System and method for extracting lithium from seawater and coupling to prepare deuterium gas

Abstract

The invention provides a system and a method for extracting lithium from seawater and coupling to prepare deuterium gas. The system for extracting lithium from seawater and coupling to prepare deuterium gas comprises a desalination treatment part, an adsorption part, a concentration part, a filtering part and an evaporation electrolysis part which are sequentially connected in series. The desalting treatment part can be used for desalting seawater to produce strong brine; the adsorption part can adsorb and desorb strong brine to produce lithium-rich water. And the concentration part can be used for concentrating the lithium-rich water. And the filtering part can filter the lithium-rich water. The evaporation electrolysis part can evaporate the lithium-rich water to produce lithium ion crystals and crude heavy water, and then electrolyze the crude heavy water to obtain deuterium gas. The output end and the input end of the desalting treatment part are connected to enable strong brine to flow back, and the desalting treatment part is also connected with the backwashing water input end of the filtering part to enable the strong brine to backwash the filtering part. The backwashing water output end of the filtering part is connected with the input end of the desalting treatment part, so that backwashing water flows back. The utilization efficiency is improved, and the resource consumption is reduced.

Description

Technical Field

[0001] This invention belongs to the field of nuclear fusion fuel extraction technology, and specifically relates to a system and method for lithium extraction from seawater coupled with deuterium production. Background Art

[0002] Controlled nuclear fusion is considered humanity's ultimate energy dream. Deuterium-tritium is the most likely form of fuel for fusion to be realized first. Deuterium can be produced by electrolyzing heavy water, while tritium can be produced by bombarding lithium with neutrons generated from the deuterium-tritium reaction, resulting in lithium fission. Therefore, heavy water and lithium are important raw materials for the preparation of deuterium-tritium.

[0003] Globally, seawater contains approximately 230 billion tons of lithium, more than 8,000 times the amount found on land, and is unaffected by geopolitics. However, the lithium-ion concentration in seawater is only 0.18-0.20 mg / L. Heavy water concentration in seawater is approximately 155 ppm (1 / 6500). Current methods for lithium extraction from seawater generally involve adsorption, while heavy water extraction typically involves evaporation and electrolysis. However, these methods are inefficient and energy-intensive. Even after processing large quantities of seawater, only small amounts of lithium and heavy water can be extracted. Furthermore, the treated seawater still contains significant amounts of heavy water and lithium, making the production of deuterium and tritium resource-intensive.

[0004] Therefore, existing methods for preparing deuterium-tritium are inefficient and costly. Summary of the Invention

[0005] To address the above problems, this invention proposes a system and method for lithium extraction from seawater coupled with deuterium gas production. The system for lithium extraction from seawater coupled with deuterium gas production includes:

[0006] A desalination unit capable of desalinizing seawater and producing concentrated brine.

[0007] The adsorption unit has its input end connected to the output end of the desalination unit. The adsorption unit can sequentially adsorb and desorb concentrated brine to produce lithium-rich water.

[0008] The concentration section has its input end connected to the output end of the adsorption section, and the concentration section can concentrate lithium-rich water.

[0009] The filter section has its input end connected to the output end of the concentration section. The filter section can filter lithium-rich water to remove impurities.

[0010] The evaporation electrolysis unit has its input end connected to the output end of the filtration unit. The evaporation electrolysis unit can evaporate lithium-rich water and precipitate solid crystals of lithium ions, producing crude heavy water. The evaporation electrolysis unit can also electrolyze the crude heavy water to obtain deuterium gas.

[0011] The output and input ends of the desalination unit are connected to allow for the reflux treatment of a portion of the concentrated brine.

[0012] The output end of the desalination unit is connected to the input end of the backwash water of the filtration unit, so that some concentrated brine can backwash the filtration unit.

[0013] The output end of the backwash water of the filtration unit is also connected to the input end of the desalination unit to perform backwash water recirculation treatment.

[0014] In some specific embodiments, the desalination treatment unit includes:

[0015] A nanofiltration device capable of removing divalent ions from seawater to produce primary water containing monovalent ions;

[0016] A reverse osmosis unit, the input end of which is connected to the output end of the nanofiltration unit, is capable of desalinizing primary permeate to produce concentrated brine.

[0017] In some specific embodiments, the output of the reverse osmosis device is connected to the input of the nanofiltration device to reflux a portion of the produced concentrated brine.

[0018] In some specific embodiments, the input end of the nanofiltration device is connected to a pretreatment device that can perform preliminary filtration of seawater to remove impurities from the seawater.

[0019] In some specific embodiments, the output end of the reverse osmosis device is connected to the input end of the backwash water of the filter section, so as to backwash the filter section with a portion of the produced concentrated brine;

[0020] The backwash water output of the filter section is connected to the input of the pretreatment device so that the backwash water can carry impurities backflow.

[0021] In some specific embodiments, the evaporation electrolysis unit includes:

[0022] An evaporation crystallization apparatus, wherein the input end of the evaporation crystallization apparatus is connected to the output end of the filter section to produce solid crystals of lithium ions and coarse heavy water;

[0023] An electrolysis device, the input end of which is connected to the output end of the evaporation and crystallization device, to produce deuterium gas.

[0024] In some specific embodiments, the electrolysis apparatus includes:

[0025] A primary electrolysis mechanism is provided, the input end of which is connected to the output end of the evaporation and crystallization device. The primary electrolysis mechanism can electrolyze crude heavy water to obtain refined heavy water by electrolyzing hydrogen and oxygen.

[0026] The secondary electrolysis mechanism has its input end connected to the output end of the primary electrolysis mechanism. The secondary electrolysis mechanism can electrolyze the refined heavy water to produce deuterium gas.

[0027] In some specific embodiments, the concentration unit is a membrane distillation device or an electrodialysis device.

[0028] In some specific embodiments, the filtration unit is an ultrafiltration device or a microfiltration device.

[0029] A method for producing deuterium gas from seawater using lithium extraction coupled with deuterium gas production, based on the same concept, employs the system for producing deuterium gas from seawater using lithium extraction coupled with deuterium gas production as described in any of the above specific embodiments, and includes the following steps:

[0030] The seawater is desalinated in the desalination unit to produce concentrated brine; some of the concentrated brine is sent to the adsorption unit, and some of the concentrated brine is sent to the filtration unit. At the same time, some of the concentrated brine is refluxed in the desalination unit.

[0031] Lithium-rich water is produced by adsorbing or desorbing concentrated brine in the adsorption section; the lithium-rich water is then transported to the concentration section.

[0032] The lithium-rich water is concentrated through the concentration section; the concentrated lithium-rich water is then transported to the filtration section.

[0033] Impurities in lithium-rich water are removed by the filtration section; at the same time, the filtration section is backwashed by the concentrated brine supplied to it, and the backwashed concentrated brine is returned to the desalination section.

[0034] The lithium-rich water is evaporated in the evaporation electrolysis section to produce solid lithium-ion crystals and crude heavy water; then the crude heavy water is electrolyzed in the evaporation electrolysis section to obtain deuterium gas.

[0035] The present invention relates to a system for lithium extraction from seawater coupled with deuterium gas production. Seawater is desalinated in a desalination unit to produce concentrated brine. This concentrated brine then passes through an adsorption unit, a concentration unit, and a filtration unit to obtain concentrated lithium-rich water with impurities removed. After evaporation and electrolysis, crude heavy water and lithium ion solid crystals are obtained. Deuterium gas is then produced by electrolysis of the crude heavy water. Furthermore, a portion of the concentrated brine produced in the desalination unit can be refluxed within the unit, and another portion can be backwashed in the filtration unit before being refluxed back to the desalination unit. This significantly improves the utilization efficiency of the desalinated seawater concentrated brine, enabling efficient extraction of lithium and heavy water from seawater, thereby increasing the production efficiency of deuterium and tritium, reducing the resources consumed in deuterium and tritium production, decreasing the overall system throughput and scale, and lowering resource consumption.

[0036] The method for producing deuterium gas by coupling lithium extraction from seawater according to the present invention adopts the system for producing deuterium gas by coupling lithium extraction from seawater described above, so it has the same beneficial effects as the system for producing deuterium gas by coupling lithium extraction from seawater described above, and will not be repeated here.

[0037] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 A schematic diagram of a system for coupling deuterium production from seawater lithium extraction is shown in an embodiment of the present invention.

[0040] In the diagram, 100 is the desalination unit; 110 is the nanofiltration unit; 120 is the reverse osmosis unit; 130 is the pretreatment unit; 200 is the adsorption unit; 300 is the concentration unit; 400 is the filtration unit; 500 is the evaporation and electrolysis unit; 510 is the evaporation and crystallization unit; 520 is the electrolysis unit; 521 is the primary electrolysis unit; and 522 is the secondary electrolysis unit. Detailed Implementation

[0041] 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, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Reference Figure 1 This invention provides a system for lithium extraction from seawater coupled with deuterium gas production, comprising: a desalination unit 100, an adsorption unit 200, a concentration unit 300, a filtration unit 400, and an evaporation and electrolysis unit 500. Seawater is transported to the desalination unit 100 for desalination treatment, thereby producing concentrated brine. The input end of the adsorption unit 200 is connected to the output end of the desalination unit 100, allowing the produced concentrated brine to be transported from the desalination unit 100 to the adsorption unit 200. The adsorption unit 200 sequentially adsorbs and desorbs the concentrated brine, thereby producing lithium-rich water and increasing the lithium-ion concentration. The input end of the concentration unit 300 is connected to the output end of the adsorption unit 200, allowing the produced lithium-rich water to be transported from the adsorption unit 200 to the concentration unit 300. The concentration unit 300 performs preliminary concentration treatment on the lithium-rich water, thereby further increasing the concentration of lithium ions and heavy water. The input end of the filtration unit 400 is connected to the output end of the concentration unit 300. The filtration unit 400 removes suspended solids and other impurities from the lithium-rich water, thereby improving the purity of lithium ions. The input end of the evaporation electrolysis unit 500 is connected to the output end of the filtration unit 400. The evaporation electrolysis unit 500 further evaporates the lithium-rich water. At the same time, sodium carbonate can be added to generate lithium carbonate crystals and produce crude heavy water. The crude heavy water produced can be electrolyzed by the evaporation electrolysis unit to generate refined heavy water and deuterium gas. Through multiple concentrations and purifications, the concentrations of lithium ions and heavy water are continuously increased, ultimately producing lithium carbonate crystals and deuterium gas. This achieves comprehensive utilization of concentrated seawater desalination brine, reducing wastewater discharge while obtaining high-value products such as lithium and deuterium gas.

[0043] Furthermore, the concentrated water output end of the desalination unit 100 is connected to the raw water input end, allowing a portion of the concentrated brine produced by the desalination unit 100 to flow back from the output end to the input end. This not only increases the influent flow rate of the desalination unit 100, extends the residence time, and improves the water recovery rate, but also increases the concentration factor of the concentrated brine, improves the lithium ion adsorption efficiency, and reduces the flow load and equipment size of the adsorption unit 200. Simultaneously, the concentrated water output end of the desalination unit 100 is also connected to the backwash water input end of the filtration unit 400, enabling a portion of the concentrated brine produced by the desalination unit 100 to be transported from the desalination unit 100 to the filtration unit 400 for backwashing the filter membrane of the filtration unit 400. The backwash water output of the filtration unit 400 is also connected to the raw water input of the desalination unit 100, so that the concentrated brine discharged from the backwash flows back to the desalination unit 100 for comprehensive utilization of backwash wastewater. This reduces waste liquid discharge, improves the production efficiency of lithium and deuterium, and also reduces the processing volume and scale of subsequent devices, thus reducing resource consumption.

[0044] Furthermore, the adsorption unit 200 includes adsorption towers, switching valves, and a regeneration device. Multiple adsorption towers are used; some towers adsorb concentrated brine, retaining most lithium ions and discharging lithium-poor brine with low lithium ion content. Other towers desorb lithium ions by adding desorbents such as hydrochloric acid or citric acid, producing lithium-rich brine. The multiple adsorption towers are connected by switching valves and pipelines, rotating between adsorption and desorption to ensure continuous operation.

[0045] Furthermore, there are 2 to 4 adsorption towers, connected by switching valves and pipelines, which alternately perform adsorption or desorption. Two adsorption towers can basically meet the requirements for continuous operation, while four adsorption towers can fully meet the requirements for continuous operation. If there are more than four adsorption towers, it may result in excessive equipment investment and wasted costs.

[0046] In some specific embodiments of the present invention, the desalination unit 100 includes a nanofiltration device 110 and a reverse osmosis device 120. The nanofiltration device 110 can remove calcium from seawater... 2+ Mg 2+ SO4 2- By retaining divalent ions in the concentrated brine and discharging them externally, the scaling tendency of downstream units is reduced. Simultaneously, the recovery rate of the reverse osmosis unit 120 is improved, and interference from calcium and magnesium ions on the evaporation process of the evaporation electrolysis section 500 is avoided, ensuring the purity of lithium ions. The primary product water of the nanofiltration unit 110 mainly contains Na+. + Li + Cl - OH -Monovalent ions are present. The input end of the reverse osmosis unit 120 is connected to the permeate output end of the nanofiltration unit 110, so that the primary permeate produced by the nanofiltration unit 110 is transported into the reverse osmosis unit 120. The reverse osmosis unit 120 performs deep desalination treatment on the primary permeate, producing high-quality freshwater and concentrated brine that is 2 to 3 times stronger, providing raw materials for the production of lithium and heavy water. Compared with the 40% recovery rate of traditional seawater desalination, the above process can increase the freshwater recovery rate to over 70% and the total lithium recovery rate to over 70%.

[0047] Furthermore, the nanofiltration unit 110 includes a security filter, a nanofiltration membrane stack, a high-pressure pump, and an energy recovery assembly. The security filter removes fine particles, colloids, microorganisms, etc., from seawater, thereby protecting the membrane stack. The nanofiltration unit 110 can remove Ca... 2+ Mg 2+ SO4 2- Organic matter is retained in the concentrated brine and discharged, allowing the freshwater side to produce primary permeate mainly containing monovalent ions. A high-pressure pump powers the membrane separation process. An energy recovery unit recovers the pressure of the high-pressure concentrated seawater for initial pressurization of the raw water, thereby reducing energy consumption and cost in seawater desalination.

[0048] Furthermore, the reverse osmosis unit 120 includes a security filter, a reverse osmosis membrane stack, a high-pressure pump, and an energy recovery unit. The security filter removes impurities such as silt and suspended solids from the primary product water, thus protecting the membrane stack. The reverse osmosis membrane has extremely high selectivity, allowing only the solvent to pass through and not the solute, effectively removing various salts and other impurities from the primary product water. This allows for the production of high-purity freshwater on the freshwater side, while the concentrate side produces concentrated brine that is 2 to 3 times more concentrated, thereby improving seawater utilization. The high-pressure pump provides power for the membrane separation process. The energy recovery unit recovers the pressure of the high-pressure concentrated seawater to initially pressurize the primary product water, thereby reducing the energy consumption and cost of seawater desalination.

[0049] Furthermore, the high-pressure pump of the reverse osmosis unit 120 is a variable frequency pump, thereby improving membrane separation efficiency and reducing energy consumption.

[0050] Furthermore, the reverse osmosis unit 120 includes a reverse osmosis membrane stack comprising multiple reverse osmosis membrane modules arranged in a mixed configuration, thereby improving the concentration effect.

[0051] Furthermore, the concentrated water output end of the reverse osmosis unit 120 is connected to the raw water input end, so that some of the concentrated brine produced by the reverse osmosis unit 120 can be returned to the input end of the reverse osmosis unit 120 in order to improve the system recovery rate.

[0052] In some specific embodiments of the present invention, the concentrated water output end of the reverse osmosis device 120 is connected to the raw water input end of the nanofiltration device 110, so that some of the concentrated brine produced by the reverse osmosis device 120 can also be returned to the input end of the nanofiltration device 110 to perform reflux treatment on the produced concentrated brine, thereby further improving the system recovery rate and increasing the concentration factor.

[0053] In some specific embodiments of the present invention, the input end of the nanofiltration device 110 is connected to a pretreatment device 130, which removes algae, silt, suspended solids, colloids, etc. from seawater to meet the inlet water requirements of the nanofiltration device 110.

[0054] Furthermore, the pretreatment device 130 includes a seawater pump, flocculation, sedimentation, sand and carbon filtration, microfiltration, and ultrafiltration equipment arranged in series.

[0055] In some specific embodiments of the present invention, the output end of the reverse osmosis device 120 is connected to the input end of the backwash water of the filtration section 400, so that a portion of the concentrated brine produced by the reverse osmosis device 120 can reach the filtration section 400 to backwash the filtration section 400, thereby ensuring the filtration performance of the filter membrane in the filtration section 400. The output end of the backwash water of the filtration section 400 is connected to the input end of the pretreatment device 130 for reuse of the backwash water carrying impurities. Backwashing the ultrafiltration membrane with concentrated brine can reduce the amount of external wastewater and improve the recovery rate of concentrated brine.

[0056] In some specific embodiments of the present invention, the evaporation electrolysis unit 500 includes an evaporation crystallization device 510 and an electrolysis device 520. The input end of the evaporation crystallization device 510 is connected to the output end of the filtration unit 400, so that lithium-rich water filtered by the filtration unit 400 is transported to the evaporation crystallization device 510 for evaporation. Simultaneously with evaporation, sodium carbonate is added to the evaporation crystallization device 510, causing carbonate ions to react with Li+ in the lithium-rich water to form slightly water-soluble lithium carbonate. Through precipitation and drying, a lithium carbonate powder product with a purity of over 99.2% can be obtained. The mother liquor after separating lithium carbonate mainly contains Na. + Cl - H2O and D2O are further evaporated until sodium chloride saturation is achieved, resulting in sodium chloride solid crystals. Since H2O has a lower boiling point than D2O, crude heavy water rich in D2O can be obtained at the end of the evaporation process. The input of the electrolysis unit 520 is connected to the output of the evaporation crystallization unit 510, allowing the crude heavy water produced by the evaporation crystallization unit 510 to be transported to the electrolysis unit 520 for further electrolysis, producing refined heavy water and deuterium gas.

[0057] Furthermore, the electrolysis device 520 is a two-stage electrolysis device, comprising a primary electrolysis unit 521 and a secondary electrolysis unit 522. Under the action of the primary electrolysis unit 521, the water in the crude heavy water is electrolyzed into hydrogen and oxygen, thereby increasing the concentration of the heavy water and forming refined heavy water. The refined heavy water enters the secondary electrolysis unit 522, where it is further electrolyzed into deuterium and oxygen. The two electrolysis processes are carried out sequentially, and combined with the purification facilities in the electrolysis unit, deuterium gas with a purity of over 99.75% can ultimately be generated.

[0058] Furthermore, the evaporation crystallization apparatus 510 includes an evaporator, a circulating pump, a dosing device, and a solid drying device to complete the evaporation and concentration of the feed liquid and the precipitation and separation of lithium ions.

[0059] In some specific embodiments of the present invention, the concentration unit 300 is a membrane distillation device, which is equipped with a hydrophobic microporous membrane inside. When lithium-rich water enters the concentration unit 300, the vapor pressure difference generated by the temperature difference across the hydrophobic microporous membrane serves as the driving force to achieve the separation of solute and solvent. This device can effectively utilize solar thermal, geothermal, and low-temperature waste heat to further concentrate lithium-rich water while producing fresh water, thereby improving the seawater recovery rate and increasing the concentration of lithium and heavy water in the lithium-rich water.

[0060] Furthermore, the concentration unit 300 can also be an electrodialysis device, which can also meet the concentration treatment needs of lithium-rich water.

[0061] In some specific embodiments of the present invention, the filtration unit 400 is an ultrafiltration device, the purpose of which is to remove suspended impurities that are enriched during the enrichment process of concentrated brine, so as to ensure the purity of the lithium carbonate product produced subsequently.

[0062] Furthermore, the filtration unit 400 can also be a microfiltration device. If the purity requirement of the subsequently produced lithium carbonate is not high according to user needs, a microfiltration device can be used to reduce construction and operation costs.

[0063] The present invention also provides a method for producing deuterium gas from seawater coupled with lithium extraction, employing the system for producing deuterium gas from seawater coupled with lithium extraction as described in any of the above specific embodiments, comprising the following steps:

[0064] Seawater is desalinated in the desalination unit 100 to produce concentrated brine. A portion of the concentrated brine is fed to the adsorption unit 200, and then to the filtration unit 400. Simultaneously, a portion of the concentrated brine is refluxed within the desalination unit 100. The concentrated brine is then subjected to adsorption and desorption treatment in the adsorption unit 200 to produce lithium-rich water. The lithium-rich water is fed to the concentration unit 300. The lithium-rich water is concentrated in the concentration unit 300. The concentrated lithium-rich water is fed to the filtration unit 400. Impurities in the lithium-rich water are removed in the filtration unit 400. Simultaneously, the filtration unit 400 is backwashed with the concentrated brine fed to it, and the backwash water is refluxed back to the desalination unit 100. The lithium-rich water is evaporated in the evaporation electrolysis unit 500, and sodium carbonate is added to precipitate lithium carbonate, producing coarse heavy water. The coarse heavy water is then electrolyzed in the evaporation electrolysis unit 500 to obtain deuterium gas.

[0065] Specifically, seawater is pumped in and transported to the pretreatment unit 130, where impurities such as silt, suspended solids, and colloids are removed through flocculation, sedimentation, sand and carbon filtration, microfiltration, and ultrafiltration.

[0066] The pretreated seawater is then transported to nanofiltration unit 110, where Ca... 2+ Mg 2+ SO4 2- Divalent ions are retained in concentrated brine by the nanofiltration membrane and are expelled, while Na+ ions are retained in the concentrated brine and expelled. + Li + Cl - OH - Monovalent ions pass through the nanofiltration membrane and enter the primary permeate water.

[0067] The primary permeate is transported to the reverse osmosis unit 120 for deep desalination. High-quality freshwater and concentrated brine (2 to 3 times stronger) are produced by using multi-stage membrane modules, concentrate recirculation, and variable frequency pumps.

[0068] Part of the concentrated brine is returned to the raw water input of the nanofiltration unit 110, another part of the concentrated brine is returned to the raw water input of the reverse osmosis unit 120, and a portion of the concentrated brine is used for backwashing of the ultrafiltration unit. The remaining concentrated brine is transported to the adsorption tower, where lithium-rich water is produced through adsorption and desorption operations and lithium-poor water is discharged.

[0069] The lithium-rich water is transported to a membrane distillation unit, where the vapor pressure difference generated by the temperature difference across the hydrophobic microporous membrane serves as the driving force to separate the solute and solvent, producing fresh water and further concentrating the lithium-rich water.

[0070] The further concentrated lithium-rich water is then fed into the ultrafiltration unit of the filtration section 400 to remove suspended impurities. Simultaneously, the filtration section 400 returns the backwash water to the pretreatment unit 130.

[0071] The filtered lithium-rich water is transported to the evaporation crystallization device 510 for evaporation to obtain fresh water. Sodium carbonate is added to the evaporation crystallization device 510, and carbonate ions react with lithium ions to generate lithium carbonate that is slightly soluble in water. Lithium carbonate product powder is obtained through precipitation and drying. After the water and heavy water are completely evaporated and condensed, coarse heavy water is formed.

[0072] The coarse heavy water is transported to the primary electrolysis unit 521, where it is electrolyzed into hydrogen and oxygen and either discharged or reused, so that the heavy water concentration meets the standard and forms refined heavy water.

[0073] The purified heavy water is transported to the secondary electrolysis unit 522, where it is electrolyzed into deuterium and oxygen. The oxygen is either discharged or reused, thus obtaining deuterium with the required purity.

[0074] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for coupling lithium extraction from seawater with deuterium gas production, characterized in that, include: A desalination unit capable of desalinizing seawater and producing concentrated brine. The adsorption unit has its input end connected to the output end of the desalination unit. The adsorption unit can sequentially adsorb and desorb concentrated brine to produce lithium-rich water. The concentration section has its input end connected to the output end of the adsorption section, and the concentration section can concentrate lithium-rich water. The filter section has its input end connected to the output end of the concentration section. The filter section can filter lithium-rich water to remove impurities. The evaporation electrolysis unit has its input end connected to the output end of the filtration unit. The evaporation electrolysis unit can evaporate lithium-rich water and precipitate solid crystals of lithium ions, producing crude heavy water. The evaporation electrolysis unit can also electrolyze the crude heavy water to obtain deuterium gas. The output and input ends of the desalination unit are connected to allow for the reflux treatment of a portion of the concentrated brine. The output end of the desalination unit is connected to the input end of the backwash water of the filtration unit, so that some concentrated brine can backwash the filtration unit. The output end of the backwash water of the filtration unit is also connected to the input end of the desalination unit to perform backwash water recirculation treatment.

2. The system for coupling lithium extraction from seawater to deuterium gas production according to claim 1, characterized in that, The desalination unit includes: A nanofiltration device capable of removing divalent ions from seawater to produce primary water containing monovalent ions; A reverse osmosis unit, the input end of which is connected to the output end of the nanofiltration unit, is capable of desalinizing primary permeate to produce concentrated brine.

3. The system for coupling lithium extraction from seawater to deuterium gas production according to claim 2, characterized in that, The output of the reverse osmosis unit is connected to the input of the nanofiltration unit to reflux a portion of the produced concentrated brine.

4. The system for coupling lithium extraction from seawater to deuterium gas production according to claim 2, characterized in that, The input end of the nanofiltration device is connected to a pretreatment device, which can perform preliminary filtration of seawater to remove impurities from the seawater.

5. The system for coupling lithium extraction from seawater to deuterium gas production according to claim 4, characterized in that, The output end of the reverse osmosis device is connected to the input end of the backwash water of the filter section, so as to backwash the filter section with a portion of the produced concentrated brine. The backwash water output of the filter section is connected to the input of the pretreatment device so that the backwash water can carry impurities backflow.

6. The system for coupling lithium extraction from seawater to deuterium gas production according to claim 1, characterized in that, The evaporation electrolysis unit includes: An evaporation crystallization apparatus, wherein the input end of the evaporation crystallization apparatus is connected to the output end of the filter section to produce solid crystals of lithium ions and coarse heavy water; An electrolysis device, the input end of which is connected to the output end of the evaporation and crystallization device, to produce deuterium gas.

7. The system for coupling lithium extraction from seawater to deuterium gas production according to claim 6, characterized in that, The electrolysis apparatus includes: A primary electrolysis mechanism is provided, the input end of which is connected to the output end of the evaporation and crystallization device. The primary electrolysis mechanism can electrolyze crude heavy water to obtain refined heavy water by electrolyzing hydrogen and oxygen. The secondary electrolysis mechanism has its input end connected to the output end of the primary electrolysis mechanism. The secondary electrolysis mechanism can electrolyze the refined heavy water to produce deuterium gas.

8. The system for coupling lithium extraction from seawater to deuterium gas production according to any one of claims 1 to 7, characterized in that, The concentration unit is a membrane distillation device or an electrodialysis device.

9. The system for coupling lithium extraction from seawater with deuterium production according to any one of claims 1 to 7, characterized in that, The filtration section is an ultrafiltration device or a microfiltration device.

10. A method for producing deuterium gas from seawater coupled with lithium extraction, employing the system for producing deuterium gas from seawater coupled with lithium extraction as described in any one of claims 1 to 9, characterized in that, Includes the following steps: The seawater is desalinated in the desalination unit to produce concentrated brine; some of the concentrated brine is sent to the adsorption unit, and some of the concentrated brine is sent to the filtration unit. At the same time, some of the concentrated brine is refluxed in the desalination unit. Lithium-rich water is produced by adsorbing or desorbing concentrated brine in the adsorption section; the lithium-rich water is then transported to the concentration section. The lithium-rich water is concentrated through the concentration section; the concentrated lithium-rich water is then transported to the filtration section. Impurities in lithium-rich water are removed by the filtration section; at the same time, the filtration section is backwashed by the concentrated brine supplied to it, and the backwashed concentrated brine is returned to the desalination section. The lithium-rich water is evaporated in the evaporation electrolysis section to produce solid lithium-ion crystals and crude heavy water; then the crude heavy water is electrolyzed in the evaporation electrolysis section to obtain deuterium gas.

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