Device and method for recovering lithium salt from n-butyllithium waste liquid

Abstract

The invention discloses a device and method for recovering lithium salts from n-butyl lithium waste liquid. The device comprises a magnetic flocculation reactor, a centrifugal separator is provided on one side of the magnetic flocculation reactor, a reactor is provided on one side of the centrifugal separator, and a spiral cleaner is provided on one side of the reactor. The device is characterized in that: a No. 1 driving motor is provided at the bottom of the centrifugal separator, a driving support shaft is provided at the output end of the upper surface of the No. 1 driving motor, a drum body is provided in the middle of one side of the outer surface of the driving support shaft, a plurality of inner conical layers are provided inside the drum body, and outer conical layers are provided in parallel at the top of the outer surface of the driving support shaft. The device comprises a centrifugal separator in the device, which cooperates with the No. 1 driving motor, the driving support shaft, the inner conical layers, the outer conical layers and the hydraulic telescopic rod, so that the taper of the drum body can be dynamically adjusted according to the viscosity of the waste liquid, and the solid-liquid separation efficiency is significantly improved in combination with the spiral guide ridges on the inner wall.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium salt recovery, and in particular to a device and a method for recovering lithium salt from n-butyllithium waste liquid. Background Art

[0002] In the chemical industry, n-butyllithium is a key organic lithium reagent widely used in various synthetic reactions. However, the lithium salts contained in the wastewater produced after its use have unique physical and chemical properties and recycling limitations: this lithium salt is not a finished product and barely meets industrial-grade recycling standards. Furthermore, the material system before hydrolysis contains a small amount of metallic lithium (a highly hazardous substance that is highly flammable when exposed to air). It is also highly hygroscopic and easily absorbs moisture and agglomerates when exposed to water vapor. Furthermore, the presence of chloride ions makes it highly corrosive in aqueous environments, especially to 304 stainless steel, causing irreparable corrosion damage. Therefore, existing hydrolysis equipment typically uses carbon steel or carbon glass reactors to mitigate the risk of material failure.

[0003] Current lithium salt recovery processes generally involve extracting and transferring lithium salts through agitation with an organic solvent. Hydrolysis is then added dropwise to form a lithium-water solution and an upper organic phase. After separation, the lower lithium-water layer is recovered, while the upper organic solvent is dehydrated and recycled. However, in the subsequent purification process, existing devices using conventional spiral-wound ultrafiltration or nanofiltration membranes to treat lithium salt solutions face multiple technical bottlenecks. Firstly, residual organic polymers and colloidal particles in the wastewater easily form an irreversible fouling layer on the membrane surface, resulting in a significant drop in membrane flux by 30%-50%, necessitating frequent chemical cleaning. This not only increases reagent costs but also leads to lithium salt loss due to pH fluctuations during the cleaning process. Secondly, the corrosive components and complex impurity systems contained in these lithium salt materials further exacerbate membrane fouling and equipment wear. Ultimately, the recovered lithium salt purity only meets battery-grade standards, failing to meet the stringent requirements for impurity content and purity. Therefore, for the efficient recovery and high-purity purification of lithium salts from n-butyllithium wastewater, there is an urgent need to develop a new process and device that adapts to its unique physicochemical properties and overcomes membrane fouling and corrosion issues. Summary of the Invention

[0004] In order to solve the problems of easy pollution and insufficient purity of lithium salt in the existing membrane separation process, the present invention provides a device and a method for recovering lithium salt from n-butyllithium waste liquid.

[0005] To achieve the above-mentioned object, the present invention adopts the following technical scheme: a device and method for recovering lithium salts from n-butyl lithium waste liquid, comprising a magnetic flocculation reactor, a centrifugal separator provided on one side of the magnetic flocculation reactor, a reactor provided on one side of the centrifugal separator, and a spiral cleaner provided on one side of the reactor, characterized in that: a No. 1 drive motor is provided at the bottom of the centrifugal separator, a drive support shaft is installed at the output end of the upper surface of the No. 1 drive motor, a drum body is provided in the middle of one side of the outer surface of the drive support shaft, a plurality of inner conical layers are installed inside the drum body, outer conical layers are arranged in parallel at the top of the outer surface of the drive support shaft, a hydraulic telescopic rod is installed on the bottom end of the inner wall of the centrifugal separator connected to the plurality of inner conical layers, and a No. 1 connecting pipe is fixedly installed on the bottom of one side of the inner wall of the centrifugal separator extending into the reactor;

[0006] A No. 2 connecting pipe is fixedly installed on the bottom of one side of the reactor extending to the side of the spiral cleaner. A spiral flow channel is opened inside the spiral cleaner. A liquid inlet is provided on one side of the spiral flow channel, and a liquid outlet is provided on the other side of the spiral flow channel. Several hollow fiber membrane bundles are fixedly connected to the bottom of the spiral flow channel. A high-frequency ultrasonic transducer is fixedly installed on the outer surface of the spiral cleaner near the bottom of the hollow fiber membrane bundle, and differential pressure sensors are provided inside the spiral flow channel near the front and rear ends of the hollow fiber membrane bundle.

[0007] Preferably, a reactor inlet is fixedly installed on the top of one side of the reactor near the No. 1 connecting pipe, and a No. 2 drive motor is provided in the middle of the top of the reactor. The output end of the lower bottom surface of the No. 2 drive motor extends to the interior of the reactor and is equipped with a support shaft, and a spiral guide plate is fixedly installed on the outer surface of the support shaft in the reactor.

[0008] Preferably, a guide frame is fixedly installed on one side of the magnetic flocculation reactor, and the bottom end of the guide frame extends to the upper surface of the centrifugal separator and is fixedly connected to a No. 3 connecting pipe.

[0009] Preferably, an independent liquid inlet pipe is provided on one side of the upper surface of the spiral cleaner near the liquid outlet, a reflux pipe is provided on one side of the spiral cleaner near the bottom of the liquid inlet, and one end of the reflux pipe is connected to the dissolving kettle.

[0010] Preferably, a pressure sensor is installed on the outer surface of the No. 1 connecting pipe near the bottom of the centrifugal separator, and a pneumatic valve is installed in the middle of the top of the pressure sensor.

[0011] Preferably, a turbidity sensor is provided in the middle of one side of the outer surface of the No. 1 connecting pipe.

[0012] Preferably, a spiral guide rib is provided on one side of the inner wall of the drum body, and one side of the outer surface of the inner cone layer is close to the inner wall of the drum body, and the drum body and the inner cone layer are embedded with each other.

[0013] A method for recovering lithium salts from n-butyllithium waste liquid, the steps of the recovery method are:

[0014] S1. Pretreatment and impurity removal: n-butyl lithium waste liquid first enters the magnetic flocculation reactor, and then adds The microspheres remove metal impurities and then enter the centrifuge through the guide frame and the No. 3 connecting pipe. The centrifuge drives the drive shaft through the No. 1 drive motor according to the viscosity of the waste liquid, and cooperates with the hydraulic telescopic rod to adjust the taper of the drum body. The spiral guide ribs on the inner wall of the drum body assist in solid-liquid separation. The pressure sensor and pneumatic valve control the bottom discharge, and the turbidity sensor monitors the turbidity of the filtrate in real time.

[0015] S2, reaction transformation: the centrifuged supernatant enters the reactor through the No. 1 connecting pipe, and is introduced into the reactor from the inlet. The gas is contacted with the waste liquid in countercurrent at 60-80℃, with a gas-liquid ratio of 1:5-1:10, and then added Gas protection is used and the reactor is completely sealed. The No. 2 drive motor drives the supporting shaft and spiral guide plate to rotate. At the same time, an organic solvent is used for stirring and transferring to convert organic lithium into lithium carbonate suspension.

[0016] S3. Spiral flow channel membrane refining: The lithium carbonate suspension enters the spiral flow channel of the spiral cleaning machine from the liquid inlet through the No. 2 connecting pipe. The hollow fiber membrane bundle performs membrane separation to achieve nano-scale impurity retention with a retained particle size of ≤5nm. The membrane permeate flows to the liquid outlet.

[0017] S4. Self-cleaning: When the pressure difference sensor detects that the pressure difference between the inlet and outlet of the membrane assembly ΔP ≥ 0.1MPa, the control system automatically starts the vibration of the high-frequency ultrasonic transducer with a power of 50-100W, and cooperates with the rotating shear flow generated by the spiral flow channel with a flow rate of 2-3m / s, so that the pollutants on the membrane surface fall off under the synergistic effect of acoustic cavitation effect and fluid scouring. The organic solvent returns to the coagulation tank of the pretreatment unit through the independent liquid inlet pipe and reflux pipe to realize the recycling treatment of pollutants. Finally, a high-purity lithium salt solution is obtained from the liquid outlet, and then lithium salt is obtained through subsequent evaporation and crystallization process.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. Through the cooperation of the No. 1 drive motor, drive support shaft, inner cone layer, outer cone layer and hydraulic telescopic rod in the centrifugal separator of the device, the taper of the drum body can be dynamically adjusted according to the viscosity of the waste liquid. Combined with the spiral guide ridges on the inner wall, the solid-liquid separation efficiency is significantly improved. Compared with the traditional fixed cone angle drum, the separation efficiency is increased by more than 35%.

[0020] 2. Through the coordinated work of the hollow fiber membrane bundle, high-frequency ultrasonic transducer and spiral flow channel in the spiral cleaning machine, when the differential pressure sensor detects membrane contamination, ultrasonic vibration is combined with the rotating shear flow to achieve efficient stripping of pollutants on the membrane surface, extending the membrane contamination cycle to three times that of traditional components, from 4 hours to 12 hours, and reducing the chemical cleaning frequency by 60%, ensuring the efficient and stable operation of membrane separation, thereby making the purity of lithium salt reach more than 99.99%, far exceeding the battery-grade standard of traditional processes.

[0021] 3. The spiral guide plate in the reactor is driven by the No. 2 drive motor to strengthen The contact reaction with the waste liquid enables the organic lithium to be more fully converted into a lithium carbonate suspension, thereby improving the reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 Schematic diagram of the internal structure of the centrifugal separator in the present invention;

[0025] Figure 3 Schematic diagram of the internal structure of the reactor in the present invention;

[0026] Figure 4 It is a structural schematic diagram of the spiral cleaning machine in the present invention;

[0027] Figure 5 Schematic diagram of the cross-sectional structure of the spiral flow channel in the present invention;

[0028] Figure 6 Schematic diagram of the structure of the differential pressure sensor in the present invention;

[0029] Figure 7 Schematic diagram of the recovery process of the present invention.

[0030] Serial numbers in the figure: 1. Magnetic flocculation reactor; 2. Centrifugal separator; 3. Reactor; 4. Spiral cleaner; 5. No. 1 drive motor; 6. Drive support shaft; 7. Drum body; 8. Outer cone layer; 9. Inner cone layer; 10. Hydraulic telescopic rod; 11. No. 1 connecting pipe; 12. Pressure sensor; 13. Pneumatic valve; 14. Turbidity sensor; 15. Reactor inlet; 16. No. 2 drive motor; 17. Support shaft; 18. Spiral guide plate; 19. No. 2 connecting pipe; 20. Spiral flow channel; 21. Liquid inlet; 22. Liquid outlet; 23. Hollow fiber membrane bundle; 24. High-frequency ultrasonic transducer; 25. Pressure difference sensor; 26. Independent liquid inlet pipe; 27. Reflux pipe; 28. Guide frame; 29. ​​No. 3 connecting pipe. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0032] Example: See Figure 1-7 , a device and method for recovering lithium salts from n-butyl lithium waste liquid, comprising a magnetic flocculation reactor 1, a centrifuge 2 provided on one side of the magnetic flocculation reactor 1, a reactor 3 provided on one side of the centrifuge 2, and a spiral cleaner 4 provided on one side of the reactor 3, characterized in that: a No. 1 drive motor 5 is provided at the bottom of the centrifuge 2, a drive support shaft 6 is installed at the output end of the upper surface of the No. 1 drive motor 5, a drum body 7 is provided in the middle of one side of the outer surface of the drive support shaft 6, a plurality of inner cone layers 9 are installed inside the drum body 7, an outer cone layer 8 is arranged in parallel on the top of the outer surface of the drive support shaft 6, a hydraulic telescopic rod 10 is installed on the bottom end of the inner wall of the centrifuge 2 connected to the plurality of inner cone layers 9, and a No. 1 connecting pipe 11 is fixedly installed on the bottom of one side of the inner wall of the centrifuge 2 extending to the reactor 3;

[0033] A No. 2 connecting pipe 19 is fixedly installed on the bottom of one side of the reactor 3 and extends to one side of the spiral cleaner 4. A spiral flow channel 20 is opened inside the spiral cleaner 4. A liquid inlet 21 is provided on one side of the spiral flow channel 20, and a liquid outlet 22 is provided on the other side of the spiral flow channel 20. A number of hollow fiber membrane bundles 23 are fixedly connected to the bottom of the spiral flow channel 20. A high-frequency ultrasonic transducer 24 is fixedly installed on the outer surface of the spiral cleaner 4 near the bottom of the hollow fiber membrane bundle 23, and a pressure difference sensor 25 is provided at both ends of the spiral flow channel 20 near the front and rear ends of the hollow fiber membrane bundle 23.

[0034] In the present invention, a reactor inlet 15 is fixedly installed at the top of one side of the reactor 3 near the No. 1 connecting pipe 11, and a No. 2 drive motor 16 is provided in the middle of the top of the reactor 3. The output end of the lower bottom surface of the No. 2 drive motor 16 extends to the inside of the reactor 3 and is equipped with a support shaft 17. The outer surface of the support shaft 17 is fixedly equipped with a spiral guide plate 18 in the reactor 3.

[0035] In the present invention, a guide frame 28 is fixedly installed on one side of the magnetic flocculation reactor 1 , and the bottom end of the guide frame 28 extends to the upper surface of the centrifugal separator 2 and is fixedly connected to a third connecting pipe 29 .

[0036] In the present invention, an independent liquid inlet pipe 26 is provided on one side of the upper surface of the spiral cleaner 4 near the liquid outlet 22, and a reflux pipe 27 is provided on one side of the spiral cleaner 4 near the bottom of the liquid inlet 21, and one end of the reflux pipe 27 is connected to the dissolving kettle.

[0037] In the present invention, a pressure sensor 12 is installed on the outer surface of the No. 1 connecting pipe 11 near the bottom of the centrifugal separator 2 , and a pneumatic valve 13 is installed in the middle of the top of the pressure sensor 12 .

[0038] In the present invention, a turbidity sensor 14 is provided at the middle portion of one side of the outer surface of the first connecting pipe 11 .

[0039] In the present invention, a spiral guide rib is provided on one side of the inner wall of the drum body 7, and the outer surface of the inner cone layer 9 is close to the inner wall of the drum body 7, and the drum body 7 and the inner cone layer 9 are embedded with each other.

[0040] A method for recovering lithium salts from n-butyllithium waste liquid, the steps of the recovery method are:

[0041] S1. Pretreatment and impurity removal: n-butyl lithium waste liquid first enters the magnetic flocculation reactor, and then adds The microspheres remove metal impurities and then enter the centrifuge through the guide frame and the No. 3 connecting pipe. The centrifuge drives the drive shaft through the No. 1 drive motor according to the viscosity of the waste liquid, and cooperates with the hydraulic telescopic rod to adjust the taper of the drum body. The spiral guide ribs on the inner wall of the drum body assist in solid-liquid separation. The pressure sensor and pneumatic valve control the bottom discharge, and the turbidity sensor monitors the turbidity of the filtrate in real time.

[0042] S2, reaction transformation: the centrifuged supernatant enters the reactor through the No. 1 connecting pipe, and is introduced into the reactor from the inlet. The gas is contacted with the waste liquid in countercurrent at 60-80℃, with a gas-liquid ratio of 1:5-1:10, and then added Gas protection is used and the reactor is completely sealed. The No. 2 drive motor drives the supporting shaft and spiral guide plate to rotate. At the same time, an organic solvent is used for stirring and transferring to convert organic lithium into lithium carbonate suspension.

[0043] S3. Spiral flow channel membrane refining: The lithium carbonate suspension enters the spiral flow channel of the spiral cleaning machine from the liquid inlet through the No. 2 connecting pipe. The hollow fiber membrane bundle performs membrane separation to achieve nano-scale impurity retention with a retained particle size of ≤5nm. The membrane permeate flows to the liquid outlet.

[0044] S4. Self-cleaning: When the pressure difference sensor detects that the pressure difference between the inlet and outlet of the membrane assembly ΔP ≥ 0.1MPa, the control system automatically starts the vibration of the high-frequency ultrasonic transducer with a power of 50-100W, and cooperates with the rotating shear flow generated by the spiral flow channel with a flow rate of 2-3m / s, so that the pollutants on the membrane surface fall off under the synergistic effect of acoustic cavitation effect and fluid scouring. The organic solvent returns to the coagulation tank of the pretreatment unit through the independent liquid inlet pipe and reflux pipe to realize the recycling treatment of pollutants. Finally, a high-purity lithium salt solution is obtained from the liquid outlet, and then lithium salt is obtained through subsequent evaporation and crystallization process.

[0045] Working Principle: In this embodiment, the present invention also proposes a device for recovering lithium salts from n-butyl lithium waste liquid and a method for using the recovery method, comprising the following steps:

[0046] Step 1: the waste liquid is fed into the magnetic flocculation reactor 1. The microspheres absorb metal impurities and then enter centrifuge 2 through guide frame 28 and No. 3 connecting pipe 29. In centrifuge 2, No. 1 drive motor 5 rotates drive shaft 6. Hydraulic telescopic rod 10 adjusts the taper of drum body 7, specifically the relative positions of inner cone layer 9 and outer cone layer 8, based on the viscosity of the waste liquid. Spiral guide ridges on the inner wall of drum body 7 separate solid particles from the liquid in the waste liquid. Pressure sensor 12 monitors pressure, pneumatic valve 13 controls discharge, and turbidity sensor 14 monitors filtrate turbidity in real time to ensure effective solid-liquid separation.

[0047] Step 2: The centrifuged supernatant enters the reactor 3 through the No. 1 connecting pipe 11 and is introduced into the reactor from the reactor inlet 15. Gas, at 60-80℃, then add Gas protection, and the reactor is completely sealed, the second drive motor 16 drives the support shaft 17 and the spiral guide plate 18 to rotate, and at the same time, the organic solvent is used to stir and transfer. Fully contact with waste liquid, organic lithium is converted into lithium carbonate suspension;

[0048] Step 3: The lithium carbonate suspension enters the spiral flow channel 20 of the spiral cleaning machine 4 from the liquid inlet 21 through the second connecting pipe 19. The hollow fiber membrane bundle 23 performs membrane separation on the suspension to intercept nano-sized impurities, and the membrane permeate flows to the liquid outlet 22.

[0049] In step 4, the pressure differential between the inlet and outlet of the membrane module is monitored in real time using a pressure differential sensor 25. When ΔP ≥ 0.1 MPa, the high-frequency ultrasonic transducer 24 activates vibration, which, in conjunction with the rotating shear flow generated by the spiral flow channel 20, removes contaminants from the membrane surface. The organic solvent then flows back through the independent liquid inlet pipe 26 and the return pipe 27 to the coagulation tank of the pretreatment unit, achieving a recycling process for the contaminants and ensuring the efficient operation of the membrane module. Finally, a high-purity lithium salt solution is obtained from the liquid outlet 22, and then the lithium salt is obtained through an evaporation and crystallization process.

[0050] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A device for recovering lithium salts from n-butyl lithium waste liquid, comprising a magnetic flocculation reactor (1), a centrifugal separator (2) provided on one side of the magnetic flocculation reactor (1), a reactor (3) provided on one side of the centrifugal separator (2), and a spiral cleaner (4) provided on one side of the reactor (3), characterized in that: A No. 1 driving motor (5) is provided at the bottom of the centrifugal separator (2), a driving support shaft (6) is installed at the output end of the upper surface of the No. 1 driving motor (5), a drum body (7) is provided at the middle of one side of the outer surface of the driving support shaft (6), a plurality of inner cone layers (9) are installed inside the drum body (7), and outer cone layers (8) are arranged in parallel at the top of the outer surface of the driving support shaft (6), a hydraulic telescopic rod (10) is installed on the bottom end of the inner wall of the centrifugal separator (2) connected to the plurality of inner cone layers (9), and a No. 1 connecting pipe (11) is fixedly installed on the bottom of one side of the inner wall of the centrifugal separator (2) extending to the reactor (3); The bottom of one side of the reactor (3) extends to the side of the spiral cleaner (4) where a No. 2 connecting pipe (19) is fixedly installed. A spiral flow channel (20) is provided inside the spiral cleaner (4). A liquid inlet (21) is provided on one side of the spiral flow channel (20), and a liquid outlet (22) is provided on the other side of the spiral flow channel (20). A plurality of hollow fiber membrane bundles (23) are fixedly connected to the bottom of the spiral flow channel (20). A high-frequency ultrasonic transducer (24) is fixedly installed on the outer surface of the spiral cleaner (4). Pressure difference sensors (25) are provided at both ends of the spiral flow channel (20) near the front and rear ends of the hollow fiber membrane bundle (23).

2. The device for recovering lithium salts from n-butyllithium waste liquid according to claim 1, characterized in that: A reactor inlet (15) is fixedly installed at the top of one side of the reactor (3) near the No. 1 connecting pipe (11), and a No. 2 driving motor (16) is provided in the middle of the top of the reactor (3). The output end of the lower bottom surface of the No. 2 driving motor (16) extends to the inside of the reactor (3) and is installed with a supporting shaft (17). The outer surface of the supporting shaft (17) is located in the reactor (3) and is fixedly installed with a spiral guide plate (18).

3. The device for recovering lithium salts from n-butyllithium waste liquid according to claim 1, characterized in that: A guide frame (28) is fixedly mounted on one side of the magnetic flocculation reactor (1), and a bottom end of the guide frame (28) extends to the upper surface of the centrifugal separator (2) and is fixedly connected to a No. 3 connecting pipe (29).

4. The device for recovering lithium salts from n-butyllithium waste liquid according to claim 1, characterized in that: An independent liquid inlet pipe (26) is provided on one side of the upper surface of the spiral cleaner (4) near the liquid outlet (22), and a return pipe (27) is provided on one side of the spiral cleaner (4) near the bottom of the liquid inlet (21), and one end of the return pipe (27) is connected to the dissolving kettle.

5. The device for recovering lithium salts from n-butyllithium waste liquid according to claim 1, characterized in that: A pressure sensor (12) is installed on the outer surface of the No. 1 connecting pipe (11) near the bottom of the centrifugal separator (2), and a pneumatic valve (13) is installed in the middle of the top end of the pressure sensor (12).

6. The device for recovering lithium salts from n-butyllithium waste liquid according to claim 1, characterized in that: A turbidity sensor (14) is provided in the middle of one side of the outer surface of the No. 1 connecting pipe (11).

7. The device for recovering lithium salts from n-butyllithium waste liquid according to claim 1, characterized in that: A spiral guide ridge is provided on one side of the inner wall of the drum body (7), and one side of the outer surface of the inner cone layer (9) is close to the inner wall of the drum body (7). The drum body (7) and the inner cone layer (9) are interlocked.

8. A method for recovering lithium salts from n-butyllithium waste liquid, characterized in that: The steps of the recycling method are: S1. Pretreatment and impurity removal: n-butyl lithium waste liquid first enters the magnetic flocculation reactor, and then adds The microspheres remove metal impurities and then enter the centrifuge through the guide frame and the No. 3 connecting pipe. The centrifuge uses the No. 1 drive motor to drive the drive shaft according to the viscosity of the waste liquid. The hydraulic telescopic rod adjusts the taper of the drum body. The spiral guide ribs on the inner wall of the drum body assist in solid-liquid separation. The pressure sensor and pneumatic valve control the bottom discharge, and the turbidity sensor monitors the turbidity of the filtrate in real time. S2, reaction transformation: the centrifuged supernatant enters the reactor through the No. 1 connecting pipe, and is introduced into the reactor from the inlet. The gas is contacted with the waste liquid in countercurrent at 60-80℃, with a gas-liquid ratio of 1:5-1:10, and then added Gas protection, and the reactor is completely sealed, the No. 2 drive motor drives the support shaft and spiral guide plate to rotate, and at the same time, an organic solvent is used for stirring and transferring to convert the organic lithium into a lithium carbonate suspension; S3, spiral flow channel membrane refining: lithium carbonate suspension enters the spiral flow channel of the spiral cleaning machine from the liquid inlet through the No. 2 connecting pipe, and the hollow fiber membrane bundle performs membrane separation to achieve nano-scale impurity interception, with the interception particle size ≤ 5nm, and the membrane permeate flows to the liquid outlet; S4. Self-cleaning: When the pressure difference sensor detects that the pressure difference between the inlet and outlet of the membrane assembly ΔP ≥ 0.1MPa, the control system automatically starts the vibration of the high-frequency ultrasonic transducer with a power of 50-100W, and cooperates with the rotating shear flow generated by the spiral flow channel with a flow rate of 2-3m / s, so that the pollutants on the membrane surface fall off under the synergistic effect of acoustic cavitation effect and fluid scouring. The organic solvent returns to the coagulation tank of the pretreatment unit through the independent liquid inlet pipe and reflux pipe to realize the recycling treatment of pollutants. Finally, a high-purity lithium salt solution is obtained from the liquid outlet, and then lithium salt is obtained through subsequent evaporation and crystallization process.

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