Industrial waste salt treatment system

Abstract

The utility model discloses an industrial waste salt treatment system which comprises a microwave pyrolysis unit which is used for pyrolyzing organic matters in industrial waste salt and is provided with a tail gas outlet and a discharge hole; the tail gas treatment unit is connected to the tail gas outlet and is used for treating and discharging the tail gas; the salt dissolving, impurity removing and degassing unit comprises a salt dissolving pond, one end of the salt dissolving pond is connected with the discharging port, the other end of the salt dissolving pond is connected with an impurity removing device, and the salt dissolving pond is connected with a degassing device; the lithium recovery unit is used for lithium precipitation reaction and is connected with the impurity removal device; the membrane separation unit comprises a hardness removal softening device and a nanofiltration separation membrane device which are connected in sequence, the nanofiltration separation membrane device comprises a produced water outlet and a concentrated water outlet, the produced water outlet is connected with a sodium chloride generation module, the concentrated water outlet is connected with a sodium sulfate generation module, and the hardness removal softening device is connected with the lithium recovery unit. According to the utility model, harmless and resourceful treatment on the industrial waste salt generated in the lithium battery recycling process is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of recycling, and particularly relates to an industrial waste salt treatment system. Background Art

[0002] Industrial waste salt generally contains various inorganic salts and toxic complex organic substances, and cannot be directly recycled as industrial raw materials. In the process of lithium battery recycling, the salt solution remaining after the recovery of lithium carbonate and lithium hydroxide enters the MVR evaporation crystallizer. The industrial waste salt enriched in the evaporation mother liquor produced after evaporation and crystallization has complex components, including not only sodium sulfate, sodium chloride, and a small amount of impurities, but also high-content organic substances and concentrated lithium salts. The main components of this industrial waste salt are inorganic salts such as chlorides and sulfates. If this industrial waste salt can be treated to make the purity of the product salt reach the purity standard of industrial raw materials and the harmful substances such as organic substances in the industrial waste salt can be removed, then the resource utilization of this industrial waste salt can be realized. This not only solves the problems of the harm of industrial waste salt to the ecological environment and storage problems, but also can reasonably utilize it to achieve sustainable development and bring economic benefits to enterprises. However, the current industrial waste salt treatment systems have problems such as a relatively single type of waste salt to be disposed of, inability to specifically treat multiple types of waste salts, and the organic matter removal effect not meeting the resource utilization requirements. Content of the Utility Model

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. For this purpose, the utility model provides an industrial waste salt treatment system, which can recover the lithium resources in the industrial waste salt generated in the process of lithium battery recycling, and can separate out single crystal sodium sulfate and single crystal sodium chloride salts, realizing the harmless and resource utilization of industrial waste salt.

[0004] An industrial waste salt treatment system according to an embodiment of the first aspect of the utility model includes: a microwave pyrolysis unit for pyrolyzing the organic matter in the industrial waste salt and having a tail gas outlet and a discharge port; a tail gas treatment unit connected to the tail gas outlet and discharging the tail gas after treatment; a salt dissolution, impurity removal and degassing unit including a salt dissolution tank, one end of the salt dissolution tank is connected to the discharge port, the other end is connected to an impurity removal device, and a degassing device is connected to the salt dissolution tank; a lithium recovery unit for lithium precipitation reaction and connected to the impurity removal device; a membrane separation unit including a hardness removal and softening device and a nanofiltration separation membrane device connected in sequence. The nanofiltration separation membrane device includes a product water outlet and a concentrated water outlet. The product water outlet is connected to a sodium chloride generation module, and the concentrated water outlet is connected to a sodium sulfate generation module. The hardness removal and softening device is connected to the lithium recovery unit.

[0005] According to some embodiments of the present utility model, the microwave pyrolysis unit includes a feeding device, a microwave treatment device, and a discharging machine connected in sequence. The tail gas outlet is arranged on the microwave treatment device, and the discharging port is arranged on the discharging machine.

[0006] According to some embodiments of the present utility model, the microwave treatment device includes a microwave pyrolysis furnace. An air conveying device is connected to one end of the microwave pyrolysis furnace away from the discharging machine. A first stirring device is arranged on the microwave pyrolysis furnace. A microwave processor is arranged at the bottom of the microwave pyrolysis furnace, and a microwave magnetron is arranged inside the microwave processor.

[0007] According to some embodiments of the present utility model, the tail gas treatment unit includes a VOCs treatment device, a gas desulfurization, denitrification, and deacidification device, a dust removal device, and a ventilation device connected in sequence. The VOCs treatment device is connected to the microwave treatment device, and the tail gas is discharged through the ventilation device.

[0008] According to some embodiments of the present utility model, an on-line tail gas detector is further arranged on the tail gas treatment unit, and the on-line tail gas detector is arranged between the dust removal device and the ventilation device.

[0009] According to some embodiments of the present utility model, the impurity removal device includes an impurity removal tank, a first filter press, and a first liquid storage tank connected in sequence. A second stirring device is arranged on the impurity removal tank. The impurity removal tank is connected to the salt dissolving tank. The impurity removal device further includes a first filtering device. One end of the first filtering device is connected to the first liquid storage tank, and the other end of the first filtering device is connected to the lithium recovery unit. A first reflux pipe is arranged between the impurity removal tank and the salt dissolving tank, and a first reflux pump is arranged on the first reflux pipe. A second reflux pipe is arranged between the first liquid storage tank and the impurity removal tank, and a second reflux pump is arranged on the second reflux pipe.

[0010] According to some embodiments of the present utility model, the lithium recovery unit includes a lithium precipitation reaction device and a second filtering device. The lithium precipitation reaction device includes a lithium precipitation reaction tank, a second filter press, and a second liquid storage tank connected in sequence. A third stirring device is arranged on the lithium precipitation reaction tank. A third reflux pipe is arranged between the second liquid storage tank and the lithium precipitation reaction tank, and a third reflux pump is arranged on the third reflux pipe. The lithium precipitation reaction tank is connected to the salt dissolving, impurity removal, and degassing unit. One end of the second filtering device is connected to the second liquid storage tank, and the other end of the second filtering device is connected to the hardening removal and softening device.

[0011] According to some embodiments of the present utility model, the sodium chloride generation module includes a nanofiltration product water tank and a reverse osmosis device connected in sequence. The nanofiltration product water tank is connected to the product water outlet of the nanofiltration separation membrane device. The reverse osmosis device is provided with a concentrated water outlet and a fresh water outlet. A reverse osmosis fresh water tank is connected to the fresh water outlet of the reverse osmosis device, and a reverse osmosis concentrated water tank is connected to the concentrated water outlet of the reverse osmosis device. A sodium chloride crystallizer is connected to the reverse osmosis concentrated water tank.

[0012] According to some embodiments of the present utility model, the sodium sulfate generation module includes a nanofiltration concentrated water tank and a sodium sulfate crystallizer connected to each other. The nanofiltration concentrated water tank is connected to the concentrated water outlet of the nanofiltration separation membrane device.

[0013] According to some embodiments of the present utility model, the hard removal and softening device includes a chemical softening tank, a clear water tank, a multi-media filter, an ultrafilter and a third liquid storage tank connected in sequence. The chemical softening tank is connected to the lithium recovery unit, and the third liquid storage tank is connected to the nanofiltration separation membrane device.

[0014] An industrial waste salt treatment system according to an embodiment of the present utility model has at least the following technical effects: This industrial waste salt treatment system can recover the lithium resources in the industrial waste salt generated during the lithium battery recycling process, and can separate out sodium sulfate single crystal salt and sodium chloride single crystal salt. There is no waste generated during the separation process, and the quality and purity of the refined salt are improved. There is no secondary waste salt generated, and there is no burden on the environment, realizing the harmless and resourceful treatment of industrial waste salt. Description of the Drawings

[0015] The above and / or additional aspects and advantages of the present utility model will become apparent and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0016] Figure 1 is a schematic diagram of the whole of the embodiment of the present utility model;

[0017] Figure 2 is a schematic diagram of the microwave pyrolysis unit and the tail gas treatment unit of the embodiment of the present utility model;

[0018] Figure 3 is a schematic diagram of the salt dissolution impurity removal and degassing unit, the lithium recovery unit and the membrane separation unit of the embodiment of the present utility model.

[0019] Reference Numerals:

[0020] 100. Microwave pyrolysis unit; 101. Feeding device; 101a. Belt conveyor; 101b. Feed hopper; 102. Microwave treatment device; 102a. Microwave pyrolysis furnace; 102b. Air conveying device; 102c. First stirring device; 102d. Microwave processor; 103. Discharger

[0021] 200. Tail gas treatment unit; 201. VOCs treatment device; 202. Gas desulfurization, denitrification and deacidification device; 203. Dust removal device; 204. Exhaust device; 205. Tail gas on-line detector;

[0022] 300. Salt dissolution impurity removal and degassing unit; 301. Salt dissolution tank; 302. Impurity removal device; 302a. Impurity removal tank; 302b. First filter press; 302c. First liquid storage tank; 303. First filtration device; 304. Degassing device; 305. Front-end MVR condensate tank; 306. Second stirring device; 307. First reflux pipe; 308. First reflux pump; 309. Second reflux pipe; 310. Second reflux pump;

[0023] 400. Lithium recovery unit; 401. Lithium precipitation reaction device; 401a. Lithium precipitation reaction tank; 401b. Second filter press; 401c. Second liquid storage tank; 402. Second filtration device; 403. Third stirring device; 404. Third reflux pipe; 405. Third reflux pump;

[0024] 500. Membrane separation unit; 501. Hardness removal and softening device; 501a. Chemical softening tank; 501b. Clear water tank; 501c. Multi-media filter; 501d. Ultrafilter; 501e. Third liquid storage tank; 502. Nanofiltration separation membrane device; 503. Nanofiltration product water tank; 504. Reverse osmosis device; 505. Reverse osmosis concentrated water tank; 506. Sodium chloride crystallizer; 507. Nanofiltration concentrated water tank; 508. Sodium sulfate crystallizer; 509. Reverse osmosis fresh water tank. Detailed implementation manners

[0025] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0026] In the description of the present invention, it should be understood that the orientation or positional relationship involved, such as up, down, front, back, left, right, etc., indicates the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0027] In the description of the present utility model, the meaning of "a number of" is one or more, the meaning of "a plurality of" is more than two, and understandings such as "greater than", "less than", "exceeding", etc. do not include the corresponding number, while understandings such as "above", "below", "within", etc. include the corresponding number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features or implicitly specifying the sequence relationship of the indicated technical features.

[0028] In the description of the present utility model, unless otherwise clearly defined, words such as "arrangement", "installation", "connection", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present utility model in combination with the specific content of the technical solution.

[0029] The following refers to Figures 1 to 3 Describe an industrial waste salt treatment system according to an embodiment of the present utility model.

[0030] As Figure 1 shown, an industrial waste salt treatment system according to an embodiment of the present utility model includes a microwave pyrolysis unit 100, a tail gas treatment unit 200, a molten salt impurity removal and degassing unit 300, a lithium recovery unit 400 and a membrane separation unit 500. As Figure 2 and Figure 3As shown, the microwave pyrolysis unit 100 is used to pyrolyze the organic matter in industrial waste salt and has a tail gas outlet and a discharge port; the tail gas treatment unit 200 is connected to the tail gas outlet and discharges the tail gas after treatment; the molten salt impurity removal and degassing unit 300 includes a molten salt pool 301, one end of the molten salt pool 301 is connected to the discharge port, the other end is connected to an impurity removal device 302, and a degassing device 304 is connected to the molten salt pool 301. The molten salt impurity removal and degassing unit 300 is used to dissolve, degas and remove impurities from the material processed by the microwave pyrolysis unit 100; the lithium recovery unit 400 is used for lithium precipitation reaction and is connected to the impurity removal device 302; the membrane separation unit 500 includes a hardness removal and softening device 501 and a nanofiltration separation membrane device 502 connected in sequence. The nanofiltration separation membrane device 502 includes a water production outlet and a concentrated water outlet. The water production outlet is connected to a sodium chloride generation module, and the concentrated water outlet is connected to a sodium sulfate generation module. The hardness removal and softening device 501 is connected to the lithium recovery unit 400. The membrane separation unit 500 is used to separate sodium chloride and sodium sulfate. When this industrial waste salt treatment system treats industrial waste salt, the industrial waste salt undergoes a pyrolysis reaction through the microwave pyrolysis unit 100, and the organic matter in the industrial waste salt is decomposed into carbon powder, volatile small molecule organic matter, nitrogen oxides, sulfides, hydrogen chloride, etc. The tail gas of the microwave pyrolysis enters the tail gas treatment unit 200 through the tail gas outlet and is discharged up to standard after being treated by the tail gas treatment unit 200. The industrial waste salt after the microwave pyrolysis unit 100 enters the molten salt impurity removal and degassing unit 300 through the discharge port. High-temperature hot water is added to the molten salt pool 301 and stirred to dissolve, obtaining a salt-containing solution. After undergoing a degassing and impurity removal process, it enters the lithium recovery unit 400. The water output from the molten salt impurity removal and degassing unit 300 enters the lithium recovery unit 400, reagents are added and reacted for a period of time to precipitate and recover lithium compounds. After filtration, a mixed salt solution is obtained. The water output from the lithium recovery unit 400 enters the membrane separation unit 500, passes through the hardness removal and softening device 501, and the water output enters the nanofiltration separation membrane device 502. The concentrated water enters the sodium sulfate generation module to produce solid sodium sulfate, and the water production enters the sodium chloride generation module to produce sodium chloride products.

[0031] In some specific embodiments of the present invention, the microwave pyrolysis unit 100 includes a feeding device 101, a microwave treatment device 102 and a discharging machine 103 connected in sequence. The tail gas outlet is arranged on the microwave treatment device 102, and the discharge port is arranged on the discharging machine 103. The feeding device 101 transports the industrial waste salt into the microwave treatment device 102 for pyrolysis treatment. The generated tail gas enters the tail gas treatment unit 200 through the tail gas outlet on the microwave treatment device 102, and the remaining waste materials enter the molten salt pool 301 through the discharge port of the discharging machine 103.

[0032] In some specific embodiments of the present utility model, the feeding device 101 includes a conveyor belt conveyor 101a, and a feeding hopper 101b is provided at one end of the conveyor belt conveyor 101a. After the industrial waste salt is put into the feeding hopper 101b, it is conveyed by the conveyor belt conveyor 101a to the microwave treatment device 102 for treatment.

[0033] In some specific embodiments of the present utility model, the microwave treatment device 102 includes a microwave pyrolysis furnace 102a. An air conveying device 102b is connected and provided at one end of the microwave pyrolysis furnace 102a away from the discharging machine 103. A first stirring device 102c is provided on the microwave pyrolysis furnace 102a. A microwave processor 102d is provided at the bottom of the microwave pyrolysis furnace 102a, and a microwave magnetron is provided inside the microwave processor 102d. A material conveyor, a low-temperature pyrolysis zone, a medium-temperature pyrolysis zone, a high-temperature pyrolysis zone, and air inlets and outlets are provided inside the microwave pyrolysis furnace 102a. The conveyor belt conveyor 101a conveys the industrial waste salt into the microwave pyrolysis furnace 102a. The microwave pyrolysis furnace 102a starts stirring and passes in air. The industrial waste salt sequentially passes through the low-temperature, medium-temperature, and high-temperature pyrolysis zones, and the frequency of the microwave processor 102d is sequentially increased to degrade organic substances.

[0034] In some specific embodiments of the present utility model, the low-temperature, medium-temperature, and high-temperature pyrolysis zones are Figure 2 separated by dotted lines and arranged in sequence from left to right, and are respectively provided with a first stirring device 102c.

[0035] In some specific embodiments of the present utility model, the tail gas treatment unit 200 includes a VOCs treatment device 201, a gas desulfurization, denitrification, and deacidification device 202, a dust removal device 203, and an air extraction device 204 that are connected in sequence. The VOCs treatment device 201 is connected to the microwave treatment device 102, and the tail gas is discharged through the air extraction device 204. Substances such as carbon powder, volatile small molecule organic substances, nitrogen oxides, sulfides, and hydrogen chloride generated during the pyrolysis process of the microwave treatment device 102 pass through the tail gas VOCs treatment device 201, the gas desulfurization, denitrification, and deacidification device 202, the dust removal device 203, and the air extraction device 204, and are discharged up to standard after being fully combusted, denitrified, and deacidified.

[0036] In some specific embodiments of the present utility model, an on-line tail gas detector 205 is further provided on the tail gas treatment unit 200. The on-line tail gas detector 205 is arranged between the dust removal device 203 and the air extraction device 204. After being treated by the VOCs treatment device 201, the treated tail gas VOCs is not higher than 16 ppm. After being detected and qualified by the on-line tail gas detector 205, it is finally discharged through the air extraction device.

[0037] In some specific embodiments of the present utility model, the dust removal device 203 is a bag filter, and the air extraction device 204 is a first blower. The bag filter can better intercept dust.

[0038] In some specific embodiments of the present utility model, the VOCs treatment device 201 is one of an RTO device, an RCO device, and a secondary combustion chamber device.

[0039] In some specific embodiments of the present utility model, a front-end MVR condensate tank 305 is connected to the molten salt tank 301. During the front-end lithium battery recycling process, the salt solution remaining after the recovery of lithium carbonate and lithium hydroxide enters the front-end MVR evaporation crystallizer, and the high-temperature hot water generated in the front-end MVR condensate tank 305 is used to dissolve the waste salt in the molten salt tank 301.

[0040] In some specific embodiments of the present utility model, hot water can also be directly added to the molten salt tank 301 to replace the high-temperature hot water generated in the front-end MVR condensate tank 305.

[0041] In some specific embodiments of the present utility model, the impurity removal device 302 includes an impurity removal tank 302a, a first filter press 302b, and a first liquid storage tank 302c connected in sequence. A second stirring device 306 is provided on the impurity removal tank 302a. The impurity removal tank 302a is connected to the molten salt tank 301. The impurity removal device 302 further includes a first filtering device 303. The first filtering device 303 is a precision filter. One end of the first filtering device 303 is connected to the first liquid storage tank 302c, and the other end of the first filtering device 303 is connected to the lithium recovery unit 400. A first return pipe 307 is provided between the impurity removal tank 302a and the molten salt tank 301, and a first return pump 308 is provided on the first return pipe 307. A second return pipe 309 is provided between the first liquid storage tank 302c and the impurity removal tank 302a, and a second return pump 310 is provided on the second return pipe 309. The waste material enters the molten salt tank 301 through the discharge port of the discharging machine 103 to obtain a salt solution. The salt solution is processed by the degassing device 304 to obtain a degassed salt solution. The degassed salt solution enters the impurity removal tank 302a. A pH detector is provided in the impurity removal tank 302a. A strong alkaline agent of sodium is added to the degassed salt solution to adjust the pH to remove impurities such as iron and aluminum in the salt solution. Then, it is roughly filtered by the first filter press 302b, and the obtained filtrate enters the first liquid storage tank 302c. Finally, it enters the lithium recovery unit 400 after being precisely filtered by the first filtering device 303. At the same time, through the judgment of the detection data, if the iron and aluminum content in the salt solution in the impurity removal tank 302a is too high, the salt solution in the impurity removal tank 302a can be refluxed to the molten salt tank 301 through the first return pipe 307 and the first return pump 308 for repeated dissolution. Through the judgment of the detection data, if the iron and aluminum ion content in the filtrate in the first liquid storage tank 302c is too high, the filtrate in the first liquid storage tank 302c can be refluxed to the impurity removal tank 302a through the second return pipe 309 and the second return pump 310 for repeated impurity removal.

[0042] In some specific embodiments of the present utility model, the degassing device 304 includes a second blower. The degassing device 304 is used to blow air into the salt dissolution tank 301 to remove gases such as dissolved carbon dioxide and ammonia in the salt solution.

[0043] In some specific embodiments of the present utility model, the lithium recovery unit 400 includes a lithium precipitation reaction device 401 and a second filtering device 402. The second filtering device 402 is a precision filter. The lithium precipitation reaction device 401 includes a lithium precipitation reaction tank 401a, a second filter press 401b, and a second liquid storage tank 401c connected in sequence. A third stirring device 403 is provided on the lithium precipitation reaction tank 401a. A third return pipe 404 is provided between the second liquid storage tank 401c and the lithium precipitation reaction tank 401a, and a third return pump 405 is provided on the third return pipe 404. The lithium precipitation reaction tank 401a is connected to the salt dissolution, impurity removal, and degassing unit 300, specifically connected to the first filtering device 303. One end of the second filtering device 402 is connected to the second liquid storage tank 401c, and the other end of the second filtering device 402 is connected to the hardness removal and softening device 501. The filtrate of the salt dissolution, impurity removal, and degassing unit 300 is transported to the lithium precipitation reaction tank 401a through a pipeline, and sodium carbonate is added to recover lithium. After being filtered by the second filter press 401b, lithium carbonate is retained on the filter mesh inside the second filter press 401b. The lithium carbonate on the filter mesh can be taken out by opening the disassembly plate of the second filter press 401b. The filtrate flowing out of the second filter press 401b passes through the second liquid storage tank 401c and the second filtering device 402 in sequence to reach the membrane separation unit 500. Lithium carbonate can be sold as a product on the market. In addition, if it is determined by detecting data that the lithium ion content in the filtrate in the second liquid storage tank 401c is too high, the filtrate in the second liquid storage tank 401c can be refluxed into the lithium precipitation reaction tank 401a through the third return pipe 404 and the third return pump 405 to repeat the lithium precipitation process.

[0044] In some specific embodiments of the present utility model, the sodium chloride generation module includes a nanofiltration product water tank 503 and a reverse osmosis device 504 connected in sequence. The nanofiltration product water tank 503 is connected to the water production outlet of the nanofiltration separation membrane device 502. The reverse osmosis device 504 is provided with a concentrated water outlet and a fresh water outlet. A reverse osmosis fresh water tank 509 is connected to the fresh water outlet of the reverse osmosis device 504, and a reverse osmosis concentrated water tank 505 is connected to the concentrated water outlet of the reverse osmosis device 504. A sodium chloride crystallizer 506 is connected to the reverse osmosis concentrated water tank 505. The water produced by the nanofiltration separation membrane device 502 enters the nanofiltration product water tank 503, and then undergoes reverse osmosis treatment by the reverse osmosis device 504. The concentrated water generated during the reverse osmosis treatment enters the reverse osmosis concentrated water tank 505, and then undergoes treatment by the sodium chloride crystallizer 506 to obtain sodium chloride crystals.

[0045] In some specific embodiments of the present utility model, the sodium sulfate generation module includes a nanofiltration concentrated water tank 507 and a sodium sulfate crystallizer 508 which are connected. The nanofiltration concentrated water tank 507 is connected to the concentrated water outlet of the nanofiltration separation membrane device 502. The concentrated water generated during the separation process of the nanofiltration separation membrane device 502 enters the nanofiltration concentrated water tank 507 and then is processed by the sodium sulfate crystallizer 508 to obtain sodium sulfate crystals.

[0046] In some specific embodiments of the present utility model, the hardness removal and softening device 501 includes a chemical softening tank 501a, a clear water tank 501b, a multi-media filter 501c, an ultrafilter 501d, and a third liquid storage tank 501e which are connected in sequence. The chemical softening tank 501a is connected to the lithium recovery unit 400, specifically connected to the second filtration device 402. The third liquid storage tank 501e is connected to the nanofiltration separation membrane device 502. The water outlet of the third liquid storage tank 501e is connected to the water inlet of the nanofiltration separation membrane device 502 through a pipeline. The water inlet and the water production outlet of the nanofiltration separation membrane device 502 are located at both ends of the membrane, and the concentrated water outlet is on the side of the membrane. The water production outlet of the nanofiltration separation membrane device 502 is connected to the water inlet of the nanofiltration water production tank 503 through a pipeline; the concentrated water outlet of the nanofiltration separation membrane device 502 is connected to the water inlet of the nanofiltration concentrated water tank 507 through a pipeline; the outlet of the nanofiltration concentrated water tank 507 is connected to the water inlet of the sodium sulfate crystallizer 508 through a pipeline. The water outlet of the nanofiltration water production tank 503 is connected to the water inlet of the reverse osmosis device 504 through a pipeline. The fresh water outlet of the reverse osmosis device 504 is connected to the water inlet of the reverse osmosis fresh water tank 509 through a pipeline. The concentrated water outlet of the reverse osmosis device 504 is connected to the water inlet of the reverse osmosis concentrated water tank 505 through a pipeline. The water outlet of the reverse osmosis concentrated water tank 505 is connected to the water inlet of the sodium chloride crystallizer 506 through a pipeline. The filtered water output from the lithium recovery unit 400 enters the hardness removal and softening device 501, which can fully remove the hardness, suspended solids, etc. in the system influent. The filtered filtrate enters the nanofiltration separation membrane device 502 through a pipeline, separating out a sodium sulfate solution and a sodium chloride solution. The sodium sulfate solution is connected to the sodium sulfate crystallizer 508 through a pipeline, and sodium sulfate single crystal salt can be crystallized. The water production of the nanofiltration separation membrane device 502 is a sodium chloride solution, which enters the reverse osmosis device 504 for concentration. The concentrated water after concentration enters the sodium chloride crystallizer 506, and sodium chloride single crystal salt can be obtained. The water production of the reverse osmosis device 504 can be recycled to the front-end battery recycling leaching process. There is no waste generated in the whole process, achieving zero discharge.

[0047] The utility model solves the possibility of waste salt becoming hazardous waste, and at the same time recovers a large amount of lithium resources, realizing the high-value utilization of waste salt. At the same time, the utility model uses microwave pyrolysis technology. Microwave absorption is selective for organic matter, with short heating time, high efficiency, low energy consumption, uniform heating inside and outside the material, and complete removal of organic matter. In addition, the utility model can separate sodium sulfate and sodium chloride, with no waste generated during the separation process, improve the quality and purity of refined salt, no secondary waste salt generated, achieve zero emissions, and greatly utilize the resources of the production line without burdening the environment.

[0048] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0049] Of course, the utility model is not limited to the above-described embodiments. Those skilled in the art can make equivalent deformations or substitutions without departing from the spirit of the utility model. These equivalent deformations or substitutions are all included in the scope defined by the claims of the utility model.

Claims

1. An industrial waste salt treatment system, characterized in that, Comprising: A microwave pyrolysis unit (100) for pyrolyzing organic substances in industrial waste salts and having a tail gas outlet and a discharge port; A tail gas treatment unit (200) connected to the tail gas outlet and discharging the tail gas after treatment; A molten salt impurity removal and degassing unit (300) includes a molten salt tank (301), one end of the molten salt tank (301) is connected to the discharge port, the other end is connected to an impurity removal device (302), and a degassing device (304) is connected to the molten salt tank (301); A lithium recovery unit (400) for lithium precipitation reaction and connected to the impurity removal device (302); A membrane separation unit (500) includes a hardness removal and softening device (501) and a nanofiltration separation membrane device (502) connected in sequence. The nanofiltration separation membrane device (502) includes a water production outlet and a concentrated water outlet. The water production outlet is connected to a sodium chloride generation module, and the concentrated water outlet is connected to a sodium sulfate generation module. The hardness removal and softening device (501) is connected to the lithium recovery unit (400).

2. An industrial waste salt treatment system according to claim 1, characterized in that: The microwave pyrolysis unit (100) includes a feeding device (101), a microwave treatment device (102), and a discharging machine (103) connected in sequence. The tail gas outlet is arranged on the microwave treatment device (102), and the discharge port is arranged on the discharging machine (103).

3. An industrial waste salt treatment system according to claim 2, characterized in that: The microwave treatment device (102) includes a microwave pyrolysis furnace (102a). One end of the microwave pyrolysis furnace (102a) far from the discharging machine (103) is connected with an air conveying device (102b). A first stirring device (102c) is arranged on the microwave pyrolysis furnace (102a). A microwave processor (102d) is arranged at the bottom of the microwave pyrolysis furnace (102a), and a microwave magnetron is arranged in the microwave processor (102d).

4. An industrial waste salt treatment system according to claim 2, characterized in that: The tail gas treatment unit (200) includes a VOCs treatment device (201), a gas desulfurization, denitrification and deacidification device (202), a dust removal device (203), and an air extraction device (204) connected in sequence. The VOCs treatment device (201) is connected to the microwave treatment device (102), and the tail gas is discharged through the air extraction device (204).

5. An industrial waste salt treatment system according to claim 4, characterized in that: A tail gas on-line detector (205) is further arranged on the tail gas treatment unit (200), and the tail gas on-line detector (205) is arranged between the dust removal device (203) and the air extraction device (204).

6. The industrial waste salt treatment system according to claim 1, wherein: The impurity removal device (302) includes an impurity removal tank (302a), a first filter press (302b), and a first liquid storage tank (302c) connected in sequence. A second stirring device (306) is provided on the impurity removal tank (302a). The impurity removal tank (302a) is connected to the salt dissolving tank (301). The impurity removal device (302) further includes a first filtering device (303). One end of the first filtering device (303) is connected to the first liquid storage tank (302c), and the other end of the first filtering device (303) is connected to the lithium recovery unit (400). A first reflux pipe (307) is provided between the impurity removal tank (302a) and the salt dissolving tank (301), and a first reflux pump (308) is provided on the first reflux pipe (307). A second reflux pipe (309) is provided between the first liquid storage tank (302c) and the impurity removal tank (302a), and a second reflux pump (310) is provided on the second reflux pipe (309).

7. An industrial waste salt treatment system according to claim 1, characterized in that: The lithium recovery unit (400) includes a lithium precipitation reaction device (401) and a second filtering device (402). The lithium precipitation reaction device (401) includes a lithium precipitation reaction tank (401a), a second filter press (401b), and a second liquid storage tank (401c) connected in sequence. A third stirring device (403) is provided on the lithium precipitation reaction tank (401a). A third reflux pipe (404) is provided between the second liquid storage tank (401c) and the lithium precipitation reaction tank (401a), and a third reflux pump (405) is provided on the third reflux pipe (404). The lithium precipitation reaction tank (401a) is connected to the salt dissolving, impurity removal, and degassing unit (300). One end of the second filtering device (402) is connected to the second liquid storage tank (401c), and the other end of the second filtering device (402) is connected to the hardness removal and softening device (501).

8. An industrial waste salt treatment system according to claim 1, characterized in that: The sodium chloride generation module includes a nanofiltration product water tank (503) and a reverse osmosis device (504) connected in sequence. The nanofiltration product water tank (503) is connected to the water production outlet of the nanofiltration separation membrane device (502). The reverse osmosis device (504) is provided with a concentrated water outlet and a fresh water outlet. A reverse osmosis fresh water tank (509) is connected to the fresh water outlet of the reverse osmosis device (504), and a reverse osmosis concentrated water tank (505) is connected to the concentrated water outlet of the reverse osmosis device (504). A sodium chloride crystallizer (506) is connected to the reverse osmosis concentrated water tank (505).

9. The industrial waste salt treatment system according to claim 1, wherein: The sodium sulfate generation module includes a nanofiltration concentrated water tank (507) and a sodium sulfate crystallizer (508) connected to each other. The nanofiltration concentrated water tank (507) is connected to the concentrated water outlet of the nanofiltration separation membrane device (502).

10. The industrial waste salt treatment system according to claim 1, characterized in that: The hard removal and softening device (501) includes a chemical softening tank (501a), a clear water tank (501b), a multi-media filter (501c), an ultrafilter (501d), and a third liquid storage tank (501e) that are connected in sequence. The chemical softening tank (501a) is connected to the lithium recovery unit (400), and the third liquid storage tank (501e) is connected to the nanofiltration separation membrane device (502).

Images