

[0018] The second regulating unit pipeline is connected to the water outlet of the second grit unit, and is used to receive and regulate the low-concentration fluorine-containing wastewater discharged from the second grit unit.

[0019] The second by-product forming unit includes a fluidized bed, a seed dosing device and a second dosing device. The bottom inlet of the fluidized bed is connected to the second regulating unit through a third pump, and is used to receive and process the low-concentration fluorine-containing wastewater discharged from the second regulating unit. The seed dosing device is connected to the fluidized bed and is used to add seed crystals to the fluidized bed. The second dosing device is connected to the fluidized bed and is used to add drugs to the fluidized bed to form the second by-product.

[0020] The inlet pipe of the second solid-liquid separation unit is connected to the fluidized bed, and is used to receive and separate the second solid-liquid mixture discharged from the fluidized bed after the reaction.

[0021] The inlet pipe of the second filtrate collecting unit is connected to the liquid outlet of the second solid-liquid separation unit for receiving the second waste liquid discharged from the second solid-liquid separation unit.

[0022] The second solid collecting unit is used to collect the second by-product filtered by the second solid-liquid separation unit.

[0023] As a further improvement of the present application, a quartz sand screening device is further included, wherein the quartz sand screening device is connected to the first sand settling unit and the second sand settling unit via pipelines, respectively, for receiving and screening sand and gravel discharged by the first sand settling unit and the second sand settling unit.

[0024] As a further improvement of the present application, the quartz sand screening device is connected to the seed adding device to replenish quartz sand seeds to the seed adding device.

[0025] As a further improvement of the present application, the outlet of the first filtrate collection unit is connected to the second regulating unit, which is used to transport the waste liquid discharged from the first solid-liquid separation unit to the second regulating unit so as to mix it with low-concentration fluoride-containing wastewater to adjust the concentration of fluoride ions in the wastewater.

[0026] As a further improvement of the present application, the fluidized bed is divided into a clear water zone, a sedimentation zone and a reaction zone from top to bottom, and the low-concentration fluorine-containing wastewater, crystal seeds and drugs are mixed and reacted in the reaction zone.

[0027] As a further improvement of the present application, a fourth pump is also included, wherein the fourth pump pipeline connects the clean water zone and the reaction zone, and is used to transport the wastewater from the clean water zone to the reaction zone with a preset water volume, so that a circulating water flow is formed inside the fluidized bed.

[0028] As a further improvement of the present application, the reaction zone of the fluidized bed is positioned higher than the second solid-liquid separation unit, and a discharge valve is provided at the bottom of the reaction zone of the fluidized bed, so that the second solid-liquid mixture in the reaction zone of the fluidized bed falls into the second solid-liquid separation unit by its own weight.

[0029] As a further improvement of the present application, the first solid-liquid separation unit is a centrifuge, and the second solid-liquid separation unit is a filter cloth drain box.

[0030] As a further improvement of the present application, the reactor is also connected to an exhaust gas treatment system.

[0031] As a further improvement of the present application, the clean water zone of the fluidized bed is also connected to a wastewater deep treatment system.

[0032] The beneficial effect of this application is that it provides a fluorine resource recovery system for fluorine-containing wastewater. By providing a pickling fluorine-containing wastewater treatment module and a rinsing fluorine-containing wastewater treatment module, the system can scientifically classify and comprehensively treat high-purity quartz sand pickling wastewater and rinsing wastewater. This treatment method not only achieves near-zero discharge of hazardous waste liquid or solid waste, effectively reducing outsourcing disposal costs, but also can efficiently recover fluorine resources in waste liquid or wastewater, producing high-value-added products such as high-purity sodium fluorosilicate and calcium fluoride, bringing additional economic benefits to the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of the fluorine resource recovery system for fluorine-containing wastewater in this application.

[0034] In the figure: 1. first grit unit; 2. first regulating unit; 3. first by-product forming unit; 4. first solid-liquid separation unit; 5. first filtrate collecting unit; 6. first solid collecting unit; 7. second grit unit; 8. second regulating unit; 9. second by-product forming unit; 10. second solid-liquid separation unit; 11. second solid collecting unit; 12. second filtrate collecting unit; 13. quartz sand screening device; 31. first dosing device; 32. reactor; 91. second dosing device; 92. seed adding device; 93. fluidized bed; 94. discharge valve. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments and drawings of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them, and are not intended to limit the scope of this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] This application provides a fluorine resource recovery system for fluorine-containing wastewater, particularly suitable for high-purity quartz sand production lines. It aims to efficiently and environmentally friendly treat and recover fluorine resources from fluorine-containing wastewater. The fluorine resource recovery system comprises an acid wash fluorine-containing wastewater treatment module, a rinse fluorine-containing wastewater treatment module, and other auxiliary modules.

[0037] The pickling fluorine-containing wastewater treatment module is used to treat high-concentration pickling fluorine-containing wastewater, and includes a first sand settling unit 1, a first regulating unit 2, a first by-product forming unit 3, a first solid-liquid separation unit 4, a first filtrate collecting unit 5, and a first solid collecting unit 6. Among them:

[0038] The inlet pipe of the first grit unit 1 is connected to the outlet of the pickling process and is used to collect the high-concentration fluorine-containing wastewater discharged from the pickling process. The unit is designed with a grit chamber to use gravity to settle large particles of sand and gravel in the wastewater.

[0039] The first regulating unit 2 is connected to the outlet of the first grit unit 1 through a pipeline, and is used to receive and regulate the high-concentration fluorine-containing wastewater discharged from the first grit unit 1, and to create favorable conditions for subsequent treatment by adjusting parameters such as pH value and temperature.

[0040] The first byproduct formation unit 3 includes a reactor 32 and a first dosing device 31. The inlet of the reactor 32 is connected to the first regulating unit 2 via a first pump, and is used to receive and treat the high-concentration fluorine-containing wastewater discharged from the first regulating unit 2. The first dosing device 31 is connected to the reactor 32 and is used to add a saturated sodium chloride solution to the reactor 32. The solution reacts with the fluoride ions in the wastewater to produce the first byproduct, sodium fluorosilicate. The first dosing device 31 precisely controls the dosage to ensure reaction efficiency.

[0041] The inlet of the first solid-liquid separation unit 4 is connected to the reactor 32 through a second pump, and is used to receive and separate the first solid-liquid mixture after the reaction discharged from the reactor 32. The first solid-liquid separation unit 4 is a centrifuge, which is used to perform solid-liquid separation to obtain a first waste liquid and a first by-product.

[0042] The first filtrate collecting unit 5 and the first solid collecting unit 6 are used to collect the first waste liquid and the first by-product respectively. The first waste liquid can be further processed or discharged, and the by-product can be used for the reuse of fluorine resources.

[0043] The rinse fluorine-containing wastewater treatment module is used to treat low-concentration rinse fluorine-containing wastewater, and includes a second sand settling unit 7, a second regulating unit 8, a second by-product forming unit 9, a second solid-liquid separation unit 10, a second solid collecting unit 11, and a second filtrate collecting unit 12.

[0044] The inlet pipe of the second grit unit 7 is connected to the outlet of the rinsing process and is used to collect the low-concentration fluorine-containing wastewater discharged from the rinsing process. This unit is also designed with a grit chamber to use gravity to settle large particles of sand and gravel in the wastewater.

[0045] The second regulating unit 8 is connected by a pipe to the outlet of the second grit unit 7 and is used to receive and regulate the low-concentration fluoride-containing wastewater discharged from the second grit unit 7 by adjusting parameters such as pH, temperature, and fluoride ion concentration to meet subsequent treatment requirements. The second regulating unit 8 is also connected by a pipe to the outlet of the first filtrate collection unit 5 to collect the first waste liquid discharged from the first solid-liquid separation unit 4. The second regulating unit 8 mixes the small-volume, high-concentration fluoride-containing wastewater with the large-volume, low-concentration fluoride-containing wastewater in a preset ratio, thereby controlling the fluoride ion concentration in the mixed wastewater within a preset range.

[0046] The second by-product formation unit 9 includes a fluidized bed, a seed crystal dosing device 92, and a second chemical dosing device 91. The fluidized bed is divided into a clear water zone, a settling zone, and a reaction zone. The bottom inlet of the fluidized bed is connected to the second regulating unit 8 via a third pump. The fluidized bed receives low-concentration fluoride-containing wastewater discharged from the second regulating unit 8 and adds seed crystals and chemicals to promote the crystallization reaction of fluoride ions. The low-concentration fluoride-containing wastewater, seed crystals, and chemicals mix and react in the reaction zone to produce the second by-product calcium fluoride. The added chemical is calcium chloride solution, and the added seed crystals are quartz sand.

[0047] A fourth pump pipeline connects the clean water zone and the reaction zone, and is used to transport wastewater from the clean water zone to the reaction zone at a preset volume. This creates a circulating water flow within the fluidized bed, fluidizing the seed crystals and ensuring sufficient contact and reaction between the various substances, thereby producing calcium fluoride particles with a relatively uniform particle size. The sedimentation zone is used for settling and collecting the crystals. A discharge valve 94 is provided at the bottom of the fluidized bed. When the generated calcium fluoride particles reach a preset height at the bottom of the fluidized bed, the discharge valve 94 is opened, allowing the calcium fluoride particles to flow by gravity into the filter cloth drain tank for treatment, thereby producing a high-purity calcium fluoride byproduct. Water between the particles quickly collects to the bottom of the filter cloth drain tank through its own weight, and then flows into the wastewater advanced treatment system through a drain pipe.

[0048] The second filtrate collecting unit 12 and the second solid collecting unit 11 are used to collect the second waste liquid and the second by-product, respectively.

[0049] Other auxiliary systems include a quartz sand screening device 13, an exhaust gas treatment system, and a wastewater advanced treatment system. The quartz sand screening device 13 is connected to the first and second grit settling units 1 and 7 to screen the discharged large sand and gravel. Some of the screened quartz sand can be added to the seed crystal dosing device 92 as seed crystals. The exhaust gas treatment system is connected to the reactor 32 to treat the exhaust gas generated during the reaction process and ensure environmentally friendly emissions. The wastewater advanced treatment system is connected to the clear water area of the fluidized bed to perform advanced wastewater treatment to meet higher emission standards.

[0050] In summary, the fluorine resource recovery system for fluorine-containing wastewater of this application has shown significant advantages in many aspects:

[0051] 1) Efficient Classification and Recovery: The system scientifically classifies and comprehensively treats high-purity quartz sand pickling wastewater and rinsing wastewater. This treatment method not only achieves near-zero discharge of hazardous liquid or solid waste, effectively reducing outsourcing disposal costs, but also efficiently recovers fluorine resources from the wastewater, producing high-value-added products such as high-purity sodium fluorosilicate and calcium fluoride, generating additional economic benefits for the company.

[0052] 2) Environmental Protection and Energy Saving: The system significantly reduces chemical consumption and wastewater discharge through precise dosing control and wastewater recycling, thereby minimizing environmental impact. In particular, the use of a crystallization fluidized bed process, which induces precipitation by adding seed crystals, accelerates the formation of calcium fluoride particles and reduces excessive chemical dosing, further embodying the concept of environmental protection and energy conservation.

[0053] 3) High value of by-products: Recovered by-products such as calcium fluoride and sodium fluorosilicate have high market value and can be widely used as raw materials in other industrial production fields, achieving a dual improvement in economic and environmental benefits.

[0054] 4) Flexibility and Applicability: The system can be flexibly adjusted and optimized based on actual production needs, adapting to the treatment requirements of fluorine-containing wastewater of varying concentrations and flow rates. Furthermore, the system utilizes waste generated during the high-purity quartz sand pickling process as seed crystals for the fluidized bed crystallization process, achieving comprehensive waste utilization and further enhancing the system's flexibility and applicability.

[0055] 5) Cost reduction: The calcium fluoride particles produced by the crystallization fluidized bed process are large, uniform in size, and have a low moisture content. There is no need for forced dehydration. Most of the inter-particle water can be removed in a short time by natural drainage, thereby significantly reducing the operating cost of wastewater treatment.

[0056] Although this specification is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0057] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of this application. They are not intended to limit the scope of protection of this application. Any equivalent implementation methods or changes that do not deviate from the technical spirit of this application should be included in the scope of protection of this application.

Claims

1. A fluorine resource recovery system for fluorine-containing wastewater, applied to a high-purity quartz sand production line, characterized in that: include: A pickling fluorine-containing wastewater treatment module is used to treat high-concentration pickling fluorine-containing wastewater, comprising a first grit settling unit, a first regulating unit, a first by-product forming unit, a first solid-liquid separation unit, a first filtrate collecting unit, and a first solid collecting unit, wherein: The inlet pipe of the first sand settling unit is connected to the outlet of the pickling process and is used to collect the high-concentration fluorine-containing wastewater discharged from the pickling process. The first regulating unit pipeline is connected to the water outlet of the first grit unit, and is used to receive and regulate the high-concentration fluorine-containing wastewater discharged from the first grit unit. The first by-product forming unit includes a reactor and a first dosing device. The inlet of the reactor is connected to the first regulating unit through a first pump, and is used to receive and treat the high-concentration fluorine-containing wastewater discharged from the first regulating unit. The first dosing device is connected to the reactor and is used to add drugs to the reactor to form the first by-product. The inlet of the first solid-liquid separation unit is connected to the reactor via a second pump, and is used to receive and separate the first solid-liquid mixture discharged from the reactor after the reaction. The inlet pipe of the first filtrate collecting unit is connected to the liquid outlet of the first solid-liquid separation unit for receiving the first waste liquid discharged from the first solid-liquid separation unit. The first solid collecting unit is used to collect the first by-product separated by the first solid-liquid separation unit; The rinsing fluorine-containing wastewater treatment module is used to treat low-concentration rinsing fluorine-containing wastewater, including a second grit settling unit, a second regulating unit, a second by-product forming unit, a second solid-liquid separation unit, a second solid collecting unit, and a second filtrate collecting unit, wherein: The inlet pipe of the second sand settling unit is connected to the outlet of the rinsing process and is used to collect the low-concentration fluorine-containing wastewater discharged from the rinsing process. The second regulating unit pipeline is connected to the water outlet of the second grit unit, and is used to receive and regulate the low-concentration fluorine-containing wastewater discharged from the second grit unit. The second by-product forming unit includes a fluidized bed, a seed dosing device and a second dosing device. The bottom inlet of the fluidized bed is connected to the second regulating unit through a third pump, and is used to receive and process the low-concentration fluorine-containing wastewater discharged from the second regulating unit. The seed dosing device is connected to the fluidized bed and is used to add seed crystals to the fluidized bed. The second dosing device is connected to the fluidized bed and is used to add drugs to the fluidized bed to form the second by-product. The inlet pipe of the second solid-liquid separation unit is connected to the fluidized bed, and is used to receive and separate the second solid-liquid mixture discharged from the fluidized bed after the reaction. The inlet pipe of the second filtrate collecting unit is connected to the liquid outlet of the second solid-liquid separation unit for receiving the second waste liquid discharged from the second solid-liquid separation unit. The second solid collecting unit is used to collect the second by-product filtered by the second solid-liquid separation unit.

2. The fluorine resource recovery system for fluorine-containing wastewater according to claim 1, characterized in that: It also includes a quartz sand screening device, which is connected to the first sand settling unit and the second sand settling unit through pipelines, and is used to receive and screen sand and gravel discharged by the first sand settling unit and the second sand settling unit.

3. The fluorine resource recovery system for fluorine-containing wastewater according to claim 2, characterized in that: The quartz sand screening device is connected to the seed adding device and is used to replenish quartz sand seeds to the seed adding device.

4. The fluorine resource recovery system for fluorine-containing wastewater according to claim 1, characterized in that: The outlet of the first filtrate collecting unit is connected to the second regulating unit for conveying the first waste liquid discharged from the first solid-liquid separation unit to the second regulating unit so as to mix with the low-concentration fluorine-containing waste water to regulate the concentration of fluoride ions in the waste water.

5. The fluorine resource recovery system for fluorine-containing wastewater according to claim 1, characterized in that: The fluidized bed is divided into a clear water zone, a sedimentation zone and a reaction zone from top to bottom, and the low-concentration fluorine-containing wastewater, crystal seeds and drugs are mixed and reacted in the reaction zone.

6. The fluorine resource recovery system for fluorine-containing wastewater according to claim 5, characterized in that: It also includes a fourth pump, the fourth pump pipeline connecting the clean water zone and the reaction zone, for transporting the wastewater from the clean water zone to the reaction zone with a preset water volume, so that a circulating water flow is formed inside the fluidized bed.

7. The fluorine resource recovery system for fluorine-containing wastewater according to claim 6, characterized in that: The reaction zone of the fluidized bed is located higher than the second solid-liquid separation unit. A discharge valve is provided at the bottom of the reaction zone of the fluidized bed. The second solid-liquid mixture in the reaction zone of the fluidized bed falls into the second solid-liquid separation unit by gravity.

8. The fluorine resource recovery system for fluorine-containing wastewater according to claim 1, characterized in that: The first solid-liquid separation unit is a centrifuge, and the second solid-liquid separation unit is a filter cloth drain tank.

9. The fluorine resource recovery system for fluorine-containing wastewater according to claim 1, characterized in that: The reactor is also connected to an exhaust gas treatment system.

10. The fluorine resource recovery system for fluorine-containing wastewater according to claim 6, characterized in that: The clear water area of the fluidized bed is also connected to a wastewater deep treatment system.

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