A lithium extraction system from salt lakes

Abstract

This utility model discloses a lithium extraction system for salt lakes, comprising a magnesium removal module, a boron removal module, and a lithium ion precipitation module connected in sequence. The magnesium removal module includes an ion exchange resin magnesium removal device, a nanofiltration membrane magnesium removal device, and a deep reverse osmosis membrane magnesium removal device connected in sequence, with the permeate outlet of the deep reverse osmosis membrane magnesium removal device connected to the inlet of the boron removal module. The boron removal module includes a nanofiltration boron removal device and a reverse osmosis boron removal device connected in sequence, with the permeate outlet of the reverse osmosis boron removal device connected to the inlet of the lithium ion precipitation module. The lithium ion precipitation module includes an ion exchange resin lithium adsorption device, a MVR device, and a lithium precipitation device connected in sequence. The MVR device further includes an evaporation recovery device, with a portion of the permeate from the MVR device entering the lithium precipitation device through the evaporation recovery device, and the other portion directly entering the lithium precipitation device.

Description

Technical Field

[0001] This utility model relates to the field of lithium extraction technology from salt lake brine, and in particular to a lithium extraction system from salt lakes. Background Technology

[0002] Traditional lithium extraction processes, such as precipitation and solvent extraction, suffer from high reagent consumption, severe pollution, and low lithium recovery rates. In recent years, membrane separation technology has been widely applied in lithium extraction processes due to its advantages such as low energy consumption, no phase change, and good selectivity. However, single-membrane technology struggles to achieve efficient separation of monovalent and divalent ions, especially under high magnesium-to-lithium ratio conditions, where magnesium ion interference severely restricts lithium concentration and purity.

[0003] In existing technologies, my country's salt lakes have a high proportion of magnesium and lithium, and the separation of magnesium and lithium is quite difficult. At the same time, existing salt lake lithium extraction systems still suffer from problems such as low system integration, incomplete impurity removal, high acid and alkali consumption, and difficulties in mother liquor treatment, making it difficult to achieve the goal of economical, environmentally friendly, and sustainable lithium extraction.

[0004] Therefore, there is an urgent need to develop an efficient membrane-coupled lithium extraction system to solve the problem of efficient lithium extraction from salt lake brines with high magnesium-to-lithium ratios. Utility Model Content

[0005] The technical problem to be solved by this utility model embodiment is to provide a lithium extraction system for salt lakes, which can efficiently extract lithium from salt lake brines with a high magnesium-to-lithium ratio.

[0006] To address the aforementioned technical problems, this utility model provides a lithium extraction system from a salt lake, comprising a magnesium removal module, a boron removal module, and a lithium-ion sedimentation module connected in sequence; wherein...

[0007] The magnesium removal module includes an ion exchange resin magnesium removal device, a nanofiltration membrane magnesium removal device, and a deep reverse osmosis membrane magnesium removal device connected in sequence. The product water outlet of the deep reverse osmosis membrane magnesium removal device is connected to the inlet of the boron removal module.

[0008] The boron removal module includes a nanofiltration boron removal device and a reverse osmosis boron removal device connected in sequence, and the product water outlet of the reverse osmosis boron removal device is connected to the inlet of the lithium ion sedimentation module.

[0009] The lithium-ion precipitation module includes an ion exchange resin lithium adsorption device, an MVR device, and a lithium precipitation device connected in sequence. The MVR device further includes an evaporation recovery device. Part of the product water from the MVR device enters the lithium precipitation device through the evaporation recovery device, and the other part enters the lithium precipitation device directly.

[0010] In one feasible implementation, the salt lake lithium extraction system further includes a lithium precipitation mother liquor recovery module, which includes an electrodialysis device connected to the mother liquor outlet of the lithium precipitation device of the lithium ion precipitation module.

[0011] In one feasible implementation, the lithium precipitation mother liquor recovery module further includes a recovery nanofiltration membrane device, the inlet of which is connected to the mother liquor outlet of the lithium precipitation device, the product water outlet of which is connected to the inlet of the MVR device, and the concentrate outlet of which is connected to the inlet of the electrodialysis device.

[0012] In one feasible implementation, the nanofiltration boron removal device includes at least two nanofiltration units and a reverse osmosis unit connected in sequence. Among the nanofiltration units in adjacent stages, the product water outlet of the nanofiltration unit with a lower stage number is connected to the inlet water of the nanofiltration unit with a higher stage number, the backwash water outlet of the nanofiltration unit with a higher stage number is connected to the inlet water of the nanofiltration unit with a lower stage number, the product water outlet of the nanofiltration unit with the highest stage number is connected to the inlet water of the reverse osmosis unit, and the backwash water outlet of the reverse osmosis unit is connected to the inlet water of the nanofiltration unit with the highest stage number.

[0013] In one feasible implementation, the nanofiltration boron removal device includes a primary nanofiltration unit, a secondary nanofiltration unit, and a tertiary nanofiltration unit connected in sequence. The permeate from the primary nanofiltration unit is adjusted by a pH adjustment device before entering the secondary nanofiltration unit. The permeate from the secondary nanofiltration unit is adjusted by a pH adjustment device before entering the tertiary nanofiltration unit. The permeate from the tertiary nanofiltration unit is adjusted by a pH adjustment device before entering the reverse osmosis unit. The permeate from the reverse osmosis unit enters the lithium-ion sedimentation module. The backwash water from the secondary nanofiltration unit enters the primary nanofiltration unit, the backwash water from the tertiary nanofiltration unit enters the secondary nanofiltration unit, and the backwash water from the reverse osmosis unit enters the tertiary nanofiltration unit.

[0014] In one feasible implementation, the magnesium removal module further includes a magnesium recovery device, the inlet of which is connected to the concentrate outlet of the ion exchange resin equipment.

[0015] In one feasible implementation, the magnesium recovery device includes an alkali inlet connected to the alkali outlet of the electrodialysis device.

[0016] In one feasible implementation, the acid outlet of the electrodialysis device is connected to the pH adjustment device.

[0017] In one feasible implementation, the lithium extraction system from the salt lake further includes a pretreatment module, which comprises a raw lake water storage tank, a filtration device, and a filtered water storage tank connected in sequence.

[0018] In one feasible implementation, the filtration device is selected from at least one of a V-type filter, a quartz sand filter, a multi-media filter, or a variable gap filter.

[0019] Implementing this utility model has the following beneficial effects:

[0020] The lithium extraction system from salt lakes provided in this application embodiment efficiently removes magnesium ions from salt lake water through an ion exchange resin magnesium removal device, a nanofiltration membrane magnesium removal device, and a deep reverse osmosis membrane magnesium removal device. It then efficiently extracts lithium ions through an ion exchange resin lithium adsorption device, an MVR device, and a lithium precipitation device. Through the rational combination and connection of these modules, the system achieves efficient removal of impurities such as magnesium and boron from the salt lake brine, improving the purity and recovery rate of lithium extraction, and effectively increasing the lithium ion concentration efficiency and concentration.

[0021] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application, and do not constitute an undue limitation of this application.

[0023] Figure 1 This is a schematic diagram of a lithium extraction system from a salt lake according to an embodiment of this application.

[0024] The reference numerals in the figure:

[0025] 10-Magnesium removal module; 11-Ion exchange resin magnesium removal device; 12-Nanofiltration membrane magnesium removal device; 13-Deep reverse osmosis membrane magnesium removal device; 14-Magnesium recovery device.

[0026] 20 - Boron removal module; 21 - Reverse osmosis boron removal unit; 22 - First-stage nanofiltration unit; 23 - Second-stage nanofiltration unit; 24 - Third-stage nanofiltration unit.

[0027] 30 - Lithium-ion precipitation module; 31 - Lithium adsorption device using ion exchange resin; 32 - MVR device; 321 - Evaporation and recovery equipment; 33 - Lithium precipitation device.

[0028] 40 - Mother liquor recovery module, 41 - Electrodialysis unit, 42 - Nanofiltration membrane recovery unit.

[0029] 50 - Pretreatment module, 51 - Raw lake water storage tank, 52 - Filtration device, 53 - Filtered water storage tank. Detailed Implementation

[0030] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0031] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0032] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0033] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0034] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] Please refer to Figure 1 This application provides a lithium extraction system from a salt lake for extracting lithium from salt lake water. The system includes a magnesium removal module 10, a boron removal module 20, a lithium ion sedimentation module 30, and a mother liquor recovery module 40 connected in sequence.

[0036] The magnesium removal module 10 includes an ion exchange resin magnesium removal device 11, a nanofiltration membrane magnesium removal device 12, and a deep reverse osmosis membrane magnesium removal device 13 connected in sequence. The water outlet of the deep reverse osmosis membrane magnesium removal device 13 is connected to the water inlet of the boron removal module 20.

[0037] The boron removal module 20 includes a nanofiltration boron removal device and a reverse osmosis boron removal device 21 connected in sequence. The product water outlet of the reverse osmosis boron removal device 21 is connected to the inlet of the lithium ion sedimentation module 30.

[0038] The lithium-ion precipitation module 30 includes an ion exchange resin lithium adsorption device 31, an MVR (Mechanical Vapor Recompression) device, and a lithium precipitation device 33 connected in sequence. The MVR device 32 further includes an evaporation recovery device 321. Part of the water produced by the MVR device 32 enters the lithium precipitation device 33 through the evaporation recovery device 321, and the other part directly enters the lithium precipitation device 33.

[0039] The lithium extraction system from salt lakes provided in this application embodiment efficiently removes magnesium ions from salt lake water through an ion exchange resin magnesium removal device 11, a nanofiltration membrane magnesium removal device 12, and a deep reverse osmosis membrane magnesium removal device 13. It then extracts lithium ions through an ion exchange resin lithium adsorption device 31, an MVR device 32, and a lithium precipitation device 33. Through the rational combination and connection of these modules, the system achieves efficient removal of impurities such as magnesium and boron from the salt lake brine, improving the purity and recovery rate of lithium extraction, and effectively increasing the lithium ion concentration efficiency and concentration.

[0040] The magnesium removal device 11 uses a chelating ion exchange resin with iminodiacetic acid groups (-N(CH2COO⁻)2) and aminophosphonic acid groups. The ion exchange resin adsorbs most of the magnesium ions. The eluent from the resin enters the magnesium recovery process; adding alkali to the eluent yields magnesium hydroxide precipitate, resulting in significant magnesium ion recovery. The adsorption tail liquid from the ion exchange resin magnesium removal device 11 enters the nanofiltration membrane device for further magnesium removal. The tail liquid after resin adsorption has a lithium ion concentration of 0.6 g / L, a magnesium ion concentration of 1.9 g / L, and a boron ion concentration of 0.3 g / L. The concentrate from the nanofiltration membrane magnesium removal device 12 is returned to the ion exchange resin in the ion exchange resin magnesium removal device 11 for magnesium ion adsorption. The product directly enters the deep reverse osmosis membrane magnesium removal device 13 for deep magnesium removal. The concentrate from the deep reverse osmosis membrane magnesium removal device 13 is returned to the nanofiltration membrane device, and the product enters the boron removal module 20. In the magnesium removal module 10, the magnesium ion retention rate is greater than 99%, the lithium ion recovery rate is greater than 96%, the lithium ion content is 0.71 g / L, and the magnesium ion content is less than 0.095 mg / L.

[0041] In one feasible implementation, the brine lithium extraction system further includes a lithium precipitation mother liquor recovery module 40. The lithium precipitation mother liquor recovery module 40 includes an electrodialysis device 41, which is connected to the mother liquor outlet of the lithium precipitation device 33 in the lithium-ion precipitation module 30. The electrodialysis device 41, connected to the mother liquor outlet of the lithium precipitation device 33, can treat the low-concentration mother liquor remaining after lithium precipitation, separating acid and alkali solutions, thus avoiding the waste of lithium resources and environmental pollution caused by direct discharge of the mother liquor. Furthermore, the electrodialysis device 41 may be equipped with an inlet, an acid outlet, and an alkali outlet. The obtained acid and alkali solutions can be used in other modules of the brine lithium extraction system, realizing resource recycling and reducing production costs.

[0042] Furthermore, the lithium precipitation mother liquor recovery module 40 also includes a recovery nanofiltration membrane device 42. The inlet of the recovery nanofiltration membrane device 42 is connected to the mother liquor outlet of the lithium precipitation device 33, the product water outlet of the recovery nanofiltration membrane device 42 is connected to the inlet of the MVR device 32, and the concentrate outlet of the recovery nanofiltration membrane device 42 is connected to the inlet of the electrodialysis device 41. The recovery nanofiltration membrane device 42 pre-treats the mother liquor, and the product water is returned to the MVR device 32 for re-concentration, which can further enrich and recover the residual lithium in the mother liquor, improving the overall lithium recovery rate.

[0043] In one feasible implementation, the nanofiltration boron removal device includes at least two nanofiltration stages connected in sequence. In adjacent stages, the permeate outlet of the lower-stage nanofiltration stage is connected to the inlet of the higher-stage nanofiltration stage; the backwash water outlet of the higher-stage nanofiltration stage is connected to the inlet of the lower-stage nanofiltration stage; the permeate outlet of the highest-stage nanofiltration stage is connected to the inlet of the reverse osmosis device; and the backwash water outlet of the reverse osmosis device is connected to the inlet of the highest-stage nanofiltration stage. This multi-stage nanofiltration progressively removes boron ions, improving the boron ion removal rate through progressive filtration from lower-stage permeate to higher-stage permeate. The backwash water from the higher-stage stages is returned to the lower-stage stages, achieving backwash water recycling and reducing water consumption. Simultaneously, the reverse flow of backwash water flushes away residual impurities in the lower-stage stages, preventing membrane fouling and extending the nanofiltration membrane's lifespan.

[0044] In one feasible implementation, the nanofiltration boron removal device includes a primary nanofiltration unit 22, a secondary nanofiltration unit 23, and a tertiary nanofiltration unit 24 connected in sequence. The permeate from the primary nanofiltration unit 22 is adjusted by a pH adjustment device before entering the secondary nanofiltration unit. The permeate from the secondary nanofiltration unit is adjusted by a pH adjustment device before entering the tertiary nanofiltration unit. The permeate from the tertiary nanofiltration unit is adjusted by a pH adjustment device before entering the reverse osmosis unit. The permeate from the reverse osmosis unit enters the lithium ion settling module 30. The backwash water from the secondary nanofiltration unit enters the primary nanofiltration unit, the backwash water from the tertiary nanofiltration unit enters the secondary nanofiltration unit, and the backwash water from the reverse osmosis unit enters the tertiary nanofiltration unit. Thus, the series connection of the three nanofiltration units 24 further improves the boron removal accuracy. Combined with the pH adjustment devices between each stage, boron ions can exist in the form of borate ions, enhancing the nanofiltration membrane's ability to retain boron and effectively reducing the final boron content. Simultaneously, the backwash water flows back in a counter-cyclic manner at each stage. The backwash water (concentrate) from the reverse osmosis unit enters the third-stage nanofiltration unit 24, the third-stage backwash water (concentrate) enters the second-stage nanofiltration unit 23, and the second-stage backwash water (concentrate) enters the first-stage nanofiltration unit 22, forming a closed-loop backwash system. This maximizes the removal of key boron from the brine lake water while ensuring the cleanliness of each membrane module and maintaining stable filtration efficiency. Specifically, the pH adjustment equipment stabilizes the pH of the permeate water at each stage between 9.0 and 9.5, while the boron removal system reduces the boron content to 7.5 mg / L.

[0045] In one feasible implementation, the magnesium removal module 10 further includes a magnesium recovery device 14, the inlet of which is connected to the concentrate outlet of the ion exchange resin equipment. The magnesium recovery device 14 can recover magnesium from the concentrate discharged from the ion exchange resin magnesium removal device 11, converting it into byproducts such as magnesium hydroxide, thereby achieving secondary utilization of magnesium resources and improving the comprehensive utilization rate of salt lake resources.

[0046] In one feasible embodiment, the magnesium recovery device 14 includes an alkali inlet connected to the alkali outlet of the electrodialysis device 41. The alkali solution produced by the electrodialysis device 41 reacts with magnesium ions in the concentrated water in the magnesium recovery device 14 to form magnesium hydroxide precipitate, thereby achieving magnesium recovery and utilization while reducing processing costs.

[0047] In one feasible implementation, the acid outlet of the electrodialysis device 41 is connected to the pH adjustment device. The acid can be used to adjust the pH value of the permeate from each stage of the nanofiltration unit in the nanofiltration boron removal device, thereby achieving resource recycling and reducing the input of chemical reagents.

[0048] In one feasible implementation, the lithium extraction system from the salt lake further includes a pretreatment module 50, which comprises a raw lake water storage tank 51, a filtration device 52, and a filtered water storage tank 53 connected in sequence. The raw lake water storage tank 51 is used to store raw lake water, and the filtration device 52 removes suspended solids such as algae, silt, humus, and colloidal particles from the lake water. The cleaned lake water is stored in the storage tank to provide a stable water supply for the magnesium removal module 10.

[0049] In one feasible embodiment, the filtration device 52 is selected from at least one of a V-type filter, a quartz sand filter, a multi-media filter, or a variable gap filter. This allows for flexible selection of the filtration device 52 based on the water quality characteristics of the salt lake. These characteristics may include, for example, suspended solids content or particulate matter size.

[0050] The workflow of the lithium extraction system from salt lakes provided in this application includes the following steps:

[0051] The raw lake water flows from the raw lake water storage tank 51 into the tank of the filtration device 52. After being filtered by the filtration device 52, suspended impurities are removed. The backwash water is discharged from the backwash port, and the filtered water flows from the outlet into the filtered water storage tank 53.

[0052] The brine from the filtered water storage tank 53 enters the magnesium removal unit 11 of the ion exchange resin. The ion exchange resin adsorbs most of the magnesium ions, and the eluent on the resin enters the magnesium recovery process. Adding alkali to the eluent yields magnesium hydroxide precipitate, resulting in a significant recovery of magnesium ions. The adsorption tail liquid from the ion exchange resin magnesium removal unit 11 enters the nanofiltration membrane unit for further magnesium removal. The lithium ion concentration in the tail liquid after resin adsorption is 0.6 g / L, the magnesium ion concentration is 1.9 g / L, and the boron ion concentration is 0.3 g / L. The concentrate from the nanofiltration membrane magnesium removal unit 12 is returned to the ion exchange resin of the ion exchange resin magnesium removal unit 11 for magnesium ion adsorption. The product liquid directly enters the deep reverse osmosis membrane magnesium removal unit 13 for deep magnesium removal. The concentrate from the deep reverse osmosis membrane magnesium removal unit 13 is returned to the nanofiltration membrane unit, and the product liquid enters the boron removal module 20. In the magnesium removal module 10, the magnesium ion retention rate is greater than 99%, the lithium ion recovery rate is greater than 96%, the lithium ion content is 0.71 g / L, and the magnesium ion content is less than 0.095 mg / L.

[0053] The permeate from magnesium removal module 10 is adjusted to pH 9.0-9.5 and then enters the primary nanofiltration unit 22. After pH adjustment to 9.0-9.5, the permeate from primary nanofiltration unit 22 enters the secondary nanofiltration unit 23, and the concentrate from secondary nanofiltration unit 23 is returned to primary nanofiltration unit 22. After pH adjustment to 9.0-9.5, the permeate from secondary nanofiltration unit 23 enters the tertiary nanofiltration unit 24, and the concentrate from tertiary nanofiltration unit 24 is returned to secondary nanofiltration unit 23. After pH adjustment to 9.0-9.5, the permeate from tertiary nanofiltration unit 24 enters the reverse osmosis boron removal unit 21, and the concentrate from reverse osmosis boron removal unit 21 is returned to tertiary nanofiltration unit 24. The permeate from the reverse osmosis membrane unit then enters the lithium ion settling module 30. The boron removal module 20 has a lithium ion content of 13.5 g / L and a boron content of less than 7.5 mg / L.

[0054] After adjusting the pH of the product liquid from boron removal module 20 to 3-6, it enters the lithium adsorption unit 31 via ion exchange resin. The tail liquid from ion exchange resin adsorption unit 31 enters MVR unit 32 for concentration, achieving a lithium ion concentration of up to 23.5 g / L. The resulting vapor enters evaporation recovery equipment 321, and the concentrated liquid enters lithium precipitation unit 33 for lithium precipitation. After concentration, the lithium ion concentration reaches a certain level. Soda ash is added to lithium precipitation unit 33 to produce lithium carbonate, with a purity exceeding 99.5%. The mother liquor from lithium precipitation unit 33 enters mother liquor recovery module 40.

[0055] The mother liquor from the lithium-ion precipitation module 30 enters the recovery nanofiltration membrane unit 42, the product liquor enters the MVR unit 32, and the concentrate enters the electrodialysis unit 41. The alkaline and acidic solutions separated by the electrodialysis unit 41 are used in the lithium precipitation unit 33, the magnesium recovery unit 14, and the boron removal module 20, as well as for adjusting the system's acidic pH.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A lithium extraction system from a salt lake, characterized in that, The lithium extraction system from the salt lake includes a magnesium removal module, a boron removal module, and a lithium-ion sedimentation module connected in sequence; wherein... The magnesium removal module includes an ion exchange resin magnesium removal device, a nanofiltration membrane magnesium removal device, and a deep reverse osmosis membrane magnesium removal device connected in sequence. The product water outlet of the deep reverse osmosis membrane magnesium removal device is connected to the inlet of the boron removal module. The boron removal module includes a nanofiltration boron removal device and a reverse osmosis boron removal device connected in sequence, and the product water outlet of the reverse osmosis boron removal device is connected to the inlet of the lithium ion sedimentation module. The lithium-ion precipitation module includes an ion exchange resin lithium adsorption device, an MVR device, and a lithium precipitation device connected in sequence. The MVR device further includes an evaporation recovery device. Part of the product water from the MVR device enters the lithium precipitation device through the evaporation recovery device, and the other part enters the lithium precipitation device directly.

2. The lithium extraction system from salt lakes according to claim 1, characterized in that, The lithium extraction system from the salt lake also includes a lithium precipitation mother liquor recovery module, which includes an electrodialysis device connected to the mother liquor outlet of the lithium precipitation device in the lithium ion precipitation module.

3. The lithium extraction system from salt lakes according to claim 2, characterized in that, The lithium precipitation mother liquor recovery module also includes a recovery nanofiltration membrane device. The inlet of the recovery nanofiltration membrane device is connected to the mother liquor outlet of the lithium precipitation device, the product water outlet of the recovery nanofiltration membrane device is connected to the inlet of the MVR device, and the concentrate outlet of the recovery nanofiltration membrane device is connected to the inlet of the electrodialysis device.

4. The lithium extraction system from salt lakes according to claim 2, characterized in that, The nanofiltration boron removal device includes at least two nanofiltration units and a reverse osmosis unit connected in sequence. Among the nanofiltration units in adjacent stages, the product water outlet of the nanofiltration unit with a lower stage number is connected to the inlet water of the nanofiltration unit with a higher stage number, the backwash water outlet of the nanofiltration unit with a higher stage number is connected to the inlet water of the nanofiltration unit with a lower stage number, the product water outlet of the nanofiltration unit with the highest stage number is connected to the inlet water of the reverse osmosis unit, and the backwash water outlet of the reverse osmosis unit is connected to the inlet water of the nanofiltration unit with the highest stage number.

5. The lithium extraction system from salt lakes according to claim 4, characterized in that, The nanofiltration boron removal device includes a primary nanofiltration unit, a secondary nanofiltration unit, and a tertiary nanofiltration unit connected in sequence. The permeate from the primary nanofiltration unit is adjusted by a pH adjustment device before entering the secondary nanofiltration unit. The permeate from the secondary nanofiltration unit is adjusted by a pH adjustment device before entering the tertiary nanofiltration unit. The permeate from the tertiary nanofiltration unit is adjusted by a pH adjustment device before entering the reverse osmosis unit. The permeate from the reverse osmosis unit enters the lithium ion precipitation module. The backwash water from the secondary nanofiltration unit enters the primary nanofiltration unit, the backwash water from the tertiary nanofiltration unit enters the secondary nanofiltration unit, and the backwash water from the reverse osmosis unit enters the tertiary nanofiltration unit.

6. The lithium extraction system from salt lakes according to claim 2, characterized in that, The magnesium removal module also includes a magnesium recovery device, the inlet of which is connected to the concentrate outlet of the ion exchange resin equipment.

7. The lithium extraction system from salt lakes according to claim 6, characterized in that, The magnesium recovery device includes an alkali inlet, which is connected to the alkali outlet of the electrodialysis device.

8. The lithium extraction system from salt lakes according to claim 5, characterized in that, The acid outlet of the electrodialysis device is connected to the pH adjustment device.

9. The lithium extraction system from salt lakes according to claim 1, characterized in that, The lithium extraction system from the salt lake also includes a pretreatment module, which comprises a raw lake water storage tank, a filtration device, and a filtered water storage tank connected in sequence.

10. The lithium extraction system from salt lakes according to claim 9, characterized in that, The filtration device is selected from at least one of V-type filter, quartz sand filter, multi-media filter, or variable gap filter.

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