Method and system for treating boron trifluoride tail gas

Abstract

The invention provides a method and system for treating boron trifluoride tail gas, and relates to the technical field of boron trifluoride tail gas treatment. The method for treating the boron trifluoride tail gas comprises the following steps: under normal pressure, carrying out first mixing on the boron trifluoride tail gas and ammonia gas, and reacting to obtain a solid product A; heating the solid product A to obtain a solid mixture; carrying out second mixing on the solid mixture and water, and carrying out solid-liquid separation to obtain a solid product B and a solution; evaporating and crystallizing the solution to obtain a solid product C; according to the method for treating the boron trifluoride tail gas, most of boron trifluoride in the tail gas is removed, and effective components in the boron trifluoride tail gas can be utilized to the maximum extent under the condition that the boron trifluoride concentration is low.

Description

Technical Field

[0001] The present application relates to the technical field of boron trifluoride tail gas treatment, and in particular to a method and system for treating boron trifluoride tail gas. Background Art

[0002] Boron trifluoride gas is widely used in the production and manufacturing process of semiconductor devices. It is a P-type doping source for silicon and germanium epitaxy, diffusion and ion implantation, and is also used as a raw material for preparing optical fiber preforms. In the prior art, whether it is the production of boron trifluoride or the use of boron trifluoride, it is difficult to avoid the treatment of tail gas containing boron trifluoride.

[0003] Most of the existing boron trifluoride tail gas treatment methods are designed for the low-purity boron trifluoride gas production process, using alkaline solution for absorption or adsorbents. These methods of treating boron trifluoride tail gas use the principle of acid-base neutralization to uniformly absorb the acidic gas in the tail gas, and the treatment process fails to effectively utilize the boron trifluoride gas in the tail gas, resulting in low economic benefits. Summary of the invention

[0004] The purpose of the present application is to provide a method and system for treating boron trifluoride tail gas to solve the above problems.

[0005] To achieve the above objectives, the present application provides a method for treating boron trifluoride tail gas in a first aspect, comprising:

[0006] Under normal pressure, boron trifluoride tail gas and ammonia gas are first mixed to react to obtain a solid product A;

[0007] Heating the solid product A to obtain a solid mixture;

[0008] The solid mixture and water are subjected to a second mixing and solid-liquid separation to obtain a solid product B and a solution;

[0009] The solution is evaporated and crystallized to obtain a solid product C.

[0010] Optionally, the boron trifluoride tail gas is filtered before the first mixing.

[0011] Optionally, the molar amount of the ammonia gas is 1.02 to 1.05 times the molar amount of boron trifluoride in the boron trifluoride tail gas.

[0012] Optionally, the reaction temperature is 20°C-25°C, and the reaction time is 3h-5h.

[0013] Optionally, the temperature of the ammonia gas before the first mixing is 10°C-15°C.

[0014] Optionally, the heating temperature is 125°C-300°C, and the heating time is 4.5h-5.5h.

[0015] Optionally, the solid-liquid ratio of the solid mixture and the water is 1 g:4 mL-5 mL.

[0016] The second aspect of the present application provides a system for treating boron trifluoride tail gas, comprising:

[0017] The first reaction device is used for reacting the boron trifluoride tail gas with ammonia;

[0018] A second reaction device, used for decomposing the solid product A to obtain a solid mixture;

[0019] A dissolving device, used for dissolving the solid mixture to obtain a solid product B and a solution;

[0020] A solid-liquid separation device, used for separating the solid product B from the solution;

[0021] An evaporation crystallization device, used for evaporating and crystallizing the solution;

[0022] The first reaction device, the second reaction device, the dissolving device, the solid-liquid separation device, and the evaporation crystallization device are connected in sequence.

[0023] Optionally, the first reaction device includes a first reactor and a condensing device;

[0024] The material and / or coating of the first reactor is Teflon.

[0025] Optionally, the system for treating boron trifluoride tail gas meets at least one of the following conditions:

[0026] A. A collecting device is also provided between the first reaction device and the second reaction device;

[0027] The collecting device comprises a cyclone filter, a collecting box, and a pneumatic conveying device connected in sequence;

[0028] The inlet of the cyclone filter is connected to the outlet of the first reaction device;

[0029] The outlet of the pneumatic conveying device is connected to the inlet of the second reaction device;

[0030] B. The system further comprises a filtering device, which is used to filter the boron trifluoride tail gas;

[0031] The outlet of the filtering device is connected to the inlet of the first reaction device.

[0032] Compared with the prior art, the beneficial effects of this application include:

[0033] The method for treating boron trifluoride tail gas provided by the present application utilizes the reaction of boron trifluoride gas in the tail gas with ammonia to generate a solid coordination compound NH3BF3, and then heats and decomposes NH3BF3 to obtain a solid mixture composed of BN nanopowder and NH4BF4, and dissolves the solid mixture in deionized water. The BN nanopowder is insoluble in water. After solid-liquid separation, BN nanopowder solid and NH4BF4 aqueous solution are obtained. After evaporation and crystallization of the NH4BF4 aqueous solution, NH4BF4 paste salt is obtained. The method provided by the present application can remove most of the boron trifluoride in the tail gas, and when the boron trifluoride concentration is low, the effective components in the boron trifluoride tail gas can be utilized to the maximum extent possible.

[0034] The device for treating boron trifluoride tail gas provided in the present application can fully utilize the boron trifluoride tail gas generated during the filling process, and fully utilize the effective components of boron trifluoride therein to generate usable boron nitride and ammonium fluoroborate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0036] Figure 1 A schematic diagram of a device for treating boron trifluoride tail gas provided in this application;

[0037] Figure 2 is an X-ray image of the white powder prepared in Example 1;

[0038] Figure 3 is an X-ray image of the solid product B prepared in Example 1;

[0039] Figure 4 This is the X-ray image of the solid product C prepared in Example 1.

[0040] Digital ID Description:

[0041] 100-first reaction device, 110-first reactor, 120-condensing device, 200-collecting device, 210-cyclone filter, 220-collecting box, 230-pneumatic conveying device, 300-second reaction device, 400-dissolving device, 500-solid-liquid separation device, 510-centrifuge, 520-filter, 600-evaporation crystallization device, 700-first filtering device, 800-alkali solution treatment device. DETAILED DESCRIPTION

[0042] As used herein:

[0043] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0044] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0045] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0046] In these examples, parts and percentages are by mass unless otherwise indicated.

[0047] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0048] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0049] It should be noted that during the filling process of boron trifluoride gas products, boron trifluoride gas cylinders need to be repeatedly heated and vacuumed, which usually produces a certain amount of boron trifluoride tail gas. Gas cylinders used to contain electronic grade boron trifluoride need to be purged and replaced with finished gas to meet customer requirements for the product. During the filling process, the replaced tail gas usually contains a certain concentration of boron trifluoride gas, which contains gas impurities such as O2, N2, CO2, SO2, SiF4, HF, etc. These gas impurities will also generate other by-products during the recovery process, affecting the recovery and utilization of boron trifluoride; at this stage, this part of the tail gas is usually mixed with the waste gas in the production process and absorbed by alkaline solution, and the boron trifluoride component is not effectively utilized.

[0050] It should also be noted that the boron trifluoride content in the boron trifluoride tail gas generated during the filling process is 90%-95%.

[0051] The first aspect of the present application provides a method for treating boron trifluoride tail gas, comprising:

[0052] Under normal pressure, boron trifluoride tail gas and ammonia gas are first mixed to react to obtain a solid product A;

[0053] Heating the solid product A to obtain a solid mixture;

[0054] The solid mixture and water are subjected to a second mixing and solid-liquid separation to obtain a solid product B and a solution;

[0055] The solution is evaporated and crystallized to obtain a solid product C.

[0056] In some embodiments, the boron trifluoride tail gas is filtered before the first mixing.

[0057] It should be noted that the boron trifluoride tail gas is filtered to remove particulate matter in the gas.

[0058] In some embodiments, the molar amount of the ammonia gas is 1.02 to 1.05 times the molar amount of boron trifluoride in the boron trifluoride tail gas.

[0059] Optionally, the molar amount of ammonia can be 1.02 times, 1.03 times, 1.04 times, 1.05 times, or any value between 1.02 times and 1.05 times the molar amount of boron trifluoride in the boron trifluoride tail gas.

[0060] It should be noted that, since the effective content of boron trifluoride in the boron trifluoride tail gas is lower than that of the pure boron trifluoride substance, the heat release during the reaction is controllable, so the process is easier to control when the boron trifluoride tail gas is used to react with ammonia.

[0061] It should also be noted that the molar amount of ammonia must be greater than the molar amount of boron trifluoride in the boron trifluoride tail gas. If the molar amount of boron trifluoride in the boron trifluoride tail gas is higher than the molar amount of ammonia, the following reaction will occur:

[0062] 4BF3+3NH3=H3BO3+3HBF4;

[0063] During the reaction, trace amounts of SiF4 and HF in the tail gas of boron trifluoride will react with ammonia to generate Si3N4 and NH4F. The Si3N4 component is stable, but the generated NH4F is toxic and easily decomposed between 180℃ and 230℃. The reaction equation is as follows:

[0064] 3SiF4+4NH3=Si3N4+12HF;

[0065] HF+NH3=NH4F;

[0066] Therefore, to ensure the production of NH3BF3, ammonia needs to be in excess in the reaction system, maintaining the ammonia at 1.02 to 1.05 times the molar amount of boron trifluoride in the boron trifluoride tail gas, which can reduce the generation of side reactions.

[0067] In some embodiments, the reaction temperature is 20°C-25°C, and the reaction time is 3h-5h.

[0068] Optionally, the reaction temperature can be 20°C, 21°C, 22°C, 23°C, 24°C, 25°C or any value between 20°C and 25°C, and the reaction time can be 3h, 4h, 5h or any value between 3h and 5h.

[0069] It should be noted that the reaction temperature needs to be stabilized between 20°C and 25°C. The reaction time of boron trifluoride tail gas and ammonia is long at low temperatures, and the reaction rate needs to be maintained above 20°C. When the temperature is too high, the reaction is violent and the heat generated by the reaction is difficult to control.

[0070] In some embodiments, the temperature of the ammonia gas before the first mixing is 10°C-15°C.

[0071] Optionally, the temperature of the ammonia gas before the first mixing may be 10°C, 11°C, 12°C, 13°C, 14°C, 15°C or any value between 10°C and 15°C.

[0072] It should be noted that, since the reaction between ammonia and boron trifluoride is an exothermic reaction, the temperature of the ammonia before the first mixing is controlled between 10° C. and 15° C., which can better adjust the reaction temperature.

[0073] In some embodiments, the heating temperature is 125° C.-300° C., and the heating time is 4.5 h-5.5 h.

[0074] Optionally, the heating temperature can be 125°C, 150°C, 200°C, 250°C, 300°C or any value between 125°C and 300°C, and the heating time can be 4.5h, 5h, 5.5h or any value between 4.5h and 5.5h.

[0075] It should be noted that when the heating temperature is lower than 125°C, NH3BF3 hardly decomposes; when the temperature is higher than 300°C, the yield of BN generated by the decomposition of NH3BF3 increases slightly, but the yield of NH4BF4 decreases significantly. Heating temperatures higher than 300°C will cause NH4BF4 to decompose.

[0076] In some embodiments, the solid-to-liquid ratio of the solid mixture to the water is 1 g:4 mL-5 mL.

[0077] Optionally, the solid-to-liquid ratio of the solid mixture to water can be 1 g:4 mL, 1 g:4.5 mL, 1 g:5 mL or any value between 1 g:4 mL and 5 mL.

[0078] The second aspect of the present application provides a system for treating boron trifluoride tail gas, the device is used to perform the above method, comprising:

[0079] The first reaction device is used for reacting the boron trifluoride tail gas with ammonia;

[0080] A second reaction device, used for decomposing the solid product A to obtain a solid mixture;

[0081] A dissolving device, used for dissolving the solid mixture to obtain a solid product B and a solution;

[0082] A solid-liquid separation device, used for separating the solid product B from the solution;

[0083] An evaporation crystallization device, used for evaporating and crystallizing the solution;

[0084] The first reaction device, the second reaction device, the dissolving device, the solid-liquid separation device, and the evaporation crystallization device are connected in sequence.

[0085] In some embodiments, the first reaction device comprises a first reactor and a condensation device;

[0086] The material and / or coating of the first reactor is Teflon.

[0087] In some embodiments, the system for treating boron trifluoride tail gas satisfies at least one of the following conditions:

[0088] A. A collecting device is also provided between the first reaction device and the second reaction device;

[0089] The collecting device comprises a cyclone filter, a collecting box, and a pneumatic conveying device connected in sequence;

[0090] The inlet of the cyclone filter is connected to the outlet of the first reaction device;

[0091] The outlet of the pneumatic conveying device is connected to the inlet of the second reaction device;

[0092] B. The system further comprises a filtering device, which is used to filter the boron trifluoride tail gas;

[0093] The outlet of the filtering device is connected to the inlet of the first reaction device.

[0094] For details, please refer to Figure 1 As shown, the device for treating boron trifluoride tail gas provided in the present application comprises:

[0095] The first reaction device 100 includes a first reactor 110 and a condensation device 120. The first reactor 110 is used to react boron trifluoride tail gas with ammonia. The condensation device 120 is used to cool dry air and / or helium and ammonia.

[0096] A collecting device 200 is used to collect the solid product A obtained by the reaction;

[0097] The second reaction device 300 is used to decompose the solid product A to obtain a solid mixture;

[0098] A dissolving device 400 is used to dissolve the solid mixture to obtain a solid product B and a solution;

[0099] A solid-liquid separation device 500, used to separate the solid product B from the solution;

[0100] An evaporation crystallization device 600, used for evaporating and crystallizing the solution;

[0101] The first filtering device 700 is used to filter the boron trifluoride tail gas entering the first reaction device, so as to separate particulate matter in the boron trifluoride tail gas;

[0102] an alkali solution treatment device 800 for absorbing the gas separated by the cyclone filter 210 and / or the gas generated by the second reaction device 300;

[0103] In some embodiments, the filter in the first filter device 700 includes alkali metal and / or alkaline earth metal fluorides.

[0104] The first filtering device 700, the first reaction device 100, the collecting device 200, the second reaction device 300, the dissolving device 400, the solid-liquid separation device 500, and the evaporation crystallization device 600 are connected in sequence.

[0105] The first reactor 110 is provided with four inlets, the first inlet is used to input ammonia, the second inlet is used to input boron trifluoride tail gas, the third inlet is used to input dry air and / or helium, and the fourth inlet is used to input the gas in the collecting device 200. The inlet ends of the first inlet, the third inlet and the fourth inlet are all connected to the condensing device 120 (condenser), and the inlet end of the second inlet is connected to the first filtering device 700; when the first inlet and the second inlet are opened for reaction, the third inlet and the fourth inlet are closed, and when the reaction is finished, the first inlet and the second inlet are closed, and the third inlet and the fourth inlet are opened;

[0106] The collecting device 200 is provided with a cyclone filter 210, a collecting box 220, and a pneumatic conveying device 230. The inlet of the cyclone filter 210 is connected to the outlet of the first reaction device 100. The cyclone filter 210 is provided with an inlet and two outlets. When the third inlet and the fourth inlet of the first reaction device 100 are opened, the dry air and / or helium entering the third inlet of the first reaction device 100 will purge the solid product A obtained by the reaction, and pass through the inlet of the cyclone filter 210. After separation, the solid product A is conveyed to the collecting box 220 through the first outlet. The dry air and / or helium returns to the fourth inlet of the first reaction device 100 or enters the alkali solution treatment device 800 through the second outlet, thereby realizing the recycling of the dry air and / or helium; the solid product A in the collecting box 220 is conveyed to the second reaction device 300 through the pneumatic conveying device 230, and the inlet of the pneumatic conveying device 230 is used to input dry air and / or helium;

[0107] The second reaction device 300 is provided with two inlets, the first inlet is connected to the outlet of the pneumatic conveying device 230, and the second inlet is used to input dry air and / or helium; the second reaction device 300 is provided with two outlets, the first outlet is connected to the first inlet of the dissolving device 400, and is used to output the solid mixture obtained by heating, and the second outlet is connected to the alkali solution treatment device 800, and is used to output the gas generated during the heating process, because a small amount of NH4F will be generated during the heating process, and NH4F will decompose to generate HF+NH3;

[0108] The dissolving device 400 is provided with two inlets, the first inlet is connected to the second outlet of the second reaction device 300, and the second inlet is connected to the outlet of the filter 520;

[0109] The solid-liquid separation device 500 is provided with a centrifuge 510 and a filter 520 which are connected in sequence; the inlet of the centrifuge 510 is connected to the outlet of the dissolving device 400 , and the centrifuge 510 is provided with two outlets, the first outlet is connected to the evaporation crystallization device 600 , and the second outlet is connected to the inlet of the filter 520 .

[0110] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0111] Example 1

[0112] This embodiment provides a method for treating boron trifluoride tail gas, comprising:

[0113] S1: passing the boron trifluoride tail gas through a filter to remove particulate matter in the gas;

[0114] S2: In a 2L jacketed water-cooled Teflon reactor, the boron trifluoride tail gas and ammonia treated by S1 were introduced simultaneously in equal molar amounts at a flow rate of 0.7L / min, and the reaction was carried out under atmospheric pressure, wherein the temperature of the ammonia gas entering was maintained at 10°C, and the temperature of the boron trifluoride tail gas entering was maintained at room temperature, about 25°C, and the molar amount of ammonia was 1.02 times the molar amount of boron trifluoride in the boron trifluoride tail gas. The reaction was carried out in the reactor for 3 hours at a temperature of 20°C-25°C to obtain a white powder, which was subjected to X-ray analysis, as shown in FIG. Figure 2 As shown, it was confirmed that the product was NH3BF3;

[0115] S3: The obtained white powdery crystals are loaded into a graphite furnace reactor, heated to 125°C under dry nitrogen conditions, maintained for 5 hours, and the generated gas is passed into an alkaline solution for absorption. After the reaction is completed, the solid mixture in the container is naturally cooled to room temperature, and the solid mixture is extracted and subjected to X-ray phase analysis. The solid mixture consists of boron nitride (BN) and ammonium fluoroborate (NH4BF4); the solid mixture is transferred to a polypropylene container, in which the mixture is mixed with deionized water, and the solid-liquid ratio of the mixture to the deionized water is 1g:4mL, thereby forming a suspension;

[0116] S4: The suspended particles (solid product B) contained in the suspension are separated from the solution by centrifugation, and the suspended particles are dried. The XRD detection shows that the solid product B is BN. The XRD diagram is as follows: Figure 3 shown.

[0117] S5: The solution is evaporated, crystallized and dried to obtain a solid product C. The drying temperature is 70°C. The solid product C is NH4BF4 crystals as detected by XRD. The XRD pattern is as follows: Figure 4 shown.

[0118] Example 2

[0119] The difference from Example 1 is that the heating temperature of the graphite furnace reactor is 150°C.

[0120] Example 3

[0121] The difference from Example 1 is that the heating temperature of the graphite furnace reactor is 200°C.

[0122] Example 4

[0123] The difference from Example 1 is that the heating temperature of the graphite furnace reactor is 250°C.

[0124] Example 5

[0125] The difference from Example 1 is that the molar amount of ammonia is 1.05 times the molar amount of boron trifluoride in the boron trifluoride tail gas.

[0126] Example 6

[0127] The difference from Example 1 is that the temperature of the ammonia gas before the first mixing is 15°C.

[0128] Comparative Example 1

[0129] The difference from Example 1 is that the heating temperature of the graphite furnace reactor is 100° C.; X-ray phase analysis of the solid mixture shows that it is all NH3BF3, and no BN and NH4BF4 are found.

[0130] Comparative Example 2

[0131] The difference from Example 1 is that the heating temperature of the graphite furnace reactor is 350°C; X-ray phase analysis of the solid mixture shows BN and NH4BF4, but the contents are significantly lower than those in Example 1, and the gas generated by the decomposition of the graphite furnace reactor is significantly increased.

[0132] Comparative Example 3

[0133] The difference from Example 1 is that the temperature of the ammonia gas before the first mixing is 0°C, and the reaction is carried out in the reactor for 3 hours to obtain a white powder. X-ray analysis of the white powder confirms that the product is NH3BF3, but the yield is slightly lower than that in Example 1.

[0134] Comparative Example 4

[0135] The difference from Example 1 is that the temperature of the ammonia gas before the first mixing is 20°C, and the reaction is carried out in the reactor for 3 hours to obtain a white powder. X-ray analysis of the white powder confirms that the product is NH3BF3, but the reaction process is violent and a large amount of white smoke is generated.

[0136] The products produced during the preparation of the above-mentioned embodiments and comparative examples were subjected to quality inspection, and the specific results are shown in Table 1, wherein the NH3BF3 content is the mass of NH3BF3 in the white powder after the reaction is completed, BN is the mass of the suspended particles after drying, and NH4BF4 is the mass of the evaporated crystals and dried.

[0137] Table 1 Quality inspection

[0138] sample <![CDATA[NH3BF3]]> BN <![CDATA[NH4BF4]]> Example 1 650g 17.2g 221g Example 2 650g 18.7g 205g Example 3 650g 19.3g 180g Example 4 650g 17.1g 175g Example 5 650g 17.3g 221g Example 6 643g 16.5 202g Comparative Example 1 650g 0g 0g Comparative Example 2 650g 16.7g 2g Comparative Example 3 603g 14.6g 172g Comparative Example 4 650g 17.0g 211g

[0139] From the results in Table 1, it can be seen that when the heating temperature of the graphite furnace reactor is 125°C, the output of boron nitride and ammonium fluoroborate is high. When the reaction temperature of the graphite furnace is increased, the output of BN increases slightly, but the output of ammonium fluoroborate decreases rapidly. When the temperature of the graphite furnace is greater than 350°C, a large amount of ammonium fluoroborate will decompose.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0141] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for treating boron trifluoride tail gas, characterized in that: include: Under normal pressure, boron trifluoride tail gas and ammonia gas are first mixed to react to obtain a solid product A; Heating the solid product A to obtain a solid mixture; The solid mixture and water are subjected to a second mixing and solid-liquid separation to obtain a solid product B and a solution; The solution is evaporated and crystallized to obtain a solid product C.

2. The method for treating boron trifluoride tail gas according to claim 1, characterized in that: The boron trifluoride tail gas is filtered before the first mixing.

3. The method for treating boron trifluoride tail gas according to claim 1, characterized in that: The molar amount of the ammonia gas is 1.02 to 1.05 times the molar amount of the boron trifluoride in the boron trifluoride tail gas.

4. The method for treating boron trifluoride tail gas according to claim 1, characterized in that: The reaction temperature is 20°C-25°C and the reaction time is 3h-5h.

5. The method for treating boron trifluoride tail gas according to claim 1, characterized in that: The temperature of the ammonia gas before the first mixing is 10°C-15°C.

6. The method for treating boron trifluoride tail gas according to claim 1, characterized in that: The heating temperature is 125° C.-300° C., and the heating time is 4.5 h-5.5 h.

7. The method for treating boron trifluoride tail gas according to any one of claims 1 to 6, characterized in that: The solid-to-liquid ratio of the solid mixture to the water is 1 g:4 mL-5 mL.

8. A system for treating boron trifluoride tail gas, characterized in that: include: The first reaction device is used for reacting the boron trifluoride tail gas with ammonia; A second reaction device, used for decomposing the solid product A to obtain a solid mixture; A dissolving device, used for dissolving the solid mixture to obtain a solid product B and a solution; A solid-liquid separation device, used for separating the solid product B from the solution; An evaporation crystallization device, used for evaporating and crystallizing the solution; The first reaction device, the second reaction device, the dissolving device, the solid-liquid separation device, and the evaporation crystallization device are connected in sequence.

9. The system for treating boron trifluoride tail gas according to claim 8, characterized in that: The first reaction device comprises a first reactor and a condensing device; The material and / or coating of the first reactor is Teflon.

10. The system for treating boron trifluoride tail gas according to claim 8, characterized in that: At least one of the following conditions is met: A. A collecting device is also provided between the first reaction device and the second reaction device; The collecting device comprises a cyclone filter, a collecting box, and a pneumatic conveying device connected in sequence; The inlet of the cyclone filter is connected to the outlet of the first reaction device; The outlet of the pneumatic conveying device is connected to the inlet of the second reaction device; B. The system further comprises a filtering device, which is used to filter the boron trifluoride tail gas; The outlet of the filtering device is connected to the inlet of the first reaction device.

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