Method and device for extracting lithium from salt lake brine

Abstract

The application belongs to the technical field of lithium extraction, and discloses a method and device for extracting lithium from salt lake raw brine, which comprises the following steps: performing crystallization treatment on the raw brine in advance before adsorption lithium extraction, so as to reduce the saturation degree of salt in the raw brine; and then performing adsorption lithium extraction on the treated raw brine. The crystallization treatment on the raw brine in advance before adsorption lithium extraction reduces the crystallization trend of the crystallization components in the raw brine during adsorption lithium extraction, thereby avoiding a series of problems such as plugging of the adsorption column and caking of the adsorbent caused by crystallization of salt during adsorption lithium extraction.

Description

Technical Field

[0001] This invention relates to the field of lithium extraction technology, and in particular to a method and apparatus for lithium extraction from raw brine in salt lakes. Background Technology

[0002] With the rapid development of new energy vehicles, electronic devices and energy storage technologies, lithium has become a key raw material for global energy transformation, especially in new energy fields such as high-performance power batteries and energy storage systems, where it holds an irreplaceable core position.

[0003] Most lithium resources are found in salt lake brines, and the current mainstream front-end process for lithium extraction from salt lake brines is "adsorption + membrane." Most use old brine as raw material. The existing conventional method of lithium extraction from old brine involves evaporation of the raw brine through sodium salt ponds, equalization ponds, and carnallite ponds. After more than half of the water evaporates, most of the sodium chloride settles in the sodium salt ponds, a portion settles in the equalization ponds, and potassium chloride settles in the carnallite ponds. Lithium extraction based on the settled brine allows for continuous lithium chloride adsorption. However, during the process of moving from the raw brine to the old brine through the sodium salt ponds, equalization ponds, and carnallite ponds, lithium chloride resources are already carried away by the settled sodium chloride and carnallite, resulting in a loss of more than 50% and a significant waste of lithium resources.

[0004] Chinese patent CN119082492B discloses a method and system for combined lithium extraction from mineralized brine and old brine. This process combines lithium extraction from mineralized brine with lithium extraction from old brine. Although it reduces lithium loss from mineralized brine, it does not solve the lithium loss problem in the lithium extraction process from old brine.

[0005] To address the issue of significant lithium loss during lithium extraction from old brine, some literature suggests using freshly extracted brine as raw material for lithium extraction.

[0006] For example, Chinese patent application CN118792522A discloses a method for lithium extraction from raw brine in salt lakes. The method involves directly feeding the raw brine into an adsorption column and extracting the eluent using a divalent cation extraction system to obtain a lithium-rich raffinate, thus achieving efficient separation and enrichment of lithium ions in raw brine from salt lakes.

[0007] For example, Chinese patent CN118755959B discloses a continuous cross-linking process for lithium extraction from chlorinated raw brine, which includes sequentially filtering, adsorbing, rinsing, desorbing, and top-liquid treatment of the chlorinated raw brine. Compared with lithium extraction from old brine, this process can extract lithium without sun-drying in sodium salt ponds after the raw brine is mined, thus avoiding lithium loss in salt fields.

[0008] The aforementioned literature addresses the lithium loss problem in lithium extraction from old brine by using raw brine extraction. However, during their research on raw brine lithium extraction, the inventors realized that many salts in the raw brine are saturated or near-saturated. During adsorption, due to the adsorbent's large specific surface area, salt crystallization easily occurs on the adsorbent surface and in the pores within the adsorption column. Figure 3 shows the crystallization route of salts (NaCl, KCl, MgCl2) extracted from the raw brine of the Qarhan Salt Lake. Currently, no reports or solutions regarding salt crystallization in the "adsorption column" have been found.

[0009] Although some literature mentions the problem of brine salt formation, for example, coating technology: patent CN221278088U proposes applying an anti-salt-forming coating made of hydrophobic material to the inner surface of the container or pump. Another example is water-injection desalination technology: patents CN220909664U and CN218669758U propose using a spraying device to evenly spray fresh water around the brine pump and well wall to solve the impact of salt formation on brine extraction; patents CN101476557B, CN207195217U, and CN104196498A install fresh water pipelines at the pump's inlet section, allowing the salt to dissolve or lose its adhesion through fresh water, ultimately being discharged with the collected brine, thus preventing salt formation in the brine pump.

[0010] However, these documents emphasize the problem of salt formation on container walls / brine pumps during brine transportation or extraction. Moreover, coatings cannot solve the problem of salt crystallization on the surface or between adsorbents in the adsorption column. Although water-addition desalination technology can solve the problem of salt formation on the surface of the adsorbent in the original brine to some extent, the inventors further realized that the large amount of fresh water added to the original brine will greatly increase the evaporation required for potassium salt production when the brine enters the salt field evaporation stage after lithium extraction and adsorption, which will have an adverse effect on subsequent potassium fertilizer production. Summary of the Invention

[0011] According to one embodiment of the present invention, the purpose is to provide a method and apparatus for lithium extraction from salt lake brine. By pretreating the salt lake brine, the crystallization tendency of crystallizing components (such as sodium chloride) in the brine is reduced, so as to avoid a series of problems such as adsorbent blockage and agglomeration caused by salt crystallization during the lithium extraction process using brine with less lithium loss.

[0012] The above objective can be achieved through the following technical solutions: According to one aspect of the present invention, a method for lithium extraction from raw brine in a salt lake is provided, comprising: pre-crystallizing the raw brine by employing a crystallization-promoting method before adsorption lithium extraction to reduce the salt saturation level in the raw brine, thereby obtaining treated raw brine; and performing adsorption lithium extraction on the treated raw brine.

[0013] Preferably, the method of promoting crystallization includes one or more of seed-induced crystallization, ultrasonic treatment, and temperature control for crystallization.

[0014] Preferably, the method of promoting crystallization is seed-induced crystallization.

[0015] Preferably, the original halogen is pre-crystallized using a seed-induced crystallization method based on heterogeneous nucleation.

[0016] Preferably, the step of crystallizing the raw brine is carried out using a particle bed crystallizer, including: allowing the raw brine to flow through the particle bed crystallizer and crystallizing on the surface of the particle packing.

[0017] Preferably, the particle bed crystallizer is a particle bed with a high specific surface area.

[0018] Preferably, the surface area provided by the particle bed is greater than the surface area provided by the adsorbent during lithium adsorption.

[0019] Preferably, the particle bed has a particle size of 0.5mm-5mm.

[0020] Preferably, the thickness of the particle bed is 0.5m-2m.

[0021] Preferably, the step of crystallizing the raw brine further includes: when the crystallization process on the surface of the particle packing in the particle bed crystallizer reaches equilibrium, switching the valve to allow the raw brine to enter the next parallel particle bed crystallizer to continuously complete the crystallization process.

[0022] Preferably, the method further includes: washing the particle bed crystallizer to obtain washing wastewater.

[0023] Preferably, after leaching, the process further includes: collecting the leaching wastewater and returning it as a brine extraction solvent to the brine extraction process in the salt field.

[0024] Preferably, the washing method adopts one of the following methods: water washing, combined water and aeration washing, combined water and hydraulic stirring washing, and combined water and mechanical stirring washing.

[0025] Preferably, the step of allowing the raw brine to flow through the particle bed crystallizer further includes: using a water distributor to evenly distribute water to the raw brine, so that the raw brine passes evenly through the particle bed of the particle bed crystallizer after water distribution.

[0026] Preferably, the step of washing the particle bed crystallizer further includes: using a water distributor to evenly distribute the washing water so that the washing water passes evenly through the particle bed of the particle bed crystallizer after distribution, thereby washing the particle bed crystallizer.

[0027] According to another aspect of the present invention, a lithium extraction apparatus from salt lake brine is provided, comprising: Crystallization equipment is used to crystallize the raw brine by promoting crystallization before adsorption lithium extraction, so as to reduce the salt saturation of the raw brine, obtain the treated raw brine, and send it to the adsorption lithium extraction device. An adsorption lithium extraction device, including an adsorption column, is used to adsorb and extract lithium from the supplied processed raw brine.

[0028] Preferably, the method of promoting crystallization is seed-induced crystallization.

[0029] Preferably, the method for promoting crystallization is a seed-induced crystallization method based on heterogeneous nucleation.

[0030] Preferably, the crystallization equipment is a particle bed crystallizer.

[0031] Preferably, the crystallization equipment is a particle bed crystallizer with a high specific surface area.

[0032] Preferably, the crystallization treatment equipment further includes a washing pipeline for washing the crystallization treatment equipment with washing water.

[0033] Preferably, the washing pipeline is connected to a collector for collecting washing wastewater, which is then returned to the brine extraction process in the salt field as a brine extraction solvent.

[0034] Preferably, the crystallization processing equipment further includes a water distributor for uniformly distributing water.

[0035] Preferably, the crystallization processing equipment consists of multiple units, which are connected in parallel, and each crystallization processing equipment is equipped with a valve on a branch pipe connected to the original brine main pipeline.

[0036] Preferably, the washing pipeline includes multiple washing branch pipelines, each washing branch pipeline is connected to a crystallization processing device, and each washing branch pipeline is equipped with a valve.

[0037] Beneficial effects: According to one embodiment of the present invention, in the lithium extraction method based on raw brine, the raw brine is crystallized in advance before entering the adsorption lithium extraction process, thereby reducing the saturation and crystallization tendency of the raw brine, thus avoiding salt crystallization during the adsorption lithium extraction process, and overcoming a series of problems such as adsorbent blockage and agglomeration caused by salt crystallization.

[0038] Compared with the prior art, the embodiments of the present invention have the following advantages: 1) When performing early crystallization treatment, using a crystallization-promoting method can reduce the difficulty of crystallization and effectively promote the early and rapid crystallization of salt.

[0039] Among these methods, seed-induced crystallization is preferred. By lowering the kinetic energy barrier of crystallization, the salt crystallizes earlier, thereby reducing the saturation level and crystallization tendency of the raw brine entering the adsorption lithium extraction unit. Furthermore, using seed-induced crystallization based on heterogeneous nucleation can significantly reduce the energy barrier of the crystallization process, transforming the spontaneous homogeneous crystallization process in the solution into a highly efficient heterogeneous surface deposition process, making it easier to initiate crystallization.

[0040] 2) In the seed-induced crystallization method, a particle bed crystallizer with a high specific surface area is used for pre-crystallization treatment. During the continuous passage of the original brine through the particle bed with a high specific surface area, the huge specific surface area of ​​the particle bed provides a large number of low-energy nucleation sites, which significantly reduces the kinetic energy barrier of crystallization. This allows chloride and sodium ions to precipitate from the liquid phase and crystallize and anchor on the particle surface during the flow process, thereby reducing the saturation degree of salts such as sodium chloride in the original brine and reducing the crystallization tendency in the subsequent adsorption process. That is, the original brine will not crystallize (such as sodium chloride crystallization) when passing through the lithium chloride adsorption column.

[0041] 3) After crystallization is completed, crystallization equipment such as granular bed crystallizers can be restored to their crystallization-promoting function through a washing operation and can continue to be used; moreover, the washing wastewater can be reused as a solvent in the brine extraction process of salt fields.

[0042] 4) During the process of the raw brine flowing through the granular bed of the granular bed crystallizer, water is first distributed through a water distributor to ensure that the raw brine flows evenly through the granular bed and that the water flow is evenly distributed on the effective flow cross-section of the granular bed, thereby further improving the crystallization efficiency.

[0043] 5) By setting up multiple crystallization processing devices in parallel, the raw brine can be continuously pre-treated for crystallization by switching valves, thus achieving continuous crystallization processing.

[0044] 6) By adsorbing and extracting lithium from the original brine after reducing the salt saturation, the problem of salt crystallization on the surface or in the gaps of the adsorbent is avoided, thus improving the lithium extraction efficiency. Compared with lithium extraction from old brine, the lithium loss is small and the recovery rate is high. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the lithium extraction process from salt lake brine based on a high specific surface area particle bed crystallizer in an embodiment of the present invention; Figure 2 This is a schematic diagram of the washing process of the high specific surface area particle bed crystallizer in an embodiment of the present invention; Figure 3 This is a schematic diagram of the crystallization route of the raw brine extracted from the Qarhan Salt Lake. Detailed Implementation

[0046] The technical solution of the present invention will be clearly and completely described below with reference to embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0047] The mainstream front-end process for lithium extraction from salt lake brine is "adsorption + membrane treatment," using raw brine as raw material, resulting in lithium loss exceeding 50%. While using freshly extracted raw brine avoids lithium resource entrainment loss, the brine contains various salts in a saturated or near-saturated state. During adsorption, due to the large specific surface area of ​​the porous adsorbent, high-salt raw brine easily crystallizes on the surface and in the pores of the adsorbent, causing a series of problems such as adsorbent blockage, poisoning, and shortened lifespan. Taking the raw brine extracted from the Qarhan Salt Lake as an example, the first component to precipitate in the raw brine is sodium chloride, such as... Figure 3 As shown in the phase diagram, OP represents the sodium chloride crystallization route. During the process of the raw brine passing through the porous adsorbent bed in the adsorption column for lithium extraction, sodium chloride molecules in the raw brine do not need to form new crystal nuclei and can directly adhere to the adsorbent surface to form crystals. The crystallized sodium chloride crystals will cause a series of problems such as adsorbent blockage and agglomeration, seriously affecting the lithium extraction process.

[0048] This invention innovatively proposes a method for lithium extraction from raw brine in salt lakes. Before the raw brine enters the adsorption process, the sodium chloride and other salts in the brine are pre-crystallized, reducing the salt saturation level. Due to the reduced salt saturation, the crystallization tendency during the lithium extraction process decreases, allowing the raw brine adsorption process to operate normally and be implemented smoothly. Compared to lithium extraction from aged brine, this invention significantly improves the recovery rate of lithium resources from raw brine. Moreover, by pre-crystallizing the raw brine before adsorption and lithium extraction, a series of problems caused by adsorbent blockage, poisoning, and shortened lifespan due to salt crystallization on the surface or gaps of the adsorbent in the adsorption column are avoided.

[0049] This invention also provides a lithium extraction device for raw brine from salt lakes, comprising a crystallization treatment device and an adsorption lithium extraction device. The crystallization treatment device is used to crystallize the raw brine to reduce its salt saturation, obtaining treated raw brine, which is then sent to the adsorption lithium extraction device. The adsorption lithium extraction device is connected to the outlet of the crystallization treatment system and includes an adsorption column for adsorbing and extracting lithium from the treated raw brine.

[0050] By installing a crystallization treatment device, such as a particle bed crystallizer, before the adsorption lithium extraction unit, pre-crystallization is performed using this device, reducing the saturation level of salts in the raw brine entering the adsorption lithium extraction unit, thereby reducing the tendency of salts in the raw brine to crystallize in the adsorption lithium extraction unit. Preferably, the crystallization treatment device also includes a water distributor for uniformly distributing the raw brine or washing water, ensuring that the distributed raw brine or washing water passes evenly through the crystallization treatment device, avoiding short-circuiting or uneven liquid distribution.

[0051] In this invention, when pre-crystallizing the raw brine, a crystallization-promoting method is preferably used. Using a crystallization-promoting method reduces the difficulty of crystallization, effectively promotes the early crystallization of salts, reduces the salt saturation level in the lithium-extraction raw brine, and decreases the tendency of salts to crystallize during the adsorption process. The crystallization-promoting method can be one or more of seed-induced crystallization, ultrasonic treatment, and temperature control.

[0052] In some preferred embodiments, seed-induced crystallization is used to crystallize the raw brine. For example, particle bed-induced crystallization. Seed-induced crystallization lowers the kinetic energy barrier of crystallization, causing the salt to crystallize earlier, thereby reducing the saturation and crystallization tendency of the raw brine entering the adsorption lithium extraction unit. Furthermore, by employing heterogeneous nucleation-induced crystallization, heterogeneous surface deposition significantly reduces the energy barrier of the crystallization process, transforming the spontaneous homogeneous crystallization process in solution into a highly efficient heterogeneous surface deposition process, making it easier to initiate crystallization.

[0053] In some preferred embodiments, based on seed-induced crystallization, a high specific surface area particle bed crystallizer is used to pre-crystallize the original brine to reduce the salt saturation of the original brine before adsorption and lithium extraction.

[0054] like Figure 1 As shown, it includes the following steps: 1) The raw brine is passed through a high specific surface area particle bed crystallizer, allowing the salt in the raw brine to crystallize on the surface of the particle packing, reducing the salt saturation of the raw brine, and obtaining the treated raw brine; 2) The treated raw brine is then introduced into an adsorption lithium extraction device for adsorption lithium extraction.

[0055] Based on the induced crystallization method, before the raw brine enters the adsorption lithium extraction process, the raw brine is first allowed to flow through a high specific surface area particle bed crystallizer, which promotes the early crystallization of salts such as sodium chloride in the raw brine in the particle bed. Since the salt saturation has been reduced during adsorption lithium extraction, the crystallization tendency of salt in the adsorption lithium extraction device is reduced, so that the raw brine adsorption lithium extraction process can be operated normally and implemented smoothly.

[0056] The principle of granular bed-promoted crystallization: As the raw brine continuously passes through a high specific surface area granular bed, the large surface area of ​​the granular bed provides numerous low-energy nucleation sites, significantly reducing the kinetic energy barrier for crystallization. This allows chloride and sodium ions to precipitate from the liquid phase and crystallize and anchor on the particle surface during the flow process. Consequently, the raw brine completes premature crystallization before entering the lithium extraction adsorption column. At this point, the saturation of the raw brine is insufficient to produce salt crystallization on the adsorbent surface and in the pores, thus ensuring the smooth progress of the entire adsorption process. Moreover, this process does not require the addition of fresh water to the raw brine and will not affect subsequent potash fertilizer production.

[0057] In addition, such as Figure 1 As shown, the adsorption lithium extraction device adsorbs the treated raw brine to obtain adsorbed raw brine, which can then be evaporated in a sodium salt bath. After adsorption, the adsorption lithium extraction device can further eluent to produce a qualified adsorption solution, in which the concentration and purity of lithium ions have been initially enriched and improved. For further purification, conventional membrane treatment is used for deep impurity removal to remove any remaining small amounts of impurities.

[0058] The granular bed crystallizer provides a large solid-liquid contact area through granular packing, inducing salt crystallization and transforming the homogeneous crystallization process in solution into a highly efficient heterogeneous surface deposition process. To more efficiently promote the early crystallization of the original brine salts and significantly reduce the crystallization tendency of the salts during lithium extraction, the surface area provided by the granular bed crystallizer is greater than the surface area provided by the lithium extraction adsorbent. The granular packing in the crystallizer provides a large specific surface area; the material is not limited, as long as it differs from the salt. It can be common inorganic packing used in crystallizers or organic packing. The particle size of the granular packing is not limited; for example, the particle size can be 0.5mm-5mm, specifically determined based on the actual production scale and the surface area provided by the lithium extraction adsorbent. Examples of average particle sizes include 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, and 5.0mm. Furthermore, the thickness of the particle bed is not limited and can be adjusted according to the size of the crystallizer. For example, the thickness of the particle bed can be controlled within the range of 0.5m-2m to maximize the crystallization-promoting effect of the filler while providing the required surface area.

[0059] In some embodiments, the method further includes: regenerating the crystallization equipment. After the crystallization equipment has been running for a period of time, its function of reducing the saturation of raw brine salts decreases or fails, requiring regeneration of the crystallization equipment. This can be achieved by washing the crystallization equipment with dissolving water to dissolve the salt deposits in the equipment. The washing method can be one of the following: fresh water washing, or a combination of fresh water and aeration, fresh water and hydraulic stirring, or fresh water and mechanical stirring.

[0060] For example, such as Figure 2 As shown, the crystallization equipment described in this embodiment is a particle bed crystallizer. When the surface crystallization of particles in the particle bed crystallizer is saturated, for example, when the surface area provided by a high specific surface area particle bed crystallizer has been completely or partially occupied by sodium chloride crystals and the particle surface cannot recrystallize, the particle bed crystallizer is soaked and washed with fresh water to wash off the crystalline salts attached to the particle surface, thereby restoring the crystallization-promoting function of the particle bed and allowing the particle bed crystallizer to be reused.

[0061] In addition, the salt-containing washing wastewater from the crystallization treatment unit can be collected in a collector and used as a supplementary raw material for brine extraction, returning it to the brine extraction process in the salt fields. If the washing wastewater contains impurities, it can be treated first, for example, by filtration using a filter press, and then the separated liquid can be collected and returned to the brine extraction process in the salt fields.

[0062] By leaching the granular bed crystallizer, on the one hand, the crystallizer function can be restored after the crystallization-promoting effect of the high specific surface area granular bed is reduced or ineffective; on the other hand, the salts of the granular bed crystals are dissolved out, and the leaching liquid, i.e., the leaching wastewater, can be returned to the brine mining stage as a solvent for recycling.

[0063] In some embodiments, when crystallizing raw brine, multiple crystallization devices connected in parallel are arranged to form a crystallizer group, such as a granular bed crystallizer group, to continuously complete the pre-crystallization process. Specifically, multiple branch pipelines are connected to the main raw brine pipeline used to transport the raw brine. Each branch pipeline is connected to a crystallization device, and each branch pipeline is equipped with a valve. The feed is switched by the valve, so that the raw brine enters the next parallel granular bed crystallizer. By having multiple crystallization devices operate sequentially and continuously, the pre-crystallization process is continuously completed.

[0064] For example, when the crystallization process on the surface of the granular packing material in a granular bed crystallizer reaches equilibrium (crystallization saturation), or when the bed resistance exceeds the limit due to salt crystallization agglomeration or blockage by salt crystals and impurities, the system can automatically switch to the next granular bed crystallizer via a valve. This allows the raw brine to continue contacting the clean granular packing material, completing the crystallization-reduction saturation process. Crystallizers where the surface of the granular packing material cannot recrystallize can be washed to restore their crystallization-promoting function and reused.

[0065] In addition, in optional embodiments, the crystallization treatment equipment, such as a particle bed crystallizer, is provided with a washing pipeline in addition to the original brine pipeline. The washing pipeline is connected to each crystallization treatment equipment through each washing branch pipeline. Each washing branch pipeline is equipped with a valve, which can be used to switch the washing water so that the washing water enters the crystallization treatment equipment that needs to be washed for washing.

[0066] The present invention will now be described in conjunction with a specific embodiment and accompanying drawings: Example This embodiment provides a method for lithium extraction from raw brine in salt lakes, which uses a particle bed crystallizer for pre-induced crystallization. Taking sodium chloride crystallization as an example, the specific steps include: 1) The raw brine enters the water distributor and is evenly distributed across the flow cross section of the cleaned particle bed crystallizer.

[0067] 2) The original brine passes uniformly through the cross section of the particle bed, continuously contacting the solid-liquid interface between the uncrystallized saturated particles and the original brine. Sodium chloride salts in the original brine continuously crystallize at the solid-liquid interface, and the crystals gradually grow.

[0068] 3) When the packing material at the very end of the particle bed that is in contact with the raw brine reaches the crystallization limit and the saturation of sodium chloride in the raw brine can no longer be reduced, stop using it and transfer the raw brine to the next particle bed crystallizer by switching valves.

[0069] 4) Use a washing pipeline to soak and wash the particle bed crystallizer that was stopped in step 3) to wash away the crystalline salts attached to the particle surface and restore the function of the particle bed crystallizer.

[0070] 5) Collect the washing wastewater, i.e., the brine containing solid impurities. Filter the brine using a filter press to obtain mud cake, and send the mud cake out. The treated brine is returned to the salt field for use as a brine extraction solvent.

[0071] 6) The granular bed crystallizer after washing is ready for use. After being re-entered into the brine, steps 1) to 6) are repeated.

[0072] 7) The raw brine after treatment in each particle bed crystallizer is sent to the adsorption lithium extraction unit for adsorption lithium extraction. After adsorption, the raw brine is sent to the sodium salt pool for evaporation. The adsorption lithium extraction unit can produce qualified adsorption solution after all adsorption lithium extraction processes are completed. Test results: The adsorption lithium extraction can operate normally, and no salt crystallization occurred on the surface and pores of the adsorbent in the adsorption column.

[0073] In summary, based on the original brine lithium extraction method, this invention first introduces the original brine into a high specific surface area particle bed crystallizer before it enters the adsorption column. Through induced crystallization, the sodium chloride and other salts in the original brine are promoted to crystallize in advance in the particle bed, reducing the salt saturation in the original brine. This prevents the salts from crystallizing in the lithium extraction adsorption column, solving a series of problems caused by salt crystallization during the original brine adsorption lithium extraction process, such as adsorbent blockage, poisoning, and shortened lifespan. This allows the original brine lithium extraction to be carried out smoothly and significantly improves the recovery rate of lithium resources in the original brine.

[0074] Furthermore, after the crystallization-promoting effect of high specific surface area particle bed crystallizers decreases or becomes ineffective, it can be restored to its function of promoting early salt crystallization by washing with fresh water, or by a combination of fresh water and aeration, hydraulic stirring, or mechanical stirring. The salt crystallized in the particle bed crystallizer can be washed out by water, and the separated liquid can be reused as a brine solvent in salt fields.

[0075] The description of this invention is given for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A method for lithium extraction from raw brine in salt lakes, characterized in that, The method includes: The raw brine was crystallized using a method that promotes crystallization, thereby reducing the salt saturation level in the raw brine and obtaining the treated raw brine. Lithium extraction is performed on the treated raw brine by adsorption. The crystallization promotion method is a seed-induced crystallization method based on heterogeneous nucleation; the seed-induced crystallization method based on heterogeneous nucleation is used to pre-crystallize the original brine, including: letting the original brine flow through a particle bed crystallizer and crystallize on the surface of the particle packing; the particle bed crystallizer has a high specific surface area, and the surface area provided by the particle bed is greater than the surface area provided by the adsorbent during lithium adsorption.

2. The method for lithium extraction from salt lake brine according to claim 1, characterized in that, The particle size in the particle bed is 0.5mm-5mm; And / or, the thickness of the particle bed is 0.5m-2m.

3. The method for lithium extraction from salt lake brine according to claim 1, characterized in that, The step of crystallizing the original brine further includes: When the crystallization process on the surface of the particle packing in the particle bed reaches equilibrium, the valve is switched to allow the raw brine to enter the next parallel particle bed crystallizer to continuously complete the crystallization process.

4. The method for lithium extraction from salt lake brine according to claim 1, characterized in that, The method further includes: The granular bed crystallizer is washed to obtain washing wastewater; The washing wastewater is collected and returned to the brine extraction process in the salt field as a brine extraction solvent; Among them, the washing method adopts one of the following methods: water washing, water and aeration combined washing, water and hydraulic stirring combined washing, and water and mechanical stirring combined washing.

5. The method for lithium extraction from salt lake brine according to claim 4, characterized in that, The step of allowing the raw brine to flow through the particle bed crystallizer further includes: uniformly distributing water to the raw brine using a water distributor; The step of washing the particle bed crystallizer further includes: using a water distributor to evenly distribute the washing water.

6. A lithium extraction apparatus for raw brine from salt lakes used in the lithium extraction method according to any one of claims 1-5, characterized in that, include: A crystallization processing device is used to pre-crystallize raw brine using a crystallization-promoting method to reduce the salt saturation level in the raw brine, obtain processed raw brine, and send it to an adsorption lithium extraction device; wherein, the crystallization-promoting method is a seed-induced crystallization method based on heterogeneous nucleation; An adsorption lithium extraction device, including an adsorption column, is used to adsorb and extract lithium from the supplied processed raw halogen.

7. The lithium extraction device from salt lake brine according to claim 6, characterized in that, The crystallization equipment also includes a water distributor for uniformly distributing water; The crystallization equipment is a particle bed crystallizer with a high specific surface area.

8. The lithium extraction device from salt lake brine according to claim 7, characterized in that, The crystallization treatment equipment also includes a washing pipeline for washing the crystallization treatment equipment with washing water; The washing pipeline is also connected to a collector for collecting washing wastewater, which is then returned to the brine extraction process in the salt field as a brine extraction solvent.

9. The lithium extraction device from salt lake brine according to claim 8, characterized in that, The crystallization processing equipment consists of multiple units, which are connected in parallel. Each crystallization processing equipment is equipped with a valve on the branch pipe connected to the original brine main pipeline. Alternatively, the washing pipeline may include multiple washing branch pipelines, each of which is connected to a crystallization processing device, and each washing branch pipeline is equipped with a valve.

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