Modified lithium extraction adsorbent, and preparation method therefor and use thereof

Abstract

Provided are a modified lithium extraction adsorbent, and a preparation method therefor and a use thereof. The modified lithium extraction adsorbent comprises an aluminum-based adsorbent and microcapsules arranged on the surface of the aluminum-based adsorbent, wherein the microcapsules include curing agent microcapsules and adhesive microcapsules. The microcapsules in the modified lithium extraction adsorbent can fill cracks when the lithium extraction adsorbent fractures due to expansion, thereby reducing the dissolution loss of the adsorbent.

Description

A modified lithium extraction adsorbent and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of lithium extraction from salt lakes and relates to a modified lithium extraction adsorbent and a preparation method and application thereof. Background Art

[0002] Lithium is the lightest metallic element in the world, and its unique properties are attracting increasing attention to it and its compounds. Lithium and its compounds are used in industries such as medicine, polymers, new materials, and new energy batteries, making them a strategic resource of vital importance to the national economy and national defense. In recent years, lithium extraction from salt lakes has become one of the most important methods for obtaining lithium resources.

[0003] Methods for extracting lithium from salt lakes can be categorized into precipitation, extraction, membrane, and adsorption. However, precipitation is inefficient, and extraction equipment is susceptible to corrosion and loss of the extractant. Full membrane and adsorption are emerging technologies in the salt lake lithium extraction industry, offering advantages such as simplicity and minimal pollution. However, the full membrane method consumes a lot of membrane and is prone to contamination, increasing the cost of extraction. The adsorption method is challenging due to the preparation of the lithium adsorbent, but overall, the adsorption method is the most competitive of the available options.

[0004] The active ingredients of existing lithium adsorbents such as aluminum, manganese, and titanium are inorganic powders. Direct use has the disadvantages of poor permeability and high dissolution loss, so the inorganic adsorbents need to be granulated. Common molding methods include granulation and film making, among which granulation is generally divided into physical blending and chemical reaction granulation. Physical blending granulation is the process of uniformly mixing an inorganic adsorbent with an inert binder and then molding. Chemical reaction granulation is the process of uniformly mixing an inorganic adsorbent with an active binder and then reacting and solidifying.

[0005] CN115155528A discloses a method for preparing a granular aluminum salt adsorbent for lithium extraction with a high adsorption capacity. The method comprises: (1) preparing a lithium-intercalating aluminum salt precursor slurry by uniformly mixing an aluminum source, a lithium source, and water, and then adding an alkaline solution to adjust the pH to obtain a lithium-intercalating aluminum salt precursor slurry; (2) integrally granulating the lithium-intercalating aluminum salt precursor slurry; and (3) drying and rinsing the granulated adsorbent to obtain a granular aluminum salt adsorbent for lithium extraction.

[0006] CN110743516A discloses a granulation technology suitable for adsorbents used in lithium extraction from brine. The granulation method comprises the following steps: 1) mixing a polymer and a latent solvent in a certain proportion; 2) adding a certain amount of stabilizer to the paste from step 1) and kneading the mixture evenly to obtain a granulated agent; 3) kneading a certain amount of lithium adsorbent powder and the granulated agent to obtain a uniformly mixed mixture; and 4) granulating the mixture from step 3 in a granulator to obtain finished adsorbent particles with a fixed particle shape.

[0007] The granulated adsorbent can generally improve the cyclic stability of the adsorbent, but the granulated adsorbent will undergo a certain volume expansion during the lithium extraction process due to the insertion and extraction of lithium ions, causing cracks in the adsorbent and thus causing dissolution of the adsorbent.

[0008] Summary of the Invention

[0009] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0010] The purpose of the present disclosure is to provide a modified lithium extraction adsorbent, a preparation method and application thereof. The microcapsules in the modified lithium extraction adsorbent described in the present disclosure can fill cracks when the lithium extraction adsorbent ruptures due to expansion, thereby reducing adsorbent dissolution loss.

[0011] To achieve this purpose, the present disclosure adopts the following technical solutions:

[0012] In a first aspect, the present disclosure provides a modified lithium extraction adsorbent, which includes an aluminum-based adsorbent and microcapsules arranged on the surface of the aluminum-based adsorbent, wherein the microcapsules include curing agent microcapsules and binder microcapsules.

[0013] The present invention sets microcapsules on the surface of the aluminum-based adsorbent. When the adsorbent particles crack during the circulation process, the microcapsules rupture, and the binder that can be solidified in water flows out and reacts with the curing agent to fill the cracks, reduce the dissolution loss of the adsorbent, and improve the recyclability of the adsorbent.

[0014] In one embodiment, the curing agent microcapsules include an underwater curing agent and a curing composite shell;

[0015] In one embodiment, the cured composite shell comprises urea-formaldehyde resin.

[0016] In one embodiment, the underwater curing agent includes any one of T31 curing agent, JA-IS curing agent, I965 curing agent, 810 curing agent or P117 curing agent, or a combination of at least two thereof;

[0017] In one embodiment, the binder microcapsule comprises a liquid epoxy resin core and a bonding composite shell disposed on the surface of the liquid epoxy resin core;

[0018] In one embodiment, the bonded composite shell comprises urea-formaldehyde resin.

[0019] In one embodiment, the median particle size D50 of the curing agent microcapsules and the binder microcapsules is independently 100-300 μm, for example, 100 μm, 150 μm, 200 μm, 250 μm or 300 μm.

[0020] In one embodiment, based on the mass of the modified lithium extraction adsorbent being 100%, the mass fraction of the microcapsules is 0.5-2%, for example, 0.5%, 0.8%, 1%, 1.5% or 2%.

[0021] In one embodiment, the mass ratio of the curing agent microcapsules to the binder microcapsules is (0.3-1.5):1, for example: 0.3:1, 0.5:1, 1:1, 1.2:1 or 1.5:1.

[0022] In one embodiment, the modified lithium extraction adsorbent further comprises a binder.

[0023] In one embodiment, the binder comprises polyurethane.

[0024] In a second aspect, the present disclosure provides a method for preparing the modified lithium extraction adsorbent as described in the first aspect, the preparation method comprising the following steps:

[0025] The urea-formaldehyde resin prepolymer solution, the surfactant solution and the binder dilution solution are mixed, heated and stirred, and then acid is added to adjust the pH to react to obtain binder microcapsules;

[0026] The urea-formaldehyde resin prepolymer solution, the surfactant solution and the curing agent dilution solution are mixed, heated and stirred, and then acid is added to adjust the pH to react to obtain curing agent microcapsules;

[0027] An aluminum-based adsorbent, a binder microcapsule, a curing agent microcapsule, a binder and a solvent are mixed to obtain a mixed solution, and the mixed solution is granulated to obtain the modified lithium extraction adsorbent.

[0028] There is no special requirement for the preparation order of the binder microcapsules and curing agent microcapsules disclosed in the present invention. The binder microcapsules can be prepared first for later use, or the curing agent microcapsules can be prepared first for later use and then used when preparing the modified lithium extraction adsorbent.

[0029] In one embodiment, the urea-formaldehyde resin prepolymer is prepared by the following method:

[0030] The urea and formaldehyde solutions are mixed to prepare a mixed solution, and after mixing until the urea is completely dissolved, triethanolamine is added dropwise to adjust the pH of the mixed solution. The solution is stirred and refluxed in a water bath to obtain a urea-formaldehyde resin prepolymer solution.

[0031] In one embodiment, the molar ratio of urea to formaldehyde in the formaldehyde solution is 1:(1.4-1.6), for example, 1:1.4, 1:1.45, 1:1.5, 1:1.55 or 1:1.6.

[0032] In one embodiment, the pH of the mixed solution is 8 to 9, for example, 8, 8.2, 8.5, 8.8 or 9.

[0033] In one embodiment, the temperature of the water bath reflux stirring reaction is 60-80°C, for example, 60°C, 65°C, 70°C, 75°C or 80°C.

[0034] In one embodiment, the reaction time of the water bath reflux stirring reaction is 1 to 3 hours, for example: 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.

[0035] In one embodiment, the mass concentration of the surfactant solution is 0.3-0.8%, for example, 0.3%, 0.4%, 0.5%, 0.6% or 0.8%.

[0036] In one embodiment, the surfactant includes any one of sodium oleate, sodium stearate, sodium laurate or sodium dodecylbenzene sulfonate, or a combination of at least two thereof.

[0037] In one embodiment, the binder dilution solution is prepared by the following method:

[0038] The liquid epoxy resin is mixed with the diluent, and then subjected to ultrasonication and then heated in a water bath for reaction to obtain the adhesive dilution solution.

[0039] In one embodiment, the mass ratio of the liquid epoxy resin to the diluent is 1:(0.1-0.2), for example: 1:0.1, 1:0.12, 1:0.15, 1:0.18 or 1:0.2, etc.

[0040] The present disclosure improves the fluidity of the binder in the microcapsule by adding a certain diluent, but too much diluent will reduce the viscosity.

[0041] In one embodiment, the curing agent dilution is prepared by the following method:

[0042] The curing agent, coupling agent and diluent are mixed, subjected to ultrasonic treatment and then heated in a water bath for reaction to obtain the curing agent dilution solution.

[0043] In one embodiment, the coupling agent includes γ-aminopropyltriethoxysilane (KH-550) and / or γ-glycidoxypropyltrimethoxysilane (KH560).

[0044] In one embodiment, the diluent includes n-butyl glycidyl ether, ethylene glycol butyl ether, or benzyl glycidyl ether.

[0045] In one embodiment, during the preparation of the binder dilution solution and the curing agent dilution solution, the ultrasonication time is independently 30 to 60 minutes, for example, 30 minutes, 35 minutes, 40 minutes, 50 minutes or 60 minutes.

[0046] In one embodiment, during the preparation of the binder dilution and the curing agent dilution, the temperature of the water bath heating reaction is independently 40-50°C, for example, 40°C, 42°C, 45°C, 48°C or 50°C.

[0047] In one embodiment, during the preparation of the binder dilution solution and the curing agent dilution solution, the water bath heating reaction time is independently 0.5 to 1 h, for example, 0.5 h, 0.6 h, 0.8 h, 0.9 h or 1 h.

[0048] In one embodiment, during the preparation of the binder microcapsules and the curing agent capsules, the heating and stirring speeds are independently 500 to 1000 rpm, for example, 500 rpm, 600 rpm, 800 rpm, 900 rpm or 1000 rpm.

[0049] During the preparation of the binder microcapsules and curing agent capsules, the speed of heating and stirring will affect the coating effect of the capsules themselves (the capsules are core-shell structures). If the rotation speed is too slow, the core droplets will be large and difficult to be completely coated. The particles that are not completely coated will agglomerate, further increasing the particles, reducing the proportion of the microcapsule core, and affecting the repair effect. The extent to which the droplet size can be reduced by continuously increasing the rotation speed is limited.

[0050] In one embodiment, during the preparation of the binder microcapsules and curing agent capsules, the heating and stirring temperatures are independently 40-50°C, for example, 40°C, 42°C, 45°C, 48°C or 50°C.

[0051] In one embodiment, during the preparation of the binder microcapsules and the curing agent capsules, the heating and stirring time is independently 30 to 60 minutes, for example, 30 minutes, 35 minutes, 40 minutes, 50 minutes or 60 minutes.

[0052] In one embodiment, during the preparation of the binder microcapsules and the curing agent capsules, acid is added to adjust the pH to be independently 1.8 to 2.2, for example, 1.8, 1.9, 2, 2.1 or 2.2.

[0053] In one embodiment, during the preparation of the binder microcapsules and the curing agent capsules, the reaction temperature is independently 40-60°C, for example, 40°C, 45°C, 50°C, 55°C or 60°C.

[0054] During the preparation of the binder microcapsules and curing agent capsules, the reaction temperature controls the synthesis rate of the urea-formaldehyde resin. If the temperature is too low, the reaction rate is slow and the efficiency is low; if the temperature is too high, the urea-formaldehyde resin is generated too quickly and agglomerates before attaching to the surface of the inner core droplets, affecting the formation of the capsule shell and thus affecting the repair effect.

[0055] In one embodiment, during the preparation of the binder microcapsules and the curing agent capsules, the reaction time is independently 2 to 5 hours, for example, 2 hours, 2.5 hours, 3 hours, 4 hours or 5 hours.

[0056] In one embodiment, the mass ratio of the aluminum-based adsorbent to the binder is 1:(0.2-0.8), for example: 1:0.2, 1:0.3, 1:0.5, 1:0.6 or 1:0.8, etc.

[0057] In one embodiment, the solvent comprises ethyl acetate.

[0058] In one embodiment, the mass ratio of the solvent to the binder is (2-3):1, for example: 2:1, 2.2:1, 2.5:1, 2.8:1 or 3:1, etc.

[0059] In one embodiment, the mass fraction of the microcapsules in the mixed solution is 0.5-1.5%, for example, 0.5%, 0.8%, 1%, 1.2% or 1.5%.

[0060] In one embodiment, the granulation process includes liquid phase solidification granulation and / or extrusion granulation, and liquid phase solidification granulation is optional.

[0061] In one embodiment, the liquid phase solidification granulation includes: dissolving carboxymethyl cellulose and propylene diamine in saturated salt water to form a uniform solution, slowly adding the mixed solution to the uniform solution, adjusting the stirring rate to 200-500 rpm (for example: 200 rpm, 250 rpm, 300 rpm, 400 rpm or 500 rpm, etc.), and obtaining spherical particles with a particle size of 0.5-2 mm (for example: 0.5 mm, 0.8 mm, 1 mm, 1.5 mm or 2 mm, etc.), and curing at 30-60°C (for example: 30°C, 35°C, 40°C, 50°C or 60°C, etc.), filtering and washing to obtain the modified lithium extraction adsorbent.

[0062] In a third aspect, the present disclosure provides an application of the modified lithium extraction adsorbent as described in the first aspect, wherein the modified lithium extraction adsorbent is used for extracting lithium from salt lakes.

[0063] Compared with the prior art, the present disclosure has the following beneficial effects:

[0064] (1) The microcapsules in the modified lithium extraction adsorbent disclosed herein can fill cracks in the lithium extraction adsorbent when it ruptures due to expansion, thereby reducing adsorbent dissolution loss. The adsorbent does not require adsorbent particle treatment during the lithium extraction process. When cracks are greater than 50 μm, the microcapsules are ruptured and the cracks are repaired, resulting in a simple repair method.

[0065] (2) The adsorption capacity of the modified lithium extraction adsorbent disclosed in the present invention can reach more than 8.72 mg / g, and the capacity retention rate can reach more than 98.67% after 100 cycles.

[0066] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0068] FIG1 is a schematic diagram of the synthesis process of the binder capsule according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0069] The technical solution of the present disclosure is further described below through specific implementation methods. It should be understood by those skilled in the art that the embodiments are only used to help understand the present disclosure and should not be regarded as specific limitations of the present disclosure.

[0070] Example 1

[0071] This embodiment provides a modified lithium extraction adsorbent, which is prepared by the following method:

[0072] (1) Urea and formaldehyde were mixed in a molar ratio of 1:1.5 to prepare a mixed solution with a concentration of 0.1 mol / L. After mixing until the urea was completely dissolved, triethanolamine was added dropwise until the pH reached 8.5. The mixed solution was placed in a 70°C water bath and refluxed for 1.5 hours to obtain a urea-formaldehyde resin prepolymer solution. A sodium oleate surfactant solution with a mass fraction of 0.5% was prepared using pure water. Liquid epoxy resin and n-butyl glycidyl ether were mixed in a mass ratio of 6:1. After ultrasonication for 40 minutes, the solution was placed in a water bath at 50°C for 1 hour until the solution was allowed to stand without stratification, thereby obtaining a uniformly mixed adhesive dilution solution. 810 curing agent, KH-550 and butyl glycidyl ether were mixed. After ultrasonication for 40 minutes, the solution was placed in a water bath at 50°C for 1 hour until the solution was allowed to stand without stratification, thereby obtaining a uniformly mixed curing agent dilution solution.

[0073] (2) The urea-formaldehyde resin prepolymer solution, the surfactant solution and the binder dilution solution were stirred at a speed of 800 rpm and 50°C for 30 minutes, and then dilute sulfuric acid was added dropwise to adjust the reaction pH to 2, the reaction temperature was controlled to 55°C, the reaction was carried out for 3 hours, and the binder microcapsule powder was obtained after filtering, washing and drying, and the binder microcapsule D50 was 180 μm (the schematic diagram of the synthesis process of the binder microcapsule is shown in Figure 1). The urea-formaldehyde resin prepolymer solution, the surfactant solution and the curing agent dilution solution were stirred at a speed of 800 rpm and 50°C for 30 minutes, and then dilute sulfuric acid was added dropwise to adjust the reaction pH to 2, the reaction temperature was controlled to 55°C, the reaction was carried out for 3 hours, and the curing agent microcapsule powder was obtained after filtering, washing and drying, and the curing agent microcapsule D50 was 180 μm;

[0074] (3) An aluminum-based adsorbent, a curing agent microcapsule, a binder microcapsule, polyurethane, and ethyl acetate were mixed and stirred to form an adsorbent slurry, wherein the mass ratio of the aluminum-based adsorbent to the polyurethane was 1:0.5, the mass ratio of the ethyl acetate to the polyurethane was 2.5:1, the mass fraction of the total amount of microcapsules in the solids of the adsorbent slurry was 1%, and the mass of the curing agent microcapsules was 80% of the mass of the binder microcapsules. 5% carboxymethyl cellulose and propylene diamine were dissolved in saturated saline to form a uniform solution, wherein the mass ratio of carboxymethyl cellulose to propylene diamine was 4:1, and the total concentration of carboxymethyl cellulose and propylene diamine in the saturated saline was 80 g / L. The adsorbent slurry was slowly added, and the stirring rate was adjusted to 300 rpm to obtain spherical particles with a median particle size of 1.5 mm. After curing at 50° C. for 18 hours, the modified lithium extraction adsorbent was filtered and washed to obtain the modified lithium extraction adsorbent.

[0075] Example 2

[0076] This embodiment provides a modified lithium extraction adsorbent, which is prepared by the following method:

[0077] (1) Urea and formaldehyde were mixed in a molar ratio of 1:1.4 to prepare a mixed solution with a concentration of 0.1 mol / L. After mixing until the urea was completely dissolved, triethanolamine was added dropwise until the pH was 8. The mixed solution was placed in a water bath at 60°C and refluxed for 3 hours to obtain a urea-formaldehyde resin prepolymer solution. A sodium stearate surfactant solution with a mass fraction of 0.3% was prepared using pure water. Liquid epoxy resin and ethylene glycol butyl ether were mixed in a mass ratio of 5:1. After ultrasonication for 60 minutes, the solution was placed in a water bath at 40°C and heated for 1 hour until the solution was allowed to stand without stratification, thereby obtaining a uniformly mixed adhesive dilution solution. JA-IS curing agent, KH-560 and ethylene glycol butyl ether were mixed. After ultrasonication for 40 minutes, the solution was placed in a water bath at 50°C and heated for 0.8 hours until the solution was allowed to stand without stratification, thereby obtaining a uniformly mixed curing agent dilution solution.

[0078] (2) The urea-formaldehyde resin prepolymer solution, surfactant solution and binder dilution solution were stirred at 900 rpm and 50°C for 30 min, then dilute sulfuric acid was added dropwise to adjust the reaction pH to 1.8, the reaction temperature was controlled to 40°C, the reaction was carried out for 5 h, and the binder microcapsule powder was obtained after filtering, washing and drying, and the binder microcapsule D50 was 120 μm (the schematic diagram of the synthesis process of the binder microcapsule is shown in Figure 1). The urea-formaldehyde resin prepolymer solution, surfactant solution and curing agent dilution solution were stirred at 500 rpm and 50°C for 30 min, then dilute sulfuric acid was added dropwise to adjust the reaction pH to 2.2, the reaction temperature was controlled to 60°C, the reaction was carried out for 3 h, and the curing agent microcapsule powder was obtained after filtering, washing and drying, and the curing agent microcapsule D50 was 300 μm;

[0079] (3) The aluminum-based adsorbent, curing agent microcapsules, binder microcapsules, polyurethane, and ethyl acetate were mixed and stirred to form an adsorbent slurry, wherein the mass ratio of the aluminum-based adsorbent to the polyurethane was 1:0.2, the mass ratio of the ethyl acetate to the polyurethane was 3:1, the mass fraction of the total amount of microcapsules in the solid of the adsorbent slurry was 2%, and the mass of the curing agent microcapsules was 150% of the mass of the binder microcapsules. 5% carboxymethyl cellulose and propylene diamine were dissolved in saturated salt water to form a uniform solution, wherein the mass ratio of carboxymethyl cellulose to propylene diamine was 4:1, and the total concentration of carboxymethyl cellulose and propylene diamine in the saturated salt water was 80 g / L. The adsorbent slurry was slowly added and the stirring rate was adjusted to 200 rpm to obtain spherical particles with a median particle size of 2 mm. After curing at 30° C. for 18 hours, the modified lithium extraction adsorbent was filtered and washed to obtain the modified lithium extraction adsorbent.

[0080] Example 3

[0081] This embodiment provides a modified lithium extraction adsorbent, which is prepared by the following method:

[0082] (1) Urea and formaldehyde were mixed in a molar ratio of 1:1.6 to prepare a mixed solution with a concentration of 0.1 mol / L. After mixing until the urea was completely dissolved, triethanolamine was added dropwise until the pH was 9. The mixed solution was placed in a water bath at 80°C and refluxed for 1 hour to obtain a urea-formaldehyde resin prepolymer solution. A sodium stearate surfactant solution with a mass fraction of 0.3% was prepared using pure water. Liquid epoxy resin and ethylene glycol butyl ether were mixed in a mass ratio of 8:1. After ultrasonication for 30 minutes, the solution was placed in a water bath at 50°C and heated for 0.5 hours until the solution was allowed to stand without stratification, thereby obtaining a uniformly mixed adhesive dilution solution. T31 curing agent, KH-560 and ethylene glycol butyl ether were mixed. After ultrasonication for 40 minutes, the solution was placed in a water bath at 60°C and heated for 0.8 hours until the solution was allowed to stand without stratification, thereby obtaining a uniformly mixed curing agent dilution solution.

[0083] (2) The urea-formaldehyde resin prepolymer solution, surfactant solution and binder dilution solution were stirred at 600 rpm and 40°C for 30 min, then dilute sulfuric acid was added dropwise to adjust the reaction pH to 2, the reaction temperature was controlled at 40°C, the reaction was carried out for 5 h, and the binder microcapsule powder was obtained after filtering, washing and drying, and the binder microcapsule D50 was 220 μm (the schematic diagram of the synthesis process of the binder microcapsule is shown in Figure 1). The urea-formaldehyde resin prepolymer solution, surfactant solution and curing agent dilution solution were stirred at 800 rpm and 50°C for 30 min, then dilute sulfuric acid was added dropwise to adjust the reaction pH to 2.2, the reaction temperature was controlled at 60°C, the reaction was carried out for 3 h, and the curing agent microcapsule powder was obtained after filtering, washing and drying, and the curing agent microcapsule D50 was 150 μm;

[0084] (3) The aluminum-based adsorbent, curing agent microcapsules, binder microcapsules, polyurethane, and ethyl acetate were mixed and stirred uniformly to form an adsorbent slurry, wherein the mass ratio of the aluminum-based adsorbent to the polyurethane was 1:0.8, the mass ratio of the ethyl acetate to the polyurethane was 2:1, the mass fraction of the total amount of microcapsules in the solid of the adsorbent slurry was 0.5%, and the mass of the curing agent microcapsules was 30% of the mass of the binder microcapsules. 5% carboxymethyl cellulose and propylene diamine were dissolved in saturated salt water to form a uniform solution, wherein the mass ratio of carboxymethyl cellulose to propylene diamine was 4:1, and the total concentration of carboxymethyl cellulose and propylene diamine in the saturated salt water was 80 g / L. The adsorbent slurry was slowly added and the stirring rate was adjusted to 500 rpm to obtain spherical particles with a median particle size of 0.5 mm. After curing at 60° C. for 12 hours, the modified lithium extraction adsorbent was filtered and washed to obtain the modified lithium extraction adsorbent.

[0085] Example 4

[0086] The only difference between this embodiment and embodiment 1 is that the mass ratio of the curing agent microcapsules to the binder microcapsules is 0.2:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0087] Example 5

[0088] The only difference between this embodiment and embodiment 1 is that the mass ratio of the curing agent microcapsules to the binder microcapsules is 2:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0089] Example 6

[0090] The only difference between this embodiment and embodiment 1 is that the total mass fraction of the microcapsules in the modified lithium extraction adsorbent is 0.3%, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0091] Example 7

[0092] The only difference between this embodiment and embodiment 1 is that the total mass fraction of the microcapsules in the modified lithium extraction adsorbent is 5%, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0093] Example 8

[0094] The only difference between this embodiment and embodiment 1 is that, during the preparation of the microcapsules, the stirring speed is 200 rpm, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0095] Example 9

[0096] The only difference between this embodiment and embodiment 1 is that the reaction temperature during the preparation of the microcapsules is 80° C., and the other conditions and parameters are exactly the same as those in embodiment 1.

[0097] Comparative Example 1

[0098] This comparative example directly uses aluminum-based adsorbent.

[0099] Comparative Example 2

[0100] The only difference between this comparative example and Example 1 is that no binder microcapsules are added, and other conditions and parameters are exactly the same as those in Example 1.

[0101] Comparative Example 3

[0102] The only difference between this comparative example and Example 1 is that no curing agent microcapsules are added, and other conditions and parameters are exactly the same as those in Example 1.

[0103] Performance testing:

[0104] The adsorption performance test method is the static adsorption method. This adsorbent is used for Li + To extract lithium from brine with a concentration of 500 ppm, take 20 g of deionized water and mix it with 2 g of lithium adsorbent. Extract lithium at room temperature for 10 hours. Measure the brine concentration before and after adsorption, and calculate the adsorption capacity according to the following formula.

[0105] The adsorption capacity of the adsorbent is: Q = V (C0-C) / m;

[0106] Q is the adsorption capacity, mg / g; V is the volume of the adsorption liquid, L; m is the mass of the adsorbent, g; C0 and C are the lithium ion concentrations in the brine before and after adsorption, respectively, mg / L.

[0107] The ratio of the adsorption capacity after 100 cycles to the initial adsorption capacity is the capacity retention rate after 100 cycles. The test results are shown in Table 1:

[0108] Table 1

[0109] As can be seen from Table 1, from Examples 1-3, the adsorption capacity of the modified lithium extraction adsorbent disclosed in the present disclosure can reach above 8.72 mg / g, and the capacity retention rate can reach above 98.67% after 100 cycles.

[0110] By comparing Example 1 with Examples 4-5, it can be seen that in the modified lithium extraction adsorbent disclosed in the present invention, the mass ratio of the curing agent microcapsules and the binder microcapsules will affect its performance. The mass ratio of the curing agent microcapsules and the binder microcapsules is controlled at (0.3-1.5):1. The performance of the modified lithium extraction adsorbent is good. If the proportion of the curing agent microcapsules is too high, the overall proportion of the binder will be reduced, affecting the adsorbent repair effect, thereby affecting the material cycle stability. If the proportion of the binder microcapsules is too high, the curing agent curing effect will be poor, affecting the material cycle stability.

[0111] By comparing Example 1 with Examples 6-7, it can be seen that in the modified lithium extraction adsorbent disclosed in the present invention, the mass proportion of microcapsules will affect its performance. When the mass fraction of microcapsules is controlled at 0.5-2%, the performance of the modified lithium extraction adsorbent is better. If the proportion of microcapsules is too high, the adsorption capacity of the adsorbent is affected. If the proportion of microcapsules is too low, the adsorbent cannot be repaired well.

[0112] By comparing Example 1 and Example 8, it can be seen that during the preparation process of the microcapsules described in the present disclosure, the stirring speed will affect the performance of the modified lithium extraction adsorbent. If the rotation speed is too slow, the core droplets will be large and difficult to be completely wrapped. The particles that are not completely wrapped will agglomerate, further increasing the size of the particles, reducing the proportion of the microcapsule core, and affecting the repair effect.

[0113] By comparing Example 1 and Example 8, it can be seen that in the preparation process of the microcapsules described in the present disclosure, the reaction temperature controls the synthesis rate of the urea-formaldehyde resin. If the temperature is too low, the reaction rate is slow and the efficiency is low; if the temperature is too high, the urea-formaldehyde resin is generated too quickly and agglomerates before it adheres to the surface of the inner core droplets, affecting the formation of the capsule shell and thus affecting the repair effect.

[0114] From the comparison between Example 1 and Comparative Example 1, it can be seen that the present invention sets microcapsules on the surface of the aluminum-based adsorbent. When the adsorbent particles crack during the circulation process, the microcapsules rupture, and the binder that can be solidified in water flows out and reacts with the curing agent to fill the cracks, thereby reducing the dissolution loss of the adsorbent and improving the recyclability of the adsorbent.

[0115] From the comparison between Example 1 and Comparative Example 2, it can be seen that the binder microcapsules can react with the curing agent microcapsules during the lithium extraction process to fill the cracks of the adsorbent and increase the service life of the adsorbent.

[0116] From the comparison between Example 1 and Comparative Example 3, it can be seen that the curing agent microcapsules play a role in curing the adhesive, making the adhesive present in the cracks more stable.

Claims

1. A modified lithium extraction adsorbent, comprising an aluminum-based adsorbent and microcapsules disposed on the surface of the aluminum-based adsorbent, wherein the microcapsules include curing agent microcapsules and binder microcapsules.

2. The modified lithium extraction adsorbent according to claim 1, wherein, The curing agent microcapsules include an underwater curing agent and a curing composite shell.

3. The modified lithium extraction adsorbent according to claim 2, wherein, The curing composite shell includes urea-formaldehyde resin.

4. The modified lithium extraction adsorbent according to claim 2 or 3, wherein, The underwater curing agent includes any one or a combination of at least two of T31 curing agent, JA-IS curing agent, I965 curing agent, 810 curing agent or P117 curing agent.

5. The modified lithium extraction adsorbent according to any one of claims 1-4, wherein, The binder microcapsules include a liquid epoxy resin core and a binder composite shell disposed on the surface of the liquid epoxy resin core.

6. The modified lithium extraction adsorbent according to claim 5, wherein, The binder composite shell includes urea-formaldehyde resin.

7. The modified lithium extraction adsorbent according to any one of claims 1-6, wherein, The median particle size D50 of the curing agent microcapsules and the binder microcapsules is independently 100 - 300 μm.

8. The modified lithium extraction adsorbent according to any one of claims 1-7, wherein, Based on the mass of the modified lithium extraction adsorbent being 100%, the mass fraction of the microcapsules is 0.5 - 2%; Optionally, the mass ratio of the curing agent microcapsules to the binder microcapsules is (0.3 - 1.5):

1.

9. The modified lithium extraction adsorbent according to any one of claims 1-8, wherein, The modified lithium extraction adsorbent further includes a binder; Optionally, the binder includes polyurethane.

10. A preparation method of the modified lithium extraction adsorbent according to any one of claims 1 - 9, comprising the following steps: Mix a urea-formaldehyde resin prepolymer solution, a surfactant solution and a binder diluent, heat and stir, then add acid to adjust the pH for reaction to obtain binder microcapsules; Mix a urea-formaldehyde resin prepolymer solution, a surfactant solution and a curing agent diluent, heat and stir, then add acid to adjust the pH for reaction to obtain curing agent microcapsules; Mix the aluminum-based adsorbent, binder microcapsules, curing agent microcapsules, binder and solvent to obtain a mixed solution, and perform granulation treatment on the mixed solution to obtain the modified lithium extraction adsorbent.

11. The preparation method according to claim 10, wherein, The urea-formaldehyde resin prepolymer solution is prepared by the following method: Mix urea and a formaldehyde solution to form a mixed solution. After mixing until the urea is completely dissolved, add triethanolamine to adjust the pH of the mixed solution, and perform a water bath reflux stirring reaction to obtain the urea-formaldehyde resin prepolymer solution; Optionally, the molar ratio of formaldehyde in the urea and formaldehyde solution is 1:(1.4 - 1.6); Optionally, the pH of the mixed solution is 8 - 9; Optionally, the temperature of the water bath reflux stirring reaction is 60 - 80°C; Optionally, the time of the water bath reflux stirring reaction is 1 - 3 h; Optionally, the mass concentration of the surfactant solution is 0.3% - 0.8%; Optionally, the surfactant includes any one or a combination of at least two of sodium oleate, sodium stearate, sodium metasilicate or sodium dodecylbenzenesulfonate.

12. The preparation method according to claim 10 or 11, wherein, The binder diluent is prepared by the following method: Mix liquid epoxy resin with a diluent, perform ultrasonic treatment and then carry out a water bath heating reaction to obtain the binder diluent; Optionally, the mass ratio of the liquid epoxy resin to the diluent is 1:(0.1 - 0.2).

13. The preparation method according to any one of claims 10-12, wherein, The curing agent diluent is prepared by the following method: Mix a curing agent, a coupling agent and a diluent, perform ultrasonic treatment and then carry out a water bath heating reaction to obtain the curing agent diluent; Optionally, the coupling agent includes KH-550 and / or KH560; Optionally, the diluent includes n-butyl glycidyl ether, ethylene glycol monobutyl ether, or benzyl glycidyl ether; Optionally, during the preparation of the binder diluent and the curing agent diluent, the ultrasonic time is independently 30 to 60 min; Optionally, during the preparation of the binder diluent and the curing agent diluent, the temperature of the water bath heating reaction is independently 40 to 50 °C; Optionally, during the preparation of the binder diluent and the curing agent diluent, the time of the water bath heating reaction is independently 0.5 to 1 h.

14. The preparation method according to any one of claims 10-13, wherein, During the preparation of the binder microcapsules and the curing agent capsules, the heating and stirring speed is independently 500 to 1000 rpm; Optionally, during the preparation of the binder microcapsules and the curing agent capsules, the heating and stirring temperature is independently 40 to 50 °C; Optionally, during the preparation of the binder microcapsules and the curing agent capsules, the heating and stirring time is independently 30 to 60 min; Optionally, during the preparation of the binder microcapsules and the curing agent capsules, the pH adjusted by adding acid is independently 1.8 to 2.2; Optionally, during the preparation of the binder microcapsules and the curing agent capsules, the reaction temperature is independently 40 to 60 °C; Optionally, during the preparation of the binder microcapsules and the curing agent capsules, the reaction time is independently 2 to 5 h.

15. The preparation method according to any one of claims 10-14, wherein, The mass ratio of the aluminum-based adsorbent to the binder is 1:(0.2 to 0.8); Optionally, the solvent includes ethyl acetate; Optionally, the mass ratio of the solvent to the binder is (2 to 3):1; Optionally, the mass fraction of the microcapsules in the mixed solution is 0.5% to 1.5%.

16. The preparation method according to any one of claims 10-15, wherein, The granulation treatment includes liquid-phase solidification granulation and / or extrusion granulation, preferably liquid-phase solidification granulation; Optionally, the liquid-phase solidification granulation includes: dissolving carboxymethyl cellulose and propylenediamine in saturated brine to form a homogeneous solution, slowly adding the mixed solution to the homogeneous solution, adjusting the stirring rate to 200 to 500 rpm, obtaining spherical particles with a particle size of 0.5 to 2 mm, and filtering and washing after heat preservation and curing at 30 to 60 °C to obtain the modified lithium extraction adsorbent.

17. Use of the modified lithium extraction adsorbent according to any one of claims 1-9 for extracting lithium from salt lakes.

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