Electrochemical medium recovery cleaning process for lithium extraction from salt lakes

Abstract

The application provides an electrochemical salt lake lithium extraction medium recovery and cleaning process and belongs to the technical field of salt lake lithium extraction processes. The core process logic of the application is recovery first and then cleaning. After the completion of single-round electrochemical lithium extraction electrolysis, the high-concentration brine and lithium-rich liquid medium in the pipeline and the electrolysis unit cavity are classified and recovered through pump body back suction, air pressure back pressure and gravity flow, and then cleaning is performed, so that most of the brine and lithium-rich liquid medium in the equipment is recovered and reused, lithium resource waste is eliminated, water consumption for cleaning is greatly reduced, waste medium discharge is reduced, and environmental protection treatment pressure is effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of lithium extraction technology from salt lakes, specifically relating to an electrochemical lithium extraction medium recovery and cleaning process, applicable to the recovery of electrolytic unit media and reuse of pipeline media in electrochemical deintercalation lithium extraction production lines.

[0002] Electrochemical intercalation / deintercalation is a mainstream green lithium extraction technology suitable for my country's high magnesium-to-lithium ratio salt lakes, offering advantages such as good magnesium-lithium separation, short process flow, and continuous industrial production. During the electrolysis process, a certain amount of brine and lithium-rich liquid media remain inside the electrolysis unit and pipelines after each electrolysis operation. If this portion of the media cannot be recovered, it will lead to lithium resource waste, the generation of large amounts of wastewater, and equipment scaling and clogging. Background Technology

[0003] my country's salt lakes are generally characterized by high magnesium-to-lithium ratios and low lithium concentrations. Electrochemical lithium extraction technology is suitable for such complex brine systems and is now widely used in industrial lithium production. However, existing production processes lack a systematic media recovery procedure, leading to several technical problems: First, lithium-containing media remaining after processing are either used for cleaning or directly discarded, resulting in low lithium resource utilization and high production costs. Second, direct washing without pre-recovery of media leads to high water consumption, significant waste media discharge, and poor environmental performance. Third, traditional washing methods do not provide complete cleaning coverage, allowing media to accumulate in stagnant areas, causing problems such as salt deposition, blockage, and scale buildup.

[0004] In summary, existing technologies suffer from drawbacks such as significant lithium resource depletion, severe water waste, poor environmental performance, and incomplete equipment cleaning. Based on these issues, this invention proposes an electrochemical salt lake lithium extraction medium recovery and cleaning process. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing technologies and provide an electrochemical lithium extraction medium recovery and cleaning process from salt lakes. By combining a pre-systematic medium recovery process with multi-stage cleaning procedures, it solves the technical problems of high lithium resource loss, high water consumption during washing, poor environmental performance, and incomplete equipment cleaning in existing processes, thereby improving lithium resource utilization and reducing equipment operation and maintenance costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: An electrochemical lithium extraction medium recovery and cleaning process from salt lakes specifically includes the following steps: S1. Single-cycle electrolysis operation completion: Complete a single-cycle electrochemical lithium extraction electrolysis operation. S2. Medium recovery: The brine medium remaining inside the electrolysis unit and its connecting pipelines is transported back to the brine storage tank by at least one of the following methods: pump body back suction, air pressure back, and gravity flow, and / or the lithium-rich liquid medium is transported back to the lithium-rich liquid storage tank, thus completing the medium reuse and recovery after a single round of electrolysis.

[0007] Furthermore, after the media recovery step, compressed gas is introduced into the electrolysis unit and connecting pipelines for purging. The liquid generated during purging is selectively returned to the corresponding storage tank, directly discharged, or sent to a washing tank for storage and reuse, depending on the media type and lithium ion concentration, to assist in the recovery of trace amounts of adhering media.

[0008] Furthermore, after completing the media recovery or auxiliary purging process, cleaning operations are carried out on the brine-side pipelines, lithium-rich liquid-side pipelines, and electrolysis units. The waste liquid generated after cleaning is treated differently according to the media type and lithium-ion concentration, selectively returned to the corresponding storage tank for reuse, directly discharged, or stored in the washing tank for later use, achieving refined media management.

[0009] Furthermore, after cleaning, high-pressure compressed gas is introduced for secondary purging to completely remove residual water stains and waste liquid from areas such as pipe bends and cavity depressions, and discharge them centrally through the equipment's preset drain outlet, achieving thorough cleaning and emptying of the entire equipment without any dead corners.

[0010] Furthermore, the pump body back-suction recovery mode includes two implementation methods: first, by switching the bidirectional pump operating direction, the reverse suction and return of the medium inside the equipment is achieved; second, by maintaining a constant pump body rotation and cooperating with the pipeline reversing valve group to switch the fluid flow direction, the medium return operation is completed.

[0011] Furthermore, the gas pressure return method is as follows: compressed gas is introduced into the electrolysis unit and connecting pipeline, and the gas pressure in the closed pipeline is used to push the residual medium back to the corresponding storage tank. Multiple intermittent gas venting can be used to impact the medium trapped in dead corners and improve the recovery effect.

[0012] Furthermore, the gravity flow method is as follows: the pipeline adopts an inclined layout structure, relying on the gravity of the medium itself, it naturally flows back to the storage tank located at a lower position, thereby achieving low energy consumption and low cost medium recovery.

[0013] Furthermore, multiple independent purging points are arranged on the electrolysis unit and connecting pipelines, which can simultaneously introduce compressed gas to carry out full-area purging operations, ensuring that the pipelines and cavities are purged evenly and thoroughly.

[0014] Furthermore, a dedicated air blowing channel is pre-embedded inside the electrolysis unit, allowing high-pressure gas to reach deep into the cavity and electrode gaps, areas that are difficult to cover by conventional purging, thus thoroughly removing deep-seated residual media.

[0015] Furthermore, the pipeline cleaning fluid inlet is located close to the shut-off valve, which can accurately flush the dead corners inside the valve. Furthermore, a downward-sloping bottom drain valve is installed at the lowest point of the electrolysis unit, with the valve axis forming an acute angle with the horizontal plane to ensure rapid drainage of waste liquid and water stains.

[0016] Compared with the prior art, the beneficial effects of the embodiments of the present invention are: 1. This invention adopts the core process logic of recycling first and then cleaning. Before the cleaning operation is carried out, most of the brine and lithium-rich liquid media inside the equipment are recycled through multiple recycling modes, avoiding the brine and lithium-rich liquid media remaining after the operation from participating in the cleaning, reducing the demand for cleaning water, reducing water waste, and meeting the requirements of green industrial production. 2. It avoids the direct discharge of the original retained medium with the water wash, thus improving the utilization rate of raw materials; 3. This invention adopts a pre-process media recovery and multi-stage cleaning process, which largely solves the technical problem of incomplete cleaning in traditional processes, avoids equipment failures such as salt crystallization, pipeline blockage, and electrode fouling, reduces equipment maintenance costs, extends equipment service life, and ensures long-term stable operation of the production line. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the overall process of the electrochemical lithium extraction medium recovery and cleaning process in salt lakes according to the present invention.

[0019] Explanation of reference numerals in the attached drawings: 10-Brine storage tank, 20-Lithium-rich liquid storage tank, 30-Electrolysis unit, 40-Pump body, 50-Drain outlet, 101-First connecting pipe, 102-Second connecting pipe, 103-Third connecting pipe, 104-Fourth connecting pipe. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use, are merely for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0026] The following detailed and complete description of the process steps, working principle, and implementation methods of the present invention is provided through specific embodiments. Those skilled in the art can make equivalent substitutions and adaptations to the technical solutions of the present invention without creative effort, and all such substitutions and adaptations fall within the protection scope of the present invention. This embodiment provides complete support for the technical solutions of the present invention, without omissions or deviations.

[0027] The overall process of this invention consists of two core steps, S1 and S2, and is the core technical architecture for achieving efficient recovery of media from equipment. The overall process flow can be referred to... Figure 1 The diagram shows the overall process flow.

[0028] S1. Single-round electrolysis operation termination: During normal operation of the electrochemical lithium extraction production line, lithium insertion and delithiation operations are carried out simultaneously. After completing the preset single-round lithium insertion and delithiation operations, cleaning is required to prevent media mixing. At this time, the electrolysis power supply must be cut off to terminate this round of electrolysis reaction, providing a safe and stable operating condition for subsequent media recovery and pipeline cleaning operations, and avoiding safety hazards and media performance degradation caused by live operation.

[0029] S2. Overall Recovery of Pre-treatment Medium: After the return flow path is constructed, any one or a combination of methods, such as pump body back suction, air pressure back, and gravity flow, is used to carry out overall recovery of the medium remaining in the electrolysis unit 30 and pipelines. The brine medium remaining in the electrolysis unit 30 and pipelines can be recovered separately and returned to the brine storage tank 10. The lithium-rich liquid medium can be recovered separately and returned to the lithium-rich liquid storage tank 20. Alternatively, both types of media can be recovered and returned simultaneously, maximizing the resource reuse of the medium after a single round of electrolysis. The overall recovery process flow is as follows: Figure 1 .

[0030] Circulation return path construction: Based on the piping configuration of the on-site equipment, select and construct a suitable medium circulation return path to adapt to different production equipment operating conditions. Format 1 (Existing Operational Circulation Pipeline Reverse Recovery Mode): No new pipelines are required; the existing operational connection pipelines between the brine storage tank 10, the lithium-rich liquid storage tank 20, and the electrolysis unit 30 are directly reused. During normal electrolysis operations, brine flows from the brine storage tank 10 into the electrolysis unit 30 through the first connecting pipeline 101. After the lithium intercalation reaction is completed in the electrolysis unit 30, the remaining brine flows back to the brine storage tank 10 through the second connecting pipeline 102, entering the next cycle. The lithium-rich liquid flows from the lithium-rich liquid storage tank 20 into the electrolysis unit 30 through the third connecting pipeline 103. After the delithiation reaction is completed in the electrolysis unit 30, the liquid flows back to the lithium-rich liquid storage tank 20 through the fourth connecting pipeline 104, entering the next cycle. After a single round of electrolysis is completed, the flow direction of the pipeline fluid is switched by bidirectional pump reversing suction or pipeline reversing valve group to achieve the return and recovery of brine and lithium-rich liquid inside the equipment. This is compatible with most conventional production lines and has strong versatility.

[0031] Form 2 (with a third independent recycling pipeline): For equipment equipped with a dedicated recycling pipeline, an independent recycling pipeline is added to the existing dual-pipeline circulation between the brine storage tank 10 and the electrolysis unit 30, and between the lithium-rich liquid storage tank 20 and the electrolysis unit 30.

[0032] After a single round of electrolysis is completed, the original circulation pipeline is disconnected and a dedicated recovery pipeline is activated to return the electrolysis unit 30 and the high-concentration brine medium and lithium-rich liquid medium remaining in the pipeline to the corresponding brine storage tank 10 and lithium-rich liquid storage tank 20, respectively, making the structure simpler.

[0033] Note that during reflux, the vent valve at the outlet of the electrolytic cell must be opened to ensure atmospheric pressure and smooth reflux.

[0034] After completing the aforementioned pre-processing media recovery steps, a primary purging process is selectively initiated. Compressed gas is introduced into the electrolysis unit 30 and its connecting pipes on both sides. The gas pressure forces the trace amounts of residual media adhering to the pipes and cavities back along a pre-defined return path to the corresponding brine storage tank 10 or lithium-rich liquid storage tank 20. This process assists in recovering trace amounts of media adhering to the inner wall of the equipment, compensating for the shortcomings of simple fluid reflux recovery, further improving the media recovery rate, and simultaneously initially drying the liquid film on the inner wall of the pipes, reducing media adhesion and retention. In other embodiments, the trace amounts of residual media can also be directly discharged through the bottom of the electrolysis unit 30 or the pre-defined drain port 50 in the pipes. This process is not essential and can be selected as needed, such as when there is a large amount of residual media.

[0035] After completing the pre-treatment media recovery process, or as needed, the aforementioned primary purging process, the cleaning operation is initiated. This invention employs an independent zoned cleaning mode for the brine side and the lithium-rich liquid side, respectively, by introducing clean water or purified water as the cleaning fluid into the brine side pipeline and the lithium-rich liquid side pipeline. After the cleaning operation is completed, the generated waste media is classified and treated accordingly: if the cleaning media has a high lithium-ion concentration and its purity meets production requirements, it is returned to the corresponding storage tank for resource recovery; if the lithium-ion concentration is extremely low and has no recovery value, it is directly discharged; if centralized and unified treatment is required, it can be sent to a dedicated washing tank for storage and backup, achieving refined and differentiated management of waste media. In other embodiments, the cleaning fluid can be other liquids containing trace elements, as long as it can achieve the cleaning function.

[0036] After completing the above-mentioned zoned cleaning process, a secondary compressed gas purging operation is initiated. Compared to the primary purging, this purging operation specifically targets areas where liquids can remain, such as pipe bends, cavity recesses, and dead corners in pipe connections. Through powerful purging with high-pressure gas, the trace amounts of residual liquid, water stains, and cleaning media in these areas are completely removed and discharged through the bottom of the electrolysis unit 30 or the pre-set drain outlet 50 in the pipeline. This thoroughly eliminates the problem of media retention in dead corners of the equipment and prevents potential equipment malfunctions such as salt crystallization and scale buildup.

[0037] The three media reflux methods are described in detail below: The pump body back-suction mode of this invention includes two equivalent and interchangeable implementation schemes, which can be adapted to production conditions with different pump body configurations: Method 1 (Bidirectional Pump Reversal and Recirculation): The pipeline system is equipped with a bidirectional pump. The operating direction of the bidirectional pump is switched by the control system, which changes the direction of fluid delivery in the pipeline. The original feed flow direction is switched to the back suction flow direction, realizing the reverse suction and recirculation of the medium stored in the electrolysis unit 30 and the connecting pipeline. It has a simple structure, convenient control, and strong adaptability.

[0038] Method 2 (Constant directional pump + reversing valve assembly for backflow): This method uses a conventional unidirectional pump with a constant direction of rotation. No changes to the pump's inherent parameters are required. By switching the on / off state of the pipeline using a matching reversing valve assembly, the fluid flow direction can be changed, achieving reverse backflow of the medium. This method eliminates the need for a dedicated bidirectional pump and can be directly adapted to traditional unidirectional pump pipeline systems, resulting in lower equipment modification costs and greater versatility.

[0039] The pneumatic backflow mode continuously supplies compressed gas into the electrolysis unit 30 cavity and its connecting pipes on both sides. Utilizing the positive pressure of the gas generated within the sealed pipeline, the remaining brine and lithium-rich liquid media are propelled back along the return flow path to the corresponding brine storage tank 10 and lithium-rich liquid storage tank 20. Simultaneously, the compressed gas can be intermittently introduced multiple times, using pressure fluctuations to impact the remaining media in dead zones of the pipeline, avoiding localized media accumulation caused by constant pressure and significantly improving the media recovery effect of the pneumatic purging.

[0040] Gravity reflux primarily involves laying the pipeline at an angle, allowing the medium to naturally flow back to a storage tank positioned at a lower level, relying on the medium's own gravity. This achieves zero-energy, low-cost medium recovery. In other embodiments, the electrolysis unit 30 itself can also be laid at an angle to provide energy for the natural reflux.

[0041] Multiple independent purging points can be arranged on the electrolysis unit and connecting pipelines, and compressed gas can be introduced simultaneously to carry out full-area purging operations, ensuring that the pipelines and cavities are purged evenly and thoroughly.

[0042] Preferably, a dedicated air blowing channel is pre-embedded inside the electrolysis unit, allowing high-pressure gas to reach deep into the cavity, electrode gaps, and other dead-angle areas that are difficult to cover by conventional purging, thus thoroughly removing deep residual media.

[0043] Preferably, the pipeline cleaning fluid inlet is located close to the shut-off valve, which can accurately flush the dead corners inside the valve.

[0044] Preferably, a bottom drain valve is installed at the lowest point of the electrolysis unit, tilted downwards, with the valve axis forming an acute angle with the horizontal plane to ensure rapid drainage of waste liquid and water stains.

[0045] Compared with existing technologies, the beneficial effects of the embodiments of the present invention are: 1. This invention adopts the core process logic of recycling first and then cleaning. Before the cleaning operation is carried out, most of the brine and lithium-rich liquid media inside the equipment are recycled through multiple recycling modes, avoiding the brine and lithium-rich liquid media remaining after the operation from participating in the cleaning, reducing the demand for cleaning water, reducing water waste, and meeting the requirements of green industrial production. 2. It avoids the direct discharge of the original retained medium with the water wash, thus improving the utilization rate of raw materials; 3. This invention adopts a pre-process media recovery and multi-stage cleaning process, which largely solves the technical problem of incomplete cleaning in traditional processes, avoids equipment failures such as salt crystallization, pipeline blockage, and electrode fouling, reduces equipment maintenance costs, extends equipment service life, and ensures long-term stable operation of the production line.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for recovering and cleaning media in electrochemical lithium extraction from salt lakes, characterized in that, Includes the following steps: S1. Single-cycle electrolysis operation completion: Complete a single-cycle electrochemical lithium extraction electrolysis operation. S2, Medium recovery: The brine medium remaining inside the electrolysis unit (30) and its connecting pipeline is transported back to the brine storage tank (10) by at least one of the following methods: pump body (40) back suction, air pressure back, and gravity flow, and / or the lithium-rich liquid medium is transported back to the lithium-rich liquid storage tank (20) to complete the medium reuse and recovery after a single round of electrolysis.

2. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 1, characterized in that, It also includes the purging process: After the media recovery step, compressed gas is introduced into the electrolysis unit (30) and connecting pipeline for purging. The liquid generated during purging is selectively returned to the corresponding storage tank, directly discharged, or sent to the washing tank for storage and reuse, depending on the type of media.

3. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 1 or 2, characterized in that, Perform the cleaning process: After the media recovery is completed, or after the purging process described in claim 2 is completed, cleaning solution is introduced into the brine side and lithium-rich liquid side of the electrolysis unit (30) and its connecting pipeline respectively for cleaning; the liquid generated during cleaning is selectively returned to the corresponding storage tank, directly discharged or sent to the washing tank for storage and reuse, depending on the type of media.

4. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 3, characterized in that, After cleaning, compressed gas is introduced for purging, and the liquid remaining in the liquid retention area of ​​the electrolysis unit (30) and its connecting pipeline is discharged from the drain port (50) located in the electrolysis unit (30) or the connecting pipeline.

5. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 1, characterized in that, The pump body back suction includes two implementation methods: Method 1: Use a bidirectional pump to switch the operating direction to achieve reverse suction and return of the medium; Method 2: The pump body maintains a constant rotation direction, and in conjunction with the reversing valve group, the flow direction of the fluid in the pipeline is changed to achieve medium return.

6. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 1, characterized in that, The gas pressure return method is as follows: compressed gas is introduced into the electrolysis unit (30) and its connecting pipeline, and the gas pressure is used to push the internal medium back to the corresponding storage tank. The compressed gas can be introduced intermittently multiple times.

7. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 1, characterized in that, The gravity flow method includes: the connecting pipeline adopts an inclined layout structure, relying on the gravity of the medium itself to naturally flow back to the corresponding storage tank.

8. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 4, characterized in that, The electrolysis unit (30) and its connecting pipeline are equipped with multiple purging points, which can realize the purging operation by introducing compressed gas at multiple points.

9. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 8, characterized in that, The electrolysis unit (30) has a pre-embedded dedicated air blowing channel inside.

10. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 3, characterized in that, The cleaning fluid inlet port is located near the shut-off valve on the pipeline.

11. The electrochemical salt lake lithium extraction medium recovery and cleaning process according to claim 3, characterized in that, The bottom valve at the lowest geometric point of the electrolysis unit (30) is arranged at an angle downwards, and the valve axis forms an acute angle with the horizontal plane.

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