Process system for extracting lithium from salt lake brine through continuous ion exchange adsorption

Abstract

The invention relates to the technical field of continuous ion exchange adsorption lithium extraction processes, and discloses a process system for continuous ion exchange adsorption lithium extraction from salt lake brine, which comprises a pretreatment unit, an ion exchange adsorption unit, a desorption unit and a lithium ion enrichment and purification unit. The method comprises the following steps: removing suspended matters and impurities in brine through pretreatment, continuously adsorbing lithium ions in the brine by using ion exchange resin with high selectivity and adsorption capacity, efficiently desorbing the lithium ions by using a desorption agent, and finally obtaining a high-purity lithium product through the steps of enrichment and purification. The process system improves the extraction efficiency of lithium ions and the product purity, reduces the production cost and the environmental influence, realizes automatic control, has good stability and adaptability, is suitable for various salt lake brine resources, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of continuous ion exchange adsorption lithium extraction technology, in particular to a continuous ion exchange adsorption lithium extraction technology system from salt lake brine. Background Art

[0002] Traditional lithium extraction processes from salt lake brine mainly include salt field concentration precipitation, solvent extraction, calcination leaching, etc. These methods have the following disadvantages: Salt field concentration precipitation method: The lithium extraction cycle is long and may take months or even years if it relies on natural evaporation. It occupies a large area and depends on natural climate influences, resulting in low lithium extraction efficiency. Solvent extraction method: The chemical reagents require large dosages and are easily degraded. Long-term use reduces the extraction efficiency and requires frequent replacement. The investment cost is high and it is only suitable for brines with a low magnesium-lithium ratio, which limits its applicability. Calcination leaching method: The calcination temperature needs to be above 1000℃, the fuel cost is high, and it emits waste gases such as CO2 and SO2, which puts great pressure on environmental protection; To overcome these challenges, researchers have developed a variety of new lithium extraction technologies, including ion exchange adsorption, membrane separation, and electrochemical extraction. Ion exchange adsorption has garnered widespread attention due to its high efficiency, environmental friendliness, and operability. This method leverages the selective adsorption capacity of ion exchange resins for lithium ions to rapidly extract them from brine.

[0003] However, the existing ion exchange adsorption lithium extraction process has limited adsorption capacity of ion exchange resins and low desorption efficiency; therefore, developing an efficient and continuous ion exchange adsorption lithium extraction process system to achieve efficient extraction and high-purity enrichment of lithium ions is an urgent problem to be solved in the current lithium resource extraction field. Summary of the Invention

[0004] (1) Technical problems solved In view of the shortcomings of the existing technology, the present invention provides a continuous ion exchange adsorption process system for extracting lithium from salt lake brine, which solves the problems raised in the above background technology.

[0005] (2) Technical solution To achieve the above objectives, the present invention provides the following technical solutions: a continuous ion exchange adsorption process system for extracting lithium from salt lake brine, the system comprising a pretreatment unit, an ion exchange adsorption unit, an elution regeneration unit, and a lithium ion enrichment and purification unit: The pretreatment unit is used to pretreat the salt lake brine to remove suspended matter and sediment impurities so that the brine meets the requirements of subsequent treatment; The ion exchange adsorption unit: The pretreated brine is fed into the ion exchange adsorption device, and the lithium ions in the brine are adsorbed by the ion exchange resin. The basic principle of the ion exchange adsorption process is: R-H+Li+⇌R-Li+H+, where RH represents the hydrogen form of the ion exchange resin, R-Li represents the lithium form of the ion exchange resin, Li+ represents lithium ions, and H+ represents hydrogen ions; The elution and regeneration unit is used to elute and regenerate the adsorption saturated ion exchange resin to recover lithium ions. The basic principle of the elution and regeneration process is as follows: R-Li+HCl→R-H+LiCl, where R-Li represents the lithium form of the ion exchange resin, HCl represents hydrochloric acid, RH represents the hydrogen form of the ion exchange resin, and LiCl represents lithium chloride; The lithium ion enrichment and purification unit: enriches and purifies the eluate to obtain a high-purity lithium product. The basic principle of the lithium ion enrichment and purification process is: Li++Cl-→LiCl(s) wherein Li+ represents lithium ion, Cl- represents chloride ion, and LiCl(s) represents solid lithium chloride.

[0006] Preferably, the pre-processing unit comprises the following steps: S1. Remove suspended matter, sediment, colloid and other solid impurities in brine by flocculation and filtration to prevent clogging of adsorbent gaps; S2. Adjust the pH value of the brine to make it reach the optimal working pH range for the adsorbent, while reducing the interference of competing ions (such as Mg2+, Ca2+); S3. Remove the influence of multivalent interfering ions. According to the characteristics of brine in different salt lakes, chemical precipitation, ion exchange and solvent extraction methods can be used to remove the common Mg2+, Ca2+ and Fe3+ in salt lake brine to prevent them from competing with Li+ for adsorption sites. S4. For salt lake brines with different lithium contents, the Li+ concentration can be adjusted by concentration and dilution to match the optimal working concentration of the corresponding adsorbent.

[0007] Preferably, the ion exchange adsorption unit uses the following ion exchange resin: Step 1: using an inorganic lithium ion sieve adsorbent (mainly including manganese lithium ion sieve, titanium lithium ion sieve, aluminum adsorbent) or an organic ion exchange resin (mainly including weak acid cation exchange resin, lithium selective chelating resin); Step 2: Usually 4-6 ion exchange columns are set up to run in series. The pretreated salt lake brine is fed into the ion exchange column in the adsorption area at a constant feed flow rate through a feed pump. The lithium ions in the brine replace the original hydrogen ions by occupying the adsorption sites on the adsorbent, thereby completing the adsorption process.

[0008] Preferably, the elution regeneration unit adopts the following method: Step 1: Depending on the type of adsorbent selected, a low-concentration strong acid or pure water can be selected as the eluent; Step 2: Usually, 2-3 ion exchange columns are set up to run in series. The prepared eluent is uniformly fed into the ion exchange column in the desorption zone through a desorption pump at a certain flow rate. The ion exchange resin that has been saturated with adsorption is fully countercurrently contacted to replace the lithium ions embedded in the adsorption sites to achieve the lithium ion elution process; Step 3: Usually 1-2 ion exchange columns are set up in series to operate as a regeneration unit, which is used for water washing after pickling to remove residual acid and remaining impurity ions (such as Mg2+, Ca2+) after pickling to make the effluent pH ≈ 7, so that it can re-enter the adsorption unit for adsorption operation after regeneration and realize recycling.

[0009] Preferably, the lithium ion enrichment and purification unit adopts the following method: S11. Pre-treat the eluate by filtering to remove suspended matter or adsorbent debris, and add acid or alkali to adjust the pH of the eluate to neutral to prevent subsequent equipment corrosion; S12, concentrating the eluate using evaporation concentration or membrane separation technology; S13, remove impurity ions by chemical precipitation (adding Na2CO3 or Na3PO4 to remove calcium and magnesium); S14. High-purity lithium products are obtained through fine purification through solvent extraction and membrane separation technology.

[0010] Preferably, the entire system is automatically controlled, adopting a process mode of multiple columns in series with three functional zones of adsorption, elution and regeneration, which are uniformly controlled by a distribution valve. After each step cycle, the distribution valve drives the exchange column to rotate in the opposite direction, that is, the movement direction of the ion exchange column is opposite to the direction of material flow, so as to realize the reverse rotation of the ion exchange column in each functional zone and the switching between functional zones; The pretreated salt lake brine is passed into the adsorption zone for adsorption, and the saturated adsorption columns are transferred to the elution zone in turn by rotating the rotary valve. The eluent quickly washes the ion exchange column to replace the lithium-containing material and remove impurity ions. After desorption, the eluent enriches lithium and flows out of the system as qualified liquid. The eluted ion exchange column is transferred to the regeneration zone for water washing to remove residual acid and remaining impurity ions. When the pH of the effluent is ≈ 7, the regeneration is considered complete. The ion exchange column after regeneration re-enters the adsorption zone for adsorption operation, so that the multi-column system forms a complete loop. The adsorption-elution-regeneration functional areas are spatially separated but the process is continuous, so as to realize the recycling of ion exchange columns and improve production efficiency and stability. This system is suitable for various salt lake brine resources and has a high lithium ion extraction rate and purity.

[0011] Preferably, the pretreatment unit includes a raw brine storage tank, an evaporation tank, a mixing tank, a flocculant addition system, a stirring device, a sedimentation tank, a filter tank, a softening device, a regulating tank, a pumping system, a flow control device and an online monitoring instrument; The raw brine storage tank is used to store raw brine collected from the salt lake to provide a stable supply of raw materials for the pretreatment process; The evaporation pool is used to evaporate and concentrate the brine to precipitate impurity salt ions, while increasing the lithium ion concentration in the brine; The mixing tank is used to dilute the brine to reduce the concentration of impurity ions or adjust the viscosity to prevent the impurity ion concentration or viscosity from being too high and affecting the effect of subsequent ion exchange work; The flocculant addition system is used to add flocculants to the brine to promote the flocculation of suspended matter and sediment; The stirring device is used to stir the brine in the mixing tank to ensure that the flocculant and the brine are fully mixed and the flocculation effect is improved; The sedimentation tank allows the flocs in the flocculated brine to settle under the action of gravity to separate the flocs from the brine; The filter tank further removes fine suspended matter and flocs in the brine, thereby improving the clarity of the brine; The softening device is used to remove calcium and magnesium ions from the brine to prevent these ions from reacting with the ion exchange resin in subsequent processes; The regulating tank is used to adjust the pH value and temperature parameters of the brine to meet the operating requirements of the ion exchange adsorption unit; The pumping system pumps the pretreated brine to the ion exchange adsorption unit; The flow control device is used to accurately control the flow of brine to ensure material balance between the pretreatment unit and the subsequent units; The online monitoring instrument is used to monitor the quality parameters of the brine in real time to ensure that the pretreatment effect meets the specified standards.

[0012] Preferably, the ion exchange adsorption unit includes an ion exchange resin packed tower, a feed pump, a flow control valve, a distributor at the top of the resin tower, a collector at the bottom of the resin tower, a backwash pump, a backwash liquid storage tank, a regeneration liquid supply system, a regeneration pump, a control system, an online analyzer and a temperature control system; The ion exchange resin packed tower is filled with ion exchange resin for adsorbing lithium ions in the brine. The resin is generally selected based on its selectivity for lithium ions. The feed pump is used to feed the pretreated brine into the ion exchange resin tower at a certain flow rate; The flow control valve adjusts the feed flow rate of the brine to ensure that the adsorption process is carried out under optimal conditions; The distributor at the top of the resin tower ensures that the brine is evenly distributed to the resin layer, thereby improving the ion exchange efficiency; The collector at the bottom of the resin tower is used to collect the brine after being adsorbed by the resin layer and guide it to the next processing unit; The backwash pump is used to reversely flush the resin after the resin is saturated with adsorption, so as to remove impurities and saturated lithium ions in the resin layer; The backwash liquid storage tank is used to store the solution used for backwashing the resin; The regeneration liquid supply system provides a solution for resin regeneration; The regeneration pump is used to deliver the regeneration liquid into the resin tower at a uniform speed to restore the adsorption capacity of the resin; The control system monitors and adjusts the operating parameters of the ion exchange adsorption unit; The online analytical instrument is used to monitor the lithium ion concentration in the brine, as well as the liquid flow and composition in and out of the resin tower in real time; The temperature control system is used to maintain the temperature in the resin tower within a suitable range to improve the ion exchange efficiency.

[0013] Preferably, the lithium ion enrichment and purification unit includes a desorption tower, a desorbent supply system, a desorbent heater, a desorption pump, a desorption liquid collector, a filter tank, a regulating tank, an evaporator, a condenser, a concentrate storage tank, a chemical precipitation tank, an ion exchange membrane, a purification tower, a product collection system, a control system, an online analytical instrument and a waste liquid treatment system; The desorption tower is used to load the resin that has adsorbed lithium ions and elute the lithium ions from the resin through a desorbent; The desorbent supply system is used to provide desorbent, usually by pumping the solution in the desorbent storage tank to the desorption tower; The desorbent heater is used to increase the temperature of the desorbent to enhance the desorption effect and improve the elution efficiency of lithium ions; The desorption pump is used to deliver the desorbent into the desorption tower at a certain flow rate to ensure that the desorption process is carried out evenly; The desorption liquid collector is used to collect the desorption liquid containing lithium ions flowing out of the desorption tower; The filter tank is used to filter the desorption liquid to remove suspended matter and adsorbent debris therein; The regulating tank is used to add acid and alkali to adjust the pH value of the desorption liquid to prevent subsequent equipment corrosion; The evaporator evaporates the water in the desorption liquid by heating, thereby concentrating the lithium ions to obtain a lithium ion-rich solution; The condenser condenses the water vapor evaporated in the evaporator into water for recycling and discharge; The concentrated liquid storage tank is used to store the lithium ion concentrated liquid obtained from the evaporator; The chemical precipitation tank is used to add chemical agents to the concentrated liquid to precipitate and remove calcium and magnesium ions therein; The ion exchange membrane is used to further purify the lithium ion concentrate by removing other ions through the selective permeability of the ion exchange membrane, thereby improving the purity of the lithium ions; The purification tower is used for lithium products with higher purity, and the purification tower can be used for secondary ion exchange or adsorption to remove residual impurity ions; The product collection system is used to collect the enriched and purified lithium ion solution, which can be further processed to prepare a lithium salt product; The control system is used to monitor and adjust the operating parameters during desorption, evaporation, condensation and purification to ensure process stability and product quality; The online analytical instrument monitors the lithium ion concentration and other key parameters in real time to optimize the process; The waste liquid treatment system is used to treat the waste liquid generated during the desorption and purification process to ensure compliance with environmental protection requirements.

[0014] (3) Beneficial effects Compared with the existing technology, the present invention provides a continuous ion exchange adsorption process system for extracting lithium from salt lake brine, which has the following beneficial effects: 1. Improve lithium extraction efficiency: Through the continuous ion exchange adsorption process, the lithium ion extraction cycle is significantly shortened, and production efficiency is improved. Compared with the traditional evaporation pool method, the lithium extraction speed is greatly increased.

[0015] 2. Reduce production costs: By optimizing the process flow and realizing automated control, manual operation and energy consumption are reduced, thereby reducing overall production costs.

[0016] 3. Reduce environmental impact: The process system of the present invention reduces the evaporation of brine and the risk of soil salinization. At the same time, it treats the discharged wastewater and reduces pollution to the environment.

[0017] 4. Improve product purity: Through ion exchange adsorption and delicate desorption steps, high-purity lithium products can be obtained, which reduces the complexity of subsequent chemical treatment and improves the market competitiveness of the product.

[0018] 5. Good system stability: The process system of the present invention adopts a modular design, which is easy to maintain and upgrade, and the system runs stably with a low failure rate.

[0019] 6. Strong adaptability: The process system of the present invention is suitable for salt lake brine of different concentrations and components, has strong adaptability, and can be used in salt lake brine of different regions and different types.

[0020] 7. Save water resources: Through the efficient ion exchange adsorption and desorption process, the water usage is reduced, which has important economic and social significance for areas with water scarcity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the overall system architecture of the present invention; Figure 2 This is an experimental data diagram of the present invention. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] This is a continuous ion exchange adsorption process system for extracting lithium from salt lake brine. The system includes a pretreatment unit, an ion exchange adsorption unit, an elution regeneration unit, and a lithium ion enrichment and purification unit: The pretreatment unit is used to pretreat the salt lake brine to remove suspended matter and sediment impurities so that the brine meets the requirements of subsequent treatment; The ion exchange adsorption unit: The pretreated brine is fed into the ion exchange adsorption device, and the lithium ions in the brine are adsorbed by the ion exchange resin. The basic principle of the ion exchange adsorption process is: R-H+Li+⇌R-Li+H+, where RH represents the hydrogen form of the ion exchange resin, R-Li represents the lithium form of the ion exchange resin, Li+ represents lithium ions, and H+ represents hydrogen ions; The elution and regeneration unit is used to elute and regenerate the adsorption saturated ion exchange resin to recover lithium ions. The basic principle of the elution and regeneration process is as follows: R-Li+HCl→R-H+LiCl, where R-Li represents the lithium form of the ion exchange resin, HCl represents hydrochloric acid, RH represents the hydrogen form of the ion exchange resin, and LiCl represents lithium chloride; The lithium ion enrichment and purification unit: enriches and purifies the eluate to obtain a high-purity lithium product. The basic principle of the lithium ion enrichment and purification process is: Li++Cl-→LiCl(s) where Li+ represents lithium ion, Cl- represents chloride ion, and LiCl(s) represents solid lithium chloride; The pretreatment unit includes a raw brine storage tank, an evaporation tank, a mixing tank, a flocculant addition system, a stirring device, a settling tank, a filtration tank, a softening device, a regulating tank, a pumping system, a flow control device and an online monitoring instrument; The raw brine storage tank is used to store raw brine collected from the salt lake to provide a stable supply of raw materials for the pretreatment process; The evaporation pool is used to evaporate and concentrate the brine to precipitate impurity salt ions, while increasing the lithium ion concentration in the brine; The mixing tank is used to dilute the brine to reduce the concentration of impurity ions or adjust the viscosity to prevent the impurity ion concentration or viscosity from being too high and affecting the effect of subsequent ion exchange work; The flocculant addition system is used to add flocculants to the brine to promote the flocculation of suspended matter and sediment; The stirring device is used to stir the brine in the mixing tank to ensure that the flocculant and the brine are fully mixed and the flocculation effect is improved; The sedimentation tank allows the flocs in the flocculated brine to settle under the action of gravity to separate the flocs from the brine; The filter tank further removes fine suspended matter and flocs in the brine, thereby improving the clarity of the brine; The softening device is used to remove calcium and magnesium ions from the brine to prevent these ions from reacting with the ion exchange resin in subsequent processes; The regulating tank is used to adjust the pH value and temperature parameters of the brine to meet the operating requirements of the ion exchange adsorption unit; The pumping system pumps the pretreated brine to the ion exchange adsorption unit; The flow control device is used to accurately control the flow of brine to ensure material balance between the pretreatment unit and the subsequent units; The online monitoring instrument is used to monitor the quality parameters of the brine in real time to ensure that the pretreatment effect meets the specified standards; The ion exchange adsorption unit includes an ion exchange resin filled tower, a feed pump, a flow control valve, a distributor at the top of the resin tower, a collector at the bottom of the resin tower, a backwash pump, a backwash liquid storage tank, a regeneration liquid supply system, a regeneration pump, a control system, an online analyzer and a temperature control system; The ion exchange resin packed tower is filled with ion exchange resin for adsorbing lithium ions in the brine. The resin is generally selected based on its selectivity for lithium ions. The feed pump is used to feed the pretreated brine into the ion exchange resin tower at a certain flow rate; The flow control valve adjusts the feed flow rate of the brine to ensure that the adsorption process is carried out under optimal conditions; The distributor at the top of the resin tower ensures that the brine is evenly distributed to the resin layer, thereby improving the ion exchange efficiency; The collector at the bottom of the resin tower is used to collect the brine after being adsorbed by the resin layer and guide it to the next processing unit; The backwash pump is used to reversely flush the resin after the resin is saturated with adsorption, so as to remove impurities and saturated lithium ions in the resin layer; The backwash liquid storage tank is used to store the solution used for backwashing the resin; The regeneration liquid supply system provides a solution for resin regeneration; The regeneration pump is used to deliver the regeneration liquid into the resin tower at a uniform speed to restore the adsorption capacity of the resin; The control system monitors and adjusts the operating parameters of the ion exchange adsorption unit; The online analytical instrument is used to monitor the lithium ion concentration in the brine, as well as the liquid flow and composition in and out of the resin tower in real time; The temperature control system is used to maintain the temperature in the resin tower within a suitable range to improve the ion exchange efficiency; The lithium ion enrichment and purification unit includes a desorption tower, a desorbent supply system, a desorbent heater, a desorption pump, a desorption liquid collector, a filter tank, a regulating tank, an evaporator, a condenser, a concentrate storage tank, a chemical precipitation tank, an ion exchange membrane, a purification tower, a product collection system, a control system, an online analytical instrument and a waste liquid treatment system; The desorption tower is used to load the resin that has adsorbed lithium ions and elute the lithium ions from the resin through a desorbent; The desorbent supply system is used to provide desorbent, usually by pumping the solution in the desorbent storage tank to the desorption tower; The desorbent heater is used to increase the temperature of the desorbent to enhance the desorption effect and improve the elution efficiency of lithium ions; The desorption pump is used to deliver the desorbent into the desorption tower at a certain flow rate to ensure that the desorption process is carried out evenly; The desorption liquid collector is used to collect the desorption liquid containing lithium ions flowing out of the desorption tower; The filter tank is used to filter the desorption liquid to remove suspended matter and adsorbent debris therein; The regulating tank is used to add acid and alkali to adjust the pH value of the desorption liquid to prevent subsequent equipment corrosion; The evaporator evaporates the water in the desorption liquid by heating, thereby concentrating the lithium ions to obtain a lithium ion-rich solution; The condenser condenses the water vapor evaporated in the evaporator into water for recycling and discharge; The concentrated liquid storage tank is used to store the lithium ion concentrated liquid obtained from the evaporator; The chemical precipitation tank is used to add chemical agents to the concentrated liquid to precipitate and remove calcium and magnesium ions therein; The ion exchange membrane is used to further purify the lithium ion concentrate by removing other ions through the selective permeability of the ion exchange membrane, thereby improving the purity of the lithium ions; The purification tower is used for lithium products with higher purity, and the purification tower can be used for secondary ion exchange or adsorption to remove residual impurity ions; The product collection system is used to collect the enriched and purified lithium ion solution, which can be further processed to prepare a lithium salt product; The control system is used to monitor and adjust the operating parameters during desorption, evaporation, condensation and purification to ensure process stability and product quality; The online analytical instrument monitors the lithium ion concentration and other key parameters in real time to optimize the process; The waste liquid treatment system is used to treat the waste liquid generated during the desorption and purification process to ensure compliance with environmental protection requirements. The following is a specific embodiment used to illustrate the process system of the present invention for continuous ion exchange adsorption and extraction of lithium from salt lake brine.

[0024] Example 1: 1. Preprocessing unit: The collected salt lake brine is pumped into the original brine storage tank with a capacity of 100 cubic meters.

[0025] The brine is pumped into the mixing tank, and flocculants (such as polyferric sulfate) are added at the same time. The stirring speed is 60 rpm and the stirring time is 30 minutes to promote the flocculation and sedimentation of suspended matter and sediment.

[0026] The mixed brine enters the flocculation sedimentation tank and the sedimentation time is 2 hours. The supernatant is filtered through a filter cloth with a filtration accuracy of 50 microns.

[0027] 2. Ion exchange adsorption unit: The filtered brine enters the ion exchange resin packed tower, which is filled with specific lithium ion exchange resin. The resin bed height is 3 meters and the tower diameter is 1 meter.

[0028] The brine flows through the resin tower at a flow rate of 5 cubic meters per hour, and the resin adsorbs lithium ions for 1 hour.

[0029] An online monitoring instrument is used to monitor the lithium ion concentration at the inlet and outlet of the resin tower in real time. When the lithium ion concentration drops to the set value, the feed is stopped and the resin desorption step is carried out.

[0030] 3. Desorption unit: The desorbent is a 4% hydrochloric acid solution, which is passed through the resin tower in reverse at a flow rate of 2 cubic meters per hour, and the desorption time is 2 hours.

[0031] During the desorption process, lithium ions are released from the resin and enter the desorption solution.

[0032] 4. Lithium ion enrichment and purification unit: The desorbed lithium-containing solution enters the evaporator and concentrates the lithium ions by reduced pressure evaporation. The evaporation temperature is 70°C and the vacuum degree is 0.08 MPa.

[0033] The concentrated lithium solution is electrolyzed through an ion exchange membrane to further purify the lithium ions and ultimately obtain a high-purity lithium product.

[0034] Through the above embodiments, the process system of the present invention realizes the continuous and efficient extraction of lithium ions from salt lake brine, and through automated control, ensures the stability of the entire process and the purity of the product. In summary, the present invention provides an efficient, environmentally friendly and economical process system for extracting lithium from salt lake brine, which has important practical application value for promoting the development and utilization of lithium resources.

[0035] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0036] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A continuous ion exchange adsorption process system for extracting lithium from salt lake brine, characterized by: The system includes a pretreatment unit, an ion exchange adsorption unit, an elution regeneration unit, and a lithium ion enrichment and purification unit: The pretreatment unit is used to pretreat the salt lake brine to remove suspended matter and sediment impurities so that the brine meets the requirements of subsequent treatment; The ion exchange adsorption unit: The pretreated brine is fed into the ion exchange adsorption device, and the lithium ions in the brine are adsorbed by the ion exchange resin. The basic principle of the ion exchange adsorption process is: R-H+Li+⇌R-Li+H+, where RH represents the hydrogen form of the ion exchange resin, R-Li represents the lithium form of the ion exchange resin, Li+ represents lithium ions, and H+ represents hydrogen ions; The elution and regeneration unit is used to elute and regenerate the adsorption saturated ion exchange resin to recover lithium ions. The basic principle of the elution and regeneration process is as follows: R-Li+HCl→R-H+LiCl, where R-Li represents the lithium form of the ion exchange resin, HCl represents hydrochloric acid, RH represents the hydrogen form of the ion exchange resin, and LiCl represents lithium chloride; The lithium ion enrichment and purification unit: enriches and purifies the eluate to obtain a high-purity lithium product. The basic principle of the lithium ion enrichment and purification process is: Li++Cl-→LiCl(s) wherein Li+ represents lithium ion, Cl- represents chloride ion, and LiCl(s) represents solid lithium chloride.

2. The continuous ion exchange adsorption process system for extracting lithium from salt lake brine according to claim 1, characterized in that: The pre-processing unit comprises the following steps: S1. Remove suspended matter, silt and colloidal solid impurities in brine by flocculation and filtration to prevent clogging of adsorbent voids; S2. Adjust the pH value of the brine to make it reach the optimal working pH range for the adsorbent while reducing the interference of competing ions; S3. Remove the influence of multivalent interfering ions. According to the characteristics of brine in different salt lakes, chemical precipitation, ion exchange and solvent extraction methods are used to remove the influence of Mg2+, Ca2+ and Fe3+ in the salt lake brine to prevent them from competing with Li+ for adsorption sites. S4. For salt lake brines with different lithium contents, the Li+ concentration is adjusted by concentration and dilution to match the optimal working concentration of the corresponding adsorbent.

3. The continuous ion exchange adsorption process system for extracting lithium from salt lake brine according to claim 1, characterized in that: The ion exchange adsorption unit uses the following ion exchange resins: Step 1: using an inorganic lithium ion sieve adsorbent and an organic ion exchange resin; Step 2: Set up the ion exchange columns to run in series, and use the feed pump to uniformly flow the pretreated salt lake brine into the ion exchange columns in the adsorption area. The lithium ions in the brine replace the original hydrogen ions by occupying the adsorption sites on the adsorbent, thereby completing the adsorption process.

4. The continuous ion exchange adsorption process system for extracting lithium from salt lake brine according to claim 1, characterized in that: The elution regeneration unit adopts the following method: Step 1: Select low-concentration strong acid and pure water as eluents according to the selected adsorbent type; Step 2: Set up the ion exchange columns to operate in series, and use the desorption pump to uniformly pass the prepared eluent into the ion exchange column in the desorption zone, so that the saturated ion exchange resin is fully countercurrently contacted to replace the lithium ions embedded in the adsorption sites to achieve the lithium ion elution process; Step 3: Set up the ion exchange column to run in series as a regeneration unit for water washing after pickling to remove residual acid and remaining impurity ions after pickling to make the effluent pH ≈ 7, so that it can re-enter the adsorption unit for adsorption operation after regeneration and realize recycling.

5. The continuous ion exchange adsorption process system for extracting lithium from salt lake brine according to claim 1, characterized in that: The lithium ion enrichment and purification unit adopts the following method: S11. Pre-treat the eluate by filtering to remove suspended matter and adsorbent debris, and add acid and alkali to adjust the pH of the eluate to neutral to prevent subsequent equipment corrosion; S12, concentrating the eluate using evaporation concentration and membrane separation technology; S13, removing impurity ions by chemical precipitation; S14. High-purity lithium products are obtained through fine purification through solvent extraction and membrane separation technology.

6. The continuous ion exchange adsorption process system for extracting lithium from salt lake brine according to claim 1, characterized in that: The entire system is automatically controlled, using a process method in which multiple columns are connected in series in three functional zones: adsorption, elution, and regeneration. The system is uniformly controlled by a distribution valve. After each step cycle, the distribution valve drives the exchange column to rotate in the opposite direction. That is, the movement direction of the ion exchange column is opposite to the direction of material flow, thereby enabling the ion exchange column to rotate in the opposite direction in each functional zone and switch between functional zones. The pretreated salt lake brine is passed into the adsorption zone for adsorption, and the adsorption columns that have been saturated with adsorption are transferred to the elution zone in turn by rotating the rotary valve. The eluent quickly washes the ion exchange column to replace the lithium-containing material and remove impurity ions. After desorption, the eluent enriches lithium and flows out of the system as a qualified liquid. The eluted ion exchange column is transferred to the regeneration zone for water washing to remove residual acid and remaining impurity ions. The regeneration is completed when the pH of the outlet water is ≈ 7. The ion exchange column after regeneration re-enters the adsorption zone for adsorption operation, so that the multi-column system forms a complete loop. The adsorption-elution-regeneration functional areas are spatially separated but the process is continuous, so as to realize the recycling of ion exchange columns and improve production efficiency and stability. This system is suitable for various salt lake brine resources and has a high lithium ion extraction rate and purity.

7. The continuous ion exchange adsorption process system for extracting lithium from salt lake brine according to claim 1, characterized in that: The pretreatment unit includes a raw brine storage tank, an evaporation tank, a mixing tank, a flocculant addition system, a stirring device, a settling tank, a filtration tank, a softening device, a regulating tank, a pumping system, a flow control device and an online monitoring instrument; The raw brine storage tank is used to store raw brine collected from the salt lake to provide a stable supply of raw materials for the pretreatment process; The evaporation pool is used to evaporate and concentrate the brine to precipitate impurity salt ions, while increasing the lithium ion concentration in the brine; The mixing tank is used to dilute the brine to reduce the concentration of impurity ions and adjust the viscosity, so as to prevent the impurity ion concentration and viscosity from being too high and affecting the effect of subsequent ion exchange work; The flocculant addition system is used to add flocculants to the brine to promote the flocculation of suspended matter and sediment; The stirring device is used to stir the brine in the mixing tank to ensure that the flocculant and the brine are fully mixed and the flocculation effect is improved; The sedimentation tank allows the flocs in the flocculated brine to settle under the action of gravity to separate the flocs from the brine; The filter tank further removes fine suspended matter and flocs in the brine, thereby improving the clarity of the brine; The softening device is used to remove calcium and magnesium ions from the brine to prevent these ions from reacting with the ion exchange resin in subsequent processes; The regulating tank is used to adjust the pH value and temperature parameters of the brine to meet the operating requirements of the ion exchange adsorption unit; The pumping system pumps the pretreated brine to the ion exchange adsorption unit; The flow control device is used to accurately control the flow of brine to ensure material balance between the pretreatment unit and the subsequent units; The online monitoring instrument is used to monitor the quality parameters of the brine in real time to ensure that the pretreatment effect meets the specified standards.

8. The continuous ion exchange adsorption process system for extracting lithium from salt lake brine according to claim 1, characterized in that: The ion exchange adsorption unit includes an ion exchange resin filled tower, a feed pump, a flow control valve, a distributor at the top of the resin tower, a collector at the bottom of the resin tower, a backwash pump, a backwash liquid storage tank, a regeneration liquid supply system, a regeneration pump, a control system, an online analyzer and a temperature control system; The ion exchange resin packed tower is filled with ion exchange resin for adsorbing lithium ions in the brine, and the resin is selected based on its selectivity for lithium ions; The feed pump is used to feed the pretreated brine into the ion exchange resin tower at a uniform speed; The flow control valve adjusts the feed flow rate of the brine to ensure that the adsorption process is carried out under optimal conditions; The distributor at the top of the resin tower ensures that the brine is evenly distributed to the resin layer, thereby improving the ion exchange efficiency; The collector at the bottom of the resin tower is used to collect the brine after being adsorbed by the resin layer and guide it to the next processing unit; The backwash pump is used to reversely flush the resin after the resin is saturated with adsorption, so as to remove impurities and saturated lithium ions in the resin layer; The backwash liquid storage tank is used to store the solution used for backwashing the resin; The regeneration liquid supply system provides a solution for resin regeneration; The regeneration pump is used to deliver the regeneration liquid into the resin tower at a uniform speed to restore the adsorption capacity of the resin; The control system monitors and adjusts the operating parameters of the ion exchange adsorption unit; The online analytical instrument is used to monitor the lithium ion concentration in the brine, as well as the liquid flow and composition in and out of the resin tower in real time; The temperature control system is used to maintain the temperature in the resin tower to improve the ion exchange efficiency.

9. The continuous ion exchange adsorption process system for extracting lithium from salt lake brine according to claim 1, characterized in that: The lithium ion enrichment and purification unit includes a desorption tower, a desorbent supply system, a desorbent heater, a desorption pump, a desorption liquid collector, a filter tank, a regulating tank, an evaporator, a condenser, a concentrate storage tank, a chemical precipitation tank, an ion exchange membrane, a purification tower, a product collection system, a control system, an online analytical instrument and a waste liquid treatment system; The desorption tower is used to load the resin that has adsorbed lithium ions and elute the lithium ions from the resin through a desorbent; The desorbent supply system is used to provide desorbent, and the solution in the desorbent storage tank is transported to the desorption tower by a pump; The desorbent heater is used to increase the temperature of the desorbent to enhance the desorption effect and improve the elution efficiency of lithium ions; The desorption pump is used to deliver the desorbent into the desorption tower at a uniform speed to ensure that the desorption process is carried out evenly; The desorption liquid collector is used to collect the desorption liquid containing lithium ions flowing out of the desorption tower; The filter tank is used to filter the desorption liquid to remove suspended matter and adsorbent debris therein; The regulating tank is used to add acid and alkali to adjust the pH value of the desorption liquid to prevent subsequent equipment corrosion; The evaporator evaporates the water in the desorption liquid by heating, thereby concentrating the lithium ions to obtain a lithium ion-rich solution; The condenser condenses the water vapor evaporated in the evaporator into water for recycling and discharge; The concentrated liquid storage tank is used to store the lithium ion concentrated liquid obtained from the evaporator; The chemical precipitation tank is used to add chemical agents to the concentrated liquid to precipitate and remove calcium and magnesium ions therein; The ion exchange membrane is used to further purify the lithium ion concentrate by removing other ions through the selective permeability of the ion exchange membrane, thereby improving the purity of the lithium ions; The purification tower is used for lithium products with higher purity, and the purification tower is used for secondary ion exchange and adsorption to remove residual impurity ions; The product collection system is used to collect the enriched and purified lithium ion solution and process the solution to prepare a lithium salt product; The control system is used to monitor and adjust the operating parameters during desorption, evaporation, condensation and purification to ensure process stability and product quality; The online analytical instrument monitors the lithium ion concentration and other key parameters in real time to optimize the process; The waste liquid treatment system is used to treat the waste liquid generated during the desorption and purification process to ensure compliance with environmental protection requirements.

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