Modified aluminum salt lithium extraction adsorbent suitable for low-lithium and high-sulfate brine as well as preparation method and application of modified aluminum salt lithium extraction adsorbent

Abstract

The invention discloses a modified aluminum salt lithium extraction adsorbent suitable for low-lithium and high-sulfate brine. The modified aluminum salt lithium extraction adsorbent comprises an aluminum salt lithium extraction adsorbent and an anionic polymer loaded on the surface of the aluminum salt lithium extraction adsorbent and inserted between layers, the chemical formula of the aluminum salt lithium extraction adsorbent is mLiX. 2Al (OH) 3. NH2O, X is a charge compensation anion, and 0.4 < = mlt; the value of n ranges from 0.2 to 12; the anionic polymer comprises a carbon chain main chain and a polar group side chain rich in lone pair electrons. The modified aluminum salt lithium extraction adsorbent which is large in adsorption capacity, high in lithium extraction efficiency and high in sulfate radical poisoning resistance is prepared by introducing anionic polymers rich in lone pair electron polar groups on the surface and between layers of the aluminum salt lithium extraction adsorbent and combining a one-step composite modification and lithium removal activation process; the method is especially suitable for the fields of extraction of lithium from low-lithium-concentration salt lake raw brine, oilfield brine, sulfate radical type brine and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium extraction from brine, and specifically relates to a modified aluminum salt lithium extraction adsorbent suitable for low-lithium and high-sulfate brine, and a preparation method and application thereof. Background Art

[0002] Lithium is a key element in the transition to clean energy and is widely used in many fields such as new energy, batteries, chemical industry, aerospace, etc. At present, the global demand for lithium is growing exponentially, and the sustainable supply of lithium is particularly important. Salt lake brine contains more than 60% of the world's lithium resources, and compared with lithium extraction from ore, lithium extraction from salt lakes is low-cost and environmentally friendly, and is the future development direction. However, salt lake brine has a complex composition and generally contains high concentrations of chlorides, sulfates, and carbonates of magnesium, sodium, potassium, calcium and other ions. It is urgent to develop highly selective and sustainable salt lake lithium extraction technology.

[0003] The adsorption method for lithium extraction has the characteristics of simple operation, low energy consumption, high selectivity, and green environmental protection. It has gradually developed into the mainstream technology of the salt lake lithium extraction industry. Its core is the key adsorbent material. At present, the developed adsorbents mainly include aluminum salt lithium extraction adsorbents, titanium adsorbents, and manganese adsorbents. Among them, the raw materials of aluminum salt lithium extraction adsorbents are cheap and easy to obtain, the preparation process is simple, and desorption can be completed using fresh water. It is the most successful and widely used lithium extraction adsorbent in industrialization. At present, aluminum salt lithium extraction adsorbents (LiX·2Al(OH)3·nH2O, X is usually Cl - ) has been successfully used to extract lithium from chloride salt lakes, but its promotion and application still has the following major disadvantages: (1) The efficiency of lithium extraction from brine with low lithium concentration (such as raw brine and oilfield brine) is low; (2) The resistance to sulfate is poor. 2- Compared with Cl - It has a higher electronegativity, so in the process of lithium extraction from brine with high sulfate concentration, SO4 2- It is easier to follow Li + Adsorbed into the aluminum salt lithium extraction adsorbent and exists in the form of lithium sulfate, resulting in Li + It is difficult to be eluted, and the adsorbent undergoes irreversible decline in adsorption capacity, which is called "sulfate poisoning".

[0004] Existing aluminum salt lithium extraction adsorbents are mainly suitable for extracting lithium from chloride-type old brine, but are difficult to be used for extracting lithium from raw brine with low lithium concentration, oilfield brine, and sulfate brine, the second largest brine type, which significantly restricts the industrial application of aluminum salt lithium extraction adsorbents. It is of great significance to further develop aluminum salt lithium extraction adsorbents suitable for low-lithium and high-sulfate brine. Summary of the invention

[0005] The main object of the present invention is to provide a modified lithium extraction adsorbent from aluminum salts in view of the existing problems and deficiencies of current lithium extraction adsorbents from aluminum salts, which has a large adsorption capacity, high lithium extraction efficiency, and strong resistance to sulfate poisoning, and is particularly suitable for extracting lithium from raw brines in salt lakes with low lithium concentration, oilfield brines, and sulfate-type brines.

[0006] Another object of the present invention is to provide a preparation method of the modified lithium extraction adsorbent from aluminum salts applicable to low-lithium and high-sulfate brines, and this preparation method has a simple process and strong scalability.

[0007] Another object of the present invention is to provide a lithium extraction application of the lithium extraction adsorbent from aluminum salts in brines with low lithium concentration and / or high sulfate concentration.

[0008] To achieve the above-mentioned invention objects, the specific technical solutions adopted in the present invention are as follows: A modified lithium extraction adsorbent from aluminum salts applicable to low-lithium and high-sulfate brines, which comprises a lithium extraction adsorbent from aluminum salts and an anionic polymer loaded on its surface and inserted into the interlayer; the chemical formula of the lithium extraction adsorbent from aluminum salts is mLiX·2Al(OH)3·nH2O, where X is a charge-compensating anion, 0.4 ≤ m < 1, and n ranges from 0.2 to 12; the anionic polymer contains a carbon chain main chain and polar group side chains rich in lone pairs of electrons.

[0009] Furthermore, the degree of polymerization DP of the carbon chain main chain in the anionic polymer is greater than 100; the number of lone pairs of electrons in the group is greater than 4.

[0010] In the above solution, the carbon chain main chain of the polymer is at least one of polyethylene, polypropylene, and polybutadiene; the polar group side chain contains at least one of a sulfonic acid group, a phosphoric acid group, a sulfonamide group, and a phosphorous acid group.

[0011] In the above solution, the anionic polymer can specifically be at least one of polyvinyl sulfonic acid, polystyrene sulfonic acid, polypropylene sulfonic acid, poly(styrene-propylene) sulfonic acid, sulfonated polyacrylamide, polystyrene sulfonamide, poly(2-acrylamido-2-methyl-1-propanesulfonic acid), sodium polyvinyl sulfonate, sodium polystyrene sulfonate, sodium polypropylene sulfonate, polyvinyl phosphoric acid, polypropylene phosphoric acid, phosphorylated polypropylene sulfonic acid, sodium polyvinyl phosphate, sodium polypropylene phosphate, etc.

[0012] Preferably, the weight-average molecular weight of the anionic polymer is 5000 - 20000000 Da.

[0013] Preferably, X is Cl - or NO3 - .

[0014] In the above solution, for the modified aluminum salt lithium extraction adsorbent, first, a co-precipitation reaction is carried out using a soluble aluminum salt, a lithium salt, and an alkali solution to prepare a lithium intercalated aluminum salt precursor LiX·2Al(OH)3·nH2O. Then, it is mixed with an anionic polymer modifier solution for one-step modification and de-lithiation activation, realizing the surface loading and interlayer insertion modification of the anionic polymer modifier on the surface of mLiX·2Al(OH)3·nH2O (0.4 ≤ m < 1, with a value range of 0.2 to 12), thus obtaining the modified aluminum salt lithium extraction adsorbent.

[0015] The preparation method of the above-mentioned modified aluminum salt lithium extraction adsorbent applicable to low-lithium and high-sulfate brine includes the following steps: (1) Add an aluminum salt and a lithium salt to water and mix evenly to obtain a lithium-aluminum mixed solution. Then, drop it into an alkali solution for co-precipitation reaction until the pH value reaches 3 to 9, age, separate, filter, and dry to obtain a lithium intercalated aluminum salt precursor; (2) Add the obtained lithium intercalated aluminum salt precursor into an anionic polymer modifier solution, carry out a stirring reaction. After the reaction ends, separate, filter, and dry to obtain the modified aluminum salt lithium extraction adsorbent.

[0016] Preferably, the molar ratio of aluminum ions to lithium ions in the lithium-aluminum mixed solution is (1 to 5):1; the concentration of the alkali solution is 1 to 15 mol / L.

[0017] Preferably, the aluminum salt is a soluble aluminum salt, and specifically, at least one of aluminum chloride, aluminum nitrate, etc. can be selected; the lithium salt is a soluble lithium salt, and specifically, at least one of lithium chloride, lithium nitrate, lithium hydroxide, etc. can be selected.

[0018] Preferably, the alkali solution is selected from at least one of sodium hydroxide solution, potassium hydroxide solution, and ammonia water.

[0019] In the above solution, the aging temperature is 0 to 90 °C, and the time is 0.1 to 24 h.

[0020] Preferably, the mass ratio of the lithium intercalated aluminum salt precursor to the anionic polymer modifier solution is 1:(25 to 250).

[0021] Preferably, the concentration of the anionic polymer modifier solution is 0.1 to 10 g / L.

[0022] According to the above solution, the temperature for the stirring reaction is 0 to 80 °C, the time is 1 to 24 h; the stirring rate is 100 to 1000 r / min; during the stirring reaction process, lithium elution activation and the modification of the lithium intercalated aluminum salt precursor by the polymer are simultaneously achieved.

[0023] Preferably, the temperature for the stirring reaction is 25 to 60 °C.

[0024] The present invention also provides an application of the modified aluminum salt lithium extraction adsorbent in extracting lithium from brine with low lithium concentration and / or high sulfate concentration brine.

[0025] Further, in the brine with low lithium concentration, the lithium concentration is below 260 mg / L; in the brine with high sulfate concentration, the sulfate concentration is above 5 g / L.

[0026] Further, the modified aluminum salt lithium extraction adsorbent can achieve a relatively high lithium recovery rate and adsorption capacity in brine with low lithium concentration and / or high sulfate concentration brine; within 10 cycle periods, the adsorption capacity remains unchanged or slightly decreases.

[0027] Further, the modified aluminum salt lithium extraction adsorbent is also applicable in brine with conventional lithium concentration and / or low (or no) sulfate concentration, can achieve a relatively high lithium recovery rate and adsorption capacity, and ensure good cycle stability.

[0028] Compared with the prior art, the beneficial effects of the present invention include: (1) For the modified aluminum salt lithium extraction adsorbent proposed by the present invention, an anionic polymer with side chains rich in lone pair electrons polar groups is introduced on the surface of the traditional aluminum salt adsorbent through hydrogen bond interaction, changing its surface from positive charge to negative charge, enhancing the attraction to Li + , which is beneficial to the enrichment of Li + ; meanwhile, through ion exchange, the anionic polymer is inserted into the interlayer of the aluminum salt lithium extraction adsorbent, promoting the exposure of more adsorption sites, thus significantly improving the lithium extraction efficiency of the adsorbent in brine with low lithium concentration.

[0029] (2) For the modified aluminum salt lithium extraction adsorbent proposed by the present invention, the surface rich in lone pair electrons polar groups loaded through hydrogen bond interaction changes the surface of the adsorbent from positive charge to negative charge, enhancing the repulsion dissipation to SO4 2- ; meanwhile, the main chain of the high-degree-of-polymerization carbon chain polymer in the interlayer serves as an intercalation barrier to enhance the steric hindrance of SO4 2- intercalation, and the polar group side chains rich in lone pair electrons induce electrostatic repulsion to SO4 2- , thus significantly improving the anti-"sulfate poisoning" ability.

[0030] (3) For the modified aluminum salt lithium extraction adsorbent proposed by the present invention, by regulating the side chain groups, the interaction between the adsorbent and coexisting ions in the brine can be regulated, which is beneficial to customizing a stable and efficient aluminum salt lithium extraction adsorbent for different component brines.

[0031] (4)The present invention first proposes to adopt a one-step activation modification reaction to simultaneously achieve the compounding of an anionic polymer and a lithium extraction adsorbent of aluminum salt (loading on the surface of the adsorbent and intercalating into its interlayer) and lithium elution activation. This not only has simple operation and strong scalability, but also can effectively avoid problems and deficiencies such as over-elution of the lithium extraction adsorbent of aluminum salt caused by traditional step-by-step activation and modification means, and at the same time promote the intercalation of the anionic polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 XRD diagrams of the modified lithium extraction adsorbents of aluminum salt and the unmodified lithium extraction adsorbents of aluminum salt prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0033] Figure 2 Surface Zeta potential diagrams of the modified lithium extraction adsorbents of aluminum salt and the unmodified lithium extraction adsorbents of aluminum salt prepared in Example 1, Example 2, Example 3, and Comparative Example 1.

[0034] Figure 3 FTIR diagrams of the modified lithium extraction adsorbents of aluminum salt and the unmodified lithium extraction adsorbents of aluminum salt prepared in Example 1, Example 2, Example 3, and Comparative Example 1.

[0035] Figure 4 Lithium adsorption capacity and recovery diagrams of the lithium extraction adsorbents of aluminum salt prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3 in the oilfield brine of Jianghan Basin.

[0036] Figure 5 Adsorption capacity change diagrams of the lithium extraction adsorbents of aluminum salt prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3 in the Xinjiang salt lake brine within 10 cycle periods. DETAILED DESCRIPTION OF THE INVENTION

[0037] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present disclosure.

[0038] Example 1 A modified lithium extraction adsorbent of aluminum salt applicable to low-lithium and high-sulfate brine, and its preparation method includes the following steps: 1) Take 21.7287 g of AlCl3·6H2O and 1.9076 g of LiCl and dissolve them in 60 mL of deionized water. Then, ultrasonically oscillate for 30 min to uniformly mix them, obtaining a lithium-aluminum mixed solution, where the concentrations of aluminum ions and lithium ions are 1.5 mol / L and 0.75 mol / L, respectively. Then, prepare an 8 mol / L NaOH solution, set the water bath temperature at 75 °C, and the stirring speed at 250 r / min. Slowly drop the lithium-aluminum mixed solution into the NaOH solution, controlling the reaction pH to be 6. After the reaction ends, continue to age at 75 °C for 30 min. After aging, separate and filter. The obtained filter cake is dried at 80 °C for 12 h to obtain a lithium-inserted aluminum salt precursor. 2) Take 5 g of a poly(4-styrenesulfonic acid) solution (PSS) with a molecular weight of approximately 75000 Da and 18 wt%, add 175 g of deionized water, and uniformly mix to prepare a 5 g / L PSS solution. Take 1 g of the lithium-inserted aluminum salt precursor and place it in 100 mL of the PSS solution. Under a water bath temperature of 40 °C and a stirring speed of 100 r / min, stir for 2 h. After the reaction ends, separate and filter the sample. The obtained filter cake is dried at 80 °C for 12 h to obtain a PSS-modified aluminum salt lithium extraction adsorbent.

[0039] Example 2 A modified aluminum salt lithium extraction adsorbent applicable to low-lithium and high-sulfate brines, and its preparation method includes the following steps: Take 56.2695 g of Al(NO3)3·9H2O and 6.8946 g of LiNO3 and dissolve them in 250 mL of deionized water. Then, ultrasonically oscillate for 60 min to uniformly mix them, obtaining a lithium-aluminum mixed solution, where the concentrations of aluminum ions and lithium ions are 0.6 mol / L and 0.4 mol / L, respectively. Then, prepare a 10 mol / L KOH solution, set the water bath temperature at 60 °C, and the stirring speed at 400 r / min. Slowly drop the lithium-aluminum mixed solution into the KOH solution, controlling the reaction pH to be 4. After the reaction ends, continue to age at 60 °C for 2 h. After aging, separate and filter. The obtained filter cake is dried at 50 °C for 18 h to obtain a lithium-inserted aluminum salt precursor. Take 8 g of polyvinylphosphonic acid (PVPA) with a molecular weight of approximately 50000 Da, add 1000 g of deionized water, and uniformly mix to prepare an 8 g / L PVPA solution. Take 2 g of the lithium-inserted aluminum salt precursor and place it in 300 mL of the PVPA solution. Under a water bath temperature of 45 °C and a stirring speed of 150 r / min, stir for 1 h. After the reaction ends, separate and filter the sample. The obtained filter cake is dried at 70 °C for 12 h to obtain a PVPA-modified aluminum salt lithium extraction adsorbent.

[0040] Example 3 A modified aluminum salt lithium extraction adsorbent applicable to low-lithium and high-sulfate brines, and its preparation method includes the following steps: Take 12.0725 g of AlCl₃·6H₂O and 1.379 g of LiNO₃ and dissolve them in 50 mL of deionized water. Then, ultrasonically oscillate for 60 min to make them evenly mixed, obtaining a lithium-aluminum mixed solution, where the concentrations of aluminum ions and lithium ions are 1 mol / L and 0.4 mol / L respectively. Then, prepare 5 mol / L ammonia water, set the water bath temperature at 40 °C, and the stirring speed at 400 r / min. Slowly drip the lithium-aluminum mixed solution into the ammonia water, controlling the reaction pH to be 7. After the reaction ends, continue aging at 30 °C for 8 h. After aging, separate and filter. The obtained filter cake is dried at 60 °C for 24 h to obtain a lithium-inserted aluminum salt precursor. Take 1 g of poly(styrene sulfonamide) (PSAM) with a molecular weight of approximately 8,000,000 Da, add 2000 g of deionized water, and mix evenly to prepare a 0.5 g / L PSAM solution. Take 2 g of the lithium-inserted aluminum salt precursor and place it in 400 mL of the PSAM solution. Under a water bath temperature of 25 °C and a stirring speed of 300 r / min, stir for 8 h. After the reaction ends, separate and filter the sample. The obtained filter cake is dried at 60 °C for 24 h to obtain a PSAM-modified aluminum salt lithium extraction adsorbent.

[0041] Example 4 A modified aluminum salt lithium extraction adsorbent suitable for low-lithium and high-sulfate brine, and its preparation method includes the following steps: Take 38.62912 g of AlCl₃·6H₂O and 1.6958 g of LiCl and dissolve them in 100 mL of deionized water. Then, ultrasonically oscillate for 30 min to make them evenly mixed, obtaining a lithium-aluminum mixed solution, where the concentrations of aluminum ions and lithium ions are 1.6 mol / L and 0.4 mol / L respectively. Then, prepare 12 mol / L KOH solution, set the water bath temperature at 90 °C, and the stirring speed at 150 r / min. Slowly drip the lithium-aluminum mixed solution into the KOH solution, controlling the reaction pH to be 8.5. After the reaction ends, continue aging at 90 °C for 20 min. After aging, separate and filter. The obtained filter cake is dried at 70 °C for 12 h to obtain a lithium-inserted aluminum salt precursor. Take 20 g of a 15 wt% poly(2-acrylamido-2-methyl-1-propanesulfonic acid) solution (PAMPS) with a molecular weight of approximately 20,000,000 Da, add 2980 g of deionized water, and mix evenly to prepare a 1 g / L PAMPS solution. Take 5 g of the lithium-inserted aluminum salt precursor and place it in 250 mL of the PAMPS solution. Under a water bath temperature of 60 °C and a stirring speed of 500 r / min, stir for 4 h. After the reaction ends, separate and filter the sample. The obtained filter cake is dried at 50 °C for 18 h to obtain a PAMPS-modified aluminum salt lithium extraction adsorbent.

[0042] Example 5 The difference between this example and Example 1 is only that the anionic polymer is replaced by poly(4-styrenesulfonic acid sodium) from poly(4-styrenesulfonic acid).

[0043] Example 6 The difference between this example and Example 3 is only that the concentration of the anionic polymer solution is adjusted from 0.5 g / L to 0.1 g / L.

[0044] Comparative Example 1 The difference between this comparative example and Example 1 is only that the adsorbent is not modified with an anionic polymer.

[0045] Comparative Example 2 The difference between this comparative example and Example 1 is only that the concentration of the anionic polymer solution is adjusted from 5 g / L to 20 g / L.

[0046] Comparative Example 3 A method for preparing a modified lithium extraction adsorbent from aluminum salt by first eluting and activating and then modifying, comprising the following steps: 1) Take 1 g of the lithium-inserted aluminum salt precursor prepared in Example 1 and place it in 50 mL of deionized water for elution and activation. At a water bath temperature of 40 °C, stir at 100 r / min for 2 h. After the reaction, separate and filter the sample. The obtained filter cake is dried at 80 °C for 12 h to obtain an aluminum salt lithium extraction adsorbent; 2) 5 g of a poly(4-styrenesulfonic acid) solution (PSS) with a molecular weight of about 75000 Da and 18 wt%, add 85 g of deionized water, and mix evenly to prepare a 10 g / L PSS solution; take 1 g of the activated aluminum salt lithium extraction adsorbent and place it in 50 mL of the PSS solution for modification. At a water bath temperature of 40 °C, stir at 100 r / min for 2 h. After the reaction, separate and filter the sample. The obtained filter cake is dried at 80 °C for 12 h to obtain a PSS-modified aluminum salt lithium extraction adsorbent.

[0047] Characterization and testing: Figure 1 XRD patterns of the modified aluminum salt lithium extraction adsorbents and unmodified aluminum salt lithium extraction adsorbents prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3. From Figure 1It can be seen that the XRD pattern of the adsorbent prepared in Comparative Example 1 showed three sharp characteristic peaks at 2θ = 11.42°, 20.44°, and 23.19°. Comparing with the standard PDF card (No. 31-0700), these characteristic peaks belong to the (003), (100), and (006) crystal planes of typical LiCl·2Al(OH)3·nH2O. The XRD patterns of the lithium extraction adsorbents modified with aluminum salts in Examples 1, 2, and 3 were basically the same as those of the unmodified adsorbent, but the characteristic peak of the (003) crystal plane shifted to a smaller angle, and the layer spacing increased from 7.45 Å to ~7.8 Å, indicating that the anionic polymer was successfully inserted into the interlayer of the adsorbent. The XRD pattern of the product obtained in Comparative Example 2 was almost exactly the same as that of the unmodified adsorbent, and the (003) crystal plane did not shift, so the interlayer intercalation modification effect of the anionic polymer on the lithium extraction adsorbent with aluminum salts could not be effectively achieved. For the XRD pattern of the modified lithium extraction adsorbent with aluminum salts prepared by the two-step method in Comparative Example 3, although the characteristic peak of the (003) crystal plane also shifted to a smaller angle compared with the unmodified adsorbent, the increase in the layer spacing was small; in addition, a relatively sharp characteristic peak (belonging to the characteristic peak of gibbsite) appeared at 2θ ≈ 18°, indicating that the lithium extraction adsorbent with aluminum salts prepared by the two-step method was prone to over-elution of the adsorbent, resulting in partial collapse of the structure.

[0048] Figure 2 Figure Figure 2 shows the surface Zeta potential diagrams of the modified lithium extraction adsorbents with aluminum salts and the unmodified lithium extraction adsorbents with aluminum salts prepared in Examples 1, 2, 3, and Comparative Example 1. From Figure 2 it can be seen that the surface of the adsorbent prepared in Comparative Example 1 carried typical positive charges, which was not conducive to the adsorption of Li + . However, the surfaces of the modified lithium extraction adsorbents with aluminum salts in Examples 1, 2, and 3 were negatively charged, indicating that the anionic polymer was successfully attached to the surface of the adsorbent.

[0049] Figure 3 Figure Figure 3 shows the FTIR diagrams of the modified lithium extraction adsorbents with aluminum salts and the unmodified lithium extraction adsorbents with aluminum salts prepared in Examples 1, 2, 3, and Comparative Example 1. From Figure 3 it can be seen that the FTIR diagram of the modified lithium extraction adsorbent with aluminum salts prepared in Example 1 showed characteristic peaks attributed to S=O at 1184 and 1130 cm -1 , proving the existence of sulfonic acid groups; the FTIR diagram of the modified lithium extraction adsorbent with aluminum salts prepared in Example 2 showed a characteristic peak attributed to P-O at 1076 cm -1 , proving the existence of phosphoric acid groups; the FTIR diagram of the modified lithium extraction adsorbent with aluminum salts prepared in Example 3 showed characteristic peaks attributed to N-H at 1512 and 1458 cm -1 and a characteristic peak attributed to S=O at 1184 cm -1Characteristic peaks attributed to S=O appeared, proving the existence of the sulfonamide group.

[0050] For the brine of an oilfield in the Jianghan Basin (ultra-low lithium concentration brine, specific chemical components are shown in Table 1), the lithium extraction adsorbents prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were used for lithium extraction tests in this brine to measure the lithium adsorption capacity and evaluate the lithium enrichment ability of the adsorbents. The specific lithium adsorption capacity and lithium recovery rate are as Figure 4 shown. The results show that the adsorption capacity and lithium recovery rate of the anion polymer-modified aluminum salt lithium extraction adsorbents prepared in Examples 1 to 3 are significantly improved compared with those before modification, and efficient lithium extraction from ultra-low lithium concentration brine can be achieved. Although the adsorption capacity and lithium recovery rate of the aluminum salt lithium extraction adsorbent obtained in Comparative Example 2 are improved compared with those before modification, they are still significantly smaller than those of the modified aluminum salt lithium extraction adsorbents obtained in Examples 1 to 3 of the present invention. The adsorption capacity and lithium recovery rate of the aluminum salt lithium extraction adsorbent obtained in Comparative Example 3 are significantly reduced.

[0051] Table 1 Composition of Oilfield Brine in Jianghan Basin

[0052] For the brine of a salt lake in Xinjiang (typical sulfate-type brine, specific chemical components are shown in Table 2), the lithium extraction adsorbents prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were operated in long-term cycles in this brine to monitor the change of lithium adsorption capacity and evaluate the "sulfate poisoning" resistance performance of the adsorbents; the specific data of the change of lithium adsorption capacity are as Figure 5 shown. The results show that within the 10 test cycle periods, the adsorption capacity of the anion polymer-modified aluminum salt lithium extraction adsorbents prepared in Examples 1 to 3 remains unchanged or slightly decreases, indicating that the modified aluminum salt lithium extraction adsorbents obtained in the present invention have good "sulfate poisoning" resistance ability. However, the adsorption capacity of the unmodified aluminum salt lithium extraction adsorbent shows an irreversible significant decline, showing poor "sulfate poisoning" resistance ability. For the aluminum salt lithium extraction adsorbent described in Comparative Example 2, the adsorption capacity also shows an irreversible decline. For the aluminum salt lithium extraction adsorbent obtained by the two-step method of first eluting and activating and then modifying in Comparative Example 3, although the anion polymer exists both on the surface and in the interlayer and has certain "sulfate poisoning" resistance performance, the adsorption capacity is very low.

[0053] Table 2 Composition of Salt Lake Brine in Xinjiang

[0054] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Appropriate modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention should all be covered within the protection scope of the present invention, and the protection scope of the present invention is defined by the claims.

Claims

1. A modified aluminum salt lithium extraction adsorbent applicable to low-lithium and high-sulfate brine, characterized in that, It includes a lithium extraction adsorbent from aluminum salts and an anionic polymer loaded on its surface and inserted into the interlayer; the chemical formula of the lithium extraction adsorbent from aluminum salts is mLiX·2Al(OH)3·nH2O, where X is a charge compensation anion, 0.4 ≤ m < 1, and n ranges from 0.2 to 12; the anionic polymer contains a carbon chain main chain and polar group side chains rich in lone pairs of electrons.

2. The modified aluminum salt lithium extraction adsorbent according to claim 1, wherein In the anionic polymer, the degree of polymerization DP of the carbon chain main chain is greater than 100; the number of lone pairs of electrons in the group is greater than 4.

3. The modified aluminum salt lithium extraction adsorbent according to claim 1, wherein, The carbon chain main chain of the polymer is at least one of polyethylene, polypropylene, and polybutadiene; the polar group side chain contains at least one of a sulfonic acid group, a phosphoric acid group, a sulfonamide group, and a phosphorous acid group.

4. The modified aluminum salt lithium extraction adsorbent according to claim 1, wherein The weight-average molecular weight of the anionic polymer is 5000 - 20000000 Da.

5. The modified aluminum salt lithium extraction adsorbent according to claim 1, characterized in that, First, a lithium-inserted aluminum salt precursor LiX·2Al(OH)3·nH2O is prepared by a coprecipitation reaction of a soluble aluminum salt, a lithium salt, and an alkali solution, and then it is mixed with an anionic polymer modifier solution to obtain one-step modification and de-lithiation activation.

6. The preparation method of the modified aluminum salt lithium extraction adsorbent according to any one of claims 1 to 5, characterized in that, It includes the following steps: (1) Add an aluminum salt and a lithium salt to water and mix evenly to obtain a lithium-aluminum mixed solution, then drop it into an alkali solution for coprecipitation reaction until the pH value is 3 - 9, age, separate, filter, and dry to obtain a lithium-inserted aluminum salt precursor; (2) Add the obtained lithium-inserted aluminum salt precursor to an anionic polymer modifier solution, carry out a stirring reaction, and after the reaction is completed, separate, filter, and dry to obtain a modified lithium extraction adsorbent from aluminum salts.

7. The preparation method according to claim 6, characterized in that, The molar ratio of aluminum ions to lithium ions in the lithium-aluminum mixed solution is (1 - 5):

1.

8. The preparation method according to claim 6, characterized in that The concentration of the anionic polymer modifier solution is 0.1 - 10 g / L.

9. The preparation method according to claim 6, wherein The temperature used for the stirring reaction is 0 - 80 °C, and the time is 1 - 24 h.

10. The application of the modified lithium extraction adsorbent from aluminum salts according to claim 1 in extracting lithium from brine with low lithium concentration and / or high sulfate concentration brine; in the low lithium concentration brine, the lithium concentration is below 260 mg / L; in the high sulfate concentration brine, the sulfate concentration is above 5 g / L.

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