A method for comprehensive recycling of waste lithium titanate anode materials

Abstract

This invention proposes a method for recycling waste lithium titanate anode materials, comprising the following steps: S1: The recycled lithium titanate anode material is calcined once, and the resulting calcined material is mixed with a mixture containing an acidic salt and an additive under pressure. After the reaction, solid-liquid separation is performed to obtain a lithium extraction solution and a leaching residue; wherein, the acidic salt is at least one of a hydrogen sulfate or an ammonium salt; the additive is at least one of barium chloride or calcium chloride; the reaction pressure is 0.3~0.6 MPa. After pressurized selective leaching of the lithium titanate anode material, the lithium extraction solution can be purified to obtain battery-grade lithium carbonate products, and the leaching residue can be used to prepare high-value-added titanium-based adsorbent precursors.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgy and lithium extraction from salt lakes, specifically relating to a method for the comprehensive recycling and utilization of waste lithium titanate anode materials. Background Technology

[0002] With the widespread adoption and application of lithium-ion batteries, many have now reached the end of their lifespan and require recycling. Some of the recycled lithium battery anode materials are lithium titanate. Current recycling methods involve removing the organic solvent and then adding lithium carbonate or titanium dioxide for calcination to synthesize lithium titanate anode materials, without increasing their added value.

[0003] Meanwhile, lithium recovery has become a major research direction in the new energy industry. Compared to lithium recovery from batteries and lithium extraction from ores, lithium extraction from salt lakes has gradually become the mainstream method due to its high efficiency, relatively low cost, and environmental friendliness. Salt lake lithium extraction processes mainly include precipitation, extraction, adsorption, and electrodialysis. Among adsorption methods, aluminum-based adsorption is the most mature and widely used. However, aluminum-based adsorbents have limitations; they are more suitable for chloride-type brines with low sulfate and boron content. They are unsuitable for alkaline brines with excessively high sulfate and boron content, or carbonate-type brines, as sulfate and boron poisoning can easily occur, affecting the stability of the adsorbent. In adsorption lithium extraction, titanium-based adsorbents can be used for alkaline brines with excessively high sulfate or carbonate content, thus compensating for some of the shortcomings of aluminum-based adsorbents and becoming a research focus for major lithium companies. However, the production cost of titanium-based adsorbents is high, necessitating the development of a low-cost preparation method. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for the comprehensive recycling of waste lithium titanate anode materials, which involves targeted treatment of lithium titanate anode materials to prepare high-value-added titanium-based adsorbent precursors, and then granulation to obtain titanium-based adsorbents that can be used for lithium extraction from salt lakes.

[0005] According to a first aspect of the present invention, a method for recycling waste lithium titanate anode materials is provided, comprising the following steps:

[0006] S1: The recovered lithium titanate anode material is roasted once, and the resulting roasted material is mixed with a mixture containing acidic salts and additives and reacted under pressure. After the reaction is completed, solid-liquid separation is performed to obtain lithium extraction liquid and leaching residue.

[0007] The acidic salt is at least one of a hydrogen sulfate or an ammonium salt;

[0008] The auxiliary agent is at least one of barium chloride or calcium chloride;

[0009] The reaction pressure is 0.3~0.6 MPa.

[0010] In some embodiments, the temperature of the first roasting is 400~600℃, and the roasting time is 5~8h.

[0011] In some embodiments, the bisulfate is at least one of sodium bisulfate or potassium bisulfate; and / or, the ammonium salt is at least one of ammonium bisulfate or ammonium chloride.

[0012] This invention utilizes acidic salts and additives to selectively leach lithium titanate anode materials after calcination to remove organic matter. The chemical reaction formula is as follows:

[0013] 4NaHSO4 + 4BaCl2 + Li4Ti5O 12 =4NaCl+4BaSO4↓+4LiCl+5TiO2↓+2H2O;

[0014] 2NH4HSO4 + 2CaCl2 + Li4Ti5O 12 =2NH3↑+2CaSO4↓+4LiCl+5TiO2↓+2H2O.

[0015] The lithium extraction solution obtained after filtration can be used to prepare battery-grade lithium carbonate after impurity removal treatment. The leaching residue contains titanium dioxide, which can be used as a raw material for the preparation of titanium-based adsorbents.

[0016] In some embodiments, the liquid-to-solid ratio of the calcined material to the mixture is (3~8) mL:1g;

[0017] And / or, the concentration of the acidic salt in the mixture is 0.1~3 mol / L;

[0018] And / or, the concentration of the additive in the mixture is 0.1~0.8 mol / L.

[0019] In some embodiments, the reaction temperature is 200~300°C, and the reaction time is 5~8 hours.

[0020] In some implementations, the following steps are also included:

[0021] S2: Mix titanium source, lithium source and dispersant and ball mill, then calcine the resulting ball milled material a second time to obtain titanium-based adsorbent precursor;

[0022] S3: The titanium-based adsorbent precursor is eluted and then granulated to obtain the titanium-based adsorbent;

[0023] The titanium source is the leaching residue described in step S1.

[0024] In some embodiments, in step S2, the lithium source is an organic lithium source; and / or, the dispersant is an alcohol.

[0025] In some preferred embodiments, the organic lithium source is at least one of lithium oxalate or lithium acetate.

[0026] In some preferred embodiments, the alcohol is at least one of methanol, ethanol, or ethylene glycol.

[0027] In some embodiments, in step S2, the rotational speed of the ball mill is 800~2000 r / min; and / or, the mass ratio of the grinding balls to the total mass of the titanium source and lithium source in the ball mill is (4~8):1; and / or, the grinding time is 3~8 h.

[0028] In some embodiments, in step S2, the ball milling material is first subjected to low-temperature drying treatment before secondary calcination. The low-temperature drying temperature is 40~80℃ and the time is 6~10h.

[0029] In some embodiments, in step S2, the temperature of the secondary roasting is 800~1200℃, and the time of the secondary roasting is 6~12h.

[0030] In some embodiments, in step S2, the secondary calcination is carried out under inert gas protection.

[0031] In some embodiments, in step S3, the elution process is as follows: the titanium-based adsorbent precursor is mixed and stirred with an acid solution; the concentration of the acid solution is 0.15~0.4 mol / L, and the elution time is 3~8 h.

[0032] In some preferred embodiments, the liquid-to-solid ratio of the acid solution to the titanium-based adsorbent precursor is (5~8) mL:1g.

[0033] In some preferred embodiments, the acid solution is at least one of hydrochloric acid or sulfuric acid.

[0034] In some embodiments, in step S3, the granulation process is as follows: the eluted titanium-based adsorbent precursor is mixed and stirred with an organic solvent, a binder, a hydrophilic agent, and a pore-forming agent, and then extruded to obtain the titanium-based adsorbent.

[0035] In some preferred embodiments, the organic solvent is NMP (N-methylpyrrolidone); and / or, the binder is PVDF (polyvinylidene fluoride) and PAN (polyacrylonitrile); and / or, the hydrophilic agent is PEG (polyethylene glycol); and / or, the porogen is at least one of sodium chloride or PVP (polyvinylpyrrolidone).

[0036] According to a second aspect of the present invention, a titanium-based adsorbent is provided, prepared by the preparation method described in the first aspect of the present invention, wherein the BET of the titanium-based adsorbent is 10~50m. 2 / g, with a porosity of 30%-50% and a particle size d=0.8~1.5mm; the adsorption capacity of the titanium-based adsorbent is above 3.5g / L.

[0037] According to a third aspect of the present invention, the application of titanium-based adsorbents prepared by the method described in the first aspect of the present invention or the titanium-based adsorbents described in the second aspect of the present invention in lithium extraction from carbonate brine or lithium precipitation mother liquor is proposed.

[0038] According to one embodiment of the present invention, at least the following beneficial effects are achieved:

[0039] 1. This invention innovatively utilizes recycled lithium titanate as a raw material. After removing organic matter from the negative electrode material, selective lithium leaching is achieved through high-pressure leaching with acidic salts and additives, achieving a lithium leaching rate of over 95%. The lithium extraction solution, after impurity removal, yields battery-grade lithium carbonate. The extracted titanium dioxide and dispersant are then combined using a lithium source mechanical ball milling-high-temperature calcination process to prepare a high-value-added titanium-based adsorbent precursor, which is then eluted and granulated to become a lithium metatitanate adsorbent. Thus, this invention achieves high-value recycling and utilization of lithium titanate negative electrode materials from waste lithium-ion batteries through comprehensive recycling and processing.

[0040] 2. This invention, by employing acidic salts and additives, eliminates the need for conventional acid leaching, reducing production costs and making the process environmentally friendly. The addition of additives stabilizes the adsorbent structure and enhances its hardness, reducing titanium loss during the adsorbent desorption process. Furthermore, the titanium-based adsorbent prepared by this invention possesses a porous structure, providing more effective adsorption sites. It can be effectively applied to lithium extraction from alkaline brines, carbonate brines, or lithium precipitation mother liquors, with a working adsorption capacity exceeding 3.5 g / L. This provides new ideas and methods for the research and application of titanium-based adsorbents in lithium extraction from salt lakes. Attached Figure Description

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0042] Figure 1This is a flowchart of Embodiment 1 of the present invention;

[0043] Figure 2 This is a 10,000x magnified SEM image of the titanium-based adsorbent precursor prepared in Example 1 of the present invention.

[0044] Figure 3 This is a 5000x magnified SEM image of the titanium-based adsorbent precursor prepared in Example 2 of the present invention.

[0045] Figure 4 This is a 10,000x magnified SEM image of the titanium-based adsorbent precursor prepared in Example 3 of the present invention.

[0046] Figure 5 The XRD comparison diagrams are of the titanium-based adsorbent precursors prepared in Examples 1-3 of this invention and lithium titanate Li2TiO3.

[0047] Figure 6 This is a magnified SEM image of the internal structure of the granulated titanium-based adsorbent in Example 1 of the present invention, magnified 11,000 times.

[0048] Figure 7 This is a 13,000x magnified SEM image of the internal structure of the granulated titanium-based adsorbent in Example 2 of the present invention. Detailed Implementation

[0049] The following will describe the concept and technical effects of the present invention clearly and completely with reference to the embodiments, so as to fully understand the purpose, features and effects of the present invention.

[0050] Unless otherwise specified, the raw materials, reagents, or apparatus used in the following examples can be obtained from conventional commercial sources or by existing known methods. Specifically, the lithium titanate anode material for lithium batteries is obtained by crushing and sieving lithium battery anode materials, wherein the lithium titanate content is above 80%.

[0051] Example 1

[0052] This embodiment provides a method for the comprehensive recycling and utilization of waste lithium titanate anode materials, such as... Figure 1 As shown, the specific steps include:

[0053] S1: Take the recovered lithium titanate anode material from lithium batteries, calcine it at 500℃ for 6 hours to remove its organic solvent, then transfer 500g of lithium titanate to a reaction vessel, add sodium bisulfate solution and barium chloride auxiliary agent solution to react. The liquid-to-solid ratio in the reaction vessel is 4 mL:1 g, the concentration of sodium bisulfate in the reaction vessel is 2 mol / L, and the concentration of barium chloride is 0.5 mol / L. Raise the temperature to 220℃ and react for 5 hours under a pressure of 0.3 MPa. After the reaction, filter to obtain lithium extraction solution and leaching residue, with a lithium leaching rate of 95.2%. The chemical reaction formula is as follows:

[0054] 4NaHSO4 + 4BaCl2 + Li4Ti5O 12 =4NaCl+4BaSO4↓+4LiCl+5TiO2↓+2H2O;

[0055] The lithium leaching rate is calculated as follows: Leaching rate = C*V / (m*ω), where C is the lithium concentration in the lithium extraction solution (g / L); V is the volume of the lithium extraction solution (L); m is the mass of lithium titanate (g); and ω is the mass fraction of lithium in lithium titanate (g).

[0056] S2: Take 100g of leaching residue obtained in step S1, wash it with water, add 120g of lithium acetate and 600g of ethanol, mix and mechanically ball mill. The mass of the ball milling beads is 900g, the ball milling speed is 1200r / min, and the ball milling is carried out for 4h.

[0057] S3: Transfer the mixture obtained in step S2 to an atmosphere furnace, first dry it at 60℃ for 8 hours, then raise the temperature to 900℃ under nitrogen atmosphere protection and hold it for 8 hours to obtain the titanium-based adsorbent precursor. The titanium-based adsorbent precursor particles are uniform and there is no agglomeration. Its SEM image is shown below. Figure 2 As shown, the XRD pattern is as follows Figure 5 As shown.

[0058] S4: The obtained titanium-based adsorbent precursor was added to 0.15 mol / L hydrochloric acid at a liquid-to-solid ratio of 5 mL:1 g for elution, followed by washing with water and drying. The obtained titanium-based adsorbent powder was granulated. 18 g of PVDF and 1 g of PAN binder were added to 65 g of NMP, and the mixture was stirred in an 80°C water bath for 1 h. Then, 5 g of PEG was added and stirred for 0.5 h. Next, 20 g of sodium chloride and 100 g of titanium-based adsorbent powder were added and stirred for 1 h. After stirring, the mixture was extruded and granulated to obtain the titanium-based adsorbent. Its SEM image is shown below. Figure 6 As shown.

[0059] The obtained titanium-based adsorbent was used to perform single-column adsorption verification on alkaline lithium precipitation mother liquor, and the results are shown in Table 1.

[0060] Table 1 Adsorption Lithium Extraction Data

[0061]

[0062] The working adsorption capacity of titanium-based adsorbents is calculated using the following formula:

[0063] Q e =V1(C0-C) / V2;

[0064] Among them, Q e V1 is the adsorption capacity, in g / L; C0 is the concentration of the original adsorption solution, in g / L; C is the concentration of the adsorption tail solution, in g / L; V2 is the adsorbent volume, in L.

[0065] In this embodiment, the volume of the adsorbed tail liquid V1 is 0.3L, and the volume of the adsorbent V2 is 0.1L. Therefore, the working adsorption capacity Q of the titanium-based adsorbent is... e =0.3L*(1.81g / L-0.61g / L) / 0.1L = 3.6g / L.

[0066] Example 2

[0067] This embodiment provides a method for the comprehensive recycling and utilization of waste lithium titanate anode materials, specifically including the following steps:

[0068] S1: Take the recovered lithium titanate anode material from lithium batteries, calcine it at 500℃ for 8 hours to remove its organic solvent, then transfer 500g of lithium titanate to a reaction vessel, add sodium bisulfate solution and barium chloride auxiliary agent solution to react. The liquid-to-solid ratio in the reaction vessel is 3mL:1g, the concentration of sodium bisulfate in the reaction vessel is 2.8mol / L, and the concentration of barium chloride is 0.8mol / L. Raise the temperature to 230℃ and react at a pressure of 0.35MPa for 8 hours. After the reaction, filter to obtain lithium extraction solution and leaching residue, with a lithium leaching rate of 95.6%. The chemical reaction formula is as follows:

[0069] 4NaHSO4 + 4BaCl2 + Li4Ti5O 12 =4NaCl+4BaSO4↓+4LiCl+5TiO2↓+2H2O;

[0070] S2: Take 100g of leaching residue obtained in step S1, wash it with water, add 120g of lithium acetate and 600g of ethanol, mix and mechanically ball mill. The mass of the ball milling beads is 950g, the ball milling speed is 1100r / min, and the ball milling time is 3h.

[0071] S3: Transfer the mixture obtained in step S2 to an atmosphere furnace, first dry it at 70℃ for 6 hours, then heat it to 850℃ under nitrogen atmosphere protection and hold it for 8 hours to obtain the titanium-based adsorbent precursor. Its SEM image is shown below. Figure 3 As shown, the XRD pattern is as follows Figure 5 As shown.

[0072] S4: The obtained titanium-based adsorbent precursor was added to 0.15 mol / L hydrochloric acid at a liquid-to-solid ratio of 5 mL: 1 g for elution, followed by washing with water and drying. The obtained titanium-based adsorbent powder was granulated. 19 g of PVDF and 2 g of PAN binder were added to 70 g of NMP, and the mixture was stirred in an 80°C water bath for 1 h. Then, 5 g of PEG was added and stirred for 0.5 h. Next, 10 g of PVP and 100 g of titanium-based adsorbent powder were added and stirred for 1 h. After stirring, the mixture was extruded and granulated to obtain the titanium-based adsorbent. Its SEM image is shown below. Figure 7 As shown.

[0073] The obtained titanium-based adsorbent was used to perform single-column adsorption verification on alkaline lithium precipitation mother liquor. The results are shown in Table 2. The calculated working adsorption capacity is 3.75 g / L.

[0074] Table 2 Adsorption Lithium Extraction Data

[0075]

[0076] Example 3

[0077] This embodiment provides a method for the comprehensive recycling and utilization of waste lithium titanate anode materials, specifically including the following steps:

[0078] S1: Take the recovered lithium titanate anode material from lithium batteries, calcine it at 500℃ for 8 hours to remove its organic solvent, then transfer 500g of lithium titanate to a reaction vessel, add sodium bisulfate solution and calcium chloride additive solution to react. The liquid-to-solid ratio in the reaction vessel is 4mL:1g, the concentration of sodium bisulfate in the reaction vessel is 2.6mol / L, and the concentration of calcium chloride is 0.5mol / L. Raise the temperature to 230℃ and react at a pressure of 0.35MPa for 8 hours. After the reaction, filter to obtain lithium extraction solution and leaching residue, with a lithium leaching rate of 95.3%. The chemical reaction formula is as follows:

[0079] 4NaHSO4 + 4CaCl2 + Li4Ti5O 12 =4NaCl+4CaSO4↓+4LiCl+5TiO2↓+2H2O;

[0080] S2: Take 100g of leaching residue obtained in step S1, wash it with water, add 120g of lithium acetate and 600g of ethanol, mix and mechanically ball mill. The mass of the ball milling beads is 950g, the ball milling speed is 1100r / min, and the ball milling time is 3h.

[0081] S3: Transfer the mixture obtained in step S2 to an atmosphere furnace, first dry it at 70°C for 6 hours, then heat it to 850°C under nitrogen atmosphere protection and hold it for 8 hours to obtain the titanium-based adsorbent precursor. Its SEM image is shown below. Figure 3 As shown, the XRD pattern is as follows Figure 5 As shown.

[0082] S4: The obtained titanium-based adsorbent precursor was added to 0.15 mol / L hydrochloric acid at a liquid-to-solid ratio of 5 mL: 1 g for elution, followed by washing with water and drying. The obtained titanium-based adsorbent powder was granulated. 19 g of PVDF and 2 g of PAN binder were added to 70 g of NMP, and the mixture was stirred in an 80°C water bath for 1 h. Then, 5 g of PEG was added and stirred for 0.5 h. Next, 10 g of PVP and 100 g of titanium-based adsorbent powder were added and stirred for 1 h. After stirring, the mixture was extruded and granulated to obtain the titanium-based adsorbent.

[0083] The obtained titanium-based adsorbent was used to perform single-column adsorption verification on alkaline lithium precipitation mother liquor. The results are shown in Table 3. The calculated working adsorption capacity is 3.68 g / L.

[0084] Table 3 Adsorption Lithium Extraction Data

[0085]

[0086] Comparative Example 1

[0087] This comparative example provides a method for the comprehensive recycling and utilization of waste lithium titanate anode materials, specifically including the following steps:

[0088] S1: Take the recovered lithium titanate anode material from lithium batteries, calcine it at 500℃ for 6 hours to remove its organic solvent, then transfer 500g of lithium titanate to a reaction vessel, add sodium bisulfate solution and magnesium chloride solution to react. The liquid-to-solid ratio in the reaction vessel is 4mL:1g, the concentration of sodium bisulfate in the reaction vessel is 2mol / L, and the concentration of magnesium chloride is 0.5mol / L. Raise the temperature to 220℃ and react at a pressure of 0.3MPa for 5 hours. After the reaction, filter to obtain lithium extraction solution and leaching residue. The lithium leaching rate is 92.1%. The chemical reaction formula is as follows:

[0089] 4NaHSO4+ Li4Ti5O 12 =2Na2SO4+2Li2SO4+5TiO2↓+2H2O;

[0090] S2: Take 100g of leaching residue obtained in step S1, wash it with water, add 120g of lithium acetate and 600g of ethanol, mix and mechanically ball mill. The mass of the ball milling beads is 900g, the ball milling speed is 1200r / min, and the ball milling is carried out for 4h.

[0091] S3: Transfer the mixture obtained in step S2 to an atmosphere furnace, dry it at 60°C for 8 hours, and then heat it to 900°C under nitrogen atmosphere protection and keep it at that temperature for 8 hours to obtain the titanium-based adsorbent precursor.

[0092] S4: The obtained titanium-based adsorbent precursor was added to 0.15 mol / L hydrochloric acid at a liquid-to-solid ratio of 5 mL: 1 g for elution, followed by washing with water and drying. The obtained titanium-based adsorbent powder was granulated. 18 g of PVDF and 1 g of PAN binder were added to 65 g of NMP, and the mixture was stirred in an 80°C water bath for 1 h. Then, 5 g of PEG was added and stirred for 0.5 h. Next, 20 g of sodium chloride and 100 g of titanium-based adsorbent powder were added and stirred for 1 h. After stirring, the mixture was extruded and granulated to obtain the titanium-based adsorbent.

[0093] The obtained titanium-based adsorbent was used to perform single-column adsorption verification on alkaline lithium precipitation mother liquor. The results are shown in Table 4. The calculated working adsorption capacity is 3.3 g / L.

[0094] Table 4 Adsorption Lithium Extraction Data

[0095]

[0096] Comparative Example 2

[0097] This comparative example provides a method for the comprehensive recycling and utilization of waste lithium titanate anode materials, specifically including the following steps:

[0098] S1: Take the recovered lithium titanate anode material from lithium batteries, calcine it at 500℃ for 8 hours to remove its organic solvent, then transfer 500g of lithium titanate to a reaction vessel, add sodium bisulfate solution and potassium chloride solution to react. The liquid-to-solid ratio in the reaction vessel is 4mL:1g, the concentration of sodium bisulfate in the reaction vessel is 2mol / L, and the concentration of potassium chloride is 0.5mol / L. Raise the temperature to 210℃ and react at a pressure of 0.3MPa for 7 hours. After the reaction is completed, filter to obtain lithium extraction solution and leaching residue, with a lithium leaching rate of 89.6%.

[0099] S2: Take 100g of leaching residue obtained in step S1, wash it with water, add 110g of lithium acetate and 600g of ethanol, mix and mechanically ball mill. The mass of the ball milling beads is 850g, the ball milling speed is 1200r / min, and the ball milling time is 4h.

[0100] S3: Transfer the mixture obtained in step S2 to an atmosphere furnace, dry it at 60°C for 8 hours, and then heat it to 900°C under nitrogen atmosphere protection and keep it at that temperature for 8 hours to obtain the titanium-based adsorbent precursor.

[0101] S4: The obtained titanium-based adsorbent precursor was added to 0.15 mol / L hydrochloric acid at a liquid-to-solid ratio of 5 mL: 1 g for elution, followed by washing with water and drying. The obtained titanium-based adsorbent powder was granulated. 18 g of PVDF and 1 g of PAN binder were added to 65 g of NMP, and the mixture was stirred in an 80°C water bath for 1 h. Then, 5 g of PEG was added and stirred for 0.5 h. Next, 20 g of sodium chloride and 100 g of titanium-based adsorbent powder were added and stirred for 1 h. After stirring, the mixture was extruded and granulated to obtain the titanium-based adsorbent.

[0102] The obtained titanium-based adsorbent was used to perform single-column adsorption verification on alkaline lithium precipitation mother liquor. The results are shown in Table 5. The calculated working adsorption capacity is 3.2 g / L.

[0103] Table 5 Adsorption Lithium Extraction Data

[0104]

[0105] The titanium-based adsorbents obtained in Examples 1-3 were tested for BET, porosity, and particle size, and the BET of the adsorbents was found to be 10~50 μm. 2 / g, porosity 30%~50%, particle size d=0.8~1.5mm. Among them, the particle size was tested according to GB / T 19077-2024 / ISO 13320:2020; BET was tested according to GB / T 19587-2017 / ISO 9277:2010; and porosity was tested according to GB / T 42697-2023.

[0106] As can be seen from the above examples and comparative examples, the addition of barium chloride or calcium chloride as an auxiliary agent in the examples for selective leaching of lithium resulted in a lithium leaching rate of over 95%. In contrast, the addition of other common chloride salts in the comparative examples did not promote the lithium extraction process, and the lithium leaching rate was less than 93%. Furthermore, the barium sulfate or calcium sulfate generated by the auxiliary agents in the examples effectively enhanced the synthesis of titanium-based adsorbents, reducing titanium dissolution during the adsorbent desorption process and increasing the adsorption capacity of the titanium-based adsorbents, with a working adsorption capacity of over 3.5 g / L.

[0107] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for recycling waste lithium titanate anode materials, characterized in that, Includes the following steps: S1: The recovered lithium titanate anode material is roasted once, and the resulting roasted material is mixed with a mixture containing acidic salts and additives and reacted under pressure. After the reaction is completed, solid-liquid separation is performed to obtain lithium extraction liquid and leaching residue. The acidic salt is a hydrogen sulfate; The auxiliary agent is at least one of barium chloride or calcium chloride; The reaction pressure is 0.3~0.6 MPa.

2. The method according to claim 1, characterized in that, The liquid-to-solid ratio of the calcined material to the mixture is (3~8) mL: 1g; And / or, the concentration of the acidic salt in the mixture is 0.1~3 mol / L; And / or, the concentration of the additive in the mixture is 0.1~0.8 mol / L.

3. The method according to claim 1, characterized in that, The reaction temperature is 200~300℃, and the reaction time is 5~8h.

4. The method according to claim 1, characterized in that, It also includes the following steps: S2: Mix titanium source, lithium source and dispersant and ball mill, then calcine the resulting ball milled material a second time to obtain titanium-based adsorbent precursor; S3: The titanium-based adsorbent precursor is eluted and then granulated to obtain the titanium-based adsorbent. The titanium source is the leaching residue described in step S1.

5. The method according to claim 4, characterized in that, In step S2, the lithium source is an organic lithium source; and / or, the dispersant is an alcohol.

6. The method according to claim 4, characterized in that, In step S2, the temperature of the secondary roasting is 800~1200℃, and the time of the secondary roasting is 6~12h.

7. The method according to claim 4, characterized in that, In step S3, the elution process is as follows: the titanium-based adsorbent precursor is mixed and stirred with acid solution; the concentration of the acid solution is 0.15~0.4 mol / L, and the elution time is 3~8 h.

8. The method according to claim 4, characterized in that, In step S3, the granulation process is as follows: the eluted titanium-based adsorbent precursor is mixed and stirred with an organic solvent, a binder, a hydrophilic agent, and a pore-forming agent, and then extruded to obtain the titanium-based adsorbent.

9. A titanium-based adsorbent, prepared by the method according to any one of claims 4-8, characterized in that, The BET of the titanium-based adsorbent is 10~50m. 2 / g, with a porosity of 30%~50% and a particle size d=0.8~1.5mm; the adsorption capacity of the titanium-based adsorbent is above 3.5g / L.

10. The application of the titanium-based adsorbent prepared by the method of any one of claims 4-8 or the titanium-based adsorbent of claim 9 in the extraction of lithium from carbonate brine or lithium precipitation mother liquor.

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