Aluminum lithium adsorbent and preparation method thereof

Abstract

The invention belongs to the field of inorganic adsorbent materials, and discloses an aluminum-based lithium adsorbent and a preparation method thereof.The preparation method comprises the steps that a lithium source-containing solution and an aluminum source-containing solution are mixed and added into an alkali liquor to prepare a precursor, then a glue solution with the concentration being 8-12% is prepared, the precursor and a pore-forming agent are mixed to form powder with the particle size D50 being larger than or equal to 0.05 mm and smaller than or equal to 0.2 mm, and the aluminum-based lithium adsorbent is obtained. And adding a part of the organic solvent into the powder to form wet powder, adding a part of the glue solution and the rest of the organic solvent into the wet powder, mixing, finally adding the rest of the glue solution, stirring to prepare slurry, and extruding, baking and crushing the slurry to prepare the aluminum-based lithium adsorbent. By designing the binder and controllably adjusting the mixing process, the aluminum-series lithium adsorbent which does not block the active sites of the adsorption material and has excellent adsorption performance and relatively strong mechanical performance is prepared while good bonding strength is ensured.

Description

Technical Field

[0001] The present application belongs to the field of inorganic adsorbent materials, and specifically relates to an aluminum-based lithium adsorbent and a preparation method thereof. Background Art

[0002] my country's salt lake brine has the characteristics of high magnesium content and low lithium content. 2+ and Li + With similar properties, it is a huge challenge to efficiently separate magnesium and lithium from salt lakes with a high magnesium-to-lithium ratio and to achieve the enrichment and extraction of lithium resources. At present, the developed salt lake brine lithium extraction technologies mainly include adsorption, extraction, membrane, electrochemical, and newly developed reaction / separation coupling technologies. Among them, the adsorption method is expected to make breakthroughs in solving the problem of magnesium-lithium separation and achieving efficient lithium extraction due to its advantages such as high selectivity and convenient recycling. The key to the adsorption method is to design and prepare adsorbents with strong selectivity, good adsorption ability, large adsorption capacity, and good stability.

[0003] Related technologies show that aluminum-based lithium ion sieves have the advantages of good selectivity, high reversibility, fast adsorption rate, good cycle performance, simple preparation process, and green environmental protection. It is currently the only adsorbent for large-scale industrial application in Qinghai Salt Lake in my country. Domestic and foreign scholars have done a lot of research on the molding problem of lithium ion adsorbents. According to the different forms of the prepared adsorbents, the main research methods can be divided into granulation method, film forming method, foaming method, spinning method, composite carrier method, etc. Granulation is currently the most common ion sieve molding technology. The lithium ion sieve adsorbent material prepared by granulation has a high specific surface area, good mechanical stability and water permeability, can adapt to industrial column operation, and has good application prospects.

[0004] Although the granulation method is a commonly used lithium ion sieve forming method, it still faces many challenges in practical application. For example, in the granulation method, the uneven mixing of the precursor and the binder may cause the active sites to be covered by the binder, thereby reducing the lithium extraction efficiency and adsorption capacity of the lithium ion adsorbent. In addition, insufficient hydrophilicity of the binder, uneven mixing or excessive use of the binder may also lead to poor mechanical strength of the adsorbent, easy wear and high dissolution rate. Summary of the invention

[0005] Based on the above, a technical problem to be solved in the present application is to provide an aluminum-based lithium adsorbent and a preparation method thereof. By designing the binder and controllably adjusting the mixing process, an aluminum-based lithium adsorbent is prepared that does not block the active sites of the adsorption material while ensuring good bonding strength, thereby maintaining excellent adsorption performance and high compressive strength.

[0006] The technical solution adopted in this application is:

[0007] On the one hand, the present application provides a method for preparing an aluminum-based lithium adsorbent, comprising the following steps:

[0008] S1, mixing a lithium source solution and an aluminum source solution, adding alkali solution dropwise under stirring, aging, filtering and drying to obtain a precursor;

[0009] S2, dissolving the binder in an organic solvent to prepare a glue solution with a concentration of 8-12%;

[0010] S3, mixing the precursor and the pore-forming agent, and crushing them to form powder, wherein the particle size of the powder is 0.05 mm ≤ D50 ≤ 0.2 mm;

[0011] S4, adding 1-15% of the total amount of organic solvent to the powder, and uniformly mixing at high speed to form wet powder, wherein the high speed rotation speed is 250-500r / min;

[0012] S5, adding 40-60% of the glue and the remaining organic solvent to the wet powder, stirring at a low speed, wherein the low speed is 60-100 r / min;

[0013] S6, adding the remaining glue solution, stirring to obtain slurry, extruding the slurry, baking, and crushing to obtain an aluminum-based lithium adsorbent.

[0014] In step S1, the lithium source and the aluminum source are generally conventional choices in the art. In some embodiments, the lithium source is at least one of lithium hydroxide, lithium acetate, lithium nitrate and lithium chloride, and the aluminum source is aluminum chloride and / or aluminum sulfate.

[0015] In some embodiments, the alkali solution includes sodium hydroxide and / or potassium hydroxide, and the alkali solution is generally added dropwise until the system reaches a neutral pH of 7 and then stopped.

[0016] In some embodiments, the ratio of lithium atoms in the lithium source to aluminum atoms in the aluminum source is 1:1.

[0017] In some embodiments, the aging temperature is 50-70° C., and the aging time is 120-180 min.

[0018] In step S1, the drying step is performed by conventional means in the art, such as drying in an oven at 108°C, and the filtering is also performed by conventional means in the art.

[0019] In step S2, the binder generally includes resin and additives.

[0020] In some embodiments, the resin is a mixture of two or more of polyester polyurethane, polyether polyurethane, phenolic resin and epoxy resin.

[0021] In some embodiments, the auxiliary agent is one or more of diethylamine, isopentylamine, triethylamine and pyrrolidine.

[0022] Wherein, the mass ratio of the resin to the auxiliary agent is 8:1-20:1, for example, 8:1-15:1.

[0023] The mass ratio of the resins prepared by compounding two or more substances can usually be adjusted according to actual needs. For example, the mass ratio of two substances can be (1-3):1, and the mass ratio of three substances can be 2:(1-2):1.

[0024] In the present application, the organic solvent is generally one or more of tetrahydrofuran, dichloromethane and ether.

[0025] In step S3, the pore-forming agent is generally carbon tetrachloride.

[0026] In some embodiments, the mass ratio of the pore former to the binder is 1:2-8:1, for example, 2:1-6:1.

[0027] In some embodiments, the mass ratio of the precursor to the binder is 5:1-10:1, for example, 5:1-8:1.

[0028] In some embodiments, the mixing time is 10-30 min, such as 15-25 min.

[0029] In the present application, the crushing generally adopts the common crushing methods in the art, such as ball milling or air flow crushing. Commonly used crushing devices include planetary ball mills, high-speed swing ball mills or air flow mills.

[0030] In the present application, the crushing time is adaptively adjusted according to the actual situation, such as the selected crushing device, until the powder particle size D50 after crushing meets 0.05mm≤D50≤0.2mm, which usually takes 3-6h.

[0031] In step S4, in some embodiments, the mixing time is 40-100 min, such as 50-80 min.

[0032] In some embodiments, the high speed rotation speed is 300-500r / min.

[0033] In step S5, in some embodiments, the stirring temperature is 30-40°C.

[0034] In some embodiments, the low speed rotation speed is 60-80 r / min.

[0035] In this step of the present application, a too high rotation speed may not effectively improve the mixing effect, but may cause structural damage to the material due to excessive shearing, thereby affecting its performance.

[0036] In step S6, in some embodiments, the stirring speed is 400-500 r / min, and the stirring time is 2-4 h.

[0037] In the present application, the baking temperature is 95-105° C., and the baking time is 20-30 min.

[0038] On the other hand, the present application further provides an aluminum-based lithium adsorbent prepared by the above preparation method. Preferably, the diameter of the aluminum-based lithium adsorbent of the present application is in the range of 0.4-1.2 mm.

[0039] Compared with the prior art, this application has the following advantages:

[0040] In the preparation process of aluminum-based lithium adsorbent, the present application selects a specific compound binder to coordinate with a controllable and adjustable mixing method of the precursor and the binder, while ensuring good bonding strength, the original pore structure of the adsorbent material will not be blocked, and the good adsorption performance of the adsorbent material can be ensured. It can be achieved that during the entire mixing process, the prepared slurry has good uniformity, thereby ensuring that the powder is not easy to fall off and lose, has strong mechanical properties, and the compressive strength of the adsorbent can reach more than 80N / particle. At the same time, it takes into account the characteristics of large adsorption capacity, low dissolution rate and high recyclability. The adsorption capacity of the product is above 9.20mg / g, and the dissolution rate is ≤0.40 after 50 cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a process flow chart for preparing an aluminum-based lithium adsorbent according to any embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail in combination with specific embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present implementation methods, and cannot be understood as limiting the present implementation methods.

[0043] In the description of this embodiment, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0044] In the description of this embodiment, it should be noted that all ranges disclosed in this application will be understood to include any and all sub-ranges included therein. For example, the stated range "3% to 20%" should be deemed to include any and all sub-ranges that start with a minimum value of 3% or greater and end with a maximum value of 20% or less, for example, 4% to 19%, or 4.5% to 15%, or 12% to 13%. At the same time, all ranges disclosed in this application are also deemed to include the endpoints of the ranges, unless otherwise explicitly stated. For example, the range "between 4 and 6" or "4 to 6" or "4-6" should generally be deemed to include the endpoints 4 and 6.

[0045] my country's salt lake brine is characterized by high magnesium content and low lithium content. Due to the similar properties of Mg2+ and Li+, it is a huge challenge to efficiently separate magnesium and lithium from high magnesium-to-lithium ratio salt lakes and realize the enrichment and extraction of lithium resources. Due to its advantages such as high selectivity and convenient recycling, the adsorption method is expected to make breakthroughs in solving the problem of magnesium-lithium separation and realizing efficient lithium extraction. Aluminum-based lithium ion sieves have the advantages of good selectivity, high reversibility, fast adsorption rate, good cycle performance, simple preparation process, and green environmental protection. It is currently the only adsorbent for large-scale industrial application in Qinghai Salt Lake in my country. However, the aluminum-based lithium adsorbent prepared by the granulation method may cause the active sites to be covered by the binder due to the uneven mixing of the precursor and the binder, thereby reducing the lithium extraction efficiency and adsorption capacity of the lithium ion adsorbent. In addition, improper use of the binder will lead to insufficient mechanical strength of the adsorbent, easy wear, and high dissolution rate.

[0046] In order to solve the above problems, the present embodiment provides a method for preparing an aluminum-based lithium adsorbent, comprising the following steps:

[0047] Step S1, mixing a lithium source solution and an aluminum source solution, adding alkaline solution dropwise under stirring, aging, filtering and then drying to obtain a precursor.

[0048] In some embodiments of the present application, the lithium source and aluminum source are generally common raw material sources in the art, for example, the lithium source includes at least one of lithium hydroxide, lithium acetate, lithium nitrate and lithium chloride, and the aluminum source is aluminum chloride and / or aluminum sulfate.

[0049] In some embodiments, in the preparation of the precursor, the atomic ratio of the lithium element in the lithium source to the aluminum element in the aluminum source is 1:1.

[0050] In some embodiments, the alkali solution is selected as conventional in the art, such as sodium hydroxide and / or potassium hydroxide.

[0051] In the present application, an alkali solution is generally added to adjust the system to neutrality, assisted by conventional stirring means in the art, and then aged and filtered, the filter residue is collected, and the filter residue is dried to obtain a precursor of the aluminum-based lithium adsorbent.

[0052] In some embodiments, the aging temperature is 50-70° C., and the aging time is 120-180 min.

[0053] In step S1, the drying step is performed by conventional means in the art, such as drying in an oven at 108°C, and the filtering is also performed by conventional means in the art.

[0054] Step S2, dissolving the binder in an organic solvent to prepare a glue solution with a concentration of 8-12%.

[0055] In the present application, the binder uses resin as the main body and adds a reaction aid, which can ensure good bonding strength while not blocking the original pore structure of the carbonaceous adsorption material, thereby ensuring that the final adsorption product maintains good adsorption performance.

[0056] In some embodiments, the resin is preferably a combination of two or more of polyester polyurethane, polyether polyurethane, phenolic resin and epoxy resin, and the auxiliary agent is preferably one or more of diethylamine, isopentylamine, triethylamine and pyrrolidine.

[0057] In some embodiments, the mass ratio of the resin to the auxiliary agent is 8:1-20:1, preferably 8:1-15:1.

[0058] In the present application, the mass ratio of the resin compounded of two or more substances can usually be adjusted according to actual needs. For example, the mass ratio of the compounded of two substances can be (1-3):1, and the mass ratio of the compounded of three substances can be 2:(1-2):1.

[0059] In some embodiments, the organic solvent is a common reagent in the art, such as one or more of tetrahydrofuran, dichloromethane and diethyl ether.

[0060] The concentration of the above glue solution should not be too high and should be controlled within the range of 8-12%, which can help reduce the formation of micelles in the subsequent mixing process with the powder. At the same time, it should not be too low, which may affect the mechanical strength of the adsorbent product.

[0061] Step S3: mixing the precursor and the pore-forming agent, and crushing them into powder, wherein the particle size of the powder is 0.05 mm ≤ D50 ≤ 0.2 mm.

[0062] In the present application, the pore former is carbon tetrachloride.

[0063] In some embodiments, the mass ratio of the pore former to the binder is 1:2-8:1, for example, 2:1-6:1.

[0064] In some embodiments, the mass ratio of the precursor to the binder is 5:1-10:1, for example, 5:1-8:1.

[0065] In some embodiments, in step S3, the mixing time is 10-30 min, such as 15-25 min.

[0066] Step S4, adding 1-15% of the total amount of organic solvent to the powder, and uniformly mixing at high speed to form wet powder, wherein the high speed rotation speed is 250-500 r / min, for example, 300-500 r / min.

[0067] Step S5, adding 40-60% of the glue solution and the remaining organic solvent to the wet powder, and stirring at a low speed, wherein the low speed is 60-100 r / min, for example, 60-80 r / min.

[0068] In the present application, the amount of glue and organic solvent added in this step must ensure that the viscosity of the system is not too high, and generally the amount of glue added is controlled between 40-60% of the total amount of glue.

[0069] In the present application, after adding a small amount of solvent to the mixed powder, the surface of the powder can be wetted, the surface tension is improved, and the possibility of particle agglomeration is reduced.

[0070] In some embodiments, in step S4, the mixing time is 40-100 min, such as 50-80 min.

[0071] In some embodiments, in step S5, it is generally necessary to maintain the temperature of the system at 30-40° C. to ensure the dispersion and disintegration of micelles in the system and make the slurry more uniform.

[0072] Step S6, adding the remaining glue solution, stirring to obtain slurry, extruding the slurry, baking, and crushing to obtain an aluminum-based lithium adsorbent.

[0073] In some embodiments, stirring is required under high-speed conditions, the stirring speed is 400-500 min, and the stirring time is 2-4 h.

[0074] In some embodiments, the baking temperature is 95-105° C., and the baking time is 20-30 min.

[0075] The present application adopts a unique mixing method in combination with the selection of a binder. Since the agglomeration of particles is well controlled during the process, uneven mixing of the precursor and the binder can be effectively avoided, thereby effectively preventing the powder from falling off and losing. The compressive strength is high, and while ensuring good mixing, the original pore structure of the adsorption material is not blocked, thereby effectively improving the lithium extraction efficiency and adsorption capacity of the lithium ion adsorbent.

[0076] On the other hand, the present application also provides an aluminum-based lithium adsorbent obtained by the above preparation method. Preferably, the diameter of the aluminum-based lithium adsorbent of the present application is in the range of 0.4-1.2 mm.

[0077] The present application is further explained below in conjunction with embodiments.

[0078] All raw materials, reagents, etc. used without specifying the manufacturer are conventional products that can be purchased from the market.

[0079] Phenolic resin was purchased from Shengquan Group

[0080] Epoxy resin purchased from BASF

[0081] Polyether polyurethane purchased from Bailing New Materials

[0082] Polyester polyurethane purchased from Huafeng Group

[0083] Example 1

[0084] Example 1 of the present application provides a method for preparing an aluminum-based lithium adsorbent, comprising the following steps:

[0085] S1: In 5L aluminum chloride solution, the concentration of aluminum chloride is 26.67g / L, add 2.8L LiOH solution (8.5g / L), the atomic ratio of Al and Li is Al:Li=1:1, prepare 5mol / L NaOH aqueous solution, add it dropwise to the aqueous solution containing lithium hydroxide and aluminum chloride under stirring, insert an online pH meter for real-time monitoring, and control the end point of the addition to pH=7. After heating the reaction bottle to 65℃ and aging for 120min, filter the material with a filter and put it into an oven at 108℃ for drying for later use.

[0086] S2: Compound phenolic resin and epoxy resin at a mass ratio of 2:1, then add auxiliary agent diethylamine at a mass ratio of 10:1, mix and prepare 4g of adhesive, which is set aside. Dissolve the prepared adhesive in tetrahydrofuran to prepare 40mL of 10% adhesive solution, which is set aside.

[0087] S3: Next, 40 g of the prepared dried precursor was weighed and mixed with 8 g of carbon tetrachloride for 25 min, and ground into powder with a jet mill to a particle size of D50 = 0.1 mm.

[0088] S4: The mixed powder was uniformly mixed with 10% tetrahydrofuran (200 mL in total volume) at a rotation speed of 350 r / min for 50 min to form a wet powder.

[0089] S5: Add 45% of the total amount of the glue and the remaining 180 mL of tetrahydrofuran used to prepare the wet powder to the wet powder, and mix them evenly under stirring conditions of 40° C. and 70 r / min.

[0090] S6: Finally, the remaining glue solution is added to the obtained mixture, and the mixture is stirred at a speed of 500 r / min for 2 hours to obtain a slurry. The slurry is extruded through a noodle machine, and then baked at 95° C. for 20 minutes and crushed to obtain an aluminum-based lithium adsorbent with a particle diameter of 0.7 mm.

[0091] Example 2

[0092] S1: In 5L aluminum chloride solution, the concentration of aluminum chloride is 26.67g / L, add 2.8L LiOH solution (8.5g / L), the atomic ratio of Al and Li is Al:Li=1:1, prepare 5mol / L NaOH aqueous solution, add it dropwise to the aqueous solution containing lithium hydroxide and aluminum chloride under stirring, insert an online pH meter for real-time monitoring, and control the end point of the addition to pH=7. After heating the reaction bottle to 50℃ and aging for 150min, filter the material with a filter and put it into an oven at 108℃ for drying for later use.

[0093] S2: Compound phenolic resin and polyether polyurethane at a mass ratio of 2:1, then add triethylamine as an auxiliary agent at a mass ratio of 8:1, mix and prepare 4 g of a binder for later use. Dissolve the prepared binder in tetrahydrofuran to prepare 33 mL of a 12% glue solution for later use.

[0094] S3: Next, 20 g of the prepared dried precursor was weighed and mixed with 2.5 g of carbon tetrachloride and stirred for 20 min, and then ground into powder with a jet mill until the particle size D50 was 0.2 mm.

[0095] S4: The mixed powder was uniformly mixed with 10% tetrahydrofuran (100 mL in total volume) at a rotation speed of 300 r / min for 60 min to form a wet powder.

[0096] S5: Add 60% of the total amount of the glue and the remaining 90 mL of tetrahydrofuran used to prepare the wet powder to the wet powder, and mix them evenly under stirring conditions of 60° C. and 80 r / min.

[0097] S6: Finally, the remaining glue solution is added to the obtained mixture, and the mixture is stirred at a speed of 450 r / min for 2.5 hours to obtain a slurry. The slurry is extruded through a noodle machine, and then baked at 95° C. for 20 minutes and crushed to obtain an aluminum-based lithium adsorbent with a particle diameter of 1.2 mm.

[0098] Example 3

[0099] Example 3 of the present application provides a method for preparing an aluminum-based lithium adsorbent, comprising the following steps:

[0100] S1: In 5L aluminum chloride solution, the concentration of aluminum chloride is 26.67g / L, add 2.8L LiOH solution (8.5g / L), the atomic ratio of Al and Li is Al:Li=1:1, prepare 4mol / L KOH aqueous solution, add it dropwise to the aqueous solution containing lithium hydroxide and aluminum chloride under stirring, insert an online pH meter for real-time monitoring, and control the end point of the addition to pH=7. After heating the reaction bottle to 50℃ and aging for 180min, filter the material with a filter and put it into an oven at 108℃ for drying for later use.

[0101] S2: Polyester polyurethane and epoxy resin are compounded at a mass ratio of 3:1, and then the auxiliary agent pyrrolidine is added at a mass ratio of 8:1, and mixed to prepare 4g of adhesive for use. The prepared adhesive is dissolved in tetrahydrofuran to prepare 52mL of 8% adhesive solution for use.

[0102] S3: Next, 40 g of the prepared dried precursor was weighed and mixed with 8 g of carbon tetrachloride and stirred for 20 min, and then ground into powder with a high-speed swing ball mill to a particle size of D50 = 0.05 mm.

[0103] S4: The mixed powder was uniformly mixed with 5% tetrahydrofuran (200 mL in total volume) at a rotation speed of 500 r / min for 80 min to form a wet powder.

[0104] S5: Add 55% of the total amount of the glue and the remaining 190 mL of tetrahydrofuran used to prepare the wet powder to the wet powder, and mix them evenly under stirring conditions of 40° C. and 60 r / min.

[0105] S6: Finally, the remaining glue solution is added to the obtained mixture, and the mixture is stirred at a speed of 400 r / min for 3.5 hours to obtain a slurry. The slurry is extruded through a noodle machine, and then baked at 95° C. for 20 minutes and crushed to obtain an aluminum-based lithium adsorbent with a particle diameter of 0.6 mm.

[0106] Example 4

[0107] Example 4 of the present application provides a method for preparing an aluminum-based lithium adsorbent, which differs from Example 1 in that a gel solution with a concentration of 8% is prepared in step S2, and the obtained particles have a diameter of 0.4 mm.

[0108] Example 5

[0109] Example 5 of the present application provides a method for preparing an aluminum-based lithium adsorbent. The difference from Example 1 is that in step S2, phenolic resin, epoxy resin and polyester polyurethane are compounded in a mass ratio of 2:2:1, and then the auxiliary agent isoamylamine is added in a mass ratio of 10:1, and mixed to obtain 4 g of a binder for later use.

[0110] Comparative Example 1

[0111] Compared with Example 2, the only difference is that in step S2, the binder is phenolic resin.

[0112] Comparative Example 2

[0113] Compared with Example 2, the only difference is that in step S2, the binder is a phenolic resin and an epoxy resin compounded in a mass ratio of 2:1, and does not include an auxiliary agent triethylamine.

[0114] Comparative Example 3

[0115] Compared with Example 2, the only difference is that steps S2-S6 are not included. After step S1, 4 g of the composite resin binder including the auxiliary agent triethylamine is directly dissolved in 100 mL of tetrahydrofuran, and then 20 g of the precursor and 2.5 g of carbon tetrachloride are directly added in sequence to obtain a slurry, which is extruded through a noodle machine, baked at 95° C. for 20 min, and crushed.

[0116] Comparative Example 4

[0117] Compared with Example 2, the only difference is that in step S2, the concentration of the glue solution is 5%.

[0118] Comparative Example 5

[0119] Compared with Example 2, the only difference is that in step S2, the concentration of the glue solution is 20%.

[0120] Comparative Example 6

[0121] Compared with Example 2, the only difference is that both steps S4 and S5 are at high speed, and the rotation speed is 300 r / min.

[0122] Comparative Example 7

[0123] Compared with Example 3, the only difference is that the powder particle size D50 in step S3 is 0.01 mm.

[0124] Comparative Example 8

[0125] Compared with Example 2, the only difference is that the powder particle size D50 in step S3 is 0.5 mm.

[0126] Effect Example

[0127] Compressive strength test

[0128] Randomly select the adsorbent products to be tested. At least 50 particles should be used as samples for each test to ensure the reliability of the test results. The test should be carried out in accordance with the national standard GB 3635-1983.

[0129] Adsorbent static adsorption test

[0130] First, weigh 2.5g of aluminum-based lithium adsorbent in a 500mL conical flask, add 250mL of chloride-type salt lake brine, and oscillate at a speed of 150r / min at an ambient temperature of 10-50°C. After reaching adsorption equilibrium, collect the supernatant in the brine, use an ICP analyzer to detect the lithium ion concentration in the solution, and calculate the adsorption amount of the aluminum-based lithium adsorbent by the difference in the two concentrations, in mg / g.

[0131] Adsorbent dissolution rate detection

[0132] The above adsorption experiment was repeated 50 times, and the mass loss of the adsorbent was determined by testing the change in bulk mass before and after adsorption.

[0133] Table 1 shows the compressive strength, adsorption performance, cycle stability and dissolution loss rate of the aluminum-based lithium adsorbents prepared in different embodiments and comparative examples.

[0134] Table 1

[0135]

[0136] Through the overall comparison of the examples and the comparative data, it can be seen that the technical solution requested for protection in the present application can ensure the bonding strength while maintaining the adsorption performance, stability and dissolution rate of the adsorbent at a high level. This is because in the preparation process of the aluminum-based lithium adsorbent, a specific compound binder is selected and coordinated with the improved mixing process of the precursor and the binder. On the one hand, by selecting auxiliary agents and resins, it is easy to form an open-pore permeable adhesive film, which will not block the original pore structure of the adsorbent material while ensuring good bonding strength, thereby ensuring good adsorption performance of the adsorbent material; on the other hand, the unique mixing method of staged dilution can achieve good uniformity in the prepared slurry during the entire mixing process, thereby ensuring that the adsorption performance of the adsorbent is improved.

[0137] Among them, by comparing Example 2 and Comparative Examples 1-2, it can be seen that it is necessary to use two or more resins and add reaction aids to improve the adsorption capacity and cycle stability of the product, and the dissolution loss rate of the adsorbent can also be maintained at a low level.

[0138] By comparing Example 2 and Comparative Example 3, it can be seen that the unique mixing method of the present application greatly improves the final adsorption performance and stability of the adsorbent compared to the conventional process of directly mixing the precursor and the binder at one time. This is because if a large amount of glue is added at one time, the adsorption components in the glue will quickly occupy the adsorption sites on the surface of the adsorbed substance. As the adsorption proceeds, these sites quickly reach a saturated state, and the subsequent adsorption effect is greatly limited; and the mechanical strength of the product is also greatly improved. This is because the segmented process is conducive to a more uniform dispersion of the binder, thereby forming a more stable connection structure at an early stage.

[0139] By comparing Example 2 and Comparative Examples 4-5, it can be seen that the concentration of the binder dissolved in the organic solution should not be too high or too low. A too high concentration may increase the formation of micelles when mixed with the powder later, and a too low concentration may lead to insufficient mechanical strength of the adsorbent, affecting the effect. By comparing Example 2 and Comparative Example 6, it can be seen that although the mechanical strength of the product is not greatly affected, in step S5, due to the addition of the adhesive liquid of the binder, too high a rotation speed may not be able to improve the mixing effect, but may cause the structure of the material to be destroyed due to excessive shearing, affecting its performance, so that the product cannot ensure mechanical strength while also having good adsorption performance.

[0140] It can be seen from Example 2 and Comparative Example 8 as well as Example 3 and Comparative Example 7 that a precursor with a particle size that is too large or too small is not conducive to improving the adsorption performance of the product. A particle size that is too large has a small specific surface area, and the active sites that can be used to adsorb lithium ions are reduced, thereby affecting the adsorption performance of the adsorbent. A precursor with a particle size that is too small is prone to agglomeration during the preparation of the adsorbent to form larger aggregates, which has a negative effect on the adsorption performance.

[0141] In summary, the present application combines the characteristics of the aluminum-based lithium adsorbent itself, designs the binder and adjusts the mixing process to achieve controllable regulation of the process, and can ensure that the active sites of the adsorbent material are not blocked while having good bonding strength, thereby ensuring the adsorbent's excellent adsorption performance, stability and resistance to dissolution, and providing ideas for large-scale production.

[0142] The above is a further detailed description of the present application, which shall not be regarded as a limitation on the specific implementation of the present application. For ordinary technicians in the technical field to which the present application belongs, simple deduction or replacement without departing from the concept of the present application shall fall within the protection scope of the present application.

Claims

1. A method for preparing an aluminum-based lithium adsorbent, characterized in that: The following steps are involved: S1, mixing a lithium source solution and an aluminum source solution, adding alkali solution dropwise under stirring, aging, filtering and drying to obtain a precursor; S2, dissolving the binder in an organic solvent to prepare a glue solution with a concentration of 8-12%; S3, mixing the precursor and the pore-forming agent, and crushing them to form powder, wherein the particle size of the powder is 0.05 mm ≤ D50 ≤ 0.2 mm; S4, adding 1-15% of the total amount of organic solvent to the powder, and uniformly mixing at high speed to form wet powder, wherein the high speed rotation speed is 250-500r / min; S5, adding 40-60% of the glue and the remaining organic solvent to the wet powder, stirring at a low speed, wherein the low speed is 60-100 r / min; S6, adding the remaining glue solution, stirring to obtain slurry, extruding the slurry, baking, and crushing to obtain an aluminum-based lithium adsorbent.

2. The preparation method according to claim 1, characterized in that: Step S1 satisfies the following conditions: a. The lithium source is at least one of lithium hydroxide, lithium acetate, lithium nitrate and lithium chloride, and the aluminum source is aluminum chloride and / or aluminum sulfate; b. The alkali solution comprises sodium hydroxide and / or potassium hydroxide; c. The ratio of lithium atoms in the lithium source to aluminum atoms in the aluminum source is 1:1; d. The aging temperature is 50-70°C, and the aging time is 120-180 min.

3. The preparation method according to claim 1, characterized in that: In step S2, the binder includes resin and auxiliary agents, the resin is a composite of two or more of polyester polyurethane, polyether polyurethane, phenolic resin and epoxy resin, and the auxiliary agent is one or more of diethylamine, isopentylamine, triethylamine and pyrrolidine.

4. The preparation method according to claim 3, characterized in that: The mass ratio of the resin to the auxiliary agent is 8:1-20:

1.

5. The preparation method according to claim 1, characterized in that: The organic solvent is one or more of tetrahydrofuran, dichloromethane and ether.

6. The preparation method according to claim 1, characterized in that: In step S3, the pore former is carbon tetrachloride, the mass ratio of the pore former to the binder is 1:2-8:1, and the mass ratio of the precursor to the binder is 5:1-10:

1.

7. The preparation method according to claim 1, characterized in that: At least one of the following conditions is met: a. In step S3, the mixing time is 10-30 min; b. In step S4, the mixing time is 40-100 min.

8. The preparation method according to claim 1, characterized in that: In step S5, the stirring temperature is 30-40°C.

9. The preparation method according to claim 1, characterized in that: Step S6 satisfies the following conditions: a. The stirring speed is 400-500r / min, and the stirring time is 2-4h; b. The baking temperature is 95-105°C and the baking time is 20-30 minutes.

10. An aluminum-based lithium adsorbent prepared by the preparation method according to any one of claims 1 to 9.

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