Electrochemical lithium ion sieve lithium extraction device and process

Abstract

This invention relates to an electrochemical lithium-ion sieve-based lithium extraction apparatus and method, belonging to the field of electrochemical lithium extraction. The apparatus and method mainly comprise: a first end plate, a second end plate, and several electrolytic cell units assembled together. The electrolytic cell units are located between the two end plates. After brine and supporting electrolyte enter the electrolytic cell unit, due to the crisscrossing of the flow guide holes on the cathode and anode guide plates, the brine and supporting electrolyte flow to the cathode and anode respectively. Under the action of an electric field, lithium ions in the brine are absorbed by the lithium-deficient ion sieve on the cathode, transforming into lithium-rich ion sieves. Lithium ions from the lithium-rich ion sieve on the anode are released into the supporting electrolyte, transforming into lithium-deficient ion sieves. After draining the brine and supporting electrolyte, the apparatus is rinsed with pure water, and the brine and supporting electrolyte are exchanged, with the current direction changed, repeating the cycle to achieve selective extraction of lithium from the brine.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical lithium extraction, and relates to an apparatus and process for extracting lithium from brine. Background Technology

[0002] Lithium resources, as an important new energy material and strategic reserve resource, are widely used in aviation, medicine, chemical industry, national defense, and new energy fields. Lithium is known as a "key element driving the world forward," and its development and utilization have attracted widespread attention. In nature, lithium resources mainly exist in two forms: ore and brine. In China, most lithium resources exist in the form of salt lake brine, accounting for more than 80% of all lithium resources. Extracting lithium from salt lakes is more in line with the characteristics of China's resource endowment and has become a major trend in the development of China's lithium resources.

[0003] Electrochemical ion sieving for lithium extraction is a lithium-ion sieving method based on electrochemical redox reactions and high selectivity for lithium ions. It achieves the adsorption and desorption of lithium ions, offering advantages such as high efficiency and energy saving. However, current research on electrochemical lithium-ion sieving devices and methods is limited, and existing devices are complex in structure and require periodic electrode movement during the extraction process, resulting in low extraction efficiency.

[0004] To address the shortcomings of current electrochemical lithium extraction processes and achieve efficient separation and extraction of lithium resources, it is necessary to develop a lithium extraction device and process that is simple in structure and easy to operate. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a simple and easy-to-operate electrochemical lithium-ion screening lithium extraction device and process to achieve efficient extraction of lithium resources from brine.

[0006] The technical solution adopted by this invention to solve the technical problem is:

[0007] An electrochemical lithium-ion sieve lithium extraction device and process are disclosed. The device is composed of a first end plate, a second end plate, and several electrolytic cell units spliced ​​together. The electrolytic cell units are located between the two end plates. Each electrolytic cell unit is composed of a first anode guide plate, an anode, a second anode guide plate, an anion exchange membrane, a first cathode guide plate, a cathode, and a second cathode guide plate, which are overlapped and pressure is applied.

[0008] The first end plate and the second end plate have the same frame size and shape, and the lower part of the first end plate has a first liquid inlet and a second liquid inlet. Preferably, the first liquid inlet and the second liquid inlet are located on the same horizontal line. The first liquid outlet and the second liquid outlet are located on the same horizontal line. Preferably, the first liquid inlet, the second liquid inlet, the first liquid outlet, and the second liquid outlet are the same size and shape.

[0009] The anode, anion exchange membrane, and cathode each have two liquid passage holes at the top and bottom. The liquid passage holes are identical in position, size, and shape. The lower liquid passage hole is identical in position, size, and shape to the first and second liquid inlets of the first end plate. The upper liquid passage hole is identical in position, size, and shape to the first and second liquid outlets of the second end plate.

[0010] The lithium-rich ion sieve material mentioned above uses lithium iron phosphate, lithium manganese oxide, lithium titanate, and LiA. x B y C (1-x-y) O z One or more mixtures of ternary oxides, wherein A, B, and C are one of nickel, cobalt, manganese, iron, and aluminum, respectively, and x and y are both between 0 and 1.

[0011] The cathode is a current collector coated with a lithium-ion screen material in a lithium-deficient state, wherein the lithium-ion screen material is one or a mixture of iron phosphate and manganese dioxide.

[0012] The anode guide plate consists of two liquid passage holes, two guide holes, and a guide mesh. The two liquid passage holes are placed diagonally and are not connected to the guide mesh. The two guide holes are placed diagonally and are connected to the guide mesh by multiple staggered guide strips. The guide mesh is composed of multiple staggered guide strips. The position, size, and shape of the two liquid passage holes and the two guide holes correspond to the liquid inlets on the first end plate and the second end plate.

[0013] The diversion method involves connecting the anode and cathode guide plates to the guide mesh via guide holes, while the liquid passage holes on the anode and cathode guide plates are not connected to the guide mesh, thereby enabling the diversion of electrolyte and brine.

[0014] The current collector is one of stainless steel mesh, stainless steel plate, titanium mesh, titanium plate, graphite plate, and graphite paper. The current collector has tabs for connecting to a power source.

[0015] The supporting electrolyte is a magnesium-free electrolyte solution, such as one or a mixture of sodium chloride, sodium sulfate, potassium chloride, potassium sulfate, sodium nitrate, and potassium nitrate solutions.

[0016] The brine is any solution containing lithium ions, such as salt lake brine, evaporated old brine, lithium battery recycled liquid, or a mixture of several of these.

[0017] An electrochemical lithium-ion sieve lithium extraction device and process are disclosed. The process involves the following steps: Support electrolyte enters the device through a first inlet on a first end plate, then passes through the guide holes of a first anode guide plate. Since the guide holes are connected to a guide mesh, the support electrolyte is split into two parts. One part flows along the guide strips connecting the guide holes and the guide mesh to the guide mesh, where it is evenly dispersed on the reverse side of the anode and then flows towards the diagonally opposite guide holes. The other part passes through the guide holes of the first anode guide plate, then through the liquid passage holes on the anode, and enters the guide holes of the second anode guide mesh. This part flows along the guide strips connecting the guide holes and the guide mesh to the guide mesh, where it is evenly dispersed on the front side of the anode and then flows towards the diagonally opposite guide holes. After the two parts of the support electrolyte converge here, they sequentially pass through the liquid passage holes on the anion exchange membrane, the cathode guide plate, the cathode itself, and the cathode guide plate, exiting from the second end plate. The first outlet flows into the electrolyte storage tank. Brine enters the device through the second inlet on the first end plate. Since the liquid passage holes on the anode guide plate are not connected to the guide net, the brine passes through the liquid passage holes on the anode guide plate, the anode itself, the anode guide plate, and the anion exchange membrane, entering the guide holes on the cathode guide net. Because the guide holes on the cathode guide plate are connected to the guide net, the brine splits into two parts here. One part of the brine flows along the guide holes and connects to the guide net. The brine flows through the flow guide strip and the flow guide net. The brine is evenly dispersed on the front side of the cathode through the flow guide net, and then flows to the diagonal flow guide hole. Another part of the brine passes through the liquid passage hole on the cathode and enters the flow guide hole of the second cathode flow guide plate. This part of the supporting electrolyte flows along the flow guide strip connected to the flow guide net and the flow guide hole. It is evenly dispersed on the back side of the cathode through the flow guide net, and then flows to the diagonal flow guide hole. The two parts of brine converge here and flow into the brine tank from the second liquid outlet on the second end plate. In this cyclic process, the air between the first anode guide plate, the anode, the second anode guide plate, and the anion exchange membrane is squeezed out by the supporting electrolyte, and the air between the anion exchange membrane, the first cathode guide plate, the cathode, and the second cathode guide plate is squeezed out by the brine. Then, the power is turned on, and the lithium ions in the brine are adsorbed by the lithium-deficient lithium ion sieve on the cathode and converted into lithium-rich lithium ion sieves. Meanwhile, the lithium ions on the lithium-rich lithium ion sieves on the anode are released from the anode into the supporting electrolyte and converted into lithium-deficient lithium ion sieves. After a certain period of time, the power is turned off, and the brine and supporting electrolyte in the device are drained. Water is then introduced through the first and second inlets on the first end plate to wash the inside of the device. After washing, brine is introduced through the first inlet on the first end plate, and supporting electrolyte is introduced through the second inlet. Then, the power direction is changed, and the lithium-deficient lithium ion sieves adsorb lithium ions in the brine, while the lithium ions on the lithium-rich lithium ion sieves are released into the supporting electrolyte.By changing the position of the brine and the supporting electrolyte, as well as the direction of the current, lithium ions can be enriched from the brine.

[0018] The present invention has the following advantages:

[0019] 1. This invention, by placing anode guide plates on both sides of the anode and cathode guide plates on both sides of the cathode, and applying pressure during placement, can effectively prevent lithium-rich lithium-ion sieve material on the anode and lithium-deficient lithium-ion sieve material on the cathode from falling off the current collector, thereby improving the service life of the anode and cathode.

[0020] 2. This invention uses anode and cathode guide plates to guide and distribute water on the anode and cathode respectively. The structure is simple, which helps to reduce the pipeline layout and facilitates large-scale production. At the same time, it supports the electrolyte and brine to fully contact the anode and cathode, which helps to improve the lithium extraction efficiency.

[0021] 3. The lithium ion sieve of the present invention has high selectivity for lithium ions, large adsorption capacity, and high stability, and can effectively extract lithium from brine.

[0022] 4. The device designed in this invention places an anode guide plate between the anode and the anion exchange membrane, and a cathode guide plate between the anion exchange membrane and the cathode. The anode and cathode are separated only by the anode guide plate, the anion exchange membrane and the cathode guide plate. The small distance between the anode and the cathode is beneficial to reduce solution resistance and reduce operating energy consumption. Attached Figure Description

[0023] Figure 1 This is a flowchart of the apparatus of the present invention. Detailed Implementation

[0024] The present invention will be further described below with reference to embodiments.

[0025] Example 1

[0026] The brine used in this embodiment is a sulfate-type brine, containing sodium, calcium, lithium, boron, and sulfate ions at concentrations of 80.0 g / L, 0.04 g / L, 1.0 g / L, 0.1 g / L, and 167.5 g / L, respectively. It is then fed into an electrochemical lithium extraction device equipped with a lithium-rich titanium ion sieve / a lithium-deficient titanium ion sieve for electrochemical adsorption. The parameters for the electrochemical adsorption process are: current density 15 A / m³. 2 After 400 minutes of cyclic adsorption, the electroadsorption process ends, yielding a lithium-rich solution. The device is then rinsed with water, followed by lithium concentration using a membrane concentration system at an operating pressure of 3.0–3.5 MPa and a recovery rate of 50%. The membrane permeate is used as the rinsing water for the next batch of the electrochemical lithium extraction unit, while the membrane concentrate is returned to the feed water system for the electrochemical lithium adsorption process.

[0027] Example 2

[0028] The brine used in this embodiment is a carbonate-type salt lake brine, containing sodium ions, magnesium ions, lithium ions, chloride ions, carbonate ions, and bicarbonate ions at concentrations of 40.0 g / L, 0.2 g / L, 0.8 g / L, 52 g / L, 2 g / L, and 1.5 g / L, respectively. It is then fed into an electrochemical lithium extraction device equipped with a lithium-rich titanium ion sieve / a lithium-deficient titanium ion sieve for electrochemical adsorption. The parameters for the electrochemical adsorption process are: current density 16 A / m³. 2 After 400 minutes of cyclic adsorption, the electroadsorption process ends, yielding a lithium-rich solution. The device is then rinsed with water, followed by lithium concentration using a membrane concentration system at an operating pressure of 7.5–8.0 MPa and a recovery rate of 80%. The membrane permeate is used as the rinsing water for the next batch of the electrochemical lithium extraction unit, while the membrane concentrate is returned to the feed water system for the electrochemical lithium adsorption process.

[0029] Comparative Example 1

[0030] The difference from Example 1 is that the device is not powered on, and a desorption solution with a pH of 1 is used for desorption. The desorption conditions are a flow rate of 180 BV / h and a cycle of 30 min.

[0031] Experimental data:

[0032] The ion content in the lithium-rich solutions and / or desorption solutions obtained in the above embodiments and comparative examples is shown in the table below:

[0033]

[0034] As can be seen from the table above, the sodium / lithium ratio of the desorption solution obtained in Example 1 is 0.494, while that in Comparative Example 1 is 1.011. The use of electrochemical adsorption for lithium extraction inhibits sodium migration, thus reducing the sodium / lithium ratio in the resulting lithium-rich solution. Furthermore, the process is applicable to a wide range of brine systems and produces a high-quality lithium-rich solution.

Claims

1. An electrochemical lithium-ion sieve lithium extraction device: characterized in that, The device is assembled by pressure from a first end plate, a second end plate, and several electrolytic cell units, with the several electrolytic cell units located between the two end plates.

2. The electrochemical lithium-ion sieve lithium extraction device according to claim 1: characterized in that, The first end plate and the second end plate are the same size and shape. The lower part of the first end plate has a first liquid inlet and a second liquid inlet. The upper part of the first end plate has a first liquid outlet and a second liquid outlet. Preferably, the first liquid inlet and the second liquid inlet are located on the same horizontal line. The first liquid outlet and the second liquid outlet are located on the same horizontal line. More preferably, the first liquid inlet, the second liquid inlet, the first liquid outlet, and the second liquid outlet are the same size and shape.

3. The electrochemical lithium-ion sieve lithium extraction device according to claim 1: characterized in that, The electrolytic cell unit consists of a first anode guide plate, an anode, a second anode guide plate, an anion exchange membrane, a first cathode guide plate, a cathode, and a second cathode guide plate, stacked and pressurized. The arrangement of the anode and cathode guide plates allows for the separate flow of supporting electrolyte and brine at the anode and cathode, respectively. An anion exchange membrane must be placed between the electrolytic cell units.

4. An electrochemical lithium-ion sieve lithium extraction device according to claim 3: characterized in that the anode, anion exchange membrane and cathode each have two liquid passage holes at the top and bottom, the liquid passage holes have the same position, size and shape, the position, size and shape of the lower liquid passage hole are the same as the first liquid inlet and the second liquid inlet of the first end plate, and the position, size and shape of the upper liquid passage hole are the same as the first liquid outlet and the second liquid outlet of the second end plate.

5. The electrochemical lithium-ion sieve lithium extraction device according to claim 3: characterized in that, The anode is a current collector coated with a lithium-rich lithium-ion sieve material, wherein the lithium-rich ion sieve material is lithium iron phosphate, lithium manganese oxide, lithium titanate, or LiA. x B y C (1-x-y) O z One or more mixtures of ternary oxides, wherein A, B, and C are one of nickel, cobalt, manganese, iron, and aluminum, respectively, and x and y are both between 0 and 1.

6. The electrochemical lithium-ion sieve lithium extraction device according to claim 3: characterized in that, The cathode is a current collector coated with a lithium-ion screen material in a lithium-deficient state, wherein the lithium-ion screen material is one or a mixture of iron phosphate and manganese dioxide.

7. The electrochemical lithium-ion sieve lithium extraction device according to claim 3: characterized in that, The anode guide plate consists of two liquid passage holes, two guide holes, and a guide mesh. The two liquid passage holes are placed diagonally and are not connected to the guide mesh. The two guide holes are placed diagonally and are connected to the guide mesh by multiple staggered guide spacers. The guide mesh is composed of multiple staggered guide spacers. The position, size, and shape of the two liquid passage holes and the two guide holes correspond to the liquid inlet of the first end plate and the liquid outlet of the second end plate.

8. An electrochemical lithium-ion sieve lithium extraction device according to claim 3: characterized in that, The cathode guide plate is the same size and shape as the anode guide plate, the difference being that when placed on the cathode, the anode guide plate needs to be reversed for use; the diversion method is as follows: since the guide holes on the anode and cathode guide plates are connected to the guide mesh, while the liquid passage holes on the anode and cathode guide plates are not connected to the guide mesh, the liquid passage holes on the anode guide plate and the guide holes on the cathode guide plate are stacked correspondingly, thereby achieving the diversion of electrolyte and brine.

9. An electrochemical lithium-ion sieve lithium extraction apparatus and method: characterized in that, The method involves the following steps: The supporting electrolyte enters the device through the first inlet of the first end plate, then flows through the guide holes of the first anode guide plate. Since the guide holes are connected to the guide mesh, the supporting electrolyte splits into two parts. One part flows along the guide strips connecting the guide holes and the guide mesh to the guide mesh, where it is evenly dispersed on the reverse side of the anode and then flows towards the diagonally opposite guide holes. The other part passes through the guide holes of the first anode guide plate, then through the liquid passage holes on the anode, and enters the guide holes of the second anode guide mesh. This part flows along the guide strips connecting the guide holes and the guide mesh to the guide mesh, where it is evenly dispersed on the front side of the anode and then flows towards the diagonally opposite guide holes. After the two parts of the supporting electrolyte converge here, they sequentially pass through the liquid passage holes on the anion exchange membrane, the cathode guide plate, the cathode, and the cathode guide plate, and finally flow out from the first outlet on the second end plate to the supporting electrolyte. In the electrolyte storage tank, brine enters the device through the second inlet of the first end plate. Since the liquid passage holes on the anode guide plate are not connected to the flow guide mesh, the brine passes through the liquid passage holes on the anode guide plate, the anode itself, the anode guide plate, and the anion exchange membrane, entering the flow guide holes on the cathode flow guide mesh. Because the flow guide holes on the cathode guide plate are connected to the flow guide mesh, the brine splits into two parts here. One part of the brine flows along the flow guide partition connecting the flow guide holes and the flow guide mesh. The brine is evenly dispersed on the front side of the cathode through the flow guide net, and then flows to the diagonal flow guide hole. Another part of the brine passes through the liquid passage hole on the cathode and enters the flow guide hole of the second cathode flow guide plate. This part of the supporting electrolyte flows along the flow guide net and the flow guide spacer connected to the flow guide hole, and is evenly dispersed on the back side of the cathode through the flow guide net, and then flows to the diagonal flow guide hole. The two parts of brine converge here and flow into the brine tank from the second liquid outlet on the second end plate. In this cyclic process, the air between the first anode guide plate, the anode, the second anode guide plate, and the anion exchange membrane is squeezed out by the supporting electrolyte, while the air between the anion exchange membrane, the first cathode guide plate, the cathode, and the second cathode guide plate is squeezed out by the brine. Then, the power is turned on, and the lithium ions in the brine are adsorbed by the lithium-deficient lithium ion sieve on the cathode, transforming into lithium-rich lithium ion sieves. Meanwhile, the lithium ions on the lithium-rich lithium ion sieves on the anode are released from the anode into the supporting electrolyte, transforming into lithium-deficient lithium ion sieves. After a certain period of time, the power is turned off, and the brine and supporting electrolyte in the device are drained. Water is then introduced through the first and second inlets on the first end plate to wash the device, cleaning away any remaining brine and supporting electrolyte. The washing process continues until the conductivity of the wash water drops to 10 μS / cm. After washing, the wash water is collected, and then brine is introduced through the first inlet on the first end plate, and supporting electrolyte is introduced through the second inlet. The power direction is then reversed, and the lithium-deficient lithium ion sieves adsorb lithium ions from the brine, while the lithium ions on the lithium-rich lithium ion sieves are released into the supporting electrolyte.By changing the position of the brine and the supporting electrolyte, as well as the direction of the current, lithium ions can be enriched from the brine.

10. An electrochemical lithium-ion sieve lithium extraction apparatus and method: characterized in that, The lithium extraction efficiency is adjusted based on the lithium ion concentration in the brine by controlling the number of electrolytic cell units, power supply voltage, supporting electrolyte, and brine flow rate. The brine is any solution containing lithium ions, such as salt lake brine, evaporated old brine, or one or a mixture of several lithium battery recovery solutions. After the washing water is collected, it is concentrated using a nanofiltration membrane or a reverse osmosis membrane, depending on the concentration of lithium ions and other ions in the washing water and the volume of washing water. The concentrated solution is then returned to the brine tank to continue the lithium extraction process.

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