Manganese-series lithium adsorbent precursor, preparation method thereof and manganese-series lithium adsorbent

Abstract

The invention provides a manganese-series lithium adsorbent precursor, a preparation method thereof and a manganese-series lithium adsorbent, and particularly relates to the technical field of manganese-series lithium adsorbents. The manganese-series lithium adsorbent precursor is a lead-doped manganese-series lithium adsorbent precursor, the chemical formula of the manganese-series lithium adsorbent precursor is Li < 4 > Mn < 5-x > Pb < x > O < 12 >, and the value of x is 1-1.5. Pb < 4 + > ions with the ion radius of 0.077 nm are introduced into Li4Mn5O12, an electron barrier is formed between adjacent Mn < 3 + >, the tendency of disproportionation reaction is effectively inhibited, and the stability of the structure is kept; on the other hand, Pb < 4 + > has higher electronegativity and higher Pb-O bonding capacity, the overall bonding strength of crystal lattices is remarkably enhanced, Jahn-Teller distortion is inhibited, the crystal lattice structure is more compact and stable, an ion migration channel is reduced, and a valence state transition energy barrier is improved, so that dissolution of Mn < 2 + > is inhibited synergistically, the dissolution loss rate is reduced, and the cycling stability is improved.

Description

Technical Field

[0001] This invention relates to the technical field of manganese-based lithium adsorbents, and in particular to a manganese-based lithium adsorbent precursor, its preparation method, and the manganese-based lithium adsorbent itself. Background Technology

[0002] With the rapid development of the lithium-ion battery industry, global demand for lithium resources continues to rise. Lithium extraction from salt lake brine, due to its abundant reserves and low production costs, has become an important approach to lithium resource development. Among numerous lithium extraction technologies, adsorption methods have received widespread attention due to their advantages such as high selectivity, ease of operation, and recyclability. Manganese-based lithium adsorbents, in particular, have gained significant attention for their effectiveness against Li-II. + Excellent selectivity and high saturated adsorption capacity have made them a research hotspot. However, existing manganese-based adsorbents face serious technical bottlenecks in practical applications: during repeated adsorption-desorption cycles, manganese elements in the crystal lattice are prone to dissolution (i.e., "manganese loss"). The dissolution rate of conventional materials usually exceeds 5%, leading to the destruction of the material's crystal structure and rapid performance degradation, which greatly limits its cycle life and industrial application prospects.

[0003] To address the manganese dissolution problem, researchers have attempted to stabilize the manganese-oxygen framework structure through metal doping. For example, doping aluminum into lithium manganese oxide reduced the manganese dissolution rate to 1.2%, but after 50 cycles, the adsorption capacity retention rate was only 70%, indicating unsatisfactory stability. Another technique uses transition metals such as cobalt for doping, which can further reduce the dissolution rate to around 0.84%, but the high cost of cobalt and the associated environmental risks make it difficult to meet the demands of large-scale, low-cost production.

[0004] In addition, existing preparation processes mostly rely on simple co-precipitation, one-step hydrothermal method or direct high-temperature calcination, which lacks effective control over the micro-uniformity of the precursor, resulting in uneven distribution of dopant elements and difficulty in forming a dense and stable lattice structure, thus affecting the overall performance and batch consistency of the material.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a manganese-based lithium adsorbent precursor, its preparation method, and the manganese-based lithium adsorbent, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A first aspect of the present invention provides a manganese-based lithium adsorbent precursor, wherein the manganese-based lithium adsorbent precursor is a lead-doped manganese-based lithium adsorbent precursor; the chemical formula of the lead-doped manganese-based lithium adsorbent precursor is Li4Mn. 5- x Pb xO 12 x takes values ​​from 1 to 1.5.

[0008] Furthermore, the chemical formula of the lead-doped manganese-based lithium adsorbent precursor is Li4Mn. 5-x Pb x O 12 x takes values ​​from 1 to 1.25.

[0009] The second aspect of the present invention provides a method for preparing the precursor of the manganese-based lithium adsorbent, wherein an alkaline solution is added to a mixed solution containing manganese salt and lead salt to react, and after the reaction is completed, the mixture is filtered to obtain a filter cake; the filter cake, lithium compound, complexing agent and water are mixed evenly to form a slurry, and the slurry is spray-dried and then calcined to obtain the precursor of the manganese-based lithium adsorbent.

[0010] Furthermore, the manganese salt is a soluble manganese salt.

[0011] Preferably, the soluble manganese salt includes at least one of MnCl2, MnSO4, Mn(NO3)2, and Mn(CH3COO)2, with MnCl2 being the most preferred.

[0012] Preferably, the lead salt is a soluble lead salt.

[0013] Preferably, the soluble lead salt includes Pb(NO3)2 and / or Pb(CH3COO)2.

[0014] Preferably, in the mixed solution, the concentration of manganese salt is 0.133~0.2 kg / L and the concentration of lead salt is 0.056~0.111 kg / L.

[0015] Preferably, in the mixed solution, the molar ratio of Mn:Pb is (3~4):1.

[0016] Preferably, the alkali in the alkaline solution includes NaOH and / or KOH, with NaOH being the most preferred.

[0017] Preferably, the concentration of the alkaline solution is 0.5~1.5 mol / L.

[0018] Preferably, the pH of the reaction is 8-11.

[0019] Preferably, the alkaline solution is added at a rate of 20-50 kg / h.

[0020] Furthermore, the filtration method includes plate and frame filtration, centrifugal filtration, or pressure filtration.

[0021] Preferably, the preparation method further includes a rinsing process after obtaining the filter cake through filtration, wherein the conductivity of the rinse water is <200 μS·cm. -1 Then finish rinsing.

[0022] Preferably, the moisture content of the filter cake is 40-60%.

[0023] Furthermore, the lithium compound includes LiOH, Li2CO3, and Li2C2O4.

[0024] Preferably, the ratio of lithium in the lithium compound to the total molar amount of manganese and lead in the filter cake is (0.8~0.95):1.

[0025] Preferably, the complexing agent includes at least one of tannic acid, citric acid, ethylenediaminetetraacetic acid, tartaric acid, gallic acid, and phytic acid, with tannic acid being the most preferred.

[0026] Preferably, the ratio of the complexing agent to the total molar amount of manganese and lead in the filter cake is (0.02~0.04):1.

[0027] Furthermore, the viscosity of the slurry is 500~1000 mPa·s.

[0028] Preferably, during the spray drying process, the slurry spraying rate is 50~100 L / h, the inlet air temperature of the drying tower is 200~250℃, and the inlet air volume is 1500~2000 m³ / h. 3 / h.

[0029] Preferably, the powder obtained by spray drying has a moisture content of <5%.

[0030] Furthermore, the calcination process is as follows: first, the temperature is increased to 250-400℃ at a heating rate of 5-10℃ / min, and held for 1-3 hours; then, the temperature is increased to 500-700℃ at a heating rate of 5-10℃ / min, and held for 10-20 hours.

[0031] A third aspect of this invention provides a manganese-based lithium adsorbent, prepared using the aforementioned manganese-based lithium adsorbent precursor; wherein the chemical formula of the manganese-based lithium adsorbent is H4Mn. 5-x Pb x O 12 x takes values ​​from 1 to 1.5.

[0032] Furthermore, in the initial cycle of lithium extraction from the salt lake, the manganese dissolution rate is <50ppm.

[0033] Preferably, the adsorption capacity is ≥7.5g / L.

[0034] Preferably, the adsorption capacity decreases by ≤0.7% after 100 cycles.

[0035] Compared with the prior art, the present invention has at least the following beneficial effects: The manganese-based lithium adsorbent precursor provided by this invention is in Li4Mn5O 12 Pb with an ionic radius of 0.077 nm was introduced into the mixture. 4 + Ions can uniformly replace Mn sites in the crystal lattice, introducing Pb 4+ Ions in adjacent Mn 3+ An electron barrier is formed between them, reducing the two Mn atoms. 3+ The probability of close contact effectively suppresses its tendency to undergo disproportionation reactions and maintains its structural stability; on the other hand, Pb 4+ It exhibits higher electronegativity and stronger Pb-O bonding ability, significantly enhancing the overall lattice bonding strength and suppressing Mn-induced bonding. 3+ The Jahn-Teller distortion caused by this process makes the crystal structure more compact and stable, reduces ion migration channels, and raises the valence transition energy barrier, thereby synergistically suppressing Mn. 2+ Dissolution reduces the rate of dissolution loss and improves cycle stability.

[0036] The preparation method provided by this invention first involves reacting to generate a Mn(OH)₂-Pb(OH)₂ coprecipitated filter cake. Then, a complexing agent is used in the slurry to achieve uniform dispersion of Li, Mn, and Pb at the molecular level. Simultaneously, the complexing agent stabilizes the slurry system, preventing particle sedimentation and improving material homogeneity. Next, spray drying rapidly transforms the slurry into spherical powders with uniform particle size and low moisture content. Finally, calcination yields a manganese-based lithium adsorbent precursor, Li₄Mn, with a complete crystal structure, uniform doping, and stable performance. 5-x Pb x O 12 This preparation method synergistically improves the material's component uniformity, structural density, and phase purity, and the process is highly repeatable, making it suitable for large-scale industrial production.

[0037] The manganese-based lithium adsorbent provided by this invention, given the advantages of the manganese-based lithium adsorbent precursor, has a more stable structure when produced using the precursor, significantly reducing the manganese dissolution rate, improving cycle stability and lithium adsorption capacity, and promoting the industrial application of manganese-based lithium adsorbents. Attached Figure Description

[0038] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1This is a schematic diagram of the preparation steps in Example 1; Figure 2 Li4Mn synthesized in Example 1 3.75 Pb 1.25 O 12 Scanning electron microscope image; Figure 3 The Li4Mn4PbO synthesized in Example 2 12 Scanning electron microscope image; Figure 4 Li4Mn synthesized in Example 3 3.875 Pb 1.125 O 12 Scanning electron microscope image; Figure 5 Li4Mn synthesized in Example 1 3.75 Pb 1.25 O 12 XRD patterns; Figure 6 The Li4Mn4PbO synthesized in Example 2 12 XRD patterns; Figure 7 Li4Mn synthesized in Example 3 3.875 Pb 1.125 O 12 XRD patterns. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0041] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0042] A first aspect of the present invention provides a manganese-based lithium adsorbent precursor, wherein the manganese-based lithium adsorbent precursor is a lead-doped manganese-based lithium adsorbent precursor; the chemical formula of the lead-doped manganese-based lithium adsorbent precursor is Li4Mn. 5- x Pb x O 12 x takes values ​​from 1 to 1.5.

[0043] The manganese-based lithium adsorbent precursor provided by this invention is in Li4Mn5O 12 Pb with an ionic radius of 0.077 nm was introduced into the mixture. 4 + Ions can uniformly replace Mn sites in the crystal lattice, introducing Pb 4+ Ions in adjacent Mn 3+ An electron barrier is formed between them, reducing the two Mn atoms. 3+ The probability of close contact effectively suppresses its tendency to undergo disproportionation reactions and maintains its structural stability; on the other hand, Pb 4+ It exhibits higher electronegativity and stronger Pb-O bonding ability, significantly enhancing the overall lattice bonding strength and suppressing Mn-induced bonding. 3+ The Jahn-Teller distortion caused by this process makes the crystal structure more compact and stable, reduces ion migration channels, and raises the valence transition energy barrier, thereby synergistically suppressing Mn. 2+ Dissolution reduces the rate of dissolution loss and improves cycle stability.

[0044] When x is in the range of 1 to 1.5, it can ensure sufficient Pb doping to achieve effective structural stability and solubility suppression, while avoiding excessive doping that would lead to low trivalent manganese content and affect the number of lithium-ion adsorption active sites, thus balancing the material's cycle stability and high adsorption capacity.

[0045] Furthermore, the chemical formula of the lead-doped manganese-based lithium adsorbent precursor is Li4Mn. 5-x Pb x O 12 x takes values ​​from 1 to 1.25.

[0046] Typical, but not limiting, chemical formulas of lead-doped manganese-based lithium adsorbent precursors can be, for example, Li₄Mn₄PbO₂. 12 Li4Mn 3.5 Pb 1.5 O 12 Li4Mn 3.75 Pb 1.25 O 12 Li4Mn 3.9 Pb 1.1 O 12 Li4Mn 3.8 Pb 1.2 O 12 Li4Mn 3.875 Pb 1.125 O 12 .

[0047] The second aspect of the present invention provides a method for preparing the precursor of the manganese-based lithium adsorbent, wherein an alkaline solution is added to a mixed solution containing manganese salt and lead salt to react, and after the reaction is completed, the mixture is filtered to obtain a filter cake; the filter cake, lithium compound, complexing agent and water are mixed evenly to form a slurry, and the slurry is spray-dried and then calcined to obtain the precursor of the manganese-based lithium adsorbent.

[0048] The preparation method provided by this invention first involves reacting to generate a Mn(OH)₂-Pb(OH)₂ coprecipitated filter cake. Then, a complexing agent is used in the slurry to achieve uniform dispersion of Li, Mn, and Pb at the molecular level. Simultaneously, the complexing agent stabilizes the slurry system, preventing particle sedimentation and improving material homogeneity. Next, spray drying rapidly transforms the slurry into spherical powders with uniform particle size and low moisture content. Finally, calcination yields a manganese-based lithium adsorbent precursor, Li₄Mn, with a complete crystal structure, uniform doping, and stable performance. 5-x Pb x O 12 This preparation method synergistically improves the material's component uniformity, structural density, and phase purity, and the process is highly repeatable, making it suitable for large-scale industrial production.

[0049] Furthermore, the manganese salt is a soluble manganese salt.

[0050] Preferably, the soluble manganese salt includes at least one of MnCl2, MnSO4, Mn(NO3)2, and Mn(CH3COO)2, with MnCl2 being the most preferred.

[0051] Preferably, the lead salt is a soluble lead salt.

[0052] Preferably, the soluble lead salt includes Pb(NO3)2 and / or Pb(CH3COO)2.

[0053] Preferably, in the mixed solution, the concentration of manganese salt is 0.133~0.2 kg / L and the concentration of lead salt is 0.056~0.111 kg / L. This concentration range ensures that the manganese and lead salts are fully dissolved and remain stable in the solution, avoiding premature precipitation or crystallization due to supersaturation, while also ensuring the stability of Mn during subsequent co-precipitation. 2+ With Pb 2+ The ions can uniformly and synchronously form Mn(OH)2-Pb(OH)2 coprecipitates.

[0054] Typically, but not limitingly, the concentration of manganese salt in the mixed solution can be, for example, 0.133 kg / L, 0.15 kg / L, 0.17 kg / L, 0.19 kg / L, or 0.2 kg / L, or any value within the range of 0.133 to 0.2 kg / L; the concentration of lead salt can be, for example, 0.056 kg / L, 0.07 kg / L, 0.08 kg / L, 0.09 kg / L, 0.1 kg / L, or 0.111 kg / L, or any value within the range of 0.056 to 0.111 kg / L.

[0055] Preferably, in the mixed solution, the molar ratio of Mn:Pb is (3~4):1.

[0056] Typically, but not limitingly, the molar ratio of Mn:Pb in the mixed solution can be, for example, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1 or 4:1, or any value in the range of (3~4):1.

[0057] Preferably, the alkali in the alkaline solution includes NaOH and / or KOH, with NaOH being the most preferred.

[0058] Preferably, the concentration of the alkaline solution is 0.5~1.5 mol / L.

[0059] Typically, but not limitingly, the concentration of the alkaline solution can be, for example, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1.1 mol / L, 1.3 mol / L, or 1.5 mol / L, or any value in the range of 0.5 to 1.5 mol / L.

[0060] Preferably, the pH of the reaction is 8-11.

[0061] Typically, but not limitingly, the pH of the reaction can be, for example, 8, 9, 10 or 11, or any value in the range of 8 to 11.

[0062] Preferably, the alkaline solution is added at a rate of 20-50 kg / h.

[0063] Typically, but not limitingly, the rate at which the alkaline solution is added can be, for example, 20 kg / h, 25 kg / h, 30 kg / h, 35 kg / h, 40 kg / h, 45 kg / h, or 50 kg / h, or any value within the range of 20 to 50 kg / h.

[0064] Furthermore, the filtration method includes plate and frame filtration, centrifugal filtration, or pressure filtration.

[0065] Preferably, the preparation method further includes a rinsing process after obtaining the filter cake through filtration, wherein the conductivity of the rinse water is <200 μS·cm.-1 Then finish rinsing.

[0066] Preferably, the moisture content of the filter cake is 40-60%, ensuring material operability while balancing the uniformity of subsequent slurry preparation and the efficiency of spray drying: a moisture content >60% will reduce the solid content, increase drying energy consumption and time, and may lead to spray blockage or uneven particle morphology; a moisture content <40% results in an overly dense and hard filter cake, which is not conducive to the thorough mixing and dispersion of subsequent components such as lithium sources and complexing agents, and is prone to agglomeration, affecting component uniformity. A moisture content within this range helps to form a slurry with moderate fluidity, ensuring uniform distribution of elements at the molecular level, thereby improving the structural consistency and lithium adsorption performance of the final precursor.

[0067] Typically, but not limitingly, the moisture content of the filter cake can be, for example, 40%, 45%, 50%, 55% or 60%, or any value in the range of 40% to 60%.

[0068] Furthermore, the lithium compound includes LiOH, Li2CO3, and Li2C2O4.

[0069] Preferably, the ratio of lithium in the lithium compound to the total molar amount of manganese and lead in the filter cake is (0.8~0.95):1, with the total molar amount of manganese and lead used for comparison.

[0070] Typically, but not limitingly, the ratio of lithium in the lithium compound to the total molar amount of manganese and lead in the filter cake can be, for example, 0.8:1, 0.85:1, 0.9:1 or 0.95:1, or any value in the range of (0.80 to 0.95):1.

[0071] Preferably, the complexing agent includes at least one of tannic acid, citric acid, ethylenediaminetetraacetic acid, tartaric acid, gallic acid, and phytic acid, with tannic acid being the most preferred.

[0072] Preferably, the ratio of the complexing agent to the total molar amount of manganese and lead in the filter cake is (0.02~0.04):1.

[0073] Typically, but not limitingly, the ratio of the complexing agent to the total molar amount of manganese and lead in the filter cake can be, for example, 0.02:1, 0.03:1, or 0.04:1, or any value in the range of (0.02 to 0.04):1.

[0074] Furthermore, the viscosity of the slurry is 500~1000 mPa·s, ensuring that it has good flowability and atomization performance. This ensures that it can be smoothly transported, evenly sprayed, and effectively atomized into fine droplets during the spray drying process, forming precursor powder with narrow particle size distribution and good sphericity. It also prevents the droplets from sticking to the wall or agglomerating due to excessively low viscosity, or causing atomization difficulties, nozzle blockage, and uneven particle size due to excessively high viscosity. This ensures the continuity of spray drying and the consistency of the microstructure of the product.

[0075] Typically, but not limitingly, the viscosity of the slurry can be, for example, 500 mPa·s, 600 mPa·s, 700 mPa·s, 800 mPa·s, 900 mPa·s or 1000 mPa·s, or any value in the range of 500 to 1000 mPa·s.

[0076] Preferably, during the spray drying process, the slurry spraying rate is 50~100 L / h, the inlet air temperature of the drying tower is 200~250℃, and the inlet air volume is 1500~2000 m³ / h. 3 / h.

[0077] Typically, but not limitingly, during the spray drying process, the spraying rate of the slurry can be, for example, 50 L / h, 60 L / h, 70 L / h, 80 L / h, 90 L / h, or 100 L / h, or any value within the range of 50 to 100 L / h; the inlet air temperature of the drying tower can be, for example, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C, or any value within the range of 200 to 250°C; the inlet air volume can be, for example, 1500 m³ / h. 3 / h, 1600m 3 / h, 1700m 3 / h, 1800m 3 / h, 1900m 3 / h or 2000m 3 / h, or 1500~2000m 3 Any value within the range / h.

[0078] Preferably, the powder obtained by spray drying has a moisture content of <5%.

[0079] Furthermore, the calcination process is as follows: first, the temperature is increased to 250-400℃ at a heating rate of 5-10℃ / min, and held for 1-3 hours; then, the temperature is increased to 500-700℃ at a heating rate of 5-10℃ / min, and held for 10-20 hours.

[0080] The low-temperature stage (250~400℃) is mainly used for the slow oxidation of Mn in the Mn(OH)2-Pb(OH)2 co-precipitate. 2+ and Pb2+ Generates the active intermediate Mn 3+ / Mn 4+ and Pb 4+ This avoids excessively rapid heating that could lead to violent local reactions, resulting in sudden gas release, particle breakage, or uneven doping; simultaneously, it provides stable conditions for crystal nucleation. The high-temperature stage (500–700℃) provides sufficient energy to promote lattice rearrangement and crystal growth, allowing Li... + Fully integrated into the crystal lattice and forming a complete Li4Mn 5-x Pb x O 12 The spinel structure ensures crystal phase purity and structural compactness.

[0081] Typical, but not limiting, the calcination process is as follows: first, the temperature is increased to 250℃, 300℃, 350℃, or 400℃ at a heating rate of 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min, and held at that temperature for 1h, 2h, or 3h; then, the temperature is increased to 500℃ or 600℃ at a heating rate of 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min. Alternatively, the temperature can be 700℃, with a holding time of 10h, 12h, 14h, 16h, 18h, or 20h. The heating rate can be any value within the range of 5~10℃ / min, the first-stage heating temperature can be any value within the range of 250~400℃, the first-stage holding time can be any value within the range of 1~3h, the second-stage heating temperature can be any value within the range of 500~700℃, and the second-stage holding time can be any value within the range of 10~20h.

[0082] A third aspect of this invention provides a manganese-based lithium adsorbent, prepared using the aforementioned manganese-based lithium adsorbent precursor; wherein the chemical formula of the manganese-based lithium adsorbent is H4Mn. 5-x Pb x O 12 x takes values ​​from 1 to 1.5.

[0083] The manganese-based lithium adsorbent provided by this invention, given the advantages of the manganese-based lithium adsorbent precursor, has a more stable structure when produced using the precursor, significantly reducing the manganese dissolution rate, improving cycle stability and lithium adsorption capacity, and promoting the industrial application of manganese-based lithium adsorbents.

[0084] Furthermore, in the initial cycle of lithium extraction from the salt lake, the manganese dissolution rate is <50ppm.

[0085] Preferably, the adsorption capacity is ≥7.5g / L.

[0086] Preferably, the adsorption capacity decreases by ≤0.7% after 100 cycles.

[0087] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0088] Example 1 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12 The specific preparation steps are as follows: Figure 1 As shown, it includes: (1) Precipitation reaction: 200 kg of solid MnCl2·4H2O was dissolved in 1000 kg of deionized water, and then 83.6 kg of solid Pb(NO3)2 (the molar ratio of MnCl2·4H2O to Pb(NO3)2 was added, and the mixture was stirred until fully dissolved to obtain a mixed solution of MnCl2 and Pb(NO3)2. Then, the pH of the mixed solution of MnCl2 and Pb(NO3)2 was adjusted to 8 with 0.5 mol / L sodium hydroxide solution at a dropping rate of 20 kg / h to precipitate divalent manganese and divalent lead into Mn(OH)2 and Pb(OH)2 precipitates. The mixture was then subjected to plate and frame filtration, and the filter cake was washed with deionized water for 1 h to make the conductivity of the effluent <200 μS·cm. -1 A filter cake of Mn(OH)2-Pb(OH)2 with a moisture content of 40% was obtained.

[0089] (2) Slurry preparation: Place the Mn(OH)2-Pb(OH)2 filter cake in a mechanically stirred tank, and add 42.5 kg of solid LiOH·H2O to the tank (the molar ratio of Li to H2O is required). + :(Mn 2+ +Pb 2+ The ratio was 0.8:1, and 40 kg of solid tannic acid C was added. 76 H 52 O 46 First, add 50 kg of deionized water, then start mechanical stirring. Continue to slowly add deionized water while monitoring the viscosity of the slurry. Stop adding deionized water when the viscosity reaches 500 mPa·s, and continue mechanical stirring for 3 hours to obtain C. 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 slurry.

[0090] (3) Spray drying: C 76 H 52 O 46 The -LiOH-Mn(OH)2-Pb(OH)2 slurry is injected into the spray drying tower through a high-speed centrifugal spray disc at the top of the tower. The centrifugal spray disc rotates at 500 rpm, the slurry injection rate is 50 L / h, the inlet air temperature is 200℃, and the inlet air volume is adjusted to 1500 m³ / h. 3 / h, ensuring that at this slurry spraying rate, the moisture content of the obtained powder is <5%, and the outlet air temperature of the spray drying tower is 60℃. After the slurry is dried, the C obtained by the above spray drying is... 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 powder was placed entirely in a large ribbon mixer with a ribbon rotation frequency of 10Hz and mixed for 2 hours to obtain a uniformly mixed C. 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 powder.

[0091] (4) Calcination reaction: The uniformly mixed C 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 powder was placed in a mullite mortar with a packing thickness of 5 cm. Calcination was performed in air using a combination of short-duration low-temperature and long-duration high-temperature methods, with a heating rate of 5℃ / min. The calcination was carried out at a low temperature of 250℃ for 1 hour, followed by a high-temperature calcination at 500℃ for 10 hours. After cooling to room temperature, the calcined solid was mechanically pulverized to obtain the manganese-based lithium adsorbent precursor Li4Mn. 3.75 Pb 1.25 O 12 Powder.

[0092] Example 2 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn4PbO. 12 The specific preparation steps are as follows: (1) Precipitation reaction: 300 kg of solid MnCl2·4H2O was dissolved in 1500 kg of deionized water, and then 167.2 kg of solid Pb(NO3)2 (the molar ratio of MnCl2·4H2O to Pb(NO3)2 was added, and the mixture was stirred until fully dissolved to obtain a mixed solution of MnCl2 and Pb(NO3)2. Then, the pH of the mixed solution of MnCl2 and Pb(NO3)2 was adjusted to 11 with 1.5 mol / L sodium hydroxide solution at a dropping rate of 50 kg / h to precipitate divalent manganese and divalent lead into Mn(OH)2 and Pb(OH)2 precipitates. The mixture was then subjected to plate and frame filtration, and the filter cake was washed with deionized water for 3 h to make the conductivity of the effluent <200 μS·cm. -1 A filter cake of Mn(OH)2-Pb(OH)2 with a moisture content of 60% was obtained.

[0093] (2) Slurry preparation: Place the Mn(OH)2-Pb(OH)2 filter cake in a mechanically stirred tank, and add 80.5 kg of solid LiOH·H2O to the tank (the molar ratio of Li to Pb(OH)2 should be equal). + :(Mn 2+ +Pb 2+ The ratio was 0.95:1, and 80 kg of solid tannic acid C was added. 76 H 52 O 46 First, add 80 kg of deionized water, then start mechanical stirring. Continue to slowly add deionized water while monitoring the viscosity of the slurry. Stop adding deionized water when the viscosity reaches 1000 mPa·s, and continue mechanical stirring for 6 hours to obtain C. 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 slurry.

[0094] (3) Spray drying: C 76 H 52 O 46 The -LiOH-Mn(OH)2-Pb(OH)2 slurry is sprayed into the spray drying tower through a high-speed centrifugal spray disc at the top of the tower. The centrifugal spray disc rotates at 800 rpm, the slurry spray rate is 100 L / h, the inlet air temperature is 250℃, and the inlet air volume is adjusted to 2000 m³ / h. 3 / h, ensuring that at this slurry spraying rate, the moisture content of the obtained powder is <5%, and the outlet air temperature of the spray drying tower is 100℃. After the slurry is dried, the C obtained by the above spray drying is... 76 H 52 O 46-LiOH-Mn(OH)2-Pb(OH)2 powder was placed entirely in a large ribbon mixer with a ribbon rotation frequency of 30Hz and mixed for 4 hours to obtain a uniformly mixed C. 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 powder.

[0095] (4) Calcination reaction: The uniformly mixed C 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 powder was placed in a mullite mortar with a packing thickness of 12 cm. Calcination was performed in air using a combination of short-duration low-temperature and long-duration high-temperature methods, with a heating rate of 10℃ / min. The calcination was carried out at a low temperature of 400℃ for 3 hours, followed by a high-temperature calcination at 700℃ for 20 hours. After cooling to room temperature, the calcined solid was mechanically pulverized to obtain the manganese-based lithium adsorbent precursor Li4Mn4PbO. 12 Powder.

[0096] Example 3 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.875 Pb 1.125 O 12 The specific preparation steps are as follows: (1) Precipitation reaction: 250 kg of solid MnCl2·4H2O was dissolved in 1250 kg of deionized water, and then 125.4 kg of solid Pb(NO3)2 (the molar ratio of MnCl2·4H2O to Pb(NO3)2 was added, and the mixture was stirred until fully dissolved to obtain a mixed solution of MnCl2 and Pb(NO3)2. Then, the pH of the mixed solution of MnCl2 and Pb(NO3)2 was adjusted to 9.5 with 1.0 mol / L sodium hydroxide solution, and the dropping rate was 35 kg / h, so that divalent manganese and divalent lead were converted into Mn(OH)2 and Pb(OH)2 precipitates. The mixture was then subjected to plate and frame filter press, and the filter cake was washed with deionized water for 2 h to make the conductivity of the effluent <200 μS·cm. -1 A filter cake of Mn(OH)2-Pb(OH)2 with a moisture content of 50% was obtained.

[0097] (2) Slurry preparation: Place the Mn(OH)2-Pb(OH)2 filter cake in a mechanically stirred reactor, and add 62.9 kg of solid LiOH·H2O to the reactor (the molar ratio of Li to H2O is required). + :(Mn 2+ +Pb 2+ The ratio was 0.875:1, and 60 kg of solid tannic acid C was added. 76 H52 O 46 First, add 65 kg of deionized water, then start mechanical stirring. Continue to slowly add deionized water while monitoring the viscosity of the slurry. Stop adding deionized water when the viscosity reaches 750 mPa·s, and continue mechanical stirring for 4.5 hours to obtain C. 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 slurry.

[0098] (3) Spray drying: C 76 H 52 O 46 The -LiOH-Mn(OH)2-Pb(OH)2 slurry is injected into the spray drying tower through a high-speed centrifugal spray disc at the top. The rotation speed of the high-speed centrifugal spray disc is 650 rpm, the slurry injection rate is 75 L / h, the inlet air temperature of the drying tower is 225℃, and the inlet air volume is adjusted to 1750 m³ / h. 3 / h, ensuring that at this slurry spraying rate, the moisture content of the obtained powder is <5%, and the outlet air temperature of the spray drying tower is 80℃. After the slurry is dried, the C obtained by the above spray drying is... 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 powder was placed entirely in a large ribbon mixer with a ribbon rotation frequency of 20Hz and mixed for 3 hours to obtain a uniformly mixed C. 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 powder.

[0099] (4) Calcination reaction: The uniformly mixed C 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 powder was placed in a mullite mortar with a packing thickness of 8.5 cm. Calcination was performed in air using a combination of short-duration low-temperature and long-duration high-temperature methods, with a heating rate of 7.5 °C / min. The calcination was carried out at a low temperature of 325 °C for 2 hours, followed by a high-temperature calcination at 550 °C for 15 hours. After cooling to room temperature, the calcined solid was mechanically pulverized to obtain the manganese-based lithium adsorbent precursor Li4Mn. 3.875 Pb 1.125 O 12 Powder.

[0100] Example 4 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12Unlike Example 1, 4.52 kg of citric acid was used instead of 40 kg of solid tannic acid C. 76 H 52 O 46 The remaining raw materials and preparation methods are the same as in Example 1, and will not be repeated here.

[0101] Example 5 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12 Unlike Example 1, 6.87 kg of ethylenediaminetetraacetic acid was used instead of 40 kg of solid tannic acid C. 76 H 52 O 46 The remaining raw materials and preparation methods are the same as in Example 1, and will not be repeated here.

[0102] Example 6 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12 Unlike Example 1, 3.53 kg of tartaric acid was used instead of 40 kg of solid tannic acid C. 76 H 52 O 46 The remaining raw materials and preparation methods are the same as in Example 1, and will not be repeated here.

[0103] Example 7 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12 Unlike Example 1, 4 kg of gallic acid was used instead of 40 kg of solid tannic acid C. 76 H 52 O 46 The remaining raw materials and preparation methods are the same as in Example 1, and will not be repeated here.

[0104] Example 8 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12 Unlike Example 1, 15.52 kg of phytic acid was used instead of 40 kg of solid tannic acid C. 76 H 52 O 46 The remaining raw materials and preparation methods are the same as in Example 1, and will not be repeated here.

[0105] Example 9 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12 The specific preparation steps are as follows: (1) Precipitation reaction: 200 kg of solid MnCl2·4H2O was dissolved in 500 kg of deionized water. Then, 0.5 mol / L sodium hydroxide solution was used to adjust the pH of the MnCl2 solution to 8, and the dropping rate was 20 kg / h to convert divalent manganese into Mn(OH)2 precipitate. 83.6 kg of solid Pb(NO3)2 (the molar ratio of MnCl2·4H2O to Pb(NO3)2 was 3:1) was dissolved in 500 kg of deionized water. Then, 0.5 mol / L sodium hydroxide solution was used to adjust the pH of the Pb(NO3)2 solution to 8, and the dropping rate was 20 kg / h to convert divalent lead into Pb(OH)2 precipitate. The Mn(OH)2 precipitate slurry and the Pb(OH)2 precipitate slurry were mixed and mechanically stirred until uniform. The mixture was then subjected to plate and frame filter press filtration. The filter cake was then rinsed with deionized water for 1 h to make the conductivity of the effluent <200 μS·cm. -1 A filter cake of Mn(OH)2-Pb(OH)2 with a moisture content of 40% was obtained.

[0106] (2) Slurry preparation: Same as in Example 1.

[0107] (3) Spray drying: Same as in Example 1.

[0108] (4) Calcination reaction: Same as in Example 1.

[0109] Example 10 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12 The specific preparation steps are as follows: (1) Precipitation reaction: Same as in Example 1.

[0110] (2) Slurry preparation: Place the Mn(OH)2-Pb(OH)2 filter cake in a mechanically stirred tank, and add 42.5 kg of solid LiOH·H2O to the tank (the molar ratio of Li to H2O is required). + :(Mn 2+ +Pb 2+ The ratio of water to slurry is 0.8:1. First, add 50 kg of deionized water, then start mechanical stirring and continue to slowly add deionized water while monitoring the viscosity of the slurry. Stop adding deionized water when the viscosity of the slurry reaches 500 mPa·s, and continue mechanical stirring for 3 hours to obtain LiOH-Mn(OH)2-Pb(OH)2 slurry.

[0111] (3) Spray drying: Same as in Example 1.

[0112] (4) Calcination reaction: Same as in Example 1.

[0113] Example 11 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12 The specific preparation steps are as follows: (1) Precipitation reaction: Same as in Example 1.

[0114] (2) Slurry preparation: Same as in Example 1.

[0115] (3) Drying: C 76 H 52 O 46 The -LiOH-Mn(OH)2-Pb(OH)2 slurry was placed in a stainless steel basin and dried in an oven at 200℃ for 48 hours to obtain dried C. 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 hard block.

[0116] (4) Calcination reaction: Same as in Example 1.

[0117] Example 12 This embodiment provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Pb 1.25 O 12 The specific preparation steps are as follows: (1) Precipitation reaction: Same as in Example 1.

[0118] (2) Slurry preparation: Same as in Example 1.

[0119] (3) Spray drying: Same as in Example 1.

[0120] (4) Calcination reaction: The uniformly mixed C 76 H 52 O 46 LiOH-Mn(OH)2-Pb(OH)2 powder was placed in a mullite mortar with a packing thickness of 5 cm. Under air atmosphere, a one-step calcination method was used, with a heating rate of 5℃ / min, directly entering a high-temperature zone at 500℃ and calcining at this temperature for 10 hours. After cooling to room temperature, the calcined solid was mechanically pulverized to obtain the manganese-based lithium adsorbent precursor Li4Mn. 3.75 Pb 1.25 O 12 Powder.

[0121] Comparative Example 1 This comparative example provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.33 Pb 1.67 O 12 The specific preparation steps are as follows: (1) Precipitation reaction: 200 kg of solid MnCl2·4H2O was dissolved in 1000 kg of deionized water, and then 167.2 kg of solid Pb(NO3)2 (the molar ratio of MnCl2·4H2O to Pb(NO3)2 was added, and the mixture was stirred until fully dissolved to obtain a mixed solution of MnCl2 and Pb(NO3)2. Then, the pH of the mixed solution of MnCl2 and Pb(NO3)2 was adjusted to 8 with 0.5 mol / L sodium hydroxide solution at a dropping rate of 20 kg / h to precipitate divalent manganese and divalent lead into Mn(OH)2 and Pb(OH)2 precipitates. The mixture was then subjected to plate and frame filtration, and the filter cake was washed with deionized water for 1 h to make the conductivity of the effluent <200 μS·cm. -1 A filter cake of Mn(OH)2-Pb(OH)2 with a moisture content of 40% was obtained.

[0122] (2) Slurry preparation: Place the Mn(OH)2-Pb(OH)2 filter cake in a mechanically stirred tank, and add 51.0 kg of solid LiOH·H2O to the tank (the molar ratio of Li to H2O is required). + :(Mn 2+ +Pb 2+ The ratio was 0.8:1, and 40 kg of solid tannic acid C was added. 76 H 52 O 46 First, add 50 kg of deionized water, then start mechanical stirring. Continue to slowly add deionized water while monitoring the viscosity of the slurry. Stop adding deionized water when the viscosity reaches 500 mPa·s, and continue mechanical stirring for 3 hours to obtain C. 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 slurry.

[0123] (3) Spray drying: Same as in Example 1.

[0124] (4) Calcination reaction: Same as in Example 1.

[0125] Comparative Example 2 This comparative example provides a manganese-based lithium adsorbent precursor, Li4Mn. 4.167 Pb 0.833 O 12 The specific preparation steps are as follows: (1) Precipitation reaction: 200 kg of solid MnCl2·4H2O was dissolved in 1000 kg of deionized water, and then 66.9 kg of solid Pb(NO3)2 (the molar ratio of MnCl2·4H2O to Pb(NO3)2 was added, and the mixture was stirred until fully dissolved to obtain a mixed solution of MnCl2 and Pb(NO3)2. Then, the pH of the mixed solution of MnCl2 and Pb(NO3)2 was adjusted to 8 with 0.5 mol / L sodium hydroxide solution at a dropping rate of 20 kg / h to precipitate divalent manganese and divalent lead into Mn(OH)2 and Pb(OH)2, respectively. The mixture was then subjected to plate and frame filtration, and the filter cake was rinsed with deionized water for 1 h to make the conductivity of the effluent <200 μS·cm. -1 A filter cake of Mn(OH)2-Pb(OH)2 with a moisture content of 40% was obtained.

[0126] (2) Slurry preparation: Place the Mn(OH)2-Pb(OH)2 filter cake in a mechanically stirred tank, and add 40.7 kg of solid LiOH·H2O to the tank (the molar ratio of Li to H2O is required). + :(Mn 2+ +Pb 2+ The ratio was 0.8:1, and 40 kg of solid tannic acid C was added. 76 H 52 O 46 First, add 50 kg of deionized water, then start mechanical stirring. Continue to slowly add deionized water while monitoring the viscosity of the slurry. Stop adding deionized water when the viscosity reaches 500 mPa·s, and continue mechanical stirring for 3 hours to obtain C. 76 H 52 O 46 -LiOH-Mn(OH)2-Pb(OH)2 slurry.

[0127] (3) Spray drying: Same as in Example 1.

[0128] (4) Calcination reaction: Same as in Example 1.

[0129] Comparative Example 3 This comparative example provides a manganese-based lithium adsorbent precursor, Li4Mn5O. 12 The specific preparation steps are as follows: (1) Precipitation reaction: 200 kg of solid MnCl2·4H2O was dissolved in 1000 kg of deionized water and stirred until fully dissolved to obtain a MnCl2 solution. Then, the pH of the MnCl2 solution was adjusted to 8 with 0.5 mol / L sodium hydroxide solution at a dropping rate of 20 kg / h to convert divalent manganese into Mn(OH)2 precipitate. The mixture was then subjected to plate and frame filtration, and the filter cake was rinsed with deionized water for 1 h to make the conductivity of the effluent <200 μS·cm. -1A filter cake of Mn(OH)2 with a moisture content of 40% was obtained.

[0130] (2) Slurry preparation: Place the Mn(OH)2 filter cake in a mechanically stirred tank, and add 33.9 kg of solid LiOH·H2O to the tank (the molar ratio of Li to H2O is required). + :Mn 2+ (0.8%), and added 40kg of solid tannic acid C 76 H 52 O 46 First, add 50 kg of deionized water, then start mechanical stirring. Continue to slowly add deionized water while monitoring the viscosity of the slurry. Stop adding deionized water when the viscosity reaches 500 mPa·s, and continue mechanical stirring for 3 hours to obtain C. 76 H 52 O 46 -LiOH-Mn(OH)2 slurry.

[0131] (3) Spray drying: C 76 H 52 O 46 The LiOH-Mn(OH)₂ slurry is injected into the spray drying tower through a high-speed centrifugal spray disc at the top. The rotation speed of the high-speed centrifugal spray disc is 500 rpm, the slurry injection rate is 50 L / h, the inlet air temperature of the drying tower is 200℃, and the inlet air volume is adjusted to 1500 m³ / h. 3 / h, ensuring that at this slurry spraying rate, the moisture content of the obtained powder is <5%, and the outlet air temperature of the spray drying tower is 60℃. After the slurry is dried, the C obtained by the above spray drying is... 76 H 52 O 46 -LiOH-Mn(OH)2 powder was placed entirely in a large ribbon mixer with a ribbon rotation frequency of 10Hz and mixed for 2 hours to obtain a uniformly mixed C. 76 H 52 O 46 -LiOH-Mn(OH)2 powder.

[0132] (4) Calcination reaction: The uniformly mixed C 76 H 52 O 46 LiOH-Mn(OH)₂ powder was placed in a mullite mortar with a packing thickness of 5 cm. Calcination was performed in air using a "short-time low temperature + long-time high temperature" method, with a heating rate of 5℃ / min. The calcination was carried out at a low temperature of 250℃ for 1 hour, followed by a high temperature of 500℃ for 10 hours. After cooling to room temperature, the calcined solid was mechanically pulverized to obtain the manganese-based lithium adsorbent precursor Li₄Mn₅O₂. 12 Powder.

[0133] Comparative Example 4 This comparative example provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Sn 1.25 O 12 The difference from Example 1 is that 57.4 kg of solid SnCl2·2H2O was used instead of 83.6 kg of solid Pb(NO3)2. The remaining steps are the same as in Example 1 and will not be repeated here.

[0134] Comparative Example 5 This comparative example provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Zr 1.25 O 12 The difference from Example 1 is that 108.4 kg of solid Zr(NO3)4·5H2O was used instead of 83.6 kg of solid Pb(NO3)2. The remaining steps are the same as in Example 1 and will not be repeated here.

[0135] Comparative Example 6 This comparative example provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Al 1.25 O 12 The difference from Example 1 is that 61.0 kg of solid AlCl3·6H2O was used instead of 83.6 kg of solid Pb(NO3)2. The remaining steps are the same as in Example 1 and will not be repeated here.

[0136] Comparative Example 7 This comparative example provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Fe 1.25 O 12 The difference from Example 1 is that 41.0 kg of solid FeCl3 was used instead of 83.6 kg of solid Pb(NO3)2. The remaining steps are the same as in Example 1 and will not be repeated here.

[0137] Comparative Example 8 This comparative example provides a manganese-based lithium adsorbent precursor, Li4Mn. 3.75 Co 1.25 O 12 The difference from Example 1 is that 59.04 kg of solid CoCl2·6H2O was used instead of 83.6 kg of solid Pb(NO3)2. The remaining steps are the same as in Example 1 and will not be repeated here.

[0138] Characterization Example 1 The manganese-based lithium adsorbent precursors obtained in Examples 1-3 were subjected to scanning electron microscopy (SEM), and the corresponding SEM images are shown below. Figures 2-4 As shown.

[0139] from Figure 2 It can be seen that the Li4Mn synthesized in Example 1 3.75 Pb 1.25 O 12 The powder has a particle size of about 50~200nm and the powder particles are spherical.

[0140] from Figure 3 It can be seen that the Li4Mn4PbO synthesized in Example 2 12 The powder has a particle size of about 50~200nm and the powder particles are spherical.

[0141] from Figure 4 It can be seen that the Li4Mn synthesized in Example 3 3.875 Pb 1.125 O 12 The powder has a particle size of about 50~200nm and the powder particles are spherical.

[0142] Characterization Example 2 The precursors obtained in Examples 1-3, 9-12 and Comparative Examples 1-2 were dissolved by heating with nitric acid, and the key element ratios of the manganese-based lithium adsorbent precursors were measured by inductively coupled plasma atomic emission spectrometry (ICP).

[0143] In Example 1, the key element ratio of the manganese-based lithium adsorbent precursor was measured to be Li:Mn:Pb = 4.02:3.76:1.24, indicating that the chemical formula of the manganese-based lithium adsorbent precursor is approximately Li4Mn. 3.75 Pb 1.25 O 12 In Example 2, the key element ratio of the manganese-based lithium adsorbent precursor was measured to be Li:Mn:Pb = 4.03:3.98:1.02, indicating that the chemical formula of the manganese-based lithium adsorbent precursor is approximately Li4Mn4Pb1O. 12 In Example 3, the key element ratio of the manganese-based lithium adsorbent precursor was measured to be Li:Mn:Pb = 4.03:3.875:1.125, indicating that the chemical formula of the manganese-based lithium adsorbent precursor is approximately Li4Mn. 3.875 Pb 1.125 O 12 In Example 9, the key element ratio of the manganese-based lithium adsorbent precursor was measured to be Li:Mn:Pb = 4.03:3.75:1.25, indicating that the chemical formula of the manganese-based lithium adsorbent precursor is approximately Li4Mn. 3.75 Pb 1.25 O 12 In Example 10, the key element ratio of the manganese-based lithium adsorbent precursor was measured to be Li:Mn:Pb = 4.05:3.74:1.26, indicating that the chemical formula of the manganese-based lithium adsorbent precursor is approximately Li4Mn. 3.75 Pb 1.25 O12 In Example 11, the key element ratio of the manganese-based lithium adsorbent precursor was measured to be Li:Mn:Pb = 4.07:3.72:1.28, indicating that the chemical formula of the manganese-based lithium adsorbent precursor is approximately Li4Mn. 3.75 Pb 1.25 O 12 In Example 12, the key element ratio of the manganese-based lithium adsorbent precursor was measured to be Li:Mn:Pb = 4.02:3.73:1.27, indicating that the chemical formula of the manganese-based lithium adsorbent precursor is approximately Li4Mn. 3.75 Pb 1.25 O 12 .

[0144] The key element ratio of the manganese-based lithium adsorbent precursor measured in Comparative Example 1 was Li:Mn:Pb = 4.04:3.33:1.67, indicating that the chemical formula of the manganese-based lithium adsorbent precursor is approximately Li4Mn. 3.33 Pb 1.67 O 12 Comparative Example 2 showed that the key element ratio of the manganese-based lithium adsorbent precursor was Li:Mn:Pb = 4.01:4.167:0.833, indicating that the chemical formula of the manganese-based lithium adsorbent precursor is approximately Li4Mn. 4.167 Pb 0.833 O 12 .

[0145] Characterization Example 3 The manganese-based lithium adsorbent precursors obtained in Examples 1-3 were tested using X-ray diffraction (XRD), and the corresponding spectra are shown below. Figures 5-7 As shown.

[0146] from Figure 5 It can be seen from the XRD pattern and the standard card PDF#46-0810 (the corresponding crystal chemical formula of this standard card is Li4Mn5O) 12 The consistent peak positions further confirm that the chemical formula of the synthesized manganese-based lithium adsorbent precursor is Li4Mn. 3.75 Pb 1.25 O 12 Furthermore, Pb element is doped into Li4Mn5O 12 It replaces Mn elements in the crystal lattice.

[0147] from Figure 6 It can be seen from the XRD pattern and the standard card PDF#46-0810 (the corresponding crystal chemical formula of this standard card is Li4Mn5O) 12 The consistent peak positions further confirm that the chemical formula of the synthesized manganese-based lithium adsorbent precursor is Li4Mn4PbO. 12 Furthermore, Pb element is doped into Li4Mn5O 12It replaces Mn elements in the crystal lattice.

[0148] from Figure 7 It can be seen from the XRD pattern and the standard card PDF#46-0810 (the corresponding crystal chemical formula of this standard card is Li4Mn5O) 12 The consistent peak positions further confirm that the chemical formula of the synthesized manganese-based lithium adsorbent precursor is Li4Mn. 3.875 Pb 1.125 O 12 Furthermore, Pb element is doped into Li4Mn5O 12 It replaces Mn elements in the crystal lattice.

[0149] Test case The precursors obtained in the examples and comparative examples were granulated using PVC adhesive as a binder to obtain spherical particles with a particle size of 0.5~0.8 mm (bulk density of 0.9 kg / L), wherein the PVC content in the particles was 15%. The shaped manganese-based lithium adsorbent precursor-PVC was acidified with 1 mol / L hydrochloric acid for 6 h to obtain shaped manganese-based lithium adsorbent-PVC. 50 mL of manganese-based lithium adsorbent-PVC was placed in an plexiglass adsorption column, and real brine (lithium ion concentration of 250 mg / L) was pumped into the adsorption column for adsorption for 3 h at a flow rate of 12 BV / h. The lithium ion concentration in the mixed product water was tested, and the lithium adsorption capacity was calculated based on the lithium concentrations in the influent and product water.

[0150] The obtained data is recorded in Table 1.

[0151] Table 1

[0152] As shown in Table 1, Example 1 showed a lithium adsorption capacity of 7.5 g / L after 3 hours of adsorption. Taking adsorption and desorption as a single cycle, it was found that during the adsorption and desorption process (manganese and lead content was measured using inductively coupled plasma atomic emission spectrometry (ICP)), manganese dissolution was very low, lead was undetectable, and the adsorption capacity decreased by only 0.5% after 100 cycles. Example 2 showed a lithium adsorption capacity of 7.8 g / L after 3 hours of adsorption, with a capacity decrease of only 0.7% after 100 cycles. Example 3 showed a lithium adsorption capacity of 8.1 g / L after 3 hours of adsorption, with a capacity decrease of only 0.65% after 100 cycles.

[0153] Examples 4-8 involved replacing the complexing agent tannic acid with citric acid, ethylenediaminetetraacetic acid, tartaric acid, gallic acid, and phytic acid, respectively. Table 1 shows that the lithium adsorption capacity measured after 3 hours of adsorption in Examples 4-8 was 7.5-7.7 g / L. Taking adsorption and desorption as a single cycle, it was found that during the adsorption and desorption process (manganese and lead content was measured using inductively coupled plasma atomic emission spectrometry (ICP)), manganese loss was very low, lead was undetectable, and the adsorption capacity decreased by only 0.3%-0.6% after 100 cycles. This demonstrates that replacing the complexing agent tannic acid with citric acid, ethylenediaminetetraacetic acid, tartaric acid, gallic acid, and phytic acid can yield a manganese-based lithium adsorbent with high adsorption capacity, low manganese loss, and high adsorption stability.

[0154] Manganese-based lithium adsorbent H4Mn in Example 9 3.75 Pb 1.25 The lithium adsorption capacity of PVC after 3 hours of adsorption was 5.6 g / L, a 25% decrease compared to Example 1 (7.5 g / L). Furthermore, lead was undetectable during adsorption and desorption, but manganese dissolution was high, and the adsorption capacity decreased by 11.5% after 100 cycles. This indicates that stepwise precipitation followed by blending leads to increased Mn dissolution and decreased adsorption capacity. Instead of preparing MnCl2 and Pb(NO3)2 precipitates separately and then blending them, the pH of the mixed solution was adjusted with sodium hydroxide solution to convert divalent manganese and divalent lead into Mn(OH)2-Pb(OH)2 co-precipitates. This method involves adjusting the pH of a mixed solution of MnCl2 and Pb(NO3)2 to transform it into a Mn(OH)2-Pb(OH)2 coprecipitate. This allows for uniform mixing of the two precipitates at the micro-nano level, facilitating the highly uniform incorporation of Pb into the Li-Mn-O crystal framework during subsequent calcination. This improves the uniformity of product performance, the controllability of synthesis, and enhances adsorption capacity while reducing manganese loss. Conversely, preparing Mn(OH)2 and Pb(OH)2 precipitates separately and then blending them results in difficulty achieving micro-nano-level uniformity, negatively impacting product quality during calcination.

[0155] The molded manganese-based lithium adsorbent H4Mn in Example 10 3.75 Pb 1.25The lithium adsorption capacity of PVC after 3 hours of adsorption was 4.2 g / L, a 44% decrease compared to Example 1 (7.5 g / L). Furthermore, lead was undetectable during adsorption and desorption, but manganese dissolution was high, and the adsorption capacity decreased by 17.9% after 100 cycles. This indicates that 40 kg of solid tannic acid C was not added during the slurry preparation stage. 76 H 52 O 46 This will lead to increased Mn dissolution and decreased adsorption capacity. Utilizing tannic acid C... 76 H 52 O 46 The reaction with lithium hydroxide (LiOH) yields lithium tannate. Furthermore, the phenolic hydroxyl groups on the tannic acid molecule can form coordination complexes with the Mn and Pb elements in Mn(OH)₂ and Pb(OH)₂ precipitates. This means that tannic acid alone can achieve the distribution of Mn, Pb, and Li elements at a micro-nano scale, facilitating the uniform formation of Li₄Mn during subsequent calcination. 5- x Pb x O 12 Crystals. Furthermore, tannic acid C is added to the Mn(OH)₂-Pb(OH)₂ coprecipitation slurry. 76 H 52 O 46 By utilizing the structural characteristics of the large molecular weight three-dimensional organic framework of tannic acid, the dispersibility of the slurry can be effectively stabilized, preventing the co-precipitation of Mn(OH)2-Pb(OH)2 in the slurry and sedimentation, which is beneficial to the uniformity of the reactants and to obtaining adsorbent products with high adsorption capacity and low manganese loss.

[0156] The molded manganese-based lithium adsorbent H4Mn in Example 11 3.75 Pb 1.25The lithium adsorption capacity of PVC after 3 hours of adsorption was 3.2 g / L, a decrease of 57.3% compared to Example 1 (7.5 g / L). Lead was undetectable during adsorption and desorption, but manganese dissolution was high, and the adsorption capacity decreased by 34.1% after 100 cycles. This indicates that static oven drying during the raw material drying stage results in hard lumps with uneven drying and mixing, leading to increased Mn dissolution and reduced adsorption capacity. Spray drying instead of static drying equipment like ovens is used to obtain a powder with uniform material distribution, rather than hard lumps. Powder calcination is more effective than hard lumps, resulting in higher product performance. Drying filter cake in an oven first results in hard lumps; secondly, the outer layer of the filter cake is dried before the inner layer is fully dried, resulting in hard lumps with uneven drying and mixing; and finally, the slurry undergoes sedimentation and stratification during static drying. These three disadvantages affect the uniformity of material reaction during calcination. The uniformity of the materials determines the performance of the products from the calcination reaction.

[0157] The molded manganese-based lithium adsorbent H4Mn in Example 12 3.75 Pb 1.25 The lithium adsorption capacity of PVC after 3 hours of adsorption was 5.0 g / L, a decrease of 33.3% compared to Example 1 (7.5 g / L). Furthermore, the lead concentration in the permeate was found to be 1.8 mg / L during adsorption and desorption, and 2.7 mg / L during desorption, indicating significant lead dissolution. Additionally, manganese was detected in both the adsorption and desorption permeate, indicating high manganese dissolution. After 100 cycles, the adsorption capacity decreased by 48.1%. This suggests that the one-step method during the calcination reaction leads to increased Mn dissolution and decreased adsorption capacity. This is because the low-temperature stage primarily causes Mn in the Mn(OH)₂-Pb(OH)₂ co-precipitation. 2+ and Pb 2+ Oxidized to Mn 3+ / Mn 4+ and Pb 4+ This provides a basis for constructing Li4Mn at high temperatures. 5-x Pb x O 12 (x=1~1.25) The direct raw material Mn required for crystal formation 3+ / Mn 4+ and Pb 4+ To avoid the problems of excessively rapid Mn(OH)₂-Pb(OH)₂ reaction and insufficient raw material supply at high temperatures, which could lead to severe crystal defects and uneven distribution of the dopant element Pb, furthermore, the Mn in the Mn(OH)₂-Pb(OH)₂ co-precipitation... 2+ and Pb 2+ Oxidized to Mn 3+ / Mn 4+ and Pb 4+ The reaction rate is very fast and does not require a long time, so a "short-time low-temperature" method is used. The high-temperature zone is mainly to provide energy and time for the crystal growth and perfection. If the temperature is too low, the chemical reaction will not be completed; if the time is too short, the crystal will not be perfected, resulting in a large number of defects in the crystal, which will affect the adsorption performance and operational stability of the product.

[0158] H4Mn in Comparative Example 1 3.33 Pb 1.67 O 12 -PVC has a very low adsorption capacity, but it was found that the decrease rate of adsorption capacity during adsorption and desorption was only 0.57%. This indicates that increasing the amount of Pb incorporated leads to a decrease in adsorption capacity, but the dissolution of Mn is unaffected. This is because Pb in Li4Mn... 5-x Pb x O 12 An increase in the crystal framework, due to the tetravalent nature of Pb, leads to the substitution of Mn (including both trivalent and tetravalent manganese) by Pb, resulting in Li4Mn. 5-x Pb x O 12 The reduction of trivalent manganese in the crystal framework leads to the decrease in Li4Mn. 5-x Pb x O 12 The reduction in adsorption sites in the crystal framework decreases the adsorption capacity. However, Pb doping has the dual effect of spatial isolation and lattice environment enhancement, thus suppressing manganese dissolution.

[0159] H4Mn in Comparative Example 2 4.167 Pb 0.833 O 12 The adsorption capacity of PVC remained essentially unchanged compared to Example 1, but a significant decrease of 39.6% was observed during adsorption and desorption. This indicates that reducing the amount of Pb incorporated leads to a substantial increase in Mn dissolution, but the change in adsorption capacity is relatively small. This is because Pb in Li4Mn... 5-x Pb x O 12 The reduction in the crystal framework led to severe manganese dissolution.

[0160] The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 does not contain lead. As shown in Table 1, the adsorption capacity of the obtained manganese-based lithium adsorbent is 2.5 g / L, far less than the 7.5 g / L in Example 1. Furthermore, manganese concentrations of 17.6 mg / L and 39.8 mg / L were detected during adsorption and desorption, respectively, indicating severe manganese loss. After 100 cycles, the adsorption capacity decreased by as much as 62.3%. This demonstrates that the manganese-based lithium adsorbent without lead doping cannot meet the requirements of high adsorption capacity, low manganese loss, and high adsorption stability. The difference between Comparative Examples 4-8 and Example 1 is that Example 1 is doped with Pb, while Comparative Examples 4-8 are doped with Sn, Zr, Al, Fe, and Co, respectively. As shown in Table 1, when the doping elements of the manganese-based lithium adsorbent are Sn, Zr, Al, Fe, and Co, the adsorption capacity is 2.5-4.4 g / L, which is much lower than the 7.5 g / L in Example 1. Taking adsorption and desorption as a cycle, it was found that during the adsorption and desorption processes (manganese concentration measured by inductively coupled plasma atomic emission spectrometry (ICP)), the manganese concentration detected during adsorption was 7.3-17.9 mg / L, and the manganese concentration detected during desorption was 9.8-41.2 mg / L. Compared with Example 1, the manganese loss is very severe. Furthermore, after 100 cycles, the adsorption capacity decrease rate is 18.1%-36.8%, much higher than the 0.5% decrease rate in Example 1. This demonstrates that when the doping element is replaced by Sn, Zr, Al, Fe, and Co, the requirements of high adsorption capacity, low manganese loss, and high adsorption stability cannot be met. The reason for this result may be that compared to Sn, Zr, Al, Fe, and Co, Pb... 4+ With higher electronegativity and stronger Pb-O bonding ability, it significantly enhances the overall lattice bonding strength of manganese-based lithium adsorbents, suppresses Jahn-Teller distortion, makes the lattice structure more compact and stable, narrows ion migration channels, and increases the valence state transition energy barrier, thereby synergistically suppressing Mn. 2+ Dissolution reduces the rate of dissolution loss and improves cycle stability.

[0161] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A manganese-based lithium adsorbent precursor, characterized in that, The precursor of the manganese-based lithium adsorbent is a lead-doped manganese-based lithium adsorbent precursor. The chemical formula of the lead-doped manganese-based lithium adsorbent precursor is Li4Mn. 5-x Pb x O 12 x takes values ​​from 1 to 1.

5.

2. The manganese-based lithium adsorbent precursor according to claim 1, characterized in that, The chemical formula of the lead-doped manganese-based lithium adsorbent precursor is Li4Mn. 5-x Pb x O 12 x takes values ​​from 1 to 1.

25.

3. A method for preparing the manganese-based lithium adsorbent precursor according to claim 1 or 2, characterized in that, An alkaline solution is added to a mixed solution containing manganese and lead salts to carry out a reaction. After the reaction is completed, the mixture is filtered to obtain a filter cake. The filter cake, lithium compound, complexing agent and water are mixed evenly to form a slurry. The slurry is spray-dried and then calcined to obtain a manganese-based lithium adsorbent precursor.

4. The preparation method according to claim 3, characterized in that, The manganese salt is a soluble manganese salt; Preferably, the soluble manganese salt includes at least one of MnCl2, MnSO4, Mn(NO3)2, and Mn(CH3COO)2, with MnCl2 being the most preferred; Preferably, the lead salt is a soluble lead salt; Preferably, the soluble lead salt includes Pb(NO3)2 and / or Pb(CH3COO)2; Preferably, in the mixed solution, the concentration of manganese salt is 0.133~0.2 kg / L, and the concentration of lead salt is 0.056~0.111 kg / L; Preferably, in the mixed solution, the molar ratio of Mn:Pb is (3~4):1; Preferably, the alkali in the alkaline solution includes NaOH and / or KOH, with NaOH being the most preferred; Preferably, the concentration of the alkaline solution is 0.5~1.5 mol / L; Preferably, the pH of the reaction is 8-11; Preferably, the alkaline solution is added at a rate of 20-50 kg / h.

5. The preparation method according to claim 3, characterized in that, The filtration methods include plate and frame filtration, centrifugal filtration, or pressure filtration; Preferably, the preparation method further includes a rinsing process after obtaining the filter cake through filtration, wherein the conductivity of the rinse water is <200 μS·cm. -1 Then finish rinsing; Preferably, the moisture content of the filter cake is 40-60%.

6. The preparation method according to claim 3, characterized in that, The lithium compounds include LiOH, Li2CO3, and Li2C2O4; Preferably, the ratio of lithium in the lithium compound to the total molar amount of manganese and lead in the filter cake is (0.80~0.95):1; Preferably, the complexing agent includes at least one of tannic acid, citric acid, ethylenediaminetetraacetic acid, tartaric acid, gallic acid, and phytic acid, with tannic acid being the most preferred. Preferably, the ratio of the complexing agent to the total molar amount of manganese and lead in the filter cake is (0.02~0.04):

1.

7. The preparation method according to any one of claims 3 to 6, characterized in that, The viscosity of the slurry is 500~1000 mPa·s; Preferably, during the spray drying process, the slurry spraying rate is 50~100 L / h, the inlet air temperature of the drying tower is 200~250℃, and the inlet air volume is 1500~2000 m³ / h. 3 / h; Preferably, the powder obtained by spray drying has a moisture content of <5%.

8. The preparation method according to any one of claims 3 to 6, characterized in that, The calcination process is as follows: First, raise the temperature to 250-400℃ at a heating rate of 5-10℃ / min and hold for 1-3 hours; then raise the temperature to 500-700℃ at a heating rate of 5-10℃ / min and hold for 10-20 hours.

9. A manganese-based lithium adsorbent, characterized in that, It is prepared using the manganese-based lithium adsorbent precursor described in claim 1 or 2; The chemical formula of the manganese-based lithium adsorbent is H4Mn. 5-x Pb x O 12 x takes values ​​from 1 to 1.

5.

10. The manganese-based lithium adsorbent according to claim 9, characterized in that, In the initial cycle of lithium extraction from salt lakes, the manganese dissolution rate is <50ppm; Preferably, the adsorption capacity is ≥7.5 g / L; Preferably, the adsorption capacity decreases by ≤0.7% after 100 cycles.

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