Valuable metal recovery composition and valuable metal recovery method

Abstract

The present invention relates to a valuable metal recovery composition and a valuable metal recovery method, wherein the valuable metal recovery composition comprises a valuable metal recovery alloy containing a carbon layer and a lithium compound, the carbon layer being arranged in at least a portion of the surface and interior of the valuable metal recovery alloy, and the carbon (C) content in the carbon layer is 60% by weight or more, based on 100% by weight of the carbon layer.

Description

Technical Field

[0001] Relates to waste batteries, a valuable metal recovery composition recovered from waste batteries, and a method for recovering valuable metals.

Background Art

[0002] As the global demand for electric vehicles increases, the problem of treating waste batteries generated from said electric vehicles has emerged as a social issue. In the case of lithium secondary batteries, which are the main raw material for said waste batteries, they contain organic solvents, explosive substances, and heavy metal substances such as Ni, Co, Mn, and Fe. In the case of Ni, Co, Mn, and Li, they have a high scarcity value as valuable metals, and the recovery and reuse processes after lithium secondary batteries are discarded have emerged as an important research field.

[0003] Specifically, lithium secondary batteries mainly consist of copper and aluminum used as current collectors, Li, Ni, Co, Mn-containing oxides constituting the positive electrode material, and graphite used as the negative electrode material. They also include a separator for separating the positive electrode material and the negative electrode material and an electrolyte injected into the separator. The solvents used as the solvent (Solvent) and salt (Salt) constituting the electrolyte are mainly mixed with carbonate organic substances such as ethylene carbonate and propylene carbonate, and for example, LiPF6 is used.

[0004] Thus, lithium secondary batteries are composed of heavy metal substances such as Ni-Co-Mn-Fe and carbon and other electrolyte substances, among which Ni, Co, Mn, and Li are valuable as valuable metals.

[0005] Reuse for battery raw material recovery generally involves dismantling, discharging, crushing, heat treatment, recovery, and wet processing of batteries to recover valuable metals. In the case of discharge, saltwater discharge is performed, and substances such as Na, K, Mg, Ca, and Cl that enter at this time are included as impurities in the recovered raw material.

[0006] After heat treatment, the recovered material produces different products depending on the heat treatment temperature. When heat-treated at temperatures below 600°C, it is called Black Powder, which is a powder mixture of Ni-Co-Mn-Li oxide and carbon (the negative electrode material), with only very small amounts of Al and Cu present because they are removed beforehand.

[0007] When the aforementioned black powder is heat-treated at a high temperature of 1,000°C or higher, the metal oxide is reduced and alloyed by the carbon in the negative electrode material, resulting in a black alloy containing such alloy components, carbon, and other substances. From the black alloy thus obtained, valuable metal alloys, lithium oxide, and graphite can be recovered separately for each material. At this time, the valuable metal alloy in metallic form is coated with lithium aluminate or lithium oxide, and the black alloy is ultimately used as a raw material after undergoing additional processes such as leaching.

[0008] At this time, the carbon content and carbon shape within the recovered valuable metal alloy change according to the size of the valuable metal alloy, which can increase the efficiency of the wet smelting process using acids or bases and reduce the costs of the process. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The technical problem that this invention aims to solve is to provide a valuable metal recovery composition that can improve the efficiency of a process and reduce the costs of a process when valuable metal alloy raw materials obtained from waste batteries are introduced into a wet smelting process using an acid or a base.

[0010] Another technical problem that the present invention aims to solve is to provide a method for recovering valuable metals to produce a valuable metal recovery composition having the advantages described above. [Means for solving the problem]

[0011] A valuable metal recovery composition according to one embodiment of the present invention comprises a valuable metal recovery alloy containing a carbon layer and a lithium compound, wherein the carbon layer is arranged in at least a portion of the surface and interior of the valuable metal recovery alloy, and the carbon (C) content in the carbon layer may be 60% by weight or more, based on 100% by weight of the carbon layer.

[0012] In one embodiment, at least a portion of the lithium compound can be bonded to at least a portion of the surface of the valuable metal recovery alloy. In one embodiment, the carbon layer is located on the surface of the valuable metal recovery alloy, and the total amount of Ni, Co, and Mn in the carbon layer may be 50% by weight or less, based on 100% by weight of the carbon layer. In one embodiment, the carbon layer is located inside the valuable metal recovery alloy, and the carbon layer may be located as a strip-shaped carburized layer on the cross-section of the valuable metal recovery alloy.

[0013] In one embodiment, the ratio of the major axis to the minor axis of the strip-shaped carburized layer may be 2 or more. In one embodiment, the lithium compound may include lithium oxide. In one embodiment, the lithium oxide may include lithium aluminum oxide. In one embodiment, the valuable metal may include at least one of lithium (Li), cobalt (Co), nickel (Ni), aluminum (Al), and manganese (Mn).

[0014] A method for recovering valuable metals according to another embodiment of the present invention may include the steps of: preparing a battery or battery crushed material in cell units; performing dry heat treatment of the battery or crushed material at a temperature range of 1,100 to 1,800°C without going through a melting step; and cooling the dry heat-treated product at a cooling rate of 10 to 50°C / min or less.

[0015] In one embodiment, the high-temperature reduction reaction step may be carried out in an atmosphere with an oxygen content of 5% or less. In one embodiment, the step may include separating the product obtained after the cooling step by at least one of particle size separation and magnetic separation.

[0016] In one embodiment, the step of separating the resulting material after the cooling step by at least one of particle size separation and magnetic separation can be performed by first performing magnetic separation followed by particle size separation. In one embodiment, the resulting material obtained from the step of dry heat treatment of the crushed material can be separated by external force from lithium compounds bound to a portion of the surface of the valuable metal recovery alloy. In one embodiment, the step of preparing the cell-unit battery or battery crushed material can include a step of pre-treating the cell-unit battery or battery crushed material. [Effects of the Invention]

[0017] In one embodiment of the present invention, a valuable metal recovery composition contains a carbon layer within a valuable metal alloy, which allows the alloy particles to be easily crushed by external force in the subsequent wet smelting process, reducing the diameter of the alloy and simultaneously increasing the specific surface area, thereby improving reactivity to sulfuric acid leaching. Furthermore, the carbon layer positioned on or within the valuable metal alloy has the advantage of facilitating the selective leaching of lithium from lithium oxide present on the alloy surface.

[0018] Another embodiment of the present invention provides a method for recovering valuable metals by controlling heat treatment and cooling conditions to produce a valuable metal recovery composition having the advantages described above. [Brief explanation of the drawing]

[0019] [Figure 1] SEM photograph of the unit valuable metal recovery composition constituting the valuable metal recovery composition according to an embodiment of the present invention.

[0020] [Figure 2] Flowchart of the battery treatment method according to an embodiment of the present invention.

[0021] [Figure 3] SEM photograph of the valuable metal alloy of the present invention is shown.

[0022] [Figure 4] SEM photograph of the valuable metal alloy of the present invention is shown.

[0023] [Figure 5] SEM photograph of the cross section of the valuable metal alloy of the present invention is shown.

[0024] [Figure 6] EPMA analysis result according to the comparative example of the present invention.

[0025] [Figure 7] EPMA analysis result according to the comparative example of the present invention.

[0026] [Figure 8] EPMA analysis result according to the comparative example of the present invention.

MODE FOR CARRYING OUT THE INVENTION

[0027] The terms first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited to these. These terms are used solely to distinguish one part, component, region, layer, or section from other parts, components, regions, layers, or sections. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the invention.

[0028] The technical terms used herein are for the sole purpose of referring to specific embodiments and are not intended to limit the invention. The singular form used herein also includes plural forms unless the wording clearly indicates otherwise. The meaning of “including” as used in this specification embodies a particular characteristic, area, integer, stage, operation, element, and / or component, and does not exclude the presence or addition of other characteristics, areas, integers, stages, operations, elements, and / or components.

[0029] When we say that one part is "on top of" another part, it means that it is either directly above the other part, or that another part may be in between them. In contrast, when we say that one part is "directly above" another part, there is no other part in between them.

[0030] Furthermore, unless otherwise specified, percentages in this specification refer to percentages by weight.

[0031] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosures, and are not interpreted in their ideal or highly formal sense unless otherwise defined.

[0032] Embodiments of the present invention will be described in detail below. However, these are presented as examples only, and the present invention is not limited thereto, but is defined solely within the scope of the claims described below.

[0033] Figure 1 is an SEM image of a unit valuable metal recovery composition that constitutes a valuable metal recovery composition according to one embodiment of the present invention.

[0034] Referring to Figure 1, the valuable metal recovery composition 100 may include a core portion 110 containing a valuable metal, and a shell portion 120 disposed on at least a part of the core portion 110. Specifically, the unit valuable metal recovery composition 100 may consist of a metal such as Ni, Co, or Mn in the core portion 110, with a lithium-containing oxide bonded and disposed on the core portion 110.

[0035] The core portion 110 includes a valuable metal recovery alloy, which may contain 45% by weight or more of valuable metals and the remainder being impurities, based on 100% by weight of the total composition of the alloy. The valuable metal recovery alloy may contain at least one of valuable metals such as nickel (Ni), cobalt (Co), manganese (Mn), lithium (Li), carbon (C), aluminum (Al), and copper (Cu), and the remainder being impurities. In this specification, valuable metals mean expensive metallic components contained in a battery, and refer to nickel, cobalt, manganese, aluminum, copper, and lithium. In one embodiment, the valuable metals may be 70% by weight or more.

[0036] In one embodiment, the valuable metal may contain lithium (Li) in a range of 0.01 to 5% by weight. The advantage of this is that the Li recovery rate can be maximized during the Li smelting process if the lithium content falls within this range. If the lithium content falls outside the upper limit of the range, there is a problem of reduced recovery rates for Ni and Co. If the lithium content falls outside the lower limit of the range, there is a problem of reduced Li recovery rates during the Li smelting process and increased process costs.

[0037] In one embodiment, the valuable metal recovery alloy may contain 0.02% by weight or more of copper (Cu). Specifically, the valuable metal recovery alloy may contain copper in the range of 0.1 to 15% by weight. If the copper content falls outside the upper limit of the range, there is a problem of increased process costs due to the increased amount of CuSO4 precipitated during leaching and solvent extraction. If the copper content falls outside the lower limit of the range, there is a problem of increased unreacted material due to the difficulty in producing low-melting-point Ni-Co-Mn.

[0038] In one embodiment, the copper can combine with nickel (Ni) in the valuable metal to form an alloy. In one embodiment, the nickel can be present in a range of 5 to 40% by weight. If the nickel exceeds the upper limit of the range, there is a problem of reduced leaching rate due to the formation of nickel carbide (Ni3C), and if the nickel exceeds the lower limit of the range, there is a problem of reduced Ni recovery rate in leaching and solvent extraction.

[0039] In one embodiment, the valuable metal recovery alloy may contain carbon (C) in the range of 0.1 to 10% by weight. By satisfying this range of carbon, the actual yield can be increased and the processing time in the wet process can be reduced. Specifically, the carbon may be contained in the range of 1 to 7% by weight.

[0040] If the value falls outside the upper limit of the aforementioned range, it means that the negative electrode material remains in an unreacted state, resulting in poor alloying and the material remaining in the form of a valuable metal oxide within the positive electrode material. If the value falls outside the lower limit of the aforementioned range, it means that lithium may be lost due to high temperatures.

[0041] In one embodiment, the valuable metal recovery alloy may contain aluminum (Al) in the range of 0.25 to 30% by weight. If the aluminum content falls outside the upper limit of the range, there is a problem of reduced Ni and Co recovery rates during the leaching and solvent extraction process. If the aluminum content falls outside the lower limit of the range, there is a problem of reduced Li recovery rates due to difficulty in LiAlO2 formation.

[0042] In one embodiment, the valuable metal recovery alloy may include a carbon layer in at least a portion of its region. Specifically, the carbon layer may be located on or within the valuable metal recovery alloy. The carbon layer may be formed during the process in which carbon from graphite contained in the negative electrode material of a waste battery is carburized into the valuable metal alloy.

[0043] The inclusion of the carbon layer in the valuable metal recovery alloy allows the alloy particles to be easily crushed by external force during subsequent wet smelting processes, thereby reducing their diameter, increasing their specific surface area, and improving their reactivity to sulfuric acid leaching. Furthermore, the inclusion of the carbon layer in the valuable metal alloy has the advantage of facilitating selective leaching when pre-leaching lithium from lithium oxide present on the alloy surface.

[0044] In one embodiment, the carbon (C) content in the carbon layer may be 60% by weight or more, based on 100% by weight of the carbon layer. Specifically, the carbon content may be 60-98% by weight, more specifically, 70-95% by weight, and more specifically, 75-94% by weight.

[0045] The carbon content within the carbon layer satisfies the aforementioned range, which has the advantage that during subsequent wet smelting, the valuable metal alloy particles are easily crushed by external force, reducing their diameter, increasing their specific surface area, improving their reactivity to sulfuric acid leaching, and facilitating the pre-leaching of lithium.

[0046] In one embodiment, the carbon layer may be located inside the valuable metal recovery alloy. Specifically, when viewed on a cross-section of the valuable metal recovery alloy, the carbon layer may be located on the cross-section of the valuable metal recovery alloy as a strip-shaped carburized layer. The strip-shaped carburized layer may be formed by the deposition of carbon at the grain boundaries of the alloy particles.

[0047] Specifically, in the carburized layer, when the cathode material oxide contains an excess of carbon, which is graphite used as a reducing agent, and the temperature is raised to a high temperature under reducing conditions, a reaction occurs in which the carbon carburizes the surface of the cathode material and combines with oxygen to be reduced to CO and CO2. At this time, the amount of carbon carburized in the cathode material increases as the temperature rises, because the solubility of carbon that can dissolve in the cathode material increases as the reduction temperature increases, thus increasing the amount of carburization. At this time, the melting point decreases as the carbon is carburized, and even if the temperature increases further after the carbon is saturated, the melting point does not decrease any further. As the saturated carbon cools, its saturation solubility decreases again, and it begins to precipitate on the particle surface. This carbon precipitated on the particle surface exists in a band form at the grain boundaries of the alloy particles. At this time, if the cooling rate is slow, most of the carbon in the carbon layer precipitates at the grain boundaries, and if the cooling rate is very fast, the reduced cathode material and carbon become a solid solution, or precipitate in a point form inside the particles.

[0048] In one embodiment, the ratio of the major axis to the minor axis of the strip-shaped carburized layer may be 2 or more. Specifically, the ratio may be 10 or more. Specifically, the minor axis of the strip-shaped carburized layer represents the thickness of the carburized layer, and the major axis of the strip-shaped carburized layer represents the grain boundaries of the cathode alloy. If the ratio is less than 2 to 10, the cooling rate is slow and a point-shaped carburized layer is formed, and the effects intended by the present invention cannot be obtained.

[0049] The strip-shaped carburized layer, by satisfying the aforementioned ratio, has the advantage of facilitating the penetration of carbon into the alloy, thereby improving its reactivity to sulfuric acid leaching in subsequent wet smelting processes. However, if the ratio of the major axis to the minor axis of the strip-shaped carburized layer falls outside the aforementioned range, the aforementioned effect will not be achieved.

[0050] In one embodiment, the valuable metal recovery composition 10 contains lithium that, unlike Ni, Co, and Mn, cannot be reduced to form an alloy, but can combine with the Al component in the battery to form lithium oxide.

[0051] In one embodiment, the valuable metal recovery composition 10 may include a shell portion 120 disposed on a core portion 110. The shell portion 120 may be a lithium oxide disposed on the core portion 110.

[0052] The lithium oxide may include, for example, lithium-aluminum oxide. The lithium-aluminum oxide may be a lithium-aluminum compound. In the lithium-aluminum oxide, the lithium and aluminum contained in the composition can be physically or chemically bonded to each other and bonded together as an oxide.

[0053] In one embodiment, the lithium oxide may include LiAlO2, Li5AlO4, Li2CO3, and LiF. LiAlO2, Li5AlO4, and Li2CO3 are lithium oxides that react in the high-temperature reduction reaction process of battery waste, and LiF may be a lithium oxide detected by the electrolyte residue depending on the degree of pretreatment.

[0054] In one embodiment, the lithium compound may have an XRD peak with 2θ of at least one of the following ranges: 20.5–21.5°, 29.0–29.5°, 31.5–32.0°, 32.2–33.0°, 60.5–61.5°, 70.0–72.0°, 19.5–20.2°, 21.6–22.2°, 24.0–26.0°, 27.0–29.0°, 34.0–36.0°, 37.0–39.0°, 38.2–39.5°, 44.0–46.0°, 64.5–66.5°, and 77.77–79.77°.

[0055] In one embodiment, LiAlO2 may include at least one of the following XRD peaks: 20.5–21.5°, 29.0–29.5°, 31.5–32.0°, 32.2–33.0°, 60.5–61.5°, and 70.0–72.0°. A lO4 may contain at least one of the following XRD peaks: 19.5–20.2° and 21.6–22.2°.

[0056] The Li2CO3 composition may contain at least one of the following XRD peaks: 24.0–26.0°, 27.0–29.0°, 34.0–36.0°, and 37.0–39.0°. The LiF composition may contain at least one of the following XRD peaks: 38.2–39.5°, 44.0–46.0°, 64.5–66.5°, and 77.77–79.77°.

[0057] As described above, the valuable metal recovery composition 10 has an XRD peak value for at least one of LiAlO2, Li5AlO4, Li2CO3, and LiF, and it can be confirmed that the lithium compound is attached to and arranged on the core portion containing the valuable metal.

[0058] In one embodiment, the lithium compound partially bonded to the surface of the valuable metal recovery alloy can be separated using a wet process. In another embodiment, the lithium compound can be separated from the valuable metal recovery alloy by mechanical or physical external force. In this way, not only can the valuable metal recovery alloy be recovered from the valuable metal recovery composition 10, but the lithium compound can also be separated at the same time, resulting in a high lithium recovery rate and a reduction in the amount of lithium lost.

[0059] In one embodiment, the valuable metal recovery composition 10 may contain a carbon-based substance. The carbon-based substance may be, for example, the element carbon (C). The carbon content may be in the range of 1% to 7%. A carbon content within this range offers advantages in optimizing the wet processing of the valuable metal recovery composition.

[0060] If the carbon content falls outside the upper limit of the range, there is a problem of reduced leaching rate due to the formation of nickel carbide (Ni3C). If the carbon content falls outside the lower limit of the range, the content of other impurities such as Si increases, leading to a problem of reduced recovery rates of valuable metals such as Ni and Co in solvent extraction after the leaching process.

[0061] In one embodiment, the valuable metal recovery composition 10 may contain 10 to 30% by weight of aluminum (Al). The aluminum content meeting this range has the advantage of being able to form lithium compounds through physical or chemical bonding with lithium, and the subsequent separation of these lithium compounds can increase the lithium yield.

[0062] If the aluminum content falls outside the upper limit of the range, excessive Al2(SO4)3 is produced in the leaching and solvent extraction steps, leading to increased costs in the Ni, Co solvent extraction and crystallization steps, and a decrease in the recovery rate of Ni and Co. If the aluminum content falls outside the lower limit of the range, insufficient aluminum content leads to a decrease in the production of Li-Al-O oxide.

[0063] In one embodiment, the unit valuable metal recovery composition 100 contains aluminum (Al), and the concentration of aluminum (Al) may have a gradually increasing gradient from the interface between the core portion 110 and the shell portion 120 toward the shell portion 120. The reason why the concentration gradient of aluminum (Al) increases toward the shell portion 120 is that an oxide containing aluminum adheres to the core portion 110 which contains a valuable metal alloy.

[0064] A method for recovering valuable metals according to another embodiment of the present invention may include a step of preparing battery crushed material, a step of dry heat treating the crushed material, and a cooling step of cooling the dry heat treated product. In particular, as a method for producing an alloy with a high concentration content of the recovered valuable metal alloy, it may be a method for producing an alloy with a higher concentration content of valuable metals compared to the black powder obtained through the initial crushing step. Furthermore, the recovered valuable metal composition and the recovered valuable metal alloy produced by the above production method are identical to those shown in Figure 1 above, to the extent that they are not inconsistent with the above.

[0065] The step of preparing battery shredder involves either shredding a material that will become the base material of the battery shredder, or preparing the shredded material itself. The base material of the battery shredder can include waste materials in the manufacturing process of a lithium-ion battery, such as batteries that have reached the end of their lifespan, scrap, jelly rolls, and cathode materials such as slurry that make up the waste battery, defective products produced during the manufacturing process, residues within the manufacturing process, and generated fragments. The shredded material itself can be the shredded product itself, such as black powder.

[0066] In one embodiment, the step of preparing a battery or battery shredder in cell units may further include a step of crushing a material that will become the base material of the battery shredder, if the base material of the battery shredder is to be crushed. The crushed material can be obtained by using a crusher to obtain a pulverized product. The crushing is a non-limiting example and may include breaking the waste battery by applying physical or mechanical force and crushing it into a fine powder. The crushing step can separate some larger impurities in the composition contained in the waste battery, such as aluminum (Al), copper (Cu), iron (Fe), and plastics. The state in which the larger impurities have been separated is called black powder, and battery shredder such as black powder can be produced through the crushing step.

[0067] In one embodiment, the battery shredder is for recovering valuable metals from waste batteries and may be a layered structure including a separation membrane on which a positive or negative electrode is laminated on at least one surface. Specifically, the layered structure may include a configuration in which a positive or negative electrode is included on one or both surfaces of the separation membrane, with respect to the separation membrane. More specifically, the number of layers in the layered structure may correspond to the number of separation membranes.

[0068] The layered structure can include, for example, any one of the following: positive electrode-separator-negative electrode, positive electrode-separator, separation membrane-positive electrode, separation membrane-negative electrode, or negative electrode-separator. For example, positive electrode-separator-negative electrode-separator-positive electrode-separator-negative electrode may have a three-layered structure. Specifically, the battery shredder can have a predetermined thickness in the thickness direction by stacking at least one layer.

[0069] In one embodiment, the battery shredder can satisfy the following condition 1.

[0070] <Condition 1> The layered structure may be a laminated structure of 1 to 7 layers.

[0071] The aforementioned battery shredder may have a layered structure having one to seven layers. Specifically, the layered structure may have one to five layers.

[0072] The layered structure, when stacked within the aforementioned range, minimizes the temperature rise of the crushed material and allows for an appropriate heating time. If the layered structure is stacked to a thickness exceeding the upper limit of the aforementioned range, the temperature rise increases excessively, and the heating time also increases, leading to combustion and potentially causing a fire.

[0073] In one embodiment, the battery shredder can satisfy the following condition 2.

[0074] <Condition 2> The size of the crushed battery material may be 100 mm or less, based on the longest axis among the horizontal, vertical, and height directions.

[0075] In one embodiment, the battery shredder may have a size of 100 mm or less based on its long axis. Specifically, the size of the battery shredder may be 50 mm or less. If the size of the battery shredder is excessively large, there is a problem that the temperature of the battery shredder itself may rise to 100°C or higher, which could cause a fire.

[0076] In one embodiment, the battery fragments may include aluminum (Al), manganese (Mn), lithium (Li), copper (Cu), cobalt (Co), nickel (Ni), carbon (C), and residual impurities. In one embodiment, the black powder may contain 5-40 wt% nickel (Ni), 1-20 wt% cobalt (Co), 1-15 wt% manganese (Mn), 0.5-5 wt% lithium (Li), 10-70 wt% carbon (C), 0.0001-20 wt% aluminum (Al), and 0.0001-20 wt% copper (Cu), with the total amount of impurities such as iron (Fe) and phosphorus (P) being less than 10 wt%. The composition of the black powder may vary depending on the ratio of nickel, cobalt, and manganese, and the nickel, cobalt, and manganese can be adjusted by the cathode material oxide of the lithium secondary battery when the lithium secondary battery is crushed.

[0077] In one embodiment, the step of crushing the material that will become the base material of the battery shredder may be a crushing method utilizing at least one of shear, compression, and tensile forces. Specifically, the crushing step may be performed by at least one of a hammer mill, a ball mill, and a stirred ball mill, for example. The hammer mill may perform at least one of disassembly, punching, and milling, and this is a non-limiting example, and it is clear that a wide variety of crushing or grinding equipment, such as industrial grinders, can be used for grinding.

[0078] In one embodiment, the particle size of the battery fragments can be within 50 mm, specifically within 30 mm. If the particle size is larger than this range, a greater energy supply is required in the heat treatment stage described later, which is uneconomical.

[0079] In one embodiment, a pretreatment step may be further included before the step of crushing the material that will become the base material of the battery shreds, in order to prevent explosion or detoxify the base material of the battery shreds. By including the pretreatment step, explosive substances such as electrolyte in the base material can be removed, and the base material, such as a waste battery, can be discharged, thereby increasing safety during the crushing step and improving the recovery of valuable metals and productivity.

[0080] When a battery is used as the base material for the crushed battery material, the process may include a step of freezing the battery before crushing the crushed battery material. Direct crushing of the battery may cause an explosion and fire due to the electrolyte contained within the battery. Specifically, when a certain pressure is applied to the battery, the separator is physically crushed, a high current is formed due to a short circuit, and a spark is generated. This spark can cause the electrolyte to ignite, resulting in a fire.

[0081] The step of freezing the battery involves freezing the battery to suppress the ignition of the liquid electrolyte contained within it, and then carrying out the crushing process, thus preventing problems caused by electrolyte ignition.

[0082] In one embodiment, the step of freezing the battery can be carried out by cooling in the range of -150°C to -60°C. If the temperature is outside the upper limit of the above temperature range, the voltage remaining inside the battery may not drop to 0V, a battery reaction due to a short circuit may occur, and the electrolyte will not be completely frozen, which is not appropriate.

[0083] If the temperature falls outside the lower limit of the aforementioned temperature range, the electrolyte is sufficiently frozen, and the voltage inside the battery drops to 0V. Therefore, even if a short circuit occurs where the positive and negative electrodes are in direct contact, no battery reaction takes place, and the battery temperature does not rise, thus preventing the generation of electrolyte gas and combustion. Furthermore, because the electrolyte is frozen and the mobility of lithium ions is very low, the current-carrying characteristics due to lithium ion movement can be significantly reduced, and since the electrolyte does not vaporize, flammable gases such as ethylene, propylene, and hydrogen are not generated.

[0084] If the temperature exceeds the upper limit of the temperature range during the freezing stage of the battery, the voltage remaining inside the battery will not drop to 0V, which may cause a short circuit and battery reaction, and the electrolyte will not be completely frozen, making it unsuitable. If the temperature exceeds the lower limit of the temperature range, a large amount of energy must be supplied for freezing, which is uneconomical.

[0085] In one embodiment, the step of freezing the battery can be carried out by cooling it in a temperature range of -60 to -20°C under a vacuum atmosphere of 100 torr or less. The step of freezing the battery can be carried out in the temperature range that suppresses the vaporization of the electrolyte. The vacuum atmosphere may be, for example, an inert gas, carbon dioxide, nitrogen, water, or a combination thereof.

[0086] By adjusting the pressure to a vacuum atmosphere of 100 torr or less, the oxygen supply is suppressed, preventing the electrolyte from reacting with oxygen and thus preventing explosions. Furthermore, the vaporization of the electrolyte is suppressed, thus preventing the generation of flammable gases such as ethylene, propylene, and hydrogen.

[0087] When freezing the battery, if the process is carried out in an air atmosphere or under a pressure exceeding 100 torr, some voltage may remain inside the battery. Since the electrolyte is not frozen at a temperature range of -60 to -20°C, a spark generated when a short circuit occurs due to the remaining voltage can vaporize the electrolyte and cause an explosion.

[0088] In one embodiment, the pretreatment step may include a step of forcibly discharging the waste battery or battery shredder. The forcibly discharging step is a step of lowering the voltage of the waste battery or battery shredder, which can enhance safety, recover valuable metals, and increase productivity during the shredding process. The forcibly discharging step may be, for example, saltwater discharge or electrical discharge.

[0089] The step of dry heat treatment of the crushed material involves placing the crushed material into a heating furnace capable of raising its temperature to a level above its melting point. The step of dry heat treatment of the crushed material may involve heat treatment conditions that allow for a high-temperature reduction reaction without going through a melting stage.

[0090] In one embodiment, the heat treatment conditions can be in the range of 1,100 to 1,800°C. Specifically, the range can be 1,150 to 1,400°C, and more specifically, 1,200 to 1,400°C. If the temperature is outside the upper limit of the range, there is a problem of loss due to lithium vaporization, and if it is outside the lower limit of the range, sintering and reduction of the alloying elements do not occur, and there is a problem of excessive flake formation. Within the temperature range, the reduction reaction can be carried out in a state where carbon in the crushed material is burned to the minimum extent possible, resulting in almost no carbon dioxide generation.

[0091] In one embodiment, the step of dry heat treatment of the crushed material can be carried out in a gas atmosphere of at least one of an inert gas, carbon dioxide, carbon monoxide, and hydrocarbon gas. In the case of the inert gas, for example, at least one of argon and nitrogen can be included. By carrying out the reduction reaction of the crushed material in the gas atmosphere, a valuable metal recovery alloy containing valuable metals as components contained in the crushed material can be effectively recovered.

[0092] In one embodiment, a portion of the gas atmosphere may contain impurities, including residual oxygen. If the oxygen content in the impurities is high, it may combine with components of the crushed material during the reduction reaction to form carbon dioxide, which can lead to the problem of gasification together with lithium and difficulty in recovery.

[0093] In one embodiment, the oxygen content may be 5% or less during the dry heat treatment stage. More specifically, the oxygen content may be 1% or less, and more specifically, 0.1% or less. Specifically, if the partial pressure of oxygen exceeds the range described above, there is a problem of lithium loss and the generation of large amounts of carbon dioxide in localized high-temperature conditions.

[0094] Specifically, the valuable metal recovery composition, which is an alloy of components such as nickel, cobalt, manganese, and lithium-containing oxides in the crushed material during the dry heat treatment stage, may contain valuable metals and residual impurities. The valuable metal recovery composition may contain, for example, aluminum (Al), manganese (Mn), lithium (Li), copper (Cu), cobalt (Co), nickel (Ni), carbon (C), and residual impurities, and a detailed explanation thereof is the same as that of the valuable metal recovery composition described above in Figure 1, to the extent that it is not inconsistent.

[0095] The valuable metal recovery composition may contain a lithium compound, which can be produced by the reduction reaction. In one embodiment, the aluminum content in the valuable metal recovery composition may be 0.25 to 30% by weight. The more aluminum added, the lower the stabilization temperature during the formation of the lithium compound, for example, lithium-alumina (LiAlO2).

[0096] If the aluminum content falls outside the upper limit of the range, Li-Al-O oxide (LiAl) has a high Al2O3 content. 11 O 17 The formation of ) leads to a problem of reduced Li recovery rate. If the aluminum content falls outside the lower limit of the range, the Al2O3 content does not reach the target, resulting in a problem of reduced Li-Al-O oxide formation.

[0097] In one embodiment, a stirring step can be added to the heat treatment furnace. This stirring step can be carried out, for example, by using a rotating body or gas to promote the reaction in the heat treatment furnace, which is a high-temperature reduction furnace, and to ensure uniformity of the internal temperature. A valuable metal recovery composition can be recovered by the reduction reaction of black powder in the heat treatment furnace.

[0098] The cooling step, which involves cooling the dry heat-treated product, may be a step that assists in the leaching of carbon layers within the valuable metal alloy by cooling the dry heat-treated product. Specifically, the cooling step may be a step that adjusts the rate and shape at which carburized carbon precipitates along the grain boundaries of particles during the reduction process of the cathode material.

[0099] In one embodiment, the cooling step for cooling the dry heat-treated product may be carried out in the range of 10 to 50°C / min. Specifically, the cooling step may be carried out in the range of 20 to 30°C / min.

[0100] The cooling step has the advantage that by lowering the temperature at the aforementioned cooling rate, the deposited carbon is stably deposited in a band shape at the grain boundaries of the cathode alloy. However, if the cooling step is performed outside the aforementioned rate range, there is a problem that the carbon may be deposited in a point shape inside the particles, or in a planar shape at the grain boundaries with respect to the cross-section of the particles.

[0101] In one embodiment, the process may further include a step of separating the resulting material after the cooling step by at least one of particle size separation and magnetic separation. Specifically, the separation step can separate the resulting material after the cooling step, for example, a valuable metal recovery composition, by at least one of particle size separation and magnetic separation. The particle size separation method is a method of separating according to the size or diameter of the particles and can include a variety of methods, for example, using a sieve. The magnetic separation method can utilize a magnetic material to separate particles through contact with the magnetic material, and a variety of magnetic separation methods can be applied.

[0102] In one embodiment, the step of separating the resulting material after the cooling step by at least one of particle size separation and magnetic separation may be a step of separation by at least one of particle size separation, magnetic separation, and specific gravity difference separation. The specific gravity difference separation is a method of separating particles by taking into account the difference in specific gravity of different substances, and for example, by utilizing a specific solvent, particles can be separated based on the magnitude of the specific gravity of the particles corresponding to the specific solvent, and various types of specific gravity difference separation methods can be applied.

[0103] In one embodiment, the step of separating the cooled crushed material by at least one of particle size separation and magnetic separation includes all of the steps of particle size separation, magnetic separation, and steps performed together with particle size separation and magnetic separation, thereby enabling the separation of the valuable metal recovery alloy. In the step of performing only particle size separation, the valuable metal recovery alloy can be recovered by particle size separation alone from a valuable metal recovery composition with a particle size of 100 μm to 100 mm or less.

[0104] In the case of magnetic separation, if the valuable metal recovery composition contains a substance with a particle size of 100 μm or less, the valuable metal can be recovered from the valuable metal recovery composition by magnetic separation alone. In the case of the substance with a particle size of 100 μm or less, since its particle size is similar to that of carbon, the recovery rate of valuable metals that would be lost by particle size separation alone can be increased through magnetic separation.

[0105] In one embodiment, when the particle size separation and magnetic separation are performed together, the magnetic separation can be performed first, followed by the particle size separation. By performing the magnetic separation first, the loss of the valuable metal recovery alloy from the valuable metal recovery composition with particles smaller than 100 μm can be prevented.

[0106] In one embodiment, the step of separating the cooled crushed material by at least one of particle size separation and magnetic separation may further include a step of separating the valuable metal alloy from the lithium-containing lithium compound disposed on the valuable metal. The step of separating the lithium-containing lithium compound may be performed before or after the step of separating the cooled crushed material by at least one of particle size separation and magnetic separation.

[0107] The lithium compound may be, for example, a lithium-containing oxide, which can be separated by physical force. A detailed explanation of this can be found in the valuable metal recovery composition shown in Figure 1, to the extent that it is consistent with the description. In this way, by separating the lithium-containing oxide by physical force, the recovery rate of not only the valuable metal but also the lithium can be increased. [Examples]

[0108] To illustrate the present invention in more detail, embodiments of the present invention are described below. The embodiments described below are merely one example of the present invention, and the present invention is not limited to these embodiments.

[0109] <Example of experiment> <Example 1> Steps to prepare a valuable metal recovery composition A cell, module, or pack of a used electric vehicle battery is prepared, containing a lithium-ion positive electrode material, a graphite negative electrode material, an aluminum current collector, a separator membrane, an electrolyte, and a copper current collector. The used battery is frozen at -30°C or below, then crushed, and then shredded using a shredder under inert gas conditions so that the longest horizontal and vertical length of the used battery is 100 mm or less.

[0110] After obtaining a valuable metal recovery composition by the method described above, the crushed battery fragments were heat-treated at 1,300°C under an oxygen partial pressure of 0.5% to perform a reduction process. After the reduction process, the reduced product was cooled at a cooling rate of 25°C / min to obtain a valuable metal recovery composition.

[0111] Figure 1 is an SEM image of a valuable metal recovery composition according to one embodiment of the present invention.

[0112] Figures 2a and 2b show the results of XRD analysis of a valuable metal recovery composition according to one embodiment.

[0113] Referring to Figures 1, 2a, and 2b, it can be seen that in the valuable metal recovery composition, lithium compounds, specifically lithium oxides, are bonded and arranged on a valuable metal recovery alloy. Such a structure may be formed by the reduction process described above.

[0114] <Comparative example 1> - Cooling rate 5℃ / min or less A valuable metal recovery composition was obtained under the same conditions as in Example 1, except that the cooling rate was 3°C / min.

[0115] <Comparative Example 2> - Reduction temperature 1,100℃ or less A valuable metal recovery composition was obtained under the same conditions as in Example 1, except that the reduction temperature was 1,100°C or lower.

[0116] <Comparative example 3> - Cooling rate 100℃ / min or more A valuable metal recovery composition was obtained under the same conditions as in Example 1, except that the cooling temperature during the cooling stage was 100°C / min.

[0117] <Evaluation Example 1> - Component content on alloy surface Figures 3 and 4 show SEM images of the valuable metal alloy of the present invention.

[0118] Figures 3 and 4 are SEM images showing the shape within a valuable metal alloy, relating to one embodiment of the present invention.

[0119] Tables 1 and 2 below show the results of observing the surface of the valuable metal alloy in Spectrum 1 and Spectrum 2 using SEM and measuring the component content with EDAX. Spectrum 1 and Spectrum 2 were defined as follows, and the component content was measured using the method described below.

[0120] Spectrum 1: The gray area in Figures 3 and 4, which are SEM images of a valuable metal alloy, represents the carbon layer.

[0121] Spectrum 2: These are SEM images of valuable metal alloys, showing bright color regions in Figures 3 and 4, which represent lithium-containing compounds, specifically lithium aluminate (LiAlO2).

[0122] [Table 1]

[0123] [Table 2]

[0124] Figures 3 and 4 and Tables 1 and 2 show that in Example 1, the carbon content in area 1 is 76-92%. This confirms that graphite adheres to the surface of the valuable metal recovery alloy in the valuable metal recovery composition produced by the example of the present invention, or that graphite precipitated during the cooling process contains areas with high carbon content. Thus, in comparative examples where the oxygen concentration during the reduction process and the cooling rate during the cooling stage do not fall within the range of the present invention, it was confirmed that the graphite content is low and a carbon layer cannot be formed. In contrast, Example 1 has the advantage that, by containing a carbon layer, the alloy particles are easily crushed by external force during the wet smelting process, and lithium oxide can be pre-leached.

[0125] <Evaluation Example 2> - Component content of alloy cross-section Figure 5 shows an SEM image of a cross-section of the valuable metal alloy of the present invention.

[0126] Figure 5 shows a cross-section of a valuable metal alloy according to one embodiment of the present invention, observed with an SEM image and its composition measured with EDAX. Specifically, regions 1 (Spectrum 1) and 2 (Spectrum 2) represent carbon, region 3 (Spectrum 3) represents a lithium compound bonded with Al, and region 4 (Spectrum 4) represents an NCM alloy.

[0127] Table 3 below shows the results of observing cross-sections of valuable metal alloys in areas 1, 2, 3, and 4 using SEM images and measuring the component content with EDAX.

[0128] [Table 3]

[0129] As shown in Table 3, in the cross-sectional photograph of the alloy particles, the gray areas distributed in a band shape within the particles are carbon deposited at the grain boundaries of the alloy particles by regions 1 and 2. As in the examples, it was confirmed that when the reducing atmosphere and oxygen concentration are within the range of the present invention, and the cooling rate is within the range of the present invention, the carburized carbon precipitates in a band shape. In contrast, in the comparative examples, particularly Comparative Example 1, when the cooling rate is lower than in the examples, the precipitated carbon diffuses into the cross-section of the alloy particles, reducing the ratio of the major axis to the minor axis of the band-shaped carbon layer, and causing the carbon to remain in the alloy in a point shape. Figures 6 to 8 show the EPMA analysis results of the comparative examples of the present invention.

[0130] Referring to Figure 6, in the case of Comparative Example 1, where the cooling rate is slow, there is insufficient time for the carbon carburized at high temperature to gradually diffuse onto the particle surface. Therefore, the carburized layer is not observed within the droplet grain boundaries where the reduced cathode material particles are aggregated, but only on the outer surface of the droplet.

[0131] Referring to Figure 7, in the case of Comparative Example 2, where the reduction temperature is low, lithium aluminate is not coated on the surface of the cathode alloy. Because the reduction temperature of the cathode material is low and the amount of carbon carburized inside the particles is small, the cooling rate is low and droplets of the reduced alloy are not formed well. It was also confirmed that the deposited carburized layer precipitates in a point morphology with a short major-minus ratio.

[0132] Figure 8 shows that, as in Comparative Example 3, when the cooling rate is rapidly accelerated, the carbon that was carburized at high temperature and melted inside the particles does not diffuse and precipitate at grain boundaries or on the droplet surface, but rather precipitates in a solid-solution state inside. Specifically, it was confirmed that when rapidly cooled, the carbon does not show any particular tendency to precipitate inside the cathode alloy droplet.

[0133] The present invention is not limited to the embodiments described above, and can be manufactured in a variety of different forms. Those with ordinary skill in the art to which the invention pertains should understand that it can be implemented in other specific forms without altering the technical idea or essential features of the invention. Therefore, it should be understood that the embodiments described above are illustrative and not limiting in all respects.

Claims

1. Valuable metal recovery alloys containing a carbon layer; and Contains lithium compounds, The carbon layer is arranged in at least a portion of the surface and interior of the valuable metal recovery alloy. A valuable metal recovery composition wherein the carbon (C) content in the carbon layer is 60% by weight or more, based on 100% by weight of the carbon layer.

2. The valuable metal recovery composition according to claim 1, wherein at least a portion of the lithium compound is bonded to at least a portion of the surface of the valuable metal recovery alloy.

3. The carbon layer is placed on the surface of the valuable metal recovery alloy, The valuable metal recovery composition according to claim 1, wherein the total amount of Ni, Co, and Mn in the carbon layer is 50% by weight or less, based on 100% by weight of the carbon layer.

4. The carbon layer is placed inside the valuable metal recovery alloy. The valuable metal recovery composition according to claim 1, wherein the carbon layer is arranged as a strip-shaped carburized layer on the cross-section of the valuable metal recovery alloy.

5. The valuable metal recovery composition according to claim 4, wherein the strip-shaped carburized layer has a ratio of major axis to minor axis of 2 or more.

6. The lithium compound is recovered from a waste battery containing lithium oxide, as described in claim 1.

7. The lithium oxide is recovered from a waste battery containing lithium aluminum oxide, as described in claim 6.

8. The valuable metal recovery composition according to claim 1, wherein the valuable metal comprises at least one of lithium (Li), cobalt (Co), nickel (Ni), aluminum (Al), and manganese (Mn).

9. The stage of preparing individual battery cells or battery fragments; A step of performing dry heat treatment at a temperature range of 1,100 to 1,800°C without going through the melting step of the battery or the crushed material; A method for recovering valuable metals, comprising a cooling step of cooling the dry heat-treated product at a cooling rate of 10 to 50°C / minute.

10. The method for recovering valuable metals according to claim 9, wherein the high-temperature reduction reaction step is carried out in an atmosphere with an oxygen content of 5% or less.

11. A method for recovering valuable metals according to claim 9, further comprising the step of separating the resulting material after the cooling step by at least one of particle size separation and magnetic separation.

12. The method for recovering valuable metals according to claim 9, wherein the step of separating the product obtained after the cooling step by at least one of particle size separation and magnetic separation is to perform magnetic separation first, followed by particle size separation.

13. The method for recovering valuable metals according to claim 9, wherein the result obtained from the step of dry heat treatment of the crushed material separates lithium compounds bound to a part of the surface of the valuable metal recovery alloy by external force.

14. The method for recovering valuable metals according to claim 9, wherein the step of preparing the cell-unit battery or battery shredder includes a step of pre-treating the cell-unit battery or battery shredder.

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