Lithium extraction device and lithium extraction method

Abstract

This application discloses a lithium extraction device and method, which belongs to the technical field of lithium extraction from salt lakes. The device includes an electrolytic cell and a lithium ion screen. The electrolytic cell includes a negative electrode area, a positive electrode area, and a lithium-containing liquid injection area. The negative electrode area, the lithium-containing liquid injection area, and the positive electrode area are separated by a cation exchange membrane and an anion exchange membrane in sequence. The negative electrode area and the positive electrode area are respectively used to connect to the negative electrode and the positive electrode of the power supply. During use, there is electrolyte in both the negative electrode area and the positive electrode area. The lithium ion screen is used to first undergo a reduction reaction in the negative electrode area to adsorb Li + The device can continuously enrich and extract lithium ions while removing some impurity ions, which can effectively improve the impurities (such as Mg 2+ ) removal rate, thereby improving the purity of lithium ions. The corresponding lithium extraction method is simple to operate, low in cost, and high in lithium extraction efficiency.

Description

Technical Field

[0001] The present application relates to the field of lithium extraction technology, and specifically to a lithium extraction device and a lithium extraction method. Background Art

[0002] With the rapid development of new energy vehicles, the demand for lithium has increased dramatically, and the development of lithium extraction technology has gradually received attention. According to statistics, 70% of the world's lithium resources are found in salt lake brine. my country's salt lake brine resources are mainly high in magnesium and lithium ratio. The brine contains a large amount of lithium. + Mg with similar properties 2+ Therefore, Mg needs to be removed during the lithium extraction process. 2+ 、Li + Only after separation can efficient lithium extraction be achieved.

[0003] For the extraction of lithium from salt lake brine, the methods currently developed include adsorption, precipitation, solvent extraction, electrodialysis and electrochemical deintercalation. Among them, precipitation is suitable for brine with a low Mg / Li ratio; the life of the extractant in the solvent extraction method is short and it is not suitable for industrial production; electrodialysis separation requires high costs; the electrochemical deintercalation method cannot be produced continuously, and the electrolyte or electrode position needs to be replaced after adsorption saturation, and impurity ions such as Mg adsorbed on the electrode 2+ etc. are difficult to remove.

[0004] Therefore, it is of great significance to develop a low-impurity continuous lithium extraction technology.

[0005] In view of this, this application is hereby filed. Summary of the Invention

[0006] One of the purposes of this application is to provide a lithium extraction device that can continuously enrich and extract lithium ions while removing some impurity ions, which can effectively improve the impurities (such as Mg 2+ ) removal rate and improve the purity of lithium ions.

[0007] The second purpose of this application includes providing a method for extracting lithium using the above-mentioned lithium extraction device, which is simple to operate, low in cost, and high in lithium extraction efficiency.

[0008] In order to achieve at least one of the above-mentioned objectives of this application, the following technical solutions may be adopted:

[0009] The first solution of the present application includes providing a lithium extraction device, which includes an electrolytic cell and a lithium ion screen, wherein the electrolytic cell includes a negative electrode region, a positive electrode region, and a lithium-containing liquid injection region;

[0010] The negative electrode region and the positive electrode region are relatively spaced apart, and the lithium-containing liquid injection region is located between the negative electrode region and the positive electrode region; a cation exchange membrane is provided between the negative electrode region and the lithium-containing liquid injection region, and an anion exchange membrane is provided between the lithium-containing liquid injection region and the positive electrode region;

[0011] The negative electrode region and the positive electrode region are respectively used to connect to the negative electrode and the positive electrode of the power supply. During use, there is electrolyte in both the negative electrode region and the positive electrode region.

[0012] Lithium ion sieve is used to first undergo reduction reaction in the negative electrode area during the lithium extraction process to adsorb Li + It is mixed with some cationic impurities, and then an oxidation reaction occurs in the positive electrode area to precipitate the cations.

[0013] In some embodiments of the present application, the positive electrode region of the lithium extraction device is further provided with a discharge port, and the discharge port is provided with a filtering device for separating the precipitate formed by the precipitated cations and the anions in the positive electrode region from the electrolyte.

[0014] In some embodiments of the present application, the lithium extraction device further includes a lithium ion sieve cleaning tank, the inlet of the lithium ion sieve cleaning tank is connected to the positive electrode area, and the outlet of the lithium ion sieve cleaning tank is connected to the negative electrode area.

[0015] In some embodiments of the present application, the lithium extraction device further includes a power supply, which includes a positive electrode for connecting to the positive electrode region and a negative electrode for connecting to the negative electrode region.

[0016] The second solution of the present application includes providing a lithium extraction method, which uses the above-mentioned lithium extraction device to extract lithium from the lithium-containing liquid to be treated.

[0017] In some embodiments of the present application, the lithium-containing liquid includes at least one of brine, seawater, waste battery leachate, lithium precipitation mother liquor and ore lithium extraction leachate.

[0018] In some embodiments of the present application, the electrolyte includes a lithium-free electrolyte or a lithium-containing electrolyte.

[0019] In some embodiments of the present application, the electrolyte is a lithium-free electrolyte or a lithium-reduced electrolyte.

[0020] In some embodiments of the present application, the electrolyte is a lithium-free electrolyte.

[0021] In some embodiments of the present application, the electrolyte includes at least one of a NaCl solution and a KCl solution.

[0022] In some embodiments of the present application, the electrolyte contains an oxidant.

[0023] In some embodiments of the present application, the lithium extraction process includes at least one processing cycle, each processing cycle including:

[0024] S1: Powering on the lithium extraction device so that the positive electrode region and the negative electrode region respectively enrich the anions and cations in the lithium-containing solution;

[0025] S2: Continue to maintain the power-on state to allow the lithium ion sieve in the negative electrode area to undergo a reduction reaction and adsorb Li + And mixed with some cationic impurities;

[0026] S3: transferring at least part of the lithium ion sieve from the negative electrode region to the positive electrode region, causing the lithium ion sieve to undergo an oxidation reaction to precipitate cations, and at least part of the precipitated cations form a precipitate together with the anions in the positive electrode region.

[0027] In some embodiments of the present application, in each processing cycle, the power-on condition in each step independently includes: voltage>0V and ≤1.5V.

[0028] In some embodiments of the present application, in each processing cycle, the total power-on time of S1 and S2 is 0.5-1 hour.

[0029] In some embodiments of the present application, S3 is performed under power-on conditions, and the power-on time of S3 is 0.5-1 hour.

[0030] In some embodiments of the present application, in each processing cycle, the lithium ion sieve just put into the negative electrode region is a desorbed lithium ion sieve, and the lithium ion sieve just transferred to the positive electrode region is a lithium-rich lithium ion sieve.

[0031] In some embodiments of the present application, the lithium ion sieve is a manganese iron phosphate lithium ion sieve.

[0032] In some embodiments of the present application, each processing cycle further includes:

[0033] S4: transferring at least part of the lithium ion sieve after cations are precipitated in the positive electrode region to a lithium ion sieve cleaning tank for cleaning, so as to be subsequently put into the negative electrode region for recycling.

[0034] In some embodiments of the present application, the cleaning method is ultrasonic cleaning.

[0035] In some embodiments of the present application, the cleaning time is 0.5-1 h.

[0036] In some embodiments of the present application, when Li + When the concentration reaches a preset concentration, the lithium-containing solution is collected and the precipitate is removed.

[0037] In some embodiments of the present application, the preset concentration is not less than 0.7 g / L.

[0038] In some embodiments of the present application, the lithium extraction process further includes: removing the precipitate from the collected lithium-containing solution; + Precipitated in the form of crystals.

[0039] In some embodiments of the present application, precipitating crystals includes: mixing a lithium-containing solution with a readily soluble carbonate or bicarbonate, and heating.

[0040] In some embodiments of the present application, the readily soluble carbonate comprises Na2CO3.

[0041] In some embodiments of the present application, the readily soluble bicarbonate salt comprises NaHCO 3 .

[0042] In some embodiments of the present application, precipitating crystals includes: mixing a lithium-containing solution with lithium phosphate and heating.

[0043] In some embodiments of the present application, the heating temperature is 55-65°C.

[0044] The beneficial effects of this application include:

[0045] The lithium extraction device provided in the present application allows anions in the lithium-containing liquid to be enriched in the positive electrode region and cations to be enriched in the negative electrode region under power-on conditions. The ion exchange membrane can prevent anions from entering the negative electrode region and prevent cations from entering the positive electrode region. The lithium ion sieve contained in the device first undergoes a reduction reaction in the negative electrode region to adsorb Li + And mixed with some cationic impurities (such as Mg 2+ Then it is transferred to the positive electrode area to undergo oxidation reaction to precipitate cations. At this time, some of the precipitated cations can form precipitates together with the anions in the positive electrode area (such as Mg 2+ With CO3 2- Together with the formation of MgCO3 precipitation) can be removed.

[0046] The lithium extraction device can remove some impurity ions (such as Mg 2+ ) while continuously enriching and extracting lithium ions to improve the purity of lithium ions. The corresponding lithium extraction method is simple to operate, low in cost, and high in lithium extraction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0048] Figure 1This is a schematic diagram of the structure of the lithium extraction device provided in this application in the first stage;

[0049] Figure 2 This is a schematic structural diagram of the lithium extraction device provided in this application in the second stage.

[0050] Icons: 10-electrolyzer; 11-negative electrode area; 12-positive electrode area; 13-electrolyte; 14-lithium-containing feed solution injection area; 15-lithium-containing feed solution; 16-cation exchange membrane; 17-anion exchange membrane; 20-lithium ion sieve; 30-power supply; 31-negative electrode of power supply; 32-positive electrode of power supply; 40-lithium ion sieve cleaning tank. DETAILED DESCRIPTION

[0051] The embodiments of the present application will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0052] The endpoints of the ranges and any values ​​disclosed in this application are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0053] The inventor proposed that when lithium ions are enriched in the lithium-containing liquid by using a lithium ion sieve 20 during lithium extraction, the Mg in the liquid will be mixed. 2+ Impurity ions such as ions reduce the lithium extraction effect.

[0054] Based on this, the present application proposes a lithium extraction device and method that can continuously enrich and extract lithium ions while removing some impurity ions.

[0055] For details, please refer to Figure 1 and Figure 2 The lithium extraction device proposed in this application includes an electrolytic cell 10 and a lithium ion sieve 20. The electrolytic cell 10 includes a negative electrode area 11, a positive electrode area 12 and a lithium-containing liquid injection area 14.

[0056] The negative electrode region 11 and the positive electrode region 12 are arranged relative to each other, and the lithium-containing liquid injection region 14 is located between the negative electrode region 11 and the positive electrode region 12; a cation exchange membrane 16 is provided between the negative electrode region 11 and the lithium-containing liquid injection region 14, and an anion exchange membrane 17 is provided between the lithium-containing liquid injection region 14 and the positive electrode region 12.

[0057] The negative electrode region 11 and the positive electrode region 12 are respectively used to connect to the negative electrode 31 and the positive electrode 32 of the power supply. During use, the negative electrode region 11 and the positive electrode region 12 both contain electrolyte 13 .

[0058] The lithium-containing liquid 15 may include at least one of brine, seawater, waste battery leachate, lithium precipitation mother liquor and ore lithium extraction leachate. Taking the lithium-containing liquid 15 as brine and / or seawater as an example, the cations contained therein may include, for example but not limited to, Li + Mg 2+ , K + , Ca 2+ and Na + The anions contained therein may include CO3, for example but not limited thereto. 2- 、SO4 2- and Cl - wait.

[0059] The electrolyte 13 can be a lithium-free electrolyte or a lithium-containing electrolyte (preferably, the lithium content in the lithium-containing electrolyte does not exceed 0.7 g / L). In some preferred embodiments, the electrolyte 13 is a lithium-free electrolyte or a low-lithium electrolyte (preferably, the lithium content in the low-lithium electrolyte does not exceed 0.1 g / L), and is more preferably a lithium-free electrolyte (such as comprising at least one of a NaCl solution and a KCl solution) to avoid affecting the accuracy of the final lithium content detection result.

[0060] The lithium ion sieve 20 is used to firstly generate a reduction reaction in the negative electrode region 11 to adsorb Li during the lithium extraction process. + It is mixed with some cationic impurities, and then an oxidation reaction occurs in the positive electrode region 12 to precipitate the cations.

[0061] In the above process, it can be understood that the lithium ion sieve 20 just put into the negative electrode area 11 is in a desorbed state, and the adsorbed Li + After being mixed with some cationic impurities, the lithium-ion sieve 20 becomes lithium-rich. Accordingly, the lithium-ion sieve 20 immediately after being transferred to the positive electrode region 12 is already lithium-rich, and after cations are precipitated, it becomes desorbed. Therefore, the lithium-ion sieve 20 can be recycled in the aforementioned manner. Transferring the lithium-ion sieve 20 can be performed using conventional methods.

[0062] Understandably, Figure 1 Corresponding to the stage where the lithium ion screen 20 is just put into the negative electrode area 11, Figure 2 This corresponds to the stage in which part of the lithium ion sieve 20 is transferred to the positive electrode area 12 during use.

[0063] In some specific embodiments, the lithium ion sieve 20 may be a manganese iron phosphate lithium ion sieve 20. In other embodiments, the lithium ion sieve 20 may also be other common types of lithium ion sieves 20, which are not limited here.

[0064] In some optional embodiments, the aforementioned “oxidation reaction” may be achieved by applying electricity. In other optional embodiments, the aforementioned “oxidation reaction” may be achieved by using an electrolyte 13 containing an oxidant.

[0065] Illustratively, the oxidant used in the electrolyte 13 may include at least one of an organic oxidant and an inorganic oxidant.

[0066] The organic oxidant may include an organic peroxide, such as at least one of performic acid and peracetic acid. The inorganic oxidant may include at least one of hydrogen peroxide, a gas containing O2, and a high-valent oxide of a multivalent element (such as potassium permanganate).

[0067] Furthermore, the positive electrode region 12 of the lithium extraction device provided in the present application is also provided with a discharge port (not shown in the figure), and the discharge port is provided with a filtering device (such as a filter mesh, not shown in the figure) for separating the lithium ion sieve 20 and the precipitate formed by the precipitated cations and the anions in the positive electrode region 12 from the electrolyte 13.

[0068] Furthermore, the lithium extraction device provided in the present application also includes a lithium ion sieve cleaning tank 40 , the inlet of the lithium ion sieve cleaning tank 40 is connected to the positive electrode area 12 , and the outlet of the lithium ion sieve cleaning tank 40 is connected to the negative electrode area 11 .

[0069] After the cations are precipitated in the positive electrode region 12, the lithium ion sieve 20 can be transferred to the lithium ion sieve cleaning tank 40 for cleaning to further remove impurities and other substances adsorbed on the lithium ion sieve 20 (such as precipitated calcium carbonate, magnesium carbonate, etc.) and improve the adsorption capacity of the lithium ion sieve 20. The cleaned lithium ion sieve 20 can be further used, such as recycled into the negative electrode region 11.

[0070] It should be noted that the present application solution does not exclude the possibility of not cleaning the lithium ion sieve 20 , but adding a new lithium ion sieve 20 into the negative electrode region 11 during subsequent processing.

[0071] In addition, the lithium extraction device further includes a power supply 30 , which includes a positive electrode for connecting to the positive electrode region 12 and a negative electrode for connecting to the negative electrode region 11 .

[0072] When the power source 30 is in working state, the electrolytic cell 10 and the power source 30 together form an electrolysis system, and lithium extraction from the lithium-containing feed solution 15 can be achieved through the principle of electrodialysis.

[0073] Correspondingly, the present application also provides a lithium extraction method, which uses the above-mentioned lithium extraction device to extract lithium from the lithium-containing liquid 15 to be processed.

[0074] For reference, the lithium extraction process includes at least one treatment cycle. The specific number of treatment cycles required is determined by the amount of Li contained in the solution in the positive electrode region 12 after treatment. + The concentration depends on the situation.

[0075] Each processing cycle includes:

[0076] S1: The lithium extraction device is powered on so that the positive electrode region 12 and the negative electrode region 11 respectively enrich the anions and cations in the lithium-containing solution 15 .

[0077] Specifically, the enrichment of anions and cations is achieved in the positive electrode region 12 and the negative electrode region 11 respectively through the electrodialysis principle and the electric field on the migration of anions and cations. That is, the cations (such as Li + Mg 2+ , K + , Ca 2+ and Na + etc.) enter the negative electrode region 11, and the anions (such as CO3 2- 、SO4 2- and Cl-, etc.) enter the positive electrode region 12.

[0078] It should be noted that before power is applied, the lithium-containing liquid injection area 14 is injected with a lithium-containing liquid 15, the positive electrode area 12 and the negative electrode area 11 are both injected with an electrolyte 13, and there is a lithium ion sieve 20 in the negative electrode area 11 (preferably a clean desorbed lithium ion sieve 20, such as a clean desorbed manganese iron phosphate lithium ion sieve 20).

[0079] In this step, the voltage of the power supply is greater than 0V and less than or equal to 1.5V, such as 0.5V, 0.6V, 0.7V, 0.8V, 0.9V, 1.0V, 1.1V, 1.2V, 1.3V, 1.4V or 1.5V, etc., or any other value within the range of greater than 0V and less than or equal to 1.5V.

[0080] It should be noted that if the voltage is greater than 1.5V, on the one hand, it is easy to make the voltage and current larger, resulting in concentration polarization; on the other hand, it will greatly increase energy consumption.

[0081] S2: Continue to maintain the above-mentioned power-on state, so that the lithium ion sieve 20 in the negative electrode region 11 undergoes a reduction reaction to adsorb Li + And mixed with some cationic impurities.

[0082] That is, the desorbed lithium ion sieve 20 in the electrolyte 13 of the negative electrode region 11 undergoes a reduction reaction. + While combining, it also contains other impurity cations (such as Mg 2+ etc.), thereby forming a lithium-rich lithium ion sieve 20 that is rich in lithium ions and other impurity cations.

[0083] For reference, the total power-on time of S1 and S2 can be 0.5-1 h, for example, 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h or 1 h, etc. The specific time can be determined according to the adsorption of cations by the lithium ion sieve 20 .

[0084] S3: Transferring at least part of the lithium ion sieve 20 (lithium-rich lithium ion sieve 20) from the negative electrode region 11 to the positive electrode region 12, and causing the lithium ion sieve 20 to undergo an oxidation reaction to precipitate the adsorbed cations, and at least part of the precipitated cations form a precipitate together with the anions in the positive electrode region 12.

[0085] In this process, the lithium ion sieve 20 undergoes an oxidation reaction, the cations are reduced and precipitated from the lithium ion sieve 20, and the lithium ion sieve 20 after the cations are precipitated is in a desorbed state again, and the precipitated Mg 2+ , Ca 2+ Cationic impurities such as CO3 2- etc.) combine to form a precipitate.

[0086] In some preferred embodiments, the power supply is always maintained during the process from S2 to S3. Preferably, the power supply voltage during the process from S1 to S3 is the same.

[0087] For reference, the power-on time in S3 may be 0.5-1 h, for example, 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h or 1 h, etc. The specific time may be determined according to the precipitation of cations by the lithium ion sieve 20 .

[0088] Furthermore, each processing cycle may also include:

[0089] S4: transferring at least a portion of the lithium ion sieve 20 after cations are precipitated in the positive electrode region 12 to the lithium ion sieve cleaning tank 40 for cleaning, so as to be subsequently put into the negative electrode region 11 for recycling.

[0090] For example, the cleaning method may be ultrasonic cleaning. The cleaning time may be, for example but not limited to, 0.5-1 hour. The cleaning liquid used for cleaning may be pure water.

[0091] During the cleaning process, the power supply 30 can be turned off to save energy.

[0092] When the Li in the positive electrode region 12 + The concentration reaches the preset concentration (such as Li + When the concentration is not less than 0.7 g / L), the lithium-containing solution after removing the precipitate is collected for subsequent treatment.

[0093] It is understandable that after only one treatment cycle, the Li +When the concentration reaches the preset concentration, after S3, the lithium-containing solution is collected and the precipitate is removed. Further, the desorbed lithium ion sieve 20 obtained in S3 can be subjected to step S4.

[0094] After one treatment cycle, the Li contained in the solution in the positive electrode region 12 + When the concentration does not reach the preset concentration, steps S1 to S4 can be performed in sequence until the Li content in the solution in the positive electrode region 12 reaches 0. + When the concentration reaches the preset concentration, the lithium-containing solution after the precipitation is collected and removed after S3 in the treatment cycle. Further, the desorbed lithium ion sieve 20 obtained in S3 in the treatment cycle can be subjected to step S4.

[0095] Furthermore, the lithium extraction process provided in the present application further comprises: removing the precipitate from the collected lithium-containing solution; + Precipitate in the form of crystals. For example, this can be achieved by mixing a lithium-containing solution with a readily soluble carbonate or bicarbonate and then heating it, or by mixing a lithium-containing solution with lithium phosphate and then heating it.

[0096] In some embodiments, the lithium-containing solution may be mixed with a readily soluble carbonate (such as Na2CO3) and heated to allow Li + In other embodiments, the lithium-containing solution can be mixed with a readily soluble bicarbonate (such as NaHCO3) and heated to make Li + In other embodiments, the lithium-containing solution can also be mixed with lithium phosphate to make Li + It precipitates in the form of crystals (such as Li3PO4 crystals).

[0097] For reference, the heating temperature may be 55-65°C, such as 55°C, 58°C, 60°C, 62°C or 65°C, or any other value within the range of 55-65°C.

[0098] As mentioned above, the lithium extraction device and method provided by the present application can repeatedly clean the lithium ion screen 20 and continuously recycle it, which can not only effectively improve the lithium extraction efficiency, but also greatly reduce the cost. For lithium extraction from brine with a high Mg / Li ratio, this method can more effectively remove impurities (especially Mg 2+ ), thereby improving the purity of extracted lithium ions.

[0099] The features and performance of the present application are further described in detail below with reference to the embodiments.

[0100] Example 1

[0101] This embodiment provides a lithium extraction device, please refer to Figure 1and Figure 2 , which includes a power supply 30, an electrolytic cell 10 and a lithium ion sieve 20.

[0102] The electrolytic cell 10 includes a negative electrode region 11 , a positive electrode region 12 , a lithium-containing solution injection region 14 , and a lithium ion screen cleaning tank 40 .

[0103] The negative electrode region 11 and the positive electrode region 12 are arranged relative to each other, and the lithium-containing liquid injection region 14 is located between the negative electrode region 11 and the positive electrode region 12; a cation exchange membrane 16 is provided between the negative electrode region 11 and the lithium-containing liquid injection region 14, and an anion exchange membrane 17 is provided between the lithium-containing liquid injection region 14 and the positive electrode region 12.

[0104] The negative electrode region 11 and the positive electrode region 12 are respectively used to connect to the negative electrode 31 and the negative electrode 31 of the power supply. During use, both the negative electrode region 11 and the positive electrode region 12 contain an electrolyte 13 (NaCl solution).

[0105] The lithium-containing liquid 15 is brine. The cations contained in the brine include Li + Mg 2+ , K + , Ca 2+ and Na + etc., containing anions including CO3 2- 、SO4 2- and Cl-, etc.

[0106] The lithium ion sieve 20 (manganese iron phosphate lithium ion sieve 20) is used to first adsorb Li in the negative electrode area 11 during the lithium extraction process. + It is mixed with some cationic impurities, and then the cations are precipitated in the positive electrode region 12 under the action of electrolysis.

[0107] The lithium ion sieve 20 just put into the negative electrode area 11 is in a desorbed state, adsorbing Li + After being mixed with some cationic impurities, it is in a lithium-rich state; accordingly, the lithium ion sieve 20 just transferred to the positive electrode area 12 is in a lithium-rich state, and is in a desorbed state after the cations are precipitated.

[0108] The positive electrode region 12 of the lithium extraction device is also provided with a discharge port, and the discharge port is provided with a filter screen for filtering out the precipitate formed by the precipitated cations and the anions in the positive electrode region 12 .

[0109] The inlet of the lithium ion screening cleaning tank 40 is connected to the positive electrode area 12 , and the outlet of the lithium ion screening cleaning tank 40 is connected to the negative electrode area 11 .

[0110] The positive electrode of the power source 30 is connected to the positive electrode region 12 , and the negative electrode of the power source 30 is connected to the negative electrode region 11 .

[0111] Example 2

[0112] The difference between this embodiment and embodiment 1 is that the electrolyte 13 contains an oxidant (hydrogen peroxide).

[0113] Example 3

[0114] This embodiment provides a method for extracting lithium from salt lake brine (high Mg / Li ratio), which uses the lithium extraction device in Example 1 in the following manner:

[0115] S1: The lithium extraction device is powered (1.5V) to allow the positive electrode region 12 and the negative electrode region 11 to enrich the anions and cations in the lithium-containing solution 15, respectively. Specifically, the cations (such as Li + Mg 2+ , K + , Ca 2+ and Na + etc.) enter the negative electrode region 11, and the anions (such as CO3 2- 、SO4 2- and Cl-, etc.) enter the positive electrode region 12.

[0116] Before power is turned on, the lithium-containing liquid injection area 14 is injected with salt lake brine (Mg 2+ The concentration is 10g / L, Li + The concentration is 0.2g / L, CO3 2- The concentration is 0.16 g / L), the positive electrode area 12 and the negative electrode area 11 are both injected with NaCl solution, and the negative electrode area 11 contains a clean desorbed manganese iron phosphate lithium ion sieve 20 (particle size is 10 μm).

[0117] S2: Continue to maintain the above-mentioned power-on state so that the lithium ion sieve 20 in the negative electrode region 11 adsorbs Li + And some cationic impurities are mixed in, thereby forming a lithium-rich lithium ion sieve 20 that is rich in lithium ions and other impurity cations.

[0118] The total energization time of S1 and S2 is 0.5h.

[0119] S3: The lithium ion sieve 20 (lithium-rich lithium ion sieve 20) is transferred from the negative electrode region 11 to the positive electrode region 12, and the cations adsorbed by the lithium ion sieve 20 are precipitated under the power-on state (1.5V), and part of the precipitated cations and the anions in the positive electrode region 12 form a precipitate (such as Mg 2+ With CO3 2- After the cations are precipitated, the lithium ion sieve 20 is in a desorbed state again.

[0120] During the above process from S2 to S3, the power is always kept on, and the power-on time in S3 is 0.5h.

[0121] S4: The lithium ion sieve 20 after cations are precipitated in the positive electrode region 12 is transferred to the lithium ion sieve cleaning tank 40 for cleaning so as to be subsequently put into the negative electrode region 11 for recycling.

[0122] The cleaning method is ultrasonic cleaning, the cleaning time is 0.5h, and the cleaning liquid used is pure water.

[0123] Repeat the above steps S1 to S4 until the Li + When the concentration exceeds 0.7 g / L, the lithium-containing solution is collected and the precipitate is removed.

[0124] S5: The collected lithium-containing solution after removing the precipitate is mixed with NaOH powder and heated to 60°C to make Li + It precipitates as LiOH crystals.

[0125] Example 4

[0126] This embodiment provides a method for extracting lithium from salt lake brine (low Mg / Li ratio), which uses the lithium extraction device in Example 1 in the following manner:

[0127] S1: The lithium extraction device is powered (1.2V) to allow the positive electrode region 12 and the negative electrode region 11 to respectively enrich the anions and cations in the lithium-containing solution 15. Specifically, the cations (such as Li + Mg 2+ , K + , Ca 2+ and Na + etc.) enter the negative electrode region 11, and the anions (such as CO3 2- 、SO4 2- and Cl - etc.) into the positive electrode region 12.

[0128] Before power is turned on, the lithium-containing liquid injection area 14 is injected with salt lake brine (Mg 2+ The concentration is 5g / L, Li + The concentration is 0.2g / L, CO3 2- The concentration is 0.04 g / L), the positive electrode area 12 and the negative electrode area 11 are both injected with NaCl solution, and the negative electrode area 11 contains a clean desorbed manganese iron phosphate lithium ion sieve 20 (particle size is 10 μm).

[0129] S2: Continue to maintain the above-mentioned power-on state so that the lithium ion sieve 20 in the negative electrode region 11 adsorbs Li + And some cationic impurities are mixed in, thereby forming a lithium-rich lithium ion sieve 20 that is rich in lithium ions and other impurity cations.

[0130] The total energization time of S1 and S2 is 0.5h.

[0131] S3: The lithium ion sieve 20 (lithium-rich lithium ion sieve 20) is transferred from the negative electrode region 11 to the positive electrode region 12, and the cations adsorbed by the lithium ion sieve 20 are precipitated under the power-on state (1.2V), and part of the precipitated cations and the anions in the positive electrode region 12 form a precipitate (such as Mg 2+ With CO3 2- After the cations are precipitated, the lithium ion sieve 20 is in a desorbed state again.

[0132] During the above process from S2 to S3, the power is always kept on, and the power-on time in S3 is 0.5h.

[0133] S4: The lithium ion sieve 20 after cations are precipitated in the positive electrode region 12 is transferred to the lithium ion sieve cleaning tank 40 for cleaning so as to be subsequently put into the negative electrode region 11 for recycling.

[0134] The cleaning method is ultrasonic cleaning, the cleaning time is 0.5h, and the cleaning liquid used is pure water.

[0135] Repeat the above steps S1 to S4 until the Li + When the concentration exceeds 0.7 g / L, the lithium-containing solution is collected and the precipitate is removed.

[0136] S5: The collected lithium-containing solution after removing the precipitate is mixed with Na2CO3 powder and heated to 60°C to make Li + It precipitates as Li2CO3 crystals.

[0137] Example 5

[0138] The difference between this embodiment and embodiment 2 is that the power-on voltage is 1V.

[0139] Example 6

[0140] The difference between this embodiment and embodiment 2 is that the total power-on time of S1 and S2 is 1 hour, and the power-on time of S3 is 1 hour.

[0141] Comparative Example 1

[0142] The difference between this comparative example and Example 3 is that a conventional electrodialysis lithium extraction device is used to extract lithium. The specific method is as follows:

[0143] In the positive electrode area 12, a circulating brine (Mg 2+ The concentration is 10g / L, Li + The concentration is 0.2g / L, CO3 2- The concentration is 0.16g / L), the negative electrode area 11 is KCl solution, the positive and negative electrode areas are separated by lithium ion solid electrolyte, a voltage of 1.0V is applied, and the power is turned on for 0.5h. Li+ After multiple enrichments, the negative electrode solution was taken out, NaOH powder was added to the solution and the solution was heated to 60 ° C to evaporate, so that Li + The product was precipitated in the form of LiOH crystals. Lithium ion sieve 20 was not used in this process.

[0144] Comparative Example 2

[0145] The difference between this comparative example and Example 4 is that a conventional electrodialysis lithium extraction device is used to extract lithium. The specific method is as follows:

[0146] In the positive electrode area 12, a circulating brine (Mg 2+ The concentration is 5g / L, Li + The concentration is 0.2g / L, CO3 2- The concentration is 0.04g / L), the negative electrode area 11 is KCl solution, the positive and negative electrode areas are separated by lithium ion solid electrolyte, a voltage of 1.0V is applied, and the power is turned on for 0.5h. Li + After multiple enrichments, the negative electrode solution was taken out, NaOH powder was added to the solution and the solution was heated to 60 ° C to evaporate, so that Li + The product was precipitated in the form of LiOH crystals. Lithium ion sieve 20 was not used in this process.

[0147] Test example

[0148] The lithium-containing solutions after removing the precipitate collected from Examples 3-6 and Comparative Examples 1-2 were tested, specifically Mg 2+ He Li + The concentration was detected according to HJ776-2015 "Determination of 32 elements in water by inductively coupled plasma emission spectrometry", and the results are shown in Table 1.

[0149] Table 1 Test results

[0150] <![CDATA[Mg 2+ (g / L)]]> <![CDATA[Li + (g / L)]]> <![CDATA[Mg 2+ Removal rate (%)]]> Example 3 0.085 0.74 99.15 Example 4 0.075 0.72 98.50 Example 5 0.082 0.75 99.18 Example 6 0.080 0.71 99.20 Comparative Example 1 0.741 0.71 92.59 Comparative Example 2 0.423 0.72 91.54

[0151] As can be seen from Table 1, the methods provided in Examples 3-6 of the present application can all obtain higher Mg 2+ Removal rate (≥98.50%). Among them, Example 3 can have higher Mg removal rate than Comparative Example 1. 2+ Removal rate, similarly, Example 4 of the present application can have higher Mg removal rate than Comparative Example 2. 2+ Removal rate. This shows that the lithium extraction method provided by this application can effectively remove Mg 2+ At the same time, lithium ions are effectively enriched and extracted.

[0152] Moreover, Example 3 has a better effect than Example 4, indicating that in the lithium extraction process, the lithium extraction device provided in this application is more effective in removing magnesium ion impurities in high magnesium-lithium ratio brine.

[0153] In summary, the lithium extraction device provided by this application can remove some impurity ions (such as Mg 2+ ) while enriching and extracting lithium ions to improve the purity of lithium ions. The corresponding lithium extraction method is simple to operate, low in cost, and high in lithium extraction efficiency.

[0154] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

[0155] Industrial Applicability

[0156] The lithium device provided by this application can remove some impurity ions (such as Mg 2+ ) while continuously enriching and extracting lithium ions to improve the purity of lithium ions. The corresponding lithium extraction method is simple to operate, low in cost, and high in lithium extraction efficiency.

Claims

1. A lithium extraction method, characterized in that: A lithium extraction device is used to extract lithium from the lithium-containing liquid to be treated; The lithium extraction device includes an electrolytic cell and a lithium ion screen, wherein the electrolytic cell includes a negative electrode area, a positive electrode area and a lithium-containing liquid injection area; The negative electrode region and the positive electrode region are arranged relative to each other, and the lithium-containing liquid injection region is located between the negative electrode region and the positive electrode region; a cation exchange membrane is provided between the negative electrode region and the lithium-containing liquid injection region, and an anion exchange membrane is provided between the lithium-containing liquid injection region and the positive electrode region; The negative electrode region and the positive electrode region are respectively used to connect to the negative electrode and the positive electrode of the power supply. During use, the negative electrode region and the positive electrode region both contain electrolyte. The lithium ion sieve is used to first undergo a reduction reaction in the negative electrode region to adsorb Li during the lithium extraction process. + and mixed with some cationic impurities, and then an oxidation reaction occurs in the positive electrode region to precipitate the cations; The positive electrode region of the lithium extraction device is further provided with a discharge port, and the discharge port is provided with a filtering device for separating the precipitate formed by the precipitated cations and the anions in the positive electrode region from the electrolyte; The lithium extraction process includes at least one processing cycle, and each processing cycle includes: S1: Powering the lithium extraction device so that the positive electrode region and the negative electrode region respectively enrich the anions and cations in the lithium-containing solution; S2: Continue to maintain the power-on state, so that the lithium ion sieve in the negative electrode region undergoes a reduction reaction to adsorb Li + And mixed with some cationic impurities; S3: transferring at least a portion of the lithium ion sieve from the negative electrode region to the positive electrode region, causing the lithium ion sieve to undergo an oxidation reaction to precipitate cations, and at least a portion of the precipitated cations and anions in the positive electrode region to form a precipitate together; The lithium-containing liquid comprises brine and / or seawater, and the cations contained in the lithium-containing liquid comprise Li + Mg 2+ , K + , Ca 2+ and Na + The anions contained in the lithium-containing solution include CO3 2- 、SO4 2- and Cl - .

2. The lithium extraction method according to claim 1, characterized in that The lithium extraction device further includes a lithium ion sieve cleaning tank, the inlet of the lithium ion sieve cleaning tank is connected to the positive electrode area, and the outlet of the lithium ion sieve cleaning tank is connected to the negative electrode area.

3. The lithium extraction method according to claim 1 or 2, characterized in that: The lithium extraction device further includes a power supply, which includes a positive electrode connected to the positive electrode region and a negative electrode connected to the negative electrode region.

4. The lithium extraction method according to claim 1, characterized in that The lithium-containing liquid also includes at least one of waste battery leaching liquid, lithium precipitation mother liquor and ore lithium extraction leaching liquid.

5. The lithium extraction method according to claim 1, characterized in that: The electrolyte includes a lithium-free electrolyte or a lithium-containing electrolyte.

6. The lithium extraction method according to claim 5, characterized in that: The electrolyte is a lithium-free electrolyte or a lithium-reduced electrolyte.

7. The lithium extraction method according to claim 6, characterized in that: The electrolyte is a lithium-free electrolyte.

8. The lithium extraction method according to any one of claims 5 to 7, characterized in that: The electrolyte includes at least one of a NaCl solution and a KCl solution.

9. The lithium extraction method according to claim 5, characterized in that: The electrolyte contains an oxidant.

10. The lithium extraction method according to claim 1, characterized in that: In each processing cycle, the power-on condition in each step independently includes: voltage>0V and ≤1.5V.

11. The lithium extraction method according to claim 1, characterized in that: In each processing cycle, the total power-on time of S1 and S2 is 0.5-1h.

12. The lithium extraction method according to claim 1, characterized in that: S3 is carried out under power-on condition, and the power-on time of S3 is 0.5-1h.

13. The lithium extraction method according to claim 1, characterized in that: In each treatment cycle, the lithium ion sieve just put into the negative electrode area is a desorbed lithium ion sieve, and the lithium ion sieve just transferred to the positive electrode area is a lithium-rich lithium ion sieve.

14. The lithium extraction method according to claim 13, characterized in that: The lithium ion sieve is a manganese iron phosphate lithium ion sieve.

15. The lithium extraction method according to claim 1, characterized in that: Each processing cycle also includes: S4: transferring at least a portion of the lithium ion sieve after cations are precipitated in the positive electrode region to a lithium ion sieve cleaning tank for cleaning, so as to be subsequently put into the negative electrode region for recycling.

16. The lithium extraction method according to claim 15, characterized in that: The cleaning method is ultrasonic cleaning.

17. The lithium extraction method according to claim 16, characterized in that: The cleaning time is 0.5-1h.

18. The lithium extraction method according to claim 1, characterized in that: When the Li + When the concentration reaches a preset concentration, the lithium-containing solution is collected and the precipitate is removed.

19. The lithium extraction method according to claim 18, characterized in that: The preset concentration is not less than 0.7 g / L.

20. The lithium extraction method according to claim 1, characterized in that: The lithium extraction process also includes: removing the precipitate from the lithium-containing solution and + Precipitated in the form of crystals.

21. The lithium extraction method according to claim 20, characterized in that: The crystal precipitation comprises: mixing the lithium-containing solution with a readily soluble carbonate or bicarbonate, and heating.

22. The lithium extraction method according to claim 21, characterized in that: Soluble carbonates include Na2CO3.

23. The lithium extraction method according to claim 22, characterized in that: Readily soluble bicarbonates include NaHCO3.

24. The lithium extraction method according to claim 20, characterized in that: The crystal precipitation comprises: mixing the lithium-containing solution with lithium phosphate and heating.

25. The lithium extraction method according to claim 24, characterized in that: The heating temperature is 55-65℃.

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