Raw brine treatment system and raw brine treatment method suitable for lithium extraction from salt lakes

Abstract

The present invention discloses a raw brine treatment system and a raw brine treatment method suitable for lithium extraction from salt lakes. The raw brine treatment system comprises: an ion exchange adsorption unit, the ion exchange adsorption unit comprises an adsorption tower, a part of the raw brine to be treated enters the adsorption process of the adsorption tower for adsorption treatment, and then is desorbed with desorption water in the desorption process; a desorption water extraction unit, another part of the raw brine to be treated and / or part of the adsorption tail liquid of the ion exchange adsorption unit enters the desorption water extraction unit, the desorption water extraction unit extracts desorption water from the raw brine and / or the adsorption tail liquid entering the desorption water extraction unit, and the desorption water extraction unit is connected to the ion exchange adsorption unit; a recovery unit, the recovery unit is connected to the ion exchange adsorption unit and the desorption water extraction unit. The above raw brine treatment system can alleviate or solve the problem that a large amount of process water required for desorption treatment needs to be provided by an external water source and the problem of difficulty in external discharge of tail brine.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium extraction from salt lakes, and in particular to a raw brine treatment system and a raw brine treatment method suitable for lithium extraction from salt lakes. Background Art

[0002] Lithium and its compounds are widely used and have important value for the development of the country and society. In particular, the demand for lithium resources has increased significantly in recent years, while the production capacity of lithium resources cannot meet the sudden increase in demand in time, which has caused the price of lithium to remain high and the supply of lithium resources to exceed demand. Salt lake lithium extraction plants require a large amount of fresh water for key processes such as adsorption and lithium precipitation. The geographical location of salt lakes is mostly in high-altitude desert areas, which are extremely dry and water-deficient. They are far away from water sources and the cost of transporting fresh water is very high. This has caused great obstacles to the normal operation of the salt lake lithium extraction process system; in addition, salt lake brine is mostly stored in sponge-like pores, and it is difficult to achieve the reinjection of tail brine after lithium extraction from the original brine. In related technologies, tail brine is stored by building a tail brine pool. Due to the large amount of tail brine, it is necessary to plan a huge storage pool area.

[0003] Therefore, the current raw brine processing system and raw brine processing method suitable for lithium extraction from salt lakes still need to be improved. Summary of the invention

[0004] The present invention aims to alleviate or solve at least one of the above-mentioned problems to at least some extent.

[0005] In one aspect of the present invention, a raw brine treatment system suitable for lithium extraction from salt lakes is proposed, the raw brine treatment system comprising: an ion exchange adsorption unit, the ion exchange adsorption unit comprising one or more adsorption towers filled with adsorbent, a portion of the raw brine to be treated enters the adsorption process of the adsorption tower for adsorption treatment, and then is desorbed with desorption water in the desorption process of the adsorption tower; a desorption water extraction unit, another portion of the raw brine to be treated and / or part of the adsorption tail liquid of the ion exchange adsorption unit enters the desorption water extraction unit, the desorption water extraction unit extracts desorption water from the raw brine and / or adsorption tail liquid entering the desorption water extraction unit, the desorption water extraction unit is connected to the ion exchange adsorption unit so that the extracted desorption water enters the desorption process to desorb the lithium salt in the adsorption tower; a recovery unit, the recovery unit is connected to the ion exchange adsorption unit and the desorption water extraction unit. Therefore, part of the adsorption tail liquid of the ion exchange adsorption unit and part of the raw brine liquid to be treated can be used to extract desorption water, and part of the adsorption tail liquid of the ion exchange adsorption unit can be used to leach and recover the crystalline salt mixture carried in the solid precipitate of the desorption water extraction unit, so that the raw brine liquid can be treated by the above-mentioned raw brine treatment system, which can at least alleviate or solve to a certain extent the problem that a large amount of process water required for the desorption link needs to be provided by an external water source and the problem of difficulty in discharging the tail brine.

[0006] In another aspect of the present invention, a method for treating raw brine using the raw brine treatment system described above is proposed, the method comprising: allowing a portion of the raw brine to be treated to enter the adsorption tower of the ion exchange adsorption unit, and enter the desorption process after being subjected to adsorption treatment in the adsorption process of the adsorption tower, the desorption process desorbs the lithium salt in the adsorption tower, and a qualified liquid is obtained after the desorption treatment; a portion of the adsorption tail liquid formed after the adsorption process of the raw brine is adsorbed enters the desorption water extraction unit, and another portion of the raw brine to be treated also enters the desorption water extraction unit, the adsorption tail liquid and the raw brine are treated by the desorption water extraction unit to obtain a mixture of desorption water and crystallized salt, the desorption water enters the desorption process, another portion of the adsorption tail liquid formed after the raw brine is adsorbed in the adsorption process enters the recovery unit, the crystallized salt mixture enters the recovery unit, and the adsorption tail liquid in the recovery unit is used to leach and recover the crystallized salt mixture. Therefore, by using the above method to treat the raw brine, desorption water can be extracted from the raw brine and the adsorption tail liquid, thereby reducing or even avoiding the use of external water sources, and at least to a certain extent alleviating or even solving the technical problem of difficulty in obtaining process fresh water; the adsorption tail liquid is used to provide desorption water and to elute and recover the crystalline salt mixture, so that the adsorption tail liquid can be fully utilized and the problem of difficulty in discharging the adsorption tail liquid can be solved; the lithium-containing solution obtained by eluting and recovering the crystalline mixed salt can be mixed with the raw brine to be treated for further treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0008] Figure 1 It shows a schematic structural diagram of a raw halogen treatment system according to an embodiment of the present invention;

[0009] Figure 2 It shows a schematic structural diagram of a raw halogen treatment system according to another embodiment of the present invention;

[0010] Figure 3 It shows a schematic structural diagram of a raw halogen treatment system according to yet another embodiment of the present invention;

[0011] Figure 4 It shows a schematic structural diagram of a raw halogen treatment system according to yet another embodiment of the present invention;

[0012] Figure 5 It shows a schematic structural diagram of a raw halogen treatment system according to yet another embodiment of the present invention;

[0013] Figure 6 A schematic structural diagram of a recovery unit according to an embodiment of the present invention is shown.

[0014] Description of reference numerals:

[0015] 100: ion exchange adsorption unit; 110: adsorption tower; 111: adsorption process; 112: desorption process; 130: feed port of ion exchange adsorption unit; 200: desorption water extraction unit; 210: feed port of desorption water extraction unit; 220: extraction tail liquid outlet; 230: preheater; 240: evaporator; 250: crystallization separation system; 251: liquid inlet; 252: liquid outlet; 253: solid outlet; 260: reverse osmosis component; 300: recovery unit; 310: lithium-rich solution outlet of recovery unit; 320: eluent tank; 330: spray component; 340: conveyor component; 350: solid Body inlet; 400: feed pretreatment unit; 410: feed pretreatment unit outlet; 420: feed tank; 421: agitator; 430: filter; 1: original brine; 1': a part of the original brine; 1": another part of the original brine; 2: first diverter valve; 3: second diverter valve; 4: adsorption tail liquid; 4': a part of the adsorption tail liquid; 4": another part of the adsorption tail liquid; 5: high-temperature condensed water; 5': low-temperature condensed water; 6: water for desorption; 7: waste liquid; 8: extraction tail liquid; 9: crystallized salt mixture; 10: lithium-containing concentrated solution; 11: qualified liquid; 12: lithium-rich solution; 13: waste crystallized salt mixture. DETAILED DESCRIPTION

[0016] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0017] In one aspect of the present invention, the present invention provides a raw brine processing system suitable for extracting lithium from salt lakes. Figures 1 to 5The raw brine treatment system may include an ion exchange adsorption unit 100, a desorption water extraction unit 200 and a recovery unit 300, wherein the ion exchange adsorption unit 100 includes one or more adsorption towers 110 filled with adsorbents, a portion 1' of the raw brine to be treated enters the adsorption process 111 of the adsorption tower 110 for adsorption treatment, and then is desorbed with desorption water in the desorption process 112 of the adsorption tower, wherein each adsorption tower 110 continuously cycles through adsorption and desorption treatments, another portion 1" of the raw brine to be treated and / or part of the adsorbed tail liquid of the ion exchange adsorption unit 100 enters the desorption water extraction unit 200, and the desorption water extraction unit 200 is a unit that extracts the tail liquid from the raw brine entering the desorption tower. Desorption water is extracted from the raw brine and / or adsorption tail liquid of the absorption water extraction unit 200, and the desorption water extraction unit 200 is connected to the ion exchange adsorption unit 100, so that the extracted desorption water enters the desorption process to desorb the lithium salt in the adsorption tower 110, and the recovery unit 300 is connected to the ion exchange adsorption unit 100 and the desorption water extraction unit 200. Therefore, the raw brine treatment system can be used to extract water from the raw brine and adsorption tail liquid and use it as desorption water, thereby reducing or even avoiding the use of external water sources, and further reducing the problem of difficulty in obtaining external water sources; and the adsorption tail liquid can be fully utilized, thereby at least to a certain extent alleviating or even solving the problem of difficulty in discharging the adsorption tail liquid.

[0018] According to some embodiments of the present invention, reference Figures 1 to 5 The desorption water extraction unit 200 is connected to the ion exchange adsorption unit 100 so that part of the adsorption tail liquid in the ion exchange adsorption unit 100 enters the desorption water extraction unit 200, that is, part of the adsorption tail liquid produced in the adsorption process 112 enters the desorption water extraction unit 200. Thus, the desorption water extraction unit can extract desorption water from the adsorption tail liquid, which can solve the problems of difficulty in handling the adsorption tail liquid and lack of desorption water at the same time.

[0019] According to some specific embodiments of the present invention, Figure 4 and Figure 5 A first diverter valve 2 can be provided on one side of the ion exchange adsorption unit 100. The adsorption process 111 of the ion exchange adsorption unit 100 is respectively connected to the desorption water extraction unit 200 and the recovery unit 300. By providing the first diverter valve 2, the adsorption tail liquid generated by the adsorption process 111 can be divided into two parts, one part enters the desorption water extraction unit 200 for extracting desorption water, and the other part enters the recovery unit 300 for eluting and recovering the crystalline salt mixture, thereby achieving full utilization of the adsorption tail liquid and reducing the discharge amount of the adsorption tail liquid.

[0020] According to some embodiments of the present invention, reference Figures 2 to 5The raw brine treatment system may further include a feed pretreatment unit 400, which is connected to the ion exchange adsorption unit 100 and the desorption water extraction unit 200, and the discharge port 410 of the feed pretreatment unit is respectively connected to the feed port 130 of the ion exchange adsorption unit and the feed port 210 of the desorption water extraction unit. Thus, the raw brine 1 can be pretreated in the feed pretreatment unit first, and then enter the ion exchange adsorption unit and the desorption water extraction unit, which is conducive to further improving the effect of the raw brine treatment system on the treatment of the raw brine.

[0021] According to some embodiments of the present invention, reference Figures 2 to 5 The desorption water extraction unit 200 includes an evaporator 240 and a crystal separation system 250, the evaporator 240 and the crystal separation system 250 are connected, the crystal separation system 250 includes a liquid inlet 251, a liquid outlet 252 and a solid outlet 253, the liquid inlet 251 of the crystal separation system 250 is connected to the extraction tail liquid outlet 220 of the evaporator 240, and another part 1" of the original brine to be treated and / or part of the adsorption tail liquid of the ion exchange adsorption unit 100 are evaporated and concentrated in the evaporator 240 to form The tail liquid is extracted, and the crystallization separation system 250 performs crystallization separation on the tail liquid to obtain a lithium-containing concentrated solution and a crystallized salt mixture; the liquid outlet 252 is connected to the feed pretreatment unit 400, and the lithium-containing concentrated solution flows out from the liquid outlet 252 and enters the feed pretreatment unit 400; the solid outlet 253 is connected to the solid inlet 350 of the recovery unit 300, and the crystallized salt mixture discharged from the solid outlet 253 enters the recovery unit 300 via the solid inlet 350, and the recovery unit 300 performs elution recovery treatment on the crystallized salt mixture.

[0022] According to some embodiments of the present invention, reference Figures 2 to 5 The recovery unit 300 is connected to the feed pretreatment unit 400, the lithium-rich solution outlet 310 of the recovery unit is connected to the feed pretreatment unit 400, and the liquid outlet 252 is connected to the feed pretreatment unit 400. The recovery unit processes the crystallized salt mixture to obtain a lithium-rich solution, the lithium-rich solution enters the feed pretreatment unit for further processing, and the lithium-containing concentrated solution flows out from the liquid outlet and enters the feed pretreatment unit for further processing. Thus, the raw brine processing system can further process the lithium-rich solution and the lithium-containing concentrated solution, thereby further improving the recovery rate of lithium in the raw brine.

[0023] According to some embodiments of the present invention, reference Figure 2 The lithium-rich solution outlet 310 and the liquid outlet 252 of the recovery unit can be connected to different feed ports of the feed pretreatment unit 400, respectively, and the lithium-rich solution and the lithium-containing concentrated solution enter the feed pretreatment unit from different feed ports. According to other embodiments of the present invention, refer to Figures 3 to 5The lithium-rich solution of the recovery unit 300 and the lithium-containing concentrated solution of the desorption water extraction unit 200 can be combined before entering the feed pretreatment unit 400.

[0024] According to some embodiments of the present invention, reference Figure 4 and Figure 5 The feed pretreatment unit 400 may include a feed tank 420 and a filter 430 connected in sequence, wherein the filter 430 is connected to the ion exchange adsorption unit 100 and the desorption water extraction unit 200, that is, after the original brine 1 is processed by the feed tank 420 and the filter 430 in sequence, it is divided into two parts and enters the ion exchange adsorption unit 100 and the desorption water extraction unit 200 respectively.

[0025] According to some embodiments of the present invention, reference Figure 4 and Figure 5 The feed tank 420 has a stirrer 421, so that the raw brine can be stirred in the feed tank, making the raw brine more uniform, which is beneficial for subsequent processing and can reduce the load on the filter.

[0026] According to an embodiment of the present invention, the filter 430 may be a security filter, a bag filter, a filter screen or other filter components, as long as it can filter the material well.

[0027] According to an embodiment of the present invention, referring to Figure 4 and Figure 5 A second diverter valve 3 is provided between the feed pretreatment unit 400 and the ion exchange adsorption unit 100 and the desorption water extraction unit 200 , so that the diversion ratio of the material entering the ion exchange adsorption unit 100 and the desorption water extraction unit 200 is adjusted by the second diverter valve 3 .

[0028] According to some embodiments of the present invention, reference Figure 4 and Figure 5The desorption water extraction unit 200 may further include a preheater 230 and a reverse osmosis component 260, wherein the preheater 230 is connected to the evaporator 240 and the reverse osmosis component 260, and the reverse osmosis component 260 is connected to the desorption process 112. The desorption water extraction unit 200 may preheat the material entering the preheater 230, thereby realizing the preheating of the evaporator feed, saving the energy input of the preheating heat source, and also cooling the high-temperature condensed water to the applicable temperature of the reverse osmosis component; the evaporator 240 is an important component for extracting desorption water, and the high-temperature condensed water generated in the evaporator 240 enters the preheater 230 and can be used to preheat the material. After the high-temperature condensed water is preheated by the preheater 230, the temperature is reduced to form low-temperature condensed water. The low-temperature condensed water flows out of the preheater 230 and enters the reverse osmosis component 260 for multiple reverse osmosis to form The desorption water enters the desorption process 112; after the material is preheated in the preheater 230, it enters the evaporator 240 for evaporation and concentration, and then enters the crystallization separation system 250 for crystallization separation to obtain a crystalline salt mixture and a lithium-containing concentrated liquid. After that, the crystalline salt mixture is discharged from the solid outlet 253 and enters the recovery unit 300 through the solid inlet 350 for elution and recovery treatment, and the lithium-containing concentrated liquid flows out from the liquid outlet 252 and enters the feed pretreatment unit 400. The lithium-containing concentrated liquid can be used as a raw material and is processed again by the raw brine treatment system to improve the overall utilization rate of the raw brine and the recovery rate of lithium.

[0029] According to some embodiments of the present invention, the preheater 230 can be a shell and tube heat exchanger, a shell and tube heat exchanger or a plate heat exchanger. The above types of heat exchangers can preheat the material and can fully utilize the high-temperature condensed water in the evaporator for preheating.

[0030] According to some embodiments of the present invention, the evaporator 240 can be a steam mechanical recompression (MVR) component or a multiple-effect evaporator, whereby the evaporator can better evaporate and concentrate the material, so that the solid and liquid are better separated, thereby obtaining more high-temperature condensed water that can be used for preheating and a crystalline salt mixture with less water content.

[0031] According to some embodiments of the present invention, a waste heat exchanger may be provided inside the evaporator 240, whereby the evaporator can fully realize waste heat recovery and energy cascade utilization through the waste heat exchanger, etc., so as to reduce the use of external heat sources. Taking the evaporator as a steam mechanical recompression (MVR) component as an example, during the evaporator startup phase, an external steam heat source is required to start the evaporator. As the startup phase proceeds, the steam consumption continues to decrease. When the evaporator operates normally, the steam consumption will stabilize at the lowest level or the external steam heat source can be completely cut off.

[0032] According to some embodiments of the present invention, the crystallization separation system 250 may include a thickener, a centrifuge and a discharge pump, which are connected in sequence, thereby achieving full separation of solid and liquid through centrifugal separation to obtain a crystallized salt mixture with less water content.

[0033] According to some embodiments of the present invention, the reverse osmosis component 260 can be a three-stage reverse osmosis component, a four-stage reverse osmosis component or a five-stage reverse osmosis component, so that the reverse osmosis component 260 can perform multiple reverse osmosis treatments on the low-temperature condensed water to obtain more desorption water that meets the use requirements.

[0034] According to some embodiments of the present invention, the reverse osmosis component 260 may use a low-pressure reverse osmosis membrane to reduce the operating energy consumption of the reverse osmosis component.

[0035] According to some embodiments of the present invention, a switch is provided between the ion exchange adsorption unit 100 and the recovery unit 300. According to some specific embodiments of the present invention, a switch can be provided between the ion exchange adsorption unit and the recovery unit separately to control the on-off of the flow path between the ion exchange adsorption unit and the recovery unit. According to other specific embodiments of the present invention, the port connecting the first diverter valve 2 and the recovery unit 300 can also be used as a switch to control the on-off of the flow path.

[0036] According to some other embodiments of the present invention, Figure 6 The recovery unit 300 may include a rinsing liquid tank 320, a spray assembly 330 and a transmission assembly 340. The rinsing liquid tank 320 and the ion exchange adsorption unit ( Figure 6 ), the conveying assembly 340 is connected to the desorption water extraction unit ( Figure 6 The recycling unit 340 is connected to the elution tank 320 (not shown in the figure), the spray component 330 and the conveying component 340 are respectively connected to the elution tank 320. The crystallized salt mixture can be fully eluted by the recovery unit to obtain a lithium-rich solution which is recovered to the feed pretreatment unit for use as a raw material. Moreover, the recovery unit can continuously process the crystallized salt mixture without interruption. In addition, the conveying component can be a conveyor belt, and the spray component can elute a large amount of crystallized salt mixture on the conveyor belt, so that the elution recovery efficiency is higher.

[0037] In another aspect of the present invention, the present invention provides a method for raw halogen treatment using the raw halogen treatment system described above. According to an embodiment of the present invention, the method for raw halogen treatment using the raw halogen treatment system described above comprises the following steps:

[0038] S100: a part of the original brine to be treated enters the adsorption tower of the ion exchange adsorption unit, and enters the desorption step for desorption after being subjected to adsorption treatment in the adsorption step of the adsorption tower. The desorption step desorbs the lithium salt in the adsorption tower, and a qualified liquid is obtained after the desorption treatment.

[0039] According to an embodiment of the present invention, referring to Figures 1 to 5 A portion 1' of the original brine to be treated enters the adsorption tower 110 of the ion exchange adsorption unit 100, and after being adsorbed by the adsorption process 111 of the adsorption tower 110, enters the desorption process 112 for desorption treatment, and after the desorption treatment, a qualified liquid 11 is obtained, and the qualified liquid 11 can enter the subsequent device for lithium extraction from the salt lake for subsequent treatment.

[0040] S200: A part of the adsorption tail liquid formed after the original brine is adsorbed and treated in the adsorption process enters the desorption water extraction unit, and the other part of the original brine to be treated also enters the desorption water extraction unit. After the adsorption tail liquid and the original brine are treated in the desorption water extraction unit, a mixture of desorption water and crystallized salt is obtained, and the desorption water enters the desorption process.

[0041] According to an embodiment of the present invention, referring to Figures 1 to 5 After the adsorption process 111 adsorbs and treats the original brine to form an adsorption tail liquid 4, a part of the adsorption tail liquid 4' enters the desorption water extraction unit 200, and another part 1" of the original brine to be treated also enters the desorption water extraction unit. After the adsorption tail liquid and the original brine are treated by the desorption water extraction unit 200, desorption water 6 and a crystalline salt mixture 9 are obtained. The desorption water 6 enters the desorption process 112 to desorb the lithium salt in the adsorption tower.

[0042] According to some embodiments of the present invention, the raw brine 1 to be treated first enters the feed pretreatment unit 400 for stirring and filtering, and then enters the ion exchange adsorption unit 100 and the desorption water extraction unit 200. This can help improve the treatment effect of the raw brine and improve the efficiency of the ion exchange adsorption unit and the desorption water extraction unit in treating the raw brine.

[0043] According to some specific embodiments of the present invention, Figure 5In the adsorption process 111, a part of the adsorption tail liquid formed after the original brine is adsorbed and another part of the original brine to be treated enters the preheater 230 of the desorption water extraction unit 200 for preheating, and then enters the evaporator 240 for evaporation and concentration to produce high-temperature condensed water 5 and extracted tail liquid 8. The high-temperature condensed water 5 enters the preheater 230 to release heat and produces low-temperature condensed water 5' which enters the reverse osmosis component 260. The low-temperature condensed water 5' is desalted in the reverse osmosis component 260 to form desorption water 6 and waste liquid 7. The desorption water 6 enters the desorption process 112 to desorb the lithium salt in the adsorption tower, and the waste liquid 7 is discharged; the extracted tail liquid 8 enters the crystallization separation system 250 for crystallization separation treatment to form a lithium-containing concentrated solution 10 and a crystallized salt mixture 9. The lithium-containing concentrated solution 10 enters the feed pretreatment unit 400, and the crystallized salt mixture 9 enters the recovery unit 300 for elution recovery treatment. The elution recovery treatment can fully recover the lithium-rich solution that has not been separated in the crystallized salt mixture 9.

[0044] According to some embodiments of the present invention, the diversion ratio of the material entering the ion exchange adsorption unit 100 and the material entering the desorption water extraction unit 200 is 1:1.2-1:0.9, for example, it can be 1:1.2, 1:1.1, 1:1.0, 1:0.9, etc., which can be specifically controlled by adjusting the second diverter valve 3. More specifically, it can be determined according to factors such as the specific composition of the original brine, the evaporation amount of the evaporator, and the diversion condition of the first diverter valve 2. Therefore, setting the above-mentioned diversion ratio can make the ion exchange adsorption unit and the desorption water extraction unit better matched, thereby improving the system's treatment effect on the original brine.

[0045] According to an embodiment of the present invention, the preheater 230 has a cold side inlet, a cold side outlet, a hot side inlet and a hot side outlet, wherein the cold side inlet is the feed inlet for the raw brine etc. to enter the preheater, the cold side outlet is the discharge port for the material in the preheater to enter the evaporator, the hot side inlet is the feed inlet for the high-temperature condensed water to enter the preheater, and the hot side outlet is the discharge port for the low-temperature condensed water to flow out of the preheater.

[0046] According to some embodiments of the present invention, the temperature of the cold side inlet of the preheater 230 can be 15°C-27°C, for example, 15°C, 18°C, 20°C, 23°C, 25°C, 27°C, etc. The specific temperature depends on the temperature of the original brine.

[0047] According to some embodiments of the present invention, the temperature of the cold side outlet of the preheater 230 can be 95°C-105°C, for example, 95°C, 98°C, 100°C, 103°C, 105°C, etc. The specific temperature depends on the temperature and flow rate of the high-temperature condensed water 5, which can be obtained through heat balance calculation.

[0048] According to some embodiments of the present invention, the temperature of the high-temperature condensed water 5 at the hot side inlet of the preheater 230 can be 100°C-110°C, for example, 100°C, 102°C, 105°C, 107°C, 110°C, etc. The specific temperature depends on the operating parameters of the evaporator, that is, the operating parameters of the evaporator can be adjusted and set to make the high-temperature condensed water have a suitable temperature or temperature range.

[0049] According to some embodiments of the present invention, the temperature of the hot side outlet of the preheater 230 may be 25°C-30°C, for example, 25°C, 27°C, 28°C, 30°C, etc.

[0050] By setting the temperature of the cold side inlet of the preheater, the temperature of the cold side outlet, the high-temperature condensed water at the hot side inlet, and the temperature of the hot side outlet to each within an appropriate temperature range, the thermal energy can be fully utilized without damaging the membrane in the reverse osmosis component, thereby extending the service life of the reverse osmosis component.

[0051] According to some embodiments of the present invention, the evaporation amount of each ton of feed in the evaporator 240 is 400 kg-600 kg of distilled water, and the conductivity of the distilled water is 50μs / cm-100μs / cm, for example, it can be 50μs / cm, 60μs / cm, 70μs / cm, 80μs / cm, 90μs / cm, 100μs / cm, etc., thereby, the evaporator can generate sufficient distilled water for preheating treatment of the preheater, thereby reducing the use of external steam heat source; the distilled water has a lower conductivity and a lower conductive ion content, which is more conducive to obtaining desorption water through subsequent reverse osmosis treatment.

[0052] According to some embodiments of the present invention, the electrical conductivity of the low-temperature condensed water 5 ′ is 50 μs / cm-100 μs / cm, for example, 50 μs / cm, 60 μs / cm, 70 μs / cm, 80 μs / cm, 90 μs / cm, 100 μs / cm, etc.

[0053] According to some embodiments of the present invention, the conductivity of the waste liquid 7 can be 500μs / cm-2000μs / cm, for example, it can be 500μs / cm, 800μs / cm, 1000μs / cm, 1200μs / cm, 1500μs / cm, 2000μs / cm, etc. After the reverse osmosis component performs reverse osmosis treatment on the low-temperature condensed water, the waste liquid and the desorption water that can be used to desorb the lithium salt in the adsorption tower are well separated.

[0054] According to an embodiment of the present invention, the recovery rate of the low-temperature condensed water 5' can be 90%-95%, for example, it can be 90%, 91%, 92%, 93%, 94%, 95%, etc., that is, after the reverse osmosis treatment by the reverse osmosis component 260, the mass of the desorption water 6 obtained is 90%-95% of the mass of the low-temperature condensed water 5' entering the reverse osmosis component 260. The recovery rate is relatively high, and a large amount of desorption water can be generated for desorption treatment in the desorption process.

[0055] According to an embodiment of the present invention, the water content of the crystallized salt mixture 9 can be 5%-12%, for example, 5%, 7%, 9%, 10%, 12%, etc. After being processed by the crystallization separation system, the water content of the crystallized salt mixture can be reduced, which is convenient for subsequent elution and recovery treatment.

[0056] According to an embodiment of the present invention, the conductivity of the desorption water is below 50μs / cm, that is, the conductivity of the desorption water is less than 50μs / cm. For example, the conductivity of the desorption water may be 45μs / cm, 40μs / cm, 35μs / cm, 30μs / cm, 25μs / cm, 20μs / cm, 10μs / cm, etc. The desorption water contains less conductive ions and can be used for desorption of lithium salts in the adsorption tower, and has a better desorption effect.

[0057] S300: The other part of the adsorption tail liquid formed after the adsorption of the original brine enters the recovery unit, and the crystallized salt mixture enters the recovery unit. The adsorption tail liquid in the recovery unit is used to rinse and recover the crystallized salt mixture.

[0058] According to an embodiment of the present invention, another part of the adsorption tail liquid 4" formed after the adsorption process 111 adsorbs the original brine enters the recovery unit 300, and the crystallized salt mixture 9 separated by the desorption water extraction unit enters the recovery unit 300, and the adsorption tail liquid in the recovery unit 300 is used to rinse and recover the crystallized salt mixture 9.

[0059] According to an embodiment of the present invention, referring to Figure 5, the crystallized salt mixture 9 enters the recovery unit 300 for elution recovery to form a lithium-rich solution 12 and a waste crystallized salt mixture 13, the lithium-rich solution 12 enters the feed pretreatment unit 400, and the waste crystallized salt mixture 13 is discharged. It should be noted that the lithium-rich solution 12 and the lithium-containing concentrated solution 10 can enter the feed pretreatment unit 400 through different pipelines respectively, and the lithium-rich solution 12 and the lithium-containing concentrated solution 10 can also be first merged and then enter the feed pretreatment unit through the same pipeline. It should also be noted that the lithium-rich solution 12 and the lithium-containing concentrated solution 10 can enter the feed tank 420 and the filter 430 of the feed pretreatment unit 400 in sequence, and the original brine 1 and the lithium-rich solution 12 and the lithium-containing concentrated solution 10 enter the feed tank, and can be discharged after stirring to ensure uniform composition and temperature. In addition, a small amount of crystallized salt particles may be entrained in the lithium-rich solution and the lithium-containing concentrated solution. The stirring treatment can fully dissolve the crystallized salt particles to reduce the load on the filter.

[0060] According to some embodiments of the present invention, the raw brine 1 and / or lithium-containing concentrated solution 10 and / or lithium-rich solution 12 to be treated enters the feed tank 420 and is stirred for 15 minutes to 30 minutes, for example, 15 minutes, 18 minutes, 20 minutes, 23 minutes, 25 minutes, 27 minutes, 30 minutes, etc., thereby making the composition and temperature uniform after stirring, and making the crystalline salt particles that may be entrained fully dissolved, thereby reducing the load on the filter.

[0061] According to some embodiments of the present invention, when the crystallized salt mixture is eluted and recovered, an intermittent operation method can be used to close the switch between the ion exchange adsorption unit 100 and the recovery unit 300 to cut off the flow path between the ion exchange adsorption unit 100 and the recovery unit 300. Specifically, the flow path from the first diverter valve 2 to the recovery unit can be cut off. According to some embodiments of the present invention, the recovery unit 300 has a centrifuge, which can centrifuge the mixture of the crystallized salt mixture and the adsorption tail liquid, and the adsorption tail liquid can be circulated in the recovery unit for 3-8 times to fully enrich and absorb the concentrated lithium solution remaining in the crystallized salt mixture. According to some embodiments of the present invention, the total time for eluting and recovering the crystallized salt mixture is 20 minutes to 60 minutes. For example, the adsorption tail liquid can be circulated in the recovery unit for 20 minutes, 30 minutes, 50 minutes, 60 minutes, etc., thereby ensuring more sufficient enrichment and absorption of the concentrated lithium solution remaining in the crystallized salt mixture, thereby further improving the utilization rate of the raw materials and the recovery rate of lithium.

[0062] According to other embodiments of the present invention, it is also possible to use Figure 6 The recovery unit in the process uses a continuous treatment method to wash and recover the crystallized salt mixture. Figure 6When the recovery unit shown in the figure performs elution and recovery treatment on the crystallized salt mixture, another part 4" of the adsorption tail liquid enters the eluent tank 320, and then enters the spray assembly 330. The crystallized salt mixture 9 falls onto the conveying assembly 340, and the crystallized salt mixture 9 is eluted and recovered by the spray assembly 330. The adsorption tail liquid in the eluent tank 320 can also repeatedly elute the crystallized salt mixture 9 until the lithium content in the adsorption tail liquid reaches a certain proportion. The obtained lithium-rich solution 12 is first returned to the eluent tank 320, and then enters the feed tank 420 of the feed pretreatment unit 400 for use as a raw material, and the waste crystallized salt mixture 13 is discharged from the system.

[0063] According to some embodiments of the present invention, when the recovery unit 300 needs to adsorb tail liquid, the diversion ratio of the adsorption tail liquid entering the desorption water extraction unit 200 and the adsorption tail liquid entering the recovery unit 300 is 10:1-25:1, for example, it can be 10:1, 13:1, 15:1, 18:1, 20:1, 22:1, 25:1, etc., which can be specifically controlled by the first diverter valve 2. Thus, the adsorption tail liquid can be more fully utilized to extract desorption water and elute the crystallized salt mixture, thereby further reducing the use of external steam heat source and further improving the elution efficiency of the crystallized salt mixture.

[0064] In general, the raw brine treatment system proposed by the present invention has the following advantages: (1) It can realize the recycling of adsorption tail liquid. The liquid that needs to be discharged from the entire system is only the waste liquid generated by the reverse osmosis component. The liquid discharge volume is only 1%-5% of the adsorption tail liquid discharge volume in the traditional process. The liquid discharge volume can be reduced by 95%-99%, breaking through the restriction of adsorption tail liquid discharge and solving the problem of difficulty in discharging adsorption tail liquid. (2) The mixed liquid of raw brine and adsorption tail liquid is evaporated and concentrated by an evaporator, and sufficient desorption water can be directly obtained from the mixed liquid of raw brine and adsorption tail liquid, thereby solving the problem of supply of desorption water and the problem of difficulty in obtaining desorption water in the process of salt lake lithium extraction plant. (3) Compared with the traditional method of utilizing raw brine, the recycling of adsorption tail liquid in the present invention can increase the lithium recovery rate of raw brine by 2%-5% without affecting the adsorption efficiency of ion exchange adsorption unit.

[0065] In the description of this specification, the description with reference to the terms "one embodiment", "another embodiment", "yet another embodiment", "some embodiments", "other embodiments", "some specific embodiments" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory. In addition, it should be noted that in this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0066] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A raw brine treatment system suitable for extracting lithium from salt lakes, characterized in that: include: An ion exchange adsorption unit, wherein the ion exchange adsorption unit comprises one or more adsorption towers filled with adsorbents, a portion of the original brine to be treated enters the adsorption process of the adsorption tower for adsorption treatment, and then is desorbed with desorption water in the desorption process of the adsorption tower; A desorption water extraction unit, another part of the original brine to be treated and / or part of the adsorption tail liquid of the ion exchange adsorption unit enters the desorption water extraction unit, the desorption water extraction unit extracts desorption water from the original brine and / or adsorption tail liquid entering the desorption water extraction unit, and the desorption water extraction unit is connected to the ion exchange adsorption unit so that the extracted desorption water enters the desorption process to desorb the lithium salt in the adsorption tower; A recovery unit, wherein the recovery unit is connected to the adsorption process of the ion exchange adsorption unit and the desorption water extraction unit; A feed pretreatment unit, wherein the feed pretreatment unit is connected to both the ion exchange adsorption unit and the desorption water extraction unit, and the discharge port of the feed pretreatment unit is respectively connected to the feed port of the ion exchange adsorption unit and the feed port of the desorption water extraction unit; The desorption water extraction unit comprises an evaporator and a crystallization separation system, and the crystallization separation system comprises a liquid inlet, a liquid outlet and a solid outlet; The liquid inlet of the crystallization separation system is connected to the extraction tail liquid outlet of the evaporator; Another part of the original brine to be treated and / or part of the adsorption tail liquid of the ion exchange adsorption unit is evaporated and concentrated in the evaporator to form an extraction tail liquid, and the crystallization separation system performs crystallization separation on the extraction tail liquid to obtain a lithium-containing concentrated liquid and a crystalline salt mixture; the liquid outlet is connected to the feed pretreatment unit, and the lithium-containing concentrated liquid flows out of the liquid outlet and enters the feed pretreatment unit, and the solid outlet is connected to the solid inlet of the recovery unit, and the crystalline salt mixture discharged from the solid outlet enters the recovery unit via the solid inlet.

2. The raw brine treatment system according to claim 1, characterized in that: The desorption water extraction unit is connected to the ion exchange adsorption unit so that part of the adsorption tail liquid in the ion exchange adsorption unit enters the desorption water extraction unit.

3. The raw brine treatment system according to claim 1, characterized in that: The recovery unit processes the crystallized salt mixture to obtain a lithium-rich solution, and an outlet of the lithium-rich solution of the recovery unit is connected to the feed pretreatment unit.

4. The raw brine treatment system according to claim 3, characterized in that: The lithium-rich solution and the lithium-containing concentrated solution are combined and then enter the feed pretreatment unit.

5. The raw brine treatment system according to claim 1, characterized in that: The feed pretreatment unit comprises a feed tank and a filter which are connected in sequence, and the filter is connected to the ion exchange adsorption unit and the desorption water extraction unit.

6. The raw brine treatment system according to claim 5, characterized in that: The feed tank has a stirrer.

7. The raw brine treatment system according to claim 1, characterized in that: The desorption water extraction unit further comprises a preheater and a reverse osmosis component, wherein the preheater is connected to the evaporator and the reverse osmosis component, and the reverse osmosis component is connected to the desorption process.

8. The raw brine treatment system according to claim 7, characterized in that: At least one of the following conditions is met: The preheater is a shell and tube heat exchanger, a shell and tube heat exchanger or a plate heat exchanger; The evaporator is a steam mechanical recompression assembly or a multiple-effect evaporator; A waste heat exchanger is arranged inside the evaporator; The crystallization separation system comprises a thickener, a centrifuge and a discharge pump; The reverse osmosis component is a three-stage reverse osmosis component, a four-stage reverse osmosis component or a five-stage reverse osmosis component.

9. The raw brine treatment system according to any one of claims 1 to 8, characterized in that: A switch is provided between the ion exchange adsorption unit and the recovery unit.

10. The raw brine treatment system according to any one of claims 1 to 8, characterized in that: The recovery unit comprises a leaching liquid tank, a spray assembly and a conveying assembly. The leaching liquid tank is connected to the ion exchange adsorption unit, the conveying assembly is connected to the desorption water extraction unit, and the spray assembly and the conveying assembly are respectively connected to the leaching liquid tank.

11. A method for raw halogen treatment using the raw halogen treatment system according to any one of claims 1 to 10, characterized in that: include: A portion of the original brine to be treated enters the adsorption tower of the ion exchange adsorption unit, and enters the desorption process after being subjected to adsorption treatment in the adsorption process of the adsorption tower. The desorption process desorbs the lithium salt in the adsorption tower to obtain a qualified liquid after the desorption treatment; A part of the adsorption tail liquid formed after the adsorption process adsorbs and treats the original brine enters the desorption water extraction unit, and another part of the original brine to be treated also enters the desorption water extraction unit. The adsorption tail liquid and the original brine are treated by the desorption water extraction unit to obtain a mixture of desorption water and crystallized salt. The desorption water enters the desorption process. Another part of the adsorption tail liquid formed after the adsorption process adsorbs the original brine enters the recovery unit, and the crystallized salt mixture enters the recovery unit. The adsorption tail liquid in the recovery unit is used to rinse and recover the crystallized salt mixture.

12. The method according to claim 11, characterized in that The raw brine to be treated enters the feed pretreatment unit for stirring and filtering, and then enters the ion exchange adsorption unit and the desorption water extraction unit.

13. The method according to claim 12, characterized in that A part of the adsorption tail liquid formed after the adsorption process adsorbs the original brine and another part of the original brine to be treated enter the preheater of the desorption water extraction unit for preheating, and then enter the evaporator for evaporation and concentration to produce high-temperature condensed water and lithium extraction tail liquid. The high-temperature condensed water enters the preheater to release heat and the low-temperature condensed water generated enters the reverse osmosis component of the desorption water extraction unit. The low-temperature condensed water is desalted in the reverse osmosis component to form the desorption water and waste liquid, and the waste liquid is discharged. The lithium extraction tail liquid enters the crystallization separation system of the desorption water extraction unit, and the crystallization separation system forms a lithium-containing concentrated solution and a crystallized salt mixture after crystallization separation on the lithium extraction tail liquid. The lithium-containing concentrated solution enters the feed pretreatment unit, and the crystallized salt mixture enters the recovery unit for elution recovery to form a lithium-rich solution and a waste crystallized salt mixture. The lithium-rich solution enters the feed pretreatment unit, and the waste crystallized salt mixture is discharged.

14. The method according to claim 13, characterized in that At least one of the following conditions is met: The temperature of the cold side inlet of the preheater is 15℃-27℃; The temperature of the cold side outlet of the preheater is 95°C-105°C; The temperature of the high-temperature condensed water at the hot side inlet of the preheater is 100°C-110°C; The temperature of the hot side outlet of the preheater is 25°C-30°C; The evaporation amount per ton of feed in the evaporator is 400 kg-600 kg of distilled water, and the conductivity of the distilled water is 50 μs / cm-100 μs / cm; The electrical conductivity of the low-temperature condensed water is 50 μs / cm-100 μs / cm; The electrical conductivity of the waste liquid is 500 μs / cm-2000 μs / cm; The recovery rate of the low-temperature condensed water is 90%-95%; The water content of the crystalline salt mixture is 5%-12%; The electrical conductivity of the desorption water is 50 μs / cm or less.

15. The method according to any one of claims 11 to 13, characterized in that: The original brine and / or lithium-containing concentrated solution and / or lithium-rich solution to be treated enters the feed tank and is stirred for 15 minutes to 30 minutes.

16. The method according to claim 13, characterized in that When the crystallized salt mixture is eluted and recovered, the switch between the ion exchange adsorption unit and the recovery unit is closed to cut off the flow path between the ion exchange adsorption unit and the recovery unit.

17. The method according to claim 13, characterized in that At least one of the following conditions is met: The total time for eluting and recovering the crystalline salt mixture is 20 minutes to 60 minutes; When the recovery unit needs to adsorb tail liquid, the split ratio of the adsorption tail liquid entering the desorption water extraction unit and the adsorption tail liquid entering the recovery unit is 10:1-25:1; The split ratio of the material entering the ion exchange adsorption unit and the material entering the desorption water extraction unit is 1:1.2-1:0.9.

Images