Method and equipment for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetization material

Abstract

The application provides a method and equipment for purifying battery-grade lithium carbonate by dilute acid leaching of magnetic-removing lithium carbonate, and relates to the technical field of lithium carbonate purification, and comprises the following steps: step S1, slurry treatment: mixing battery-grade magnetic-removing lithium carbonate with deionized water and uniformly stirring to obtain a slurry; step S2, mild leaching: adding dilute acid to the slurry and stirring to leach under mild conditions to remove magnetic metal impurities; and step S3, neutralization and recrystallization: quickly adding a neutralizing agent to the leached slurry, adjusting the pH of the slurry, stirring to react, and recrystallizing the trace dissolved lithium carbonate. The scheme finally realizes the mild leaching process without carbonization, avoids the massive dissolution of the main body of lithium carbonate, selectively removes only the magnetic impurities, combines the rapid neutralization and recrystallization, makes the lithium carbonate re-precipitate, the purity of the finished product can reach the high-purity battery-grade standard, the content of magnetic impurities is extremely low, the lithium loss is extremely small in the whole process, the total lithium carbonate yield is extremely high in combination with the mother liquor membrane method.

Description

Technical Field

[0001] This invention relates to the field of lithium carbonate purification, and more particularly to a method and equipment for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetizing material. Background Technology

[0002] Battery-grade lithium carbonate is a core raw material for the cathode material of lithium-ion batteries, and its purity and impurity content directly affect the performance and safety of lithium-ion batteries. In the production process of battery-grade lithium carbonate, demagnetization is a crucial purification step, aiming to remove magnetic impurities (mainly metal oxides and salts such as Fe, Ni, Cr, and Zn) from the lithium carbonate to ensure the product meets battery-grade standards. However, the demagnetization process generates a large amount of demagnetizing material with a magnetic impurity content as high as 8000~12000 ppb, which cannot be directly reused in the production of battery-grade lithium carbonate. Directly discarding this material would not only waste lithium resources but also create environmental pressure.

[0003] Currently, the industry mainly uses traditional carbonization purification processes for purifying battery-grade lithium carbonate demagnetizing materials. The core principle is to react the demagnetizing material with CO2 to generate a lithium bicarbonate solution. After filtration to remove insoluble magnetic impurities, the lithium bicarbonate is then heated to decompose and obtain high-purity lithium carbonate. However, this process has significant drawbacks: firstly, it requires a large amount of high-purity CO2, resulting in high reagent costs; secondly, both the carbonization and decomposition reactions require specific temperatures and pressures, leading to high energy consumption; and thirdly, the process is complex, with long reaction cycles and large equipment investments, resulting in high overall purification costs and making it difficult to achieve large-scale, low-cost recycling of demagnetizing materials.

[0004] Therefore, it is necessary to provide a method for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetizing material to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a method for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetizing material, which solves the problems of high reagent cost and high energy consumption in the purification of existing battery-grade lithium carbonate demagnetizing materials.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetizing material, comprising the following steps:

[0007] Step S1, Slurry treatment: Mix battery-grade lithium carbonate demagnetizing material with deionized water and stir evenly to obtain a slurry;

[0008] Step S2, Gentle Leaching: Add dilute acid to the slurry and leach under gentle conditions to remove magnetic metal impurities;

[0009] Step S3, Neutralization and Recrystallization: A neutralizing agent is quickly added to the leached slurry to adjust the pH of the slurry. The mixture is stirred to react and allow the trace amounts of dissolved lithium carbonate to recrystallize.

[0010] Step S4, solid-liquid separation: the recrystallized slurry is filtered and washed to obtain high-purity lithium carbonate wet material and mother liquor;

[0011] Step S5: Drying the finished product: Dry the obtained high-purity lithium carbonate wet material to obtain battery-grade lithium carbonate finished product;

[0012] Step S6, Mother liquor recovery: The mother liquor is treated through a nanofiltration membrane to recover the lithium solution, which is then returned to the pulping process for recycling, thus realizing the recycling of lithium resources.

[0013] Equipment for purifying lithium carbonate by dilute acid leaching of demagnetizing material for battery-grade lithium carbonate includes a slurrying kettle, a mixing mechanism, a regulating mechanism, and a centrifugal feeding mechanism.

[0014] The mixing mechanism is used to mix battery-grade lithium carbonate demagnetizing material and deionized material, and includes a stirring shaft vertically arranged inside the slurry tank;

[0015] The adjustment mechanism includes an adjustment seat fixed to the surface of the stirring shaft by bolts. Two rotating brackets are fixed on both sides of the top of the adjustment seat. The surfaces of the two rotating brackets are rotatably connected to a first connecting rod. The circumferential side of the stirring shaft and the top of the adjustment seat are fixed to a rotating seat by bolts. The two sides of the rotating seat are rotatably connected to a second connecting rod. The tops of the two first connecting rods are rotatably connected to the two second connecting rods respectively.

[0016] The centrifugal feeding mechanism includes a feeding cylinder, an adjusting sleeve rotatably connected to the circumferential side of the bottom of the feeding cylinder, a drive motor fixedly mounted at the bottom of the feeding cylinder, the output shaft of the drive motor fixedly connected to the center of the adjusting sleeve, feeding holes opened inside both the feeding cylinder and the adjusting sleeve, a guide plate fixedly mounted at the bottom inside the feeding cylinder, a sealing plate rotatably connected to the top of the feeding cylinder, and a connecting bracket fixedly mounted on the right side of the feeding cylinder.

[0017] Preferably, the centrifugal feeding mechanism is arranged in two sets in a left-right mirror configuration. The two feeding cylinders are respectively fixedly connected to the bottom ends of the two second connecting rods through two connecting brackets. The feeding cylinders are used to store battery-grade lithium carbonate demagnetizing material. When the stirring shaft rotates, it will drive the centrifugal feeding mechanism to rotate through the adjustment mechanism, and use centrifugal force to feed the battery-grade lithium carbonate demagnetizing material.

[0018] Preferably, the feeding cylinder has a feeding chamber inside, which is a frustum-shaped cone that is larger at the top and smaller at the bottom. The bottom of the inner wall of the feeding cylinder is designed to be inclined, with the lowest point of the inclined bottom surface located on one side in the direction of centrifugal force. The feeding hole inside the feeding cylinder is located on one side in the direction of centrifugal force and is a conical hole that is larger on the inner side and smaller on the outer side.

[0019] Preferably, the circumferential side of the stirring shaft is fitted with an adaptive adjustment mechanism, the adaptive adjustment mechanism including a floating seat fitted on the circumferential side of the stirring shaft, the floating seat being disposed at the bottom of the adjustment seat, the bottom of the floating seat being fixedly provided with a float, and the top of the floating seat being fixedly provided with multiple connecting rods by bolts, the top ends of the multiple connecting rods being fixedly connected to the adjustment seat.

[0020] Preferably, an active defoaming mechanism is fixedly provided on the circumferential side of the stirring shaft. The active defoaming mechanism includes a mounting base fixedly provided on the circumferential side of the stirring shaft. The mounting base is located at the bottom of the floating seat. Four connecting seats are arranged in a circular array on the top of the mounting base. Defoaming plates are rotatably connected to the surfaces of the four connecting seats. Four third connecting rods are rotatably connected to the circumferential side of the floating seat. The ends of the four third connecting rods that are far apart are respectively rotatably connected to the four defoaming plates.

[0021] Preferably, an active anti-sticking mechanism is fixedly provided at the top of the inner wall of the feeding cylinder. The active anti-sticking mechanism includes an installation ring fixedly provided at the top of the inner wall of the feeding cylinder, a connecting rope fixedly provided at the bottom of the installation ring, and an eccentric hammer fixedly provided at the bottom of the connecting rope.

[0022] Preferably, the mixing mechanism further includes multiple sets of stirring blades fixed to the periphery of the stirring shaft, and a cross frame is fixed to the top of the slurry tank, with a stirring motor for driving the stirring shaft to rotate on the top of the cross frame.

[0023] Preferably, the top of the slurry reactor is fixed with a sealing plate by bolts, the right side of the slurry reactor is connected to a liquid inlet pipe, the bottom of the slurry reactor is connected to a discharge pipe, and four support brackets are arranged in a ring array on the periphery of the slurry reactor.

[0024] Compared with related technologies, the method for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetizing material provided by the present invention has the following beneficial effects:

[0025] Employing a non-carbonation, gentle leaching process, this method avoids the extensive dissolution of lithium carbonate, selectively removing only magnetic impurities. Combined with rapid neutralization and recrystallization, lithium carbonate is redeposited, resulting in a finished product with high-purity battery-grade standards and extremely low magnetic impurity content. Lithium loss is minimal throughout the process. Combined with mother liquor membrane recovery, the overall lithium carbonate yield is extremely high. This method eliminates the need for high-temperature heating and complex equipment, requires minimal reagents, recycles washing water, and eliminates wastewater discharge, significantly reducing extraction and storage costs. It also meets green production requirements. The process is concise, operates under mild conditions, and utilizes mature equipment, making it easy to scale up industrially. This method achieves efficient recovery and high-quality regeneration of lithium carbonate from demagnetized materials. Attached Figure Description

[0026] 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.

[0027] Figure 1 This is a schematic diagram of the method flow provided by the present invention;

[0028] Figure 2 The optimal structural schematic diagram provided for this invention;

[0029] Figure 3 for Figure 2 The diagram shows a cross-sectional view of the slurry reactor.

[0030] Figure 4 This is a schematic diagram of the structure of the adjustment mechanism and the centrifugal feeding mechanism provided by the present invention;

[0031] Figure 5 for Figure 4 The diagram shows a structural schematic of the cross-sectional view of the feed cylinder.

[0032] Figure 6 A schematic diagram showing the state in which the adjusting seat provided by the present invention moves upward, driving two revolving centrifugal feeding mechanisms to move to opposite sides via the first and second connecting rods;

[0033] Figure 7 Schematic diagram of the adaptive adjustment mechanism and active defoaming mechanism provided by the present invention;

[0034] Figure 8 for Figure 7 The enlarged structural diagram at point A is shown below;

[0035] Figure 9 A schematic diagram showing the state in which the floating seat provided by the present invention moves upward and the four defoaming plates move to a different side via the third connecting rod;

[0036] Figure 10 This is a schematic diagram of the anti-sticking mechanism provided by the present invention;

[0037] Figure 11 This is a schematic diagram of the structure of the hybrid mechanism provided by the present invention.

[0038] Explanation of icon numbers:

[0039] 1. Pulping kettle;

[0040] 2. Mixing mechanism; 21. Stirring shaft; 22. Stirring paddle; 23. Stirring motor;

[0041] 3. Adjustment mechanism; 31. Adjustment seat; 32. Rotating bracket; 33. First connecting rod; 34. Rotating seat; 35. Second connecting rod;

[0042] 4. Centrifugal feeding mechanism; 41. Feeding cylinder; 42. Adjusting sleeve; 43. Drive motor; 44. Feeding hole; 45. Guide plate; 46. Sealing plate; 47. Connecting bracket;

[0043] 5. Adaptive adjustment mechanism; 51. Floating seat; 52. Float; 53. Connecting rod;

[0044] 6. Active defoaming mechanism; 61. Mounting base; 62. Connecting base; 63. Defoaming plate; 64. Third connecting rod;

[0045] 7. Anti-sticking mechanism; 71. Mounting ring; 72. Connecting rope; 73. Eccentric hammer;

[0046] 8. Horizontal frame;

[0047] 9. Sealing plate; 10. Liquid inlet pipe; 11. Discharge pipe; 12. Support bracket. Detailed Implementation

[0048] 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.

[0049] This invention provides a method for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetizing material.

[0050] Please see Figure 1 A method for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetizing material includes the following steps:

[0051] Step S1, Slurry treatment: Mix battery-grade lithium carbonate demagnetizing material with deionized water and stir evenly to obtain a slurry;

[0052] Step S2, Gentle Leaching: Add dilute acid to the slurry and leach under gentle conditions to remove magnetic metal impurities;

[0053] Step S3, Neutralization and Recrystallization: A neutralizing agent is quickly added to the leached slurry to adjust the pH of the slurry. The mixture is stirred to react and allow the trace amounts of dissolved lithium carbonate to recrystallize.

[0054] Step S4, solid-liquid separation: the recrystallized slurry is filtered and washed to obtain high-purity lithium carbonate wet material and mother liquor;

[0055] Step S5: Drying the finished product: Dry the obtained high-purity lithium carbonate wet material to obtain battery-grade lithium carbonate finished product;

[0056] Step S6, Mother liquor recovery: The mother liquor is treated through a nanofiltration membrane to recover the lithium solution, which is then returned to the slurry processing step for recycling, thus realizing the recycling of lithium resources;

[0057] Preferably, in step S1, battery-grade lithium carbonate demagnetizing material is mixed with deionized water and stirred evenly to obtain a slurry. The liquid-to-solid ratio of the slurry is (3~8):1 (v / w), the slurry concentration is 120~330g / L, and the magnetic impurity content of the battery-grade lithium carbonate demagnetizing material is 8000~12000ppb. The magnetic impurities are mainly one or more metal oxides and salts of Fe, Ni, Cr, and Zn.

[0058] Preferably, in step S2, the leaching temperature is controlled at 20~50℃, the stirring speed is 100~300r / min, and the leaching time is 10~60min to gently leach magnetic metal impurities in the demagnetized material. The concentration of the dilute acid is 0.5~2wt%, and the amount of dilute acid added is 5~20% of the slurry mass. The dilute acid is one or a mixture of two of hydrochloric acid and sulfuric acid, and the mass ratio of hydrochloric acid to sulfuric acid in the mixture is (1~3):1.

[0059] Preferably, in step S3, the pH of the slurry is adjusted to 7.5~9.5, and the reaction is stirred for 5~20 minutes to allow the trace amount of dissolved lithium carbonate to recrystallize. The neutralizing agent is one or a mixture of lithium hydroxide and lithium carbonate. The neutralizing agent is added at a rate of 0.5~2g / min to ensure that the pH of the slurry quickly reaches the specified range and to avoid secondary encapsulation of magnetic impurities.

[0060] Preferably, in step S4, deionized water is used for washing, and the number of washing cycles is 2 to 4. The amount of water used for each washing is 1 to 2 times the mass of the high-purity lithium carbonate wet material, and the conductivity of the wet material after washing is ≤50μS / cm.

[0061] Preferably, in step S5, the high-purity lithium carbonate wet material is dried at 80~120℃ for 2~6 hours to obtain battery-grade lithium carbonate product. The dried battery-grade lithium carbonate product has a magnetic impurity content ≤50ppb and a purity ≥99.5%.

[0062] Preferably, in step S6, the nanofiltration membrane has a molecular weight cutoff of 100~300 Da, an operating pressure of 0.3~0.8 MPa, a temperature of 25~40℃, and a lithium recovery rate of ≥99%.

[0063] In this embodiment, a non-carbonation mild leaching process is adopted to avoid the dissolution of a large amount of lithium carbonate and to selectively remove magnetic impurities. Combined with rapid neutralization and recrystallization, lithium carbonate is redeposited, and the purity of the finished product can reach the high-purity battery grade standard with extremely low magnetic impurity content. The lithium loss is minimal throughout the process. With the mother liquor membrane method for recovery, the total lithium carbonate yield is extremely high. No high-temperature heating or complex equipment is required, the amount of reagents used is small, the washing water is recycled, and there is no wastewater discharge, which greatly reduces the extraction and storage costs. At the same time, it meets the requirements of green production. The process flow is simple, the operating conditions are mild, and all mature equipment is used, which is easy to scale up industrially and achieves efficient recovery and high-quality regeneration of lithium carbonate in demagnetized materials.

[0064] The present invention also provides an apparatus for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetizing material.

[0065] First embodiment:

[0066] Please see Figures 2 to 6 Equipment for purifying lithium carbonate by dilute acid leaching of demagnetizing lithium carbonate for battery grade includes a slurrying kettle 1, a mixing mechanism 2, an adjusting mechanism 3, and a centrifugal feeding mechanism 4.

[0067] The mixing mechanism 2 is used to mix battery-grade lithium carbonate demagnetizing material and deionized material, and includes a stirring shaft 21 vertically arranged inside the slurry tank 1;

[0068] The adjustment mechanism 3 includes an adjustment seat 31 fixed to the surface of the stirring shaft 21 by bolts. Two rotating brackets 32 are fixed to both sides of the top of the adjustment seat 31. The surfaces of the two rotating brackets 32 are rotatably connected to the first connecting rods 33. A rotating seat 34 is fixed to the circumferential side of the stirring shaft 21 and located at the top of the adjustment seat 31 by bolts. The two sides of the rotating seat 34 are rotatably connected to the second connecting rods 35. The tops of the two first connecting rods 33 are respectively rotatably connected to the two second connecting rods 35.

[0069] The centrifugal feeding mechanism 4 includes a feeding cylinder 41, an adjusting sleeve 42 rotatably connected to the circumferential side of the bottom of the feeding cylinder 41, a drive motor 43 fixedly mounted at the bottom of the feeding cylinder 41, the output shaft of the drive motor 43 fixedly connected to the center of the adjusting sleeve 42, feeding holes 44 are provided inside both the feeding cylinder 41 and the adjusting sleeve 42, a guide plate 45 is fixedly mounted at the bottom inside the feeding cylinder 41, a sealing plate 46 is rotatably connected to the top of the feeding cylinder 41, and a connecting bracket 47 is fixedly mounted on the right side of the feeding cylinder 41.

[0070] The centrifugal feeding mechanism 4 is arranged in two sets, mirror images of each other. The two feeding cylinders 41 are respectively fixedly connected to the bottom ends of the two second connecting rods 35 through two connecting brackets 47. The feeding cylinders 41 are used to store battery-grade lithium carbonate demagnetizing material. When the stirring shaft 21 rotates, it will drive the centrifugal feeding mechanism 4 to revolve through the adjusting mechanism 3, and use centrifugal force to feed the battery-grade lithium carbonate demagnetizing material.

[0071] The feeding cylinder 41 has a feeding chamber inside, which is a frustum-shaped cone that is larger at the top and smaller at the bottom. The bottom of the inner wall of the feeding cylinder 41 is designed to be inclined, with the lowest point of the inclined bottom surface located on one side in the direction of centrifugal force. The feeding hole 44 is opened inside the feeding cylinder 41 and is located on one side in the direction of centrifugal force. The feeding hole 44 is a conical hole, which is larger on the inner side and smaller on the outer side.

[0072] Preferably, both the top of the feeding cylinder 41 and the top of the sealing plate 46 are provided with through grooves. When the sealing plate 46 is rotated, the two through grooves overlap, so that demagnetizing material can be added into the feeding cylinder 41.

[0073] Please combine Figures 4 to 6 When the stirring shaft 21 rotates, it drives the adjusting seat 31, the rotating seat 34, the first connecting rod 33 and the second connecting rod 35 to rotate. The rotation of the second connecting rod 35 then drives the two feeding cylinders 41 to revolve around the center of the stirring shaft 21 through the connecting bracket 47. During the revolve, the two feeding cylinders 41 generate centrifugal force, which presses the demagnetizing material inside towards the outer wall (the side away from the stirring shaft 21). The guide plate 45 and the inclined bottom surface inside the feeding cylinder 41 guide the powder to the feeding hole 44 located on the side of the centrifugal force direction. The feeding hole 44 is a cone shape with a larger inner diameter and a smaller outer diameter, which facilitates the extrusion of the powder. After the powder is thrown out from the feeding hole 44, it is evenly sprinkled on the liquid surface in the slurry tank 1, achieving dust-free and anti-caking feeding.

[0074] Furthermore, by controlling the drive motor 43 to rotate, the drive motor 43 rotates and drives the adjusting sleeve 42 to rotate. The adjustment sleeve 42 rotates and adjusts the position of the feeding hole 44 inside it, thereby forming a sealed state for the feeding cylinder 41. When the feeding cylinder 41 revolves with the stirring shaft 21, the position of the feeding cylinder 41 is adjusted intermittently, so that the demagnetizing material can be intermittently fed into the slurry kettle 1.

[0075] Furthermore, when the height of the adjusting seat 31 is adjusted upward by the bolt, the bottom of the two first connecting rods 33 will move upward simultaneously. The two second connecting rods 35 and the connecting bracket 47 will adjust the two feeding cylinders 41 to a higher position on a different side. When the distance between the two feeding cylinders 41 and the stirring shaft 21 increases, the centrifugal force on the two feeding cylinders 41 will increase at the same stirring speed, thereby increasing the feeding speed of the demagnetizing material.

[0076] Preferably, without changing the height position of the adjusting seat 31, the greater the rotation speed of the stirring shaft 21, the greater the revolution speed of the two feeding cylinders 41. Therefore, the lateral pressure on the powder will increase sharply with the increase of rotation speed, and the powder extrusion speed at the feeding hole 44 will also increase significantly. At the same time, the higher revolution speed will also enhance the shearing and vibration of the powder in the feeding cylinder 41, which will help to break the powder bridging and further promote the feeding.

[0077] In this embodiment, when the stirring shaft 21 rotates, it will drive the two feeding cylinders 41 to revolve around the center of the stirring shaft 21 through the adjustment mechanism 3. During the revolve, the two feeding cylinders 41 will generate centrifugal force, thereby pressing the demagnetizing material inside to the outer wall. The material is then evenly sprinkled onto the liquid surface in the slurry kettle 1 through the feeding hole 44. This can eliminate the problem of dust and powder flying in traditional direct feeding. In addition, the continuous centrifugal shear force generated by the revolve will also have a vibration effect, which can break up the agglomeration of lithium carbonate powder and destroy the bridging dead zone formed by the powder in the cylinder. This solves the industry pain point of easy arching and blockage of the feeding port of lithium battery fine powder from the root, and ensures continuous and uninterrupted feeding.

[0078] Furthermore, by adjusting the height of the adjusting seat 31, the center radius of the feeding cylinder 41 and the stirring shaft 21 is expanded. At the same rotation speed, the centrifugal force will increase synchronously, directly improving the powder extrusion feeding rate. The feeding speed can be mechanically and precisely adjusted according to the slurry ratio requirements, adapting to the preparation of lithium carbonate slurry of different concentrations. The feeding speed is also proportional to the rotation speed of the stirring shaft 21. By simply adjusting the rotation speed of the stirring shaft 21, the linear velocity of the feeding cylinder 41 can be changed. The higher the rotation speed, the stronger the centrifugal extrusion force and the faster the discharge speed. It is suitable for two production conditions: fast feeding premixing and slow feeding fine homogenization, making it easy to adjust flexibly and conveniently.

[0079] Second embodiment:

[0080] Please see Figures 7 to 9 An adaptive adjustment mechanism 5 is fitted around the periphery of the stirring shaft 21. The adaptive adjustment mechanism 5 includes a floating seat 51 fitted around the periphery of the stirring shaft 21. The floating seat 51 is located at the bottom of the adjusting seat 31. A float 52 is fixedly provided at the bottom of the floating seat 51. A plurality of connecting rods 53 are fixedly provided at the top of the floating seat 51 by bolts. The top ends of the plurality of connecting rods 53 are fixedly connected to the adjusting seat 31.

[0081] An active defoaming mechanism 6 is fixedly provided on the circumferential side of the stirring shaft 21. The active defoaming mechanism 6 includes a mounting base 61 fixedly provided on the circumferential side of the stirring shaft 21. The mounting base 61 is located at the bottom of the floating seat 51. Four connecting seats 62 are arranged in a circular array on the top of the mounting base 61. Defoaming plates 63 are rotatably connected to the surfaces of the four connecting seats 62. Four third connecting rods 64 are rotatably connected to the circumferential side of the floating seat 51. The four third connecting rods 64 are respectively rotatably connected to the four defoaming plates 63 at their respective ends.

[0082] Please combine Figures 7 to 9 When the fixing bolts between the adjusting seat 31 and the stirring shaft 21 are loosened, the adjusting seat 31 can slide freely along the axial direction of the stirring shaft 21. At this time, if the liquid level in the slurry tank 1 rises, the float 52 will drive the floating seat 51 to move upward under the action of buoyancy. The floating seat 51 pushes the adjusting seat 31 to move upward synchronously through the connecting rod 53. The upward movement of the adjusting seat 31, through the cooperation of the first connecting rod 33 and the second connecting rod 35, will cause the two feeding cylinders 41 to move away from the axis of the stirring shaft 21, that is, the radius of revolution increases. Under the premise that the rotation speed of the stirring shaft 21 remains unchanged, the increase in the radius of revolution leads to a linear increase in the centrifugal force on the demagnetized material in the feeding cylinder 41, thereby increasing the amount of demagnetized material squeezed out from the feeding hole 44. Thus, the feeding rate automatically increases as the liquid level rises (that is, the amount of deionized water added increases), so that the feeding rate of the demagnetized material and the amount of deionized water added form an approximately positive proportional relationship, ensuring the stability of the slurry concentration without manual intervention.

[0083] Furthermore, as the liquid level rises, the float 52 drives the floating seat 51 to move upward. When the floating seat 51 rises, the third connecting rod 64 is lifted upward, forcing the defoaming plate 63 to swing upward around the hinge point of the connecting seat 62 (that is, the angle between the defoaming plate 63 and the liquid surface increases, and the plate body deflects in a direction closer to the horizontal). At the same time, due to the rise in liquid level, the probability of foam generation in the slurry tank 1 will increase. When the defoaming plate 63 rotates at high speed with the stirring shaft 21, the plate surface will shear and impact the bubbles on the liquid surface, which can effectively break the foam. The upward swing angle adjustment of the defoaming plate 63 is just adapted to the higher liquid level, so that it always acts on the foam enrichment layer, and the defoaming efficiency can be maintained or even improved.

[0084] Furthermore, the rise of the floating seat 51 will drive the adjusting seat 31 to move upward through the connecting rod 53, thereby increasing the revolution radius of the feeding cylinder 41 and increasing the feeding rate of the demagnetizing material. At this time, the active attitude adjustment of the defoaming plate 63 and the increase in feeding rate occur simultaneously, realizing the automatic matching of increased feeding amount, increased risk of foam generation, and simultaneous enhancement of defoaming force, without the need for manual intervention.

[0085] In this embodiment, when the liquid level rises, the float 52 drives the floating seat 51 to move upward. On the one hand, the connecting rod 53 pushes the adjusting seat 31 to increase the revolution radius of the feeding cylinder 41, so that the centrifugal force increases linearly and the feeding rate is automatically matched with the amount of deionized water added, thereby stabilizing the slurry concentration. On the other hand, the third connecting rod 64 forces the defoaming plate 63 to swing upward, so that it is always shallowly immersed in the optimal defoaming layer on the liquid surface. As the stirring shaft 21 rotates at high speed, it breaks up the foam that increases due to the increase in feeding. Thus, the feeding amount and the defoaming force are enhanced simultaneously without manual intervention, which not only ensures the uniformity and concentration stability of the slurry process, but also effectively suppresses the risk of foam overflow.

[0086] Third embodiment:

[0087] Please see Figure 2 , Figure 10 and Figure 11 An active anti-sticking mechanism 7 is fixedly provided on the top of the inner wall of the feeding cylinder 41. The active anti-sticking mechanism 7 includes an installation ring 71 fixedly provided on the top of the inner wall of the feeding cylinder 41, a connecting rope 72 fixedly provided on the bottom of the installation ring 71, and an eccentric hammer 73 fixedly provided on the bottom of the connecting rope 72.

[0088] The mixing mechanism 2 also includes multiple sets of stirring paddles 22 fixed to the periphery of the stirring shaft 21. A cross frame 8 is fixed to the top of the slurry tank 1, and a stirring motor 23 for driving the stirring shaft 21 to rotate is provided on the top of the cross frame 8.

[0089] The top of the slurry reactor 1 is fixed with a sealing plate 9 by bolts. The right side of the slurry reactor 1 is connected to a liquid inlet pipe 10. The bottom of the slurry reactor 1 is connected to a discharge pipe 11. Four support brackets 12 are arranged in a ring array on the circumferential side of the slurry reactor 1.

[0090] Please combine Figure 10 When the lower feed cylinder 41 revolves with the stirring shaft 21, the eccentric hammer 73 is thrown outward (away from the axis of the stirring shaft 21) by centrifugal force, swings radially and hits the inner wall of the outer side of the lower feed cylinder 41. This knocking action can shake off the demagnetizing powder adhering to the cylinder wall, prevent the powder from solidifying due to static electricity or compaction, keep the inner wall smooth and avoid clogging of the feeding hole 44.

[0091] When the revolution stops, the centrifugal force disappears, and the eccentric hammer 73 will naturally droop and continue to swing back under the action of gravity. During the swinging process, it will hit the inner wall of the feed cylinder 41 (the side near the stirring shaft 21), thereby realizing bidirectional knocking and achieving an automatic self-cleaning cycle of cleaning the outside when rotating and cleaning the inside when stopping, without the need for manual intervention or additional power source.

[0092] During the revolution, since the connecting rope 72 is a flexible connection, the eccentric hammer 73 will also generate irregular additional vibrations under the alternating action of centrifugal force and gravity, further enhancing the destructive effect on powder bridging and ensuring that the inside of the feed cylinder 41 is always unobstructed.

[0093] Please combine Figure 11 Start the stirring motor 23. The stirring motor 23 rotates, which drives the stirring shaft 21 to rotate. The rotation of the stirring shaft 21 drives the stirring paddle 22 to rotate, thereby mixing the demagnetizing material and deionized water.

[0094] In this embodiment, the eccentric hammer 73 is driven alternately by the centrifugal force of revolution and gravity to achieve a two-way self-cleaning cycle that strikes the outer inner wall of the feeding cylinder 41 when rotating and swings back to strike the inner inner wall when stopping. This effectively shakes off the adhering demagnetizing powder and prevents the feeding hole 44 from becoming blocked. At the same time, the irregular additional vibration generated by the flexible connecting rope 72 further destroys the powder bridging, ensuring smooth feeding without manual intervention or additional power, and greatly reducing the frequency of downtime maintenance.

[0095] In another application, the equipment for leaching and purifying lithium carbonate with dilute acid using battery-grade lithium carbonate demagnetizing material can also be used in the fields of food additives and health products. For example, it can be used to add easily dusty powders such as microcrystalline cellulose, whey protein powder, vegetable fat powder, and dietary fiber to liquids to prepare suspensions or emulsions. This can prevent clumping and "fish eye" phenomena, improve dispersion uniformity, and allow for intermittent feeding to control the addition rhythm and ensure formula accuracy.

[0096] In another application, the equipment for leaching and purifying lithium carbonate with dilute acid using battery-grade lithium carbonate demagnetizing material can also be used for the powder dispersion and slurrying of novel functional materials, including nanoscale new materials such as graphene, carbon nanotubes, and nano-silica, as well as the pre-mixing and slurrying process of composite materials. By using centrifugal throwing feeding, the nanoparticles can quickly and uniformly contact the dispersion medium. Combined with stirring, the agglomeration of nanoparticles is reduced, the surface activity of nanomaterials is fully utilized, and the performance of new materials is improved.

[0097] Please refer to the reference again. Figures 2 to 11 The working principle of the equipment for leaching and purifying lithium carbonate with dilute acid using battery-grade lithium carbonate demagnetizing material provided by this invention is as follows:

[0098] Step S1: Add deionized water into the slurry reactor 1 through the liquid inlet pipe 10, load the battery-grade lithium carbonate demagnetizing material into the two feeding cylinders 41, close the sealing plate 46, start the stirring motor 23, drive the stirring shaft 21 to rotate, when the stirring shaft 21 rotates, it will drive the adjusting seat 31, rotating seat 34, first connecting rod 33 and second connecting rod 35 to rotate, the second connecting rod 35 rotates and then drives the two feeding cylinders 41 to revolve around the center of the stirring shaft 21 through the connecting bracket 47. During the revolve, the two feeding cylinders 41 will generate centrifugal force, which will press the demagnetizing material inside against the outer wall. The guide plate 45 and the inclined bottom surface inside the feeding cylinder 41 will guide the powder to the feeding hole 44 located on the side of the centrifugal force direction. The feeding hole 44 is a cone shape with a larger inner diameter and a smaller outer diameter, which makes it easier for the powder to be squeezed out. After the powder is thrown out from the feeding hole 44, it is evenly sprinkled on the liquid surface in the slurry reactor 1.

[0099] In step S2, after the height of the adjusting seat 31 is adjusted upward by the bolt, the bottom of the two first connecting rods 33 will move upward simultaneously. The two second connecting rods 35 and the connecting bracket 47 will adjust the two feeding cylinders 41 to a higher position on a different side. When the distance between the two feeding cylinders 41 and the stirring shaft 21 increases, the centrifugal force on the two feeding cylinders 41 will increase at the same stirring speed, and thus the feeding speed of the demagnetizing material will also increase.

[0100] In step S3, after the fixing bolts between the adjusting seat 31 and the stirring shaft 21 are loosened, the adjusting seat 31 can slide freely along the axial direction of the stirring shaft 21. At this time, if the liquid level in the slurry tank 1 rises, the float 52 will drive the floating seat 51 to move upward under the action of buoyancy. The floating seat 51 pushes the adjusting seat 31 to move upward synchronously through the connecting rod 53. The upward movement of the adjusting seat 31, through the cooperation of the first connecting rod 33 and the second connecting rod 35, will cause the two feeding cylinders 41 to move away from the axis of the stirring shaft 21, that is, the revolution radius increases. Under the premise that the rotation speed of the stirring shaft 21 remains unchanged, the increase in revolution radius leads to a linear increase in the centrifugal force on the demagnetized material in the feeding cylinder 41, thereby increasing the amount of demagnetized material squeezed out from the feeding hole 44. Thus, the feeding rate automatically increases as the liquid level rises (that is, the amount of deionized water added increases).

[0101] In step S4, as the liquid level rises, the float 52 drives the floating seat 51 to move upward. When the floating seat 51 rises, the third connecting rod 64 is lifted upward, forcing the defoaming plate 63 to swing upward around the hinge point of the connecting seat 62. At the same time, due to the rise in liquid level, the probability of foam generation in the slurry tank 1 will increase. When the defoaming plate 63 rotates at high speed with the stirring shaft 21, the plate surface will shear and impact the bubbles on the liquid surface, which can effectively break the foam.

[0102] Step S5: When the lower material cylinder 41 revolves with the stirring shaft 21, the eccentric hammer 73 is thrown outward by centrifugal force, swings radially and hits the outer inner wall of the lower material cylinder 41. This knocking action can shake off the demagnetizing powder adhering to the cylinder wall.

[0103] When the revolution stops, the centrifugal force disappears, and the eccentric hammer 73 will naturally droop and continue to swing back under the action of gravity. During the swinging process, it will hit the inner wall of the feed cylinder 41, thereby realizing bidirectional knocking and achieving an automatic self-cleaning cycle of cleaning the outer side when rotating and cleaning the inner side when stopping.

[0104] During the revolution, because the connecting rope 72 is a flexible connection, the eccentric hammer 73 will also generate irregular additional vibrations under the alternating action of centrifugal force and gravity, further enhancing the destructive effect on the powder bridging.

[0105] In step S6, the stirring motor 23 rotates, which drives the stirring shaft 21 to rotate. The rotation of the stirring shaft 21 drives the stirring paddle 22 to rotate, thus mixing the demagnetizing material and the deionized water.

[0106] 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 process for the purification of battery grade lithium carbonate by dilute acid leaching of a magnetic removed lithium carbonate material, characterised in that, Includes the following steps: Step S1, Slurry treatment: Mix battery-grade lithium carbonate demagnetizing material with deionized water and stir evenly to obtain a slurry; Step S2, Gentle Leaching: Add dilute acid to the slurry and leach under gentle conditions to remove magnetic metal impurities; Step S3, Neutralization and Recrystallization: A neutralizing agent is quickly added to the leached slurry to adjust the pH of the slurry. The mixture is stirred to react and allow the trace amounts of dissolved lithium carbonate to recrystallize. Step S4, solid-liquid separation: the recrystallized slurry is filtered and washed to obtain high-purity lithium carbonate wet material and mother liquor; Step S5: Drying the finished product: Dry the obtained high-purity lithium carbonate wet material to obtain battery-grade lithium carbonate finished product; Step S6, Mother liquor recovery: The mother liquor is treated through a nanofiltration membrane to recover the lithium solution, which is then returned to the pulping process for recycling, thus realizing the recycling of lithium resources.

2. The equipment for purifying lithium carbonate of battery grade by dilute acid leaching of magnetic removal material, characterized in that, The equipment for purifying lithium carbonate is used in step S1 of the method for purifying lithium carbonate by dilute acid leaching of battery-grade lithium carbonate demagnetizing material as described in claim 1, and includes a slurrying kettle, a mixing mechanism, an adjusting mechanism, and a centrifugal feeding mechanism. The mixing mechanism is used to mix battery-grade lithium carbonate demagnetizing material and deionized material, and includes a stirring shaft vertically arranged inside the slurry tank; The adjustment mechanism includes an adjustment seat fixed to the surface of the stirring shaft by bolts. Two rotating brackets are fixed on both sides of the top of the adjustment seat. The surfaces of the two rotating brackets are rotatably connected to a first connecting rod. The circumferential side of the stirring shaft and the top of the adjustment seat are fixed to a rotating seat by bolts. The two sides of the rotating seat are rotatably connected to a second connecting rod. The tops of the two first connecting rods are rotatably connected to the two second connecting rods respectively. The centrifugal feeding mechanism includes a feeding cylinder, an adjusting sleeve rotatably connected to the circumferential side of the bottom of the feeding cylinder, a drive motor fixedly mounted at the bottom of the feeding cylinder, the output shaft of the drive motor fixedly connected to the center of the adjusting sleeve, feeding holes opened inside both the feeding cylinder and the adjusting sleeve, a guide plate fixedly mounted at the bottom inside the feeding cylinder, a sealing plate rotatably connected to the top of the feeding cylinder, and a connecting bracket fixedly mounted on the right side of the feeding cylinder.

3. The equipment for leaching and purifying lithium carbonate from battery-grade lithium carbonate demagnetizing material using dilute acid according to claim 2, characterized in that, The centrifugal feeding mechanism is arranged in two sets, mirror images of each other. The two feeding cylinders are fixedly connected to the bottom ends of the two second connecting rods through two connecting brackets. The feeding cylinders are used to store battery-grade lithium carbonate demagnetizing material. When the stirring shaft rotates, it will drive the centrifugal feeding mechanism to rotate through the adjustment mechanism, and use centrifugal force to feed the battery-grade lithium carbonate demagnetizing material.

4. The equipment for leaching and purifying lithium carbonate from battery-grade lithium carbonate demagnetizing material using dilute acid according to claim 2, characterized in that, The feeding cylinder has a feeding chamber inside, which is a frustum-shaped cone that is larger at the top and smaller at the bottom. The bottom of the inner wall of the feeding cylinder is designed to be inclined, with the lowest point of the inclined bottom surface located on one side in the direction of centrifugal force. The feeding hole inside the feeding cylinder is located on one side in the direction of centrifugal force and is a conical hole that is larger on the inside and smaller on the outside.

5. The apparatus for purifying lithium carbonate of battery grade by magnetic separation of lithium carbonate-containing material and dilute acid leaching according to claim 2, characterized by, An adaptive adjustment mechanism is fitted around the periphery of the stirring shaft. The adaptive adjustment mechanism includes a floating seat fitted around the periphery of the stirring shaft. The floating seat is located at the bottom of the adjustment seat. A float is fixed at the bottom of the floating seat. Multiple connecting rods are fixed at the top of the floating seat by bolts. The top ends of the multiple connecting rods are fixedly connected to the adjustment seat.

6. The apparatus for purifying lithium carbonate of battery grade by magnetic separation of lithium carbonate-containing material and dilute acid leaching according to claim 5, characterized by, An active defoaming mechanism is fixedly provided on the circumferential side of the stirring shaft. The active defoaming mechanism includes a mounting base fixedly provided on the circumferential side of the stirring shaft. The mounting base is located at the bottom of the floating seat. Four connecting seats are arranged in a circular array on the top of the mounting base. Defoaming plates are rotatably connected to the surfaces of the four connecting seats. Four third connecting rods are rotatably connected to the circumferential side of the floating seat. The ends of the four third connecting rods are respectively rotatably connected to the four defoaming plates.

7. The apparatus for purification of battery grade lithium carbonate by dilute acid leaching of magnetic material from lithium carbonate according to claim 2, wherein, An active anti-sticking mechanism is fixedly provided at the top of the inner wall of the feeding cylinder. The active anti-sticking mechanism includes an installation ring fixedly provided at the top of the inner wall of the feeding cylinder, a connecting rope fixedly provided at the bottom of the installation ring, and an eccentric hammer fixedly provided at the bottom of the connecting rope.

8. The apparatus for purifying lithium carbonate of battery grade by magnetic separation of lithium carbonate-containing material and dilute acid leaching according to claim 2, characterized by, The mixing mechanism also includes multiple sets of stirring blades fixed to the side of the stirring shaft, and a cross frame is fixed to the top of the slurry tank. A stirring motor for driving the stirring shaft to rotate is provided on the top of the cross frame.

9. The apparatus for purifying lithium carbonate of battery grade by dilute acid leaching of magnetic material of lithium carbonate as claimed in claim 2 wherein, The top of the slurry reactor is fixed with a sealing plate by bolts. The right side of the slurry reactor is connected to a liquid inlet pipe, and the bottom of the slurry reactor is connected to a discharge pipe. Four support brackets are arranged in a ring array on the periphery of the slurry reactor.

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