Salt lake lithium extraction device and method

Abstract

Disclosed in the present invention are a salt lake lithium extraction device and method, belonging to the technical field of salt lake lithium extraction. The salt lake lithium extraction device comprises: a feed liquid tank, a cathode chamber, an anode chamber, an extraction tank and a boron removal tank, wherein the feed liquid tank, the cathode chamber, the anode chamber, the extraction tank and the boron removal tank are sequentially separated by exchange membranes, and the extraction tank is connected to a back extraction tank. In the present disclosure, by means of providing the extraction tank and the boron removal tank, formation of boric acid precipitation which affects lithium extraction is effectively avoided during the lithium extraction process, and moreover, boron removal reaction is carried out while lithium extraction is performed, such that brine does not need to be pretreated for boron removal, thus simplifying the process, and effectively improving the lithium recovery rate and the purity of lithium.

Description

A device and method for extracting lithium from salt lake Technical Field

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

[0002] Lithium and its compounds possess numerous important properties and are widely used in glass, ceramics, batteries, and the nuclear industry. In recent years, the rapid development of electric vehicles has led to the rapid development of lithium-ion batteries, one of the fastest-growing sectors. 80% of global lithium production capacity comes from salt lakes. my country's brine lithium resources are extremely abundant, with the majority of reserves in Qinghai's salt lakes. Qinghai's salt lake brine is a multi-component system with a complex composition. Inorganic salts primarily exist as monovalent or divalent ions. Lithium and magnesium ions have similar radii and chemical properties. A high magnesium-to-lithium ratio is a key characteristic of Qinghai's salt lake resources. Lithium ion concentrations range from 0.3 g / L to 6 g / L, magnesium ion concentrations from 100 to 125 g / L, and magnesium-to-lithium mass ratios from 20 to 100:1. This makes magnesium-lithium separation difficult and is the key to lithium extraction technology from salt lakes.

[0003] Research on lithium extraction from high-Mg / Li salt lakes has been extensive and in-depth, including precipitation, extraction, and ion exchange adsorption. In my country, TBP extraction has been the largest and most in-depth method for lithium extraction. It is the most effective method for extracting lithium from high-Mg / Li brine and is one of the most promising methods for extracting lithium from high-Mg / Li brine in salt lakes. However, the TBP extraction method inevitably uses FeCl₃ as a co-extractant. Because the organic phase contains a co-extractant, the brine must remain weakly acidic, otherwise Fe hydrolysis will occur. The brine entering the extraction process must be acidified. However, lithium and boron are commonly found together in salt lakes in the Qinghai-Tibet region of my country. Boric acid will inevitably precipitate during the acidification process, requiring prior boron removal.

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

[0005] Summary of the Invention

[0006] The purpose of this article is to overcome the shortcomings of the existing technology and provide a salt lake lithium extraction device and method, which effectively avoids the formation of boric acid precipitation affecting lithium extraction during the lithium extraction process. In addition, 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 recovery rate and purity of lithium.

[0007] To achieve the above objectives, the technical solutions adopted in this paper are:

[0008] A lithium extraction device for a salt lake comprises a feed liquid tank, a cathode chamber, an anode chamber, an extraction tank, and a boron removal tank, wherein the feed liquid tank, cathode chamber, anode chamber, extraction tank, and boron removal tank are sequentially separated by exchange membranes, the extraction tank is connected to a stripping tank, a cathode is provided in the cathode chamber, an anode is provided in the anode chamber, and the cathode and the anode are arranged opposite to each other.

[0009] This article sets up 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 the lithium in the aqueous phase to obtain a loaded organic phase and a raffinate. Anions such as borate enter the boron removal tank. During the lithium extraction process, the formation of boric acid precipitation that affects the extraction of lithium is effectively avoided. In addition, the boron removal reaction is carried out while extracting lithium. There is no need to pretreat the brine to remove boron in advance, which simplifies the process and effectively improves the recovery rate and purity of lithium.

[0010] In one embodiment, the cathode is connected to the negative electrode of the power supply via a wire, and the anode is connected to the positive electrode of the power supply via a conductor.

[0011] In one embodiment, a stirring paddle is provided in the extraction tank.

[0012] In one embodiment, the feed liquid tank and the extraction tank are separated by a cation exchange membrane.

[0013] In one embodiment, the boron removal tank is separated from the anode chamber by a cation exchange membrane.

[0014] In one embodiment, the feed liquid tank and the boron removal tank are separated by an anion exchange membrane.

[0015] In one embodiment, the extraction tank is separated from the cathode chamber by an anion exchange membrane.

[0016] In one embodiment, the cathode and the anode are each independently selected from one of an Ag electrode and a Pt electrode.

[0017] This article also provides a method for extracting lithium from a salt lake, which is performed using the above-mentioned salt lake lithium extraction device and includes the following steps:

[0018] Sodium chloride solution is introduced into the cathode chamber and the anode chamber respectively, 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;

[0019] Voltage is applied to the anode and the cathode to react. 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.

[0020] In this paper, the lithium extraction process is carried out in an electrodialysis cell. Under the action of the electric field, the borate ions and cations in the brine enter the boron removal cell and the extraction cell respectively. In the process of lithium extraction, the formation of boric acid precipitation that affects the extraction of lithium is effectively avoided. In addition, the boron removal reaction is carried out while the lithium is extracted. There is no need to pre-treat the brine to remove the boron, which simplifies the process and effectively improves the recovery rate and purity of lithium.

[0021] In one embodiment, the concentration of the sodium chloride solution is 0.1-1 mol / L.

[0022] In one embodiment, the method for preparing the organic solution is as follows: the method for preparing the organic solution is as follows: mixing an extractant and a diluent to obtain a blank organic phase, preparing a mixed solution comprising 0.5 mol / L ferric chloride and 0.5 mol / L hydrochloric acid, uniformly mixing the mixed solution with the blank organic phase, shaking and then allowing the phases to separate, and uniformly mixing the organic phase with water to obtain an organic solution;

[0023] The mass ratio of the extractant to the diluent is (50-70): (30-50);

[0024] The volume ratio of the mixed solution to the blank organic phase is 1:(0.5-2);

[0025] The mass ratio of the organic phase to water is (1-2):1.

[0026] In one embodiment, the extractant is tributyl phosphate.

[0027] In one embodiment, the diluent is kerosene.

[0028] In one embodiment, the voltage applied to the anode and the cathode is 0.8-1.2V, and the current density is 380-420A / m 2 , the reaction time is 30 to 60 minutes.

[0029] In one embodiment, during the reaction, the stirring speed of the stirring paddle in the extraction tank is 400-600 rpm.

[0030] In one embodiment, the volume ratio of the hydrochloric acid solution to the lithium-containing organic phase is (20-40):1.

[0031] In one embodiment, the concentration of the hydrochloric acid solution is 0.2-6 mol / L.

[0032] 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 of the lithium-containing brine enter the extraction tank, and the organic extraction system extracts the lithium in the aqueous phase to obtain a loaded organic phase and a residual liquid, while anions such as borate enter the boron removal tank. During the lithium extraction process, the formation of boric acid precipitation that affects the extraction of lithium is effectively avoided. In addition, the boron removal reaction is carried out while extracting lithium, and there is no need to pre-treat the brine for boron removal in advance, which simplifies the process and effectively improves the recovery rate and purity of lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of the salt lake lithium extraction device in this article.

[0034] 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. DETAILED DESCRIPTION

[0035] In order to better illustrate the purpose, technical solutions and advantages of this article, this article will be further described below in conjunction with specific embodiments and comparative examples. The purpose is to understand the content of this article in detail, rather than to limit this article.

[0036] Unless otherwise specified, the components and raw materials used in the examples and comparative examples herein are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0037] Example 1

[0038] As shown in Figure 1, this embodiment 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, the cathode chamber 2, the anode chamber 3, the extraction tank 4, and the boron removal tank 5 are separated in sequence by exchange membranes. The extraction tank 4 is connected to a stripping tank 6. A cathode 10 is provided in the cathode chamber 2, and an anode 9 is provided in the anode chamber 3. The cathode 10 is arranged opposite to the anode 9.

[0039] In one embodiment, the cathode 10 is connected to the negative electrode 12 of the power supply via a wire, and the anode 9 is connected to the positive electrode 11 of the power supply via a conductor.

[0040] In one embodiment, a stirring paddle is provided in the extraction tank 4 .

[0041] More specifically, the feed liquid tank 1 is separated from the extraction tank 5 by a cation exchange membrane 7, the boron removal tank 4 is separated from the anode chamber 3 by a cation exchange membrane 7, the feed liquid tank 1 is separated from the boron removal tank 4 by an anion exchange membrane 8, and the extraction tank 4 is separated from the cathode chamber 2 by an anion exchange membrane 8.

[0042] Example 2

[0043] A method for extracting lithium from a salt lake, wherein the method is performed using the salt lake lithium extraction device described in Example 1, and comprises the following steps:

[0044] TBP (tributyl phosphate) and kerosene were mixed in a mass ratio of 60:40 to obtain a blank organic phase, the blank organic phase was mixed with a solution containing 0.5 mol / L ferric chloride and 0.5 mol / L hydrochloric acid in a volume ratio of 1:1, and the mixture was shaken and allowed to stand for phase separation to obtain an organic phase, and the organic phase was mixed with water in a volume ratio of 2:1 to obtain an organic solution;

[0045] 0.5 mol / L sodium chloride solution was introduced into the cathode chamber and the anode chamber respectively, water was introduced into the boron removal tank, lithium-containing brine was introduced into the feed liquid tank, and an organic solution was introduced into the extraction tank;

[0046] The voltage was applied to the anode and the anode for 45 minutes, the applied voltage was 1V, and the current density was 400A / m 2 The stirring rate of the stirring paddle in the extraction tank is 500 rpm. After the reaction is completed, 0.6 mol / L hydrochloric acid solution is added to the boron removal tank until boric acid precipitate is formed. The extraction tank is allowed to stand for phase separation to obtain a lithium-containing organic phase. The lithium-containing organic phase is discharged from the lower end of the extraction tank into the stripping tank and mixed with 3 mol / L hydrochloric acid solution for reaction for 30 minutes. The volume ratio of the lithium-containing organic phase to the hydrochloric acid is 20:1. The lithium in the loaded organic phase is stripped to the aqueous phase to obtain a lithium-rich solution.

[0047] Example 3

[0048] A method for extracting lithium from a salt lake, the method being performed using the salt lake lithium extraction device described in Example 1, comprising the following steps:

[0049] TBP and kerosene were mixed in a mass ratio of 50:50 to obtain a blank organic phase, the blank organic phase was mixed with a solution containing 0.1 mol / L ferric chloride and 0.1 mol / L hydrochloric acid in a volume ratio of 1:1, and the mixture was shaken and allowed to stand for phase separation to obtain an organic phase, and the organic phase was mixed with water in a volume ratio of 1:1 to obtain an organic solution;

[0050] 0.5 mol / L sodium chloride solution was introduced into the cathode chamber and the anode chamber respectively, water was introduced into the boron removal tank, lithium-containing brine was introduced into the feed liquid tank, and an organic solution was introduced into the extraction tank;

[0051] A voltage was applied to the anode and the cathode for 30 min, the applied voltage was 0.8 V, and the current density was 380 A / m 2The stirring rate of the stirring paddle in the extraction tank is 400 rpm. After the reaction is completed, 0.2 mol / L hydrochloric acid solution is added to the boron removal tank until boric acid precipitate is formed. The extraction tank is allowed to stand for phase separation to obtain a lithium-containing organic phase. The lithium-containing organic phase is discharged from the lower end of the extraction tank into the stripping tank and mixed with 1 mol / L hydrochloric acid solution for reaction for 40 minutes. The volume ratio of the lithium-containing organic phase to the hydrochloric acid is 20:1. The lithium in the loaded organic phase is stripped to the aqueous phase to obtain a lithium-rich solution.

[0052] Example 4

[0053] A method for extracting lithium from a salt lake, wherein the method is performed using the salt lake lithium extraction device described in Example 1, and comprises the following steps:

[0054] TBP and kerosene were mixed uniformly in a mass ratio of 70:30 to obtain a blank organic phase, the blank organic phase was mixed with a solution containing 1 mol / L ferric chloride and 1 mol / L hydrochloric acid in a volume ratio of 1:1, and the mixture was shaken and allowed to stand for phase separation to obtain an organic phase, and the organic phase was mixed uniformly with water in a volume ratio of 2:1 to obtain an organic solution;

[0055] 0.5 mol / L sodium chloride solution was introduced into the cathode chamber and the anode chamber respectively, water was introduced into the boron removal tank, lithium-containing brine was introduced into the feed liquid tank, and an organic solution was introduced into the extraction tank;

[0056] The voltage was applied to the anode and the anode for 60 minutes, the applied voltage was 1.2V, and the current density was 4200A / m 2 The stirring rate of the stirring paddle in the extraction tank is 600 rpm. After the reaction is completed, 1 mol / L hydrochloric acid solution is added to the boron removal tank until boric acid precipitate is formed. The extraction tank is allowed to stand for phase separation to obtain a lithium-containing organic phase. The lithium-containing organic phase is discharged from the lower end of the extraction tank into the stripping tank and mixed with 6 mol / L hydrochloric acid solution for reaction for 20 minutes. The volume ratio of the lithium-containing organic phase to the hydrochloric acid is 20:1. The lithium in the loaded organic phase is stripped to the aqueous phase to obtain a lithium-rich solution.

[0057] Comparative Example 1

[0058] A method for extracting lithium from a salt lake comprises the following steps:

[0059] Preparation of the organic phase: TBP and kerosene were mixed in a mass ratio of 70:30 to obtain a blank organic phase. The blank organic phase was mixed with a solution containing 1 mol / L ferric chloride and 1 mol / L hydrochloric acid in a volume ratio of 1:1. The mixture was shaken and allowed to stand for phase separation to obtain an organic phase. The organic phase was then mixed with water in a volume ratio of 2:1 to obtain an organic solution.

[0060] The organic phase and the lithium-containing brine are countercurrently extracted in a volume ratio of 2:1 to obtain a lithium-containing organic phase and a residual water phase, and then the lithium-containing organic phase is mixed with a 0.01 mol / L hydrochloric acid washing solution in a volume ratio of 4:1 for washing, and then the lithium-containing organic phase is countercurrently stripped with a 6 mol / L hydrochloric acid stripping agent in a volume ratio of 20:1, and the phases are separated to obtain a lithium-rich solution.

[0061] Performance Testing

[0062] The components of lithium-containing brine introduced into the embodiment are: 0.35g / L Li, 85.65g / L Na, 107.97g / LMg, 10.87g / LB, 8.45g / L K, 2.76g / L Ca, 10.54g / L SO4 2- After lithium was extracted using the methods of the embodiment and the comparative example, the concentration of lithium ions in the lithium-rich solution was detected using ICP, and the lithium recovery rate and lithium purity were as shown in the following table.

[0063] Table 1

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

Claims

1. A device for extracting lithium from a salt lake, characterized in that: The invention comprises a feed liquid tank, a cathode chamber, an anode chamber, an extraction tank and a boron removal tank, wherein the feed liquid tank, the cathode chamber, the anode chamber, the extraction tank and the boron removal tank are separated in sequence by exchange membranes, the extraction tank is connected to a stripping tank, a cathode is arranged in the cathode chamber, an anode is arranged in the anode chamber, and the cathode and the anode are arranged opposite to each other.

2. The salt lake lithium extraction device according to claim 1, characterized in that: The cathode is connected to the negative electrode of the power source through a wire, and the anode is connected to the positive electrode of the power source through conduction.

3. The salt lake lithium extraction device according to claim 1, characterized in that: A stirring paddle is arranged in the extraction tank.

4. The salt lake lithium extraction device according to claim 1, characterized in that: The feed tank and the extraction tank are separated by a cation exchange membrane; and / or The boron removal tank is separated from the anode chamber by a cation exchange membrane.

5. The salt lake lithium extraction device according to claim 1, characterized in that: The feed liquid tank and the boron removal tank are separated by an anion exchange membrane; and / or The extraction tank is separated from the cathode chamber by an anion exchange membrane.

6. The salt lake lithium extraction device according to claim 1, characterized in that: The cathode and the anode are independently selected from one of an Ag electrode and a Pt electrode.

7. A method for extracting lithium from a salt lake, characterized in that: The lithium extraction method is carried out using the salt lake lithium extraction device according to any one of claims 1 to 6, comprising the following steps: Sodium chloride solution is introduced into the cathode chamber and the anode chamber respectively, 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; Voltage is applied to the anode and the cathode to react. 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 a 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.

8. The method for extracting lithium from salt lake according to claim 7, characterized in that: The concentration of the sodium chloride solution is 0.1-1 mol / L.

9. The method for extracting lithium from salt lake according to claim 7, characterized in that: The method for preparing the organic solution is as follows: mixing an extractant and a diluent to obtain a blank organic phase, preparing a mixed solution comprising 0.5 mol / L ferric chloride and 0.5 mol / L hydrochloric acid, uniformly mixing the mixed solution with the blank organic phase, shaking and standing for phase separation, and uniformly mixing the organic phase with water 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.

10. The method for extracting lithium from salt lake according to claim 9, characterized in that: The extractant is tributyl phosphate.

11. The method for extracting lithium from salt lake according to claim 9, characterized in that: The diluent is kerosene.

12. The method for extracting lithium from salt lake according to claim 7, characterized in that: The voltage applied to the anode and the anode is 0.8-1.2V, and the current density is 380-420A / m 2 , the reaction time is 30 to 60 minutes.

13. The method for extracting lithium from salt lake according to claim 7, characterized in that: During the reaction, the stirring speed of the stirring paddle in the extraction tank is 400-600 rpm.

14. The method for extracting lithium from salt lake according to claim 7, characterized in that: The volume ratio of the hydrochloric acid solution to the lithium-containing organic phase is (20-40):

1.

15. The method for extracting lithium from salt lake according to claim 7, characterized in that: The concentration of the hydrochloric acid solution is 0.2-6 mol / L.

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