A magnetic separation method for mixed pole pieces of waste lithium-ion batteries

Abstract

The present invention discloses a method for magnetic separation of waste lithium-ion battery pole pieces. The waste lithium-ion batteries are subjected to mechanical crushing, preliminary magnetic separation, air separation, and screening to obtain large-scale mixed positive and negative pole pieces. The large-scale mixed positive and negative pole pieces are then pre-magnetized to enhance their magnetic differences. Ultra-high-purity positive pole pieces are then separated through weak magnetic separation, followed by strong magnetic separation to separate the mixed positive and negative pole pieces. The remaining material is the ultra-high-purity negative pole piece. The positive and negative pole pieces obtained by the method of the present invention are of high purity, and the positive electrode material in the positive pole piece retains its original crystalline structure, making it suitable for direct use as raw material for regeneration and repair.

Description

Technical Field

[0001] The present invention relates to a method for magnetic separation of mixed pole pieces of waste lithium-ion batteries, and in particular to a process for fine magnetic separation of a mixture of waste battery pole pieces, belonging to the technical field of waste battery recycling. Background Art

[0002] In recent years, with the massive retirement of lithium-ion batteries, it is urgent to carry out the comprehensive recycling and utilization of waste lithium-ion batteries. Waste lithium-ion batteries contain a large amount of valuable metals, which is far higher than natural minerals and has huge economic value. At present, the comprehensive recycling and treatment methods of waste lithium-ion batteries mainly include wet comprehensive recovery and physical direct regeneration. Among them, the element loss rate of wet recovery is large and the pollution of three wastes is high. Although direct regeneration is a recycling and utilization method with short process, high resource utilization efficiency and high economic value, it has extremely high requirements for the quality of raw materials. Traditional screening, re-selection and other methods are difficult to provide high-quality raw materials, resulting in poor compatibility of direct regeneration. Based on this, starting from the source, through the high-quality separation of mixed electrodes of waste lithium-ion batteries, ultra-high purity positive electrode sheet materials and negative electrode sheet materials are obtained, which is expected to provide reliable raw materials for subsequent direct regeneration materials.

[0003] Currently, some patents use magnetic separation to separate the positive and negative pole pieces of spent lithium-ion batteries. For example, Chinese patent application CN107492695A utilizes the magnetic difference between the positive and negative pole pieces to magnetically separate a mixture of positive and negative pole pieces in a magnetic field with a strong induction intensity greater than 9000 Gs, selecting the positive pole pieces and achieving a high separation rate. However, this method exhibits a small magnetic difference between the positive and negative pole pieces, and does not require the size of the spent pole pieces. This can lead to significant material carryover from large pole piece materials and significant impurity entanglement from small-scale materials, resulting in a high concentration of impurities in the positive and negative pole pieces obtained through magnetic separation. Chinese patent application CN113083848A discloses a method for efficiently separating the pole pieces by converting graphite into carbon dioxide for removal and converting lithium iron phosphate into highly magnetic materials such as trivalent lithium iron phosphate and iron oxide. However, the crystal structure of the lithium iron phosphate undergoes transformation during the oxidative calcination process, making the resulting pole pieces unsuitable for direct regeneration and repair.

[0004] Therefore, it is necessary to find a method that can achieve efficient separation of the positive and negative electrodes of waste lithium-ion batteries without damaging the crystal phase structure of the positive electrode material in the positive electrode, so that the obtained positive and negative electrodes can be used as raw materials for regeneration and repair. Summary of the Invention

[0005] In response to the problems existing in the prior art, the purpose of the present invention is to provide a method for magnetic separation of mixed pole pieces of waste lithium-ion batteries. This method controls the scale of the mixed pole pieces, utilizes a pre-magnetization method to improve the magnetic difference between the positive and negative pole pieces, and combines the synergistic effect of weak magnetic separation and strong magnetic separation to efficiently separate the positive and negative pole pieces. The obtained positive and negative pole pieces have high purity, and the positive electrode material in the positive pole piece maintains the original crystalline phase structure, and can be directly used as a raw material for regeneration and repair.

[0006] In order to achieve the above technical objectives, the present invention provides a method for magnetic separation of mixed pole pieces of waste lithium-ion batteries. According to the method, waste lithium-ion batteries are subjected to mechanical crushing, preliminary magnetic separation, air separation and screening to obtain large-scale positive and negative mixed pole pieces; the large-scale positive and negative mixed pole pieces are pre-magnetized to enhance the magnetic difference of the pole pieces, and then ultra-high-purity positive pole pieces are separated by weak magnetic separation, and positive and negative mixed pole pieces are separated by strong magnetic separation. The remaining material is the ultra-high-purity negative pole piece.

[0007] The technical solution of the present invention first controls the degree of crushing and screening to obtain large-sized mixed positive and negative pole pieces, which is beneficial to prevent fine materials from causing impurity winding in the subsequent processing process, which seriously affects the purity of magnetic separation. At the same time, the iron shell, electrolyte and diaphragm in the waste lithium-ion batteries can be removed by mechanical crushing, preliminary magnetism and air separation. Secondly, the present invention can increase the magnetic difference between the positive active material (such as lithium iron phosphate, ternary material) and the negative pole piece (graphite) in the positive pole piece through pre-magnetization treatment, which is beneficial to create better conditions for subsequent more accurate magnetic separation, and the crystal structure of the positive electrode material will not be damaged in this process, which is beneficial to the direct regeneration and repair of the positive and negative pole pieces obtained after separation. In addition, the present invention adopts the combined effect of weak magnetism and strong magnetism to achieve weak magnetic separation of ultra-high purity positive pole pieces with strong magnetism, strong magnetic extraction of finely divided positive pole pieces with weaker magnetism, positive pole materials and a small amount of negative pole pieces that are mixed in the positive pole pieces due to folding, winding, etc. during the crushing process. The remaining materials are ultra-high purity negative pole pieces with no magnetism at all. Different pole piece materials can be treated differently to improve the overall processing efficiency and economic value of the materials.

[0008] The inventors discovered that the present invention must adopt a combination of weak magnetic and strong magnetic methods. If weak magnetic separation is not used, the mixed positive and negative pole pieces will be magnetically separated and enter the positive pole pieces, causing the purity of the positive pole pieces to decrease. If only weak magnetic separation is used, ultra-high-purity negative pole pieces cannot be obtained.

[0009] As a preferred solution, the waste lithium-ion batteries include at least one of waste lithium iron phosphate batteries, waste ternary batteries, waste lithium cobalt oxide batteries, and waste lithium titanate batteries.

[0010] As a preferred solution, the scale range of the crushed waste lithium-ion battery pole piece is 1cm 2 ~2cm 2 If the battery electrode pieces of the present invention are crushed to a too small scale, the positive and negative electrode pieces will shed powder seriously, and the ultra-fine positive and negative electrode pieces will be easily entrained with large pieces, affecting the purity of the final product; if the crushing scale is too large, the positive and negative electrode pieces will be easily folded and entrained during the process, resulting in a reduced recovery rate.

[0011] As a preferred solution, the screening system uses a 50-200 mesh pore size. The mesh size of the screening system has little effect on the recovery rate of the electrode pieces. However, if the pore size of the screening system is too small (i.e., the mesh size is too large), some finely divided electrode pieces will enter the subsequent magnetic separation process, causing serious entrainment of fine impurities, resulting in lower purity of the separated positive electrode pieces. If the pore size is too large, some positive and negative electrode pieces will be lost, reducing the recovery rate.

[0012] As a preferred solution, the pre-magnetization process is as follows: the large-scale positive and negative mixed pole pieces are -1 The rate of transmission passes through the pre-magnetization device, and the magnetic field strength is 0.5 to 3.0 T. The pre-magnetization process of the present invention requires comprehensive control of the transmission rate and magnetic field strength. If the rate is too fast or the magnetic field strength is too low, it will lead to incomplete magnetization of the positive and negative mixed pole pieces, resulting in weak magnetism of the positive pole piece, which is not conducive to the subsequent sorting and purification; while if the rate is too slow or the magnetic field strength is too high, although it is conducive to purification, the energy consumption is too high and the economic value is reduced.

[0013] As a preferred solution, the pre-magnetization device includes, from the inside to the outside, a transport pipe, a magnetic induction coil, and a protective cover. The magnetic induction coil is wound around the outside of the transport pipe, and during the pre-magnetization process, large-scale positive and negative mixed pole pieces are transported from the inside of the transport pipe. The pre-magnetization device of the present invention uses electromagnetic magnetization means, with an induction coil installed on the outside of the transport pipe, and further equipped with a protective cover to shield the magnetic field from the outside. By controlling the power-on process and the current size to control the magnetic field strength, the magnetic strength is regulated. The pre-established magnetic field rearranges the magnetic moment of the positive magnetic material on the positive pole piece in the positive and negative mixed pole piece of the present invention and adjusts the internal structure, ultimately achieving a significant increase in the magnetism of the positive pole material.

[0014] As a preferred solution, the pre-magnetization magnetic field is any one of a steady-state magnetic field, a pulsed magnetic field and an alternating magnetic field.

[0015] As a preferred solution, the weak magnetic separation treatment conditions are: a magnetic field strength of 0.1 to 0.5 T and a number of cycles of 3 to 6. Low weak magnetic separation field strength and a small number of cycles will reduce the recovery rate of waste lithium-ion battery positive electrode sheets. High weak magnetic separation field strength and a large number of cycles will remove some finely divided positive electrode material or mixed negative electrode sheets, resulting in a reduction in the purity of waste lithium-ion battery positive electrode sheets.

[0016] As a preferred solution, the processing conditions of the high-intensity magnetic separation are: a magnetic field strength of 1.0 to 2.0 T and a number of cycles of 2 to 4. A low magnetic field strength and a small number of cycles in the high-intensity magnetic separation of the present invention will reduce the purity of the high-purity waste lithium-ion battery negative electrode sheets; a high magnetic field strength and a large number of cycles will lead to a longer process and increased energy consumption.

[0017] As a preferred solution, the purity of the ultra-high purity positive electrode sheet is greater than 99.90%, and the purity of the ultra-high purity negative electrode sheet is greater than 98.1%. The positive and negative electrode sheets obtained by the magnetic separation method of the present invention are of high purity and can be directly used as raw materials for regeneration and repair.

[0018] As a preferred solution, the material to be processed by the pre-magnetization treatment is solid or liquid; when it is liquid, water or a low-cost organic solvent is used as a dispersant to improve the dispersibility of the positive and negative electrodes.

[0019] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0020] 1) The method of the present invention controls the scale of the mixed pole pieces, utilizes the pre-magnetization method to improve the magnetic difference between the positive and negative pole pieces, and combines the synergistic effect of weak magnetic separation and strong magnetic separation to efficiently separate the positive and negative pole pieces. The obtained positive and negative pole pieces have high purity, and the positive pole piece retains the original crystalline structure, and can be directly used as a raw material for regeneration and repair.

[0021] 2) This method has the characteristics of simple operation, short cycle and high economic benefit.

[0022] 3) The method of the present invention controls the degree of crushing and screening to obtain large-sized positive and negative mixed electrode sheets, which is beneficial to preventing problems such as impurity winding caused by fine materials in subsequent processing, which seriously affects the purity of magnetic separation.

[0023] 4) The pre-magnetization device used in the present invention has a simple structure and can significantly increase the magnetism of the positive electrode material without destroying the crystalline structure of the positive electrode material through electromagnetic magnetization, thereby facilitating subsequent magnetic separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a process flow chart of the present invention.

[0025] Figure 2 This is a schematic structural diagram of the pre-magnetization device used in the present invention.

[0026] Figure 3 This is the XRD of the lithium iron phosphate separated in Example 5 of the present invention. DETAILED DESCRIPTION

[0027] In order to further illustrate the present invention, the contents of the present invention are described in detail below in conjunction with the examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are provided only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. The scope of protection of the present invention is not limited to the following examples.

[0028] The structural diagram of the pre-magnetization device used in the embodiment of the present invention is as follows Figure 2 As shown, from the inside to the outside, it includes a transport pipe, a magnetic induction coil and a protective cover. The magnetic induction coil is wound around the outside of the transport pipe. During the pre-magnetization treatment, large-scale positive and negative mixed pole pieces are transported from the inside of the transport pipe.

[0029] The positive electrode materials remaining in the mixed materials referred to in the embodiment are finely divided positive electrode materials and positive electrode plates with weak magnetism, and the negative electrode materials are mixed negative electrode plates.

[0030] Example 1 (Comparative Example)

[0031] The waste lithium iron phosphate batteries are mechanically crushed to obtain an area of ​​0.1mm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials is high-purity large-scale waste battery materials. They are conveyed through a pre-magnetization device on a conveyor belt at a rate of 8 m s -1The magnetic field strength transmitted is 1.5T, the magnetic field type adopts a steady-state magnetic field, and the material form is solid; the pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and a cycle number of 4 times to obtain ultra-high purity positive electrode sheets; the remaining material is passed through a strong magnetic separator with a magnetic separation strength of 1.5T and a cycle number of 3 to finally obtain ultra-high purity negative electrode sheets. The calculation rule is based on the material after screening of the positive and negative electrode sheets, where the recovery rate of ultra-high purity positive electrode sheets is as high as 90%, the content of positive electrode material remaining in the mixed material is 10%, and the content of negative electrode material is 5%, and the recovery rate of ultra-high purity negative electrode sheets is as high as 95%. However, due to the crushing of the material into relatively finely divided materials in this process, a large amount of positive electrode powder falls off, and the overall recovery efficiency is relatively low. This is primarily because, after the materials are crushed into ultrafine powder, some of the positive and negative electrode materials fall off the current collector. After passing through the screening system, the detached mixed powder is gathered together to form a mixed positive and negative electrode powder. Furthermore, after the positive electrode sheet is de-powdered, only the aluminum foil remains. This aluminum foil cannot be pre-magnetized and will directly enter the negative electrode system, resulting in a high impurity content in the final material.

[0032] Example 2 (Comparative Example)

[0033] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized materials of waste batteries are subjected to magnetic separation, sorting and other processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper material is a high-purity large-scale positive and negative electrode mixed electrode sheet. The large-scale positive and negative electrode mixed electrode sheets are initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and 4 cycles to obtain positive electrode sheets; the remaining materials are passed through a strong magnetic separator with a magnetic separation strength of 1.5T and 3 cycles to finally obtain negative electrode sheets. The calculation rule is based on the materials after screening of the positive and negative electrode sheets, where the recovery rate of the positive electrode sheets is as high as 30%, the content of positive electrode materials remaining in the mixed materials is 70%, and the negative electrode materials are 55%, and the recovery rate of the negative electrode sheets is as high as 45%. The positive and negative electrode mixed electrode sheets that have not been pre-magnetized have a small difference in positive and negative magnetic properties, making them difficult to separate efficiently.

[0034] Example 3 (Comparative Example)

[0035] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1The magnetic field strength transmitted is 1.5T, the magnetic field type adopts a steady-state magnetic field, and the material form is solid; the mixed electrode pieces are passed through a strong magnetic separator with a magnetic separation strength of 1.5T and a cycle number of 3 times to finally obtain the negative electrode pieces. The calculation rule is based on the material after the positive and negative electrode pieces are screened, where the recovery rate of the positive electrode pieces is as high as 40%, the content of positive electrode material remaining in the mixed material is 60%, and the negative electrode material is 43%, and the recovery rate of the negative electrode pieces is as high as 57%. Without adding a weak magnetic separation stage, the mixed electrode pieces of positive and negative electrodes will be entrained and separated by magnetic separation into the positive electrode pieces, resulting in some negative electrode pieces being mixed in the positive electrode pieces.

[0036] Example 4 (Comparative Example)

[0037] The waste lithium iron phosphate batteries are mechanically crushed to obtain an area of ​​1mm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1 The magnetic field strength transmitted is 1.5T, the magnetic field type adopts a steady-state magnetic field, and the material form is solid; the pre-magnetized material is initially separated by a weak magnetic separator, the magnetic field strength is 0.30T, the number of cycles is 4, and ultra-high purity positive electrode sheets are obtained; the positive and negative electrode sheet materials after screening are used as the calculation rule, among which the recovery rate of ultra-high purity positive electrode sheets is 80%, and the remaining separated negative electrode sheets contain the remaining 20% ​​of positive electrode materials. If high-quality utilization is required, high-acid wet leaching is still required.

[0038] Example 5

[0039] The waste lithium iron phosphate batteries are mechanically crushed to obtain an area of ​​1mm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1The magnetic field strength is 1.5T, the magnetic field type is a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and a cycle number of 4 times, obtaining ultra-high-purity positive electrode sheets. The remaining material is passed through a high-intensity magnetic separator with a magnetic separation strength of 1.5T and a cycle number of 3 times, finally obtaining ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 80%, and the content of positive electrode material remaining in the mixed material is 20% and the content of negative electrode material is 25%, respectively. The recovery rate of ultra-high-purity negative electrode sheets is as high as 75%.

[0040] Example 6

[0041] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​2cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1 The magnetic field strength is 1.5T, the magnetic field type is a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and four cycles to obtain ultra-high-purity positive electrode sheets. The remaining material is passed through a high-intensity magnetic separator with a magnetic separation strength of 1.5T and three cycles to obtain ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 75%, and the content of positive electrode material remaining in the mixed material is 25%, and the content of negative electrode material is 18%, resulting in a recovery rate of ultra-high-purity negative electrode sheets of up to 82%.

[0042] Example 7

[0043] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 50-mesh screening system, and the upper layer of materials is high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1The magnetic field strength transmitted through the process is 1.5T, the magnetic field type adopts a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and four cycles to obtain ultra-high-purity positive electrode sheets. The remaining material is passed through a strong magnetic separator with a magnetic separation strength of 1.5T and three cycles to finally obtain ultra-high-purity negative electrode sheets. The calculation rule is based on the material after screening of the positive and negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 78%. The content of positive electrode material remaining in the mixed material is 22%, and the content of negative electrode material is 26%, resulting in a recovery rate of ultra-high-purity negative electrode sheets as high as 74%. The mesh size of the screen has little effect on the recovery rate of the sheets.

[0044] Example 8

[0045] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 200-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 1 m s -1 The magnetic field strength is 1.5T, the magnetic field type is a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and four cycles to obtain ultra-high-purity positive electrode sheets. The remaining material is passed through a high-intensity magnetic separator with a magnetic separation strength of 1.5T and three cycles to obtain ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 81%, and the content of positive electrode material remaining in the mixed material is 19% and the content of negative electrode material is 22%, respectively. The recovery rate of ultra-high-purity negative electrode sheets is as high as 78%.

[0046] The mesh size of the screen has little effect on the recovery rate of the cathode. However, due to the small aperture of the screen, some finely divided cathodes may enter the subsequent magnetic separation process, causing the inclusion of fine impurities and reducing the purity of the separated cathodes.

[0047] Example 9

[0048] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 15ms. -1The magnetic field strength is 1.5T, the magnetic field type is a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and four cycles to obtain ultra-high-purity positive electrode sheets. The remaining material is passed through a high-intensity magnetic separator with a magnetic separation strength of 1.5T and three cycles to obtain ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 68%, and the content of positive electrode material remaining in the mixed material is 32% and the content of negative electrode material is 29%, respectively. The recovery rate of ultra-high-purity negative electrode sheets is as high as 71%.

[0049] Example 10

[0050] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1 The magnetic field strength is 0.5T, the magnetic field type is a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and four cycles to obtain ultra-high-purity positive electrode sheets. The remaining material is passed through a high-intensity magnetic separator with a magnetic separation strength of 1.5T and three cycles to obtain ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 55%, and the content of positive electrode material remaining in the mixed material is 45% and 35% respectively, resulting in a recovery rate of ultra-high-purity negative electrode sheets of up to 65%.

[0051] Example 11

[0052] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1The magnetic field strength is 3.0T, the magnetic field type is a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and a cycle number of 4 times, obtaining ultra-high-purity positive electrode sheets. The remaining material is passed through a high-intensity magnetic separator with a magnetic separation strength of 1.5T and a cycle number of 3 times, ultimately obtaining ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 78%, and the content of positive electrode material remaining in the mixed material is 22%, and the content of negative electrode material is 33%, resulting in a recovery rate of ultra-high-purity negative electrode sheets of up to 67%.

[0053] Example 12

[0054] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1 The magnetic field strength is 1.5T, using a pulsed magnetic field, and the material is in solid form. The pre-magnetized material is initially separated in a weak magnetic separator with a magnetic field strength of 0.30T and three cycles to obtain ultra-high-purity positive electrode sheets. The remaining material is then passed through a high-intensity magnetic separator with a magnetic separation strength of 1.5T and three cycles to obtain ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 81%, and the residual positive electrode material content in the mixed material is 19% and the negative electrode material content is 22%, respectively, for a recovery rate of 78% for ultra-high-purity negative electrode sheets.

[0055] Example 13

[0056] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1The magnetic field strength is 1.5T, the magnetic field type is a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.10T and three cycles to obtain ultra-high-purity positive electrode sheets. The remaining material is passed through a high-intensity magnetic separator with a magnetic separation strength of 1.5T and three cycles to obtain ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 62%, and the content of positive electrode material remaining in the mixed material is 38% and the content of negative electrode material is 32%, respectively. The recovery rate of ultra-high-purity negative electrode sheets is as high as 68%.

[0057] Example 14

[0058] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1 The magnetic field strength is 1.5T, the magnetic field type is a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.50T and a cycle number of 6 times, obtaining ultra-high-purity positive electrode sheets. The remaining material is passed through a high-intensity magnetic separator with a magnetic separation strength of 1.5T and a cycle number of 3 times, ultimately obtaining ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 83%, and the content of positive electrode material remaining in the mixed material is 17%, and the content of negative electrode material is 22%, resulting in a recovery rate of ultra-high-purity negative electrode sheets of 78%.

[0059] Example 15

[0060] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1The magnetic field strength transmitted is 1.5T, the magnetic field type adopts a steady-state magnetic field, and the material form is solid; the pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and a cycle number of 4 times to obtain ultra-high-purity positive electrode sheets; the remaining material is passed through a strong magnetic separator with a magnetic separation strength of 1.0T and a cycle number of 2 to finally obtain ultra-high-purity negative electrode sheets. The calculation rule is based on the material after screening of the positive and negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 80%. The content of positive electrode material remaining in the mixed material is 20%, and the content of negative electrode material is 17%. The recovery rate of ultra-high-purity negative electrode sheets is as high as 83%. However, the purity of the ultra-high-purity negative electrode sheets decreases.

[0061] Example 16

[0062] The waste lithium iron phosphate batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1 The magnetic field strength is 1.5T, the magnetic field type is a steady-state magnetic field, and the material is in solid form. The pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.30T and four cycles to obtain ultra-high-purity positive electrode sheets. The remaining material is passed through a high-intensity magnetic separator with a magnetic separation strength of 2.0T and four cycles to finally obtain ultra-high-purity negative electrode sheets. The recovery rate of ultra-high-purity positive electrode sheets is as high as 80%, and the recovery rate of ultra-high-purity negative electrode sheets is as high as 78%, based on the material after screening.

[0063] Example 17

[0064] The waste ternary lithium batteries were mechanically crushed to obtain an area of ​​1cm 2 The large-sized waste battery materials are subjected to magnetic separation and sorting processes to obtain positive and negative electrode mixtures. The obtained positive and negative electrode mixtures are passed through a 100-mesh screening system, and the upper layer of materials are high-purity large-scale positive and negative electrode mixed pieces. They are conveyed through a conveyor belt through a pre-magnetization device at a conveying rate of 8ms. -1The magnetic field strength transmitted is 1.5T, the magnetic field type adopts a steady-state magnetic field, and the material form is solid; the pre-magnetized material is initially separated by a weak magnetic separator with a magnetic field strength of 0.10T and a cycle number of 3 times to obtain ultra-high-purity positive electrode sheets; the remaining material is passed through a strong magnetic separator with a magnetic separation strength of 1.5T and a cycle number of 3 times to finally obtain ultra-high-purity negative electrode sheets. The calculation rule is based on the material after the positive and negative electrode sheets are screened, among which the recovery rate of ultra-high-purity positive electrode sheets is as high as 90%. The content of positive electrode material remaining in the mixed material is 10%, and the content of negative electrode material is 7.0%, and the recovery rate of ultra-high-purity negative electrode sheets is as high as 93%. The magnetic physical difference between the ternary material positive electrode sheet and the graphite negative electrode sheet is significant.

[0065] The separation conditions of Examples 1 to 17 are summarized in Table 1 and the separation results are summarized in Table 2.

[0066] Table 1

[0067]

[0068]

[0069] Table 2

[0070]

Claims

1. A method for magnetic separation of mixed pole pieces of waste lithium-ion batteries, characterized by: After the waste lithium-ion batteries are subjected to mechanical crushing, preliminary magnetic separation, air separation and screening to remove the upper layer of material, large-scale positive and negative mixed electrode pieces are obtained; the large-scale positive and negative mixed electrode pieces are pre-magnetized to enhance the magnetic difference of the electrode pieces, and then the ultra-high-purity positive electrode pieces are separated by weak magnetic separation, and the positive and negative mixed electrode pieces are separated by strong magnetic separation. The remaining material is the ultra-high-purity negative electrode piece; The scale range of the crushed waste lithium-ion battery pole piece is 1cm 2 ~2cm 2 ; The screening adopts a screening system with an aperture of 50 to 200 mesh; The process of the pre-magnetization treatment is: -1 The rate passes through the pre-magnetization device with a magnetic field strength of 0.5~3.0T.

2. The method for magnetic separation of mixed pole pieces of waste lithium-ion batteries according to claim 1, characterized in that: The waste lithium-ion batteries include at least one of waste lithium iron phosphate batteries, waste ternary batteries, waste lithium cobalt oxide batteries, and waste lithium titanate batteries.

3. The method for magnetic separation of mixed pole pieces of waste lithium-ion batteries according to claim 1, characterized in that: The pre-magnetization magnetic field is any one of a steady-state magnetic field, a pulsed magnetic field and an alternating magnetic field; The pre-magnetization device includes a transport pipe, a magnetic induction coil and a protective cover from the inside to the outside. The magnetic induction coil is wound around the outside of the transport pipe. During the pre-magnetization process, large-scale positive and negative mixed pole pieces are transported from the inside of the transport pipe.

4. The method for magnetic separation of mixed pole pieces of waste lithium-ion batteries according to claim 1, characterized in that: The processing conditions of the weak magnetic separation are: magnetic field intensity of 0.1-0.5T, and number of cycles of 3-6 times.

5. The method for magnetic separation of mixed pole pieces of waste lithium-ion batteries according to claim 4, characterized in that: The processing conditions of the high-intensity magnetic separation are: magnetic field intensity of 1.0-2.0 T, and number of cycles of 2-4 times.

6. The method for magnetic separation of mixed pole pieces of waste lithium-ion batteries according to any one of claims 1 to 5, characterized in that: The purity of the ultra-high purity positive electrode sheet is greater than 99.90%, and the purity of the ultra-high purity negative electrode sheet is greater than 98.1%.

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