Method for extracting lithium from gas field produced water based on electrochemical intercalation method

Abstract

The invention discloses a method for extracting lithium from gas field produced water based on an electrochemical intercalation method. The method comprises the following steps: (1) pretreatment; (2) the pretreated gas field produced water serves as electrolyte to enter an electrolytic bath for lithium adsorption; (3) replacing the electrolyte with an eluent, exchanging the positive electrode and the negative electrode of a power supply of the electrolytic cell, and desorbing lithium under the action of a reverse electric field; (4) collecting the desorbed lithium ion solution, concentrating, adding a sodium carbonate solution or directly adding sodium carbonate, stirring at 60-65 DEG C, filtering, washing with water, and drying to obtain lithium carbonate; and (5) taking the liquid obtained by filtering in the step (4) as electrolyte, and repeating the steps (2)-(4) for 0-4 times. By utilizing an electrochemical intercalation method, the lithium ions in the gas field produced water can be efficiently and selectively separated, the lithium ion recovery rate is high, and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium resource recovery, and in particular relates to a method for extracting lithium from gas field produced water based on an electrochemical intercalation method. Background Art

[0002] With the rapid development of the electric vehicle and energy storage industries, demand for lithium resources has increased dramatically. Traditional lithium resources primarily come from salt lake brines and spodumene mines, but the development of these resources faces challenges such as resource depletion and environmental pollution. Gas field produced water, as a potential lithium resource, has garnered increasing attention in recent years. While produced water contains a certain concentration of lithium ions, the concentration is typically low and contains a large amount of impurity ions, making it difficult to directly utilize.

[0003] Currently, the main methods for extracting lithium from gas field produced water include adsorption, membrane separation, and solvent extraction. However, these methods generally suffer from complex processes, high costs, and low efficiency, making them difficult to implement on a large scale in industrial applications. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a method for extracting lithium from gas field produced water based on the electrochemical intercalation method, which can efficiently and selectively separate lithium ions in gas field produced water with a high lithium ion recovery rate.

[0005] A method for extracting lithium from gas field produced water based on electrochemical intercalation method, comprising the following steps: (1) Pretreatment: The produced water from the gas field is treated by at least one of filtration, softening or adsorption; (2) The pre-treated gas field produced water enters the electrolytic cell as the electrolyte, and the voltage is 0.5-5V and the current is 1-50mA / cm 2 The electrolysis is carried out for 30-120 minutes under the action of an electric field to adsorb lithium; wherein the anode of the electrolytic cell is a lithium ion intercalation material; the cathode is made of stainless steel, nickel or copper; and a diaphragm is further provided between the anode and cathode of the electrolytic cell; (3) Replace the electrolyte with eluent, then swap the positive and negative poles of the electrolytic cell, and operate at a voltage of 0.5-5V and a current of 1-30mA / cm 2 Treat under the action of reverse electric field for 20-60 minutes to desorb lithium; (4) collecting the desorbed lithium ion solution, concentrating it, then adding a sodium carbonate solution or directly adding sodium carbonate, stirring at 60-65°C, filtering, and drying to obtain lithium carbonate; (5) Use the liquid filtered in step (4) as the electrolyte and repeat steps (2) to (4) 0-4 times.

[0006] Preferably, the lithium ion intercalation material is one of lithium iron phosphate, lithium titanate, and lithium manganate.

[0007] Preferably, the diaphragm is a cation exchange membrane, a polypropylene microporous membrane or a polyethylene microporous membrane.

[0008] Preferably, the eluent is an acidic solution or an alkaline solution.

[0009] Preferably, the acidic solution is a dilute sulfuric acid solution or a dilute hydrochloric acid solution with a mass concentration of 3-10 wt%; and the alkaline solution is a 5-8 wt% sodium hydroxide solution.

[0010] Preferably, the filtration in step (1) is microfiltration.

[0011] Preferably, the softening in step (1) is performed by adding Na2CO3 solution to adjust the pH to 10, centrifuging, and taking the supernatant.

[0012] Preferably, the adsorption in step (1) is activated carbon adsorption.

[0013] Preferably, the concentration in step (4) is reverse osmosis or cooling crystallization.

[0014] Preferably, the drying condition is drying at 100-105° C. for 6-7 hours.

[0015] Advantages of the present invention: (1) The present invention utilizes an electrochemical intercalation method to efficiently and selectively separate lithium ions from gas field produced water, with a high lithium ion recovery rate; (2) The electrode material used in the present invention is low-cost and recyclable, which reduces production costs; (3) The process is simple, does not require the addition of chemical reagents, is environmentally friendly, and is easy to achieve large-scale industrial application. DETAILED DESCRIPTION

[0016] The gas field produced water used in the embodiment of the present invention has the following characteristics: lithium ion concentration of 120 mg / L, pH=6.5, and contains impurity ions such as Na⁺, K⁺, Ca²⁺, and Mg²⁺ (total salinity of 8 g / L).

[0017] Example 1 A method for extracting lithium from gas field produced water based on electrochemical intercalation method, comprising the following steps: (1) Pretreatment: The gas field produced water was passed through a 0.45 μm microfiltration membrane to remove suspended solids, and then softened. 0.1 mol / L Na2CO3 solution was added to adjust the pH to 10 to precipitate the Ca 2+ Mg 2+ After centrifugation, the supernatant was collected; (2) The pre-treated gas field produced water enters the electrolytic cell as the electrolyte, and the voltage is 1.2V and the current is 10mA / cm 2 The electrolyte was electrolyzed for 30 minutes under the action of an electric field to adsorb lithium; wherein the anode of the electrolytic cell was lithium manganate, a lithium ion intercalation material; the cathode was nickel; a diaphragm was further provided between the anode and cathode of the electrolytic cell, and the diaphragm was a Nafion 117 cation exchange membrane; (3) Using 5wt% dilute sulfuric acid as the eluent, replace the electrolyte with the eluent, then swap the positive and negative poles of the power supply of the electrolytic cell, and at a voltage of 1.5V and a current of 10mA / cm 2 The solution was treated under the action of a reverse electric field for 20 min to desorb lithium and obtain an eluent rich in lithium ions; (4) Collect the lithium ion-rich eluate and concentrate it to Li + The content is 2000 mg / L, and then 1 mol / L Na2CO3 solution is added thereto, stirred at 60°C, filtered, and dried at 100°C for 7h to obtain lithium carbonate with a purity of 99.2%; Li + The recovery rate was 68%; (5) The liquid obtained by filtering in step (4) is used as the electrolyte, and the above steps (2) to (4) are repeated twice. + The total recovery rate is greater than 95%, and the concentration of lithium ions in the recovered produced water is 5-8 mg / L.

[0018] In this embodiment, the average energy consumption for lithium extraction per ton of water is 15 kWh / kg Li2CO3.

[0019] Example 2 The lithium ion intercalation material is lithium titanate, and the eluent is a sodium hydroxide solution with a concentration of 5 wt%; the rest is the same as in Example 1, and the purity of the lithium carbonate obtained in step (4) is 99.4%; Li + The recovery rate was 72%; step (5) Li + The total recovery rate is 96%; the average energy consumption for lithium extraction per ton of water is 17kWh / kg Li2CO3.

[0020] Example 3 The concentration method in step (4) is cooling crystallization; the rest is the same as in Example 1, and the purity of lithium carbonate obtained in step (4) is 98.5%; Li + The recovery rate was 67%; step (5) Li + The total recovery rate is 94.8%; the average energy consumption for lithium extraction per ton of water is 14 kWh / kg Li2CO3.

[0021] Example 4 A method for extracting lithium from gas field produced water based on electrochemical intercalation method, comprising the following steps: (1) Pretreatment: The gas field produced water was passed through a 0.45 μm microfiltration membrane to remove suspended solids, and then softened. 0.1 mol / L Na2CO3 solution was added to adjust the pH to 10 to precipitate the Ca 2+ Mg 2+ After centrifugation, the supernatant was taken and adsorbed on activated carbon for 30 min; (2) The pre-treated gas field produced water enters the electrolytic cell as the electrolyte, and the voltage is 0.5V and the current is 1mA / cm 2 The electrolyte was electrolyzed for 120 minutes under the action of an electric field to adsorb lithium; wherein the anode of the electrolytic cell was lithium iron phosphate, a lithium ion intercalation material; the cathode was stainless steel; a diaphragm was further provided between the anode and cathode of the electrolytic cell, and the diaphragm was a polypropylene microporous membrane; (3) Using dilute sulfuric acid with a concentration of 10wt% as the eluent, replace the electrolyte with the eluent, and then swap the positive and negative poles of the power supply of the electrolytic cell. 2 The solution was treated under the action of a reverse electric field for 40 min to desorb lithium and obtain an eluent rich in lithium ions; (4) Collect the lithium ion-rich eluate and concentrate it to Li + The content is 2000 mg / L, and then 1 mol / L Na2CO3 solution is added thereto, stirred at 65℃, filtered, and dried at 105℃ for 6h to obtain lithium carbonate with a purity of 98.9%; Li + The recovery rate was 75%; In this embodiment, the average energy consumption for lithium extraction per ton of water is 10 kWh / kg Li2CO3.

[0022] Example 5 A method for extracting lithium from gas field produced water based on electrochemical intercalation method, comprising the following steps: (1) Pretreatment: The gas field produced water was passed through a 0.45 μm microfiltration membrane to remove suspended solids, and then softened. 0.1 mol / L Na2CO3 solution was added to adjust the pH to 10 to precipitate the Ca 2+ Mg 2+ After centrifugation, the supernatant was collected; (2) The pre-treated gas field produced water enters the electrolytic cell as the electrolyte, and the voltage is 5V and the current is 50mA / cm 2 The electrolyte is electrolyzed for 30 minutes under the action of an electric field to adsorb lithium; wherein the anode of the electrolytic cell is lithium manganese oxide, a lithium ion intercalation material; the cathode is copper; a diaphragm is further provided between the anode and cathode of the electrolytic cell, and the diaphragm is a polyethylene microporous membrane; (3) Using 3 wt% dilute hydrochloric acid as the eluent, replace the electrolyte with the eluent, then swap the positive and negative poles of the power supply of the electrolytic cell, and at a voltage of 5 V and a current of 1 mA / cm 2 The solution was treated under the action of a reverse electric field for 60 min to desorb lithium and obtain an eluent rich in lithium ions; (4) Collect the lithium ion-rich eluate and concentrate it to Li + The content is 2000 mg / L, and then 1 mol / L Na2CO3 solution is added thereto, stirred at 60℃, filtered, and dried at 105℃ for 7h to obtain lithium carbonate with a purity of 99.9%; Li + The recovery rate was 72%; (5) The liquid obtained by filtering in step (4) is used as the electrolyte, and the above steps (2) to (4) are repeated 4 times. + The total recovery rate was 99.5%; In this embodiment, the average energy consumption for lithium extraction per ton of water is 20 kWh / kg Li2CO3.

Claims

1. A method for extracting lithium from gas field produced water based on electrochemical intercalation, characterized by: The following steps are involved: (1) Pretreatment: The produced water from the gas field is treated by at least one of filtration, softening or adsorption; (2) The pre-treated gas field produced water enters the electrolytic cell as the electrolyte, and the voltage is 0.5-5V and the current is 1-50mA / cm 2 The electrolysis is carried out for 30-120 minutes under the action of an electric field to adsorb lithium; wherein the anode of the electrolytic cell is a lithium ion intercalation material; the cathode is made of stainless steel, nickel or copper; and a diaphragm is further provided between the anode and cathode of the electrolytic cell; (3) Replace the electrolyte with eluent, then swap the positive and negative poles of the electrolytic cell, and operate at a voltage of 0.5-5V and a current of 1-30mA / cm 2 Treat under the action of reverse electric field for 20-60 minutes to desorb lithium; (4) Collect the desorbed lithium ion solution, concentrate it, then add sodium carbonate solution or directly add sodium carbonate, stir at 60-65°C, filter, wash with water and then dry to obtain lithium carbonate; (5) Use the liquid filtered in step (4) as the electrolyte and repeat steps (2) to (4) 0-4 times.

2. The method for extracting lithium from gas field produced water based on electrochemical intercalation according to claim 1, characterized in that: The lithium ion intercalation material is one of lithium iron phosphate, lithium titanate, and lithium manganate.

3. The method for extracting lithium from gas field produced water based on electrochemical intercalation according to claim 1, characterized in that: The diaphragm is a cation exchange membrane, a polypropylene microporous membrane or a polyethylene microporous membrane.

4. The method for extracting lithium from gas field produced water based on electrochemical intercalation according to claim 1, characterized in that: The eluent is an acidic solution or an alkaline solution.

5. The method for extracting lithium from gas field produced water based on electrochemical intercalation according to claim 4, characterized in that: The acidic solution is a dilute sulfuric acid solution or a dilute hydrochloric acid solution with a mass concentration of 3-10wt%; the alkaline solution is a 5-8wt% sodium hydroxide solution.

6. The method for extracting lithium from gas field produced water based on electrochemical intercalation according to claim 1, characterized in that: The filtration in step (1) is microfiltration.

7. The method for extracting lithium from gas field produced water based on electrochemical intercalation according to claim 1, characterized in that: The softening in step (1) is to add Na2CO3 solution to adjust the pH to 10, centrifuge, and take the supernatant.

8. The method for extracting lithium from gas field produced water based on electrochemical intercalation according to claim 1, characterized in that: The adsorption in step (1) is activated carbon adsorption.

9. The method for extracting lithium from gas field produced water based on electrochemical intercalation according to claim 1, characterized in that: The concentration in step (4) is reverse osmosis or cooling crystallization.

10. The method for extracting lithium from gas field produced water based on electrochemical intercalation according to claim 1, characterized in that: The drying condition is drying at 100-105°C for 6-7h.