A device and method for extracting lithium from salt lakes

Abstract

The present invention discloses a device and method for extracting lithium from salt lakes, belonging to the technical field of lithium extraction from salt lakes, including a feed liquid tank, a cathode chamber, an anode chamber, an extraction tank, and a boron removal tank. The feed liquid tank, the cathode chamber, the anode chamber, the extraction tank, and the boron removal tank are sequentially separated by an exchange membrane, and the extraction tank is connected with a stripping tank. By setting the extraction tank and the boron removal tank, the formation of boric acid precipitation is effectively avoided during the process of extracting lithium, which affects the extraction of lithium. In addition, the boron removal reaction is carried out while extracting lithium, and it is not necessary to pre-treat the brine to remove boron in advance, which simplifies the process and effectively improves the recovery rate and purity of lithium.

Description

Technical Field

[0001] This article relates to the technical field of lithium extraction from salt lakes, and specifically relates to a device and method for lithium extraction from salt lakes. Background Art

[0002] Lithium and its compounds are widely used in fields such as glass, ceramics, batteries, and the nuclear industry due to many important properties. In recent years, due to the rapid development of electric vehicles, lithium-ion lithium batteries have become one of the fastest-growing fields. And 80% of the global lithium production capacity comes from salt lakes. China has very rich brine lithium resources, mainly based on the lithium resource reserves in Qinghai salt lakes. The brine in Qinghai salt lakes belongs to a multi-component system with a complex composition. Among them, inorganic salts mostly exist in the form of monovalent or divalent ions. The lithium and magnesium ion radii are similar and their chemical properties are similar. The high magnesium-lithium ratio is the main characteristic of Qinghai salt lake resources. The lithium ion concentration is between 0.3 g / L and 6 g / L, the magnesium ion concentration is between 100 and 125 g / L, and the mass ratio of magnesium to lithium is between (20 - 100):1, making the separation of magnesium and lithium difficult, and it is also the key and focus of the lithium extraction technology from salt lakes.

[0003] For the lithium extraction from salt lakes with a high magnesium-lithium ratio, precipitation method, extraction method, and ion exchange adsorption method have been studied widely and deeply. In China, the experimental scale of lithium extraction by TBP extraction method is large and the most in-depth. It is the most effective method for extracting lithium from brine with a high magnesium-lithium ratio and is one of the lithium extraction methods from high magnesium-lithium ratio brines in salt lakes with industrial application prospects. However, when using the TBP extraction method to extract lithium, FeCl3 is inevitably used as a co-extractor. Since the organic phase contains the co-extractor, this requires the brine to be kept weakly acidic, otherwise Fe hydrolysis will occur. The brine entering the extraction section must be acidified. And in the salt lakes in the Qinghai-Tibet region of China, lithium and boron generally coexist. Borate will inevitably precipitate out during the acidification process, and boron removal treatment needs to be carried out in advance.

[0004] In view of this, this article is proposed. Summary of the Invention

[0005] The purpose of this article is to overcome the deficiencies of the prior art and provide a device and method for lithium extraction from salt lakes, which can effectively avoid the formation of boric acid precipitation and affect the extraction of lithium during the extraction process. In addition, boron removal reaction is carried out while extracting lithium, and it is not necessary to pre-treat the brine for boron removal in advance, which simplifies the process and effectively improves the recovery rate and purity of lithium.

[0006] To achieve the above purpose, the technical solutions adopted in this article are as follows:

[0007] A lithium extraction device from salt lakes, comprising a feed liquid tank, a cathode chamber, an anode chamber, an extraction tank, and a boron removal tank. The feed liquid tank, the cathode chamber, the anode chamber, the extraction tank, and the boron removal tank are sequentially separated by a membrane. The extraction tank is connected to a stripping tank. A cathode is provided in the cathode chamber, and an anode is provided in the anode chamber. The cathode and the anode are arranged opposite to each other.

[0008] In this paper, by setting an extraction tank and a boron removal tank, during the lithium extraction process, the cations of the lithium-containing brine enter the extraction tank, and the organic extraction system extracts lithium from the aqueous phase to obtain a loaded organic phase and a raffinate. Anions such as borate ions enter the boron removal tank, effectively avoiding the formation of boric acid precipitation during the lithium extraction process and affecting the lithium extraction. In addition, a boron removal reaction is carried out while extracting lithium, eliminating the need for pre-treatment of the brine to remove boron, simplifying the process, and effectively improving the recovery rate and purity of lithium.

[0009] In one embodiment, the cathode is connected to the negative electrode of a power source through a wire, and the anode is connected to the positive electrode of the power source through a conductor.

[0010] In one embodiment, a stirring paddle is provided in the extraction tank.

[0011] In one embodiment, the feed liquid tank and the extraction tank are separated by a cation exchange membrane.

[0012] In one embodiment, the boron removal tank and the anode chamber are separated by a cation exchange membrane.

[0013] In one embodiment, the feed liquid tank and the boron removal tank are separated by an anion exchange membrane.

[0014] In one embodiment, the extraction tank and the cathode chamber are separated by an anion exchange membrane.

[0015] In one embodiment, the cathode and the anode are each independently selected from one of an Ag electrode and a Pt electrode.

[0016] This paper also provides a method for extracting lithium from salt lakes. The lithium extraction method is carried out using the above-mentioned lithium extraction device from salt lakes, and includes the following steps:

[0017] Sodium chloride solution is respectively introduced into the cathode chamber and the anode chamber, water is introduced into the boron removal tank, lithium-containing brine is introduced into the feed liquid tank, and an organic solution is introduced into the extraction tank;

[0018] A voltage is applied to the anode and the cathode for reaction. After the reaction is completed, hydrochloric acid solution is added to the boron removal tank, and the extraction tank is allowed to stand for phase separation to obtain a lithium-containing organic phase. The lithium-containing organic phase enters the stripping tank, and hydrochloric acid solution is added to the stripping tank to strip the lithium in the loaded organic phase into the aqueous phase to obtain a lithium-rich solution.

[0019] In this paper, the reaction of the lithium extraction process is carried out in an electrodialysis cell. Under the action of an electric field, borate ions and cations in the brine enter the boron removal cell and the extraction cell respectively, effectively avoiding the formation of boric acid precipitation during the lithium extraction process, which affects the lithium extraction. In addition, the boron removal reaction is carried out while extracting lithium, and there is no need to pre-treat the brine to remove boron, simplifying the process and effectively improving the lithium recovery rate and purity.

[0020] In one embodiment, the concentration of the sodium chloride solution is 0.1 - 1 mol / L.

[0021] In one embodiment, the preparation method of the organic solution is as follows: mix the extractant and the diluent to obtain a blank organic phase, prepare a mixed solution containing 0.5 mol / L ferric chloride and 0.5 mol / L hydrochloric acid, mix the mixed solution with the blank organic phase evenly, shake and then let it stand for phase separation, and mix the organic phase with water evenly to obtain the organic solution;

[0022] The mass ratio of the extractant to the diluent is (50 - 70):(30 - 50);

[0023] The volume ratio of the mixed solution to the blank organic phase is 1:(0.5 - 2);

[0024] The mass ratio of the organic phase to water is (1 - 2):1.

[0025] In one embodiment, the extractant is tributyl phosphate.

[0026] In one embodiment, the diluent is kerosene.

[0027] In one embodiment, the voltage applied to the anode is 0.8 - 1.2 V, and the current density is 380 - 420 A / m 2 , and the reaction time is 30 - 60 min.

[0028] In one embodiment, during the reaction, the stirring rate of the stirring paddle in the extraction cell is 400 - 600 rpm.

[0029] In one embodiment, the volume ratio of the hydrochloric acid solution to the lithium-containing organic phase is (20 - 40):1.

[0030] In one embodiment, the concentration of the hydrochloric acid solution is 0.2 - 6 mol / L.

[0031] The beneficial effects of this article are as follows: (1) By setting up an extraction tank and a boron removal tank, during the lithium extraction process, the cations in the lithium-containing brine enter the extraction tank, and the organic extraction system extracts lithium from the aqueous phase to obtain a loaded organic phase and a raffinate. Anions such as borate radicals enter the boron removal tank, effectively avoiding the formation of boric acid precipitation during the lithium extraction process, which affects the extraction of lithium. In addition, the boron removal reaction is carried out while extracting lithium, eliminating the need for pre-treatment of the brine to remove boron, simplifying the process, and effectively improving the recovery rate and purity of lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of the salt lake lithium extraction device of this article.

[0033] Markings in the figure: 1, feed liquid tank; 2, cathode chamber; 3, anode chamber; 4, extraction tank; 5, boron removal tank; 6, stripping tank; 7, cation exchange membrane; 8, anion exchange membrane; 9, anode; 10, cathode; 11, positive electrode; 12, negative electrode. SPECIFIC EMBODIMENTS

[0034] To better illustrate the purpose, technical solutions, and advantages of this article, the following will further explain this article in combination with specific examples and comparative examples. The purpose is to understand the content of this article in detail, rather than to limit this article.

[0035] Unless otherwise specified, the component raw materials used in each example and comparative example of this article are all commercially available raw materials, and the component raw materials used in each parallel experiment are the same.

[0036] Example 1

[0037] As Figure 1 shown, this example provides a salt lake lithium extraction device, including a feed liquid tank 1, a cathode chamber 2, an anode chamber 3, an extraction tank 4, and a boron removal tank 5. The feed liquid tank 1, cathode chamber 2, anode chamber 3, extraction tank 4, and boron removal tank 5 are separated by exchange membranes in sequence. The extraction tank 4 is connected to a stripping tank 6. The cathode 10 is arranged in the cathode chamber 2, and the anode 9 is arranged in the anode chamber 3. The cathode 10 and the anode 9 are arranged opposite to each other.

[0038] In one embodiment, the cathode 10 is connected to the negative electrode 12 of the power supply through a wire, and the anode 9 is connected to the positive electrode 11 of the power supply through conduction.

[0039] In one embodiment, a stirring paddle is arranged in the extraction tank 4.

[0040] More specifically, the feed liquid tank 1 and the extraction tank 5 are separated by a cation exchange membrane 7, the boron removal tank 4 and the anode chamber 3 are separated by a cation exchange membrane 7, the feed liquid tank 1 and the boron removal tank 4 are separated by an anion exchange membrane 8, and the extraction tank 4 and the cathode chamber 2 are separated by an anion exchange membrane 8.

[0041] Example 2

[0042] A method for extracting lithium from salt lakes, which uses the salt lake lithium extraction device described in Example 1 and includes the following steps:

[0043] Mix TBP (tributyl phosphate) and kerosene evenly according to a mass ratio of 60:40 to obtain a blank organic phase. Mix the blank organic phase and a solution containing 0.5 mol / L ferric chloride and 0.5 mol / L hydrochloric acid in a volume ratio of 1:1, shake and then let it stand for phase separation to obtain an organic phase. Mix the organic phase and water evenly in a volume ratio of 2:1 to obtain an organic solution;

[0044] Introduce 0.5 mol / L sodium chloride solution into the cathode chamber and the anode chamber respectively, introduce water into the boron removal tank, introduce lithium-containing brine into the feed liquid tank, and introduce the organic solution into the extraction tank;

[0045] Apply a voltage to the anode and the anode for reaction for 45 minutes. The applied voltage is 1 V and the current density is 400 A / m 2 , the stirring rate of the stirring paddle in the extraction tank is 500 rpm. After the reaction is completed, add 0.6 mol / L hydrochloric acid solution to the boron removal tank until boric acid precipitation forms. Let the extraction tank stand for phase separation to obtain a lithium-containing organic phase. Flow the lithium-containing organic phase out from the lower end of the extraction tank and into the stripping tank to mix and react with 3 mol / L hydrochloric acid solution for 30 minutes. The volume ratio of the lithium-containing organic phase to hydrochloric acid is 20:1. Strip the lithium in the loaded organic phase into the aqueous phase to obtain a lithium-rich solution.

[0046] Example 3

[0047] A method for extracting lithium from salt lakes, which uses the salt lake lithium extraction device described in Example 1 and includes the following steps:

[0048] Mix TBP and kerosene evenly according to a mass ratio of 50:50 to obtain a blank organic phase. Mix the blank organic phase and a solution containing 0.1 mol / L ferric chloride and 0.1 mol / L hydrochloric acid in a volume ratio of 1:1, shake and then let it stand for phase separation to obtain an organic phase. Mix the organic phase and water evenly in a volume ratio of 1:1 to obtain an organic solution;

[0049] Introduce 0.5 mol / L sodium chloride solution into the cathode chamber and the anode chamber respectively, introduce water into the boron removal tank, introduce lithium-containing brine into the feed liquid tank, and introduce the organic solution into the extraction tank;

[0050] Apply a voltage to the anode for 30 minutes for the reaction. The applied voltage is 0.8 V and the current density is 380 A / m 2 , the stirring rate of the stirring paddle in the extraction tank is 400 rpm. After the reaction is completed, add 0.2 mol / L hydrochloric acid solution to the boron removal tank until boric acid precipitation forms. Let the extraction tank stand for phase separation to obtain the lithium-containing organic phase. Flow the lithium-containing organic phase out from the lower end of the extraction tank and into the stripping tank to mix and react with 1 mol / L hydrochloric acid solution for 40 minutes. The volume ratio of the lithium-containing organic phase to hydrochloric acid is 20:1. Strip the lithium in the loaded organic phase into the aqueous phase to obtain a lithium-rich solution.

[0051] Example 4

[0052] A method for extracting lithium from salt lakes, the lithium extraction method is carried out using the salt lake lithium extraction device described in Example 1, and includes the following steps:

[0053] Mix TBP and kerosene evenly according to a mass ratio of 70:30 to obtain a blank organic phase. Mix the blank organic phase and a solution containing 1 mol / L ferric chloride and 1 mol / L hydrochloric acid according to a volume ratio of 1:|1, shake and then let it stand for phase separation to obtain an organic phase. Mix the organic phase and water evenly according to a volume ratio of 2:1 to obtain an organic solution;

[0054] Introduce 0.5 mol / L sodium chloride solution into the cathode chamber and the anode chamber respectively, introduce water into the boron removal tank, introduce lithium-containing brine into the feed liquid tank, and introduce the organic solution into the extraction tank;

[0055] Apply a voltage to the anode for 60 minutes for the reaction. The applied voltage is 1.2 V and the current density is 4200 A / m 2 , the stirring rate of the stirring paddle in the extraction tank is 600 rpm. After the reaction is completed, add 1 mol / L hydrochloric acid solution to the boron removal tank until boric acid precipitation forms. Let the extraction tank stand for phase separation to obtain the lithium-containing organic phase. Flow the lithium-containing organic phase out from the lower end of the extraction tank and into the stripping tank to mix and react with 6 mol / L hydrochloric acid solution for 20 minutes. The volume ratio of the lithium-containing organic phase to hydrochloric acid is 20:1. Strip the lithium in the loaded organic phase into the aqueous phase to obtain a lithium-rich solution.

[0056] Comparative Example 1

[0057] A method for extracting lithium from salt lakes, including the following steps:

[0058] Preparation of organic phase: Mix TBP and kerosene evenly according to the mass ratio of 70:30 to obtain a blank organic phase. Mix the blank organic phase and a solution containing 1 mol / L ferric chloride and 1 mol / L hydrochloric acid according to the volume ratio of 1:1. After shaking, let it stand for phase separation to obtain an organic phase. Mix the organic phase and water evenly according to the volume ratio of 2:1 to obtain an organic solution;

[0059] Perform countercurrent extraction on the organic phase and lithium-containing brine according to the volume ratio of 2:1 to obtain a lithium-containing organic phase and a raffinate aqueous phase. Then, mix the lithium-containing organic phase and a 0.01 mol / L hydrochloric acid washing solution according to the volume ratio of 4:1 for washing. Next, perform countercurrent stripping on the lithium-containing organic phase and a 6 mol / L hydrochloric acid stripping agent according to the volume ratio of 20:1, and separate the phases to obtain a lithium-rich solution.

[0060] Performance test

[0061] The composition of the lithium-containing brine introduced in the examples is: 0.35 g / L Li, 85.65 g / L Na, 107.97 g / L Mg, 10.87 g / L B, 8.45 g / L K, 2.76 g / L Ca, 10.54 g / L SO4 2- , and after extracting lithium using the methods of the examples and comparative examples respectively, use ICP to detect the concentration of lithium ions in the lithium-rich solution, and the lithium recovery rate and lithium purity are as shown in the following table.

[0062] Table 1

[0063]

[0064] As can be seen from Table 1, by using the method of this article, the formation of boric acid precipitate, which affects the extraction of lithium, can be effectively avoided during the process of extracting lithium. In addition, the boron removal reaction is carried out while extracting lithium, and there is no need to pre-treat the brine to remove boron in advance, which simplifies the process and effectively improves the lithium recovery rate and purity.

Claims

1. A method for extracting lithium from salt lakes, characterized in that, The lithium extraction method is carried out using a salt lake lithium extraction device, which includes a feed liquid tank, a cathode chamber, an anode chamber, an extraction tank, and a boron removal tank. The anode chamber, boron removal tank, feed liquid tank, extraction tank, and cathode chamber are separated by exchange membranes in sequence. The extraction tank is connected to a stripping tank. A cathode is provided in the cathode chamber, and an anode is provided in the anode chamber. The cathode and the anode are arranged opposite to each other; The cathode is connected to the negative electrode of a power supply through a wire, and the anode is connected to the positive electrode of the power supply through a wire; the feed liquid tank and the extraction tank are separated by a cation exchange membrane; the boron removal tank and the anode chamber are separated by a cation exchange membrane; the feed liquid tank and the boron removal tank are separated by an anion exchange membrane; the extraction tank and the cathode chamber are separated by an anion exchange membrane; The salt lake lithium extraction method includes the following steps: Sodium chloride solutions are respectively introduced into the cathode chamber and the anode chamber, water is introduced into the boron removal tank, lithium-containing brine is introduced into the feed liquid tank, and an organic solution is introduced into the extraction tank; wherein the organic solution includes a blank organic phase and a mixed solution. The blank organic phase includes an extractant and a diluent, and the mixed solution includes ferric chloride and hydrochloric acid; A voltage is applied to the cathode and the anode for reaction. After the reaction is completed, hydrochloric acid solution is added to the boron removal tank, and the extraction tank is allowed to stand for phase separation to obtain a lithium-containing organic phase. The lithium-containing organic phase enters the stripping tank, and hydrochloric acid solution is added to the stripping tank to strip the lithium in the loaded organic phase into the aqueous phase to obtain a lithium-rich solution.

2. The method for extracting lithium from salt lakes according to claim 1, wherein A stirring paddle is provided in the extraction tank.

3. The method for extracting lithium from salt lakes according to claim 1, wherein, The cathode and the anode are each independently selected from one of an Ag electrode and a Pt electrode.

4. The method for extracting lithium from salt lakes according to claim 1, characterized in that, The concentration of the sodium chloride solution is 0.1 - 1 mol / L.

5. The method for extracting lithium from salt lakes according to claim 1, wherein, The preparation method of the organic solution is: mixing the extractant and the diluent to obtain a blank organic phase, preparing a mixed solution containing 0.5 mol / L ferric chloride and 0.5 mol / L hydrochloric acid, mixing the mixed solution and the blank organic phase evenly, shaking and then allowing to stand for phase separation to obtain an organic phase, and mixing the organic phase and water evenly to obtain an organic solution; The mass ratio of the extractant to the diluent is (50 - 70):(30 - 50); The volume ratio of the mixed solution to the blank organic phase is 1:(0.5 - 2); The mass ratio of the organic phase to water is (1 - 2):

1.

6. The method for extracting lithium from salt lakes according to claim 1, wherein The extractant is tributyl phosphate.

7. The method for extracting lithium from salt lakes according to claim 1, characterized in that, The diluent is kerosene.

8. The method for extracting lithium from salt lakes according to claim 1, wherein The voltage applied to the counter electrode and the anode is 0.8~1.2V, and the current density is 380~420 A / m 2 , and the reaction time is 30~60min.

9. The method for extracting lithium from salt lakes according to claim 2, wherein, During the reaction, the stirring rate of the stirring paddle in the extraction tank is 400 - 600 rpm.

10. The method for extracting lithium from salt lakes according to claim 1, characterized in that, The volume ratio of the hydrochloric acid solution added to the stripping tank to the lithium-containing organic phase is (20 - 40):

1.

11. The method for extracting lithium from salt lakes according to claim 1, wherein The concentration of the hydrochloric acid solution added to the stripping tank is 0.2 - 6 mol / L.

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