Method for combined recovery of waste lithium iron phosphate batteries and ternary lithium batteries

Abstract

The invention provides a method for combined recovery of waste lithium iron phosphate batteries and ternary lithium batteries, which comprises the following steps: carrying out first anaerobic roasting on a battery pack with a safety valve opened to obtain a roasted battery pack; taking out the single battery cells in the roasted battery pack, and crushing and screening the single battery cells to obtain a copper-aluminum product on the screen and battery powder under the screen; carrying out second anaerobic roasting on the battery powder to obtain roasted battery powder; carrying out first magnetic separation on the roasted battery powder to obtain a first magnetic material and a first non-magnetic material; performing lithium leaching and solid-liquid separation on the first magnetic material in sequence to obtain a lithium-containing solution and a nickel-cobalt-manganese-containing solid phase; mixing a reducing agent and the first non-magnetic material, and performing third roasting to obtain a third roasted product; performing second magnetic separation on the third roasted product to obtain a second magnetic material and a second non-magnetic material; performing acid leaching purification and solid-liquid separation on the second non-magnetic material to obtain a solution containing lithium and phosphorus and a graphite product; and efficient recovery of the waste batteries is realized.

Description

Technical Field

[0001] This invention relates to the field of waste battery recycling technology, and in particular to a method for the combined recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Background Technology

[0002] The advantages of lithium-ion batteries, such as high energy density, high voltage, good cycle performance, long life, low self-discharge, and environmental friendliness, have made them one of the important driving forces for the development of new energy, and they are widely used in important fields such as electric vehicles, energy storage systems, and smart grids.

[0003] Currently, lithium-ion batteries can be classified into ternary lithium batteries, lithium iron phosphate batteries, lithium cobalt oxide batteries, and lithium manganese oxide batteries based on their cathode materials. To meet market demands for increased range and safety in new energy vehicles, a small number of ternary lithium battery cells are added to lithium iron phosphate battery packs to enhance the pack's energy storage capabilities. However, when these packs are no longer usable, it is difficult to distinguish the types of individual cells within the pack, increasing the challenge of subsequent battery recycling. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries, so as to efficiently recover valuable materials directly from battery packs containing both ternary and lithium iron phosphate battery cells, with broad application prospects.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] This invention provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries, the method comprising the following steps:

[0007] (1) The battery pack with the safety valve opened is subjected to the first oxygen-free calcination to obtain the calcined battery pack.

[0008] (2) Take out the battery cells from the calcined battery pack, and crush and screen the battery cells. Copper and aluminum products are obtained on the sieve, and battery powder is obtained on the underside of the sieve.

[0009] (3) The battery powder is subjected to a second oxygen-free calcination to obtain calcined battery powder.

[0010] (4) The calcined battery powder is subjected to a first magnetic separation to obtain a first magnetic material containing nickel, cobalt and manganese and a first non-magnetic material containing lithium iron phosphate.

[0011] (5) The first magnetic material is sequentially subjected to lithium immersion and solid-liquid separation to obtain a lithium-containing solution and a nickel-cobalt-manganese solid phase.

[0012] (6) The reducing agent and the first non-magnetic material are mixed and then subjected to a third calcination to obtain a third calcined product. The third calcined product is subjected to a second magnetic separation to obtain a second magnetic material containing iron and a second non-magnetic material. The second non-magnetic material is purified by acid leaching and solid-liquid separation to obtain a lithium-phosphorus solution and a graphite product.

[0013] There is no sequential relationship between steps (5) and (6).

[0014] The method for joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries provided by this invention has the following advantages:

[0015] (1) For battery packs containing both lithium iron phosphate battery cells and ternary lithium battery cells, the method provided by the present invention does not require identification of the type of battery cells and can be directly processed synchronously.

[0016] (2) The method of the present invention can process lithium iron phosphate battery packs and ternary lithium battery packs at the same time, so that there is no need to set up two production lines in industrial applications, saving overall equipment costs and production costs.

[0017] (3) In the second oxygen-free roasting, lithium iron phosphate cathode material and graphite material will simultaneously promote the reduction of ternary cathode material and enhance the formation of nickel and cobalt elements, which is beneficial to the subsequent recovery of nickel and cobalt by magnetic separation. The two achieve a synergistic effect in the recovery process.

[0018] (4) Before extracting the battery cell, the present invention performs a first oxygen-free roasting, which directly removes organic matter such as binders in the battery pack, making it easier to recover valuable elements in the battery powder after disassembly.

[0019] This invention involves sequentially subjecting the battery to a first oxygen-free roasting, core extraction, crushing, sieving, a second oxygen-free roasting, and a first magnetic separation to obtain a first magnetic material containing nickel, cobalt, and manganese, and a first non-magnetic material containing lithium iron phosphate. The first magnetic material is then subjected to lithium leaching and filtration to recover the lithium-containing solution and the nickel, cobalt, and manganese-containing solid phase. The first non-magnetic material is then purified through a third roasting, a second magnetic separation, and acid leaching to recover the lithium-phosphate solution and graphite product, achieving comprehensive recycling of both battery types and demonstrating broad application prospects.

[0020] The equation for the first oxygen-free calcination in this invention is as follows: 2Li(Ni x Co y Mn 1-x-yO2 + C = Li2O + 2xNiO + 2yCoO + 2(1-xy)MnO + CO. The value of x is in the range of 0 < x < 1, for example, 0.01, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, or 0.9; the value of y is in the range of 0 < y < 1, for example, 0.01, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, or 0.9.

[0021] The equations for the second anaerobic roasting process are shown below:

[0022] 2NiO + C = 2Ni + CO2

[0023] 2CoO+C=2Co+CO2.

[0024] The equations for the events occurring during the third roasting are shown below:

[0025] 6LiFePO4+3C=6Fe+2P2O5+2Li3PO4+3CO2

[0026] Preferably, the battery pack manufacturing process for opening the safety valve in step (1) includes: using a puncturing device to open the safety valve on the individual cell inside the battery pack.

[0027] Preferably, the temperature of the first oxygen-free calcination in step (1) is 380~550℃, for example, it can be 380℃, 390℃, 410℃, 430℃, 450℃, 475℃, 490℃, 510℃, 530℃ or 550℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] The present invention preferably controls the temperature of the first oxygen-free calcination within the above-mentioned range, which can better improve the removal rate of structural adhesive, binder, separator and electrolyte, improve the powder removal rate of battery powder, thereby increasing the recovery rate of each element, and better balance energy consumption.

[0029] Preferably, the atmosphere for the first oxygen-free roasting includes a nitrogen atmosphere.

[0030] Preferably, the first anaerobic calcination time is 1 to 3 hours, for example, it can be 1 hour, 1.3 hours, 1.5 hours, 1.7 hours, 1.9 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] Preferably, the battery pack includes any one or a combination of at least two of the following: a pure waste lithium iron phosphate battery pack, a pure waste ternary lithium-ion battery pack, or a battery pack consisting of waste lithium iron phosphate battery cells and waste ternary lithium-ion battery cells.

[0032] Preferably, the step (2) of removing the battery cells from the calcined battery pack includes: cutting the calcined battery pack to obtain the battery casing product and the battery cells.

[0033] Preferably, the crushing device includes a hammer crusher.

[0034] Preferably, the sieving includes sequentially performing a first mesh size sieving, a second mesh size sieving, and a third mesh size sieving. The mesh size of the first mesh size sieving is less than the mesh size of the second mesh size sieving, which in turn is less than the mesh size of the third mesh size sieving.

[0035] Preferably, copper and aluminum products are obtained from the first, second, and third mesh sieves.

[0036] Preferably, the battery powder is obtained from the undersize of the third mesh sieve.

[0037] Preferably, the temperature of the second oxygen-free calcination in step (3) is 600~750℃, for example, it can be 600℃, 610℃, 630℃, 650℃, 660℃, 680℃, 700℃, 710℃, 730℃ or 750℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] The present invention preferably controls the temperature of the second oxygen-free calcination within the above-mentioned range, which can better improve the recovery rate of nickel, cobalt and manganese, while taking into account energy consumption and graphite recovery rate.

[0039] Preferably, the atmosphere for the second oxygen-free roasting includes a nitrogen atmosphere.

[0040] Preferably, the second anaerobic calcination time is 1 to 3 hours, for example, it can be 1 hour, 1.3 hours, 1.5 hours, 1.7 hours, 1.9 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] Preferably, the magnetic field strength of the first magnetic separation in step (4) is 0.4~0.6T, for example, it can be 0.4T, 0.43T, 0.45T, 0.47T, 0.49T, 0.52T, 0.54T, 0.56T, 0.58T or 0.6T, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the first magnetic separation is performed using a dry magnetic separator.

[0043] Preferably, the lithium impregnation in step (5) includes: mixing a first magnetic material, water and acid, and then stirring the resulting mixture for lithium impregnation.

[0044] Preferably, the solid-liquid ratio of the first magnetic material to water is 1:(2~5)g / mL, for example, it can be 1:2g / mL, 1:2.4g / mL, 1:2.7g / mL, 1:3g / mL, 1:3.4g / mL, 3.7:1g / mL, 4:1g / mL, 4.4:1g / mL, 1:4.7g / mL or 1:5g / mL, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0045] Preferably, the acid includes sulfuric acid.

[0046] Preferably, the pH range of the mixture is 4 to 6, for example, it can be 4, 4.3, 4.5, 4.7, 4.9, 5.2, 5.4, 5.6, 5.8 or 6, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Preferably, the temperature of the stirring process is 25~60℃, for example, it can be 25℃, 29℃, 33℃, 37℃, 41℃, 45℃, 49℃, 53℃, 57℃ or 60℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] Preferably, the stirring speed is 400~600 r / min.

[0049] Preferably, the stirring time is 30 to 90 minutes, for example, it can be 30 minutes, 37 minutes, 44 minutes, 50 minutes, 57 minutes, 64 minutes, 70 minutes, 77 minutes, 84 minutes or 90 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Preferably, step (5) further includes: leaching the nickel-cobalt-manganese solid phase.

[0051] Preferably, the leaching process includes: mixing a sulfuric acid solution and the nickel-cobalt-manganese solid phase, followed by stirring and solid-liquid separation to obtain a nickel-cobalt-manganese sulfate solution and leaching residue.

[0052] Preferably, the molar concentration of the sulfuric acid solution is 1.5~3 mol / L, for example, it can be 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.5 mol / L, 2.7 mol / L, 2.9 mol / L or 3 mol / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0053] Preferably, the solid-liquid ratio of the sulfuric acid solution to the nickel-cobalt-manganese solid phase is 1:(2~4) g / mL, for example, it can be 1:2 g / mL, 1:2.2 g / mL, 1:2.3 g / mL, 1:2.4 g / mL, 1:2.5 g / mL, 1:2.8 g / mL, 1:2.9 g / mL, 1:3.0 g / mL, 1:3.2 g / mL, 1:3.3 g / mL, 1:3.5 g / mL, 1:3.8 g / mL or 1:4 g / mL, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0054] Preferably, the temperature of the stirring reaction is 70~90℃, for example, it can be 70℃, 73℃, 75℃, 77℃, 79℃, 82℃, 84℃, 86℃, 88℃ or 90℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0055] Preferably, the stirring speed is 400~600 r / min, for example, it can be 400 r / min, 420 r / min, 440 r / min, 460 r / min, 480 r / min, 510 r / min, 530 r / min, 550 r / min, 570 r / min or 600 r / min, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0056] Preferably, the duration of the stirring reaction is 0.5 to 2 hours, for example, it can be 0.5 hours, 0.7 hours, 0.9 hours, 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, 1.7 hours, 1.9 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] Preferably, the reducing agent in step (6) includes asphalt and / or needle coke.

[0058] Preferably, the mass ratio of the reducing agent to the first non-magnetic material is (0.4~0.7):1, for example, it can be 0.4:1, 0.44:1, 0.47:1, 0.5:1, 0.54:1, 0.57:1, 0.6:1, 0.64:1, 0.67:1 or 0.7:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] Preferably, the reducing agent comprises asphalt and needle coke, wherein the mass ratio of the asphalt to needle coke is (2~4):1, for example, it can be 2:1, 2.3:1, 2.5:1, 2.7:1, 2.9:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1 or 4:1, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0060] Preferably, the third firing is carried out in a rotary kiln.

[0061] Preferably, the temperature of the third roasting is 950~1450℃, for example, it can be 950℃, 1006℃, 1062℃, 1117℃, 1173℃, 1228℃, 1284℃, 1339℃, 1395℃ or 1450℃, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0062] The present invention preferably controls the temperature of the third calcination within the above-mentioned range, which can improve the reaction degree of LiFePO4 decomposition into Fe and Fe2P and increase the recovery rate of Fe and P. However, if the temperature is too high, the loss rate of P and Li elements will increase, resulting in a decrease in the recovery rate of Li and P. If the temperature is too low, the decomposition degree of LiFePO4 will be low, and the Fe element will be difficult to be converted into Fe element or Fe2P and other strongly magnetic substances, thereby reducing the recovery rate of iron.

[0063] Preferably, the atmosphere for the third roasting includes a nitrogen atmosphere.

[0064] Preferably, the third calcination time is 0.5 to 2 hours, for example, it can be 0.5 hours, 0.7 hours, 0.9 hours, 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, 1.7 hours, 1.9 hours or 2 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0065] Preferably, leaching residue is also added to the mixing process in step (6).

[0066] Preferably, the mass ratio of the leaching residue to the total mass of the first non-magnetic material and the reducing agent is (0.1~1):100, for example, it can be 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100 or 1:100, etc.

[0067] Preferably, the second magnetic separator in step (6) is a wet magnetic separator.

[0068] Preferably, the magnetic field strength of the second magnetic separation is 0.8~1.2T, for example, it can be 0.8T, 0.85T, 0.89T, 0.94T, 0.98T, 1.03T, 1.07T, 1.12T, 1.16T or 1.2T, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0069] Preferably, the second non-magnetic material includes graphite, phosphorus compounds, and lithium compounds.

[0070] Preferably, the acid leaching purification in step (6) includes: mixing a second non-magnetic material, acid solution and hydrogen peroxide for acid leaching.

[0071] Preferably, the acid solution includes sulfuric acid.

[0072] Preferably, the concentration of sulfuric acid in the acid leaching and purification is 2~4 mol / L, for example, it can be 2 mol / L, 2.3 mol / L, 2.5 mol / L, 2.7 mol / L, 2.9 mol / L, 3.2 mol / L, 3.4 mol / L, 3.6 mol / L, 3.8 mol / L or 4 mol / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0073] Preferably, the solid-liquid ratio of the acid solution to the second non-magnetic material is 1:(1~3)g / mL, for example, it can be 1:1g / mL, 1:1.3g / mL, 1.5g / mL, 1:1.7g / mL, 1:1.9g / mL, 1:2.2g / mL, 1:2.4g / mL, 1:2.6g / mL, 1:2.8g / mL or 1:3g / mL, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0074] Preferably, the amount of hydrogen peroxide added is 1 to 1.5 times the amount of metal in the second non-magnetic material, for example, it can be 1.0 times, 1.06 times, 1.12 times, 1.17 times, 1.23 times, 1.28 times, 1.34 times, 1.39 times, 1.45 times or 1.5 times, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0075] Preferably, the acid leaching and purification temperature is 70~90℃, for example, it can be 70℃, 73℃, 75℃, 77℃, 79℃, 82℃, 84℃, 86℃, 88℃ or 90℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0076] Preferably, the acid leaching and purification time is 1 to 3 hours, for example, it can be 1 hour, 1.3 hours, 1.5 hours, 1.7 hours, 1.9 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0077] The present invention does not impose any special restrictions on the solid-liquid separation in the above process. Any device and method known to those skilled in the art for solid-liquid separation can be used. It can also be adjusted according to the actual process. For example, it can be filtration, centrifugation or sedimentation separation, or a combination of different methods.

[0078] The present invention does not impose any special restrictions on the drying process described above. Any device and method known to those skilled in the art for drying can be used. Adjustments can also be made according to the actual process. For example, it can be air drying, vacuum drying, oven drying, or freeze drying, or a combination of different methods.

[0079] The present invention does not impose any special restrictions on the pulverization process described above. Any device and method known to those skilled in the art for pulverization can be used. Adjustments can also be made according to the actual process. For example, it can be grinding, extrusion pulverization, splitting pulverization, or impact pulverization, or a combination of different methods.

[0080] As a preferred embodiment of the present invention, the recycling method includes the following steps:

[0081] (1) Use a punching device to open the safety valve on the individual cell in the battery pack, and then bake the battery pack with the safety valve open in a nitrogen atmosphere at 380~550℃ for 1~3 hours to obtain the baked battery pack; the battery pack includes any one or at least two of the following: waste lithium iron phosphate battery pack, waste ternary lithium-ion battery pack, or a battery pack composed of waste lithium iron phosphate battery cells and waste ternary lithium-ion battery cells.

[0082] (2) The calcined battery is cut to obtain the battery shell product and the battery cell. The battery cell is crushed with a hammer crusher. The crushed material is then screened in sequence with a first mesh size, a second mesh size, and a third mesh size. The mesh size of the first mesh size screening is less than that of the second mesh size screening and the mesh size of the third mesh size screening. Copper and aluminum products are obtained from the oversize of the first mesh size screening, the second mesh size screening and the undersize of the third mesh size screening. Battery powder is obtained from the undersize of the third mesh size screening.

[0083] (3) The battery powder is calcined at 600~750℃ in a nitrogen atmosphere for 1~3 hours to obtain calcined battery powder.

[0084] (4) The calcined battery powder is subjected to a first magnetic separation by a dry magnetic separator under a magnetic field strength of 0.4~0.6T to obtain a first magnetic material containing nickel, cobalt and manganese and a first non-magnetic material containing lithium iron phosphate.

[0085] (5) Mix the first magnetic material and water at a solid-liquid ratio of 1:(2~5)g / mL, then add sulfuric acid to adjust the pH to 4~6. The resulting mixture is stirred at 25~60℃ and 400~600r / min for 30~90min to leach lithium, and then the solid and liquid are separated to obtain a lithium-containing solution and a nickel-cobalt-manganese solid phase.

[0086] Mix 1.5-3 mol / L sulfuric acid solution and nickel-cobalt-manganese solid phase at a solid-liquid ratio of 1:(2-4) g / mL, and stir at 70-90℃ and 400-600 r / min for 0.5-2 h. Then, separate the solid and liquid phases to obtain nickel-cobalt-manganese sulfate solution and leaching residue.

[0087] (6) The reducing agent and the first non-magnetic material are mixed according to the mass ratio of reducing agent to the first non-magnetic material (0.4~0.7):1, and the mass ratio of leaching residue to the total mass of the first non-magnetic material and reducing agent is (0.1~1):100. The reducing agent, the leaching residue and the first non-magnetic material in step (4) are then roasted in a rotary kiln at 950~1450℃ under a nitrogen atmosphere for 0.5~2h to obtain the third roasting product. The reducing agent includes pitch and needle coke, and the mass ratio of pitch and needle coke is (2~4):1.

[0088] The third roasting product is subjected to a second magnetic separation by a wet magnetic separator under a magnetic field strength of 0.8~1.2T to obtain a second magnetic material containing iron and a second non-magnetic material.

[0089] The solid-liquid ratio of sulfuric acid solution to the second non-magnetic material is 1:(1~3)g / mL. The second non-magnetic material and 2~4mol / L sulfuric acid solution are mixed. Then, hydrogen peroxide is added at 1~1.5 times the amount of metal in the second non-magnetic material. The mixture is then purified by acid leaching at 70~90℃ for 1~3h. Finally, solid-liquid separation is performed to obtain a lithium-phosphorus solution and graphite product.

[0090] There is no sequential relationship between steps (5) and (6).

[0091] Compared with the prior art, the present invention has at least the following beneficial effects:

[0092] (1) The method for combined recycling of waste lithium iron phosphate batteries and ternary lithium batteries provided by the present invention can directly realize the combined recycling of lithium iron phosphate batteries and ternary lithium batteries without distinguishing the product properties or building two separate recycling production lines, and the recycling cost can be greatly reduced.

[0093] (2) The method for joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries provided by the present invention can promote the reduction of ternary cathode materials during the first oxygen-free roasting process, thereby enhancing the generation of nickel and cobalt elements, so as to achieve the separation and recycling of nickel and cobalt during the first magnetic separation process.

[0094] (3) The method for joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries provided by the present invention can reduce the amount of acid used in the wet leaching of lithium iron phosphate batteries and reduce production costs by separating and recycling iron-containing substances in waste batteries through magnetic separation.

[0095] (4) The method for joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries provided by the present invention can simultaneously achieve the repair and recycling of graphite products in the lithium iron phosphate decomposition step, and the obtained graphite products can be directly used as battery negative electrodes. Attached Figure Description

[0096] Figure 1 This is a schematic flowchart of the method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries provided by the present invention. Detailed Implementation

[0097] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0098] It should be understood that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0099] As a specific embodiment of the present invention, a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries is provided, such as... Figure 1 As shown, the method includes the following steps:

[0100] (1) Use a punching device to open the safety valve on the individual cell in the battery pack, and perform a first oxygen-free roasting on the battery pack with the safety valve opened to obtain a roasted battery pack. The flue gas generated by the first oxygen-free roasting is treated. The battery pack includes waste lithium iron phosphate battery cells and waste ternary lithium-ion battery cells.

[0101] (2) The calcined battery is cut to obtain the battery shell product and the battery cell. The battery cell is crushed with a hammer crusher. The crushed material is then screened. The copper and aluminum products are obtained on the screen and the battery powder is obtained on the underside of the screen.

[0102] (3) The battery powder is subjected to a second oxygen-free calcination to obtain calcined battery powder.

[0103] (4) The calcined battery powder is subjected to a first magnetic separation to obtain a first magnetic material containing nickel, cobalt and manganese and a first non-magnetic material containing lithium iron phosphate.

[0104] (5) Mix the first magnetic material and water, then add sulfuric acid to adjust the pH. The resulting mixture is stirred to leach lithium, and then solid-liquid separation is performed to obtain a lithium-containing solution and a nickel-cobalt-manganese-containing solid phase.

[0105] A mixed sulfuric acid solution and a nickel-cobalt-manganese solid phase were reacted by stirring and then separated into solid and liquid phases to obtain a nickel-cobalt-manganese sulfate solution and a leaching residue.

[0106] (6) Mix the leaching residue, reducing agent and the first non-magnetic material, and then roast them for the third time in a rotary kiln to obtain the third roasting product; wherein the reducing agent includes pitch and needle coke.

[0107] The third roasting product is subjected to a second magnetic separation to obtain a second magnetic material containing iron and a second non-magnetic material.

[0108] The second non-magnetic material and sulfuric acid solution are mixed, and hydrogen peroxide is added for acid leaching purification. Then, solid-liquid separation is performed to obtain a lithium-phosphorus solution and graphite product.

[0109] There is no sequential relationship between steps (5) and (6).

[0110] The following detailed description uses specific embodiments.

[0111] Example 1

[0112] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries, the method comprising the following steps:

[0113] (1) Use a punching device to open the safety valve on the individual cell in the battery pack, and then bake the battery pack with the safety valve open in a nitrogen atmosphere at 450°C for 2 hours to obtain the baked battery pack. The flue gas generated by the first oxygen-free baking is treated. The battery pack includes waste lithium iron phosphate battery cells and waste ternary lithium-ion battery cells, of which the number of waste ternary lithium-ion battery cells accounts for 20%.

[0114] (2) The calcined battery is cut to obtain the battery shell product and the battery cell. The battery cell is crushed with a hammer crusher. The crushed material is then screened in sequence with a first mesh size of 3, a second mesh size of 20, and a third mesh size of 80. Copper and aluminum products are obtained from the upper screens of the first, second, and third mesh sizes, and battery powder is obtained from the lower screen of the third mesh size.

[0115] (3) The battery powder is calcined at 700°C in a nitrogen atmosphere for 2 hours to obtain calcined battery powder.

[0116] (4) The calcined battery powder is subjected to a first magnetic separation by a dry magnetic separator under a magnetic field strength of 0.5T to obtain a first magnetic material containing nickel, cobalt and manganese and a first non-magnetic material containing lithium iron phosphate. The first non-magnetic material also contains graphite.

[0117] (5) Mix the first magnetic material and water at a solid-liquid ratio of 1:3 g / mL, then add sulfuric acid to adjust the pH to 5. The resulting mixture is stirred at 50°C and 500 r / min for 60 min to leach lithium, and then filtered to obtain a lithium-containing solution and a nickel-cobalt-manganese solid phase.

[0118] A 2.5 mol / L sulfuric acid solution and a nickel-cobalt-manganese solid phase were mixed at a solid-liquid ratio of 1:3 g / mL and stirred at 80℃ and 500 r / min for 1 h. The mixture was then filtered to obtain a nickel-cobalt-manganese sulfate solution and a leaching residue.

[0119] (6) The reducing agent, the leaching residue and the first non-magnetic material are mixed according to a mass ratio of 4:7 and a mass ratio of 0.5:100 of the leaching residue to the total mass of the first non-magnetic material and the reducing agent. The mixture is then calcined in a rotary kiln at 1100°C under a nitrogen atmosphere for 1 hour to obtain the third calcined product. The reducing agent includes pitch and needle coke, and the mass ratio of the pitch and needle coke is 3:1.

[0120] The third roasting product is subjected to a second magnetic separation by a wet magnetic separator under a magnetic field strength of 1.0T to obtain a second magnetic material containing iron and a second non-magnetic material.

[0121] The second non-magnetic material and 3 mol / L sulfuric acid solution were mixed with sulfuric acid solution at a solid-liquid ratio of 1:2 g / mL. Then, hydrogen peroxide was added at 1.2 times the amount of metal in the second non-magnetic material. The mixture was purified by acid leaching at 80℃ for 2 hours, then filtered. The solid phase was dried to obtain a lithium-phosphorus solution and graphite product.

[0122] There is no sequential relationship between steps (5) and (6).

[0123] Example 2

[0124] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries, the method comprising the following steps:

[0125] (1) Use a punching device to open the safety valve on the individual cell in the battery pack, and then bake the battery pack with the safety valve open in a nitrogen atmosphere at 380°C for 3 hours to obtain the baked battery pack. The flue gas generated by the first oxygen-free baking is treated. The battery pack includes waste lithium iron phosphate battery cells and waste ternary lithium-ion battery cells, of which the number of waste ternary lithium-ion battery cells accounts for 30%.

[0126] (2) The calcined battery is cut to obtain the battery shell product and the battery cell. The battery cell is crushed with a hammer crusher. The crushed material is then screened in sequence with a first mesh size of 3, a second mesh size of 20, and a third mesh size of 80. Copper and aluminum products are obtained from the upper screens of the first, second, and third mesh sizes, and battery powder is obtained from the lower screen of the third mesh size.

[0127] (3) The battery powder is calcined at 600°C in a nitrogen atmosphere for 3 hours to obtain calcined battery powder.

[0128] (4) The calcined battery powder is subjected to a first magnetic separation by a dry magnetic separator under a magnetic field strength of 0.4T to obtain a first magnetic material containing nickel, cobalt and manganese and a first non-magnetic material containing lithium iron phosphate. The first non-magnetic material also contains graphite.

[0129] (5) Mix the first magnetic material and water at a solid-liquid ratio of 1:5 g / mL, then add sulfuric acid to adjust the pH to 6. The resulting mixture is stirred at 60°C and 400 r / min for 30 min for lithium leaching, and then filtered to obtain a lithium-containing solution and a nickel-cobalt-manganese solid phase.

[0130] Mix 1.5 mol / L sulfuric acid solution and nickel-cobalt-manganese solid phase at a solid-liquid ratio of 1:2 g / mL, then filter, and stir at 70℃ and 400 r / min for 2 h to obtain nickel-cobalt-manganese sulfate solution and leaching residue.

[0131] (6) The reducing agent, the leaching residue, and the first non-magnetic material are mixed according to a mass ratio of 0.4:1 for the reducing agent and 0.1:100 for the total mass of the leaching residue and the first non-magnetic material, and then calcined in a rotary kiln at 1450°C under a nitrogen atmosphere for 0.5 h to obtain the third calcined product; wherein the reducing agent includes pitch and needle coke, and the mass ratio of the pitch and needle coke is 2:1.

[0132] The third roasting product is subjected to a second magnetic separation by a wet magnetic separator under a magnetic field strength of 1.2T to obtain a second magnetic material containing iron and a second non-magnetic material.

[0133] The solid-liquid ratio of sulfuric acid solution to the second non-magnetic material was 1:3 g / mL. The second non-magnetic material and 4 mol / L sulfuric acid solution were mixed, and hydrogen peroxide was added at 1.0 times the amount of metal in the second non-magnetic material. The mixture was then purified by acid leaching at 70℃ for 3 hours. After filtration, the solid phase was dried to obtain a lithium-phosphorus solution and graphite product.

[0134] There is no sequential relationship between steps (5) and (6).

[0135] Example 3

[0136] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries, the method comprising the following steps:

[0137] (1) Use a punching device to open the safety valve on the individual cell in the battery pack, and then bake the battery pack with the safety valve open in a nitrogen atmosphere at 550°C for 1 hour to obtain the baked battery pack. The flue gas generated by the first oxygen-free baking is treated. The battery pack includes waste lithium iron phosphate battery cells and waste ternary lithium-ion battery cells, wherein the ternary material accounts for 40% of the total amount in the battery pack.

[0138] (2) The calcined battery is cut to obtain the battery shell product and the battery cell. The battery cell is crushed with a hammer crusher. The crushed material is then screened in sequence with a first mesh size of 3, a second mesh size of 20, and a third mesh size of 80. Copper and aluminum products are obtained from the upper screens of the first, second, and third mesh sizes, and battery powder is obtained from the lower screen of the third mesh size.

[0139] (3) The battery powder is calcined at 750°C in a nitrogen atmosphere for 1 hour to obtain calcined battery powder.

[0140] (4) The calcined battery powder is subjected to a first magnetic separation by a dry magnetic separator under a magnetic field strength of 0.6T to obtain a first magnetic material containing nickel, cobalt and manganese and a first non-magnetic material containing lithium iron phosphate. The first non-magnetic material also contains graphite.

[0141] (5) Mix the first magnetic material and water at a liquid-solid ratio of 1:2 g / mL, then add sulfuric acid to adjust the pH to 4. The resulting mixture is stirred at 25°C and 600 r / min for 90 min to leach lithium, and then filtered to obtain a lithium-containing solution and a nickel-cobalt-manganese solid phase.

[0142] A 3 mol / L sulfuric acid solution and a nickel-cobalt-manganese solid phase were mixed at a solid-liquid ratio of 1:4 g / mL and stirred at 90℃ and 600 r / min for 0.5 h. The mixture was then filtered to obtain a nickel-cobalt-manganese sulfate solution and a leaching residue.

[0143] (6) The reducing agent and the first non-magnetic material are mixed according to a mass ratio of 0.7:1 and a mass ratio of 1:100 between the leaching residue and the total mass of the first non-magnetic material and the reducing agent. The mixture is then calcined in a rotary kiln at 950°C under a nitrogen atmosphere for 2 hours to obtain the third calcined product. The reducing agent includes pitch and needle coke, and the mass ratio of the pitch and needle coke is 4:1.

[0144] The third roasting product is subjected to a second magnetic separation by a wet magnetic separator under a magnetic field strength of 0.8T to obtain a second magnetic material containing iron and a second non-magnetic material.

[0145] The second non-magnetic material and 2 mol / L sulfuric acid solution were mixed with sulfuric acid solution at a solid-liquid ratio of 1:1 g / mL. Then, hydrogen peroxide was added at a ratio of 1.5 times the amount of metal in the second non-magnetic material. The mixture was purified by acid leaching at 90℃ for 1 hour, then filtered. The solid phase was dried to obtain a lithium-phosphorus solution and graphite product.

[0146] There is no sequential relationship between steps (5) and (6).

[0147] Example 4

[0148] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the first anaerobic roasting temperature of 380°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0149] Example 5

[0150] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the first anaerobic roasting temperature of 550°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0151] Example 6

[0152] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the first anaerobic roasting temperature of 600°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0153] Example 7

[0154] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the first anaerobic roasting temperature of 300°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0155] Example 8

[0156] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the second anaerobic roasting temperature of 600°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0157] Example 9

[0158] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the second anaerobic roasting temperature of 750°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0159] Example 10

[0160] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the second anaerobic roasting temperature of 500°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0161] Example 11

[0162] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the second anaerobic roasting temperature of 800°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0163] Example 12

[0164] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the third roasting temperature of 950°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0165] Example 13

[0166] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the third roasting temperature of 1250°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0167] Example 14

[0168] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the third roasting temperature of 1500℃, the method is the same as that in Embodiment 1, and will not be repeated here.

[0169] Example 15

[0170] This embodiment provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the third roasting temperature of 800°C, the method is the same as that in Embodiment 1, and will not be repeated here.

[0171] Comparative Example 1

[0172] This comparative example provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the absence of the first anaerobic roasting, the method is the same as that in Example 1, and will not be repeated here.

[0173] Comparative Example 2

[0174] This comparative example provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the absence of a second anaerobic roasting, the method is the same as that in Example 1, and will not be repeated here.

[0175] Comparative Example 3

[0176] This comparative example provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for the absence of a third roasting, the method is the same as that in Example 1, and will not be repeated here.

[0177] Comparative Example 4

[0178] This comparative example provides a method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries. Except for step (6), which does not involve the addition of a reducing agent, the method is the same as that in Example 1 and will not be repeated here.

[0179] Test methods: ICP was used to test the lithium and phosphorus contents in the recovered lithium-containing solution and lithium-phosphorus solution, and the recovery rates of lithium and phosphorus were calculated; ICP was used to test the nickel, cobalt, and manganese contents in the nickel-cobalt-manganese sulfate solution, and the recovery rates of nickel, cobalt, and manganese were calculated; a carbon-sulfur analyzer was used to test the purity of the graphite product, and the graphite recovery rate was calculated; iron purity in the iron-containing secondary magnetic material was tested by iron element titration, and the iron recovery rate was calculated.

[0180] The test results of the above embodiments and comparative examples are shown in Table 1.

[0181] Table 1

[0182]

[0183] The COD of the battery powder products obtained in the above embodiments and comparative example step (2) was tested, and the results are shown in Table 2.

[0184] Table 2

[0185]

[0186] Taking Example 1 and Comparative Example 3 as examples, the collected graphite products were subjected to electrochemical performance tests, and the test results are shown in Table 3.

[0187] Table 3

[0188]

[0189] As can be seen from Tables 1 to 3:

[0190] (1) As can be seen from Examples 1 to 3, the method for joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries provided by the present invention can achieve simultaneous recycling of the two types of waste batteries. The recovery rates of each component are relatively high. The recovery rate of lithium is above 97.36%, the recovery rate of phosphorus is above 76%, the recovery rate of nickel is above 98.81%, the recovery rate of cobalt is above 98.32%, the recovery rate of manganese is above 97.31%, the purity of graphite is above 99.86%, and the recovery rate of graphite is above 97.31%. The purity of iron in the second magnetic material is above 91.93%, and the recovery rate of iron is above 96.23%.

[0191] (2) Comparing Examples 1 and 5-7, it can be seen that the main function of the first oxygen-free calcination in this invention is to volatilize and decompose the structural adhesive, separator, electrolyte, and binder in the battery pack, thereby increasing the recovery rate of battery powder. Moreover, this invention preferably controls the temperature of the first oxygen-free calcination within a reasonable range, which can avoid the risk of increased equipment energy consumption and thermal runaway of ternary cells in the battery pack caused by excessively high first oxygen-free calcination temperature; at the same time, it can promote the complete decomposition of separator and binder in the cells in the battery pack, improve the battery powder yield, and further ensure the recovery rate of elements such as nickel, cobalt, manganese, and lithium iron.

[0192] (3) Comparing Example 1 and Example 8 to Example 11, it can be seen that the second oxygen-free calcination in this invention mainly reduces nickel, cobalt and manganese in the ternary cathode material to elemental form. By controlling the temperature of the second oxygen-free calcination within a reasonable range, the recovery rate of nickel, cobalt and manganese can be improved, while reducing equipment energy consumption and effectively reducing the excessive consumption of graphite materials, thus taking into account the graphite recovery rate.

[0193] (4) Comparing Example 1 and Examples 12 to 15, it can be seen that the third roasting in this invention mainly modifies the lithium iron phosphate cathode material, converting the Fe element in LiFePO4 into Fe element with stronger magnetic properties and iron-containing compounds, thereby facilitating subsequent recovery through the second magnetic separation. By controlling the temperature of the third roasting within a reasonable range, the situation where Li and P in the battery powder are vaporized into flue gas can be reduced, while promoting the decomposition of lithium iron phosphate cathode powder into Fe and P2O5, improving the magnetic separation effect of Fe, and comprehensively improving the recovery rate and purity of iron.

[0194] (5) As can be seen from the combined example 1 and comparative example 1, the first oxygen-free calcination of the present invention can remove the structural adhesive, binder, separator and electrolyte in this step, improve the powder removal rate of battery powder, and thus increase the recovery rate of each element.

[0195] (6) As can be seen from the combined example 1 and comparative example 2, the present invention adopts the second oxygen-free calcination, which can realize the reaction between nickel cobalt manganese oxide and negative electrode graphite material, realize the transformation of ternary positive electrode material into nickel cobalt manganese element, and then realize the recovery of nickel cobalt manganese through the first magnetic separation.

[0196] (7) As can be seen from the combined examples 1 and 3, the present invention uses a third calcination to decompose LiFePO4 into Fe and P2O5, so that Fe can be recovered by the second magnetic separation.

[0197] (8) As can be seen from Example 1 and Comparative Example 4, the present invention adds a reducing agent in the third calcination, which can repair the negative electrode graphite while realizing the decomposition of lithium iron phosphate, improve the electrochemical performance of graphite products, and increase the value of graphite products.

[0198] In summary, the method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries provided by this invention can achieve simultaneous recycling of the two types of waste batteries, with high recovery rates for each component. Under preferred conditions, the recovery rate of lithium is above 96%, the recovery rate of phosphorus is above 75%, the recovery rate of nickel is above 98%, the recovery rate of cobalt is above 98%, the recovery rate of manganese is above 97%, the purity of graphite is above 99%, and the recovery rate of graphite is above 97%. In the second magnetic material, the purity of iron is above 90%, and the recovery rate of iron is above 95%.

[0199] The present invention has been illustrated with the above embodiments to illustrate its detailed features, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the selected technical features, additions of auxiliary technical features, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for the joint recycling of waste lithium iron phosphate batteries and ternary lithium batteries, characterized in that, The method includes the following steps: (1) The battery pack with the safety valve opened is subjected to the first oxygen-free calcination to obtain the calcined battery pack; (2) Take out the battery cells from the calcined battery pack, and crush and screen the battery cells. Copper and aluminum products are obtained on the sieve, and battery powder is obtained on the underside of the sieve. (3) The battery powder is subjected to a second oxygen-free calcination to obtain calcined battery powder; (4) The calcined battery powder is subjected to a first magnetic separation to obtain a first magnetic material containing nickel, cobalt and manganese and a first non-magnetic material containing lithium iron phosphate; (5) The first magnetic material is sequentially subjected to lithium impregnation and solid-liquid separation to obtain a lithium-containing solution and a nickel-cobalt-manganese-containing solid phase; (6) Mix the reducing agent and the first non-magnetic material, and then calcine it for the third time to obtain the third calcined product; the third calcined product is subjected to a second magnetic separation to obtain a second magnetic material containing iron and a second non-magnetic material; the second non-magnetic material is purified by acid leaching and solid-liquid separation to obtain a lithium-phosphorus solution and a graphite product. There is no sequential relationship between steps (5) and (6).

2. The method according to claim 1, characterized in that, The process of making the battery pack with the safety valve opened in step (1) includes: using a puncturing device to open the safety valve on the individual cell inside the battery pack; Preferably, the temperature of the first anaerobic calcination in step (1) is 380~550℃; Preferably, the atmosphere for the first anaerobic roasting includes a nitrogen atmosphere; Preferably, the first anaerobic calcination time is 1~3 hours; Preferably, the battery pack includes any one or a combination of at least two of the following: waste lithium iron phosphate battery pack, waste ternary lithium-ion battery pack, or a battery pack combining waste lithium iron phosphate battery cells and ternary lithium-ion battery cells.

3. The method according to claim 1 or 2, characterized in that, The removal process in step (2) includes: cutting the shell of the baked battery to obtain the battery shell product and the battery cell. Preferably, the crushing device includes a hammer crusher; Preferably, the sieving includes sequentially performing a first mesh size sieving, a second mesh size sieving, and a third mesh size sieving; the mesh size of the first mesh size sieving is less than the mesh size of the second mesh size sieving, which is less than the mesh size of the third mesh size sieving. Preferably, the copper-aluminum product is obtained from the first mesh size sieve, the second mesh size sieve, and the third mesh size sieve. Preferably, the battery powder is obtained from the undersize sample of the third mesh sieve.

4. The method according to any one of claims 1 to 3, characterized in that, In step (3), the temperature of the second anaerobic calcination is 600~750℃; Preferably, the atmosphere for the second anaerobic roasting includes a nitrogen atmosphere; Preferably, the second anaerobic calcination time is 1-3 hours.

5. The method according to any one of claims 1 to 4, characterized in that, In step (4), the magnetic field strength of the first magnetic separator is 0.4~0.6T; Preferably, the first magnetic separation is performed using a dry magnetic separator.

6. The method according to any one of claims 1 to 5, characterized in that, The lithium impregnation in step (5) includes: mixing the first magnetic material, water and acid, and then stirring the resulting mixture. Preferably, the solid-liquid ratio of the first magnetic material to water is 1:(2~5)g / mL; Preferably, the acid includes sulfuric acid; Preferably, the pH range of the mixture is 4 to 6; Preferably, the temperature of the stirring process is 25~60℃; Preferably, the stirring speed is 400~600 r / min; Preferably, the stirring time is 30-90 minutes.

7. The method according to any one of claims 1 to 6, characterized in that, Step (5) further includes: leaching the nickel-cobalt-manganese solid phase; Preferably, the leaching treatment includes: mixing a sulfuric acid solution and the nickel-cobalt-manganese solid phase, followed by stirring and solid-liquid separation to obtain a nickel-cobalt-manganese sulfate solution and leaching residue; Preferably, the molar concentration of the sulfuric acid solution is 1.5~3 mol / L; Preferably, the solid-liquid ratio of the sulfuric acid solution to the nickel-cobalt-manganese solid phase is 1:(2~4)g / mL; Preferably, the temperature of the stirring reaction is 70~90℃; Preferably, the stirring speed is 400~600 r / min; Preferably, the stirring reaction lasts for 0.5 to 2 hours.

8. The method according to any one of claims 1 to 7, characterized in that, The reducing agent mentioned in step (6) includes pitch and / or needle coke; Preferably, the mass ratio of the reducing agent to the first non-magnetic material is (0.4~0.7):1; Preferably, the reducing agent comprises pitch and needle coke, wherein the mass ratio of pitch to needle coke is (2~4):1; Preferably, the third firing is carried out in a rotary kiln; Preferably, the temperature of the third calcination is 950~1450℃; Preferably, the atmosphere for the third roasting includes a nitrogen atmosphere; Preferably, the third calcination time is 0.5~2 hours; Preferably, leaching residue is also added to the mixing process in step (6); Preferably, the mass ratio of the leaching residue to the total mass of the first non-magnetic material and the reducing agent is (0.1~1):

100.

9. The method according to any one of claims 1 to 8, characterized in that, In step (6), the second magnetic separation uses a wet magnetic separator; Preferably, the magnetic field strength of the second magnetic separator is 0.8~1.2T; Preferably, the second non-magnetic material includes graphite, phosphorus compounds, and lithium compounds.

10. The method according to any one of claims 1 to 9, characterized in that, The acid leaching purification in step (6) includes: mixing a second non-magnetic material, acid solution and hydrogen peroxide to carry out a reaction; Preferably, the acid solution includes sulfuric acid; Preferably, the concentration of sulfuric acid in the acid leaching and purification process is 2-4 mol / L; Preferably, the solid-liquid ratio of the acid solution to the second non-magnetic material is 1:(1~3)g / mL; Preferably, the amount of hydrogen peroxide added is 1 to 1.5 times the amount of metal in the second non-magnetic material; Preferably, the acid leaching and purification temperature is 70~90℃; Preferably, the acid leaching purification time is 1-3 hours.

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