Salt lake lithium extraction adsorbent continuous ion exchange device

Abstract

The utility model discloses a continuous ion exchange device for a salt lake lithium extraction adsorbent, belongs to the technical field of salt lake lithium extraction, and solves the problems of waste of adsorption capacity or qualified liquid in an adsorption washing stage and large solution loss of the adsorbent in a desorption stage by improving an existing continuous ion exchange system. According to the continuous ion exchange device, the connection relation of the exchange columns in the adsorption washing area and the desorption area is improved, the concentration of impurity ions in output qualified liquid is reduced, meanwhile, two stages of desorption tanks are arranged in the desorption area, the acid concentration is remarkably reduced by controlling desorption liquid, the desorption effect is guaranteed, the solution loss of an adsorbent is reduced, and the quality of the product is improved. The service life of the adsorbent is prolonged; when the device is used for continuous ion exchange of the salt lake lithium extraction adsorbent, the acid consumption can be reduced, and the operation cost can be saved.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium extraction from salt lakes, and particularly relates to a continuous ion exchange device for lithium extraction adsorbents from salt lakes. Background Art

[0002] As a key raw material for new energy batteries, the demand for lithium resources continues to grow. The reserves of lithium resources in salt lakes in China account for about 80% of the total lithium resource reserves. To meet the future lithium demand, the technology of lithium extraction from salt lakes has attracted more and more attention.

[0003] Driven by market demand, the technology of extracting lithium from raw brine has developed rapidly. Among them, the "adsorption method" is regarded as the means of extracting lithium from raw brine with the highest industrialization degree and the most mature technology at present. And the continuous ion exchange system has been more and more applied in the adsorption method due to its advantages such as high process continuity, high utilization rate of adsorbents, compact structure, and small washing water volume. At present, among the mainstream adsorbents on the market, titanium-based adsorbents belong to ion sieve adsorbents, and the extraction of lithium ions is achieved through the exchange between lithium ions and hydrogen ions.

[0004] The patent "A continuous ion exchange system for controlling the dissolution loss of lithium extraction adsorbents by ion sieve" with the application number CN202320799315.1 discloses a continuous ion exchange system for lithium extraction adsorbents. The adsorbent undergoes four stages: adsorption - adsorption washing - desorption - desorption washing. In the adsorption stage, lithium ions in the brine enter the ion sieve to replace hydrogen ions to complete the adsorption process; in the adsorption washing stage, dilute acid or qualified desorption liquid is used to wash away the residual brine and some co-adsorbed impurity ions in the adsorption stage; in the desorption stage, excessive acid is used to displace lithium ions; in the desorption washing stage, pure water is used to wash away the residual acid liquid in the desorption stage. However, the following problems still exist in the above scheme: 1. In the adsorption washing stage, although the residual brine and some co-adsorbed impurity ions in the adsorption stage are washed away by using dilute acid or qualified desorption liquid, some lithium ions will be displaced, resulting in a waste of adsorption capacity; 2. In the desorption stage, since the acid is used in excess, the concentration of H + reaches 0.02 - 0.15 mol / L. The excessive acid will cause varying degrees of chemical dissolution loss of the adsorbent, reducing the service life of the adsorbent. The higher the concentration of the acid, the greater the dissolution loss of the adsorbent. Therefore, it is necessary to improve the continuous ion exchange system to solve the problems of waste of adsorption capacity or waste of qualified liquid in the adsorption washing stage and large dissolution loss of the adsorbent in the desorption stage. Summary of the Utility Model

[0005] To solve the problems in the prior art, the utility model provides a continuous ion exchange device for lithium extraction adsorbents from salt lakes, which can reduce the dissolution loss of the adsorbent, extend the service life of the adsorbent, and significantly reduce the operation cost of the system while ensuring the desorption effect.

[0006] The solution of the utility model is as follows:

[0007] A continuous ion exchange device for lithium adsorption agent in salt lake brine extraction, comprising an adsorption zone, an adsorption washing zone, a desorption zone and a desorption washing zone;

[0008] The adsorption zone includes 16 exchange columns located at positions 1-16. Among them, the exchange columns at positions 1-8 have brine inlet at the top, and the exchange columns at positions 9-16 have water outlet at the top;

[0009] The adsorption washing zone includes 5 exchange columns located at positions 26-30 respectively and a primary water washing tank. The exchange columns in the adsorption washing zone all have water inlet at the top and water outlet at the bottom. Among them, the exchange columns at positions 26 and 27 are connected in series for primary washing, and the exchange columns at positions 28-30 are connected in series for secondary washing;

[0010] The desorption zone includes 7 exchange columns located at positions 19-25 and 2 interconnected desorption tanks. Among them, the exchange columns in the desorption zone all have water inlet at the bottom. The exchange columns at positions 19-22 are connected in parallel and form a circulating reflux with the secondary desorption tank. The exchange columns at positions 23-25 are connected in parallel, and the bottom water inlets are all connected to the primary desorption tank;

[0011] The desorption washing zone includes 2 exchange columns located at positions 17 and 18 and connected in series and a secondary water washing tank, both of which have water inlet at the top. The top water inlet of the exchange column at position 17 is connected to the secondary water washing tank, and the bottom water outlet of the exchange column at position 18 is connected to the secondary desorption tank.

[0012] Furthermore, the exchange columns at positions 1-8 in the adsorption zone are connected in parallel, and all have water inlet at the top and water outlet at the bottom. The water outlets at the bottoms of the exchange columns at positions 1-8 are respectively connected to the water inlets at the bottoms of the exchange columns at positions 16-9. The tops of the exchange columns at positions 16-9 are water outlets and are connected to the salt lake.

[0013] Furthermore, the bottom water inlet of the exchange column at position 23 in the desorption zone is connected to the primary desorption tank, and the top water outlet is the qualified liquid. The exchange column at position 24 forms a circulating reflux with the primary desorption tank. The bottom water inlet of the exchange column at position 25 is connected to the primary desorption tank. The top water outlet at position 25 forms a branch and is connected to the primary water washing tank or the primary desorption tank, and a control valve is provided on the branch pipeline.

[0014] Furthermore, the bottom water inlet of the exchange column at position 23 in the desorption zone is connected to the primary desorption tank, and the top water outlet is the qualified liquid. The bottom water inlets of the exchange columns at positions 24 and 25 are connected to the primary desorption tank. The top water outlet at position 25 is connected to the primary water washing tank or the primary desorption tank.

[0015] Furthermore, a conductivity meter is provided at the top water outlet of the exchange column at position 25.

[0016] Furthermore, the secondary desorption tank is provided with an overflow pipe connected to the primary desorption tank; both the primary desorption tank and the secondary desorption tank are provided with a stirring and heating device, a heat preservation device and a pH on-line monitor.

[0017] Furthermore, an acid replenishing tank is also arranged in the desorption area, and the acid replenishing tank is connected to the overflow pipe at the connection of the primary desorption tank and the secondary desorption tank through an acid replenishing pump.

[0018] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0019] 1. In the present utility model, the connection relationship of the exchange columns in the adsorption washing area and the desorption area is improved, reducing the concentration of impurity ions in the output qualified liquid; two-stage desorption tanks are arranged in the desorption area, and the desorbed liquid of the primary desorption tank is mainly the overflow liquid of the secondary desorption tank. By controlling the desorbed liquid, the acid concentration is significantly reduced to 3.16×10 -6 -3.16×10 -5 mol / L (pH = 3 - 6), which can well reduce the dissolution loss of the adsorbent, ensure the desorption effect, extend the service life of the adsorbent, and significantly reduce the replacement cost of the adsorbent.

[0020] 2. Using the device of the present utility model for continuous ion exchange of the lithium adsorbent in salt lakes can reduce the acid consumption, save the operation cost. Pure water is used in the whole process of desorption and washing of the device. Compared with using qualified liquid, the water production of the system is increased; compared with using other lithium-containing solutions, the operation input is saved; compared with using dilute acid, both the acid input is saved and the lithium adsorption capacity is not wasted.

[0021] Reference numerals

[0022] Figure 1 is the process flow chart of the device of the present utility model. Detailed implementation manners

[0023] The following further describes the present utility model with reference to the drawings and preferred embodiments.

[0024] As Figure 1 shown, this embodiment provides a continuous ion exchange device for lithium adsorbent in salt lakes, including an adsorption area, an adsorption washing area, a desorption area and a desorption washing area;

[0025] Sixteen exchange columns are arranged in sequence in the adsorption zone, among which brine is introduced into the top of the exchange columns located at positions 1-8, and the brine flows from top to bottom. The water outlets at the bottom of the exchange columns located at positions 1-8 are respectively connected to the water inlets at the bottom of the exchange columns located at positions 16-9, and the brine forms a countercurrent from the bottom to the top from the bottom of the exchange columns located at positions 9-16. The top of the exchange columns located at positions 16-9 is the water outlet, and the tail brine of the outlet is returned to the salt lake. The adsorption process of the exchange columns through which the brine flows in the adsorption zone is divided into two areas, which can make the contact between the adsorbent and the brine more sufficient and reduce the adsorption deviation caused by the filling height of the adsorbent in the exchange column.

[0026] The adsorption washing area includes 5 exchange columns located at positions 26-30 and a primary water washing tank. The exchange columns in the adsorption washing area are all top-inlet and bottom-out. Among them, the exchange columns located at positions 26 and 27 are connected in series as a primary washing area. The water inlet of the primary washing area is drawn from the secondary water washing tank of the desorption washing area, entering from the top of the exchange column located at position 26, and the bottom of the exchange column at position 27 is discharged into the primary water washing tank. The exchange columns located at positions 28-30 are connected in series as a secondary washing area. The water inlet of the secondary washing area is drawn from the primary water washing tank, entering from the top of the exchange column located at position 28, and discharged from the bottom of the exchange column at position 30. The outlet water can be used as a washing liquid discharge system. The primary water washing tank collects the residual washing water from the exchange columns at positions 24 and 25 and the washing water from the exchange columns at positions 26 and 27, which are used for flushing the exchange columns at positions 28-30. Such a segmented setting can wash the brine residual in the exchange columns more thoroughly, avoiding the problem of high impurity ion content in the qualified liquid caused by the introduction of impurity ions by the residual brine.

[0027] The desorption zone includes 7 exchange columns located at positions 19-25 and 2 interconnected desorption tanks, each of which is equipped with a stirring and heating device, a heat preservation device and a pH online monitor; the exchange columns in the desorption zone are all bottom-inlet, the exchange columns located at positions 19-22 are connected in parallel, and the bottom water inlets are all connected to the secondary desorption tank. The desorption liquid in the exchange columns in this area enters the bottom of the exchange columns from the secondary desorption tank and flows back to the secondary desorption tank from the top of the exchange columns;

[0028] The exchange columns located at positions 23 - 25 are connected in parallel, and their bottom water inlets are all connected to the first-stage desorption tank. The desorbing liquid in the exchange columns in this area enters the bottom of the exchange columns from the first-stage desorption tank. The water outlet at the top of the exchange column at position 23 flows out as qualified liquid and enters the qualified liquid tank or the next-stage system, which can ensure the stability of the qualified liquid. The exchange column at position 24 forms a circulating reflux with the desorbing liquid in the first-stage desorption tank. The bottom water inlet of the exchange column at position 25 is connected to the first-stage desorption tank, and the water outlet at the top of the exchange column at position 25 forms a branch and is connected to the first-stage water washing tank or the first-stage desorption tank. A control valve is set on the branch pipeline. The water flowing out from the water outlet at the top of the exchange column can pass through the control valve and be selected to flow back to the first-stage water washing tank or the first-stage desorption tank. An electrical conductivity meter is also set at the water outlet at the top of the exchange column at position 25 to monitor the electrical conductivity. When the electrical conductivity is lower than the set value, the valve on the pipeline connected to the first-stage water washing tank is opened, and the water flows into the first-stage water washing tank. When the electrical conductivity is higher than the set value, the valve on the pipeline connected to the first-stage desorption tank is opened, and the water flows into the first-stage desorption tank. At the same time, the setting of the electrical conductivity meter can also remove the washing water remaining in the adsorption washing stage, which can avoid the dilution of the desorbing liquid by this part of water, is beneficial to maintaining the acid concentration and the lithium ion concentration of the desorbing liquid, and improves the target ion concentration of the qualified liquid.

[0029] Two-stage desorption tanks are set in the desorption area to make more full use of acid. As a preferred embodiment, the desorbing liquid in the first-stage desorption tank is mainly the overflow liquid from the second-stage desorption tank. The pH of the desorbing liquid in the first-stage desorption tank is controlled at 4.5 - 6 (corresponding H + concentration is 10 -6 -3.16×10 -5 mol / L). The residual acid in the first-stage desorption tank is used to desorb the exchange columns at positions 23 - 25. Since the adsorbent in the exchange columns in this area is in a saturated state, using a desorbing liquid with a lower acid concentration can achieve a good desorption effect, realizing the further concentration of the desorbing liquid. At the same time, the low-concentration acid reduces the dissolution loss of the adsorbent. The exchange columns corresponding to the second-stage desorption tank at positions 19 - 22 need a higher concentration of acid solution to more thoroughly desorb the adsorbed ions after the first-stage desorption. The pH of the desorbing liquid in the second-stage desorption tank is controlled at 3.5 - 5.5 (corresponding H + concentration is 3.16×10 -6- 3.16×10 -4 mol / L).

[0030] As a preferred embodiment, an acid replenishing tank is also set in the desorption area. The acid replenishing tank is connected to the overflow pipe at the connection of the first-stage desorption tank and the second-stage desorption tank through an acid replenishing pump. When the pH is higher than the set value, acid liquid is replenished into the desorption tank from the acid replenishing tank through the acid replenishing pump.

[0031] As a preferred embodiment, the higher the temperature of the desorbing liquid in the desorption zone, the faster the desorption rate. However, at the same time, the dissolution loss of the adsorbent is also greater, and the system energy consumption is also higher. Therefore, for this system, the preferred temperature of the desorbing liquid is 20 - 35°C.

[0032] The desorption and washing zone includes two exchange columns arranged in series at positions 17 and 18 and a secondary water washing tank, all of which have water inlet at the top. The top water inlet of the exchange column at position 17 is connected to the secondary water washing tank, and the bottom water outlet of the exchange column at position 18 is connected to the secondary desorption tank. The water inlet flows into the top of the exchange column at position 17 and flows out from the bottom of the exchange column at position 18. The makeup water of the secondary water washing tank is pure water.

[0033] When the device of the present utility model is used in a pilot-scale system, the obtained data are as follows:

[0034] Table 1 is the main ion composition table of alkaline salt lake brine, which is the raw brine for the device inlet, and Table 2 is the water quality test data of multiple rounds of qualified liquid.

[0035] Table 1 Main Ion Composition Table of Brine

[0036]

[0037]

[0038] Table 2 Water Quality Test Data of Qualified Liquid

[0039] Ionic components <![CDATA[Li + > <![CDATA[K + > <![CDATA[Na + > <![CDATA[Mg 2+ > <![CDATA[Ca 2+ > <![CDATA[B 3+ > <![CDATA[Ti 4+ > Data 1, mg / L 1577.68 138.31 569.14 155.67 185.29 34.62 0 Data 2, mg / L 1571.63 152.7 602.26 165.67 135.11 35.99 0.09 Data 3, mg / L 1574.42 137.1 530.12 151.82 138.09 31.12 0.04 Data 4, mg / L 1538.366 153.12 539.861 260.839 181.078 35.317 0 Data 5, mg / L 1557.383 155.854 536.332 244.778 172.235 35.08 0.028

[0040] It can be seen from the data in the above table that the concentration of titanium ions in the qualified liquid is used to characterize the dissolution loss of the adsorbent, which is at least 10 times higher than that of the traditional process, equivalent to the extension of the adsorbent life by more than 10 times. At the same time, the concentration of the target ion lithium ions in the qualified liquid also has a corresponding increase, and the concentration of impurity ions is controlled at a low level.

[0041] The above are only the embodiments of the present utility model, and do not limit the patent scope of the present utility model accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification of the present utility model, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present utility model.

Claims

1. A salt lake lithium extraction adsorbent continuous desorption device, comprising an adsorption zone, an adsorption washing zone, a desorption zone and a desorption washing zone; characterized in that: The adsorption zone includes 16 exchange columns located at positions 1 to 16, wherein brine enters the top of the exchange columns located at positions 1 to 8, and water exits the top of the exchange columns located at positions 9 to 16; The adsorption washing area includes 5 exchange columns located at positions 26-30 and a primary water washing tank. The exchange columns in the adsorption washing area are all connected in series for water inlet at the top and outlet at the bottom. Among them, the exchange columns located at positions 26 and 27 are connected in series for primary washing, and the exchange columns located at positions 28-30 are connected in series for secondary washing. The desorption zone includes 7 exchange columns located at positions 19-25 and 2 interconnected desorption tanks; wherein, the exchange columns in the desorption zone are all bottom-water inlet, the exchange columns located at positions 19-22 are connected in parallel to form a circulation reflux with the secondary desorption tank, and the exchange columns located at positions 23-25 ​​are connected in parallel, and the bottom water inlets are all connected to the primary desorption tank; The desorption and washing area includes two exchange columns located at positions 17 and 18 and connected in series and a secondary water washing tank. Water is supplied from the top. The top water inlet of the exchange column located at position 17 is connected to the secondary water washing tank, and the bottom water outlet of the exchange column located at position 18 is connected to the secondary desorption tank.

2. A salt lake lithium extraction adsorbent continuous ion exchange device according to claim 1, characterized in that: The exchange columns at positions 1 to 8 in the adsorption zone are connected in parallel, and all have water inlet at the top and outlet at the bottom. The water outlets at the bottom of the exchange columns at positions 1 to 8 are respectively connected to the water inlets at the bottom of the exchange columns at positions 16 to 9, and the tops of the exchange columns at positions 16 to 9 are water outlets connected to the salt lake.

3. A salt lake lithium extraction adsorbent continuous ion exchange device according to claim 1, characterized in that: The top water inlet of the exchange column at position 26 in the adsorption washing area is connected to the secondary water washing tank, the bottom water outlet of the exchange column at position 27 is connected to the primary water washing tank, the top water inlet of the exchange column at position 28 is connected to the primary water washing tank, and the bottom water outlet of the exchange column at position 30 is used as eluent.

4. A salt lake lithium extraction adsorbent continuous ion exchange device according to claim 1, characterized in that: The bottom water inlet of the exchange column at position 23 in the desorption zone is connected to the primary desorption tank, and the water discharged from the top water outlet is used as qualified liquid. The exchange column at position 24 forms a circulation reflux with the primary desorption tank, the bottom water inlet of the exchange column at position 25 is connected to the primary desorption tank, and the top water outlet at position 25 forms a branch and is connected to the primary water washing tank or the primary desorption tank, and a control valve is set on the branch pipeline.

5. A salt lake lithium extraction adsorbent continuous ion exchange device according to claim 4, characterized in that: A conductivity meter is installed at the water outlet of the top of the exchange column at position 25.

6. A salt lake lithium extraction adsorbent continuous ion exchange device according to claim 4, characterized in that: The secondary desorption tank is provided with an overflow pipe connected to the primary desorption tank; both the primary desorption tank and the secondary desorption tank are provided with a stirring and heating device, a heat preservation device and a pH online monitor.

7. A salt lake lithium extraction adsorbent continuous ion exchange device according to claim 4, characterized in that: The desorption zone is also provided with an acid feed tank, which is connected to an overflow pipe at the connection between the primary desorption tank and the secondary desorption tank through an acid feed pump.

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