A CVD dust and waste hydrofluoric acid coordinated treatment system

Abstract

The utility model relates to the technical field of hazardous waste treatment, and specifically to a CVD dust and waste hydrofluoric acid coordinated treatment system, comprising an ammonia water storage tank, a first reaction device, a second reaction device and a third reaction device; the first reaction device is respectively connected to the ammonia water storage tank and the third reaction device; the second reaction device is respectively connected to the ammonia water storage tank and the third reaction device. The utility model generates white carbon black (silicon dioxide) products by comprehensively utilizing silicon resources in CVD dust and waste hydrofluoric acid, and further utilizes its fluorine resources to generate sodium fluoride products, which not only achieves the purpose of waste resource utilization, but also avoids environmental pollution, and also has the characteristics of stable operation, convenient management, simple operation, low investment, high economic benefits, etc.

Description

Technical Field

[0001] The utility model relates to the technical field of hazardous waste treatment, in particular to a CVD dust and waste hydrofluoric acid coordinated treatment system. Background Art

[0002] Chemical vapor deposition (CVD) is a new technology for preparing inorganic materials developed in recent decades. This technology can prepare materials such as crystals, films, fibers, etc., and is used in many fields, such as semiconductor industry, electronic devices, photovoltaics, optoelectronics and other industries. Chemical vapor deposition (CVD) uses different raw materials due to its different application fields and uses. Silane (SiH 4 ), borane (B 2 H 6 ), tetraethyl orthosilicate, N 2 O、NH 3 , C 2 F 6 NF 3 , He and other gases. This process will produce a large amount of waste gas. After high-temperature incineration, the waste gas will often produce a large amount of silicon-containing and fluorine-containing dust. This type of dust has fine particles, large specific surface area and is fluffy. It easily forms a gel when it comes into contact with water, and it is difficult to separate and recover useful components. At present, the industry mainly uses lime neutralization to treat this type of fluorine-containing dust, but it will produce a large amount of calcium fluoride slag and silicon dioxide slag, a large amount of sludge, high processing cost, and easy to cause secondary pollution. Therefore, it is urgent to find an economical and reasonable resource utilization route to turn these CVD fluorine-containing wastes into treasures.

[0003] Crystalline silicon solar cells can convert solar radiation into electrical energy for human use, and have the advantages of being clean and sustainable. Its production process mainly includes texturing, pickling, diffusion, laser SE, etching and back polishing, oxidation and front and back coating, laser grooving, screen printing, sintering, electrical injection or light injection, testing and sorting, etc. During the production process, a certain amount of hydrofluoric acid, hydrochloric acid, nitric acid, sodium hydroxide, potassium hydroxide, etc. will be consumed, among which hydrofluoric acid is one of the necessary chemicals. The pollution indicators in the wastewater of the battery workshop mainly include the pH value of the wastewater and the content of fluoride ions. Waste hydrofluoric acid is highly corrosive and belongs to hazardous waste. If it is discharged arbitrarily, it will cause serious pollution to surface water, groundwater and soil. It must be effectively treated or comprehensively utilized to eliminate its pollution and protect the environment. At present, the waste hydrofluoric acid discharged by chemical enterprises, etching enterprises, photovoltaic enterprises, etc. has a HF content of 20%-30%. According to the traditional neutralization treatment method, a large amount of lime is required, and the neutralization slag is difficult to handle, which is easy to cause secondary pollution and waste a large amount of hydrofluoric acid in vain. Utility Model Content

[0004] In order to overcome the shortcomings and deficiencies in the prior art, the utility model aims to provide a CVD dust and waste hydrofluoric acid coordinated treatment system.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a CVD dust and waste hydrofluoric acid coordinated treatment system, including an ammonia water storage tank, a first reaction device, a second reaction device and a third reaction device; the first reaction device is respectively connected to the ammonia water storage tank and the third reaction device; the second reaction device is respectively connected to the ammonia water storage tank and the third reaction device.

[0006] In some embodiments, the first reaction device includes a first reaction tank and a first filter press, and the ammonia water storage tank, the first reaction tank, the first filter press and the third reaction device are connected in sequence.

[0007] In some embodiments, the first filter press has a first solid discharge port and a first liquid discharge port, and the first liquid discharge port is connected to the third reaction device; and / or

[0008] The first reaction tank is provided with a first stirring structure.

[0009] In some embodiments, the first reaction tank is provided with a first pipeline for introducing waste hydrofluoric acid.

[0010] In some embodiments, the second reaction device includes a second reaction tank and a second filter press, and the ammonia water storage tank, the second reaction tank, the second filter press and the third reaction device are connected in sequence.

[0011] In some embodiments, the second filter press has a second solid discharge port and a second liquid discharge port, and the second liquid discharge port is connected to the third reaction device; and / or

[0012] The second reaction tank is provided with a second stirring structure.

[0013] In some embodiments, the second reaction tank is provided with a second pipeline for introducing steam.

[0014] In some embodiments, the third reaction device includes a third reaction tank and a third filter press, and the third reaction tank is connected to the first reaction device, the second reaction device and the third filter press respectively.

[0015] In some embodiments, a dryer is further included, wherein the dryer is connected to the third filter press; and / or

[0016] The third reaction tank is provided with a third stirring structure.

[0017] In some embodiments, the third filter press has a third solid discharge port and a third liquid discharge port, and the dryer is connected to the third solid discharge port.

[0018] Compared with the prior art, the utility model has the following advantages:

[0019] The utility model avoids the waste of resources caused by the harmless treatment of CVD dust and waste hydrofluoric acid, generates white carbon black (silicon dioxide) products by comprehensively utilizing silicon resources in CVD dust and waste hydrofluoric acid, and further utilizes the fluorine resources to generate sodium fluoride products, thereby achieving the purpose of waste resource utilization and avoiding environmental pollution, and also having the characteristics of stable operation, convenient management, simple operation, low investment, high economic benefit, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments.

[0021] Figure 1 A schematic diagram of the structure provided for an embodiment of the present application.

[0022] The attached drawings are marked as: 1. Ammonia water storage tank; 2. First reaction tank; 3. Second reaction tank; 4. First filter press; 5. Second filter press; 6. Third reaction tank; 7. Third filter press; 8. Dryer. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

[0024] In this application, "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0025] In the present application, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c" can all mean: a, b, c, a+b, a+c, b+c, or a+b+c, where a, b, c can be single or multiple, respectively.

[0026] See also Figure 1 This embodiment provides a CVD dust and waste hydrofluoric acid coordinated treatment system, including an ammonia water storage tank 1, a first reaction device, a second reaction device and a third reaction device; the first reaction device is respectively connected to the ammonia water storage tank 1 and the third reaction device; the second reaction device is respectively connected to the ammonia water storage tank 1 and the third reaction device.

[0027] It can be understood that the first reaction device and the second reaction device can respectively process CVD dust and waste hydrofluoric acid at the same time, and the materials after the reaction enter the third reaction device for the next reaction, thereby achieving coordinated treatment of CVD dust and waste hydrofluoric acid, realizing waste resource utilization, and improving treatment efficiency.

[0028] Optionally, the first reaction device comprises a first reaction tank 2 and a first filter press 4, and the ammonia water storage tank 1, the first reaction tank 2, the first filter press 4 and the third reaction device are connected in sequence.

[0029] Optionally, the first filter press 4 has a first solid discharge port and a first liquid discharge port, and the first liquid discharge port is connected to the third reaction device; and / or, a first stirring structure is provided in the first reaction tank 2.

[0030] Optionally, the first reaction tank 2 is provided with a first pipeline for introducing waste hydrofluoric acid.

[0031] It can be understood that the liquid medicine in the ammonia water storage tank 1 is high-concentration ammonia water, and the ammonia water storage tank 1 transports the liquid medicine to the first reaction tank 2, and adjusts the pH to 7-8 to be suitable for the occurrence of the reaction; during the treatment process, the waste hydrofluoric acid is transferred to the first reaction tank 2, and then the first stirring structure in the first reaction tank 2 is opened, and then the ammonia water in the ammonia water storage box is passed into the first reaction tank 2, and the pH is adjusted to 7-8 to promote the reaction. After the reaction in the first reaction tank 2 is carried out for at least 30 minutes, the material in the first reaction tank 2 is an ammonium fluoride mixed liquid, and the ammonium fluoride mixed liquid after the reaction is completed is transferred to the first filter press 4 for filtration, and then the by-product white carbon black (silicon dioxide) is obtained at the first solid discharge port of the first filter press 4, and the pure ammonium fluoride solution obtained at the first liquid discharge port of the first filter press 4 is transferred to the third reaction tank 6.

[0032] Optionally, the second reaction device comprises a second reaction tank 3 and a second filter press 5, and the ammonia water storage tank 1, the second reaction tank 3, the second filter press 5 and the third reaction device are connected in sequence.

[0033] Optionally, the second filter press 5 has a second solid discharge port and a second liquid discharge port, and the second liquid discharge port is connected to the third reaction device; and / or, a second stirring structure is provided in the second reaction tank 3.

[0034] Optionally, the second reaction tank 3 is provided with a second pipeline for introducing steam.

[0035] It can be understood that, during the treatment process, tap water is first transferred to the second reaction tank 3, then the second stirring structure in the second reaction tank 3 is opened, CVD dust is added and steam is introduced through the second pipe to heat and dissolve, the temperature is maintained at 60-70°C, and then the ammonia water in the ammonia water storage box is introduced into the first reaction tank 2, and the pH is adjusted to 7-8 to promote the reaction. After the reaction in the second reaction tank 3 is carried out for at least 30 minutes, the material in the second reaction tank 3 is an ammonium fluoride mixture, and the ammonium fluoride mixture after the reaction is completed is transferred to the second filter press 5 for filtration, and then the by-product white carbon black (silicon dioxide) is obtained at the second solid discharge port of the second filter press 5, and the pure ammonium fluoride solution obtained at the second liquid discharge port of the second filter press 5 is transferred to the third reaction tank 6.

[0036] Optionally, the third reaction device comprises a third reaction tank 6 and a third filter press 7, and the third reaction tank 6 is connected to the first reaction device, the second reaction device and the third filter press 7 respectively.

[0037] It can be understood that the third reaction tank 6 is connected to the first reaction tank 2 , the second reaction tank 3 and the third filter press 7 respectively.

[0038] Optionally, a dryer 8 is further included, and the dryer 8 is connected to the third filter press 7; and / or a third stirring structure is provided in the third reaction tank 6.

[0039] Optionally, the third filter press 7 has a third solid discharge port and a third liquid discharge port, and the dryer 8 is connected to the third solid discharge port.

[0040] It can be understood that, during the treatment process, after the ammonium fluoride solution is loaded into the third reaction tank 6, the third stirring structure in the third reaction tank 6 is then opened, and then solid sodium chloride is added to the third reaction tank 6. After the reaction in the third reaction tank 6 is carried out for at least 30 minutes, the sodium fluoride mixed liquid after the reaction is completed is transferred to the third filter press 7 for filtration. The liquid obtained at the third liquid discharge port of the third filter press 7 is the ammonium chloride waste liquid, and the solid obtained at the third solid discharge port of the third filter press 7 is the desired crude sodium fluoride sample. Finally, the crude sodium fluoride sample is transferred to the dryer 8, and the desired sodium fluoride product can be obtained after being treated in the dryer 8.

[0041] Specifically, the CVD dust and waste hydrofluoric acid coordinated treatment system of this embodiment is used for treatment. First, about 5m 3 The waste hydrofluoric acid is in the first reaction tank 2, and then 8m of 28% ammonia water is introduced through the ammonia water storage tank 1. 3 After the reaction lasts for 30 minutes, the material in the first reaction tank 2 is passed into the first filter press 4, and the ammonium fluoride solution is transferred to the third reaction tank 6; at the same time, 3 tons of CVD dust and 9 tons of tap water are added to the second reaction tank 3, heated to 60-70°C, and then 4 tons of 28% ammonia water are passed through the ammonia water storage tank 1. 3 After reacting for 30 minutes, the material in the second reaction tank 3 is passed into the second filter press 5, and the ammonium fluoride solution is transferred to the third reaction tank 6; finally, 6 tons of sodium chloride are added to the third reaction tank 6. After reacting for 30 minutes, the material in the third reaction tank 6 is passed into the third filter press 7. The obtained solid is the desired crude sodium fluoride product. After passing through the dryer 8, the desired sodium fluoride product can be obtained. The test results are shown in Table 1, which all meet the second-class sodium fluoride standard of YS / T 517-2009.

[0042] Table 1 Sodium fluoride product test results

[0043]

[0044]

[0045] It can be seen that the embodiments of the present application avoid the waste of resources caused by the harmlessness of CVD dust and waste hydrofluoric acid, and generate white carbon black (silicon dioxide) products by comprehensively utilizing silicon resources in CVD dust and waste hydrofluoric acid, and further utilizing their fluorine resources to generate sodium fluoride products, which not only achieves the purpose of waste resource utilization, but also avoids environmental pollution, and also has the characteristics of stable operation, convenient management, simple operation, low investment, high economic benefits, etc.

[0046] The embodiments of the present application are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the description of the above embodiments is only used to help understand the present application. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A CVD dust and waste hydrofluoric acid coordinated treatment system, characterized in that: It includes an ammonia water storage tank, a first reaction device, a second reaction device and a third reaction device; The first reaction device is connected to the ammonia water storage tank and the third reaction device respectively; The second reaction device is connected to the ammonia water storage tank and the third reaction device respectively.

2. The CVD dust and waste hydrofluoric acid coordinated treatment system according to claim 1, characterized in that: The first reaction device comprises a first reaction tank and a first filter press, and the ammonia water storage tank, the first reaction tank, the first filter press and the third reaction device are connected in sequence.

3. The CVD dust and waste hydrofluoric acid coordinated treatment system according to claim 2, characterized in that: The first filter press has a first solid discharge port and a first liquid discharge port, and the first liquid discharge port is connected to the third reaction device; and / or The first reaction tank is provided with a first stirring structure.

4. The CVD dust and waste hydrofluoric acid coordinated treatment system according to claim 2, characterized in that: The first reaction tank is provided with a first pipeline for introducing waste hydrofluoric acid.

5. The CVD dust and waste hydrofluoric acid coordinated treatment system according to claim 1, characterized in that: The second reaction device comprises a second reaction tank and a second filter press, and the ammonia water storage tank, the second reaction tank, the second filter press and the third reaction device are connected in sequence.

6. The CVD dust and waste hydrofluoric acid coordinated treatment system according to claim 5, characterized in that: The second filter press has a second solid discharge port and a second liquid discharge port, and the second liquid discharge port is connected to the third reaction device; and / or The second reaction tank is provided with a second stirring structure.

7. The CVD dust and waste hydrofluoric acid coordinated treatment system according to claim 5, characterized in that: The second reaction tank is provided with a second pipeline for introducing steam.

8. The CVD dust and waste hydrofluoric acid coordinated treatment system according to claim 1, characterized in that: The third reaction device comprises a third reaction tank and a third filter press, and the third reaction tank is connected to the first reaction device, the second reaction device and the third filter press respectively.

9. The CVD dust and waste hydrofluoric acid coordinated treatment system according to claim 8, characterized in that: It also includes a dryer, wherein the dryer is connected to the third filter press; and / or The third reaction tank is provided with a third stirring structure.

10. The CVD dust and waste hydrofluoric acid coordinated treatment system according to claim 9, characterized in that: The third filter press has a third solid discharge port and a third liquid discharge port, and the dryer is connected to the third solid discharge port.

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