Recovery method of valuable metal from waste lithium-ion batteries

Abstract

To provide a recovery method of valuable metal in which valuable metal can be recovered from waste lithium-ion batteries at a high content.SOLUTION: A recovery method of valuable metal from waste lithium-ion batteries includes: a first step of roasting waste lithium-ion battery; a second step of crushing a roasted product to select black mass; and a third step of performing air flow classification while applying physical impact to black mass or performing air flow classification or sieving after applying physical impact to black mass.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In recent years, the demand for lithium-ion batteries has been increasing in industrial fields such as automobiles, mobile phones, and household electrical appliances. Lithium-ion batteries contain valuable metals such as lithium, nickel, manganese, cobalt, copper, and aluminum, so recovering these valuable metals from used lithium-ion batteries is extremely beneficial for Japan, a country with few resources. Therefore, in order to recover valuable metals from used lithium-ion batteries, separation and recovery are carried out by roasting, crushing or pulverization, sieving, sorting, etc.

[0003] For example, Patent Document 1 reports that valuable metals with high contents of cobalt and nickel can be obtained at a high recovery rate by heat-treating lithium-ion secondary batteries, crushing the heat-treated material, classifying the crushed material at a predetermined classification point into a coarse product and an intermediate product, and classifying the intermediate product at a predetermined classification point into a medium product and a fine product. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-182724 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional methods, the recovery rate of valuable metals may fall below a certain level depending on the type of used lithium-ion batteries. Therefore, in order to increase the recovery rate of valuable metals, it is possible to consider multi-stage processing, but this makes the process complicated and increases energy and costs. Therefore, an object of the present invention is to provide a method for recovering valuable metals capable of recovering valuable metals at a high content from waste lithium ion batteries. [Means for solving the problem]

[0006] The present inventors have conducted various studies in consideration of the above problems, and have found that valuable metals can be efficiently recovered at a high content from waste lithium-ion batteries by roasting waste lithium-ion batteries, crushing the roasted material, separating the black mass, subjecting the black mass to a physical impact to disintegrate it into a form of primary particles, and then air classifying the black mass. Here, in this specification, "black mass" refers to a fraction of fine particles separated from the roasted material of lithium-ion batteries, and is a powder in which metals such as nickel, manganese, cobalt, lithium, aluminum, iron, etc., as well as carbon, are concentrated.

[0007] That is, the present invention provides the following [1] to [5]. [1] A first step of roasting waste lithium-ion batteries; a second step of crushing the roasted material and separating the black mass; A third step of air classifying the black mass while subjecting it to physical impact, or air classifying or sieving the black mass after subjecting it to physical impact. A method for recovering valuable metals from waste lithium-ion batteries, comprising: [2] The method for recovering the above-described [1], wherein the third step is a step of subjecting the resulting mixture to the following (1) or (2). (1) Classify the black mass using a swirling airflow sieve. (2) The black mass is crushed using a dry grinding machine, and the crushed material is classified using a cyclone classifier or a sieve. [3] The recovery method according to [1] or [2] above, wherein the classification point or sieve opening in the air classification is 50 μm or less. [4] The method according to any one of the above [1] to [3], wherein the dry grinding machine is a jet mill, a pin mill or a hammer mill. [5] The method for recovering valuable metals according to any one of [1] to [4] above, wherein the valuable metal is one or more selected from nickel, manganese, cobalt, and lithium. Effect of the Invention

[0008] According to the present invention, valuable metals can be efficiently recovered at a high content from discarded lithium ion batteries. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The method for recovering valuable metals from used lithium ion batteries of the present invention includes steps 1, 2, and 3. Each step will be described in detail below.

[0010] <First step> The first step is to roast waste lithium-ion batteries. (Waste lithium-ion batteries) The used lithium ion batteries that are the subject of the present invention are lithium ion batteries that can be used in electric vehicles, hybrid vehicles, mobile phones, and various other electronic devices, and are discarded due to product life, manufacturing defects, or other reasons. The used lithium ion batteries may be in the form of a battery module disassembled or in the form of a battery pack containing multiple modules. Note that one or more types of used lithium ion batteries can be used.

[0011] The waste lithium ion battery is composed of a positive electrode material, a negative electrode material, an electrolyte, a separator, and the like. Examples of the positive electrode material include iron phosphate (LiFePO4), cobalt (LiCoO2), nickel (LiNiO2), manganese (LiMn2O4), and ternary (Li(Ni-Mn-Co)O2). In this specification, the term "ternary" refers to lithium cobalt oxide in which part of the cobalt is replaced with nickel and manganese. The positive electrode material may include, for example, an aluminum foil (positive electrode substrate) fixed with an organic binder such as polyvinylidene fluoride. Examples of the negative electrode material include carbon and lithium titanate. The negative electrode material may include, for example, a copper foil (negative electrode substrate) fixed with a polyacrylic binder. The electrolyte is not particularly limited, and an organic electrolyte obtained by dissolving a lithium salt in an organic solvent may be used as the electrolyte. Examples of the separator include a polyethylene film and a polypropylene film. The exterior that encases the lithium ion battery may be a case made of only aluminum, a case containing aluminum and iron, or an aluminum laminate. The lithium ion battery may contain metals such as copper and iron. Furthermore, the lithium ion battery may contain a resin box-shaped case that houses a battery module in which multiple lithium ion battery cells are arranged, or a battery pack in which multiple battery modules are connected.

[0012] (Roasting) Roasting is carried out for the purpose of deactivating the remaining electrical capacity and thermally decomposing the flammable electrolyte, resin, etc., to remove and render harmless harmful substances. The roasting can be carried out using a heating furnace. Examples of the heating furnace include a burner-heated fixed furnace, an externally heated rotary kiln furnace, a fluidized bed furnace, a tunnel furnace, a muffle furnace, a cupola furnace, and a stoker furnace. The roasting can be carried out by treating the waste lithium-ion batteries in their original form without distinguishing between battery cells, battery modules, battery packs, and the like.

[0013] The roasting may be performed in a non-oxidizing or reducing atmosphere by circulating nitrogen gas, argon gas, CO, CO2, or other gases in the heating furnace. In addition, since harmful fluorine compounds such as hydrogen fluoride may be generated in the heating furnace during roasting, a gas treatment mechanism may be provided. For example, the gas generated by roasting may be transferred to a secondary combustion furnace such as a cement kiln and reacted with calcium to fix it as calcium fluoride.

[0014] The roasting temperature is preferably higher than the thermal decomposition temperature of the resin and lower than the melting point of the metal constituting the battery casing, for example, preferably 300°C or higher, more preferably 350°C or higher, further preferably 400°C or higher, and preferably 650°C or lower, more preferably 600°C or lower, further preferably 550°C or lower.

[0015] The roasting time is not particularly limited, and can be appropriately selected depending on the amount, shape, size, etc. of the waste lithium-ion batteries to be treated. For example, it is preferably 0.5 hours or more, more preferably 1 hour or more, even more preferably 2 hours or more, and is preferably 10 hours or less, more preferably 7 hours or less, and even more preferably 5 hours or less.

[0016] <Second step> The second step is to crush the roasted material and separate the black mass. (Crushing) The roasted materials are crushed for the purpose of destroying the strong casing of the lithium-ion battery and separating the active materials containing valuable metals from the other constituent materials. Note that the term "crushing" as used here is a concept that includes not only crushing the roasted materials but also dismantling the roasted materials. For crushing, an industrial crusher can be used, and it may be either an impact crusher or a shear crusher. For example, a sample mill, a hammer mill, a pin mill, a wing mill, a tornado mill, or a hammer crusher may be mentioned. Among them, a shear crusher that shears and crushes with a fixed blade and a movable blade, or a movable blade and a movable blade, is preferable. For example, a single-shaft or double-shaft shredder may be mentioned, but three or more shafts may also be used. The shear crusher may be either a horizontal type or a vertical type. Crushing can be carried out until the average particle size of the crushed material reaches, for example, about 10 to 20 mm.

[0017] (Sorting) The inventors have found that when the average particle size of the crushed material is within the above range, the active material such as valuable metals is present as fine particles. Therefore, the crushed material can be sieved to select the concentrated valuable metals. This makes it possible to recover black mass, which is the undersize mass and is a concentrated active material such as valuable metals.

[0018] For the sieving, a sieve or a sieve separator can be used. As the sieve, for example, one conforming to the JIS Z 8801 standard can be used. As the sieve separator, an industrial device can be used, and for example, any of a vibration type, an in-plane motion type, a rotary type, and a fixed type can be used, and is not particularly limited.

[0019] The particle size of the undersize particles is preferably 3 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less. The lower limit of the particle size is not particularly limited. For example, the present inventors have confirmed that when the crushed material is sieved using a sieve with a mesh size of 1.0 mm conforming to the JIS Z 8801 standard, a powdered black mass containing concentrated valuable metals such as cobalt and nickel is obtained as the undersize particles.

[0020] <Third process> The third step is a step of performing air classification while applying a physical impact to the black mass, or performing air classification or sieving after applying a physical impact to the black mass. Conventionally, wet classification has been adopted as a method for disintegrating agglomerates contained in black mass, but the present inventors have confirmed that the agglomerates can be returned to the form of primary particles by disintegrating the black mass by applying a physical impact. They have also found that valuable metals such as cobalt, manganese, and nickel are abundantly contained in the finer particles of the primary particles, and that valuable metals such as cobalt, manganese, and nickel can be efficiently recovered at a high content by subjecting the material to airflow dry classification or sieving. Note that "disintegration" is a different concept from "pulverization," which is the process of finely crushing the material into powder between blades.

[0021] In this step, from the viewpoint of efficiently recovering valuable metals at a high content, it is preferable to subject the process to the following (1) or (2). This makes it easier to crush the black mass into primary particles, and by separating the crushed material into coarse powder and fine powder by air classification, the fine powder in which valuable metals are concentrated can be efficiently recovered. (1) Classify the black mass using a swirling airflow sieve. (2) The black mass is crushed using a dry grinding machine, and the crushed material is classified using a cyclone classifier or sieving.

[0022] In the process (1), a swirling airflow type sieving machine is used. The swirling airflow breaks down the black mass into primary particles, and the finer particles can quickly pass through the sieve mesh. This prevents clogging and allows a high content of valuable metals to be recovered in a short period of time. The swirling airflow type sieving machine is not particularly limited as long as it can disintegrate a sample into primary particles by a swirling flow and classify the sample by airflow. For example, a Spin Air Sieve (manufactured by Seishin Enterprise Co., Ltd.) can be used.

[0023] In addition, the dry grinding mill used in the step (2) is used for the purpose of crushing the black mass into primary particles. The dry grinding machine is not particularly limited as long as it can crush the black mass into primary particles, but examples thereof include a jet mill, a pin mill, and a hammer mill. Among these, a jet mill is preferred because it can efficiently crush the black mass into primary particles. Then, in the step (2), the crushed material is classified using a cyclone classifier or sieved using a sieve. The cyclone classifier is not particularly limited as long as it can classify the crushed material by a swirling air current, and an industrial device can be used. The sieve used should be one conforming to the JIS Z 8801 standard.

[0024] The classification point or sieve opening in air classification is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, and even more preferably 20 μm or less, from the viewpoint of recovering valuable metals including cobalt, manganese, nickel, etc. at a high content. The "classification point" here refers to the 50% separation diameter, and the "50% separation diameter" refers to the particle size at which the distribution rate to the fine powder side is 50%. For example, a classification point of 30 μm means that 50% of particles of 30 μm or less can be recovered as fine powder. By recovering the fine powder and undersize material from the swirling airflow sieving machine and cyclone classifier, valuable metals rich in cobalt, manganese, nickel, etc. can be efficiently recovered.

[0025] After the third step, the recovered material from the third step may be sieved in order to increase the content of valuable metals. The sieving can be performed using a sieve or a sieve separator. Specific examples of the sieve and the sieve separator are as described above. From the viewpoint of improving the content of valuable metals, the mesh size is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. By recovering the undersize fraction, valuable metals such as cobalt, manganese, and nickel can be obtained at high contents. EXAMPLES

[0026] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0027] 1. Test sample As the waste lithium-ion battery, an in-vehicle battery module was used which was composed of an assembly of laminated battery cells and contained the following active materials as electrode materials: (1) Automotive battery module A: Positive electrode is NMC ternary material, negative electrode is carbon (2) Vehicle battery module B: Positive electrode is NMC ternary material, negative electrode is lithium titanate

[0028] 2.Equipment used (1) Swirling airflow sieving machine: Spin Air Sieve SAR-75, manufactured by Seishin Enterprises (2) JIS Z 8801 standard sieve: mesh size 1.0 mm, 45 μm, 20 μm (3) X-ray fluorescence analyzer: ZSX Primus II, manufactured by Rigaku

[0029] Example 1 The vehicle-mounted battery module A was placed in a basket and roasted in a rotary bed kiln at 500°C for 4 hours. After cooling, the roasted material was crushed by shearing, sieved through a 1.0 mm mesh sieve conforming to JIS Z 8801, and the undersieve (black mass) was collected. Next, a 20 μm mesh sieve conforming to JIS Z 8801 was set in a rotating airflow sieving machine, and the undersieve was air-classified, and the fine powder was collected.

[0030] Comparative Example 1 The crushed material was sieved through a sieve with 1.0 mm openings to obtain black mass, and the remaining mass was sieved through a sieve with 45 μm openings conforming to JIS Z 8801 standard instead of using a swirling airflow sieving machine, and the undersize material was recovered in the same manner as in Example 1. In this comparative example, a sieve with 45 μm openings was used in order to obtain a recovery amount approximately equal to that of Example 1.

[0031] Example 2 The undersize particles were collected in the same manner as in Example 1, except that the vehicle-mounted module B was used.

[0032] Comparative Example 2 Except for using the vehicle-mounted module B, the undersize material was collected by the same operation as in Comparative Example 1. In this Comparative Example, a sieve with an opening of 45 μm was used in order to obtain a recovery amount approximately equal to that in Example 2.

[0033] 〔evaluation〕 After measuring the amount of the undersieve recovered, the mass ratios of nickel (Ni) and cobalt (Co) were measured using an X-ray fluorescence analyzer (ZSX Primus II, Rigaku Corporation) after correcting for the ignition loss at 850°C. Table 1 shows the results before and after classification.

[0034] [Table 1]

[0035] Table 1 shows the analysis results of the undersize fraction recovered by sieving, and the nickel and cobalt contents of the working example are both higher than those of the comparative example. These results show that valuable metals can be concentrated in greater amounts in the undersize fraction by subjecting the sample to physical impact to crushing and turning it into primary particles, and then air classifying it.

Claims

1. A first step of roasting waste lithium ion batteries; a second step of crushing the roast and separating the black mass; A third step of air classifying the black mass while subjecting it to physical impact, or of air classifying or sieving the black mass after subjecting it to physical impact. A method for recovering valuable metals from waste lithium-ion batteries, comprising:

2. The method for recovering the refrigerant according to claim 1, wherein the third step is a step of subjecting the refrigerant to the following (1) or (2): (1) Classify the black mass using a swirling airflow sieve. (2) Crushing the black mass using a dry grinding mill, and classifying the crushed material using a cyclone classifier or a sieve.

3. 2. The method according to claim 1, wherein the classification point in the air classification or the mesh size of the sieve is 50 μm or less.

4. 2. The method according to claim 1, wherein the dry grinding machine is a jet mill, a pin mill or a hammer mill.

5. The method according to any one of claims 1 to 4, wherein the valuable metal is one or more selected from nickel, manganese, cobalt and lithium.

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