Modified aluminum-based lithium adsorbent suitable for high sulfate brine and preparation method thereof

Abstract

The application discloses a modified aluminum-based lithium adsorbent suitable for high-sulfate brine and a preparation method thereof, and belongs to the technical field of lithium extraction adsorption in salt lakes. The modified aluminum-based lithium adsorbent is prepared by mixing a lithium source solution, an aluminum source solution and an additive solution, and then performing pH adjustment, constant-temperature water bath reaction, aging, drying and granulation. The application uses a compound additive source, can greatly improve the stability and lithium extraction efficiency of the lithium adsorbent, overcomes the problem of poisoning in high-sulfate brine, and is suitable for lithium extraction in high-sulfate brine.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium adsorption from salt lake, and particularly relates to a modified aluminum-based lithium adsorbent suitable for a high-sulfate brine system and a preparation method thereof. BACKGROUND

[0002] The lithium adsorption process has become one of the most promising processes widely used in lithium extraction from salt lakes. At present, the mainstream commercial lithium adsorbent material is an aluminum-based layered hydroxide (Li-Al-LDHs), and its molecular formula is LiX·mAl(OH)3·nH2O, wherein "X" represents an intercalated charge-compensating anion, generally Cl - , F - , Br - , CO3 2- , SO4 2- , etc. These anions are mainly connected to the layer plate through hydrogen bonding, electrostatic attraction and van der Waals force. The aluminum-based lithium adsorbent has many advantages, including simple preparation, fast adsorption speed, high selectivity, good recyclability, and almost no dissolution loss in a neutral pH environment, and can be applied to most salt lake brines (chloride type) in Qinghai area. However, in the high-sulfate brine environment, the traditional mainstream aluminum-based lithium adsorbent will have an irreversible decline in adsorption capacity, which is also known as "adsorbent poisoning". The mechanism of this phenomenon is that the mass transfer process is blocked after the sulfate is inserted into the interlayer of the aluminum-based lithium adsorbent, and the regenerant cannot displace the intercalated sulfate, resulting in the stability of the overall structure and charge capacity of the layered compound, and the lithium ions cannot enter or remove from the molecular structure, finally losing the lithium adsorption activity. In some areas of Qinghai, the sulfate concentration in some deep underground brine is as high as 50 g / L or more, and the traditional mainstream aluminum-based lithium adsorbent cannot be applied. SUMMARY

[0003] In order to overcome the problem of poisoning of the traditional mainstream aluminum-based lithium adsorbent in the high-sulfate brine, the application prepares a modified aluminum-based lithium adsorbent suitable for lithium extraction from high-sulfate brine.

[0004] To solve the above technical problems, the technical scheme adopted by the application is as follows:

[0005] A preparation method of a modified aluminum-based lithium adsorbent suitable for high-sulfate brine, comprising the following steps:

[0006] 1) preparing a lithium source solution, the lithium source being lithium chloride and lithium hydroxide;

[0007] 2) preparing an aluminum source solution;

[0008] 3) preparing an additive solution, using a compounded additive source;

[0009] 4) Slowly mix the prepared lithium source solution, aluminum source solution and additive solution, adjust the pH by adding hydrochloric acid after stabilization, and then perform constant temperature water bath reaction;

[0010] 5) After the reaction is completed, the powder obtained after aging and filtration is dried to obtain the modified aluminum-based lithium adsorbent powder;

[0011] 6) The modified aluminum-based lithium adsorbent powder is wet granulated with PVC and PVDF to obtain the modified aluminum-based lithium adsorbent finished product.

[0012] Further, in step 1), the molar ratio of lithium chloride to lithium hydroxide is 2:1 to 10:1, and the total lithium concentration of the lithium source solution is 1 to 2 mol / L.

[0013] Further, in step 2), the aluminum source is one of aluminum chloride, aluminum hydroxide colloid, sodium metaaluminate, aluminum isopropoxide, aluminum nitrate, and aluminum sulfate, and the aluminum source solution concentration is 1 to 5 mol / L.

[0014] Further, in step 3), the compounded additive source includes an anionic surfactant and a stabilizer, the anionic surfactant is one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium hexadecyl sulfonate, sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate, and the concentration is 0.01 to 0.05 mol / L; the stabilizer is one of sodium chloride, potassium chloride, magnesium chloride, and calcium chloride, and the concentration is 1 to 3 mol / L.

[0015] Further, in step 3), the compounded additive source is preferably sodium dodecyl sulfate and sodium chloride.

[0016] Further, in step 4), the prepared lithium source solution, aluminum source solution and additive solution are slowly mixed according to the molar ratio of lithium source, aluminum source and compounded additive source (0.5 to 1):(0.8 to 1.5):(0.01 to 0.2).

[0017] Further, in step 4), the pH is adjusted to 5.5 to 6.0.

[0018] Further, in step 4), the constant temperature water bath reaction is performed at 50 to 90°C for 4 to 5h.

[0019] Further, in step 5), the aging is 4 to 24h.

[0020] A modified aluminum-based lithium adsorbent suitable for high sulfate brine is prepared by the above preparation method.

[0021] The beneficial effects of the present application are:

[0022] 1. Traditionally prepared aluminum-based lithium adsorbents exhibit severe adsorbent poisoning during circulation in high-sulfate brine, resulting in irreversible degradation of adsorption performance. In contrast, the modified aluminum-based lithium adsorbent prepared in this invention maintains stable lithium adsorption capacity, lithium selectivity, and lithium extraction efficiency during circulation in high-sulfate brine, without significant degradation with increasing cycle count.

[0023] 2. The key to the modified aluminum-based lithium adsorbent prepared in this invention lies in the introduction of a "compound additive source" during the preparation process. Sodium dodecyl sulfate and other components in the compound additive source are anionic surfactants with fixed hydrophilic and lipophilic groups, allowing them to oriented on the surface of the solution. The introduction of this substance significantly reduces the surface tension of the mixed solution. When the lithium source, aluminum source, and additives are slowly mixed, Li-Al-LDHs crystal nuclei are formed. The layered Li-Al-LDHs crystal nuclei have fewer lattice defects during growth, resulting in a larger specific surface area for the target product and higher lithium extraction efficiency. Furthermore, dodecyl sulfate ions insert into the anionic interlayer of the Li-Al-LDHs molecules, greatly increasing the interlayer spacing, which is beneficial for the exchange and mass transfer of sulfate and chloride ions. Sodium chloride in the compound additive source acts as a stabilizer. During the exchange of sulfate and chloride ions, sufficient chloride ions around the layered molecules ensure the stability of the layered structure, which is one of the structural factors contributing to the stable performance of the material during long-term operation. Attached Figure Description

[0024] Figure 1 The image shows a scanning electron microscope image of the aluminum-based lithium adsorbent powder prepared in Example 1, which appears as a cluster of petals.

[0025] Figure 2 This is a physical image of the granulated modified aluminum-based lithium adsorbent product prepared in Example 1.

[0026] Figure 3 This is a comparison chart of the lithium adsorption capacity of two groups of aluminum-based lithium adsorbents operating in the deep brine of Dongtai Jinaier.

[0027] Figure 4 This is a graph showing the change in lithium extraction capacity of the modified aluminum-based lithium adsorbent prepared in Example 1 in different formulations.

[0028] Figure 5 This is a graph showing the change in lithium extraction capacity of traditional aluminum-based lithium adsorbents in different formulations. Detailed Implementation

[0029] To make the various technical features, advantages, or effects of the present invention more apparent and understandable, a detailed description is provided below in conjunction with the accompanying drawings.

[0030] Example 1:

[0031] 1) Preparation of lithium source solution, lithium source components are lithium chloride and lithium hydroxide, the molar ratio is 5:1, and the total lithium concentration is 1.6 mol / L;

[0032] 2) Preparation of aluminum source solution, aluminum source components are aluminum chloride, and the concentration is 2 mol / L;

[0033] 3) Preparation of additive solution, the complex additive source components are sodium dodecyl sulfate and sodium chloride, wherein the concentration of sodium dodecyl sulfate is 0.02 mol / L, and the concentration of sodium chloride is 1.5 mol / L;

[0034] 4) Slowly mix the three solutions prepared above according to the molar ratio of lithium source, aluminum source and complex additive source 0.8:1:0.1, adjust the pH to 5.8 by adding hydrochloric acid after stabilization, and then react in a constant temperature water bath at 70℃ for 4.5h;

[0035] 5) After the reaction is completed, the powder obtained after aging for 12h is dried to obtain the modified aluminum-based lithium adsorbent powder;

[0036] 6) The powder obtained is wet granulated with PVC and PVDF to obtain the modified aluminum-based lithium adsorbent finished product.

[0037] The modified aluminum-based lithium adsorbent powder prepared in this example is in petal cluster shape, as shown in Figure 1 The modified aluminum-based lithium adsorbent material after granulation is in granular shape, the particle size is about 1-2mm, and the lithium adsorption capacity is 6-8mg / g, as shown in Figure 2

[0038] Example 2:

[0039] 1) Preparation of lithium source solution, lithium source components are lithium chloride and lithium hydroxide, the molar ratio is 2:1, and the total lithium concentration is 1 mol / L;

[0040] 2) Preparation of aluminum source solution, aluminum source components are aluminum hydroxide, and the concentration is 1 mol / L;

[0041] 3) Preparation of additive solution, the complex additive source components are sodium dodecyl sulfate and sodium chloride, wherein the concentration of sodium dodecyl sulfate is 0.01 mol / L, and the concentration of sodium chloride is 1 mol / L;

[0042] 4) Slowly mix the three solutions prepared above according to the molar ratio of lithium source, aluminum source and complex additive source 0.5:0.8:0.01, adjust the pH to 5.5 by adding hydrochloric acid after stabilization, and then react in a constant temperature water bath at 50℃ for 5h;

[0043] 5) After the reaction is completed, the powder obtained after aging for 4h is dried to obtain the modified aluminum-based lithium adsorbent powder;

[0044] ​6) The obtained powder is wet granulated with PVC and PVDF to obtain the modified aluminum-based lithium adsorbent product.

[0045] Example 3:

[0046] 1) A lithium source solution is prepared, the lithium source components are lithium chloride and lithium hydroxide, the molar ratio is 10:1, and the total lithium concentration is 2 mol / L;

[0047] 2) An aluminum source solution is prepared, the aluminum source component is aluminum chloride, and the concentration is 5 mol / L;

[0048] 3) An additive solution is prepared, the additive source components are sodium dodecyl sulfate and sodium chloride, the concentration of sodium dodecyl sulfate is 0.05 mol / L, and the concentration of sodium chloride is 3 mol / L;

[0049] 4) The three prepared solutions are slowly mixed according to the molar ratio of lithium source, aluminum source, and complex additive source of 1:1.5:0.2, and after stabilization, hydrochloric acid is added to adjust the pH to 6, and then the reaction is carried out in a constant temperature water bath at 90°C for 4h;

[0050] 5) After the reaction is completed, the obtained powder is aged for 24h, and then dried to obtain the modified aluminum-based lithium adsorbent powder;

[0051] 6) The obtained powder is wet granulated with PVC and PVDF to obtain the modified aluminum-based lithium adsorbent product.

[0052] Experimental test 1:

[0053] Taking the actual brine in the deep layer of Dongtaijinaier underground as an example, the modified aluminum-based lithium adsorbent prepared in Example 1 and the traditional aluminum-based lithium adsorbent are respectively run in the brine system for a long period of time, and the lithium adsorption capacity change is monitored. The composition of the deep layer brine in Dongtaijinaier Lake is shown in Table 1, and the lithium adsorption capacity change data is shown in Figure 3 The results show that during the 15 cycles tested, the lithium adsorption capacity of the modified aluminum-based lithium adsorbent is maintained at 1.4-1.6 g / L, while the capacity of the traditional aluminum-based lithium adsorbent has an irreversible and significant decline in the initial 7 cycles, which strongly proves the lithium extraction activity of the modified aluminum-based lithium adsorbent.

[0054] Table 1. Composition of deep layer brine in Dongtaijinaier Lake

[0055]

[0056] Experimental test 2:

[0057] Lithium-containing brines A, B, C, D and E with different concentrations of sulfate are prepared, wherein the concentrations of sulfate are 10 g / L, 20 g / L, 30 g / L, 40 g / L and 50 g / L respectively, the concentration of Li is controlled at about 500-550 ppm, the concentration of Cl is controlled at 160 g / L, and the pH is adjusted to about 6.0 with hydrochloric acid. The specific components of the prepared solutions are shown in Table 2. The modified aluminum-based lithium adsorbent and the conventional aluminum-based lithium adsorbent of Example 1 are respectively placed in the solutions to test the lithium extraction effect, and the results are shown in Table 3. Figures 4-5 The results show that the modified aluminum-based lithium adsorbent can maintain stable lithium extraction in the lithium-containing brine systems with different concentrations of sulfate. When the concentration of sulfate is less than 30 g / L, the lithium adsorption capacity of the conventional aluminum-based lithium adsorbent can still be maintained stable, and when the concentration of sulfate reaches 40 or 50 g / L, the lithium adsorption capacity of the conventional aluminum-based lithium adsorbent presents a significant decline. The experiment further proves that the modified aluminum-based lithium adsorbent can be applied to the lithium-containing brine with high concentration of sulfate.

[0058] Table 2. Components of lithium-containing brine solutions with different concentrations of sulfate

[0059]

[0060]

[0061] Although the present application has been disclosed as above, it is not intended to limit the present application, and any appropriate modification or equivalent replacement made by those skilled in the art to the technical solutions of the present application shall be covered within the protection scope of the present application, and the protection scope of the present application is defined by the claims.

Claims

1. A method for preparing a modified aluminum-based lithium adsorbent suitable for high sulfate brine, characterized in that, Includes the following steps: 1) Prepare a lithium source solution, the lithium source being lithium chloride and lithium hydroxide; 2) Prepare the aluminum source solution; 3) Prepare the additive solution using a compound additive source; the compound additive source includes anionic surfactants and stabilizers. The anionic surfactant is one of sodium dodecyl sulfate, sodium dodecyl sulfonate, and sodium hexadecyl sulfonate, and the stabilizer is one of sodium chloride, potassium chloride, magnesium chloride, and calcium chloride. 4) Slowly mix the prepared lithium source solution, aluminum source solution and additive solution according to the molar ratio of lithium source, aluminum source and compound additive source (0.5~1):(0.8~1.5):(0.01~0.2). After stabilization, add hydrochloric acid to adjust the pH to 5.5~6.0, and then carry out the reaction in a constant temperature water bath. 5) After the reaction is complete, the mixture is aged, filtered, and then dried to obtain modified aluminum-based lithium adsorbent powder. 6) The modified aluminum-based lithium adsorbent powder is wet-granulated using PVC and PVDF to obtain the finished modified aluminum-based lithium adsorbent.

2. The preparation method according to claim 1, characterized in that, In step 1), the molar ratio of lithium chloride to lithium hydroxide is 2:1 to 10:1, and the total lithium concentration of the lithium source solution is 1 to 2 mol / L.

3. The preparation method according to claim 1, characterized in that, In step 2), the aluminum source is one of aluminum chloride, aluminum hydroxide colloid, aluminum nitrate, or aluminum sulfate, and the concentration of the aluminum source solution is 1~5 mol / L.

4. The preparation method according to claim 1, characterized in that, In step 3), the concentration of the anionic surfactant is 0.01~0.05 mol / L, and the concentration of the stabilizer is 1~3 mol / L.

5. The preparation method according to claim 4, characterized in that, In step 3), the compound additive sources are sodium dodecyl sulfate and sodium chloride.

6. The preparation method according to claim 1, characterized in that, In step 4), the reaction is carried out in a constant temperature water bath at 50~90℃ for 4~5 hours.

7. The preparation method according to claim 1, characterized in that, In step 5), age for 4-24 hours.

8. A modified aluminum-based lithium adsorbent suitable for high-sulfate brine, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

Images