Steam condensation type adsorption device for extracting lithium from salt lake brine and production process

Abstract

The invention discloses a steam condensation type adsorption tower device system for extracting lithium from plateau salt lake brine, and belongs to the technical field of salt lake lithium extraction processes. A condenser of a multi-effect evaporation system and a traditional adsorption tower are coupled into a whole, the optimal temperature in the salt lake brine lithium adsorption process is achieved, and the lithium ion adsorption efficiency of the adsorption tower is improved; latent heat of vaporization released by condensation of secondary steam generated in a last-effect evaporator in a multi-flow tube bundle directly heats salt lake brine for adsorption and desorption processes, so that the adsorption rate of lithium in the salt lake brine is increased, fresh water required by a subsequent desorption process can be preheated, and the energy consumption cost of lithium extraction from the salt lake is reduced; the temperatures of an adsorbent and salt lake brine at different positions in the adsorption tower are optimized by reasonably arranging the flow of the condensation heat exchange tube bundle, the temperature of the adsorbent and the salt lake brine is gradually increased from top to bottom in the adsorption tower, and the temperature in the adsorption tower is increased from top to bottom to compensate the reduction of the adsorption rate caused by the reduction of the lithium ion concentration.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium extraction from salt lakes, and particularly relates to a steam condensation adsorption device for extracting lithium from salt lake brine and a production process for lithium extraction adsorption using this device. Background Technique

[0002] Lithium, the lightest metal in nature, has unique physical and chemical properties and is widely used in the field of new energy materials. China has become the world's largest consumer of lithium resources. Approximately 80% of China's lithium resource reserves are hosted in the salt lakes of the Qinghai-Tibet Plateau, which is ecologically fragile, energy-shortage, and has a low environmental temperature. The lithium content in the salt lakes is low and the magnesium-lithium ratio is high, making it difficult to separate lithium from the plateau salt lake brine and requiring high lithium extraction technology.

[0003] The main lithium extraction technologies from salt lake brine include precipitation method, adsorption method, solvent extraction method, membrane separation method, electrochemistry method, calcination method, solar pond method, etc. Compared with other lithium extraction technologies, the adsorption method has the advantages of low requirements for the magnesium-lithium ratio of brine, high elution rate, simple process, strong stability, high product purity, low energy consumption cost, and environmental friendliness. It is suitable for salt lake brine with low lithium content and high magnesium-lithium ratio. Therefore, this method has become the most promising lithium extraction technology for plateau salt lake brine.

[0004] The key technology of the adsorption method is the selection of lithium ion adsorbent and the optimization of adsorption operation parameters. The research on the adsorption method focuses on the development of adsorbents with high adsorption capacity, low cost, and recyclability. The optimal temperature requirements for lithium ion adsorption and desorption are above 50°C. For the low-temperature salt lake brine in the Qinghai-Tibet Plateau with an average annual temperature of 4°C, a large amount of heat is required to achieve the optimal adsorption temperature. The Qinghai-Tibet Plateau lacks electric energy and fossil fuels, which makes the existing adsorption lithium extraction energy consumption cost too high. Developing an adsorption device and production process suitable for lithium extraction from salt lake brine in the Qinghai-Tibet Plateau has become an urgent problem to be solved.

[0005] Chinese Patent with Publication No. CN213313473U discloses a new lithium extraction system for adsorbing and concentrating lithium-containing brine, which integrally realizes the adsorption, desorption, and concentration of lithium ions; Chinese Patent with Publication No. CN219058781U discloses a combined device for extracting lithium from lithium-containing salt lake brine, which can overcome the defect of the single function of the solar pond in salt lake brine and realize multiple processes such as evaporation, crystallization, and filtration; Chinese Patent with Publication No. CN110606499A discloses a combined device for extracting lithium from lithium-containing salt lake brine, which combines evaporation crystallization, nanofiltration, ion exchange, and a monovalent electrodialysis process for separating magnesium and lithium. The above invention patents are the integration of the existing salt lake lithium extraction processes, without considering the operation parameters such as the temperature and concentration of the brine in the adsorption lithium extraction process, not involving reducing the energy consumption in the adsorption process, and cannot be used to reduce the energy consumption cost of lithium extraction from plateau salt lake brine.

[0006] The Chinese patent with the publication number CN118813977A discloses a method for extracting lithium from carbonate-type saline lake brine and an adsorption tower, which improves the recovery efficiency of lithium adsorbent by adjusting the pH value of the saline lake brine; the Chinese patent with the publication number CN118812040A discloses a lithium extraction adsorption and desorption tower device, which uses two or more tower bodies with the same structure to achieve lithium extraction from produced water in oil and gas fields; the Chinese patent with the publication number CN111621640B discloses an adsorption tower and a lithium extraction method for extracting lithium from saline lake brine, which shortens the adsorption time by feeding liquid from the bottom of the adsorption tower and discharging liquid from the top; the Chinese patent with the publication number CN221740387U discloses an adsorption device for efficiently extracting lithium from lithium precipitation mother liquor with a titanium-based adsorbent, which solves problems such as compaction, solidification, and wear of the adsorbent bed layer, and greatly reduces the production cost of replenishing the adsorbent. Among the above patents on lithium extraction adsorption towers, the temperature during the adsorption process is not involved, and only the adsorption tower process or the adsorbent loading structure is optimized.

[0007] The Chinese patent with the publication number CN215444173U discloses a supercritical carbon dioxide power generation - brine lithium extraction coupling system. This system utilizes the waste heat of the supercritical carbon dioxide cycle, and after improving the quality of the waste heat through an absorption heat pump, it is used for the lithium extraction process. However, the supercritical carbon dioxide power generation system requires a high-temperature heat source, and the absorption heat pump consumes electric energy. Increasing the temperature during the adsorption process requires consuming high-quality electric energy and heat energy, which is not suitable for the actual situation in the Qinghai-Tibet Plateau where there is a shortage of electric energy and fossil fuels.

[0008] To sum up the above: In the prior art, the problems existing in the lithium extraction adsorption tower device and production process for saline lake brine are as follows: (1) The adsorption process of saline lake brine in the adsorption tower is an endothermic reaction. The optimal adsorption temperature of the commonly used aluminum salt adsorbent is 50 - 60°C, and the annual average temperature of saline lake brine in the Qinghai-Tibet Plateau is 4°C. When the saline lake brine directly adsorbs in the adsorption tower, the efficiency is too low. In the Qinghai-Tibet Plateau, there is a shortage of fossil fuels and electric energy, and the energy consumption cost of directly consuming electric energy and fuel to heat the saline lake brine is too high.

[0009] (2) In the lithium extraction process for saline lakes, after adsorption, the lithium solution is concentrated through a multi-effect evaporation system. The 55°C secondary steam generated in the last evaporator of the multi-effect evaporation system is condensed by the adsorbed lithium solution in the condenser. The adsorbed lithium solution is preheated and then enters the evaporator for evaporation, thereby improving the thermal efficiency of the multi-effect evaporation system. The improvement of the thermal efficiency of the multi-effect evaporation system is achieved at the expense of the temperature during the lithium ion adsorption process of the saline lake brine. The too low lithium ion adsorption efficiency of the low-temperature saline lake brine makes it difficult to effectively reduce the total energy consumption cost of saline lake lithium extraction.

[0010] (3) If the 55°C secondary steam generated by the final evaporator does not enter the condenser but directly enters the heat exchanger to preheat the salt lake brine, the preheated salt lake brine enters the adsorption tower and contacts the adsorbent at ambient temperature to complete the adsorption process. Limited by the heat transfer terminal temperature difference of the preheater, the temperature of the salt lake brine after preheating in the preheater is below 50°C, and the adsorption reaction temperature between the preheated salt lake brine and the adsorbent at ambient temperature in the adsorption tower is lower than the lower limit of the optimal adsorption temperature of 50°C. Therefore, directly heating the salt lake brine with secondary steam cannot ensure the temperature conditions for the adsorption reaction.

[0011] (4) During the downward flow of the salt lake brine entering from the upper part of the adsorption tower, lithium ions in the salt lake brine are adsorbed by the adsorbent, and its lithium ion concentration gradually decreases. The adsorption rate of the salt lake brine gradually decreases. As a result, when the adsorbent in the upper part of the adsorption tower reaches saturation, the adsorbent in the lower part has not yet reached saturation, reducing the overall adsorption rate of the adsorption tower. Summary of the Invention

[0012] In order to overcome the deficiencies of the prior art, the present invention proposes a steam condensation type adsorption device and production process for extracting lithium from salt lake brine.

[0013] The characteristics of the present invention are as follows: Develop a steam condensation type adsorption tower device that couples the condensation process of the secondary steam in the final effect of the lithium solution multi-effect evaporation system with the adsorption process of extracting lithium from salt lake brine. The latent heat of vaporization released by the condensation of the secondary steam generated by the final evaporator is directly used in the adsorption and desorption processes of the salt lake brine. The latent heat of vaporization released by the condensation of the 55°C secondary steam in the tube is used to heat the aluminum salt adsorbent and spray the salt lake brine in the adsorption tower outside the tube, so that the lithium adsorption process of the salt lake brine is maintained above the optimal temperature of 50°C; in the adsorption tower, the salt lake brine flows downward and collides with the heat exchange tubes and adsorbent particles, reducing the size of the salt lake brine spray droplets and making them in a suspended state with the adsorbent particles, increasing the contact area of the adsorption reaction and strengthening the heat transfer between the steam condensation in the tube and the brine droplets and adsorbent particles outside the tube, improving the adsorption efficiency of extracting lithium from salt lake brine; a multi-flow steam condensation heat exchange tube bundle is arranged in the steam condensation type adsorption tower device, and the overall adsorption efficiency in the adsorption tower is improved by reasonably arranging the heat exchange tube bundle process; the waste heat of the hot salt lake brine after adsorption is used to preheat the fresh water for the subsequent desorption process, and the preheated fresh water is used to wash the hot saturated adsorbent, which is beneficial to reducing the energy consumption cost of extracting lithium from salt lake brine.

[0014] The specific technical solution of the present invention is described as follows: A steam condensation type adsorption device for extracting lithium from salt lake brine, which includes an adsorption tower unit and a lithium solution concentration unit. The adsorption tower unit includes a salt lake water pump, a four-way stop valve, a steam condensation type adsorption tower, a hot brine tank, a heat exchanger, a fresh water tank, a fresh water pump and a three-way stop valve. The steam condensation type adsorption tower includes a sprayer, several process tube bundles, a tube box is provided for each process tube bundle, a terminal condensation water tank and an adsorbent. The salt lake water pump is connected to the four-way stop valve, and the fresh water tank is also connected to the four-way stop valve through the fresh water pump. The four-way stop valve diverts fresh water and brine into the sprayer. The steam condensation type adsorption tower is connected to the lithium solution concentration unit through a steam pipeline. Several stages of tube bundles are connected to the tube box and then connected to the terminal condensation water tank. Multiple tube boxes and the terminal condensation water tank are connected to the fresh water tank. The outlet of the steam condensation type adsorption tower is connected to the three-way stop valve, and the three-way stop valve is also connected to the hot brine tank. The hot brine tank is connected to the heat exchanger, and the heat exchanger is also connected to the fresh water tank.

[0015] The lithium solution concentration unit includes a booster pump, a nanofiltration membrane device, two-stage evaporators, a lithium carbonate precipitation device, a three-way stop valve and a magnesium solution tank. The three-way stop valve is connected to the booster pump, and the booster pump is connected to the nanofiltration membrane device. The nanofiltration membrane device is connected to the second evaporator through a pipeline, and the nanofiltration membrane device is also connected to the magnesium solution tank. A first evaporator heat exchange tube bundle is arranged in the first evaporator. The exhaust hole of the first evaporator is connected to the secondary steam outlet of the first evaporator, the heating steam inlet of the second evaporator and the heat exchange tube bundle of the second evaporator through a pipeline. The concentrated liquid outlet of the second evaporator is connected to the sprayer of the first evaporator through the feed liquid inlet of the first evaporator. The concentrated liquid outlet of the first evaporator is connected to the lithium carbonate precipitation device. The feed liquid inlet of the second evaporator is connected to the sprayer of the second evaporator. The exhaust hole of the second evaporator is connected to the secondary steam outlet of the second evaporator and the steam inlet tube box of the adsorption tower device unit in sequence through a pipeline. The condensate outlet of the second evaporator and the condensate outlet of the first evaporator are connected to the lower inlet of the fresh water tank through the three-way stop valve.

[0016] A production process for extracting lithium from salt lake brine adopts the following steps: Step 1: The salt lake brine is boosted by the salt lake water pump and enters the sprayer through the four-way stop valve. The salt lake brine is sprayed by the sprayer onto the surface of the adsorbent in the steam condensation type adsorption tower. Step 2: Constant-temperature steam enters into several process tube bundles and tube boxes in series step by step. The condensate in the process tube bundle at the outermost end enters the terminal tube box through the terminal condensation water tank. The outlets of each tube box and the terminal tube box are gathered, and the gathered condensate enters the fresh water tank. Step 3: The aluminum salt adsorbent in the steam condensation absorption tower and several process tube bundles form a heat exchanger with a fluidized bed structure; during the adsorption process, the salt lake brine sprayed by the sprayer impacts several process tube bundles in sequence, and the aluminum salt adsorbent exchanges heat with the impacted process tube bundles, and the aluminum salt adsorbent adsorbs magnesium and lithium ions in the salt lake brine; the hot brine that has completed the adsorption process converges to the bottom of the steam condensation absorption tower and enters the hot brine tank through a three-way stop valve; Step 4: The hot brine in the hot brine tank forms a closed hot brine circulation loop between the hot brine tank and the heat exchanger, and the cold fresh water in the fresh water tank forms a closed cold fresh water circulation loop between the fresh water tank and the heat exchanger; the hot brine in the hot brine circulation loop passing through the heat exchanger heats the fresh water in the cold fresh water circulation loop, and the temperature of the fresh water rises to 45 - 47 °C; Step 5: During the desorption process, the preheated fresh water in the fresh water tank is boosted by a fresh water pump and enters the sprayer through a four-way stop valve. The sprayed fresh water and the aluminum salt adsorbent form a thin liquid film outside the heat exchange tube wall of several process tube bundles. Under the impact of the fresh water, the collision between the aluminum salt adsorbent and the tube wall surface of the heat exchanger realizes heat exchange. After the fresh water outside the tube bundle and the aluminum salt adsorbent absorb the latent heat of vaporization released by the condensation of the steam inside the tube bundle, the temperature rises to 50 - 52 °C. The magnesium and lithium ions adsorbed by the aluminum salt adsorbent undergo a desorption process with the fresh water, and the magnesium-lithium solution at 50 - 52 °C after desorption converges to the bottom of the steam condensation type adsorption tower; Step 6: The magnesium-lithium solution at 50 - 52 °C enters the three-way stop valve through the outlet of the steam condensation type adsorption tower in sequence, is boosted by a booster pump and enters the nanofiltration membrane device to complete the separation of magnesium ions. The lithium solution after removing magnesium ions enters the second evaporator as a feed liquid through the nanofiltration membrane device. The solution rich in magnesium ions flows into the magnesium solution tank through the concentrated liquid outlet of the nanofiltration membrane device; Step 7: The lithium solution is sprayed onto the outer surface of the heat exchange tube bundle of the second evaporator. The liquid film outside the tube bundle absorbs the heat released by the condensation of the steam inside the heat exchange tube bundle of the second evaporator; the evaporated and concentrated lithium solution converges to the bottom of the second evaporator and flows into the sprayer of the first evaporator through the second evaporator. The concentrated lithium solution from the sprayer of the first evaporator is sprayed onto the outer surface of the heat exchange tube bundle of the first evaporator to form a uniform liquid film. The liquid film outside the tube bundle absorbs the heat released by the condensation of the steam inside the heat exchange tube bundle of the first evaporator, and the further evaporated and concentrated saturated lithium solution converges to the bottom of the first evaporator and flows into the lithium carbonate precipitation device; Step 8: The 65 °C heating steam serves as the heat source for evaporating and concentrating the lithium solution. The heating steam passes through the OneThe vapor entering the first evaporator releases heat by condensation inside the heat exchange tubes of the first evaporator. The vapor generated by the evaporation of the lithium solution outside the heat exchange tubes of the first evaporator mixes with the uncondensed vapor inside the heat exchange tubes of the first evaporator through the exhaust holes of the first evaporator. The mixed vapor enters the heat exchange tubes of the second evaporator through the secondary vapor outlet of the first evaporator and the heating vapor inlet of the second evaporator, serving as the heat source for evaporating the lithium solution in the second evaporator. The vapor generated by the evaporation of the lithium solution outside the heat exchange tubes of the second evaporator mixes with the uncondensed vapor inside the heat exchange tubes of the second evaporator through the exhaust holes of the second evaporator. The mixed vapor enters the steam inlet header through the secondary vapor outlet of the second evaporator. The condensate in the second evaporator and the first evaporator respectively flow into the fresh water tank through the three-way stop valve. Step 9: The saturated concentrated lithium solution flowing out of the first evaporator completes the dehydration process in the lithium carbonate precipitation device to obtain high-purity lithium carbonate solid.

[0017] Advantages of the present invention: (1) Develop a steam condensation type adsorption tower for extracting lithium from plateau salt lakes, which integrates the condenser of a multi-effect evaporation system and a traditional adsorption tower, and has a device with both steam condensation and lithium adsorption functions. Without increasing equipment investment and energy consumption, it ensures the adsorption temperature and adsorption reaction rate of the adsorption tower for extracting lithium from salt lake brine. The salt lake brine and the aluminum salt adsorbent are heated to increase the adsorption temperature of the adsorption tower for extracting lithium from salt lake brine, and the optimal adsorption temperature is ensured without additional consumption of electric energy and heat energy. The collision between the salt lake brine and the heat exchange tube wall reduces the size of the salt lake brine spray droplets, thereby increasing the surface area of the droplets. The collision between the adsorbent particles and the heat exchange tube wall makes the adsorbent in a suspended state, increasing the solid-liquid two-phase contact area between the surface of the adsorbent particles and the salt lake brine, strengthening the heat transfer between the steam condensation inside the tube and the salt lake brine droplets and adsorbent particles outside the tube, ensuring the optimal temperature of the adsorption reaction, and increasing the adsorption rate of extracting lithium from salt lake brine.

[0018] (2) Couple the condensation of the last-effect secondary steam with the adsorption process, that is, use the latent heat of vaporization released by the condensation of the secondary steam generated in the last evaporator to heat the adsorption and desorption processes of the salt lake brine. The heat released by the steam condensation inside the tube heats the aluminum salt adsorbent and the sprayed salt lake brine inside the adsorption tower outside the tube, achieving an optimal adsorption temperature of over 50 °C for the lithium adsorption process of the salt lake brine. The hot brine after adsorption preheats the fresh water for the subsequent desorption process through a plate heat exchanger. The preheated fresh water rinses the hot saturated adsorbent. The hot lithium solution obtained from the bottom of the adsorption tower undergoes a nanofiltration process and then serves as the feed liquid for the multi-effect evaporation system, that is, the heat of the secondary steam condensation in the last evaporator realizes the dual effects of heating up the adsorption and desorption processes and preheating the feed liquid for the multi-effect evaporation process.

[0019] (3) Optimize the temperatures of the adsorbent and the salt lake brine at different positions in the adsorption tower by reasonably arranging the flow path of the condensation heat exchange tube bundle, i.e., the temperatures of the adsorbent and the salt lake brine gradually increase from top to bottom in the adsorption tower. Increase the adsorption rate of lithium in the salt lake brine by increasing the temperatures of the adsorbent and the salt lake brine at the lower part of the tower. Adopt a multi-flow design. The steam inlet is at the top of the tower. The number of tube rows in the first flow path is the largest, with a large condensation heat transfer amount, and the temperatures of the adsorbent and the salt lake brine rise to the lower limit of the optimal adsorption temperature. The number of tube rows in the second and third flow paths decreases successively, the condensation heat transfer amount decreases, and the temperatures of the adsorbent and the salt lake brine increase slightly successively. Compensate for the decrease in the adsorption rate caused by the reduction of the lithium ion concentration by increasing the temperature from top to bottom in the adsorption tower, and improve the overall adsorption rate in the adsorption tower through the reasonable design of the condensation heat exchange device. Brief Description of the Drawings

[0020] Figure 1 It is a steam condensation type adsorption device and a production process diagram for extracting lithium from plateau salt lake brine disclosed by the present invention.

[0021] In the figure: 1. Salt lake water pump; 2. Four-way stopcock valve, 21. Salt lake brine inlet of the four-way stopcock valve, 22. Salt lake brine outlet of the four-way stopcock valve, 23. Fresh water outlet of the four-way stopcock valve, 24. Fresh water inlet of the four-way stopcock valve; 3. Sprayer, 31. Water inlet of the sprayer, 32. Water outlet of the sprayer; 4. Steam inlet header; 5. First flow path tube bundle; 6. Second flow path header, 61. Second flow path header inlet, 62. Second flow path header steam outlet, 63. Second flow path header condensate outlet; 7. Third flow path header, 71. Third flow path header inlet, 72. Third flow path header steam outlet, 73. Third flow path header condensate outlet; 8. Second flow path tube bundle; 9. Third flow path tube bundle; 10. End header, 101. End header inlet, 102. End header outlet; 11. Steam condensation absorption tower, 111. Water outlet of the steam condensation absorption tower; 12. Aluminum salt adsorbent; 13. Hot brine tank, 131. Upper inlet of the hot brine tank, 132. Lower outlet of the hot brine tank, 133. Lower inlet of the hot brine tank; 14. Heat exchanger, 141. Hot brine side inlet of the heat exchanger, 142. Hot brine side outlet of the heat exchanger, 143. Fresh water side inlet of the heat exchanger, 144. Fresh water side outlet of the heat exchanger; 15. Fresh water tank, 151. Middle inlet of fresh water tank, 152. Upper outlet of fresh water tank, 153. Upper inlet of fresh water tank, 154. Lower outlet of fresh water tank, 155. Lower inlet of fresh water tank; 16. Fresh water pump; 17. Three-way stop valve I, 171. Inlet of three-way stop valve, 172. Hot brine outlet of three-way stop valve, 173. Magnesium-lithium solution outlet of three-way stop valve; 18. Booster pump; 19. Nanofiltration membrane device, 191. Inlet of nanofiltration membrane device, 192. Outlet of nanofiltration membrane device, 193. Concentrate outlet of nanofiltration membrane device; 20. Second evaporator, 201. Feed liquid inlet of second evaporator, 202. Concentrate outlet of second evaporator, 203. Heating steam inlet of second evaporator, 204. Secondary steam outlet of second evaporator, 205. Condensate outlet of second evaporator, 206. Sprayer of second evaporator, 207. Heat exchange tube bundle of second evaporator, 208. Exhaust hole of second evaporator; 25. Magnesium solution tank; 26. Three-way stop valve II; 27. Lithium carbonate precipitation device; 28. First evaporator, 281. Feed liquid inlet of first evaporator, 282. Concentrate outlet of first evaporator, 283. Secondary steam outlet of first evaporator, 284. Heating steam inlet of first evaporator, 285. Condensate outlet of first evaporator, 286. Sprayer of first evaporator, 287. Heat exchange tube bundle of first evaporator, 288. Exhaust hole of first evaporator. Detailed implementation mode

[0022] The present invention will be described in detail below through specific embodiments. Those who understand this technology can easily understand other advantages and effects of the present invention from the content disclosed in this specification; it should be noted, however, that the following specific implementation modes do not technically limit the technical solution of the present application. Under the guidance of the following technical solutions, those skilled in the art can further extend the technology. The protection scope of this patent application is subject to the claims.

[0023] Example 1: (Connection structure of this adsorption device) Figure 1A steam condensation type adsorption device for extracting lithium from plateau salt lake brine is shown. It includes an adsorption tower device unit on the left and a lithium solution concentration unit on the right. The adsorption tower device unit on the left includes a salt lake water pump 1, a four-way stopcock valve 2, a steam condensation type adsorption tower 11, a hot brine tank 13, a heat exchanger 14, a fresh water tank 15, a fresh water pump 16, and a three-way stopcock valve I 17. The steam condensation type adsorption tower 11 includes a sprayer 3, a steam inlet header 4, a first-pass tube bundle 5, a second-pass tube bundle 8, a third-pass tube bundle 9, a second-pass header 6, a third-pass header 7, a terminal condensate tank 10, and an aluminum salt adsorbent 12. The salt lake water pump 1 is connected to the salt lake water inlet 21 of the four-way stopcock valve. The fresh water outlet 22 and the salt lake water outlet 23 of the four-way stopcock valve are connected to the sprayer inlet 31 through a pipeline and then to the sprayer 3 and the sprayer outlet 32. The lower outlet 154 of the fresh water tank is connected to the fresh water inlet 24 of the four-way stopcock valve through the fresh water pump 16. The steam inlet header 4 in the steam condensation type adsorption tower 11 is connected to the lithium solution concentration unit through a pipeline. The first-pass tube bundle 5 is connected to the inlet 61 of the second-pass header. The steam outlet 62 of the second-pass header is connected to the second-pass tube bundle 8 and then to the inlet 71 of the third-pass header. The steam outlet 72 of the third-pass header is connected to the third-pass tube bundle 9 and then to the inlet 101 of the terminal header. The condensate outlet 63 of the second-pass header, the condensate outlet 73 of the third-pass header, and the outlet 102 of the terminal header are connected to the middle inlet 151 of the fresh water tank. The outlet 111 of the steam condensation type adsorption tower is connected to the inlet 171 of the three-way stopcock valve. The hot brine outlet 172 of the three-way stopcock valve is connected to the upper inlet 131 of the hot brine tank through a pipeline. The lower outlet 132 of the hot brine tank is connected to the inlet 141 of the hot brine side of the heat exchanger. The lower inlet 133 of the hot brine tank is connected to the outlet 142 of the hot brine side of the heat exchanger. The inlet 143 of the fresh water side of the heat exchanger is connected to the upper outlet 152 of the fresh water tank. The outlet 144 of the fresh water side of the heat exchanger is connected to the upper inlet 153 of the fresh water tank.

[0024] The lithium solution concentration unit on the right side includes a booster pump 18, a nanofiltration membrane device 19, a second evaporator 20, a first evaporator 28, a lithium carbonate precipitation device 27, a three-way stop valve II 26, and a magnesium solution tank 25; the magnesium-lithium solution outlet 173 of the three-way stop valve is connected to the inlet 191 of the nanofiltration membrane device through the booster pump 18, the outlet 192 of the nanofiltration membrane device is connected to the second evaporator 20 through a pipeline, and the concentrated liquid outlet 193 of the nanofiltration membrane device is connected to the magnesium solution tank 25; the heating steam inlet 284 of the first evaporator is connected to the heat exchange tube bundle 287 of the first evaporator, the exhaust hole 288 of the first evaporator is sequentially connected to the secondary steam outlet 283 of the first evaporator, the heating steam inlet 203 of the second evaporator, and the heat exchange tube bundle 207 of the second evaporator through a pipeline, the concentrated liquid outlet 202 of the second evaporator is connected to the sprayer 286 of the first evaporator through the feed liquid inlet 281 of the first evaporator, the concentrated liquid outlet 282 of the first evaporator is connected to the lithium carbonate precipitation device 27, the feed liquid inlet 201 of the second evaporator is connected to the sprayer 206 of the second evaporator, the exhaust hole 208 of the second evaporator is sequentially connected to the secondary steam outlet 204 of the second evaporator and the steam inlet header 4 of the adsorption tower device unit through a pipeline, and the condensate outlet 205 of the second evaporator and the condensate outlet 285 of the first evaporator are connected to the lower inlet 155 of the fresh water tank through the three-way stop valve II 26.

[0025] Example 2 A production process using the steam condensation type adsorption device for extracting lithium from plateau salt lake brine in Example 1 adopts the following steps: Step 1: The salt lake brine with a temperature of 0 - 5°C and a lithium ion mass concentration of 0.05% is pressurized by the salt lake water pump 1 and enters the sprayer 3 through the salt lake water inlet 21 of the four-way stop valve, the salt lake water outlet 23 of the four-way stop valve, and the sprayer water inlet 31 in sequence. The salt lake brine is evenly sprayed onto the surface of the adsorption layer of the aluminum salt adsorbent 12 in the steam condensation type adsorption tower 11 through the sprayer water outlet 32. Step 2: The secondary steam at 55°C enters from the steam inlet header 4 into the inlet of the first-pass tube bundle 5. 60% - 75% of the steam condenses inside the tubes of the first-pass tube bundle 5, releasing the latent heat of vaporization. After the condensed liquid inside the tubes and the uncondensed steam flow out from the outlet of the first-pass tube bundle 5, they enter the second-pass header 6 through the second-pass header inlet 61. The uncondensed steam enters the inlet of the second-pass tube bundle 8 from the second-pass header steam outlet 62. In the second pass, 70 - 80% of the inlet steam condenses inside the tubes of the second-pass tube bundle 8, releasing the latent heat of vaporization, and then enters the third-pass header 7 through the third-pass header inlet 71. The uncondensed steam enters the third-pass tube bundle 9 to continue condensing and releasing heat from the third-pass header steam outlet 72. The condensed liquid inside the third-pass tube bundle 9 enters the end header 10 through the end header inlet 101. The condensed liquid at the bottoms of the second-pass header 6, the third-pass header 7, and the end header 10 are respectively collected through the second-pass header condensate outlet 63, the third-pass header condensate outlet 73, and the end header outlet 102. The collected condensed liquid enters the fresh water tank 15 through the middle inlet 151 of the fresh water tank; Step 3: The granular aluminum salt adsorbent 12 with a diameter of about 1 mm inside the steam condensation absorption tower 11 forms a fluidized bed structure heat exchanger with the first-pass tube bundle 5, the second-pass tube bundle 8, and the third-pass tube bundle 9. During the adsorption process, the salt lake brine sprayed by the sprayer 3 forms a thin liquid film outside the heat exchange tube wall of the first-pass tube bundle 5 through the aluminum salt adsorbent 12. Under the impact of the salt lake brine, the collision between the aluminum salt adsorbent 12 and the heat exchange tube wall surface realizes heat exchange. After the salt lake brine outside the tube bundle and the aluminum salt adsorbent 12 absorb the latent heat of vaporization released by the steam condensation inside the first-pass tube bundle 5, the temperature rises to 50°C, and the aluminum salt adsorbent 12 adsorbs magnesium and lithium ions in the salt lake brine. On the outer wall surfaces of the second-pass heat tube bundle 8 and the third-pass tube bundle 9, the temperature of the aluminum salt adsorbent 12 and the salt lake brine continues to rise to 52 - 53°C. The salt lake brine with a reduced lithium ion concentration after preliminary adsorption outside the first-pass tube bundle 5 continues to react with the aluminum salt adsorbent 12. The hot brine that has completed the adsorption process is collected at the bottom of the steam condensation absorption tower 11 and enters the hot brine tank 13 through the steam condensation type adsorption tower outlet 111, the three-way cock inlet 171, the three-way cock hot brine outlet 172, and the upper inlet 131 of the hot brine tank in sequence; Step 4: The hot brine in the hot brine tank 13 flows through the lower outlet 132 of the hot brine tank, the heat exchanger hot brine side inlet 141, the heat exchanger 14, the heat exchanger hot brine side outlet 142, and the lower inlet 133 of the hot brine tank in sequence to form a hot brine closed circulation loop. The cold fresh water in the fresh water tank 15 flows through the upper outlet 152 of the fresh water tank, the heat exchanger fresh water side inlet 143, the heat exchanger 14, the heat exchanger fresh water side outlet 144, and the upper inlet 153 of the fresh water tank in sequence to form a cold fresh water closed circulation loop. The hot brine in the hot brine closed circulation loop passing through the heat exchanger 14 heats the fresh water in the cold fresh water closed circulation loop, and the temperature of the fresh water in the fresh water tank 15 rises to 45 - 47°C; Step 5: During the desorption process, the preheated fresh water in the fresh water tank 15 flows out from the lower outlet 154 of the fresh water tank, is boosted by the fresh water pump 16, and then enters the sprayer 3 successively through the fresh water inlet 24 of the four-way cock valve, the salt lake water outlet 23 of the four-way cock valve, and the sprayer water inlet 31. The fresh water sprayed out from the sprayer outlet 32 forms a thin liquid film on the outer wall of the heat exchange tubes of the first-stage tube bundle 5, the second-stage tube bundle 8, and the third-stage tube bundle 9 of the aluminum salt adsorbent 12. Under the impact of the fresh water, the collision between the aluminum salt adsorbent 12 and the heat exchange tube wall surface realizes heat exchange. After the fresh water outside the tube bundle and the aluminum salt adsorbent 12 absorb the latent heat of vaporization released by the condensation of the steam inside the tube bundle, the temperature rises to 50 - 52 °C. The magnesium and lithium ions adsorbed by the aluminum salt adsorbent 12 undergo a desorption process with the fresh water. After desorption, the magnesium-lithium solution at 50 - 52 °C collects at the bottom of the steam condensation type adsorption tower 11; Step 6: The magnesium-lithium solution at 50 - 52 °C passes through the steam condensation type adsorption tower outlet 111, the three-way cock valve inlet 171, and the three-way cock valve magnesium-lithium solution outlet 173 in sequence, is boosted by the booster pump 18, and enters the nanofiltration membrane device 19 through the nanofiltration membrane device inlet 191 to complete the separation of magnesium ions. The lithium solution after removing magnesium ions enters the second evaporator sprayer 206 as the feed liquid through the nanofiltration membrane device outlet 192 and the second evaporator feed liquid inlet 201. The magnesium-rich solution flows into the magnesium solution tank 25 through the nanofiltration membrane device concentrated liquid outlet 193; Step 7: The lithium solution is sprayed onto the outer surface of the second evaporator heat exchange tube bundle 20g by the second evaporator sprayer 20f. The liquid film outside the tube bundle absorbs the heat released by the condensation of the steam inside the second evaporator heat exchange tube bundle 20g. The evaporated and concentrated lithium solution collects at the bottom of the second evaporator 20, and flows into the first evaporator sprayer 286 through the second evaporator concentrated liquid outlet 202 and the first evaporator feed liquid inlet 281. The concentrated lithium solution sprayed by the first evaporator sprayer 286 forms a uniform liquid film on the outer surface of the first evaporator heat exchange tube bundle 287. The liquid film outside the tube bundle absorbs the heat released by the condensation of the steam inside the first evaporator heat exchange tube bundle 287. The further evaporated and concentrated saturated lithium solution collects at the bottom of the first evaporator 28, and flows into the lithium carbonate precipitation device 27 through the first evaporator concentrated liquid outlet 282; Step 8: The 65°C heating steam serves as the heat source for evaporating and concentrating the lithium solution. The heating steam enters the heat exchange tube bundle 287 of the first evaporator through the first evaporator heating steam inlet 284 and condenses and releases heat therein. The secondary steam generated by the evaporation of the lithium solution outside the heat exchange tube bundle 287 of the first evaporator mixes with the uncondensed steam in the heat exchange tube bundle 287 of the first evaporator through the first evaporator exhaust hole 288. The mixed steam enters the heat exchange tube bundle 207 of the second evaporator through the first evaporator secondary steam outlet 283 and the second evaporator heating steam inlet 203, serving as the heat source for evaporating the lithium solution in the second evaporator 20. The steam generated by the evaporation of the lithium solution outside the heat exchange tube bundle 207 of the second evaporator mixes with the uncondensed steam inside the heat exchange tube bundle 207 of the second evaporator through the second evaporator exhaust hole 208. The mixed steam enters the steam inlet header 4 through the second evaporator secondary steam outlet 204. The condensate of the second evaporator 20 and the first evaporator 28 flow out through the second evaporator condensate outlet 205 and the first evaporator condensate outlet 285 respectively, and flow into the fresh water tank 15 through the three-way stop valve II 26 and the lower inlet 155 of the fresh water tank.

[0026] Step 9: The saturated concentrated lithium solution flowing out from the first evaporator concentrated solution outlet 282 completes the dehydration process in the lithium carbonate precipitation device 27 to obtain high-purity lithium carbonate solid.

[0027] With the above technical solutions, through the steam condensation type adsorption tower device for extracting lithium from plateau salt lakes, the condenser of the multi-effect evaporation system and the traditional adsorption tower are coupled into one, with both steam condensation and lithium adsorption functions. By the collision between the aluminum salt adsorbent and the salt lake brine and the tube bundle, the heat exchange efficiency is improved. In the three-pass tube bundle of the steam condensation type adsorption tower, the heat released by the condensation of the 55°C secondary steam generated in the second evaporator is used to heat the aluminum salt adsorbent outside the tube bundle and the sprayed salt lake brine to 52 - 53°C, reaching the optimal adsorption temperature for the lithium adsorption process of the salt lake brine, thereby improving the overall adsorption efficiency in the adsorption tower. After adsorption, the added brine preheats the fresh water required for the subsequent desorption process through a heat exchanger, and the heated fresh water rinses the saturated adsorbent to complete the desorption process, saving the heating steam amount in the three-pass tube bundle and reducing the energy consumption cost for extracting lithium from salt lakes. By arranging the heat exchange tube bundle in three passes, the temperature of the adsorbent and the salt lake brine at different positions in the adsorption tower is optimized, that is, the temperature of the adsorbent and the salt lake brine gradually increases from top to bottom in the adsorption tower, corresponding to the decrease in the lithium concentration of the salt lake brine from top to bottom in the adsorption tower. By increasing the temperature of the adsorbent and the salt lake brine at the lower part of the adsorption tower, the adsorption rate of lithium in the salt lake brine is enhanced.

Claims

1. A steam condensation adsorption device for extracting lithium from salt lake brine, characterized in that: It includes an adsorption tower unit and a lithium solution concentration unit. The adsorption tower unit comprises a salt lake water pump, a four-way stop valve, a steam condensation type adsorption tower, a hot brine tank, a heat exchanger, a fresh water tank, a fresh water pump and a three-way stop valve; the steam condensation type adsorption tower comprises a sprayer, a number of process tube bundles, a tube box is arranged for each process tube bundle, a terminal condensation water tank and an adsorbent; the salt lake water pump is connected to the four-way stop valve, and the fresh water tank is also connected to the four-way stop valve through the fresh water pump. The four-way stop valve diverts fresh water and brine into the sprayer; the steam condensation type adsorption tower is connected to the lithium solution concentration unit through a steam pipeline. A number of tube bundles are connected to the tube box and then connected to the terminal condensation water tank. A plurality of tube boxes and the terminal condensation water tank are connected to the fresh water tank. The outlet of the steam condensation type adsorption tower is connected to the three-way stop valve, and the three-way stop valve is also connected to the hot brine tank. The hot brine tank is connected to the heat exchanger, and the heat exchanger is also connected to the fresh water tank.

2. The steam condensation adsorption device for extracting lithium from salt lake brine according to claim 1, wherein: The lithium solution concentration unit comprises a booster pump, a nanofiltration membrane device, two-stage evaporators, a lithium carbonate precipitation device, a three-way stop valve and a magnesium solution tank; the three-way stop valve is connected to the booster pump, and the booster pump is connected to the nanofiltration membrane device. The nanofiltration membrane device is connected to the second evaporator through a pipeline, and the nanofiltration membrane device is also connected to the magnesium solution tank; a first evaporator heat exchange tube bundle is arranged in the first evaporator. The exhaust hole of the first evaporator is connected to the secondary steam outlet of the first evaporator, the heating steam inlet of the second evaporator and the heat exchange tube bundle of the second evaporator through a pipeline. The concentrated liquid outlet of the second evaporator is connected to the sprayer of the first evaporator through the feed liquid inlet of the first evaporator. The concentrated liquid outlet of the first evaporator is connected to the lithium carbonate precipitation device. The feed liquid inlet of the second evaporator is connected to the sprayer of the second evaporator. The exhaust hole of the second evaporator is connected to the secondary steam outlet of the second evaporator and the steam inlet tube box of the adsorption tower device in sequence through a pipeline. The condensate outlet of the second evaporator and the condensate outlet of the first evaporator are connected to the lower inlet of the fresh water tank through the three-way stop valve.

3. A production process for extracting lithium from salt lake brine, using the steam condensation type adsorption device for extracting lithium from salt lake brine as claimed in claim 2, characterized in that: It includes the following steps: Step 1: The salt lake brine is boosted by the salt lake water pump and enters the sprayer through the four-way stop valve. The salt lake brine is sprayed by the sprayer onto the surface of the adsorbent in the steam condensation type adsorption tower; Step 2: Constant-temperature steam enters into a number of process tube bundles and tube boxes in series step by step; the condensate in the process tube bundle at the outermost end enters the terminal tube box through the terminal condensation water tank; the outlets of each tube box and the terminal tube box are collected, and the collected condensate enters the fresh water tank; Step 3: The aluminum salt adsorbent in the steam condensation absorption tower and a number of process tube bundles form a heat exchanger with a fluidized bed structure; during the adsorption process, the salt lake brine sprayed by the sprayer impacts a number of process tube bundles in sequence. The aluminum salt adsorbent exchanges heat with the impacted process tube bundles, and the aluminum salt adsorbent adsorbs magnesium and lithium ions in the salt lake brine; the hot brine after the adsorption process is collected at the bottom of the steam condensation absorption tower and enters the hot brine tank through the three-way stop valve; Step 4: The hot brine in the hot brine tank forms a closed circulation loop between the hot brine tank and the heat exchanger, and the cold fresh water in the fresh water tank forms a closed circulation loop between the fresh water tank and the heat exchanger; the hot brine in the hot brine closed circulation loop passing through the heat exchanger heats the fresh water in the cold fresh water closed circulation loop, and the temperature of the fresh water rises to 45 - 47 °C; Step 5: During the desorption process, the preheated fresh water in the fresh water tank is pressurized by a fresh water pump and enters the sprayer through a four-way cock valve. The sprayed fresh water and the aluminum salt adsorbent form a thin liquid film outside the heat exchange tube walls of several process tube bundles. Under the impact of the fresh water, the collision between the aluminum salt adsorbent and the heat exchange tube wall surface realizes heat exchange. After the fresh water and the aluminum salt adsorbent outside the tube bundle absorb the latent heat of vaporization released by the condensation of the steam inside the tube bundle, the temperature rises to 50 - 52 °C. The magnesium and lithium ions adsorbed by the aluminum salt adsorbent undergo a desorption process with the fresh water, and the 50 - 52 °C magnesium-lithium solution after desorption converges to the bottom of the steam condensation type adsorption tower; Step 6: The 50 - 52 °C magnesium-lithium solution enters the three-way cock valve successively through the outlet of the steam condensation type adsorption tower, is pressurized by a booster pump, and then enters the nanofiltration membrane device to complete the separation of magnesium ions. The lithium solution after removing magnesium ions enters the second evaporator as the feed liquid through the nanofiltration membrane device. The solution rich in magnesium ions flows into the magnesium solution tank through the concentrated liquid outlet of the nanofiltration membrane device; Step 7: The lithium solution is sprayed onto the outer surface of the heat exchange tube bundle of the second evaporator, and the liquid film outside the tube bundle absorbs the heat released by the condensation of the steam inside the heat exchange tube bundle of the second evaporator; the evaporated and concentrated lithium solution converges to the bottom of the second evaporator and then flows into the sprayer of the first evaporator through the second evaporator. The concentrated lithium solution from the sprayer of the first evaporator is sprayed onto the outer surface of the heat exchange tube bundle of the first evaporator to form a uniform liquid film. The liquid film outside the tube bundle absorbs the heat released by the condensation of the steam inside the heat exchange tube bundle of the first evaporator, and the further evaporated and concentrated saturated lithium solution converges to the bottom of the first evaporator and flows into the lithium carbonate precipitation device; Step 8: The 65 °C heating steam serves as the heat source for evaporating and concentrating the lithium solution. The heating steam enters the heat exchange tube bundle inside the first evaporator and condenses to release heat. The steam generated by the evaporation of the lithium solution outside the heat exchange tube bundle of the first evaporator mixes with the uncondensed steam inside the heat exchange tube bundle of the first evaporator through the exhaust hole of the first evaporator. The mixed steam enters the heat exchange tube bundle inside the second evaporator through the secondary steam outlet of the first evaporator and the heating steam inlet of the second evaporator, serving as the heat source for evaporating the lithium solution inside the second evaporator; the steam generated by the evaporation of the lithium solution outside the heat exchange tube bundle of the second evaporator mixes with the uncondensed steam inside the heat exchange tube bundle of the second evaporator through the exhaust hole of the second evaporator. The mixed steam enters the steam inlet header through the secondary steam outlet of the second evaporator. The condensate in the second evaporator and the first evaporator flows into the fresh water tank through the three-way cock valve respectively; Step 9: The saturated concentrated lithium solution flowing out of the first evaporator completes the dehydration process in the lithium carbonate precipitation device to obtain high-purity lithium carbonate solid.

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