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

Abstract

The device comprises a magnetic flocculation reactor, a centrifugal separator is arranged on one side of the magnetic flocculation reactor, a reaction kettle is arranged on one side of the centrifugal separator, and a spiral cleaning machine is arranged on one side of the reaction kettle, and is characterized in that a first driving motor is arranged at the bottom of the centrifugal separator; a driving fulcrum shaft is installed at the output end of the upper surface of the first driving motor, a drum body is arranged in the middle of one side of the outer surface of the driving fulcrum shaft, a plurality of inner cone layers are installed in the drum body, and outer cone layers are arranged on the top of the outer surface of the driving fulcrum shaft side by side. Through cooperation of the first driving motor, the driving fulcrum shaft, the inner cone layer, the outer cone layer and the hydraulic telescopic rod, the taper of the rotary drum body can be dynamically adjusted according to the viscosity of waste liquid, and the solid-liquid separation efficiency is remarkably improved in combination with the spiral flow guide edges on the inner wall.

Description

Technical Field

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

[0002] In the field of chemical production, n-butyllithium, as a key organolithium reagent, is widely used in various synthesis reactions. However, the lithium salt contained in the waste liquid generated after its use has special physical and chemical properties and recovery limitations: This lithium salt is not a product and barely meets the industrial-grade recycling material standard. Moreover, there is a small amount of metallic lithium (a highly dangerous substance that is extremely prone to spontaneous combustion when exposed to air) in the material system before hydrolysis. At the same time, it has strong hygroscopicity, is prone to absorbing moisture and caking when encountering water vapor, and due to containing chloride ions, it shows strong corrosiveness in a water-containing environment, especially causing irreparable corrosion damage to the stainless steel 304 material. Therefore, existing hydrolysis equipment usually uses a carbon steel reaction kettle or a carbon glass reaction kettle to avoid the risk of material failure.

[0003] Currently, the common lithium salt recovery process generally stirs and extracts the lithium salt with an organic solvent, forms a lithium aqueous solution and the upper organic phase after adding water dropwise for hydrolysis. After stratification, the lower lithium water is used for recovery, and the upper organic solvent is dehydrated and recycled. However, in the subsequent refining process, when the existing device uses a conventional spiral ultrafiltration membrane or nanofiltration membrane to treat the lithium salt solution, it faces multiple technical bottlenecks: on the one hand, the residual organic polymers and colloidal particles in the waste liquid are easily formed into an irreversible pollution layer on the membrane surface, resulting in a significant decrease in the membrane flux by 30% - 50%, and it is necessary to frequently perform chemical cleaning, which not only increases the cost of reagent consumption, but also causes lithium salt loss due to the pH value fluctuation during the cleaning process; on the other hand, the corrosive components and complex impurity system contained in the above lithium salt material further exacerbate the membrane pollution and equipment loss, and finally the purity of the recovered lithium salt can only reach the battery-grade standard, unable to meet the strict requirements of lithium salt for impurity content and purity. Therefore, for the efficient recovery and high-purity refining of lithium salt from n-butyllithium waste liquid, it is urgent to develop a new process and device that adapts to its special physical and chemical properties and overcomes the problems of membrane pollution and corrosion. Summary of the Invention

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

[0005] To achieve the above object, the present invention adopts the following technical solutions: An apparatus and a recovery method for recovering lithium salts from n-butyllithium waste liquid, including a magnetic flocculation reactor, a centrifugal separator is arranged on one side of the magnetic flocculation reactor, a reaction kettle is arranged on one side of the centrifugal separator, and a spiral cleaner is arranged on one side of the reaction kettle. It is characterized in that: a first driving motor is arranged at the bottom of the centrifugal separator, a driving support shaft is installed at the output end on the upper surface of the first driving motor, a drum main body is arranged in the middle on one side of the outer surface of the driving support shaft, a plurality of inner conical layers are installed inside the drum main body, and an outer conical layer is arranged side by side at the top of the outer surface of the driving support shaft. Hydraulic telescopic rods are installed on the bottom ends of the inner walls of the centrifugal separator and connected to a plurality of inner conical layers, and one side of the bottom end of the inner wall of the centrifugal separator extends into the reaction kettle and is fixedly installed with a first connecting pipe;

[0006] One side of the bottom of the reaction kettle extends to one side of the spiral cleaner and is fixedly installed with a second connecting pipe. A spiral flow channel is opened through the inside of the spiral cleaner. A liquid inlet is arranged on one side of the spiral flow channel, and a liquid outlet is arranged on the other side of the spiral flow channel. A plurality of hollow fiber membrane bundles are fixedly connected to the inner bottom of the spiral flow channel. A high-frequency ultrasonic transducer is fixedly installed on the outer surface of the spiral cleaner near the lower part of the hollow fiber membrane bundle. Differential pressure sensors are arranged at both ends of the spiral flow channel near the hollow fiber membrane bundle.

[0007] Preferably, a reaction kettle inlet is fixedly installed at the top of one side of the reaction kettle near the first connecting pipe. A second driving motor is arranged in the middle of the top of the reaction kettle. The output end of the lower bottom surface of the second driving motor extends into the reaction kettle and is installed with a support rotating shaft. A spiral guide plate is fixedly installed on the outer surface of the support rotating shaft in the reaction kettle.

[0008] Preferably, a guide frame is fixedly installed on one side edge of the magnetic flocculation reactor. The bottom end of the guide frame extends to the upper surface of the centrifugal separator and is fixedly connected with a third connecting pipe.

[0009] Preferably, an independent liquid inlet pipe is arranged on one side of the upper surface of the spiral cleaner near the liquid outlet, a return pipe is arranged on one side of the spiral cleaner near the lower part of the liquid inlet, and one end of the return pipe is connected to a dissolution kettle.

[0010] Preferably, a pressure sensor is installed on the outer surface of the first connecting pipe near the bottom of the centrifugal separator, and a pneumatic valve is installed in the middle of the top end of the pressure sensor.

[0011] Preferably, a turbidity sensor is arranged in the middle on one side of the outer surface of the first connecting pipe.

[0012] Preferably, a spiral guide edge is opened on one side of the inner wall of the drum main body. On the outer surface of the inner conical layer near the inner wall of the drum main body, the drum main body and the inner conical layer are mutually embedded.

[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 an independent liquid inlet pipe and a 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 processes.

[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. By the collaborative work of the hollow fiber membrane bundle, high-frequency ultrasonic transducers, and spiral flow channels inside the spiral cleaning machine, when the differential pressure sensor detects membrane fouling, ultrasonic vibration combined with rotational shear flow can efficiently strip the pollutants on the membrane surface, extend the membrane fouling cycle to 3 times that of traditional components, from 4 hours to 12 hours, reduce the chemical cleaning frequency by 60%, ensure the efficient and stable operation of membrane separation, and further increase the purity of lithium salts to over 99.99%, far exceeding the battery-grade standard of traditional processes.

[0021] 3. Driven by the second drive motor, the spiral guide plate inside the reaction kettle strengthens the contact reaction with the waste liquid, enabling the more complete conversion of organolithium into a lithium carbonate suspension and 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, form a part of this application, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

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

[0024] Figure 2 is a schematic diagram of the internal structure of the centrifuge separator in the present invention;

[0025] Figure 3 is a schematic diagram of the internal structure of the reaction kettle in the present invention;

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

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

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

[0029] Figure 7 is a schematic flow chart of the recovery method in the present invention.

[0030] Sequence numbers in the figure: 1. Magnetic flocculation reactor; 2. Centrifugal separator; 3. Reaction kettle; 4. Screw cleaner; 5. First driving motor; 6. Driving support shaft; 7. Drum body; 8. Outer cone layer; 9. Inner cone layer; 10. Hydraulic telescopic rod; 11. First connecting pipe; 12. Pressure sensor; 13. Pneumatic valve; 14. Turbidity sensor; 15. Reaction kettle inlet; 16. Second driving motor; 17. Support rotating shaft; 18. Screw guide plate; 19. Second connecting pipe; 20. Screw flow channel; 21. Liquid inlet; 22. Liquid outlet; 23. Hollow fiber membrane bundle; 24. High-frequency ultrasonic transducer; 25. Differential pressure sensor; 26. Independent liquid inlet pipe; 27. Return pipe; 28. Flow guide frame; 29. Third connecting pipe. Specific implementation mode

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

[0032] Embodiment: Refer to Figures 1-7 , a device and a recovery method for recovering lithium salts from n-butyllithium waste liquid, including a magnetic flocculation reactor 1, a centrifugal separator 2 is arranged on one side of the magnetic flocculation reactor 1, a reaction kettle 3 is arranged on one side of the centrifugal separator 2, and a screw cleaner 4 is arranged on one side of the reaction kettle 3. It is characterized in that: a first driving motor 5 is arranged 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 first driving motor 5, a drum body 7 is arranged in the middle of the outer surface of one side of the driving support shaft 6, a plurality of inner cone layers 9 are installed inside the drum body 7, an outer cone layer 8 is arranged side by side at the top of the outer surface of the driving support shaft 6, a hydraulic telescopic rod 10 is installed on the inner wall bottom end of the centrifugal separator 2 and connected to a plurality of inner cone layers 9, and the bottom end of one side of the inner wall of the centrifugal separator 2 extends into the reaction kettle 3 and is fixedly installed with a first connecting pipe 11;

[0033] The bottom end of one side of the reaction kettle 3 extends to one side of the screw cleaner 4 and is fixedly installed with a second connecting pipe 19. A screw flow channel 20 is opened through the inside of the screw cleaner 4. A liquid inlet 21 is arranged on one side of the screw flow channel 20, a liquid outlet 22 is arranged on the other side of the screw flow channel 20, a plurality of hollow fiber membrane bundles 23 are fixedly connected to the inner bottom of the screw flow channel 20, a high-frequency ultrasonic transducer 24 is fixedly installed on the outer surface of the screw cleaner 4 near the lower part of the hollow fiber membrane bundle 23, and differential pressure sensors 25 are arranged at the front and rear ends of the screw flow channel 20 near the hollow fiber membrane bundle 23.

[0034] In the present invention, a reactor inlet 15 is fixedly installed near the first connecting pipe 11 at the top of one side of the reactor 3. A second driving motor 16 is arranged in the middle of the top end of the reactor 3. The output end of the lower bottom surface of the second driving motor 16 extends into the reactor 3 and is installed with a support rotating shaft 17. A spiral guide plate 18 is fixedly installed on the outer surface of the support rotating shaft 17 in the reactor 3.

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

[0036] In the present invention, an independent liquid inlet pipe 26 is arranged on one side of the upper surface of the spiral cleaning machine 4 near the liquid outlet 22. A reflux pipe 27 is arranged on one side of the spiral cleaning machine 4 near the lower part of the liquid inlet 21. One end of the reflux pipe 27 is connected with a dissolution kettle.

[0037] In the present invention, a pressure sensor 12 is installed on the outer surface of the first connecting pipe 11 near the bottom of the centrifugal separator 2. The middle part of the top end of the pressure sensor 12 is installed with a pneumatic valve 13.

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

[0039] In the present invention, a spiral diversion edge is arranged on one side of the inner wall of the drum body 7. On one side of the outer surface of the inner conical layer 9 near the inner wall of the drum body 7, the drum body 7 and the inner conical layer 9 are mutually embedded.

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

[0041] S1. Pretreatment for impurity removal: The n-butyllithium waste liquid first enters the magnetic flocculation reactor, and microspheres are added to remove metal impurities, and then enter the centrifugal separator through the diversion frame and the third connecting pipe. The centrifugal separator drives the driving support shaft through the first driving 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 diversion edge on the inner wall of the drum body assists in solid-liquid separation. The pressure sensor and the 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 clear liquid enters the reactor through the first connecting pipe, and a gas is introduced through the reactor inlet, and contacts the waste liquid countercurrently at 60 - 80 °C, and the gas-liquid ratio is 1:5 - 1:10. Then, gas protection is added, and the reactor is completely sealed. The second driving motor drives the support rotating shaft and the spiral guide plate to rotate, and at the same time, an organic solvent is used for stirring and transfer to convert the organolithium into a lithium carbonate suspension.

[0043] ​​​S3. Spiral flow channel membrane refining: The lithium carbonate suspension enters the spiral flow channel of the spiral cleaner through the second connecting pipe from the liquid inlet. The hollow fiber membrane bundle performs membrane separation to achieve the interception of nanoscale impurities with a cut-off particle size of ≤5 nm, and the membrane permeate flows towards the liquid outlet.

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

[0045] Working principle: In this embodiment, the present invention also proposes a usage method of a device and a recovery method for recovering lithium salts from n-butyllithium waste liquid, including the following steps:

[0046] Step 1, by introducing the waste liquid into the magnetic flocculation reactor 1, The microspheres adsorb metal impurities, and then enter the centrifuge 2 through the guide frame 28 and the third connecting pipe 29. In the centrifuge 2, the first driving motor 5 drives the driving support shaft 6 to rotate. According to the viscosity of the waste liquid, the hydraulic telescopic rod 10 adjusts the taper of the drum body 7, that is, the relative position of the inner cone layer 9 and the outer cone layer 8. The spiral guide ribs on the inner wall of the drum body 7 promote the separation of solid particles and liquid in the waste liquid. The pressure sensor 12 monitors the pressure, the pneumatic valve 13 controls the discharging, and the turbidity sensor 14 monitors the turbidity of the filtrate in real time to ensure the solid-liquid separation effect;

[0047] Step 2, making the centrifuged clear liquid enter the reaction kettle 3 through the first connecting pipe 11, and introducing gas from the reaction kettle inlet 15, at 60 - 80 °C, and then adding gas protection, and completely sealing the reaction kettle. The second driving motor 16 drives the support rotating shaft 17 and the spiral guide plate 18 to rotate, and at the same time uses an organic solvent to stir and transfer, so that fully contacts with the waste liquid, and the organolithium is converted into a lithium carbonate suspension;

[0048] Step 3, introducing the lithium carbonate suspension into the spiral flow channel 20 of the spiral cleaner 4 through the second connecting pipe 19 from the liquid inlet 21. The hollow fiber membrane bundle 23 performs membrane separation on the suspension, intercepting nanoscale impurities, and the membrane permeate flows towards the liquid outlet 22;

[0049] Step 4: The differential pressure sensor 25 is used to monitor the differential pressure at the inlet and outlet of the membrane module in real time. When ΔP≥0.1MPa, the high-frequency ultrasonic transducer 24 starts to vibrate, and cooperates with the rotational shear flow generated by the spiral flow channel 20 to make the pollutants on the membrane surface fall off. The organic solvent flows back to the coagulation tank of the pretreatment unit through the independent liquid inlet pipe 26 and the reflux pipe 27, realizing the cyclic treatment of pollutants 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 lithium salt is obtained through processes such as evaporation and crystallization.

[0050] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. An apparatus for recovering lithium salts from n-butyllithium waste liquid, comprising a magnetic flocculation reactor (1), a centrifugal separator (2) is arranged on one side of the magnetic flocculation reactor (1), a reaction kettle (3) is arranged on one side of the centrifugal separator (2), and a spiral cleaner (4) is arranged on one side of the reaction kettle (3), characterized in that: A first driving motor (5) is arranged at the bottom of the centrifugal separator (2). An output end of the upper surface of the first driving motor (5) is provided with a driving support shaft (6). A drum main body (7) is arranged in the middle of one side of the outer surface of the driving support shaft (6). A plurality of inner conical layers (9) are arranged inside the drum main body (7). An outer conical layer (8) is arranged side by side at the top of the outer surface of the driving support shaft (6). Hydraulic telescopic rods (10) are connected to the bottom ends of the inner walls of the centrifugal separator (2) and are arranged on the plurality of inner conical layers (9). A first connecting pipe (11) is fixedly arranged at the bottom of one side of the inner wall of the centrifugal separator (2) and extends to the inside of the reaction kettle (3). One side of the bottom of the reaction kettle (3) extends to one side of the spiral cleaning machine (4) and is fixedly provided with a second connecting pipe (19). A spiral flow channel (20) is opened through the inside of the spiral cleaning machine (4). A liquid inlet (21) is arranged on one side of the spiral flow channel (20). A liquid outlet (22) is arranged on the other side of the spiral flow channel (20). A plurality of hollow fiber membrane bundles (23) are fixedly connected to the inner bottom of the spiral flow channel (20). A high-frequency ultrasonic transducer (24) is fixedly arranged on the outer surface of the spiral cleaning machine (4). Pressure difference sensors (25) are arranged at the front and rear ends of the spiral flow channel (20) close to the hollow fiber membrane bundles (23).

2. The device for recovering lithium salts from n-butyllithium waste liquid according to claim 1, wherein: A reaction kettle inlet (15) is fixedly arranged at one side of the top of the reaction kettle (3) close to the first connecting pipe (11). A second driving motor (16) is arranged in the middle of the top end of the reaction kettle (3). An output end of the lower bottom surface of the second driving motor (16) extends to the inside of the reaction kettle (3) and is provided with a support rotating shaft (17). A spiral guide plate (18) is fixedly arranged on the outer surface of the support rotating shaft (17) inside the reaction kettle (3).

3. The device for recovering lithium salts from n-butyllithium waste liquid according to claim 1, wherein: A flow guide frame (28) is fixedly arranged on one side edge of the magnetic flocculation reactor (1). The bottom end of the flow guide frame (28) extends to the upper surface of the centrifugal separator (2) and is fixedly connected with a third 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 arranged on one side of the upper surface of the spiral cleaning machine (4) close to the liquid outlet (22). A return pipe (27) is arranged on one side of the spiral cleaning machine (4) below the liquid inlet (21). One end of the return pipe (27) is connected to a dissolution kettle.

5. The device for recovering lithium salts from n-butyllithium waste liquid according to claim 1, wherein: A pressure sensor (12) is arranged on the outer surface of the first connecting pipe (11) close to the bottom of the centrifugal separator (2). A pneumatic valve (13) is arranged 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 arranged in the middle of one side of the outer surface of the first 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 edge is arranged on one side of the inner wall of the drum main body (7). On one side of the outer surface of the inner conical layer (9) close to the inner wall of the drum main body (7), the drum main body (7) and the inner conical layer (9) are mutually embedded.

8. A recovery method for recovering lithium salts from n-butyllithium waste liquid, characterized in that: The steps of the recovery method are as follows: S1. Pretreatment for impurity removal: The n-butyllithium waste liquid first enters the magnetic flocculation reactor, and microspheres are added to remove metal impurities. Then, it enters the centrifuge separator through the guide frame and the No. 3 connecting pipe. According to the viscosity of the waste liquid, the centrifuge separator drives the drive support shaft through the No. 1 drive motor, 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 the 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 reaction kettle through the first connecting pipe, and gas is introduced from the reaction kettle inlet. It contacts the waste liquid countercurrently at 60 - 80 °C, with a gas-liquid ratio of 1:5 - 1:

10. Then gas protection is added, and the reaction kettle is completely sealed. The second drive motor drives the support rotating shaft and the spiral guide plate to rotate, and at the same time, an organic solvent is used for stirring and transfer to convert organolithium into a lithium carbonate suspension; S3. Refining by the spiral flow channel membrane: The lithium carbonate suspension enters the spiral flow channel of the spiral cleaning machine from the liquid inlet through the second connecting pipe. The hollow fiber membrane bundle performs membrane separation to intercept nano-scale impurities, and the interception particle size is ≤5 nm. The membrane permeate flows towards the liquid outlet. S4. Self-cleaning: When the differential pressure sensor detects that the differential pressure ΔP between the inlet and outlet of the membrane module is ≥ 0.1 MPa, the control system automatically starts the vibration of the high-frequency ultrasonic transducer with a power of 50 - 100 W. Combining with the rotational shear flow generated by the spiral flow channel with a flow velocity of 2 - 3 m / s, the pollutants on the membrane surface are shed under the synergistic effect of acoustic cavitation and fluid scouring. The organic solvent flows back to the coagulation tank of the pretreatment unit through the independent liquid inlet pipe and the reflux pipe, realizing the cyclic treatment of pollutants. Finally, a high-purity lithium salt solution is obtained from the liquid outlet, and then lithium salts are obtained through subsequent processes such as evaporation and crystallization.

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