Lithium carbonate washing device and recycling method for preparing battery-grade lithium carbonate from lithium carbonate washing mother liquor

Abstract

The application provides a lithium carbonate washing device and a recycling method for preparing battery-grade lithium carbonate from a lithium carbonate washing mother liquor, relates to the technical field of battery-grade lithium carbonate preparation, and comprises a stirring washing tank, a sealing cover, a driving mechanism and a lifting and rotating washing mechanism. A mounting shell is fixedly arranged on the top of the sealing cover. The driving mechanism comprises a protection frame fixedly arranged on the top of the mounting shell. A driving motor is fixedly arranged on the rear side of the bottom of the protection frame. A rotating rod is rotatably connected to the top of the inner wall of the protection frame. Through the cooperation of the convex blocks and the annular track, when the driving rod drives the rotating sleeve to rotate, the rotating stirring of the stirring paddle and the reciprocating lifting can be simultaneously realized. The reciprocating lifting of the stirring paddle can completely eliminate the washing dead angle in the stirring washing tank, scatter the compacted lithium mud, strengthen the mass transfer contact between the high-temperature washing water and the lithium carbonate crystals, deeply remove the sodium, boron and sulfate impurities adsorbed on the surface of the particles, and significantly improve the purification effect of the battery-grade lithium carbonate.

Description

Technical Field

[0001] This invention relates to the field of battery-grade lithium carbonate preparation, and more particularly to lithium carbonate washing equipment and a recycling method for preparing battery-grade lithium carbonate from lithium precipitation mother liquor. Background Technology

[0002] With the rapid development of the new energy lithium battery industry, battery-grade lithium carbonate, as a core raw material for the preparation of cathode materials for lithium-ion batteries, directly determines the electrochemical performance, cycle life, and safety stability of lithium batteries through its purity and impurity content. The industry's requirements for the purity standards and quality uniformity of battery-grade lithium carbonate are becoming increasingly stringent. During the precipitation process of lithium carbonate, the crystal surface, micropores, and interparticle gaps strongly adsorb and entrain residual sodium, potassium, calcium, and other metallic impurities, as well as sulfate-soluble salt impurities, from the mother liquor. These impurities cannot be completely removed through precipitation and filtration processes. If washing is insufficient, these impurities will remain in the finished lithium carbonate product, directly reducing the product's purity and failing to meet the stringent industry standards for battery-grade lithium carbonate.

[0003] In related technologies, after lithium carbonate production, it needs to be washed to remove surface impurities in order to meet battery-grade requirements. However, some existing washing equipment, such as the washing device for high-purity lithium carbonate preparation disclosed in application number CN202411798496.1, relies on crushing lithium carbonate polymer to improve washing mass transfer. However, a large amount of fine lithium powder is generated during the crushing process. The fine powder is very easy to float and accumulate on the liquid surface, forming stubborn foam that is difficult to dissolve. This not only causes lithium resource loss but also easily leads to overflow. It is not convenient to improve washing mass transfer efficiency while avoiding the generation of fine powder and adaptive defoaming.

[0004] Therefore, it is necessary to provide lithium carbonate washing equipment and a recycling method for preparing battery-grade lithium carbonate from lithium precipitation mother liquor to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a lithium carbonate washing device and a recycling method for preparing battery-grade lithium carbonate from lithium precipitation mother liquor, which solves the problem that some washing devices are not convenient to avoid the generation of micro powder and adaptive defoaming while improving washing mass transfer efficiency.

[0006] To solve the above-mentioned technical problems, the lithium carbonate washing equipment and the recycling method for preparing battery-grade lithium carbonate from lithium precipitation mother liquor provided by the present invention include a washing tank, a sealing cover, a driving mechanism and a lifting and rotating washing mechanism.

[0007] The top of the sealing cover is fixedly provided with a mounting shell. The driving mechanism includes a protective frame fixedly provided on the top of the mounting shell. A drive motor is fixedly provided on the rear side of the bottom of the protective frame. A rotating rod is rotatably connected to the top of the inner wall of the protective frame. Pulleys are fixedly provided on the output shaft of the drive motor and the peripheral side of the rotating rod. A belt is sleeved on the peripheral side of the two pulleys. Two support frames are fixedly provided at the bottom of the protective frame. The bottom of the two support frames is fixedly connected to the top of the sealing cover.

[0008] The lifting and rotating washing mechanism includes an installation sleeve fixed inside the sealing cover. A rotating sleeve is provided inside the sleeve, and a drive rod is slidably connected inside the rotating sleeve. The bottom end of the rotating rod passes through the top of the installation shell and extends into the interior of the installation shell. The bottom end of the rotating rod is fixedly connected to the top of the drive rod. A protrusion is fixedly provided on the right side of the rotating sleeve. An annular track that cooperates with the protrusion is opened inside the installation sleeve. An agitator rod is fixedly provided at the bottom of the rotating sleeve, and an agitator paddle is fixedly provided on the circumferential side of the agitator rod.

[0009] Preferably, the mounting sleeve is located inside the mounting shell. When the drive rod rotates, it will drive the rotating sleeve to rotate. When the rotating sleeve rotates, the protrusion will move along the annular track inside the mounting sleeve, so that the rotating sleeve moves up and down along the drive rod at the same time as it rotates.

[0010] Preferably, a mounting ring is fixed to the circumferential side of the stirring rod, and three oblique-blade centrifugal defoaming composite paddles are arranged in a ring array on the circumferential side of the mounting ring, with an elongated guide notch in the upper half of the oblique-blade centrifugal defoaming composite paddle.

[0011] Preferably, the stirring rod is fitted with an intermittent dispensing mechanism on its circumferential side. The intermittent dispensing mechanism includes a rotating seat fitted on the circumferential side of the stirring rod. A drive ring is fixedly provided on the circumferential side of the stirring rod and at the bottom of the rotating seat. A first connecting rod is rotatably connected to the top left side of the rotating seat. A sliding frame is fixedly provided on the bottom left side of the sealing cover. A sealing plate is slidably connected inside the sliding frame. The top of the first connecting rod is rotatably connected to the bottom of the sealing plate. Two springs are provided on the side of the sealing plate opposite to the sliding frame.

[0012] Preferably, a feeding tube is fixed inside the sealing cover and located at the top of the sealing plate, the bottom of the feeding tube is in contact with the top of the sealing plate, and a feeding hole for use with the feeding tube is opened inside the sealing plate.

[0013] Preferably, a transmission mechanism is rotatably connected to the right side of the top of the rotating seat. The transmission mechanism includes a second connecting rod rotatably connected to the right side of the top of the rotating seat. A mounting bracket is fixedly provided on the right side of the bottom of the sealing cover. A moving rod is slidably connected to the inside of the mounting bracket. A return spring is sleeved on the circumferential side of the moving rod and located on the left side of the mounting bracket. The top of the second connecting rod is rotatably connected to the left end of the moving rod. A transmission gear plate is fixedly provided on the right end of the moving rod. Teeth are provided on both sides of the transmission gear plate.

[0014] Preferably, an exhaust mechanism is fixedly provided on the right side of the bottom of the sealing cover. The exhaust mechanism includes a slide rail fixedly provided on the right side of the bottom of the sealing cover. A first adjusting plate is slidably connected to the surface of the slide rail. A first toothed set is fixedly provided on the left side of the first adjusting plate. A first transmission gear is rotatably connected to the bottom of the sealing cover via a rotating shaft. The first transmission gear meshes with the first toothed set. A first drive gear is fixedly provided at the bottom of the first transmission gear via a rotating shaft. The first drive gear meshes with the rear side of the transmission toothed plate. An exhaust pipe is provided inside the sealing cover and at the top of the first adjusting plate.

[0015] Preferably, a nitrogen replacement mechanism is slidably connected to the surface of the slide rail. The nitrogen replacement mechanism includes a second adjusting plate slidably connected to the surface of the slide rail. A second toothed set is fixedly provided on the left side of the second adjusting plate. A second transmission gear is rotatably connected to the bottom of the sealing cover via a rotating shaft. The second transmission gear meshes with the second toothed set. A second drive gear is fixedly provided at the bottom of the second transmission gear via a rotating shaft. The second drive gear meshes with the front side of the transmission toothed plate. An air inlet pipe is provided inside the sealing cover and at the top of the second adjusting plate.

[0016] Preferably, a mounting bracket is fixedly provided on the periphery of the agitation tank, an inlet pipe is connected to the right side of the agitation tank, and a drain pipe is connected to the bottom of the agitation tank.

[0017] A recycling method for preparing battery-grade lithium carbonate from lithium precipitation mother liquor includes the following steps:

[0018] Step S1: Mix lithium precipitation mother liquor with sulfuric acid, adjust pH to neutral, remove carbonate ions to obtain decarbonated liquor, preheat the decarbonated liquor and evaporate and concentrate it, cool and crystallize to precipitate sodium sulfate crystals, separate solid and liquid to obtain crude sodium sulfate and lithium-containing filtrate, and dehydrate and dry the crude sodium sulfate to obtain industrial grade sodium sulfate product.

[0019] Step S2: Add TDPA:TOPO low melting point eutectic extractant to the lithium-containing filtrate to selectively precipitate lithium, and separate the solid and liquid to obtain TDPA:TOPO-Li precipitate and filtrate containing sodium and potassium;

[0020] Step S3: After washing the obtained TDPA:TOPO-Li precipitate with deionized water, add sulfuric acid and heat for back-extraction to obtain the back-extraction solution and the regenerated TDPA:TOPO eutectic agent, the latter of which is returned to step S2 for recycling;

[0021] Step S4: Adjust the pH of the obtained back-extraction solution to 11–12, remove calcium through resin, add sodium carbonate to precipitate lithium carbonate, and after solid-liquid separation, washing, and drying, obtain battery-grade lithium carbonate product. Battery-grade lithium carbonate is used to prepare lithium-ion battery cathode materials.

[0022] Step S5: Mix the sodium and potassium filtrate with calcium sulfate and react at low temperature to generate potassium gypsum. Separate the solid and liquid phases to obtain the sodium filtrate and potassium gypsum intermediate phase.

[0023] Step S6: Mix potassium gypsum with water, heat to decompose, and separate the solid and liquid to obtain potassium sulfate solution and regenerated calcium sulfate solid. The potassium sulfate solution is evaporated and crystallized to obtain agricultural grade potassium sulfate product, and the regenerated calcium sulfate is returned to step S5 for recycling.

[0024] Step S7: Evaporate and crystallize the sodium-containing filtrate to obtain industrial-grade sodium sulfate product.

[0025] Compared with related technologies, the lithium carbonate washing equipment provided by the present invention has the following beneficial effects:

[0026] By using the combination of protrusions and annular tracks, when the drive rod drives the rotating sleeve to rotate, the stirring paddle can be rotated and reciprocated simultaneously. The reciprocating movement of the stirring paddle can completely eliminate the washing dead corners inside the washing tank, break up and compact the lithium sludge, enhance the mass transfer contact between the high-temperature washing water and the lithium carbonate crystals, and deeply remove sodium, boron, and sulfate impurities adsorbed on the particle surface, significantly improving the purification effect of battery-grade lithium carbonate. The coaxially matched inclined blade centrifugal defoaming composite paddle rises and falls synchronously with the stirring rod. When it is at a low position, the lower half is immersed in the liquid phase to stir the surface slurry and prevent lithium powder from floating and forming a skin. When the stirring rod is raised, the entire paddle enters the gas phase foam zone. Relying on the negative pressure suction of the guide gap and the double crushing of foam by centrifugal impact, it can continuously and stably defoam according to the height of the foam layer, effectively avoiding the loss of lithium resources caused by the overflow of fine lithium carbonate carried by foam. 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 structure of the agitation tank provided by the present invention, shown in the top view.

[0030] Figure 3 This is a structural schematic diagram of a cross-sectional view of the agitation tank provided by the present invention;

[0031] Figure 4 This is a structural schematic diagram of the cross-sectional view of the drive mechanism provided by the present invention;

[0032] Figure 5 This is a schematic diagram of the lifting and rotating washing mechanism provided by the present invention;

[0033] Figure 6 for Figure 5 A structural schematic diagram of the cross-sectional view of the sleeve and rotating sleeve shown;

[0034] Figure 7 A schematic diagram of the intermittent delivery mechanism, transmission mechanism, exhaust mechanism, and nitrogen replacement mechanism provided by the present invention;

[0035] Figure 8 A schematic diagram showing the state in which the stirring shaft drives the drive ring to move upward and pushes the rotating seat to move downward, as provided by the present invention.

[0036] Figure 9 for Figure 7 The diagram shows the structural schematics of the transmission mechanism, exhaust mechanism, and nitrogen replacement mechanism.

[0037] Figure 10 A schematic diagram showing the state in which the moving rod drives the transmission gear plate to move to the right, causing the first adjusting plate and the second adjusting plate to move to opposite sides;

[0038] Figure 11 This is a schematic diagram of the method flow provided by the present invention.

[0039] Explanation of icon numbers:

[0040] 1. Agitator; 2. Sealing cover;

[0041] 3. Drive mechanism; 31. Protective frame; 32. Drive motor; 33. Rotating rod; 34. Pulley; 35. Belt; 36. Support frame;

[0042] 4. Lifting and rotating washing mechanism; 41. Sleeve; 42. Rotating sleeve; 43. Drive rod; 44. Protrusion; 45. Agitator rod; 46. Agitator paddle;

[0043] 5. Mounting shell; 6. Mounting ring; 7. Inclined blade centrifugal defoaming composite impeller;

[0044] 8. Intermittent dispensing mechanism; 81. Rotating seat; 82. Drive ring; 83. First connecting rod; 84. Sliding frame; 85. Sealing plate; 86. Spring;

[0045] 9. Feeding pipe;

[0046] 10. Transmission mechanism; 101. Second connecting rod; 102. Mounting bracket; 103. Moving rod; 104. Return spring; 105. Transmission gear plate;

[0047] 11. Exhaust mechanism; 111. Slide rail; 112. First adjusting plate; 113. First gear set; 114. First transmission gear; 115. First drive gear;

[0048] 12. Exhaust pipe;

[0049] 13. Nitrogen purging mechanism; 131. Second adjusting plate; 132. Second gear set; 133. Second transmission gear; 134. Second drive gear;

[0050] 14. Air intake pipe;

[0051] 15. Mounting bracket; 16. Liquid inlet pipe; 17. Liquid outlet pipe. Detailed Implementation

[0052] 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.

[0053] This invention provides a lithium carbonate washing device.

[0054] First embodiment:

[0055] Please see Figures 1 to 6 The lithium carbonate washing equipment includes a washing tank 1, a sealing cover 2, a drive mechanism 3, and a lifting and rotating washing mechanism 4.

[0056] The top of the sealing cover 2 is fixedly provided with a mounting shell 5. The driving mechanism 3 includes a protective frame 31 fixedly provided on the top of the mounting shell 5. A drive motor 32 is fixedly provided on the rear side of the bottom of the protective frame 31. A rotating rod 33 is rotatably connected to the top of the inner wall of the protective frame 31. Pulleys 34 are fixedly provided on the output shaft of the drive motor 32 and the peripheral side of the rotating rod 33. A belt 35 is sleeved on the peripheral side of the two pulleys 34. Two support frames 36 are fixedly provided on the bottom of the protective frame 31. The bottom of the two support frames 36 is fixedly connected to the top of the sealing cover 2.

[0057] The lifting and rotating washing mechanism 4 includes an installation sleeve 41 fixed inside the sealing cover 2. A rotating sleeve 42 is provided inside the sleeve 41. A drive rod 43 is slidably connected inside the rotating sleeve 42. The bottom end of the rotating rod 43 passes through the top of the mounting shell 5 and extends into the interior of the mounting shell 5. The bottom end of the rotating rod 43 is fixedly connected to the top of the drive rod 43. A protrusion 44 is fixedly provided on the right side of the rotating sleeve 42. An annular track that cooperates with the protrusion 44 is opened inside the installation sleeve 41. An agitator 45 is fixedly provided at the bottom of the rotating sleeve 42. An agitator 46 is fixedly provided on the circumferential side of the agitator 45.

[0058] The mounting sleeve 41 is located inside the mounting shell 5. When the drive rod 43 rotates, it will drive the rotating sleeve 42 to rotate. When the rotating sleeve 42 rotates, the protrusion 44 will move along the annular track inside the mounting sleeve 41, so that the rotating sleeve 42 moves up and down along the drive rod 43 at the same time as it rotates.

[0059] The stirring rod 45 is fixedly provided with a mounting ring 6 on its circumferential side. The mounting ring 6 is provided with three oblique blade centrifugal defoaming composite paddles 7 arranged in a ring array on its circumferential side. The upper half of the oblique blade centrifugal defoaming composite paddle 7 is provided with a long strip guide notch.

[0060] Preferably, the initial working position of the inclined blade centrifugal defoaming composite propeller 7 is such that its lower half is located in the liquid, which is used to mix the gas and liquid at the interface;

[0061] Please combine Figure 4 and Figure 5 The drive motor 32 is started. The drive motor 32 rotates, which drives the rotating rod 33 to rotate via the belt 35 and pulley 34. The rotation of the rotating rod 33 drives the drive rod 43 to rotate, which in turn drives the rotating sleeve 42 and the stirring rod 45 to rotate. The rotation of the stirring rod 45 drives the stirring paddle 46 to rotate, thereby washing the lithium carbonate. During the rotation of the rotating sleeve 42, the protrusion 44 will rotate simultaneously. With the cooperation of the annular track, the protrusion 44 will drive the rotating sleeve 42 to move up and down. The up and down movement of the rotating sleeve 42 will drive the stirring rod 45 and the stirring paddle 46 to move up and down, thereby performing compound stirring of lithium carbonate and deionized water.

[0062] Furthermore, when the stirring rod 45 rotates, it simultaneously drives the mounting ring 6 and the inclined blade centrifugal defoaming composite paddle 7 to rotate, thereby promoting the circumferential circulation of the surface liquid, making the gas-liquid contact uniform and preventing lithium powder from floating and forming a skin. When the stirring rod 45 moves upward, it simultaneously drives the mounting ring 6 and the inclined blade centrifugal defoaming composite paddle 7 to move upward, so that the upper part of the inclined blade centrifugal defoaming composite paddle 7 is completely in the gas. Its rotation generates negative pressure to suck up the foam, and the centrifugal force stretches the bubble film, while simultaneously throwing it against the reactor wall to perform double defoaming.

[0063] In this embodiment, through the combined use of the protrusion 44 and the annular track, when the drive rod 43 drives the rotating sleeve 42 to rotate, the stirring paddle 46 can be rotated and reciprocated. The reciprocating motion of the stirring paddle 46 can completely eliminate the washing dead corners inside the washing tank 1, break up and compact the lithium sludge, enhance the mass transfer contact between the high-temperature washing water and the lithium carbonate crystals, deeply remove sodium, boron, and sulfate impurities adsorbed on the particle surface, and significantly improve the purification effect of battery-grade lithium carbonate. The coaxially matched inclined blade centrifugal defoaming composite paddle 7 rises and falls synchronously with the stirring rod 45. When it is at a low position, the lower half is immersed in the liquid phase to stir the surface slurry and prevent lithium powder from floating and forming a skin. When the stirring rod 45 is raised, the entire paddle enters the gas phase foam zone. Relying on the negative pressure suction of the guide gap and the double crushing of foam by centrifugal impact, it can continuously and stably defoam according to the height of the foam layer, effectively avoiding the overflow of fine lithium carbonate caused by foam.

[0064] Second embodiment:

[0065] Please see Figure 7 and Figure 8 An intermittent dispensing mechanism 8 is sleeved on the circumferential side of the stirring rod 45. The intermittent dispensing mechanism 8 includes a rotating seat 81 sleeved on the circumferential side of the stirring rod 45. A drive ring 82 is fixedly provided on the circumferential side of the stirring rod 45 and at the bottom of the rotating seat 81. A first connecting rod 83 is rotatably connected to the top left side of the rotating seat 81. A sliding frame 84 is fixedly provided on the bottom left side of the sealing cover 2. A sealing plate 85 is slidably connected inside the sliding frame 84. The top of the first connecting rod 83 is rotatably connected to the bottom of the sealing plate 85. Two springs 86 are provided on the side of the sealing plate 85 opposite to the sliding frame 84.

[0066] A feeding tube 9 is fixed inside the sealing cover 2 and located on top of the sealing plate 85. The bottom of the feeding tube 9 is in contact with the top of the sealing plate 85. A feeding hole for use with the feeding tube 9 is opened inside the sealing plate 85.

[0067] Preferably, the feeding pipe 9 is used for intermittent feeding of lithium carbonate material;

[0068] Please combine Figure 7 and Figure 8 When the stirring rod 45 moves upward during rotation, it will simultaneously drive the drive ring 82 to move upward. After the drive ring 82 moves upward and contacts the bottom of the rotating seat 81 and continues to move upward, it will push the rotating seat 81 to move upward. The upward movement of the rotating seat 81 will drive the sealing plate 85 to move to the left through the first connecting rod 83. The leftward movement of the sealing plate 85 will compress the spring 86, causing the spring 86 to contract. When the sealing plate 85 moves to the left a certain position, the feeding hole will coincide with the feeding pipe 9. At this time, the lithium carbonate material will simultaneously enter the washing tank 1 through the feeding hole.

[0069] Preferably, lithium carbonate material is added only when the stirring rod 45 and the stirring paddle 46 are in the lifting state and the slurry in the tank is in a strong disturbance cycle. The newly added lithium carbonate material is in the turbulent zone formed by the strong disturbance cycle. With the help of the shear force generated by the rotation of the stirring paddle 46 and the axial circulation flow, the fresh material can be quickly dispersed and fully contacted with the washing water, avoiding the problem of incomplete washing caused by the material accumulating into clumps or uneven local concentration.

[0070] Furthermore, when the stirring rod 45 moves downward during rotation, under the elastic force of the spring 86, the sealing plate 85 will slide to the right inside the sliding frame 84, thereby resealing the feeding pipe 9 and stopping the feeding. During the sliding of the sealing plate 85 to the right, the first connecting rod 83 will cause the rotating seat 81 to reset downward. Through the continuous rotation of the stirring rod 45, lithium carbonate material can be fed intermittently.

[0071] In this embodiment, the combined rotational and lifting motion of the stirring rod 45 is used as a power source to drive the sealing plate 85 to slide back and forth within the sliding frame 84, so that the feeding hole and the feeding pipe 9 intermittently overlap and connect, realizing the quantitative and periodic feeding of lithium carbonate material. Moreover, the feeding action is precisely synchronized with the lifting and lowering rhythm of the stirring rod 45. The turbulence effect formed by the disturbance cycle can improve the washing mass transfer efficiency. At the same time, because the feeding action is highly compatible with the stirring and lifting sequence, the feeding is completed only under the condition of stirring and lifting to defoam. This can effectively avoid the material floating, large-area foaming and overflow phenomena caused by concentrated feeding, greatly reduce the loss of fine lithium carbonate powder with foam, and significantly improve the comprehensive recovery rate of lithium resources.

[0072] Third embodiment:

[0073] Please see Figure 1 , Figure 3 , Figure 7 , Figure 9 and Figure 10 A transmission mechanism 10 is rotatably connected to the right side of the top of the rotating seat 81. The transmission mechanism 10 includes a second connecting rod 101 rotatably connected to the right side of the top of the rotating seat 81. A mounting bracket 102 is fixedly provided on the right side of the bottom of the sealing cover 2. A moving rod 103 is slidably connected laterally inside the mounting bracket 102. A return spring 104 is sleeved on the circumferential side of the moving rod 103 and located on the left side of the mounting bracket 102. The top of the second connecting rod 101 is rotatably connected to the left end of the moving rod 103. A transmission gear plate 105 is fixedly provided on the right end of the moving rod 103. Teeth are provided on both sides of the transmission gear plate 105.

[0074] An exhaust mechanism 11 is fixedly provided on the right side of the bottom of the sealing cover 2. The exhaust mechanism 11 includes a slide rail 111 fixedly provided on the right side of the bottom of the sealing cover 2. A first adjusting plate 112 is slidably connected to the surface of the slide rail 111. A first toothed gear 113 is fixedly provided on the left side of the first adjusting plate 112. A first transmission gear 114 is rotatably connected to the bottom of the sealing cover 2 through a rotating shaft. The first transmission gear 114 meshes with the first toothed gear 113. A first drive gear 115 is fixedly provided at the bottom of the first transmission gear 114 through a rotating shaft. The first drive gear 115 meshes with the rear side of the transmission gear plate 105. An exhaust pipe 12 is provided inside the sealing cover 2 and at the top of the first adjusting plate 112.

[0075] A nitrogen replacement mechanism 13 is slidably connected to the surface of the slide rail 111. The nitrogen replacement mechanism 13 includes a second adjusting plate 131 slidably connected to the surface of the slide rail 111. A second tooth set 132 is fixedly provided on the left side of the second adjusting plate 131. A second transmission gear 133 is rotatably connected to the bottom of the sealing cover 2 through a rotating shaft. The second transmission gear 133 meshes with the second tooth set 132. A second drive gear 134 is fixedly provided at the bottom of the second transmission gear 133 through a rotating shaft. The second drive gear 134 meshes with the front side of the transmission tooth plate 105. An air inlet pipe 14 is provided inside the sealing cover 2 and at the top of the second adjusting plate 131.

[0076] A mounting bracket 15 is fixedly provided on the periphery of the agitation tank 1, an inlet pipe 16 is connected to the right side of the agitation tank 1, and a drain pipe 17 is connected to the bottom of the agitation tank 1.

[0077] Preferably, the first adjusting plate 112 has a through groove inside that works with the exhaust pipe 12. In the initial position, the bottom of the exhaust pipe 12 is in contact with the rear side of the top of the first adjusting plate 112. When the first adjusting plate 112 moves backward a certain position, the exhaust pipe 12 will be in a communication state with the first adjusting plate 112, thereby exhausting the groove.

[0078] Preferably, the second adjusting plate 131 has a through groove inside that works with the air inlet pipe 14. At the initial position, the bottom of the air inlet pipe 14 is in contact with the front side of the top of the second adjusting plate 131. When the second adjusting plate 131 moves backward a certain position, the air inlet pipe 14 will be in a communication state with the second adjusting plate 131, thereby introducing nitrogen into the groove.

[0079] Preferably, the slots in the first adjusting plate 112 and the second adjusting plate 131 are opened at different positions and are of different sizes. When the first adjusting plate 112 and the second adjusting plate 131 move to the opposite side, the exhaust pipe 12 will be in a connected state first, and the intake pipe 14 will be in a sealed state. When the movement continues, the intake pipe 14 will be in a connected state, and the exhaust pipe 12 will be in a sealed state.

[0080] Furthermore, when the first adjusting plate 112 and the second adjusting plate 131 move to the opposite side, the intake pipe 14 will go from the connected state to the sealed state, and the exhaust pipe 12 will go from the sealed state to the connected state, and then go back to the sealed state.

[0081] Preferably, when nitrogen is introduced, hydrogen is continuously introduced to cause the pressure inside the vessel to accumulate continuously. Subsequently, when the stirring paddle 46 moves downward to stir the slurry, the high-pressure gas is prone to break through the liquid surface and generate a large amount of secondary foam. The foam will carry lithium powder out, increasing the defoaming burden and lithium loss. This problem can be effectively solved by opening the exhaust pipe 12 a second time.

[0082] Furthermore, by controlling the opening position of the feeding hole inside the sealing plate 85, lithium carbonate material can be simultaneously fed in the state of nitrogen introduction.

[0083] Please combine Figure 9 and Figure 10 When the stirring rod 45 moves upward during rotation and the rotating seat 81 moves upward synchronously, the moving rod 103 will move to the right under the action of the second connecting rod 101, and the return spring 104 will contract. The movement of the moving rod 103 to the right will simultaneously drive the transmission gear plate 105 to move to the right. The movement of the transmission gear plate 105 to the right will then drive the first drive gear 115 to rotate counterclockwise. The counterclockwise rotation of the first drive gear 115 will drive the first transmission gear 114 to rotate counterclockwise. The counterclockwise rotation of the first transmission gear 114 will drive the first tooth set 113 and the first adjusting plate 112 to move backward. During this process, the first adjusting plate 112 will be connected to the exhaust pipe 12 to exhaust gas.

[0084] Furthermore, when the transmission gear plate 105 moves to the right, it simultaneously drives the second drive gear 134 to rotate clockwise. The clockwise rotation of the second drive gear 134 drives the second transmission gear 133 to rotate clockwise via the rotating shaft. The clockwise rotation of the second transmission gear 133 drives the second tooth set 132 to move forward. The forward movement of the second tooth set 132 drives the second adjusting plate 131 to move forward. During this process, the air intake pipe 14 and the second adjusting plate 131 are connected, and nitrogen gas is discharged into the tank.

[0085] Furthermore, when the stirring rod 45 moves downward during rotation, under the action of the reset spring 104, the moving rod 103 will drive the transmission gear plate 105 to move to the left. The leftward movement of the transmission gear plate 105 will drive the first drive gear 115 to rotate clockwise and the second drive gear 134 to rotate counterclockwise, thereby resetting the first adjusting plate 112 and the second adjusting plate 131.

[0086] In this embodiment, the lifting displacement of the rotating seat 81 is converted into the lateral reciprocating motion of the transmission gear plate 105. The teeth on both sides of the transmission gear plate 105 mesh with the first drive gear 115 and the second drive gear 134 respectively, enabling the single lifting action to synchronously drive the exhaust mechanism 11 and the nitrogen replacement mechanism 13 to alternately open and close. When the stirring rod 45 rises to the feeding position, the transmission gear plate 105 moves to the right, triggering the first adjusting plate 112 to move backward and open the exhaust pipe 12, thus timely discharging the high-temperature water vapor and volatile impurities in the washing tank 1 and preventing pressure buildup in the tank. The cumulative effect on feeding smoothness is then addressed by opening the air inlet pipe 14 during the forward movement of the second regulating plate 131 to continuously introduce nitrogen into the tank, forming an inert atmosphere protective layer from top to bottom. This effectively isolates the intrusion of external air and prevents the lithium carbonate slurry from reacting with carbon dioxide in a high-temperature alkaline environment to form carbonate scale, thus ensuring product purity. The differentiated design of the opening position and size of the through slots inside the first regulating plate 112 and the second regulating plate 131 allows the exhaust pipe 12 and the air inlet pipe 14 to alternately open and close during the same lifting stroke, achieving the effect of first discharging and then filling.

[0087] In addition, by coordinating the opening position of the feeding hole in the sealing plate 85 with the timing of nitrogen introduction, the lithium carbonate material is accurately fed under the protection of continuous nitrogen purging, further isolating the material from contact with the residual hot and humid airflow in the tank during the falling process, and preventing the lithium powder from absorbing moisture and agglomerating.

[0088] In another application, the lithium carbonate washing equipment can also be used in the fine chemical industry for the surface modification of functional powder materials, such as inorganic powder materials like silicon micro powder, titanium dioxide, alumina, and silicon carbide. The lifting and stirring mechanism eliminates sedimentation dead zones, ensuring that the coating agent evenly coats each particle, while nitrogen protection prevents the powder from oxidizing and discoloring during the high-temperature modification process.

[0089] This invention also provides a recycling method for preparing battery-grade lithium carbonate from lithium precipitation mother liquor.

[0090] Please see Figure 11 A recycling method for preparing battery-grade lithium carbonate from lithium precipitation mother liquor includes the following steps:

[0091] Step S1: Mix lithium precipitation mother liquor with sulfuric acid, adjust pH to neutral, remove carbonate ions to obtain decarbonated liquor, preheat the decarbonated liquor and evaporate and concentrate it, cool and crystallize to precipitate sodium sulfate crystals, separate solid and liquid to obtain crude sodium sulfate and lithium-containing filtrate, and dehydrate and dry the crude sodium sulfate to obtain industrial grade sodium sulfate product.

[0092] Step S2: Add TDPA:TOPO low melting point eutectic extractant to the lithium-containing filtrate to selectively precipitate lithium, and separate the solid and liquid to obtain TDPA:TOPO-Li precipitate and filtrate containing sodium and potassium;

[0093] Step S3: After washing the obtained TDPA:TOPO-Li precipitate with deionized water, add sulfuric acid and heat for back-extraction to obtain the back-extraction solution and the regenerated TDPA:TOPO eutectic agent, the latter of which is returned to step S2 for recycling;

[0094] Step S4: Adjust the pH of the obtained back-extraction solution to 11–12, remove calcium through resin, add sodium carbonate to precipitate lithium carbonate, and after solid-liquid separation, washing, and drying, obtain battery-grade lithium carbonate product. Battery-grade lithium carbonate is used to prepare lithium-ion battery cathode materials.

[0095] Step S5: Mix the sodium and potassium filtrate with calcium sulfate and react at low temperature to generate potassium gypsum. Separate the solid and liquid phases to obtain the sodium filtrate and potassium gypsum intermediate phase.

[0096] Step S6: Mix potassium gypsum with water, heat to decompose, and separate the solid and liquid to obtain potassium sulfate solution and regenerated calcium sulfate solid. The potassium sulfate solution is evaporated and crystallized to obtain agricultural grade potassium sulfate product, and the regenerated calcium sulfate is returned to step S5 for recycling.

[0097] Step S7: Evaporate and crystallize the sodium-containing filtrate to obtain industrial-grade sodium sulfate product;

[0098] Preferably, in step S1, the lithium precipitation mother liquor is uniformly mixed with sulfuric acid, the pH is adjusted to 6.5, carbonate is removed, and a decarbonated liquid is obtained. The decarbonated liquid is preheated to 80°C and then evaporated and concentrated. It is cooled to 0°C to crystallize, and sodium sulfate crystals are precipitated. Solid-liquid separation is performed to obtain crude sodium sulfate and lithium-containing filtrate. The crude sodium sulfate is dehydrated and dried at 120°C to obtain industrial-grade sodium sulfate product.

[0099] Preferably, in step S2, TDPA:TOPO (1:1 molar ratio) eutectic extraction-precipitant is added to the obtained lithium-containing filtrate, and the mixture is reacted at 80°C for 30 minutes to selectively precipitate lithium ions. Solid-liquid separation yields TDPA:TOPO-Li precipitate and sodium- and potassium-containing filtrate. The lithium precipitation efficiency is 98.6%, and the sodium co-precipitation rate is less than 0.3%.

[0100] Preferably, in step S3, the obtained TDPA:TOPO-Li precipitate is washed four times with deionized water, then 2.15 mol / L sulfuric acid (liquid-solid ratio 10:12.3 mL / g) is added, and back-extracted at 60°C for 3 hours to obtain a back-extraction solution containing 25.2 g / L of lithium and regenerated TDPA:TOPO eutectic agent, the latter of which is recycled.

[0101] Preferably, in step S4, the pH of the obtained back-extraction solution is adjusted to 11.98, calcium is removed by passing it through a resin column, sodium carbonate (lithium-sodium molar ratio 1:1.1) is added, lithium carbonate is precipitated at 95°C, and after solid-liquid separation, washing, and drying, battery-grade lithium carbonate product with a purity of 99.80% is obtained.

[0102] Preferably, in step S5, the sodium and potassium filtrate is mixed with calcium sulfate (CaSO4·2H2O) at a CaSO4 / K2SO4 molar ratio of 0.9 and reacted at 10°C for 60 minutes to generate potassium gypsum precipitate. The sodium filtrate and potassium gypsum are then separated by solid-liquid separation.

[0103] Preferably, in step S6, the obtained potassium gypsum is mixed with water at a mass ratio of 1:4.5, stirred at 80°C for 2 hours to decompose, and the solid and liquid are separated to obtain a potassium sulfate solution (K). + The potassium sulfate solution (30.95 g / L) and the recycled calcium sulfate solid were evaporated and crystallized to obtain agricultural grade potassium sulfate product (K2 51.2%). The recycled calcium sulfate was recycled.

[0104] Preferably, in step S7, the sodium-containing filtrate obtained after separating potassium gypsum is evaporated and crystallized to obtain industrial-grade sodium sulfate product (purity 99.07%).

[0105] In this embodiment, a closed-loop recycling system is constructed to achieve the full-element resource recovery of lithium, sodium, and potassium in the lithium precipitation mother liquor. The core advantage of preparing battery-grade lithium carbonate lies in the synergistic design of selective extraction precipitation and fine purification. The use of TDPA:TOPO low-melting-point eutectic agent for selective lithium precipitation can efficiently capture lithium ions from a complex system with high sodium and potassium impurities, significantly reducing sodium and potassium co-contamination and ensuring the purity of lithium from the source. Subsequently, through back-extraction, precise calcium removal, and sodium carbonate precipitation, trace impurities are further removed to ensure that the final lithium carbonate product meets battery-grade standards. At the same time, the entire process does not discharge lithium-containing wastewater. Key media such as eutectic agent and calcium sulfate can be regenerated and recycled, which significantly reduces the consumption of auxiliary materials and the pressure on wastewater treatment. Furthermore, by fully recovering by-products of industrial-grade sodium sulfate and agricultural-grade potassium sulfate, the cost of lithium extraction is shared, achieving the unification of high-value lithium product extraction and clean production.

[0106] Please refer to the reference again. Figures 1 to 10 The working principle of the lithium carbonate washing equipment provided by this invention is as follows:

[0107] Step S1: Start the drive motor 32, which drives the rotating rod 33 and the drive rod 43 to rotate via the belt 35 and pulley 34. The drive rod 43 drives the rotating sleeve 42 to rotate. The protrusion 44 on the right side of the rotating sleeve 42 moves along the annular track inside the mounting sleeve 41, so that the rotating sleeve 42 reciprocates along the drive rod 43 while rotating, thereby driving the stirring rod 45 and the stirring paddle 46 to synchronously achieve the combined motion of rotational stirring and reciprocating lifting.

[0108] In step S2, when the stirring rod 45 rotates and rises, the drive ring 82 pushes the rotating seat 81 to move upward, and pushes the sealing plate 85 to slide to the left through the first connecting rod 83, so that the feeding hole coincides with the bottom of the feeding pipe 9, and the lithium carbonate material begins to be fed into the tank. At the same time, the rotating seat 81 rises and drives the moving rod 103 and the transmission gear plate 105 to move to the right through the second connecting rod 101. The rear side of the transmission gear plate 105 meshes with the first drive gear 115 and rotates counterclockwise, driving the first adjusting plate 112 to move backward, so that the exhaust pipe 12 opens first, and the high temperature water vapor and positive pressure in the tank are removed. Then, the front side of the transmission gear plate 105 meshes with the second drive gear 134 and rotates clockwise, driving the second adjusting plate 131 to move forward, so that the air inlet pipe 14 is opened, and nitrogen is introduced into the tank to form an inert atmosphere protective layer, realizing the step of first exhausting and then filling with nitrogen. The newly added lithium carbonate material falls into the turbulent zone in the tank under the protection of nitrogen purging, avoiding moisture absorption and agglomeration.

[0109] In step S3, when the stirring rod 45 moves downward, the spring 86 pushes the sealing plate 85 to slide to the right to reset, the feeding hole and the feeding pipe 9 are misaligned and closed, and the feeding stops. At the same time, the sealing plate 85 drives the rotating seat 81 to reset downward through the first connecting rod 83. The reset spring 104 pushes the moving rod 103 and the transmission gear plate 105 to reset to the left. The transmission gear plate 105 drives the first drive gear 115 to rotate clockwise and the second drive gear 134 to rotate counterclockwise, so that the first adjusting plate 112 and the second adjusting plate 131 reset to the opposite side. During the process, the air inlet pipe 14 will go from the connected state to the sealed state, and the exhaust pipe 12 will go from the sealed state to the connected state, and then go back to the sealed state.

[0110] In step S4, the stirring rod 45 is continuously rotated and raised and lowered, repeating the above movements. The inclined blade centrifugal defoaming composite paddle 7 will rise and fall synchronously with the stirring rod 45. When it is at the low position, it is immersed in the liquid phase to stir the surface slurry. When it is at the high position, it enters the gas phase foam zone as a whole. It relies on the negative pressure suction of the guide gap and the dual crushing of foam by centrifugal impact. It is coordinated with the opening of the feeding hole of the sealing plate 85 and the timing of nitrogen gas introduction to achieve precise intermittent feeding of lithium carbonate material under continuous nitrogen protection. Thus, without crushing and damaging the crystal, it can simultaneously complete the integrated operation of washing mass transfer enhancement, inert atmosphere protection, adaptive defoaming and quantitative feeding.

[0111] 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. A lithium carbonate washing device, characterized in that, Includes a washing tank, a sealing cover, a drive mechanism, and a lifting and rotating washing mechanism; The top of the sealing cover is fixedly provided with a mounting shell. The driving mechanism includes a protective frame fixedly provided on the top of the mounting shell. A drive motor is fixedly provided on the rear side of the bottom of the protective frame. A rotating rod is rotatably connected to the top of the inner wall of the protective frame. Pulleys are fixedly provided on the output shaft of the drive motor and the peripheral side of the rotating rod. A belt is sleeved on the peripheral side of the two pulleys. Two support frames are fixedly provided at the bottom of the protective frame. The bottom of the two support frames is fixedly connected to the top of the sealing cover. The lifting and rotating washing mechanism includes an installation sleeve fixed inside the sealing cover. A rotating sleeve is provided inside the sleeve, and a drive rod is slidably connected inside the rotating sleeve. The bottom end of the rotating rod passes through the top of the installation shell and extends into the interior of the installation shell. The bottom end of the rotating rod is fixedly connected to the top of the drive rod. A protrusion is fixedly provided on the right side of the rotating sleeve. An annular track that cooperates with the protrusion is opened inside the installation sleeve. An agitator rod is fixedly provided at the bottom of the rotating sleeve, and an agitator paddle is fixedly provided on the circumferential side of the agitator rod.

2. The lithium carbonate washing equipment according to claim 1, characterized in that, The mounting sleeve is located inside the mounting shell. When the drive rod rotates, it will drive the rotating sleeve to rotate. When the rotating sleeve rotates, the protrusion will move along the annular track inside the mounting sleeve, so that the rotating sleeve moves up and down along the drive rod at the same time as it rotates.

3. The lithium carbonate washing equipment according to claim 1, characterized in that, The stirring rod is fixed with a mounting ring on its circumferential side. The mounting ring is arranged in a ring array with three oblique blade centrifugal defoaming composite paddles. The upper half of the oblique blade centrifugal defoaming composite paddles is provided with a long guide notch.

4. The lithium carbonate washing equipment according to claim 1, characterized in that, An intermittent dispensing mechanism is fitted around the periphery of the stirring rod. The intermittent dispensing mechanism includes a rotating seat fitted around the periphery of the stirring rod. A drive ring is fixedly mounted on the periphery of the stirring rod and at the bottom of the rotating seat. A first connecting rod is rotatably connected to the top left side of the rotating seat. A sliding frame is fixedly mounted on the bottom left side of the sealing cover. A sealing plate is slidably connected inside the sliding frame. The top of the first connecting rod is rotatably connected to the bottom of the sealing plate. Two springs are provided on the side of the sealing plate opposite to the sliding frame.

5. The lithium carbonate washing equipment according to claim 4, characterized in that, A feeding tube is fixed inside the sealing cover and at the top of the sealing plate. The bottom of the feeding tube is in contact with the top of the sealing plate. A feeding hole for use with the feeding tube is opened inside the sealing plate.

6. The lithium carbonate washing equipment according to claim 4, characterized in that, A transmission mechanism is rotatably connected to the right side of the top of the rotating seat. The transmission mechanism includes a second connecting rod rotatably connected to the right side of the top of the rotating seat. A mounting bracket is fixedly provided on the right side of the bottom of the sealing cover. A moving rod is slidably connected laterally inside the mounting bracket. A return spring is sleeved on the circumferential side of the moving rod and located on the left side of the mounting bracket. The top of the second connecting rod is rotatably connected to the left end of the moving rod. A transmission gear plate is fixedly provided on the right end of the moving rod. Teeth are provided on both sides of the transmission gear plate.

7. The lithium carbonate washing equipment according to claim 6, characterized in that, An exhaust mechanism is fixedly provided on the right side of the bottom of the sealing cover. The exhaust mechanism includes a slide rail fixedly provided on the right side of the bottom of the sealing cover. A first adjusting plate is slidably connected to the surface of the slide rail. A first toothed set is fixedly provided on the left side of the first adjusting plate. A first transmission gear is rotatably connected to the bottom of the sealing cover through a rotating shaft. The first transmission gear meshes with the first toothed set. A first drive gear is fixedly provided at the bottom of the first transmission gear through a rotating shaft. The first drive gear meshes with the rear side of the transmission toothed plate. An exhaust pipe is provided inside the sealing cover and at the top of the first adjusting plate.

8. The lithium carbonate washing equipment according to claim 7, characterized in that, A nitrogen replacement mechanism is slidably connected to the surface of the slide rail. The nitrogen replacement mechanism includes a second adjusting plate slidably connected to the surface of the slide rail. A second toothed set is fixed on the left side of the second adjusting plate. A second transmission gear is rotatably connected to the bottom of the sealing cover via a rotating shaft. The second transmission gear meshes with the second toothed set. A second drive gear is fixed to the bottom of the second transmission gear via a rotating shaft. The second drive gear meshes with the front side of the transmission toothed plate. An air inlet pipe is provided inside the sealing cover and at the top of the second adjusting plate.

9. The lithium carbonate washing equipment according to claim 1, characterized in that, A mounting bracket is fixed to the periphery of the agitation tank, an inlet pipe is connected to the right side of the agitation tank, and a drain pipe is connected to the bottom of the agitation tank.

10. A recycling method for preparing battery-grade lithium carbonate from lithium precipitation mother liquor, characterized in that, Includes the following steps: Step S1: Mix lithium precipitation mother liquor with sulfuric acid, adjust pH to neutral, remove carbonate ions to obtain decarbonated liquor, preheat the decarbonated liquor and evaporate and concentrate it, cool and crystallize to precipitate sodium sulfate crystals, separate solid and liquid to obtain crude sodium sulfate and lithium-containing filtrate, and dehydrate and dry the crude sodium sulfate to obtain industrial grade sodium sulfate product. Step S2: Add TDPA:TOPO low melting point eutectic extractant to the lithium-containing filtrate to selectively precipitate lithium, and separate the solid and liquid to obtain TDPA:TOPO-Li precipitate and filtrate containing sodium and potassium; Step S3: After washing the obtained TDPA:TOPO-Li precipitate with deionized water, add sulfuric acid and heat for back-extraction to obtain the back-extraction solution and the regenerated TDPA:TOPO eutectic agent, the latter of which is returned to step S2 for recycling; Step S4: Adjust the pH of the obtained back-extraction solution to 11-12, remove calcium through resin, add sodium carbonate to precipitate lithium carbonate, and obtain battery-grade lithium carbonate product after solid-liquid separation, washing, and drying. Battery-grade lithium carbonate is used to prepare lithium-ion battery cathode materials. The washing of lithium carbonate needs to be carried out in the lithium carbonate washing equipment as described in claims 1-9. Step S5: Mix the sodium and potassium filtrate with calcium sulfate and react at low temperature to generate potassium gypsum. Separate the solid and liquid phases to obtain the sodium filtrate and potassium gypsum intermediate phase. Step S6: Mix potassium gypsum with water, heat to decompose, and separate the solid and liquid to obtain potassium sulfate solution and regenerated calcium sulfate solid. The potassium sulfate solution is evaporated and crystallized to obtain agricultural grade potassium sulfate product, and the regenerated calcium sulfate is returned to step S5 for recycling. Step S7: Evaporate and crystallize the sodium-containing filtrate to obtain industrial-grade sodium sulfate product.

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