Method for sorting plastics in waste lithium ion batteries

Abstract

The present invention relates to a method for sorting plastics in waste lithium ion batteries, and relates to a method for sorting plastics in waste lithium ion batteries, the method being capable of automating and optimizing a manually performed process by automatically sorting and removing plastics including polystyrene (PS) in a process of recovering valuable resources from waste batteries.

Description

Plastic sorting method for spent lithium-ion batteries

[0001] The present invention relates to a method for sorting plastics from spent lithium-ion batteries, and more specifically, to a method for sorting plastics from spent lithium-ion batteries that can optimize the process by automatically sorting and removing plastics containing polystyrene (PS) during the process of recovering valuable resources from spent batteries.

[0002] Lithium-ion batteries have advantages such as high energy density, operating voltage, and a relatively small self-discharge rate compared to commercial water-based secondary batteries (Ni-Cd, Ni-MH, etc.), and are currently widely used in portable electronic communication devices, electric vehicles, and energy storage systems (ESS). In particular, when large capacity is required, such as in electric vehicles, they are installed and used in units of multiple battery cells, battery modules, and battery packs; as battery capacity and usage increase, the amount of discarded batteries also increases.

[0003] Accordingly, recycling discarded lithium-ion batteries to recover valuable resources such as lithium is emerging as a major issue.

[0004] The above-mentioned spent lithium-ion batteries are processed into a mixed powder form of cathode material, anode material, and other materials, known as Black Powder, through steps such as discharge, crushing, grinding / classification, and heat treatment.

[0005] At this time, in the process of forming the black powder, the crushed waste lithium-ion battery material includes cathode material constituents such as nickel, cobalt, manganese, and lithium; anode material constituents such as graphite; separator constituents such as PE (polyethylene) and PP (polypropylene) plastics; and battery casing constituents such as magnetic materials and PP and PS (polystyrene) plastics.

[0006] Among these, plastics generate air pollutants during the valuable resource recovery process using black powder and can become coated on other materials due to heat; since this can act as a load on the process, it is advisable to remove them through a separation operation before performing the valuable resource recovery process using black powder.

[0007] Among these, PE-based and PP-based plastics are low-density polymer plastics that can be separated with a high recovery rate through classification performed after the crushing of spent lithium-ion batteries; however, the recovery rate of PS-based plastics remains low due to characteristics that differ somewhat from the aforementioned PE and PP-based plastics. Consequently, in the past, PS-based plastics were removed by manually disassembling the casing; this process consumed an excessive amount of time, resulting in a low process yield and preventing the process from being optimized.

[0008] Accordingly, there is a need to improve the process for removing PS-based plastics.

[0009] One aspect of the present invention for solving the aforementioned problem is to provide a method for sorting plastic from spent lithium-ion batteries that can automatically sort and remove plastic impurities during the process of recovering valuable resources from spent lithium-ion batteries.

[0010] The technical problems to be solved in this document are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this invention belongs from the description below.

[0011] To achieve the above objective, a method for sorting plastic from spent lithium-ion batteries according to one embodiment of the present invention may include: a process of preparing a shredded waste lithium-ion battery; a process of classifying the shredded waste lithium-ion battery to separate plastic in a first step; a process of separating the shredded waste lithium-ion battery separated in the first step by magnetic separation; a process of aligning the shredded waste lithium-ion battery into a single layer using a vibrating feeder; a process of sorting plastic remaining in the shredded waste lithium-ion battery using a spectrometer in a second step; and a process of recovering the sorted plastic.

[0012] A method for sorting plastics from spent lithium-ion batteries according to one embodiment of the present invention can sort plastics including polystyrene-based plastics in the secondary sorting process.

[0013] In a plastic sorting method for waste lithium-ion batteries according to one embodiment of the present invention, the spectrometer may be one or more of an infrared spectrometer (IR Spectrometer), a visible light spectrometer (Visible Light Spectrometer), a UV-Vis spectrometer (UV-Vis Spectrometer), a Raman spectrometer, a fluorescence spectrometer, an atomic absorption spectrometer (AAS), an atomic emission spectrometer (AES), a mass spectrometer (MS), an X-ray spectrometer (XRD / XRF), a near-infrared spectrometer (NIR Spectrometer), an RGB sensor-based spectrometer, and an electron spectrometer (ESCA / XPS).

[0014] In a method for separating plastic from waste lithium-ion batteries according to one embodiment of the present invention, the infrared spectrometer can separate plastic from the crushed material using the FT-IR method.

[0015] A method for sorting plastics from spent lithium-ion batteries according to one embodiment of the present invention may include one or more of PE-based plastics, PP-based plastics, and PS-based plastics.

[0016] A method for sorting plastics from spent lithium-ion batteries according to one embodiment of the present invention, wherein the PE-based plastic may exhibit peaks at one or more of wavelengths of 3.33 to 3.57 μm, 6.80 to 6.85 μm, and 13.70 to 13.89 μm as a result of infrared analysis.

[0017] A method for sorting plastic from spent lithium-ion batteries according to one embodiment of the present invention allows the PP-based plastic to exhibit peaks at one or more of wavelengths of 3.33 to 3.57 μm, 6.90 to 7.27 μm, and 10.53 to 12.50 μm as a result of infrared analysis.

[0018] A method for sorting plastic from spent lithium-ion batteries according to one embodiment of the present invention, wherein the PS-based plastic may exhibit peaks at one or more of wavelengths of 3.23–3.31 μm, 6.25–6.71 μm, and 11.76–13.33 μm as a result of infrared analysis.

[0019] In a method for sorting plastic from waste lithium-ion batteries according to one embodiment of the present invention, one or more of the visible light spectrometer or the RGB sensor-based spectrometer can sort plastic from the crushed material by a color sorting method.

[0020] A method for sorting plastics from spent lithium-ion batteries according to one embodiment of the present invention may include one or more of PE-based plastics, PP-based plastics, and PS-based plastics.

[0021] In a plastic sorting method for waste lithium-ion batteries according to one embodiment of the present invention, the PE-based plastic may exhibit RGB values ​​of 0 to 10 as a result of color analysis.

[0022] A method for sorting plastics from waste lithium-ion batteries according to one embodiment of the present invention allows the PP-based plastic to exhibit RGB values ​​of 0 to 10 as a result of color analysis.

[0023] A method for sorting plastics from spent lithium-ion batteries according to one embodiment of the present invention allows the PS-based plastic to exhibit RGB values ​​of 0 to 10 as a result of color analysis.

[0024] In a method for sorting plastic from spent lithium-ion batteries according to one embodiment of the present invention, the recovery rate of the plastic may be 60% or more.

[0025] The plastic sorting method for waste lithium-ion batteries according to the present invention can optimize the process by automating the process that was previously performed manually for plastic sorting, by recovering plastics treated as impurities, including PS (polystyrene), with a high recovery rate of 60% or more during the process of recovering valuable resources from waste lithium-ion batteries, and thereby increasing the yield.

[0026] In addition, the plastic sorting method for waste lithium-ion batteries according to the present invention can reduce air pollutants that may be generated during the process by recovering plastic with a high recovery rate during the process of recovering valuable resources, and at the same time, can recover the valuable resources, which are the final recovered materials, with high purity.

[0027] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0028] FIG. 1 is a flowchart illustrating a plastic sorting method for waste lithium-ion batteries according to one embodiment of the present invention.

[0029] Preferred embodiments of the present invention are described below. However, embodiments of the present invention may be modified in various other forms, and the technical concept of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those with average knowledge in the relevant technical field.

[0030] The terms used in this application are used merely to describe specific examples. For this reason, singular expressions include plural expressions unless the context clearly requires them to be singular. Additionally, it should be noted that terms such as “comprising” or “comprising” used in this application are used to clearly indicate the presence of features, steps, functions, components, or combinations thereof described in the specification, and are not used to preliminarily exclude the existence of other features, steps, functions, components, or combinations thereof.

[0031] Meanwhile, unless otherwise defined, all terms used in this specification shall be understood to have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Accordingly, unless explicitly defined in this specification, specific terms should not be interpreted in an overly ideal or formal sense. For instance, singular expressions in this specification include plural expressions unless the context clearly indicates an exception.

[0032] Additionally, terms such as "about," "substantially," etc., in this specification are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the said sense, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosed content in which precise or absolute values ​​are mentioned to aid in understanding the invention.

[0033] As previously explained, spent lithium-ion batteries can typically be processed into a mixed powder of cathode materials, anode materials, and other substances, known as Black Powder, through steps such as discharge, crushing, grinding / classification, and heat treatment. Valuable resources such as lithium are then recovered from the Black Powder through magnetic separation and wet smelting. At this time, prior to recovering valuable resources from the Black Powder, the crushed material of the spent lithium-ion battery contains PE-based plastics, PP-based plastics, and PS-based plastics constituting the separator and casing, in addition to the cathode and anode materials. Since these plastics can generate air pollutants or cause phenomena such as coating other materials due to heat during the valuable resource recovery process, which can act as a load on the process, it is desirable to remove them through a separation operation before performing the valuable resource recovery process using black powder. Conventionally, PE-based and PP-based plastics were removed with high recovery rates through the classification of crushed waste lithium-ion batteries, but PS-based plastics have been removed manually because they are difficult to separate due to their characteristics.

[0034] As such, there is a problem where the process yield is reduced by manually removing plastic, which is an impurity in the valuable resource recovery process.

[0035] Accordingly, the present invention aims to optimize the recycling process of spent lithium-ion batteries by automating the separation process of PS-based plastics, which was previously performed manually, and recovering them with a high recovery rate.

[0036] The plastic sorting method for waste lithium-ion batteries according to the present invention separates plastics by classifying the crushed waste lithium-ion batteries, separates the plastics by magnetic separation and sorting the crushed materials, and then separates and recovers the plastics by secondary separation. This is described in more detail with reference to FIG. 1 as follows.

[0037] FIG. 1 is a flowchart illustrating a plastic sorting method for waste lithium-ion batteries according to one embodiment of the present invention.

[0038] Referring to FIG. 1, a method for sorting plastic from waste lithium-ion batteries according to one embodiment of the present invention is described as follows: First, crushed waste lithium-ion batteries are prepared (S110).

[0039] As explained above, spent lithium-ion battery crushed material can be formed by discharging and crushing the spent lithium-ion batteries before forming black powder.

[0040] Next, the above-mentioned waste lithium-ion battery crushed material is classified to perform primary sorting of plastic (S120).

[0041] The above classification is a method of separating substances based on particle size, shape, or other physical or chemical properties, and one or more classification methods among air classification, sieve classification, gravity classification, centrifugal classification, electrostatic classification, density classification, or optical classification may be utilized.

[0042] The above air classification is a method of separating particles according to size, density, or shape using an airflow. In the present invention, a cyclone classifier, a precision air classifier, or an inertial air classifier may be used, but the classification conditions of the present invention are not necessarily limited thereto and can be appropriately applied according to various other classification environments.

[0043] In addition, gravity classification, centrifugal classification, electroclassification, density classification, or optical classification methods may be applied.

[0044] Through the above classification, the density is 0.910~0.965 g / cm³ 3 PE-based plastics and 0.895~0.920 g / cm³ 3 PP-based plastics can be easily separated with a high recovery rate into relatively low-density materials among the substances constituting the crushed material. On the other hand, PS-based plastics have a density of approximately 1.040 to 1.100 g / cm³. 3 It is difficult to recover easily through classification to that extent.

[0045] At this time, the recovery rate of plastic separated through the above classification may be 8% or more relative to the total mass of plastic present in the waste lithium-ion battery crushed material, and preferably 10% or more.

[0046] After the above classification is completed, the waste lithium-ion battery crushed material that has undergone the plastic primary sorting process (S120) can be separated into non-magnetic materials through magnetic sorting (S130).

[0047] The above-mentioned crushed waste lithium-ion battery material may include magnetic materials such as NCM (nickel-cobalt-manganese)-based compounds, iron, and fastening parts, and non-magnetic materials such as lithium compounds, copper, aluminum, graphite, and plastic.

[0048] In the above magnetic separation process, the crushed waste lithium-ion battery material can be fed into a magnetic separator to separate magnetic materials such as nickel, cobalt, and iron.

[0049] One or more of a belt magnetic separator, a drum magnetic separator, or a high-intensity magnetic separator may be used as the above magnetic separator.

[0050] Through the magnetic separation described above, the crushed waste lithium-ion battery is separated into magnetic and non-magnetic materials. The plastic separation method for waste lithium-ion batteries according to the present invention is intended to separate non-magnetic plastic particles during the process of recovering lithium compounds, which are non-magnetic materials and valuable resources, and the treatment of the non-magnetic material is described.

[0051] When the magnetic material is separated by the magnetic separation (S130), the crushed material from which the magnetic material has been separated is sorted (S140), and then the plastic remaining in the crushed material is separated a second time (S150) to separate the plastic containing polystyrene.

[0052] After the above magnetic separation (S130), the crushed waste lithium-ion battery material is fed into a vibrating feeder and arranged in a single layer (S140) on a conveyor belt. By arranging the crushed material in a single layer (S140) in this way, unnecessary scattering and noise in the subsequent secondary separation process (S150) can be minimized, thereby improving the reliability of the analysis results.

[0053] After the above crushed material is aligned into a single layer (S140), a secondary screening process (S150) can be performed using a spectrometer.

[0054] One or more of the following spectrometers may be applied: an infrared spectrometer (IR Spectrometer), a visible light spectrometer (Visible Light Spectrometer), a UV-Vis spectrometer (UV-Vis Spectrometer), a Raman spectrometer, a fluorescence spectrometer, an atomic absorption spectrometer (AAS), an atomic emission spectrometer (AES), a mass spectrometer (MS), an X-ray spectrometer (XRD / XRF), a near-infrared spectrometer (NIR Spectrometer), an RGB sensor-based spectrometer, and an electron spectrometer (ESCA / XPS).

[0055] The above infrared spectrometer is a spectrometer capable of analyzing the chemical properties of a material with high precision and resolution using the FT-IR method, and can separate polymers present in the crushed material by type by utilizing the characteristic that the molecular structure of the material absorbs or reflects infrared rays of a specific wavelength.

[0056] As a result of performing IR analysis using the above FT-IR infrared spectrometer, the PE-based plastic exhibits a unique infrared absorption pattern containing carbon-hydrogen bonds (CH), showing peaks at wavelengths of 3.33–3.57 µm, 6.80–6.85 µm, and 13.70–13.89 µm.

[0057] The above PP-based plastic exhibits a specific absorption pattern containing carbon-hydrogen bonds (CH) and methyl groups (-CH3, methyl group), and IR analysis results show peaks at wavelengths of 3.33–3.57 µm, 6.90–7.27 µm, and 10.53–12.50 µm.

[0058] The above PS-based plastic exhibits a unique absorption pattern containing benzene rings, and IR analysis results show peaks at wavelengths of 3.23–3.31 µm, 6.25–6.71 µm, and 11.76–13.33 µm.

[0059] On the other hand, other materials present in the crushed material, such as copper, a non-magnetic metal, reflect infrared radiation in its pure metallic form and do not exhibit IR absorption peaks, while lithium carbonate (Li2CO3) and lithium hydroxide (LiOH) exhibit peaks at wavelengths of 6.8–7.2 µm, 11–14 µm, and 3.0–3.2 µm and 8.5–9.5 µm, respectively.

[0060] That is, when plastics of waste lithium-ion batteries are sorted using an FT-IR infrared spectrometer according to one embodiment of the present invention, particles in which peaks are detected at the corresponding wavelengths of PE-based plastics, PP-based plastics, and PS-based plastics as a result of IR analysis can be selectively sorted.

[0061] In addition, when sorting plastics from waste lithium-ion batteries using the above-mentioned visible light spectrometer or RGB sensor-based spectrometer, a color sorting method is applied to analyze the color characteristics of the material.

[0062] At this time, as a result of analyzing the color characteristics of each particle of the crushed material using a visible light spectrometer or an RGB sensor-based spectrometer, the above PE-based plastic, PP-based plastic, and PS-based plastic may have RGB values ​​of 0 to 10.

[0063] In this way, in the process of secondary sorting of plastics using a visible light spectrometer, only plastics with RGB values ​​of 0 to 10 can be selectively sorted, unlike other metals or compounds in the crushed material.

[0064] As described above, as a result of secondary sorting of plastics among non-magnetic materials, plastics containing polystyrene can be sorted with a high recovery rate of more than 60% relative to the total mass of plastics present in the waste lithium-ion battery crushed material, and the plastics sorted in this way can be recovered (S160) through a separate recovery device and separated from the waste lithium-ion battery crushed material.

[0065] Meanwhile, the secondary sorting process (S150) using a spectrometer may be performed once, but in the plastic sorting method for waste lithium-ion batteries according to one embodiment of the present invention, the alignment (S140) and secondary sorting process (S150) may be repeated to recover more plastic remaining in the crushed waste lithium-ion batteries.

[0066] As described above, the plastic sorting method for waste lithium-ion batteries according to one embodiment of the present invention automates the PS-based plastic sorting and removal process, which was previously performed manually, and recovers at least 60% of the plastic relative to the total mass of plastic present in the waste lithium-ion battery crushed material, thereby optimizing the waste lithium-ion battery recycling process and effectively reducing the content of plastic particles in the waste lithium-ion battery crushed material fed into the valuable resource recovery process, which increases heat transfer efficiency in subsequent processes and reduces the generation of harmful substances. Accordingly, the yield of the process can be increased, and valuable resources can be recovered with higher purity.

[0067] The present invention will be explained in more detail below through the following examples. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited thereto.

[0068] Examples

[0069] Example 1

[0070] After primary sorting and magnetic separation of the crushed waste lithium-ion battery, the separated non-magnetic material was aligned in a vibrating feeder and analyzed by the FT-IR method to secondary sort plastic particles showing peaks of PS-based plastic, PP-based plastic, and PE-based plastic particles, thereby recovering the plastic.

[0071] Example 2

[0072] The procedure was carried out in the same manner as Example 1 above, except that the plastic was recovered through a total of two secondary sorting processes by aligning the crushed material from which the plastic was separated through secondary sorting into a vibrating feeder and then sorting it again.

[0073] Example 3

[0074] The procedure was carried out in the same manner as Example 1 above, except that the plastic was recovered through a total of three secondary sorting processes by aligning the crushed material from which the plastic was separated through two secondary sorting processes into a vibrating feeder and sorting it again.

[0075] Example 4

[0076] The procedure was carried out in the same manner as Example 1 above, except that the plastic was recovered through a total of four secondary sorting processes by aligning the crushed material, from which the plastic was separated through three secondary sorting processes, with the material again and sorting it through a vibrating feeder.

[0077] Comparative Example 1

[0078] The crushed waste lithium-ion battery material was sorted first, then separated by magnetic force, and the separated non-magnetic material was classified by air classification to recover the plastic.

[0079] Total initial crushed material (kg) Total crushed material after 1st sorting (kg) Total crushed material after 2nd sorting (kg) Amount of plastic recovered after 2nd sorting (kg) Final plastic recovery rate Example 1 3000 2400 229 8 10 260% Example 2 3000 2400 227 8 12 268% Example 3 3000 2400 226 13 173% Example 4 3000 2400 225 6 14 480% Comparative Example 1 3000 2400 238 8 127%

[0080] As can be seen from Table 1 above, unlike Examples 1 to 4, in which secondary screening for non-magnetic materials was performed at least once after primary screening and magnetic screening, which have a plastic recovery rate of 60% or more, Comparative Example 1, in which only classification was performed without secondary screening, shows a very low plastic recovery rate of 7%.

[0081] Through this, it can be seen that it is difficult to effectively recover plastic remaining in the crushed material by simply classifying the crushed material, and that plastics including PS-based plastics can be effectively separated by performing secondary sorting as in Examples 1 to 4.

[0082] In addition, as shown in Examples 1 to 4 above, it can be confirmed that the plastic recovery rate increases as the number of secondary screenings increases. Accordingly, in the plastic screening method for waste lithium-ion batteries according to the present disclosure, by performing secondary screening for non-magnetic materials one or more times, the plastic remaining in the crushed waste lithium-ion battery can be recovered with a recovery rate of at least 60%.

[0083] Although embodiments of the invention disclosed above have been illustrated and described, the disclosed invention is not limited to the specific embodiments described above, and various modifications may be made by those skilled in the art to which the disclosed invention belongs without departing from the essence claimed in the claims.

Claims

1. Process for preparing crushed spent lithium-ion batteries; A process of classifying the above-mentioned crushed waste lithium-ion batteries to primarily sort plastics; A process for magnetically separating the above-mentioned primary sorted crushed waste lithium-ion batteries; A process of aligning the crushed waste lithium-ion batteries into a single layer using a vibrating feeder; A process of secondary sorting of plastic remaining in the shredded waste lithium-ion batteries using a spectrometer; and A process for recovering the above-mentioned selected plastics; A method for sorting plastic from spent lithium-ion batteries including 2. In Paragraph 1, In the above secondary screening process, A method for sorting plastics from waste lithium-ion batteries, including plastics containing polystyrene-based plastics.

3. In Paragraph 1, The above spectrometer is, A method for sorting plastics from waste lithium-ion batteries, wherein one or more of an infrared spectrometer (IR Spectrometer), a visible light spectrometer (Visible Light Spectrometer), a UV-Vis spectrometer (UV-Vis Spectrometer), a Raman spectrometer, a fluorescence spectrometer, an atomic absorption spectrometer (AAS), an atomic emission spectrometer (AES), a mass spectrometer (MS), an X-ray spectrometer (XRD / XRF), a near-infrared spectrometer (NIR Spectrometer), an RGB sensor-based spectrometer, and an electron spectrometer (ESCA / XPS) are applied.

4. In Paragraph 3, The above infrared spectrometer is, A method for separating plastic from waste lithium-ion batteries using the FT-IR method.

5. In Paragraph 4, The above plastic is, A method for sorting plastics from waste lithium-ion batteries, comprising one or more of PE-based plastics, PP-based plastics, and PS-based plastics.

6. In Paragraph 5, The above PE-based plastic is, A method for sorting plastic from spent lithium-ion batteries, wherein infrared analysis results show peaks at one or more of wavelengths of 3.33–3.57 µm, 6.80–6.85 µm, and 13.70–13.89 µm.

7. In Paragraph 5, The above-mentioned PP-based plastic is, A method for sorting plastic from spent lithium-ion batteries, wherein infrared analysis results show peaks at one or more of wavelengths of 3.33–3.57 µm, 6.90–7.27 µm, and 10.53–12.50 µm.

8. In Paragraph 5, The above PS-based plastic is, A method for sorting plastic from spent lithium-ion batteries, wherein infrared analysis results show peaks at one or more of the wavelengths of 3.23–3.31 µm, 6.25–6.71 µm, and 11.76–13.33 µm.

9. In Paragraph 3, One or more of the above visible light spectrometers or RGB sensor-based spectrometers, A method for sorting plastic from waste lithium-ion batteries, sorting plastic from the above-mentioned crushed material using a color sorting method.

10. In Paragraph 9, The above plastic is, A method for sorting plastics from waste lithium-ion batteries, comprising one or more of PE-based plastics, PP-based plastics, and PS-based plastics.

11. In Paragraph 10, The above PE-based plastic is, A method for sorting plastic from waste lithium-ion batteries, showing RGB values ​​of 0 to 10 as a result of color analysis.

12. In Paragraph 10, The above-mentioned PP-based plastic is, A method for sorting plastic from waste lithium-ion batteries, showing RGB values ​​of 0 to 10 as a result of color analysis.

13. In Paragraph 10, The above PS-based plastic is, A method for sorting plastic from waste lithium-ion batteries, showing RGB values ​​of 0 to 10 as a result of color analysis.

14. In Paragraph 1, The recovery rate of the above plastic is, A method for sorting plastic from spent lithium-ion batteries, with a plastic content of 60% or more.

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