Equipment and process for recovering positive electrode material of lithium battery by alkaline roasting of low-grade clay lithium ore

Abstract

The invention provides equipment and a process for recovering a lithium battery positive electrode material by alkaline roasting of low-grade clay lithium ore, and relates to the technical field of lithium phosphate preparation, the equipment comprises a reaction kettle, a medicament adding mechanism and an inert gas protection mechanism; the medicament adding mechanism comprises a rotating shaft which is vertically and rotatably connected to the interior of the reaction kettle, a driving disc is fixedly arranged on the surface of the rotating shaft, and two sliding blocks are slidably connected to the interior of the driving disc. According to the scheme, a rotating wheel rotates to intermittently extrude and release a medicine feeding hose, so that a sodium carbonate precipitant is pumped into a solution, four driving plates rotate, a guide frame is downwards extruded through a contact wheel, the guide frame downwards extrudes to drive a piston to slide downwards in an air outlet cylinder, nitrogen is conveyed to the position below the solution, and the sodium carbonate precipitant is pumped into the solution. And dosing and inert gas protection are synchronized, so that excessive lithium carbonate impurities caused by reaction of carbon dioxide and high-concentration Li < + > when a sodium carbonate precipitant is put are avoided, and the chemical purity of the product is ensured to meet the requirement of serving as a positive electrode material of a lithium battery.

Description

Technical Field

[0001] This invention relates to the field of lithium phosphate preparation, and more particularly to equipment and processes for recovering lithium battery cathode materials by alkaline roasting of low-grade clay lithium ore. Background Technology

[0002] Lithium phosphate is a white crystalline powder belonging to the orthorhombic crystal system. It has good thermal and chemical stability. Lithium iron phosphate is currently the mainstream cathode material for power batteries and energy storage batteries. In its preparation process, lithium phosphate is often used as the lithium source and phosphorus source. As a precursor or functional additive for cathode materials, lithium phosphate plays an important role in lithium battery systems.

[0003] In related technologies, with the development of the new energy vehicle industry, global lithium consumption is growing rapidly. Extracting lithium from abundant clay-type lithium mines is an effective strategy to ensure a high-quality, cost-effective lithium supply chain. However, existing equipment for recycling lithium battery cathode materials is not convenient for effective inert gas protection when adding precipitants. Carbon dioxide in the air dissolves into the strongly alkaline solution, causing a decrease in the chemical purity of the product and a deterioration in crystal morphology and particle size, which fails to meet the requirements for lithium battery cathode materials.

[0004] Therefore, it is necessary to provide equipment and processes for recovering lithium battery cathode materials from low-grade clay lithium ore through alkaline roasting to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides equipment and process for recovering lithium battery cathode materials from alkaline roasting of low-grade clay lithium ore, which solves the problem that existing equipment for recovering lithium battery cathode materials is not convenient to provide effective inert gas protection while adding precipitant during operation.

[0006] To solve the above-mentioned technical problems, the equipment for recovering lithium battery cathode materials by alkaline roasting of low-grade clay lithium ore provided by the present invention includes a reaction vessel, a reagent addition mechanism, and an inert gas protection mechanism.

[0007] The reagent addition mechanism includes a rotating shaft vertically rotatably connected to the inside of the reactor. A drive disk is fixedly mounted on the surface of the rotating shaft. Two sliders are slidably connected inside the drive disk. A rotating wheel is rotatably connected to the top of each slider. A chuck is mounted on the top of the drive disk. A drug inlet hose is mounted on the inner side of the chuck. The two rotating wheels are located inside the drive disk and are in contact with the drug inlet hose. Four connecting plates are arranged in a ring array on the circumferential side of the chuck. The four connecting plates are fixedly connected to the inner wall of the reactor.

[0008] The inert gas protection mechanism includes four drive plates located at the bottom of the drive plate. Each of the four drive plates has a screw fixed to its top. The four screws are divided into two groups, and the two groups of screws are threadedly connected to two sliders and the drive plate, respectively. An installation plate is fixed to the inner wall of the reactor and located at the bottom of the drive plate. Four guide frames are vertically slidably connected inside the installation plate. Contact wheels are rotatably connected to the inner side of the top of each of the four guide frames. Springs are sleeved on the surface of each of the four guide frames and located at the top of the installation plate. Four gas outlet cylinders are fixed to the bottom of the installation plate. Pistons are slidably connected inside each of the four gas outlet cylinders. The bottom of each of the four guide frames is fixedly connected to the top of the four pistons.

[0009] Preferably, the bottom of the mounting plate is provided with four connecting seats in a circular array, the inner side of the four connecting seats is provided with a ring tube, the bottom of the ring tube is provided with four nozzles in a circular array, and the drug delivery hose is connected to the ring tube.

[0010] Preferably, the bottom of each of the four air outlet cylinders is connected to an air outlet pipe, the bottom end of the air outlet pipe extends into the liquid, and one side of each of the four air outlet cylinders is connected to an air inlet pipe. Valves are provided on the surface of the air outlet pipe and the air inlet pipe.

[0011] Preferably, a switching feeding mechanism is fixedly provided at the bottom of the drive disk. The switching feeding mechanism includes two electric telescopic rods fixedly provided at the bottom of the drive disk. Each of the output ends of the two electric telescopic rods is fixedly provided with a connecting bracket. The two connecting brackets are respectively fixedly connected to the bottom of the two sliders. Each of the bottoms of the two connecting brackets is fixedly provided with a baffle. Two storage cylinders are fixedly provided on the inner side of the drive disk. The bottoms of the two storage cylinders are respectively in contact with the tops of the two baffles. Each of the bottoms of the two baffles is connected to a feeding pipe.

[0012] Preferably, a wall scraping mechanism is fixedly provided on the inner wall of the reactor and at the bottom of the mounting plate. The wall scraping mechanism includes a guide ring fixedly provided on the inner wall of the reactor. A rotating rail is rotatably connected to the surface of the guide ring. An internal gear disk is fixedly provided on the inner side of the rotating rail. Multiple scrapers are arranged in a circular array at the bottom of the rotating rail. A rotating shaft is vertically rotatably connected inside the mounting plate. A driving gear is fixedly provided at the top end of the rotating shaft. A driven gear is fixedly provided at the bottom end of the rotating shaft. The driven gear meshes with the internal gear disk. A tooth set is fixedly provided on the peripheral side of the driving plate. The tooth set meshes with the driving gear.

[0013] Preferably, a mixing mechanism is fixedly provided on the surface of the rotating shaft, the mixing mechanism includes three stirring paddles fixedly provided on the surface of the rotating shaft, a mixing paddle is fixedly provided at the bottom end of the rotating shaft, and a drive motor for driving the rotating shaft to rotate is provided at the top of the reactor.

[0014] Preferably, the left side of the reactor is connected to a feed pipe, the bottom of the reactor is connected to a discharge pipe, and the top of the reactor is connected to an exhaust pipe.

[0015] Preferably, a support frame is provided on the outer side of the reactor, and four connecting frames are fixedly provided on the inner side of the support frame. The opposite sides of the four connecting frames are fixedly connected to the peripheral side of the reactor, and support feet are provided at the bottom of the support frame.

[0016] The process for recovering lithium battery cathode materials from low-grade clay lithium ore by alkaline roasting includes the following steps:

[0017] Step S1: After uniformly mixing clay-type lithium ore with sodium hydroxide additive, roast at 800℃ for 2 hours to obtain roasted clinker;

[0018] Step S2: The obtained roasted clinker is mixed with sulfuric acid solution at a stirring speed of 600 rpm to complete the leaching, and the solid and liquid are separated to obtain leaching solution and leaching residue;

[0019] Step S3: After drying the obtained leaching residue at 100°C, it is sieved through a 100-mesh sieve to obtain corundum and solid waste.

[0020] Step S4: Evaporate the leachate to form a gel, then dry the gel at 95 °C, and then calcine it to obtain a lithium-containing solid. Wash the solid with water to obtain mullite and a lithium-containing solution.

[0021] Step S5: Mix the obtained mullite with acid and wash it with acid to obtain purified mullite;

[0022] Step S6: Mix the obtained lithium-containing solution with sodium hydroxide solution, adjust the pH to 6.5 to remove iron and aluminum, and filter to obtain a lithium-free solution and precipitate;

[0023] Step S7: Evaporate and concentrate the impurity-removed lithium-containing solution to a suitable concentration, adjust the pH to 10 with sodium hydroxide, and then transfer it to the reaction vessel. Adjust the pH to 12 with sodium phosphate to form lithium phosphate.

[0024] Step S8: Add the obtained precipitate to sodium hydroxide solution, separate iron and aluminum by filtration to obtain iron hydroxide and sodium aluminate solution, adjust the pH of sodium aluminate solution to 5 and filter to obtain aluminum oxide.

[0025] Compared with related technologies, the equipment for recovering lithium battery cathode materials from low-grade clay lithium ore through alkaline roasting provided by this invention has the following beneficial effects:

[0026] The rotating shaft drives the drive disc to rotate, which in turn drives the rotating wheel and four drive plates to rotate. The rotating wheel intermittently squeezes and releases the inlet hose, thus pumping the sodium carbonate precipitant into the solution. The four drive plates rotate, pressing the guide frame downwards via the contact wheel. This downward pressure causes the piston to slide downwards within the gas outlet, delivering nitrogen gas to the submerged layer. The dosing and inert gas protection are synchronized, thus preventing the reaction of carbon dioxide and high-concentration Li during the addition of sodium carbonate precipitant. + The reaction caused lithium carbonate impurities to exceed the standard. To ensure that the chemical purity of the product meets the requirements for lithium battery cathode material, the dosing rate is matched with the intensity of inert gas bubbling, the process state is highly uniform, and the batch repeatability is excellent. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0028] Figure 1 The optimal structural schematic diagram provided for this invention;

[0029] Figure 2 This is a schematic diagram of the cross-sectional view of the reaction vessel provided by the present invention;

[0030] Figure 3 A schematic diagram of the structure of the drug addition mechanism provided by the present invention;

[0031] Figure 4 A schematic diagram of the inert gas protection mechanism provided by the present invention;

[0032] Figure 5 for Figure 4 The enlarged structural diagram at point A is shown below;

[0033] Figure 6 for Figure 4 The diagram shows a top view of the mounting plate.

[0034] Figure 7 for Figure 6 The diagram shows a cross-sectional view of the air outlet.

[0035] Figure 8 A schematic diagram showing the state in which the drive plate rotates counterclockwise due to the drive disc and the piston slides downwards due to the guide frame, provided by the present invention.

[0036] Figure 9 This is a schematic diagram of the switching feeding mechanism provided by the present invention;

[0037] Figure 10 This is a schematic diagram of the wall scraping mechanism provided by the present invention;

[0038] Figure 11 A schematic diagram showing the state in which the drive disk drives the tooth assembly to rotate counterclockwise, and the internal tooth disk is driven to rotate through the driving gear and the driven gear;

[0039] Figure 12 A schematic diagram of the structure of the mixing mechanism provided by the present invention;

[0040] Figure 13 This is a schematic diagram of the process flow provided by the present invention.

[0041] Explanation of icon numbers:

[0042] 1. Reactor;

[0043] 2. Drug dispensing mechanism; 21. Rotating shaft; 22. Drive disc; 23. Slider; 24. Rotary wheel; 25. Chuck; 26. Drug inlet hose; 27. Connecting plate;

[0044] 3. Inert gas protection mechanism; 31. Drive plate; 32. Screw; 33. Mounting plate; 34. Guide frame; 35. Contact wheel; 36. Spring; 37. Air outlet; 38. Piston;

[0045] 4. Connecting seat; 5. Ring pipe; 6. Nozzle;

[0046] 7. Switching feeding mechanism; 71. Electric telescopic rod; 72. Connecting bracket; 73. Baffle; 74. Storage cylinder; 75. Feeding pipe;

[0047] 8. Scraping mechanism; 81. Guide ring; 82. Rotating rail; 83. Internal gear disc; 84. Scraper; 85. Rotating shaft; 86. Driving gear; 87. Driven gear; 88. Gear assembly;

[0048] 9. Mixing mechanism; 91. Stirring paddle; 92. Mixing paddle; 93. Drive motor;

[0049] 10. Feed pipe; 11. Discharge pipe; 12. Exhaust pipe;

[0050] 13. Support frame; 14. Connecting frame; 15. Support leg. Detailed Implementation

[0051] 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.

[0052] This invention provides equipment for recovering lithium battery cathode materials by alkaline roasting of low-grade clay lithium ore.

[0053] First embodiment:

[0054] Please see Figures 1 to 8 Equipment for recovering lithium battery cathode materials by alkaline roasting of low-grade clay lithium ore, including a reaction vessel 1, a reagent addition mechanism 2 and an inert gas protection mechanism 3;

[0055] The reagent addition mechanism 2 includes a rotating shaft 21 vertically rotatably connected to the inside of the reactor 1. A drive disk 22 is fixedly mounted on the surface of the rotating shaft 21. Two sliders 23 are slidably connected inside the drive disk 22. A rotating wheel 24 is rotatably connected to the top of each of the two sliders 23. A chuck 25 is provided on the top of the drive disk 22. A drug inlet hose 26 is provided on the inner side of the chuck 25. The two rotating wheels 24 are located on the inner side of the drive disk 22 and are in contact with the drug inlet hose 26. Four connecting plates 27 are arranged in a ring array on the circumferential side of the chuck 25. The four connecting plates 27 are fixedly connected to the inner wall of the reactor 1.

[0056] The inert gas protection mechanism 3 includes four drive plates 31 disposed at the bottom of the drive plate 22. Each of the four drive plates 31 is fixedly provided with a screw 32 at its top. The four screws 32 are divided into two groups, and the two groups of screws 32 are respectively threadedly connected to two sliders 23 and the drive plate 22. An installation plate 33 is fixedly provided on the inner wall of the reactor 1 at the bottom of the drive plate 22. Four guide frames 34 are vertically slidably connected inside the installation plate 33. Contact wheels 35 are rotatably connected to the inner side of the top of each of the four guide frames 34. Springs 36 are sleeved on the surface of each of the four guide frames 34 at the top of the installation plate 33. Four gas outlet cylinders 37 are fixedly provided at the bottom of the installation plate 33. Pistons 38 are slidably connected inside each of the four gas outlet cylinders 37. The bottom of each of the four guide frames 34 is fixedly connected to the top of the four pistons 38.

[0057] The mounting plate 33 has four connecting seats 4 arranged in a ring array at its bottom. A ring tube 5 is arranged inside the four connecting seats 4. Four nozzles 6 are arranged in a ring array at the bottom of the ring tube 5. The drug delivery hose 26 is connected to the ring tube 5.

[0058] The bottom of each of the four air outlet cylinders 37 is connected to an air outlet pipe, the bottom end of which extends into the liquid. Each of the four air outlet cylinders 37 is connected to an air inlet pipe on one side. Valves are provided on the surface of both the air outlet pipe and the air inlet pipe.

[0059] Please combine Figure 3 : Start the drive motor 93. The drive motor 93 rotates and drives the rotating shaft 21 to rotate. The rotating shaft 21 rotates and drives the drive disk 22 to rotate. The rotation of the drive disk 22 drives the two rotating wheels 24 to rotate through the slider 23. The two rotating wheels 24 rotate and intermittently squeeze and release the drug inlet hose 26, thereby extracting sodium phosphate precipitant through negative pressure, and then injecting sodium phosphate precipitant into the solution from multiple directions through the annular pipe 5 and the nozzle 6.

[0060] Please combine Figures 4 to 8 When the drive disc 22 rotates, it will simultaneously drive the four screws 32 to rotate. The four screws 32 will then drive the four drive plates 31 to rotate. When the four drive plates 31 rotate, they will press the guide frame 34 downward through the contact wheel 35 and cause the spring 36 to contract. The guide frame 34 moves downward and drives the piston 38 to slide downward in the gas outlet cylinder 37, thereby delivering the inert gas to the liquid surface through the gas outlet pipe.

[0061] Furthermore, when the four drive plates 31 are continuously rotated by the drive disc 22, and the four drive plates 31 are disengaged from the contact wheel 35, the expansion of the spring 36 drives the guide frame 34 to move upward, and the upward movement of the guide frame 34 drives the piston 38 to move upward, thereby using the intake pipe to extract inert gas.

[0062] Preferably, the inert gas is nitrogen.

[0063] In this embodiment, the rotating shaft 21 drives the drive disc 22 to rotate. Simultaneously, the drive disc 22 rotates the rotating wheel 24 and four drive plates 31. The rotating wheel 24 intermittently squeezes and releases the drug delivery hose 26, thereby pumping the sodium carbonate precipitant into the solution. The four drive plates 31 rotate, pressing the guide frame 34 downwards via the contact wheel 35. This downward pressure causes the piston 38 to slide downwards within the gas outlet 37, thus delivering nitrogen gas to the submerged state. The drug delivery and inert gas protection are synchronized, preventing the reaction of carbon dioxide and high-concentration Li during the addition of the sodium carbonate precipitant. + The reaction caused lithium carbonate impurities to exceed the standard. To ensure that the chemical purity of the product meets the requirements for lithium battery cathode material, the dosing rate is matched with the intensity of inert gas bubbling, the process state is highly uniform, and the batch repeatability is excellent.

[0064] Second embodiment:

[0065] Please see Figures 9 to 11The bottom of the drive disk 22 is fixedly provided with a switching feeding mechanism 7. The switching feeding mechanism 7 includes two electric telescopic rods 71 ​​fixedly provided at the bottom of the drive disk 22. The output ends of the two electric telescopic rods 71 ​​are each fixedly provided with a connecting bracket 72. The two connecting brackets 72 are respectively fixedly connected to the bottom of the two sliders 23. The bottom of the two connecting brackets 72 is fixedly provided with a baffle 73. The inner side of the drive disk 22 is fixedly provided with two storage cylinders 74. The bottom of the two storage cylinders 74 are respectively in contact with the top of the two baffles 73. The bottom of the two baffles 73 are connected to a feeding pipe 75.

[0066] A wall scraping mechanism 8 is fixedly provided on the inner wall of the reactor 1 and at the bottom of the mounting plate 33. The wall scraping mechanism 8 includes a guide ring 81 fixedly provided on the inner wall of the reactor 1. A rotating rail 82 is rotatably connected to the surface of the guide ring 81. An internal gear disk 83 is fixedly provided on the inner side of the rotating rail 82. A plurality of scrapers 84 are arranged in a ring array at the bottom of the rotating rail 82. A rotating shaft 85 is vertically rotatably connected to the inside of the mounting plate 33. A driving gear 86 is fixedly provided at the top end of the rotating shaft 85. A driven gear 87 is fixedly provided at the bottom end of the rotating shaft 85. The driven gear 87 meshes with the internal gear disk 83. A tooth set 88 is fixedly provided on the peripheral side of the drive plate 22. The tooth set 88 meshes with the driving gear 86.

[0067] Please combine Figure 9 When the lithium-containing solution transitions from the reaction stage to the aging stage, the addition of sodium phosphate to the solution is stopped, and the two electric telescopic rods 71 ​​are activated to retract. The retraction of the two electric telescopic rods 71 ​​then drives the two sliders 23 to move to opposite sides via the two connecting brackets 72. The movement of the two sliders 23 drives the two rotating wheels 24 to move to opposite sides, canceling contact with the drug inlet hose 26. When the two connecting brackets 72 move to opposite sides, they also drive the two baffles 73 to move to opposite sides. When the dispensing pipe 75 and the storage cylinder 74 are connected, lithium phosphate seed crystals are added to the solution.

[0068] Preferably, by adding large-particle lithium phosphate seed crystals that have been sieved, a perfect growth template is provided for the system. During the Oswald aging process, lithium ions and phosphate ions in the solution will preferentially deposit on these seed crystals instead of spontaneously forming new small crystal nuclei or growing randomly. After adding seed crystals, the aging time can be significantly shortened, the particle size uniformity of the final product can be significantly improved, and high-quality crystals with consistent morphology can be obtained.

[0069] Furthermore, when the two sliders 23 move to the opposite side, they will simultaneously drive the two drive plates 31 at the bottom to move to the opposite side, thereby causing the rotation trajectory of the two drive plates 31 to disengage from the contact wheel 35. When the drive disc 22 rotates, it will intermittently squeeze the four contact wheels 35 through the two drive plates 31, thereby intermittently introducing nitrogen gas into the reactor 1 for protection during the aging stage.

[0070] Preferably, during the aging stage, the system maintains a strongly alkaline environment with a pH of 11.5-12. If it comes into contact with carbon dioxide in the air, it will react with Li in the solution. + The formation of lithium carbonate impurities, which are embedded in lithium phosphate crystals, will reduce the purity of the product.

[0071] Intermittent nitrogen replenishment can maintain a slight positive pressure inside the reactor, forming a gas seal to isolate the outside air. Compared with continuous ventilation, it can achieve full oxygen-free protection with a lower nitrogen consumption, avoid the formation of lithium carbonate impurities, and ensure the integrity of lithium phosphate crystal structure.

[0072] Preferably, during the aging stage, the rotational speed of the rotating shaft 21 will decrease.

[0073] Please combine Figure 10 and Figure 11 When the drive disk 22 rotates, it will simultaneously drive the tooth assembly 88 to rotate. The rotation of the tooth assembly 88 will then drive the drive gear 86 to rotate. The rotation of the drive gear 86 will drive the driven gear 87 to rotate via the rotating shaft 85. The rotation of the driven gear 87 will drive the internal tooth disk 83 and the rotating rail 82 to rotate. The rotation of the rotating rail 82 will then drive multiple scrapers 84 to rotate. The rotation of the scrapers 84 will scrape off the fine lithium phosphate crystals on the inner wall of the reactor 1.

[0074] In this embodiment, when the lithium-containing solution transitions from the reaction stage to the aging stage, the two electric telescopic rods 71 ​​retract, and the connecting bracket 72 drives the two sliders 23, the rotating wheel 24, the drive plate 31, and the baffle 73 to move to the opposite side, canceling the contact between the rotating wheel 24 and the drug inlet hose 26, so that the dispensing pipe 75 and the storage cylinder 74 are connected, thereby dispensing lithium phosphate seed crystals into the solution. After the two drive plates 31 move, their rotation trajectory will disengage from the contact wheel 35. Then, during the aging stage, when the drive disk 22 drives the drive plate 31 to rotate, nitrogen gas is intermittently supplied to the reactor 1 for protection. The intermittent ventilation only replenishes nitrogen gas briefly when the pressure inside the reactor is insufficient. There is no continuous airflow impact, which can maintain the stability of the liquid phase environment inside the reactor, ensuring that the crystals complete the aging under mild conditions, forming particles with regular morphology and uniform particle size, improving the electrochemical performance of the subsequent cathode material, and reducing nitrogen consumption. The energy saving and cost reduction effect is extremely significant.

[0075] As the drive disk 22 rotates, it drives the tooth assembly 88 to rotate. The tooth assembly 88 drives the internal tooth disk 83 and the rotating rail 82 to rotate via the drive gear 86, the rotating shaft 85 and the driven gear 87. The rotation of the rotating rail 82 drives multiple scrapers 84 to rotate, thereby scraping off the fine lithium phosphate crystals on the inner wall of the reactor 1. The real-time rotating scrapers 84 can thoroughly remove the newly formed microcrystals, ensuring that the wall surface is always smooth and the heat transfer coefficient is stable, providing a constant temperature field for crystal maturation.

[0076] Third embodiment:

[0077] Please see Figure 1 , Figure 2 and Figure 12 A mixing mechanism 9 is fixedly provided on the surface of the rotating shaft 21. The mixing mechanism 9 includes three stirring paddles 91 fixedly provided on the surface of the rotating shaft 21. A mixing paddle 92 is fixedly provided at the bottom end of the rotating shaft 21. A drive motor 93 for driving the rotating shaft 21 to rotate is provided at the top of the reactor 1.

[0078] The left side of the reactor 1 is connected to a feed pipe 10, the bottom of the reactor 1 is connected to a discharge pipe 11, and the top of the reactor 1 is connected to an exhaust pipe 12.

[0079] A support frame 13 is provided on the outside of the reactor 1, and four connecting frames 14 are fixedly provided on the inside of the support frame 13. The opposite sides of the four connecting frames 14 are fixedly connected to the peripheral side of the reactor 1. A support foot 15 is provided at the bottom of the support frame 13.

[0080] Please combine Figure 12 Start the drive motor 93. The drive motor 93 rotates, which in turn drives the rotating shaft 21 to rotate. The rotating shaft 21 rotates, which drives the stirring paddle 91 and the mixing paddle 92 to rotate, thereby mixing the solution with the sodium phosphate precipitant.

[0081] In this embodiment, the drive motor 93 rotates, which in turn drives the rotating shaft 21 to rotate. The rotating shaft 21 rotates, which drives the stirring paddle 91 and the mixing paddle 92 to rotate, mixing the solution with the sodium phosphate precipitant. During the reaction and aging stages, lithium phosphate solid particles are continuously generated and grow. The flow field generated by the mixing mechanism 9 ensures that all solid particles are uniformly suspended in the solution.

[0082] This invention also provides a process for recovering lithium battery cathode materials by alkaline roasting of low-grade clay lithium ore.

[0083] Please see Figure 13 The process for recovering lithium battery cathode materials by alkaline roasting of low-grade clay lithium ore includes the following steps:

[0084] Step S1: After uniformly mixing clay-type lithium ore with sodium hydroxide additive, roast at 800℃ for 2 hours to obtain roasted clinker;

[0085] Step S2: The obtained roasted clinker is mixed with sulfuric acid solution at a stirring speed of 600 rpm to complete the leaching, and the solid and liquid are separated to obtain leaching solution and leaching residue;

[0086] Step S3: After drying the obtained leaching residue at 100°C, it is sieved through a 100-mesh sieve to obtain corundum and solid waste.

[0087] Step S4: Evaporate the leachate to form a gel, then dry the gel at 95 °C, and then calcine it to obtain a lithium-containing solid. Wash the solid with water to obtain mullite and a lithium-containing solution.

[0088] Step S5: Mix the obtained mullite with acid and wash it with acid to obtain purified mullite;

[0089] Step S6: Mix the obtained lithium-containing solution with sodium hydroxide solution, adjust the pH to 6.5 to remove iron and aluminum, and filter to obtain a lithium-free solution and precipitate;

[0090] Step S7: Evaporate and concentrate the impurity-removed lithium-containing solution to a suitable concentration, adjust the pH to 10 with sodium hydroxide, and then transfer it to reactor 1, adjust the pH to 12 with sodium phosphate to form lithium phosphate;

[0091] Step S8: Add the obtained precipitate to sodium hydroxide solution, separate iron and aluminum by filtration to obtain iron hydroxide and sodium aluminate solution, adjust the pH of sodium aluminate solution to 5 and filter to obtain aluminum oxide;

[0092] Preferably, clay-type lithium ore and sodium hydroxide additive are uniformly mixed at a mass ratio of 10:4-7 and then roasted at 800°C for 2 hours to obtain roasted clinker.

[0093] Preferably, the obtained roasted clinker is mixed with a 1.5 mol / L sulfuric acid solution at a stirring speed of 600 rpm to complete the leaching, and the solid and liquid are separated to obtain leachate and leaching residue;

[0094] Preferably, the leachate is evaporated to form a gel, then the gel is dried at 95 °C, and then calcined at 800 °C for 2 h to obtain a lithium-containing solid;

[0095] Preferably, the obtained mullite is mixed with an acid of 0.3 mol / L concentration and acid washed to obtain purified mullite;

[0096] Preferably, the obtained lithium-containing solution is mixed with a 10 wt.% sodium hydroxide solution;

[0097] Preferably, the lithium-containing solution is evaporated and concentrated to a lithium concentration of 3 mol / L, the pH is adjusted to 10 with 1 mol / L sodium hydroxide, and then the pH is adjusted to 12 with 1 mol / L sodium phosphate to form lithium phosphate.

[0098] Before adding sodium phosphate, purge the solution with nitrogen gas for 10-20 minutes to expel the air dissolved in the solution;

[0099] Preferably, the obtained precipitate is added to a 10 wt.% sodium hydroxide solution, and the iron and aluminum are separated by filtration to obtain iron hydroxide and sodium aluminate solution. The pH of the sodium aluminate solution is adjusted to 5 and then filtered to obtain alumina.

[0100] In this embodiment, lithium in clay-type lithium ore often exists in the form of aluminosilicate structure, which is chemically stable and has extremely low efficiency when directly acid leached. Alkaline roasting can destroy the aluminosilicate lattice at high temperature, converting the lithium in the structure into soluble lithium salt. Furthermore, this process not only recovers lithium, but also plans the recovery and purification pathways for by-products such as corundum, mullite, alumina, and iron hydroxide. This is of great significance for reducing the production cost of the main product, lithium phosphate, improving the economics of the entire process, and reducing the amount of solid waste from mines. The high-purity lithium phosphate prepared is an ideal precursor for synthesizing lithium iron phosphate cathode materials. It can be prepared into high-performance LFP materials simply by undergoing solid-phase sintering or liquid-phase reaction with iron and carbon sources.

[0101] Please refer to the reference again. Figures 1 to 12 The working principle of the equipment and process for recovering lithium battery cathode materials by alkaline roasting of low-grade clay lithium ore provided by the present invention is as follows:

[0102] Step S1: The lithium-containing solution is evaporated and concentrated to a suitable concentration, the pH is adjusted to 10 with sodium hydroxide, and then it is transported to the reaction vessel 1. The drive motor 93 is started. The drive motor 93 rotates and drives the rotating shaft 21 to rotate. The rotating shaft 21 rotates and drives the drive disk 22 to rotate. The rotation of the drive disk 22 drives the two rotating wheels 24 to rotate through the slider 23. The two rotating wheels 24 intermittently squeeze and release the drug inlet hose 26. The sodium phosphate precipitant is extracted by negative pressure and introduced into the solution from multiple directions through the annular pipe 5 and the nozzle 6.

[0103] The rotation of the rotating shaft 21 will simultaneously drive the stirring paddle 91 and the mixing paddle 92 to rotate, thereby mixing the solution with the sodium phosphate precipitant;

[0104] In step S2, when the drive disk 22 rotates, it will simultaneously drive the four screws 32 to rotate. The four screws 32 will then drive the four drive plates 31 to rotate. When the four drive plates 31 rotate, they will press the guide frame 34 downward through the contact wheel 35 and cause the spring 36 to contract. The guide frame 34 moves downward and drives the piston 38 to slide downward in the gas outlet cylinder 37, thereby delivering the inert gas to the liquid surface through the gas outlet pipe.

[0105] In step S3, when the drive disk 22 rotates, it will simultaneously drive the tooth assembly 88 to rotate. The rotation of the tooth assembly 88 will then drive the drive gear 86 to rotate. The rotation of the drive gear 86 will drive the driven gear 87 to rotate via the rotating shaft 85. The rotation of the driven gear 87 will drive the inner tooth disk 83 and the rotating rail 82 to rotate. The rotation of the rotating rail 82 will then drive multiple scrapers 84 to rotate. The rotation of the scrapers 84 will scrape off the fine lithium phosphate crystals on the inner wall of the reactor 1.

[0106] Step S4: When the lithium-containing solution transitions from the reaction stage to the aging stage, the addition of sodium phosphate to the solution is stopped, and the two electric telescopic rods 71 ​​are activated to retract. The retraction of the two electric telescopic rods 71 ​​then drives the two sliders 23 to move to the opposite side through the two connecting brackets 72. The movement of the two sliders 23 drives the two rotating wheels 24 to move to the opposite side, canceling the contact with the drug inlet hose 26. When the two connecting brackets 72 move to the opposite side, they will simultaneously drive the two baffles 73 to move to the opposite side. When the dispensing tube 75 and the storage cylinder 74 are connected, lithium phosphate seed crystals are dispensed into the solution.

[0107] In step S5, when the two sliders 23 move to the opposite side, they will simultaneously drive the two drive plates 31 at the bottom to move to the opposite side, thereby causing the rotation trajectory of the two drive plates 31 to disengage from the contact wheels 35. When the drive disc 22 rotates, the two drive plates 31 intermittently squeeze the four contact wheels 35, thereby intermittently introducing nitrogen gas into the reactor 1 for protection during the aging stage.

[0108] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An apparatus for recovering lithium cathode material for batteries from low-grade clay lithium ores by alkaline roasting, characterized in that, Including reaction kettle, medicament adding mechanism and inert gas protection mechanism; The medicament adding mechanism comprises a rotating shaft vertically connected to the inside of the reaction kettle, the surface of the rotating shaft is fixedly provided with a driving disc, the inside of the driving disc is slidably connected with two sliding blocks, the top of each of the two sliding blocks is rotatably connected with a rotating wheel, the top of the driving disc is provided with a chuck, the inner side of the chuck is provided with a medicament feeding hose, the two rotating wheels are located on the inner side of the driving disc and are attached to the medicament feeding hose, the circumferential side of the chuck is annularly provided with four connecting plates, and the four connecting plates are fixedly connected with the inner wall of the reaction kettle. The inert gas protection mechanism comprises four driving plates arranged at the bottom of the driving disc, the top of each of the four driving plates is fixedly provided with a screw rod, the four screw rods are divided into two groups, the two groups of screw rods are respectively threadedly connected with the two sliding blocks and the driving disc, the inner wall of the reaction kettle and located at the bottom of the driving disc is fixedly provided with a mounting disc, the inside of the mounting disc is vertically slidably connected with four guide frames, the inner side of the top of each of the four guide frames is rotatably connected with a contact wheel, the surface of each of the four guide frames and located at the top of the mounting disc is sleeved with a spring, the bottom of the mounting disc is fixedly provided with four air outlet cylinders, the inside of each of the four air outlet cylinders is slidably connected with a piston, and the bottom of each of the four guide frames is fixedly connected with the top of each of the four pistons.

2. The apparatus for recovering lithium cathode material for batteries from an alkaline-roasted low-grade clay lithium ore according to claim 1, characterized in that, The bottom of the mounting disc is annularly provided with four connecting seats, the inner side of each of the four connecting seats is provided with an annular tube, the bottom of the annular tube is annularly provided with four spray heads, and the medicament feeding hose is in communication with the annular tube.

3. The apparatus for recovering lithium cathode material for batteries from an alkaline-roasted low-grade clay lithium ore according to claim 1, characterized in that, The bottom of each of the four air outlet cylinders is communicated with an air outlet pipe, the bottom end of the air outlet pipe extends into the liquid, one side of each of the four air outlet cylinders is communicated with an air inlet pipe, and the surface of each of the air outlet pipe and the air inlet pipe is provided with a valve.

4. The apparatus for recovering lithium cathode material for batteries from an alkaline-roasted low-grade clay lithium ore according to claim 1, characterized in that, The bottom of the driving disc is fixedly provided with a switching and discharging mechanism, the switching and discharging mechanism comprises two electric telescopic rods fixedly arranged at the bottom of the driving disc, the output end of each of the two electric telescopic rods is fixedly provided with a connecting bracket, the bottom of each of the two connecting brackets is fixedly connected with the two sliding blocks, the bottom of each of the two connecting brackets is fixedly provided with a baffle, the inner side of the driving disc is fixedly provided with two storage cylinders, the bottom of each of the two storage cylinders is in contact with the top of each of the two baffles, and the bottom of each of the two baffles is communicated with a feeding pipe.

5. The apparatus for recovering lithium cathode material for batteries from an alkali-roasted low-grade clay lithium ore according to claim 1, characterized in that, The inner wall of the reaction kettle and located at the bottom of the mounting disc is fixedly provided with a wall scraping mechanism, the wall scraping mechanism comprises a guide ring fixedly arranged on the inner wall of the reaction kettle, the surface of the guide ring is rotatably connected with a rotating rail, the inner side of the rotating rail is fixedly provided with an internal tooth disc, the bottom of the rotating rail is annularly provided with a plurality of scrapers, the inside of the mounting disc is vertically rotatably connected with a rotating shaft, the top end of the rotating shaft is fixedly provided with a driving gear, the bottom end of the rotating shaft is fixedly provided with a driven gear, the driven gear is engaged with the internal tooth disc, the circumferential side of the driving disc is fixedly provided with a gear set, and the gear set is engaged with the driving gear.

6. The apparatus for recovering lithium cathode material for batteries from an alkaline-roasted low-grade clay lithium ore according to claim 1, characterized in that, The surface of the rotating shaft is fixedly provided with a mixing mechanism, the mixing mechanism comprises three stirring paddles fixedly arranged on the surface of the rotating shaft, the bottom end of the rotating shaft is fixedly provided with a mixing paddle, and the top of the reaction kettle is provided with a driving motor for driving the rotating shaft to rotate.

7. The apparatus for recovering lithium cathode material for batteries from an alkali-roasted low-grade clay lithium ore according to claim 1, characterized in that, The left side of the reaction kettle is communicated with a feeding pipe, the bottom of the reaction kettle is communicated with a discharge pipe, and the top of the reaction kettle is communicated with an exhaust pipe.

8. The apparatus for recovering lithium cathode material for batteries from an alkali-roasted low-grade clay lithium ore according to claim 1, characterized in that, The outer side of the reaction kettle is provided with a support frame, the inner side of the support frame is fixedly provided with four connecting frames, the opposite sides of the four connecting frames are fixedly connected with the peripheral side of the reaction kettle, and the bottom of the support frame is provided with supporting feet.

9. Process for the recovery of lithium cathode materials for batteries from alkaline roasting of low-grade clay lithium ores, characterized by, The process for recycling lithium battery positive electrode material comprises the equipment according to any one of claims 1-8 and the following steps: Step S1, uniformly mixing clay-type lithium ore and sodium hydroxide additive, roasting at 800 DEG C for 2h to obtain roasted clinker; Step S2, mixing the obtained roasted clinker with sulfuric acid solution at a stirring speed of 600 rpm to complete leaching, and then solid-liquid separation to obtain leaching solution and leaching residue; Step S3, drying the obtained leaching residue at 100 DEG C, and then screening under a 100-mesh sieve to obtain corundum and solid waste; Step S4, evaporating the leaching solution to form a gel, then drying the gel at 95 DEG C, and then roasting to obtain lithium-containing solid, washing the solid with water to obtain mullite and lithium-containing solution; Step S5, mixing the obtained mullite with acid for acid washing to obtain purified mullite; Step S6, mixing the obtained lithium-containing solution with sodium hydroxide solution, adjusting the pH to 6.5 to remove iron and aluminum, and filtering to obtain impurity-removed lithium solution and precipitate; Step S7, evaporating and concentrating the impurity-removed lithium-containing solution to a suitable concentration, adjusting the pH to 10 with sodium hydroxide, and then conveying to a reaction kettle, adjusting the pH to 12 with sodium phosphate to form lithium phosphate; Step S8, adding the obtained precipitate to sodium hydroxide solution, separating iron and aluminum to obtain iron hydroxide and sodium aluminate solution, adjusting the pH of the sodium aluminate solution to 5 to obtain aluminum oxide by filtration. Step S1, uniformly mixing clay-type lithium ore and sodium hydroxide additive, roasting at 800 DEG C for 2h to obtain roasted clinker; Step S2, mixing the obtained roasted clinker with sulfuric acid solution at a stirring speed of 600 rpm to complete leaching, and then solid-liquid separation to obtain leaching solution and leaching residue; Step S3, drying the obtained leaching residue at 100 DEG C, and then screening under a 100-mesh sieve to obtain corundum and solid waste; Step S4, evaporating the leaching solution to form a gel, then drying the gel at 95 DEG C, and then roasting to obtain lithium-containing solid, washing the solid with water to obtain mullite and lithium-containing solution; Step S5, mixing the obtained mullite with acid for acid washing to obtain purified mullite; Step S6, mixing the obtained lithium-containing solution with sodium hydroxide solution, adjusting the pH to 6.5 to remove iron and aluminum, and filtering to obtain impurity-removed lithium solution and precipitate; Step S7, evaporating and concentrating the impurity-removed lithium-containing solution to a suitable concentration, adjusting the pH to 10 with sodium hydroxide, and then conveying to a reaction kettle, adjusting the pH to 12 with sodium phosphate to form lithium phosphate; Step S8, adding the obtained precipitate to sodium hydroxide solution, separating iron and aluminum to obtain iron hydroxide and sodium aluminate solution, adjusting the pH of the sodium aluminate solution to 5 to obtain aluminum oxide by filtration.

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