Electric de-intercalation lithium extraction system for improving robustness based on parameter decoupling and application of electric de-intercalation lithium extraction system

Abstract

The invention provides an electric de-intercalation lithium extraction system, and belongs to the technical field of salt lake lithium extraction. The electric de-intercalation lithium extraction system comprises an electric de-intercalation membrane stack, the electric de-intercalation membrane stack comprises at least one membrane stack unit, and the membrane stack unit comprises a lithium extraction polar plate; and parameters in the electric de-intercalation lithium extraction process meet the following formula (1): D =. According to the method, the relevant parameters of the electric de-intercalation lithium extraction are accurately estimated through the mathematical model, the value of each parameter in the electric de-intercalation lithium extraction process can be accurately controlled, the capacity of the lithium extraction equipment is fully utilized, and the production efficiency is improved. The robustness of the mathematical estimation model can be improved by adjusting the equilibrium coefficient D of the electric de-intercalation lithium extraction system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium extraction from salt lakes, and particularly relates to an electric deintercalation lithium extraction system based on parameter decoupling for improving robustness and application thereof. BACKGROUND

[0002] In recent years, with the rapid development of new energy vehicles and energy storage industries, the demand for lithium has surged. Lithium carbonate, as a key lithium salt, is widely used in the field of new energy vehicles. At present, lithium carbonate mainly comes from ore extraction and salt lake extraction. Compared with ore extraction, the lithium reserves in salt lake brine are huge (accounting for 65% of the global total). Salt lake extraction not only reduces the consumption of reagents in the mineral leaching process, but also has more advantages in cost, and will become the main direction of lithium salt production.

[0003] Magnesium-lithium separation is a major technical problem in lithium extraction from salt lakes. China's lithium resource reserves rank third in the world (80% are hosted in salt lake brine), but most of them are high magnesium-lithium ratio brine, which is difficult to develop efficiently. To solve this problem, researchers have developed various process technologies, such as adsorption, electrodialysis, nanofiltration, and extraction. In recent years, a new method for lithium extraction based on the principle of "rocking chair" lithium ion battery has been proposed - electrochemical deintercalation method. This technology uses lithium-rich lithium battery materials as anode and lithium-deficient lithium battery materials as cathode, and builds a new system for lithium extraction from salt lake by electrochemical deintercalation method - "lithium-rich electrode-electrolyte-anion membrane-brine-lithium-deficient electrode".

[0004] For actual production, the extraction rate directly affects production efficiency and cost. How to fully utilize the actual lithium extraction capacity of the electric deintercalation lithium extraction equipment is beneficial to reduce the cost of industrial production and achieve energy saving and consumption reduction. In the process of lithium extraction by electric deintercalation method, the key factors affecting the lithium extraction efficiency of the electrode plate include the coating quality of the electrode plate material surface, the concentration level of lithium ions (Li + ) in the brine, the set value of the tank voltage, and the temperature conditions of the brine during operation. How to accurately adjust and balance the interaction between these parameters to optimize the working efficiency of electric deintercalation lithium extraction and improve the overall efficiency of lithium extraction from salt lakes is of great significance.

[0005] Specifically, increasing the brine flow in the cyclic lithium extraction can improve the lithium extraction efficiency to a certain extent, but blindly increasing the brine flow may damage the coating material on the surface of the electrode plate, affect the cycle performance, and reduce the service life of components such as anion membrane. Therefore, scientific evaluation of the balance relationship between various parameters in electric deintercalation lithium extraction is beneficial to accurately control the values of various parameters in the electric deintercalation lithium extraction process, ensure the full utilization of the production capacity of the lithium extraction equipment, improve the production efficiency, and reduce the operating cost.

[0006] In view of this, the present application is proposed. SUMMARY

[0007] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes an electric intercalation lithium extraction system based on parameter decoupling to improve robustness and its application, aiming to accurately regulate various factors in the electric intercalation lithium extraction process and ensure efficient operation of the salt lake lithium extraction process.

[0008] According to a first aspect of the present application, an electric intercalation lithium extraction system is proposed, comprising an electric intercalation membrane stack, the electric intercalation membrane stack comprising at least one membrane stack unit, the membrane stack unit comprising a lithium extraction electrode plate; The parameters in the electric intercalation lithium extraction process satisfy formula (1): D = Formula (1); Wherein, D is the balance coefficient of the electric intercalation lithium extraction system, and the value range is D∈[0.95, 1.05]; Q is the brine flow, with the unit L / h; is the lithium ion concentration of the brine, with the unit g / L; S is the electrode plate area of the lithium extraction electrode plate, with the unit m 2 ; k1 is the efficiency coefficient of the brine providing lithium ions in unit electrode plate area, with the value 1 / m 2 ; B is the lithium extraction frequency factor, with the empirical value 5.72×10 3 cm 2 / (V·min); is the applied voltage during electric intercalation lithium extraction, with the value range ∈[0.35, 1.1]V; is the iron phosphate coating density on the surface of the lithium extraction electrode plate, with the unit mg / cm 2 ; E is the apparent activation energy, with the value 18.9kJ / mol; R is the molar gas constant, with the value 8.314J / (mol·K); T is the brine temperature during electric intercalation lithium extraction, with the unit K; N is the number of membrane stack units; is the correction parameter, satisfying the following formula: , is the attenuation coefficient, with 0.01h -1 ; t is the electric intercalation lithium extraction time, t∈[0, 24]h.

[0009] the denominator is an estimated formula of the lithium extraction capacity of the lithium extraction system per unit time, which is obtained according to the lithium extraction kinetics equation, and the numerator is the amount of lithium ions provided by the brine per unit time on the lithium extraction electrode plate; theoretically =1, the lithium extraction rate of the lithium extraction electrode plate matches the lithium ion rate provided by the brine, and at this time, the parameters of the lithium extraction system reach equilibrium; however, because the actual lithium extraction capacity of the lithium extraction electrode plate will be lower than the theoretical calculation value, and it is also impossible to separate all the lithium ions in the brine during the actual lithium extraction process, therefore the calculated system equilibrium coefficient will be larger, so the parameter C T is further set to correct the above formula. At the same time, as the lithium extraction process proceeds, the lithium extraction capacity of the lithium extraction electrode plate will gradually decrease, so the correction parameter C T is a variable related to time, and the empirical value is taken as t, which is the lithium extraction time.

[0010] Preferably, the lithium extraction system further comprises a brine storage tank, a lithium-rich liquid storage tank, control valves, liquid pumping devices and a control system, and the control system adjusts the brine flow according to the correction parameter. Further, the control system adjusts the brine flow according to the lithium ion concentration of the brine and the correction parameter.

[0011] Preferably, the brine flow is 3.32×10 3 ~1.82×10 4 L / h.

[0012] Preferably, the electrode plate area is 0.1~5m 2 .

[0013] Preferably, the coating density ≤5000 mg / cm 2 .

[0014] Preferably, the brine temperature is 20~45℃. When calculating, the brine temperature is calculated in K, and K=℃+273.15.

[0015] Preferably, the brine storage tank is provided with a first temperature control device, and the lithium-rich liquid storage tank is provided with a second temperature control device. The brine storage tank and the lithium-rich liquid storage tank in the present application are provided with temperature control devices (such as electric heating, circulating water cooling, heat exchangers, etc.), so as to control the temperature of the brine and the lithium-rich liquid.

[0016] Preferably, the membrane stack unit comprises a first separator, a first electrode plate, a second separator, an anion membrane, a third separator, a second electrode plate and a fourth separator arranged in sequence; the first separator and the second separator form a first chamber, and the third separator and the fourth separator form a second chamber. It can be understood that the first electrode plate is located in the first chamber, and the second electrode plate is located in the second chamber. Optionally, the first separator, the first electrode plate, the second separator, the third separator, the second electrode plate and the fourth separator are provided with an outer frame, at least one end of the outer frame is provided with a through hole, so that the anions (such as chloride ions) in the brine in the membrane stack unit during the lithium extraction process can pass through the anion membrane into the lithium-rich liquid, ensuring the continuous reaction; at the same time, the anion membrane is arranged between the membrane stack units to maintain the charge balance of the lithium extraction system.

[0017] Preferably, the adjacent membrane stack units are separated by an additional anion membrane.

[0018] More preferably, the lithium extraction membrane stack comprises a plurality of membrane stack units, the first chambers in the plurality of membrane stack units are sequentially connected by pipelines, and the second chambers in the plurality of membrane stack units are sequentially connected by pipelines; and / or the number of the membrane stack units is 2-24. In the present application, "a plurality of" refers to two or more than two, the first (second) chambers in the plurality of membrane stack units are sequentially connected by pipelines, which means that the first (second) chamber of the first membrane stack unit is connected with the first (second) chamber of the second membrane stack unit, if there is a third membrane stack unit, the first (second) chamber thereof is connected with the first (second) chamber of the second membrane stack unit, and so on. The above connection mode can ensure that the flow rates of the brine or the lithium-rich liquid in each chamber are equal, thereby stably controlling the lithium extraction process.

[0019] Preferably, the control valve comprises a lithium-rich liquid delivery valve and a brine delivery valve, the lithium-rich liquid delivery valve comprises a first valve, a third valve, a fifth valve and an eighth valve, the brine delivery valve comprises a second valve, a fourth valve, a sixth valve and a seventh valve; the liquid pumping device comprises a first liquid pump and a second liquid pump.

[0020] Preferably, in one working state of the lithium extraction system, the third valve, the fourth valve, the fifth valve and the sixth valve are closed, the first valve, the second valve, the seventh valve and the eighth valve are opened, the solution in the lithium-rich liquid storage tank enters the lithium extraction membrane stack through the first valve and the first liquid pump in sequence, then passes through the second chamber in each membrane stack unit in sequence, and then returns to the lithium-rich liquid storage tank through the eighth valve; the solution in the brine storage tank enters the lithium extraction membrane stack through the second valve and the second liquid pump in sequence, then passes through the first chamber in each membrane stack unit in sequence, and then returns to the brine storage tank through the seventh valve. In another working state of the lithium extraction system, the third valve, the fourth valve, the fifth valve and the sixth valve are opened, and the first valve, the second valve, the seventh valve and the eighth valve are closed. The solution in the lithium-rich liquid storage tank enters the lithium extraction membrane stack through the third valve and the second liquid pump in sequence, and then passes through the first chamber in each membrane stack unit in sequence, and then returns to the lithium-rich liquid storage tank through the fifth valve. The solution in the brine storage tank enters the lithium extraction membrane stack through the fourth valve and the first liquid pump in sequence, and then passes through the second chamber in each membrane stack unit in sequence, and then returns to the brine storage tank through the sixth valve.

[0021] According to a second aspect of the present application, the application of the lithium extraction system according to the first aspect of the present application in the production of lithium from salt lakes is proposed.

[0022] According to an embodiment of the present application, at least the following beneficial effects are achieved: The present application proposes a lithium extraction system based on parameter decoupling to improve robustness. The mathematical model is used to accurately estimate the lithium extraction related parameters, which is beneficial to accurately control the values of various parameters in the lithium extraction process, and ensures that the production capacity of the lithium extraction equipment is fully utilized and the production efficiency is improved. Through the adjustment of the balance coefficient D of the lithium extraction system, the robustness of the mathematical estimation model of the present application can be improved to meet the needs of lithium extraction equipment of different types and specifications. BRIEF DESCRIPTION OF DRAWINGS

[0023] The present application will be further described below in conjunction with the drawings and examples, in which: Figure 1 The physical structure diagram of the lithium extraction system of the present application; Figure 2 The principle diagram of lithium extraction; Figure 3 The membrane stack structure schematic diagram; Figure 4 The lithium extraction efficiency data trend diagram of Example 1 and Comparative Examples 1-2 of the present application; Figure 5 The lithium extraction efficiency data trend diagram of Example 2 and Comparative Examples 3-4 of the present application; Figure 6 The lithium extraction efficiency data trend diagram of Example 3 and Comparative Examples 5-6 of the present application; Figure 7 The lithium extraction efficiency data trend diagram of Example 4 and Comparative Examples 7-8 of the present application; Figure 8 The lithium extraction efficiency data trend diagram of Example 5 and Comparative Examples 9-10 of the present application.

[0024] Reference signs: 101, electric deintercalation membrane stack; 201, lithium-rich liquid storage tank; 301, brine storage tank; 401, first liquid pump; 402, second liquid pump; 501, first valve; 502, second valve; 503, third valve; 504, fourth valve; 505, fifth valve; 506, sixth valve; 507, seventh valve; 508, eighth valve; 601, first end plate; 602, first rubber pad; 603, first membrane stack unit; 6031, first separator; 6032, first electrode plate; 6033, second separator; 6034, first anion membrane; 6035, third separator; 6036, second electrode plate; 6037, fourth separator; 604, second anion membrane; 605, second membrane stack unit; 606, second rubber pad; 607, second end plate. DETAILED DESCRIPTION

[0025] The concept and the resulting technical effects of the present application will be described below in conjunction with embodiments, so as to fully understand the purposes, features and effects of the present application.

[0026] It should be noted that the terms "first", "second" and the like in the description and in the claims, as well as above-described appended drawings, are used only for distinguishing between similar objects and do not necessarily have a specific temporal or chronological order. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The use of terms "including", "comprising", or "having" should be understood to be open and non-limiting.

[0027] The ranges disclosed herein are defined by the lower and upper limits of the range, given that the range is defined by selecting a lower limit and an upper limit, the selected lower limit and upper limit define the boundaries of the particular range. In particular, the terms "(", ")", "[" and "]" indicate intervals, where "(" or ")" indicate open intervals, i.e. the end values of the interval are not included; with "[" and "]" indicating closed intervals, i.e. the end values are included in the interval. The ranges defined in this way can include or not include the end values, and can be combined arbitrarily, i.e. any lower limit can be combined with any upper limit to form a range.

[0028] The application provides an electro-deintercalation lithium extraction system, comprising an electro-deintercalation membrane stack 101, a brine storage tank 301, a lithium-rich liquid storage tank 201, control valves, liquid pumping devices and a control system. The control valves comprise lithium-rich liquid delivery valves and brine delivery valves, the lithium-rich liquid delivery valves comprise a first valve 501, a third valve 503, a fifth valve 505 and an eighth valve 508, and the brine delivery valves comprise a second valve 502, a fourth valve 504, a sixth valve 506 and a seventh valve 507; the liquid pumping devices comprise a first liquid pump 401 and a second liquid pump 402, as shown in Figure 1 .

[0029] In some embodiments, the brine storage tank and the lithium-rich liquid storage tank are respectively provided with temperature control devices, so as to control the temperature of the brine and the lithium-rich liquid. The temperature control devices can be selected from one of electric heating, circulating water cooling or a heat exchanger.

[0030] In some embodiments, the electro-deintercalation membrane stack 101 comprises a plurality of membrane stack units, each of which comprises a first baffle 6031, a first electrode plate 6032, a second baffle 6033, a first anion membrane 6034, a third baffle 6035, a second electrode plate 6036 and a fourth baffle 6037 arranged in sequence, and adjacent membrane stack units are separated by an additionally arranged second anion membrane 604. The first baffle 6031 and the second baffle 6033 form a first chamber of the membrane stack unit, the first electrode plate 6032 is located in the first chamber, the third baffle 6035 and the fourth baffle 6037 form a second chamber of the membrane stack unit, and the second electrode plate 6036 is located in the second chamber. The first baffle, the first electrode plate, the second baffle, the third baffle, the second electrode plate and the fourth baffle are provided with an outer frame (not shown in the figure), one end of the outer frame is provided with a through hole, so that the anions (such as chloride ions) in the brine in the membrane stack unit can pass through the anion membrane into the lithium-rich liquid during the electro-deintercalation lithium extraction process, ensuring that the reaction continues; at the same time, the setting of the anion membrane between the membrane stack units maintains the stable operation of the electro-deintercalation lithium extraction system.

[0031] In some embodiments, the electro-deintercalation membrane stack 101 further comprises a pair of end plates and a pair of rubber pads, and taking the number of membrane stack units as an example, the electro-deintercalation membrane stack 101 comprises a first end plate 601, a first rubber pad 602, a first membrane stack unit 603, a second anion membrane 604, a second membrane stack unit 605, a second rubber pad 606 and a second end plate 607 arranged in sequence, as shown in Figure 3 .

[0032] When the lithium extraction system enters one of the working states, the first electrode plate in the membrane stack unit is a cathode plate, and the surface can be coated with iron phosphate material, and the second electrode plate is an anode plate, and the surface can be coated with lithium iron phosphate material; the third valve 503, the fourth valve 504, the fifth valve 505 and the sixth valve 506 are closed, and the first valve 501, the second valve 502, the seventh valve 507 and the eighth valve 508 are opened. The brine in the brine storage tank 301 is transported into the electric intercalation membrane stack 101 by the second valve 502 and the second liquid pump 402, the first chamber of the first membrane stack unit 603 and the first chamber of the second membrane stack unit 605 are connected by a pipeline, and the brine sequentially passes through the first chambers of multiple membrane stack units, and the iron ions in the first electrode plate are reduced by electrons, so that the lithium ions in the brine can be intercalated into the iron phosphate to generate lithium iron phosphate, and the brine leaves the electric intercalation membrane stack 101 and returns to the brine storage tank 301 through the seventh valve 507; the lithium-rich liquid in the lithium-rich liquid storage tank 201 is transported into the electric intercalation membrane stack 101 by the first valve 501 and the first liquid pump 401, the second chamber of the first membrane stack unit 603 and the second chamber of the second membrane stack unit 605 are connected by a pipeline, and the lithium-rich liquid sequentially passes through the second chambers of multiple membrane stack units, and the ferrous ions in the second electrode plate are oxidized by losing electrons, so that the lithium ions in the lithium iron phosphate are removed to generate iron phosphate, and the lithium ions enter the lithium-rich liquid to realize enrichment, and the lithium-rich liquid leaves the electric intercalation membrane stack 101 and returns to the lithium-rich liquid storage tank 201 through the eighth valve 508.

[0033] When the lithium extraction system enters another working state, the voltage applied to the electrode plate is opposite to the first working state, the first electrode plate of the membrane stack unit is an anode plate, and the surface is lithium iron phosphate material, and the second electrode plate is a cathode plate, and the surface is iron phosphate material; the third valve 503, the fourth valve 504, the fifth valve 505 and the sixth valve 506 are opened, and the first valve 501, the second valve 502, the seventh valve 507 and the eighth valve 508 are closed. The brine in the brine storage tank 301 is transported into the electric intercalation membrane stack 101 by the fourth valve 504 and the first liquid pump 401, the brine sequentially passes through the second chambers of multiple membrane stack units, and the iron ions in the second electrode plate are reduced by electrons, so that the lithium ions in the brine can be intercalated into the iron phosphate to generate lithium iron phosphate, and the brine leaves the electric intercalation membrane stack 101 and returns to the brine storage tank 301 through the sixth valve 506; the lithium-rich liquid in the lithium-rich liquid storage tank 201 is transported into the electric intercalation membrane stack 101 by the third valve 503 and the second liquid pump 402, the lithium-rich liquid sequentially passes through the first chambers of multiple membrane stack units, and the ferrous ions in the first electrode plate are oxidized by losing electrons, so that the lithium ions in the lithium iron phosphate are removed to generate iron phosphate, and the lithium ions enter the lithium-rich liquid to realize further enrichment, and the lithium-rich liquid leaves the electric intercalation membrane stack 101 and returns to the lithium-rich liquid storage tank 201 through the fifth valve 505.

[0034] Through the above two working state cycles, lithium resources in the brine can be enriched in the lithium-rich liquid.

[0035] In the present application, the control system adjusts the brine flow by controlling the motor power of the liquid pump, and the parameters in the lithium extraction process by electro-deintercalation meet formula (1): D = Formula (1); Wherein, D is the balance coefficient of the lithium extraction system by electro-deintercalation, and the value range is D∈[0.95, 1.05]; Q is the brine flow, unit L / h; is the lithium ion concentration of the brine, unit g / L; S is the electrode plate area of the lithium extraction, unit m 2 ; k1 is the efficiency coefficient of the brine providing lithium ions in unit electrode plate area, value 1 / m 2 ; B is the lithium extraction frequency factor, and the experience value is 5.72×10 3 cm 2 / (V·min); is the voltage applied during lithium extraction by electro-deintercalation, the value range ∈[0.35, 1.1]V; is the iron phosphate coating density on the surface of the lithium extraction electrode plate, unit mg / cm 2 ; E is the apparent activation energy, and the value is 18.9kJ / mol; R is the molar gas constant, and the value is 8.314J / (mol·K); T is the brine temperature during lithium extraction by electro-deintercalation, unit K; N is the number of membrane stack units; is the correction parameter, which meets the following formula: , is the attenuation coefficient, and the value is 0.01h -1 ; t is the lithium extraction time by electro-deintercalation, t∈[0, 24]h.

[0036] The present application will be described in detail below in combination with specific embodiments. The calculated flow is used as the experimental condition for continuous experiments. In order to ensure the consistency of the test conditions, the present experiment adopts a continuous brine supply mode, that is, the brine is no longer circulated for lithium extraction, so as to ensure that the ion concentration of the brine flowing into the membrane stack is unchanged. The flow detection instrument in the experiment adopts a Japanese Yokohama DN series electromagnetic flowmeter.

[0037] Example 1 The experiment used an electro-deintercalation lithium extraction device with a 24-layer membrane stack structure, where the electrode area of ​​each layer was 1 m². 2 Set the slot voltage =0.5V, =2500 mg / cm 2 At a temperature of T = 298.15 K, the Li content of the brine was measured. + concentration =0.88g / L, take D=1, C T =0.2. The optimal brine flow rate calculated by simulation is approximately 6.84 × 10⁻⁶. 3 L / h. Based on the estimated value, brine was pumped into the membrane stack. Simultaneously, multiple membrane stacks (based on comparative experiments) were set up for electrodeposition and extraction of lithium. Every hour, the electrode plates were removed for lithium extraction, and the Li content in the extraction solution was measured. + The lithium content was calculated, and the lithium extraction capacity per hour ((Li) mg / g(FePO4)) was obtained. The experimental parameters are shown in Table 1, the changes in lithium extraction capacity are shown in Table 2, and the trend of lithium extraction capacity is shown in [Table 2]. Figure 4 After one lithium extraction cycle, the electrodes were switched, and the operating state of the electro-deintercalation lithium extraction system was changed to perform lithium extraction again. The above steps were repeated, and the cycle performance of the electrodes was measured after 100 cycles, as shown in Table 4.

[0038] Example 2 The experiment used an electro-deintercalation lithium extraction device with a 24-layer membrane stack structure, where the electrode area of ​​each layer was 1 m². 2 Set the slot voltage =1.1V, =2500 mg / cm 2 At a temperature of T = 298.15 K, the Li content of the brine was measured. + concentration =0.88g / L, take D=1, C T =0.2. The optimal brine flow rate calculated by simulation is approximately 1.5 × 10⁻⁶. 4 L / h. Based on the estimated value, brine was pumped into the membrane stack. Simultaneously, multiple membrane stacks (based on comparative experiments) were set up for electrodeposition and extraction of lithium. Every hour, the electrode plates were removed for lithium extraction, and the Li content in the extraction solution was measured. + The lithium content was calculated, and the lithium extraction capacity per hour ((Li) mg / g(FePO4)) was obtained. The experimental parameters are shown in Table 1, the changes in lithium extraction capacity are shown in Table 2, and the trend of lithium extraction capacity is shown in [Table 2]. Figure 5 After one lithium extraction cycle, the electrodes were switched, and the operating state of the electro-deintercalation lithium extraction system was changed to perform lithium extraction again. The above steps were repeated, and the cycle performance of the electrodes was measured after 100 cycles, as shown in Table 4.

[0039] Example 3 The experiment used an electro-deintercalation lithium extraction device with a 24-layer membrane stack structure, where the electrode area of ​​each layer was 1 m².2 , the tank voltage is set to be 0.35 V, =0.35V, =2500 mg / cm 2 , the temperature T = 298.15 K, the measured brine Li + concentration =0.88g / L, taking D = 1, C T =0.2. The simulation calculates that the optimal brine flow value is about 4.79 x 10 3 L / h. According to the estimated value, the brine is pumped to the membrane stack, and multiple groups of membrane stacks (according to the comparative experiment) are set to carry out the lithium extraction by the electric intercalation and deintercalation. Every 1 hour, the electrode plate is taken out for lithium extraction, and the Li + content in the lithium extraction solution is measured, and the lithium extraction capacity ((Li) mg / g (FePO4)) per hour is calculated. The experimental parameters are shown in Table 1, the lithium extraction capacity change is shown in Table 2, and the lithium extraction capacity trend is shown in Figure 6 . After one lithium extraction cycle, the electrode is replaced, the working state of the lithium extraction system by the electric intercalation and deintercalation is switched, and the lithium extraction is carried out again. The above steps are repeated, and the cycle performance of the electrode is measured for 100 cycles, as shown in Table 4.

[0040] Example 4 The experiment adopts a 24-layer membrane stack structure for the lithium extraction by the electric intercalation and deintercalation, the electrode plate area in each membrane stack structure is 1 m 2 , the tank voltage is set to be 0.5 V, =0.5V, =5000 mg / cm 2 , the temperature T = 298.15 K, the measured brine Li + concentration =0.88g / L, taking D = 1, C T =0.2. The simulation calculates that the optimal brine flow value is about 1.36 x 10 4 L / h. According to the estimated value, the brine is pumped to the membrane stack, and multiple groups of membrane stacks (according to the comparative experiment) are set to carry out the lithium extraction by the electric intercalation and deintercalation. Every 1 hour, the electrode plate is taken out for lithium extraction, and the Li + content in the lithium extraction solution is measured, and the lithium extraction capacity ((Li) mg / g (FePO4)) per hour is calculated. The experimental parameters are shown in Table 1, the lithium extraction capacity change is shown in Table 2, and the lithium extraction capacity trend is shown in Figure 7 . After one lithium extraction cycle, the electrode is replaced, the working state of the lithium extraction system by the electric intercalation and deintercalation is switched, and the lithium extraction is carried out again. The above steps are repeated, and the cycle performance of the electrode is measured for 100 cycles, as shown in Table 4.

[0041] Example 5 The experiment adopts a 24-layer membrane stack structure for the lithium extraction by the electric intercalation and deintercalation, the electrode plate area in each membrane stack structure is 1 m 2 , the tank voltage is set to be 0.5 V, =0.5V, =1500 mg / cm 2 At a temperature of T = 298.15 K, the Li content of the brine was measured. + concentration =0.88g / L, take D=1, C T =0.2. The optimal brine flow rate calculated by simulation is approximately 4.1 × 10⁻⁶. 3 L / h. Based on the estimated value, brine was pumped into the membrane stack. Simultaneously, multiple membrane stacks (based on comparative experiments) were set up for electrodeposition and extraction of lithium. Every hour, the electrode plates were removed for lithium extraction, and the Li content in the extraction solution was measured. + The lithium content was calculated, and the lithium extraction capacity per hour ((Li) mg / g(FePO4)) was obtained. The experimental parameters are shown in Table 1, the changes in lithium extraction capacity are shown in Table 2, and the trend of lithium extraction capacity is shown in [Table 2]. Figure 8 After one lithium extraction cycle, the electrodes were switched, and the operating state of the electro-deintercalation lithium extraction system was changed to perform lithium extraction again. The above steps were repeated, and the cycle performance of the electrodes was measured after 100 cycles, as shown in Table 4.

[0042] Example 6 The experiment used an electro-deintercalation lithium extraction device with a 24-layer membrane stack structure, where the electrode area of ​​each layer was 1 m². 2 Set the slot voltage =0.5V, =2500 mg / cm 2 At a temperature of T = 298.15 K, the Li content of the brine was measured. + concentration =0.88g / L, take D=1. Continuous electro-extraction and extraction of lithium is performed, every hour according to... Calculate C T Subsequently, the optimal brine flow rate for that hour was calculated using simulation, and the brine flow rate pumped to the membrane stack was adjusted based on the estimated value. After one lithium extraction cycle, the electrode plates were removed for delithiation, and the Li content in the delithiation solution was measured. + The lithium content was determined, and the lithium extraction capacity ((Li) mg / g(FePO4)) within that cycle was obtained. Experimental parameters and lithium extraction capacities are shown in Table 3. The electrodes were then swapped, and the operating state of the electro-deintercalation lithium extraction system was switched for another lithium extraction cycle. The above steps were repeated 100 times, and the cycle performance of the electrodes was measured, as shown in Table 4.

[0043] Comparative Example 1 The only difference from Example 1 is that the brine flow rate is approximately 8.28 × 10⁻⁶. 3 L / h.

[0044] Comparative Example 2 The only difference from Example 1 is that the brine flow rate is approximately 5.55 × 10⁻⁶. 3 L / h.

[0045] Comparative Example 3 The difference from Example 2 is only that the brine flow rate is about 1.82 x 10 4 L / h.

[0046] Comparative Example 4 The difference from Example 2 is only that the brine flow rate is about 1.21 x 10 4 L / h.

[0047] Comparative Example 5 The difference from Example 3 is only that the brine flow rate is about 5.27 x 10 3 L / h.

[0048] Comparative Example 6 The difference from Example 3 is only that the brine flow rate is about 4.31 x 10 3 L / h.

[0049] Comparative Example 7 The difference from Example 4 is only that the brine flow rate is about 1.50 x 10 4 L / h.

[0050] Comparative Example 8 The difference from Example 4 is only that the brine flow rate is about 1.23 x 10 4 L / h.

[0051] Comparative Example 9 The difference from Example 5 is only that the brine flow rate is about 4.97 x 10 3 L / h.

[0052] Comparative Example 10 The difference from Example 5 is only that the brine flow rate is about 3.32 x 10 3 L / h.

[0053] Comparative Example 11 The difference from Example 6 is only that the brine flow rate is kept at 8.28 x 10 3 L / h.

[0054] Comparative Example 12 The difference from Example 6 is only that the brine flow rate is kept at 5.55 x 10 3 L / h.

[0055] Table 1

[0056] Table 2

[0057] Table 3

[0058] Table 4

[0059] According to the experimental results of Table 2 and the attached Figures 4-8 It can be known that under different voltage and iron phosphate coating density conditions, the brine flow calculated by the D theory within the scope of the present application can achieve very ideal lithium extraction efficiency, and when D is not within the scope of the present application, or the brine flow is lower than the theoretical estimated value, the lithium extraction efficiency is significantly reduced; or when the brine flow is greater than the theoretical estimated value, the lithium extraction efficiency is not improved or has no obvious improvement. Through the above comparison of brine flow and lithium extraction efficiency under different conditions, it can be known that the brine flow value estimated can ensure the lithium extraction efficiency. According to the experimental results of Table 3, under the condition of continuous lithium extraction, the brine flow calculated according to the gradually changed correction parameters can still achieve good lithium extraction efficiency, and when the brine flow is kept lower than the theoretical estimated value, the lithium extraction efficiency is significantly lower, and when the brine flow is kept greater than the theoretical estimated value, the lithium extraction efficiency is not improved or has no obvious improvement. According to the experimental results of Table 4, it can be known that the cycle performance of the electrode is good when the brine flow calculated by the theory is used for cyclic lithium extraction, and when the brine flow is greater than the theoretical estimated value, it will obviously affect the cycle performance of the electrode.

[0060] The above has made a detailed description of the embodiments of the present application, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge range of ordinary skilled in the art without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A lithium extraction system, comprising: a lithium source; a lithium extraction cell; a lithium intercalation cell; and a lithium intercalation cell controller. The system comprises an electro-deintercalation membrane stack, which comprises at least one membrane stack unit, and the membrane stack unit comprises a lithium extraction electrode plate. Parameters in the electro-deintercalation lithium extraction process satisfy formula (1): D = Formula (1); Wherein, D is the equilibrium coefficient of the electro-deintercalation lithium extraction system, and the value range is D∈[0.95, 1.05]; Q is the brine flow, in L / h; Lithium concentration in brine, in g / L; S is the area of the lithium extraction electrode plate in m2 2 ; k1 is the efficiency coefficient of the brine to provide lithium ions in unit of polar plate area, taking value 1 / m 2 ; B is the lithium extraction frequency factor, taken as 5.72 x 10 3 cm 2 / (V min); the voltage applied for the electro-intercalation of lithium, taking values in the range ∈ [0.35, 1.1] V; The coating density of the iron phosphate on the surface of the lithium extraction electrode plate is mg / cm 2 ; E is the apparent activation energy, and the value is 18.9 kJ / mol; R is the molar gas constant, and the value is 8.314 J / (mol·K); T is the brine temperature during electro-deintercalation lithium extraction, in K; N is the number of membrane stack units; For the correction parameter, the following formula is satisfied: , is the attenuation coefficient, taking the value 0.01h -1 ; t is the lithium extraction time, t ∈ [0, 24]h.

2. The electro-intercalation lithium extraction system of claim 1, wherein, The electro-deintercalation lithium extraction system further comprises a brine storage tank, a lithium-rich liquid storage tank, control valves, liquid pumping devices and a control system, and the control system adjusts the brine flow according to the correction parameters.

3. The electro-intercalation lithium extraction system of claim 2, wherein, The brine flow rate is 3.32 x 10 3 ~1.82 x 10 4 L / h.

4. The electro-intercalation lithium extraction system of claim 1, wherein, The electrode plate area is 0.1-5 m 2 .

5. The electro-intercalation lithium extraction system of claim 1, wherein, The coating density ≤ 5000 mg / cm 2 .

6. The electro-intercalation lithium extraction system of claim 1, wherein, The brine temperature is 20-45℃.

7. The electro-intercalation lithium extraction system of claim 2, wherein, The brine storage tank is provided with a first temperature control device, and the lithium-rich liquid storage tank is provided with a second temperature control device.

8. The electro-intercalation lithium extraction system of claim 1, wherein, The membrane stack unit comprises a first baffle, a first electrode plate, a second baffle, an anion membrane, a third baffle, a second electrode plate and a fourth baffle arranged in sequence; the first baffle and the second baffle form a first chamber, and the third baffle and the fourth baffle form a second chamber.

9. The electro-intercalation lithium extraction system of claim 8, wherein, The electro-deintercalation membrane stack comprises a plurality of membrane stack units, the first chambers in the plurality of membrane stack units are sequentially connected through pipelines, the second chambers in the plurality of membrane stack units are sequentially connected through pipelines; and / or the number of the membrane stack units is 2-24.

10. Application of the electro-deintercalation lithium extraction system in claim any one of claims 1-9 in lithium extraction production in salt lakes.

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