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

Abstract

The invention provides an electrochemical method for removing magnesium and extracting lithium from salt lake brine, which comprises the following steps: feeding the salt lake brine into a single-chamber electrolysis chamber, and carrying out electrolytic reaction in the single-chamber electrolysis chamber; the anolyte after electrolysis is sent out from the single-chamber electrolysis chamber and collected, and the collected anolyte is sent into the single-chamber electrolysis chamber again to participate in the electrolytic reaction; the electrolyzed catholyte is sent out from the single-chamber electrolysis chamber and filtered, hydroxyl ions in the electrolyzed catholyte react with magnesium ions in the salt lake brine to generate magnesium hydroxide precipitates, and the filtered lithium-ion-rich salt lake brine is evaporated and concentrated to obtain a lithium-ion-rich brine concentrated solution; sodium carbonate is added into the lithium-rich brine concentrated solution for a lithium precipitation reaction, lithium carbonate precipitates are obtained, and lithium carbonate is obtained after the lithium carbonate precipitates are centrifuged, washed and dried. The invention further provides a magnesium and lithium separation system of the electrochemical salt lake brine magnesium removal and lithium extraction method. The method realizes efficient separation of lithium and magnesium in the salt lake brine and extraction of lithium.

Description

Technical Field

[0001] The invention relates to the technical field of removing magnesium and extracting lithium from salt lake brine, and in particular to a method for removing magnesium and extracting lithium from electrochemical salt lake brine and a magnesium-lithium separation system. Background Art

[0002] As an important component of new energy materials in the 21st century, lithium is widely used in many fields such as batteries, ceramics and medicine, and is known as "an important element that drives the world forward."

[0003] With the development of new energy vehicles, the demand for lithium continues to rise, and the global production of lithium salts comes from brine and hard rock ores (accounting for 63% and 37% respectively). Compared with the ore lithium extraction process, the advantages of salt lake brine lithium extraction are 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, a green, efficient and low-cost magnesium removal and lithium extraction process is urgently needed to meet this challenge.

[0004] At present, the technologies for extracting lithium from salt lake brine mainly include precipitation, adsorption and membrane separation. Among them, precipitation is the most mature and simple process at present, because it was first applied in salt lakes with low magnesium-lithium ratios. Although the precipitation method is relatively simple to operate, it has a long process cycle, its operation is limited by climatic conditions, and it will produce a large number of by-products. Therefore, it does not have an advantage in extracting lithium from salt lake brine with a high magnesium-lithium ratio. The adsorption method has the advantages of good selectivity, low energy consumption, and high lithium absorption capacity, but the slow exchange rate and high solubility lead to poor economic efficiency, which is the reason why it cannot be promoted in industry. Although the membrane separation method has environmental advantages in extracting lithium from salt lake brine, its disadvantages are the short life of the membrane and the high water and energy consumption. Therefore, there is an urgent need for a low-cost, green, and pollution-free method and system for removing magnesium and extracting lithium. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an electrochemical salt lake brine magnesium removal and lithium extraction method and a magnesium-lithium separation system, aiming to solve the problems raised in the technical background and achieve efficient separation of lithium and magnesium and extraction of lithium in high-magnesium and low-lithium salt lake brine. In addition, the operation process is simple, the production cost is low, the whole process is pollution-free, and it is suitable for industrial applications.

[0006] In order to solve the above technical problems, the first implementation scheme provided by the present invention is to provide a method for removing magnesium and extracting lithium from electrochemical salt lake brine, comprising the following steps:

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

[0008] After electrolysis, the anolyte containing hydrogen ions, lithium ions and magnesium ions is sent out from the single-chamber electrolysis chamber and collected, and the collected anolyte is sent back into the single-chamber electrolysis chamber to participate in the electrolysis reaction;

[0009] 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 as to react the hydroxide ions in the cathode liquid after electrolysis 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] Sodium carbonate is added to the lithium-rich brine concentrate 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 fed into the single-chamber electrolysis chamber by a first peristaltic pump at a rate of 50 mL / min to 200 mL / min, and the cathode liquid containing hydroxide ions, lithium ions and magnesium ions after electrolysis is fed out of the single-chamber electrolysis chamber by a 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 ~40mA / cm 2 .

[0012] Preferably, 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.

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

[0014] Preferably, sodium carbonate is added to the lithium-rich brine concentrate to carry out lithium precipitation reaction to obtain a 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 for 5 minutes to 15 minutes at room temperature before being fed into the electrolysis chamber by the first peristaltic pump.

[0016] The second implementation scheme provided by the present invention is to provide a magnesium-lithium separation system for an electrochemical salt lake brine magnesium removal and lithium extraction method, comprising:

[0017] Raw water tank, used to store salt lake brine that needs electrolysis;

[0018] An electrolysis device for electrolyzing salt lake brine, comprising:

[0019] The single-chamber electrolysis chamber is connected to the raw water tank through a pipeline and a first peristaltic pump, and is used to deliver salt lake brine into the single-chamber electrolysis chamber. 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 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, 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 through a pipeline;

[0021] A cathode is arranged in the single-chamber electrolysis chamber, and the cathode is connected to the negative electrode of the power supply through a wire, so that the salt lake brine generates salt lake brine rich in hydroxide ions at the cathode;

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

[0023] The cathode liquid storage tank is connected to the filtering 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 anolyte storage device is connected to the raw water tank via a third peristaltic pump and a pipeline.

[0025] Preferably, the cross-sectional area of ​​the single-chamber electrolytic chamber is circular, and the cathode and the anode are arranged in sequence from the center of the circular single-chamber electrolytic chamber.

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

[0027] Preferably, the filtering component includes a microfiltration tank and a microfiltration filter element. The cathode liquid discharge outlet is connected to the microfiltration tank through a second peristaltic pump and a pipeline. The microfiltration filter element is arranged in the microfiltration tank and is used to filter the generated magnesium hydroxide. The microfiltration filter element is connected to the filtering component through a pipeline and a third peristaltic pump.

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

[0029] 1. The present invention uses a first peristaltic pump to send salt lake brine into a single-chamber electrolysis chamber to perform electrolysis reaction with the anode and cathode in the single-chamber electrolysis chamber. The anolyte containing hydrogen ions generated by the salt lake brine after the anode electrolysis and the electrolyte containing hydroxide generated after the cathode electrolysis are respectively sent out of the single-chamber electrolysis chamber. The method can realize the effective separation of the cathode liquid and the anode liquid, and does not require the use of a membrane, thereby avoiding the problems of short membrane life, large water consumption and energy consumption in the membrane separation method for lithium extraction from salt lake brine. At the same time, the cathode liquid after electrolysis of the present invention is sucked out by the second peristaltic pump. The cathode liquid after suction has a high content of hydroxide ions, so it can react with magnesium ions in the salt lake brine to generate magnesium hydroxide precipitation. The precipitation process cycle is short and no by-products are generated, so it has advantages in extracting lithium from salt lake brine with a high magnesium-to-lithium ratio. In addition, the present invention does not have an exchange rate or solubility, so it has low cost and high economic efficiency, and can be vigorously promoted in industry.

[0030] 2. The electrochemical salt lake brine magnesium removal and lithium extraction method and system provided by the present invention removes magnesium, and the magnesium removal efficiency is ≥99.9%. The lithium ions in the obtained cathode electrolyte still exist in the solution in the form of ions. The lithium ion concentration in the lithium-rich brine concentrate is 20 to 30 times that of the lithium ions in the original salt lake brine. Sodium carbonate is added to the concentrate to carry out lithium precipitation reaction, and the precipitate is centrifuged and washed, and dried to finally obtain lithium carbonate. This method achieves the effect of magnesium precipitation and lithium enrichment and magnesium removal and lithium extraction. In the present invention, the anolyte is circulated and sent into the raw water tank to participate in the electrolysis reaction again, so that no anodic acid is generated, and the cathode liquid (lithium chloride solution, lithium sulfate) generated during the lithium extraction process does not pollute the environment.

[0031] 3. This method can be used to treat brines with different high-concentration magnesium-lithium ratios, and can also treat different types of brines. This method can achieve 99.98% resource utilization of magnesium ions, and the generated magnesium hydroxide is recycled as a product. In addition, the electrochemical salt lake brine magnesium removal and lithium extraction system provided by the present invention can achieve membrane-free and drug-free removal of magnesium ions, achieving efficient magnesium-lithium separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of the electrochemical salt lake brine magnesium removal and lithium extraction process.

[0033] Figure 2 This is a process diagram for the precipitation of lithium ions with sodium carbonate in the electrochemical salt lake brine for removing magnesium and extracting lithium.

[0034] Description of reference numerals:

[0035] 1. Raw water tank; 2. Electrolysis device; 2-1. Single-chamber electrolysis chamber; 2-2. Anode; 2-3. Cathode; 3. Filter component; 4. Cathode liquid storage tank; 5. Anode liquid storage. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The inventors found that there are many methods for extracting lithium from salt lake brine, such as membrane method and reagent method. The membrane method will cause membrane pollution and high membrane cost. The reagent method is to directly add alkali, which will cause environmental pollution problems. The method is relatively backward. 2+ / Li + Mg in salt lake brine 2+ With Li + Selective separation generates Mg(OH)2 precipitate to remove magnesium, achieving the effect of efficient magnesium removal and lithium enrichment without adding chemicals and membrane electrochemistry. Sodium carbonate is added in the later stage to generate lithium carbonate precipitate to realize lithium ion resource utilization.

[0038] In view of this, the present invention provides a method and system for removing magnesium from electrochemical salt lake brine and extracting lithium, which can achieve efficient separation of lithium and magnesium and extraction of lithium from high-magnesium and low-lithium salt lake brine. The method has simple operation process, low production cost, no pollution in the whole process, and is suitable for industrial application.

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

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

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

[0042] 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 as to react the hydroxide ions in the cathode liquid after electrolysis 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;

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

[0044] Specifically, the salt lake brine containing lithium ions and magnesium ions is fed into the single-chamber electrolysis chamber by a first peristaltic pump at a rate of 50 mL / min to 200 mL / min, and the cathode liquid containing hydroxide ions, lithium ions and magnesium ions after electrolysis is fed out of the single-chamber electrolysis chamber by a second peristaltic pump at a rate of 10 mL / min to 30 mL / min. The current density of the electrolysis reaction is 20 mA / cm 2 ~40mA / 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 in the lithium-rich brine concentrate to carbonate ions in sodium carbonate is 1:15-20.

[0047] Specifically, the salt lake brine needs to be stirred for 5 to 15 minutes at room temperature before being fed into the electrolysis chamber by the first peristaltic pump, so as to make the lithium and magnesium ions evenly distributed.

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

[0049] Raw water tank 1, used to store salt lake brine that needs to be electrolyzed;

[0050] The electrolysis device 2 is used for electrolyzing salt lake brine, comprising:

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

[0052] The anode 2-2 is 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] The cathode 2-3 is 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 salt lake brine rich in hydroxide ions at the cathode 2-3;

[0054] The filter component 3 is 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 component 3 through a pipeline and a third peristaltic pump, and is used to store the cathode liquid from which magnesium hydroxide has been removed.

[0056] There are many methods for extracting lithium from salt lake brine, such as membrane method and reagent method. The membrane method will cause membrane pollution and high membrane cost. The reagent method is to directly add alkali, which will cause environmental pollution problems. The method is relatively backward. 2+ / Li + Mg in salt lake brine 2+ With Li + Selectively separate and generate Mg(OH)2 precipitate to remove magnesium, achieving the effect of efficient magnesium removal and lithium enrichment without adding chemicals and membrane electrochemistry.

[0057] The cathode liquid from which magnesium hydroxide has been removed is concentrated to a certain concentration and then sodium carbonate is added to generate lithium carbonate precipitation, realizing lithium ion resource utilization. The whole process only consumes electricity, reducing the addition of reagents.

[0058] Specifically, the anolyte storage device 5 is connected to the raw water tank 1 through a third peristaltic pump and a pipeline. The anolyte is sent to the raw water tank 1 for circulation treatment to improve the efficiency of magnesium removal and lithium enrichment.

[0059] Specifically, the cross-sectional area of ​​the single-chamber electrolysis chamber 2-1 is circular, 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, in order to improve the electrolysis efficiency.

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

[0061] Cathode 2-3 is a conductive stainless steel filter element, which uses the second peristaltic pump to pump the OH produced by cathode electrolysis. - Pump away and discharge the anolyte through the overflow port to achieve H + OH - Efficient separation, in addition, the cathode 2-3 material is a conductive stainless steel filter element, the anode 2-2 material is graphite, and the electrode cost is low.

[0062] Specifically, the specific structure of the filter component 3 is given, and the filter component 3 includes a microfiltration tank and a microfiltration filter element. The cathode liquid outlet is connected to the microfiltration tank through a second peristaltic pump and a pipeline. The microfiltration filter element is arranged in the microfiltration tank and is used to filter the generated magnesium hydroxide. The microfiltration filter element is connected to the filter component 3 through a 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 filter element, without the need to use other agents, thereby reducing costs.

[0063] In order to explain the present invention in more detail, the following examples are given for illustration, but the present invention is not limited to such examples.

[0064] The experiment was conducted using raw brine from a domestic salt lake. The main components and contents of the brine are shown in Table 1:

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

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

[0067] Example 1

[0068] 5L of salt lake brine was added to the raw water tank 1, stirred for 10 minutes at room temperature, and then pumped into the single-chamber electrolysis chamber 2-1 by the first peristaltic pump. The peristaltic pump rate of the first peristaltic pump to pump the raw water was 100mL / min, and the peristaltic pump rate of the second peristaltic pump to pump the cathode liquid was 20mL / min. The current density set in the single-chamber electrolysis chamber 2-1 was 30mA / cm 2 During the electrolysis process, both the anode and cathode will produce gas. The obtained cathode liquid is used to determine the magnesium ion and lithium ion content of the cathode liquid, and the pH values ​​of the cathode liquid and the anode liquid are determined at the same time. The obtained cathode liquid is then evaporated and concentrated into a lithium-rich solution, sodium carbonate is added, and the mass of lithium carbonate is weighed after filtering. The experimental results are shown in Table 2

[0069] Example 2

[0070] 5L of salt lake brine was added to the raw water tank 1, stirred for 10 minutes at room temperature, and then sent to the single-chamber electrolysis chamber 2-1 through the first peristaltic pump. The first peristaltic pump pumped the raw water at a rate of 80mL / min, and the second peristaltic pump pumped the cathode liquid at a rate of 20mL / min. The current density set in the single-chamber electrolysis chamber 2-1 was 30mA / cm 2 , brine electrolysis is performed, and gas is generated at the anode and cathode during the electrolysis process. The obtained cathode liquid is used to determine the content of magnesium ions and lithium ions in the cathode liquid, and the pH values ​​of the cathode liquid and the anode liquid are determined at the same time. The obtained cathode liquid is then evaporated and concentrated into a lithium-rich solution, sodium carbonate is added, and the mass of lithium carbonate is weighed after filtering. The experimental results are shown in Table 2.

[0071] Example 3

[0072] 5L of salt lake brine was added to the raw water tank 1, stirred for 10 minutes at room temperature, and then sent to the single-chamber electrolysis chamber 2-1 through the first peristaltic pump. The first peristaltic pump pumped the raw water at a rate of 80mL / min, and the second peristaltic pump pumped the cathode liquid at a rate of 20mL / min. The current density set in the single-chamber electrolysis chamber 2-1 was 20mA / cm 2, brine electrolysis is performed, and gas is generated at the anode and cathode during the electrolysis process. The obtained cathode liquid is used to determine the content of magnesium ions and lithium ions in the cathode liquid, and the pH values ​​of the cathode liquid and the anode liquid are determined at the same time. The obtained cathode liquid is then evaporated and concentrated into a lithium-rich solution, sodium carbonate is added, and the mass of lithium carbonate is weighed after filtering. The experimental results are shown in Table 2.

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

[0074]

[0075] Compared with Example 1, the peristaltic pump rate of the first peristaltic pump for pumping raw water is different. Although the magnesium ions in the cathode liquid are completely removed, when the peristaltic pump rate of the first peristaltic pump for pumping raw water is 100 mL / min, the lithium ion content in the cathode liquid is higher and the time required for complete removal of the magnesium ions in the cathode liquid is shorter.

[0076] Compared with Example 3, the electrolysis current density of Example 2 is different from that of Example 3. The current density of Example 2 is larger than that of Example 3, so the lithium ion content of the cathode liquid is higher, and the treatment time for completely removing the magnesium ions in the cathode liquid is shorter.

[0077] The present invention uses electrochemical equipment to perform electrolysis, and utilizes a first peristaltic pump to pump the hydroxide generated in the cathode boundary layer, which is used to combine with the magnesium ions in the absorbed cathode liquid, thereby improving the lithium-magnesium separation efficiency in the cathode liquid. Based on the cathode alkali solution extraction strategy, a single-chamber electrolysis-cathode pumping-high-efficiency microfiltration closed-loop system is constructed to achieve the selective separation of lithium and magnesium in salt lake brine. The process is simple and easy to operate, and can completely separate lithium and magnesium ions, achieve 99.98% resource utilization of magnesium ions, and obtain a lithium-rich, magnesium-free solution. After the lithium-rich brine is evaporated and concentrated, sodium carbonate is added to the concentrated solution, and the concentrated solution is reacted with sodium carbonate to precipitate lithium, and lithium carbonate is obtained to achieve the subsequent utilization of lithium. The entire process greatly reduces the addition of reagents, effectively reducing the production cost. It is a green and environmentally friendly method for removing magnesium and extracting lithium, and has good industrial production potential and application prospects.

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

Claims

1. A method for removing magnesium and extracting lithium from electrochemical salt lake brine, characterized in that: The steps include: Salt lake brine containing lithium ions and magnesium ions is fed into a single-chamber electrolysis chamber, and an electrolysis reaction occurs in the single-chamber electrolysis chamber; After electrolysis, the anolyte containing hydrogen ions, lithium ions and magnesium ions is sent out from the single-chamber electrolysis chamber and collected, and the collected anolyte is sent back into the single-chamber electrolysis chamber 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 as to react the hydroxide ions in the cathode liquid after electrolysis 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; Sodium carbonate is added to the lithium-rich brine concentrate 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.

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 containing lithium ions and magnesium ions is fed 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 hydroxide ions, lithium ions and magnesium ions after electrolysis is fed out of the single-chamber electrolysis chamber by the second peristaltic pump at a rate of 10 mL / min to 30 mL / min. The current density of the electrolysis reaction is 20 mA / cm 2 ~40mA / cm 2 .

3. The method for removing magnesium and extracting lithium from electrochemical salt lake brine according to claim 1, characterized in that: The magnesium ion content in the salt lake brine is 250mg / L to 1000mg / L, and the lithium ion content is 50mg / L to 100mg / L.

4. The method for removing magnesium and extracting lithium from electrochemical salt lake brine according to claim 1, characterized in that: The molar ratio of lithium ions in the lithium-rich brine concentrate to carbonate ions in sodium carbonate is 1:15-20.

5. 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 for 5 to 15 minutes at room temperature before being fed into the electrolysis chamber by the first peristaltic pump.

6. A magnesium-lithium separation system for an electrochemical salt lake brine magnesium removal and lithium extraction method according to any one of claims 1 to 5, characterized in that: include: A raw water tank (1) is used to store salt lake brine that needs to be electrolyzed; The electrolysis device (2) is used for electrolyzing salt lake brine, comprising: The single-chamber electrolysis chamber (2-1) is connected to the raw water tank (1) via a pipeline and a first peristaltic pump, and is used to deliver salt lake brine into the single-chamber electrolysis chamber (2-1). 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) is disposed in the single-chamber electrolysis chamber (2-1), and the anode (2-2) is connected to the positive electrode of a power source via a wire, so that 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 an anode liquid overflow port, and the anode liquid overflow port is connected to an anode liquid storage device (5) via a pipeline; A cathode (2-3) is disposed in the single-chamber electrolysis chamber (2-1), and the cathode (2-3) is connected to the negative electrode of a power source via a wire, so that salt lake brine is converted into salt lake brine rich in hydroxide ions at the cathode (2-3); A filter component (3) is connected to the cathode liquid discharge port through a pipeline and a second peristaltic pump; The cathode liquid storage tank (4) is connected to the filter component (3) through a pipeline and a third peristaltic pump, and is used to store the cathode liquid from which magnesium hydroxide has been removed.

7. The magnesium-lithium separation system according to claim 6, characterized in that: The anolyte storage device (5) is connected to the raw water tank (1) via a third peristaltic pump and a pipeline.

8. The magnesium-lithium separation system according to claim 6, characterized in that: The cross-sectional area of ​​the single-chamber electrolytic chamber (2-1) is circular, and the cathode (2-3) and the anode (2-2) are arranged in sequence from the center of the circular single-chamber electrolytic chamber (2-1).

9. The magnesium-lithium separation system according to claim 6, characterized in that: The cathode (2-3) is a conductive stainless steel filter element, and the anode (2-2) is cylindrical graphite.

10. The magnesium-lithium separation system according to claim 6, characterized in that: The filtering component (3) comprises a microfiltration tank and a microfiltration filter element. The cathode liquid discharge port is connected to the microfiltration tank via a second peristaltic pump and a pipeline. The microfiltration filter element is arranged in the microfiltration tank and is used to filter the generated magnesium hydroxide. The microfiltration filter element is connected to the filtering component (3) via a pipeline and a third peristaltic pump.

Images