Adsorbent for extracting lithium from salt lake, and preparation method therefor

Abstract

Disclosed in the present invention are an adsorbent for extracting lithium from a salt lake, and a preparation method therefor. The preparation method comprises: embedding an aluminum salt and urea by using a polymer monomer during the bulk polymerization reaction for cross-linking, thereby forming a macroporous resin block; crushing and washing the macroporous resin block, and screening same to obtain resin particles; and adding the resin particles into a lithium salt solution, heating same to perform a reaction, and activating and washing same to obtain a lithium-extracting adsorbent. A preparation method for the macroporous resin block comprises: uniformly mixing a polymer monomer, a cross-linking agent and a pore-foaming agent, then adding an initiator and a precursor powder thereto, uniformly mixing same to obtain an oil phase, and subjecting the oil phase to a polymerization reaction, so as to obtain a macroporous resin block. In the preparation method of the present invention, urea hydrolysis, aluminum hydroxide generation and lithium replacement are finished in one step, thereby improving the reaction efficiency, enlarging the surface area and active sites of aluminum hydroxide, and clearing resin pore channels, and the prepared lithium-extracting adsorbent has the characteristics of a high adsorption speed, a large adsorption capacity, high selectivity, stable performance and a long service life.

Description

An adsorbent for extracting lithium from salt lakes and a preparation method thereof Technical Field

[0001] The present invention belongs to the technical field of adsorbents, and in particular relates to an adsorbent for extracting lithium from salt lakes and a preparation method thereof. Background Art

[0002] Before the mid-1980s, lithium salt production worldwide primarily used lithium ore as a raw material. This process was relatively mature, but it was costly, environmentally destructive, and limited in resources, creating significant limitations that urgently required new technologies. my country's lithium reserves account for approximately 6% of global reserves, with approximately 85% concentrated in salt lake brines. Lithium extraction from salt lakes is less expensive than mining ore. With the exploration and development of South America's vast salt lake brine lithium resources, lithium extraction from salt lakes has become a growing trend. Because most of my country's salt lake brines have a high magnesium-to-lithium ratio, the traditional process of extracting potassium from the raw brine further increases this ratio, making lithium extraction more difficult and yielding a low lithium recovery rate. Only 20% of lithium extracted from brine in my country is produced, and the majority of salt lake lithium products are industrial-grade lithium carbonate, leaving China with a high dependence on foreign sources for high-end processing.

[0003] Methods for extracting lithium from salt lake brines primarily include solvent extraction, adsorption, membrane separation, electrochemical methods, and coupled reaction / separation techniques. Liquid-liquid extraction, with its advantages of simple process, easily controlled operating conditions, low cost, and high extraction efficiency and selectivity, is considered the most effective method for extracting lithium from Qinghai salt lake brines in terms of ion selectivity and lithium yield. However, environmental concerns regarding the extractant and the high requirements for extraction equipment have limited its industrial application. Membrane separation is costly and difficult to commercialize. Electrochemical methods avoid the need for acid elution during the delithiation process, reducing material loss and enhancing cycling performance. They offer low-energy, high-efficiency lithium extraction technologies. However, the chemical reactions at the electrodes must avoid side reactions, and the electrolyte composition is demanding. The system requires further optimization, and currently, large-scale production is not feasible. Adsorption is a lithium extraction technology with significant environmental and economic advantages, particularly for extracting low-grade, high-magnesium lithium from brines and seawater. Clearly, adsorption holds the greatest potential for application in my country's low-grade salt lakes.

[0004] The core of the adsorption method is to prepare lithium adsorbents with high selectivity, large adsorption capacity and good cyclic stability. In recent years, most of the research reports on lithium extraction by adsorption method have used inorganic adsorbents, mainly ion sieve oxides and aluminum adsorbents. Among them, ion sieve oxides include manganese ion sieves and doped ion sieves. Manganese adsorbents are the research hotspot of lithium ion sieve adsorbents. They have a spinel structure and mainly include LiMn2O4, Li4Mn5O 12 、Li 1.6Mn 1.6 O4, etc., lithium manganese oxide is acid-leached, Li + H + The expression of aluminum adsorbent is "LiCl·mAl(OH)3·nH2O" (Li / Al-LDHs), where LiCl is inserted into the amorphous Al(OH)3 layer, and Li + Entering into the Al-O octahedral cavity, deintercalating some Li + After that, the aluminum adsorbent has steric hindrance effect and memory effect, thereby selectively adsorbing Li + After saturation, elution is performed with water, which does not introduce other impurities and reduces operating costs. However, these adsorbents often aggregate into unstable particles from coprecipitated crystals, often in powder form, resulting in poor mechanical strength and high dissolution rates. Therefore, granulation of these adsorbents is often necessary.

[0005] Currently, the most common granulation method involves extruding a mixture of activated aluminum hydroxide powder, lithium chloride solid, a polymer, and an organic solvent. However, due to factors such as low reaction efficiency between solids and low porosity during extrusion, the resulting adsorbent activity decreases significantly, while the dissolution loss rate remains high. Resin granulation technologies, including direct encapsulation and resin hybridization, can partially address this issue.

[0006] There are multiple patent reports using monomer in-situ polymerization to form resin, directly embedding lithium adsorbent to form granulation. Patent CN104014308A uses monomer polymerization to generate resin to directly embed aluminum hydroxide powder, which improves the load rate and adsorption capacity of active inorganic particles. Patent CN102631897A also uses similar binder embedding, and its molecular sieve type or ion sieve type lithium adsorbent uses insoluble hydroxide, and the exchange capacity is 3-15mg / mL (resin). CN106975436A uses chlorine-containing polymer (such as vinyl chloride) powder to mix with aluminum hydroxide, and adds liquid chlorine to soften and establish embedding skeleton during extrusion. Although this method can make resin have larger specific surface area by pore making, after embedding, inorganic particle surface interface is closely combined with resin, and exposed surface is still smaller, and aluminum hydroxide powder is smaller than surface itself, so exchange rate and lithium extraction capacity are still lower.

[0007] Another resin hybrid method is to first enrich aluminum ions in the resin pores, and then precipitate aluminum hydroxide in the pores. U.S. Patent US4221767A discloses a method for loading LiCl·2Al(OH)3·nH2O in an anion exchange resin. The specific method is to first enrich aluminum ions in the resin pores, then precipitate aluminum hydroxide in the pores, and then use lithium hydroxide to react with the aluminum hydroxide in the resin, and finally transform it into LiCl·2Al(OH)3·nH2O. This method solves the problem of loading active inorganic particles and maintains its lithium extraction activity, but the pore volume and specific surface area of ​​the anion exchange resin are relatively low. Therefore, the loading amount of active inorganic particles is relatively low, which affects the lithium extraction capacity. In addition, the Chinese patent application number 20201015308.5 uses Al 3+ It is introduced into the adsorption resin, and then alkali solution is added to precipitate aluminum hydroxide. However, the in-situ reaction in the resin has the advantages of open pores and large surface area. At the same time, due to the 3+ The introduction amount is limited, so the overall adsorption amount is limited, and the maximum adsorption amount of the lithium adsorbent is only 4.1 mg / g.

[0008] Summary of the Invention

[0009] The present invention provides an adsorbent for lithium extraction from salt lakes and a preparation method thereof, which can overcome the problems in existing resin-based lithium extraction adsorbent technology, such as a small number of active sites in the direct embedding method and a low aluminum loading capacity in the resin hybridization reaction, which ultimately leads to low lithium extraction adsorbent activity, exchange rate and lithium extraction capacity.

[0010] The technical solution of the present invention is:

[0011] The present invention relates to a method for preparing an adsorbent, comprising the following steps:

[0012] S1, using the polymer monomer bulk polymerization reaction to embed aluminum salt and urea during cross-linking to form a macroporous resin block;

[0013] S2, crushing and washing the macroporous resin block obtained in step S1, crushing and washing, and sieving to obtain resin particles;

[0014] S3. Adding the resin particles obtained in step S2 to a lithium salt solution for temperature reaction, and obtaining a lithium-extracting adsorbent after activation and washing.

[0015] The present invention soaks resin particles in a lithium salt solution for a temperature reaction. At a relatively high temperature, urea contacts and penetrates into the resin moisture, hydrolyzes to produce alkalinity, and precipitates the aluminum salt into aluminum hydroxide. Simultaneously, lithium ions penetrate to form an ion sieve. The carbon dioxide gas generated by the hydrolysis of urea further expands, making the aluminum hydroxide loose and porous. When the carbon dioxide overflows, it further expands the resin pores.

[0016] Preferably, in step S1, the preparation method of the macroporous resin block is specifically as follows: polymer monomers, crosslinking agents and porogens are mixed, and then an initiator and a precursor powder composed of a mixture of aluminum salt powder and urea powder are added and mixed to obtain an oil phase, and the oil phase is polymerized to obtain a macroporous resin block.

[0017] Preferably, the particle sizes of the aluminum salt powder and the urea powder are both 0.01-1 μm, and the mass ratio of the aluminum salt powder to the urea powder is 1:3-3:1; wherein the aluminum salt powder is at least one of aluminum chloride, aluminum bromide, aluminum nitrate and aluminum sulfate.

[0018] Preferably, in the preparation method of the macroporous resin block, the polymer monomer is at least one of styrene, p-chloromethylstyrene, m-chloromethylstyrene, p-nitrostyrene, m-nitrostyrene, acrylonitrile, butadiene and acrylamide; the cross-linking agent is at least one of p-divinylbenzene, divinylbenzene, N'N-methylenebisacrylamide, pentaerythritol triacrylate, pentaerythritol triallyl ether, pentaerythritol allyl ether, polyethylene glycol diacrylate and tetraallyloxyethane; the porogen is at least one of ethylbenzene, isopropanol, butanol, octanol and xylene; and the initiator is benzoyl peroxide and / or azobisisobutyronitrile.

[0019] Preferably, the mass ratio of the polymer monomer, the cross-linking agent, the porogen, the initiator and the precursor powder is 50:100-150:50-150:1-4:50-110.

[0020] Preferably, in step S1, the polymerization reaction temperature is 50-70° C. and the time is 2-6 hours.

[0021] Preferably, in step S2, the particle size of the resin particles is 0.3-1.2 mm.

[0022] Preferably, in step S3, the lithium salt solution is a solution of at least one of lithium chloride, lithium sulfate and lithium nitrate; and the mass concentration of the lithium salt solution is 10-30%.

[0023] Preferably, in step S3, the temperature of the temperature-raising reaction is 80-100° C., and the time is 4-10 h.

[0024] Preferably, in step S3, the activation method is: adding sodium chloride solution to the resin obtained by cooling and filtering after temperature reaction for activation, the mass ratio of resin to sodium chloride solution is 1: (3-10), and the mass concentration of the sodium chloride solution is 1-20%.

[0025] The present invention also relates to an adsorbent for extracting lithium from salt lakes, which is prepared by the above-mentioned preparation method.

[0026] Preferably, the molar ratio of lithium to aluminum in the lithium extraction adsorbent is 1-1.5:1-5.

[0027] The beneficial effects of the present invention are:

[0028] (1) The lithium-extracting adsorbent prepared by the present invention utilizes an in-situ bulk polymerization synthesis method and a urea pore hydrolysis method. The present invention first utilizes a monomer cross-linked resin to embed aluminum salt and urea to form a macroporous resin block, so that the precursors (aluminum salt and urea) are evenly dispersed in the adsorption resin pores. The macroporous resin block is then made into resin particles, and the resin particles are immersed in a lithium salt solution and subjected to a temperature reaction. Urea hydrolysis + aluminum hydroxide generation + lithium replacement are completed in one step, thereby improving the reaction efficiency, expanding the surface area and active sites of aluminum hydroxide, unblocking the resin pores, and further improving the activity of the adsorbent.

[0029] (2) The preparation method of the present invention utilizes the cross-linking and entanglement of polymer chains within the resin nanopores to effectively inhibit the loss of active nanoparticles and ensure the service life of the adsorbent.

[0030] (3) The lithium extraction adsorbent prepared by the present invention has the characteristics of fast adsorption speed, large adsorption capacity, high selectivity, stable performance and long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0032] FIG1 is a flow chart of the preparation of a lithium-extracting adsorbent according to the present invention;

[0033] FIG2 is a characterization diagram of the lithium extraction adsorbent of Example 1 of the present invention;

[0034] Among them, (a) is the XRD pattern of resin-embedded aluminum sulfate and urea; (b) is the FTIR pattern of resin-embedded aluminum sulfate and urea, A is before the temperature reaction, and B is after the temperature reaction;

[0035] FIG3 is an X-ray diffraction pattern of the active inorganic component (LiCl·nAl(OH)3·mH2O) of the lithium adsorbent in Comparative Example 1;

[0036] FIG4 is an X-ray diffraction pattern of the lithium extraction adsorbent of the present invention, wherein the active ingredient embedded in the polymer powder is (LiCl·nAl(OH)3·mH2O). DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0038] Example 1

[0039] (1) 100 g of styrene monomer, 200 g of crosslinking agent (N'N-methylenebisacrylamide), and porogen (150 g of octanol and 50 g of ethylbenzene) were mixed uniformly to a total of 500 g. Then, initiator (1 g of benzoyl peroxide and 1 g of azobisisobutyronitrile) was added and stirred at room temperature until completely mixed. Then, 125 g of precursor powder was added, wherein the precursor powder was composed of aluminum sulfate powder and urea powder with a particle size of 0.01-1 μm, and the mass ratio of aluminum sulfate to urea was 1:2. The obtained oil phase was added to a flask equipped with a stirring and temperature control device, stirred, and then a polymerization reaction was carried out at 50°C for 2 hours to obtain a macroporous resin block.

[0040] (2) The macroporous resin block is crushed and washed, and sieved to obtain 0.3-1.2 mm resin particles loaded with the precursor.

[0041] (3) Add the resin particles to a 10% lithium chloride solution with a volume 2.5 times that of the resin, control the temperature at 90°C, react for 6 hours, cool, and filter out the resin.

[0042] (4) Add a sodium chloride solution with a mass concentration of 10% for activation, and the mixing mass ratio is resin: sodium chloride solution = 1:5. After activation, the material is washed with pure water.

[0043] The obtained lithium extraction adsorbent is numbered A.

[0044] Example 2

[0045] (1) 100 g of polymer monomer p-chloromethylstyrene, 200 g of crosslinking agent (N'N-methylenebisacrylamide), and porogen (150 g of octanol and 50 g of ethylbenzene) were mixed evenly to a total of 500 g. Then, initiator (1 g of benzoyl peroxide and 1 g of azobisisobutyronitrile) was added and stirred at room temperature until completely mixed. Then, 125 g of precursor powder was added, wherein the precursor powder was composed of aluminum sulfate powder and urea powder with a particle size of 0.01-1 μm, and the mass ratio of aluminum sulfate to urea was 1:2. The obtained oil phase was added to a flask equipped with a stirring and temperature control device, stirred, and then heated to react, and then polymerized at 50°C for 2 hours to obtain a macroporous resin block.

[0046] (2) The macroporous resin block is crushed and washed, and sieved to obtain 0.3-1.2 mm resin particles loaded with the precursor.

[0047] (3) Add the resin particles to a 10% lithium chloride solution 2.5 times the volume of the resin, control the temperature at 90°C, react for 6 hours, cool, and filter out the resin.

[0048] (4) Add a sodium chloride solution with a mass concentration of 20% for activation, and the mixing mass ratio is resin: sodium chloride solution = 1:5. After activation, the material is washed with pure water.

[0049] The obtained lithium extraction adsorbent is numbered B.

[0050] Example 3

[0051] (1) 100 g of styrene monomer, 200 g of crosslinking agent (N'N-methylenebisacrylamide), and 150 g of porogen (ethylbenzene) were mixed uniformly to a total of 450 g. Then, initiators (1 g of benzoyl peroxide and 1 g of azobisisobutyronitrile) were added and stirred at room temperature until completely mixed. Then, 125 g of precursor powder was added, wherein the precursor powder consisted of aluminum sulfate powder and urea powder with a particle size of 0.01-1 μm, and the mass ratio of aluminum sulfate to urea was 1:2. The resulting oil phase was added to a flask equipped with a stirring and temperature control device, stirred, and then polymerized at 50°C for 2 h to obtain a macroporous resin block.

[0052] (2) The macroporous resin block is crushed and washed, and sieved to obtain 0.3-1.2 mm resin particles loaded with the precursor.

[0053] (3) Add the resin particles to a 10% lithium chloride solution 2.5 times the volume of the resin, control the temperature at 90°C, react for 6 hours, cool, and filter out the resin.

[0054] (4) Add a sodium chloride solution with a mass concentration of 10% for activation, and the mixing mass ratio is resin: sodium chloride solution = 1:3. After activation, the material is washed with pure water.

[0055] The obtained lithium extraction adsorbent is numbered C.

[0056] Example 4

[0057] (1) 100 g of monomer styrene, 200 g of crosslinking agent (N'N-methylenebisacrylamide), and porogen (150 g of octanol and 50 g of ethylbenzene) were mixed evenly to a total of 500 g. Then, initiator (1 g of benzoyl peroxide and 1 g of azobisisobutyronitrile) was added and stirred at room temperature until completely mixed. Then, 125 g of precursor powder was added, wherein the precursor powder was composed of aluminum sulfate powder and urea powder with a particle size of 0.01-1 μm, and the mass ratio of aluminum sulfate to urea was 3:1. The obtained oil phase was added to a flask equipped with a stirring and temperature control device, stirred, and then a polymerization reaction was carried out at 50°C for 2 hours to obtain a macroporous resin block.

[0058] (2) The macroporous resin block is crushed and washed, and sieved to obtain 0.3-1.2 mm resin particles loaded with the precursor.

[0059] (3) Add the resin particles to a 10% lithium chloride solution 2.5 times the volume of the resin, control the temperature at 90°C, react for 6 hours, cool, and filter out the resin.

[0060] (4) Add a sodium chloride solution with a mass concentration of 20% for activation, and the mixing mass ratio is resin: sodium chloride solution = 1:5. After activation, the material is washed with pure water.

[0061] The obtained lithium extraction adsorbent is numbered D.

[0062] Example 5

[0063] (1) 100 g of polymer monomer styrene, 200 g of crosslinking agent (N'N-methylenebisacrylamide), and porogen (150 g of octanol and 50 g of ethylbenzene) were mixed uniformly to a total of 500 g. Then, initiator (1 g of benzoyl peroxide and 1 g of azobisisobutyronitrile) was added and stirred at room temperature until completely mixed. Then, 220 g of precursor powder was added, wherein the precursor powder was composed of aluminum sulfate powder and urea powder with a particle size of 0.01-1 μm, and the mass ratio of aluminum sulfate to urea was 1:2. The obtained oil phase was added to a flask equipped with a stirring and temperature control device, stirred, and then a polymerization reaction was carried out at 50°C for 2 hours to obtain a macroporous resin block.

[0064] (2) The macroporous resin block is crushed and washed, and sieved to obtain 0.3-1.2 mm resin particles loaded with the precursor.

[0065] (3) Add the resin particles to a 10% lithium chloride solution 2.5 times the volume of the resin, control the temperature at 90°C, react for 6 hours, cool, and filter out the resin.

[0066] (4) Add a sodium chloride solution with a mass concentration of 10% for activation, and the mixing mass ratio is resin: sodium chloride solution = 1:5. After activation, the material is washed with pure water.

[0067] The obtained lithium extraction adsorbent is numbered E.

[0068] Example 6

[0069] (1) 100 g of polymer monomer styrene, 200 g of crosslinking agent (N'N-methylenebisacrylamide), and porogen (150 g of octanol and 50 g of ethylbenzene) were mixed uniformly to a total of 500 g. Then, initiator (1 g of benzoyl peroxide and 1 g of azobisisobutyronitrile) was added and stirred at room temperature until completely mixed. Then, 125 g of precursor powder was added, wherein the precursor powder was composed of aluminum sulfate powder and urea powder with a particle size of 0.01-1 μm, and the mass ratio of aluminum sulfate to urea was 1:2. The obtained oil phase was added to a flask equipped with a stirring and temperature control device, stirred, and then a polymerization reaction was carried out at 60°C for 6 hours to obtain a macroporous resin block.

[0070] (2) The macroporous resin block is crushed and washed, and sieved to obtain 0.3-1.2 mm resin particles loaded with the precursor.

[0071] (3) Add the resin particles to a 10% lithium chloride solution 2.5 times the volume of the resin, control the temperature at 90°C, react for 6 hours, cool, and filter out the resin.

[0072] (4) Add a sodium chloride solution with a mass concentration of 10% for activation, and the mixing mass ratio is resin: sodium chloride solution = 1:5. After activation, the material is washed with pure water.

[0073] The obtained lithium extraction adsorbent is numbered F.

[0074] Example 7

[0075] (1) 100 g of styrene monomer, 200 g of crosslinking agent (N'N-methylenebisacrylamide), and porogen (150 g of octanol and 50 g of ethylbenzene) were mixed uniformly to a total of 500 g. Then, initiator (1 g of benzoyl peroxide and 1 g of azobisisobutyronitrile) was added and stirred at room temperature until completely mixed. Then, 125 g of precursor powder was added, wherein the precursor powder was composed of aluminum sulfate powder and urea powder with a particle size of 0.01-1 μm, and the mass ratio of aluminum sulfate to urea was 1:2. The obtained oil phase was added to a flask equipped with a stirring and temperature control device, stirred, and then a polymerization reaction was carried out at 50°C for 2 hours to obtain a macroporous resin block.

[0076] (2) The macroporous resin block is crushed and washed, and sieved to obtain 0.3-1.2 mm resin particles loaded with the precursor.

[0077] (3) Add the resin particles to a 10% lithium sulfate solution with a volume 2.5 times that of the resin, control the temperature at 90°C, react for 6 hours, cool, and filter out the resin.

[0078] (4) Add a sodium chloride solution with a mass concentration of 10% for activation, and the mixing mass ratio is resin: sodium chloride solution = 1:5. After activation, the material is washed with pure water.

[0079] The obtained lithium extraction adsorbent is numbered G.

[0080] Example 8

[0081] (1) 100 g of styrene monomer, 200 g of crosslinking agent (N'N-methylenebisacrylamide), and porogen (150 g of octanol and 50 g of ethylbenzene) were mixed uniformly to a total of 500 g. Then, initiator (1 g of benzoyl peroxide and 1 g of azobisisobutyronitrile) was added and stirred at room temperature until completely mixed. Then, 125 g of precursor powder was added, wherein the precursor powder was composed of aluminum sulfate powder and urea powder with a particle size of 0.01-1 μm, and the mass ratio of aluminum sulfate to urea was 1:2. The obtained oil phase was added to a flask equipped with a stirring and temperature control device, stirred, and then a polymerization reaction was carried out at 50°C for 2 hours to obtain a macroporous resin block.

[0082] (2) The macroporous resin block is crushed and washed, and sieved to obtain 0.3-1.2 mm resin particles loaded with the precursor.

[0083] (3) Add the resin particles to a 10% lithium chloride solution with a volume 2.5 times that of the resin, control the temperature at 100°C, react for 6 hours, cool, and filter out the resin.

[0084] (4) Add a sodium chloride solution with a mass concentration of 10% for activation, and the mixing mass ratio is resin: sodium chloride solution = 1:5. After activation, the material is washed with pure water.

[0085] The obtained lithium extraction adsorbent is numbered H.

[0086] Comparative Example 1

[0087] A brine lithium extraction adsorbent was prepared according to the method of Example 5 in the specific implementation manner of the specification of Chinese patent CN104014308A.

[0088] This patent uses an in-situ polymerization synthesis method to evenly disperse active aluminum hydroxide powder in the pores of the adsorption resin, and then reacts with a lithium salt solution. The active inorganic component of the resulting lithium extraction adsorbent is LiCl·nAl(OH)3·mH2O, as shown in Figure 3, which has a regular layered structure.

[0089] Test Example 1

[0090] The lithium extraction adsorbent A of Example 1 was characterized by X-ray and infrared spectroscopy. The results are shown in Figure 2, where (a) is the XRD pattern of resin-embedded aluminum sulfate and urea; (b) is the FTIR pattern of resin-embedded aluminum sulfate and urea, A is before the temperature reaction, and B is after the temperature reaction.

[0091] As can be seen from A in Figures 2(a) and 2(b), when Al2(SO4)3 and CO(NH2)2 are encapsulated in the resin, XRD and FTIR results clearly indicate the presence of characteristic peaks for Al2(SO4)3 and CO(NH2)2 in the material, demonstrating the successful encapsulation of aluminum salts and urea in the monomeric cross-linked resin. The macroporous resin blocks are formed into resin particles, which are then immersed in a lithium salt solution and reacted at a high temperature. The urea comes into contact with the resin moisture, hydrolyzing to produce alkalinity, causing the aluminum salt to precipitate as Al(OH)3. Simultaneously, the CO2 produced by the urea hydrolysis escapes. B in Figures 2(a) and 2(b) clearly demonstrates the formation of Al(OH)3.

[0092] Test Example 2

[0093] The active inorganic component embedded in the lithium-extraction adsorbent obtained by the present invention is LiCl·nAl(OH)3·mH2O. As shown in Figure 4, it has a regular layered structure. Compared with Figure 3, the main characteristic peaks are the same, indicating that the active component LiCl·nAl(OH)3·mH2O has been successfully obtained. However, the peaks are significantly broadened, indicating that the particle size of the active component has become smaller and the dispersion is high, confirming the effectiveness of the in-situ embedding and dispersion of the macroporous resin.

[0094] The saturated adsorption capacity of lithium by the adsorbents in each example is shown in Table 1. The molar ratio of lithium to aluminum in the adsorbent of Comparative Example 1 is 1:1, and the saturated adsorption capacity of lithium is 7.2 g / L.

[0095] Table 1

[0096] It can be seen from Table 1 that the lithium extraction adsorbent prepared by the present invention has a relatively high saturated adsorption capacity for lithium.

[0097] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or illustrative of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A method for preparing an adsorbent for extracting lithium from salt lakes, characterized in that: The following steps are involved: S1, using the polymer monomer bulk polymerization reaction to embed aluminum salt and urea during cross-linking to form a macroporous resin block; wherein the preparation method of the macroporous resin block is specifically: mixing the polymer monomer, the cross-linking agent and the porogen, then adding an initiator and a precursor powder composed of a mixture of aluminum salt powder and urea powder to mix, to obtain an oil phase, and polymerizing the oil phase to obtain a macroporous resin block; S2, crushing and washing the macroporous resin block obtained in step S1, and sieving to obtain resin particles; S3, adding the resin particles obtained in step S2 into a lithium salt solution for temperature reaction, and obtaining a lithium extraction adsorbent after activation and washing.

2. The preparation method according to claim 1, characterized in that: The particle sizes of the aluminum salt powder and the urea powder are both 0.01-1 μm, and the mass ratio of the aluminum salt powder to the urea powder is 1:3-3:1; wherein the aluminum salt powder is at least one of aluminum chloride, aluminum bromide, aluminum nitrate and aluminum sulfate.

3. The preparation method according to claim 1, characterized in that: The polymer monomer is at least one of styrene, p-chloromethylstyrene, m-chloromethylstyrene, p-nitrostyrene, m-nitrostyrene, acrylonitrile, butadiene and acrylamide; the crosslinking agent is at least one of divinylbenzene, N'N-methylenebisacrylamide, pentaerythritol triacrylate, pentaerythritol allyl ether, polyethylene glycol diacrylate and tetraallyloxyethane; the porogen is at least one of ethylbenzene, isopropanol, butanol, octanol and xylene; and the initiator is benzoyl peroxide and / or azobisisobutyronitrile.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the polymer monomer, the crosslinking agent, the porogen, the initiator and the precursor powder is 50:100-150:50-150:1-4:50-110.

5. The preparation method according to claim 1, characterized in that: In step S1, the polymerization reaction temperature is 50-70°C and the time is 2-6 hours.

6. The preparation method according to claim 1, characterized in that: In step S3, the lithium salt solution is a solution of at least one of lithium chloride, lithium sulfate and lithium nitrate; and the mass concentration of the lithium salt solution is 10-30%.

7. The preparation method according to claim 1, characterized in that: In step S3, the temperature of the temperature-raising reaction is 80-100° C. and the time is 4-10 hours.

8. The preparation method according to claim 1, characterized in that: In step S3, the activation method is: adding sodium chloride solution to the resin obtained by cooling and filtering after the temperature reaction for activation, the mass ratio of the resin to the sodium chloride solution is 1: (3-10), and the mass concentration of the sodium chloride solution is 1-20%.

9. An adsorbent for extracting lithium from salt lakes, characterized in that: The method is prepared by the method according to any one of claims 1 to 8.

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