System for preparing lithium carbonate based on electric lithium extraction method

Abstract

The invention discloses a system for preparing lithium carbonate based on an electric lithium extraction method, comprising: an electric lithium extraction device comprising an electric lithium extraction box body, and a first electrode plate and a second electrode plate which are alternately arranged in the electric lithium extraction box body in sequence, the electric lithium extraction box body is provided with a first pipe orifice and a second pipe orifice, and the first pipe orifice and the second pipe orifice are communicated with each other; the two electrode plates are respectively connected with positive and negative voltages, the positive and negative voltages of the two electrode plates can be exchanged, and the first electrode plate can electrically adsorb lithium ions in brine when connected with the negative voltage and release the adsorbed lithium ions when connected with the positive voltage; the brine circulating unit is connected with the first pipe orifice and the second pipe orifice through pipelines and is used for circularly conveying brine to the electric lithium extraction equipment for adsorbing lithium ions; and the lithium discharging circulating unit is connected with the first pipe orifice and the second pipe orifice through pipelines and is used for circularly conveying the recovery liquid to the electric lithium extraction equipment for discharging lithium. By using the system, the problem of lithium-magnesium separation can be effectively solved, the problems of low lithium-magnesium separation rate, difficulty in desorption or extraction and the like of a chemical method are solved, and the problem of membrane pollution does not exist.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium extraction from salt lakes, and in particular to a system for preparing lithium carbonate based on an electrolithium extraction method. Background Art

[0002] In the process of lithium extraction from salt lakes, the separation of lithium and magnesium is a key technical difficulty. Currently, common methods are divided into chemical, membrane and electrochemical methods. Chemical methods include calcination, precipitation, adsorption and extraction. There are problems such as low lithium-magnesium separation rate, difficulty in desorption or extraction, and decreased efficiency of adsorption or extraction agents. They are often difficult to apply due to high costs. The membrane separation method uses pressure or electric field as the driving force to separate lithium and magnesium through the selective permeability of the membrane, but this process is prone to membrane contamination, which limits the application of this method. In addition, the membrane separation method has poor selectivity for monovalent cations and it is difficult to reduce the sodium-lithium ratio (in some salt lake brines, the sodium-lithium ratio is as high as 100, such as the Zabuye Salt Lake). The electrochemical method refers to the use of the charge and discharge process of electrode materials to extract lithium ions from water. There are no problems such as desorption or extraction, and there is no membrane contamination, but stable production has not yet been achieved. Summary of the Invention

[0003] To this end, the present invention provides a system for preparing lithium carbonate based on the lithium electrolysis method to solve one or more of the above-mentioned technical problems.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A system for preparing lithium carbonate based on lithium electrolysis, comprising:

[0006] The lithium extraction equipment comprises a lithium extraction box and a first electrode plate and a second electrode plate alternately arranged in the lithium extraction box, wherein the lithium extraction box is provided with a first pipe opening and a second pipe opening, the two electrode plates are respectively connected to positive and negative voltages, and the positive and negative voltages of the two electrode plates are reversible, wherein the first electrode plate can electrically adsorb lithium ions in brine when connected to a negative voltage and release the adsorbed lithium ions when connected to a positive voltage;

[0007] a brine circulation unit connected to the first pipe opening and the second pipe opening through a pipeline, and configured to circulate brine to the lithium electroextraction equipment for lithium ion adsorption;

[0008] The lithium discharge circulation unit is connected to the first pipe opening and the second pipe opening through a pipeline, and is used for circulating the recovery liquid to the lithium electrolytic stripping equipment for lithium discharge.

[0009] Furthermore, the system for preparing lithium carbonate based on the lithium electroextraction method also includes a natural evaporation lithium precipitation unit, which is connected to the lithium release circulation unit through a pipeline and is used for performing natural evaporation, concentration, precipitation and crystallization operations.

[0010] Furthermore, the first electrode plate is a lithium manganate or lithium iron phosphate electrode plate, and the second electrode plate is a graphite electrode plate or a lithium titanate electrode plate.

[0011] Furthermore, the lithium electroextraction equipment further includes an anion exchange membrane, which is disposed between the first electrode plate and the second electrode plate.

[0012] Furthermore, the system for preparing lithium carbonate based on the lithium electrolysis method also includes a cleaning unit, which is connected to the first pipe opening and the second pipe opening through a pipeline and is used to circulate clean water to the lithium electrolysis equipment.

[0013] Furthermore, the brine circulation unit includes a brine raw water tank, a brine make-up pipe, a brine make-up pump, a brine circulation box, a first brine circulation pipe, a brine circulation pump, a first brine circulation valve, a second brine circulation pipe and a second brine circulation valve. The brine raw water tank is connected to the brine circulation box through the brine make-up pipe, the brine make-up pump is connected in series to the head end of the brine make-up pipe, the brine circulation box is connected to the first pipe mouth through the first brine circulation pipe, the brine circulation pump is connected in series to the head end of the first brine circulation pipe, the first brine circulation valve is connected in series to the end of the first brine circulation pipe, the second pipe mouth is connected to the brine circulation box through the second brine circulation pipe, and the second brine circulation valve is connected in series to the head end of the second brine circulation pipe.

[0014] Furthermore, the lithium discharge circulation unit includes a lithium discharge circulation box, a first lithium discharge circulation pipe, a lithium discharge circulation pump, a first lithium discharge circulation valve, a second lithium discharge circulation pipe and a second lithium discharge circulation valve. The lithium discharge circulation box is connected to the first pipe port through the first lithium discharge circulation pipe, the lithium discharge circulation pump is connected in series to the head end of the first lithium discharge circulation pipe, the first lithium discharge circulation valve is connected in series to the end of the first lithium discharge circulation pipe, the second pipe port is connected to the lithium discharge circulation box through the second lithium discharge circulation pipe, and the second lithium discharge circulation valve is connected in series to the head end of the second lithium discharge circulation pipe.

[0015] Furthermore, the cleaning unit includes a pure water tank, a pure water replenishing pipe, a pure water replenishing pump, a brine cleaning tank, a first brine cleaning pipe, a brine cleaning pump, a first brine cleaning valve, a second brine cleaning pipe, a second brine cleaning valve, a lithium-discharging cleaning tank, a first lithium-discharging cleaning pipe, a lithium-discharging cleaning pump, a first lithium-discharging cleaning valve, a second lithium-discharging cleaning pipe and a second lithium-discharging cleaning valve. The pure water tank is connected to the brine cleaning tank and the lithium-discharging cleaning tank through the pure water replenishing pipe, the pure water replenishing pump is connected in series to the head end of the pure water replenishing pipe, the brine cleaning tank is connected to the first pipe mouth through the first brine cleaning pipe, and the brine cleaning pump is connected in series to the first brine cleaning tank. The head end of the cleaning pipe, the first brine cleaning valve is connected in series to the end of the first brine cleaning pipe, the second pipe mouth is connected to the brine cleaning tank through the second brine cleaning pipe, the second brine cleaning valve is connected in series to the head end of the second brine cleaning pipe, the lithium discharge cleaning tank is connected to the first pipe mouth through the first lithium discharge cleaning pipe, the lithium discharge cleaning pump is connected in series to the head end of the first lithium discharge cleaning pipe, the first lithium discharge cleaning valve is connected in series to the end of the first lithium discharge cleaning pipe, the second pipe mouth is connected to the lithium discharge cleaning tank through the second lithium discharge cleaning pipe, and the second lithium discharge cleaning valve is connected in series to the head end of the second lithium discharge cleaning pipe.

[0016] Furthermore, the system for preparing lithium carbonate based on the lithium electrolysis method also includes a backflush unit, which is connected to the lithium electrolysis equipment through a pipeline and is used to perform gas backflush on the lithium electrolysis equipment.

[0017] Furthermore, the back-blowing unit includes a high-pressure fan, a first back-blowing pipe, a first back-blowing valve, a second back-blowing pipe, a second back-blowing valve and a back-blowing pool, the high-pressure fan is connected to the second pipe mouth through the first back-blowing pipe, the first back-blowing valve is connected in series to the first back-blowing pipe, the first pipe mouth is connected to one end of the second back-blowing pipe, the other end of the second back-blowing pipe is connected to the back-blowing pool, and the second back-blowing valve is connected in series to the second back-blowing pipe.

[0018] The present invention has the following advantages:

[0019] During use: the first electrode plate is connected to a negative voltage, the second electrode plate is connected to a positive voltage, the brine circulation unit circulates the salt lake brine containing lithium ions, magnesium ions and sodium ions into the lithium electroextraction equipment, and under the electric field and the selection of the first electrode plate made of special materials, the lithium ions are electrically adsorbed on the first electrode plate, the magnesium ions remain in the original brine, and only a small amount of sodium ions are adsorbed on the first electrode plate; after the lithium adsorption process is completed, the voltages of the first electrode plate and the second electrode plate are swapped, and the lithium discharge circulation unit circulates a recovery liquid containing a small amount of sodium chloride or lithium chloride to the lithium electroextraction equipment; after the lithium discharge process is completed, a lithium-rich liquid with a high lithium ion content is obtained in the lithium discharge circulation unit.

[0020] Therefore, by adopting the system for preparing lithium carbonate based on the lithium electroextraction method provided by the present invention, the problem of lithium-magnesium separation can be effectively solved, and the problems of low lithium-magnesium separation rate, difficulty in desorption or extraction, and decreased efficiency of adsorption or extraction agents in chemical methods can be overcome; there is no membrane contamination problem, and the defect of membrane separation method being limited by membrane contamination is overcome; and the industrial application of electrochemical lithium extraction is realized.

[0021] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present application will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can, without inventive effort, derive other implementation drawings based on the provided drawings.

[0023] The structures, proportions, sizes, etc. illustrated in this specification are intended solely to complement the contents disclosed herein and to facilitate understanding and reading by persons skilled in the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall remain within the scope of the technical contents disclosed herein.

[0024] Figure 1 A schematic diagram of the connection relationship of a system for preparing lithium carbonate based on the lithium electrolysis method provided in an embodiment of the present invention;

[0025] Figure 2 A structural block diagram of a system for preparing lithium carbonate based on lithium electrolysis provided by an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of the internal structure of a lithium electrolysis device for preparing lithium carbonate based on a lithium electrolysis method provided by an embodiment of the present invention;

[0027] Figure 4 A schematic diagram of the connection relationship between the lithium extraction equipment and the brine circulation unit of a system for preparing lithium carbonate based on the lithium extraction method provided by an embodiment of the present invention;

[0028] Figure 5 A schematic diagram of the connection relationship between the lithium extraction equipment and the lithium discharge circulation unit of a system for preparing lithium carbonate based on the lithium extraction method provided by an embodiment of the present invention;

[0029] Figure 6 A schematic diagram of the connection relationship between the lithium extraction equipment and the cleaning unit of a system for preparing lithium carbonate based on the lithium extraction method provided by an embodiment of the present invention;

[0030] Figure 7 A schematic diagram of the connection relationship between the lithium extraction equipment and the backflush unit of a system for preparing lithium carbonate based on the lithium extraction method provided in an embodiment of the present invention.

[0031] In the figure: 1. Lithium electrolysis equipment; 101. Lithium electrolysis box; 102. First electrode plate; 103. Second electrode plate; 104. First pipe opening; 105. Second pipe opening; 106. Anion exchange membrane; 2. Brine circulation unit; 201. Brine raw water tank; 202. Brine feed pipe; 203. Brine feed pump; 204. Brine circulation box; 205. First brine circulation pipe; 206. Brine circulation pump; 207. First brine Circulation valve; 208, second brine circulation pipe; 209, second brine circulation valve; 210, third brine circulation pipe; 211, third brine circulation valve; 3, lithium discharge circulation unit; 301, lithium discharge circulation box; 302, first lithium discharge circulation pipe; 303, lithium discharge circulation pump; 304, first lithium discharge circulation valve; 305, second lithium discharge circulation pipe; 306, second lithium discharge circulation valve; 307, third lithium discharge circulation pipe; 308, third lithium discharge circulation pump Circulation valve; 4. Natural evaporation lithium precipitation unit; 5. Cleaning unit; 501. Pure water tank; 502. Pure water supply pipe; 503. Pure water supply pump; 504. Brine cleaning tank; 505. First brine cleaning pipe; 506. Brine cleaning pump; 507. First brine cleaning valve; 508. Second brine cleaning pipe; 509. Second brine cleaning valve; 510. Third brine cleaning pipe; 511. Third brine cleaning valve; 512. Lithium cleaning Washing box; 513, first lithium discharge cleaning pipe; 514, lithium discharge cleaning pump; 515, first lithium discharge cleaning valve; 516, second lithium discharge cleaning pipe; 517, second lithium discharge cleaning valve; 518, third lithium discharge cleaning pipe; 519, third lithium discharge cleaning valve; 6, backflush unit; 601, high-pressure blower; 602, first backflush pipe; 603, first backflush valve; 604, second backflush pipe; 605, second backflush valve; 606, backflush tank. DETAILED DESCRIPTION

[0032] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present application. Therefore, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0033] like Figure 1-7As shown, this embodiment provides a system for preparing lithium carbonate based on the lithium electrolysis method, including lithium electrolysis equipment 1, a brine circulation unit 2 and a lithium release circulation unit 3.

[0034] The lithium extraction equipment 1 includes a lithium extraction box 101 and a first electrode plate 102 and a second electrode plate 103 alternately arranged in the lithium extraction box 101. The lithium extraction box 101 is provided with a first nozzle 104 and a second nozzle 105. The two electrode plates are respectively connected to positive and negative voltages and the positive and negative voltages of the two electrode plates can be reversed. The first electrode plate 102 can electrically adsorb lithium ions in brine when connected to a negative voltage and release the adsorbed lithium ions when connected to a positive voltage. For example, the first nozzle 104 serves as a medium inlet and is arranged at the lower side of the lithium extraction box 101; the second nozzle 105 serves as a medium outlet and is arranged at the upper side of the lithium extraction box 101; the first nozzle 104 and the second nozzle 105 are respectively arranged on two opposite side walls of the lithium extraction box 101, such as one on the left wall and the other on the right wall. Exemplarily, there are N first electrode plates 102 and N+1 second electrode plates 103, and the electrode plates are parallel to each other. The N first electrode plates 102 are spaced apart in the front-to-back direction, and the N-1 second electrode plates 103 are arranged one by one between two adjacent first electrode plates 102. The remaining two second electrode plates 103 are located on the outside of the two first electrode plates 102 at the front and rear ends.

[0035] The brine circulation unit 2 is connected to the first pipe port 104 and the second pipe port 105 through a pipeline, and is used to circulate brine to the lithium electroextraction equipment 1 for lithium ion adsorption. Specifically, the brine circulation unit 2 includes a brine raw water tank 201, a brine replenishment pipe 202, a brine replenishment pump 203, a brine circulation box 204, a first brine circulation pipe 205, a brine circulation pump 206, a first brine circulation valve 207, a second brine circulation pipe 208, a second brine circulation valve 209, a third brine circulation pipe 210 and a third brine circulation valve 211. The brine raw water tank 201 is connected to the brine circulation box 204 through the brine replenishment pipe 202, the brine replenishment pump 203 is connected in series to the head end of the brine replenishment pipe 202, and the brine circulation box 204 is connected to the first brine replenishment pipe 202. The circulation pipe 205 is connected to the first pipe mouth 104, the brine circulation pump 206 is connected in series to the head end of the first brine circulation pipe 205, the first brine circulation valve 207 is connected in series to the end of the first brine circulation pipe 205, the second pipe mouth 105 is connected to the brine circulation box 204 through the second brine circulation pipe 208, the second brine circulation valve 209 is connected in series to the head end of the second brine circulation pipe 208, the head end of the third brine circulation pipe 210 is connected to the first pipe mouth 104, and the end is connected to the second brine circulation pipe 208, and the third brine circulation valve 211 is connected in series to the head end of the third water circulation pipe. Before the salt lake brine enters the main treatment process, it needs to be pretreated. A high-strength membrane process is used to treat the salt lake brine. This process can remove some impurities in the brine and adjust the composition and properties of the brine to make it more suitable for subsequent electrical adsorption operations. The pretreated brine enters the brine raw water tank 201, then enters the brine circulation tank 204 from the brine raw water tank 201, and finally enters the lithium electrolysis equipment 1 under the action of the brine circulation pump 206. Exemplarily, the first brine circulation valve 207, the second brine circulation valve 209 and the third brine circulation valve 211 are all electrically controlled valves, and the brine make-up pump 203, the brine circulation pump 206, the first brine circulation valve 207, the second brine circulation valve 209 and the third brine circulation valve 211 are all controlled by a controller. Under normal circumstances, the brine replenishment pump 203 and the brine circulation pump 206 are shut down, and the first brine circulation valve 207, the second brine circulation valve 209 and the third brine circulation valve 211 are all closed; when replenishing brine, the brine replenishment pump 203 is started; when brine is circulated, the first brine circulation valve 207 and the second brine circulation valve 209 are opened, and the brine circulation pump 206 is started; when brine is circulated, if there is a circulation problem, the third brine circulation valve 211 is opened, and the third brine circulation pipe 210 is used as a backup circulation pipeline.

[0036] The lithium discharge circulation unit 3 is connected to the first pipe port 104 and the second pipe port 105 through a pipeline, and is used to circulate the recovered liquid to the lithium electrolysis equipment 1 for lithium discharge. Specifically, the lithium discharge circulation unit 3 includes a lithium discharge circulation box 301, a first lithium discharge circulation pipe 302, a lithium discharge circulation pump 303, a first lithium discharge circulation valve 304, a second lithium discharge circulation pipe 305, a second lithium discharge circulation valve 306, a third lithium discharge circulation pipe 307 and a third lithium discharge circulation valve 308. The lithium discharge circulation box 301 is connected to the first pipe port 104 through the first lithium discharge circulation pipe 302, and the lithium discharge circulation pump 303 is connected in series to the head end of the first lithium discharge circulation pipe 302. The first lithium discharge circulation valve 304 is connected in series to the end of the first lithium discharge circulation pipe 302, the second pipe port 105 is connected to the lithium discharge circulation box 301 through the second lithium discharge circulation pipe 305, the second lithium discharge circulation valve 306 is connected in series to the head end of the second lithium discharge circulation pipe 305, the head end of the third lithium discharge circulation pipe 307 is connected to the first pipe port 104, and the end is connected to the second lithium discharge circulation pipe 305, and the third lithium discharge circulation valve 308 is connected in series to the head end of the third lithium discharge circulation pipe 307. The positive and negative poles of the electrode plates are adjusted to discharge lithium, and the lithium discharge is circulated under the action of the lithium discharge circulation pump 303 until a solution meeting the required lithium concentration is obtained. Exemplarily, the first lithium discharge circulation valve 304, the second lithium discharge circulation valve 306, and the third lithium discharge circulation valve 308 are all electronically controlled valves, and the lithium discharge circulation pump 303, the first lithium discharge circulation valve 304, the second lithium discharge circulation valve 306, and the third lithium discharge circulation valve 308 operate under the control of a controller. Under normal circumstances, the lithium discharge circulation pump 303 is shut down, and the first lithium discharge circulation valve 304, the second lithium discharge circulation valve 306 and the third lithium discharge circulation valve 308 are all closed; during lithium discharge circulation (recovery liquid circulation), the first lithium discharge circulation valve 304 and the second lithium discharge circulation valve 306 are opened, and the lithium discharge circulation pump 303 is started; during brine circulation, if a circulation problem occurs, the third lithium discharge circulation valve 308 is opened, and the third lithium discharge circulation pipe 307 is used as a backup circulation pipeline.

[0037] During use: the first electrode plate 102 is connected to a negative voltage, the second electrode plate 103 is connected to a positive voltage, and the brine circulation unit 2 circulates the salt lake brine containing lithium ions, magnesium ions, and sodium ions into the lithium electroextraction equipment 1. Under the electric field and the selection of the first electrode plate 102 made of special materials, lithium ions are electrically adsorbed on the first electrode plate 102, and magnesium ions remain in the original brine, which has very good divalent cation selectivity. In this way, the lithium-magnesium separation problem can be effectively solved. During the electrosorption process, only a small amount of sodium ions are adsorbed on the first electrode plate 102, and most of the sodium ions remain in the original brine, which has good first-order cation selectivity. In this way, the sodium-lithium ratio in the lithium-rich solution can be reduced. After the lithium adsorption process is completed, the voltages of the first electrode plate 102 and the second electrode plate 103 are swapped (the first electrode plate 102 is connected to a positive voltage and the second electrode plate 103 is connected to a negative voltage), and the lithium discharge circulation unit 3 circulates a recovery liquid containing a small amount of sodium chloride or lithium chloride to the lithium electroextraction equipment 1. The lithium ions adsorbed by the first electrode plate 102 in the previous process (electrical adsorption process) are released under the action of the electric field and enter the recovery liquid. After continuous release, when the lithium ions in the recovery liquid reach a certain level, the lithium discharge process ends. At this time, a lithium-rich liquid with a high lithium ion content is obtained in the lithium discharge circulation unit 3; lithium absorption and release are continuously performed, thereby continuously obtaining a lithium-rich liquid. The system for preparing lithium carbonate based on the lithium electrolysis method of this embodiment has good first-order cation selectivity (effectively solving the problem of relatively high sodium and lithium ratios in the lithium-rich solution obtained in the prior art), and better second-order cation selectivity (effectively solving the lithium-magnesium separation problem). It can overcome the problems of low lithium-magnesium separation rate, difficulty in desorption or extraction, and decreased efficiency of adsorption or extraction agents in chemical methods, and there is no membrane pollution problem, thus overcoming the defect of membrane separation method being limited by membrane pollution; thus realizing the industrial application of electrochemical lithium extraction.

[0038] It can be seen that the brine circulation corresponds to the lithium absorption process, and the recycling liquid circulation corresponds to the lithium discharge process. In this embodiment, the first pipe port 104 is used to input the liquid, and the second pipe port 105 is used to discharge the liquid. Therefore, lithium absorption and lithium discharge are performed alternately. In the lithium absorption process, the lithium content in the brine is generally required to be greater than 200 mg / L, and the lithium concentration in the lithium-poor brine is less than 100 mg / L. The higher the lithium content in the brine, the higher the lithium utilization rate. The lithium concentration in the lithium-rich liquid generated during the lithium discharge process is greater than 5 g / L. For brines with lower alkalinity, the lithium concentration of the lithium-rich liquid can reach 10 g / L.

[0039] In this embodiment, the system for preparing lithium carbonate based on the lithium electrolysis method also includes a natural evaporation lithium precipitation unit 4, which is connected to the lithium release circulation unit 3 through a pipeline and is used for natural evaporation, concentration, precipitation and crystallization operations, which can effectively improve the yield and purity of lithium carbonate while saving energy and floor space.

[0040] During the lithium discharge process, as the lithium ion concentration in the recovered liquid continues to increase, a lithium-rich liquid is finally obtained. The lithium-rich liquid is placed in the evaporation pool of the natural evaporation lithium precipitation unit 4, and sodium carbonate is added according to the lithium content. Natural evaporation is carried out to achieve concentration, precipitation, crystallization, concentration, precipitation and crystallization operations to obtain a lithium concentrate with high purity. Among them, the amount of sodium carbonate added is calculated based on the molar ratio of lithium to carbonate. + :CO3 2- ≥1.2; the purity of the produced lithium carbonate is ≥75%, the yield can reach more than 80%, and the lithium carbonate harvesting cycle is ≤6 months / time, while the purity of lithium carbonate produced by traditional salt gradient solar ponds is generally 60%, the yield is generally 40%, and the lithium carbonate harvesting cycle is 12 months / time.

[0041] The system for preparing lithium carbonate based on the lithium electroextraction method provided in this embodiment is used to prepare lithium carbonate through the following steps: salt lake brine is first lifted and sent to an ultrafiltration device for filtration treatment to remove most of the particulate matter in the brine, and then the pretreated brine is lifted and sent to the lithium electroextraction equipment 1; under the action of the electric field, the lithium in the brine is adsorbed on the electrode, and the brine becomes lithium-poor brine; the introduction of brine is stopped and replaced with a recovery liquid, and at the same time the voltage of the electrodes is reversed, and the lithium released from the electrodes enters the recovery liquid to form a lithium-rich solution; a certain amount of saturated sodium carbonate solution is added to the lithium-rich solution, and after sufficient mixing, it is discharged to a solar pond for natural evaporation and concentration of lithium, and the lithium carbonate in the solar pond is harvested regularly. By directly coupling the electrolithium extraction technology with the solar pond, the entire process of lithium extraction, concentration and precipitation in salt lake brine can be realized, which greatly shortens the lithium carbonate production process. Compared with the existing salt gradient solar pond process, the purity of lithium carbonate is increased by more than 25%, the lithium carbonate yield is increased by more than 40%, and the single-pond production capacity is increased by more than 1 times, which greatly improves the efficiency and production capacity of lithium extraction. It has broad application prospects and can provide technical support for the industrial operation of lithium extraction from salt lakes.

[0042] Since the first electrode plate 102 can electrically adsorb lithium ions from the brine when connected to a negative voltage and release the adsorbed lithium ions when connected to a positive voltage, the first electrode plate 102 can generally be made of lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (NMC, LiNiMnCoO2), lithium nickel cobalt aluminum oxide (NCA, LiNiCoAlO2), lithium iron phosphate (LFP, LiFePO4), or lithium manganese oxide (LMO, LiMn2O4). In this embodiment, the first electrode plate 102 is a lithium manganese oxide (LiMn2O4 / Li1-xMn2O4) or lithium iron phosphate (LiFePO4 / Li1-xFePO4) electrode plate. Since lithium absorption and release occur alternately, when the first electrode plate 102 releases lithium, it is necessary to prevent lithium ions from being adsorbed by the second electrode plate 103. Therefore, the second electrode plate 103 cannot be made of the above materials. Generally, the second electrode plate 103 is a graphite electrode plate or a lithium titanate electrode plate.

[0043] In an optional embodiment, the lithium electrolysis device 1 further includes an anion exchange membrane 106, which is disposed between the first electrode plate 102 and the second electrode plate 103. By providing the anion exchange membrane 106, the anion permeability of the brine or recovered liquid can be ensured, while the problem of short circuit between the two electrode plates due to deformation can be avoided. When the precision of the two electrode plates is sufficiently high and the deformation is controllable within a certain range, the anion exchange membrane 106 may not be provided.

[0044] In this embodiment, the system for preparing lithium carbonate based on the lithium electrolysis method also includes a cleaning unit 5, which is connected to the first pipe port 104 and the second pipe port 105 through a pipeline, and is used to circulate clean water to the lithium electrolysis equipment 1. Before each lithium absorption and release, the cleaning unit 5 is first used for cleaning, generally cleaning for 10-15 minutes or the clean water is circulated 2-3 times. Specifically, the cleaning unit 5 includes a pure water tank 501, a pure water replenishment pipe 502, a pure water replenishment pump 503, a brine cleaning tank 504, a first brine cleaning pipe 505, a brine cleaning pump 506, a first brine cleaning valve 507, a second brine cleaning pipe 508, a second brine cleaning valve 509, a third brine cleaning pipe 510, a third brine cleaning valve 511, a lithium release cleaning tank 512, a first lithium release cleaning pipe 513, a lithium release cleaning pump 514, a first lithium release cleaning valve 515, and a second lithium release cleaning pipe 516. , a second lithium discharge cleaning valve 517, a third lithium discharge cleaning pipe 518 and a third lithium discharge cleaning valve 519, the pure water tank 501 is connected to the brine cleaning tank 504 and the lithium discharge cleaning tank 512 through the pure water replenishment pipe 502, the pure water replenishment pump 503 is connected in series to the head end of the pure water replenishment pipe 502, the brine cleaning tank 504 is connected to the first pipe port 104 through the first brine cleaning pipe 505, the brine cleaning pump 506 is connected in series to the head end of the first brine cleaning pipe 505, and the first brine cleaning valve 507 is connected in series to the first brine cleaning pipe 505, the second pipe port 105 is connected to the brine cleaning tank 504 through the second brine cleaning pipe 508, the second brine cleaning valve 509 is connected in series to the head end of the second brine cleaning pipe 508, the head end of the third brine cleaning pipe 510 is connected to the first pipe port 104, and the end is connected to the second brine cleaning pipe 508, the third brine cleaning valve 511 is connected in series to the head end of the third brine cleaning pipe 510, the lithium discharge cleaning tank 512 is connected to the first pipe port 104 through the first lithium discharge cleaning pipe 513, and the lithium discharge cleaning pump 51 4 is connected in series to the head end of the first lithium discharge and cleaning pipe 513, the first lithium discharge and cleaning valve 515 is connected in series to the terminal end of the first lithium discharge and cleaning pipe 513, the second pipe port 105 is connected to the lithium discharge and cleaning tank 512 via the second lithium discharge and cleaning pipe 516, the second lithium discharge and cleaning valve 517 is connected in series to the head end of the second lithium discharge and cleaning pipe 516, the head end of the third lithium discharge and cleaning pipe 518 is connected to the first pipe port 104, and the terminal end is connected to the second lithium discharge and cleaning pipe 516, and the third lithium discharge and cleaning valve 519 is connected in series to the head end of the third lithium discharge and cleaning pipe 518. During the adsorption process, some impurities may be adsorbed on the surface of the first electrode plate 102. These impurities may affect the lithium ion concentration during the subsequent lithium discharge. The cleaning operation can effectively remove these impurities, ensuring that the lithium ion concentration during lithium discharge meets the expected requirements and ensuring the normal operation of the system. Similarly, after the lithium discharge is completed, the first electrode plate 102 is cleaned to remove impurities thereon and ensure smooth operation of the next cycle.Illustratively, the first brine cleaning valve 507, the second brine cleaning valve 509, the third brine cleaning valve 511, the first lithium release cleaning valve 515, the second lithium release cleaning valve 517, and the third lithium release cleaning valve 519 are all electrically controlled valves, and the pure water make-up pump 503, the brine cleaning pump 506, the first brine cleaning valve 507, the second brine cleaning valve 509, the lithium release cleaning pump 514, the first lithium release cleaning valve 515, and the second lithium release cleaning valve 517 operate under the control of the controller. Under normal circumstances, the pure water replenishment pump 503, the brine cleaning pump 506, and the lithium discharge cleaning pump 514 are all stopped, and the first brine cleaning valve 507, the second brine cleaning valve 509, the third brine cleaning valve 511, the first lithium discharge cleaning valve 515, the second lithium discharge cleaning valve 517, and the third lithium discharge cleaning valve 519 are all closed; when replenishing water to the brine cleaning tank 504 and the lithium discharge cleaning tank 512, the pure water replenishment pump 503 is started; when brine cleaning is in progress, the first brine cleaning valve 507, the second brine cleaning valve 509, the third brine cleaning valve 511, the first lithium discharge cleaning valve 515, the second lithium discharge cleaning valve 517, and the third lithium discharge cleaning valve 519 are all closed. Valve 509 is opened and the brine cleaning pump 506 is started; during the brine cleaning process, if a circulation abnormality occurs, the third brine cleaning valve 511 is opened and the third brine cleaning pipe 510 is used as a backup circulation pipeline; when lithium is discharged for cleaning, the first lithium discharge cleaning valve 515 and the second lithium discharge cleaning valve 517 are opened and the lithium discharge cleaning pump 514 is started; during the lithium discharge cleaning process, if a circulation abnormality occurs, the third lithium discharge cleaning valve 519 is opened and the third lithium discharge cleaning pipe 518 is used as a backup circulation pipeline.

[0045] In the present embodiment, the system for preparing lithium carbonate based on the lithium electrolysis method also includes a backflush unit 6, and the backflush unit 6 is connected to the lithium electrolysis equipment 1 by a pipeline, for carrying out gas backflush to the lithium electrolysis equipment 1. Specifically, the backflush unit 6 includes a high-pressure blower 601, a first backflush pipe 602, a first backflush valve 603, a second backflush pipe 604, a second backflush valve 605 and a backflush pool 606, and the high-pressure blower 601 is connected to the second nozzle 105 by the first backflush pipe 602, and the first backflush valve 603 is connected in series on the first backflush pipe 602, and the first nozzle 104 is connected to one end of the second backflush pipe 604, and the other end of the second backflush pipe 604 is connected to the backflush pool 606, and the second backflush valve 605 is connected in series on the second backflush pipe 604. By arranging the backflush unit 6, the liquid in the lithium electrolysis equipment 1 can be blown into the backflush pool 606, and the operations such as the lithium electrolysis equipment 1 can be repaired afterwards. For example, the first back-blow valve 603 and the second back-blow valve 605 are both electrically controlled valves, and the high-pressure blower 601, the first back-blow valve 603, and the second back-blow valve 605 all operate under the control of a controller. Normally, when the high-pressure blower 601 is shut down, the first back-blow valve 603 and the second back-blow valve 605 are closed. During back-blow operation, the first back-blow valve 603 and the second back-blow valve 605 are opened, and the high-pressure blower 601 is started.

[0046] In the description of this specification, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0048] In this application, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0049] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0050] The disclosure above provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described above. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0051] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various modifications or substitutions within the technical scope disclosed in this application, and such modifications or substitutions should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A system for preparing lithium carbonate based on lithium electrolysis, characterized in that: include: The lithium extraction device (1) comprises a lithium extraction box (101) and a first electrode plate (102) and a second electrode plate (103) which are alternately arranged in the lithium extraction box (101), wherein the lithium extraction box (101) is provided with a first pipe opening (104) and a second pipe opening (105), the two electrode plates are respectively connected to positive and negative voltages and the positive and negative voltages of the two electrode plates can be switched, wherein the first electrode plate (102) can electrically adsorb lithium ions in brine when connected to a negative voltage and release the adsorbed lithium ions when connected to a positive voltage; A brine circulation unit (2) is connected to the first pipe opening (104) and the second pipe opening (105) via a pipeline, and is used for circulating brine to the lithium electroextraction device (1) for adsorbing lithium ions; The lithium discharge circulation unit (3) is connected to the first pipe opening (104) and the second pipe opening (105) through a pipeline, and is used for circulating the recovery liquid to the lithium electroextraction equipment (1) for lithium discharge.

2. The system for preparing lithium carbonate based on the lithium electrolysis method according to claim 1, characterized in that: The system for preparing lithium carbonate based on the lithium electroextraction method also includes a natural evaporation lithium precipitation unit (4), which is connected to the lithium release circulation unit (3) through a pipeline and is used for performing natural evaporation, concentration, precipitation and crystallization operations.

3. The system for preparing lithium carbonate based on the lithium electrolysis method according to claim 1, characterized in that: The first electrode plate (102) is a lithium manganate or lithium iron phosphate electrode plate, and the second electrode plate (103) is a graphite electrode plate or a lithium titanate electrode plate.

4. The system for preparing lithium carbonate based on the lithium electrolysis method according to claim 3, characterized in that: The lithium electroextraction device (1) further comprises an anion exchange membrane (106), wherein the anion exchange membrane (106) is arranged between the first electrode plate (102) and the second electrode plate (103).

5. The system for preparing lithium carbonate based on the lithium electrolysis method according to claim 1, characterized in that: The system for preparing lithium carbonate based on the lithium electrolysis method further comprises a cleaning unit (5), wherein the cleaning unit (5) is connected to the first pipe opening (104) and the second pipe opening (105) via a pipeline and is used for circulating clean water to the lithium electrolysis equipment (1).

6. The system for preparing lithium carbonate based on the lithium electrolysis method according to claim 1, characterized in that: The brine circulation unit (2) comprises a brine raw water tank (201), a brine replenishment pipe (202), a brine replenishment pump (203), a brine circulation tank (204), a first brine circulation pipe (205), a brine circulation pump (206), a first brine circulation valve (207), a second brine circulation pipe (208) and a second brine circulation valve (209); the brine raw water tank (201) is connected to the brine circulation tank (204) via the brine replenishment pipe (202); the brine replenishment pump (203) is connected in series to the head of the brine replenishment pipe (202). end, the brine circulation box (204) is connected to the first pipe opening (104) through the first brine circulation pipe (205), the brine circulation pump (206) is connected in series to the head end of the first brine circulation pipe (205), the first brine circulation valve (207) is connected in series to the end of the first brine circulation pipe (205), the second pipe opening (105) is connected to the brine circulation box (204) through the second brine circulation pipe (208), and the second brine circulation valve (209) is connected in series to the head end of the second brine circulation pipe (208).

7. The system for preparing lithium carbonate based on the lithium electrolysis method according to claim 1, characterized in that: The lithium discharge circulation unit (3) comprises a lithium discharge circulation box (301), a first lithium discharge circulation pipe (302), a lithium discharge circulation pump (303), a first lithium discharge circulation valve (304), a second lithium discharge circulation pipe (305) and a second lithium discharge circulation valve (306); the lithium discharge circulation box (301) is connected to the first pipe opening (104) via the first lithium discharge circulation pipe (302); the lithium discharge circulation pump (303) is connected in series to the head end of the first lithium discharge circulation pipe (302); the first lithium discharge circulation valve (304) is connected in series to the end of the first lithium discharge circulation pipe (302); the second pipe opening (105) is connected to the lithium discharge circulation box (301) via the second lithium discharge circulation pipe (305); and the second lithium discharge circulation valve (306) is connected in series to the head end of the second lithium discharge circulation pipe (305).

8. The system for preparing lithium carbonate based on the lithium electrolysis method according to claim 5, characterized in that: The cleaning unit (5) comprises a pure water tank (501), a pure water replenishment pipe (502), a pure water replenishment pump (503), a brine cleaning tank (504), a first brine cleaning pipe (505), a brine cleaning pump (506), a first brine cleaning valve (507), a second brine cleaning pipe (508), a second brine cleaning valve (509), a lithium release cleaning tank (512), a first lithium release cleaning pipe (513), a lithium release cleaning pump (514), a first lithium release cleaning valve (515 ), a second lithium release cleaning pipe (516) and a second lithium release cleaning valve (517), the pure water tank (501) is connected to the brine cleaning tank (504) and the lithium release cleaning tank (512) through the pure water replenishment pipe (502), the pure water replenishment pump (503) is connected in series to the head end of the pure water replenishment pipe (502), the brine cleaning tank (504) is connected to the first pipe port (104) through the first brine cleaning pipe (505), and the brine cleaning pump (50 6) is serially connected to the head end of the first brine cleaning pipe (505), the first brine cleaning valve (507) is serially connected to the end of the first brine cleaning pipe (505), the second pipe opening (105) is connected to the brine cleaning box (504) through the second brine cleaning pipe (508), the second brine cleaning valve (509) is serially connected to the head end of the second brine cleaning pipe (508), the lithium discharge cleaning box (512) is connected to the lithium discharge cleaning pipe (51 3) is connected to the first pipe opening (104), the lithium discharge cleaning pump (514) is connected in series to the head end of the first lithium discharge cleaning pipe (513), the first lithium discharge cleaning valve (515) is connected in series to the end of the first lithium discharge cleaning pipe (513), the second pipe opening (105) is connected to the lithium discharge cleaning box (512) through the second lithium discharge cleaning pipe (516), and the second lithium discharge cleaning valve (517) is connected in series to the head end of the second lithium discharge cleaning pipe (516).

9. The system for preparing lithium carbonate based on the lithium electrolysis method according to claim 1, characterized in that: The system for preparing lithium carbonate based on the lithium electrolysis method further comprises a backflush unit (6), wherein the backflush unit (6) is connected to the lithium electrolysis equipment (1) via a pipeline and is used for backflush gas to the lithium electrolysis equipment (1).

10. The system for preparing lithium carbonate based on the lithium electrolysis method according to claim 9, characterized in that: The back-blowing unit (6) comprises a high-pressure fan (601), a first back-blowing pipe (602), a first back-blowing valve (603), a second back-blowing pipe (604), a second back-blowing valve (605) and a back-blowing pool (606); the high-pressure fan (601) is connected to the second pipe opening (105) via the first back-blowing pipe (602); the first back-blowing valve (603) is connected in series to the first back-blowing pipe (602); the first pipe opening (104) is connected to one end of the second back-blowing pipe (604); the other end of the second back-blowing pipe (604) is connected to the back-blowing pool (606); and the second back-blowing valve (605) is connected in series to the second back-blowing pipe (604).

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