Fluorine-containing mixed acid treatment method and system

Abstract

The invention discloses a fluorine-containing mixed acid treatment method and system, and relates to treatment of fluorine-containing mixed acid after rare earth kiln tail gas is absorbed, and the fluorine-containing mixed acid treatment system comprises a pipeline assembly, a heater, a separator, a fluorine acid condenser, a fluorine acid collecting tank, a sulfuric acid condenser and a sulfuric acid collecting tank; a multi-effect concentration rectifying tower is connected to the pipeline assembly, mixed acid at the bottom of the front-effect concentration rectifying tower overflows into the rear-effect concentration rectifying tower, a heater is arranged in the concentration rectifying tower, and the heater is horizontally arranged in the concentration rectifying tower; a separator is arranged at the top of the concentration rectifying tower; the fluorine acid condenser is vertically arranged, and fluorine acid passing through the fluorine acid condenser enters the fluorine acid collecting tank; the sulfuric acid condenser is arranged at the tower bottom of the last-effect concentration rectifying tower; and the sulfuric acid passing through the sulfuric acid condenser enters the sulfuric acid collecting tank. The heater is horizontally arranged in the concentration rectifying tower, and the fluorine acid condenser is vertically arranged, so that sulfur separated by condensation of fluorine acid can be prevented from blocking the heater, and the fluorine-containing mixed acid treatment system can stably operate for a long time.

Description

Technical Field

[0001] The invention relates to a method and a system for treating fluorine-containing mixed acid, belonging to the technical field of chemical industry. Background Art

[0002] During rare earth smelting production, the fluorine-containing tail gas produced by the roasting kiln produces a large amount of fluorine-containing mixed acid after absorption. The mixed acid is directly neutralized to produce solid waste, which causes harm to human health and the surrounding environment. The mixed acid needs to be separated into fluoric acid and sulfuric acid for recycling.

[0003] The traditional separation method can only separate sulfuric acid and return it to the kiln for continued use. The separated fluoric acid cannot be used directly due to its high sulfuric acid content, and the recovery and utilization of fluoric acid cannot be achieved.

[0004] At the same time, during the mixed acid separation process, the condensation of fluoric acid will precipitate sulfur, which will block the heater and fluoric acid condenser, and the sulfuric acid condenser will be blocked, resulting in short device operation time and high maintenance frequency. Summary of the invention

[0005] In view of the deficiencies of the prior art, the object of the present invention is to provide a method and system for treating fluorine-containing mixed acid;

[0006] In one aspect, the present invention provides a fluorine-containing mixed acid treatment system, comprising a pipeline assembly, a heater, a separator, a fluoric acid condenser, a fluoric acid collection tank, a sulfuric acid condenser and a sulfuric acid collection tank;

[0007] The pipeline assembly is connected to a multi-effect concentrating and rectifying tower, and two adjacent concentrating and rectifying towers are connected via the pipeline assembly, and the mixed acid at the bottom of the preceding concentrating and rectifying tower overflows into the subsequent concentrating and rectifying tower.

[0008] A heater is provided in each effect of the concentration and distillation tower, and the heater is horizontally arranged in the concentration and distillation tower;

[0009] A separator is provided at the top of each effective concentration and distillation tower;

[0010] The fluoric acid condenser is arranged on the pipeline assembly, and the fluoric acid condenser is arranged vertically.

[0011] The fluoric acid passing through the fluoric acid cooler enters the fluoric acid collection tank;

[0012] The sulfuric acid condenser is arranged at the bottom of the last effect concentration and rectification tower;

[0013] The sulfuric acid passing through the sulfuric acid condenser enters the sulfuric acid collecting tank.

[0014] Furthermore, the multi-effect concentrating distillation tower includes a first-effect concentrating distillation tower, a second-effect concentrating distillation tower and a third-effect concentrating distillation tower, the bottom of the first-effect concentrating distillation tower is connected to the second-effect concentrating distillation tower so that the mixed acid at the bottom of the first-effect concentrating distillation tower overflows into the second-effect concentrating distillation tower; the bottom of the second-effect concentrating distillation tower is connected to the third-effect concentrating distillation tower so that the mixed acid at the bottom of the second-effect concentrating distillation tower overflows into the third-effect concentrating distillation tower.

[0015] Furthermore, the fluoric acid condenser comprises a second fluoric acid condenser connected to the second-effect concentrating and rectifying tower and a third fluoric acid condenser connected to the third-effect concentrating and rectifying tower; the fluoric acid separated from the top of the second-effect concentrating and rectifying tower enters the fluoric acid collecting tank through the second fluoric acid condenser; the fluoric acid separated from the top of the third-effect concentrating and rectifying tower enters the fluoric acid collecting tank through the third fluoric acid condenser.

[0016] Furthermore, the separator at the top of the first-effect concentrating and distilling tower is connected to the heater in the second-effect concentrating and distilling tower through a pipeline assembly.

[0017] Furthermore, the multi-effect concentrating distillation tower includes a fourth-effect concentrating distillation tower, a fifth-effect concentrating distillation tower, a sixth-effect concentrating distillation tower and a seventh-effect concentrating distillation tower. The bottom of the fourth-effect concentrating distillation tower is connected to the fifth-effect concentrating distillation tower, so that the mixed acid at the bottom of the fourth-effect concentrating distillation tower overflows into the fifth-effect concentrating distillation tower; the bottom of the fifth-effect concentrating distillation tower is connected to the sixth-effect concentrating distillation tower, so that the mixed acid at the bottom of the fifth-effect concentrating distillation tower overflows into the sixth-effect concentrating distillation tower; the bottom of the sixth-effect concentrating distillation tower is connected to the seventh-effect concentrating distillation tower, so that the mixed acid at the bottom of the sixth-effect concentrating distillation tower overflows into the seventh-effect concentrating distillation tower.

[0018] Furthermore, the fluoric acid condenser includes a fifth fluoric acid condenser connected to the fifth effect concentrating and rectifying tower and a sixth fluoric acid condenser connected to the sixth effect concentrating and rectifying tower. The fluoric acid separated from the top of the fifth effect concentrating and rectifying tower enters the fluoric acid collecting tank through the fifth fluoric acid condenser; the fluoric acid separated from the top of the sixth effect concentrating and rectifying tower enters the fluoric acid collecting tank through the sixth fluoric acid condenser.

[0019] Furthermore, the heater of the fourth-effect concentrating and rectifying tower is connected to the sixth-effect concentrating and rectifying tower through a pipeline assembly, so that the fluoric acid evaporated from the fourth-effect concentrating and rectifying tower can heat the sixth-effect concentrating and rectifying tower, and the heater of the seventh-effect concentrating and rectifying tower is connected to the fifth-effect concentrating and rectifying tower through a pipeline assembly, so that the fluoric acid evaporated from the seventh-effect concentrating and rectifying tower can heat the fifth-effect concentrating and rectifying tower.

[0020] Furthermore, the hydrofluoric acid separated from the top of the fifth effect concentrating and rectifying tower passes through the fifth hydrofluoric acid condenser and enters the hydrofluoric acid collecting tank; the hydrofluoric acid separated from the top of the sixth effect concentrating and rectifying tower passes through the sixth hydrofluoric acid condenser and enters the hydrofluoric acid collecting tank.

[0021] On the other hand, the present invention also discloses a method for treating fluorine-containing mixed acid, which is implemented based on a treatment system for fluorine-containing mixed acid and comprises the following steps:

[0022] S1. Preheating the fluorine-containing mixed acid solution;

[0023] S2, the preheated fluorine-containing mixed acid is subjected to multi-effect concentration and rectification, and the mixed acid at the bottom of the front-effect concentration and rectification tower overflows into the rear-effect concentration and rectification to separate fluoric acid and sulfuric acid;

[0024] S3. Cooling of fluoric acid and sulfuric acid.

[0025] Furthermore, a method for treating fluorine-containing mixed acid comprises the following steps:

[0026] S1. Preheating the fluorine-containing mixed acid solution;

[0027] S2, the preheated fluorine-containing mixed acid enters the first-effect concentrating and rectifying tower to heat the fluorine-containing mixed acid, and the fluorine acid is separated by the separator at the top of the first-effect concentrating and rectifying tower and enters the heater in the second-effect concentrating and rectifying tower; the mixed acid overflows from the bottom of the first-effect concentrating and rectifying tower and enters the second-effect concentrating and rectifying tower;

[0028] S3, the separator at the top of the second-effect concentrating and rectifying tower separates the fluoric acid, which enters the fluoric acid collection tank after being cooled by the second fluoric acid condenser; the mixed acid overflows from the bottom of the second-effect concentrating and rectifying tower and enters the third-effect concentrating and rectifying tower;

[0029] S4, the separator at the top of the third effect concentrating distillation tower separates the hydrofluoric acid, which enters the hydrofluoric acid collection tank after being cooled by the third hydrofluoric acid condenser; the sulfuric acid overflow at the bottom of the third effect concentrating distillation tower enters the sulfuric acid collection tank

[0030] Furthermore, a method for treating fluorine-containing mixed acid comprises the following steps:

[0031] S1. Preheating the fluorine-containing mixed acid solution;

[0032] S2, the preheated fluorine-containing mixed acid enters the fourth-effect concentrating and rectifying tower to heat the fluorine-containing mixed acid, and the fluorine acid separated by the separator at the top of the fourth-effect concentrating and rectifying tower enters the heater of the sixth-effect concentrating and rectifying tower; the mixed acid overflow at the bottom of the fourth-effect concentrating and rectifying tower enters the fifth-effect concentrating and rectifying tower;

[0033] S3, the separator at the top of the fifth effect concentrating and rectifying tower separates the fluoric acid, which enters the fluoric acid collection tank after being cooled by the fifth condenser; the mixed acid overflow at the bottom of the fifth effect concentrating and rectifying tower enters the sixth effect concentrating and rectifying tower;

[0034] S4, the separator at the top of the sixth effect concentrating and rectifying tower separates the fluoric acid, which enters the fluoric acid collection tank after being cooled by the sixth condenser; the sulfuric acid at the bottom of the sixth effect concentrating and rectifying tower enters the seventh effect concentrating and rectifying tower;

[0035] S5. The separator at the top of the seventh-effect concentrating and distilling tower separates the hydrofluoric acid, which enters the fifth-effect concentrating and distilling tower through the seventh condenser, and enters the hydrofluoric acid collecting tank after being cooled by the fifth condenser; the mixed acid overflow at the bottom of the seventh-effect concentrating and distilling tower enters the sulfuric acid collecting tank.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1) The method for treating fluorine-containing mixed acid provided by the present invention is to recover fluorine acid and sulfuric acid by efficiently separating sulfuric acid from concentrated and rectified fluorine acid, thereby reducing the discharge of fluorine-containing waste acid and recovering fluorine acid products with high added value;

[0038] 2) In the fluorine-containing mixed acid treatment system provided by the present invention, the heater is arranged horizontally in the concentration and distillation tower, and the fluoric acid condenser is arranged vertically, which can prevent the sulfur precipitated by the fluoric acid condensation from clogging the heater and ensure the long-term stable operation of the fluorine-containing mixed acid treatment system;

[0039] 3) The fluorine-containing mixed acid treatment system provided by the present invention controls the sulfuric acid temperature at the outlet of the sulfuric acid condenser to prevent the sulfuric acid cooler from being blocked. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 It is a flow chart of a method for treating a fluorine-containing mixed acid provided in a typical implementation case of the present invention;

[0042] Figure 2 is a flow chart of a method for treating a fluorine-containing mixed acid provided in Example 1 of the present invention;

[0043] Figure 3 is a flow chart of a method for treating a fluorine-containing mixed acid provided in Example 2 of the present invention; DETAILED DESCRIPTION

[0044] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

[0045] On one hand, the present invention discloses a treatment system for fluorine-containing mixed acid, comprising a pipeline assembly, a heater, a separator, a fluoric acid condenser, a fluoric acid collection tank, a sulfuric acid condenser and a sulfuric acid collection tank;

[0046] The pipeline assembly is connected to a multi-effect condensing and rectifying tower, and two adjacent condensing and rectifying towers are connected by a pipeline assembly, and the pipeline assembly includes a pipeline. The mixed acid at the bottom of the condensing and rectifying tower of the first effect overflows into the condensing and rectifying tower of the second effect; a heater is arranged in each condensing and rectifying tower, and the heater is arranged horizontally in the condensing and rectifying tower to prevent the sulfur precipitated during the condensation of fluoric acid from clogging the heater, and to ensure the long-term stable operation of the system.

[0047] The top of each effect concentration and distillation tower is provided with a separator, which can separate fluoric acid from the fluorine-containing mixed acid. The fluoric acid condenser is provided on the pipeline assembly, and the fluoric acid condenser can condense fluoric acid. The fluoric acid condenser is provided vertically, which can prevent the sulfur precipitated by the fluoric acid from clogging the heat exchanger, and can make the fluorine-containing mixed acid treatment system run stably for a long period of time. The fluoric acid passing through the fluoric acid cooler enters the fluoric acid collection tank; the sulfuric acid condenser is provided at the bottom of the last effect concentration and distillation tower; the sulfuric acid passing through the sulfuric acid condenser enters the sulfuric acid collection tank.

[0048] In one implementation case, the multi-effect concentrating distillation tower includes a first-effect concentrating distillation tower, a second-effect concentrating distillation tower and a third-effect concentrating distillation tower, the bottom of the first-effect concentrating distillation tower is connected to the second-effect concentrating distillation tower so that the mixed acid at the bottom of the first-effect concentrating distillation tower overflows into the second-effect concentrating distillation tower; the bottom of the second-effect concentrating distillation tower is connected to the third-effect concentrating distillation tower so that the mixed acid at the bottom of the second-effect concentrating distillation tower overflows into the third-effect concentrating distillation tower.

[0049] On the basis of the above, the fluoric acid condenser includes a second fluoric acid condenser connected to the second effect concentrating distillation tower and a third fluoric acid condenser connected to the third effect concentrating condenser; the fluoric acid separated from the top of the second effect concentrating distillation tower enters the fluoric acid collecting tank through the second fluoric acid condenser; the fluoric acid separated from the top of the third effect concentrating distillation tower enters the fluoric acid collecting tank through the third fluoric acid condenser.

[0050] On the basis of the above, the separator at the top of the first-effect concentrating and distilling tower is connected to the heater in the second-effect concentrating and distilling tower through a pipeline assembly.

[0051] In another embodiment, the multi-effect concentrating and rectifying tower includes a fourth-effect concentrating and rectifying tower, a fifth-effect concentrating and rectifying tower, a sixth-effect concentrating and rectifying tower, and a seventh-effect concentrating and rectifying tower (the fourth-effect concentrating and rectifying tower, the fifth-effect concentrating and rectifying tower, the sixth-effect concentrating and rectifying tower, and the seventh-effect concentrating and rectifying tower mentioned here are named in this way to distinguish them from the first-effect concentrating and rectifying tower, the second-effect concentrating and rectifying tower, and the third-effect concentrating and rectifying tower in the previous embodiment. According to the treatment steps of the fluorine-containing mixed acid, the fluorine-containing mixed acid in this embodiment is sequentially passed through the first-effect concentrating and rectifying tower, the second-effect concentrating and rectifying tower, and the seventh-effect concentrating and rectifying tower. The bottom of the fourth-effect concentrating distillation tower is connected to the fifth-effect concentrating distillation tower, so that the mixed acid at the bottom of the fourth-effect concentrating distillation tower overflows into the fifth-effect concentrating distillation tower; the bottom of the fifth-effect concentrating distillation tower is connected to the sixth-effect concentrating distillation tower, so that the mixed acid at the bottom of the fifth-effect concentrating distillation tower overflows into the sixth-effect concentrating distillation tower; the bottom of the sixth-effect concentrating distillation tower is connected to the seventh-effect concentrating distillation tower, so that the mixed acid at the bottom of the sixth-effect concentrating distillation tower overflows into the seventh-effect concentrating distillation tower.

[0052] On the basis of the above, the fluoric acid condenser includes a fifth fluoric acid condenser connected to the fifth effect concentrating distillation tower and a sixth fluoric acid condenser connected to the sixth effect concentrating distillation tower. The fluoric acid separated from the top of the fifth effect concentrating distillation tower enters the fluoric acid collecting tank through the fifth fluoric acid condenser; the fluoric acid separated from the top of the sixth effect concentrating distillation tower enters the fluoric acid collecting tank through the sixth fluoric acid condenser.

[0053] Specifically, the heater of the fourth-effect concentrating and rectifying tower is connected to the sixth-effect concentrating and rectifying tower through a pipeline assembly, so that the fluoric acid evaporated from the fourth-effect concentrating and rectifying tower heats the sixth-effect concentrating and rectifying tower, and the heater of the seventh-effect concentrating and rectifying tower is connected to the fifth-effect concentrating and rectifying tower through a pipeline assembly, so that the fluoric acid evaporated from the seventh-effect concentrating and rectifying tower heats the fifth-effect concentrating and rectifying tower.

[0054] Specifically, the hydrofluoric acid separated from the top of the fifth effect concentrating and rectifying tower passes through the fifth hydrofluoric acid condenser and enters the hydrofluoric acid collecting tank; the hydrofluoric acid separated from the top of the sixth effect concentrating and rectifying tower passes through the sixth hydrofluoric acid condenser and enters the hydrofluoric acid collecting tank.

[0055] Another aspect of the present invention also discloses a method for treating fluorine-containing mixed acid, which is implemented based on a treatment system for fluorine-containing mixed acid, such as Figure 1 As shown, the following steps are included:

[0056] S1. Preheating the fluorine-containing mixed acid solution, preheating the fluorine-containing mixed acid after absorbing the kiln tail gas from the ambient temperature to 70-98 degrees Celsius; preferably, the heat medium for preheating the fluorine-containing mixed acid comes from the steam condensate flash steam and condensate of the first effect concentrating distillation tower or the fourth effect concentrating distillation tower heater, and concentrated sulfuric acid; more preferably, the refrigerant for cooling the sulfuric acid and fluoric acid is circulating water.

[0057] S2, the preheated fluorine-containing mixed acid is subjected to multi-effect concentration and rectification, and the mixed acid at the bottom of the front-effect concentration and rectification tower overflows into the rear-effect concentration and rectification to separate fluoric acid and sulfuric acid;

[0058] S3, condensing hydrofluoric acid through a hydrofluoric acid condenser, and condensing sulfuric acid through a sulfuric acid condenser, wherein the temperature at the outlet of the hydrofluoric acid condenser is controlled to be greater than 50 degrees Celsius.

[0059] Embodiment 1:

[0060] like Figure 2 As shown, a method for treating fluorine-containing mixed acid comprises the following steps:

[0061] S1. Preheat the fluorine-containing mixed acid by using the steam condensate flash steam and condensate of the heater in the first-effect concentrating distillation tower, and preheat the fluorine-containing mixed acid after the kiln tail gas is absorbed from the ambient temperature to 90°C;

[0062] S2, the preheated fluorine-containing mixed acid enters the first-effect concentrating and rectifying tower to heat the fluorine-containing mixed acid, and the fluorine acid is separated by the separator at the top of the first-effect concentrating and rectifying tower and enters the heater in the second-effect concentrating and rectifying tower; the mixed acid overflows from the bottom of the first-effect concentrating and rectifying tower and enters the second-effect concentrating and rectifying tower;

[0063] S3, the separator at the top of the second-effect concentrating and rectifying tower separates the fluoric acid, which enters the fluoric acid collection tank after being cooled by the second fluoric acid condenser; the mixed acid overflows from the bottom of the second-effect concentrating and rectifying tower and enters the third-effect concentrating and rectifying tower;

[0064] S4, the separator at the top of the third effect concentrating distillation tower separates the fluoric acid, which enters the fluoric acid collecting tank after being cooled by the third fluoric acid condenser; the sulfuric acid temperature at the outlet of the sulfuric acid condenser is controlled at 52°C, the sulfuric acid overflow at the bottom of the third effect concentrating distillation tower enters the sulfuric acid collecting tank, the sulfuric acid concentration in the mixed acid in the sulfuric acid collecting tank is 67.8%, and after the sulfuric acid is efficiently separated at the top of the first effect concentrating distillation tower, the second effect concentrating distillation tower and the third effect concentrating distillation tower, the fluoric acid concentration is 13.1%, and the sulfuric acid concentration is 0.023%.

[0065] Embodiment 2:

[0066] like Figure 3 As shown, a method for treating fluorine-containing mixed acid comprises the following steps:

[0067] S1. Preheat the fluorine-containing mixed acid by using the steam condensate flash steam and condensate of the heater in the fourth effect concentration distillation tower, and preheat the fluorine-containing mixed acid after the kiln tail gas is absorbed from the ambient temperature to 96°C;

[0068] S2, the preheated fluorine-containing mixed acid enters the fourth-effect concentrating and rectifying tower to heat the fluorine-containing mixed acid, and the fluorine acid separated by the separator at the top of the fourth-effect concentrating and rectifying tower enters the heater of the sixth-effect concentrating and rectifying tower; the mixed acid overflow at the bottom of the fourth-effect concentrating and rectifying tower enters the fifth-effect concentrating and rectifying tower;

[0069] S3, the separator at the top of the fifth effect concentrating and rectifying tower separates the fluoric acid, which enters the fluoric acid collection tank after being cooled by the fifth condenser; the mixed acid overflow at the bottom of the fifth effect concentrating and rectifying tower enters the sixth effect concentrating and rectifying tower;

[0070] S4, the separator at the top of the sixth effect concentrating and rectifying tower separates the fluoric acid, which enters the fluoric acid collection tank after being cooled by the sixth condenser; the sulfuric acid at the bottom of the sixth effect concentrating and rectifying tower enters the seventh effect concentrating and rectifying tower;

[0071] S5, the separator at the top of the seventh effect concentrating and rectifying tower separates the fluoric acid, which enters the fifth effect concentrating and rectifying tower through the seventh condenser, and enters the fluoric acid collection tank after being cooled by the fifth condenser; the mixed acid overflow at the bottom of the seventh effect concentrating and rectifying tower enters the sulfuric acid collection tank, and the concentration of sulfuric acid in the sulfuric acid collection tank in this embodiment is 68.9%. In this implementation case, after separation by the fourth effect concentrating and rectifying tower, the fifth effect concentrating and rectifying tower, the sixth effect concentrating and rectifying tower and the seventh effect concentrating and rectifying tower, the concentration of fluoric acid in the fluoric acid collection tank is 12.91%, and the concentration of sulfuric acid in the sulfuric acid collection tank is less than 0.01%.

[0072] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A fluorine-containing mixed acid treatment system, characterized in that: include A pipeline assembly is connected to a multi-effect concentrating and rectifying tower, and two adjacent concentrating and rectifying towers are connected by the pipeline assembly, and the mixed acid at the bottom of the preceding concentrating and rectifying tower overflows into the subsequent concentrating and rectifying tower. A heater is provided in each effect of the concentration and distillation tower, and the heater is horizontally arranged in the concentration and distillation tower; A separator is provided at the top of each effective concentration and distillation tower; A fluoric acid condenser is provided on a pipeline assembly and is arranged vertically. Fluoric acid collection tank: the fluoric acid passing through the fluoric acid cooler enters the fluoric acid collection tank; A sulfuric acid condenser, wherein the sulfuric acid condenser is arranged at the bottom of the last effect concentration and rectification tower; Sulfuric acid collecting tank: the sulfuric acid passing through the sulfuric acid condenser enters the sulfuric acid collecting tank.

2. A fluorine-containing mixed acid treatment system according to claim 1, characterized in that: The multi-effect concentrating and rectifying tower comprises a first-effect concentrating and rectifying tower, a second-effect concentrating and rectifying tower and a third-effect concentrating and rectifying tower. The bottom of the first-effect concentrating and rectifying tower is connected to the second-effect concentrating and rectifying tower so that the mixed acid at the bottom of the first-effect concentrating and rectifying tower overflows into the second-effect concentrating and rectifying tower; the bottom of the second-effect concentrating and rectifying tower is connected to the third-effect concentrating and rectifying tower so that the mixed acid at the bottom of the second-effect concentrating and rectifying tower overflows into the third-effect concentrating and rectifying tower.

3. A fluorine-containing mixed acid treatment system according to claim 1, characterized in that: The fluoric acid condenser comprises a second fluoric acid condenser connected to the second effect concentrating and rectifying tower and a third fluoric acid condenser connected to the third effect concentrating and rectifying tower; the fluoric acid separated from the top of the second effect concentrating and rectifying tower enters the fluoric acid collecting tank through the second fluoric acid condenser; The hydrofluoric acid separated from the top of the third-effect concentrating distillation tower enters the hydrofluoric acid collecting tank through the third hydrofluoric acid condenser.

4. A fluorine-containing mixed acid treatment system according to claim 3, characterized in that: The separator at the top of the first-effect concentrating and rectifying tower is connected to the heater in the second-effect concentrating and rectifying tower through a pipeline assembly.

5. A fluorine-containing mixed acid treatment system according to claim 1, characterized in that: The multi-effect concentrating and rectifying tower comprises a fourth-effect concentrating and rectifying tower, a fifth-effect concentrating and rectifying tower, a sixth-effect concentrating and rectifying tower and a seventh-effect concentrating and rectifying tower. The bottom of the fourth-effect concentrating and rectifying tower is connected with the fifth-effect concentrating and rectifying tower so that the mixed acid at the bottom of the fourth-effect concentrating and rectifying tower overflows into the fifth-effect concentrating and rectifying tower; the bottom of the fifth-effect concentrating and rectifying tower is connected with the sixth-effect concentrating and rectifying tower so that the mixed acid at the bottom of the fifth-effect concentrating and rectifying tower overflows into the sixth-effect concentrating and rectifying tower; the bottom of the sixth-effect concentrating and rectifying tower is connected with the seventh-effect concentrating and rectifying tower so that the mixed acid at the bottom of the sixth-effect concentrating and rectifying tower overflows into the seventh-effect concentrating and rectifying tower.

6. A fluorine-containing mixed acid treatment system according to claim 5, characterized in that: The fluoric acid condenser comprises a fifth fluoric acid condenser connected to the fifth effect concentrating and rectifying tower and a sixth fluoric acid condenser connected to the sixth effect concentrating and rectifying tower. The fluoric acid separated from the top of the fifth effect concentrating and rectifying tower enters the fluoric acid collecting tank through the fifth fluoric acid condenser; the fluoric acid separated from the top of the sixth effect concentrating and rectifying tower enters the fluoric acid collecting tank through the sixth fluoric acid condenser; The heater of the fourth-effect concentrating and rectifying tower is connected to the sixth-effect concentrating and rectifying tower through a pipeline assembly, so that the fluoric acid evaporated from the fourth-effect concentrating and rectifying tower heats the sixth-effect concentrating and rectifying tower, and the heater of the seventh-effect concentrating and rectifying tower is connected to the fifth-effect concentrating and rectifying tower through a pipeline assembly, so that the fluoric acid evaporated from the seventh-effect concentrating and rectifying tower heats the fifth-effect concentrating and rectifying tower; The hydrofluoric acid separated from the top of the fifth effect concentrating and rectifying tower passes through the fifth hydrofluoric acid condenser and enters the hydrofluoric acid collecting tank; the hydrofluoric acid separated from the top of the sixth effect concentrating and rectifying tower passes through the sixth hydrofluoric acid condenser and enters the hydrofluoric acid collecting tank.

7. A method for treating a fluorinated mixed acid, implemented based on the fluorinated mixed acid treatment system according to any one of claims 1 to 6, characterized in that: The steps include: S1. Preheating the fluorine-containing mixed acid solution; S2, the preheated fluorine-containing mixed acid is subjected to multi-effect concentration and rectification, and the mixed acid at the bottom of the front-effect concentration and rectification tower overflows into the rear-effect concentration and rectification to separate fluoric acid and sulfuric acid; S3. Cooling of fluoric acid and sulfuric acid.

8. The method for treating fluorine-containing mixed acid according to claim 1, characterized in that: The heat medium for preheating the fluorine-containing mixed acid solution comes from the steam of the first effect condensing distillation tower or the fourth effect condensing distillation tower; the fluorine-containing mixed acid solution is preheated to 70 to 98 degrees Celsius in S1.

9. The method for treating fluorine-containing mixed acid according to claim 8, characterized in that: The steps include: S1. Preheating the fluorine-containing mixed acid solution; S2, the preheated fluorine-containing mixed acid enters the first-effect concentrating and rectifying tower to heat the fluorine-containing mixed acid, and the fluorine acid is separated by the separator at the top of the first-effect concentrating and rectifying tower and enters the heater in the second-effect concentrating and rectifying tower; the mixed acid overflows from the bottom of the first-effect concentrating and rectifying tower and enters the second-effect concentrating and rectifying tower; S3, the separator at the top of the second-effect concentrating and rectifying tower separates the fluoric acid, which enters the fluoric acid collection tank after being cooled by the second fluoric acid condenser; the mixed acid overflows from the bottom of the second-effect concentrating and rectifying tower and enters the third-effect concentrating and rectifying tower; S4, the separator at the top of the third effect concentrating distillation tower separates the hydrofluoric acid, which is cooled by the third hydrofluoric acid condenser and then enters the hydrofluoric acid collection tank; The sulfuric acid overflows from the bottom of the third-effect concentrating distillation tower into the sulfuric acid collection tank.

10. The method for treating fluorine-containing mixed acid according to claim 8, characterized in that: The steps include: S1. Preheating the fluorine-containing mixed acid solution; S2, the preheated fluorine-containing mixed acid enters the fourth-effect concentrating and rectifying tower to heat the fluorine-containing mixed acid, and the fluorine acid separated by the separator at the top of the fourth-effect concentrating and rectifying tower enters the heater of the sixth-effect concentrating and rectifying tower; the mixed acid overflow at the bottom of the fourth-effect concentrating and rectifying tower enters the fifth-effect concentrating and rectifying tower; S3, the separator at the top of the fifth effect concentrating distillation tower separates the hydrofluoric acid, which enters the hydrofluoric acid collection tank after being cooled by the fifth condenser; The mixed acid at the bottom of the fifth effect concentrating and rectifying tower overflows into the sixth effect concentrating and rectifying tower; S4, the separator at the top of the sixth effect concentrating distillation tower separates the hydrofluoric acid, which enters the hydrofluoric acid collection tank after being cooled by the sixth condenser; The sulfuric acid at the bottom of the sixth-effect concentrating and rectifying tower enters the seventh-effect concentrating and rectifying tower; S5, the separator at the top of the seventh effect concentrating and rectifying tower separates the hydrofluoric acid, which enters the fifth effect concentrating and rectifying tower through the seventh condenser, and enters the hydrofluoric acid collection tank after being cooled by the fifth condenser; The mixed acid at the bottom of the seventh-effect concentrating and rectifying tower overflows into the sulfuric acid collecting tank.

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