CN114892025A

CN114892025A - Simulated moving bed lithium extraction adsorption process

Info

Publication number: CN114892025A
Application number: CN202210624812.8A
Authority: CN
Inventors: 梁琪; 范飞; 牟志强; 宋超飞; 赵磊; 孟祥龙; 宫宝斌; 王飘扬
Original assignee: Beijing Water Business Doctor Co ltd
Current assignee: Beijing Water Business Doctor Co ltd
Priority date: 2022-06-02
Filing date: 2022-06-02
Publication date: 2022-08-12
Anticipated expiration: 2042-06-02
Also published as: CN114892025B

Abstract

The invention belongs to the field of lithium extraction adsorption processes, and discloses a simulated moving bed lithium extraction adsorption process. The process comprises the following steps: preparing an adsorption system which comprises a raw brine feeding tank, a desorption liquid tank, a low-magnesium water tank, a qualified elution liquid tank, a wastewater treatment device, an adsorption tail liquid container and an adsorption bed, wherein a plurality of adsorption columns are arranged in the adsorption bed; introducing brine to be treated, sequentially placing the adsorption column in an adsorption stage, a leaching stage, a desorption stage and a water washing stage in sequence by controlling a valve, and circularly operating; and (3) keeping the adsorption columns in the adsorption stage at any time period, wherein the adsorption columns are in the leaching stage, the desorption stage and the water washing stage or are used as blanks for standby application, N is a natural number not less than 2, and N is a non-0 natural number less than N. The system has simple structure, can switch each adsorption column in the adsorption stage, the leaching stage, the water washing stage and the desorption stage at any time and the working time of each stage, has high adsorption efficiency of the adsorption process, and saves the cost.

Description

Simulated moving bed lithium extraction adsorption process

Technical Field

The invention belongs to the field of lithium extraction adsorption processes, and particularly relates to a simulated moving bed lithium extraction adsorption process.

Background

A Simulated Moving Bed (SMB) is an adsorption separation device which is composed of a plurality of fixed Bed chromatographic columns connected in series and can realize continuous separation of components. The simulated moving bed integrates the advantages of a fixed bed and a moving bed, has the characteristics of large treatment capacity, continuous production and small adsorbent abrasion, is widely applied to product separation in petrochemical industry, medicine and fine chemical industry, and particularly shows good superiority and economy for a material system which is difficult to separate by a traditional separation method.

The lithium ion sieve type adsorbent is a non-traditional adsorbent with a special structure, and compared with the traditional adsorbent, the lithium ion sieve type adsorbent can selectively adsorb lithium ions from brine containing low lithium grade, and then elute the lithium ions by using specific eluent, so that the aim of separating the lithium ions from other impurity ions is fulfilled, and the first step of extracting lithium from the brine is realized.

Chinese patent publication No. CN201810516600.1, "a continuous ion exchange device and method capable of realizing lithium-sodium separation", includes resin, a plurality of resin columns for loading resin, a feeding main pipe communicated with the upper ends of the resin columns, and a discharging main pipe communicated with the lower ends of the resin columns, wherein the resin columns are sequentially connected in series through serial pipes, and form a group for absorbing lithium ions, a leaching group, a desorption group, a back flushing group, and a material top water group in a lithium-sodium solution that sequentially moves and circularly operates; the technical scheme is characterized in that each feeding branch pipe and each discharging branch pipe are respectively provided with a control valve for coordinating and controlling the processes of ion exchange, leaching and desorption among all groups of resin column groups in turn.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a simulated moving bed lithium extraction adsorption process which is high in adsorption efficiency and cost-saving.

In order to realize the purpose of the invention, the specific technical scheme is as follows:

a crossed simulated moving bed lithium extraction adsorption process comprises the following steps:

a system preparation stage: preparing an adsorption system, wherein the adsorption system comprises a raw brine feeding tank, a desorption liquid tank, a low-magnesium water tank, a qualified eluent tank, a wastewater treatment device, an adsorption tail liquid container and an adsorption bed, a plurality of adsorption columns are arranged in the adsorption bed, and lithium ion sieve adsorbents are filled in the adsorption columns; the adsorption column is provided with a liquid inlet end and a liquid outlet end, the liquid inlet end is respectively connected with the feeding raw brine tank, the desorption liquid tank and the low-magnesium water tank through pipelines, and the liquid outlet end is respectively connected with the feeding raw brine tank, the low-magnesium water tank, the qualified elution liquid tank, the wastewater treatment device and the adsorption tail liquid container through pipelines; the liquid outlet end of the adsorption column is respectively connected with the liquid inlet ends of other adsorption columns through pipelines; the pipelines are provided with valves and pumps;

and (3) lithium extraction and adsorption stage: introducing brine to be treated, sequentially placing the adsorption column in an adsorption stage, a leaching stage, a desorption stage and a water washing stage in sequence by controlling a valve, and circularly operating;

wherein: keeping 3N adsorption columns in an adsorption stage in any time period, wherein N adsorption columns are in a leaching stage, a desorption stage and a water washing stage or are used as blanks for standby application, N is a natural number not less than 2, and N is a non-0 natural number less than N;

and (3) adsorption columns positioned in the adsorption stage are connected in series to form 1 group, n groups are formed, and the groups are arranged in parallel.

Further, n is an even number not less than 2.

Further, the adsorption system further comprises a control unit for controlling a valve and/or a pump, preferably, the valve is a solenoid valve or a pneumatic valve, and the pump is a booster pump.

Further, the adsorption column is filled with manganese-based or titanium-based adsorbent.

Further, in the brine to be treated, the concentration of lithium is more than 20mg/L, and the ratio of magnesium to lithium is more than or equal to 10-1000: 1, the temperature of brine in the adsorption column is kept between 5 and 20 ℃.

Further, the lithium extraction and adsorption stage specifically comprises the following steps:

(1) setting an adsorption initial state: in the n groups of adsorption columns, each group of the 1 st-stage adsorption columns is in an adsorption saturated state, each group of the 2 nd-stage adsorption columns is in a semi-saturated state, and each group of the 3 rd-stage adsorption columns is in a basic blank state; the N adsorption columns are used as standby adsorption columns which are in a basic blank state;

(2) controlling a valve, and enabling 1 adsorption column which is adsorbed and saturated to be used as an adsorption column to be used after a leaching stage, a desorption stage and a water washing stage are sequentially carried out at intervals of T;

when the 1 adsorption column which is saturated by adsorption is in a leaching stage, connecting the 1 adsorption column to be used in series at the tail end of the group as a 3 rd-stage adsorption column, using the original 2 nd and 3 rd-stage adsorption columns as new 1 st and 2 nd-stage adsorption columns, and performing an adsorption stage until the new 1 st-stage adsorption column is saturated again by adsorption;

wherein: and (3) producing 1 adsorption column to be used while producing 1 saturated adsorption column for adsorption, and circulating the step (2) to form a cross type simulated moving bed form.

Furthermore, the time of each adsorption column undergoing an adsorption stage, a leaching stage, an analysis stage and a water washing stage is respectively set to tx, t1, t2 and t3, t1+ t2+ t3 is not more than tx/p, and p is a natural number not less than 1; the tx/T is rounded down to obtain n; when n ≠ 2, T ═ T1, and when n ≠ 2, T ≠ 2T 1. More preferably, n is 2 to 4, p is 1 to 3, and t1+ t2+ t3 is 80 to 300 min.

Further, in the adsorption process:

an adsorption stage: keeping the liquid inlet end of the adsorption column communicated with a raw brine feeding tank, and the liquid outlet end communicated with an adsorption tail liquid container;

a leaching stage: keeping the liquid inlet end of the adsorption column communicated with the low-magnesium water tank, and the liquid outlet end of the adsorption column communicated with the raw brine feeding tank and the low-magnesium water tank;

a desorption stage: keeping the liquid inlet end of the adsorption column communicated with a desorption liquid tank, and the liquid outlet end of the adsorption column communicated with a raw brine feeding tank, a wastewater treatment device and a qualified elution liquid tank;

and (3) water washing stage: the liquid inlet end of the adsorption column is communicated with the low-magnesium water tank, and the liquid outlet end of the adsorption column is communicated with the low-magnesium water tank and the wastewater treatment device.

Preferably:

the end point of adsorption completion in the adsorption stage is that the adsorption of the 1 st-stage adsorption column is saturated, the lithium concentration of the tail liquid of the 1 st-stage adsorption column is 80-100% of the concentration of the original brine, and the lithium concentration of the tail liquid of the 3 rd-stage adsorption column is 1-10% of the concentration of the original brine;

the end point of leaching completion in the leaching stage is that the concentration content of lithium in the effluent is lower than 1 ppm;

the end point of the desorption completion in the desorption stage is that the concentration content of the lithium in the effluent is lower than 100 ppm;

and the end point of the water washing in the water washing stage is that the concentration content of the lithium in the effluent is lower than 1 ppm.

Preferably, the first several column volumes of the leaching stage and the water washing stage of the invention are respectively fed into a brine tank and a wastewater treatment system for neutralization treatment due to residual brine, residual desorption solution and ions, and are discharged into a brine tank after the neutralization treatment. The low-magnesium water with the latter column volume can flow back to the low-magnesium water tank for recycling because of less ions and low magnesium concentration. And the desorbed lithium-rich eluent enters an eluent tank and enters the next concentration unit.

Preferably, the wastewater treatment system of the present invention consists of an acid-base neutralization system and a filtration system. The wastewater treatment system mainly collects the desorption liquid with low lithium in the first few column volumes of the leaching stage and wastewater containing part of the desorption liquid in the first few column volumes of the water washing stage. The water treated by the wastewater treatment system is discharged into the brine tank through a pipeline, so that the waste of water resources can be effectively avoided.

Preferably, in the invention, the desorption solution is 0.1-0.5 mol/L dilute hydrochloric acid, the lithium ion concentration of the qualified lithium-rich eluent is 500-1200 mg/L, and the magnesium ion concentration is 100-500 mg/L.

Compared with the prior art, the invention has the beneficial effects that:

the simulated moving bed lithium extraction adsorption process applies the simulated moving bed and the process to the lithium extraction industry of salt lakes. Aiming at salt lake brine with high magnesium-lithium ratio and low lithium concentration, an adsorption column series connection cross type mobile adsorption method is creatively arranged, and the working time arrangement of each adsorption column is reasonable through valve adjustment, the operation is stable, and the absorption and desorption processes are continuously carried out; the number of the adsorption columns can be reduced, and the investment is saved.

In the simulated moving bed lithium extraction adsorption process, the low-magnesium water can be recycled, so that a large amount of water can be saved, and the water taking cost is reduced; the desorption liquid treated by the wastewater treatment system is treated to reach the standard and discharged into a salt lake brine pool, so that the waste of water resources is avoided.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic diagram of the structure of a simulated moving bed lithium extraction adsorption system of the present invention.

FIG. 2 is a schematic view of the structure of the adsorption column of the present invention.

FIG. 3 is a schematic diagram of a simulated moving bed lithium extraction adsorption system in example 2 of the present invention.

FIG. 4 is a schematic diagram of a simulated moving bed lithium extraction adsorption system in example 3 of the present invention.

Detailed Description

In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

Example 1

As shown in fig. 1-2, the present embodiment provides a simulated moving bed lithium extraction adsorption system, which includes a raw brine feeding tank, a desorption liquid tank, a low-magnesium water tank, a qualified elution liquid tank, a wastewater treatment device, an adsorption tail liquid container, and an adsorption bed, wherein a plurality of adsorption columns 6 are disposed in the adsorption bed, and lithium ion sieve adsorbents 63 are filled in the adsorption columns 6; the adsorption column 6 is provided with a liquid inlet end 61 and a liquid outlet end 62. The liquid inlet end 61 is respectively connected with the feeding raw brine tank, the desorption liquid tank and the low magnesium water tank through pipelines, and the liquid outlet end 62 is respectively connected with the feeding raw brine tank, the low magnesium water tank, the qualified elution liquid tank, the wastewater treatment device and the adsorption tail liquid container through pipelines; the liquid outlet end of the adsorption column 6 is respectively connected with the liquid inlet ends of other adsorption columns 6 and the same adsorption column 6 through pipelines; the pipeline is provided with a valve and a pump.

In this embodiment, the number of the adsorption columns is 3N + N, where N is a natural number greater than or equal to 2, and N is a non-0 natural number less than N.

In this embodiment, adsorption system still includes the SMB intelligence numerical control system of control valve and pump.

In this embodiment, a backwash water distribution plate 64 is arranged at the bottom of the column body of the adsorption column near the liquid outlet end.

In this embodiment, the lithium ion sieve adsorbent 63 is a manganese-based or titanium-based adsorbent.

In this embodiment, the adsorption column can be in the adsorption stage, the elution stage, the desorption stage, and the water washing stage by controlling the valve, wherein:

an adsorption stage: keeping the liquid inlet end 61 of the adsorption column 6 communicated with the raw brine feeding tank and the liquid outlet end 62 communicated with the adsorption tail liquid container;

a leaching stage: keeping the liquid inlet end 61 of the adsorption column 6 communicated with the low-magnesium water tank, and the liquid outlet end 62 communicated with the raw brine feeding tank and the low-magnesium water tank;

a desorption stage: keeping the liquid inlet end 61 of the adsorption column 6 communicated with a desorption liquid tank, and the liquid outlet end 62 communicated with a raw brine feeding tank, a waste water treatment device and a qualified elution liquid tank;

and (3) water washing stage: the liquid inlet end 61 of the adsorption column 6 is communicated with the low magnesium water tank, and the liquid outlet end 62 is communicated with the low magnesium water tank and a wastewater treatment device;

specifically, the method comprises the following steps:

in the embodiment, the adsorption columns 6 are connected in series or in parallel through the first pipeline 5 and the second pipeline 11;

in the embodiment, the connection of the liquid inlet end 61 with the raw brine feeding tank, the desorption liquid tank and the low magnesium water tank is realized by arranging the adsorption liquid inlet pipeline 1, the leaching liquid inlet pipeline 2, the desorption liquid inlet pipeline 3 and the water washing liquid inlet pipeline 4 which are communicated with the liquid inlet end 61 of each adsorption column 6;

in the embodiment, the connection of the liquid outlet end 61 with the feeding raw brine tank, the low magnesium water tank, the qualified elution liquid tank, the wastewater treatment device and the adsorption tail liquid container is realized by arranging the adsorption liquid outlet pipeline 7, the leaching liquid outlet pipeline 8, the desorption liquid outlet pipeline 9 and the water washing liquid outlet pipeline 10 which are communicated with the liquid outlet end 62 of each adsorption column 6.

Example 2

The embodiment provides a simulated moving bed lithium extraction adsorption process, which uses the adsorption system in embodiment 1, wherein 7 adsorption columns are arranged, 6 adsorption columns are located in an adsorption stage, and 1 adsorption column is located in a leaching stage, a desorption stage and a water washing stage or is used as a blank for standby; in the adsorption stage, every 3 adsorption columns are connected in series to form 1 group, and 2 groups are formed in total, and the groups are arranged in parallel.

In the adsorption process:

and (3) water washing stage: the liquid inlet end of the adsorption column is communicated with the low-magnesium water tank, and the liquid outlet end of the adsorption column is communicated with the low-magnesium water tank and the wastewater treatment device;

The time for each adsorption column to go through the adsorption phase, the leaching phase, the desorption phase and the water washing phase is tx, t1, t2 and t3 respectively.

In this embodiment, t1 is 50min, t2 is 30min, t3 is 20min, and tx is 200 min. In the brine to be treated, the concentration of lithium is more than 20mg/L, and the ratio of magnesium to lithium is more than or equal to 10-1000: 1, the temperature of brine in the adsorption column is kept between 5 and 20 ℃.

As shown in fig. 3 and table 1, the process flow of this example includes the following steps:

(1) when starting, firstly, 100 column volumes (BV) are respectively arranged in the original brine ABC series connection and the DEF series connection at the same time. The column A and the column D which are positioned at the column position No. 1 adsorb in a saturated state; column B and column E at column position No. 2, in a semi-saturated state; column C and column F, in column position three, are in an unsaturated state.

(2) SMB intelligent numerical control system can adjust the business turn over water valve and the flow of each post. After 100 BV of loading at 400min, both column A and column D were in adsorption saturation. Firstly, a saturated A column is adjusted to a leaching area through a numerical control system, meanwhile, a column B is adjusted to a No. 1 bit column, a column C is adjusted to a No. 2 bit column, a standby column a is adjusted to a No. 3 bit column, and brine starts to run sample tx which is 200min for 50 BV. The A column is respectively carried out with a leaching section, a desorption section and a water washing section for 100 min. After the column A is washed with water, the column A recovers the adsorption capacity again, and is marked as A'. Meanwhile, the saturated D column is sequentially adjusted to a leaching area, meanwhile, the column E is adjusted to the No. 1 position column by the numerical control system, the column F is adjusted to the No. 2 position column, the column A 'is adjusted to the No. 3 position column, and EFA' brine starts to sample for 200min, which is 50 BV.

(3) And respectively carrying out a leaching section, a desorption section and a water washing section on the D column for 100 min. And after the D column is washed with water, the adsorption capacity of the D column is recovered again and is marked as D'. Meanwhile, BCa is just about to finish 50BV, the adsorption is finished, and the column B is saturated.

(4) And adjusting the saturated B column to a leaching area through a numerical control system, adjusting the sample I area to be CaD', and keeping the sample solution from changing into 50 BV. The column B is respectively subjected to a leaching section, a desorption section and a water washing section for 100 min. After the column B is washed with water, the column B 'recovers the adsorption capacity again, and is marked as B'. At the same time, EFA' just finishes 50BV, adsorption is finished, and the E column is saturated.

The above steps are repeated to form a cross type simulated moving bed mode. The adsorption step sequence is shown in Table 1.

In this example, the initial brine concentration was 165mg/L for lithium ions and 10 ten thousand mg/L for magnesium ions. The desorption solution in this example is 0.1mol/L diluted hydrochloric acid, and after a single adsorption, the lithium ion concentration of the column tail solution of the 3 rd stage is lower than 5 mg/L. The lithium ion concentration of the qualified lithium-rich eluent is 600-850 mg/L, and the magnesium ion concentration is 200-260 mg/L.

TABLE 1

Example 3

The embodiment provides a simulated moving bed lithium extraction adsorption process, which uses the adsorption system in embodiment 1, wherein 14 adsorption columns are arranged, 12 adsorption columns are located in an adsorption stage, and 2 adsorption columns are located in a leaching stage, a desorption stage and a water washing stage or serve as blanks for standby; in the adsorption stage, every 3 adsorption columns are connected in series to form 1 group, 4 groups in total, and the groups are arranged in parallel.

In the adsorption process:

the end point of leaching completion in the leaching stage is that the concentration content of lithium in the effluent is below 1 ppm;

the end point of the water washing in the water washing stage is that the concentration of the lithium in the effluent is less than 1 ppm.

The time for each adsorption column to go through one adsorption stage, one leaching stage, one desorption stage and one water washing stage is tx, t1, t2 and t3 respectively, in this embodiment, t1 is 50min, t2 is 30min, t3 is 20min, and tx is 200 min. In the brine to be treated, the concentration of lithium is more than 20mg/L, and the ratio of magnesium to lithium is more than or equal to 10-1000: 1, the temperature of brine in the adsorption column is kept between 5 and 20 ℃.

As shown in fig. 4 and table 2, the process flow of this example includes the following steps:

(1) setting an adsorption initial state: firstly, 4 groups of raw brine ABC, DEF, GHI and JKL are connected in series, and 100 column volumes (BV) are respectively arranged at the same time. Column A, column D, column G and column J, located at column position No. 1, in an adsorption saturation state; column B, column E, column H and column K at column position No. 2, in a half-saturated state; column C, column F, column I and column L at column position three, unsaturated state.

(2) The SMB intelligent numerical control system can adjust the water inlet and outlet valves and the flow of each column. After 100 BV of loading at 400min, the A, D, G and J columns were all in adsorption saturation. Firstly, adjusting a saturated A column to a leaching section through a numerical control system, simultaneously adjusting a column B to a No. 1 column, adjusting a column C to a No. 2 column, adjusting a column a which is washed with water to a No. 3 column, and starting to sample with brine for tx being 200min for 50 BV. And (4) eluting the A column for t1 min, and entering a desorption section to start desorption. And starting the group II when the leaching is finished for 50min, sequentially adjusting the saturated D columns to a leaching section, simultaneously adjusting the column E to the No. 1 column, adjusting the column F to the No. 2 column, adjusting the washed column b to the No. 3 column by the numerical control system, and starting to sample by introducing brine for 200min for 50 BV.

(3) The desorption t2 of the A column is finished in the desorption section for 30min, and the D column is still in the leaching section. The column A enters a water washing section, and water washing is started for t3 ═ 20 min. And after the D column is leached for 50min, entering a desorption section. After the column A is washed with water, the column A recovers the adsorption capacity again, and is marked as A'. And starting a group III, sequentially adjusting the saturated G columns to a leaching section, simultaneously adjusting the column H to a No. 1 column, adjusting the column I to a No. 2 column, adjusting the column A' which is well washed with water to a No. 3 column, and starting to sample by introducing brine for 200min for 50 BV.

(4) And adjusting the saturated G column to a leaching section through a numerical control system, leaching for 50min, just desorbing and washing the D column, and recovering and recording as D'. Starting the IV group, adjusting the sample IV group to be KLD', introducing brine, keeping the sample constant at 50BV, and enabling the J column to enter a leaching section. And (3) after the G column is sequentially adjusted to a desorption section and a water washing section from the elution section for 50min, the adsorption capacity of the G column is recovered and is marked as G'. Meanwhile, the adsorption of the group 1 of the sample BCa is completed, and the B column is saturated. And (5) after the J column is leached for 50min, entering a desorption section.

(5) And adjusting the saturated B column to a leaching section through a numerical control system, adjusting the group 1 of the sample to be CaG', and keeping the sample water unchanged for 50BV for 200 min.

(6) And the J column enters a water washing section after desorption for 30min from the desorption section.

(7) And (3) after the J column is washed for 20min in the water washing section, the J column recovers the adsorption capacity, the adsorption capacity is recorded as J', the group II EFb finishes 50BV, the E column is saturated, and the E column enters the leaching stage. J 'participates in group II FbJ' sample loop. And after the elution of the column B is finished, sequentially entering a desorption section and a water washing section to start desorption and water washing. And B ' is recorded as B ' after the column B is washed with water, HIA ' of the group III of the sample is adsorbed completely, and the column H is saturated in adsorption.

(8) And adjusting the saturated H column to a leaching section by a numerical control system, adjusting the group III of the running sample to be IA 'B', and introducing brine for 200min while keeping the running sample of 50 BV. And (3) the E column enters a desorption stage, after 50min, the desorption and water washing stage is completed, the E is recovered to be E ', meanwhile, the KLD' of the IV group is completely adsorbed, the K column is saturated, and the K column enters a leaching stage. E ' is involved in LD ' E ' of group IV.

The above steps are repeated to form a cross type simulated moving bed mode. The adsorption step sequence is shown in Table 2.

In this example, the initial brine concentration was 86mg/L for lithium ions and 6 ten thousand mg/L for magnesium ions. The desorption solution in the embodiment is 0.15mol/L dilute hydrochloric acid, after single adsorption, the lithium ion concentration of the column tail solution of the 3 rd stage is lower than 8mg/L, the lithium ion concentration in the qualified lithium-rich eluent is 750-1000 mg/L, and the magnesium ion concentration is 120-300 mg/L.

TABLE 2

Example 4

The embodiment provides a simulated moving bed lithium extraction adsorption process, which uses the adsorption system in embodiment 1, wherein 21 adsorption columns are arranged, 18 adsorption columns are located in an adsorption stage, and 3 adsorption columns are located in a leaching stage, a desorption stage and a water washing stage or serve as blanks for standby; in the adsorption stage, every 3 adsorption columns are connected in series to form 1 group, and 6 groups are formed in total, and the groups are arranged in parallel.

In the adsorption process:

The time for each adsorption column to go through one adsorption stage, one leaching stage, one desorption stage and one water washing stage is tx, t1, t2 and t3 respectively, in this embodiment, t1 is 30min, t2 is 40min, t3 is 30min, and tx is 200 min. In the brine to be treated, the concentration of lithium is more than 20mg/L, and the ratio of magnesium to lithium is more than or equal to 10-1000: 1, the temperature of brine in the adsorption column is kept between 5 and 20 ℃.

As shown in table 3, the process flow of this example includes the following steps:

(1) setting an adsorption initial state: firstly, 6 groups of raw brine ABC, DEF, GHI, JKL, MNO and PQR are connected in series, and 100 column volumes (BV) are respectively arranged at the same time. Column A, column D, column G, column J, column M and column P located at column position No. 1, and the adsorption is in a saturated state; column B, column E, column H, column K, column N and column Q at column position No. 2, in a half-saturated state; column C, column F, column I, column L, column N and column R at column position three, unsaturated state.

(2) The SMB intelligent numerical control system can adjust the water inlet and outlet valves and the flow of each column. After 100 BV of loading at 400min, column A, column D, column G, column J, column M and column P were all in adsorption saturation. Firstly, adjusting a saturated A column to a leaching section through a numerical control system, simultaneously adjusting a column B to a No. 1 bit column, adjusting a column C to a No. 2 bit column, adjusting a column to a No. 3 bit column for standby, and starting to sample with brine tx being 200min for 50BV in total. And (4) eluting the A column for t1 min, and entering a desorption section to start desorption. And starting the group II when the leaching is finished for 30min, sequentially adjusting the saturated D columns to a leaching section, simultaneously adjusting the column E to the No. 1 column, adjusting the column F to the No. 2 column, adjusting the column B to the No. 3 column for standby, and starting to sample by introducing brine for 200min, wherein the total amount of 50 BV. And after the D column is leached for 30min, entering a desorption section. And simultaneously starting a group III, sequentially adjusting the saturated G columns to a leaching section, simultaneously adjusting the column H to a No. 1 position column, adjusting the column I to a No. 2 position column, adjusting the standby column c to a No. 3 position column, and starting to carry out sample introduction by brine for 200min for 50 BV. And starting the IV group, the V group and the VI group in the same way.

Other operation steps are similar to those in embodiment 2 and embodiment 3, and are not described again here.

The above steps are repeated to form a cross type simulated moving bed mode. The adsorption step sequence is shown in Table 3.

In this example, the initial brine concentration was 102mg/L for lithium ions and 7 ten thousand mg/L for magnesium ions. The desorption solution in the embodiment is 0.18mol/L dilute hydrochloric acid, after single adsorption, the lithium ion concentration of the column tail solution of the 3 rd stage is lower than 5mg/L, the lithium ion concentration in the qualified lithium-rich eluent is 660-900 mg/L, and the magnesium ion concentration is 100-270 mg/L.

TABLE 3

Example 5

The present embodiment is basically the same as embodiment 4, but different from the following:

the number of the adsorption columns is 20, 18 adsorption columns are positioned in the adsorption stage, and 2 adsorption columns are positioned in the leaching stage, the desorption stage and the water washing stage or are used as blanks for standby.

t 1-50 min, t 2-30 min, t 3-20 min, tx-300 min. In the brine to be treated, the concentration of lithium is more than 20mg/L, and the ratio of magnesium to lithium is more than or equal to 10-1000: 1, the temperature of brine in the adsorption column is kept between 5 and 20 ℃.

As shown in table 4, the process flow of this example includes the following steps:

(1) setting an adsorption initial state: firstly, 6 groups of raw brine ABC, DEF, GHI, JKL, MNO and PQR are connected in series, and 100 column volumes (BV) are respectively arranged at the same time. A column A, a column D, a column G, a column J, a column M and a column P which are positioned at the column position No. 1 are in an adsorption saturation state; column B, column E, column H, column K, column N and column Q at column position No. 2, in a half-saturated state; column C, column F, column I, column L, column N and column R at column position three, unsaturated state.

(2) The SMB intelligent numerical control system can adjust the water inlet and outlet valves and the flow of each column. After 100 BV of loading at 400min, column A, column D, column G, column J, column M and column P were all in adsorption saturation. Firstly, adjusting a saturated A column to a leaching section through a numerical control system, simultaneously adjusting a column B to a No. 1 bit column, adjusting a column C to a No. 2 bit column, adjusting a column to a No. 3 bit column for standby, and starting to sample with brine tx being 200min for 50BV in total. And (4) eluting the A column for t1 min, and entering a desorption section to start desorption. And starting the group II when the leaching is finished for 50min, sequentially adjusting the saturated D columns to a leaching section, simultaneously adjusting the column E to the No. 1 column, adjusting the column F to the No. 2 column, adjusting the column B to the No. 3 column for standby, and starting to sample by introducing brine for 200min for 50 BV. And after the D column is leached for 50min, entering a desorption section. At the moment, the elution, desorption and water washing of the column A are finished for 100min, and the column A is recovered and recorded as A'. And simultaneously starting a group III, sequentially adjusting the saturated G columns to a leaching section, simultaneously adjusting the column H to a No. 1 column, adjusting the column I to a No. 2 column, adjusting the recovered A' column to a No. 3 column, and starting to perform sample running for 200min by introducing brine for 50 BV. And starting the IV group, the V group and the VI group in the same way.

Other operation steps are similar to those in embodiments 2 to 4, and are not described again.

The above steps are repeated to form a cross type simulated moving bed mode. The adsorption step sequence is shown in Table 4.

In this example, the initial brine concentration was 94mg/L for lithium ions and 11 ten thousand mg/L for magnesium ions. The desorption solution in the embodiment is 0.2mol/L dilute hydrochloric acid, after single adsorption, the lithium ion concentration of the column tail solution of the 3 rd stage is lower than 8mg/L, the lithium ion concentration in the qualified lithium-rich eluent is 560-1130 mg/L, and the magnesium ion concentration is 210-360 mg/L.

TABLE 4

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A crossed simulated moving bed lithium extraction adsorption process is characterized by comprising the following steps:

wherein: keeping 3N adsorption columns in an adsorption stage in any time period, wherein the N adsorption columns are in a leaching stage, a desorption stage and a water washing stage or are blank for standby, N is a natural number not less than 2, and N is a non-0 natural number less than N;

2. The adsorption process of claim 1, wherein n is an even number not less than 2.

3. The adsorption process of claim 1, wherein the adsorption system further comprises a control unit that controls valves and/or pumps.

4. The adsorption process of claim 1, wherein the ion sieve adsorbent is a manganese-based or titanium-based adsorbent.

5. The adsorption process according to claim 1, wherein in the brine to be treated, the lithium concentration is more than 20mg/L, the magnesium-lithium ratio is more than or equal to 10-1000: 1, the temperature of brine in the adsorption column is kept between 5 and 20 ℃.

6. The adsorption process according to any one of claims 1 to 5, wherein the lithium extraction adsorption stage specifically comprises the steps of:

(1) setting an adsorption initial state: in the n groups of adsorption columns, each group of the 1 st-stage adsorption columns is in an adsorption saturated state, each group of the 2 nd-stage adsorption columns is in a semi-saturated state, and each group of the 3 rd-stage adsorption columns is in a blank state; n adsorption columns are used as standby adsorption columns which are in a blank state;

when the 1 adsorption column which is saturated by adsorption is subjected to a leaching stage, connecting 1 adsorption column to be used in series at the tail end of the group as a 3 rd-stage adsorption column, using the original 2 nd and 3 rd-stage adsorption columns as new 1 st and 2 nd-stage adsorption columns, and performing an adsorption stage until the new 1 st-stage adsorption column is saturated again by adsorption;

7. The adsorption process of claim 6, wherein the time for each adsorption column to go through the adsorption stage, the leaching stage, the desorption stage and the water washing stage is respectively set to tx, t1, t2 and t3, t1+ t2+ t3 ≦ tx/p, and p is a natural number not less than 1; the tx/T is rounded down to obtain n; when n ≠ 2, T ═ T1; when n is 2, T is 2T 1.

8. The adsorption process of claim 7, wherein n is 2 to 4, p is 1 to 3, and t1+ t2+ t3 is 80 to 300 min.

9. The adsorption process of claim 6, wherein the adsorption process is characterized by:

an adsorption stage: the liquid inlet end of the adsorption column is communicated with a raw brine feeding tank, and the liquid outlet end of the adsorption column is communicated with an adsorption tail liquid container;

a leaching stage: the liquid inlet end of the adsorption column is communicated with the low-magnesium water tank, and the liquid outlet end of the adsorption column is communicated with the raw brine feeding tank and the low-magnesium water tank;

10. The adsorption process of claim 9, wherein the adsorption stage is completed at the end point of the 1 st adsorption column being saturated in adsorption, the tail liquid from the 1 st adsorption column having a lithium concentration of 80-100% of the original brine concentration, and the tail liquid from the 3 rd adsorption column having a lithium concentration of 1-10% of the original brine concentration;