CN114086006B

CN114086006B - Lithium extraction process for coupling powdery lithium adsorbent with hollow fiber membrane

Info

Publication number: CN114086006B
Application number: CN202111388808.8A
Authority: CN
Inventors: 徐徐; 杨刚; 孙朋飞; 高丽; 王苏琴; 年敏
Original assignee: Jiangsu Liboxing Water Technology Co ltd; Nanjing Tech University
Current assignee: Jiangsu Liboxing Water Technology Co ltd; Nanjing Tech University
Priority date: 2021-11-22
Filing date: 2021-11-22
Publication date: 2023-03-21
Anticipated expiration: 2041-11-22
Also published as: CN114086006A

Abstract

The invention provides a lithium extraction process for a powdery lithium adsorbent coupled hollow fiber membrane, which comprises the following steps: (1) Adjusting the pH value of the lithium-containing brine by using an alkaline solution to obtain alkaline lithium-containing brine; (2) Carrying out cyclic dynamic adsorption on alkaline lithium-containing brine by using a powdery lithium adsorbent to obtain an adsorbed solid-liquid mixture, and carrying out first solid-liquid membrane separation to obtain a lithium-containing adsorbent I and lithium-removing brine; (3) Carrying out cyclic dynamic washing on the lithium-containing adsorbent I by using pure water to obtain a washing solid-liquid mixture containing the lithium-containing adsorbent, and carrying out second solid-liquid membrane separation to obtain a lithium-containing adsorbent II and washing wastewater; (4) And (3) performing cyclic dynamic desorption on the lithium-containing adsorbent II by using desorption liquid to obtain a desorbed solid-liquid mixture, and performing third solid-liquid membrane separation to obtain a regenerated powdery lithium adsorbent and a lithium-rich liquid. The method has the characteristics of novelty, high efficiency and low cost, greatly improves the lithium extraction efficiency of the brine and the lithium ion yield, and has remarkable economic and social benefits.

Description

Lithium extraction process for coupling powdery lithium adsorbent with hollow fiber membrane

Technical Field

The invention belongs to the technical field of lithium resource extraction, and particularly relates to a lithium extraction process for a powdery lithium adsorbent coupled hollow fiber membrane.

Background

Lithium is called industrial monosodium glutamate, an important element for promoting world progress and an energy element in the 21 st century, and is widely applied to industries of new energy, ceramic glass manufacturing, chemical industry, metallurgy, medical treatment and the like.

In global lithium resources, the lithium ore and the lithium brine respectively account for 38.2 percent and 61.8 percent of the total amount, the lithium storage amount in the brine is huge, and the lithium extraction from the brine becomes a main lithium extraction way along with the continuous increase of the demand of lithium resources. China is a large lithium resource reserve country, wherein the proven reserve of the salt lake brine lithium resource accounts for about 80 percent of the total amount, accounts for 1/3 of the world salt lake brine lithium resource, is mainly distributed in high-altitude areas such as Qinghai and Tibet, and occupies more than half of the lithium resource reserve of China by taking the maximum reserve of the Qinghai salt lake brine lithium resource. However, most of the salt lake brine in China has the characteristics of low lithium content and high magnesium-lithium ratio, and the difficulty in extracting lithium from the salt lake brine is brought.

At present, methods for extracting lithium from brine mainly comprise an adsorption method, a precipitation method, an extraction method, a membrane method, a calcination leaching method and the like, wherein the adsorption method for extracting lithium from brine is one of the current research hotspots, especially the field of extracting lithium from brine with high magnesium-lithium ratio, and the method is to utilize a lithium adsorbent for extracting Li in brine ⁺ Adsorbing, and desorbing Li ⁺ And (5) desorbing, further purifying the obtained lithium-rich liquid, and preparing the required lithium product.

In the existing lithium extraction technology, CN201410555213.0 adopts an adsorption method to extract lithium, and static Li is carried out in an adsorption tank ⁺ After adsorption, separating the adsorbent by using a ceramic membrane and a plate-and-frame filter press, adding the adsorbent into a desorption tank for static desorption, and performing nanofiltration, ion exchange, RO, electrodialysis, precipitation, impurity removal and other processes on the obtained desorption solution to obtain the battery grade Li ₂ CO ₃ . Patent CN201810981694.X mixes ion sieve adsorbent and polyacrylonitrile by dry-wet spinning and casts into hollow fiber membrane, and builds membrane module, and carries out brine circulation adsorption and lithium extraction. In patent CN201910212673.6, a polymer-containing monomer is introduced into a manganese-based lithium ion sieve by ultrasound, an intercalation polymer @ manganese-based lithium ion sieve composite material is prepared through a polymerization reaction, and the composite material and PVDF are dissolved in DMF to finally prepare an intercalation polymer lithium ion sieve/PVDF film, wherein the prepared film has high lithium ion adsorption capacity and selectivity. The patent technologies have the problems of large reduction of the actual adsorption capacity of the lithium adsorbent, complex membrane preparation process, long time consumption of static adsorption and desorption, large consumption of pure water and desorption liquid and the like, and the development of a high-efficiency and high-selectivity lithium extraction process and device is urgently needed.

Disclosure of Invention

In order to solve the problems, the invention provides a lithium extraction process for coupling a powdery lithium adsorbent with a hollow fiber membrane, which comprises the following steps:

(1) In an adsorption tank, adjusting the pH value of lithium-containing brine by using an alkaline solution to obtain alkaline lithium-containing brine; the pH value of the alkaline lithium-containing brine is specifically 7.5-9.5;

(2) Carrying out cyclic dynamic adsorption on alkaline lithium-containing brine by using a powdery lithium adsorbent to obtain an adsorbed solid-liquid mixture, and carrying out first solid-liquid membrane separation on the adsorbed solid-liquid mixture to obtain a lithium-containing adsorbent I and lithium-removing brine;

(3) Carrying out cyclic dynamic washing on the lithium-containing adsorbent I by using pure water to obtain a washing solid-liquid mixture including the lithium-containing adsorbent after the dynamic washing is finished, and carrying out second solid-liquid membrane separation on the washing solid-liquid mixture to obtain a lithium-containing adsorbent II and washing wastewater;

(4) And (3) carrying out cyclic dynamic desorption on the lithium-containing adsorbent II by using desorption liquid to obtain a desorbed solid-liquid mixture, and carrying out third solid-liquid membrane separation on the desorbed solid-liquid mixture to obtain a regenerated powdery lithium adsorbent and a lithium-rich liquid.

Wherein the powdery lithium adsorbent is one or a mixture of several of ion sieve type adsorbent, aluminum salt adsorbent, modified mineral adsorbent, macrocyclic compound type adsorbent and hydroxide type adsorbent.

Aiming at different types of powdery lithium adsorbents, the alkaline lithium-containing brine needs to be in different pH value ranges to promote the adsorption capacity of the adsorbents to the maximum extent, and when an ion sieve type adsorbent is adopted, the pH value of the alkaline lithium-containing brine is preferably 8.5-9.5; when an aluminum salt adsorbent and a hydroxide adsorbent are adopted, the pH value of the alkaline lithium-containing brine is preferably 7.5-8.0; when the modified mineral adsorbent is adopted, the pH value of the alkaline lithium-containing brine is preferably 7.0-8.0; when a macrocyclic compound type adsorbent is used, the pH of the alkaline lithium-containing brine is preferably 7.0 to 8.5. When the adsorbents are used in combination, it is preferable to conduct experiments to determine the optimum pH range.

The alkaline solution is one or a mixture of more of sodium hydroxide solution, sodium carbonate solution and sodium bicarbonate solution, and the concentration of the solution is 10 to 40 weight percent.

During the process of adjusting the pH value, stirring is kept, and the stirring speed is controlled to be 50-120 r/min, preferably 60-90 r/min. According to the lithium-containing brine in the adsorption tank, the stirring effect is ensured, the stirring speed is prevented from being too high, and the electric energy consumption is reduced.

In the application, firstly, the pH value of the lithium-containing brine is adjusted, and after the pH value is adjusted, the lithium adsorbent can play a role in promoting the lithium ion adsorption process; then, lithium ion adsorption is carried out by utilizing the powdery lithium adsorbent, and a better adsorption effect can be obtained by virtue of larger adsorption capacity and specific surface area. At present, in order to separate the lithium adsorbent in the lithium extraction process, the lithium adsorbent is generally granulated to form particles with the particle size of 0.5-5 mm or mixed casting films of the particles, the two types of lithium adsorbents are adhered to corresponding carriers, 20-50% of adsorption sites are sacrificed, the adsorption capacity to lithium ions is obviously reduced, and meanwhile, due to the limitation of the mechanical strength of the carriers, external forces such as stirring and the like cannot be used for increasing the meeting probability of the lithium adsorbent and the lithium ions in the lithium-containing brine, most of the lithium adsorbents can only adopt static adsorption, static washing and static desorption, the lithium extraction efficiency is low, and the time consumption is long. In this application, powdered lithium adsorbent has been adopted, these powdered lithium adsorbents need not to carry out granulation or cast membrane and handle, have reduced the process on the one hand, have practiced thrift the energy, have reduced manufacturing cost, and on the other hand is because the original structure of lithium adsorbent has been remain completely, and is more to lithium ion's adsorption site, and adsorption capacity is also bigger, and powdered lithium adsorbent mechanical strength is high, does not receive external force restriction such as stirring, can realize the abundant contact of whole adsorption process lithium ion and powdered lithium adsorbent.

In the embodiment of the application, the difference of the adsorption performance of the same ion sieve type lithium adsorbent under different appearance forms is compared, wherein the adsorption capacity of the powdery ion sieve type lithium adsorbent can reach 30-37 mg/g according to the lithium extraction process of the application, and the adsorption capacity of the granular ion sieve type lithium adsorbent can only reach 15.7mg/g according to the existing process. As can be seen from the comparison of the data, the powdered lithium adsorbent has a significant advantage in adsorption capacity over the granular lithium adsorbent.

Further, in order to ensure the adsorption effect of the lithium adsorbent and the solid-liquid separation effect of the hollow fiber membrane, the particle size range of the powdery lithium adsorbent is selected to be 200-600 nm. When the particle size of the lithium adsorbent is too small, the hollow fiber membrane pores are easy to block, the solid-liquid membrane separation effect is influenced, the backflushing frequency is increased, the equipment loss is accelerated, and the operation investment is increased; when the particle size of the lithium adsorbent is too large, the specific surface area of the lithium adsorbent is reduced, corresponding lithium adsorbent adsorption sites are also reduced, the adsorption capacity of the lithium adsorbent is unfavorable, and the particle size is too large, so that the sedimentation tendency of the lithium adsorbent is easily increased, and the stable cycle is not favorable.

Specifically, in the step (1), the lithium-containing brine is salt lake brine or underground brine; mg in lithium-containing brine ²⁺ With Li ⁺ The mass ratio of 1:1-1500; li in lithium-containing brine ⁺ The mass percentage concentration is 0.002-2%.

The lithium extraction process adopts the powdery lithium adsorbent, avoids the adsorption site loss caused by granulation or cast film treatment, has higher adsorption performance, effectively promotes the adsorption process of the lithium adsorbent to lithium ions by utilizing a circulating dynamic adsorption system, has wider applicable brine water quality conditions compared with other methods, and is particularly suitable for extracting lithium from brine with high magnesium-lithium ratio and low lithium content.

Specifically, in the step (2), the cyclic dynamic adsorption is to add a powdery lithium adsorbent into the alkaline lithium-containing brine, stir the mixture uniformly to form a first cyclic liquid, so that the first cyclic liquid flows in a first cycle between the adsorption tank and the membrane separation device, and the powdery lithium adsorbent dynamically adsorbs lithium ions; and after the dynamic adsorption is finished, forming an adsorption solid-liquid mixture, and performing first solid-liquid membrane separation on the adsorption solid-liquid mixture by using the membrane separation device to obtain a lithium-containing adsorbent I and lithium-removing brine.

In the application, dynamic adsorption and first solid-liquid membrane separation are carried out in the same device, wherein the membrane separation device is used as different equipment at different stages, and during dynamic adsorption, the membrane separation device does not start a membrane separation unit and is only used as an adsorption container, so that the first circulating liquid can smoothly complete circulating flow, and the smooth implementation of circulating dynamic adsorption is ensured. In the first solid-liquid membrane separation process, the membrane separation device recovers the filtering function thereof to obtain the lithium-containing adsorbent I. In the process of carrying out first solid-liquid membrane separation, the continuous flow of the first circulating liquid needs to be ensured, so that the concentration of the adsorbent in the first circulating liquid can be gradually reduced, and the phenomenon that a large amount of adsorbent is retained in a membrane separation device to form a thick filter layer to influence the filtration efficiency is avoided.

Above-mentioned design, make full use of carries lithium technology in-system device, need not additionally to add the circulation and adsorb the buffer tank, makes each material concentration of upper and lower floor in the adsorption tank even, avoids powdered lithium adsorbent to subside, increases the meeting probability of powdered lithium adsorbent and lithium ion simultaneously, realizes the dynamic adsorption of the two.

Further, the addition amount of the powdery lithium adsorbent in the alkaline lithium-containing brine is 0.5 to 8g/L, and more preferably 1 to 5g/L; and adding alkaline lithium-containing brine into the powdery lithium adsorbent, performing first stirring, and stirring for 10-30 min to form a first circulating liquid, wherein the stirring speed of the first stirring is 60-120 r/min. The first stirring time is preferably 15 to 20min, and the stirring speed of the first stirring is preferably 70 to 90r/min.

When the addition amount of the powdery lithium adsorbent is too small, the adsorption efficiency of the powdery lithium adsorbent on lithium ions in lithium-containing brine is low, the adsorption time is long, the content of residual lithium ions in the lithium-removing brine is high, and the lithium extraction effect is poor; when the addition amount is too large, the lithium extraction cost is increased, the difficulty of solid-liquid membrane separation is also increased, and the comprehensive efficiency of the lithium extraction process is influenced. The first stirring is to fully wet and uniformly mix the powdery lithium adsorbent and the alkaline lithium-containing brine, and because the powdery lithium adsorbent has a large bulk specific gravity and a strong sedimentation tendency, reasonable stirring time and stirring speed must be ensured in order to avoid sedimentation of the powdery lithium adsorbent or over-high local concentration, and the use effect of the powdery lithium adsorbent can be influenced by over-short time or over-low stirring speed.

Further, when the cyclic dynamic adsorption is carried out, the temperature of the first circulating liquid is-5-45 ℃, more preferably 10-35 ℃, and the cyclic dynamic adsorption time is 1-4 h, more preferably 2-3 h;

in the case of the cyclic dynamic adsorption, the first circulating liquid in the adsorption tank is kept under second stirring at a stirring speed of 30 to 80r/min, more preferably 40 to 60r/min.

The lithium extraction process has the advantages that the salt lake or underground lithium-containing brine has high salt content and low freezing point, the lithium extraction process has low requirement on brine temperature, and the practical production time per year is long. However, the temperature is too low or too high, which easily causes unnecessary abnormal problems of the hollow fiber membrane separation device and influences the stability of the lithium extraction process system. The circulating dynamic adsorption can effectively improve the lithium extraction efficiency of the lithium adsorbent, shorten the lithium extraction time and reduce the concentration of residual lithium ions in the lithium removal brine, but the short adsorption time can cause the lithium ions not to be fully adsorbed, cause the waste of the adsorbent and possibly cause the reworking and re-adsorption of the lithium-containing brine; the adsorption time is too long, and although the lithium extraction yield can be improved by a small amount, the cost performance is lower compared with the input energy and time.

Further, the membrane separation device is a hollow fiber membrane separation device, and negative pressure suction is adopted when the first solid-liquid membrane separation is carried out, wherein the suction pressure is-0.4 to-0.8 MPa, more preferably-0.5 to-0.7 MPa, the membrane passing temperature is 0 to 80 ℃, more preferably 10 to 60 ℃, and the membrane surface flow velocity is 1 to 3m/s.

The membrane separation device is a hollow fiber membrane separation device and comprises a microfiltration membrane and an ultrafiltration membrane, wherein the ultrafiltration membrane is preferably adopted, the average pore diameter of the membrane is 15-150 nm, and the porosity is 35-50%; the membrane separation mode comprises an external pressure type and an internal pressure type; the membrane material comprises an inorganic membrane and an organic membrane, and preferably comprises a ceramic membrane, a polyvinylidene fluoride (PVDF) membrane and a polyether sulfone (PES) membrane; the membrane separation device group type includes a single-stage type and a combined type.

In the first solid-liquid membrane separation process, the suction pressure is recommended to be within a recommended range, particularly recommended to be within a preferable range, when the suction pressure is too low, the membrane separation effect is poor, and the solid-liquid membrane separation time is long; when the pumping pressure is too high, on one hand, the requirement on the membrane separation device is high, the corresponding cost is increased, and on the other hand, the lithium adsorbent is caused to block the surface of the membrane too fast, so that the discharge of the lithium removal brine is influenced. When the flow rate of the membrane surface is too low, the lithium adsorbent is easy to deposit, the back-flushing frequency is increased, and the membrane separation efficiency is influenced; when the flow velocity of the membrane surface is too high, the requirement on a delivery pump is high, the energy consumption is high, and meanwhile, the lithium-containing adsorbent I can be suspended and circulated for a long time, which is not beneficial to solid-liquid membrane separation.

Further, in the step (3), in the step of cyclic dynamic washing, pure water is added into the lithium-containing adsorbent I to form second cyclic liquid, then the second cyclic liquid is subjected to second cyclic flow between the membrane separation device and the cyclic tank to dynamically wash the lithium-containing adsorbent I, after the dynamic washing is completed, a washing solid-liquid mixture is formed, and the membrane separation device is used for performing second solid-liquid membrane separation on the washing solid-liquid mixture to obtain a lithium-containing adsorbent II and washing wastewater;

when dynamic washing is carried out, the temperature of the second circulating liquid is 5-60 ℃, more preferably 10-35 ℃, and the washing time is 5-20 min, more preferably 10-20 min; the flushing time is the duration of the second circulation flow;

the membrane separation device is a hollow fiber membrane separation device, and negative pressure suction is adopted when second solid-liquid membrane separation is carried out, wherein the suction pressure is-0.4 to-0.8 MPa, the more preferable pressure is-0.5 to-0.6 MPa, the membrane passing temperature is 5 to 70 ℃, the more preferable temperature is 10 to 50 ℃, and the membrane surface flow rate is 1 to 3m/s.

In the application, dynamic washing and second solid-liquid membrane separation are both carried out in the same device, wherein the membrane separation device is used as different equipment in different stages, and when the dynamic washing is carried out, the membrane separation device does not start a membrane separation unit and is only used as an overflowing container, so that the second circulating liquid can smoothly complete circulating flow, and in the circulating flow, the lithium-containing adsorbent II is washed, so that the washing is smoothly carried out. In the second solid-liquid membrane separation process, the membrane separation device recovers the filtering function of the device to obtain the lithium-containing adsorbent II. In the process of performing the second solid-liquid membrane separation, the continuous flow of the second circulating liquid needs to be ensured, so that the concentration of the adsorbent in the second circulating liquid can be gradually reduced, and a large amount of adsorbent is prevented from being retained in the membrane separation device to form a thick filter layer, which affects the filtration efficiency.

When the dynamic washing time is too short, the washing effect is poor, more impurity ions exist on the surface of the obtained lithium-containing adsorbent II, and the impurity ions enter the lithium-rich liquid along with the desorption process, so that the purification of the final lithium product is difficult; the washing time is too long, which causes energy waste and causes a small amount of lithium ions to be separated out, and the lithium ion yield of the lithium adsorbent is affected.

Further, in the step (4), in the cyclic dynamic desorption, desorption liquid is added into the lithium-containing adsorbent II to form third circulation liquid, then the third circulation liquid is subjected to third circulation flow between the membrane separation device and the second circulation tank, dynamic desorption is performed on the lithium-containing adsorbent II, after the dynamic desorption is completed, a desorption solid-liquid mixture is formed, and the membrane separation device is used for performing third solid-liquid membrane separation on the desorption solid-liquid mixture to obtain a regenerated powder lithium adsorbent and a lithium-rich liquid;

when the dynamic desorption is carried out, the temperature of the third circulating liquid is 5-60 ℃, the further optimization is 10-40 ℃, and the desorption time is 1-3 h, the further optimization is 2-3 h;

the membrane separation device is a hollow fiber membrane separation device, and negative pressure suction is adopted when the third solid-liquid membrane separation is carried out, wherein the suction pressure is-0.4 to-0.8 MPa, more preferably-0.5 to-0.7 MPa, the membrane passing temperature is 5 to 70 ℃, more preferably 10 to 50 ℃, and the membrane surface flow rate is 1 to 3m/s.

In the application, dynamic desorption and third solid-liquid membrane separation are carried out in the same device, the membrane separation device serves as different equipment in different stages, and the membrane separation unit is not opened by the membrane separation device and serves as a desorption container only during dynamic desorption, so that third circulating liquid can smoothly complete circulating flow, and desorption is guaranteed to be smoothly carried out. In the third solid-liquid membrane separation process, the membrane separation device recovers the filtering function of the device to obtain a regenerated powdery lithium adsorbent and a lithium-rich liquid. In the process of carrying out the third solid-liquid membrane separation, the continuous flow of the third circulating liquid needs to be ensured, so that the concentration of the adsorbent in the third circulating liquid can be gradually reduced, and the phenomenon that a large amount of adsorbent is retained in the membrane separation device to form a thick filter layer to influence the filtration efficiency is avoided.

In the present application, in order to avoid the repeated installation of the equipment and the high purchase cost and maintenance cost of the equipment, it is preferable that the first circulation tank and the second circulation tank are the same circulation tank.

When the desorption time is too short, lithium ions adsorbed in the lithium-containing adsorbent II are not fully desorbed, and the desorption rate of the lithium ions and the actual lithium ion yield are influenced; when the desorption time is too long, the desorption rate of the desorption solution to the lithium-containing adsorbent II tends to be stable, the desorbed lithium ions are less, and the cost performance is not high.

Further, in order to improve the utilization rate of equipment, the same membrane separation device is adopted for carrying out first solid-liquid membrane separation, second solid-liquid membrane separation and third solid-liquid membrane separation; when the cyclic dynamic adsorption, the cyclic dynamic flushing and the cyclic dynamic desorption are carried out, the first circulating liquid during the cyclic dynamic adsorption, the second circulating liquid during the cyclic dynamic flushing and the third circulating liquid during the cyclic dynamic desorption are all carried out by the membrane separation device. And when the circulating dynamic adsorption, the circulating dynamic flushing and the circulating dynamic desorption are carried out, the same circulating pump is adopted as a circulating power device.

The design not only can improve the utilization rate of the equipment and reduce the purchase cost and the maintenance cost of the equipment, but also can avoid the transfer of the lithium adsorbent, and because the lithium adsorbent is always in a controllable space, the use amounts of the washing pure water and the desorption liquid can be obviously reduced.

In the lithium extraction process, the lithium adsorbent is subjected to adsorption, cleaning and desorption steps and is respectively formed into three stages including a lithium adsorbent I, a lithium adsorbent II and a regenerated powdery lithium adsorbent.

The application also has the following overall effects:

1. the lithium extraction process of coupling the powdery lithium adsorbent with the hollow fiber membrane effectively solves the bottleneck problem that the powdery lithium adsorbent is difficult to be applied industrially;

2. the adopted powdery lithium adsorbent avoids the loss of adsorption sites and the reduction of adsorption capacity, structural strength and service life of the powdery lithium adsorbent caused by molding treatment, and retains the original adsorption performance advantage of the powdery lithium adsorbent to the maximum extent;

3. by circulating the dynamic adsorption, flushing and desorption processes, the solid-liquid mixture in each step is circulated, the adsorption, flushing and desorption efficiency and the lithium ion yield of the process are greatly improved, and the time for the adsorption, flushing and desorption processes is obviously shortened;

4. because the circulating flushing loop and the circulating desorption loop which do not pass through the adsorption tank are adopted, the adding amount of the flushing pure water and the desorption liquid can be controlled as required, and the consumption of the pure water and the desorption liquid is effectively reduced.

5. The selection range of the powdery lithium adsorbent in the lithium extraction process is wide, and the process can be applied to all self-grinding or commercially available ion sieve type adsorbents, aluminum salt adsorbents, modified mineral adsorbents, macrocyclic compound adsorbents, hydroxide adsorbents and mixtures of the above materials with the powder particle size of 200-600 nm.

6. The lithium extraction process has wide application range, is suitable for most of lithium extraction occasions of brine at home and abroad, and is particularly suitable for extracting lithium from brine with high magnesium-lithium ratio and low lithium content.

In conclusion, the application provides a novel, efficient and low-cost brine lithium extraction process, the brine lithium extraction efficiency and the lithium ion yield are greatly improved, and the economic and social benefits are remarkable.

Drawings

FIG. 1 is a process flow diagram of the present application.

Fig. 2 is a schematic view of a lithium extraction device for use in the present application.

FIG. 3 is a layout of the apparatus involved in the cyclic dynamic adsorption and the first solid-liquid membrane separation.

FIG. 4 is a layout of the equipment involved in circulating dynamic washing and performing the second solid-liquid membrane separation.

FIG. 5 is a layout of the apparatus involved in the cyclic dynamic desorption and the performance of the third solid-liquid membrane separation.

Detailed Description

First, a lithium extraction device used in the present application will be described, with reference to fig. 2, the lithium extraction device includes an adsorption tank 10, a circulation pump 20, a membrane separation device 30, and a buffer tank 40, a stirrer 11 is installed in the adsorption tank, a motor 12 for driving the stirrer 11 to rotate is installed on the top of the adsorption tank, a feed pipe 13 and a circulation feed connection pipe 15 are installed on the upper portion of the adsorption tank 10, a circulation discharge connection pipe 14 is installed on the lower portion of the adsorption tank 10, a drain pipe 19 is installed on the bottom of the adsorption tank 10, a drain valve 191 is installed on the drain pipe 19, and an alkali inlet pipe 181 and an adsorbent inlet pipe 182 are installed on the top of the adsorption tank.

The inlet of the circulating pump is connected with two liquid inlet pipes, which are a first liquid inlet pipe 21 and a second liquid inlet pipe 22 respectively, wherein the first liquid inlet pipe 21 is connected to the circulating discharge interface pipe 14, the first liquid inlet pipe is provided with a first liquid inlet switching valve 16, the second liquid inlet pipe 22 is connected to a circulating liquid outlet connecting pipe 42 at the bottom of the buffer tank 40, and the second liquid inlet pipe 22 is provided with a second liquid inlet switching valve 43.

The outlet of the circulation pump is connected to the feed inlet 31 of the membrane separation device 30. A concentrated solution outlet 32 of the membrane separation device 30 is connected with a first liquid outlet pipe 34 and a second liquid outlet pipe 35, wherein the first liquid outlet pipe 34 is communicated with the circulating feeding interface pipe 15, and a first liquid outlet switching valve 17 is arranged on the first liquid outlet pipe; the second liquid outlet pipe 35 is communicated with the circulating liquid inlet connecting pipe 41 on the upper part of the buffer tank 40, and a second liquid outlet switching valve 44 is arranged on the second liquid outlet pipe 35.

The vacuum outlet of the vacuum device 50 is connected to the clean liquid outlet 33 of the membrane separation device 30 via the intermediate tank 51, and the clean liquid outlet 33 is provided with a shut-off valve 53. A waste water outlet 54 is provided at the bottom of the intermediate tub 51, and a waste water valve 55 is mounted on the waste water outlet 54. In this embodiment, the vacuum device 50 is a roots vacuum pump, and it is understood that in other embodiments, the vacuum device may also be other vacuum devices, such as a rotary vane vacuum pump or a water ring vacuum pump.

For convenience of operation, in this embodiment, the lithium extraction device is further provided with a water tank 61 and a desorption liquid tank 62, wherein the water tank 61 is used for containing pure water, and the desorption liquid tank 62 is used for containing desorption liquid. It can be understood that when the consumption of pure water and desorption liquid can in time satisfy the needs, water pitcher 61 and desorption liquid jar 62 all can cancel, in process of production, directly add pure water and desorption liquid respectively to the circulating tank as required.

The membrane separation device is a hollow fiber membrane separation device, and specifically in the embodiment, an ultrafiltration membrane is adopted, the average pore diameter of the membrane is 50nm, and the porosity is 35-45%; membrane separation means include external pressure type; the membrane material is polyvinylidene fluoride (PVDF) membrane; the membrane separation device is of a single-stage type.

The following describes a lithium extraction process of coupling a powdery lithium adsorbent to a hollow fiber membrane, and referring to fig. 1, the lithium extraction process is performed by using the above-mentioned lithium extraction device. The lithium extraction process is first generally described as follows, and comprises the following steps:

(1) And introducing lithium-containing brine into the adsorption tank 10 through the feed pipe 13, and then introducing an alkaline solution into the adsorption tank 10 through the alkali inlet pipe 181 until the pH value is set, so as to obtain the lithium-containing brine.

(2) The second outlet switching valve 44, the second inlet pipe 22 and the cut-off valve 33 are closed, and the first outlet switching valve 17 and the first inlet switching valve 16 are opened.

Putting a powdery lithium adsorbent into the adsorption tank 10 through the adsorbent inlet pipe 182, uniformly stirring to form a first circulating liquid, starting the circulating pump 20 to enable the first circulating liquid to flow between the adsorption tank and the membrane separation device in a first circulating mode, and dynamically adsorbing lithium ions by the powdery lithium adsorbent; after the dynamic adsorption is finished, an adsorption solid-liquid mixture is formed. And opening a cut-off valve 53, starting a vacuum device 50, carrying out first solid-liquid membrane separation on the adsorbed solid-liquid mixture, feeding the lithium-removed brine into a middle barrel 51, discharging the lithium-removed brine to a wastewater treatment system periodically, and keeping a lithium-containing adsorbent I in a membrane separation device 30.

In the first solid-liquid membrane separation, the circulation pump 20 is kept in operation, and the adsorbed solid-liquid mixture in the adsorption tank and the pipeline is returned to the membrane separation apparatus 30 as much as possible until the solid-liquid separation is completed, and the circulation pump is turned off. Alternatively, the adsorption tank is disposed above the membrane separation device 30, and the adsorbed solid-liquid mixture in the adsorption tank and the pipeline is introduced into the membrane separation device 30 by gravity.

Referring to fig. 3, fig. 3 is a layout diagram of the devices involved in step (2).

(3) The first liquid outlet switching valve 17, the first liquid inlet switching valve 16 and the cut-off valve 33 are closed, the second liquid outlet switching valve 44 and the second liquid inlet pipe 22 are opened, and the pure water in the water tank 61 is added into the buffer tank 40 until the volume is set. And mixing the pure water with the lithium-containing adsorbent I to form a second circulating liquid.

And starting the circulating pump 20 to enable the second circulating liquid to flow between the membrane separation device and the circulating tank 40 in a second circulating mode, dynamically washing the lithium-containing adsorbent I, and forming a washing solid-liquid mixture after the dynamic washing is finished.

And opening the cut-off valve 53, starting the vacuum device 50, performing second solid-liquid membrane separation on the washing solid-liquid mixture, feeding the washing wastewater into the intermediate barrel 51, periodically discharging the washing wastewater into a wastewater treatment system, and retaining the lithium-containing adsorbent II in the membrane separation device 30.

In the second solid-liquid membrane separation, the circulation pump 20 is kept in operation, and the circulation tank and the pipe are returned to the membrane separation device 30 as much as possible until the solid-liquid separation is completed, and the circulation pump is turned off. Or the circulation tank is arranged above the membrane separation device 30, and the flushing solid-liquid mixture in the adsorption tank and the pipeline enters the membrane separation device 30 by utilizing gravity.

Referring to fig. 4, fig. 4 is a layout diagram of the apparatus involved in step (3).

(4) The first liquid outlet switching valve 17, the first liquid inlet switching valve 16 and the shut-off valve 33 are closed, the second liquid outlet switching valve 44 and the second liquid inlet pipe 22 are opened, and the desorption liquid in the desorption liquid tank 62 is added into the buffer tank 40 until the volume is set. And mixing the desorption solution with a lithium-containing adsorbent II to form a third circulating solution.

And starting the circulating pump 20 to make the third circulating liquid flow in a third circulating mode between the membrane separation device and the circulating tank 40, and performing dynamic desorption on the lithium-containing adsorbent II to form a desorbed solid-liquid mixture after the dynamic desorption is completed.

Opening a cut-off valve 53, starting a vacuum device 50, carrying out third solid-liquid membrane separation on the desorbed solid-liquid mixture, feeding the lithium-rich liquid into an intermediate barrel 51, periodically discharging the lithium-rich liquid into a lithium ion purification system, and finally preparing the lithium-rich liquid into a required lithium product; the regenerated powdered lithium sorbent remains within the membrane separation device 30. The next round of production is performed.

Referring to fig. 5, fig. 5 is a layout diagram of the apparatus involved in the step (4).

In the present embodiment, the second circulation liquid and the third circulation liquid are circulated through the same circulation tank when the second circulation flow and the third circulation flow are performed, and it is understood that, in another embodiment, the second circulation flow and the third circulation flow are circulated using different circulation tanks, respectively, for example, between the membrane separation apparatus and the first circulation tank when the second circulation flow is performed; in carrying out the third recycle flow, it is passed between the membrane separation device and the second recycle tank.

In the following specific examples, the khaki salt lake brine, which is characterized by low lithium content, high magnesium-lithium ratio and great difficulty in extracting lithium, was used as the test object, and the mass percentage concentrations of the ions and the magnesium-lithium ratio in the brine are shown in table 1:

TABLE 1 composition of Carr's salt lake brine (wt%)

Na ⁺	K ⁺	Mg ²⁺	Li ⁺	Ca ²⁺	SO ₄ ^2-	Cl ^-	B ³⁺	Mg ²⁺ /Li ⁺
									0.224	0.056	10.0602	0.0094	0.096	0.02	22.78	0.012	1070.2：1

The powdery lithium adsorbent in the application can adopt one or a mixture of several of self-grinding or commercially available ion sieve type adsorbents, aluminum salt adsorbents, modified mineral adsorbents, macrocyclic compound type adsorbents and hydroxide adsorbents, the particle size of the powdery lithium adsorbent is 200-600 nm, and the powdery lithium adsorbent meeting the requirements can be used in the lithium extraction process.

Wherein the ion sieve adsorbent comprises manganese ion sieve adsorbent (such as HMn) ₂ O ₄ 、H _1.33 Mn _1.67 O ₄ 、 H _1.6 Mn _1.6 O ₄ Etc.), titanium-based ion sieve adsorbent (e.g., H) ₂ TiO ₃ 、H ₄ Ti ₅ O ₁₂ Etc.), antimony-based ion sieve adsorbent [ e.g., HSb (OH) ₆ Etc. of]And various doped modified ion sieve adsorbents of the three, wherein after lithium ions are adsorbed by the adsorbents, the adsorbents are generally washed by pure water and then are subjected to acidity treatmentDesorbing the solution, and filtering and separating to obtain the lithium-rich solution and the regenerated manganese ion sieve adsorbent. The aluminum salt adsorbent has a general formula of LiX.2Al (OH) ₃ ·nH ₂ O, wherein X represents an anion (e.g. Cl) ^- And Br ^- ) And n represents the number of crystal water, the adsorbent of the type generally has small adsorption capacity, and pure water is used for flushing and desorption.

The hydroxide-type adsorbent is usually an amorphous structure in which amorphous aluminum hydroxide [ structural formula Al (OH) ]is used ₃ ]Most commonly, pure water is used for both this type of adsorbent rinse and desorption. The modified mineral adsorbent comprises a modified kaolin adsorbent, a modified zeolite adsorbent, a modified montmorillonite adsorbent and the like, and the modified montmorillonite adsorbent is generally washed by pure water after adsorbing lithium ions, desorbed by an acid solution, filtered and separated after desorption to obtain a lithium-rich liquid and a regenerated modified mineral adsorbent.

The macrocyclic compound type adsorbent is formed by more than 12 or 12 atoms in a ring shape, wherein more than 3 coordination atoms are contained, a special cavity structure can selectively adsorb lithium ions, and the macrocyclic compound type adsorbent is typically a calixarene macrocyclic compound type adsorbent and a crown ether type adsorbent.

In some embodiments of the present application, an ion sieve type adsorbent is used, including a titanium-based ion sieve adsorbent and a manganese-based ion sieve adsorbent, and in other embodiments, an aluminum salt adsorbent is used, wherein the titanium-based ion sieve adsorbent contains powder and particles, and the other adsorbents are in powder form. The aluminum salt adsorbent, the titanium ion sieve adsorbent and the manganese ion sieve adsorbent related in each embodiment of the application are self-made products of the team, and the specific preparation methods are respectively as follows:

the preparation method of the aluminum salt adsorbent comprises the following steps: 100g of aluminum chloride and 27.2g of lithium chloride are weighed, mixed, dissolved and fixed in a 1000mL volumetric flask for standby. 500mL of mixed solution of lithium chloride and aluminum chloride is put in an open crystallizer, the reaction temperature is controlled to be 80 ℃, the stirring speed is controlled to be 200r/min, the rotational speed of a peristaltic pump is controlled to adjust the dropping speed to be 3mL/min, and 5mol/L of sodium hydroxide solution is slowly dropped into the mixed solution of lithium chloride and aluminum chloride for coprecipitation reaction. Controlling the end point pH value to be 6-7, washing with water, centrifuging, separating solid from liquid, drying and grinding the obtained solid in a blast oven at 60 ℃ to obtain the aluminum salt adsorbent product. The aluminum salt adsorbent prepared by the method is in a uniform powder shape, the particle size of the adsorbent is 250-550 nm, and the method is suitable for the application example 2.

The preparation method of the powdery titanium ion sieve adsorbent comprises the following steps: dissolving 25g of lithium carbonate in 100mL of absolute ethanol at room temperature, and adding TiO according to the molar ratio of lithium to titanium of 2:1 under magnetic stirring ₂ Continuously stirring for 24h, carrying out spray drying on the obtained slurry at 90 ℃ at a feeding rate of 5ml/min under magnetic stirring to obtain lithium source titanium source mixed powder, uniformly spreading the mixed powder on a ceramic calcining plate for 4.5 g/(200 mm multiplied by 200 mm), heating to 650 ℃ at 2 ℃/min in a muffle furnace, preserving heat for 18h, and naturally cooling to room temperature to obtain a precursor Li ₂ TiO ₃ . Under the condition of magnetic stirring, taking the precursor Li according to the solid-to-liquid ratio of 2g/L ₂ TiO ₃ Adding into 1mol/L hydrochloric acid solution, acid treating for 24H, filtering, washing and drying to obtain titanium ion sieve adsorbent (structural formula is H) ₂ TiO ₃ ). The titanium ion sieve adsorbent prepared by the method is in a uniform powder shape, the particle size of the adsorbent is 250-450 nm, and the method is suitable for the application example 1.

The preparation method of the granular titanium ion sieve adsorbent comprises the following steps: the granular titanium ion sieve adsorbent is prepared by mixing and granulating a precursor of the powdery titanium ion sieve adsorbent and a carrier material to prepare granules, wherein the particle size of the prepared adsorbent granules is 1-3 mm, and the content of active ingredients is 42wt%. Specifically, 36ml of NMP was placed in a 500ml beaker and 5.5g of PVC was added slowly with magnetic stirring. After the PVC is completely dissolved, 7.1g of PEG and 1.2gCA are added for dissolution, and then 10g of Li which is a precursor of the powdery titanium ion sieve adsorbent is slowly added ₂ TiO ₃ Mixing, and stirring for 30min. Dropping the mixture into a 500ml beaker filled with 350ml of deionized water at the speed of 1 drop/second by using a dropping device to obtain the microsphere particles. The dripping is finishedAnd standing for 60min after completion, washing the microsphere particles with deionized water for multiple times, filtering, and drying in a 50 ℃ oven for 24h to obtain precursor particles. Adding precursor particles into 0.5mol/L hydrochloric acid according to the proportion of 2g/120ml, washing to remove lithium and activate, stirring for 6H at 85 ℃, filtering, washing to be neutral, and drying to obtain porous-hydrophilic H ₂ TiO ₃ And (4) ion sieve particles. The granular titanium ion sieve adsorbent prepared by the method has the particle size of 1-3 mm, and is suitable for the comparative example 1 of the application.

The preparation method of the manganese ion sieve adsorbent comprises the following steps: 50g of lithium carbonate was added to 150mL of anhydrous ethanol under magnetic stirring to obtain an ethanol solution of lithium carbonate. According to the molar ratio of lithium to manganese 1:2, manganese nitrate tetrahydrate is metered into the solution, and stirring is continued until the manganese nitrate tetrahydrate is dissolved. And (3) drying the obtained mixed solution at 90 ℃ in vacuum to obtain a brownish red solid, and fully grinding the brownish red solid to obtain the lithium source manganese source mixed powder with high dispersity. Transferring the ground powder to a muffle furnace, heating to 700 ℃ and reacting for 20h to obtain a precursor LiMn ₂ O ₄ . Under the magnetic stirring, taking the LiMn precursor according to the solid-to-liquid ratio of 2g/L ₂ O ₄ Adding 1mol/L hydrochloric acid solution, performing acid treatment for 24h, filtering, washing and drying to obtain manganese ion sieve adsorbent (with structural formula of HMn) ₂ O ₄ ). The manganese ion sieve adsorbent prepared by the method is in a uniform powder shape, has the particle size of 200-500 nm, and is suitable for the application of example 3, example 4 and example 5.

Example 1

(1) Injecting 100L of brine into the adsorption tank, wherein the temperature of the brine is 15 ℃, starting a stirrer 11 of the adsorption tank, and keeping the stirring speed at 80r/min; adjusting the pH of the brine by using 30wt% of sodium hydroxide solution, and adjusting the pH of the brine to 9.0-9.5 by adopting a pH on-line detector for real-time test to obtain the alkaline lithium-containing brine.

(2) 300g of powdery titanium ion sieve adsorbent (structural formula H) is metered ₂ TiO ₃ ) Adding the powder into alkaline lithium-containing brine, keeping the stirring speed at 80r/min, and continuously stirring for 20min to uniformly disperse the powdery titanium ion sieve adsorbent into the alkaline lithium-containing brine to form a first circulating liquid; the circulation pump 20 is turned on to maintain vacuumThe device is in a closed state, the stirring speed is reduced to 50r/min, the cyclic dynamic adsorption is started, and the adsorption time is 2h; testing Li in the first circulating liquid after adsorption ⁺ The adsorption capacity of the powdery titanium ion sieve adsorbent is calculated to be 30.3mg/g according to the mass percentage concentration.

Starting a vacuum device, and carrying out first solid-liquid membrane separation by negative pressure suction, wherein the suction pressure is-0.6 MPa, the membrane passing temperature is 35 ℃, and the membrane surface flow rate is 2m/s; discharging the lithium-removed brine through a permeation side, and intercepting to obtain the lithium-containing adsorbent I.

The powdery titanium ion sieve adsorbent in the embodiment has uniform and fine appearance, and the particle size of the adsorbent is 250-450 nm.

(3) Closing the vacuum device, metering and adding 20L of pure water to form a second circulating liquid, and starting to circularly and dynamically wash for 15min; and starting a vacuum device, performing second solid-liquid membrane separation, wherein the suction pressure is-0.5 MPa, the membrane passing temperature is 35 ℃, the membrane surface flow rate is 1.5m/s, performing suction filtration to obtain flushing wastewater, and intercepting to obtain a lithium-containing adsorbent II.

(4) Closing the vacuum device, and metering and adding 20L of 3wt% hydrochloric acid solution to form a third circulating liquid, wherein the temperature of the third circulating liquid is 20 ℃, and the circulating dynamic desorption is started for 2 hours; and after the desorption is finished, starting a vacuum device to perform third solid-liquid membrane separation, wherein the suction pressure is-0.7 MPa, the membrane passing temperature is less than 50 ℃, and the membrane surface flow rate is 2m/s. The lithium-rich liquid is pumped out from the permeation side of the membrane separation device, and Li in the lithium-rich liquid is tested ⁺ The mass percentage concentration is reduced to 93.5 percent of desorption rate of the powdery titanium ion sieve adsorbent, and the obtained lithium-rich liquid is supplied to the subsequent lithium ion purification and lithium product preparation processes; the obtained regenerated powdery titanium ion sieve adsorbent is continuously and repeatedly used for extracting lithium from subsequent lithium-containing brine.

Comparative example 1

The comparative example 1 differs from example 1 in that: although the titanium ion sieve type adsorbent belongs to the same titanium ion sieve type adsorbent, the adsorbent is granular, the particle size is 1-3 mm, and the adsorption performance and the effect of the adsorbent are different. The method comprises the following specific steps:

(1) Injecting 100L of brine into the adsorption tank, wherein the temperature of the brine is 18 ℃, starting a stirrer 11 of the adsorption tank, and keeping the stirring speed at 80r/min; adjusting the pH of the brine by using 30wt% of sodium hydroxide solution, and adjusting the pH of the brine to 9.0-9.5 by adopting a pH on-line detector for real-time test to obtain the alkaline lithium-containing brine.

(2) Stopping stirring, and adding 715g of granular titanium ion sieve lithium adsorbent (active ingredient is 42wt%, and the active ingredient is of the ionic sieve structural formula H) into the alkaline lithium-containing brine ₂ TiO ₃ ) Standing for adsorption for 18h; testing of Li in adsorbed lithium-containing brines ⁺ And calculating to obtain the adsorption capacity of the granular lithium titanium ion sieve adsorbent of 9.7mg/g (test data of the granular lithium titanium ion sieve adsorbent with 42wt% of effective component).

And opening a drainage valve, intercepting by a 80-mesh filter screen arranged at a water outlet in the tank to obtain a lithium-containing adsorbent I, and filtering and discharging the lithium-removing brine.

In this example, a granular titanium ion sieve adsorbent was used, the particle size of which was 1 to 3mm, and the content of the titanium ion sieve adsorbent in the granular material was 42wt%.

(3) Adding 40L of pure water into the lithium-containing adsorbent I in a metering manner, soaking and washing for 20min, opening a drainage valve, and filtering washing water by using an 80-mesh filter screen arranged at a water outlet in the tank; and then 20L of pure water is metered and added, the mixture is soaked and washed for 10min again, the lithium-containing adsorbent II is obtained by interception through a 80-mesh filter screen arranged at a water outlet in the tank, and the filtered washing wastewater is discharged.

(4) Adding 60L of 3wt% hydrochloric acid solution into the lithium-containing adsorbent II, soaking and desorbing for 12h; after the desorption is finished, a drainage valve is opened, a 80-mesh filter screen arranged at a water outlet in the tank is used for intercepting to obtain a regenerated granular titanium ion sieve adsorbent, lithium-rich liquid is obtained by filtration, and Li in the lithium-rich liquid is tested ⁺ The mass percentage concentration is converted into the desorption rate of 72.5 percent of the granular titanium ion sieve adsorbent; the obtained lithium-rich liquid is used in the subsequent lithium product purification and preparation processes; the obtained regenerated granular titanium ion sieve adsorbent is continuously and repeatedly used for extracting lithium from subsequent lithium-containing brine.

Compared with a powdery titanium ion sieve adsorbent, the granular titanium ion sieve adsorbent is used for extracting lithium ions, although the lithium extraction process is simpler, the problems of complicated granulation process, large addition amount of the adsorbent, long time consumption in the adsorption, washing and desorption processes, large consumption of washing pure water and desorption liquid (3 wt% hydrochloric acid solution) and the like exist, meanwhile, the adsorption capacity of the adsorbent particles is 23.1mg/g under the condition that the effective components are 100% by converting the content of the adsorbent particles into 42wt%, compared with the adsorption capacity of the powdery titanium ion sieve adsorbent which is not subjected to granulation treatment in example 1, the adsorption capacity of the granulated titanium ion sieve adsorbent is reduced by 23.76%, in a static desorption process, the desorption rate is also low, and the lithium extraction efficiency and the lithium ion yield in the whole process are not superior.

Example 2

The difference compared to example 1 is that: different powdered lithium adsorbents are selected, and the adsorption, flushing and desorption process control is also different. The method comprises the following specific steps:

(1) Injecting 100L of brine into the adsorption tank, wherein the brine temperature is 15 ℃, starting a stirrer 11 of the adsorption tank, and keeping the stirring speed at 80r/min; adjusting the pH of the brine by using a 30wt% sodium hydroxide solution, and adjusting the pH of the brine to 7.5-8.0 by adopting a pH online detector for real-time test to obtain alkaline lithium-containing brine;

(2) 450g of powdery aluminum salt adsorbent [ the structural general formula of which is LiX.2Al (OH) ]is metered ₃ ·nH ₂ O]Adding the mixture into the alkaline lithium-containing brine, and keeping the stirring speed of 80r/min to continue stirring for 20min so that the adsorbent is uniformly dispersed in the alkaline lithium-containing brine; forming a first circulating liquid; starting the circulating pump 20, keeping the vacuum device in a closed state, reducing the stirring speed to 50r/min, and starting circulating dynamic adsorption for 2h; testing Li in the first circulating liquid after adsorption ⁺ The adsorption capacity of the powdery aluminum salt adsorbent is calculated to be 10.5mg/g according to the mass percentage concentration.

The powdered aluminum salt adsorbent in this example is a uniform powder, and the particle size of the adsorbent is 250 to 550nm.

(3) Closing the vacuum device, metering and adding 10L of pure water to form a second circulating liquid, and starting to circularly and dynamically wash for 5min; and starting a vacuum device, performing second solid-liquid membrane separation, wherein the suction pressure is-0.5 MPa, the membrane passing temperature is 25 ℃, the membrane surface flow rate is 1.5m/s, performing suction filtration to obtain washing wastewater, and intercepting to obtain a lithium-containing adsorbent II.

(4) Closing the vacuum device, metering and injecting 20L of pure water to form a third circulating liquid, wherein the temperature of the formed third circulating liquid is 20 ℃, and starting to perform cyclic dynamic desorption for 2h; and after the desorption is finished, starting a vacuum device to perform third solid-liquid membrane separation, wherein the suction pressure is-0.6 MPa, the membrane passing temperature is less than 50 ℃, and the membrane surface flow velocity is 2m/s. The lithium-rich liquid is pumped out from the permeation side of the membrane separation device, and Li in the lithium-rich liquid is tested ⁺ The mass percentage concentration is reduced to 93.8 percent of desorption rate of the powdery aluminum salt adsorbent, and the obtained lithium-rich liquid is supplied to subsequent lithium product purification and preparation processes; the obtained regenerated powder aluminum salt adsorbent is continuously and repeatedly used for extracting lithium from subsequent lithium-containing brine.

Under the same process, the adsorption capacity of the powdery aluminum salt adsorbent is smaller, but the preparation process is simple, the energy consumption is less, pure water is used for desorption in the desorption process, the cost is lower, the pollution is less, and the method has a certain application space.

Example 3

The difference compared to example 1 is that: although the manganese ion sieve adsorbent belongs to the ion sieve type adsorbent, the manganese ion sieve adsorbent is selected in powder form, and the manganese ion sieve adsorbent are different in structure and composition, and different in adsorption performance and effect. The method comprises the following specific steps:

(2) 300g of powdery manganese ion sieve adsorbent (structural formula HMn) ₂ O ₄ ) Adding into alkaline lithium-containing brine, and stirring at 80r/min for 20min to uniformly disperse the powdery manganese ion sieve adsorbent in the alkaline lithium-containing brineBrine; forming a first circulating liquid; starting the circulating pump 20, keeping the vacuum device in a closed state, reducing the stirring speed to 50r/min, and starting circulating dynamic adsorption for 2h; testing Li in the first circulating liquid after adsorption ⁺ The adsorption capacity of the powdery manganese ion sieve adsorbent is 34.7mg/g by calculation according to the mass percentage concentration.

Starting a vacuum device, and carrying out first solid-liquid membrane separation by negative pressure suction, wherein the suction pressure is-0.6 MPa, the membrane passing temperature is 37 ℃, and the membrane surface flow rate is 2m/s; discharging the lithium-removing brine through the permeation side, and intercepting to obtain the lithium-containing adsorbent I.

The particle size of the powdery manganese ion sieve adsorbent in the embodiment is 200-500 nm.

(4) Closing the vacuum device, metering and adding 20L of 3wt% hydrochloric acid solution to form a third circulating liquid, wherein the temperature of the third circulating liquid is 21 ℃, starting circulating dynamic desorption, and the desorption time is 2h; and after the desorption is finished, starting a vacuum device to perform third solid-liquid membrane separation, wherein the suction pressure is-0.7 MPa, the membrane passing temperature is less than 50 ℃, and the membrane surface flow velocity is 2m/s. The lithium-rich liquid is pumped out from the permeation side of the membrane separation device, and Li in the lithium-rich liquid is tested ⁺ The mass percentage concentration is reduced to obtain that the desorption rate of the powdery manganese ion sieve adsorbent is 94.7 percent; the obtained lithium-rich liquid is supplied to subsequent lithium product purification and preparation processes for use; the obtained regenerated powdery manganese ion sieve adsorbent is continuously and repeatedly used for extracting lithium from subsequent lithium-containing brine.

The powdery manganese ion sieve adsorbent adopts the lithium extraction process, so that a good lithium extraction effect is achieved, the adsorption capacity and the desorption rate are high, the time consumption of the whole lithium extraction process is short, and the economical efficiency is good.

Example 4

The differences compared to example 3 are: the same powdered manganese ion sieve adsorbent is adopted, but the adsorbent is adjustedFor Li-containing brine ⁺ Adsorption and desorption times of (a). The method comprises the following specific steps:

(1) Injecting 100L of brine into the adsorption tank, wherein the temperature of the brine is 16 ℃, starting a stirrer 11 of the adsorption tank, and keeping the stirring speed at 80r/min; adjusting the pH of the brine by using 30wt% of sodium hydroxide solution, and adjusting the pH of the brine to 9.0-9.5 by adopting a pH on-line detector for real-time test to obtain the alkaline lithium-containing brine.

(2) 300g of powdery manganese ion sieve adsorbent (structure HMn) is respectively metered ₂ O ₄ ) Adding into alkaline lithium-containing brine, and keeping the stirring speed of 80r/min to continue stirring for 20min, so that the powdery manganese ion sieve adsorbent is uniformly dispersed in the alkaline lithium-containing brine; forming a first circulating liquid; starting a circulating pump 20, keeping the vacuum device in a closed state, reducing the stirring speed to 50r/min, and starting circulating dynamic adsorption for 1h, 3h and 4h respectively; testing Li in the first circulating liquid after adsorption ⁺ And calculating the adsorption capacity of the powdery manganese ion sieve adsorbent according to the mass percentage concentration.

Starting a vacuum device, and performing negative pressure suction to perform first solid-liquid membrane separation, wherein the suction pressure is-0.6 MPa, the membrane passing temperature is 35 ℃, and the membrane surface flow velocity is 2m/s; discharging the lithium-removed brine through a permeation side, and intercepting to obtain a lithium-containing adsorbent I;

(3) Closing the vacuum device, metering and adding 20L of pure water to form a second circulating liquid, and starting to circularly and dynamically wash for 15min; starting a vacuum device, carrying out second solid-liquid membrane separation, wherein the suction pressure is-0.5 MPa, the membrane passing temperature is 32 ℃, the membrane surface flow rate is 1.5m/s, carrying out suction filtration on the flushing wastewater, and intercepting to obtain a lithium-containing adsorbent II;

(4) Closing the vacuum device, and metering and adding 20L of 3wt% hydrochloric acid solution to form a third circulating liquid, wherein the temperature of the third circulating liquid is 20 ℃, and the circulating dynamic desorption is started, and the desorption time is respectively 1h, 2h and 3h; and after the desorption is finished, starting a vacuum device to perform third solid-liquid membrane separation, wherein the suction pressure is-0.7 MPa, the membrane passing temperature is less than 50 ℃, and the membrane surface flow velocity is 2m/s. The lithium-rich liquid is pumped out from the permeation side of the membrane separation device and is measuredLi in Li-rich test solution ⁺ Converting the mass percentage concentration into the desorption rate of the powdery manganese ion sieve adsorbent; the obtained lithium-rich liquid is supplied to subsequent lithium product purification and preparation processes for use; the obtained regenerated powdery manganese ion sieve adsorbent is continuously and repeatedly used for extracting lithium from subsequent lithium-containing brine. The adjusted test results are shown in Table 2.

TABLE 2

By combining the relevant test data of the adsorption time 2h and the desorption time 2h in the example 3, in the example, when the adsorption time of the powdery manganese ion sieve adsorbent is 1h, the adsorption capacity value is smaller and is only 27.7mg/g, it can be seen that the adsorption time is relatively short, the powdery manganese ion sieve adsorbent cannot be sufficiently adsorbed, and when the adsorption time is prolonged to 3h and 4h, the adsorption capacity is greatly improved, but the improvement rate of the adsorption capacity between the two is not large, which indicates that the lithium adsorbent is close to saturated adsorption, and the influence of the time prolongation on the adsorption capacity is not large, so that the adsorption time is preferably 2-3 h, and the cost is optimal; on the other hand, the desorption rate of lithium ions in the adsorbent is increased along with the increase of the desorption time, and when the desorption time is prolonged to 2 hours and 3 hours, the desorption rate reaches a higher level, and the desorption time is preferably 2 to 3 hours in consideration of the operation cost and the lithium extraction efficiency.

Example 5

The differences compared to example 3 are: the same powdery manganese ion sieve adsorbent is adopted, but the types and concentration parameters of desorption liquid in the lithium extraction process are adjusted. The method comprises the following specific steps:

(1) Injecting 100L of brine into the adsorption tank, wherein the temperature of the brine is 17 ℃, starting a stirrer 11 of the adsorption tank, and keeping the stirring speed at 80r/min; adjusting the pH of the brine by using 30wt% of sodium hydroxide solution, and adjusting the pH of the brine to 9.0-9.5 by adopting a pH on-line detector for real-time test to obtain the alkaline lithium-containing brine.

(2) 300g of powdery manganese ion sieve adsorbent (structural formula HMn) ₂ O ₄ ) Adding into alkaline lithium-containing brine, and maintaining the stirring speed at 80r/minContinuously stirring for 20min to uniformly disperse the powdery manganese ion sieve adsorbent in the alkaline lithium-containing brine; forming a first circulating liquid; starting the circulating pump 20, keeping the vacuum device in a closed state, reducing the stirring speed to 50r/min, and starting circulating dynamic adsorption for 2h; testing Li in the first circulating liquid after adsorption ⁺ The adsorption capacity of the powdery manganese ion sieve adsorbent is calculated to be 35.8mg/g according to the mass percentage concentration.

Starting a vacuum device, and carrying out first solid-liquid membrane separation by negative pressure suction, wherein the suction pressure is-0.6 MPa, the membrane passing temperature is 35 ℃, and the membrane surface flow rate is 2m/s; discharging the lithium-removing brine through the permeation side, and intercepting to obtain the lithium-containing adsorbent I.

(3) Closing the vacuum device, metering and adding 20L of pure water to form a second circulating liquid, and starting to circularly and dynamically wash for 15min; and starting a vacuum device, performing second solid-liquid membrane separation, wherein the suction pressure is-0.5 MPa, the membrane passing temperature is 25 ℃, the membrane surface flow rate is 1.5m/s, performing suction filtration to obtain flushing wastewater, and intercepting to obtain a lithium adsorbent II.

(4) Closing the vacuum device, and metering 20L of desorption liquid with different types and different concentrations (the type and the concentration of the desorption liquid are shown in table 3) to form third circulating liquid, wherein the temperature of the third circulating liquid is 20 ℃, the circulating dynamic desorption is started, and the desorption time is 2h; and after the desorption is finished, starting a vacuum device to perform third solid-liquid membrane separation, wherein the suction pressure is-0.7 MPa, the membrane passing temperature is less than 50 ℃, and the membrane surface flow rate is 2m/s. The lithium-rich liquid is pumped out from the permeation side of the membrane separation device, and Li in the lithium-rich liquid is tested ⁺ Converting the mass percent concentration into the desorption rate of the powdery manganese ion sieve adsorbent; the obtained lithium-rich liquid is supplied to subsequent lithium product purification and preparation processes for use; the obtained regenerated powdery manganese ion sieve adsorbent is continuously and repeatedly used for extracting lithium from subsequent lithium-containing brine.

The results of the influence of different desorption liquid types and concentrations on the desorption rate of the lithium adsorbent II are shown in Table 3.

TABLE 3

As can be seen from the data in Table 3, the desorption effect of the nitric acid solution is the worst, and the data change is large; the desorption effect of the sulfuric acid solution is not as good as that of the hydrochloric acid solution; the hydrochloric acid solution has high desorption rate effect of lithium ions under the concentration of 1wt%, 2wt% and 3wt%, and can be comprehensively selected in combination with other factors in practical application.

Claims

1. A lithium extraction process for coupling a powdery lithium adsorbent with a hollow fiber membrane is characterized by comprising the following steps:

(1) In an adsorption tank, adjusting the pH value of lithium-containing brine by using an alkaline solution to obtain alkaline lithium-containing brine;

(4) Carrying out cyclic dynamic desorption on the lithium-containing adsorbent II by using desorption liquid to obtain a desorbed solid-liquid mixture, and carrying out third solid-liquid membrane separation on the desorbed solid-liquid mixture to obtain a regenerated powdery lithium adsorbent and a lithium-rich liquid;

in the step (2), the step of cyclic dynamic adsorption is to add the powdery lithium adsorbent into the alkaline lithium-containing brine, stir the mixture evenly to form a first circulating liquid, so that the first circulating liquid flows in a first cycle between the adsorption tank and the membrane separation device, and the powdery lithium adsorbent dynamically adsorbs lithium ions; after the dynamic adsorption is finished, an adsorption solid-liquid mixture is formed, and the adsorption solid-liquid mixture is subjected to first solid-liquid membrane separation by using the membrane separation device to obtain a lithium-containing adsorbent I and lithium-removing brine;

in the step (3), the step of circularly and dynamically washing is to add pure water into the lithium-containing adsorbent I to form second circulating liquid, then to make the second circulating liquid perform second circulating flow between the membrane separation device and the first circulating tank to dynamically wash the lithium-containing adsorbent I, to form a washing solid-liquid mixture after the dynamic washing is completed, to perform second solid-liquid membrane separation on the washing solid-liquid mixture by using the membrane separation device, to obtain a lithium-containing adsorbent II and washing wastewater;

in the step (4), in the cyclic dynamic desorption, desorption liquid is added into a lithium-containing adsorbent II to form third circulation liquid, then the third circulation liquid is subjected to third circulation flow between a membrane separation device and a second circulation tank, dynamic desorption is carried out on the lithium-containing adsorbent II, a desorption solid-liquid mixture is formed after the dynamic desorption is completed, and the membrane separation device is used for carrying out third solid-liquid membrane separation on the desorption solid-liquid mixture to obtain a regenerated powder lithium adsorbent and a lithium-rich liquid;

the same membrane separation device is adopted to carry out first solid-liquid membrane separation, second solid-liquid membrane separation and third solid-liquid membrane separation, and the membrane separation device is a hollow fiber membrane separation device; when the cyclic dynamic adsorption, the cyclic dynamic flushing and the cyclic dynamic desorption are carried out, the first circulating liquid during the cyclic dynamic adsorption, the second circulating liquid during the cyclic dynamic flushing and the third circulating liquid during the cyclic dynamic desorption are all carried out by the membrane separation device.

2. The lithium extraction process of claim 1,

the powdery lithium adsorbent is one or a mixture of more of an ion sieve type adsorbent, an aluminum salt adsorbent, a modified mineral adsorbent, a macrocyclic compound type adsorbent and a hydroxide adsorbent, and the particle size of the powdery lithium adsorbent is 200-600nm.

3. The lithium extraction process of claim 1,

in the step (1), the lithium-containing brine is salt lake brine or underground brine; mg in lithium-containing brine ²⁺ With Li ⁺ The mass ratio of (1); li in lithium-containing brine ⁺ The mass percentage concentration is0.002~2%。

4. The lithium extraction process of claim 1,

the adding amount of the powdery lithium adsorbent in the alkaline lithium-containing brine is 0.5-8g/L, the powdery lithium adsorbent is added into the alkaline lithium-containing brine, and then first stirring is carried out for 10-30min to form a first circulating liquid, wherein the stirring speed of the first stirring is 60-120r/min.

5. The lithium extraction process of claim 1,

when the cyclic dynamic adsorption is carried out, the temperature of the first cyclic liquid is minus 5 to 45 ℃, and the cyclic dynamic adsorption time is 1 to 4 hours;

and during the cyclic dynamic adsorption, keeping the first cyclic liquid in the adsorption tank to be subjected to second stirring, wherein the stirring speed of the second stirring is 30-80r/min.

6. The lithium extraction process of claim 1,

when the first solid-liquid membrane separation is carried out, negative pressure suction is adopted, the suction pressure is-0.4 to-0.8 MPa, the membrane passing temperature is 0 to 80 ℃, and the membrane surface flow rate is 1 to 3m/s.

7. The lithium extraction process of claim 1,

when dynamic washing is carried out, the temperature of the second circulating liquid is 5 to 60 ℃, and the washing time is 5 to 20min;

and when the second solid-liquid membrane separation is carried out, negative pressure suction is adopted, the suction pressure is minus 0.4 to minus 0.8MPa, and the membrane passing temperature is 5 to 70 ℃.

8. The lithium extraction process of claim 1,

when dynamic desorption is carried out, the temperature of the third circulating liquid is 5 to 60 ℃, and the desorption time is 1 to 3 hours;

and when the third solid-liquid membrane separation is carried out, negative pressure suction is adopted, the suction pressure is-0.4 to-0.8 MPa, and the membrane passing temperature is 5 to 70 ℃.