Electrochemical method for removing magnesium and extracting lithium from salt lake brine and magnesium-lithium separation system

Abstract

The application provides a method for removing magnesium and extracting lithium from electrochemical salt lake brine, which comprises the following steps: feeding the salt lake brine into a single-chamber electrolysis chamber, and allowing an electrolysis reaction to occur in the single-chamber electrolysis chamber; feeding the anode electrolyte after electrolysis out of the single-chamber electrolysis chamber and collecting the anode electrolyte; feeding the collected anode electrolyte into the single-chamber electrolysis chamber again to participate in the electrolysis reaction; feeding the cathode liquid after electrolysis out of the single-chamber electrolysis chamber and filtering the cathode liquid, so as to allow the hydroxyl ions in the cathode liquid after electrolysis to react with magnesium ions in the salt lake brine to generate magnesium hydroxide precipitate, evaporating and concentrating the lithium-rich ion salt lake brine obtained after filtration to obtain lithium-rich brine concentrate; adding sodium carbonate into the lithium-rich brine concentrate to generate lithium carbonate precipitate through lithium precipitation reaction, and obtaining lithium carbonate through centrifugation, washing and drying of the lithium carbonate precipitate. The application also provides a magnesium-lithium separation system for the method for removing magnesium and extracting lithium from electrochemical salt lake brine. The application realizes efficient separation of lithium and magnesium in the salt lake brine and extraction of lithium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnesium removal and lithium extraction from salt lake brine, in particular to an electrochemical magnesium removal and lithium extraction method for salt lake brine and a magnesium-lithium separation system. BACKGROUND

[0002] Lithium is an important component of new energy materials in the 21st century, and is widely used in batteries, ceramics, medicine and other fields, and is known as an "important element to drive the world forward".

[0003] With the development of new energy vehicles, the demand for lithium continues to rise, and the global production of lithium salt comes from brine and hard rock ore (accounting for 63% and 37% respectively). Compared with the lithium extraction process from ore, the lithium extraction process from salt lake brine has the advantages of environmental friendliness and low cost. However, the high magnesium-lithium ratio and similar properties of magnesium and lithium ions in salt lakes have always hindered the development of lithium resource extraction technology from salt lake brine. Therefore, there is an urgent need for a green, efficient and low-cost magnesium removal and lithium extraction process to address this challenge.

[0004] Currently, the main lithium extraction technologies from salt lake brine include precipitation method, adsorption method and membrane separation method. Among them, the precipitation method is the most mature and simple process, which was first applied in salt lakes with low magnesium-lithium ratio. Although the precipitation method is relatively simple to operate, it has a long process cycle, its operation is limited by weather conditions, and a large amount of by-products are produced, so it is not suitable for lithium extraction from salt lake brine with high magnesium-lithium ratio. The adsorption method has the advantages of good selectivity, low energy consumption and high lithium adsorption capacity, but its slow exchange speed and high solution loss degree result in poor economic efficiency, which is the reason why it cannot be popularized in industry. Although the membrane separation method has environmental advantages in lithium extraction from salt lake brine, its short service life, high water consumption and high energy consumption are its disadvantages. Therefore, there is an urgent need for a low-cost, green and pollution-free magnesium removal and lithium extraction method and system. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide an electrochemical magnesium removal and lithium extraction method for salt lake brine and a magnesium-lithium separation system, which aims to solve the problems raised in the technical background, realize efficient separation of lithium and magnesium in high-magnesium and low-lithium salt lake brine and extraction of lithium, and has the advantages of simple operation process, low production cost, no pollution in the whole process and suitability for industrial application.

[0006] To solve the above technical problems, the first implementation scheme of the present application is to provide an electrochemical magnesium removal and lithium extraction method for salt lake brine, which comprises the following steps:

[0007] The salt lake brine containing lithium ions and magnesium ions is sent into a single-chamber electrolysis chamber, and an electrolysis reaction occurs in the single-chamber electrolysis chamber;

[0008] The anode electrolyte containing hydrogen ions, lithium ions and magnesium ions after electrolysis is sent out from the single-chamber electrolysis chamber and collected, and the collected anode electrolyte is sent into the single-chamber electrolysis chamber again to participate in the electrolysis reaction;

[0009] The cathode liquid containing hydroxyl ions, lithium ions and magnesium ions after electrolysis is sent out from the single-chamber electrolysis chamber and filtered, so as to make the hydroxyl ions in the cathode liquid after electrolysis react with the magnesium ions in the salt lake brine to generate magnesium hydroxide precipitate, and the lithium ion-rich salt lake brine obtained after filtration is evaporated and concentrated to obtain lithium-rich brine concentrate;

[0010] The lithium-rich brine concentrate is added with sodium carbonate to carry out lithium precipitation reaction to obtain lithium carbonate precipitate, and the lithium carbonate precipitate is centrifuged, washed and dried to obtain lithium carbonate.

[0011] Preferably, the salt lake brine containing lithium ions and magnesium ions is sent into the single-chamber electrolysis chamber by the first peristaltic pump at a rate of 50 mL / min to 200 mL / min, the cathode liquid containing hydroxyl ions, lithium ions and magnesium ions after electrolysis is sent out from the single-chamber electrolysis chamber by the second peristaltic pump at a rate of 10 mL / min to 30 mL / min, and the current density of the electrolysis reaction is 20 mA / cm 2 ~ 40 mA / cm 2 .

[0012] Preferably, the content of magnesium ions in the salt lake brine is 250 mg / L to 1000 mg / L, and the content of lithium ions is 50 mg / L to 100 mg / L.

[0013] Preferably, the molar ratio of lithium ions to carbonate in the lithium-rich brine concentrate to sodium carbonate is 1:15 to 20.

[0014] Preferably, the lithium-rich brine concentrate is added with sodium carbonate to carry out lithium precipitation reaction to obtain lithium carbonate precipitate, and the lithium carbonate precipitate is centrifuged, washed and dried to obtain lithium carbonate.

[0015] Preferably, the salt lake brine needs to be stirred at room temperature for 5 min to 15 min before being sent into the electrolysis chamber by the first peristaltic pump.

[0016] The second implementation scheme of the present application provides a magnesium-lithium separation system for the method for removing magnesium and extracting lithium from salt lake brine by electrochemistry, comprising:

[0017] A raw water tank is used to store the salt lake brine to be electrolyzed;

[0018] An electrolysis device is used to electrolyze the salt lake brine, comprising:

[0019] The single-chamber electrolysis chamber is connected with the raw water tank through a pipeline and a first peristaltic pump, and is used for sending the salt lake brine into the single-chamber electrolysis chamber, and the single-chamber electrolysis chamber is provided with an anode liquid overflow port and a cathode liquid discharge port;

[0020] The anode is arranged in the single-chamber electrolysis chamber, and the anode is connected with the positive pole of the power supply through a wire, so that the salt lake brine generates hydrogen ion-rich salt lake brine at the anode, and the hydrogen ion-rich salt lake brine is discharged from the anode liquid overflow port, and the anode liquid overflow port is connected with the anode liquid storage device through a pipeline;

[0021] The cathode is arranged in the single-chamber electrolysis chamber, and the cathode is connected with the negative pole of the power supply through a wire, so that the salt lake brine generates hydrogen ion-rich salt lake brine at the anode;

[0022] The filter component is connected with the cathode liquid discharge port through a pipeline and a second peristaltic pump;

[0023] The cathode liquid storage tank is connected with the filter component through a pipeline and a third peristaltic pump, and is used for storing the cathode liquid from which magnesium hydroxide is removed.

[0024] Preferably, the anode liquid storage device is connected with the raw water tank through a third peristaltic pump and a pipeline.

[0025] Preferably, the single-chamber electrolysis chamber has a circular cross section, and the cathode and the anode are arranged in sequence from the center of the circular single-chamber electrolysis chamber.

[0026] Preferably, the cathode is a conductive stainless steel filter core, and the anode is a cylindrical graphite.

[0027] Preferably, the filter component comprises a microfiltration tank and a microfiltration filter core, the cathode liquid discharge port is communicated with the microfiltration tank through a second peristaltic pump and a pipeline, the microfiltration filter core is arranged in the microfiltration tank and is used for filtering the generated magnesium hydroxide, and the microfiltration filter core is connected with the filter component through a pipeline and a third peristaltic pump.

[0028] Compared with the prior art, the present application has the following innovative effects:

[0029] 1、The method can realize effective separation of the cathode liquid and the anode liquid, does not need to use a membrane, and thus avoids problems of short service life of the membrane, large water consumption and large energy consumption in the membrane separation method in the lithium extraction from the salt lake brine, meanwhile, the cathode liquid after electrolysis is sucked out by the second peristaltic pump, the cathode liquid after being sucked out has high content of hydroxyl ions, and thus can react with magnesium ions in the salt lake brine to generate magnesium hydroxide precipitate, the precipitate process has short cycle and does not produce by-products, so that the method has advantages in lithium extraction from the salt lake brine with high magnesium-lithium ratio, in addition, the method does not have exchange speed and does not have dissolution loss, and thus has low cost and high economic efficiency, and can be popularized in industry.

[0030] 2、The method and system for removing magnesium and extracting lithium from the electrochemical salt lake brine can remove magnesium with an efficiency of 99.9%, and lithium ions in the obtained cathode electrolyte still exist in the solution in the form of ions, after the lithium ion concentration in the concentrated lithium-rich brine is 20 to 30 times that of the original salt lake brine, sodium carbonate is added to the concentrated solution to perform lithium precipitation, the precipitate is centrifuged, washed and dried, and finally lithium carbonate is obtained. The method realizes the effects of magnesium precipitation, lithium enrichment, magnesium removal and lithium extraction, the anode electrolyte is circulated into the raw water tank to participate in electrolysis again, so that no anode acid liquid is generated, and the cathode liquid (lithium chloride solution, lithium sulfate) generated in the lithium extraction process does not pollute the environment.

[0031] 3、The method can be used for treating different high-concentration magnesium-lithium ratio brines, and can also be used for treating different types of brines. The method can achieve 99.98% resource utilization of magnesium ions, and the generated magnesium hydroxide is recycled as a product, in addition, the system for removing magnesium and extracting lithium from the electrochemical salt lake brine realizes membrane-free and drug-free magnesium ion removal, and achieves high-efficiency magnesium-lithium separation effect. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The figure is a flow chart of the process for removing magnesium and extracting lithium from the electrochemical salt lake brine.

[0033] Figure 2 The figure is a process chart for precipitating lithium ions by sodium carbonate in the process for removing magnesium and extracting lithium from the electrochemical salt lake brine.

[0034] Legend of the figures:

[0035] 1, raw water tank; 2, electrolysis device; 2-1, single-chamber electrolysis chamber, 2-2, anode, 2-3, cathode, 3, filter part; 4, cathode liquid storage tank; 5, anode liquid storage. DETAILED DESCRIPTION

[0036] To make the above-mentioned objectives, features, and advantages of the embodiments of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The inventors discovered that there are many methods for extracting lithium from magnesium-rich brine in salt lakes, such as membrane methods and chemical methods. Membrane methods suffer from problems like membrane fouling and high costs, while chemical methods involve direct addition of alkali, which causes environmental pollution and are considered relatively outdated. Therefore, they constructed a single-chamber membrane-free electrolysis-microfiltration system for high-Mg content brine. 2+ / Li + Mg in salt lake brine 2+ With Li + Selective separation generates Mg(OH)2 precipitate to remove magnesium, achieving efficient magnesium removal and lithium enrichment without the need for reagents or membrane electrochemical processes. Sodium carbonate is added in the later stage to generate lithium carbonate precipitate, realizing the resource utilization of lithium ions.

[0038] Therefore, this invention provides an electrochemical method and system for magnesium removal and lithium extraction from salt lake brine, achieving efficient separation of lithium and magnesium and extraction of lithium from high-magnesium, low-lithium salt lake brine. This method is simple to operate, has low production costs, and is pollution-free throughout the entire process, making it suitable for industrial applications.

[0039] like Figures 1-2 As shown, an electrochemical method for removing magnesium and extracting lithium from salt lake brine includes the following steps:

[0040] Salt lake brine containing lithium and magnesium ions is fed into a single-chamber electrolysis chamber, where an electrolysis reaction occurs.

[0041] After electrolysis, the anolyte containing hydrogen ions, lithium ions and magnesium ions is sent out from the single-chamber electrolysis chamber and collected. The collected anolyte is then sent back into the single-chamber electrolysis chamber to participate in the electrolysis reaction.

[0042] After electrolysis, the catholy solution containing hydroxide ions, lithium ions and magnesium ions is sent out from the single-chamber electrolysis chamber and filtered. This is used to allow the hydroxide ions in the catholy solution to react with the magnesium ions in the salt lake brine to form magnesium hydroxide precipitate. The lithium-rich salt lake brine obtained after filtration is evaporated and concentrated to obtain lithium-rich brine concentrate.

[0043] Sodium carbonate was added to a lithium-rich brine concentrate to carry out a lithium precipitation reaction to obtain lithium carbonate precipitate. The lithium carbonate precipitate was centrifuged, washed and dried to obtain lithium carbonate. The centrifuge was used to centrifuge for 5 minutes at a speed of 5000 rpm.

[0044] Specifically, the first peristaltic pump sends the salt lake brine containing lithium ions and magnesium ions into the single-chamber electrolysis chamber at a rate of 50 mL / min to 200 mL / min, and the catholyte containing hydroxide ions, lithium ions and magnesium ions after electrolysis is sent out of the single-chamber electrolysis chamber by the second peristaltic pump at a rate of 10 mL / min to 30 mL / min, and the current density of the electrolysis reaction is 20 mA / cm 2 ~ 40 mA / cm 2 .

[0045] Specifically, the magnesium ion content in the salt lake brine is 250 mg / L to 1000 mg / L, and the lithium ion content is 50 mg / L to 100 mg / L.

[0046] Specifically, the molar ratio of lithium ions to carbonate in the lithium-rich brine concentrate is 1:15 to 20.

[0047] Specificly, the salt lake brine needs to be stirred at room temperature for 5 min to 15 min before being sent into the electrolysis chamber by the first peristaltic pump. It is used to make lithium and magnesium ions uniformly distributed.

[0048] A magnesium-lithium separation system for an electrochemical salt lake brine magnesium removal and lithium extraction method, comprising:

[0049] A raw water tank 1 for storing salt lake brine to be electrolyzed;

[0050] An electrolysis device 2 for electrolyzing the salt lake brine, comprising:

[0051] A single-chamber electrolysis chamber 2-1 connected to the raw water tank 1 through a pipeline and a first peristaltic pump, for sending the salt lake brine into the single-chamber electrolysis chamber 2-1, and the single-chamber electrolysis chamber 2-1 is provided with an anode liquid overflow port and a cathode liquid discharge port;

[0052] An anode 2-2 arranged in the single-chamber electrolysis chamber 2-1, and the anode 2-2 is connected to the positive electrode of the power supply through a wire, so that the salt lake brine generates hydrogen ion-rich salt lake brine at the anode 2-2, and the hydrogen ion-rich salt lake brine is discharged from the anode liquid overflow port, and the anode liquid overflow port is connected to the anode liquid storage device 5 through a pipeline;

[0053] A cathode 2-3 arranged in the single-chamber electrolysis chamber 2-1, and the cathode 2-3 is connected to the negative electrode of the power supply through a wire, so that the salt lake brine generates hydrogen ion-rich salt lake brine at the cathode 2-3;

[0054] A filter component 3 connected to the cathode liquid discharge port through a pipeline and a second peristaltic pump;

[0055] The cathode liquid storage tank 4 is connected to the filter unit 3 via pipelines and a third peristaltic pump, and is used to store the cathode liquid for removing magnesium hydroxide.

[0056] There are many methods for magnesium removal and lithium extraction from salt lake brine, such as membrane methods and chemical methods. Membrane methods suffer from problems like membrane fouling and high costs, while chemical methods involve direct alkali addition, which causes environmental pollution and are considered relatively outdated. This paper proposes a single-chamber membrane-free electrolysis-microfiltration system for high-Mg... 2+ / Li + Mg in salt lake brine 2+ With Li + Selective separation generates Mg(OH)2 precipitate to remove magnesium, achieving efficient magnesium and lithium removal without the need for reagents or membrane electrochemical processes.

[0057] After the catholyte used to remove magnesium hydroxide is concentrated to a certain concentration, sodium carbonate is added to form lithium carbonate precipitate, thus realizing the resource recovery of lithium ions. The entire process consumes only electricity, reducing the need for additional reagents.

[0058] Specifically, the anolyte storage device 5 is connected to the raw water tank 1 via a third peristaltic pump and pipeline. The purpose of sending the anolyte to the raw water tank 1 is for recycling and improving the efficiency of magnesium removal and lithium enrichment.

[0059] Specifically, the single-chamber electrolysis chamber 2-1 has a circular cross-sectional area, and the cathode 2-3 and anode 2-2 are arranged sequentially around the center of the circular single-chamber electrolysis chamber 2-1. The purpose is to improve electrolysis efficiency.

[0060] Specifically, the cathode 2-3 is a conductive stainless steel filter element, and the anode 2-2 is a cylindrical graphite.

[0061] Cathode 2-3 is a conductive stainless steel filter element. The OH- produced by cathode electrolysis is transferred through a second peristaltic pump. - The anolyte is drawn away and discharged through the overflow port to achieve H + OH - The high efficiency of separation, in addition, the cathode 2-3 material is a conductive stainless steel filter element and the anode 2-2 material is graphite, resulting in low electrode cost.

[0062] Specifically, the structure of filter element 3 is given. Filter element 3 includes a microfiltration tank and a microfiltration cartridge. The cathode outlet is connected to the microfiltration tank via a second peristaltic pump and pipeline. The microfiltration cartridge is located inside the microfiltration tank and is used to filter the generated magnesium hydroxide. The microfiltration cartridge is connected to filter element 3 via pipeline and a third peristaltic pump. The anolyte is an acidic solution, which can be used to remove the magnesium hydroxide deposited on the microfiltration cartridge without the need for other reagents, thus reducing costs.

[0063] To explain the invention in more detail, the following examples are provided, but the invention is not limited to these examples.

[0064] The original brine of a domestic salt lake was used for the experiment, and the main components and contents of the brine of the salt lake are shown in Table 1.

[0065] Table 1 Composition of the original brine used in Example 1

[0066] Component Li + ]]> Na + ]]> K + ]]> Mg 2+ ]]> Cl - ]]> Concentration (mg / L) 56 2654 7856 580 49772

[0067] Example 1

[0068] 5L of the brine of the salt lake was added to the raw water tank 1, and after stirring at room temperature for 10 min, it was pumped into the single-chamber electrolysis chamber 2-1 by the first peristaltic pump. The peristaltic pump rate of the first peristaltic pump for pumping the raw water was 100 mL / min, the peristaltic pump rate of the second peristaltic pump for pumping the catholyte was 20 mL / min, and the current density set in the single-chamber electrolysis chamber 2-1 was 30 mA / cm 2 During the electrolysis process, gas was generated at the anode and the cathode. The obtained catholyte was subjected to determination of the contents of magnesium ions and lithium ions in the catholyte, and the pH values of the catholyte and the anolyte were determined. Then, the obtained catholyte was subjected to evaporation and concentration of the lithium-rich solution, and then sodium carbonate was added, and the mass of lithium carbonate was determined after filtration. The experimental results are shown in Table 2.

[0069] Example 2

[0070] 5L of the brine of the salt lake was added to the raw water tank 1, and after stirring at room temperature for 10 min, it was pumped into the single-chamber electrolysis chamber 2-1 by the first peristaltic pump. The peristaltic pump rate of the first peristaltic pump for pumping the raw water was 80 mL / min, the peristaltic pump rate of the second peristaltic pump for pumping the catholyte was 20 mL / min, and the current density set in the single-chamber electrolysis chamber 2-1 was 30 mA / cm 2 During the electrolysis process, gas was generated at the anode and the cathode. The obtained catholyte was subjected to determination of the contents of magnesium ions and lithium ions in the catholyte, and the pH values of the catholyte and the anolyte were determined. Then, the obtained catholyte was subjected to evaporation and concentration of the lithium-rich solution, and then sodium carbonate was added, and the mass of lithium carbonate was determined after filtration. The experimental results are shown in Table 2.

[0071] Example 3

[0072] 5L of the brine of the salt lake was added to the raw water tank 1, and after stirring at room temperature for 10 min, it was pumped into the single-chamber electrolysis chamber 2-1 by the first peristaltic pump. The peristaltic pump rate of the first peristaltic pump for pumping the raw water was 80 mL / min, the peristaltic pump rate of the second peristaltic pump for pumping the catholyte was 20 mL / min, and the current density set in the single-chamber electrolysis chamber 2-1 was 20 mA / cm 2, electrolysis of brine, in the electrolysis process, the anode, cathode will produce gas. Will obtain the catholyte catholyte magnesium ion and lithium ion content determination, while the determination of the pH value of the catholyte and anolyte. Then the obtained catholyte is evaporated and concentrated, and then sodium carbonate is added, and the mass of lithium carbonate is measured after filtration. The experimental results are shown in Table 2.

[0073] Table 2 Magnesium-lithium separation effect of examples 1-3

[0074]

[0075] Example 1 and example 2 are compared, the first peristaltic pump pumping raw water peristaltic pump rate is different, although the magnesium ion in the catholyte is completely removed, but when the first peristaltic pump pumping raw water peristaltic pump rate is 100 mL / min, the lithium ion content in the catholyte is higher, and the time for completely removing magnesium ion in the catholyte is shorter.

[0076] Example 2 and example 3 are compared, the electrolytic current density of example 2 and example 3 is different, the current density of example 2 is larger than that of example 3, so the lithium ion content in the catholyte is higher, and the treatment time for completely removing magnesium ion in the catholyte is shorter.

[0077] The present application uses the first peristaltic pump to pump the hydroxide generated by the cathode boundary layer to combine with the magnesium ion in the pumped catholyte, thereby improving the lithium-magnesium separation efficiency in the catholyte. Based on the cathode alkali extraction strategy, a single-chamber electrolysis-cathode pumping-high-efficiency microfiltration closed-loop system is constructed to realize the selective separation of lithium and magnesium in salt lake brine. The process is simple and easy to operate, can completely separate lithium and magnesium ions, realize 99.98% resource utilization of magnesium ions, and obtain lithium-rich, magnesium-free solution. After evaporation and concentration of the lithium-rich brine, sodium carbonate is added to the concentrated solution to make the concentrated solution react with sodium carbonate to obtain lithium carbonate and realize subsequent utilization of lithium. The whole process greatly reduces the addition of reagents, effectively reduces the production cost, is a green and environmentally friendly magnesium removal and lithium extraction method, and has good industrial production potential and application prospect.

[0078] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

1. A method for removing magnesium and extracting lithium from an electrochemical salt lake brine, characterized in that, The method comprises the following steps: The salt lake brine containing lithium ions and magnesium ions is sent into a single-chamber electrolysis chamber and electrolysis occurs in the single-chamber electrolysis chamber, the content of magnesium ions in the salt lake brine is 250 mg / L-1000 mg / L, and the content of lithium ions is 50 mg / L-100 mg / L; The anode electrolyte containing hydrogen ions, lithium ions and magnesium ions after electrolysis is sent out from the single-chamber electrolysis chamber and collected, and the collected anode electrolyte is sent into the single-chamber electrolysis chamber again to participate in the electrolysis reaction; The cathode liquid containing hydroxide ions, lithium ions and magnesium ions after electrolysis is sent out from the single-chamber electrolysis chamber and filtered, so that the hydroxide ions in the cathode liquid after electrolysis react with the magnesium ions in the salt lake brine to generate magnesium hydroxide precipitate, and the lithium ion-rich salt lake brine obtained after filtration is evaporated and concentrated to obtain lithium-rich brine concentrate; The lithium-rich brine concentrate is added with sodium carbonate to carry out a lithium precipitation reaction to obtain lithium carbonate precipitate, and the lithium carbonate precipitate is centrifuged, washed and dried to obtain lithium carbonate, the molar ratio of lithium ions in the lithium-rich brine concentrate to carbonate ions in sodium carbonate is 1:15-20, the first peristaltic pump is used to send the salt lake brine containing lithium ions and magnesium ions into a single-chamber electrolysis chamber at a rate of 50 mL / min-200 mL / min, the catholyte containing hydroxyl ions, lithium ions and magnesium ions after electrolysis is sent out from the single-chamber electrolysis chamber by a second peristaltic pump at a rate of 10 mL / min-30 mL / min, and the current density of the electrolysis reaction is 20 mA / cm 2 -40 mA / cm 2 . The system used for the electrochemical salt lake brine magnesium removal and lithium extraction comprises: A raw water tank (1) for storing the salt lake brine to be electrolyzed; An electrolysis device (2) for electrolyzing the salt lake brine, comprising: A single-chamber electrolysis chamber (2-1) connected with the raw water tank (1) through a pipeline and a first peristaltic pump, for sending the salt lake brine into the single-chamber electrolysis chamber (2-1), and the single-chamber electrolysis chamber (2-1) is provided with an anode liquid overflow port and a cathode liquid discharge port; An anode (2-2) in the form of a cylindrical graphite provided in the single-chamber electrolysis chamber (2-1), the anode (2-2) is connected with the positive pole of a power supply through a wire, so that the salt lake brine generates hydrogen ion-rich salt lake brine at the anode (2-2), and the hydrogen ion-rich salt lake brine is discharged from the anode liquid overflow port, the anode liquid overflow port is connected with an anode liquid storage device (5) through a pipeline; A cathode (2-3) in the form of a conductive stainless steel filter element provided in the single-chamber electrolysis chamber (2-1), the cathode (2-3) is connected with the negative pole of the power supply through a wire, so that the salt lake brine generates hydroxide ion-rich salt lake brine at the cathode (2-3); A filtering component (3) connected with the cathode liquid discharge port through a pipeline and a second peristaltic pump; A cathode liquid storage tank (4) connected with the filtering component (3) through a pipeline and a third peristaltic pump, for storing the cathode liquid from which magnesium hydroxide has been removed.

2. The method for removing magnesium and extracting lithium from electrochemical salt lake brine according to claim 1, characterized in that, The salt lake brine needs to be stirred at room temperature for 5 min-15 min before being sent into the electrolysis chamber by the first peristaltic pump.

3. The method for removing magnesium and extracting lithium from electrochemical salt lake brine according to claim 1, characterized in that, The anode liquid storage device (5) is connected with the raw water tank (1) through a third peristaltic pump and a pipeline.

4. The method for removing magnesium and extracting lithium from electrochemical salt lake brine according to claim 1, characterized in that, The single-chamber electrolysis chamber (2-1) has a circular cross section, and the cathode (2-3) and the anode (2-2) are arranged in sequence from the center of the circular single-chamber electrolysis chamber (2-1).

5. The method for removing magnesium and extracting lithium from electrochemical salt lake brine according to claim 1, characterized in that, The cathode (2-3) is a conductive stainless steel filter element, and the anode (2-2) is a cylindrical graphite.

6. The method for removing magnesium and extracting lithium from electrochemical salt lake brine according to claim 1, characterized in that, The filtering component (3) comprises a microfiltration tank and a microfiltration filter element, the cathode liquid discharge port is communicated with the microfiltration tank through a second peristaltic pump and a pipeline, the microfiltration filter element is provided in the microfiltration tank and used for filtering the generated magnesium hydroxide, and the microfiltration filter element is connected with the filtering component (3) through a pipeline and a third peristaltic pump.

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