Method for recovering valuable materials from lithium-ion secondary batteries

Abstract

To provide a method for recovering valuable materials from lithium ion secondary batteries, capable of achieving a high recovery rate of cobalt and nickel even if the grade of cobalt and nickel in a magnetic separation object is low.SOLUTION: A method for recovering valuable materials from lithium ion secondary batteries includes: a heat treatment step in which a heat treated material is obtained by subjecting the lithium ion secondary batteries to heat treatment; a first classification step in which a coarse grain product 1 and a fine grain product are obtained by classifying a crushed material that is obtained by crushing the heat treated material; a second classification step in which a coarse grain product 2 and a microfine grain product are obtained by classifying a ground material, which is obtained by grinding the fine grain product, at a classification point that is smaller than the classification point in the first classification step; a first magnetic separation step in which a magnetically attracted material 1 and a magnetically non-attracted material 1 are obtained by magnetically separating the microfine grain product obtained in the second classification step; a second magnetic separation step in which a magnetically attracted material 2 and a magnetically non-attracted material 2 are obtained by magnetically separating the magnetically non-attracted material 1 obtained in the first magnetic separation step; and a recovery step in which valuable materials are recovered from the magnetically attracted material 1 and the magnetically attracted material 2. The second magnetic separation step is performed by wet magnetic separation.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for recovering valuable materials from lithium ion secondary batteries. [Background technology]

[0002] Lithium-ion secondary batteries are lighter, have a higher capacity, and have a higher electromotive force than conventional lead-acid batteries and nickel-cadmium secondary batteries, and are used as secondary batteries for personal computers, electric vehicles, mobile devices, etc. For example, the positive electrode of a lithium-ion secondary battery contains valuable materials such as cobalt and nickel, and is made of lithium cobalt oxide (LiCoO2), ternary positive electrode materials (LiNi x Co y Mn z O2(x+y+z=1)) and so on.

[0003] Since the use of lithium-ion secondary batteries is expected to continue to expand, from the perspective of resource recycling, it is desirable to recover valuable materials such as lithium from lithium-ion secondary batteries that are discarded due to defective products generated during the manufacturing process, or due to the end of the life of the devices in which they are used or the batteries. When recovering valuable materials such as lithium from lithium-ion secondary batteries, it is important to separate and recover the various metals or impurities used in the lithium-ion secondary batteries in order to increase the value of the recovered materials.

[0004] As a method for recovering valuable materials such as cobalt and nickel from crushed heat-treated lithium ion secondary batteries, for example, a method for recovering valuable materials from lithium ion secondary batteries has been proposed, in which the heat-treated lithium ion secondary batteries are crushed, classified, and the resulting fine particles are subjected to wet magnetic separation (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6948481 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the valuable resource recovery method described in Patent Document 1 above was unable to achieve a high recovery rate when the cobalt and nickel grades were low. That is, in a fine product (hereinafter sometimes referred to as "black mass") with low cobalt and nickel grades (the combined value of cobalt and nickel grades is 30% or less), the formation of agglomerates of cobalt metal particles and nickel metal particles is difficult to proceed, and because the average particle size of these particles is small, they become non-magnetic in the wet magnetic separation process, resulting in loss.

[0007] The present invention aims to solve the various problems of the prior art and achieve the following object: That is, the present invention aims to provide a method for recovering valuable resources from lithium-ion secondary batteries, which can achieve a high recovery rate of cobalt and nickel even when the cobalt and nickel contents of the magnetic separation target are low. [Means for solving the problem]

[0008] The means for solving the above problems are as follows: <1> a heat treatment step of heat treating the lithium ion secondary battery to obtain a heat-treated product; a first classification step of crushing the heat-treated product and classifying the crushed product to obtain a coarse product 1 and a fine product; A second classification step in which the pulverized product obtained by pulverizing the fine product is classified at a classification point smaller than the classification point of the first classification step to obtain a coarse product 2 and a fine product; a first magnetic separation step in which the fine product obtained in the second classification step is magnetically separated to obtain magnetic materials 1 and non-magnetic materials 1; a second magnetic separation step in which the non-magnetized materials 1 obtained in the first magnetic separation step are magnetically separated to obtain magnetized materials 2 and non-magnetized materials 2; a recovery step of recovering valuable materials from the magnetized materials 1 and 2; Including, This is a method for recovering valuable materials from a lithium ion secondary battery, characterized in that the second magnetic separation step is carried out by wet magnetic separation. <2> The first classification step is performed at a classification point of 600 μm or more and 2,400 μm or less. <1> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. <3> The grinding of the fine product is carried out wet. <1> or <2> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. <4> The second classification step is performed at a classification point of 25 μm or more and 1,700 μm or less. <1> or <2> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. <5> The first magnetic separation step is carried out in a wet state. <1> or <2> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. <6> The magnetic flux density of the magnetic separation in the first magnetic separation step is 0.1 T or more and less than 0.3 T, The magnetic flux density of the magnetic separation in the second magnetic separation step is 0.3 T or more and 2 T or less. <1> or <2> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. <7> The total value of the cobalt content and nickel content of the non-magnetic material 1 is 30 mass% or less. <1> or <2> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. <8> At least one of cobalt and nickel contained in the non-magnetic material 1 has a number average particle size of 50 μm or less. <1> or <2> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. <9> The second magnetic separation step is carried out by adding a dispersant to the non-magnetized material 1 obtained in the first magnetic separation step. <1> or <2> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. <10> In the recovery step, the magnetized materials 1 and 2 are washed and subjected to solid-liquid separation to recover valuable materials. <1> or <2> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. <11> Copper is recovered from the coarse product 2. <1> or <2> 2. A method for recovering valuable materials from the lithium ion secondary battery described in 1. [Effects of the Invention]

[0009] According to the present invention, it is possible to solve the above-mentioned problems in the prior art, achieve the above-mentioned object, and provide a method for recovering valuable materials from lithium-ion secondary batteries, which can achieve a high recovery rate of cobalt and nickel even when the cobalt and nickel contents in the magnetic separation target are low. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of the process flow in the method of the present invention for recovering valuable materials from a lithium ion secondary battery. [Figure 2] FIG. 2 is a schematic diagram showing an example of a drum-type wet magnetic separation device. [Figure 3] FIG. 3 is a schematic diagram showing another example of a drum-type wet magnetic separation device. [Figure 4] FIG. 4 is a photograph showing an example of a matrix inlet in a high gradient wet magnetic separator. [Figure 5] FIG. 5 is a photograph showing an example of a matrix-containing container in a high-gradient wet magnetic separation device. [Figure 6A] FIG. 6A is a diagram showing an example of a horizontal matrix. [Figure 6B] FIG. 6B is a diagram showing an example of a vertical matrix. [Figure 7] FIG. 7 is a diagram showing an example of a matrix member in which three horizontal matrices and four vertical matrices are alternately stacked. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Method for recovering valuable materials from lithium-ion secondary batteries) The method of the present invention for recovering valuable materials from lithium ion secondary batteries includes a heat treatment step, a first classification step, a second classification step, a first magnetic separation step, a second magnetic separation step, and a recovery step, and may further include other steps as necessary.

[0012] In the present invention, by performing a second magnetic separation step after performing a first magnetic separation step, the cobalt and nickel that were lost as non-magnetized matter in the first magnetic separation step can be recovered as magnetized matter in the second magnetic separation step, thereby achieving a high recovery rate of cobalt and nickel. In particular, even if the combined cobalt and nickel content of the non-magnetized matter 1 obtained in the first magnetic separation step is 30 mass% or less, or even if the number average particle size of at least one of the cobalt and nickel contained in the non-magnetized matter 1 obtained in the first magnetic separation step is 50 μm or less, a high recovery rate of cobalt and nickel can be achieved.

[0013] The method for recovering valuable materials from a lithium ion secondary battery of the present invention is a method for recovering valuable materials from a lithium ion secondary battery, which is a target object. Here, valuables refer to things that can be traded without being discarded, such as various metals. Examples of valuables in lithium-ion secondary batteries include copper (Cu), aluminum (Al), lithium (Li), cobalt (Co), nickel (Ni), iron (Fe), and carbon (C). Among these, cobalt (Co) and nickel (Ni) are preferred.

[0014] <Lithium-ion secondary battery> The lithium ion secondary battery to be disposed of is not particularly limited and can be appropriately selected depending on the purpose. Examples include defective lithium ion secondary batteries generated during the manufacturing process of lithium ion secondary batteries, lithium ion secondary batteries discarded due to defects in the equipment used or the end of the life of the equipment, and used lithium ion secondary batteries discarded due to the end of the life of the equipment.

[0015] The shape, structure, size, and material of the lithium ion secondary battery are not particularly limited and can be appropriately selected depending on the purpose. The shape of the lithium ion secondary battery is not particularly limited and can be appropriately selected depending on the purpose. Examples include laminate type, cylindrical type, button type, coin type, square type, and flat type. The form of the lithium-ion secondary battery is not particularly limited and can be appropriately selected depending on the purpose. Examples include a battery cell, a battery module, and a battery pack. Here, a battery module refers to a battery in which a plurality of battery cells, which are unit batteries, are connected and assembled into a single housing. A battery pack refers to a battery in which a plurality of battery modules are assembled into a single housing. The battery pack may also include a controller or a cooling device.

[0016] Examples of lithium ion secondary batteries include those including a positive electrode, a negative electrode, a separator, an electrolytic solution containing an electrolyte and an organic solvent, and an outer container that is a battery case that houses the positive electrode, the negative electrode, the separator, and the electrolytic solution. The lithium ion secondary battery may be in a state in which the positive electrode, the negative electrode, etc. have fallen off.

[0017] -Positive electrode- The positive electrode is not particularly limited as long as it has a positive electrode active material containing at least one of cobalt and nickel, and can be appropriately selected depending on the purpose. The shape of the positive electrode is not particularly limited and can be appropriately selected depending on the purpose. Examples include a flat plate shape and a sheet shape.

[0018] --Positive electrode current collector-- The shape, structure, size, material, etc. of the positive electrode current collector are not particularly limited and can be appropriately selected depending on the purpose. The positive electrode current collector may be in the form of, for example, a foil. Examples of materials for the positive electrode current collector include stainless steel, nickel, aluminum, copper, titanium, tantalum, etc. Among these, aluminum is preferred.

[0019] The positive electrode material is not particularly limited and can be appropriately selected depending on the purpose. For example, a positive electrode material containing at least a positive electrode active material containing lithium, and optionally containing a conductive agent and a binder resin, can be used. There are no particular limitations on the positive electrode active material as long as it contains at least one of cobalt and nickel, and it can be appropriately selected depending on the purpose. Examples of the positive electrode active material include lithium manganese oxide (LiMn2O4) called LMO system, lithium cobalt oxide (LiCoO2) called LCO system, and LiNi x Co y Mn z O2(x+y+z=1), LiNi, also known as NCA x Co y Al z (x+y+z=1), lithium iron phosphate (LiFePO4), lithium cobalt-nickel oxide (LiCo 1 / 2 Ni 1 / 2 Examples of the positive electrode active material include lithium ion batteries (Li2TiO2), lithium titanate (Li2TiO3), etc. Furthermore, these materials may be used in combination as the positive electrode active material. The conductive agent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include carbon black, graphite, carbon fiber, and metal carbides. The binder resin is not particularly limited and can be appropriately selected depending on the purpose. Examples include homopolymers or copolymers of vinylidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide, and the like, and styrene-butadiene rubber.

[0020] -Negative electrode- The negative electrode is not particularly limited as long as it has a negative electrode active material, and can be appropriately selected depending on the purpose. The shape of the negative electrode is not particularly limited and can be appropriately selected depending on the purpose. Examples include a flat plate shape and a sheet shape.

[0021] --Negative electrode current collector-- The shape, structure, size, material, etc. of the negative electrode current collector are not particularly limited and can be appropriately selected depending on the purpose. The negative electrode current collector may be in the form of, for example, a foil. Examples of materials for the negative electrode current collector include stainless steel, nickel, aluminum, copper, titanium, and tantalum, with copper being preferred among these.

[0022] The negative electrode active material is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include carbon materials such as graphite and hard carbon, titanate, silicon, etc. Furthermore, these materials may be used in combination as the negative electrode active material.

[0023] The positive electrode current collector and the negative electrode current collector have a laminate structure, and the laminate is not particularly limited and can be appropriately selected depending on the purpose.

[0024] -Outer container- The material of the outer container (casing) of the lithium ion secondary battery is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include aluminum, iron, stainless steel, and resin (plastic).

[0025] Hereinafter, each step in the method for recovering valuable materials from a lithium ion secondary battery of the present invention will be described in detail.

[0026] <Heat treatment process> The heat treatment step is a step of heat treating a lithium ion secondary battery to obtain a heat-treated product. The heat-treated product means a product obtained by heat treating a lithium ion secondary battery. The method of performing the heat treatment in the heat treatment step is not particularly limited and can be appropriately selected depending on the purpose. For example, the heat treatment can be performed by heating the object in a known roasting furnace. The roasting furnace is not particularly limited and can be appropriately selected depending on the purpose. Examples include batch furnaces such as rotary kilns, fluidized bed furnaces, tunnel furnaces and muffle furnaces, cupola furnaces and stoker furnaces.

[0027] The atmosphere used for the heat treatment is not particularly limited and can be appropriately selected depending on the purpose. Examples include air atmosphere, inert atmosphere, reducing atmosphere, and low-oxygen atmosphere. The atmospheric atmosphere (air atmosphere) means an atmosphere using atmospheric air (air) containing approximately 21% by volume of oxygen and approximately 78% by volume of nitrogen. The inert atmosphere can be exemplified by an atmosphere consisting of nitrogen or argon. The reducing atmosphere means, for example, an atmosphere containing CO, H2, H2S, SO2, or the like in an inert atmosphere such as nitrogen or argon. A low-oxygen atmosphere means an atmosphere in which the oxygen concentration is 11% by volume or less.

[0028] The conditions for heat treating (heating) the object to be heat-treated (heat treatment conditions) are not particularly limited as long as they allow the individual components of the object to be separated and crushed in the crushing and classification process described below, and can be selected appropriately depending on the purpose. Here, the heat treatment conditions include, for example, the heat treatment temperature and the heat treatment time.

[0029] The heat treatment temperature refers to the temperature of the lithium-ion secondary battery that is the object of the heat treatment. The heat treatment temperature can be measured by inserting a thermometer such as a couple or thermistor into the object during the heat treatment.

[0030] The temperature for the heat treatment (heat treatment temperature) is preferably 400°C or higher and 1,080°C or lower, more preferably 660°C or higher and 1,080°C or lower, and particularly preferably 750°C or higher and 900°C or lower. By setting the heat treatment temperature at 400°C or higher, the cobalt oxide and nickel oxide contained in the positive electrode active material are reduced to metal. Furthermore, these metals can be grown to a particle size that is easily magnetically attracted in the subsequent magnetic separation step. This particle size growth is more likely to occur the higher the heat treatment temperature. Furthermore, by setting the heat treatment temperature at 660°C or higher, it is possible to melt the aluminum that constitutes the outer casing of the LIB pack or cell and separate and recover it from the other components. Furthermore, by setting the heat treatment temperature to 750°C or higher, the lithium in Li(Ni / Co / Mn)O2 in the positive electrode active material and LiPF6 in the electrolyte can be converted into substances in a form in which lithium is soluble in an aqueous solution, such as lithium fluoride (LiF), lithium carbonate (Li2CO3), or lithium oxide (Li2O), and these can be leached into the dispersion medium during the slurry treatment. Furthermore, it is preferable that the outer container of the lithium ion secondary battery be made of a material having a melting point higher than the heat treatment temperature. When a material having a melting point lower than the heat treatment temperature is used for the outer container of the lithium ion secondary battery, the heat treatment is preferably carried out in a low-oxygen atmosphere with an oxygen concentration of 11% by volume or less, or at least so that the oxygen concentration inside the lithium ion secondary battery (particularly the positive electrode current collector and negative electrode current collector arranged in the outer container of the lithium ion secondary battery) during roasting is 11% by volume or less.

[0031] In addition, as a method for realizing a low-oxygen atmosphere, for example, the positive electrode or negative electrode of the lithium ion secondary battery may be housed in an oxygen-shielding container and heat-treated. The material of the oxygen-shielding container is not particularly limited as long as it has a melting point equal to or higher than the heat treatment temperature, and can be appropriately selected depending on the purpose. For example, when the heat treatment temperature is 800°C, iron, stainless steel, and the like, which have a melting point higher than this heat treatment temperature, can be used. In order to release the gas pressure of gas generated by combustion of the electrolyte solution or the like in the lithium-ion secondary battery or laminate, it is preferable to provide an opening in the oxygen-shielding container. The opening area of ​​the opening is preferably 12.5% ​​or less of the surface area of ​​the outer container in which the opening is provided. It is more preferable that the opening area of ​​the opening is 6.3% or less of the surface area of ​​the outer container in which the opening is provided. There are no particular limitations on the shape, size, or location of the opening, and it can be selected appropriately depending on the purpose. The heat treatment time for lithium ion secondary batteries is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 1 minute to 10 hours, more preferably 1 minute to 3 hours. The heat treatment time may be any time required to reach the desired temperature at which cobalt and nickel are metallized, and the holding time may be any time required to ensure that the metallization progresses. A heat treatment time within the preferred range is advantageous in terms of the cost required for the heat treatment. Therefore, it is preferable to carry out the heat treatment at 400° C. or higher and 1,080° C. or lower for one hour or longer.

[0032] <First classification process> The first classification step is a step in which the heat-treated product is crushed and the crushed product obtained is classified to obtain a coarse-grained product 1 and a fine-grained product. The crushing treatment of the heat-treated product is not particularly limited as long as it is a treatment that can crush the heat-treated product to obtain crushed products, and can be appropriately selected depending on the purpose. Furthermore, crushed products refer to products obtained by crushing the heat-treated product. As the crushing treatment, for example, it is preferable to crush the heat-treated product by impact to obtain crushed products. Furthermore, if the outer container of the lithium ion secondary battery does not melt during the heat treatment, it is more preferable to pre-crush the heat-treated product by cutting it with a cutter before applying an impact to the heat-treated product.

[0033] Examples of methods for crushing by impact include a method in which the heat-treated material is thrown by a rotating striking plate and slammed against a collision plate to apply an impact, and a method in which the heat-treated material is hit by a rotating striker (beater), and this can be done using, for example, a hammer crusher. Another method for crushing by impact is a method in which the heat-treated material is hit by ceramic or other balls, and this method can be done using a ball mill, for example. Impact crushing can also be done using, for example, a biaxial crusher with short blade width and length that crushes by compression. Furthermore, examples of methods for crushing by impact include a method in which the heat-treated material is hit with two rotating chains to apply impact, and this can be done, for example, by a chain mill.

[0034] Crushing the heat-treated material by impact promotes crushing of the positive electrode current collector (e.g., aluminum (Al)), but the negative electrode current collector (e.g., copper (Cu)), whose morphology has not changed significantly, exists in a form such as foil. Therefore, in the crushing process, the negative electrode current collector is merely cut into pieces, and thus crushed material can be obtained in a state in which valuable materials derived from the positive electrode current collector (e.g., aluminum) and valuable materials derived from the negative electrode current collector (e.g., copper (Cu)) can be efficiently separated in the first classification step (classification process).

[0035] The crushing time in the crushing treatment is not particularly limited and can be selected appropriately depending on the purpose, but the crushing time per 1 kg of lithium ion secondary batteries is preferably from 1 second to 30 minutes, more preferably from 2 seconds to 10 minutes, and particularly preferably from 3 seconds to 5 minutes.

[0036] The first classification step includes a process of obtaining a coarse-grained product 1 and a fine-grained product by crushing the heat-treated material and classifying the crushed material at a classification point of 600 μm or more and 2,400 μm or less, and it is preferable to classify at a classification point of 850 μm or more and 1,700 μm or less. The first classification step is not particularly limited as long as it can classify the crushed material to obtain a coarse product 1 (over-sieve product) and a fine product (under-sieve product), and can be appropriately selected depending on the purpose.

[0037] The classification method is not particularly limited and can be appropriately selected depending on the purpose, and can be carried out using, for example, a vibrating sieve, a multistage vibrating sieve, a cyclone, a JIS Z8801 standard sieve, a wet vibrating table, an air table, etc. By classification, copper (Cu), iron (Fe), etc. can be separated into the coarse product 1, and lithium, cobalt, nickel, or carbon can be concentrated in the fine product. The particle size of the classification (classification point, sieve opening) is set to a classification point of 600 μm or more and 2,400 μm or less, in order to separate copper (Cu), iron (Fe), aluminum (Al), etc. into the coarse product 1 and concentrate carbon (C), lithium (Li), cobalt (Co), nickel (Ni), manganese (Mn), etc. into the fine product.

[0038] Furthermore, when using a sieve as a classification method, by placing, for example, stainless steel balls or alumina balls on the sieve as a crushing promoter and performing classification, small crushed pieces adhering to larger crushed pieces can be separated from the larger crushed pieces, thereby more efficiently separating the large crushed pieces from the small crushed pieces and further improving the quality of the recovered metal. As described above, in the first classification step, the crushing treatment can be carried out simultaneously with the classification treatment. For example, the heat-treated product obtained in the heat treatment step can be crushed while the crushed product is classified into a coarse product 1 and a fine product, as a crushing-classification step (crushing-classification). If the ratio of fine particles in the first classification step (classification treatment) is low, the coarse particles 1 can be returned to the step of crushing the heat-treated material, thereby improving the recovery rate of valuable materials other than Fe and Cu.

[0039] <Second classification process> The second classification step is a step in which the fine product obtained in the first classification step is crushed and the crushed product obtained is classified at a classification point smaller than the classification point of the first classification step, thereby obtaining a coarse product 2 and a fine product. The grinding treatment is not particularly limited as long as it can grind a fine product to obtain ground material of a predetermined size, and can be appropriately selected depending on the purpose. Examples include media-agitation type grinders (attritors, bead mills, tower mills) that use media such as iron balls, roller mills, jet mills, high-speed rotary grinders (hammer mills, pin mills), and container-driven mills (rotary mills, vibration mills, planetary mills).

[0040] The pulverization process may be either wet or dry, and can be selected appropriately depending on the purpose, but wet pulverization is preferred. Wet pulverization can suppress a decrease in the recovery rate of cobalt (Co) and nickel (Ni) due to dust generation in each process, and eliminates the need for measures to prevent dust from scattering into the surrounding atmosphere. When wet pulverization is performed, it is preferable to perform a slurry treatment in which the fine product obtained after the first classification process is immersed in water to obtain a slurry-like liquid (fine product slurry). The slurrying process is not particularly limited as long as it is a process that can disperse the fine product in water to obtain a slurry (suspension) by immersing (immersing or placing) the fine product recovered in the first classification process in water, and can be selected appropriately depending on the purpose. The particle size (90% particle size) of the pulverized product is preferably 1,000 μm or less, more preferably 750 μm or less, and particularly preferably 500 μm or less. The 90% particle size is the particle size that corresponds to 90% in the particle size cumulative distribution obtained by measurement using, for example, a laser diffraction / scattering particle size distribution analyzer. The number average particle size of at least one or both of the cobalt and nickel contained in the pulverized material is preferably 100 μm or less, more preferably 75 μm or less, and particularly preferably 50 μm or less. The number average particle size is, for example, the average value calculated by measuring the particle sizes of 100 cobalt particles and 100 nickel particles by electron microscope observation. A smaller 90% particle size or number-average particle size promotes liberation of cobalt and nickel from other components, thereby improving the cobalt and nickel qualities of the magnetized materials 1 and 2 recovered in the first and second magnetic separation steps. Note that even when the 90% particle size or number-average particle size is small, the recovery rates of cobalt and nickel in the first and second magnetic separation steps can be increased, so further recovery steps such as a third magnetic separation step may be provided as necessary.

[0041] The dispersion medium for forming a slurry of the fine granular product is not particularly limited and can be appropriately selected depending on the purpose. Examples include industrial water, tap water, ion-exchanged water, ultrafiltered water, reverse osmosis water, pure water such as distilled water, and ultrapure water.

[0042] Here, the slurrying treatment is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a method of simply putting the fine-grained product into water, a method of putting the fine-grained product into water and stirring, a method of putting the fine-grained product into water and gently stirring while applying ultrasonic waves, a method of adding water to the fine-grained product, etc. Among these, the method of putting the fine-grained product into water and stirring is preferred, and the method of putting the fine-grained product into water and gently stirring while applying ultrasonic waves is more preferred.

[0043] The solid-liquid ratio in the slurrying process (the concentration (mass ratio) of the fine product relative to the water) is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 20% by mass or less. If the solid-liquid ratio is less than 1% by mass, cobalt and nickel that would normally be recovered as magnetized material will not be recovered by the magnetic separator and will be lost to non-magnetized material, which is likely to reduce the recovery rate of cobalt and nickel. If the solid-liquid ratio exceeds 50% by mass, more impurities will be caught in the magnetized material, which may reduce the cobalt and nickel grades. The stirring speed of the water in the slurrying treatment is not particularly limited and can be appropriately selected depending on the purpose, and can be set to, for example, 200 rpm. The leaching time in the slurrying treatment is not particularly limited and can be appropriately selected depending on the purpose, and can be, for example, 1 hour.

[0044] In the second classification step, the pulverized material obtained in the pulverization process is classified at a classification point smaller than the classification point of the first classification step and between 75 μm and 1,200 μm, thereby obtaining a coarse product 2 and a fine product. For example, when the pulverized material obtained by the pulverization treatment is subjected to a second classification step using a JIS Z8801 standard sieve with a classification point of 500 μm, the product that passes through the 500 μm standard sieve is the coarse product 2, and the product that passes through the sieve is the fine product. Copper can be concentrated and recovered from the coarse product 2.

[0045] The classification point used in the second classification step is preferably 25 μm or more and 1,700 μm or less, more preferably 75 μm or more and 1,200 μm or less, even more preferably 75 μm or more and 850 μm or less, and particularly preferably 106 μm or more and 600 μm or less. If the classification point exceeds 1,700 μm, copper contamination in the fine product increases, and the cobalt and nickel grades may decrease. If the classification point is below 25 μm, the pulverization energy required to recover cobalt and nickel in the fine product may become excessive.

[0046] The classification treatment in the second classification step is not particularly limited and can be appropriately selected depending on the purpose. Examples include a vibrating sieve, a multistage vibrating sieve, a cyclone, a JIS Z8801 standard sieve, a wet vibrating table, and an air table. The second classification step is not particularly limited and can be appropriately selected depending on the purpose, but is preferably performed in a wet manner. When performing wet classification, the pulverized slurry obtained by the wet pulverization treatment may be supplied as is, or the pulverized slurry may be diluted with a dispersion medium (water) to adjust the solid-liquid ratio. Furthermore, when the second classification step is performed wet using a vibrating sieve or a multistage vibrating sieve, showering the dispersion medium (water) from above the sieve suppresses aggregation of the pulverized material during classification, resulting in good classification results. Furthermore, the phase angle of the vibrating sieve weight is preferably 30° to 90°, more preferably 40° to 80°, and particularly preferably 50° to 70°. Setting this phase angle prevents excessive discharge of the pulverized material or the classified product outside the sieve device (too little residence time on the sieve), resulting in good classification results.

[0047] <First magnetic separation process> The first magnetic separation step is a step in which the fine product obtained in the second classification step is magnetically separated to obtain magnetized matter 1 and non-magnetized matter 1.

[0048] The magnetized object 1 refers to an object that can be attracted to a magnetic source (for example, a magnet, electromagnet, etc.) by the magnetic force generated by the magnetic source that generates the magnetic force (magnetic field). Examples of the magnetized object 1 include ferromagnetic metals. Examples of ferromagnetic metals include iron (Fe), nickel (Ni), and cobalt (Co). The non-magnetic object 1 refers to an object that is not attracted to the magnetic source by the magnetic force generated by the magnetic source. There are no particular limitations on the non-magnetic object, and it can be selected according to the purpose. Examples of non-magnetic metallic objects include paramagnetic or semi-magnetic metals. Examples of paramagnetic or semi-magnetic metals include aluminum (Al), manganese (Mn), gold (Au), silver (Ag), and copper (Cu).

[0049] The first magnetic separation step may be either dry magnetic separation or wet magnetic separation, but wet magnetic separation is preferred for the following reasons. When the fine product obtained in the second classification step is magnetically separated, for example, if dry magnetic separation is performed, the particles may aggregate due to moisture adhering between the particles, and the metal particles derived from the negative electrode current collector, and the fine particles of the negative electrode active material contained in the fine product at 10% or more, and the cobalt particles and nickel particles may not be sufficiently separated. For this reason, in the present invention, it is preferable to perform wet magnetic separation to separate the substances derived from the negative electrode active material and the metals derived from the negative electrode current collector into a non-magnetized material slurry, and recover the cobalt and nickel as magnetized material 1.

[0050] In the wet magnetic separation, the fine product slurry obtained in the second wet classification step may be fed as is, or the fine product slurry may be concentrated or diluted by solid-liquid separation such as sedimentation to adjust the solid-liquid ratio. Also, the fine product slurry may be diluted with water to adjust the solid-liquid ratio. The solid-liquid ratio (concentration (mass ratio) of the fine product relative to water) of the slurry supplied to the wet magnetic separation is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 5% by mass or more and 67% by mass or less, and more preferably 10% by mass or more and 40% by mass or less. If the solid-liquid ratio is less than 5% by mass, the recovery rate of cobalt and nickel as magnetic substances in the wet magnetic separator may decrease. If the solid-liquid ratio exceeds 67% by mass, problems such as pump clogging during slurry supply may occur, and the separation performance of cobalt and nickel (magnetic substances) from non-magnetic substances such as carbon may decrease. The method for supplying the slurry is not particularly limited and can be appropriately selected depending on the purpose, but the slurry in the tank may be supplied by a pump while being stirred.

[0051] The first magnetic separation step is not particularly limited and can be performed using a known magnetic separator (magnetic separator), for example, a drum-type magnetic separator, a high-gradient magnetic separator, etc. Among these, a drum-type magnetic separator is preferred.

[0052] The magnetic flux density for magnetic separation in the first magnetic separation step is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.05 T to 0.9 T, more preferably 0.075 T to 0.6 T, even more preferably 0.1 T to less than 0.3 T, and particularly preferably 0.1 T to 0.2 T. If the magnetic flux density is less than 0.05 T, it is difficult to magnetically attract cobalt and nickel fine particles, and the recovery rate of cobalt and nickel in the magnetized material is likely to decrease. If the magnetic flux density exceeds 0.9 T, the recovery rate of impurities other than cobalt and nickel in the magnetized material 1 increases, and the cobalt and nickel grade in the magnetized material 1 may decrease. Examples of drum-type wet magnetic separation methods in the first magnetic separation step include (1) a method in which a magnet is placed at the 6 o'clock position on a drum, a non-magnetic material 1 slurry is added from the 3 o'clock position (side), and the drum is rotated clockwise, as shown in Figure 2; and (2) a method in which a magnet is placed near the 3 o'clock position on a drum, a non-magnetic material 1 slurry is added from the 12 o'clock to 2 o'clock position (top) of the drum, and the drum is rotated counterclockwise, as shown in Figure 3. Among these, (1) the drum type wet magnetic separation method shown in FIG. 2 is preferred because it can produce high-quality magnetic products of cobalt and nickel.

[0053] <Second magnetic separation process> The second magnetic separation step is a step in which the non-magnetic materials 1 obtained in the first magnetic separation step are magnetically separated to obtain magnetic materials 2 and non-magnetic materials 2. In the case where collected dust generated during the transport of the fine product obtained in the first classification step is collected, the collected dust can also be used as the target of magnetic separation in the second magnetic separation step.

[0054] The combined value of the purity of cobalt and nickel contained in the non-magnetized matter 1 obtained in the first magnetic separation step is preferably 30% or less, more preferably 20% or less, and particularly preferably 15% or less. Even non-magnetized matter 1 having a combined cobalt and nickel content of 30% or less can be recovered as magnetized matter in the second magnetic separation step, thereby improving the recovery rate of cobalt and nickel. However, it is a well-known fact that the higher the grades of cobalt and nickel in the non-magnetized material, the easier it is to recover cobalt and nickel in the magnetized material. The number-average particle size of at least one of the cobalt and nickel contained in the non-magnetized material 1 obtained in the first magnetic separation step is preferably 50 μm or less, more preferably 35 μm or less, and particularly preferably 25 μm or less. The number-average particle size is, for example, the average value calculated by measuring the particle sizes of 100 cobalt particles and nickel particles by electron microscope observation. A smaller number-average particle size promotes liberation of cobalt and nickel from other components, thereby improving the quality of cobalt and nickel in the magnetized material 2 recovered in the second magnetic separation step. Note that, since the recovery rate of cobalt and nickel in the second magnetic separation step can be further increased, further recovery steps such as a third magnetic separation step may be added as necessary. Even cobalt particles and nickel particles with a number-average particle size of 50 μm or less can be recovered as magnetic particles in the second magnetic separation step, thereby improving the recovery rate of cobalt and nickel in the entire process.

[0055] The second magnetic separation step is not particularly limited and can be carried out using a known magnetic separator (magnetic separator), for example, a drum-type magnetic separator or a high-gradient magnetic separator.

[0056] The magnetic flux density for magnetic separation in the second magnetic separation step is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.3 T or more and 2 T or less, more preferably 0.4 T or more and 1.8 T or less, and particularly preferably 0.6 T or more and 1.2 T or less. If the magnetic flux density is less than 0.3 T, it is difficult to magnetically attract cobalt and nickel fine particles, and the recovery rate of cobalt and nickel in the magnetized material is likely to decrease. If the magnetic flux density exceeds 2 T, the recovery rate of impurities other than cobalt and nickel in the magnetized material 2 increases, and the cobalt and nickel grade in the magnetized material 2 may decrease.

[0057] The second magnetic separation step is carried out by wet magnetic separation. The second magnetic separation step is carried out by wet magnetic separation, and preferably by using a high gradient wet magnetic separation method, which may be repeated two or more times. In the high gradient wet magnetic separation method, it is preferable to use a matrix to increase the change in magnetic flux density. As the matrix, for example, a horizontal iron matrix (line width: 2 mm, thickness: 4 mm, 200 mm wide x 50 mm long) shown in Figure 6A and a vertical iron matrix (maximum diamond length: 22 mm, minimum diamond length: 10 mm, thickness: 4 mm, 200 mm wide x 50 mm long) shown in Figure 6B can be used, and a matrix member (200 mm wide x 50 mm long x 28 mm thick) shown in Figure 7 can be used, which is made by stacking three horizontal matrices of Figure 6A and four vertical matrices of Figure 6B alternately and bundling them together.

[0058] The second magnetic separation step is carried out by wet magnetic separation, preferably using a drum type wet magnetic separation method. The drum type wet magnetic separation method in the second magnetic separation step may be, for example, a method in which a non-magnetic material slurry is introduced into a rotating drum having a magnet. The direction of rotation is not particularly limited and can be appropriately selected depending on the purpose, and may be clockwise or counterclockwise. The position of the magnet on the drum is not particularly limited and can be selected appropriately depending on the purpose. For example, the magnet may be at the same position as the position where the non-magnetized material slurry is introduced, or at a position different from the position where the non-magnetized material slurry is introduced. Specific examples of drum-type wet magnetic separation methods in the second magnetic separation step include (1) a method in which a magnet is placed at the 6 o'clock position on the drum, non-magnetized material 1 slurry is added from the 3 o'clock position (side) and the drum is rotated clockwise, as shown in Figure 2, and (2) a method in which a magnet is placed near the 3 o'clock position on the drum, non-magnetized material 1 slurry is added from the 12 o'clock to 2 o'clock position (top) of the drum and the drum is rotated counterclockwise, as shown in Figure 3. Among these, the drum-type wet magnetic separation method shown in (2) Fig. 3 is preferred because it allows for a high recovery rate of cobalt and nickel. In the method shown in (2) Fig. 3, the magnetized materials attracted to the magnet are carried in the 9 o'clock direction by the rotation of the drum and recovered, and the non-magnetized material slurry 2 flows on the drum surface in the 3 o'clock to 6 o'clock direction and is discharged from the 6 o'clock direction.

[0059] The second magnetic separation step can be carried out by adding a dispersant to the slurry of non-magnetized material 1 obtained in the first magnetic separation step. By adding a dispersant to the slurry of non-magnetized material 1, the magnetic separation efficiency of the second magnetic separation step can be improved. The dispersant is not particularly limited and can be appropriately selected depending on the purpose. For example, dispersants used in the fields of dyes, pigments, agricultural chemicals, and inorganic substances can be used. Examples of dispersants include condensates of aromatic sulfonic acid and formalin, and anionic surfactants whose main component is a special carboxylic acid-type polymer surfactant (for example, the "Demol" series of surfactants manufactured by Kao Corporation).

[0060] It should be noted that additional magnetic separation may be performed on the magnetized objects 1 and / or 2, and additional magnetic separation may be performed on the non-magnetized objects 1 and / or 2.

[0061] The total value of the cobalt grade and nickel grade in the magnetic material obtained by wet magnetic separation is preferably concentrated to 1.3 times or more, more preferably 1.5 times or more, of the total value of the cobalt grade and nickel grade in the fine product.

[0062] <Recovery process> The recovery step is a step of recovering valuable materials from the magnetized materials 1 and 2. In the recovery step, valuable materials are recovered by solid-liquid separation of the magnetized materials 1 and 2. The magnetized materials 1 and 2 may be washed before solid-liquid separation. Washing can reduce the quality of impurities such as fluorine contained in the magnetized materials. The washing water used for washing is not particularly limited and can be appropriately selected depending on the purpose. Examples include pure water such as industrial water, tap water, ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, and ultrapure water. Since the magnetized materials 1 and 2 recovered in the first and second magnetic separation steps contain moisture, the moisture may be removed by solid-liquid separation using filter paper, a filter press, or a centrifuge, air drying, or heat drying in a dryer.

[0063] <Other processes> The other steps are not particularly limited and can be appropriately selected depending on the purpose. Examples include a drying step and a purification step.

[0064] <Example of embodiment> Here, an example of an embodiment of the method for recovering valuable materials from a lithium ion secondary battery of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing an example of a process flow in the embodiment of the method for recovering valuable materials from a lithium ion secondary battery of the present invention.

[0065] First, a heat treatment (heat treatment step) is performed on a waste lithium ion secondary battery (LIB; Lithium Ion Battery) to obtain a heat-treated product (heat treatment step). Next, the crushed material obtained by crushing the heat-treated material is classified at a classification point of 600 μm to 2,400 μm to obtain a coarse-grained product 1 and a fine-grained product (first classification step). Here, copper (Cu), aluminum (Al), iron (Fe), etc. can be separated from the coarse-grained product 1.

[0066] The fine product is then soaked in water to obtain a fine product slurry, during which lithium (lithium oxide or lithium carbonate) is leached into the water and residues containing nickel (Ni) and cobalt (Co) are formed in the fine product slurry.

[0067] The resulting fine product slurry is then wet milled to obtain a milled product slurry. Next, the obtained pulverized product slurry is wet classified at a classification point of 25 μm or more and 1,700 μm or less to obtain a coarse-grained product slurry 2 and a fine-grained product slurry (second classification step).

[0068] Next, the resulting fine product slurry is magnetically separated to obtain magnetized matter 1 and non-magnetized matter slurry 1 (first magnetic separation step). Next, the obtained non-magnetized material slurry 1 is magnetically separated to obtain magnetized materials 2 and non-magnetized material slurry 2 (second magnetic separation step). The obtained magnetized materials 1 and 2 are subjected to solid-liquid separation to recover nickel (Ni) and cobalt (Co). In addition, the non-magnetized material slurry 2 is subjected to solid-liquid separation to recover carbon and copper. [Example]

[0069] Examples of the present invention will be described below, but the present invention is not limited to these examples in any way.

[0070] Example 1 -Heat treatment process- The waste lithium-ion secondary batteries (approximately 300 kg) to be treated were heat-treated using a batch burner furnace manufactured by Ecosystem Akita Co., Ltd. as the heat treatment device at a heat treatment temperature of 750°C (heated from 20°C to 750°C over 15 minutes, then held for 3 hours) in an air atmosphere to obtain a heat-treated product.

[0071] -Crushing process- Next, the heat-treated lithium ion secondary batteries were crushed using a chain mill (Crossflow Shredder S-1000, manufactured by Sato Iron Works Co., Ltd.) as a crushing device under conditions of 50 Hz (chain tip speed: approximately 60 m / sec) and a residence time of 50 seconds, to obtain crushed lithium ion secondary batteries.

[0072] -First classification process- Next, the crushed lithium-ion secondary battery material was sieved using a vibrating sieve (diameter 200 mm, manufactured by Tokyo Screen Co., Ltd.) with 1.2 mm mesh openings. After sieving, the product that passed through the 1.2 mm sieve (coarse product 1) and the product that passed through the sieve (fine product) were collected. The cobalt content of the fine product (black mass) was 6.2%, and the nickel content was 13.5%, for a combined content of 19.7%.

[0073] -Slurry process- 62.5 kg of the obtained fine granules were immersed in 250 L of water and subjected to a slurry treatment under conditions of a solid-liquid ratio of 25%, a stirring speed of 400 rpm, and a leaching time of 1 hour to obtain a fine granules slurry.

[0074] -Wet grinding process- The obtained fine product slurry and 10 kg of grinding media (iron balls) were fed into a media agitation grinder (Tower Mill NE008, manufactured by Nippon Eirich Co., Ltd.) in 20 batches, and wet-ground for 30 minutes at a rotation speed of 716 rpm (circumferential speed 3 m / sec) per batch.

[0075] -Second classification process- Next, the obtained fine product slurry was wet classified using JIS Z8801 standard sieves with sieve classification points (mesh openings) of 500 μm and 250 μm, and the product that passed through the 500 μm sieve (coarse product 2) and the product that passed through the 250 μm sieve (fine product slurry) were collected. The intermediate product that passed through the 250 μm sieve was returned to the previous wet grinding process and repeatedly ground until all of the product passed through the 250 μm sieve.

[0076] -First magnetic separation process- The obtained fine product slurry (slurry concentration 15% by mass) was subjected to a first magnetic separation step using a drum-type wet magnetic separation device (manufactured by Japan Eriez Magnetics Co., Ltd., model: WD L-8 Lab Model) shown in Figure 2 at a magnetic flux density of 0.15 T and a drum rotation speed of 40 rpm, and magnetized material 1 and non-magnetized material slurry 1 were recovered. The drum-type wet magnetic separation device shown in Figure 2 is a device in which a magnet is placed at the 6 o'clock position on the drum, a slurry of non-magnetic material 1 is added from the 3 o'clock position (side) of the drum, and magnetic separation is performed while the drum is rotated clockwise. For the obtained non-magnetized material slurry 1, the particle sizes of a total of 100 cobalt particles and nickel particles were measured by electron microscope observation, and the number average particle size was found to be 10 μm. The cobalt grade of the non-magnetized material 1 contained in the non-magnetized material slurry 1 was 3.4%, and the nickel grade was 8.2%, for a combined grade of 11.6%.

[0077] -Second magnetic separation process- The non-magnetized material slurry 1 (slurry concentration: 30% by mass) obtained in the first magnetic separation step was subjected to a second magnetic separation step using a drum-type wet magnetic separator (manufactured by Japan Eriez Magnetics Co., Ltd., model: WD REX1.5φ×12W) shown in FIG. 2 at a magnetic flux density of 0.6 T and a drum rotation speed of 5 rpm, and magnetized material 2 and non-magnetized material slurry 2 were recovered. The drum-type wet magnetic separation device shown in Figure 2 is a device in which a magnet is placed at the 6 o'clock position on the drum, a slurry of non-magnetic material 1 is added from the 3 o'clock position (side) of the drum, and magnetic separation is performed while the drum is rotated clockwise.

[0078] Next, the cobalt and nickel grades, as well as the recovery rates of cobalt and nickel, were measured as follows. The results are shown in Tables 1 and 2.

[0079] <Measurement of cobalt and nickel grades> The masses of the obtained coarse-grained product 2, fine-grained product, magnetized material 1, non-magnetized material 1, and magnetized material 2 were measured using an electromagnetic balance (product name: GX-8K, manufactured by A&D Corporation) after drying at 105°C for 1 hour.The fine-grained product, magnetized material 1, non-magnetized material 1, and magnetized material 2 were then heated and dissolved in aqua regia, and analyzed using a high-frequency inductively coupled plasma optical emission spectrometer (SPECTROGREEN FMX46, manufactured by Hitachi High-Tech Science Corporation) to determine the cobalt and nickel grades.

[0080] <Calculation of cobalt and nickel recovery rates> The recovery rates of cobalt and nickel recovered in magnetized material 1 and magnetized material 2 were calculated by setting the total amount of cobalt and the total amount of nickel contained in coarse product 2, magnetized material 1, non-magnetized material 1, and magnetized material 2 to 100%, respectively.

[0081] Example 2 In Example 1, cobalt and nickel were recovered in the same manner as in Example 1, except that the non-magnetized material slurry 1 (slurry concentration: 30 mass%) obtained in the first magnetic separation step was subjected to a second magnetic separation step using a drum-type wet magnetic separator (manufactured by Japan Eriez Magnetics Co., Ltd., model: WD REX1.5φ×12W) shown in FIG. 3 at a magnetic flux density of 0.6 T and a drum rotation speed of 5 rpm. The drum-type wet magnetic separation device shown in Figure 3 has a magnet placed at the 3 o'clock position on the drum, and a slurry of non-magnetic material 1 is added from the 12 o'clock to 2 o'clock direction (top) of the drum, and magnetic separation is performed while the drum is rotated counterclockwise. Next, the cobalt grade and nickel grade, and the recovery rates of cobalt and nickel were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0082] Example 3 In Example 1, cobalt and nickel were recovered in the same manner as in Example 1, except that the non-magnetized material slurry 1 (slurry concentration: 30 mass%) obtained in the first magnetic separation step was subjected to a second magnetic separation step using a drum-type wet magnetic separator (manufactured by Japan Eriez Magnetics Co., Ltd., model: WD REX1.5φ×12W) shown in FIG. 3 at a magnetic flux density of 0.6 T and a drum rotation speed of 20 rpm. The drum-type wet magnetic separation device shown in Figure 3 has a magnet placed at the 3 o'clock position on the drum, and a slurry of non-magnetic material 1 is added from the 12 o'clock to 2 o'clock direction (top) of the drum, and magnetic separation is performed while the drum is rotated counterclockwise. Next, the cobalt grade and nickel grade, and the recovery rates of cobalt and nickel were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0083] Example 4 In Example 1, cobalt and nickel were recovered in the same manner as in Example 1, except that the non-magnetized material slurry 1 (slurry concentration: 15 mass %) obtained in the first magnetic separation step was subjected to a second magnetic separation step using a drum-type wet magnetic separator (manufactured by Japan Eriez Magnetics Co., Ltd., model: WM REX1.5φ×12W) shown in FIG. 3 at a magnetic flux density of 0.6 T and a drum rotation speed of 5 rpm. Next, the cobalt grade and nickel grade, and the recovery rates of cobalt and nickel were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0084] Example 5 In Example 1, cobalt and nickel were recovered in the same manner as in Example 1, except that the non-magnetized material slurry 1 (slurry concentration: 15 mass%) obtained in the first magnetic separation step was subjected to a second magnetic separation step using a drum-type wet magnetic separator (manufactured by Japan Eriez Magnetics Co., Ltd., model: WM REX1.5φ×12W) shown in FIG. 3 at a magnetic flux density of 0.6 T and a drum rotation speed of 20 rpm. Next, the cobalt grade and nickel grade, and the recovery rates of cobalt and nickel were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0085] Example 6 In Example 1, cobalt and nickel were recovered in the same manner as in Example 1, except that the non-magnetized material slurry 1 (slurry concentration: 15% by mass) obtained in the first magnetic separation step was subjected to the second magnetic separation step using a high gradient wet magnetic separator (manufactured by Japan Eriez Magnetics Co., Ltd., model: L-4) at an air-core magnetic flux density of 0.3 T. The high-gradient wet magnetic separation device used was a matrix member (200 mm wide × 50 mm long × 28 mm thick) shown in Figure 7, which was made by stacking three horizontal iron matrices (line width: 2 mm, thickness: 4 mm, 200 mm wide × 50 mm long) shown in Figure 6A and four vertical iron matrices (maximum diamond length: 22 mm, minimum diamond length: 10 mm, thickness: 4 mm, 200 mm wide × 50 mm long) shown in Figure 6B alternately. The matrix member was placed in the container shown in Figure 5 and attached through the matrix inlet shown in Figure 4. Next, the cobalt grade and nickel grade, and the recovery rates of cobalt and nickel were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0086] Example 7 In Example 6, cobalt and nickel were recovered in the same manner as in Example 6, except that the non-magnetized material slurry 1 (slurry concentration: 15% by mass) obtained in the first magnetic separation step was subjected to the second magnetic separation step using a high gradient wet magnetic separator (manufactured by Japan Eriez Magnetics Co., Ltd., model: L-4) at an air-core magnetic flux density of 0.6 T. Next, the cobalt grade and nickel grade, and the recovery rates of cobalt and nickel were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0087] Example 8 In Example 6, cobalt and nickel were recovered in the same manner as in Example 6, except that the non-magnetized material slurry 1 (slurry concentration: 15% by mass) obtained in the first magnetic separation step was subjected to the second magnetic separation step using a high gradient wet magnetic separator (manufactured by Japan Eriez Magnetics Co., Ltd., model: L-4) at an air-core magnetic flux density of 1.2 T. Next, the cobalt grade and nickel grade, and the recovery rates of cobalt and nickel were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0088] Example 9 In Example 1, cobalt and nickel were recovered in the same manner as in Example 1, except that the first magnetic separation step was carried out using a drum-type wet magnetic separation device (manufactured by Japan Eriez Magnetics Co., Ltd., model: WM REX 1.5φ×12W) shown in FIG. 2 at a magnetic flux density of 0.6 T and a drum rotation speed of 40 rpm. Next, the cobalt grade and nickel grade, and the recovery rates of cobalt and nickel were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0089] (Comparative Example 1) Cobalt and nickel were recovered in the same manner as in Example 1, except that the second magnetic separation step was not carried out. Next, the cobalt grade and nickel grade, and the recovery rates of cobalt and nickel were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0090] [Table 1] [Table 2]

[0091] The results in Tables 1 and 2 show that even when the cobalt and nickel contents of the fine product slurry, which is the subject of magnetic separation, are low, in Examples 1 to 8, cobalt and nickel can be recovered at a high recovery rate by performing a second magnetic separation after the first magnetic separation.

Claims

1. a heat treatment step of heat treating the lithium ion secondary battery to obtain a heat-treated product; a first classification step of crushing the heat-treated product and classifying the crushed product to obtain a coarse product 1 and a fine product; a grinding step of grinding the fine product to obtain a ground product; a second classification step in which the pulverized product is classified at a classification point smaller than the classification point of the first classification step to obtain a coarse product 2 and a fine product; a first magnetic separation step in which the fine product obtained in the second classification step is magnetically separated to obtain magnetic materials 1 and non-magnetic materials 1; a second magnetic separation step in which the non-magnetized materials 1 obtained in the first magnetic separation step are magnetically separated to obtain magnetized materials 2 and non-magnetized materials 2; a recovery step of recovering valuable materials from the magnetized materials 1 and 2; Including, A method for recovering valuable materials from a lithium ion secondary battery, characterized in that the second magnetic separation step is carried out by wet magnetic separation.

2. 2. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1, wherein the first classification step is performed at a classification point of 600 μm or more and 2,400 μm or less.

3. 3. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1, wherein the fine product is pulverized in a wet manner.

4. 3. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1, wherein the second classification step is performed at a classification point of 25 μm or more and 1,700 μm or less.

5. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1 or 2, wherein the first magnetic separation step is performed in a wet state.

6. the magnetic flux density of the magnetic separation in the first magnetic separation step is 0.1 T or more and less than 0.3 T; 3. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1, wherein a magnetic flux density for magnetic separation in the second magnetic separation step is 0.3 T or more and 2 T or less.

7. 3. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1, wherein the combined value of the cobalt content and the nickel content of the non-magnetized material 1 is 30 mass% or less.

8. 3. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1, wherein at least one of cobalt and nickel contained in the non-magnetized material 1 has a number average particle size of 50 μm or less.

9. 3. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1, wherein the second magnetic separation step is carried out by adding a dispersant to the non-magnetized material 1 obtained in the first magnetic separation step.

10. 3. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1, wherein in the recovery step, the magnetized materials 1 and 2 are washed and subjected to solid-liquid separation to recover valuable materials.

11. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1 or 2, wherein copper is recovered from the coarse product (2).

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