Comprehensive utilization method of sedimentary lithium mine

Abstract

The application provides a comprehensive utilization method of a sedimentary lithium ore, and comprises the following steps: crushing and acid curing heat treatment of the sedimentary lithium ore to obtain a cured roasting residue; aging, roasting, water leaching and solid-liquid separation treatment of the cured roasting residue, a template agent and a solvent to obtain a lithium-containing leaching solution and a mesoporous molecular sieve; and passing the lithium sulfate purification solution obtained after impurity removal of the lithium-containing leaching solution into a bipolar membrane electrodialysis system to perform electrodialysis to obtain a lithium hydroxide solution and a sulfuric acid solution. The method can obtain a mesoporous molecular sieve product and an electronic-grade lithium hydroxide product, realizes comprehensive recovery and utilization of the sedimentary lithium resource, solves the problem of difficult lithium-aluminum separation of the leaching solution in the traditional sulfuric acid roasting method, and simultaneously synthesizes the mesoporous molecular sieve. Meanwhile, the regenerated sulfuric acid obtained through the bipolar membrane electrodialysis can realize sulfuric acid recycling, reduces the consumption of acid and alkali in the process, realizes green and clean production, is suitable for large-scale popularization and application, and has high application value.

Description

Technical Field

[0001] This invention relates to the field of comprehensive resource utilization technology. Specifically, this invention relates to a method for the comprehensive utilization of sedimentary lithium deposits. Background Technology

[0002] Lithium is the lightest metal in nature and plays a significant role in new energy vehicles, lithium batteries, high-performance medical devices, biomedicine, and controlled nuclear fusion. It is an indispensable key mineral for the development of China's emerging industries in the future and is also known as "white oil," "21st-century new energy metal," and "metal that promotes world progress," with extremely high economic value.

[0003] Currently, lithium deposits are mainly classified into three categories: brine type, pegmatite type, and sedimentary type. China has relatively abundant lithium resources, primarily brine and pegmatite types. However, most lithium deposits are located in high-altitude areas with poor development conditions, and most brine-type lithium deposits have high Mg / Li ratios, meaning mining technology is not yet fully mature. Sedimentary lithium deposits generally refer to lithium deposits occurring in sedimentary rocks (including bauxite, coal, kaolin, tuff, etc.) that can be utilized as associated minerals. Currently, the development and utilization of sedimentary lithium deposits is not high; except for Jadar, most are in the exploration stage without actual production. However, with advancements in mining technology and the continuous discovery of sedimentary lithium deposits abroad in recent years, my country's sedimentary lithium deposits are expected to receive more attention.

[0004] In China's sedimentary lithium resources, lithium mainly occurs in isomorphous and ion-adsorbed forms, primarily found in chlorite, montmorillonite, kaolinite, and illite, with smaller amounts found in diaspore, gibbsite, boehmite, and some heavy minerals. Kaolinite has a relatively fine grain size (micrometer-scale), while lithium chlorite has an even finer grain size (micrometer to nanometer-scale). Lithium chlorite is mainly distributed as fine agglomerates within the illite and kaolinite mineral aggregates, intertwined with other fine-grained layered silicate minerals such as clinochlore and halloysite, making liberation difficult. Concentrating lithium chlorite using conventional physical beneficiation methods such as gravity separation, magnetic separation, and flotation is challenging. Direct lithium extraction using hydrometallurgical or pyrometallurgical methods presents numerous problems due to the low Li₂O grade in the raw ore.

[0005] How to extract lithium from lithium ore efficiently, environmentally, with low energy consumption and low cost has attracted the attention of many researchers and enterprises. The main process routes for lithium extraction from ore include: sulfuric acid roasting, sulfate roasting, chlorination roasting, limestone roasting, and pressure cooking.

[0006] Disadvantages of existing technology:

[0007] 1. Sulfuric acid roasting process: After the roasting reaction, lithium and aluminum ions are leached out together, making it difficult to separate aluminum and lithium. After the roasting reaction, sulfuric acid and soda ash are converted into sodium sulfate, which has a lower value.

[0008] 2. Sulfate roasting process: The roasting volume is large, especially in sedimentary lithium ores with low lithium content and high salt content, which greatly increases the roasting volume and energy consumption. Potassium sulfate is used as a roasting aid, which consumes a large amount and has a high cost. The product is also often contaminated by potassium. The leaching residue after roasting cannot be comprehensively utilized, resulting in a large amount of solid waste.

[0009] 3. Sodium carbonate pressure leaching process: requires high-end equipment and has high cost due to pressure leaching.

[0010] 4. Chlorination roasting production process: It causes severe corrosion to equipment, has high equipment requirements, makes it difficult to collect lithium chloride, has strong corrosive furnace gas, and requires a large amount of reagents.

[0011] 5. Limestone roasting production process: The leaching solution has a low lithium content, high evaporation energy consumption, low lithium recovery rate, and the sludge obtained after leaching has cohesiveness, which makes equipment maintenance difficult.

[0012] In comparison, sulfuric acid roasting can effectively extract lithium from lithium ore under relatively mild and simple conditions, but it also suffers from high sulfuric acid consumption and the need for large amounts of alkali to neutralize residual acid. The recycling of sulfuric acid would bring significant economic and environmental benefits. More importantly, a large amount of aluminum is leached during the sulfuric acid leaching process, leading to the loss of a significant amount of lithium as lithium aluminum hydroxide during subsequent purification. Preventing aluminum leaching at the source would avoid substantial lithium loss. Currently, there are very few reports on the comprehensive utilization of this type of sedimentary lithium ore. Therefore, developing an efficient, clean, and economical method for selectively extracting lithium from sedimentary lithium ore is of great significance to my country's lithium industry. Summary of the Invention

[0013] This invention aims to address at least one of the problems existing in the prior art. To this end, this invention proposes a comprehensive utilization method for sedimentary lithium ore. Using this method, mesoporous molecular sieve products and electronic-grade lithium hydroxide products can be obtained, achieving comprehensive recovery and utilization of sedimentary lithium resources. Furthermore, while synthesizing mesoporous molecular sieves, it effectively solves the problem of difficult lithium-aluminum separation in the leaching solution of traditional sulfuric acid roasting methods, inhibiting aluminum leaching at the source. Simultaneously, the use of bipolar membrane electrodialysis to regenerate sulfuric acid enables its recycling, greatly reducing acid and alkali consumption in the process and achieving green and clean production. The method of this invention is suitable for large-scale application and has high application value.

[0014] In one aspect of the present invention, a comprehensive utilization method for sedimentary lithium ore is proposed. According to an embodiment of the present invention, the method includes: crushing the sedimentary lithium ore to obtain lithium ore powder; subjecting the lithium ore powder to aging heat treatment with acid to obtain aging roasting residue; subjecting the aging roasting residue, template agent, and solvent to aging, roasting, water leaching, and solid-liquid separation treatment to obtain lithium-containing leachate and mesoporous molecular sieve; subjecting the lithium-containing leachate to impurity removal treatment to obtain lithium sulfate purified solution; and passing the lithium sulfate purified solution into a bipolar membrane electrodialysis system for electrodialysis to obtain lithium hydroxide solution and sulfuric acid solution.

[0015] In the method of this invention, after the lithium ore powder undergoes aging and heat treatment, silicon remains in the form of silicon dioxide and does not dissolve. The subsequent lithium-containing leachate obtained from water leaching is essentially free of silicon, consisting mostly of lithium and aluminum, thus reducing the steps of lithium enrichment and impurity removal. The aging and roasting residue is directly subjected to aging, roasting, water leaching, and solid-liquid separation to obtain a lithium-containing leachate and mesoporous molecular sieves. During this process, lithium remains in the form of lithium sulfate, while aluminum changes from aluminum sulfate to aluminum hydroxide, and after roasting, it becomes aluminum oxide. Through water leaching and then solid-liquid separation, mesoporous molecular sieves and a lithium-containing solution are obtained. The entire process not only completes the preparation of mesoporous molecular sieves but also obtains a lithium-containing solution with an aluminum impurity content of less than 5 ppm, directly solving the industry problem of difficult aluminum separation without generating slag and addressing the difficulty of tailings disposal. The lithium sulfate purified solution obtained from the lithium-containing leachate after aluminum and calcium removal treatment is subjected to bipolar membrane electrodialysis to obtain a lithium hydroxide solution and recover sulfuric acid, which facilitates the recycling of sulfuric acid, greatly reducing the consumption of acids and alkalis in the process and achieving green and clean production.

[0016] According to embodiments of the present invention, the above-mentioned comprehensive utilization method for sedimentary lithium deposits may further include the following additional technical features:

[0017] According to an embodiment of the present invention, the aging heat treatment temperature is 100-300°C and the time is 2-6 hours; the mass ratio of lithium ore powder to acid is 1:0.4-1:2; the acid is selected from sulfuric acid solution and the concentration is 50-98 wt%.

[0018] According to an embodiment of the present invention, the template agent is selected from at least one of polymethyl methacrylate and hexadecyltrimethylammonium bromide and a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer; the molar ratio of the polymethyl methacrylate or hexadecyltrimethylammonium bromide to the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is 1:1 to 1:5.

[0019] According to an embodiment of the present invention, the mass ratio of the aging roasting residue to the template agent is 1:0.01 to 1:0.06; the solvent is selected from sodium hydroxide solution, and the ratio of the total molar amount of sodium hydroxide ions in the sodium hydroxide solution and sodium oxide in the aging roasting residue to the molar amount of silicon dioxide in the aging roasting residue is 0.6:1 to 1.4:1, calculated as n(Na2O) / n(SiO2).

[0020] According to an embodiment of the present invention, the aging treatment is performed at a temperature of 70–120°C for a time of 10–48 hours.

[0021] According to an embodiment of the present invention, the calcination treatment is carried out at a temperature of 700–800°C for a time of 1–5 hours.

[0022] According to an embodiment of the present invention, the solid-liquid ratio of the water leaching treatment is 1:2 to 1:10, the temperature of the water leaching treatment is 25 to 90°C, and the time is 0.5 to 4 hours. The solid-liquid ratio refers to the ratio of the mass of the product from the calcination treatment to the mass of the water used in the water leaching treatment.

[0023] According to an embodiment of the present invention, the aluminum removal treatment includes: adjusting the pH value of the lithium-containing leaching solution to 6.0-7.0 using lithium hydroxide to precipitate aluminum, separating the solid and liquid to obtain aluminum slag and filtrate, and repeating the pH adjustment and solid-liquid separation steps of the filtrate 0-3 times to obtain a purified solution; the calcium removal treatment includes: mixing the purified solution with lithium carbonate and adjusting the pH value to 9.5-10.5 to precipitate calcium, separating the solid and liquid to obtain calcium slag and lithium sulfate purified solution.

[0024] According to an embodiment of the present invention, the bipolar membrane electrodialysis system includes an acid chamber, an alkali chamber, and a salt chamber, wherein the acid chamber contains water, the alkali chamber contains a lithium hydroxide solution, and the lithium sulfate purification solution is introduced into the salt chamber.

[0025] According to an embodiment of the present invention, the method further includes: evaporating and concentrating the lithium hydroxide solution and recrystallizing it to obtain lithium hydroxide monohydrate.

[0026] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0028] Figure 1 A schematic flowchart of a comprehensive utilization method for sedimentary lithium ore according to an embodiment of the present invention is shown;

[0029] Figure 2 A schematic diagram of a bipolar membrane electrodialysis system according to an embodiment of the present invention is shown, where BP represents the bipolar membrane, A represents the cathode membrane, and C represents the anode membrane;

[0030] Figure 3 A schematic flowchart of a comprehensive utilization method for sedimentary lithium ore according to another embodiment of the present invention is shown. Detailed Implementation

[0031] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0032] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.

[0035] This invention proposes a comprehensive utilization method for sedimentary lithium deposits. See embodiments of the invention for details. Figure 1 The method includes: S100 crushing treatment, S200 aging heat treatment, S300 aging, roasting, water leaching and solid-liquid separation treatment, S400 aluminum and calcium removal treatment and S500 electrodialysis. Each step will be described in detail below.

[0036] S100 Crushing Processing

[0037] In this step, the sedimentary lithium ore is crushed to obtain lithium ore powder. This allows for a more thorough subsequent reaction.

[0038] According to an embodiment of the present invention, the proportion of particles with a size smaller than 0.074 mm in the lithium ore powder is 70-80%. This better facilitates the full progress of subsequent reactions.

[0039] S200 aging heat treatment

[0040] In this step, the lithium ore powder is subjected to a aging heat treatment with acid to obtain aging roasting residue. This allows lithium, aluminum, and other substances in the lithium ore powder to be converted into forms that are easier to extract and process.

[0041] According to embodiments of the present invention, the aging heat treatment temperature is 100–300°C, and the time is 2–6 hours. In some embodiments, the aging heat treatment temperature is a range formed by 100°C, 150°C, 200°C, 250°C, 280°C, 300°C, or any two of these values ​​as endpoints, and the time is a range formed by 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or any two of these values ​​as endpoints. Thus, using the above-described low-temperature aging heat treatment conditions, lithium can be converted into lithium sulfate, which facilitates subsequent extraction. Silicon remains in the form of silicon dioxide and does not dissolve. The lithium-containing leachate obtained from subsequent water leaching is essentially free of silicon, consisting mostly of lithium and aluminum, reducing the steps required for lithium enrichment and impurity removal.

[0042] According to embodiments of the present invention, the mass ratio of lithium ore powder to acid is 1:0.4 to 1:2. In some embodiments, the solid-liquid ratio of lithium ore powder to acid is 1:0.4, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, or any two values ​​forming a range. This allows the lithium ore powder to react fully with the acid, improving the lithium extraction efficiency.

[0043] According to embodiments of the present invention, the acid is selected from sulfuric acid solution with a concentration of 50–98 wt%. In some embodiments, the concentration of the sulfuric acid solution is a range of 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, 95 wt%, 98 wt%, or any two of these values ​​as endpoints.

[0044] S300 aging, roasting, water leaching and solid-liquid separation treatment

[0045] In this step, the aging and roasting residue, template agent, and solvent are subjected to aging, roasting, water leaching, and solid-liquid separation to obtain a lithium-containing leachate and a mesoporous molecular sieve. During this process, lithium exists entirely in the form of lithium sulfate, while aluminum changes from aluminum sulfate to aluminum hydroxide, and after roasting, it becomes aluminum oxide. Through water leaching and then solid-liquid separation, the mesoporous molecular sieve and the lithium-containing solution are obtained. The entire process not only completes the preparation of the mesoporous molecular sieve but also yields a lithium-containing solution with an aluminum impurity content of less than 5 ppm, directly solving the industry problem of difficult aluminum separation without generating slag and addressing the issue of difficult tailings disposal. During the water leaching process, the lithium leaching rate can reach as high as 98%.

[0046] According to embodiments of the present invention, the template agent is selected from at least one of polymethyl methacrylate (also referred to as "PMMA" in this invention) and hexadecyltrimethylammonium bromide (also referred to as "CTAB" in this invention) and a poly(ethylene oxide-poly(propylene oxide-poly(ethylene oxide)) triblock copolymer (also referred to as "P123" in this invention). This allows for better promotion of mesoporous molecular sieve formation.

[0047] According to embodiments of the present invention, the molar ratio of polymethyl methacrylate or hexadecyltrimethylammonium bromide to the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is 1:1 to 1:5. In some embodiments, the molar ratio of polymethyl methacrylate or hexadecyltrimethylammonium bromide to the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is 1:1, 1:2, 1:3, 1:4, 1:5, or any two values ​​forming a range. Thus, mesoporous molecular sieves with large specific surface area and excellent performance can be obtained.

[0048] According to embodiments of the present invention, the mass ratio of the aging and roasting residue to the template agent is 1:0.01 to 1:0.06. In some embodiments, the mass ratio of the aging and roasting residue to the template agent is 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, or any two values ​​forming a range. This allows for the formation of mesoporous molecular sieves with superior performance.

[0049] According to embodiments of the present invention, the solvent is selected from sodium hydroxide solution. Sodium hydroxide is a component of the molecular sieve and not only participates in the condensation reaction of silicate and aluminate ions, but also is one of the factors affecting the alkalinity of the reaction system. The ratio of the total molar amount of sodium hydroxide ions in the sodium hydroxide solution and sodium oxide in the aging roasting residue to the molar amount of silicon dioxide in the aging roasting residue is 0.6:1 to 1.4:1, calculated as n(Na2O) / n(SiO2), where n(Na2O) / n(SiO2) is the molar ratio of Na2O to SiO2. In some embodiments, n(Na2O) / n(SiO2) is 0.6:1, 0.8:1, 1:1, 1.2:1, 1.4:1, or any two values ​​forming a range. This allows for the better formation of mesoporous molecular sieves with excellent performance.

[0050] According to embodiments of the present invention, the aging treatment temperature is 70–120°C, and the time is 10–48 hours. In some embodiments, the aging treatment temperature is a range formed by 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any two of these values ​​as endpoints, and the time is a range formed by 10 hours, 12 hours, 18 hours, 20 hours, 24 hours, 36 hours, 48 ​​hours, or any two of these values ​​as endpoints. Therefore, the above-described aging treatment can further improve the material's properties and structure, such as enhancing its thermal stability, mechanical properties, and adsorption properties.

[0051] According to embodiments of the present invention, the calcination treatment temperature is 700–800°C, and the time is 1–5 hours. In some embodiments, the calcination treatment temperature is a range formed by using 700°C, 720°C, 750°C, 780°C, 800°C, or any two of these values ​​as endpoints, and the time is a range formed by using 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or any two of these values ​​as endpoints. This allows for the removal of the template agent, improving the thermal stability and structural order of the mesoporous molecular sieve.

[0052] According to embodiments of the present invention, the solid-liquid ratio of the water leaching treatment is 1:2 to 1:10. In some embodiments, the solid-liquid ratio of the water leaching treatment is 1:2, 1:3, 1:4, 1:5, 1:8, 1:10, or any two values ​​forming a range. This facilitates more complete lithium extraction and improves lithium yield.

[0053] According to embodiments of the present invention, the water leaching treatment is performed at a temperature of 25–90°C for a duration of 0.5–4 hours. In some embodiments, the water leaching treatment temperature is a range formed by using 25°C, 30°C, 50°C, 60°C, 80°C, 85°C, 90°C, or any two of these values ​​as endpoints, and the time is a range formed by using 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, or any two of these values ​​as endpoints. This facilitates more complete extraction of lithium and improves the lithium yield.

[0054] S400 aluminum and calcium removal treatment

[0055] In this step, the lithium-containing leachate is subjected to aluminum and calcium removal treatment to obtain a purified lithium sulfate solution. This improves the final purity of lithium hydroxide.

[0056] According to an embodiment of the present invention, the aluminum removal process includes: adjusting the pH of the lithium-containing leaching solution to 6.0–7.0 using lithium hydroxide (for example, a range of values ​​including 6.0, 6.2, 6.5, 6.8, 7.0, or any two values ​​as endpoints), causing aluminum to precipitate, followed by solid-liquid separation to obtain aluminum slag and filtrate. The filtrate is then subjected to the pH adjustment and solid-liquid separation steps 0–3 times to obtain a purified solution. This effectively removes aluminum, and the use of lithium hydroxide for pH adjustment avoids the introduction of other impurities. By repeatedly adjusting the pH and performing the solid-liquid separation steps, aluminum impurities can be thoroughly removed, improving the purity of the lithium hydroxide.

[0057] According to an embodiment of the present invention, the calcium removal treatment includes: mixing the purified liquid obtained from the aluminum removal treatment with lithium carbonate, and adjusting the pH value to 9.5–10.5 (for example, a range formed by using 9.5, 9.8, 10.0, 10.2, 10.5, or any two values ​​as endpoints), causing calcium to precipitate, resulting in solid-liquid separation, and obtaining calcium slag and lithium sulfate purified liquid. This effectively removes calcium, and the use of lithium carbonate to adjust the pH value avoids the introduction of other impurities.

[0058] S500 Electrodialysis

[0059] In this step, the purified lithium sulfate solution is passed through a bipolar membrane electrodialysis system for electrodialysis to obtain a lithium hydroxide solution and a sulfuric acid solution. This achieves a one-step process for obtaining lithium hydroxide solution while simultaneously recovering sulfuric acid, facilitating its recycling and significantly reducing acid and alkali consumption in the process, thus realizing green and clean production.

[0060] According to an embodiment of the present invention, see Figure 2 The bipolar membrane electrodialysis system includes an acid chamber, an alkali chamber, and a salt chamber. The acid chamber contains water, the alkali chamber contains a lithium hydroxide solution, and the lithium sulfate purification solution is passed through the salt chamber. After electrodialysis, a lithium hydroxide solution is obtained in the alkali chamber, and a sulfuric acid solution is obtained in the acid chamber. By adding a lithium hydroxide solution to the alkali chamber, the conductivity and the concentration of lithium hydroxide in the alkali chamber in the later stages can be improved. In some embodiments, the concentration of the sulfuric acid solution obtained in the acid chamber can be 80%, 85%, 90%, 95%, 99%, 100%, etc.

[0061] It should be noted that the bipolar membrane electrodialysis system used in this invention is well known in the art, and its components, such as cation exchange membranes and anion exchange membranes, can be selected using conventional methods according to actual needs. The inventors have creatively chosen to add specific substances to the acid, alkali, and salt chambers to effectively separate and extract lithium hydroxide and sulfuric acid. Adding lithium hydroxide solution to the alkali chamber can improve conductivity and the concentration of lithium hydroxide in the later stages of the process.

[0062] According to an embodiment of the present invention, the method further includes: evaporating and concentrating the lithium hydroxide solution and recrystallizing it to obtain lithium hydroxide monohydrate. This further improves the purity of lithium hydroxide, producing high-purity lithium hydroxide products that meet battery-grade standards and the quality requirements of batteries in the new energy industry, making them suitable for use in the manufacture of lithium batteries for new energy vehicles.

[0063] According to an embodiment of the present invention, see Figure 3 The method includes the following steps:

[0064] S1: Crush sedimentary lithium ore to a particle size of less than 0.074 mm, with 70-80% of the particles being less than 0.074 mm, to obtain sedimentary lithium ore powder;

[0065] S2: After the lithium ore powder is mixed evenly with sulfuric acid, it is subjected to aging treatment to obtain aging roasting residue;

[0066] S3: Cool the calcined residue to room temperature, dissolve a certain amount of template agent in an appropriate amount of water, add it to the calcined product obtained in step S2, and then add a certain amount of NaOH for aging (in this invention, it can also be called "aging").

[0067] S4: The product obtained in step S3 is roasted (in this invention, it can also be referred to as "roasting and decomposition");

[0068] S5: Cool the calcined product obtained in step S4 to room temperature, then add deionized water to the calcined product for water leaching, and obtain a mixed solution by leaching. After leaching, obtain a lithium-containing solution and mesoporous molecular sieve by solid-liquid separation.

[0069] S6: Precipitate the lithium-containing solution to remove aluminum and calcium impurities, and obtain purified lithium sulfate solution;

[0070] S7: The obtained lithium sulfate purified solution is passed into a bipolar membrane electrodialysis system for electrodialysis to obtain a high-concentration lithium hydroxide solution and sulfuric acid solution. The sulfuric acid solution can be recycled for the aging treatment in step S2.

[0071] S8: The high-concentration lithium hydroxide solution obtained in step S7 is evaporated, concentrated, and then recrystallized to obtain electronic-grade lithium hydroxide monohydrate product.

[0072] Beneficial effects

[0073] 1. This invention has the advantages of strong adaptability to raw materials, short process, few steps, and high lithium extraction rate. It transforms aluminum-silicon waste residue from sedimentary lithium mines into high-value-added mesoporous molecular sieve products, while effectively solving the problem of difficult lithium-aluminum separation in the leaching solution of traditional sulfuric acid process, thus inhibiting aluminum leaching at the source.

[0074] 2. This invention uses bipolar membrane electrodialysis to achieve one-step preparation of electronic-grade lithium hydroxide, while simultaneously regenerating sulfuric acid, realizing the recycling of sulfuric acid, greatly reducing the consumption of acid and alkali in the process, and achieving green and clean production;

[0075] 3. This invention simultaneously realizes the comprehensive utilization of valuable elements such as lithium, aluminum, and silicon in sedimentary lithium mines, greatly reducing the large amount of solid waste pollution generated by traditional lithium extraction from ore, and has great economic value.

[0076] 4. In the water leaching process, the lithium leaching rate of this invention can reach up to 98%.

[0077] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0078] Example 1

[0079] S1: Grind 100g of sedimentary lithium ore to a particle size of less than 0.074mm, accounting for 70-80% of the total.

[0080] S2: Mix 100g of fine lithium ore powder with 50g of 98wt% sulfuric acid evenly, and then mature at 250℃ for 3h to obtain matured roasting residue;

[0081] S3: Dissolve 2g of mixed template agent P123 and PMMA in water, with a molar ratio of P123 to PMMA of 2:1 and a mass ratio of aging roasting residue to mixed template agent of 1:0.02; then add it to the aging product obtained in step S2, and add a certain amount of NaOH with a molar ratio of n(Na2O) / n(SiO2) of 1.2:1, and age at 100℃ for 48h;

[0082] S4 The aging product obtained in step S3 is further heated to 800℃ and calcined for 2 hours to decompose it.

[0083] S5: Cool the calcined product obtained in step S4 to room temperature, then add deionized water to the calcined product for water leaching to obtain a mixed solution. The solid-liquid ratio of the calcined product to the deionized water is 1:3, the water leaching temperature is 85℃, and the leaching time is 2 hours. After leaching, solid-liquid separation is performed to obtain a lithium-containing leachate and a mesoporous molecular sieve product (tested by a Konta Autosorb-1-C-TCD-MS fully automatic physicochemical gas adsorption instrument: specific surface area 788 m²). 2 / g, pore size is 8nm);

[0084] ICP analysis of the leachate revealed that the lithium leaching rate reached 98% (lithium content in leachate / lithium content in lithium ore × 100%), while the aluminum content in the leachate was only 5 ppm, with a leaching rate of less than 0.05% (aluminum content in leachate / aluminum content in lithium ore × 100%), achieving selective lithium extraction.

[0085] S6: Purify the leachate to remove aluminum and calcium impurities, and obtain lithium sulfate purified solution.

[0086] Aluminum removal treatment: The pH of the lithium-containing leaching solution is adjusted to 6.0-7.0 using lithium hydroxide to precipitate aluminum, and solid-liquid separation is performed to obtain aluminum slag and filtrate. The filtrate is then subjected to the pH adjustment process twice to obtain a purified solution.

[0087] Calcium removal treatment: The purified liquid obtained from the aluminum removal treatment is mixed with lithium carbonate, and the pH value is adjusted to 9.5-10.5 to precipitate calcium, and the solid and liquid are separated to obtain calcium slag and lithium sulfate purified liquid.

[0088] S7: The obtained purified lithium sulfate solution is passed into a bipolar membrane electrodialysis system for electrodialysis to obtain a high-concentration lithium hydroxide solution and a sulfuric acid solution.

[0089] S8: The high-concentration lithium hydroxide solution obtained in step S7 is subjected to MVR evaporation and concentration, and then recrystallized to obtain electronic-grade lithium hydroxide monohydrate product.

[0090] The composition of the obtained lithium hydroxide monohydrate product was tested, and the results are shown in Table 1. The product conforms to the GBT26008-2020 standard for battery-grade lithium hydroxide monohydrate.

[0091] Table 1. Composition of lithium hydroxide monohydrate product in Example 1

[0092]

[0093] Example 2

[0094] S1: Grind 100g of sedimentary lithium ore to a particle size of less than 0.074mm, accounting for 70-80%;

[0095] S2: Mix 100g of fine-grained lithium minerals with 150g of 50wt% sulfuric acid evenly, and then mature at 150℃ for 5h to obtain matured roasting residue;

[0096] S3: Dissolve 4g of mixed template agent P123 and CTAB in water, with a molar ratio of P123 to CTAB of 2:1 and a mass ratio of aging roasting residue to mixed template agent of 1:0.04; then add it to the aging product obtained in step S2, and add a certain amount of NaOH with a molar ratio of n(Na2O) / n(SiO2) of 0.8:1, and age at 75℃ for 24h;

[0097] S4 The aging product obtained in step S3 is further heated to 750℃ and calcined for 1 hour.

[0098] S5: Cool the calcined product obtained in step S4 to room temperature, then add deionized water to the calcined product for water leaching to obtain a mixed solution. The solid-liquid ratio of the calcined product to the deionized water is 1:8, the water leaching temperature is 50℃, and the leaching time is 3 hours. After leaching, solid-liquid separation is performed to obtain a lithium-containing leachate and a mesoporous molecular sieve product (tested by a Konta Autosorb-1-C-TCD-MS fully automatic physicochemical gas adsorption instrument: specific surface area 698 m²). 2 / g, pore size is 10nm);

[0099] ICP analysis of the leachate showed that the lithium leaching rate reached 92%, while the aluminum content in the leachate was only 3 ppm, with a leaching rate of less than 0.05%, thus achieving selective lithium extraction.

[0100] S6: Purify the leachate to remove aluminum and calcium impurities, and obtain lithium sulfate purified solution.

[0101] Aluminum removal treatment: The pH of the lithium-containing leaching solution is adjusted to 6.0-7.0 using lithium hydroxide to precipitate aluminum, and solid-liquid separation is performed to obtain aluminum slag and filtrate. The filtrate is then subjected to the pH adjustment process twice to obtain a purified solution.

[0102] Calcium removal treatment: The purified liquid obtained from the aluminum removal treatment is mixed with lithium carbonate, and the pH value is adjusted to 9.5-10.5 to precipitate calcium, and the solid and liquid are separated to obtain calcium slag and lithium sulfate purified liquid.

[0103] S7: The obtained purified lithium sulfate solution is passed into a bipolar membrane electrodialysis system for electrodialysis to obtain a high-concentration lithium hydroxide solution and a sulfuric acid solution.

[0104] S8: The high-concentration lithium hydroxide solution obtained in step S5 is subjected to MVR evaporation and concentration, and then recrystallized to obtain electronic-grade lithium hydroxide monohydrate product.

[0105] The composition of the obtained lithium hydroxide monohydrate product was tested, and the results are shown in Table 2. The product conforms to the GBT26008-2020 standard for battery-grade lithium hydroxide monohydrate.

[0106] Table 2. Composition of lithium hydroxide monohydrate product in Example 2

[0107]

[0108] Example 3

[0109] S1: Grind 100g of sedimentary lithium ore to a particle size of less than 0.074mm, accounting for 70-80% of the total.

[0110] S2: Mix 100g of fine-grained lithium minerals with 200g of 80wt% sulfuric acid evenly, and then mature at 280℃ for 3h to obtain matured roasting residue;

[0111] S3: Dissolve 6g of mixed template agent P123 and PMMA in water, with a molar ratio of P123 to PMMA of 2:1 and a mass ratio of aging roasting residue to mixed template agent of 1:0.06; then add it to the aging product obtained in step S2, and add a certain amount of NaOH with a molar ratio of n(Na2O) / n(SiO2) of 0.6:1, and age at 95℃ for 20h;

[0112] S4 The aging product obtained in step S3 is further heated to 700℃ and calcined for 1 hour to decompose it.

[0113] S5: Cool the calcined product obtained in step S4 to room temperature, then add deionized water to the calcined product for water leaching to obtain a mixed solution. The solid-liquid ratio of the calcined product to the deionized water is 1:5, the water leaching temperature is 80℃, and the leaching time is 3 hours. After leaching, solid-liquid separation is performed to obtain a lithium-containing leachate and a mesoporous molecular sieve product (tested by a Konta Autosorb-1-C-TCD-MS fully automatic physicochemical gas adsorption instrument: specific surface area 528 m²). 2 / g, pore size is 12nm);

[0114] ICP analysis of the leachate showed that the lithium leaching rate reached 96%, while the aluminum content in the leachate was only 5 ppm, with a leaching rate of less than 0.05%, thus achieving selective extraction of lithium.

[0115] S6: Purify the leachate to remove aluminum and calcium impurities, and obtain lithium sulfate purified solution.

[0116] Aluminum removal treatment: The pH of the lithium-containing leaching solution is adjusted to 6.0-7.0 using lithium hydroxide to precipitate aluminum, and solid-liquid separation is performed to obtain aluminum slag and filtrate. The filtrate is then subjected to the pH adjustment process twice to obtain a purified solution.

[0117] Calcium removal treatment: The purified liquid obtained from the aluminum removal treatment is mixed with lithium carbonate, and the pH value is adjusted to 9.5-10.5 to precipitate calcium, and the solid and liquid are separated to obtain calcium slag and lithium sulfate purified liquid.

[0118] S7: The obtained purified lithium sulfate solution is passed into a bipolar membrane electrodialysis system for electrodialysis to obtain a high-concentration lithium hydroxide solution and a sulfuric acid solution.

[0119] S8: The high-concentration lithium hydroxide solution obtained in step S7 is subjected to MVR evaporation and concentration, and then recrystallized to obtain electronic-grade lithium hydroxide monohydrate product.

[0120] The composition of the obtained lithium hydroxide monohydrate product was tested, and the results are shown in Table 3. The product conforms to the GBT26008-2020 standard for battery-grade lithium hydroxide monohydrate.

[0121] Table 3. Composition of lithium hydroxide monohydrate product in Example 3

[0122]

[0123] Comparative Example 1

[0124] S1: Grind 100g of sedimentary lithium ore to a particle size of less than 0.074mm, accounting for 70-80% of the total.

[0125] S2: Mix 100g of fine-grained lithium minerals with 50g of 98wt% sulfuric acid until homogeneous, and then ripen at 250℃ for 3h.

[0126] S3: Cool the calcined product obtained in step S2 to room temperature, then add deionized water to the calcined product and perform water leaching to obtain a mixed solution, wherein the solid-liquid ratio of the calcined product to the deionized water is 1:3, the water leaching temperature is 85℃, the leaching time is 2h, and the leachate is obtained.

[0127] ICP analysis of the leachate revealed that the lithium leaching rate reached 90%, while the aluminum content in the leachate was greater than 40 g / L, and the aluminum leaching rate was greater than 80%. The concentration of aluminum ions in the leachate was much greater than the concentration of lithium ions, making selective extraction of lithium impossible.

[0128] S4: Purify the leachate to remove aluminum impurities. Due to the large amount of aluminum hydroxide precipitate, a large amount of lithium ions are adsorbed during the purification process, making it impossible to obtain lithium sulfate purified solution.

[0129] Aluminum removal treatment: The pH of the lithium-containing leaching solution is adjusted to 6.0-7.0 using lithium hydroxide to precipitate aluminum, and solid-liquid separation is performed to obtain aluminum slag and filtrate. The pH of the filtrate is adjusted to solid-liquid separation twice.

[0130] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for the comprehensive utilization of sedimentary lithium deposits, characterized in that, include: Sedimentary lithium ore is crushed to obtain lithium ore powder; The lithium ore powder is subjected to aging heat treatment with acid to obtain aging roasting residue; The aged roasting residue, template agent and solvent are subjected to aging, roasting, water leaching and solid-liquid separation to obtain lithium-containing leachate and mesoporous molecular sieve; The lithium-containing leachate was subjected to aluminum and calcium removal treatment to obtain a purified lithium sulfate solution. The purified lithium sulfate solution was passed into a bipolar membrane electrodialysis system for electrodialysis to obtain a lithium hydroxide solution and a sulfuric acid solution.

2. The method according to claim 1, characterized in that, The aging heat treatment is performed at a temperature of 100–300°C for 2–6 hours. The mass ratio of lithium ore powder to acid is 1:0.4 to 1:2; The acid is selected from sulfuric acid solution with a concentration of 50–98 wt%.

3. The method according to claim 1, characterized in that, The template agent is selected from at least one of polymethyl methacrylate and hexadecyltrimethylammonium bromide and a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer; The molar ratio of the polymethyl methacrylate or hexadecyltrimethylammonium bromide to the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer is 1:1 to 1:

5.

4. The method according to claim 1, characterized in that, The mass ratio of the aging and roasting residue to the template agent is 1:0.01 to 1:0.06; The solvent is selected from sodium hydroxide solution, and the ratio of the total molar amount of sodium hydroxide ions in the sodium hydroxide solution and sodium oxide in the aging roasting residue to the molar amount of silicon dioxide in the aging roasting residue is 0.6:1 to 1.4:1, calculated as n(Na2O) / n(SiO2).

5. The method according to claim 1, characterized in that, The aging treatment is performed at a temperature of 70–120°C for a time of 10–48 hours.

6. The method according to claim 1, characterized in that, The roasting process is carried out at a temperature of 700–800°C for 1–5 hours.

7. The method according to claim 1, characterized in that, The solid-liquid ratio of the water leaching treatment is 1:2 to 1:10, the temperature of the water leaching treatment is 25 to 90°C, and the time is 0.5 to 4 hours.

8. The method according to claim 1, characterized in that, The aluminum removal process includes: adjusting the pH of the lithium-containing leaching solution to 6.0-7.0 using lithium hydroxide to precipitate aluminum, separating the solid and liquid to obtain aluminum slag and filtrate, and repeating the pH adjustment and solid-liquid separation steps of the filtrate 0-3 times to obtain purified solution; The calcium removal process includes: mixing the purified liquid with lithium carbonate and adjusting the pH value to 9.5-10.5 to precipitate calcium, separating the solid and liquid to obtain calcium slag and lithium sulfate purified liquid.

9. The method according to claim 1, characterized in that, The bipolar membrane electrodialysis system includes an acid chamber, an alkali chamber, and a salt chamber. The acid chamber contains water, the alkali chamber contains lithium hydroxide solution, and the lithium sulfate purification solution is introduced into the salt chamber. After the electrodialysis, a lithium hydroxide solution is obtained in the alkali chamber and a sulfuric acid solution is obtained in the acid chamber.

10. The method according to claim 1, characterized in that, Further includes: The lithium hydroxide solution was evaporated, concentrated, and recrystallized to obtain lithium hydroxide monohydrate.

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