Crystallization device, system and process for extracting lithium from brine
By incorporating a stirring mechanism and vibration element within the crystallizer, combined with a spiral guide channel, the problems of uneven lithium salt crystal size and low nucleation efficiency were solved, resulting in more efficient crystal growth and heat transfer.
Patent Information
- Application Number
- CN202512058220.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-02-17
AI Technical Summary
In the existing crystallizer process of lithium extraction from brine, the lithium salt crystals have uneven particle size, low nucleation and growth efficiency, and the crystals tend to adhere to the inner wall, affecting the heat transfer efficiency.
A stirring mechanism and a first vibration element are set in the crystallizer body. Combined with the spiral guide channel design, the mixing and mass transfer are enhanced through high-frequency micro-vibration and structured flow channels, the concentration gradient is destroyed, crystal adhesion is prevented, and the uniformity of nucleation and heat transfer efficiency are improved.
This method achieves uniformity in lithium salt crystal size and improves nucleation and growth efficiency, reduces crystal adhesion to the inner wall, and enhances the heat transfer performance of the crystallizer.
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Figure CN121534413A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of lithium ion recovery, in particular to a crystallization device, a lithium extraction system from brine and a process thereof. BACKGROUND
[0002] Lithium carbonate, as the core material of the lithium industry chain, is widely used in power batteries, aerospace and medical fields. With the rapid development of the new energy industry, the demand for lithium is increasing year by year, and the extraction and separation technology of lithium has attracted more and more attention.
[0003] The process of lithium carbonate precipitation crystallization is the core link of lithium extraction process. Its essence is to mix brine containing lithium ions with sodium carbonate solution. The concentration of carbonate ions in the mixed solution rapidly increases, forming a supersaturated solution of lithium carbonate, and nucleating and growing lithium carbonate crystals. The core control carrier in this stage is the crystallizer. This type of equipment uniformly mixes the brine in the vessel through mechanical stirring, promotes heat and mass transfer, and provides the necessary supersaturation environment for crystal growth. However, due to the high salt content in the lithium-rich solution extracted from salt lakes, it has a certain viscosity and a low solute diffusion coefficient. Simply relying on traditional stirring type crystallizers cannot completely eliminate the concentration gradient between the solid-liquid phases and the internal solution, which easily leads to uneven nucleation and growth of crystals, and is difficult to meet the requirements of high-end lithium salts for uniformity of crystal particle size. In addition, during long-term operation, some small crystals are easily attached to the inner wall of the crystallizer, which reduces the heat transfer efficiency of the crystallizer and affects the nucleation and growth efficiency of the crystals. SUMMARY
[0004] The purpose of the present application is to provide a crystallization device, a lithium extraction system from brine and a process thereof to solve the problems existing in the prior art, improve the uniformity of lithium salt crystal particle size, and improve the nucleation and growth efficiency of the crystals.
[0005] To achieve the above-mentioned purpose, the present application provides the following solutions: The present application provides a crystallization device, comprising a crystallizer body, a stirring mechanism and a first vibration element. The crystallizer body is used to accommodate slurry. A spiral flow guide groove is formed on the inner wall of the crystallizer body. An inlet and an outlet are also provided on the crystallizer body. The inlet is used to introduce sodium carbonate solution and brine, and the outlet is used to discharge lithium carbonate slurry. The stirring mechanism is arranged inside the crystallizer body and is used to stir the slurry in the crystallizer body. The first vibration element is arranged on the side wall of the crystallizer body, and the first vibration element can apply mechanical vibration to the crystallizer body.
[0006] In some embodiments, the feeding part comprises a jet nozzle and a feeding port, the jet nozzle extends into the inside of the crystallizer body for feeding the brine into the crystallizer body, and the feeding port is arranged on the inner wall of the crystallizer body for feeding the sodium carbonate solution into the crystallizer body.
[0007] In some embodiments, the first vibrating element comprises at least one ultrasonic transducer and an ultrasonic generator connected therewith, the ultrasonic transducer is arranged on the side wall of the crystallizer body for applying mechanical vibration to the crystallizer body.
[0008] In some embodiments, further comprising a heating body, the heating body is sleeved on the outside of the side wall and the bottom wall of the crystallizer body, a heat-conducting medium is filled between the outer wall of the crystallizer body and the inner wall of the heating body, and an electric heating wire is arranged in the heating body to heat the slurry in the crystallizer body through the heat-conducting medium.
[0009] The application further provides a brine lithium extraction system, comprising a nanofiltration device, a membrane distillation device, an adsorption device and the crystallization device according to any one of the above in sequence.
[0010] In some embodiments, the nanofiltration device comprises a plurality of nanofiltration units connected in series, each of the nanofiltration units is provided with a nanofiltration membrane for passing the brine, at least a part of the edge of the nanofiltration membrane is connected with a second vibrating element, and the second vibrating element can vibrate the nanofiltration membrane.
[0011] In some embodiments, the membrane distillation device comprises a plurality of membrane distillation units connected in series, each of the membrane distillation units is provided with a heater, a hydrophobic microporous membrane and a cold side circulation unit, the heater is used for heating the brine; the hydrophobic microporous membrane can divide the membrane distillation unit into a hot side and a cold side, and is used for separating the brine heated by the heater flowing through the hot side from the fluid flowing through the cold side; and the cold side circulation unit is used for providing and cooling the fluid flowing through the cold side to form a vapor pressure difference on both sides of the hydrophobic microporous membrane, so that the water vapor of the hot side passes through the hydrophobic microporous membrane to reach the cold side.
[0012] In some embodiments, the adsorption device comprises an adsorption tank, the adsorption tank is provided with a first liquid inlet, a second liquid inlet, an eluent outlet and a tail brine outlet, a resin bed layer is supported by a grid in the inside of the adsorption tank, the first liquid inlet is used for receiving the brine discharged from the hot side of the membrane distillation unit, the resin bed layer is used for adsorbing lithium ions, the tail brine outlet is used for discharging the tail brine after adsorption, and the second liquid inlet is used for receiving the eluent for flushing the resin bed layer, and the eluent outlet is used for discharging the eluent into the crystallization device.
[0013] In some embodiments, a controller is further included, which is signal connected with the nanofiltration device, the membrane distillation device, the adsorption device and the crystallization device respectively.
[0014] The application also provides a brine lithium extraction process using the brine lithium extraction system described in any of the above, comprising the following steps: adding the pretreated brine into the nanofiltration device, removing the divalent impurity ions in the brine through the nanofiltration device; passing the brine after being removed by the nanofiltration device into the membrane distillation device, evaporating and concentrating the brine through the membrane distillation device; passing the brine after being evaporated and concentrated by the membrane distillation device into the adsorption device, and adsorbing the lithium ions in the brine through the resin; passing the brine after being adsorbed by the adsorption device into the crystallization device, and generating lithium carbonate slurry by heating and reacting in the crystallizer body.
[0015] The application has the following technical effects compared with the prior art: The application provides a brine lithium extraction crystallization device, a brine lithium extraction system and a process thereof. The first vibration element is arranged on the side wall of the crystallizer body, and the first vibration element is used to generate high-frequency micro-vibration of the crystallizer body. On the one hand, the high-frequency micro-vibration can generate strong fluid disturbance in the mixed material liquid of the brine and the sodium carbonate solution, strengthen the mixing and mass transfer between the brine and the sodium carbonate solution, destroy the concentration gradient between the solid-liquid phase and the internal material liquid, avoid the occurrence of a local supersaturation region, improve the uniformity of the crystal nucleation and growth, and on the other hand, the high-frequency micro-vibration can reduce the activation energy barrier required for nucleation, improve the nucleation efficiency of the crystal, and destroy the physical adsorption force and chemical bonding between the crystal nucleus and the inner wall of the crystallizer body, thereby preventing the adhesion and growth of the crystal on the inner wall of the crystallizer body, improving the heat transfer efficiency of the crystallizer, and improving the nucleation and growth efficiency of the crystal. Further, the spiral flow guide groove is arranged on the inner wall of the crystallizer body, and the structured flow channel design is used to guide the material liquid to form a spiral upward / downward flow field, thereby reducing the high-speed flow of the material liquid close to the stirring mechanism and the low-speed flow of the material liquid far from the stirring mechanism, reducing the stirring dead angle in the material liquid, making the material liquid mixing more uniform, further avoiding the occurrence of a local supersaturation region, improving the uniformity of the crystal nucleation and growth, and further preventing the adhesion and growth of the crystal on the inner wall of the crystallizer body, thereby improving the heat transfer efficiency of the crystallizer and the nucleation and growth efficiency of the crystal. BRIEF DESCRIPTION OF DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the application or in the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only show some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort.
[0017] Figure 1 Structure diagram of brine lithium extraction system for some embodiments of example two; Figure 2 Structure diagram of nanofiltration membrane for some embodiments of example two; Figure 3 Process flow diagram of brine lithium extraction for some embodiments of example three; In the figure: 1-nanofiltration device; 11-nanofiltration unit; 111-water inlet end of nanofiltration unit; 112-water outlet end of nanofiltration unit; 12-nanofiltration membrane; 13-second vibration element; 2-membrane distillation device; 21-membrane distillation unit; 211-water inlet end of membrane distillation unit; 212-water outlet end of membrane distillation unit; 3-adsorption device; 31-adsorption tank; 311-first liquid inlet; 312-eluent outlet; 4-crystallization device; 41-crystallizer body; 411-feeding part; 412-discharging part; 42-stirring mechanism; 43-first vibration element; 44-heating body; 5-outer shell; 6-controller; 71-cooling pump; 72-cooling liquid pipeline. DETAILED DESCRIPTION
[0018] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.
[0019] The present application aims to provide a crystallization device, a brine lithium extraction system and a process thereof, so as to solve the problems in the prior art, improve the uniformity of lithium salt crystal particle size, and improve the nucleation and growth efficiency of the crystal.
[0020] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.
[0021] Example one The present embodiment provides a crystallization device, such as Figure 1As shown, including crystallizer body 41, stirring mechanism 42 and the first vibration element 43, the crystallizer body 41 inside for containing slurry, the crystallizer body 41 inner wall on which is provided with spiral flow guide groove, the crystallizer body 41 is also provided with feed part 411 and discharge part 412, feed part 411 for entering sodium carbonate solution and brine, discharge part 412 for discharging lithium carbonate crystal slurry;Stirring mechanism 42 is arranged in the crystallizer body 41 inside, for stirring the slurry in the crystallizer body 41;The first vibration element 43 is arranged on the side wall of the crystallizer body 41, the first vibration element 43 can exert mechanical vibration on the crystallizer body 41.In the crystallizer body 41, brine and sodium carbonate solution react under the stirring action of stirring mechanism 42, and the crystal slurry containing lithium carbonate crystal is obtained, by setting the first vibration element 43 on the side wall of the crystallizer body 41, the first vibration element 43 makes the crystallizer body 41 produce tiny mechanical vibration, on the one hand, it can produce strong fluid disturbance in the mixed liquor of brine and sodium carbonate solution, strengthen the mixing and mass transfer between brine and sodium carbonate solution, destroy the concentration gradient between solid-liquid liquid phase and the internal material liquid, avoid the appearance of local supersaturation area, improve the uniformity of crystal nucleation and growth, on the other hand, high-frequency tiny vibration can reduce the activation energy barrier required for nucleation, improve the nucleation efficiency of crystal, and destroy the physical adsorption force and chemical bonding (such as hydrogen bond, van der waals force) between crystal nucleus and the inner wall of the crystallizer body 41, prevent the adhesion growth of crystal on the inner wall of the crystallizer body 41, thereby improving the heat transfer efficiency of the crystallizer, improving the nucleation and growth efficiency of crystal.Further, by setting spiral flow guide groove on the inner wall of the crystallizer body 41, the structured flow channel design is used to guide the material liquid to form spiral upward / downward flow field, reduce the high-speed flow of material liquid close to stirring mechanism 42, and the flow rate of material liquid far from stirring mechanism 42 is small, thereby reducing the stirring dead angle in the material liquid, making the material liquid mixing more uniform, thereby further avoiding the appearance of local supersaturation area, improving the uniformity of crystal nucleation and growth, and by improving the flow rate of material liquid close to the inner wall of the crystallizer body 41, further preventing the adhesion growth of crystal on the inner wall of the crystallizer body 41, thereby improving the heat transfer efficiency of the crystallizer, improving the nucleation and growth efficiency of crystal.
[0022] In some embodiments, the feeding part 411 comprises a jet nozzle extending into the inside of the crystallizer body 41 for feeding the brine into the crystallizer body 41, and a feeding port provided on the inner wall of the crystallizer body 41 for feeding the sodium carbonate solution into the crystallizer body 41. The brine is sprayed into the inside of the crystallizer body 41 through the jet nozzle, so that the brine and the sodium carbonate solution can fully react, further avoiding the formation of a local supersaturation area. In a uniform supersaturation environment, homogeneous nucleation is preferentially generated instead of heterogeneous nucleation, forming lithium carbonate crystal nuclei with controllable quantity and uniform size. The jet nozzle can also impact the inner wall of the crystallizer body 41, disturb and thin the deposition on the inner wall of the crystallizer body 41, further prevent the adhesion and growth of the crystals on the inner wall of the crystallizer body 41, thereby improving the heat transfer efficiency of the crystallizer and the nucleation and growth efficiency of the crystals.
[0023] In some embodiments, the first vibrating element 43 comprises at least one ultrasonic transducer and an ultrasonic generator connected thereto, and the ultrasonic transducer is arranged on the side wall of the crystallizer body 41 for applying high-frequency mechanical vibration to the crystallizer body 41. Compared with the conventional low-frequency mechanical vibration method, the high-frequency micro-amplitude generated by the ultrasonic wave only acts on the fluid and the crystal nucleus surface, does not damage the formed crystals, avoids affecting the uniformity of the crystal nucleation and growth, and the ultrasonic transducer can generate micro-jets directly impacting the crystallizer wall, break the adsorption force between the crystal nucleus and the inner wall of the crystallizer body 41, disturb and thin the deposition on the inner wall of the crystallizer body 41, and further prevent the adhesion and growth of the crystals on the inner wall of the crystallizer body 41.
[0024] In some embodiments, the crystallization device 4 further comprises a heating body 44 sleeved on the outer side of the side wall and the bottom wall of the crystallizer body 41, a heat-conducting medium is filled between the outer wall of the crystallizer body 41 and the inner wall of the heating body 44, and an electric heating wire is arranged in the heating body 41 to heat the slurry in the crystallizer body 41 through the heat-conducting medium, so as to uniformly water-bath heat the crystallizer body 41, maintain the uniformity of the temperature field in the slurry, ensure the consistency of the solubility of the solute in the slurry, avoid the rapid increase of the solubility caused by the local high temperature, thereby causing the insufficient supersaturation in the slurry and the slow crystal nucleation and growth, and avoid the rapid decrease of the solubility caused by the local low temperature, thereby causing the supersaturation exceeding the standard and the uncontrolled crystal nucleation and growth.
[0025] Example Two This embodiment provides a lithium extraction system from brine, which comprises a crystallization device 4, a lithium extraction device 5, and a lithium recovery device 6. Figures 1-2As shown, it comprises nanofiltration device 1, membrane distillation device 2, adsorption device 3 and crystallization device 4 in example one connected in turn. By setting first vibration element 43 on the side wall of crystallizer body 41, using first vibration element 43 to make crystallizer body 41 produce high-frequency micro-vibration, on the one hand, it can produce strong fluid disturbance in the mixed liquor of brine and sodium carbonate solution, strengthen the mixing and mass transfer between brine and sodium carbonate solution, destroy the concentration gradient between solid-liquid-liquid phase and inside the feed liquid, avoid the appearance of local supersaturation area, improve the uniformity of crystal nucleation and growth, on the other hand, high-frequency micro-vibration can reduce the activation energy barrier required for nucleation, improve the nucleation efficiency of crystal, and destroy the physical adsorption force and chemical bonding (such as hydrogen bond, van der Waals force) between crystal nucleus and inner wall of crystallizer body 41, prevent the adhesion and growth of crystal on the inner wall of crystallizer body 41, thereby improving the heat transfer efficiency of crystallizer and the nucleation and growth efficiency of crystal. Further, by opening spiral flow guide grooves on the inner wall of crystallizer body 41, using structured flow channel design to guide the formation of spiral upward / downward flow field of feed liquid, reduce the high-speed flow of feed liquid close to stirring mechanism 42, and the flow rate of feed liquid far from stirring mechanism 42 is smaller, thereby reducing the stirring dead angle in the feed liquid, making the feed liquid mixing more uniform, thereby further avoiding the appearance of local supersaturation area, improving the uniformity of crystal nucleation and growth, and by increasing the flow rate of feed liquid close to the inner wall of crystallizer body 41, further preventing the adhesion and growth of crystal on the inner wall of crystallizer body 41, thereby improving the heat transfer efficiency of crystallizer and the nucleation and growth efficiency of crystal.
[0026] Specifically, according to the flow order of brine, nanofiltration device 1, membrane distillation device 2, adsorption device 3 and crystallization device 4 are sequentially integrated in outer shell 5 from top to bottom, forming a three-dimensional spatial layout, reducing space occupation.
[0027] In some embodiments, the nanofiltration device 1 comprises a plurality of nanofiltration units 11 connected in series, each nanofiltration unit 11 is provided with a nanofiltration membrane 12 for passing the brine, at least part of the edge of the nanofiltration membrane 12 is connected with a second vibration element 13, the second vibration element 13 can vibrate the nanofiltration membrane 12, by making the brine pass through the nanofiltration membrane 12, the divalent impurity ions (calcium ions, magnesium ions, etc.) in the brine are intercepted, for the divalent cations (calcium ions and magnesium ions), the two positive charges of such ions are strongly attracted by the negative charge on the surface of the nanofiltration membrane 12, and it is difficult to penetrate the nanofiltration membrane 12, and according to the Donnan equilibrium, the migration of high-valence cations in the brine is strictly limited (to maintain electrical neutrality, the penetration rate of high-valence cations is much lower than that of monovalent cations), in contrast, monovalent cations (i.e. lithium ions) have low charge density and weak electrostatic attraction, and are more likely to pass through the nanofiltration membrane 12; for divalent anions (sulfate ions, carbonate ions): such ions are repelled by the negative charge on the membrane surface and are difficult to approach the membrane pore entrance of the nanofiltration membrane 12, thereby achieving interception; further, by connecting the second vibration element 13 to at least part of the edge of the nanofiltration membrane 12, the nanofiltration membrane 12 is vibrated by the second vibration element 13, avoiding the blockage of the membrane pores of the nanofiltration membrane 12 by the intercepted divalent impurity ions, thereby maintaining the stability of the membrane flux of the nanofiltration membrane 12.
[0028] Specifically, each nanofiltration unit 11 has a water inlet end 111 of a nanofiltration unit and a water outlet end 112 of a nanofiltration unit, in the direction of the brine flow, the water inlet end 111 of the first nanofiltration unit is used to pass the pretreated brine, the water outlet end 112 of the last nanofiltration unit is in communication with the water inlet end 111 of the next nanofiltration unit, so as to realize the series connection between the nanofiltration units 11, and the water outlet end 112 of the last nanofiltration unit is in communication with the membrane distillation device 2, so as to pass the intercepted brine into the membrane distillation device 2. Preferably, the number of nanofiltration units 11 is three.
[0029] Specifically, the pretreatment process of the brine mainly includes: 1. filtering out large-particle impurities such as silt, clay, microbial floc, and gypsum microcrystals in the brine, so as to avoid direct blockage of the nanofiltration membrane pores or damage to the membrane surface; 2. treating natural organic matter and microorganisms in the brine through oxidation reaction and activated carbon adsorption; 3. adjusting the pH value and temperature of the brine to the optimal operating range of the nanofiltration membrane 12, so as to ensure the stable performance of the nanofiltration membrane 12.
[0030] In some embodiments, the membrane distillation device 2 comprises a plurality of membrane distillation units 21 connected in series, each of the membrane distillation units 21 is provided with a heater, a hydrophobic microporous membrane and a cold side circulation unit, the heater is used to heat the brine; the hydrophobic microporous membrane can divide the membrane distillation unit 21 into a hot side and a cold side, and is used to separate the heated brine flowing through the hot side from the fluid flowing through the cold side; the fluid flowing through the cold side is provided and cooled to form a vapor pressure difference on both sides of the hydrophobic microporous membrane, so that the water vapor in the hot side passes through the hydrophobic microporous membrane to the cold side. The inside of the membrane distillation unit 21 is divided into a hot side and a cold side by a hydrophobic porous membrane. By providing a fluid with a lower temperature in the cold side, a temperature gradient is generated between the two sides of the membrane surface, so that a vapor pressure difference is generated on both sides of the hydrophobic porous membrane. The vapor pressure difference forces the water vapor in the hot side to diffuse into the cold side through the membrane pores of the hydrophobic microporous membrane and condense into liquid, while the brine in the hot side is blocked by the hydrophobic microporous membrane, thereby realizing the evaporation and concentration of the brine.
[0031] Specifically, each of the membrane distillation units 21 has a water inlet end 211 of a membrane distillation unit and a water outlet end 212 of a membrane distillation unit. According to the flow direction of the brine, the water inlet end 211 of the first membrane distillation unit is used to receive the brine discharged from the water outlet end 112 of the last nanofiltration unit. The water outlet end 212 of the last membrane distillation unit is in communication with the water inlet end 211 of the next membrane distillation unit to realize the series connection between the membrane distillation units 21. The water outlet end 212 of the last membrane distillation unit is in communication with the adsorption device 3 to introduce the brine concentrated by evaporation into the adsorption device 3. Preferably, the number of membrane distillation units 21 is two.
[0032] In some embodiments, the adsorption device 3 comprises an adsorption tank 31, the adsorption tank 31 is provided with a first liquid inlet 311, a second liquid inlet, an eluent outlet 312 and a tail brine outlet. A resin bed is supported by a grid in the adsorption tank 31. The brine discharged from the hot side of the membrane distillation unit 21 is introduced into the adsorption tank 31 through the first liquid inlet 311, flows through the resin bed, and the lithium ions are adsorbed by the resin bed. The tail brine after adsorption is discharged through the tail brine outlet. Then the eluent is introduced into the adsorption tank 31 through the second liquid inlet to flush the resin bed with the eluent (usually hydrochloric acid solution or sulfuric acid solution), so as to desorb the lithium ions in the resin bed into the eluent, thereby obtaining a lithium-rich liquid, and discharging the lithium-rich liquid to the crystallization device 4 through the eluent outlet 312.
[0033] In some embodiments, the first inlet 311 is located at the top of the adsorption tank 31, allowing the brine to flow from top to bottom through the resin bed, enabling the resin bed to fully adsorb lithium ions from the brine. The second inlet is located at the bottom of the adsorption tank 31, allowing the eluent to immerse the resin bed from bottom to top, ensuring full contact with the resin bed and desorbing lithium ions from it, thereby increasing the concentration of the lithium-rich solution. Furthermore, the tail brine outlet and the first inlet 311 are connected by a first reflux branch, allowing the tail brine discharged through the tail brine outlet to flow back into the adsorption tank 31 through the first inlet 311, thereby reducing the lithium ion content in the tail brine and further increasing the concentration of the lithium-rich solution.
[0034] In some embodiments, temperature sensors are provided in each membrane distillation unit 21 and the crystallization device 4 to monitor the temperature of the hot and cold sides inside each membrane distillation unit 21, and to control the reaction temperature of the slurry in the crystallizer body 41 by the temperature sensor in the crystallization device 4.
[0035] In some embodiments, the brine lithium extraction system further includes a filtration device with an inlet and an outlet. A solid-liquid separation screen is installed inside the filtration device. The inlet of the filtration device is connected to the outlet 412 of the crystallizer body 41 to receive lithium carbonate slurry. The lithium carbonate crystals are filtered through the solid-liquid separation screen inside the filtration device, and the filtered slurry is discharged through the outlet. Furthermore, the outlet is connected to the inlet 111 of the nanofiltration unit of the first nanofiltration unit 11 via a second reflux branch to circulate the filtered slurry for lithium extraction.
[0036] In some embodiments, the brine lithium extraction system also includes a controller 6, which is connected to the nanofiltration unit 1, the membrane distillation unit 2, the adsorption unit 3, and the crystallization unit 4 respectively. The controller 6 controls and observes the working status of the nanofiltration unit 1, the membrane distillation unit 2, the adsorption unit 3, and the crystallization unit 4. Furthermore, the controller 6 is also connected to each temperature sensor to adjust the working temperature of the membrane distillation unit 2 and the crystallization unit 4 according to the temperature data monitored by each temperature sensor.
[0037] In some embodiments, the brine lithium extraction system also includes a cooling device, which includes a cooling pump 71 and a coolant line 72. The coolant line 72 is arranged in the cold-side circulation unit of each membrane distillation unit 21 to provide and cool the fluid flowing through the cold side to the cold-side circulation unit. The cooling pump 71 is used to drive the coolant circulation flow in the coolant line 72.
[0038] Example 3 This embodiment provides a brine lithium extraction process using the brine lithium extraction system described in Embodiment 2, such as... Figure 3 As shown, it includes the following steps: The pretreated brine is added into the nanofiltration device 1, and the brine passes through the nanofiltration membrane 12 to intercept the divalent impurity ions in the brine; the second vibration element 13 is connected to at least part of the edge of the nanofiltration membrane 12, and the nanofiltration membrane 12 is vibrated by the second vibration element 13, so that the intercepted divalent impurity ions do not block the membrane holes of the nanofiltration membrane 12, thereby maintaining the stability of the membrane flux of the nanofiltration membrane 12; The brine intercepted by the nanofiltration device 1 is introduced into the membrane distillation device 2, a temperature gradient is generated between the two sides of the membrane by providing a fluid with a lower temperature on the cold side, so that a vapor pressure difference is generated on the two sides of the hydrophobic porous membrane, the vapor pressure difference forces the water vapor on the hot side to diffuse into the cold side through the membrane holes of the hydrophobic microporous membrane and condense into liquid, and the brine on the hot side is intercepted by the hydrophobic microporous membrane, so that the evaporation and concentration of the brine are realized; The brine after evaporation and concentration by the membrane distillation device 2 is introduced into the adsorption device 3, the brine discharged from the membrane distillation unit 21 is introduced into the adsorption tank 31 through the first liquid inlet 311, flows through the resin bed layer, the lithium ions are adsorbed by the resin bed layer, and the adsorbed tail brine is discharged through the tail brine outlet, then the eluent is introduced into the adsorption tank 31 through the second liquid inlet, the lithium ions in the resin bed layer are desorbed into the eluent by washing the resin bed layer with the eluent (usually hydrochloric acid solution or sulfuric acid solution), so that the lithium-rich brine is obtained, and the lithium-rich brine is discharged through the eluent outlet 312 into the crystallization device 4; The brine after adsorption by the adsorption device 3 is introduced into the crystallization device 4, and in the crystallizer body 41, the brine reacts with the sodium carbonate solution under the stirring action of the stirring mechanism 42 to obtain a crystal slurry containing lithium carbonate crystals, the first vibration element 43 is arranged on the side wall of the crystallizer body 41, and the crystallizer body 41 is vibrated by the first vibration element 43 to avoid local supersaturation and improve the uniformity of crystal nucleation and growth, the heat transfer efficiency of the crystallizer, and the efficiency of crystal nucleation and growth.
[0039] In the present application, specific examples are used to illustrate the principles and implementation methods of the present application. 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 and application range can be changed. In summary, the content of the present application should not be understood as a limitation.
Claims
1. A crystallization apparatus, characterized by: The application relates to a crystallization device. The crystallization device comprises a crystallizer body, a stirring mechanism and a first vibration element. The crystallizer body is internally used for containing slurry, and a spiral flow guide groove is arranged on the inner wall of the crystallizer body. The crystallizer body is further provided with a feeding part and a discharging part. The feeding part is used for feeding sodium carbonate solution and brine.
2. The crystallization apparatus of claim 1, wherein: The discharging part is used for discharging lithium carbonate slurry. The stirring mechanism is arranged in the crystallizer body and used for stirring the slurry in the crystallizer body. The first vibration element is arranged on the side wall of the crystallizer body and can apply mechanical vibration to the crystallizer body.
3. The crystallization apparatus of claim 2, wherein: The feeding part comprises a jet nozzle and a feeding port.
4. The crystallization apparatus of claim 3, wherein: The jet nozzle extends into the crystallizer body and is used for feeding the brine into the crystallizer body.
5. A brine lithium extraction system characterized by: The feeding port is arranged on the inner wall of the crystallizer body and is used for feeding the sodium carbonate solution into the crystallizer body.
6. The brine-based lithium extraction system of claim 5, wherein: The first vibration element comprises at least one ultrasonic transducer and an ultrasonic generator connected with the ultrasonic transducer.
7. The brine-based lithium extraction system of claim 6, wherein: The ultrasonic transducer is arranged on the side wall of the crystallizer body and is used for applying mechanical vibration to the crystallizer body. The crystallization device further comprises a heating body. The heating body is sleeved on the outer side of the side wall and the bottom wall of the crystallizer body. A heat-conducting medium is filled between the outer wall of the crystallizer body and the inner wall of the heating body. An electric heating wire is arranged in the heating body.
8. The brine-based lithium extraction system of claim 7, wherein: The crystallization device further comprises a nanofiltration device, a membrane distillation device, an adsorption device and a crystallization device. The nanofiltration device comprises a plurality of nanofiltration units connected in series. Each nanofiltration unit is provided with a nanofiltration membrane for passing through brine. At least part of the edge of the nanofiltration membrane is connected with a second vibration element. The second vibration element can vibrate the nanofiltration membrane. The membrane distillation device comprises a plurality of membrane distillation units connected in series. Each membrane distillation unit is provided with a heater, a hydrophobic microporous membrane and a cold side circulation unit. The heater is used for heating the brine. The hydrophobic microporous membrane can divide the membrane distillation unit into a hot side and a cold side and is used for separating the brine heated by the heater flowing through the hot side from the fluid flowing through the cold side. The cold side circulation unit is used for providing and cooling the fluid flowing through the cold side to form a vapor pressure difference on both sides of the hydrophobic microporous membrane so that the water vapor of the hot side passes through the hydrophobic microporous membrane to reach the cold side. The adsorption device comprises an adsorption tank. The adsorption tank is provided with a first liquid inlet, a second liquid inlet, an eluent outlet and a tail brine outlet. A resin bed layer is supported by a grid in the adsorption tank. The first liquid inlet is used for receiving the brine discharged from the hot side of the membrane distillation unit. The resin bed layer is used for adsorbing lithium ions. The tail brine outlet is used for discharging the adsorbed tail brine. The second liquid inlet is used for receiving eluent for flushing the resin bed layer. The eluent outlet is used for discharging the eluent into the crystallization device.
9. The brine-based lithium extraction system of claim 5, wherein: Also included is a controller in signal connection with the nanofiltration device, the membrane distillation device, the adsorption device, and the crystallization device, respectively.
10. A brine lithium extraction process employing the brine lithium extraction system of any one of claims 5-9, characterized in that: The method comprises the following steps: The pretreated brine is added into the nanofiltration device to remove divalent impurity ions in the brine by the nanofiltration device; The brine after the nanofiltration device is added into the membrane distillation device to evaporate and concentrate the brine by the membrane distillation device; The brine after the membrane distillation device is added into the adsorption device, and lithium ions in the brine are adsorbed by the resin; The brine after the adsorption device is added into the crystallization device, and lithium carbonate crystal slurry is generated by heating and reaction in the crystallizer body.