JP2023177725A - Metal recovery method from lithium ion battery - Google Patents

Abstract

To provide a method for efficiently and readily recovering metal (lithium, manganese) from waste residues of lithium-ion batteries in a leaching process before solvent extraction.SOLUTION: The inventive method is a method for recovering metal from a lithium ion battery that includes, as a positive electrode active material, lithium (Li), cobalt (Co) and nickel (Ni) and, as a negative electrode active material, graphite (C). The method includes a step (a) of preparing a waste residue of a lithium-ion battery that, in X-ray diffraction (XRD) measurement, has a ratio (A/B) of peak intensity A at a diffraction angle 18.7° and peak intensity B at 26.5°within a range of 0-0.15 and also includes either a step (b1) for dispersing the waste residue in water and leaching lithium for 2-24 hours in a leaching solution at 30-80°C or, (b2) dispersing the waste residue in a sulphuric acid solution with 1-3 mass% concentration and leaching lithium and manganese for 0.5-24 hours in the leaching solution at 30-80°C.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for recovering metals from lithium ion batteries, and specifically to a method for recovering metals from lithium ion battery slag, and more specifically to a method for recovering metals from lithium ion battery slag. Regarding the method of collection.

Lithium ion batteries are used in many industrial fields including various electronic devices, and those that use a lithium metal composite oxide containing manganese, nickel, and cobalt as a positive electrode material are generally known. In recent years, as the amount of batteries used has increased and the range of use has expanded, the amount of batteries that are discarded due to product life or defects during the manufacturing process is increasing. Under such circumstances, it is desired to easily recover expensive elements such as nickel and cobalt from lithium ion batteries, which are discarded in large quantities, for reuse at a relatively low cost.

In order to process lithium-ion batteries for the recovery of valuable metals, there is a conventional and common method, for example, in which lithium-ion batteries are first subjected to various steps such as roasting, crushing, and sieving as necessary. Prepare powdered or granular lithium ion battery slag. The battery slag is leached with an acid, and lithium, nickel, cobalt, manganese, iron, copper, aluminum, etc. that may be contained therein are dissolved in the solution to obtain a leachate. A solvent extraction method is performed on the leachate to sequentially separate each metal element. The iron and aluminum are recovered first, followed by the manganese and copper, then the cobalt, then the nickel, and finally the lithium, leaving it in the aqueous phase.

In conventional methods, lithium is generally recovered after solvent extraction as described above, but as an example of a method in which lithium can be recovered in a leaching step before solvent extraction, for example, Patent Documents 1 and 2 below are disclosed. be. Patent Document 1 discloses a method for heat treatment of battery waste containing lithium and a method for recovering lithium. In the heat treatment method of Document 1, an atmospheric gas containing oxygen and at least one selected from the group consisting of nitrogen, carbon dioxide, and water vapor is caused to flow in a heat treatment furnace in which battery waste is placed, thereby increasing the oxygen partial pressure in the furnace. Heat the battery waste while adjusting the temperature. The lithium recovery method of Document 1 includes a lithium leaching step in which lithium in battery powder obtained from battery waste after a heat treatment step is leached with a weakly acidic solution, water, or an alkaline solution.

Patent Document 2 discloses a method for recovering lithium from battery slag obtained by roasting lithium ion battery waste. The recovery method involves a leaching step in which battery slag containing lithium aluminate is leached into an acidic solution, and the pH of the leached solution obtained in the leaching step is raised to neutralize it and solid-liquid separation is carried out to remove lithium. and a neutralization step to obtain a solution.

JP2021-193645 JP2019-160429

Patent Documents 1 and 2 are both methods in which lithium can be recovered in a leaching step before solvent extraction, but they do not disclose any information regarding the type of negative electrode active material of lithium ion batteries, and they do not disclose any information regarding the type of negative electrode active material of lithium ion batteries. There is no mention of manganese recovery in the previous leaching process.

In Patent Document 1, the composition of lithium ion battery slag is not analyzed/clarified and its composition is unclear, and in the example, the recovery (leaching) rate of lithium is about 50 to 60% (paragraph "0048"). It's staying.

Patent Document 2 shows analysis results by X-ray diffraction (XRD) in order to confirm the presence or absence of lithium aluminate in lithium ion battery slag (paragraph "0025", FIG. 2), etc. The relationship between the composition and the lithium recovery rate is not disclosed.

The present invention has been made in view of the above-mentioned circumstances of the prior art, and its purpose is to efficiently and easily remove metals (lithium, manganese, ).

One aspect of the present invention is a method for recovering metal from a lithium ion battery containing lithium (Li), cobalt (Co), and nickel (Ni) as a positive electrode active material and graphite (C) as a negative electrode active material, the method comprising: , (a) In X-ray diffraction (XRD) measurement, the ratio (A/B) of peak intensity A at a diffraction angle of 18.7° and peak intensity B at 26.5° is in the range of 0 to 0.15. , provides a method comprising the steps of: preparing battery sludge for a lithium ion battery; and (b) dispersing the battery sludge in water and leaching lithium into a leaching solution at 30 to 80° C. for 2 to 24 hours. do.

Another embodiment of the present invention is a method for recovering metal from a lithium ion battery containing lithium (Li), cobalt (Co), and nickel (Ni) as positive electrode active materials and graphite (C) as negative electrode active material. (a) In X-ray diffraction (XRD) measurement, the ratio (A/B) of peak intensity A at a diffraction angle of 18.7° and peak intensity B at 26.5° is in the range of 0 to 0.15. (b) Dispersing the battery slag in an aqueous sulfuric acid solution with a concentration of 1 to 3% by mass and soaking it in a leachate at 30 to 80°C for 0.5 to 24 hours. leaching lithium and manganese over the process.

In each of the other aspects of the present invention, the battery slag (i) has a peak caused by CoNi in X-ray diffraction (XRD) measurement, or has a peak caused by one or both of Li ₂ CO ₃ and Co ₃ O ₄ (ii) contains 10 to 35% by mass of graphite (C), or the positive electrode active material contains manganese (Mn).

In another aspect of the present invention, the step (a) of preparing battery slag for a lithium ion battery includes (a1) heating the lithium ion battery in the atmosphere in a heating furnace at a temperature of 500 to 600°C to (a2) A pulverization step in which the heat-treated lithium ion battery is pulverized to obtain a pulverized product; (a3) A sieving step in which the pulverized product is sieved to obtain powdered lithium ion battery slag. and, including.

In another aspect of the present invention, the heat treatment step (a1) is performed using an atmosphere of an inert gas or superheated steam having an oxygen concentration of 1 to 21% by volume, and an oxygen concentration of 1 to 3% by volume, instead of the atmosphere inside the heating furnace. % by volume of inert gas or superheated steam.

According to the present invention, it becomes possible to efficiently and easily separate/recover lithium/manganese from battery slag of a lithium ion battery in a leaching step before solvent extraction.

1 is a diagram showing steps of a method for recovering metal from a lithium ion battery according to an embodiment of the present invention. FIG. It is a figure showing the process of the manufacturing method of lithium ion battery slag (BM) of one embodiment of the present invention. It is a figure showing the result of X-ray diffraction (XRD) measurement of lithium ion battery slag (BM) of one embodiment of the present invention.

Embodiments of the present invention will be described with reference to the drawings and tables. FIG. 1 is a diagram showing the steps of a method for recovering metal from a lithium ion battery according to an embodiment of the present invention. First, an overview (flow) of the recovery method of the present invention will be explained with reference to FIG.

In step S1, battery slag (hereinafter also referred to as lithium ion battery slag or simply battery slag) of a lithium ion battery is prepared. The lithium ion battery used as a raw material contains lithium (Li), cobalt (Co), and nickel (Ni) as a positive electrode active material, and graphite (C) as a negative electrode active material. Further, the positive electrode active material can include manganese (Mn). Graphite (C) can be contained in the battery slag in an amount of 10 to 35% by mass. In X-ray diffraction (XRD) measurement, battery slag has a ratio (A/B) of peak intensity A at a diffraction angle of 18.7° to peak intensity B at 26.5° in the range of 0 to 0.15. prepare things. The details will be described later, but the reason to focus on this peak intensity ratio (A/B) is that it is an indicator of the ease with which lithium (Li) can be taken out (leached) due to the collapse of the crystal structure of the positive electrode active material of a lithium ion battery. This is because. Furthermore, battery slag is characterized in that it has a peak due to CoNi or a peak due to one or both of Li ₂ CO ₃ and Co ₃ O ₄ in X-ray diffraction (XRD) measurement.

In step S2, the battery slag obtained in step S1 is dispersed in water, and lithium is leached into a leachate at 30 to 80° C. over a period of 2 to 24 hours. By leaching using this water (warm water), only Li can be leached while almost completely suppressing leaching of Co, Ni, and Mn. The content of battery sludge in the water slurry is preferably about 50 to 150 g/L, preferably about 80 to 120 g/L. This is because if the content is too low, the amount of treatment (leaching) will be too low, resulting in poor treatment efficiency, while if the content is too high, stirring of the slurry will not be sufficient and the uniformity of the reaction will decrease.

In step S3, the battery slag obtained in step S1 is dispersed in an aqueous sulfuric acid solution with a concentration of 1 to 5% by mass, and Li and Mn are leached into a leachate at 30 to 80° C. for 0.5 to 24 hours. . Step S3 can be performed in place of or in parallel with step S2. By leaching using this dilute aqueous sulfuric acid solution, Li and Mn can be leached out while suppressing leaching of Co and Ni. The content of battery sludge in the sulfuric acid aqueous solution slurry is preferably about 50 to 150 g/L, preferably about 80 to 120 g/L, for the same reason as for water.

The concentration of dilute sulfuric acid is greater than 0 and 8% by mass or less, preferably 1 to 3% by mass. This is because if the sulfuric acid concentration is too high, the amount of Co and Ni leached into dilute sulfuric acid will be too large, making separation from Li poor. The leaching time is 0.25 to 24 hours, preferably 0.25 to 2 hours, more preferably 0.25 to 1 hour. The leaching temperature is preferably room temperature to 100°C, preferably 30°C to 80°C, more preferably 60°C to 80°C. When dilute sulfuric acid is used, the dilute sulfuric acid concentration, leaching temperature, and leaching time affect the recovery (leaching) rate of Li, Co, and Ni, so these should be adjusted depending on the composition of the battery slag and the peak intensity ratio (A/B). , it is preferable to adjust as appropriate.

When battery slag is leached into dilute sulfuric acid, Li, Mn, Co, and Ni are leached out at the beginning of leaching, and the recovery (leaching) rate of Co and Ni tends to decrease as time passes. Further, as the temperature is higher, the leaching rate of Co and Ni tends to decrease faster, and the recovery (leaching) of Li and Mn tends to decrease, but does not decrease significantly. As leaching with dilute sulfuric acid progresses, the pH of the leachate increases. It is thought that immediately after the start of leaching, leaching of Li, Mn, Co, and Ni begins, and the pH also begins to rise. Co and Ni are thought to precipitate as the pH increases, and this precipitation reduces the apparent recovery (leaching) rate of Co and Ni. This reaction proceeds faster at higher temperatures, so the higher the temperature, the shorter the time required to separate Li, Mn from Co and Ni. Mn exhibits the same leaching rate as Li when the leaching time is less than 2 hours. As the reaction time becomes longer, the recovery (leaching) rate of Mn tends to decrease.

In step S4, the Li leached out in step S2 is recovered. Recovery can be carried out in the form of lithium carbonate or lithium hydroxide by known methods such as neutralization and carbonation. In step S5, Li and Mn leached out in step S3 are separated and recovered. Li and Mn can be separated by appropriately adjusting the pH and oxidation-reduction potential (ORP) of the leachate. For example, by adjusting the pH to a range of 3.0 to 10.0, more preferably 3.5 to 7.0, and setting the ORP to 400 to 600 mV (V vs.Ag/AgCl), Mn can be converted into Mn oxide. It can be precipitated as a liquid and separated from Li ions in the liquid. Note that Co and Ni leached simultaneously with Li and Mn can be precipitated and recovered as Co and Ni hydroxides by further adjusting the pH after separation of Mn.

FIG. 2 is a diagram showing the steps of a method for manufacturing lithium ion battery slag according to an embodiment of the present invention prepared in step S1 of FIG. The method for producing lithium ion battery slag and its characteristics will be described below with reference to FIG.

In step S11, a lithium ion battery as a raw material is prepared. Lithium ion batteries of interest can include lithium ion batteries that can be used in various machines and devices such as mobile phones, smartphones, notebook PCs, various other electronic devices, and automobiles. These include lithium-ion batteries that have been collected from the market at the end of their lifespan, poorly manufactured lithium-ion batteries, positive and negative electrodes, defective materials including positive active materials, positive active materials, positive active material precursors, etc. may be used alone or in combination. However, the following requirements (1) to (3) must be met.

(1) The positive electrode active material is lithium cobalt oxide (LCO), which may contain lithium (Li), cobalt (Co), nickel (Ni), or manganese (Mn), or nickel, which is a ternary positive electrode active material.・Applicable to cobalt manganese (NCM), nickel cobalt aluminum (NCA), or nickel cobalt manganese aluminum (NCMA). Iron phosphate (olivine iron) is not covered.

(2) Graphite (C) is used as the negative electrode active material. Hereinafter, it will also be referred to as "graphite" or "C" in this specification. Graphite is most likely functioning as a reducing agent, so a sufficient amount of graphite must be included before heating. Therefore, graphite needs to be contained in the lithium ion battery slag in an amount of 10 to 35% by mass, more preferably 20 to 32% by mass. This is because if it is less than 10% by mass, the reduction effect of Co and Ni will be insufficient, and if it exceeds 35% by mass, the content of the metal to be recovered will be low. A lithium ion battery in which the negative electrode active material is composed only of graphite may be selected. On the premise that the required amount of graphite remains, negative electrode active materials other than graphite such as lithium titanate, lithium niobate, and silicon oxide may be mixed. Further, iron (Fe) or copper (Cu) may be included.

(3) As other lithium ion battery components, ordinary ones can be used. For example, aluminum foil (positive electrode base material) on which a positive electrode active material is coated and fixed with polyvinylidene fluoride (PVDF) or other organic or water-based binders, or a case containing aluminum as an exterior wrapping around a lithium-ion battery. may be included.

The lithium ion battery is preferably discharged to, for example, 3V or less. The discharge method may be any method that allows discharge, such as discharging by immersing it in salt water (5 to 20 mass % NaCl aqueous solution), discharging with a discharge machine having a discharge function, discharging by connecting a resistor, etc. The voltage adjustment function of a battery management system (BMS) for in-vehicle use or stationary use may also be used. In the case of salt water discharge, electrolyte removal may be performed by diffusing the electrolyte into salt water. After discharge, preliminary heating or main heating (heat treatment) in the next step is performed directly. In the preheating, the lithium ion battery can be heated, for example, at about 250 to 350° C., and the electrolyte can be evaporated before the main heating.

In step S12, the lithium ion battery prepared in step S11 is heat-treated. The heat treatment referred to here is used in the same sense as roasting, calcination, etc., and the lithium ion battery is heated in a heating furnace in the atmosphere (oxygen concentration: approximately 21% by volume) or in an atmosphere with a controlled oxygen concentration. means heating at a temperature of The atmosphere in which the oxygen concentration is controlled is, for example, an inert gas (eg, nitrogen or superheated steam) atmosphere containing 1 to 21% by volume of oxygen, preferably a superheated steam atmosphere containing 1 to 3% by volume of oxygen. When using a lithium ion battery with residual electrolyte as a raw material, it is preferable to control the oxygen concentration to 1 to 3% by volume.

The predetermined temperature is, for example, 450 to 650°C, preferably 500 to 600°C. Since graphite is oxidized at temperatures exceeding 600°C, from this point of view as well, the heating temperature is preferably 500 to 600°C. If the temperature is high, (1) a reaction between Li and aluminum foil will occur, producing a large amount of LiAlO ₂ ; (2) if the temperature is higher than the melting point of aluminum, 660°C, the aluminum foil will melt and valuable metals will turn into molten material. Inconveniences may occur, such as the plastic being taken in and becoming unrecoverable, or (3) the plastic burning in the heating furnace. The heating time is, for example, 0.3 to 10 hours, preferably 10 minutes to 6 hours.

The heating conditions are determined as appropriate depending on the heating method of the heating furnace used and the type of waste lithium ion battery. When heated under the above conditions, oxygen does not reach the inside of the casing of cylindrical or square lithium ion batteries during heating, and the plastic separator etc. does not burn. In the case of a laminated lithium ion battery, it is preferable to heat it in a superheated steam atmosphere containing 1 to 3% by volume of oxygen, since the opening may open wide when the electrolyte evaporates. Binder components such as PVDF contained in the positive and negative electrodes decompose, and the positive electrode active material easily peels off from the positive electrode current collector, and the negative electrode active material peels off from the negative electrode current collector. If there is insufficient time, these effects will not occur in large quantities.

Basically, the heating furnace used may be of any type. For example, a continuous furnace such as a rotary kiln, a tunnel furnace, a roller hearth kiln, a bogie furnace, a fluidized bed furnace, etc., or a batch furnace such as a muffle furnace can be used. Cooling is performed after heating. This is because if the next step of pulverization is performed without cooling, there is a risk that the remaining plastic will burn. Cooling is carried out to 100°C or lower, more preferably to 40°C or lower. The cooling may be performed using a chiller to increase the cooling rate, but it is preferable to perform the cooling in the air in order to reduce the cost of equipment and atmosphere adjustment.

In step S13, the heat-treated lithium ion battery is pulverized to obtain a pulverized product. For pulverization, a commonly used pulverizer can be used and can be appropriately selected depending on the purpose. A crushed product may be obtained by crushing by impact. Preliminary crushing may be performed by cutting the heat-treated product using a cutting machine. As the crusher, for example, a hammer crusher can be used. A method of hitting the object to be crushed with ceramic balls or the like may be used, and a ball mill or the like may be used. A twin-screw crusher or, if necessary, an air flow crusher such as a jet mill may be used.

In step S14, the pulverized material is sieved to obtain powdered (granular) lithium ion battery slag of a predetermined size. In this sieving, it is desirable to have a suitable powder size (particle size). The pulverized material is sieved and sorted into upper and lower sieves, and recovered materials are obtained from each. A step of magnetically sorting the sieved separation material may be included. Here, when performing magnetic separation on the sieve material, the non-magnetic material after magnetic separation is called a coarse grain product, and the material separated under the sieve is called a fine grain product.

Copper, aluminum foil, plastic, and iron mainly remain on the sieve. This includes processed materials such as positive electrode active materials that contain valuable metals under the sieve, as well as copper, aluminum foil, iron, and negative electrode active material graphite that have been crushed in the crushing process and passed through the sieve. If magnetic separation is applied, iron will be removed by magnetic force. The sieving method is not particularly limited and can be selected as appropriate depending on the purpose. For example, a vibrating sieve, a multistage vibrating sieve, a cyclone, a standard sieve according to JIS Z8801, etc. can be used. The mesh opening of the sieve can be appropriately selected depending on the purpose, but the range is preferably about 0.01 to 10 mm. Hereinafter, the obtained black lithium ion battery slag will also be referred to as black mass (BM) in this application.

In step S15, the lithium ion battery slag (BM) obtained in step S14 is subjected to X-ray diffraction (XRD) measurement. X-ray diffraction (XRD) measurement analyzes the state (compounds, etc.) of elements contained in lithium ion battery sludge (BM) and analyzes the relationship with Li/Mn leaching/recovery. do it for the sake of

In the XRD measurement of the lithium ion battery slag (BM) of the present invention, the content varies depending on the material used for the positive electrode active material and the heat treatment conditions of step S2, but for example, graphite (C), CoNi, Li ₂ CO ₃ , Co ₃ Peaks indicating the presence of O ₄ , LiAlO ₂ , Cu, CoO, MnO, etc. are detected. Furthermore, in the present invention, detected specific peaks are compared and attention is paid to their intensity ratio (peak intensity ratio) A/B. The reason is as follows.

When the positive electrode active material is LCO, NCM, NCMA, or NCA, it has a crystal structure belonging to the space group R-3m, and regardless of the difference in composition, according to XRD measurement, the diffraction angle: 2θ = 18.7°, 36 It shows peaks derived from the crystal structure at .8°, 44.5°, etc. Here, the peak at 18.7° is the largest, and the height of this peak can be used to roughly determine how well the crystal structure of the positive electrode active material in the sample is maintained. It is considered that the higher the peak height of 18.7°, the better the crystal structure is maintained.

Li in a lithium ion battery is incorporated into the crystals of the positive electrode active material in a discharged state. As the depth of charge increases, the graphite moves from the positive electrode active material to the negative electrode active material, becoming a carbon (C)-Li compound. In the lithium-ion battery targeted this time, the charging voltage is controlled to about 4.2V, so about 50% of the Li amount originally present in the positive electrode active material escapes from the positive electrode active material during charging, and the remaining 50% is considered to remain in the positive electrode active material.

Therefore, the present inventors thought that by disintegrating the crystal structure of the cathode active material by heating, the Li remaining in the cathode active material could be easily taken out. We decided to focus on the ratio (A/B) between the intensity A of the peak (the strongest peak of the positive electrode active material) and the intensity B of the peak at 26.5° (the strongest peak of graphite in the negative electrode active material).

<Manufacture of lithium ion battery slag (BM)>
A consumer cylindrical lithium ion battery using NCM523 (N:C:M=5:2:3) as the positive electrode active material was heated at 200°C/hour in a batch furnace in a superheated steam atmosphere containing 2% by volume of oxygen. The temperature was increased to 500° C. and maintained for 5.5 hours. During this time, the oxygen concentration was maintained and the supply of heated steam continued. Thereafter, the supply of superheated steam was stopped, and the mixture was cooled to room temperature over 12 hours. Thereafter, the heat-treated lithium ion battery was crushed and sieved using a cross-flow shredder, and the fraction under the sieve with a size within the range of 0.01 to 10 mm was collected to obtain BM1 of Example 1.

The obtained BM1 was quantitatively analyzed using an ICP-OES analyzer (ICPE-9000 manufactured by Shimadzu Corporation), and the amount of C was measured using TG-DTA to investigate the contained components. , the crystal structure was analyzed by XRD measurement. XRD measurement was performed using Rigaku's Smart lab. FIG. 3 shows the XRD measurement results (chart) BM1. From Figure 3, the following (1) to (4) have become clear.

(1) Height (intensity) ratio of the peak at 18.7° (strongest peak of positive electrode active material) and 26.5° (strongest peak of negative electrode active material: graphite) (18.7/26.5) was 0.102.
(2) Generation of CoNi was confirmed. Judgment was made from the peaks at 51.7° and 76.2°. Note that the peak at 44.4° cannot be separated because it overlaps with the positive electrode active material and graphite.
(3) Generation of Li ₂ CO ₃ was confirmed. Judgment was made from the peaks at 21.4°, 29.5°, 30.6° and 31.8°.
(4) Production of Co ₃ O ₄ was confirmed. Judgment was made from the peaks at 37.0° and 38.6°.

<Water leaching of Li>
10 g of BM1 was dispersed in 100 mL of tap water, and heated using a hot stirrer at a heating rate of 120° C./hour to three temperatures: 30° C., 60° C., and 80° C. After reaching each temperature, stirring was continued while maintaining the temperature for 2 hours, 5 hours, and 24 hours (9 conditions in total), and after cooling to room temperature, it was filtered. The amounts of Li, Co, Ni, and Mn in the resulting filtrate (filtrate A) and filtration residue under the nine conditions were measured. The amounts of Li, Co, Ni, and Mn in the filtration residue were defined as the amounts of Li, Co, Ni, and Mn in the filtrate (filtrate B) recovered by filtration after dissolving the filtration residue in hot aqua regia. Analysis of Li, Co, Ni, and Mn was performed using ICP (ICPE-9000, manufactured by Shimadzu Corporation) after appropriately diluting filtrate A and filtrate B with 3% nitric acid. The recovery rates of Li, Co, Ni, and Mn were calculated as: mass of each metal in filtrate A/(mass of each metal in filtrate A + mass of each metal in filtrate B)*100.

The recovery rate (%) of Li was as follows. The recovery rates of Co, Mn, and Ni were approximately 0% under all conditions.

30℃ 60℃ 80℃
2H: 46.4 49.9 49.8
5H: 52.3 50.2 47.8
24H: 47.3 49.9 40.9

From this result, it was found that solid-liquid separation of Li and (Co+Ni) was possible, with only Li leaching into water at a high rate and Co and Ni not leaching into water.

<Li and Mn leaching with sulfuric acid aqueous solution>
(a) When 10 g of BM1 was subjected to leaching reaction in 100 mL of 1, 2, and 3 wt% aqueous H ₂ SO ₄ solution at 80°C for 2 hours, the recovery rate (%) of Li, Mn, Co, and Ni was as follows. It became like this.

1wt% 2wt% 3wt%
Li: 52.0 58.2 74.3
Mn: 0.02 39.3 77.2
Co: 0.00 0.42 2.44
Ni: 0.00 0.31 0.17

(b) When 10 g of BM1 was subjected to a leaching reaction in 100 mL of a 3 wt% H ₂ SO ₄ aqueous solution at 30°C, 60°C, and 80°C for 2 hours, the recovery rate (%) of Li, Mn, Co, and Ni was , it became as follows.

30℃ 60℃ 80℃
Li: 66.1 71.2 74.3
Mn: 72.0 72.0 77.2
Co: 14.2 10.3 2.44
Ni: 9.05 4.07 0.17

(c) When 10 g of BM1 was subjected to a leaching reaction in 100 mL of a 3 wt% H ₂ SO ₄ aqueous solution at 80°C at leaching times (H) of 0.5, 2, 5, and 24 hours, Li, Mn, Co , and the recovery rate (%) of Ni were as follows.

0.5H 2H 5H 24H
Li: 79.4 72.6 70.7 79.8
Mn: 69.4 64.9 52.3 23.7
Co: 7.14 0.91 0.09 0.21
Ni: 1.89 0.10 0.91 0.21

From the leaching results (recovery rate) of BM1 in (a) to (c) above, Li and Mn were leached into an aqueous sulfuric acid solution with a concentration of 1 to 3 wt% at a temperature of 30°C to 80°C for a leaching time of 0.5 to 24 hours. It has become clear that solid-liquid separation of (Li+Mn) and (Co+Ni) is possible while leaching out at a high rate, while hardly leaching Co and Ni.

A consumer cylindrical lithium ion battery using NCM523 as a positive electrode active material was transported to a conveyor type drying oven set at 300° C. in an air atmosphere for 15 minutes to evaporate the electrolyte in the lithium ion battery. Next, the mixture was heated at 560° C. for 20 minutes in a rotor kiln through which air could circulate. The obtained heated lithium ion battery was cooled to room temperature and then crushed using a twin-screw crusher. Thereafter, it was sieved using a vibrating sieve, and the under-sieve fraction having a size within the range of 0.01 to 10 mm was collected to obtain BM2 of Example 2.

As in the case of BM1 in Example 1, after examining the contained components, crystal structure analysis was performed by XRD measurement. FIG. 3 shows the XRD measurement results (chart) BM2. From Figure 3, the following details were clarified.
(1) The peak intensity ratio between 18.7° and 26.5° (18.7/26.5) was 0.0984.
(2) Generation of CoNi, Li ₂ CO _{3 and} Co ₃ O ₄ was confirmed.

Conducted in the same manner as in Example 1, except that a consumer cylindrical lithium ion battery using NCM523 as the positive electrode active material was heated to 600°C at a rate of 200°C/hour and maintained for 5.5 hours. BM3 of Example 3 was obtained.

As in the case of BM1 in Example 1, after examining the contained components, crystal structure analysis was performed by XRD measurement. FIG. 3 shows the XRD measurement results (chart) BM3. From Figure 3, the following details were clarified.
(1) The peak intensity ratio between 18.7° and 26.5° (18.7/26.5) was 0.0328.
(2) Generation of CoNi, Li ₂ CO _{3 and} Co ₃ O ₄ was confirmed.

<Manufacture of lithium ion battery slag (BM)>
As Example 4, an experiment of Comparative Example 1 was conducted. A consumer-use cylindrical lithium ion battery using NCM523 as a positive electrode active material was transported for 15 minutes to a conveyor-type drying oven set at 200° C. in an air atmosphere. Next, it was heated at 400° C. for 20 minutes in a rotor kiln through which air could be circulated. The obtained heat-treated lithium ion battery was cooled to room temperature and then crushed using a twin-screw crusher. Thereafter, it was sieved using a vibrating sieve, and the under-sieve fraction having a size within the range of 0.01 to 10 mm was fractionated to obtain BMR, which is the BM of Comparative Example 1.

As in the case of BM1 in Example 1, after examining the contained components, crystal structure analysis was performed by XRD measurement. FIG. 3 shows the XRD measurement results (chart) BMR. From FIG. 3, the following (5) to (8) have become clear.
(1) The peak intensity ratio between 18.7° and 26.5° (18.7/26.5) was 0.18.
(2) Generation of CoNi could not be confirmed.
(3) The production of Li ₂ CO ₃ could only be confirmed in a trace amount (a trace amount below a certain standard or below a measurement limit).
(4) Production of Co ₃ O ₄ was confirmed.

<Water leaching of Li>
By the same method as in the case of BM1 in Example 1, 10 g of BMR of Example 4 (Comparative Example 1) was dispersed in 100 mL of tap water, and a Li leaching test was conducted at a leaching temperature of 80 ° C. and a leaching time of 2 hours. . As a result, the leaching rate of Li was 15.3%, and the recovery rates of Co, Mn, and Ni were all 0%.

<Leaching of Li and Mn in sulfuric acid aqueous solution>
When the BMR of Example 4 (Comparative Example 1) was subjected to a leaching reaction for 2 hours in a 5wt% H ₂ SO ₄ aqueous solution at 30°C, the leaching rate (%) of Li, Mn, Co, and Ni was as follows. , became as follows.

Li Mn Co Ni
BMR: 36.9 26.3 25.2 22.8

It was confirmed that solid-liquid separation of (Li+Mn) and (Co+Ni) was difficult because the leaching rate of Li and Mn was low, and Co and Ni were leached out at similar rates (%).

By comparing the manufacturing conditions and XRD measurement results of Examples 1 to 3 and Example 4 (Comparative Example 1),
(i) The heating temperature is 500°C to 600°C,
(ii) The oxygen concentration in the atmosphere during heating is 2 to 21% by volume (atmosphere) or less, and (iii) The heating temperature is maintained for 0.33 to 5.5 hours.
(a) In the XRD measurement chart of BM, the height (intensity) ratio of the peak at 2θ of 18.7° and the peak at 26.5° is 0.102 or less (b) CoNi compound is generated ( It has become clear that three things can occur simultaneously: c) Li ₂ CO ₃ is produced. Further, it was found that the content of graphite (C) in the BM at that time was about 20 to 31% by mass.

From the comparison of Li water leaching results (recovery rate) of Example 1 and Example 4 (Comparative Example 1), BM1 of Example 1 is more than three times the recovery rate of BMR of Comparative Example 1 (about 15%). It was found that Li could be recovered at a high recovery rate (approximately 50%).

From the sulfuric acid aqueous solution leaching results (recovery rate) of Example 1 and Example 4 (Comparative Example 1), solid-liquid separation of (Li+Mn) and (Co+Ni) is possible in BM1 of Example 1, but in Example 4 It became clear that the BMR of (Comparative Example 1) was difficult.

Embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to these embodiments. The present invention can be implemented with various improvements, modifications, and variations based on the knowledge of those skilled in the art without departing from the spirit thereof.

Lithium ion battery slag and its manufacturing method can be widely used in the recovery of metals from waste lithium ion batteries.

Claims (8)

A method for recovering metal from a lithium ion battery containing lithium (Li), cobalt (Co) and nickel (Ni) as a positive electrode active material and graphite (C) as a negative electrode active material, the method comprising:
(a) In X-ray diffraction (XRD) measurement, the ratio (A/B) of peak intensity A at a diffraction angle of 18.7° and peak intensity B at 26.5° is in the range of 0 to 0.15. a step of preparing battery slag for the lithium ion battery;
(b) dispersing the battery slag in water and leaching lithium into a leachate at 30 to 80°C for 2 to 24 hours;
method including. A method for recovering metal from a lithium ion battery containing lithium (Li), cobalt (Co) and nickel (Ni) as a positive electrode active material and graphite (C) as a negative electrode active material, the method comprising:
(a) In X-ray diffraction (XRD) measurement, the ratio (A/B) of peak intensity A at a diffraction angle of 18.7° and peak intensity B at 26.5° is in the range of 0 to 0.15. a step of preparing battery slag for the lithium ion battery;
(b) dispersing the battery slag in an aqueous sulfuric acid solution with a concentration of 1 to 3% by mass, and leaching lithium and manganese into a leachate at 30 to 80°C for 0.5 to 24 hours;
method including. 3. The method according to claim 1, wherein in X-ray diffraction (XRD) measurement, the battery slag has a peak due to CoNi. 4. The method according to claim ₃ , wherein in X-ray diffraction ₍ XRD) measurement, the battery slag has a peak resulting from one or both of _Li2CO3 and _Co3O4 . The method according to claim 4, wherein the battery slag contains 10 to 35% by mass of the graphite (C). 6. The method of claim 5, wherein the positive electrode active material comprises manganese (Mn). The step (a) of preparing battery slag for the lithium ion battery includes:
(a1) a heat treatment step of holding the lithium ion battery in the atmosphere in a heating furnace at a temperature of 500 to 600°C for 0.3 to 10 hours;
(a2) a pulverizing step of pulverizing the lithium ion battery after heat treatment to obtain a pulverized product;
(a3) a sieving step of sieving the pulverized material to obtain powdered lithium ion battery slag;
The method according to claim 1 or 2, comprising: In the heat treatment step (a1), the inside of the heating furnace is replaced by an atmosphere of inert gas or superheated steam having an oxygen concentration of 1 to 21% by volume, and an atmosphere of inert gas or superheated steam having an oxygen concentration of 1 to 3% by volume. 8. The method according to claim 7, comprising heating in any state of superheated steam atmosphere.

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