Method for extracting lithium from brine based on multi-stage CCIX combined system

Abstract

The invention relates to a method for extracting lithium from brine based on a multistage CCIX combined system, and belongs to the technical field of chemical processes. An adsorption section procedure for extracting lithium from brine is divided into three areas A, B and C, and each area adopts a CCIX continuous ion exchange system, so that efficient lithium extraction is realized. The area A is used for adsorbing pretreated raw halogen, the area B is used for secondary adsorption of tail liquid of the area A, and the area C is used for extracting lithium and removing impurities from desorption liquid of the area A and the area B. The technological process comprises the steps of pretreatment, adsorption, leaching, desorption and tail brine top water treatment, the lithium yield is increased through the aluminum-based lithium adsorbent, and meanwhile impurity ions are reduced. The final product can be lithium carbonate or crude lithium chloride. The method is suitable for lithium extraction of salt lake brine and ore leaching brine. And by optimizing the process, the cost of rear-end membrane coupling and resin impurity removal is reduced, and the environmental protection pressure is reduced.

Description

Technical Field

[0001] The present invention relates to the field of chemical process technology, and in particular to a method for extracting lithium from brine based on a multi-stage CCIX combined system. Background Art

[0002] As the lightest metal, lithium holds an irreplaceable position in new energy, consumer electronics, and military applications. Currently, lithium resources primarily come from ores and salt lake extraction, with salt lake extraction being more cost-effective. However, traditional adsorption membrane coupling technology suffers from issues such as high lithium penetration and high impurity content, leading to high costs for subsequent membrane assembly and resin impurity removal, and the acid-base regeneration process poses environmental challenges.

[0003] CCIX (Continuous Countercurrent Ion Exchange) technology is an ion exchange technology that is widely used in water treatment, industrial wastewater purification, metal recovery and other chemical separation processes. However, when traditional methods are used to treat brine with high lithium concentration, the adsorption tail liquid still contains a considerable amount of lithium. Direct discharge will reduce the yield, and the high impurities in the desorption liquid will increase the subsequent processing costs.

[0004] RO (Reverse Osmosis) concentration is a membrane separation technology that uses a semipermeable membrane to remove solvent from a solution, thereby increasing the solute concentration. A resin combination refers to the use of a specific ion exchange resin or adsorbent combination to extract target ions from brine through selective adsorption. MVR (Mechanical Vapor Recompression) is a high-efficiency evaporation technology that uses a compressor to compress secondary vapor, converting it into steam that serves as a heat source to drive the evaporation and concentration of the solution.

[0005] The present invention uses an aluminum-based lithium adsorbent to perform secondary lithium extraction and impurity removal on the desorption liquid. The aluminum-based lithium adsorbent is a composite material based on aluminum hydroxide, whose surface is endowed with the ability to adsorb lithium ions through special chemical treatment or synthesis methods. The adsorption tail liquid is then recycled as a desorbent, improving lithium yield while reducing impurities such as calcium, magnesium, and boron, lowering subsequent process costs and environmental pressures, achieving more efficient and economical lithium extraction from salt lakes.

[0006] In the prior art, for example, Chinese patent application number 2022114709709 discloses a method for extracting lithium from salt lake brine and controlling the impurity content of the desorption liquid. The shortcomings of this patent are that it relies on strong acid washing, which increases costs and environmental risks; it does not solve the problem of lithium loss in the tail liquid; the adsorbent has narrow adaptability and cannot process brine with a high magnesium-to-lithium ratio. Summary of the Invention

[0007] Based on the above analysis, the present invention provides a method for extracting lithium from brine based on a multi-stage CCIX combined system. The specific implementation scheme is as follows: A method for extracting lithium from brine based on a multi-stage CCIX combined system comprises the following steps:

[0008] S1: Pumping the raw brine into the CCIX system in area A for adsorption and lithium extraction, and the CCIX system in area A pumping out the desorption liquid in area A and the adsorption tail liquid in area A;

[0009] S2: pumping the desorption liquid from zone A into the CCIX system in zone C for adsorption and lithium extraction, and the CCIX system in zone C pumping out the desorption liquid from zone C and the adsorption tail liquid from zone C;

[0010] S3: Using the adsorption tail liquid of zone C as a desorbent of the CCIX system of zone A, and preparing lithium salt through the desorption liquid of the CCIX of zone C.

[0011] First, the CCIX system undergoes a graded treatment process, where lithium from the raw brine is gradually adsorbed. Zone A processes the raw brine. The desorbed liquid from Zone A is then pumped into Zone C for lithium extraction. The adsorbed tail liquid from Zone C is reused as the desorbent in Zone A, reducing desorbent usage and saving costs. Ultimately, the desorbed liquid from Zone C is used to produce high-purity lithium salts to meet industrial needs.

[0012] Preferably, the raw brine in S1 needs to be pretreated before entering the CCIX system in area A. The pretreatment includes ultrafiltration and pH adjustment. The ultrafiltration includes removing insoluble impurities. The pH adjustment includes adjusting the pH value of the raw brine to 5-7.5 with hydrochloric acid or alkali.

[0013] Ultrafiltration removes insoluble impurities from the raw brine, preventing them from depositing or clogging equipment in the subsequent CCIX system, thereby extending equipment life and reducing maintenance costs. Hydrochloric acid is used to adjust the pH of the raw brine to ensure it is between 5 and 7.5. Hydrochloric acid provides chloride ions, preventing performance degradation due to adsorbent poisoning and improving the reliability and efficiency of the lithium extraction process.

[0014] Preferably, if the lithium content of the adsorption tail liquid in zone A is less than 8% of the lithium content of the original brine, the adsorption tail liquid in zone A is reinjected or discharged into the lake, and the desorption liquid in zone A directly enters the CCIX system in zone C for lithium extraction, and the adsorption tail liquid in zone C is only used as a desorbent for the CCIX system in zone A; if the lithium content of the adsorption tail liquid in zone A is greater than 8% of the lithium content of the feed brine, the adsorption tail liquid in zone A is pumped into the CCIX system in zone B for adsorption and lithium extraction, and the CCIX system in zone B pumps out the desorption liquid and the adsorption tail liquid in zone B, and the adsorption tail liquid in zone B is reinjected or discharged into the lake, and the desorption liquid in zone A and the desorption liquid in zone B are mixed into a mixed desorption liquid in zones A and B and pumped into the CCIX system in zone C for adsorption and lithium extraction.

[0015] When the lithium content in the adsorption tail liquid of area A is less than 8% of the lithium content of the original halogen, it means that the residual lithium is close to the extraction limit. The amount of lithium recovered by continuing the adsorption and extraction process cannot cover the cost of further processing. Reinjection or lake discharge is selected to avoid unnecessary waste of resources and process complexity, saving operating costs. When the lithium content in the adsorption tail liquid of area A is greater than 8% of the lithium content of the original halogen, it means that a large proportion of lithium has not been extracted, and it is economically valuable to continue processing. The residual lithium can be further recovered by pumping the tail liquid into the CCIX system of area B for secondary adsorption.

[0016] Preferably, the CCIX system in area A, the CCIX system in area B and the CCIX system in area C include rotary valves and adsorption towers, the time for the rotary valve to rotate one circle is one cycle, and the number of valve switching times of the rotary valve in the cycle is equal to the number of the adsorption towers.

[0017] The CCIX system ensures orderly cycling between the adsorption towers through the cyclical rotation and switching of rotary valves. One rotary valve rotation is defined as a cycle, and the number of valve switches during a cycle equals the number of adsorption towers, allowing each tower to complete all steps sequentially. This design enables continuous system operation, rather than intermittent operation, improving production efficiency and equipment utilization.

[0018] Preferably, the CCIX system in zone A, the CCIX system in zone B and the CCIX system in zone C further include a pure water tank, and running one cycle requires four steps, namely adsorption-elution-desorption-tail brine top water, the adsorption step produces adsorption tail liquid, the elution step produces elution outlet liquid, and the desorption step produces desorption liquid; the tail brine top water refers to the residual desorption water contained in the adsorption tower that is replaced by tail brine and the residual desorption water is returned to the pure water tank containing the desorbent, and the tail brine top water produces tail brine top water outlet liquid.

[0019] Lithium separation and enrichment are achieved through adsorption and desorption steps. The tail brine topwater and rinsing steps ensure that any residual lithium is not wasted, and the adsorption tail liquid and discharge liquid can be further processed or recycled. The rinsing and topwater steps reduce impurity accumulation and contamination, extend the life of the adsorbent, and improve the purity of the desorption liquid, ensuring the quality of the lithium salt product.

[0020] Preferably, the elution discharge liquid of the CCIX system in zone A is mixed with the raw brine; the elution discharge liquid of the CCIX system in zone B is mixed with the adsorption tail liquid in zone A; the elution discharge liquid of the CCIX system in zone C in S3 is mixed with the mixed desorption liquid in zones A and B; the tail brine top water discharge liquid of the CCIX system in zone A and the tail brine top water discharge liquid of the CCIX system in zone B are respectively mixed with the adsorption tail liquid in zone C, and the tail brine top water discharge liquid of the CCIX system in zone C is mixed with the pure water tank in zone C.

[0021] The elution liquid contains a small amount of unadsorbed lithium ions. After mixing with the original brine, it re-enters the area A system for adsorption treatment to avoid waste of lithium resources. The elution liquid in area B also contains lithium ions, and the adsorption tail liquid in area A is a solution whose lithium content has been reduced after adsorption in area A, but there is still residual lithium. After the two are mixed, they enter the area B system as the original brine in area B to further adsorb and extract lithium. The elution liquid in area C contains lithium. After mixing with the mixed desorption liquid in areas A and B, it enters the area C system as the original brine in area C for further adsorption. The tail brine top water effluent from areas A and B contains residual brine, and the adsorption tail liquid in area C is a solution that still has residual lithium after adsorption in area C. After mixing the two, they can be recycled as desorbents in areas A and B. The tail brine top water effluent from area C contains lithium ions. It is mixed with the desorption liquid in area C to ensure that the lithium component is not lost.

[0022] Preferably, the desorption liquid in zone C is subjected to RO concentration, resin combination and MVR evaporation, and lithium carbonate is prepared through lithium precipitation, slurry washing, filtration, drying and powdering operations.

[0023] Through purification and treatment, the lithium ions in the desorption liquid in area C are converted into high-purity lithium carbonate products, meeting the purity and quality requirements of industrial applications.

[0024] Preferably, the desorption liquid in zone C can be produced into crude lithium chloride after MVR evaporation.

[0025] When boron content is high, directly producing high-purity lithium carbonate requires an additional boron removal step, which significantly increases process complexity and cost. Switching to producing crude lithium chloride can simplify the process and reduce additional processing costs.

[0026] Preferably, in the CCIX system of zone A, zone B and zone C, the pH of the desorbent is adjusted to 5 with hydrochloric acid before the desorption operation.

[0027] pH control is crucial for desorption efficiency, as different pH values ​​affect the efficiency of lithium ion desorption from the resin. The borate and sulfate ions loaded on the adsorbent after adsorption are desorbed off the column to prevent ion accumulation on the adsorbent, which can lead to deterioration of adsorbent performance.

[0028] Preferably, the resin combination comprises aminocarboxylic acid chelating resin and meglumine resin.

[0029] These two resins are highly selective and efficient, capable of removing common impurity ions in brine, ensuring the quality of the final product while reducing subsequent processing costs.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention divides the adsorption process of lithium extraction from brine into three zones, A, B, and C, and operates in a CCIX system combination. The desorption liquid produced by zone C ultimately contains fewer impurities, fundamentally reducing the operating cost and environmental pressure of the subsequent process.

[0032] 2. The desorption liquid after lithium extraction from the original brine in area A is used to extract lithium again in area C, and the resulting adsorption tail liquid is returned to area A for use as the desorbent. Since the tail liquid contains a certain amount of chloride salt, the probability of the aluminum-based adsorbent collapsing due to "over-desorption" is reduced.

[0033] 3. The process route of the present invention makes the impurity ion content in the desorption liquid sent to the subsequent process extremely low, and the subsequent process can selectively omit high-cost nanofiltration, electrodialysis or highly polluting resin combination.

[0034] 4. The technology of the present invention can be used to extract lithium from ores or from brine in salt lakes. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0036] Attachment Figure 1 Schematic diagram of the process of the present invention;

[0037] Attachment Figure 2 This is the pipe connection method of the CCIX system of the adsorption tower 30 of the present invention;

[0038] Attachment Figure 3 This is the partial piping connection method for the CCIX system of the 15 adsorption towers. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the added drawings and the described embodiments are only part of the present invention and do not represent the whole.

[0040] In the following examples, the aluminum-based lithium adsorbent used is from Example 3 of CN113578252B or a similar commercially available granular adsorbent with a particle size of 0.5 mm. The tail brine top-up, adsorption, and elution operations were performed at room temperature, while the desorption temperature was 40°C. BV represents bed volume.

[0041] Example 1

[0042] like Figure 1As shown, the brine used in this embodiment comes from the salt lake brine in the Atacama region of Chile. The brine enters the adsorption system after passing through the media filter. The test results before entering the adsorption system are shown in Table 1 below:

[0043]

[0044] Table 1

[0045] As shown in Table 1, the lithium ion concentration is greater than 1000ppm. The adsorption sections A, B, and C of the brine lithium extraction all adopt a continuous ion exchange system (CCIX system) combining a multi-channel rotary valve and a fixed bed, and each zone consists of four operating units: adsorption-elution-desorption-tail brine top water.

[0046] like Figure 2 As shown, area A belongs to the raw brine lithium extraction area, which consists of 30 fixed-bed adsorption columns, and each column is filled with 80% of the column volume of aluminum-based lithium adsorbent. The adsorption in area A adopts a three-in-one and four-in-one mode, and the elution adopts a single group of five columns in series. The desorption setting is the same as the adsorption, and the tail brine top water adopts a single group of single column operation.

[0047] like Figure 3 As shown, Area B belongs to the tail brine lithium extraction area of ​​Area A, which consists of 15 fixed-bed adsorption columns, each column is filled with 80% column volume of aluminum-based lithium adsorbent. The adsorption in Area B is operated in a three-in-two parallel mode, and the elution is operated in a single group of two columns in series. The desorption setting is the same as the adsorption, and the tail brine top water is operated in a single group of single columns.

[0048] like Figure 2 Zone C, shown here, is the lithium extraction and impurity removal zone for desorbing the mixed liquor from zones A and B. It consists of 30 fixed-bed adsorption columns, with each column or tank filled with 80% of the column volume of an aluminum-based lithium adsorbent. Adsorption in Zone C is operated using a three-in-series, four-in-parallel configuration, while elution is performed using a single set of five columns in series. Desorption is configured similarly to adsorption, and tail brine headwater is operated using a single set of single columns.

[0049] The adsorption unit in zone A consists of 12 adsorption columns in three series and four parallel configurations. The adsorption flow rate is set at 2BV / h. One cycle of adsorption is 3 hours, so 24BV of raw brine is adsorbed in one cycle. The switching frequency of the rotary valve in zone A is 0.25h / time (3h / 12 columns). The elution unit is equipped with 5 adsorption columns, which are operated in a single group in series. The rotary valve is switched 5 times in the elution zone, so the elution time for one cycle is 1.25h (0.25h / time*5 times). , set the elution flow rate to 4BV / h, then the elution water volume for one cycle is 5BV (1.25h*4BV / h); set the desorption flow rate to 1BV / h, and the other process operating parameters are the same as adsorption, and the desorption liquid for one cycle is 12BV; the tail brine top water is a single group of single columns, and the rotary valve is switched once, then the time for the tail brine top water is 0.25h, and the tail brine top water flow rate is set to 4BV / h, then the tail brine top water uses 1BV of tail brine; one operation cycle of area A is 7.5h.

[0050] The adsorption inlet water of zone B comes from 24BV of adsorption tail liquid of zone A. It is operated in a three-column series and two-group parallel mode. The adsorption flow rate is set at 4BV / h, so the adsorption time of zone B is 3h, and the frequency of switching of the rotary valve from the adsorption zone to zone B is 0.5h / time (3h / 6 columns); the elution operation consists of two columns in series, and the rotary valve switches twice in the elution zone. The elution time is 1h (0.5h / time*2 times). The elution flow rate is set at 2BV / h, and the elution water volume is 2BV; the desorption flow rate is set at 2BV / h, and the other process operating parameters are the same as adsorption, then the desorption liquid is 12BV; the tail brine top water is in a single group and a single column, the rotary valve is switched once, the tail brine top water time is 0.5h, and the tail brine top water flow rate is set at 2BV / h, then the tail brine top water uses 1BV tail brine; the operation time of one cycle of zone B is 7.5h.

[0051] For zone C, since the desorption mixed liquid in zones A and B is 24 BV in one cycle, the adsorption feed in zone C is 24 BV. If the process operating parameters of zone C are set to the same as those of zone A, the operating time of zone C in one cycle is 7.5 hours, and the desorption liquid obtained in the cycle is 24 BV.

[0052] After the operation of zones A, B, and C reaches a steady state, the desorption liquid in zone C is tested. The ion content of the desorption liquid in zone C is shown in Table 2 below:

[0053]

[0054] Table 2

[0055] The tail liquid of area B is the outlet liquid of the combined system. The lithium ion content affects the lithium extraction rate. The ion situation of the tail liquid of area B is shown in Table 3 below:

[0056]

[0057] Table 3

[0058] The total lithium ion yield of the entire system is calculated based on the lithium carried out by the tail liquid in area B:

[0059] (Total amount of raw lithium halide fed into zone A - lithium content in tail liquid of zone B) / total amount of raw lithium halide fed into zone A = (1221.59*24BV - 58.37*24BV) / 1221.59*24BV = 95.22%

[0060] Example 2

[0061] The brine used in this embodiment is the same as that in Example 1, except that the number of columns in Zone C of this embodiment is half of that in Zone C of Example 1.

[0062] The lithium ion concentration is greater than 1000ppm. The adsorption sections A, B, and C of brine lithium extraction all use a continuous ion exchange system (CCIX system) combining a multi-channel rotary valve and a fixed bed, and each zone consists of four operating units: adsorption-elution-desorption-tail brine top water.

[0063] Area A belongs to the raw brine lithium extraction area, which consists of 30 fixed-bed adsorption columns, and each column is filled with 80% of the column volume of aluminum-based adsorbent. The adsorption in Area A adopts a three-in-one and four-in-one mode, and the elution adopts a single group of five columns in series. The desorption setting is the same as the adsorption, and the tail brine top water adopts a single group of single column operation;

[0064] Area B, part of the tail brine lithium extraction area in Area A, consists of 15 fixed-bed adsorption columns, each filled with 80% of its column volume with aluminum-based adsorbent. Adsorption in Area B is operated using a three-in-one, two-in-one configuration, while elution is performed using a single set of two columns in series. Desorption is performed using the same setup as adsorption, while tail brine topwater is run using a single set of single columns.

[0065] Area C is the lithium extraction and impurity removal zone for desorbing the mixed liquor from Areas A and B. It consists of 15 fixed-bed adsorption columns, with each column or tank filled with 80% of the column volume of an aluminum-based lithium adsorbent. Adsorption in Area C is operated using a three-in-series, two-in-parallel configuration, while elution is performed using a single set of two columns in series. Desorption is configured similarly to adsorption, and tail brine topwater is operated using a single set of single columns.

[0066] The adsorption in area A adopts 12 adsorption columns in three series and four parallel, and the adsorption flow rate is set at 2BV / h. The adsorption is carried out for 3 hours in one cycle, so a total of 24BV of brine is adsorbed in one operation cycle. The switching frequency of the rotary valve in the entire area A is 0.25h / time (3h / 12 columns); 5 adsorption columns are set for elution, and a single group of series operation is adopted. The rotary valve is rotated and switched 5 times in the elution area, so the elution time for one cycle is 1.25h (0.25h / time * 5 times). The elution flow rate is set at 4BV / h, and the elution water volume is 5BV; the desorption flow rate is set at 1BV / h, and the other process operating parameters are the same as adsorption, so the desorption liquid is 12BV; the tail brine top water is a single group of single columns, and the rotary valve is switched once, so the tail brine top water time is 0.25h. The tail brine top water flow rate is set at 4BV / h, and the tail brine top water uses 1BV of tail brine; one operation cycle in area A is 7.5h.

[0067] The adsorption inlet of zone B comes from 24BV of adsorption tail liquid of zone A. It is operated in a three-in-two-parallel mode. The adsorption flow rate is set at 4BV / h, so zone B adsorbs for 3h, and the switching frequency of the rotary valve in zone B is 0.5h (3h / 6 columns) / time; the elution operation consists of two columns in series, and the rotary valve switches twice in the elution zone. The elution time for one cycle is 1h (0.5h / time * 2 times). The elution flow rate is set at 2BV / h, so the elution water volume is 2BV; the desorption flow rate is set at 2BV / h, and the other process operating parameters are the same as adsorption, then the desorption liquid is 12BV; the tail brine top water is single group and single column, the rotary valve is switched once, the tail brine top water time is 0.5h, and the tail brine top water flow rate is set at 2BV / h, then the tail brine top water uses 1BV tail brine, and the cycle operation time of zone B is 7.5h.

[0068] For zone C, since the desorption mixed liquid of zones A and B is 24BV, zone C adsorbs 24BV. The adsorption is operated in a three-in-two-parallel mode. The adsorption flow rate is set to 4BV / h, then the adsorption time is 3h, and the switching time of the rotary valve in zone C is 0.5h / time (3h / 6 columns); the elution is composed of two columns in series, and the rotary valve is switched twice during the elution operation. The elution time is 1h (0.5h / time*2 times), the elution flow rate is set to 2BV / h, and the elution water volume is 2BV; the desorption process operating parameters are set to be the same as the adsorption, then 24BV of water is used for desorption, and 24BV of desorption liquid is obtained; the tail brine top water is a single group and a single column, the rotary valve is switched once, the tail brine top water time is 0.5h, and the tail brine top water flow rate is set to 2BV / h, then 1BV of tail brine is used for the tail brine top water, and a cycle operation time of zone C is 7.5h to obtain 24BV of desorption eluent.

[0069] After the operation of zones A, B, and C reaches a steady state, the desorption eluent from zone C to the next process is detected. The ion content of the desorption eluent in zone C is shown in Table 4 below:

[0070]

[0071] Table 4

[0072] The adsorption tail liquid in area B is the outlet liquid of the combined system. The lithium ion content affects the overall lithium extraction rate. The ion situation of the tail liquid in area B is shown in Table 5 below:

[0073]

[0074] Table 5

[0075] The total lithium ion yield of the entire system is calculated based on the amount of lithium ions carried out by the tail liquid in area B:

[0076] (Total amount of raw lithium halide fed to area A - lithium content in tail liquid of area B) / total amount of raw lithium halide fed to area A = (1221.59*24BV - 76.32*24BV) / 1221.59*24BV = 93.75%

[0077] Example 3

[0078] This example uses brine from the intercrystalline brine in the Olaroz region of Argentina. The brine is pre-treated before entering the adsorption system. The test results before entering the adsorption system are as follows:

[0079]

[0080] Table 6

[0081] It can be seen from Table 6 that the lithium ion concentration of the original brine is lower than 1000ppm, and the lithium content of the adsorption tail liquid in area A is less than 8% of the lithium content of the original brine. Therefore, the adsorption section of lithium extraction from brine does not require area B, and only areas A and C are needed. Both areas use the CCIX continuous ion exchange system composed of a multi-channel rotary valve and a fixed bed, and are composed of four operating units: adsorption-elution-desorption-tail brine top water.

[0082] Area A belongs to the raw brine lithium extraction area, which consists of 30 fixed-bed adsorption columns, and each column is filled with 80% of the column volume of aluminum-based lithium adsorbent. The adsorption in Area A adopts a three-in-one and four-in-one mode, and the elution adopts a single group of five columns in series. The desorption setting is the same as the adsorption, and the tail brine top water adopts a single group of single column operation;

[0083] Area C, the lithium extraction and impurity removal zone for the desorbent from Area A, consists of 15 fixed-bed adsorption columns, with each column or tank filled with 80% of its volume of aluminum-based adsorbent. Adsorption in Area C utilizes three columns in series, with two groups operating in parallel. Elution utilizes a single group of two columns in series. Desorption is performed using the same setup as adsorption, while tail brine topwater is processed using a single column.

[0084] The adsorption in area A adopts 12 adsorption columns in three series and four parallel, and the adsorption flow rate is set at 4BV / h. The adsorption is carried out for 3 hours in one cycle. The switching frequency of the rotary valve of the CCIX system in the entire area A is 0.25h / time (3h / 12 columns), so 48BV of raw brine is adsorbed in one cycle; the elution unit has 5 adsorption columns, which are operated in a single group in series. The rotary valve rotates and switches 5 times in the elution area. The elution time for one cycle is 1.25h (0.25h / time * 5 times). The elution flow rate is set at 4BV / h, and the elution water volume is 5BV; the desorption flow rate is set at 2BV / h, and the other process operating parameters are the same as adsorption, so the desorption liquid is 24BV; the tail brine top water is in a single group and a single column, and the rotary valve is switched once, so the tail brine top water time is 0.25h. The tail brine top water flow rate is set at 4BV / h, so the tail brine top water uses 1BV of tail brine; the operation cycle time of area A is 7.5h.

[0085] Zone C adsorbs 24BV of desorption liquid from Zone A. Zone C uses 6 adsorption columns in three series and two parallel configurations for adsorption, with an adsorption flow rate of 4BV / h set and an adsorption cycle time of 3h. The adsorption operation results in a rotation frequency of the rotary valve in the entire Zone C of 0.5h / time (3h / 6 columns); the elution unit has two columns, which are operated in a single group in series. The rotary valve switches twice in the elution zone, with an elution time of 1h (0.5h / time*2 times). The elution flow rate is set at 2BV / h, and the elution water consumption is 2BV; the desorption process operating parameters are set to be the same as the adsorption, and the desorption water consumption is 24BV, resulting in 24BV of desorption liquid; the tail brine top water is a single group and single column, the rotary valve is switched once, the tail brine top water time is 0.5h, and the tail brine top water flow rate is set at 2BV / h, so the tail brine top water uses 1BV of tail brine. Zone C operates for 7.5h, and the eluent in Zone C is 24BV.

[0086] After the system operation of zones A and C reaches a stable state, the desorption liquid in zone C is tested. The ion situation of the desorption liquid in zone C is shown in Table 7 below:

[0087]

[0088] Table 7

[0089] The adsorption tail liquid in area A is used as the outlet liquid of the combined system. The lithium ion content affects the overall lithium extraction rate. The ion situation of the tail liquid in area A is shown in Table 8 below:

[0090]

[0091] Table 8

[0092] The total lithium ion yield of the entire system is calculated based on the amount of lithium ions carried out by the tail liquid in area A:

[0093] (Total amount of raw lithium halide fed into zone A - lithium content in tail liquid of zone A) / total amount of raw lithium halide fed into zone A = (564.23*48BV - 19.48*48BV) / 564.23*48BV = 96.5%

[0094] Example 4

[0095] The brine used in this embodiment is the same as that in Example 3, namely:

[0096] The lithium ion concentration is lower than 1000ppm, and the lithium content of the adsorption tail liquid in zone A is less than 8% of the lithium content of the original brine. The brine lithium extraction adsorption section omits zone B, and only zones A and C are required. Both zones use a continuous ion exchange system combining a multi-channel rotary valve and a fixed bed, and are composed of four operating units: adsorption-elution-desorption-tail brine top water.

[0097] Area A is the raw brine lithium extraction area and consists of 30 fixed-bed adsorption columns, with each column filled with 80% of its column volume of aluminum-based lithium adsorbent. Adsorption in Area A is operated in a three-in-one, four-in-one configuration, while elution is performed in a single set of five columns in series. The desorption setup is the same as for adsorption, and the tail brine topwater unit is operated in a single set of single columns.

[0098] Area C, the lithium extraction and impurity removal zone for the desorbent from Area A, consists of 30 fixed-bed adsorption columns, with each column or tank filled with 80% of its column volume, an aluminum-based adsorbent. Adsorption in Area C is operated using a three-in-series, four-in-parallel configuration, while elution utilizes a single set of five columns in series. Desorption is configured similarly to adsorption, while the tail brine topwater unit operates in a single set of single columns.

[0099] The adsorption unit in area A consists of 12 adsorption columns in three series and four parallel configurations. The adsorption flow rate is set at 4BV / h, and the adsorption time for one cycle is 3h. The rotary valve switching frequency of the CCIX system in area A is 0.25h / time (3h / 12 columns), and 48BV of raw brine is adsorbed in one cycle. The elution unit consists of 5 adsorption columns, which are operated in a single group in series. The rotary valve is rotated and switched 5 times in the elution zone, and the elution time is 1.25h (0.25h / time * 5 times). The elution flow rate is set at 4BV / h, and the elution water volume is 5BV. The desorption flow rate is set at 2BV / h, and the other process operating parameters are the same as adsorption, so 24BV of desorption liquid is obtained. The tail brine top water is a single group and a single column. The rotary valve is switched once, and the tail brine top water time is 0.25h. The tail brine top water flow rate is set at 4BV / h, and the tail brine top water uses 1BV of tail brine. Area A runs for one cycle of 7.5h.

[0100] Zone C adsorbs 24BV of desorption liquid from Zone A, wherein the adsorption is 12 adsorption columns, which are operated in a three-in-one and four-in-parallel manner, and the adsorption flow rate is set at 2BV / h. The time of the adsorption zone in one cycle is 3h, and the rotation frequency of the rotary valve in the entire Zone C, which is pushed out by the adsorption zone, is 0.25h / time (3h / 12 columns); the elution is performed on 5 adsorption columns, which are operated in a single group in series, and the rotary valve is switched 5 times in the elution zone, and the elution time is 1.25h (0.25h / time * 5 times). The elution flow rate is set at 4BV / h, and the elution water consumption is 5BV; the desorption process operating parameters are set to be the same as the adsorption, and 24BV of water is used in Zone C, and 24BV of desorption liquid is obtained; the tail brine top water is a single group and a single column, the rotary valve is switched once, the tail brine top water time is 0.25h, and the tail brine top water flow rate is set at 4BV / h, then 1BV of tail brine is used for the tail brine top water. One operation cycle of zone C is 7.5 hours, producing 24 BV of desorption liquid.

[0101] After the equilibrium between areas A and C is stable, the desorption liquid in area C is tested, and the ion situation of the desorption liquid in area C is as follows

[0102] As shown in Table 9:

[0103]

[0104] Table 9

[0105] The tail liquid adsorbed in area A is the outlet liquid of the combined system. The lithium ion content affects the overall lithium extraction rate. The ion situation of the tail liquid adsorbed in area A is described in Table 10 below:

[0106]

[0107] Table 10

[0108] The total lithium ion yield of the entire system is calculated based on the amount of lithium ions carried out by the tail liquid in area A:

[0109] (Total amount of raw lithium halide fed into zone A - lithium content in tail liquid of zone A) / total amount of raw lithium halide fed into zone A = (564.23*48BV - 16.86*48BV) / 564.23*48BV = 97.01%

[0110] Example 5

[0111] The brine used in this embodiment is the same as that in Example 3, and the process operating parameters are as follows:

[0112] Area A is the raw brine lithium extraction area, consisting of 30 fixed-bed adsorption columns, each filled with 80% of the column volume of aluminum-based lithium adsorbent. Adsorption in Area A is operated in a three-in-one, four-in-one configuration, while elution is performed in a single set of five columns in series. Desorption is performed in the same configuration as adsorption, and tail brine topwater is processed in a single set of single columns.

[0113] Area C is the lithium extraction and impurity removal area for the desorption liquid in Area A. It consists of 30 fixed-bed adsorption columns, with each column or tank filled with 80% of the column volume of aluminum-based lithium adsorbent. Adsorption in Area C is operated in a three-in-series and four-in-parallel mode, while elution is performed in a single group of five columns in series. Desorption is performed in the same manner as adsorption, and tail brine topwater is operated in a single group of single columns.

[0114] The adsorption in area A adopts 12 adsorption columns in three series and four parallels, with a flow rate of 8BV / h. The adsorption time in one cycle is 3h. The switching frequency of the rotary valve of the CCIX system in the entire area A is 0.25h / time (3h / 12 columns), so 96BV of raw brine can be adsorbed in one cycle; the elution of 5 adsorption columns is carried out in a single group in series. The rotary valve switches 5 times in the elution area, and the elution time for one cycle is 1.25h (0.25h / time * 5 times). The elution flow rate is set to 4BV / h, and the elution water volume is 5BV; the desorption flow rate is set to 4BV / h, and the other process operating parameters are the same as adsorption, so 48BV of desorption liquid is obtained; the tail brine top water is a single group and a single column, and the rotary valve switches once, so the tail brine top water time is 0.25h. The tail brine top water flow rate is set to 4BV / h, and the tail brine top water uses 1BV of tail brine; one operation cycle in area A is 7.5h.

[0115] Zone C adsorbs 48BV of desorption liquid from Zone A, wherein 12 adsorption columns are set for adsorption, and are operated in a three-in-one and four-in-parallel mode. The adsorption flow rate of Zone C is set at 4BV / h, and the adsorption time within the cycle is 3h. The rotation frequency of the rotary valve of the CCIX system of the entire Zone C, which is pushed out from the adsorption zone, is 0.25h / time (3h / 12 columns); 5 adsorption columns are eluted, and a single group of series operation is adopted, and the rotary valve is switched 5 times in the elution zone. The elution time for one cycle is 1.25h (0.25h / time * 5 times). The elution flow rate is set at 4BV / h, and the elution water consumption is 5BV; the desorption operation parameters are set to be the same as the adsorption, and 48BV of desorption liquid is generated in Zone C; the tail brine top water unit is a single group and single column, the rotary valve is switched once, the tail brine top water time is 0.25h, and the tail brine top water flow rate is set at 4BV / h, so the tail brine top water uses 1BV of tail brine. Then, one operating cycle of zone C is 7.5 hours, producing 48 BV of desorption liquid to be sent to the next process.

[0116] After the A and C zone systems reach a stable state, the desorption liquid in zone C is tested. The ion content of the desorption liquid in zone C is shown in Table 11 below:

[0117]

[0118] Table 11

[0119] The adsorption tail liquid in area A is used as the outlet liquid of the combined system. The lithium ion content affects the overall lithium extraction rate. The ion situation of the tail liquid in area A is shown in Table 12 below:

[0120]

[0121] Table 12

[0122] The total lithium ion yield of the entire system is calculated based on the amount of lithium ions carried out by the tail liquid in area A:

[0123] (Total amount of raw lithium halide fed into zone A - lithium content in tail liquid of zone A) / total amount of raw lithium halide fed into zone A = (564.23*96BV - 52.33*96BV) / 564.23*96BV = 90.73%

[0124] Example 6

[0125] In this example, the desorption liquid in zone C of the adsorption section of Example 5 was selected as the experimental brine:

[0126] Step 1: The desorption eluate from zone C is subjected to ultrafiltration to remove suspended impurities, and the ion content of the output liquid is measured as shown in Table 13 below:

[0127]

[0128] Table 13

[0129] Step 2: The desorbed liquid after ultrafiltration was concentrated by RO, and the calcium and magnesium resins and boron were removed by aminocarboxylic acid chelating resin and meglumine resin. The ion content was measured as shown in Table 14 below:

[0130]

[0131] Table 14

[0132] Step 3: After MVR, lithium precipitation, pulp washing, leaching, drying and powdering, lithium carbonate with a main content of 99.34% is obtained. The specific test results are shown in Table 15 below:

[0133]

[0134] Table 15

[0135] Example 7

[0136] In this example, the desorption liquid in zone C of the adsorption section of Example 5 was selected as the experimental brine:

[0137] In step 1, the desorption eluate from zone C is subjected to ultrafiltration to remove suspended impurities, and the ion content of the output liquid is measured as shown in Table 16 below:

[0138]

[0139] Table 16

[0140] Step 2, the desorbent after ultrafiltration was concentrated by RO, and calcium and magnesium were removed by aminocarboxylic acid chelating resin and meglumine resin. The ion content was as shown in Table 17 below:

[0141]

[0142] Table 17

[0143] Step 3, and then MVR to obtain 82.32% crude lithium chloride. The specific test results are shown in Table 18 below:

[0144]

[0145] Table 18

[0146] It should be noted that when using aluminum-based adsorbents to extract lithium, the adsorption rate of lithium ions in the brine is not only affected by the synergistic effects of the adsorbent performance and process operating parameters, but also by the salinity of the brine itself. For this reason, in each of the embodiments described, the amount of desorbent used in zones A and B is set to be less than the adsorption capacity of the brine. Furthermore, when the amount of desorbent used is less than the adsorption capacity, and provided that the adsorbent is not affected by poisoning factors, the lithium ion content in the desorbent is higher than the lithium ion content in the feed brine, making it easier for lithium ions to penetrate and embed into the layered structure of the adsorbent.

[0147] The present invention combines lithium adsorbent selection with process optimization to achieve its objectives by operating both the adsorbent and the process at the most efficient parameters. While certain embodiments have been shown and described, it is not possible to enumerate all of them. Those skilled in the art will readily appreciate that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention. Such changes are within the scope of the present invention and are defined by the appended claims and their equivalents.

[0148] The embodiments of the present invention are described in detail above. The description of the above embodiments is only used to help understand the method of the present invention and its core concept. At the same time, for those skilled in the art, according to the concept of the present invention, there may be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for extracting lithium from brine based on a multi-stage CCIX combined system, characterized in that: The following steps are involved: S1: Pumping the raw brine into the CCIX system in area A for adsorption and lithium extraction, and the CCIX system in area A pumping out the desorption liquid in area A and the adsorption tail liquid in area A; S2: pumping the desorption liquid from zone A into the CCIX system in zone C for adsorption and lithium extraction, and the CCIX system in zone C pumping out the desorption liquid from zone C and the adsorption tail liquid from zone C; S3: Using the adsorption tail liquid of zone C as a desorbent of the CCIX system of zone A, and preparing lithium salt through the desorption liquid of the CCIX of zone C.

2. The method for extracting lithium from brine based on a multi-stage CCIX combined system according to claim 1, characterized in that: The raw brine in S1 needs to be pretreated before entering the CCIX system in area A. The pretreatment includes ultrafiltration and pH adjustment. The ultrafiltration includes removing insoluble impurities. The pH adjustment includes adjusting the pH value of the raw brine to 5-7.5 with hydrochloric acid or alkali.

3. The method for extracting lithium from brine based on a multi-stage CCIX combined system according to claim 1, characterized in that: If the lithium content of the adsorption tail liquid in zone A is less than 8% of the lithium content of the original brine, the adsorption tail liquid in zone A is reinjected or discharged into the lake, and the desorption liquid in zone A directly enters the CCIX system in zone C for lithium extraction, and the adsorption tail liquid in zone C is only used as a desorbent for the CCIX system in zone A; if the lithium content of the adsorption tail liquid in zone A is greater than 8% of the lithium content of the feed brine, the adsorption tail liquid in zone A is pumped into the CCIX system in zone B for adsorption and lithium extraction, and the CCIX system in zone B pumps out the desorption liquid and the adsorption tail liquid in zone B, and the adsorption tail liquid in zone B is reinjected or discharged into the lake, and the desorption liquid in zone A and the desorption liquid in zone B are mixed into a mixed desorption liquid in zones A and B and pumped into the CCIX system in zone C for adsorption and lithium extraction.

4. The method for extracting lithium from brine based on a multi-stage CCIX combined system according to claim 1 and claim 3, characterized in that: The CCIX system in area A, the CCIX system in area B and the CCIX system in area C include rotary valves and adsorption towers. The time it takes for the rotary valve to rotate one circle is one cycle. The number of valve switching times of the rotary valve in the cycle is equal to the number of the adsorption towers.

5. The method for extracting lithium from brine based on a multi-stage CCIX combined system according to claim 1, characterized in that: The CCIX system in area A, the CCIX system in area B and the CCIX system in area C also include a pure water tank. Running one cycle requires four steps, namely adsorption-elution-desorption-tail brine top water. The adsorption step produces adsorption tail liquid, the elution step produces elution discharge liquid, and the desorption step produces desorption liquid; the tail brine top water refers to the residual desorption water contained in the adsorption tower, which is replaced by tail brine and the residual desorption water is returned to the pure water tank containing the desorbent, and the tail brine top water produces tail brine top water discharge liquid.

6. The method for extracting lithium from brine based on a multi-stage CCIX combined system according to claim 1 and claim 3, characterized in that: The elution discharge liquid of the CCIX system in area A is mixed with the raw brine; the elution discharge liquid of the CCIX system in area B is mixed with the adsorption tail liquid in area A; the elution discharge liquid of the CCIX system in area C in S3 is mixed with the mixed desorption liquid in areas A and B; the tail brine top water discharge liquid of the CCIX system in area A and the tail brine top water discharge liquid of the CCIX system in area B are respectively mixed with the adsorption tail liquid in area C, and the tail brine top water discharge liquid of the CCIX system in area C is mixed with the pure water tank in area C.

7. The method for extracting lithium from brine based on a multi-stage CCIX combined system according to claim 1, characterized in that: The desorption liquid in zone C is subjected to RO concentration, resin combination and MVR evaporation, and lithium carbonate is prepared through lithium precipitation, slurry washing, filtration, drying and powdering operations.

8. The method for extracting lithium from brine based on a multi-stage CCIX combined system according to claim 7, characterized in that: The desorption liquid in zone C can be made into crude lithium chloride after MVR evaporation.

9. The method for extracting lithium from brine based on a multi-stage CCIX combined system according to claim 7, characterized in that: The resin combination adopts aminocarboxylic acid chelating resin and meglumine resin.

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