Lithium adsorbent and preparation method therefor

Abstract

Disclosed in the present application are a lithium adsorbent and a preparation method therefor. The lithium adsorbent is of a porous structure, and comprises an aluminum-series lithium adsorbent active material and a hydrophilic binder; and the lithium adsorbent has an average pore size of 1-10 nm, a pore volume of 0.65-0.8 ml / g, and a specific surface area of 400-600 m2 / g. The lithium adsorbent of the present application has a specific average pore size of 1-10 nm, the diameter of lithium ions is 0.3 nm, and the pore size of the lithium adsorbent of the present application is larger than the diameter of the ions by three times or more, whereby the lithium ions can quickly go into or out of pores. Therefore, by means of the structure, a high adsorption efficiency and a high desorption efficiency at a high flow rate can be ensured, the desorption of the lithium adsorbent is more concentrated compared with that of a common lithium adsorbent, and a trailing phenomenon is reduced; therefore, the production efficiency of lithium can be effectively improved. Moreover, since the pore size of the product of the present application is smaller than 10 nm, the lithium adsorbent has a low dissolution loss rate and a long service life; and the lithium adsorbent of the present application still has a high adsorption efficiency and a high desorption efficiency after 1000 adsorption-desorption cycles.

Description

A lithium adsorbent and preparation method thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on August 11, 2023, with application number 202311013817.8 and invention name “A lithium adsorbent and its preparation method”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application belongs to the field of lithium extraction by adsorption, and specifically relates to a lithium adsorbent and a preparation method thereof. Background Art

[0004] Lithium is the lightest metallic element in the world and is widely used in rechargeable batteries, glass, ceramics, alloys, lubricants, and pharmaceuticals. Lithium reserves in salt lake brines account for 70-80% of total lithium resources, and extracting lithium from these brines is the primary focus of lithium salt production today. Most of my country's lithium-containing salt lake brines have high magnesium-to-lithium ratios. This high concentration of divalent magnesium ions complicates the separation of lithium ions, creating a bottleneck in lithium extraction from brine.

[0005] Currently, aluminum-based lithium adsorbents are commonly used for magnesium-lithium separation. Existing methods for preparing aluminum-based lithium adsorbents typically involve first preparing a precursor, LiCl·2Al(OH)3·nH2O, followed by drying and pulverization, and then granulation with a binder. This involves numerous steps and a complex process. Furthermore, existing patents generally utilize large pore sizes, which reduces adsorption efficiency and strength.

[0006] Therefore, current aluminum-based lithium adsorbents generally have shortcomings such as low adsorption efficiency, insufficient desorption concentration, and high dissolution loss. These problems have become technical difficulties that urgently need to be solved in the current salt lake lithium extraction field.

[0007] Summary of the Invention

[0008] This application proposes a lithium adsorbent having a pore structure with an average pore size of 1-10 nm. This structure can ensure high adsorption and desorption efficiency at high flow rates, and make desorption more concentrated and reduce tailing compared to general adsorbents. This application adopts the following technical solutions:

[0009] A lithium adsorbent having a porous structure and comprising an aluminum-based lithium adsorbent active material and a hydrophilic binder;

[0010] The lithium adsorbent has an average pore size of 1-10 nm, a pore volume of 0.65-0.8 ml / g, and a specific surface area of ​​400-600 m 2 / g.

[0011] Optionally, the particle size of the lithium adsorbent is 0.8-2.0 mm.

[0012] Optionally, the hydrophilic binder is at least one of polyacrylamide, polyacrylate, dextran, agarose, polyvinyl alcohol, and phenolic resin.

[0013] The preparation method of the lithium adsorbent comprises the following steps:

[0014] Mixing raw materials including a lithium compound, an aluminum compound, a porogen, a hydrophilic binder, and water, and reacting them at 60-100° C. for 2-4 hours to allow the lithium compound and the aluminum compound to react to form an aluminum-based lithium adsorbent active material; the weight ratio of the total weight of the lithium compound, the aluminum compound, and the hydrophilic binder to the porogen is 100:(0.6-20);

[0015] After the hydrophilic binder in the raw material mixture is solidified, the mixture is granulated and dried to obtain the lithium adsorbent.

[0016] Optionally, the weight ratio of the total weight of the lithium compound, the aluminum compound and the hydrophilic binder to the porogen is 100:(2-12).

[0017] Optionally, the aluminum compound is at least one of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum carbonate, aluminum hydroxide, aluminum oxide, and aluminum sol.

[0018] Optionally, the lithium compound is at least one of lithium chloride, lithium carbonate, and lithium hydroxide.

[0019] Optionally, the porogen is an organic porogen, and the organic porogen is at least one of polyvinyl pyrrolidone, polyethylene glycol, a Span emulsifier, and a Tween emulsifier.

[0020] Optionally, the polyvinyl pyrrolidone is PVP K30, and the polyethylene glycol is PEG2000.

[0021] The raw materials contain chloride ions.

[0022] The aluminum-based lithium adsorbent active material refers to LiCl·2Al(OH)3·nH2O material.

[0023] Optionally, the raw material further comprises a filler;

[0024] The weight ratio of the total weight of the lithium compound, the aluminum compound and the hydrophilic binder to the filler is 100:(0-20);

[0025] The weight ratio of the total weight of the lithium compound, the aluminum compound, the hydrophilic binder and the filler to the porogen is 100:(0.6-20).

[0026] Optionally, the weight ratio of the total weight of the lithium compound, the aluminum compound, the hydrophilic binder and the filler to the porogen is 100:(2-12).

[0027] Optionally, the filler is at least one of lithium ore, aluminum ore, and secondary recycled lithium adsorbent;

[0028] Optionally, the filler particle size is less than 0.15 mm.

[0029] Optionally, the secondary recycled lithium adsorbent material is particles smaller than 0.8 mm obtained during the granulation process of the lithium adsorbent.

[0030] Optionally, the hydrophilic binder is at least one of polyacrylamide, polyacrylate, dextran, agarose, polyvinyl alcohol, and phenolic resin.

[0031] Optionally, the raw material further contains a curing agent;

[0032] The curing agent is selected from at least one of azobisisobutyronitrile, potassium persulfate, ammonium persulfate, sulfuric acid, hydrochloric acid, sodium hydroxide, dialdehyde compounds, and epichlorohydrin.

[0033] Optionally, the dialdehyde compound includes at least one of glyoxal, malondialdehyde, succinyldialdehyde, glutaraldehyde, and adipaldehyde.

[0034] Optionally, the weight ratio of the curing agent to the binder is: 1:(1-10).

[0035] Optionally, the molar ratio of the lithium compound to the aluminum compound is 1:(2-6).

[0036] Optionally, the weight ratio of the total weight of the lithium compound and the aluminum compound to the hydrophilic binder is 100:5-25.

[0037] Optionally, the weight ratio of the total weight of the lithium compound and the aluminum compound to water in the raw material is 1:(1-2.5).

[0038] Optionally, the drying is performed at 80-150°C.

[0039] Optionally, the equipment used for the solidification is a double cone dryer or a kneader.

[0040] Optionally, the granulation equipment is a double-roll granulator or a screw extrusion granulator.

[0041] Optionally, the drying equipment used is a tunnel-type hot air circulation drying tunnel electric heating equipment or a rotary kiln.

[0042] The above-mentioned curing equipment can precisely control the reaction temperature and time, making the cured product have higher toughness and improving the yield of finished products with qualified particle size; the drying equipment can achieve zoned temperature control, making the intermediate polymerization molding process controllable and gradually forming the target pore size. During the polymer curing process, the porogen can support the pore structure. After water washing, the water replaces the porogen and the pore structure remains. Due to the current high cost of lithium raw materials, after multiple experiments, the addition of ground lithium ore fillers, ground aluminum ore fillers, and small-particle finished product fillers can reduce costs and reuse waste. In short, the selected curing equipment, granulation equipment, and drying equipment can effectively improve the production efficiency of the curing, granulation, and drying links, reduce manpower, increase lithium production and yield, and effectively reduce costs.

[0043] The technical solution of this application has the following advantages:

[0044] 1. The lithium adsorbent of the present application has a specific average pore size of 1-10nm, and the lithium ion diameter is 0.3nm. The pore size of the lithium adsorbent of the present application is more than three times larger than the ion diameter, so that lithium ions can quickly enter and exit the pores. Therefore, this structure can ensure high adsorption efficiency and high desorption efficiency at high flow rates, and make the desorption more concentrated and reduce the tailing phenomenon compared with general lithium adsorbents, which can effectively improve the production efficiency of lithium. In addition, the pore size of the product of the present application is less than 10nm, which makes the lithium adsorbent dissolution rate low and the service life long. The lithium adsorbent of the present application still has high adsorption efficiency and high desorption efficiency after 1000 adsorption and desorption cycles.

[0045] 2. The preparation method of the present application adopts a one-step method. There is no need to synthesize the aluminum and lithium raw materials into precursors first. Instead, the aluminum and lithium raw materials are directly solidified together with water and a binder. The one-step molding method greatly simplifies the preparation process, improves production efficiency and reduces production costs. DETAILED DESCRIPTION

[0046] The following examples are provided to further better understand the present application, but are not limited to the best implementation mode described herein, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by anyone under the inspiration of the present application or by combining the features of the present application with other prior arts shall fall within the scope of protection of the present application.

[0047] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0048] Example 1

[0049] In a 1000L reactor, add 500kg of water, 260kg of aluminum chloride hexahydrate, 17.5kg of lithium carbonate, 40.5kg of PVP K30, 100kg of sodium hydroxide, 62kg of acrylamide, and 7kg of N,N-methylenebisacrylamide, and react at 60°C under normal pressure with stirring for 2 hours. Transfer the slurry to a 2000L double-cone dryer, add 0.2kg of potassium persulfate, stir and mix thoroughly, heat to 60°C, react for 2 hours, then discharge the slurry, transfer it to a double-roll granulator and chop it into 0.8-2.0mm pieces. Transfer the chopped intermediate to a tunnel-type hot air circulation drying tunnel with electric heating equipment and dry it at 90°C until the moisture content is less than 5% (w / w) to obtain the finished product.

[0050] Example 2

[0051] In a 1000L reactor, add 500kg of water, 400kg of aluminum nitrate nonahydrate, and 8.75kg of lithium carbonate. Neutralize to pH 6 with hydrochloric acid, add 15kg of Span 65, and 40kg of polyvinyl alcohol 0599, and stir at 80°C for 2 hours. The slurry is transferred to a 2000L kneader, and 5kg of borax is added. After stirring and mixing, the mixture is heated to 70°C and reacted at normal pressure for 2 hours. The mixture is discharged and transferred to a double-roll granulator to be chopped into 0.8-2.0mm pieces. The chopped intermediate is then transferred to a double-cone dryer and dried at 80°C until the moisture content is less than 5% (w / w). This yields the finished product.

[0052] Example 3

[0053] In a 1000L reactor, add 500kg of water, 200kg of aluminum hydroxide, 25kg of lithium chloride, 5kg of Span 60, 0.625kg of Tween 80, 17kg of sodium hydroxide, 40kg of acrylamide 1799, and 7kg of N,N-methylenebisacrylamide, and stir at 60°C and atmospheric pressure for 2 hours. Transfer the slurry to a 2000L kneader, add 0.2kg of ammonium persulfate, stir and mix thoroughly, then heat to 70°C and react for 2 hours. Discharge the mixture, transfer it to a double-roll granulator, and chop it into 0.8-2.0mm pieces. Transfer the chopped intermediate to a double-cone dryer and dry it at 130°C until the moisture content is less than 5% (w / w) to obtain the finished product.

[0054] Example 4

[0055] In a 1000L reactor, add 500kg of water, 400kg of industrial-grade acidic aluminum sol (aluminum content 11.1%), 25kg of lithium chloride, 20kg of PEG 20000, 40kg of methyl acrylate, and 5kg of TAIC, and stir at 70°C and atmospheric pressure for 2 hours. The slurry is transferred to a 2000L kneader, 0.1kg of azobisisobutyronitrile is added, and stirring is started to mix thoroughly. The mixture is then heated to 70°C and held for 2 hours. The mixture is then cooled, discharged, and transferred to a roller granulator and chopped into 0.8-2.0mm pieces. The chopped intermediate is then transferred to a tunnel-type hot air circulation drying tunnel with electric heating and dried at 90°C until the moisture content is less than 5% (w / w). This yields the finished product.

[0056] Example 5

[0057] In a 1000L reactor, 500kg of water, 260kg of aluminum chloride hexahydrate, 7.52kg of lithium hydroxide, 30kg of PVPK30, 20kg of aluminum ore ground to 100 mesh (less than 0.15mm) (purchased from Yunnan Wenshan Aluminum, with an Al2O3 content of 58.27%), 100kg of sodium hydroxide, and 40kg of phenol were added, and stirred at 80°C and normal pressure for 2 hours. The above slurry was transferred to a 2000L double-cone dryer, and 20kg of formaldehyde was added. After stirring and mixing, the temperature was raised to 80°C and reacted for 2 hours. The material was discharged and transferred to a roller granulator and cut into 0.8-2.0mm pieces. The cut intermediate was transferred to a tunnel-type hot air circulation drying tunnel with electric heating equipment and dried at 150°C until the water content was less than 5% (w / w) to obtain the finished product.

[0058] Example 6

[0059] In a 1000L reactor, 500kg of water, 260kg of aluminum chloride hexahydrate, 20kg of lithium hydroxide, 35kg of PVPK30, 25kg of lithium ore ground to 100 mesh (less than 0.15mm) (purchased from Nanning Biaohong Trading Co., Ltd., Li2O content of 0.26%), 31kg of the finished product ground to 100 mesh (less than 0.15mm) of Example 1, 100kg of sodium hydroxide, 40kg of dextran 2w, were stirred at 90°C under normal pressure for 1h, cooled, and added 7kg of epichlorohydrin, and then transferred to a kneader, mixed, heated to 70°C, and reacted for 0.5h to form a gel, and then transferred to a screw extrusion granulator to produce a suitable particle size. The cut intermediate was transferred to a tunnel-type hot air circulation drying tunnel electric heating equipment, and the finished product was obtained at 90°C / 6h.

[0060] Example 7

[0061] In a 1000L reactor, add 500kg of water, 400kg of industrial-grade acidic aluminum sol (aluminum content 11.1%), 25kg of lithium chloride, 20kg of PEG20000, and 40kg of agarose. Stir and react at 90°C and atmospheric pressure for 2 hours. Transfer the slurry to a 2000L kneader, stir and mix thoroughly, cool, discharge, and transfer to a double-roll granulator to granulate to the desired particle size.

[0062] Comparative Example 1

[0063] In a 1000L reactor, add 500kg of water, 200kg of aluminum hydroxide, 25kg of lithium chloride, 17kg of sodium hydroxide, and 40kg of polyvinyl alcohol (2399g). Stir at 90°C and atmospheric pressure for 2 hours. Transfer the slurry to a 2000L kneader, add 20kg of adipaldehyde, stir and mix thoroughly, then heat to 70°C and react for 2 hours. Discharge the slurry, transfer it to a double-roll granulator and chop it into 0.8-2.0mm pieces. Transfer the chopped intermediate to a double-cone dryer and dry it at 130°C until the moisture content is less than 5% (w / w) to obtain the finished product.

[0064] Comparative Example 2

[0065] In a 1000L reactor, add 500kg of water, 260kg of aluminum chloride hexahydrate, 17.5kg of lithium carbonate, 1kg of PVP K30, 100kg of sodium hydroxide, 62kg of acrylamide, and 7kg of N,N-methylenebisacrylamide, and stir at 60°C and atmospheric pressure for 2 hours. Transfer the slurry to a 2000L double-cone dryer, add 0.2kg of potassium persulfate, stir and mix thoroughly, heat to 60°C, react for 2 hours, then discharge the slurry, transfer it to a double-roll granulator, and chop it into 0.8-2.0mm pieces. Transfer the chopped intermediate to a tunnel-type hot air circulation drying tunnel with electric heating equipment and dry it at 90°C until the moisture content is less than 5% (w / w) to obtain the finished product.

[0066] Comparative Example 3

[0067] In a 1000L reactor, add 500kg of water, 260kg of aluminum chloride hexahydrate, 17.5kg of lithium carbonate, 100kg of PVP K30, 100kg of sodium hydroxide, 62kg of acrylamide, and 7kg of N,N-methylenebisacrylamide, and stir at 60°C and atmospheric pressure for 2 hours. Transfer the slurry to a 2000L double-cone dryer, add 0.2kg of potassium persulfate, stir and mix thoroughly, heat to 60°C, react for 2 hours, then discharge the slurry, transfer it to a double-roll granulator, and chop it into 0.8-2.0mm pieces. Transfer the chopped intermediate to a tunnel-type hot air circulation drying tunnel with electric heating equipment and dry it at 90°C until the moisture content is less than 5% (w / w) to obtain the finished product.

[0068] Comparative Example 4

[0069] As comparative example 4, JW-LAHS adsorbent purchased from Jiangsu Jiuwu High-Tech Co., Ltd. was used.

[0070] The pore size data detected by JW-BK300 specific surface area and pore size analyzer are as follows:

[0071] Dissolution loss rate assessment:

[0072] The finished product in each embodiment was measured by a measuring cylinder and 1000 ml was loaded into an ion exchange column with an inner diameter of 70 mm and a length of 500 mm. + 972mg / L, Na + 2021mg / L, Ca 2+ 68mg / L, Mg 2+ 116285mg / L, B309mg / L, Li + 56mg / L, Cl - 296732mg / L, SO4 2- 13911mg / L, Si 10mg / L, pH 4.95) for 10 bv (1 bv is 1000 ml), then deionized water for 10 bv, which is one cycle, and after 1000 cycles, the volume of the finished product of each embodiment is measured with a graduated cylinder.

[0073] Dissolution loss rate (%) = (volume of finished product after 1-1000 cycles (ml) / 1000) * 100

[0074] Application Evaluation:

[0075] 1000 ml of the finished products in each embodiment and comparative example and the samples of embodiment 1, embodiment 2 and comparative example 3 after 1000 cycles obtained in the evaluation of dissolution loss rate were loaded into an ion exchange column and the brine of the Qarhan Salt Lake (K + 972mg / L, Na + 2021mg / L, Ca 2+ 68mg / L, Mg 2+ 116285mg / L, B 309mg / L, Li + 56mg / L, Cl - 296732mg / L, SO4 2-13911mg / L, Si 10mg / L, pH4.95) was passed through the column at a rate of 20bv / h (1bv is 1000ml), 40bv was adsorbed, and every 10bv of the adsorption tail liquid mixture was collected for testing the lithium content. After the adsorption was completed, deionized water was used for desorption at a flow rate of 20bv / h, 5bv was desorbed, and every 1bv of the desorption mixture was collected for testing. The test results and the calculation of the adsorption weight and the total desorption amount according to formula (1) and formula (2) are as follows: (1) Total adsorption amount = 56*40-10*(Li + content 0-10bv +Li + content 10-20bv +Li + content 20-30bv +Li + content 30-40bv ) (2) Total desorption amount = 1*(Li + content 1bv +Li + content 2bv +Li + content 3bv +Li + content 4bv +Li + content 5bv )

[0076] The test results are as follows:

[0077] Through application experiments, it can be found that the lithium adsorbent of the present application has a larger adsorption capacity and desorption capacity than the comparative example at high flow rates. The desorption peak is twice that of the sample without porogen, and the desorption is more concentrated and the tailing phenomenon is reduced. Compared with the commercially available comparative example 4 sample, the desorption peak is higher and the desorption volume is larger, which has obvious advantages. From the adsorption and desorption data after 1000 cycles of Example 1, Example 2 and Comparative Example 3, it can be seen that the samples prepared according to the scheme of the present application have a long service life, and the attenuation after 1000 cycles of adsorption and desorption is less than 5%.

[0078] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A lithium adsorbent, characterized in that: The lithium adsorbent is a porous structure, comprising an aluminum-based lithium adsorbent active material and a hydrophilic binder; The lithium adsorbent has an average pore size of 1-10 nm, a pore volume of 0.65-0.8 ml / g, and a specific surface area of ​​400-600 m 2 / g.

2. The lithium adsorbent according to claim 1, characterized in that The particle size of the lithium adsorbent is 0.8-2.0 mm.

3. The lithium adsorbent according to claim 1, characterized in that The hydrophilic binder is at least one of polyacrylamide, polyacrylate, dextran, agarose, polyvinyl alcohol and phenolic resin.

4. A method for preparing a lithium adsorbent, characterized in that: The following steps are involved: Mixing raw materials including a lithium compound, an aluminum compound, a porogen, a hydrophilic binder, and water, and reacting them at 60-100° C. for 2-4 hours to allow the lithium compound and the aluminum compound to react to form an aluminum-based lithium adsorbent active material; the weight ratio of the total weight of the lithium compound, the aluminum compound, and the hydrophilic binder to the weight of the porogen is 100:(0.6-20); After the hydrophilic binder in the raw material mixture is solidified, the lithium adsorbent is obtained by granulation and drying.

5. The preparation method according to claim 4, characterized in that: The aluminum compound is at least one of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum carbonate, aluminum hydroxide, aluminum oxide, and aluminum sol.

6. The preparation method according to claim 4, characterized in that: The lithium compound is at least one of lithium chloride, lithium carbonate and lithium hydroxide.

7. The preparation method according to claim 4, characterized in that: The porogen is an organic porogen, and is selected from at least one of polyvinyl pyrrolidone, polyethylene glycol, a Span emulsifier, and a Tween emulsifier.

8. The preparation method according to claim 4, characterized in that: The raw material also includes a filler; The weight ratio of the total weight of the lithium compound, the aluminum compound and the hydrophilic binder to the weight of the filler is 100:(0-20); The weight ratio of the total weight of the lithium compound, the aluminum compound, the hydrophilic binder and the filler to the porogen is 100:(0.6-20).

9. The preparation method according to claim 8, characterized in that: The filler is at least one of lithium ore, aluminum ore, and lithium adsorbent secondary recycled material; The filler particle size is less than 0.15 mm.

10. The preparation method according to claim 4, characterized in that The hydrophilic binder is at least one of polyacrylamide, polyacrylate, dextran, agarose, polyvinyl alcohol and phenolic resin.

11. The preparation method according to claim 4, characterized in that: The raw material also contains a curing agent; The curing agent is selected from at least one of azobisisobutyronitrile, potassium persulfate, ammonium persulfate, sulfuric acid, hydrochloric acid, sodium hydroxide, dialdehyde compounds, and epichlorohydrin.

12. The preparation method according to claim 11, characterized in that: The dialdehyde compound includes at least one of glyoxal, malondialdehyde, succindialdehyde, glutaraldehyde and adipaldehyde.

13. The preparation method according to claim 4, characterized in that: The molar ratio of the lithium compound to the aluminum compound is 1:(2-6).

14. The preparation method according to claim 4, characterized in that: The weight ratio of the total weight of the lithium compound and the aluminum compound to the hydrophilic binder is 100:(5-25).

15. The preparation method according to claim 4, characterized in that: The weight ratio of the total weight of the lithium compound and the aluminum compound in the raw material to water is 1:(1-2.5).

16. The preparation method according to claim 4, characterized in that: The drying is performed at 80-150°C.

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