Electrodialysis device for extracting lithium from salt lake brine

Abstract

The invention discloses an electrodialysis device for extracting lithium from salt lake brine, the electrodialysis device comprises a cation exchange membrane, an electrodialysis partition plate and an anion exchange membrane, the electrodialysis partition plate comprises a fixed frame and a block net, and the block net comprises a plurality of wavy hollow pipelines which are arranged in a cavity hole and are arranged at intervals in a criss-cross manner; a through hole is formed in the side wall of the hollow pipeline and is used for enabling brine to act on the cation exchange membrane and the anion exchange membrane through the hollow pipeline; according to the invention, the wave-shaped structure in the grid net formed by the wave-shaped hollow pipeline can prevent a two-dimensional channel from being completely vertical to the direction of an electric field in the electrodialysis operation process, so that the acting force of the electric field in the channel direction is improved; and the guide pipe is used for guiding brine to enter the hollow pipeline block net to act on each area of the membrane surface, so that the utilization rate of a two-dimensional channel film ion channel is improved, the concentration polarization phenomenon of electrodialysis membrane surface ions is weakened, the lithium extraction efficiency is effectively improved, the electrodialysis energy consumption is reduced, and the application advantage is remarkable.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of membrane separation technology, in particular to an electrodialysis device for lithium extraction from salt lake brine. BACKGROUND

[0002] Two-dimensional channel membrane is a new type of ion separation membrane, which exhibits excellent ion sieving performance due to its sub-nanometer precise two-dimensional channel structure, and has been widely studied in the application of lithium extraction from brine. Electrodialysis membrane separation for lithium extraction is a high-efficiency lithium extraction process that has been industrially applied. However, since most electrodialysis membranes on the market are organic polymer membranes, existing electrodialysis devices are not designed and optimized for two-dimensional channel membranes. The two-dimensional channel direction of the membrane is perpendicular to the electric field force, and the electric field force cannot act on the channel direction, resulting in a significant reduction in the ion separation performance of the two-dimensional electrodialysis membrane.

[0003] Patent CN115770482A proposes an electrodialysis device for lithium extraction from salt lake brine using two-dimensional channel membranes. The device solves the problem of water swelling of two-dimensional electrodialysis membranes by uniformly interlacing the holes of the strip-shaped barrier to compress the electrodialysis membrane. However, the device does not improve the ion transport path of the two-dimensional membrane based on the design. Patent CN115784248A discloses a method of assembling large nanosheets on the end face and stacking them into a two-dimensional membrane, which can effectively reduce the number of through holes in the membrane and improve the ion transport path in the two-dimensional membrane. However, the application device of the membrane is not improved, and the problem of the electric field direction being perpendicular to the channel direction still exists in the actual application process, resulting in low utilization rate of the ion channel of the membrane. In addition, under the action of the electrodialysis electric field, ions will undergo directional transport, but due to the low utilization rate of the ion transport channel, ions are prone to aggregation on the membrane surface, resulting in concentration polarization phenomenon on the membrane surface, which seriously affects the lithium-magnesium separation efficiency of the membrane.

[0004] Therefore, there is an urgent need to develop a new type of electrodialysis brine lithium extraction device that can improve the ion channel utilization rate of two-dimensional membranes and effectively reduce the concentration polarization phenomenon on the membrane surface. SUMMARY

[0005] The purpose of the present application is to provide an electrodialysis device for lithium extraction from salt lake brine, which solves the problem of low two-dimensional channel utilization rate and ion separation performance affected by concentration polarization on the membrane surface during the electrodialysis lithium extraction process of two-dimensional channel membranes.

[0006] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0007] The utility model provides an electrodialysis device for lithium extraction from salt lake brine, comprising a cation exchange membrane, electrodialysis separators arranged on both sides of the cation exchange membrane, and an anion exchange membrane arranged on the electrodialysis separator below the cation exchange membrane, the electrodialysis separator comprises a fixed frame with a chamber hole in the middle and a grid net arranged on the chamber hole, the grid net comprises a plurality of wave-shaped hollow pipes arranged in the chamber hole and spaced longitudinally and transversely, and the hollow pipes have through holes in the side walls and are used for allowing the brine to act on the cation exchange membrane and the anion exchange membrane through the hollow pipes.

[0008] Preferably, the cation exchange membrane is a two-dimensional channel film used for the separation and enrichment of lithium ions and monovalent and divalent ions in salt lake brine; the two-dimensional channel film is composed of two-dimensional nanosheet layers stacked layer by layer, the channels on the two-dimensional channel film have a height of nanometer level or sub-nanometer level; and the anion exchange membrane is an organic polymer film used for ensuring the ion balance of the electrodialysis system.

[0009] Preferably, the utility model further comprises guide pipes arranged in the edge regions of the chamber holes, the guide pipes are used for guiding the brine to enter the hollow pipes from different regions and act on different regions of the cation exchange membrane and the anion exchange membrane.

[0010] Preferably, the fixed frame is circumferentially provided with liquid guide holes and water distribution flow channels in communication with the liquid guide holes and the chamber holes at both ends respectively.

[0011] Preferably, the fixed frame has a length of a mm, a width of b mm, and a thickness of c mm, a > b > c, 2500 mm >= a >= 300 mm, 1800 mm >= b >= 200 mm, and 50 mm >= c >= 5 mm.

[0012] Preferably, the liquid guide holes are one of regular polygons, circles, or ellipses, four liquid guide holes are equally spaced on the upper and lower sides of the fixed frame, when the liquid guide holes are regular polygons, the diameter of the inscribed circle in the liquid guide hole is d mm, when the liquid guide holes are circles, the diameter of the liquid guide hole is d mm, and when the liquid guide holes are ellipses, the major axis of the liquid guide hole is d mm, and d needs to satisfy 0 < d < 1 / 4b.

[0013] Preferably, one side of the water distribution flow channel connected to the liquid guide hole has a length of d mm, one side connected to the chamber hole has a length of e mm, and e needs to satisfy d < e < 1 / 2b; a plurality of water flow grooves are symmetrically arranged on both sides of the water distribution flow channel, and the water distribution flow channels are distributed in the fixed frame in an interlaced manner between the liquid guide holes on both sides.

[0014] Preferably, the wave-shaped hollow pipe is shaped as a wave, wherein the height of the wave crest and the wave trough is m mm, and 0 < m < 1 / 2c is satisfied; the total number of the wave crest and the wave trough is k, k is an even positive number, and k < a / 5.

[0015] Preferably, the mesh of the barrier net is a regular polygon or a circle; the hollow pipe is a cylindrical pipe structure; the diameter of the hollow pipe is n mm, and 0 < n < c is satisfied; the hollow pipe 10 is uniformly provided with four rows of micropores with a diameter of h mm, and 0 < h < n / 2 is satisfied.

[0016] Preferably, the diameter of the guide pipe is n mm, one side of the guide pipe is connected with the inner side of the fixed frame, and the other side is communicated with the wave-shaped hollow pipe barrier net and the water distribution flow channel.

[0017] The present application has the following technical effects relative to the prior art:

[0018] 1. The present application can improve the channel utilization rate of the two-dimensional channel film, improve the transmission probability of ions in the two-dimensional channel, and strengthen the ion separation performance of the film in the lithium electrodialysis device.

[0019] 2. The present application increases the transmission probability of ions on the membrane surface in the two-dimensional channel, effectively improves the ion transmission rate, and the barrier net design of the hollow pipe can make the brine circulate in each area of the membrane surface, weaken the concentration polarization phenomenon caused by the ion aggregation on the membrane surface under the action of the electrodialysis electric field, and improve the ion separation performance of the film.

[0020] 3. The transmission rate of ions in the two-dimensional channel is thousands of times that in the macro fluid, the present application can strengthen the ion transmission in the two-dimensional channel, reduce the energy consumption of increasing the ion transmission power driven by electricity, and in addition, the design of the hollow pipe can make the brine act on each area of the membrane surface faster, which is beneficial to improve the lithium extraction efficiency of the film. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1 is a structural schematic diagram of the present application;

[0023] Figure 2 is a structural schematic diagram of the electrodialysis separator of the present application;

[0024] Figure 3 is a wave-shaped hollow pipe barrier net schematic diagram of the present application;

[0025] Figure 4 The electric field force acting on the two-dimensional channel thin film channel direction of the electrodialysis device provided by the application is different from the electric field force acting on the two-dimensional channel thin film channel direction of the conventional electrodialysis device.

[0026] Figure 5 A schematic diagram of brine penetrating the hollow pipe of the wave-shaped hollow pipe grid provided by the application;

[0027] Figure 6 A structural schematic diagram of the fixed frame of the application;

[0028] Figure 7 A structural schematic diagram of the actual wave-shaped hollow pipe of the application.

[0029] 1, cation exchange membrane; 2, anion exchange membrane; 3, electrodialysis diaphragm; 4, fixed frame; 5, hollow pipe; 6, guide pipe; 7, liquid guide hole; 8, water distribution channel; 9, chamber hole. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0031] The application aims to provide an electrodialysis device for lithium extraction from salt lake brine, so as to solve the problems of low utilization rate of two-dimensional channels and the influence of membrane surface concentration polarization on ion separation performance in the process of lithium extraction from salt lake brine by electrodialysis.

[0032] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to the drawings and specific embodiments.

[0033] Reference Figures 1 to 7The utility model provides a kind of electrodialysis device for lithium extraction of salt lake brine, including cation exchange membrane, the electrodialysis separator of being arranged in the cation exchange membrane both sides and the anion exchange membrane of being arranged on the electrodialysis separator below the cation exchange membrane, the electrodialysis separator includes fixed frame with chamber hole in middle part and the grid net of being arranged on the chamber hole, the grid net includes the wave hollow duct of being arranged in the chamber hole and being longitudinally and transversely staggered interval arrangement multiple, the hollow duct side wall is equipped with through hole and is used to make brine act on the cation exchange membrane and the anion exchange membrane by the hollow duct;The wave hollow duct of the grid net in the utility model can avoid two-dimensional channel and electric field direction complete perpendicular during electrodialysis operation, improve electric field in the force of channel direction, hollow duct is used to penetrate brine, guide pipe is used to guide brine to enter hollow duct grid net and act on each area of membrane surface, improve the utilization of two-dimensional channel thin film ion channel, weaken the concentration difference polarization phenomenon of electrodialysis membrane surface ion, effectively improve lithium extraction efficiency, reduce electrodialysis energy consumption, and the application advantage is remarkable.

[0034] Further, the cation exchange membrane is a two-dimensional channel thin film for separating and enriching lithium ions and monovalent and divalent ions in the salt lake brine;The two-dimensional channel thin film is composed of two-dimensional nanosheet layers stacked one by one, the channel height on the two-dimensional channel thin film is nanoscale or sub-nanoscale;The anion exchange membrane is an organic polymer thin film for ensuring ion balance of the electrodialysis system.

[0035] Further, the working principle of the utility model is that the advantage of the two-dimensional channel thin film lies in that the transmission rate of ions in the two-dimensional channel is thousands of times that of macroscopic fluid. Figure 4 Generally, the electrodialysis thin film is arranged in the electrodialysis device perpendicular to the electric field direction, at this time, the force of the electric field on the two-dimensional channel direction Fchannel1=0( Figure 4 ), the probability of ion transmission through the two-dimensional channel is low, and it is difficult to exert the advantage of high ion transmission rate of the two-dimensional channel thin film. In addition, ions are prone to gather on the membrane surface under the action of the electric field during the electrodialysis process, thereby causing concentration difference polarization phenomenon of the membrane surface and affecting the ion separation efficiency.

[0036] Reference Figure 2 Further comprising a guide tube arranged at the edge area of the chamber hole, the guide tube is used to guide the brine from different areas into the hollow pipe and act on the respective areas of the cation exchange membrane and the anion exchange membrane.

[0037] Reference Figure 2 The fixed frame is provided with a liquid guide hole and a water distribution channel in communication with the liquid guide hole and the chamber hole respectively in the circumferential direction.

[0038] Further, the fixed frame is used to compress the electrodialysis membrane, avoid water leakage and brine cross flow during the operation of the electrodialysis device, the length of the fixed frame is a mm, the width is b mm, and the thickness is c mm, a>b>c, and 2500mm≥a≥300mm, 1800mm≥b≥200mm, 50mm≥c≥5mm;

[0039] Further, the liquid guide hole is one of a regular polygon, a circle or an ellipse, four liquid guide holes are arranged at equal intervals on the upper and lower sides of the fixed frame; when the liquid guide hole is a regular polygon, the diameter of the inscribed circle in the liquid guide hole is d mm; when the liquid guide hole is a circle, the diameter of the liquid guide hole is d mm; when the liquid guide hole is an ellipse, the major axis of the liquid guide hole is d mm, and d needs to satisfy 0<d<1 / 4b.

[0040] Further, the length of one side of the water distribution channel connected to the liquid guide hole is d mm, and the length of one side connected to the chamber hole is e mm, e needs to satisfy d<e<1 / 2b; a plurality of water flow grooves are symmetrically opened on both sides of the water distribution channel, and the water distribution channels are staggered and distributed between the liquid guide holes on both sides of the fixed frame.

[0041] Further, the overall shape of the wave-shaped hollow pipe is wavy, the height of the wave crest and the wave trough is m mm, which needs to satisfy 0<m<1 / 2c; the total number of wave crests and wave troughs is k, k is a positive even number, and k<a / 5.

[0042] Further, the mesh of the blocking net is a regular polygon or a circle; the hollow pipe is a cylindrical pipe structure; the diameter of the hollow pipe is n mm, n needs to satisfy 0<n<c; the hollow pipe 10 is uniformly provided with four rows of micropores with a diameter of h mm, h needs to satisfy 0<h<n / 2.

[0043] Further, the diameter of the guide tube is n mm, one side of the guide tube is connected to the inner side of the fixed frame, and the other side is in communication with the wave-shaped hollow pipe blocking net and the water distribution channel.

[0044] Reference Figures 3 to 4The wave-shaped structure in the wave-shaped hollow-pipe barrier net can make the electrodialysis membrane be wave-shaped and fit the barrier net during the electrodialysis operation process, compared with the traditional flat barrier net, the probability of ions passing through the two-dimensional channel in the two-dimensional channel membrane is increased, the efficiency of the lithium extraction membrane is effectively improved, and the problem that the performance of the two-dimensional channel membrane is reduced due to low channel utilization rate on the electrodialysis device is solved.

[0045] Reference Figure 5 During the operation process of the electrodialysis device, the brine can penetrate through the pipe structure in the hollow-pipe barrier net, so as to effectively act on each area of the membrane, increase the fluidity of ions on the membrane surface, weaken the concentration polarization phenomenon of the electrodialysis membrane during the operation process in the brine, and improve the efficiency of the lithium extraction membrane.

[0046] In the present application, specific examples are applied to illustrate the principles and implementation modes of the present application, and the above examples are only used to help understand the method and core idea of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range can be changed. In conclusion, the content of the present application should not be understood as a limitation of the present application.

Claims

1. An electrodialysis device for lithium extraction from salt lake brine, characterized in that, It includes a cation exchange membrane, electrodialysis partitions arranged on both sides of the cation exchange membrane, and an anion exchange membrane arranged on the electrodialysis partition below the cation exchange membrane. The electrodialysis partition includes a fixed frame with a chamber hole in the middle and a grid net arranged on the chamber hole. The grid net includes a plurality of wavy hollow pipes arranged in a crisscross and spaced manner in the chamber hole. Through holes are formed on the side wall of the hollow pipe and are used to act on the cation exchange membrane and the anion exchange membrane with brine through the hollow pipe.

2. The electrodialysis apparatus for lithium extraction from salt lake brine according to claim 1, characterized in that, The cation exchange membrane is a two-dimensional channel thin film, which is used for the separation and enrichment of lithium ions and divalent and monovalent ions in salt lake brine. The two-dimensional channel thin film is composed of stacked two-dimensional nanosheets, and the channel height on the two-dimensional channel thin film is nanoscale or sub-nanoscale; the anion exchange membrane is an organic polymer thin film, which is used to ensure the ion balance of the electrodialysis system.

3. The electrodialysis apparatus for lithium extraction from salt lake brine according to claim 1, characterized in that, It also includes a guiding pipe arranged in the edge area of the chamber hole. The guiding pipe is used to guide brine to enter the hollow pipe from different areas and act on each area of the cation exchange membrane and the anion exchange membrane.

4. The electrodialysis apparatus for lithium extraction from salt lake brine according to claim 1, characterized in that, Liquid guiding holes are arranged on the circumference of the fixed frame, and a water distribution channel is connected to the liquid guiding hole at both ends and is communicated with the chamber hole.

5. The electrodialysis apparatus for lithium extraction from salt lake brine according to claim 4, characterized in that, The length of the fixed frame is a mm, the width is b mm, and the thickness is c mm, where a > b > c, and 2500mm ≥ a ≥ 300mm, 1800mm ≥ b ≥ 200mm, 50mm ≥ c ≥ 5mm.

6. The electrodialysis apparatus for lithium extraction from salt lake brine according to claim 5, characterized in that, The liquid guiding hole is one of a regular polygon, a circle or an ellipse. Four liquid guiding holes are equally spaced on each of the upper and lower sides of the fixed frame; when the liquid guiding hole is a regular polygon, the diameter of the inscribed circle of the liquid guiding hole is d mm; when the liquid guiding hole is a circle, the diameter of the liquid guiding hole is d mm; when the liquid guiding hole is an ellipse, the long axis of the liquid guiding hole is d mm, and d needs to satisfy 0 < d < 1 / 4b.

7. The electrodialysis apparatus for lithium extraction from salt lake brine according to claim 5, characterized in that, The length of one side of the water distribution channel connected to the liquid guiding hole is d mm, and the length of one side connected to the chamber hole is e mm, and e needs to satisfy d < e < 1 / 2b; a plurality of water flow grooves are symmetrically opened on both sides of the water distribution channel, and the water distribution channels are alternately distributed at intervals of the liquid guiding holes on both sides of the fixed frame.

8. The electrodialysis apparatus for lithium extraction from salt lake brine according to claim 5, characterized in that, The overall shape of the wavy hollow pipe is wavy and curved, and the height of both the wave crest and the wave trough is m mm, which needs to satisfy 0 < m < 1 / 2c; the total number of wave crests and wave troughs is k, k is a positive even number, and k < a / 5.

9. The electrodialysis apparatus for lithium extraction from salt lake brine according to claim 5, characterized in that, The mesh holes of the grid net are regular polygons or circles; the hollow pipe is a cylindrical pipe structure; the diameter of the hollow pipe is n mm, and n needs to satisfy 0 < n < c; the hollow pipe is evenly provided with four rows of micropores with a diameter of h mm, and h needs to satisfy 0 < h < n / 2.

10. The electrodialysis apparatus for lithium extraction from salt lake brine according to claim 9, characterized in that, The diameter of the guiding pipe is n mm. One side of the guiding pipe is connected to the inner side of the fixed frame, and the other side is connected to the grid net of the wavy hollow pipe and the water distribution channel.

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