A method for lithium extraction from brine by electrochemical adsorption and its application

Abstract

This disclosure provides a method for lithium extraction from brine by electrochemical adsorption and its application. The method includes: placing an electrode containing a low-lithium lithium ion carrier as the cathode electrode in the middle of the brine; adding a lithium ion adsorbent to the brine to enrich the lithium ions in the brine; centrifugally stirring the brine and energizing the electrode to obtain an electrode containing a lithium-rich lithium ion carrier. This disclosure utilizes a lithium ion adsorbent to enrich lithium ions in the brine pool, cleverly employing external force to move the lithium ion adsorbent material, transporting the lithium ion adsorbent to the vicinity of the electrode to form a lithium-rich region. This significantly shortens the distance from the lithium ions to the electrode, thereby improving lithium extraction efficiency and greatly saving extraction time.

Description

Technical Field

[0001] This disclosure pertains to the field of lithium resource extraction, such as a method for extracting lithium from brine by electrochemical adsorption and its application. Background Technology

[0002] With the rapid development of new energy vehicles, electronic devices, and energy storage technologies, the application of lithium in the field of new energy materials has received high attention. Global lithium resources are mainly found in salt lake brines and ores; of the currently proven lithium resources, salt lake brines account for 58%, and lithium concentrate accounts for 26%. With the rapid development of the new energy vehicle industry, the demand for lithium resources is increasing daily. However, due to factors such as environmental protection, transportation, and technology, China's domestic production of lithium from ore and salt lakes is insufficient to meet market demand. At present, lithium extraction still mainly relies on primary lithium ore. How to accelerate the development and recovery of secondary lithium resources from lithium-containing solutions has become crucial for the healthy, sustainable, and rapid development of the lithium salt industry.

[0003] CN1724372A discloses a method for producing lithium carbonate, magnesium oxide, and hydrochloric acid from high-magnesium lithium-containing brine. The process flow includes spray drying, calcination, water washing, evaporation and concentration, and precipitation to obtain lithium carbonate product. This method utilizes a high temperature of up to 1200℃ to calcine the lithium-containing magnesium brine, causing it to decompose into magnesium oxide at high temperature, while simultaneously recovering lithium carbonate.

[0004] CN101654741A discloses a method for separating and recovering lithium and cobalt from lithium-ion batteries. Specifically, it discloses a method in which a sample treated with lithium magnesium manganese oxide is used as a lithium-ion adsorbent for lithium-containing filtrate after acid dissolution of waste lithium-ion batteries. This method is combined with an immersion ultrafiltration membrane element, which allows lithium ions to be embedded in the interstices of the ion sieve lattice to reach the maximum adsorption capacity. Finally, the adsorbent is eluted with an acid solution to achieve the purpose of recovering lithium.

[0005] The lithium recovery methods disclosed above are complex, the equipment is susceptible to corrosion from acidic gases or liquids, they can cause environmental pollution, and they consume a lot of energy.

[0006] Therefore, it is urgent to provide a clean and efficient lithium resource recycling process that minimizes energy consumption and emissions of related chemical raw materials or auxiliary materials during the lithium resource recycling process, so that lithium resource recycling complies with current energy conservation and environmental protection policies. Summary of the Invention

[0007] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0008] This disclosure provides a method for lithium extraction from brine by electrochemical adsorption and its application, which solves the problems of long extraction time, low efficiency, complex methods and high energy consumption in related technologies.

[0009] To achieve this objective, the present disclosure adopts the following technical solution:

[0010] One objective of this disclosure is to provide a method for extracting lithium from brine by electrochemical adsorption, the method comprising:

[0011] An electrode with a low lithium-ion carrier is placed in the middle of the brine as the cathode electrode. After adding a lithium-ion adsorbent to the brine, the lithium ions in the brine are enriched. The brine is stirred centrifugally and the electrode is energized to obtain an electrode containing a lithium-rich lithium-ion carrier.

[0012] This embodiment uses a lithium-ion adsorbent to enrich lithium ions in a brine pool. External force is used to move the lithium-ion adsorbent material, transporting it to the vicinity of the electrode to form a lithium-rich region. This greatly shortens the distance from the lithium ions to the electrode, thereby improving lithium extraction efficiency and significantly saving extraction time.

[0013] In this embodiment, centripetal stirring is achieved using a centripetal stirrer, which has two stirrers positioned on either side of the cathode electrode. When the centripetal stirrer is turned on, the two stirrers stir towards the electrode, thereby achieving the enrichment of lithium-ion adsorbent.

[0014] In this embodiment, the lithium-ion adsorbent added to the brine solution is a physical adsorbent, which can adsorb without the need for electricity. However, the cathode electrode uses chemical adsorption. When electricity is applied, chemical adsorption has a stronger adsorption capacity for lithium ions. Therefore, the lithium-ion carrier in a lithium-deficient state can better enrich the surrounding lithium ions after electricity is applied.

[0015] As an optional technical solution in the embodiments of this disclosure, the brine includes any one or a combination of at least two of salt lake brine, underground brine, or concentrated seawater. Typical but non-limiting examples of such combinations include: a combination of salt lake brine and underground brine, a combination of underground brine and concentrated seawater, or a combination of salt lake brine and concentrated seawater, etc.

[0016] The concentrations of each element in the brine solution described in this embodiment include: Li + The concentration range is 0.1-0.3 g / L, Mg + The concentration range is 15.0-25.0 g / L, K + The concentration range is 0.5-1.0 g / L, SO4 2- The concentration range was 20.5-21.0 g / L and Cl - The concentration range is 60.0-64.0 g / L.

[0017] The Li +The concentration can be 0.1 g / L, 0.12 g / L, 0.14 g / L, 0.16 g / L, 0.18 g / L, 0.2 g / L, 0.22 g / L, 0.24 g / L, 0.26 g / L, 0.28 g / L, or 0.3 g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] The Mg + The concentration can be 15.0 g / L, 16.0 g / L, 17.0 g / L, 18.0 g / L, 19.0 g / L, 20.0 g / L, 21.0 g / L, 22.0 g / L, 23.0 g / L, 24.0 g / L, or 25.0 g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] The K + The concentration can be 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L or 1.0 g / L, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] The SO4 2- The concentration can be 20.5 g / L, 20.6 g / L, 20.7 g / L, 20.71 g / L, 20.8 g / L, 20.9 g / L or 21.0 g / L, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] The Cl - The concentration can be 60.0 g / L, 60.5 g / L, 61.0 g / L, 61.5 g / L, 62.0 g / L, 62.1 g / L, 62.18 g / L, 62.2 g / L, 62.3 g / L, 62.4 g / L, 62.5 g / L, 62.6 g / L, 62.7 g / L, 62.8 g / L, 62.9 g / L, or 63.0 g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] In one embodiment, the concentrations of each element in the brine solution include: Li + The concentration was 0.2 g / L, Mg + The concentration was 23.0 g / L, K + The concentration range is 0.91 g / L, SO4 2+ The concentration range was 20.71 g / L and Cl - The concentration range is 62.18 g / L.

[0023] In one embodiment, the lithium-ion carrier includes any one or a combination of at least two of LiMn2O4, LiV3O8, or LiFePO4, wherein typical but non-limiting examples of the combination include combinations of LiMn2O4 and LiV3O8, combinations of LiV3O8 and LiFePO4, or combinations of LiMn2O4 and LiFePO4, etc.

[0024] As an optional technical solution in the embodiments of this disclosure, the lithium-ion adsorbent is a reversibly bound lithium-ion adsorbent.

[0025] In one embodiment, the lithium-ion adsorbent comprises an Al2O3 adsorbent and / or a SiO2 adsorbent.

[0026] As an optional technical solution in the embodiments of this disclosure, the enrichment time is 30 to 60 minutes. The time can be 30 minutes, 35 minutes, 40 minutes, 45 minutes, 55 minutes, or 60 minutes, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] In one embodiment, the centripetal stirring speed is 80 to 100 rpm, wherein the speed can be 80 rpm, 85 rpm, 90 rpm, 85 rpm or 100 rpm, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0028] In one embodiment, the centripetal stirring time is 20 to 30 minutes, wherein the time can be 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, or 30 minutes, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0029] In this embodiment, centripetal stirring causes the lithium-ion adsorbent in the brine to accumulate in the central region, forming a lithium-ion enrichment region around the electrode.

[0030] As an optional technical solution in the embodiments of this disclosure, the voltage of the power supply is 1 to 1.5V, wherein the voltage can be 1V, 1.1V, 1.2V, 1.3V, 1.4V or 1.5V, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] In one embodiment, the energizing time is 1.5 to 2.5 hours, wherein the time can be 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, or 2.5 hours, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] As an optional technical solution in the embodiments of this disclosure, the power is turned off after being turned on, and the brine is stirred to disperse the lithium ions in the brine.

[0033] In this embodiment, the power-on and power-off operations can be repeated cyclically, and the lithium-ion carrier material and lithium-ion adsorbent material on the electrode can be recycled with a lifespan of 500 to 1000 times or more, which greatly reduces the cost of lithium resource recycling.

[0034] In this embodiment of the present disclosure, an external force is applied to centrifuge stirring, causing the lithium ion carrier to disperse.

[0035] As an optional technical solution in the embodiments of this disclosure, the electrode containing the lithium-rich lithium-ion carrier is used as the anode electrode.

[0036] In this embodiment, a lithium-ion carrier electrode in a lithium-rich state is placed in a solution from which lithium ions are to be collected, causing it to oxidize and release lithium ions. The electrode then transitions to a lithium-poor state and enters the next cycle.

[0037] As an optional technical solution in the embodiments of this disclosure, the anode electrode is placed in a NaCl solution.

[0038] As an optional technical solution in the embodiments of this disclosure, the method includes:

[0039] A lithium-ion carrier in a lithium-deficient state is placed as the cathode electrode in the middle of the brine. A lithium-ion adsorbent is added to the brine, and the brine is centripetally stirred at a speed of 80-100 rpm / min for 20-30 min. The electrode is then energized with a voltage of 1-1.5V for 1.5-2.5 h to obtain a lithium-rich lithium-ion carrier.

[0040] A second objective of this disclosure is to provide an application of the method as described in one objective, the method being applied to the field of lithium resource extraction.

[0041] This disclosure has the following beneficial effects:

[0042] This disclosure employs two adsorbents for lithium extraction. The lithium-ion adsorbent, while acting as a lithium-ion carrier to transport lithium ions to the area around the electrode, also filters out some cationic impurities, resulting in a higher lithium-ion concentration around the electrode. After further electrochemical lithium extraction, the concentration of cationic impurities (such as magnesium ions) is significantly reduced. Furthermore, this method of lithium extraction from brine via electrochemical adsorption exhibits high lithium extraction efficiency, significantly reducing extraction time, and achieving a lithium-ion recovery rate exceeding 99%.

[0043] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0044] The accompanying drawings are provided to further understand the technical solutions herein and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions herein and do not constitute a limitation on the technical solutions herein.

[0045] Figure 1 This is a schematic diagram of the method for extracting lithium from brine in Embodiments 1-2 of this disclosure.

[0046] In the diagram: 1-Centrifugal stirrer; 2-Ion adsorbent. Detailed Implementation

[0047] The technical solutions of this disclosure will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of this disclosure and should not be construed as specific limitations thereof.

[0048] Example 1

[0049] This embodiment provides a method such as Figure 1 The method for extracting lithium from brine shown includes:

[0050] (1) 0.5 liters of the brine solution (Mg) to be recovered is introduced into the cathode area of ​​the electrolytic cell. 2+ Concentration of 20 g / L, Li + With a concentration of 0.2 g / L, the same amount of NaCl solution was passed through the anode area to electrolytically delithilate the electrode containing LiMn2O4 lithium ion carrier into a lithium-poor state. Then, the electrode was inserted into the middle of the cathode area. Al2O3 adsorbent was added to the brine to make it evenly distributed in the brine pool, and the lithium ions in the brine pool were enriched for 30 min.

[0051] (2) At the bottom of the brine tank in the cathode area, a stirrer is used to perform centripetal stirring at a speed of 80 rpm / min for 10 min to make the lithium-rich manganese oxide lithium ion sieve move towards the central area and gather around the electrode to form a lithium ion enrichment area.

[0052] (3) The electrode is energized with a voltage of 1.2V for 2 hours. Under electrochemical action, the electrode adsorbs lithium ions in the enriched area and regenerates lithium oxide lithium ion sieves in a lithium-poor state.

[0053] (4) Disconnect the power supply, switch the stirrer to centrifugal stirring mode, and repeat steps (1) and (2) to disperse the lithium manganese oxide ion sieve.

[0054] (5) Replace the lithium-rich electrode with the anode region, and replace the cathode region with the lithium-poor electrode. When the voltage is 1.2V, the electrodes in the anode and cathode regions work at the same time, so that the lithium-rich electrode is oxidized under the anode current, releasing lithium ions and turning into a lithium-poor state. The lithium-poor electrode adsorbs lithium ions at the cathode. This cycle is repeated 20 times.

[0055] (6) Mix the lithium-containing solution after removing the precipitate with Na2CO3 powder, and heat to 60℃, so that Li + The lithium ion recovery rate was calculated based on the precipitation of Li2CO3 crystals. The concentration of magnesium ions in the brine after multiple cycles was also measured according to HJ776-2015 "Determination of 32 Elements in Water Quality - Inductively Coupled Plasma Atomic Emission Spectrometry".

[0056] Example 2

[0057] This embodiment provides a method such as Figure 1 The method for extracting lithium from brine shown includes:

[0058] (1) 0.5 liters of the brine solution (Mg) to be recovered is introduced into the cathode area of ​​the electrolytic cell. 2+ Concentration of 20 g / L, Li + The electrode sheet containing the LiV3O8 lithium ion carrier (concentration of 0.2 g / L) was delithiated by electrolysis to become lithium-poor. Then the electrode sheet was inserted into the middle of the cathode area containing brine in the electrolytic cell. SiO2 adsorbent was added to the brine to make it evenly distributed in the brine pool, and the lithium ions in the brine pool were enriched for 60 min.

[0059] (2) At the bottom of the brine tank in the cathode area, a stirrer is used to perform centripetal stirring at a speed of 100 rpm / min for 8 min, so that the lithium-rich vanadium oxide lithium ion sieve moves towards the central area and gathers around the electrode to form a lithium ion enrichment area.

[0060] (3) The electrode is energized with a voltage of 1.2V for 2 hours. Under electrochemical action, the electrode adsorbs lithium ions in the enriched region and regenerates lithium oxide lithium ion sieves in a lithium-poor state.

[0061] (4) Then turn off the power, switch the stirrer to centrifugal stirring mode, and repeat steps (1) and (2) to disperse the vanadium oxide lithium ion sieve.

[0062] (5) Replace the lithium-rich electrode with the anode region, and replace the cathode region with the lithium-poor electrode. When the voltage is 1.2V, the electrodes in the anode and cathode regions work at the same time, so that the lithium-rich electrode is oxidized under the anode current, releasing lithium ions and turning into a lithium-poor state. The lithium-poor electrode adsorbs lithium ions at the cathode. This cycle is repeated 20 times.

[0063] (6) The collected lithium-containing solution after removing the precipitate is mixed with Na2CO3 powder and heated to 60°C to allow the Li to react. + The lithium ion recovery rate was calculated based on the precipitation of Li₂CO₃ crystals. The concentration of magnesium ions in the brine after multiple cycles was also measured: the concentration was determined according to HJ776-2015 "Determination of 32 Elements in Water Quality - Inductively Coupled Plasma Atomic Emission Spectrometry," and the magnesium ion concentration in the brine solution was calculated.

[0064] Example 3

[0065] In this embodiment, the only difference is that the time for lithium ion enrichment by the lithium ion adsorbent in step (1) is replaced with 20 min, and all other conditions are the same as in Example 1.

[0066] Example 4

[0067] In this embodiment, the only difference is that the lithium ion enrichment time of the lithium ion adsorbent in step (1) is replaced with 80 min, and all other conditions are the same as in Example 1.

[0068] Comparative Example 1

[0069] Compared with Example 1, this comparative example does not include the addition of a reversibly bound lithium-ion adsorbent or external force.

[0070] (1) 0.5 liters of the brine solution (Mg) to be recovered is introduced into the cathode area of ​​the electrolytic cell. 2+ Concentration of 20 g / L, Li + The electrode sheet containing the lithium ion carrier LiMn2O4 (concentration of 0.2 g / L) is electrolyzed to delithiate into a lithium-poor state, and then the electrode sheet is inserted into the middle of the cathode region containing brine in the electrolytic cell.

[0071] (2) The electrode is energized with a voltage of 1.2V for 2 hours, and lithium ions are adsorbed on the electrode under electrochemical action;

[0072] (3) Replace the lithium-rich electrode with the anode region, and replace the cathode region with the lithium-poor electrode. When the voltage is 1.2V, the electrodes in the anode and cathode regions work at the same time, so that the lithium-rich electrode is oxidized under the anode current, releasing lithium ions and turning into a lithium-poor state. The lithium-poor electrode adsorbs lithium ions at the cathode. This cycle is repeated 20 times.

[0073] (4) The collected lithium-containing solution after removing the precipitate is mixed with Na2CO3 powder and heated to 60°C to allow the Li to react. + The lithium ion recovery rate was calculated based on the precipitation of Li2CO3 crystals.

[0074] Comparative Example 2

[0075] Compared with Example 1, this comparative example uses lithium ion adsorbent to directly enrich lithium ions.

[0076] (1) 0.5 liters of the brine solution (Mg) to be recovered is introduced into the cathode area of ​​the electrolytic cell. 2+ Concentration of 20 g / L, Li + Al2O3 adsorbent (concentration of 0.2 g / L) is added to the brine to ensure uniform distribution in the brine tank and to enrich the lithium ions in the brine tank.

[0077] (2) Place the lithium ion sieve enriched with lithium ions in (1) into the solution of lithium ions to be collected, add hydrogen peroxide to oxidize the lithium ion sieve and release lithium ions, and repeat this cycle 20 times.

[0078] (3) The collected lithium-containing solution after removing the precipitate is mixed with Na2CO3 powder and heated to 60°C to allow the Li to react. + The lithium ion recovery rate was calculated based on the precipitation of Li2CO3 crystals.

[0079] The lithium-ion recovery rates after 20 lithium extraction cycles in Examples 1-4 and Comparative Examples 1-2 are shown in Table 1.

[0080] Table 1

[0081]

[0082] As shown in Table 1, and by comparing Examples 1 and 3-4, it can be seen that when the adsorbent is added to the solution and lithium ions in the brine pool are enriched before centrifugal stirring, if the enrichment time is too short, the lithium ion recovery rate will decrease, and if the enrichment time is too long, the lithium ion recovery rate will not be improved.

[0083] As can be seen from the comparison between Example 1 and Comparative Examples 1-2, the lithium extraction method disclosed herein significantly improves the lithium-ion recovery rate after 20 lithium extraction cycles.

[0084] The examples and comparative examples show that the removal of magnesium ion impurities during the lithium extraction process has a certain positive effect.

Claims

1. A method for extracting lithium from brine by electrochemical adsorption, the method comprising: An electrode containing a lithium-deficient lithium ion carrier is placed in the middle of a brine as the cathode electrode. A lithium-ion adsorbent is added to the brine to enrich the lithium ions. After enrichment, the brine is centripetally stirred, and the electrode is energized to obtain an electrode containing a lithium-rich lithium ion carrier. The lithium-ion adsorbent is a physical adsorbent, including Al2O3 and / or SiO2 adsorbents. The electrode with the lithium-deficient lithium ion carrier undergoes chemical adsorption after energization. The electrode containing the lithium-rich lithium ion carrier serves as the anode electrode; the anode electrode is placed in a NaCl solution.

2. The method according to claim 1, wherein, The brine includes any one or a combination of at least two of the following: salt lake brine, underground brine, or concentrated seawater.

3. The method according to claim 1, wherein, The lithium ion carrier includes any one or a combination of at least two of LiMn2O4, LiV3O8, or LiFePO4.

4. The method according to claim 1, wherein, The enrichment time is 30-60 minutes.

5. The method according to claim 1, wherein, The centrifugal stirring speed is 80~100 rpm.

6. The method according to claim 1, wherein, The centripetal stirring time is 20-30 minutes.

7. The method according to claim 1, wherein, The voltage applied is 1~1.5V.

8. The method according to claim 7, wherein, The energizing time is 1.5~2.5h.

9. The method according to claim 1, wherein, The power is turned off after being turned on, and the brine is stirred.

10. The method according to claim 1, wherein, The method includes: A lithium-ion carrier in a lithium-deficient state is placed as the cathode electrode in the middle of the brine. A lithium-ion adsorbent is added to the brine to enrich the lithium ions in the brine. After enrichment, the brine is centripetally stirred at a speed of 80-100 rpm for 20-30 minutes, and the electrode is energized with a voltage of 1-1.5V for 1.5-2.5 hours to obtain a lithium-rich lithium-ion carrier.

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