Method for preparing lithium carbonate from lithium-containing brine

Abstract

The invention relates to the field of extraction of lithium from brine, and discloses a method for preparing lithium carbonate from lithium-containing brine. The method comprises the following steps: (1) adsorbing Li by adopting a lithium adsorption material, and desorbing to obtain a desorption solution; (2) carrying out nanofiltration on the desorption solution to obtain nanofiltration permeate and nanofiltration trapped fluid; (3) performing forward osmosis on the nanofiltration permeate to obtain forward osmosis concentrated water; (4) performing high-pressure reverse osmosis on the forward osmosis concentrated water to obtain high-pressure reverse osmosis concentrated water and high-pressure reverse osmosis fresh water; (5) performing bipolar membrane electrodialysis to obtain alkali liquor; and (6) extracting lithium hydroxide from the alkali liquor, and reacting with carbon dioxide to obtain lithium carbonate. The method can fully enrich lithium in the lithium-containing brine, has high yield and purity, is especially suitable for low-grade oilfield produced water which is difficult to treat under general conditions and has obviously lower lithium concentration, and is simple in process and low in production cost.

Description

Technical Field

[0001] The invention relates to the field of lithium extraction from brine, and in particular to a method for preparing lithium carbonate by utilizing lithium-containing brine. Background Art

[0002] Lithium is the metal with the lowest density in nature. It is currently widely used in energy, electronics, medical care, aviation and other fields and is known as "industrial MSG".

[0003] Lithium resources are mainly distributed in the following countries and regions: Chile, Australia, Argentina, Bolivia, and China. Chile is the world's largest lithium producer, accounting for more than 40% of the world's lithium reserves. China's lithium reserves are also relatively rich, and the lithium industry has developed rapidly in recent years. Lithium resources mainly exist in the form of spodumene, borax ore, and salt lake lithium storage. In recent years, the mining method of lithium has gradually shifted from hard rock mining to brine lithium extraction. For lithium extraction from brine, people have developed methods such as adsorption, precipitation, extraction, and membrane separation. These methods are applicable to different types of brine. For example, the precipitation method is suitable for low magnesium-lithium ratio brine, the adsorption method is suitable for high magnesium-lithium ratio brine; the membrane method is mainly suitable for brine with lower concentration.

[0004] CN1542147A discloses a method for separating magnesium and enriching lithium from salt lake brine by nanofiltration, using a monovalent ion selective nanofiltration membrane to enrich lithium ions in lithium-containing salt lake brine through multi-stage nanofiltration, but this method is only suitable for lithium-rich brine with low magnesium and low mineralization. CN103074502A discloses a salt lake brine treatment method for separating lithium from salt lake brine with a high magnesium-lithium ratio, evaporating and concentrating the salt lake brine, then removing sulfate and magnesium ions by chemical methods, removing magnesium through a nanofiltration unit after dilution, and then obtaining lithium-rich brine through reverse osmosis and deep magnesium removal and salt field evaporation to prepare lithium carbonate, but this process also has technical defects such as complex process and large amount of fresh water dilution. The above scheme mainly extracts lithium resources from salt lake brine. Since the salt lake brine has a higher taste, it is easier to extract, but the above method is not suitable for low-grade oilfield produced water with significantly lower lithium concentration. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned problem in the prior art that it is difficult to extract lithium from low-grade oilfield produced water with significantly lower lithium concentration, and to provide a method for preparing lithium carbonate using lithium-containing brine. The method can fully enrich the lithium in the lithium-containing brine and has a high yield and purity. It is particularly suitable for low-grade oilfield produced water with significantly lower lithium concentration that is difficult to handle under normal circumstances, and the process is simple and the production cost is low.

[0006] In order to achieve the above object, the present invention provides a method for preparing lithium carbonate using lithium-containing brine, the method comprising:

[0007] (1) using a lithium adsorption material to adsorb Li from lithium-containing brine, and desorbing the lithium adsorption material to obtain a desorption solution;

[0008] (2) subjecting the desorbed liquid to nanofiltration to obtain a nanofiltration permeate and a nanofiltration retentate;

[0009] (3) using the nanofiltration permeate as a forward osmosis treated liquid to perform forward osmosis to obtain forward osmosis concentrated water;

[0010] (4) subjecting the forward osmosis concentrated water to high-pressure reverse osmosis to obtain high-pressure reverse osmosis concentrated water and high-pressure reverse osmosis fresh water;

[0011] (5) subjecting the high-pressure reverse osmosis concentrated water and the high-pressure reverse osmosis fresh water to bipolar membrane electrodialysis to obtain alkali solution in an alkali chamber;

[0012] (6) Lithium hydroxide is extracted from the alkali solution, and lithium hydroxide is reacted with carbon dioxide to obtain lithium carbonate.

[0013] Through the above technical solution, lithium can be fully extracted from low-grade oil field produced water with significantly lower lithium concentration, which is difficult to treat under normal circumstances, to obtain lithium carbonate products with simple process and low cost. In addition, the above method has high lithium extraction rate and purity, short lithium extraction cycle, strong continuity, no additional pollution, and significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The product of Preparation Example 1, the modified Li in step (1) of Preparation Example 1 1.33 Mn 1.67 O4, and the infrared spectrum of the polyvinyl alcohol used in Preparation Example 1;

[0015] Figure 2 The product of Preparation Example 1 and the modified Li 1.33 Mn 1.67 XRD pattern of O4;

[0016] Figure 3 is a SEM (scanning electron microscope) image of the product of Preparation Example 1;

[0017] Figure 4 This is a physical picture of the product of Preparation Example 1. DETAILED DESCRIPTION

[0018] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0019] The present invention provides a method for preparing lithium carbonate by using lithium-containing brine, the method comprising:

[0020] (1) using a lithium adsorption material to adsorb Li from lithium-containing brine, and desorbing the lithium adsorption material to obtain a desorption solution;

[0021] (2) subjecting the desorbed liquid to nanofiltration to obtain a nanofiltration permeate and a nanofiltration retentate;

[0022] (3) using the nanofiltration permeate as a forward osmosis treated liquid to perform forward osmosis to obtain forward osmosis concentrated water;

[0023] (4) subjecting the forward osmosis concentrated water to high-pressure reverse osmosis to obtain high-pressure reverse osmosis concentrated water and high-pressure reverse osmosis fresh water;

[0024] (5) subjecting the high-pressure reverse osmosis concentrated water and the high-pressure reverse osmosis fresh water to bipolar membrane electrodialysis to obtain alkali solution in an alkali chamber;

[0025] (6) Lithium hydroxide is extracted from the alkali solution, and lithium hydroxide is reacted with carbon dioxide to obtain lithium carbonate.

[0026] The inventors of the present invention have found in their research that the above method can fully extract Li from lithium-containing brine and obtain a higher extraction rate and purity, which is particularly suitable for low-grade oilfield produced water with significantly lower lithium concentration that is generally difficult to treat.

[0027] According to the present invention, preferably, before performing step (1), the method further comprises: ultrafiltration of the lithium-containing brine. In this way, the suspended matter, macromolecular organic matter, colloid, etc. in the lithium-containing brine can be fully removed. It can be understood that after ultrafiltration, ultrafiltration permeate and ultrafiltration retentate will be obtained, and the suspended matter and other impurities in the lithium-containing oil field produced water will be retained in the ultrafiltration retentate, and the lithium element of particular concern will enter the ultrafiltration permeate, and the ultrafiltration permeate will be used for subsequent adsorption and other operations.

[0028] Preferably, the ultrafiltration conditions include: ultrafiltration pressure of 0.1-0.5 MPa and temperature of 15-35°C.

[0029] According to a preferred embodiment of the present invention, the molecular weight cut-off of the ultrafiltration membrane used is 10000-30000 Da. For example, the tubular ultrafiltration membrane model VFU-030 produced by Jiarong Technology Co., Ltd. can be used.

[0030] According to the present invention, preferably, the water quality of the lithium-containing brine includes: Li + The concentration is 20-80 mg / L, and the concentration of alkaline earth metal ions is 1200-1500 mg / L. Alkaline earth metal ions generally include magnesium ions and calcium ions.

[0031] Preferably, the lithium-containing brine is produced water from a lithium-containing oil field.

[0032] Preferably, the water quality of the produced water from the lithium-containing oil field includes: Li + The concentration is 40-65mg / L, Na + The concentration is 3300-3600mg / L, K + The concentration is 280-320mg / L, Mg 2+ The concentration is 1200-1350mg / L, Ca 2+ The concentration is 40-55 mg / L, Cl - Concentration is 8700-9100mg / L, SO4 2- The concentration is 1700-2100 mg / L, the pH is 7-8.5, the total organic matter is 600-1600 mg / L, and the total dissolved solid is 35000-38000 mg / L.

[0033] The method provided by the present invention is particularly suitable for the above-mentioned lithium-containing oil field produced water, and can extract Li therein with higher purity and extraction rate.

[0034] According to the present invention, preferably, in step (1), the operating conditions of adsorption include: adsorption flow rate 2-3.2 BV / h, adsorption temperature 10-32°C, and adsorption time 6-8h.

[0035] It can be understood that BV represents the filling volume of the lithium adsorbent material. Generally, the adsorbent material is filled in a container (such as an adsorption column), and then the fluid to be adsorbed continuously passes through the adsorption column to contact with the adsorbent material for adsorption. 2-3.2 BV / h means that the volume of the fluid per hour is 2-3.2 times the filling volume of the lithium adsorbent.

[0036] After the adsorption is completed, most of the lithium in the lithium-containing brine is adsorbed on the lithium adsorption material, and there is less lithium in the liquid phase (which can be called lithium-poor ultrafiltrate at this time). The lithium-poor ultrafiltrate can be treated as waste liquid in a centralized manner.

[0037] According to the present invention, preferably, the operating conditions of desorption include: a desorption flow rate of 2-3.2 BV / h of the desorbent, a temperature of 10-32° C., and a time of 6-8 hours. The desorbent is continuously passed through a container filled with a lithium adsorbent material that has completed adsorption. The Li adsorbed on the lithium adsorbent enters the desorption liquid through the above desorption.

[0038] Preferably, the desorbent is selected from water or an inorganic acid solution. The inorganic acid concentration in the inorganic acid solution may be 0.1-1 mol / L. The inorganic acid may be hydrochloric acid.

[0039] Among them, through the above operation, the water quality of the desorption liquid can generally reach: Li+ The concentration is 420-630mg / L, Na + The concentration is 150-170mg / L, K + The concentration is 35-40mg / L, Mg 2+ The concentration is 74-80mg / L, Ca 2+ The concentration is 4-6mg / L.

[0040] According to the present invention, preferably, the operating conditions of the nanofiltration include: temperature of 15-35°C, operating pressure of 2-5MPa, and time of 5-6h. Generally, the nanofiltration membrane has good permeability to monovalent ions, but poor permeability to ions of other valence states, so that the enrichment of monovalent ions can be achieved, and the monovalent ion concentration in the nanofiltration permeate is relatively high; the nanofiltration retentate refers to the part that has not passed through the nanofiltration membrane, and the monovalent ion concentration therein is significantly lower.

[0041] Preferably, the molecular weight cut-off of the nanofiltration membrane used in nanofiltration is 50-500Da. Under the above conditions, the nanofiltration membrane can have better monovalent ion selectivity, for example, the retention rate of divalent ions can reach more than 90%. For example, the nanofiltration membrane of model RS10-50C or RS10-35C of Delanmer can be selected.

[0042] Among them, the number of nanofiltration stages can be 1-3. The number of stages can be determined according to the ion content in the desorption liquid. For example, when the magnesium-lithium mass ratio is lower than 10, the first-stage nanofiltration can be used; when the magnesium-lithium mass ratio is higher than 10, the second-stage or third-stage nanofiltration can be used. Taking the third-stage nanofiltration as an example, it means that the liquid with increased monovalent ion content obtained after the first nanofiltration is subjected to the second nanofiltration, and then the liquid with increased monovalent ion content obtained after the second nanofiltration is subjected to the third nanofiltration to obtain the nanofiltration permeate.

[0043] By adopting the method of the present invention, the water quality of the nanofiltration permeate can meet the following requirements: Li + The concentration is 400-710mg / L, Na + The concentration is 175-190mg / L, K + The concentration is 39-47mg / L, Mg 2+ The concentration is 14-16mg / L.

[0044] The operation mode of the forward osmosis may also include: using the nanofiltration retentate as the forward osmosis draw liquid. It is understood that the forward osmosis uses the osmotic pressure difference of the solution on both sides of the membrane as the driving force. The two sides of the membrane are the treated liquid and the draw liquid respectively. The water molecules in the treated liquid enter the draw liquid through the membrane under the drive of the osmotic pressure difference. The treated liquid is continuously concentrated to obtain forward osmosis concentrated water; due to the continuous entry of water molecules, the draw liquid is continuously diluted to obtain the forward osmosis diluted draw liquid. In addition, the evaporation mother liquor obtained during the evaporation crystallization in the subsequent step (6) and the nanofiltration retentate can be mixed and used together as the forward osmosis draw liquid.

[0045] According to a particularly preferred embodiment of the present invention, when the lithium ion concentration in the forward osmosis dilute draw solution is higher than 0.5 times the lithium ion concentration in the lithium-containing brine after ultrafiltration, and the magnesium-lithium mass ratio in the forward osmosis dilute draw solution is not more than 40, the method further comprises: mixing the forward osmosis dilute draw solution and the lithium-containing brine after ultrafiltration, and jointly performing the adsorption in step (1). When the above conditions are not met, the forward osmosis dilute draw solution and the lithium-deficient ultrafiltrate can be treated as waste liquid and centrally disposed of.

[0046] According to the present invention, preferably, the forward osmosis operation conditions include: temperature 10-30°C, time 3-12h. Under the above operation conditions, the volume of forward osmosis concentrated water can generally be 0.3-0.5 times that of nanofiltration permeate.

[0047] The membrane used for forward osmosis can be the forward osmosis membrane model HTICTAES produced by Shanghai Tongqin Environmental Protection Technology Co., Ltd.

[0048] By adopting the method provided by the present invention, the water quality of forward osmosis concentrated water may include: Li + The concentration is 1100-1450mg / L, Na + The concentration is 350-460mg / L, K + The concentration is 80-98mg / L, Mg 2+ The concentration is 30-35mg / L.

[0049] According to the present invention, preferably, in step (4), the operating conditions of the high-pressure reverse osmosis include: a temperature of 12-36°C, an operating pressure of 7.5-10 MPa, and a time of 4-6 hours. The operating pressure can be controlled by a valve. The high-pressure reverse osmosis membrane assembly can be a commercial seawater desalination reverse osmosis membrane assembly, for example, the PRO series high-pressure reverse osmosis membrane of Delanmeyer.

[0050] After high-pressure reverse osmosis, the liquid phase with increased lithium ion concentration is high-pressure reverse osmosis concentrated water, and the other part is high-pressure reverse osmosis fresh water.

[0051] Using the method provided by the present invention, the water quality of high-pressure reverse osmosis concentrated water can generally include: TDS (total dissolved solids) not less than 20000 mg / L, preferably 22000-75000 mg / L, Li + The concentration is 2400-3050mg / L, Na + The concentration is 750-970mg / L, K + The concentration is 190-210mg / L, Mg 2+ The concentration is 65-75 mg / L. Among them, the system used in bipolar membrane electrodialysis has the following structure: between the anode chamber and the cathode chamber are bipolar membrane, acid chamber, monovalent ion selective anion membrane (for example, it can be purchased from Japan ASTOM Company, model APX-D), desalination chamber, monovalent ion selective cation membrane (for example, it can be purchased from Japan ASTOM Company, model CXP-S), alkali chamber, bipolar membrane, that is, bipolar membrane electrodialysis is a three-chamber system with the above structure, and the two sides can be connected to the titanium cathode plate and anode plate coated with ruthenium, respectively, and the two polar plates are connected to a DC power supply. The bipolar membrane can be purchased from Hangzhou Ke Rui Environmental Energy Technology Co., Ltd., and the model is BPX bipolar membrane.

[0052] According to the present invention, preferably, in step (5), the operation mode of the bipolar membrane electrodialysis includes: using high-pressure reverse osmosis concentrated water as desalination chamber inlet water, using high-pressure reverse osmosis fresh water as acid chamber and alkali chamber inlet water, the operating voltage is 2-3V, the current density is 600-900A / m 2 , time 5-7h.

[0053] In bipolar membrane electrodialysis, under the action of electric field force, Li + The ion selective cation membrane reaches the base chamber and reacts with the OH generated by the bipolar membrane. - Forming an alkaline solution containing LiOH (which may also contain a small amount of KOH); Cl - The ion selective anion membrane reaches the acid chamber and reacts with the H generated by the bipolar membrane. + HCl acid solution is formed. The HCl acid solution formed in the acid chamber can be used as a desorbent for lithium adsorption materials, which can reduce production costs, fully utilize resources, and avoid environmental impact. The brine discharged from the desalination chamber can be mixed with forward osmosis concentrated water to perform high-pressure reverse osmosis together.

[0054] Among them, in the alkaline solution obtained from the alkaline chamber, Li + The concentration can be 0.9-1.2 mol / L.

[0055] According to the present invention, preferably, the method of extracting lithium hydroxide from the alkali solution includes: evaporating and crystallizing the alkali solution. For example, evaporation and crystallization can be performed at 80-100° C. After evaporation and crystallization, a mixture of lithium hydroxide and evaporation mother liquor can be obtained, and the mixture is subjected to solid-liquid separation (such as centrifugation and filtration) to obtain lithium hydroxide and evaporation mother liquor respectively. The evaporation mother liquor can be mixed with the nanofiltration retentate and used together as the forward osmosis extraction liquid. In this way, the purity of the prepared lithium carbonate product can be further improved.

[0056] According to the present invention, preferably, the reaction of lithium hydroxide with carbon dioxide comprises: dissolving lithium hydroxide in a solvent (such as water), contacting with carbon dioxide under the condition of 23-27°C, and reacting to a liquid phase pH value of 11.5-12.5. Wherein, after lithium hydroxide is dissolved in a solvent, the mass concentration of lithium hydroxide in the solution can be 85-105g / L. The above reaction (carbonization reaction) can be carried out in a gas-liquid reactor, and the reaction reaches the above pH value in the liquid phase as the end point. Carbon dioxide can be used in the form of gas. After the reaction is completed, a precipitate is obtained. The precipitate is washed, filtered and dried (the temperature can be 40-100°C, and the time can be 3-24h) to obtain lithium carbonate. The method provided by the present invention can obtain lithium carbonate with a higher purity.

[0057] The method provided by the present invention is not limited by weather and salt drying sites, and shortens the lithium extraction cycle. The lithium-containing solution is concentrated through the forward osmosis process, which greatly reduces the cost; the application of bipolar membrane electrodialysis and gas-liquid reactor can directly obtain lithium carbonate products with good continuity and high product purity. In addition, the process is simple, easy to operate, and has low energy consumption. The purity of lithium extraction is higher than that of traditional processes, and has significant economic benefits.

[0058] According to a particularly preferred embodiment of the present invention, the lithium adsorption material comprises a skeleton and a lithium ion sieve material dispersed in the skeleton, the lithium ion sieve material is connected to the skeleton via a coupling agent, and the skeleton is provided by a cross-linked or uncross-linked polyhydroxy polymer.

[0059] The lithium adsorption material preferably provided by the present invention has good hydrophilicity, stable structure, acid and alkali resistance and high lithium adsorption capacity, and is more suitable for practical applications.

[0060] According to the present invention, preferably, the average particle size of the lithium adsorption material is 1-5 mm, more preferably 2-4 mm.

[0061] Preferably, relative to the mass of the lithium adsorption material, the mass content of the lithium ion sieve material is 10-80wt%, more preferably 68-77wt% (for example, it can be 68wt%, 69wt%, 70wt%, 71wt%, 72wt%, 73wt%, 74wt%, 75wt%, 76wt%, 77wt% and the range formed by any two of the above values ​​and the value within the range).

[0062] Preferably, the specific surface area of ​​the lithium adsorption material is 10-500m 2 / g, more preferably 10-45m 2 / g (for example, it can be 10m 2 / g, 15m 2 / g, 20m 2 / g, 25m 2 / g, 30m 2 / g, 35m 2 / g, 40m 2 / g, 45m 2 / g and the range formed by any two of the above values ​​and the value within the range).

[0063] Preferably, the average pore size of the lithium adsorption material is 0.1-10 μm, more preferably 2-5 μm (for example, it can be 2 μm, 3 μm, 4 μm, 5 μm, and a range formed by any two of the above values, and a value within the range).

[0064] Preferably, the pore volume of the lithium adsorption material is 10-100m 3 / g, more preferably 50-85m 3 / g (for example, it can be 50m 3 / g, 55m 3 / g, 60m 3 / g, 65m 3 / g, 70m 3 / g, 75m 3 / g, 80m 3 / g, 85m 3 / g and the range formed by any two of the above values ​​and the value within the range).

[0065] Preferably, at 25° C., the lithium adsorption material has a water absorption rate of 0.1-2 g / g for pure water and a volume swelling rate of 2-10% (for example, it can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and a range formed by any two of the above values ​​and values ​​within the range).

[0066] According to the present invention, preferably, the lithium ion sieve material is selected from titanium and / or manganese lithium ion sieve materials.

[0067] Preferably, the average particle size of the lithium ion sieve material is 10-500 μm (for example, it may be 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, and a range formed by any two of the above values ​​and a value within the range).

[0068] Preferably, the polyhydroxy polymer is at least one selected from polyvinyl alcohol, chitosan, polyethylene glycol and carboxymethyl cellulose, more preferably polyvinyl alcohol.

[0069] Preferably, the coupling agent is selected from silane coupling agents.

[0070] Preferably, the silane coupling agent is selected from at least one of a mercapto-containing silane coupling agent and an epoxy-containing silane coupling agent, and is preferably an epoxy-containing silane coupling agent.

[0071] More preferably, the epoxy-containing silane coupling agent is selected from at least one of γ-(2,3-glycidoxypropyl)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(2,3-glycidoxypropyl)methyldiethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0072] According to the present invention, preferably, the lithium ion sieve material is a lithium ion sieve material modified with polyphenol.

[0073] Preferably, the polyphenol modification method comprises: mixing a lithium ion sieve material and polyphenol to modify the lithium ion sieve material.

[0074] Preferably, the mixing is performed in a solution environment.

[0075] Preferably, the mass ratio of the lithium ion sieve material to the polyphenol is 1:(0.08-0.3).

[0076] Preferably, the mixing time is 1-3 hours.

[0077] The polyphenol is selected from at least one of tannic acid, tea polyphenols, dopamine, eriodictyol, epicatechin, luteolin, kaempferol, myricetin and genistein, preferably at least one of tannic acid, tea polyphenols and dopamine.

[0078] The present invention also provides a method for preparing a lithium adsorption material, the method comprising:

[0079] In the presence of a coupling agent, the polyhydroxy polymer and the lithium ion sieve material are coupled.

[0080] It can be understood that lithium ion sieve material refers to a material with lithium adsorption function. When used for adsorption, hydrogen ions and lithium ions in the lithium ion sieve material are exchanged, thereby enriching lithium ions on the lithium adsorption material. When lithium ion sieve material is used to prepare lithium adsorption material, the lithium ion sieve material can be a lithium ion sieve rich in hydrogen ions; or it can be a lithium ion sieve precursor with less hydrogen ion content but more lithium ions. Before being used for adsorption, it is acid-washed to replace the lithium ions on it with hydrogen ions to obtain a lithium ion sieve. That is, the lithium ion sieve material described in the present application includes a lithium ion sieve and a lithium ion sieve precursor.

[0081] The inventors of the present invention have found in their research that the lithium adsorption material prepared by the above method has a large saturated adsorption capacity for lithium, a high extraction rate, and a high selectivity. Among them, the polyhydroxy polymer is hydrophilic, the material skeleton has a network structure, the porosity and specific surface area are large, and the adsorbent loading is high; it is beneficial to increase the adsorption speed and adsorption amount of lithium. After coupling, the compatibility of the polyhydroxy polymer and the lithium ion sieve material is also better, the lithium ion sieve material is not easy to agglomerate, and the distribution on the polyhydroxy polymer is more uniform, which is more conducive to the adsorption effect.

[0082] The specific type of coupling agent is not particularly limited, as long as it can simultaneously connect the polyhydroxy polymer and the lithium ion sieve material. However, preferably, the coupling agent is selected from a silane coupling agent. The silane coupling agent generally has a YR-Si-X3 structure, wherein Y is an organic functional group, R is an alkylene group, and X is an alkoxy group. The alkoxy group can obtain a hydroxyl group after hydrolysis, thereby reacting with an inorganic substance such as a lithium ion sieve material; the organic functional group can react with an organic substance such as polyvinyl alcohol.

[0083] According to the present invention, preferably, the silane coupling agent is selected from at least one of a silane coupling agent containing a mercapto group and a silane coupling agent containing an epoxy group, preferably a silane coupling agent containing an epoxy group. It can be understood that the mercapto group and the epoxy group refer to the groups contained in the YR structure in the silane coupling agent.

[0084] According to the present invention, more preferably, the epoxy-containing silane coupling agent is selected from at least one of γ-(2,3-glycidoxy)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(2,3-glycidoxypropyl)methyldiethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The mercapto-containing silane coupling agent is such as γ-mercaptopropyltriethoxysilane.

[0085] According to the present invention, preferably, the polyhydroxy polymer is selected from at least one of polyvinyl alcohol, chitosan, polyethylene glycol and carboxymethyl cellulose, more preferably polyvinyl alcohol. The weight average molecular weight of the polyhydroxy polymer is not particularly limited, for example, it can be 50000-250000 g / mol. The alcoholysis degree of polyvinyl alcohol can be 83-99%.

[0086] According to the present invention, preferably, the lithium ion sieve material is selected from titanium and / or manganese lithium ion sieve materials. For example, it can be LiMn2O4, Li 1.6 Mn 1.6 O4、Li 1.33 Mn 1.67 O4、Li4Mn5O 12 , LiMnO, LiMnO2, Li2TiO3, Li 1.33 Ti 1.66 O4、Li4Ti5O 12 Such lithium ion sieve precursors, or their corresponding lithium ion sieves after acid washing.

[0087] According to another preferred embodiment of the present invention, the lithium ion sieve material is selected from aluminum-based lithium ion sieve materials. For example, it can be LiCl·2Al(OH)3·nH2O. When the aluminum-based lithium ion sieve material is used, when desorbing the lithium adsorption material adsorbed with lithium ions, pure water can be used to complete the desorption, and an acid solution is not required, which can also reduce costs.

[0088] According to the present invention, preferably, the average particle size of the lithium ion sieve material is 10-500 μm (for example, it can be 10 μm, 50 μm, 100 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 500 μm, and the range formed by any two of the above values ​​and the value within the range). During preparation, the lithium ion sieve material in the form of powder within the above particle size range can be used.

[0089] The above-mentioned lithium ion sieve material can be purchased or prepared by itself. The preparation method can be a conventional method in the field. Taking the high-temperature solid-phase synthesis preparation method of Li2TiO3 as an example: anatase TiO2 and Li2CO3 (both collectively referred to as solids) can be weighed at a molar ratio of 1:1-1.2, added to a stainless steel ball mill, and then ethanol equivalent to 1.8-2.2 times the mass of the solid and stainless steel beads equivalent to 18-25 times the mass of the solid (the diameter can be 3-5mm) are added to the ball mill, and a planetary ball mill is used to ball mill at a speed of 180-220rpm for 3.5-4.5h, and after drying at 35-45℃, it is placed in a muffle furnace and roasted at 750-850℃ in an air atmosphere for 5-7h; after cooling, it is eluted with 0.4-0.6mol / L HCl solution for 18-28h to obtain the lithium ion adsorbent powder Li2TiO3.

[0090] According to the present invention, preferably, before coupling, the method further comprises: mixing the lithium ion sieve material and polyphenol to modify the lithium ion sieve material.

[0091] According to the present invention, preferably, the mixing is performed in a solution environment, for example, in an aqueous solution environment of polyphenols.

[0092] Preferably, the mass ratio of the lithium ion sieve material to the polyphenol is 1:(0.08-0.3). In the aqueous solution, the concentration of the polyphenol can be 0.1-1 mg / L.

[0093] Preferably, the mixing time is 1-3 hours. Stirring can be performed during the mixing (the rotation speed can be 300-500 rpm), and the mixing can be performed at room temperature.

[0094] Preferably, the polyphenol is selected from at least one of tannic acid, tea polyphenols, dopamine, eriodictyol, epicatechin, luteolin, kaempferol, myricetin and genistein, preferably at least one of tannic acid, tea polyphenols and dopamine.

[0095] The above modification can generally form a polyphenol modified layer of about 0.1-2 nm on the surface of the lithium ion sieve material, so that the surface of the lithium ion sieve material contains a large number of hydroxyl groups, thereby having better compatibility with the polyhydroxy polymer skeleton and being easier to disperse evenly in the skeleton, further ensuring that the lithium ion sieve material will not aggregate or flow away in the long-term erosion of water flow and pressure.

[0096] After the mixing and stirring is completed, the material can be separated into solid and liquid (such as by centrifugation), and the obtained solid phase material can be dried (the temperature can be 30-80° C., and the time can be 4-12 hours).

[0097] By using the above method, a polyphenol modification layer of 10-50 nm can generally be formed on the surface of the lithium ion sieve material. It can be understood that the particle size of the lithium ion sieve material does not change significantly before and after the modification.

[0098] According to the present invention, preferably, the mass ratio of the polyhydroxy polymer, the lithium ion sieve material and the coupling agent is 1: (0.1-5): (0.05-1.5), and more preferably 1: (3-5): (0.1-1.5). In this way, the lithium ion sieve powder material can be loaded on the polyvinyl alcohol skeleton more evenly and efficiently.

[0099] According to the present invention, preferably, the coupling conditions include: a temperature of 50-90°C (for example, 50°C, 60°C, 70°C, 80°C, 90°C), a time of 1-24h (for example, 1h, 3h, 5h, 8h, 10h, 12h, 15h, 18h, 20h, 22h, 24h), and a pH of 1-3 (for example, 1, 1.5, 2, 2.5, 3). The pH can be adjusted with hydrochloric acid.

[0100] When used, the polyhydroxy polymer is generally used in the form of an aqueous solution, and the concentration of the polyhydroxy polymer in the aqueous solution may be 8-16 wt %.

[0101] Preferably, after coupling, the method further comprises: aging and granulating the materials in sequence.

[0102] Preferably, the aging conditions include: temperature of 50-70°C and time of 0.2-2h.

[0103] Preferably, the granulation is performed to a particle size of 1-5 mm, more preferably 2-4 mm. The granulation can be performed in a granulator. The particle size of the material obtained by granulation may not be completely consistent, but may be within a range.

[0104] According to the present invention, preferably, the method further comprises: cross-linking the granulated product under the action of a cross-linking agent. It is understood that the cross-linking agent will cause the skeleton of the lithium adsorption material, ie, the polyhydroxy polymer, to be cross-linked.

[0105] According to the present invention, preferably, the cross-linking method is: immersing the granulated product in a cross-linking agent solution with a cross-linking agent concentration of 0.1-1wt% (for example, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%), the cross-linking temperature is 20-40°C (for example, 20°C, 25°C, 30°C, 35°C, 40°C), and the cross-linking time is 30-120min (for example, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min). Generally, the amount of the cross-linking agent solution can be 80-150ml relative to 1g of the granulated product.

[0106] After the coupling, the above cross-linking is performed, the combination of the polyhydroxy polymer and the lithium ion sieve material is stronger, the structure is more stable, and the prepared lithium adsorption material is more resistant to acid and alkali.

[0107] According to the present invention, preferably, the crosslinking agent is selected from at least one of aldehyde compounds, preferably selected from at least one of C1-C5 monoaldehydes and C1-C5 dialdehydes. It can be understood that the particle size of the material will not change significantly before and after crosslinking. The aldehyde group in the crosslinking agent can react with the hydroxyl group in the polyhydroxy polymer to form a crosslinked polyhydroxy polymer structure.

[0108] According to the present invention, preferably, the method further comprises: after cross-linking, pickling the cross-linked product. Before pickling, the material can be dried (can be oven dried) at 50-70°C for 18-36h, and then the material is cyclically pickled for 0.5-2h in an adsorption column using 0.05-0.3mol / L hydrochloric acid. The pickled material can be circulated once with deionized water for water washing. Pickling can replace the lithium ions on the lithium ion sieve material with hydrogen ions.

[0109] The present invention will be described in detail below through preparation examples.

[0110] In the following preparation examples, the cross-linked material is dried, acid-washed and washed with water in the following manner: the cross-linked material is dried in an oven at 60°C for 24 hours, then loaded into an adsorption column, and 0.1 mol / L HCl is circulated in the column for 1 hour. The acid-washed material is then circulated once with deionized water and washed with water.

[0111] Preparation Example 1

[0112] (1) Take powder Li 1.33 Mn 1.67O4 (with an average particle size of 300 μm) was mixed with a tannic acid aqueous solution (wherein the concentration of tannic acid was 0.1 mg / L) so that the mass ratio of the lithium ion sieve material to the polyphenol was 1:0.1. The mixture was stirred at room temperature for 2 h (300 rpm) and then centrifuged. The solid phase material was dried (temperature was 60 ° C, time was 8 h) to complete the modification of the lithium ion sieve material.

[0113] (2) A 15 wt % aqueous solution of polyvinyl alcohol (with a degree of alcoholysis of 88% and a weight average molecular weight of 89,000 g / mol) and the modified Li prepared in step (1) were prepared. 1.33 Mn 1.67 O4 powder was mixed and stirred evenly, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added to make the polyvinyl alcohol: modified Li 1.33 Mn 1.67 O4:γ-(2,3-epoxypropoxy)propyltrimethoxysilane (mass ratio) is 1:5:1.5, and the pH of the system is adjusted to 1 with 0.1 mol / L HCl, stirred at 70°C, coupled for 8 hours, and then placed in a 60°C oven for aging for 30 minutes, and then a semi-solidified product is obtained, which is extruded through an extruder to obtain a material with a particle size of 2-3 mm.

[0114] (3) The material obtained in step (2) is immersed in a formaldehyde aqueous solution having a formaldehyde concentration of 0.1 wt% (the amount of the crosslinking agent solution is 80 ml relative to 1 g of the granulated product) at 20° C. for 120 min to perform crosslinking.

[0115] The cross-linked material is dried, pickled and washed with water to obtain a product such as Figure 4 shown.

[0116] Preparation Example 2

[0117] (1) Take powder Li 1.33 Mn 1.67 O4 (with an average particle size of 250 μm) was mixed with a tannic acid aqueous solution (with a tannic acid concentration of 0.5 mg / L) so that the mass ratio of the lithium ion sieve material to the polyphenol was 1:0.3. The mixture was stirred at room temperature for 1 h (400 rpm) and then centrifuged. The solid phase material was dried (temperature of 60 ° C for 8 h) to complete the modification of the lithium ion sieve material.

[0118] (2) taking a polyvinyl alcohol aqueous solution (with a degree of alcoholysis of 88% and a weight average molecular weight of 89,000 g / mol) with a concentration of 13 wt % and the modified Li prepared in step (1); 1.33 Mn 1.67O4 powder was mixed and stirred evenly, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added to make the polyvinyl alcohol: modified Li 1.33 Mn 1.67 O4: γ-(2,3-epoxypropoxy)propyltrimethoxysilane (mass ratio) is 1:3:0.8, and the pH of the system is adjusted to 2 with 0.1 mol / L HCl, stirred at 50°C, coupled for 24 hours, and then placed in a 55°C oven for aging for 60 minutes, and then a semi-solidified product is obtained, which is extruded through an extruder to obtain a material with a particle size of 2-3 mm.

[0119] (3) The material obtained in step (2) is immersed in a formaldehyde aqueous solution having a formaldehyde concentration of 1 wt% (the amount of the crosslinking agent solution is 100 ml relative to 1 g of the granulated product) at 30° C. for 30 min to perform crosslinking.

[0120] Preparation Example 3

[0121] (1) Take powder Li 1.33 Mn 1.67 O4 (with an average particle size of 350 μm) was mixed with a tannic acid aqueous solution (wherein the concentration of tannic acid was 1 mg / L) so that the mass ratio of the lithium ion sieve material to the polyphenol was 1:0.08. The mixture was stirred at room temperature for 3 h (500 rpm) and then centrifuged. The solid phase material was dried (temperature was 60 ° C, time was 8 h) to complete the modification of the lithium ion sieve material.

[0122] (2) A 10 wt % aqueous solution of polyvinyl alcohol (with a degree of alcoholysis of 88% and a weight average molecular weight of 89,000 g / mol) and the modified Li prepared in step (1) were prepared. 1.33 Mn 1.67 O4 powder was mixed and stirred evenly, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added to make the polyvinyl alcohol: modified Li 1.33 Mn 1.67 O4: γ-(2,3-epoxypropoxy)propyltrimethoxysilane (mass ratio) is 1:3.5:0.1, and the pH of the system is adjusted to 3 with 0.1 mol / L HCl, stirred at 90°C, coupled for 1 hour, and then placed in a 70°C oven for aging for 120 minutes, and then a semi-solidified product is obtained. After extrusion through an extruder, a material with a particle size of 2-3 mm is obtained.

[0123] (3) The material obtained in step (2) is immersed in a formaldehyde aqueous solution having a formaldehyde concentration of 0.8 wt % (the amount of the crosslinking agent solution is 130 ml relative to 1 g of the granulated product) at 38° C. for 80 min to perform crosslinking.

[0124] Preparation Example 4

[0125] The method of Preparation Example 1 is followed, except that in step (1), tannic acid is replaced by tea polyphenols.

[0126] Preparation Example 5

[0127] The method of Preparation Example 1 is followed, except that in step (1), tannic acid is replaced by dopamine.

[0128] Preparation Example 6

[0129] The method of Preparation Example 1 was followed, except that the coupling agent was replaced with γ-mercaptopropyltriethoxysilane.

[0130] Preparation Example 7

[0131] The method of Preparation Example 1 was followed, except that in step (2), the coupling agent was replaced with 3-aminopropyltrimethoxysilane.

[0132] Preparation Example 8

[0133] The lithium adsorption material was prepared according to the method of Preparation Example 1, except that the modification in step (1) was not performed.

[0134] Preparation Example 9

[0135] The lithium adsorption material was prepared according to the method of Preparation Example 1, except that in step (2), γ-(2,3-epoxypropoxy)propyltrimethoxysilane was replaced by glutaraldehyde, and step (3) was not performed.

[0136] Preparation Example 10

[0137] The lithium adsorption material was prepared according to the method of Preparation Example 1, except that: the powder modification in step (1) was not performed; and in step (2), γ-(2,3-epoxypropoxy)propyltrimethoxysilane was replaced by glutaraldehyde.

[0138] Preparation Example 11

[0139] The lithium adsorption material was prepared according to the method of Preparation Example 1, except that in step (2), no coupling agent was used.

[0140] Preparation Example 12

[0141] The lithium adsorption material was prepared according to the method of Preparation Example 1, except that no polyvinyl alcohol was added in step (2) (ie, the polyvinyl alcohol aqueous solution in Preparation Example 1 was replaced with water of the same weight).

[0142] Preparation Example 13

[0143] The lithium adsorption material was prepared according to the method of Preparation Example 1, except that: Li 1.33 Mn 1.67O4 was replaced by LiCl·2Al(OH)3·nH2O (average particle size: 300 μm).

[0144] Test Case

[0145] Take the lithium adsorption material prepared in the above preparation example and perform the following measurements respectively:

[0146] Adsorption capacity determination:

[0147] Take 0.5g lithium adsorption material and 40ml lithium magnesium mixed solution (Li + The concentration is 100ppm, Mg 2+ Static adsorption is performed on a mixed solution of lithium chloride and magnesium chloride with a concentration of 2000ppm, pH = 10.0, alkaline conditions. During the adsorption process, the change of adsorption capacity over time is monitored, which is the kinetic curve (adsorption capacity-adsorption time). The adsorption kinetics reflects the speed of adsorption of the adsorbent.

[0148] After 24 h of static adsorption, the solid and liquid were separated, and the saturated adsorption capacity Q was calculated according to the following formula. Then, 0.5 M HCl was used for desorption for 24 h.

[0149]

[0150] Wherein, Q is the saturated adsorption capacity, in mg / g, reflecting the adsorption amount when the adsorption reaches equilibrium; C0 and C are the ion concentrations in the solution at the initial and saturated adsorption, in mg / L, respectively; V is the volume of the adsorption solution, in L; M is the mass of the granular adsorbent, in g. Ion chromatography (ICS-1100, DIONEX, America) was used to determine the ion concentration.

[0151] The lithium extraction efficiency is the ratio of the mass of lithium adsorbed by the adsorbent to the mass of lithium in the solution.

[0152] Selectivity coefficient It refers to the preference of the adsorbent for ion A when adsorbing ions A and B. The larger the value, the better the selectivity for A, which reflects the selectivity of the adsorbent for different ions. It is the distribution coefficient of the two ions (K d ) ratio.

[0153]

[0154]

[0155] In the above formula, C0 is the concentration of each ion in the solution before adsorption, mg / L; C is the concentration of each ion when adsorption is saturated, mg / L; V is the volume of the solution, mL; m is the mass of the adsorbent, g.

[0156] The stability of lithium adsorption material in recycling is characterized by dynamic adsorption. The specific method is: at a temperature of 40°C, the lithium adsorption material is filled in the adsorption column, the column volume is 1 fluidized bed, that is, 1BV (1 fluidized bed volume), dynamic adsorption is performed, 8BV of brine is injected, and the flow rate is 3BV / h through the pellets; after the adsorption is completed, 2BV of desorption liquid is used for desorption, and the flow rate is 1-8BV / h through the pellets for desorption. The pH of the injected brine is 12, and the pH of the desorption liquid is 3.

[0157] Table 1

[0158]

[0159] The inventors of the present invention also found that after 40 repetitions of adsorption and desorption using the products of Preparation Examples 1-6 and Preparation Example 13, the adsorption capacity of the products did not change significantly, and the mass loss ratio was less than 1%, indicating that the products prepared by the more preferred scheme of the present invention have a stable structure and good acid resistance. The mass loss ratio of Preparation Examples 9-10 is 2-5%. In addition, the Shore A hardness of the products of Preparation Examples 1-6 is 60-70, and the Shore A hardness of the products of Preparation Examples 9-10 is less than 20. The granules of Preparation Examples 9-10 are brittle and easy to break in a dry state, the granules of Preparation Example 11 have a loose structure and are difficult to shape, and the granules of Preparation Example 12 are dissolved in water, that is, the skeleton is broken, and the above-mentioned measurement cannot be performed. The above results show that the structure of the granulated product is stable and the powder is not easy to fall off after long-term use.

[0160] The inventors of the present invention also found that the time for the adsorbent to reach adsorption equilibrium in the products of Preparation Examples 1-6 and Preparation Example 13 is within 4 hours, and 90% of the adsorption capacity can be reached in 30 minutes. The product provided by the present invention has strong hydrophilicity, good water permeability, and can quickly exchange water and ions.

[0161] Test Example 2

[0162] The product of Preparation Example 1 and the modified Li 1.33 Mn 1.67 O4 and the polyvinyl alcohol used in Preparation Example 1 were characterized by Fourier transform infrared spectrometer (FT-IR, MAGNA-IR 550). The results are shown in Figure 1 .

[0163] Figure 1 It can be seen that the absorption peak of the lithium ion sieve material modified by tannic acid is at 3400 cm -1 The hydroxyl peak at 1637 cm -1 The C=C peak shows that the polyphenol modification is successful. -1The largest peak is -OH peak, 1733cm -1 ,2927cm -1 The IR absorption peak of the product of Preparation Example 1 is at 2927 cm -1 、3400cm -1 The peak of lithium ion sieve material modified by tannic acid (3400 cm -1 ) and the C=C characteristic peak of PVA (2927cm -1 ), and 1197cm -1 The characteristic peaks nearby are characteristic peaks of Si—O—C, indicating that the coupling agent successfully couples PVA and polyphenol-modified lithium ion sieve materials in the product of Preparation Example 1. Infrared characterization also found that in the products of Preparation Examples 1-8, the coupling agent also successfully couples PVA and polyphenol-modified lithium ion sieve materials.

[0164] The product of Preparation Example 1 and the modified Li 1.33 Mn 1.67 The XRD pattern of O4 is shown in Figure 2 It can be found that the characteristic peaks and peak spacing of the product of Preparation Example 1 are similar to those of Li 1.33 Mn 1.67 The O4 powders were basically similar and did not undergo significant changes, indicating that the prepared products had no effect on the composition of the lithium ion sieve material. The corresponding situations of Preparation Examples 2-6 and Preparation Example 13 were similar to those of Preparation Example 1.

[0165] The powders prepared in Preparation Examples 1-6 and Preparation Example 13 have good dispersibility. Taking the product of Preparation Example 1 as an example, the powders were observed by scanning electron microscopy (SEM, S-4800) (the results of the product of Preparation Example 1 are shown in Figure 3 ) It can be found that the electron microscope shows that there is an irregular porous structure in the particles, with a pore size between 2-5μm. The powder adsorbent is evenly dispersed and embedded in the skeleton with a microporous network. Such a structure can avoid powder leakage during long-term use, thereby ensuring the strength and stability of the product, so that the performance of the product will not change significantly after long-term use. As shown above, polyphenol modification increases compatibility and improves the dispersibility of lithium ion sieve materials on the product.

[0166] Test Example 3

[0167] Take the lithium adsorption material prepared in the above preparation example and perform the following measurements respectively:

[0168] The specific surface area and pore volume are determined by measuring the adsorption-desorption isotherm of lithium adsorbent material to N2 at 77K, and fitting to obtain the BET specific surface area and pore volume;

[0169] The average pore size was determined by scanning electron microscopy;

[0170] The water absorption rate A and the volume swelling rate P are determined by placing a lithium adsorption material with a mass of W0 and a volume of V0 in sufficient distilled water at 25°C. After 24 hours, the weight W1 and the volume V1 are taken out and measured. A = (W1-W0) / W0, in g / g; P = (V1-V0) / V0;

[0171] The mass content of lithium ion sieve material and framework relative to the mass of lithium adsorbent material is determined as follows:

[0172] For the products of Preparation Examples 1-8 and Preparation Example 13, the contents of Mn, Al, Si, C, and O elements were determined by X-ray photoelectron spectroscopy (XPS), and the mass of the lithium ion sieve was calculated based on the contents of Mn and Al, and the mass of the coupling agent was calculated based on the content of Si, and the remainder was the mass of the skeleton; for the products of Preparation Examples 9-10, the content of Mn was determined by X-ray photoelectron spectroscopy (XPS), and the mass of the lithium ion sieve was obtained based on the content of Mn, and the remainder was the mass of the skeleton.

[0173] The above results are shown in Table 2-3.

[0174] Table 2

[0175]

[0176]

[0177] Table 3

[0178]

[0179] The mass content of the lithium ion sieve material in Preparation Examples 4-7 is 71-72.5wt%, and the mass content of the skeleton is 14-15wt%.

[0180] The present invention will be described in detail below through examples. The composition of the lithium-containing oil field produced water used in the following examples is shown in Table 4.

[0181] In the following examples and comparative examples, the determination method of each ion concentration in water is ion chromatography (a method in which ionic substances are separated using an ion exchange resin with a low exchange capacity as a fixed relative, and the conductivity change of the effluent is continuously detected using a conductivity detector); the determination method of total organic carbon is differential determination (infrared rays of a certain wavelength can be selectively absorbed by carbon dioxide, and the intensity of infrared absorption by carbon dioxide within a certain concentration range is proportional to the concentration of carbon dioxide, so total carbon and inorganic carbon can be determined. The difference between total carbon and inorganic carbon is total organic carbon); the determination method of total dissolved solid is contact conductivity method (TDS value is indirectly reflected by conductivity);

[0182] The purity of lithium carbonate is determined by potentiometric titration (using hydrochloric acid as the titrant, the ion concentration changes continuously, causing the electrode potential to change accordingly; near the titration end point, the ion concentration changes suddenly, causing a sudden jump in the electrode potential, and the amount of lithium carbonate is calculated based on the amount of hydrochloric acid consumed).

[0183] The lithium extraction rate is calculated as follows: lithium mass in lithium carbonate / (volume of produced water from the oil field × lithium ion concentration).

[0184] In the following embodiments, the structure of the system used in bipolar membrane electrodialysis is as follows: between the anode chamber and the cathode chamber are bipolar membrane, acid chamber, monovalent ion selective anion membrane (a membrane of model APX-D purchased from ASTOM, Japan), desalination chamber, monovalent ion selective cation membrane (a membrane of model CXP-S purchased from ASTOM, Japan), alkali chamber, bipolar membrane, that is, bipolar membrane electrodialysis is a three-chamber system with the above structure, and the two sides are respectively connected to a titanium cathode plate and an anode plate coated with ruthenium, and the two polar plates are connected to a DC power supply. The bipolar membrane is purchased from Hangzhou Ke Rui Environmental Energy Technology Co., Ltd., and the model is BPX bipolar membrane.

[0185] Table 4

[0186]

[0187] Example 1

[0188] (1) The produced water 1 from the lithium-containing oil field was ultrafiltered, the ultrafiltration membrane (purchased from Jiarong Technology Co., Ltd., model VFU-030 tubular ultrafiltration membrane) had a molecular weight cutoff of 30,000 Da, the ultrafiltration temperature was 20° C., and the pressure was 0.25 MPa.

[0189] The ultrafiltration water (Li + The lithium adsorption material prepared in Preparation Example 13 (with a concentration of 33.5 mg / L) was contacted in an adsorption column, and the ultrafiltration product water was pumped into the adsorption column at a rate of 3 BV / h for adsorption at 30°C for 8 hours.

[0190] After the adsorption is completed, the lithium-poor ultrafiltrate is treated as wastewater in a centralized manner.

[0191] Pure water was used as a desorbent to desorb the lithium adsorbent material at a temperature of 30°C, a desorption flow rate of 3BV / h, and a time of 8h. The desorption solution was obtained, and Li + The concentration is 630mg / L, Na + The concentration is 160mg / L, K + The concentration is 40mg / L, Mg 2+ The concentration is 80mg / L, Ca 2+ The concentration is 5mg / L.

[0192] (2) The desorption liquid is pumped into the nanofiltration system. The nanofiltration membrane (purchased from DeLanmer, model RS10-50C) has a molecular weight cutoff of 300-500 Da, which allows monovalent salts to pass through and retains divalent and higher salts. The nanofiltration operating temperature is 35°C, the pressure is 4 MPa, the time is 6 hours, and a first-stage nanofiltration is used. The nanofiltration permeate and nanofiltration retentate are obtained.

[0193] In the nanofiltration permeate obtained, Li + The concentration is 705mg / L, Na + The concentration is 180mg / L, K + The concentration is 47mg / L, Mg 2+ The concentration is 15mg / L.

[0194] (3) The nanofiltration permeate was used as the forward osmosis treatment liquid, and the nanofiltration retentate was used as the forward osmosis draw liquid. The membrane was purchased from Shanghai Tongqin Environmental Protection Technology Co., Ltd., model HTICTAES, and the temperature was 20°C for 6 hours. The water molecules in the nanofiltration permeate continuously penetrated into the other side of the membrane. After the nanofiltration permeate was subjected to forward osmosis, forward osmosis concentrated water was obtained. The volume of the forward osmosis concentrated water was 0.5 times that of the nanofiltration permeate. After the nanofiltration retentate was subjected to forward osmosis, the forward osmosis dilute draw liquid was obtained.

[0195] Li in forward osmosis concentrated water + The concentration is 1405mg / L, Na + The concentration is 350mg / L, K + The concentration is 95mg / L, Mg 2+ The concentration is 31mg / L.

[0196] The lithium ion concentration in the forward osmosis dilute draw liquid is 46 mg / L, and the magnesium-lithium mass ratio is 0.8, which satisfies that the lithium ion concentration in the forward osmosis dilute draw liquid is 0.5 times higher than the lithium ion concentration in the lithium-containing brine after ultrafiltration, and the magnesium-lithium mass ratio in the forward osmosis dilute draw liquid does not exceed 40. The forward osmosis dilute draw liquid and the lithium-containing brine after ultrafiltration are mixed and the adsorption in step (1) is carried out together.

[0197] (4) The forward osmosis concentrate was pumped into a high-pressure reverse osmosis system (the membrane assembly used was purchased from DeLanmeyer, model PRO20-35), with the pressure controlled at 10 MPa, the temperature at 35°C, and the time for 6 h.

[0198] The high-pressure reverse osmosis concentrated water and high-pressure reverse osmosis fresh water are obtained. The TDS of the high-pressure reverse osmosis concentrated water is 65000mg / L, Li + The concentration is 3020mg / L, Na + The concentration is 750mg / L, K + The concentration is 205mg / L, Mg 2+ The concentration is 67mg / L.

[0199] (5) In the bipolar membrane electrodialysis system, high-pressure reverse osmosis concentrated water is used as the inlet water for the desalination chamber, and high-pressure reverse osmosis fresh water is used as the inlet water for the acid chamber and the alkali chamber. The operating voltage is 3V and the current density is 900A / m 2 , time 5h.

[0200] From the desalination chamber, the salt water (Li + The concentration is 0.31g / L), mixed with forward osmosis concentrated water, and then carried out high-pressure reverse osmosis together.

[0201] The HCl acid solution is obtained from the acid chamber and used as a desorbent for the lithium adsorbent material.

[0202] From the alkaline chamber, an alkaline solution containing LiOH is obtained, wherein Li + The concentration is 1.18mol / L.

[0203] (6) The alkaline solution containing LiOH is evaporated and crystallized at 100° C. to obtain a mixture of lithium hydroxide and an evaporation mother liquor. The mixture is centrifuged and filtered to obtain lithium hydroxide and an evaporation mother liquor, respectively.

[0204] The evaporation mother liquor and the nanofiltration retentate are mixed and used together as the forward osmosis draw liquid.

[0205] After lithium hydroxide was dissolved in water (the concentration of lithium hydroxide in the obtained solution was 103 g / L), the solution was contacted with carbon dioxide gas in a gas-liquid reactor at 25°C and reacted until the liquid phase pH value was 12.1. The precipitate was washed, filtered and dried to obtain lithium carbonate with a purity of 99.7% and a lithium extraction rate of 81%.

[0206] Example 2

[0207] (1) The produced water 2 containing lithium oil field was ultrafiltered, the ultrafiltration membrane (purchased from Jiarong Technology Co., Ltd., model VFU-030 tubular ultrafiltration membrane) had a molecular weight cutoff of 30000Da, the ultrafiltration temperature was 22°C, and the pressure was 0.24MPa.

[0208] The ultrafiltration water (Li + The lithium adsorption material prepared in Preparation Example 13 (with a concentration of 35 mg / L) was contacted in an adsorption column, and the ultrafiltration product water was pumped into the adsorption column at a rate of 2 BV / h and adsorbed at 10°C for 6 hours.

[0209] After the adsorption is completed, the lithium-poor ultrafiltrate is treated as wastewater in a centralized manner.

[0210] Pure water was used as a desorbent to desorb the lithium adsorbent material at a desorption rate of 2 BV / h, a temperature of 23°C, and a time of 6 hours. The desorption solution was obtained, and Li +The concentration is 420mg / L, Na + The concentration is 170mg / L, K + The concentration is 35mg / L, Mg 2+ The concentration is 74mg / L, Ca 2+ The concentration is 5mg / L.

[0211] (2) The desorption liquid is pumped into the nanofiltration system, and the nanofiltration membrane (purchased from Delanmer, model RS10-35C) allows monovalent salts to pass through and intercepts divalent and higher salts, with a molecular weight cutoff of 50-100 Da. The nanofiltration operating temperature is 15° C., the pressure is 3 MPa, the time is 5.5 h, and a first-stage nanofiltration is used to obtain nanofiltration permeate and nanofiltration retentate.

[0212] In the nanofiltration permeate obtained, Li + The concentration is 470mg / L, Na + The concentration is 190mg / L, K + The concentration is 39mg / L, Mg 2+ The concentration is 14mg / L.

[0213] (3) The nanofiltration permeate was used as the forward osmosis treatment liquid, and the nanofiltration retentate was used as the forward osmosis draw liquid. The membrane was purchased from Shanghai Tongqin Environmental Protection Technology Co., Ltd., model HTICTAES, and the temperature was 15°C for 8 hours. The water molecules in the nanofiltration permeate continuously penetrated into the other side of the membrane. After the nanofiltration permeate was subjected to forward osmosis, forward osmosis concentrated water was obtained. The volume of the forward osmosis concentrated water was 0.4 times that of the nanofiltration permeate. After the nanofiltration retentate was subjected to forward osmosis, the forward osmosis dilute draw liquid was obtained.

[0214] Li in forward osmosis concentrated water + The concentration is 1170mg / L, Na + The concentration is 460mg / L, K + The concentration is 98mg / L, Mg 2+ The concentration is 35mg / L.

[0215] The lithium ion concentration in the forward osmosis dilute draw liquid is 48 mg / L, and the magnesium-to-lithium mass ratio is 0.96, which satisfies that the lithium ion concentration in the forward osmosis dilute draw liquid is 0.5 times higher than the lithium ion concentration in the lithium-containing brine after ultrafiltration, and the magnesium-to-lithium mass ratio in the forward osmosis dilute draw liquid does not exceed 40. The forward osmosis dilute draw liquid and the lithium-containing brine after ultrafiltration are mixed and the adsorption in step (1) is carried out together.

[0216] (4) The forward osmosis concentrate was pumped into a high-pressure reverse osmosis system (the membrane assembly used was purchased from DeLanmeyer, model PRO10-50), with the pressure controlled at 8 MPa, the temperature at 15°C, and the time for 5 h.

[0217] The high-pressure reverse osmosis concentrated water and high-pressure reverse osmosis fresh water are obtained. The TDS of the high-pressure reverse osmosis concentrated water is 22700 mg / L, Li + The concentration is 2460mg / L, Na + The concentration is 965mg / L, K + The concentration is 210mg / L, Mg 2+ The concentration is 72mg / L.

[0218] (5) In the bipolar membrane electrodialysis system, high-pressure reverse osmosis concentrated water is used as the inlet water for the desalination chamber, and high-pressure reverse osmosis fresh water is used as the inlet water for the acid chamber and the alkali chamber. The operating voltage is 2V and the current density is 600A / m 2 , time 6h.

[0219] From the desalination chamber, the salt water (Li + The concentration is 0.28g / L), mixed with forward osmosis concentrated water, and then carried out high-pressure reverse osmosis together.

[0220] The HCl acid solution is obtained from the acid chamber and used as a desorbent for the lithium adsorbent material.

[0221] From the alkaline chamber, an alkaline solution containing LiOH is obtained, wherein Li + The concentration is 0.96mol / L.

[0222] (6) The alkaline solution containing LiOH is evaporated and crystallized at 90° C. to obtain a mixture of lithium hydroxide and an evaporation mother liquor. The mixture is centrifuged and filtered to obtain lithium hydroxide and an evaporation mother liquor, respectively.

[0223] The evaporation mother liquor and the nanofiltration retentate are mixed and used together as the forward osmosis draw liquid.

[0224] After lithium hydroxide was dissolved in water (the concentration of lithium hydroxide in the obtained solution was 99 g / L), the solution was contacted with carbon dioxide gas in a gas-liquid reactor at 25°C and reacted until the liquid phase pH value was 11.8. The precipitate was washed, filtered and dried to obtain lithium carbonate with a purity of 98.8% and a lithium extraction rate of 79%.

[0225] Example 3

[0226] (1) The produced water 3 from the lithium-containing oil field was ultrafiltered, the ultrafiltration membrane (purchased from Jiarong Technology Co., Ltd., model VFU-030 tubular ultrafiltration membrane) had a molecular weight cutoff of 30,000 Da, the ultrafiltration temperature was 17° C., and the pressure was 0.18 MPa.

[0227] The ultrafiltration water (Li +The lithium adsorption material prepared in Preparation Example 13 (with a concentration of 34.5 mg / L) was contacted in an adsorption column, and the ultrafiltration product water was pumped into the adsorption column at a rate of 3 BV / h for adsorption at 20°C for 7 hours.

[0228] After the adsorption is completed, the lithium-poor ultrafiltrate is treated as wastewater in a centralized manner.

[0229] Pure water was used as a desorbent to desorb the lithium adsorbent material at a desorption rate of 3 BV / h, a temperature of 24°C, and a time of 7 hours. The desorption solution was obtained, and Li + The concentration is 545mg / L, Na + The concentration is 155mg / L, K + The concentration is 37mg / L, Mg 2+ The concentration is 76mg / L, Ca 2+ The concentration is 5mg / L.

[0230] (2) The desorption liquid is pumped into the nanofiltration system, and the nanofiltration membrane (purchased from DeLanmeier, model RS10-35C) allows monovalent salts to pass through and intercepts divalent and higher salts, with a molecular weight cutoff of 50-100 Da. The nanofiltration operating temperature is 25° C., the pressure is 4 MPa, the time is 5 h, and a first-stage nanofiltration is used. The nanofiltration permeate and nanofiltration retentate are obtained.

[0231] In the nanofiltration permeate obtained, Li + The concentration is 610mg / L, Na + The concentration is 175mg / L, K + The concentration is 41mg / L, Mg 2+ The concentration is 16mg / L.

[0232] (3) The nanofiltration permeate was used as the forward osmosis treatment liquid, and the nanofiltration retentate was used as the forward osmosis draw liquid. The membrane was purchased from Shanghai Tongqin Environmental Protection Technology Co., Ltd., model HTICTAES, and the temperature was 10°C for 7 hours. The water molecules in the nanofiltration permeate continuously penetrated into the other side of the membrane. After the nanofiltration permeate was subjected to forward osmosis, forward osmosis concentrated water was obtained. The volume of the forward osmosis concentrated water was 0.4 times that of the nanofiltration permeate. After the nanofiltration retentate was subjected to forward osmosis, the forward osmosis dilute draw liquid was obtained.

[0233] Li in forward osmosis concentrated water + The concentration is 1210mg / L, Na + The concentration is 355mg / L, K + The concentration is 80mg / L, Mg 2+ The concentration is 30mg / L.

[0234] The lithium ion concentration in the forward osmosis dilute draw liquid is 52 mg / L, and the magnesium-to-lithium mass ratio is 1.2, which satisfies that the lithium ion concentration in the forward osmosis dilute draw liquid is 0.5 times higher than the lithium ion concentration in the lithium-containing brine after ultrafiltration, and the magnesium-to-lithium mass ratio in the forward osmosis dilute draw liquid does not exceed 40. The forward osmosis dilute draw liquid and the lithium-containing brine after ultrafiltration are mixed and the adsorption in step (1) is carried out together.

[0235] (4) The forward osmosis concentrate was pumped into a high-pressure reverse osmosis system (the membrane assembly used was purchased from DeLanmeyer, model PRO20-35), with the pressure controlled at 9 MPa, the temperature at 25°C, and the time for 4 h.

[0236] The high pressure reverse osmosis concentrated water and high pressure reverse osmosis fresh water are obtained. The TDS of the high pressure reverse osmosis concentrated water is 27890 mg / L, Li + The concentration is 2910mg / L, Na + The concentration is 850mg / L, K + The concentration is 193mg / L, Mg 2+ The concentration is 74mg / L.

[0237] (5) In the bipolar membrane electrodialysis system, high-pressure reverse osmosis concentrated water is used as the inlet water for the desalination chamber, and high-pressure reverse osmosis fresh water is used as the inlet water for the acid chamber and the alkali chamber. The operating voltage is 3V and the current density is 900A / m 2 , time 5h.

[0238] From the desalination chamber, the salt water (Li + The concentration is 0.27g / L), mixed with forward osmosis concentrated water, and then carried out high-pressure reverse osmosis together.

[0239] The HCl acid solution is obtained from the acid chamber and used as a desorbent for the lithium adsorbent material.

[0240] From the alkaline chamber, an alkaline solution containing LiOH is obtained, wherein Li + The concentration is 1.15mol / L.

[0241] (6) The alkaline solution containing LiOH is evaporated and crystallized at 80° C. to obtain a mixture of lithium hydroxide and an evaporation mother liquor. The mixture is centrifuged and filtered to obtain lithium hydroxide and an evaporation mother liquor, respectively.

[0242] The evaporation mother liquor and the nanofiltration retentate are mixed and used together as the forward osmosis draw liquid.

[0243] After lithium hydroxide was dissolved in water (the concentration of lithium hydroxide in the obtained solution was 105 g / L), the solution was contacted with carbon dioxide gas in a gas-liquid reactor at 25°C and reacted until the liquid phase pH value was 11.9. The precipitate was washed, filtered and dried to obtain lithium carbonate with a purity of 99.5% and a lithium extraction rate of 78%.

[0244] Example 4

[0245] The oilfield produced water 1 was treated according to the method of Example 1, except that the lithium adsorption material was replaced by the lithium adsorption material prepared in Preparation Example 2. A 0.5 mol / L hydrochloric acid solution was used as a desorbent to desorb the lithium adsorption material, and the other steps were exactly the same as in Example 1 to obtain a lithium carbonate product with a purity of 99.5% and a lithium extraction rate of 78.3%.

[0246] Example 5

[0247] The oilfield produced water 1 was treated according to the method of Example 1, except that the lithium adsorption material was replaced by the lithium adsorption material prepared in Preparation Example 5. A 0.4 mol / L hydrochloric acid solution was used as a desorbent to desorb the lithium adsorption material. The other steps were exactly the same as in Example 1. The purity was 99.3%, and a lithium carbonate product was obtained. The lithium extraction rate was 78.2%.

[0248] Example 6

[0249] The oilfield produced water 1 was treated according to the method of Example 1, except that the lithium adsorption material was replaced by the lithium adsorption material prepared in Preparation Example 6. A 0.3 mol / L hydrochloric acid solution was used as a desorbent to desorb the lithium adsorption material, and the other steps were exactly the same as in Example 1 to obtain a lithium carbonate product with a purity of 98.9% and a lithium extraction rate of 77.4%.

[0250] Example 7

[0251] The oilfield produced water 1 was treated according to the method of Example 1, except that the lithium adsorption material was replaced by the lithium adsorption material prepared in Preparation Example 7. A 0.6 mol / L hydrochloric acid solution was used as a desorbent to desorb the lithium adsorption material, and the other steps were exactly the same as in Example 1 to obtain a lithium carbonate product with a purity of 98.5% and a lithium extraction rate of 77.1%.

[0252] Example 8

[0253] The oilfield produced water 1 was treated according to the method of Example 1, except that the lithium adsorption material was replaced by the lithium adsorption material prepared in Preparation Example 8. A 0.35 mol / L hydrochloric acid solution was used as a desorbent to desorb the lithium adsorption material, and the other steps were exactly the same as in Example 1 to obtain a lithium carbonate product with a purity of 98.8% and a lithium extraction rate of 77.3%.

[0254] Comparative Example 1

[0255] The oilfield produced water 1 was treated according to the method of Example 1, except that the desorption liquid was not subjected to nanofiltration but directly entered the forward osmosis system, and finally a lithium carbonate product was obtained with a purity of 83.4% and a lithium extraction rate of 68.4%.

[0256] According to the above results, it can be seen that the method provided by the present invention can extract lithium with a higher yield and purity from materials with significantly lower lithium concentrations, and is particularly suitable for low-grade oilfield produced water. The process is simple, the operating cost is low, the lithium extraction cycle is short, the continuity is strong, and no additional pollution is generated.

[0257] It can be found from Examples 1 and 4-8 that when the method for extracting lithium provided by the present invention is used, in combination with the lithium adsorption material with a higher adsorption capacity which is more preferably used in the present invention, when the lithium ion content in the produced water of the oil field is certain, the present invention requires less lithium adsorption material, and also saves production costs to a certain extent.

[0258] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing lithium carbonate using lithium-containing brine, characterized in that: The method includes: (1) using a lithium adsorption material to adsorb Li from lithium-containing brine, and desorbing the lithium adsorption material to obtain a desorption solution; (2) subjecting the desorbed liquid to nanofiltration to obtain a nanofiltration permeate and a nanofiltration retentate; (3) using the nanofiltration permeate as a forward osmosis treated liquid to perform forward osmosis to obtain forward osmosis concentrated water; (4) subjecting the forward osmosis concentrated water to high-pressure reverse osmosis to obtain high-pressure reverse osmosis concentrated water and high-pressure reverse osmosis fresh water; (5) subjecting the high-pressure reverse osmosis concentrated water and the high-pressure reverse osmosis fresh water to bipolar membrane electrodialysis to obtain alkali solution in an alkali chamber; (6) Lithium hydroxide is extracted from the alkali solution, and lithium hydroxide is reacted with carbon dioxide to obtain lithium carbonate.

2. The method according to claim 1, wherein: Before performing step (1), the method further comprises: ultrafiltration of the lithium-containing brine; Preferably, the ultrafiltration conditions include: ultrafiltration pressure of 0.1-0.5 MPa and temperature of 15-35°C.

3. The method according to claim 1, wherein: The water quality of the lithium-containing brine includes: Li + The concentration is 20-80 mg / L, and the concentration of alkaline earth metal ions is 1200-1500 mg / L; Preferably, the lithium-containing brine is produced water from a lithium-containing oil field; Preferably, the water quality of the produced water from the lithium-containing oil field includes: Li + The concentration is 40-65mg / L, Na + The concentration is 3300-3600mg / L, K + The concentration is 280-320mg / L, Mg 2+ The concentration is 1200-1350mg / L, Ca 2+ The concentration is 40-55 mg / L, Cl - Concentration is 8700-9100mg / L, SO4 2- The concentration is 1700-2100 mg / L, the pH is 7-8.5, the total organic matter is 600-1600 mg / L, and the total dissolved solid is 35000-38000 mg / L.

4. The method according to claim 1 or 3, wherein: In step (1), the operating conditions of adsorption include: adsorption flow rate 2-3.2 BV / h, adsorption temperature 10-32° C., and adsorption time 6-8 h; And / or, the operating conditions of desorption include: desorption flow rate of desorbent 2-3.2 BV / h, temperature 10-32° C., time 6-8 h; Preferably, the desorbent is selected from water or an inorganic acid solution.

5. The method according to claim 1 or 3, wherein: In step (2), the nanofiltration operating conditions include: temperature of 15-35° C., operating pressure of 2-5 MPa, and time of 5-6 h; Preferably, the molecular weight cut-off of the nanofiltration membrane used in nanofiltration is 50-500Da.

6. The method according to claim 1 or 3, wherein: The operating conditions of the forward osmosis include: temperature 10-30°C, time 3-12h.

7. The method according to claim 1 or 2, wherein: In step (4), the operating conditions of the high-pressure reverse osmosis include: temperature of 12-36° C., operating pressure of 7.5-10 MPa, and time of 4-6 h.

8. The method according to claim 1 or 2, wherein: In step (5), the operation mode of the bipolar membrane electrodialysis includes: using high-pressure reverse osmosis concentrated water as the desalination chamber inlet water, and using high-pressure reverse osmosis fresh water as the acid chamber and alkali chamber inlet water, the operating voltage is 2-3V, and the current density is 600-900A / m 2 , time 5-7h.

9. The method according to claim 1 or 2, wherein: Methods for extracting lithium hydroxide from alkali solution include: evaporating and crystallizing the alkali solution; And / or, the method of reacting lithium hydroxide with carbon dioxide includes: dissolving lithium hydroxide in a solvent, contacting with carbon dioxide at 23-27° C., and reacting until the pH value of the liquid phase reaches 11.5-12.

5.

10. The method according to claim 1 or 2, wherein: The lithium adsorption material comprises a skeleton and a lithium ion sieve material dispersed in the skeleton, wherein the lithium ion sieve material is connected to the skeleton via a coupling agent, and the skeleton is provided by a cross-linked or non-cross-linked polyhydroxy polymer; Preferably, the average particle size of the lithium adsorption material is 1-5 mm, preferably 2-4 mm; Preferably, the mass content of the lithium ion sieve material is 10-80wt%, preferably 68-77wt%, relative to the mass of the lithium adsorption material; Preferably, the specific surface area of ​​the lithium adsorption material is 10-500m 2 / g, preferably 10-45m 2 / g; Preferably, the average pore size of the lithium adsorption material is 0.1-10 μm, preferably 2-5 μm; Preferably, the pore volume of the lithium adsorption material is 10-100m 3 / g, preferably 50-85m 3 / g; Preferably, at 25° C., the water absorption rate of the lithium adsorption material to pure water is 0.1-2 g / g, and the volume swelling rate is 2-10%.

11. The method according to claim 10, wherein: The lithium ion sieve material is selected from titanium and / or manganese lithium ion sieve materials; and / or, the average particle size of the lithium ion sieve material is 10-500 μm; and / or, the polyhydroxy polymer is selected from at least one of polyvinyl alcohol, chitosan, polyethylene glycol and carboxymethyl cellulose, preferably polyvinyl alcohol; And / or, the coupling agent is selected from silane coupling agents; Preferably, the silane coupling agent is selected from at least one of a mercapto-containing silane coupling agent and an epoxy-containing silane coupling agent, preferably an epoxy-containing silane coupling agent; More preferably, the epoxy-containing silane coupling agent is selected from at least one of γ-(2,3-glycidoxypropyl)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(2,3-glycidoxypropyl)methyldiethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

12. The method according to claim 10, wherein: The lithium ion sieve material is a lithium ion sieve material modified by polyphenol; Preferably, the polyphenol modification method comprises: mixing a lithium ion sieve material and polyphenol to modify the lithium ion sieve material; Preferably, the mixing is performed in a solution environment; Preferably, the mass ratio of lithium ion sieve material to polyphenol is 1:(0.08-0.3); Preferably, the mixing time is 1-3h; Preferably, the polyphenol is selected from at least one of tannic acid, tea polyphenols, dopamine, eriodictyol, epicatechin, luteolin, kaempferol, myricetin and genistein, preferably at least one of tannic acid, tea polyphenols and dopamine.

Images