Method and device for preparing lithium iron manganese phosphate from waste lithium manganate and waste lithium iron phosphate

Abstract

The invention relates to the technical field of waste battery recovery, and particularly discloses a method for preparing lithium manganese iron phosphate from waste lithium manganate and waste lithium iron phosphate, and the method comprises the following steps: carrying out solid phase mixing on waste lithium manganate LiMn2O4 and lithium phosphate Li3PO4 to obtain a first mixture; phosphoric acid H3PO4 is used as a medium, and sanding equipment is used for sanding the first mixture; filtering the slurry to obtain lithium manganese phosphate LiMnPO4; and measuring the XRD of the lithium manganese phosphate, continuing to use new phosphoric acid as a medium if an impure phase exists, and continuing to sand the mixture and filter the slurry by using the sand mill. According to the automatic trimming mechanism for the exhaust valve box cover part, a new method is provided, the problem of recycling of waste lithium manganate and waste lithium iron phosphate is solved, meanwhile, lithium manganese iron phosphate is generated, waste is recycled, the green and environment-friendly concept advocated by the state is met, and resources and energy are saved.

Description

Technical Field

[0001] The present invention relates to the technical field of waste battery recycling, and in particular to a method and device for preparing lithium iron manganese phosphate from waste lithium manganese oxide and waste lithium iron phosphate. Background Art

[0002] Spinel lithium manganese oxide, a cathode material with three-dimensional lithium-ion channels first developed by Hunter in 1981, boasts low price, high potential, environmental friendliness, and high safety performance, making it widely used in electric bicycles, 3C digital devices, and other fields. Since Goodenough's extensive research, olivine-structured lithium iron phosphate has been widely used in automobiles, energy storage, and other fields due to its long cycle life, high safety, and low cost. Lithium-ion batteries are generally recycled for green use at the end of their lifespan through lithium extraction. However, while lithium has recycling value for lithium manganese oxide and lithium iron phosphate batteries, the extraction of manganese and iron is not economically valuable. Therefore, the market price of used lithium manganese oxide and lithium iron phosphate is generally very low.

[0003] Due to the scarcity of nickel and cobalt, which leads to the high price and low safety of ternary materials, lithium iron manganese phosphate is gradually replacing ternary materials in the automotive battery field. Directly preparing lithium iron manganese phosphate from lithium manganese oxide and waste lithium iron phosphate from waste batteries not only solves the environmental and economic problems of recycling waste lithium manganese oxide and waste lithium iron phosphate, but also produces the lithium iron manganese phosphate required for automotive batteries. Therefore, realizing this technology is a difficult problem that people need to solve. Summary of the Invention

[0004] The object of the present invention is to provide an automatic trimming mechanism for an exhaust valve box cover to solve the above-mentioned deficiencies in the prior art.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing lithium iron manganese phosphate from waste lithium manganese oxide and waste lithium iron phosphate, comprising a sand mill,

[0007] The steps include:

[0008] Solid-phase mixing of waste lithium manganate LiMn2O4 and lithium phosphate Li3PO4 to obtain a first mixture;

[0009] Using phosphoric acid H3PO4 as a medium, sand-milling the first mixture with a sand-milling device;

[0010] Filter the slurry to obtain lithium manganese phosphate LiMnPO4;

[0011] Determine the XRD of the lithium manganese phosphate. If there is an impurity phase, continue to use new phosphoric acid as a medium, continue to sand grind the mixture with a sand mill, and filter the slurry until high-purity lithium manganese phosphate is finally obtained;

[0012] mixing high-purity lithium manganese phosphate with waste lithium iron phosphate and a carbon source to obtain a second mixture;

[0013] The second mixture is solid-phase sintered at 650-750° C. to obtain LMFP / C.

[0014] Furthermore, it is characterized in that the molar ratio of the lithium manganate, lithium phosphate and phosphoric acid satisfies 3:1:5.

[0015] Furthermore, it is characterized in that the carbon source is one or more of sucrose, glucose, fructose, citric acid, phenolic resin, polyvinyl alcohol, polyethylene glycol, starch, carbon black, acetylene black, graphite, graphene, and conductive carbon tubes.

[0016] A device for preparing lithium iron manganese phosphate from waste lithium manganese oxide and waste lithium iron phosphate, and a method for preparing lithium iron manganese phosphate using the waste lithium manganese oxide and waste lithium iron phosphate, characterized in that the sand grinding equipment includes an equipment body, a sand grinding cylinder is provided on the equipment body, a grinding chamber is defined inside the sand grinding cylinder, a rotor is provided in the grinding chamber, the sand grinding cylinder is filled with abrasive, a driving source is provided at the input end of the rotor, and a sand grinding component is provided on the outside of the rotor;

[0017] The sanding component includes a sanding disc and a rotating drum connected to the rotor, and the sanding disc is responsible for driving the abrasive to violently collide and rub in the grinding chamber to sand the first mixture;

[0018] A driving component is provided on the inner side of the sanding disc, and the driving component includes a driving block. The sanding disc is in abutting connection with the driving block. The driving component is responsible for driving the driving block to move when following the rotation of the driving source, so that the multiple sanding discs extend outward intermittently in sequence.

[0019] Furthermore, a reciprocating block is provided at the bottom of the sanding disc, and a first inclined slot and a second inclined slot are respectively provided on the reciprocating block, and the first inclined slot and the second inclined slot correspond to a pair of driving blocks respectively.

[0020] Furthermore, the driving component also includes a first driving bar and a second driving bar which are slidably connected to the outer wall of the rotor, and the ends of the first driving bar and the second driving bar are both provided with a first special-shaped ring. The outside of the rotor is also movably provided with a second special-shaped ring, the first special-shaped ring and the second special-shaped ring are adapted to each other, and the first special-shaped ring moves relative to the second special-shaped ring when working.

[0021] Furthermore, the first special-shaped ring and the second special-shaped ring are provided with crests and troughs. During the rotation of the special-shaped ring, the first drive bar and the second drive bar are caused to reciprocate by contacting with the second special-shaped ring, and the sanding disc is driven to extend outward by the drive block.

[0022] Furthermore, a telescopic rod is provided between the rotor and the reciprocating block, the telescopic rod includes a hollow rod and a piston rod, a strong spring is fixedly connected between the bottom of the piston rod and the inner wall of the hollow rod, a slot is provided on the first drive bar, and the telescopic rod is located inside the slot.

[0023] In the above technical solution, the automatic trimming mechanism for the exhaust valve box cover provided by the present invention has the following beneficial effects:

[0024] This solution provides a new method of the present invention, which solves the problem of recycling waste lithium manganese oxide and waste lithium iron phosphate, and generates lithium manganese iron phosphate at the same time, and recycles the waste, which is in line with the green environmental protection concept advocated by the country, saves resources and energy, and the method of the present invention is simple, effective, low-cost, and has broad market prospects.

[0025] When the sanding disc moves outward, the abrasives squeezed around it are forced to move. The abrasives not only change their original movement trajectory, exerting extrusion and cutting forces on the materials, but also use the changes in the movement trajectory of the abrasives around the sanding disc to indirectly cause the peripheral abrasives to change in movement, so that the peripheral materials can also be subjected to extrusion forces that they did not originally have, making the movement of the abrasives inside the grinding chamber more full and uniform, ultimately improving the sanding efficiency of the abrasives on the materials.

[0026] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0027] This application document provides an overview of various implementations or examples of the technology described in this disclosure, and is not a comprehensive disclosure of the full scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0029] Figure 1 A schematic diagram of the overall external structure provided by an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of the internal structure of a sanding barrel provided by an embodiment of the present invention;

[0031] Figure 3 A schematic diagram of a structure in which a drum and a rotor are separated according to an embodiment of the present invention;

[0032] Figure 4 A schematic diagram of the structure of a driving component provided in an embodiment of the present invention;

[0033] Figure 5 A schematic diagram of the structure below the sanding disc provided in an embodiment of the present invention;

[0034] Figure 6 A schematic structural diagram of a first driving bar and a second driving bar provided in an embodiment of the present invention;

[0035] Figure 7 The embodiment of the present invention provides Figure 6 A schematic diagram of the enlarged structure.

[0036] Description of reference numerals:

[0037] 1. Equipment body; 2. Sanding cylinder; 21. Abrasive discharge cylinder; 22. Feed pipe; 23. Sealing disk; 3. Rotor; 4. Sanding component; 41. Sanding disk; 42. Rotating drum; 5. Driving component; 51. Driving block; 52. Reciprocating block; 53. First chute; 54. Second chute; 55. First driving bar; 56. Second driving bar; 57. First special-shaped ring; 58. Second special-shaped ring; 59. Peak portion; 510. Valley portion. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0039] A method for preparing lithium iron manganese phosphate from waste lithium manganese oxide and waste lithium iron phosphate, comprising a sand mill,

[0040] The steps include:

[0041] Solid-phase mixing of waste lithium manganate LiMn2O4 and lithium phosphate Li3PO4 to obtain a first mixture;

[0042] Using phosphoric acid H3PO4 as a medium, sand-milling the first mixture with a sand-milling device;

[0043] Filter the slurry to obtain lithium manganese phosphate LiMnPO4;

[0044] Determine the XRD of the lithium manganese phosphate. If there is an impurity phase, continue to use new phosphoric acid as a medium, continue to sand grind the mixture with a sand mill, and filter the slurry until high-purity lithium manganese phosphate is finally obtained;

[0045] mixing high-purity lithium manganese phosphate with waste lithium iron phosphate and a carbon source to obtain a second mixture;

[0046] The second mixture is solid-phase sintered at 650-750° C. to obtain LMFP / C.

[0047] The molar ratio of the lithium manganate, lithium phosphate and phosphoric acid satisfies 3:1:5.

[0048] The carbon source is one or more of sucrose, glucose, fructose, citric acid, phenolic resin, polyvinyl alcohol, polyethylene glycol, starch, carbon black, acetylene black, graphite, graphene, and conductive carbon tubes.

[0049] Example 1

[0050] (1) Waste lithium manganate (LiMn2O4) and lithium phosphate (Li3PO4) are solid-phase mixed to obtain a first mixture, wherein the molar ratio of lithium manganate to lithium phosphate satisfies 3:1. (2) Phosphoric acid (H3PO4) is used as a medium and the first mixture is sand-milled in a vertical sand mill, wherein the molar ratio of lithium manganate, lithium phosphate, and phosphoric acid satisfies 3:1:5. The sand mill is vertical, and the zirconium beads of the sand mill have a diameter of 0.5 mm. The sand-milled lithium phosphate can reach a particle size of 0.5 μm. The reaction equation of lithium manganate, lithium phosphate, and phosphoric acid is: 12LiMn2O4 + 4Li3PO4 + 20H3PO4 = 24LiMnPO4 + 30H2O + 9O2↑. (3) Filter the slurry to obtain lithium manganese phosphate LiMnPO4; (4) Measure the XRD of the lithium manganese phosphate. If there is an impurity phase, continue to use new phosphoric acid as a medium, continue to sand grind the mixture with a sand mill and filter the slurry until high-purity lithium manganese phosphate is finally obtained; (5) Mix the high-purity lithium manganese phosphate with waste lithium iron phosphate and sucrose to obtain a second mixture; (6) Solid-phase sinter the second mixture at 650°C to obtain a lithium manganese iron phosphate / carbon composite LMFP / C. The reaction equation of lithium manganese phosphate and lithium iron phosphate is: .

[0051] Testing of the lithium manganese iron phosphate material's particle size revealed a D50 of 1.1 μm. The powder resistance of the lithium manganese iron phosphate material was 92 Ω·cm. The lithium manganese iron phosphate material was assembled into a button-type half-cell for formation testing. The first charge at 0.1C was 156.1 mAh / g, the first discharge at 0.1C was 149.2 mAh / g, and the first efficiency was 95.6%. The gram capacity at 1C was 135.4 mAh / g, and 1C / 0.1C = 90.8%.

[0052] Example 2

[0053] (1) Waste lithium manganate (LiMn2O4) and lithium phosphate (Li3PO4) are solid-phase mixed to obtain a first mixture, wherein the molar ratio of lithium manganate to lithium phosphate satisfies 3:1. (2) Phosphoric acid (H3PO4) is used as a medium and the first mixture is sand-milled in a vertical sand mill, wherein the molar ratio of lithium manganate, lithium phosphate, and phosphoric acid satisfies 3:1:5. The sand mill is horizontal, and the zirconium beads of the sand mill have a diameter of 1 mm. The sand-milled lithium phosphate can reach a particle size of 1 μm. The reaction equation of lithium manganate, lithium phosphate, and phosphoric acid is: 12LiMn2O4 + 4Li3PO4 + 20H3PO4 = 24LiMnPO4 + 30H2O + 9O2↑. (3) Filter the slurry to obtain lithium manganese phosphate LiMnPO4; (4) Measure the XRD of the lithium manganese phosphate. If there is an impurity phase, continue to use new phosphoric acid as a medium, continue to sand grind the mixture with a sand mill and filter the slurry until high-purity lithium manganese phosphate is finally obtained; (5) Mix the high-purity lithium manganese phosphate with waste lithium iron phosphate and sucrose to obtain a second mixture; (6) Solid-phase sinter the second mixture at 750°C to obtain a lithium manganese iron phosphate / carbon composite LMFP / C. The reaction equation of lithium manganese phosphate and lithium iron phosphate is: .

[0054] Testing of the lithium iron phosphate material's particle size revealed a D50 of 1.0 μm. The powder resistance of the lithium iron phosphate material was 98 Ω·cm. Formation testing of a button cell assembled with the lithium iron phosphate material revealed a first charge of 155.8 mAh / g at 0.1C, a first discharge of 148.7 mAh / g at 0.1C, and a first efficiency of 95.4%. The gram capacity at 1C was 134.1 mAh / g, and 1C / 0.1C = 90.2%.

[0055] Comparative Example 1

[0056] (1) Waste lithium manganate LiMn2O4 and lithium phosphate Li3PO4 are solid-phase mixed to obtain a first mixture, wherein the molar ratio of lithium manganate to lithium phosphate satisfies 3:1; (2) Phosphoric acid H3PO4 is added to the first mixture for stirring reaction, wherein the molar ratio of lithium manganate, lithium phosphate and phosphoric acid satisfies 3:1:5; (3) The slurry is filtered and dried; (4) Phosphoric acid is continued to react with the dried product, the slurry is filtered and dried, and the XRD of the solid is measured; (5) The solid is mixed with waste lithium iron phosphate and sucrose to obtain a second mixture; (6) The second mixture is solid-phase sintered at 650°C to obtain a lithium manganese iron phosphate / carbon composite LMFP / C.

[0057] The XRD characteristics of the solid were tested as follows: Figure 1As shown, the solid is a mixture of lithium manganese phosphate and lithium manganate. This is mainly because when a sand mill is not used, lithium manganese phosphate is only generated on the surface of the lithium manganate. The lithium manganese phosphate on the surface then prevents the internal lithium manganate from reacting to generate lithium manganese phosphate. Without the use of a sand mill, even if phosphoric acid is added multiple times, the lithium manganate cannot be completely converted into lithium manganese phosphate, resulting in the final lithium iron phosphate being impure and having poor performance. The particle size of the lithium iron manganese phosphate material was tested and the D50 of the material was 1.1μm. The powder resistance of the tested lithium iron manganese phosphate material was 92Ω·cm. The lithium iron manganese phosphate material was assembled into a button half-cell for formation testing. The first charge at 0.1C was 140.5mAh / g, the first discharge at 0.1C was 121.5mAh / g, the first efficiency was 86.5%, the gram capacity at 1C was 106.7mAh / g, and 1C / 0.1C=87.8%.

[0058] Comparative Example 2

[0059] (1) Waste lithium manganate (LiMn2O4) and lithium phosphate (Li3PO4) are solid-phase mixed to obtain a first mixture, wherein the molar ratio of lithium manganate to lithium phosphate satisfies 3:1. (2) Phosphoric acid (H3PO4) is used as a medium and the first mixture is sand-milled in a vertical sand mill, wherein the molar ratio of lithium manganate, lithium phosphate, and phosphoric acid satisfies 3:1:5. The sand mill is horizontal, and the zirconium beads of the sand mill have a diameter of 1 mm. The sand-milled lithium phosphate can reach a particle size of 1 μm. The reaction equation of lithium manganate, lithium phosphate, and phosphoric acid is: 12LiMn2O4 + 4Li3PO4 + 20H3PO4 = 24LiMnPO4 + 30H2O + 9O2↑. (3) Filter the slurry to obtain lithium manganese phosphate LiMnPO4; (4) Measure the XRD of the lithium manganese phosphate. If there is an impurity phase, continue to use new phosphoric acid as a medium, continue to sand grind the mixture with a sand mill and filter the slurry until high-purity lithium manganese phosphate is finally obtained; (5) Mix the high-purity lithium manganese phosphate with waste lithium iron phosphate and glucose to obtain a second mixture; (6) Solid-phase sinter the second mixture at 800°C to obtain a lithium manganese iron phosphate / carbon composite LMFP / C. The reaction equation of lithium manganese phosphate and lithium iron phosphate is: .

[0060] Testing of the lithium manganese iron phosphate material's particle size revealed a D50 of 1.3 μm. The powder resistance of the lithium manganese iron phosphate material was 153 Ω·cm. The lithium manganese iron phosphate material was assembled into a button-type half-cell for formation testing. The first charge at 0.1C was 154.2 mAh / g, the first discharge at 0.1C was 143.9 mAh / g, and the first efficiency was 93.3%. The gram capacity at 1C was 122.1 mAh / g, and 1C / 0.1C = 84.9%.

[0061] Combining Example 1 and Comparative Example 1, without using a sand mill, even if phosphoric acid is added multiple times to react, lithium manganese oxide cannot be completely converted into lithium manganese phosphate, resulting in the final lithium iron phosphate being impure and having poor performance. Compared with Example 1, the powder resistance of the lithium manganese iron phosphate generated in Comparative Example 1 is high, resulting in a low 0.1C first discharge capacity of the buckling material test, a lower first efficiency, and a significant decrease in 1C capacity. At the same time, 1C / 0.1C shows poor rate performance. Combining Example 2 and Comparative Example 2, after increasing the solid-phase sintering temperature in Comparative Example 2, the particle size D50 increases, resulting in an increase in powder resistance and a decrease in the 1C / 0.1C rate performance of the final material.

[0062] In summary, this solution provides a new method that solves the problem of recycling waste lithium manganese oxide and waste lithium iron phosphate, while generating lithium manganese iron phosphate. The method of the present invention is simple, effective, low-cost, and has broad market prospects.

[0063] See also Figure 1-7 A device for preparing lithium iron manganese phosphate from waste lithium manganese oxide and waste lithium iron phosphate, the sand grinding equipment comprising an equipment body 1, a sand grinding cylinder 2 being provided on the equipment body 1, a grinding cavity being defined inside the sand grinding cylinder 2, a rotor 3 being provided inside the grinding cavity, the sand grinding cylinder 2 being filled with abrasive, a driving source being provided at the input end of the rotor 3, and a sand grinding component 4 being provided outside the rotor 3;

[0064] Specifically, the sanding cylinder 2 further includes an abrasive discharge cylinder 21 disposed on the upper portion thereof, and a feed pipe 22 and a liquid discharge pipe disposed on the outside.

[0065] The sanding component 4 includes a sanding disc 41 and a rotating drum 42 connected to the rotor 3. The sanding disc 41 is responsible for driving the abrasive to violently collide and rub in the grinding chamber to sand the first mixture.

[0066] Specifically, a plurality of movable holes are opened on the rotating drum 42 , and a flexible sealing sleeve is provided between the sanding disc 41 and the movable holes to ensure the sealing performance.

[0067] A driving component 5 is provided on the inner side of the sanding disc 41. The driving component 5 includes a driving block 51. The sanding disc 41 is in contact with the driving block 51. The driving component 5 is responsible for driving the driving block 51 to move when following the rotation of the driving source, so that the multiple sanding discs 41 extend outward intermittently in sequence.

[0068] Abrasives are filled according to actual needs, with an abrasive filling rate of 60-85%. The sanding disc 41 carries the abrasives to perform irregular movements in the grinding chamber. The abrasives repeatedly collide and rub against the materials during the movement, so that the materials eventually reach the specifications of the gaps between the abrasives. In order to ensure the rotation speed of the abrasives and the materials, it is generally not advisable to add too much abrasive, because this will result in too small an internal activity space and too large a resistance, thereby reducing its movement speed. However, when the abrasives are filled less, the collision and friction between the abrasives and the materials are not strong enough, so a driving block 51 is provided, which relies on the driving block 51 to intermittently carry the sanding disc 41 outward, thereby carrying the abrasives to further squeeze and rub, thereby further improving the sanding efficiency of the materials.

[0069] In an embodiment further provided by the present invention, a reciprocating block 52 is provided at the bottom of the sanding disc 41 , and a first inclined groove 53 and a second inclined groove 54 are respectively provided on the reciprocating block 52 , and the first inclined groove 53 and the second inclined groove 54 correspond to a pair of driving blocks 51 respectively.

[0070] Each reciprocating block 52 corresponds to a pair of driving blocks 51, and the pair of driving blocks 51 are respectively located in the first inclined groove 53 and the second inclined groove 54. The pair of driving blocks 51 will only squeeze one of the first inclined groove 53 and the second inclined groove 54 at a time, thereby realizing the outward and inward movement of the reciprocating block 52.

[0071] The driving block 51 is made of hard metal material.

[0072] Furthermore, the driving component 5 also includes a first driving bar 55 and a second driving bar 56 that are slidably connected to the outer wall of the rotor 3. The ends of the first driving bar 55 and the second driving bar 56 are both provided with a first special-shaped ring 57. The outside of the rotor 3 is also movably provided with a second special-shaped ring 58. The first special-shaped ring 57 and the second special-shaped ring 58 are adapted to each other, and the first special-shaped ring 57 moves relative to the second special-shaped ring 58 when working.

[0073] The rotor 3 is provided with a guide groove, in which a guide block is slidably arranged. The inner walls of the first drive bar 55 and the second drive bar 56 are fixedly connected to the guide block and are slidably connected to the outer wall of the rotor through the guide block.

[0074] In an embodiment further provided by the present invention, crest portions 59 and trough portions 510 are provided on the first special-shaped ring 57 and the second special-shaped ring 58. During the rotation of the special-shaped rings, the first drive bar 55 and the second drive bar 56 are caused to move back and forth by interfering with the second special-shaped ring 58, and the sanding disc 41 is driven to extend outward through the drive block 51.

[0075] Specifically, in this case, there are three first drive bars 55 and three second drive bars 56, which are distributed at intervals. The two ends of the three first drive bars 55 or the second drive bars 56 are connected to a first special-shaped ring 57. Initially, the crest of the first special-shaped ring 57 corresponds to the trough of the nearby second special-shaped ring 58, so that when the first special-shaped ring 57 rotates, it can receive resistance and move.

[0076] A sealing disk 23 is provided between the rotating drum 42 and the sanding drum 2, and the sealing disk 23 is fixedly connected to the sanding disk 41. A supporting ring is fixedly connected between the second special-shaped ring 58 and the sealing disk 23. The second special-shaped ring 58 is in a stationary state. During the rotation of the first special-shaped ring 57, it conflicts with the second special-shaped ring 58, so that the first special-shaped ring 57 will reciprocate. During the reciprocating motion of the first special-shaped ring 57, it will also move the driving block 51 back and forth, pressing the corresponding first inclined groove 53 and second inclined groove 54, thereby realizing the intermittent outward extrusion movement of the sanding disk 41, causing the surrounding abrasive to be squeezed, and also changing the original motion trajectory of the surrounding abrasive, causing its motion trajectory to change, effectively avoiding the problem that some materials are subjected to fewer collisions and frictions, and the material is sanded with less uniform force and frequency, and solves the problem that some materials have not been sanded after some materials have been sanded, thereby extending the sanding time.

[0077] The abrasive around the sanding disc 41 rotates periodically, rubbing and slightly squeezing the material. However, when the sanding disc 41 moves outward, the abrasive squeezed around it is forced to move. The abrasive not only changes its original movement trajectory, exerting squeezing and cutting forces on the material, but also utilizes the change in the movement trajectory of the abrasive around the sanding disc 41 to indirectly cause the peripheral abrasive to also experience movement changes, so that the peripheral material can also be subjected to squeezing forces that it originally did not have, making the movement of the abrasive inside the grinding chamber more full and uniform.

[0078] Specifically, a filter screen is further provided at the side end of the sealing disc 23. When the material is sanded to the minimum specification, it can pass through the filter screen into the outside thereof and flow out from the pipe, thereby achieving the effect of sanding the material.

[0079] In the solution further provided by the present invention, a telescopic rod is arranged between the rotor 3 and the reciprocating block 52, and the telescopic rod includes a hollow rod and a piston rod. A strong spring is fixedly connected between the bottom of the piston rod and the inner wall of the hollow rod. A slot is provided on the first drive bar 55, and the telescopic rod is located inside the slot.

[0080] In the present invention, the telescopic rod is provided, which not only helps the sanding disc 41 to perform free telescopic movement, but also can transmit the power of the rotor 3 to the rotating drum 42.

[0081] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A method for preparing lithium iron manganese phosphate from waste lithium manganese oxide and waste lithium iron phosphate, comprising a sand milling device, characterized in that: The steps include: Solid-phase mixing of waste lithium manganate LiMn2O4 and lithium phosphate Li3PO4 to obtain a first mixture; Using phosphoric acid H3PO4 as a medium, sand-milling the first mixture with a sand-milling device; Filter the slurry to obtain lithium manganese phosphate LiMnPO4; Determine the XRD of the lithium manganese phosphate. If there is an impurity phase, continue to use new phosphoric acid as a medium, continue to sand grind the mixture with a sand mill, and filter the slurry until high-purity lithium manganese phosphate is finally obtained; mixing high-purity lithium manganese phosphate with waste lithium iron phosphate and a carbon source to obtain a second mixture; The second mixture is solid-phase sintered at 650-750° C. to obtain LMFP / C.

2. The method for preparing lithium iron manganese phosphate from waste lithium manganate and waste lithium iron phosphate according to claim 1, characterized in that: The molar ratio of the lithium manganate, lithium phosphate and phosphoric acid satisfies 3:1:

5.

3. The method for preparing lithium iron manganese phosphate from waste lithium manganate and waste lithium iron phosphate according to claim 2, characterized in that: The carbon source is one or more of sucrose, glucose, fructose, citric acid, phenolic resin, polyvinyl alcohol, polyethylene glycol, starch, carbon black, acetylene black, graphite, graphene, and conductive carbon tubes.

4. A device for preparing lithium iron manganese phosphate from waste lithium manganese oxide and waste lithium iron phosphate, and a method for preparing lithium iron manganese phosphate from waste lithium manganese oxide and waste lithium iron phosphate according to any one of claims 1 to 3, characterized in that: The sanding equipment includes an equipment body, a sanding cylinder is provided on the equipment body, a grinding chamber is provided inside the sanding cylinder, a rotor is provided in the grinding chamber, the sanding cylinder is filled with abrasive, a driving source is provided at the input end of the rotor, and a sanding component is provided outside the rotor; The sanding component includes a sanding disc and a rotating drum connected to the rotor, and the sanding disc is responsible for driving the abrasive to violently collide and rub in the grinding chamber to sand the first mixture; A driving component is provided on the inner side of the sanding disc, and the driving component includes a driving block. The sanding disc is in abutting connection with the driving block. The driving component is responsible for driving the driving block to move when following the rotation of the driving source, so that the multiple sanding discs extend outward intermittently in sequence.

5. The automatic trimming mechanism for the exhaust valve box cover according to claim 4, characterized in that: A reciprocating block is provided at the bottom of the sanding disc. A first inclined slot and a second inclined slot are respectively provided on the reciprocating block. The first inclined slot and the second inclined slot correspond to a pair of driving blocks respectively.

6. The automatic trimming mechanism for the exhaust valve box cover according to claim 5, characterized in that: The driving component also includes a first driving bar and a second driving bar slidably connected to the outer wall of the rotor, and the ends of the first driving bar and the second driving bar are both provided with a first special-shaped ring. The outside of the rotor is also movably provided with a second special-shaped ring, the first special-shaped ring and the second special-shaped ring are adapted to each other, and the first special-shaped ring moves relative to the second special-shaped ring when working.

7. The automatic trimming mechanism for the exhaust valve box cover according to claim 6, characterized in that: The first special-shaped ring and the second special-shaped ring are provided with wave crests and wave troughs. During the rotation of the special-shaped ring, the first driving bar and the second driving bar are moved back and forth by contacting with the second special-shaped ring, and the sanding disc is driven to extend outward by the driving block.

8. The automatic trimming mechanism for the exhaust valve box cover according to claim 7, characterized in that: A telescopic rod is provided between the rotor and the reciprocating block. The telescopic rod includes a hollow rod and a piston rod. A strong spring is fixedly connected between the bottom of the piston rod and the inner wall of the hollow rod. A slot is provided on the first driving bar, and the telescopic rod is located inside the slot.

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