Method for extracting lithium from lepidolite and concentration equipment

Abstract

The invention provides a method for extracting lithium from lepidolite and concentration equipment, and relates to the field of battery material production. The method for extracting the lithium from the lepidolite comprises the following steps: S1, adding sulfuric acid into the lepidolite, heating to 200-300 DEG C, roasting, destroying mineral lattices through an acid leaching process, stirring, leaching and filtering to obtain silicon dioxide and a mixed sulfate solution; and S2, cooling, crystallizing and filtering the mixed sulfate solution to obtain alum and a solution containing Li < + >. According to the method for extracting the lithium from the lepidolite, a small amount of lithium and aluminum contained in the gypsum residues generated in the process of extracting the lithium from the lepidolite are recycled, the gypsum residues are deeply treated, the characteristics of amphoteric hydroxides and reagent circulation are utilized, high-valued aluminum and lithium and a green closed loop are achieved, the treatment pressure of industrial solid waste is reduced, and the production cost is reduced. The environmental pollution risk is reduced, the maximum utilization of resources is realized, and the waste discharge is reduced.

Description

Technical Field

[0001] This invention relates to the field of battery material production, and in particular to a method and concentration equipment for extracting lithium from lepidolite. Background Technology

[0002] As the lightest metal, lithium possesses a range of properties that make it suitable for a wide variety of applications, including batteries, ceramics, glass, lubricants, aluminum smelting, and polymers. In recent years, lithium-based batteries have seen significant growth in their global market share.

[0003] Globally, over 80% of lithium production comes from salt lake brines (containing 0.06%-0.15% lithium) because extracting lithium from brines is far less expensive than extracting it from solid minerals. However, the rapid increase in demand for lithium-ion batteries from hybrid and electric vehicles may lead to future lithium resource shortages. Therefore, it is essential to utilize solid lithium minerals more efficiently and economically as a secondary resource to meet the growing demand for lithium and lithium salts.

[0004] Early lithium mica processing relied on the "high-temperature roasting-leaching" process, which had three major problems: high energy consumption and high pollution: limestone / sulfate roasting (800-1000℃) consumes more than 800 kg of standard coal per ton of lithium and emits waste gases such as SO2 and fluorides, with environmental protection costs accounting for more than 30% of the total investment.

[0005] Low element recovery rate: lithium extraction rate is only 60%-70%, rubidium and cesium are almost not recovered, and aluminum and silicon are piled up as waste residue;

[0006] Poor process compatibility: Traditional alkaline roasting produces insoluble aluminosilicates, which hinders the separation of subsequent associated elements, while acid leaching faces the dual challenges of equipment corrosion and interference from calcium and magnesium impurities.

[0007] Therefore, it is necessary to provide a method for extracting lithium from lepidolite to solve the above-mentioned technical problems. Summary of the Invention

[0008] This invention provides a method for extracting lithium from lepidolite, which solves the problems of low lithium extraction rate and room for improvement in the recovery of incidental elements such as rubidium and cesium in the high-temperature roasting-leaching process of lepidolite.

[0009] To solve the above-mentioned technical problems, the present invention provides a method and concentration equipment for extracting lithium from lepidolite, comprising the following steps:

[0010] S1. Add sulfuric acid to lepidolite, heat to 200-300℃ for roasting, then break the mineral lattice through acid leaching, stir, leach and filter to obtain silicon dioxide and mixed sulfate solution.

[0011] S2. The mixed sulfate solution was cooled, crystallized, and filtered to obtain alum and Li-containing compounds.+ The solution;

[0012] S3, Towards Li + Ca(OH)₂ was added to the solution, and after the reaction, the residue was filtered to obtain gypsum residue and Li-containing residue. + The new solution, for Li-containing + The new solution is evaporated and concentrated, and then carbonate is added and reacted to precipitate lithium carbonate.

[0013] S4. Mix alum with Ca(OH)2 and react. Filter to obtain gypsum residue and K-containing residue. + 、Rb + Cs + The solution was evaporated and concentrated to precipitate potassium sulfate, and then Rb was captured by molecularly imprinted resin. + Cs + To prepare rubidium salts and cesium salts;

[0014] S5. Mix the gypsum residue with water, then add NaOH solution and stir at 120-150℃ for 20-40 minutes. Filter to obtain gypsum and a mixture containing NaAlO2 and Li. + Digestion solution containing excess NaOH;

[0015] S6. Add fine Al(OH)3 powder to the digestion solution to achieve a KS value of 2.0. Then, slowly cool the filtrate from 70°C to 40°C. After stirring and reacting, filter to obtain aluminum hydroxide and a solution containing Li. + A solution of NaOH was prepared and then concentrated.

[0016] S7, Towards Li + Sodium dodecahydrate was added to the solution, and after stirring and reacting at 50-70℃, the solution was filtered, washed with water, and dried to obtain pure lithium phosphate and filtrate.

[0017] Preferably, the process further includes adding Ca(OH)2 to the filtrate in S7, reacting and then filtering to obtain a solution containing NaOH, which is then recycled back to S5.

[0018] Preferably, the carbonate in S3 is sodium carbonate or potassium carbonate.

[0019] The present invention also provides a concentration device for the method of extracting lithium from lepidolite, comprising: a concentration cylinder, wherein a heating structure is provided inside the concentration cylinder;

[0020] An exhaust pipe, wherein the exhaust pipe is connected to the top of the concentration cylinder;

[0021] A scraper structure is installed on the exhaust stack, and the output end of the scraper structure extends into the interior of the concentration stack.

[0022] A liquid storage tank, which is connected to the liquid outlet at the bottom of the concentration tank;

[0023] A filter structure, which is rotatably mounted inside the liquid storage cylinder;

[0024] A rotating device is used to drive the filter structure to rotate.

[0025] Preferably, the scraper structure includes a driving device, a rotating tube, and multiple scrapers. The top end of the rotating tube passes through and is rotatably mounted on the top end of the exhaust pipe, and the bottom end of the rotating tube extends into the interior of the concentration cylinder. The multiple scrapers are symmetrically mounted on the rotating tube, and a gap is left between the scrapers and the inner wall of the concentration cylinder.

[0026] Preferably, the filtration structure includes a mounting ring and a filter screen, wherein the mounting ring is rotatably mounted inside the liquid storage cylinder, and the filter screen is mounted inside the mounting ring;

[0027] The rotating device includes a mounting frame and a second motor. The mounting frame is mounted on the liquid storage cylinder, and the second motor is mounted on the mounting frame. The second motor passes through the liquid storage cylinder and is connected to the mounting ring.

[0028] Preferably, the concentration device further includes a rinsing structure for rinsing the non-filtering side of the filter screen.

[0029] Preferably, the flushing structure includes an L-shaped frame, a mounting pipe, a spray pipe, and an assembly pipe. One end of the L-shaped frame is installed at the bottom of the mounting ring, and the other end is suspended below the filter screen. The mounting pipe is rotatably installed on the L-shaped frame and aligned with the center of the filter screen. The spray pipe is horizontally connected to the top end of the mounting pipe, and the assembly pipe is installed at the other end of the mounting pipe.

[0030] The scraper structure also includes a rotary connector, an inlet pipe, and two drive blocks. The inlet pipe is connected to the rotary pipe through the rotary connector. The bottom end of the rotary pipe extends into the interior of the liquid storage cylinder. The two drive blocks are installed at intervals at the bottom end of the rotary pipe. The bottom end of the rotary pipe is set to a concave arc shape, and the bottom end of the assembly pipe is set to a convex arc shape.

[0031] When the rotating device drives the filter structure to flip, the assembly tube is located between the two driving blocks and is connected to the rotating tube.

[0032] Preferably, the drive device includes a bracket, a first motor, a main gear, and a driven gear. The first motor is mounted on the top of the exhaust pipe via the bracket. The main gear is mounted on the output end of the first motor. The driven gear is mounted on the rotating pipe. The main gear meshes with the driven gear.

[0033] Preferably, a rotating shaft is installed on both sides of the mounting ring, and a sliding groove is provided on both sides of the inner wall of the liquid storage cylinder, into which the rotating shaft slides.

[0034] Compared with related technologies, the method for extracting lithium from lepidolite provided by this invention has the following beneficial effects:

[0035] This invention provides a method for extracting lithium from lepidolite. The method involves treating lepidolite using a sulfuric acid roasting / acid leaching process to achieve full-component recovery of lithium from lepidolite ore. By utilizing the chemical properties of sulfates and crystallization separation, the method enables the synergistic extraction of multiple metals, solving the problems of resource waste and low economic efficiency in the lithium extraction industry chain, and improving the comprehensive utilization rate of lepidolite.

[0036] Furthermore, by utilizing the small amount of lithium and aluminum contained in the gypsum residue generated during the lithium extraction process from lepidolite, the gypsum residue can be deeply treated. By leveraging the amphoteric hydroxide properties and reagent recycling, high-value utilization and green closed-loop processing of aluminum and lithium can be achieved, reducing the pressure of industrial solid waste disposal, lowering the risk of environmental pollution, maximizing resource utilization, and reducing waste emissions, which aligns with the concepts of green chemistry and circular economy. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating the steps of a method for extracting lithium from lepidolite provided by the present invention.

[0038] Figure 2 This is a schematic diagram of the concentration equipment provided by the present invention;

[0039] Figure 3 for Figure 2 The diagram shows a cross-sectional view of the concentration equipment.

[0040] Figure 4 for Figure 3 The enlarged schematic diagram of part A shown below;

[0041] Figure 5 for Figure 3 The enlarged schematic diagram of section B is shown below;

[0042] Figure 6 Assembly diagram of the filter structure and rinsing structure provided by the present invention;

[0043] Figure 7 This is a schematic diagram showing the connection between the assembly tube and the rotating tube provided by the present invention.

[0044] Figure 8 for Figure 7 The enlarged schematic diagram of section C is shown below;

[0045] Figure 9 for Figure 8The side view of the assembly tube and the rotating tube shown.

[0046] Numbering on the map:

[0047] 1. Concentrating cylinder; 11. Heating structure; 12. Liquid addition pipe;

[0048] 2. Exhaust stack; 21. Exhaust pipe;

[0049] 3. Scraper structure; 31. Drive device; 32. Rotary tube; 33. Scraper; 34. Rotary connector; 35. Inlet pipe; 36. Drive block;

[0050] 311. Bracket; 312. First motor; 313. Main gear; 314. Driven gear;

[0051] 4. Liquid storage cylinder;

[0052] 5. Rotating device; 51. Mounting bracket; 52. Second motor;

[0053] 6. Filter structure; 61. Mounting ring; 62. Filter screen;

[0054] 7. Flushing structure; 71. L-shaped frame; 72. Installation pipe; 73. Spraying pipe; 74. Assembly pipe. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0056] This invention provides a method for extracting lithium from lepidolite.

[0057] Please refer to the following: Figure 1 In one embodiment of the present invention, the method for extracting lithium from lepidolite includes the following steps:

[0058] S1. Add sulfuric acid to lepidolite, heat to 200-300℃ for roasting, then break the mineral lattice through acid leaching, stir, leach and filter to obtain silicon dioxide and mixed sulfate solution.

[0059] S2. The mixed sulfate solution was cooled, crystallized, and filtered to obtain alum and Li-containing compounds. + The solution;

[0060] S3, Towards Li + Ca(OH)₂ was added to the solution, and after the reaction, the residue was filtered to obtain gypsum residue and Li-containing residue. +The new solution, for Li-containing + The new solution is evaporated and concentrated, and then carbonate is added and reacted to precipitate lithium carbonate.

[0061] S4. Mix alum with Ca(OH)2 and react. Filter to obtain gypsum residue and K-containing residue. + 、Rb + Cs + The solution was evaporated and concentrated to precipitate potassium sulfate, and then Rb was captured by molecularly imprinted resin. + Cs + To prepare rubidium salts and cesium salts;

[0062] S5. Mix the gypsum residue with water, then add NaOH solution and stir at 120-150℃ for 20-40 minutes. Filter to obtain gypsum and a mixture containing NaAlO2 and Li. + Digestion solution containing excess NaOH;

[0063] S6. Add fine Al(OH)3 powder to the digestion solution to achieve a KS value of 2.0. Then, slowly cool the filtrate from 70°C to 40°C. After stirring and reacting, filter to obtain aluminum hydroxide and a solution containing Li. + A solution of NaOH was prepared and then concentrated.

[0064] S7, Towards Li + Sodium dodecahydrate was added to the solution, and after stirring and reacting at 50-70℃, the solution was filtered, washed with water, and dried to obtain pure lithium phosphate and filtrate.

[0065] By processing lepidolite using sulfuric acid roasting / acid leaching, the full-component recovery of lithium from lepidolite ore is achieved. Utilizing the chemical properties of sulfates and crystallization separation, multi-metal synergistic extraction is realized, solving the problems of resource waste and low economic benefits in the lithium extraction industry chain, and improving the comprehensive utilization rate of lepidolite.

[0066] Furthermore, by utilizing the small amount of lithium and aluminum contained in the gypsum residue generated during the lithium extraction process from lepidolite, the gypsum residue can be deeply treated. By leveraging the amphoteric hydroxide properties and reagent recycling, high-value utilization and green closed-loop processing of aluminum and lithium can be achieved, reducing the pressure of industrial solid waste disposal, lowering the risk of environmental pollution, maximizing resource utilization, and reducing waste emissions, which aligns with the concepts of green chemistry and circular economy.

[0067] The mixed sulfate solution in S1 contains elements such as Li⁺, Al³⁺, K⁺, Rb⁺, Cs⁺, and SO₄²⁻;

[0068] S2 contains Li + The solution also includes Rb⁺, Cs⁺, SO4²⁻, etc., and the filtered solid phase contains Al, K and a small amount of residual Rb, Cs and other elements in addition to alum;

[0069] S3 contains Li + The new solution refers to the solution containing Li + The solution reacts with Ca(OH)2 to form precipitated sulfate ions, thus reducing the solution concentration.

[0070] In S4, sulfate ions combine with Ca²⁺ to form gypsum, aluminum is converted into aluminum hydroxide (Al(OH)3) precipitate, while K⁺, Rb⁺, and Cs⁺ dissolve as hydroxides (KOH, RbOH, CsOH). Solid-liquid separation yields gypsum residue and a solution containing K⁺, Rb⁺, Cs⁺, and OH⁻. The solution then proceeds to the concentration and recovery stage.

[0071] Furthermore, by evaporating and concentrating the liquid phase, the solubility differences of K₂SO₄, Rb₂SO₄, and Cs₂SO₄ are utilized (or combined with ion exchange resins / special extractants, such as tributyl phosphate TBP) for stepwise separation. First, potassium sulfate (K₂SO₄) precipitates, and then Rb is precisely captured using molecularly imprinted resin. + Cs⁺, to prepare high-purity rubidium and cesium salts;

[0072] In S7, the controlled molar ratio of lithium ions to phosphate ions is kept below the theoretical value (3:1).

[0073] It also includes adding Ca(OH)2 to the filtrate in S7, reacting and then filtering to obtain a solution containing NaOH, which is then recycled back to S5.

[0074] The sodium element in the S7 filtrate is recovered to generate NaOH solution for use in S5, thus achieving recycling.

[0075] The carbonate in S3 is sodium carbonate or potassium carbonate.

[0076] As an optional method in this embodiment, specifically: sulfuric acid (H2SO4) is added to lepidolite, heated to 250°C for calcination, and then acid leaching is used to destroy the mineral lattice. Stirring, leaching, and filtration yield silicon dioxide (SiO2) and a mixed sulfate solution.

[0077] Cooling, crystallization, and filtration yielded alum (KAl(SO4)2・12H2O) and Li-containing compounds. + The solution;

[0078] Xiang Han Li + Lime (Ca(OH)2) was added to the solution to precipitate sulfate ions, and the mixture was filtered to obtain gypsum residue and Li-containing residue. + dilute solutions containing Li; + The dilute solution was evaporated and concentrated, and then sodium carbonate (Na2CO3) / potassium carbonate (K2CO3) was added to precipitate lithium carbonate (Li2CO3).

[0079] When alum and lime are mixed and reacted, sulfate ions combine with Ca²⁺ to form gypsum, aluminum is converted into aluminum hydroxide (Al(OH)3) precipitate, and K⁺, Rb⁺, and Cs⁺ dissolve as hydroxides (KOH, RbOH, CsOH).

[0080] The filtration process yielded gypsum residue and a solution containing K⁺, Rb⁺, Cs⁺, and OH⁻. The solution was then concentrated by evaporation, and the residues were separated stepwise based on differences in solubility. Potassium sulfate (K₂SO₄) was first precipitated, and then Rb⁺ and Cs⁺ were precisely captured using molecularly imprinted resin to prepare high-purity rubidium and cesium salts.

[0081] 100g of gypsum residue from the lithium extraction process described above was mixed with 300ml of water, followed by the addition of NaOH solution. The mixture was heated at 136℃ for 30 minutes with a stirring speed of 250r / min to digest the gypsum residue. Heating and stirring disrupted the residue structure, causing aluminum and lithium to transfer from the solid phase to the liquid phase. Filtration yielded gypsum and a mixture containing NaAlO2 (aluminum component) and Li. + Digestion solution containing lithium components and excess NaOH.

[0082] Take 500 ml of the digestion solution and add seed crystals (fine Al(OH)3 powder) to achieve a KS value of 2.0 (KS represents the ratio of Al2O3 content in the introduced solution to Al2O3 content in the sodium aluminate solution). Then, slowly cool the filtrate from 70°C to 40°C and stir at 300 rpm for 8 hours to allow aluminum hydroxide to precipitate and crystallize. Filter to obtain aluminum hydroxide (Al(OH)3) and a solution containing Li. + A solution of NaOH was prepared and then concentrated.

[0083] Take 50ml containing Li + Sodium phosphate dodecahydrate (Na3PO4·12H2O) was added to the solution to adjust the molar ratio of lithium ions to phosphate to 3:1. The solution was reacted at 60℃ for 20 minutes with a stirring speed of 250 r / min, utilizing the low solubility of lithium phosphate (Li3PO4) to precipitate lithium. Filtration yielded crude lithium phosphate (Li3PO4) and a mixture containing Na... + PO4 3- A solution of crude lithium phosphate is prepared. The crude lithium phosphate is washed with water and dried to obtain pure lithium phosphate, while the solution is then recycled.

[0084] Lime (Ca(OH)2) is added to the concentrated phosphorus-containing solution that has not precipitated lithium, utilizing the low solubility of calcium phosphate to precipitate phosphorus. The liquid phase after phosphorus precipitation is the mother liquor, mainly containing NaOH, which is recycled back to the alkaline digestion reaction process and used for leaching of gypsum residue.

[0085] The present invention also provides a concentration device.

[0086] Please see Figure 2 and Figure 3 The present invention also provides a concentration device for the method of extracting lithium from lepidolite, comprising: a concentration cylinder 1, wherein a heating structure 11 is provided inside the concentration cylinder 1;

[0087] Exhaust pipe 2, which is connected to the top of the concentration cylinder 1;

[0088] Scraper structure 3 is installed on the exhaust stack 2, and the output end of the scraper structure 3 extends into the interior of the concentration stack 1;

[0089] Storage cylinder 4, which is connected to the liquid outlet at the bottom of the concentration cylinder 1;

[0090] Filter structure 6, which is rotatably installed inside the liquid storage cylinder 4;

[0091] Rotating device 5, which is used to drive the filter structure 6 to rotate.

[0092] In this embodiment, the concentration equipment is mainly used in S4 to evaporate and concentrate the solution.

[0093] The concentration equipment also includes a condenser. The exhaust pipe 21 of the exhaust stack 2 is connected to the inlet pipe of the condenser through a valve. The concentration cylinder 1 is equipped with a liquid addition pipe 12 for adding the solution to be cooled and condensed into the inside of the concentration cylinder 1. The inside of the concentration cylinder 1 is equipped with a heating structure 11, which includes a spiral tube, an inlet pipe, and a return pipe. A jacketed cavity is provided on the shell wall of the concentration cylinder 1. The spiral tube is located inside the jacket and is sleeved in the inner cylinder of the concentration cylinder 1. The inlet pipe and the return pipe are connected to the two ends of the spiral tube. The heating medium, such as high-temperature airflow or steam, is delivered into the spiral tube through the inlet pipe. The spiral tube heats the concentration cylinder 1 through the heating medium.

[0094] The bottom of the liquid storage cylinder 4 is equipped with a discharge pipe, and a valve is installed on the discharge pipe.

[0095] During operation, the heating structure 11 inside the concentration cylinder 1 is activated, and the solution to be concentrated is added into the concentration cylinder 1 through the liquid addition pipe 12. At the same time, the scraper structure 3 is activated, and the scraper structure 3 scrapes the incoming solution to the inner wall of the concentration cylinder 1 to form a thin film, thereby improving the concentration efficiency of the solution.

[0096] The concentrated solution flows into the storage tank 4 for collection. The concentrated potassium sulfate is filtered out by the filter structure 6. After the solution is discharged from the inside of the storage tank 4, the filter structure 6 is rotated 180 degrees by the rotating device 5. The filtered solid particles are now facing downwards and are discharged through the outlet end of the storage tank 4 by gravity. By setting up the filter structure 6 in conjunction with the rotating device 5, the precipitated solid and solution can be separated and discharged without the need for subsequent separation by filtration equipment, thus simplifying the operation.

[0097] When discharging solid particles, pure water can be added to the concentration cylinder 1 to rinse the scraper structure 3, so that the solid particles attached to the scraper structure 3 are left with the water flow. After the filter structure 6 is flipped, pure water can be added to the concentration cylinder 1 again. The water flow quickly carries the solid particles away from the filter structure 6, and the water flow can also carry away the solid particles that fall on the inner wall of the storage cylinder 4.

[0098] Among them, pure water is added into the concentration tank 1 to rinse the scraper structure 3. Pure water can be added through the liquid addition pipe 12 for cleaning, or a spray structure can be set at the top inside the concentration tank 1, and water can be supplied to the spray structure through an external water supply system to clean the scraper structure 3 by spraying pure water.

[0099] During operation, the evaporated steam is discharged through exhaust pipe 2 to the condenser for condensation treatment;

[0100] Preferred concentration equipment may also include a vacuum device for removing air from the concentration equipment and lowering the evaporation temperature of the solution by means of a vacuum.

[0101] Please see Figure 3 In this embodiment, the scraper structure 3 includes a driving device 31, a rotating tube 32 and a plurality of scrapers 33. The top end of the rotating tube 32 passes through and is rotatably mounted on the top end of the exhaust pipe 2, and the bottom end of the rotating tube 32 extends into the interior of the concentration cylinder 1. The plurality of scrapers 33 are symmetrically mounted on the rotating tube 32, and a gap is left between the scrapers 33 and the inner wall of the concentration cylinder 1.

[0102] During operation, the drive unit 31 drives the rotating tube 32 to rotate the scraper 33. The scraper 33 causes the incoming solution to come into contact with the inner wall of the concentration cylinder 1 for evaporation and cooling.

[0103] The rotating pipe 32 and the exhaust pipe 2 are mechanically sealed at the point where they pass through each other. A fixed frame is installed inside the exhaust pipe 2 to provide auxiliary support for the rotating pipe 32. The rotating pipe 32 passes through the fixed frame and is rotatably connected to the fixed frame.

[0104] The scraper structure 3 is made of high temperature resistant and corrosion resistant materials, and the scraper 33 is preferably an elastic plate. The elastic part of the scraper 33 is made of polytetrafluoroethylene (PTFE) or fluororubber.

[0105] Please see Figure 5 In this embodiment, the filter structure 6 includes a mounting ring 61 and a filter screen 62. The mounting ring 61 is rotatably mounted inside the liquid storage cylinder 4, and the filter screen 62 is mounted inside the mounting ring 61.

[0106] The rotating device 5 includes a mounting frame 51 and a second motor 52. The mounting frame 51 is mounted on the liquid storage cylinder 4, and the second motor 52 is mounted on the mounting frame 51. The second motor 52 passes through the liquid storage cylinder 4 and is connected to the mounting ring 61.

[0107] During the concentration process, the concentrated solution passes through filter screen 62 and enters the lower part of the storage cylinder 4 for storage. The precipitated solid particles are filtered above filter screen 62. The second motor 52 drives the mounting ring 61 to rotate filter screen 62 180 degrees. At this time, the solid particles face downwards and fall off for separation.

[0108] The connection between the output shaft of the second motor 52 and the liquid storage tank 4 is mechanically sealed.

[0109] In other embodiments, the filter structure 6 may also include a perforated plate and a filter screen 62, with the filter screen 62 mounted on top of the perforated plate. The perforated plate is rotatably mounted inside the liquid storage cylinder 4, and the rotating device 5 is used to drive the perforated plate to rotate.

[0110] Please see Figure 3 and Figure 5 As an optional embodiment, the concentration device further includes a rinsing structure 7, which is used to rinse the non-filtering side of the filter screen 62.

[0111] By setting the rinsing structure 7, the non-filtering side, i.e. the top surface, of the flipped filter screen 62 is directly rinsed to achieve backwashing of the filter screen 62. The rinsing can quickly separate and discharge solid particles, and can also automatically backwash and clean the filter screen 62.

[0112] Please see Figure 5 As an optional embodiment, the flushing structure 7 includes an L-shaped frame 71, a mounting pipe 72, a spray pipe 73, and an assembly pipe 74. One end of the L-shaped frame 71 is installed at the bottom of the mounting ring 61, and the other end is suspended below the filter screen 62. The mounting pipe 72 is rotatably installed on the L-shaped frame 71 and aligned with the center of the filter screen 62. The spray pipe 73 is horizontally connected to the top end of the mounting pipe 72, and the assembly pipe 74 is installed at the other end of the mounting pipe 72.

[0113] The scraper structure 3 also includes a rotary connector 34, an inlet pipe 35, and two drive blocks 36. The inlet pipe 35 is connected to the rotary pipe 32 through the rotary connector 34. The bottom end of the rotary pipe 32 extends into the interior of the liquid storage cylinder 4. The two drive blocks 36 are spaced apart at the bottom end of the rotary pipe 32. The bottom end of the rotary pipe 32 is set in a concave arc shape, and the bottom end of the assembly pipe 74 is set in a convex arc shape.

[0114] When the rotating device 5 drives the filter structure 6 to flip, the assembly tube 74 is located between the two driving blocks 36 and is connected to the rotating tube 32.

[0115] The end of the inlet pipe 35 away from the rotary connector 34 is connected to the output end of the water pump, and the input end of the water pump is connected to the water storage container through a pipe.

[0116] When the solid particles filtered off the filter screen 62 are discharged, the second motor 52 drives the filter screen 62 to flip via the mounting ring 61. The mounting ring 61 drives the entire rinsing structure 7 to flip upwards via the L-shaped frame 71, and the assembly tube 74 is located between the two driving blocks 36. At the same time, the convex arc shape of the assembly tube 74 abuts against the concave arc shape at the bottom end of the rotating tube 32, thereby realizing the connection between the assembly tube 74 and the rotating tube 32. Figure 8 and Figure 9 ;

[0117] Subsequently, cleaning fluid is supplied to the interior of the rotating tube 32 through the inlet pipe 35. The cleaning fluid enters the spray pipe 73 through the rotating tube 32, the assembly pipe 74, and the installation pipe 72 in sequence. The cleaning fluid is then sprayed onto the filter screen 62 by the spray pipe 73. At the same time, the drive device 31 drives the rotating tube 32 to rotate. The rotating tube 32 drives the assembly pipe 74 to rotate through the drive block 36. The assembly pipe 74 drives the spray pipe 73 to rotate through the installation pipe 72, thereby enabling a thorough rinsing of the filter screen 62.

[0118] Thus, the scraper structure 3 is used in one state to scrape the solution against the inner wall of the concentration cylinder 1 for concentration and evaporation, and in another state to provide cleaning liquid to the rinsing structure 7 and drive the spray pipe 73 to rotate to thoroughly clean the filter screen 62. The two states are switched during the process of turning the filter screen 62 to discharge solid particles.

[0119] The use of the rotating tube 32 in the scraper structure 3 to supply liquid to the flushing structure 7, and the scraper structure 3 driving the flushing structure 7 to rotate, greatly simplifies the overall structure.

[0120] By setting the rotary connector 34, the inlet pipe 35 does not need to rotate when the rotary tube 32 rotates.

[0121] The convex arc of the assembly tube 74 and the concave arc of the bottom end of the rotating tube 32 are adapted to the arc of the trajectory of the filter structure 6 driving the rinsing structure 7 to rotate. Thus, after the rinsing structure 7 rotates 180 degrees, the assembly tube 74 can be smoothly assembled with the rotating tube 32. Preferably, a sealing strip is provided at the top end of the assembly tube 74 or the bottom end of the rotating tube 32 to improve the sealing performance during connection.

[0122] The spray pipe 73 has a strip-shaped water outlet on the side facing the filter screen 62, or multiple fan-shaped nozzles are installed.

[0123] Among them, the flushing structure 7 is made of corrosion-resistant material or is treated with corrosion protection.

[0124] As another alternative in this embodiment, a separate drive motor can be provided to drive the installation pipe 72 to rotate, and a separate water supply system can be provided to supply water to the installation pipe 72.

[0125] Please see Figure 4 In this example, the drive device 31 includes a bracket 311, a first motor 312, a main gear 313, and a driven gear 314. The first motor 312 is mounted on the top of the exhaust pipe 2 via the bracket 311. The main gear 313 is mounted on the output end of the first motor 312. The driven gear 314 is mounted on the rotating tube 32. The main gear 313 meshes with the driven gear 314.

[0126] During operation, the first motor 312 drives the main gear 313 to rotate the driven gear 314, which in turn drives the rotating tube 32 to rotate, thus achieving the function of driving the rotating tube 32 to rotate.

[0127] In other embodiments, the main gear 313 and the driven gear 314 may be replaced with a pulley structure or a synchronous pulley and synchronous belt, etc.

[0128] In this embodiment, rotating shafts are installed on both sides of the mounting ring 61, and sliding grooves are provided on both sides of the inner wall of the liquid storage cylinder 4, with the rotating shafts corresponding to slide into the sliding grooves.

[0129] When installing the filter structure 6, the liquid storage cylinder 4 is disassembled and separated from the concentration cylinder 1. Then, the cylinder cover of the liquid storage cylinder 4 is opened, and the rotating shafts on both sides of the filter structure 6 are slid into the sliding grooves on both sides of the inner wall of the liquid storage cylinder 4. The slids stop when they reach the lowest end of the sliding groove, thus realizing the installation of the filter structure 6, which facilitates the installation and disassembly of the filter structure 6.

[0130] Meanwhile, one of the rotating shafts has an opening, such as Figure 6A square shaft is provided to match the opening of the output shaft of the second motor 52. The square shaft is located in a groove. When installing the filter structure 6, the rotating shaft with the opening is slid into the groove with the square shaft and the square shaft is inserted into the socket to realize the assembly with the output shaft of the second motor 52.

[0131] The working principle of the method and concentration equipment for lithium extraction from lepidolite provided by this invention is as follows:

[0132] During operation, the heating structure 11 inside the concentration cylinder 1 is activated, and the solution to be concentrated is added into the concentration cylinder 1 through the liquid addition pipe 12. At the same time, the scraper structure 3 is activated, and the scraper structure 3 scrapes the incoming solution to the inner wall of the concentration cylinder 1 to form a thin film, thereby improving the concentration efficiency of the solution.

[0133] The concentrated solution flows into the storage tank 4 for collection. The concentrated potassium sulfate is filtered out by the filter structure 6. After the solution is discharged from the inside of the storage tank 4, the filter structure 6 is rotated 180 degrees by the rotating device 5. The filtered solid particles are now facing downwards and are discharged through the outlet end of the storage tank 4 by gravity. By setting up the filter structure 6 in conjunction with the rotating device 5, the precipitated solid and solution can be separated and discharged without the need for subsequent separation by filtration equipment, thus simplifying the operation.

[0134] When discharging the solid particles filtered from the filter screen 62, the second motor 52 drives the filter screen 62 to flip via the mounting ring 61. The mounting ring 61, through the L-shaped frame 71, drives the entire rinsing structure 7 to flip upwards, with the assembly tube 74 positioned between the two driving blocks 36. Simultaneously, the convex arc shape of the assembly tube 74 abuts against the concave arc shape at the bottom end of the rotating tube 32, thereby achieving communication between the assembly tube 74 and the rotating tube 32. Figure 8 and Figure 9 ;

[0135] Subsequently, cleaning fluid is supplied to the interior of the rotating tube 32 through the inlet pipe 35. The cleaning fluid enters the spray pipe 73 through the rotating tube 32, the assembly pipe 74, and the installation pipe 72 in sequence. The cleaning fluid is then sprayed onto the filter screen 62 by the spray pipe 73. At the same time, the drive device 31 drives the rotating tube 32 to rotate. The rotating tube 32 drives the assembly pipe 74 to rotate through the drive block 36. The assembly pipe 74 drives the spray pipe 73 to rotate through the installation pipe 72, thereby enabling a thorough rinsing of the filter screen 62.

[0136] Thus, the scraper structure 3 is used in one state to scrape the solution against the inner wall of the concentration cylinder 1 for concentration and evaporation, and in another state to provide cleaning liquid to the rinsing structure 7 and drive the spray pipe 73 to rotate to thoroughly clean the filter screen 62. The two states are switched during the process of turning the filter screen 62 to discharge solid particles.

[0137] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for extracting lithium from lepidolite, characterized in that, Includes the following steps: S1. Add sulfuric acid to lepidolite, heat to 200-300℃ for roasting, then break the mineral lattice through acid leaching, stir, leach and filter to obtain silicon dioxide and mixed sulfate solution. S2. The mixed sulfate solution was cooled, crystallized, and filtered to obtain alum and Li-containing compounds. + The solution; S3, Towards Li + Ca(OH)₂ was added to the solution, and after the reaction, the residue was filtered to obtain gypsum residue and Li-containing residue. + The new solution, for Li-containing + The new solution is evaporated and concentrated, and then carbonate is added and reacted to precipitate lithium carbonate. S4. Mix alum with Ca(OH)2 and react. Filter to obtain gypsum residue and K-containing residue. + 、Rb + Cs + The solution was evaporated and concentrated to precipitate potassium sulfate, and then Rb was captured by molecularly imprinted resin. + Cs + To prepare rubidium salts and cesium salts; S5. Mix the gypsum residue with water, then add NaOH solution and stir at 120-150℃ for 20-40 minutes. Filter to obtain gypsum and a mixture containing NaAlO2 and Li. + Digestion solution containing excess NaOH; S6. Add fine Al(OH)3 powder to the digestion solution to achieve a KS value of 2.

0. Then, slowly cool the filtrate from 70°C to 40°C. After stirring and reacting, filter to obtain aluminum hydroxide and a solution containing Li. + A solution of NaOH was prepared and then concentrated. S7, Towards Li + Sodium dodecahydrate was added to the solution, and after stirring and reacting at 50-70℃, the solution was filtered, washed with water, and dried to obtain pure lithium phosphate and filtrate.

2. The method for extracting lithium from lepidolite according to claim 1, characterized in that, It also includes adding Ca(OH)2 to the filtrate in S7, reacting and then filtering to obtain a solution containing NaOH, which is then recycled back to S5.

3. The method for extracting lithium from lepidolite according to claim 1, characterized in that, The carbonate in S3 is sodium carbonate or potassium carbonate.

4. A concentration device, characterized in that, A method for extracting lithium from lepidolite as described in any one of claims 1-3, comprising: a concentration cylinder, wherein a heating structure is provided inside the concentration cylinder; An exhaust pipe, wherein the exhaust pipe is connected to the top of the concentration cylinder; A scraper structure is installed on the exhaust stack, and the output end of the scraper structure extends into the interior of the concentration stack. A liquid storage tank, which is connected to the liquid outlet at the bottom of the concentration tank; A filter structure, which is rotatably mounted inside the liquid storage cylinder; A rotating device is used to drive the filter structure to rotate.

5. The concentration device according to claim 4, characterized in that, The scraper structure includes a drive device, a rotating tube, and multiple scrapers. The top end of the rotating tube passes through and is rotatably mounted on the top end of the exhaust pipe, and the bottom end of the rotating tube extends into the interior of the concentration cylinder. Multiple scrapers are symmetrically mounted on the rotating tube, and a gap is left between the scrapers and the inner wall of the concentration cylinder.

6. The concentration apparatus according to claim 5, characterized in that, The filtration structure includes a mounting ring and a filter screen. The mounting ring is rotatably mounted inside the liquid storage cylinder, and the filter screen is mounted inside the mounting ring. The rotating device includes a mounting frame and a second motor. The mounting frame is mounted on the liquid storage cylinder, and the second motor is mounted on the mounting frame. The second motor passes through the liquid storage cylinder and is connected to the mounting ring.

7. The concentration apparatus according to claim 6, characterized in that, The concentration device also includes a rinsing structure for rinsing the non-filtering side of the filter screen.

8. The concentration apparatus according to claim 7, characterized in that, The flushing structure includes an L-shaped frame, a mounting pipe, a spray pipe, and an assembly pipe. One end of the L-shaped frame is installed at the bottom of the mounting ring, and the other end is suspended below the filter screen. The mounting pipe is rotatably installed on the L-shaped frame and aligned with the center of the filter screen. The spray pipe is horizontally connected to the top end of the mounting pipe, and the assembly pipe is installed at the other end of the mounting pipe. The scraper structure also includes a rotary connector, an inlet pipe, and two drive blocks. The inlet pipe is connected to the rotary pipe through the rotary connector. The bottom end of the rotary pipe extends into the interior of the liquid storage cylinder. The two drive blocks are installed at intervals at the bottom end of the rotary pipe. The bottom end of the rotary pipe is set to a concave arc shape, and the bottom end of the assembly pipe is set to a convex arc shape. When the rotating device drives the filter structure to flip, the assembly tube is located between the two driving blocks and is connected to the rotating tube.

9. The concentration apparatus according to claim 8, characterized in that, The drive device includes a bracket, a first motor, a main gear, and a driven gear. The first motor is mounted on the top of the exhaust pipe via the bracket. The main gear is mounted on the output end of the first motor. The driven gear is mounted on the rotating pipe. The main gear meshes with the driven gear.

10. The concentration apparatus according to claim 6, characterized in that, The mounting ring has a rotating shaft installed on both sides, and the inner wall of the liquid storage cylinder has a sliding groove on both sides, into which the rotating shaft slides.

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