Valuable metal recovery alloy and method for preparing same

Abstract

The present invention relates to a valuable metal recovery alloy and a method for preparing same. Specifically, the present invention relates to: a valuable metal recovery alloy obtained by a dry high-temperature reduction treatment of LFP-containing waste batteries; and a method for preparing same.

Description

Precious metal recovery alloy and method for manufacturing the same

[0001] The present invention relates to a valuable metal recovery alloy and a method for manufacturing the same. Specifically, it relates to a valuable metal recovery alloy obtained by dry high-temperature reduction treatment of LFP-containing waste batteries and a method for manufacturing the same.

[0002] This application claims priority to Korean Patent Application No. 10-2024-0190991, filed on December 19, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] As global demand for electric vehicles (EVs) intensifies, the issue of disposing of waste batteries generated from these vehicles is emerging as a social concern. Lithium-ion batteries, which serve as the primary raw material for these waste batteries, contain organic solvents, explosive substances, and heavy metals such as Ni, Co, Mn, and Fe. However, given the scarcity value of Ni, Co, Mn, and Li as precious metals, the recovery and recycling processes following the disposal of lithium-ion batteries are becoming a critical area of ​​research.

[0005] LFP batteries, along with NCM batteries, are a secondary battery material attracting attention as a power source for the electric vehicle era. LFP batteries utilize iron and phosphorus for the cathode, graphite for the anode, and lithium as the positively charged metal. The conventional LFP battery recycling process involves physically separating waste batteries or cathode scrap to produce Black Mass, from which lithium is recovered through wet purification using sulfuric acid. However, during this process, if the pH of Fe and P—excluding lithium—is raised above 4 during the iron removal process, they transform into FePO4 and Fe-P-OH hydroxides, respectively; these are classified as residue (waste) and discarded. This residue contains a mixture of FePO4, Fe and P hydroxides, and a small amount of graphite from the anode, making separation extremely difficult. Consequently, the residue is excluded from recovery targets due to its lack of economic value. This results in a low recovery rate of valuable metals relative to the costs incurred in the waste battery recycling process, necessitating a method to address this issue. Specifically, there is a need for a method to recover not only lithium but also the aforementioned Fe and P components separately.

[0006] Accordingly, the present invention proposes a process for separating an LFP battery into three materials—an Fe-P alloy, a lithium compound, and graphite—through a dry high-temperature reduction process, and proposes a method for producing a high-concentration Fe-P alloy containing more than 15% P through a reduction process and a selection process for the Fe-P alloy.

[0007]

[0008] The technical problem that the present invention aims to solve is to provide a valuable metal recovery alloy that is easy to magnetically separate, comprising Fe-P alloy particles containing a high concentration of P.

[0009] Another technical problem that the present invention aims to solve is to provide a method for manufacturing a valuable metal recovery alloy having the aforementioned advantages.

[0010] A valuable metal recovery alloy according to one embodiment of the present invention may include Fe-P alloy particles in which the weight ratio of phosphorus (P) element to iron (Fe) element, [P] / [Fe], is 0.15 or higher.

[0011] A valuable metal recovery alloy according to one embodiment of the present invention can satisfy the following Equation 1 when X-ray diffraction analysis is performed.

[0012] [Equation 1]

[0013] 0≤I(Fe-PO) / I(Fe-P)≤0.1

[0014] (In Equation 1 above, I(Fe-PO) and I(Fe-P) represent the XRD maximum peak intensity of the Fe-PO compound contained in the valuable metal recovery alloy and the XRD maximum peak intensity of the Fe-P alloy particles, respectively.)

[0015] In one embodiment of the present invention, the average particle size of the Fe-P alloy particles in the valuable metal recovery alloy may be 50 to 5000 μm.

[0016] In a valuable metal recovery alloy according to one embodiment of the present invention, the Fe-P alloy particles may have an elliptical or spherical shape, and the surface of the Fe-P alloy particles may be in a form in which an oxide containing at least one of oxygen (O), aluminum (Al), carbon (C), and lithium (Li) is attached.

[0017] In one embodiment of the present invention, the titanium (Ti) content may be 1 weight% or less based on 100% of the total weight of the valuable metal recovery alloy.

[0018] A valuable metal recovery alloy according to one embodiment of the present invention may include Fe-P alloy particles alloyed with copper (Cu).

[0019] In a valuable metal recovery alloy according to one embodiment of the present invention, the Fe-P alloy particles may include at least one of FeP, Fe2P, and Fe3P.

[0020] A method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention comprises: a raw material preparation step of preparing scrap of a lithium iron phosphate (LFP) battery or a spent lithium iron phosphate (LFP) battery as a raw material; a mixing step of adding a reducing agent to the raw material to form a mixture; a calcination step of heat-treating the mixture to form a calcined product; and a sorting step of separating the calcined product to select a valuable metal recovery alloy; wherein, in the mixing step, the ratio of the amount of reducing agent added based on 1 mole of LiFePO4 content in the raw material may be 1.2 or more.

[0021] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, in the mixing step, the reducing agent is C, Al, Si, Ca, H2 (hydrogen gas), C x H y It may be one or more selected from (hydrocarbons in which 1≤x≤10, 4≤y≤22).

[0022] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, in the selection step, the valuable metal recovery alloy may include Fe-P alloy particles in which the weight ratio of phosphorus (P) element to iron (Fe) element, [P] / [Fe], is 0.15 or higher.

[0023] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the heat treatment temperature in the sintering step may be 800 to 1300 ℃.

[0024] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the time for maintaining the maximum temperature during heat treatment in the sintering step may be 10 minutes or more.

[0025] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the oxygen concentration in the furnace during heat treatment in the sintering step may be 5 vol% or less.

[0026] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the method of separating the valuable metal recovery alloy in the separation step may be selected from at least one of magnetic separation, particle size separation, and specific gravity separation.

[0027] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the sintered material in the selection step contains a magnetic material and a non-magnetic material, and the content of the magnetic material may be greater than 15 weight% and less than or equal to 25 weight% based on 100% of the total weight of the sintered material.

[0028]

[0029] A valuable metal recovery alloy according to one embodiment of the present invention includes Fe-P alloy particles containing a high concentration of P, which facilitates the separation of magnetic and non-magnetic components, thereby improving the recovery rate of valuable metals.

[0030] A method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention can provide a valuable metal recovery alloy having the aforementioned advantages of lithium.

[0031]

[0032] FIG. 1 is a schematic diagram showing the process of a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention.

[0033] Figure 2 shows the XRD analysis results of the valuable metal recovery alloy according to Example 1.

[0034] Figure 3 shows the XRD analysis results of the valuable metal recovery alloy according to Comparative Example 1.

[0035] Figure 4 is an SEM image of a valuable metal recovery alloy according to one embodiment of the present invention.

[0036]

[0037] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. 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 present invention.

[0038] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of “comprising” specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0039] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0040] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0041] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0042] In this specification, the term “combination(s) of these” described in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expression, and means including any one or more selected from the group consisting of said components.

[0043] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0044]

[0045] A valuable metal recovery alloy according to one embodiment of the present invention will be described below.

[0046] 1. Valuable metal recovery alloy

[0047] A valuable metal recovery alloy according to one embodiment of the present invention may include Fe-P alloy particles in which the weight ratio of phosphorus (P) element to iron (Fe) element, [P] / [Fe], is 0.15 or higher.

[0048] Preferably, the [P] / [Fe] may be 0.15 or more and 1 or less, 0.15 or more and 0.8 or less, 0.15 or more and 0.7 or less, or 0.15 or more and 0.67 or less.

[0049] When the above [P] / [Fe] satisfies the aforementioned range, it may be easy to separate the metal component, particularly the Fe-P alloy, from a valuable metal recovery composition mixed with Fe-P alloy, lithium compound, and graphite using magnetic separation.

[0050] On the other hand, if the [P] / [Fe] ratio does not satisfy the aforementioned range, the Fe-P alloy may be contained in a small amount within the valuable metal recovery alloy. Furthermore, at temperatures of 1000 to 1300°C, the reduction reaction rate decreases, which may result in a large amount of Fe-PO oxide remaining within the valuable metal recovery alloy. Even if Fe-P alloy is formed, the average particle size is small, which may cause problems in separating it when a screening process is performed later. In particular, if the P content drops below 5 weight%, the melting point of Fe-P rises sharply, making it difficult for the Fe-P component and the Cu component to blend together; consequently, Fe-P with a small average particle size is inevitably produced. Consequently, when the P content is 5 weight% or less, the heat treatment temperature must be maintained at a high level of 1300°C or higher during the manufacturing process of the valuable metal recovery alloy to increase the particle size of the Fe-P alloy particles. However, if the heat treatment temperature becomes excessively high as described above, lithium vaporizes and is lost, which inevitably leads to a lower lithium recovery rate from the valuable metal recovery alloy.

[0051] A valuable metal recovery alloy according to one embodiment of the present invention can satisfy the following Equation 1 when X-ray diffraction analysis is performed.

[0052] [Equation 1]

[0053] 0≤I(Fe-PO) / I(Fe-P)≤0.1

[0054] (In Equation 1 above, I(Fe-PO) and I(Fe-P) represent the XRD maximum peak intensity of the Fe-PO compound contained in the valuable metal recovery alloy and the XRD maximum peak intensity of the Fe-P alloy particles, respectively.)

[0055] When the above Equation 1 is satisfied, the reduction reaction for the LFP battery raw material proceeds well, so that there is little or no Fe-PO oxide, and the Fe-P alloy is formed with an appropriate particle size, so that a valuable metal recovery alloy that is easy to magnetically separate can be formed.

[0056] In this specification, the LFP battery raw material means that it includes scrap of lithium iron phosphate (LFP) batteries and waste lithium iron phosphate (LFP) batteries. At least one of the LFP battery scrap and waste LFP batteries may be selected as the LFP battery raw material.

[0057] On the other hand, if the upper limit of Equation 1 above is exceeded, magnetic separation may not be easy because a large amount of impurities remain in the valuable metal recovery alloy and the content of reduced Fe-P alloy particles is significantly low. Consequently, it is difficult to finely separate metals, lithium compounds, and graphite, and there may be a problem where the amount of valuable metals discarded as residue increases.

[0058] In one embodiment of the present invention, the average particle size of the Fe-P alloy particles in the valuable metal recovery alloy may be 50 to 5000 μm.

[0059] When the average particle size of Fe-P alloy particles satisfies the aforementioned range, valuable metals can be effectively separated by magnetic separation.

[0060] However, if the average particle size of the above Fe-P alloy particles is less than the lower limit of the aforementioned range, magnetic separation may not be easy because the Fe-P alloy particles are too small. In addition, it may be more difficult to separate them because their particle size is similar to that of graphite particles.

[0061] Figure 4 is an SEM image of a valuable metal recovery alloy according to one embodiment of the present invention.

[0062] Referring to FIG. 4 above, in a valuable metal recovery alloy according to one embodiment of the present invention, the Fe-P alloy particles may have an elliptical or spherical shape, and the surface of the Fe-P alloy particles may be in a form in which an oxide containing at least one of oxygen (O), aluminum (Al), carbon (C), and lithium (Li) is attached.

[0063] Fe-P alloy particles having the above-described shape have the advantage of being able to efficiently recover valuable metals such as lithium or aluminum. In particular, since the particles exhibit an elliptical or spherical shape, they can increase the efficiency of the metal extraction reaction, thereby improving process speed and efficiency. In other words, they have the advantage of improving the productivity of the valuable metal recovery process.

[0064] In one embodiment of the present invention, the titanium (Ti) content may be 1 weight% or less based on 100% of the total weight of the valuable metal recovery alloy.

[0065] If the Ti content satisfies the aforementioned range, there is an advantage in that the valuable metal recovery alloy of the present invention can be utilized as a raw material in the steel or battery fields without a separate refining process.

[0066] On the other hand, when the Ti content in Fe-P alloys is high, utilizing such alloys as raw materials in the steel or battery industries can lead to problems such as reduced product quality and increased production costs. For instance, in the steel industry, it can degrade the physical properties of steel or cause issues during casting or machining processes. Ti readily forms carbides (TiC) and nitrides (TiN) within steel, which lowers the ductility and toughness of the steel, potentially increasing the risk of product cracking and fracture. As another example, in the battery industry, Ti can degrade the conductivity and reactivity of electrode materials, leading to reduced battery capacity and shortened lifespan. Furthermore, it can hinder ion movement, resulting in increased internal resistance and reduced thermal stability. Additionally, since removing Ti, which acts as an impurity, from Fe-P alloys may require additional purification processes, it can increase production costs and time; moreover, even if purification is performed, there is a problem in that chemically stable Ti cannot be easily removed.

[0067] A valuable metal recovery alloy according to one embodiment of the present invention may include Fe-P alloy particles alloyed with copper (Cu).

[0068] When Fe-P alloy particles are alloyed with Cu, the average particle size of the Fe-P alloy particles becomes above a certain level, making magnetic separation easier.

[0069] In a valuable metal recovery alloy according to one embodiment of the present invention, the Fe-P alloy particles may include at least one of FeP, Fe2P, and Fe3P.

[0070]

[0071] A method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention will be described below.

[0072] 2. Method for manufacturing valuable metal recovery alloys

[0073] FIG. 1 is a schematic diagram showing the process of a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention.

[0074] Referring to FIG. 1 above, a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention comprises: a raw material preparation step of preparing scrap of a lithium iron phosphate (LFP) battery or a spent lithium iron phosphate (LFP) battery as a raw material; a mixing step of adding a reducing agent to the raw material to form a mixture; a calcination step of heat-treating the mixture to form a calcined product; and a sorting step of separating the calcined product to select a valuable metal recovery alloy; wherein, in the mixing step, the ratio of the amount of reducing agent added based on 1 mole of LiFePO4 content in the raw material may be 1.2 or more.

[0075] Preferably, the ratio of the reducing agent input amount may be 1.2 or more and 2.0 or less, 1.2 or more and 1.625 or less, 1.2 or more and 1.5 or less, or 1.5 or more and 1.625 or less.

[0076] When the ratio of the reducing agent input satisfies the aforementioned range, the LiFePO4 component contained in the LFP battery raw material can be completely reduced by high-temperature heat treatment.

[0077] On the other hand, if the ratio of the reducing agent input is below the lower limit of the aforementioned range, some LiFePO4 components may not be reduced and may remain in the alloy for recovering valuable metals. This may result in a decrease in the amount of Fe-P obtained and an increase in the amount of Fe and P lost.

[0078] In this specification, the phrase "preparing scrap of lithium iron phosphate (LFP) batteries or waste lithium iron phosphate (LFP) batteries as raw materials" means selecting and using at least one of the scrap of lithium iron phosphate (LFP) batteries or waste lithium iron phosphate (LFP) batteries as raw materials. That is, it can encompass both utilizing the scrap of lithium iron phosphate (LFP) batteries and waste lithium iron phosphate (LFP) batteries as separate raw materials, or utilizing a mixture of the scrap and waste batteries as raw materials.

[0079] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, in the mixing step, the reducing agent is C, Al, Si, Ca, H2 (hydrogen gas), C x H y It may be one or more selected from (hydrocarbons in which 1≤x≤10, 4≤y≤22).

[0080] In the method for manufacturing a valuable metal recovery alloy according to the present invention, the reducing agent may be used by mixing various types. In particular, even if a reducing agent of various components is mixed, if the total amount of reducing agent input is 1.2 times or more of the theoretical amount (based on mole) capable of completely reducing LiFePO4, the entire amount of LiFePO4 can be substantially reduced to form Fe-P alloy particles. As a result, no LiFePO4 remains in the valuable metal recovery alloy, and Fe and P can be obtained to the maximum extent.

[0081] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, in the selection step, the valuable metal recovery alloy may include Fe-P alloy particles in which the weight ratio of phosphorus (P) element to iron (Fe) element, [P] / [Fe], is 0.15 or higher.

[0082] Preferably, the [P] / [Fe] may be 0.15 or more and 1 or less, 0.15 or more and 0.8 or less, 0.15 or more and 0.7 or less, or 0.15 or more and 0.67 or less.

[0083] When the above [P] / [Fe] satisfies the aforementioned range, it may be easy to separate the metal component, particularly the Fe-P alloy, from a valuable metal recovery composition mixed with Fe-P alloy, lithium compound, and graphite using magnetic separation.

[0084] On the other hand, if the [P] / [Fe] ratio does not satisfy the aforementioned range, the Fe-P alloy may be contained in a small amount within the valuable metal recovery alloy. Furthermore, at temperatures of 1000 to 1300°C, the reduction reaction rate decreases, which may result in a large amount of Fe-PO oxide remaining within the valuable metal recovery alloy. Even if Fe-P alloy is formed, the average particle size is small, which may cause problems in separating it when a screening process is performed later. In particular, if the P content drops below 5 weight%, the melting point of Fe-P rises sharply, making it difficult for the Fe-P component and the Cu component to blend together; consequently, Fe-P with a small average particle size is inevitably produced. Consequently, when the P content is 5 weight% or less, the heat treatment temperature must be maintained at a high level of 1300°C or higher during the manufacturing process of the valuable metal recovery alloy to increase the particle size of the Fe-P alloy particles. However, if the heat treatment temperature becomes excessively high as described above, lithium vaporizes and is lost, which inevitably leads to a lower lithium recovery rate from the valuable metal recovery alloy.

[0085] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the heat treatment temperature in the sintering step may be 800 to 1300 ℃.

[0086] Preferably, the heat treatment temperature may be 900 to 1300 ℃, 900 to 1200 ℃, 1000 to 1300 ℃, 1000 to 1200 ℃, 1050 to 1200 ℃, 1000 to 1100 ℃, or 1050 to 1100 ℃.

[0087] When the above heat treatment temperature satisfies the aforementioned range, it is easy to reduce the LiFePO4 component in the LFP battery raw material to an Fe-P alloy while preventing loss due to lithium vaporization. In addition, Fe-P alloy particles can be grown to a particle size that facilitates magnetic separation.

[0088] On the other hand, if the heat treatment temperature is below the lower limit of the aforementioned range, a large amount of residual LiFePO4 components that are not reduced may exist. In addition, even if Fe-P alloy particles are formed, the particles do not grow sufficiently, making it difficult to separate them by magnetic separation. At temperatures below 1000 ℃, Cu does not melt well and cannot fuse with Fe-P alloy particles, so the particle size of the Fe-P alloy particles cannot increase sufficiently, which causes the above problem.

[0089] In addition, if the heat treatment temperature exceeds the upper limit of the aforementioned range, the particle size of the Fe-P particles can grow sufficiently to facilitate magnetic separation, but at temperatures exceeding 1300°C, lithium vaporizes and is lost, resulting in the formation of a valuable metal recovery alloy with a low recovery rate of valuable metals. In order to improve the recovery rate of valuable metals, it is necessary to proceed with high-temperature reduction by adhering to the aforementioned heat treatment temperature.

[0090] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the time for maintaining the maximum temperature during heat treatment in the sintering step may be 10 minutes or more.

[0091] Preferably, the time for maintaining the maximum temperature during the heat treatment may be 10 minutes or more and 30 minutes or less.

[0092] When the maximum temperature holding time (hereinafter referred to as the heat treatment time) during the above heat treatment satisfies the aforementioned range, the Fe-P alloy particles can grow sufficiently to have a particle size that facilitates magnetic separation.

[0093] On the other hand, if the above heat treatment time does not satisfy the aforementioned range, not only do the Fe-P alloy particles fail to grow sufficiently, but LiFePO4 compounds that failed to undergo reduction reactions also remain within the valuable metal recovery alloy. Consequently, the amount of Fe and P discarded as residue increases, and the recovery rate of valuable metals may be low.

[0094] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the oxygen concentration in the furnace during heat treatment in the sintering step may be 5 vol% or less.

[0095] When the above oxygen concentration falls within the aforementioned range, there is an advantage in that the loss of lithium can be prevented and the Boudouard reaction can be activated, thereby increasing the efficiency of direct and indirect reduction reactions. In addition, the amount of graphite burned is small, allowing for the recovery of graphite from waste batteries at a level of 90%. Furthermore, the low CO2 conversion rate of graphite can reduce the amount of CO2 generated from the manufacturing process of the valuable metal recovery composition.

[0096] On the other hand, if the oxygen concentration is below the lower limit of the aforementioned range, there may be a problem in which LiAlO2 is reduced and lithium is lost in the form of Li(g). This results in a disadvantage of a low lithium recovery rate in subsequent processes.

[0097] Furthermore, if the oxygen concentration exceeds the upper limit of the aforementioned range, the reduction reaction is inhibited, and the graphite contained in the spent battery burns, potentially leading to a significant increase in CO2 emissions. In addition, valuable metals such as Li and Fe may react with carbon or oxygen and be lost, resulting in a significantly lower recovery rate of these valuable metal components in subsequent processes. Moreover, the oxygen partial pressure may exceed the equilibrium level between LiFePO4 and the Fe-P liquid metal, making the reduction of LiFePO4 itself difficult.

[0098] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the method of separating the valuable metal recovery alloy in the separation step may be selected from at least one of magnetic separation, particle size separation, and specific gravity separation.

[0099] The method for selecting valuable metal recovery alloys may apply other methods in addition to the aforementioned method, and the present invention is not limited to the above method.

[0100] In a method for manufacturing a valuable metal recovery alloy according to one embodiment of the present invention, the sintered material in the selection step contains a magnetic material and a non-magnetic material, and the content of the magnetic material may be greater than 15 weight% and less than or equal to 25 weight% based on 100% of the total weight of the sintered material.

[0101] Preferably, based on 100% of the total weight of the sintered product, the content of the magnetic material may be 20% by weight or more and 25% by weight or less, or 24% by weight or more and 25% by weight or less.

[0102] In detail, the aforementioned magnetic material may be Fe-P alloy particles, and more specifically, Fe-P alloy particles having one or more phases among FeP, Fe2P, and Fe3P.

[0103] In this specification, the content of the magnetic material means the same as the weight ratio of the magnetic material.

[0104] The content of magnetic material can serve as a measure of the conversion rate of the Fe-P alloy resulting from the dry high-temperature reduction reaction of LFP battery raw materials. Specifically, the theoretical value of the magnetic material content in the valuable metal recovery alloy produced when the LFP battery raw materials are completely reduced is 24 to 25 weight percent. If the actually measured magnetic material content is below the lower limit of the aforementioned range, some LiFePO4 contained in the LFP battery raw materials may remain in the valuable metal recovery alloy without being reduced. In other words, it can be considered that the complete reduction reaction did not proceed. On the other hand, if the actually measured magnetic material content converges to the theoretical value, it can be considered that all LiFePO4 contained in the LFP battery raw materials has been reduced.

[0105]

[0106] The following describes embodiments, comparative examples, and experimental examples of the present invention. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited by the following examples. Furthermore, it is possible to implement the invention with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and such modifications may also fall within the scope of the present invention.

[0107]

[0108] Comparative Example 1

[0109] (Raw material preparation step) 25 kg of lithium iron phosphate (LFP) batteries were cooled at -70 ℃ for 7 hours and then crushed to prepare crushed battery material. At this time, the size of the crushed battery material was set to be 10 to 20 mm based on the long axis among the width, length, and height.

[0110] (Mixing Step) A reducing agent mixed with carbon (C), aluminum (Al), silicon (Si), calcium (Ca), and hydrogen gas (H2) was added to the prepared battery crushed material to form a mixture. At this time, the amount of reducing agent added was such that the molar ratio of the carbon component in the reducing agent was 2 based on the molar amount of LiFePO4 in the battery crushed material, and the remainder of the reducing agent was filled with aluminum (Al), silicon (Si), calcium (Ca), and hydrogen gas (H2). At this time, the molar ratio of each component corresponding to the remainder was less than 0.001 based on the molar amount of LiFePO4 in the battery crushed material. Specifically, the amount of reducing agent added was such that the molar ratio was 1 based on the theoretical amount (mole) of the reducing agent capable of completely reducing the FePO4 contained in the battery crushed material.

[0111] (Calcination step) Next, a mixed gas was injected into the furnace. At this time, the mixed gas was a mixture of oxygen (O2) and nitrogen (N2), and the mixture of hydrogen and oxygen was first saturated inside the furnace. Subsequently, oxygen was injected into the furnace so that the volume fraction of oxygen in the mixed gas was 2 vol%. After a reducing gas atmosphere was established, the temperature inside the furnace (heat treatment temperature) was raised to 1050 ℃, and once the target temperature was reached, the temperature was maintained for 10 minutes (heat treatment time) to produce a valuable metal recovery composition. Subsequently, a negative pressure of -10 kPa was applied to the flue gas facility to discharge the flue gas, and the valuable metal recovery composition (calcined product) was obtained.

[0112] (Selection step) A magnetic field of strength of 0.1 T or more was applied to the above-mentioned valuable metal recovery composition to select a valuable metal recovery alloy containing Fe-P alloy particles.

[0113] Comparative Example 2

[0114] In the above mixing step, a valuable metal recovery alloy was produced using the same process as Comparative Example 1, except that the amount of reducing agent added was changed so that the molar ratio of the carbon component in the reducing agent was 2.2 based on the molar amount of LiFePO4 in the battery crush. The amount of reducing agent added was set so that the molar ratio was 1.1 based on the theoretical amount (mole) of the reducing agent capable of completely reducing the LiFePO4 contained in the battery crush.

[0115] Example 1

[0116] In the above mixing step, a valuable metal recovery alloy was produced using the same process as Comparative Example 1, except that the amount of reducing agent added was changed so that the molar ratio of the carbon component in the reducing agent was 2.4 based on the molar amount of LiFePO4 in the battery crush. The amount of reducing agent added was set so that the molar ratio was 1.2 based on the theoretical amount (mole) of reducing agent capable of completely reducing the LiFePO4 contained in the battery crush.

[0117] Example 2

[0118] In the above mixing step, a valuable metal recovery alloy was produced using the same process as Comparative Example 1, except that the amount of reducing agent added was changed so that the molar ratio of the carbon component in the reducing agent was 3 based on the molar amount of LiFePO4 in the battery crush. The amount of reducing agent added was set so that the molar ratio was 1.5 based on the theoretical amount (mole) of reducing agent capable of completely reducing the LiFePO4 contained in the battery crush.

[0119] Example 3

[0120] In the above mixing step, a valuable metal recovery alloy was produced using the same process as Comparative Example 1, except that the amount of reducing agent added was changed so that the molar ratio of the aluminum component in the reducing agent was 4 based on the molar amount of LiFePO4 in the battery crush. The amount of reducing agent added was set so that the molar ratio was 1.5 based on the theoretical amount (mole) of reducing agent capable of completely reducing the LiFePO4 contained in the battery crush.

[0121] Comparative Example 3

[0122] In the above mixing step, the amount of reducing agent added was changed so that the molar ratio of the carbon component in the reducing agent was 2.5 and the molar ratio of the aluminum component was 1, based on the molar amount of LiFePO4 in the battery crush. In addition, a valuable metal recovery alloy was produced using the same process as Comparative Example 1, except that the heat treatment temperature in the above calcination step was changed to 900 ℃. The amount of reducing agent added was set so that the molar ratio was 1.625 based on the theoretical amount (mole) of reducing agent capable of completely reducing the LiFePO4 contained in the battery crush.

[0123] Example 4

[0124] In the above calcination step, a valuable metal recovery alloy was produced using the same process as Comparative Example 3, except that the heat treatment temperature was changed to 1000 ℃. The amount of reducing agent added was set so that the molar ratio was 1.625 based on the theoretical amount (mole) of reducing agent capable of completely reducing LiFePO4 contained in the battery crushed material.

[0125] Example 5

[0126] In the above calcination step, a valuable metal recovery alloy was produced using the same process as Comparative Example 3, except that the heat treatment temperature was changed to 1050 ℃. The amount of reducing agent added was set so that the molar ratio was 1.625 based on the theoretical amount (mole) of reducing agent capable of completely reducing LiFePO4 contained in the battery crushed material.

[0127] Example 6

[0128] In the above calcination step, a valuable metal recovery alloy was produced using the same process as in Example 5, except that the heat treatment time was changed to 15 minutes. The amount of reducing agent added was set so that the molar ratio was 1.625 based on the theoretical amount (mole) of reducing agent capable of completely reducing LiFePO4 contained in the battery crushed material.

[0129] Example 7

[0130] In the above calcination step, a valuable metal recovery alloy was produced using the same process as in Example 5, except that the heat treatment time was changed to 20 minutes. The amount of reducing agent added was set so that the molar ratio was 1.625 based on the theoretical amount (mole) of reducing agent capable of completely reducing LiFePO4 contained in the battery crushed material.

[0131] Example 8

[0132]

[0133] In the above calcination step, a valuable metal recovery alloy was produced using the same process as in Example 5, except that the heat treatment time was changed to 30 minutes. The amount of reducing agent added was set so that the molar ratio was 1.625 based on the theoretical amount (mole) of reducing agent capable of completely reducing LiFePO4 contained in the battery crushed material.

[0134] Example 9

[0135] In the above calcination step, a valuable metal recovery alloy was produced using the same process as Comparative Example 3, except that the heat treatment temperature was changed to 1100 ℃. The amount of reducing agent added was set so that the molar ratio was 1.625 based on the theoretical amount (mole) of reducing agent capable of completely reducing LiFePO4 contained in the battery crushed material.

[0136] Example 10

[0137] In the above calcination step, a valuable metal recovery alloy was produced using the same process as Comparative Example 3, except that the heat treatment temperature was changed to 1200 ℃. The amount of reducing agent added was set so that the molar ratio was 1.625 based on the theoretical amount (mole) of reducing agent capable of completely reducing LiFePO4 contained in the battery crushed material.

[0138]

[0139] Experimental Example 1 - Evaluation based on the amount of reducing agent added

[0140] In the mixing step of the manufacturing process of the valuable metal recovery alloy of the present invention, the formation of an Fe-P alloy was evaluated according to the amount of reducing agent added.

[0141] Reducing agent input amount (mole) Total reducing agent molar ratio Whether LiFePO4 is observed during XRD analysis Whether Fe-P alloy particles are formed [P] / [Fe] weight ratio Classification: CAlSiCaH2 (hydrogen gas) Comparative Example 1: Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 0.001 Less than 1.5 x 0.15

[0142] Table 1 above shows the amount of reducing agent input, the total molar ratio, and the results regarding the formation of Fe-P alloy during the mixing step of the valuable metal recovery alloy manufacturing process. According to Table 1, it was found that when the total molar ratio of the reducing agent is 1.2 or higher, the LiFePO4 present in the LFP battery raw material can be completely reduced to produce Fe-P alloy particles. On the other hand, when the total molar ratio of the reducing agent is less than 1.2, although Fe-P alloy particles can be produced, the LiFePO4 in the LFP battery raw material cannot be completely reduced, and it was confirmed that LiFePO4 remains in the valuable metal recovery alloy. In other words, it was found that in order to completely reduce the LiFePO4 compound present in the LFP battery raw material and convert it into an Fe-P alloy, the amount of reducing agent input must be at least 1.2 times the theoretical amount of reducing agent required for the reduction reaction. In addition, comparing Examples 2 and 3, it was found that the total molar ratio of the reducing agent is not significantly affected by the type of main component element constituting the reducing agent, and that the ratio of the amount of reducing agent added to the content of the compound (total molar ratio of the reducing agent) is a key requirement for the complete reduction of the LiFePO4 compound. However, it was found that differences in reduction performance may occur depending on the type of reducing agent. In Example 2, the main component of the reducing agent is C, and in Example 3, the main component of the reducing agent is Al; it was found that when the total molar ratio of the reducing agent is the same value, adopting C rather than Al as the main component of the reducing agent is more advantageous for improving the reduction rate of metal oxides in the LFP battery raw material.

[0143]

[0144] Experimental Example 2 - Evaluation based on process conditions of the firing stage

[0145] In the firing step of the valuable metal recovery alloy manufacturing process of the present invention, the formation of an Fe-P alloy was evaluated according to the heat treatment temperature and heat treatment time.

[0146]

[0147] Reducing agent input amount (mole) Total molar ratio of reducing agent Sintering stage Weight ratio of magnetic material (Weight of Fe-P alloy / Total weight of valuable metal recovery alloy, weight%) Average particle size of Fe-P alloy particles (㎛) [P] / [Fe] weight ratio Classification CAl Heat Treatment Temperature (°C) Heat Treatment Time (min) Comparative Example 3 2.5 11.6 25 800 10 15 35 0.036 Example 4 100 0 102 0 125 0.32 Example 5 105 0 102 5 28 8 0.4 Example 6 105 0 15 25 47 9 0.32 Example 7 105 0 20 25 5 6 0.33 Example 8 105 0 30 25 8 9 20.67 Example 9 110 0 102 5 122 0 0.5 Example 101200102521540.48

[0148] Table 2 above shows the heat treatment temperature and heat treatment time of the firing stage of the valuable metal recovery alloy manufacturing process, as well as the amount of Fe-P alloy produced and the average particle size. According to Table 2 above, with the amount of reducing agent input fixed, it is possible to determine whether the LiFePO4 component in the LFP battery raw material was completely reduced to Fe-P alloy and the average particle size of the Fe-P alloy produced by the reduction reaction, depending on the heat treatment temperature and / or heat treatment time.

[0149] In Table 2 above, the weight ratio of the magnetic material can serve as a measure of the conversion rate of the Fe-P alloy resulting from the dry high-temperature reduction reaction of the LFP battery raw material. Specifically, the magnetic material may be an Fe-P alloy in the Fe2P phase. Specifically, the theoretical weight ratio of the magnetic material in the valuable metal recovery alloy produced when the LFP battery raw material is completely reduced is 24 to 25 weight percent. If the actually measured weight ratio of the magnetic material is less than the lower limit of the aforementioned range, some LiFePO4 contained in the LFP battery raw material may remain in the valuable metal recovery alloy without being reduced. In other words, it can be considered that the complete reduction reaction did not proceed. On the other hand, if the actually measured weight ratio of the magnetic material converges to the theoretical value, it can be considered that all LiFePO4 contained in the LFP battery raw material has been reduced.

[0150] In Comparative Example 3 and Example 4, where the heat treatment temperature was 1000 ℃ or lower, the weight ratio of the magnetic material was 15 wt% and 20 wt%, respectively, which is lower than the theoretical value, so LiFePO4 was not completely reduced, and it can be seen that Fe-P alloy and LiFePO4 compound coexist within the valuable metal recovery alloy. On the other hand, in Examples 5 to 10, where the magnetic heat treatment temperature was greater than 1000 ℃, the weight ratio of the magnetic material reached 25 wt%, so it can be seen that LiFePO4 was completely reduced.

[0151] Furthermore, as the heat treatment temperature increases and the heat treatment time lengthens under the same temperature conditions, the average particle size of Fe-P alloy particles in the valuable metal recovery alloy may increase. This is because increasing the heat treatment temperature and / or heat treatment time facilitates the alloying of Cu components contained in the LFP battery raw materials with Fe-P components. In particular, at temperatures above 1048°C, Cu contained in the LFP battery raw materials can completely melt, and since Fe-P alloys containing approximately 5 to 24 weight percent of P can exist in a liquid state, Cu and Fe-P components are prone to fusing with each other.

[0152] However, it is not desirable to unconditionally increase the heat treatment temperature. Depending on the P content in the Fe-P alloy, the temperature range in which Fe-P can exist in a liquid state may vary, and in particular, when the P content is about 33 wt%, the melting point of Fe-P reaches 1370°C. Accordingly, increasing the heat treatment temperature can melt the Fe-P alloy and facilitate alloying with Cu. However, since the vaporization temperature of lithium (Li) is 1300°C, if the heat treatment temperature exceeds 1300°C, lithium vaporizes and is lost. Consequently, the lithium content in the alloy for recovering valuable metals decreases, which is undesirable when considering the recovery rate of valuable metals. In other words, to maximize the content of valuable metals while facilitating the separation and sorting of metals, it is appropriate to control the heat treatment temperature within a predetermined range. Accordingly, the inventors of the present invention confirmed through experiments that when LFP battery raw materials are dry reduction heat-treated at a temperature of 1050 ℃ to 1300 ℃, a valuable metal recovery alloy can be produced in which the valuable metal content is maximized and magnetic separation is also easy.

[0153] Experimental Example 3 - ICP-MS Analysis

[0154] The elemental content of the prepared valuable metal recovery alloy was analyzed using ICP-MS (Inductively Coupled Plasma Spectroscopy). Specifically, the component analysis by ICP-MS was performed on the magnetically separated sample (valuable metal recovery alloy).

[0155] Elemental Content (Weight%) (Elemental Content Excluding Oxygen) Classification LiAlCuFePVCaNdTiSiBCSF Example 10.98 3.67 8.45 49.91 7.20.01 Less than 0.037 0.01 Less than 0.042 0.10.0117.41 0.021 - Comparative Example 10.39 7.11 132.18 16.8<0.010 0.065<0.010 0.227 0.44 0.043 2.32 0.018 -

[0156] Table 3 above shows the results of measuring the content of metal elements using ICP-MS. Table 3 indicates the content of constituent elements excluding oxygen (O), and it can be understood that oxygen occupies the remainder of the valuable metal recovery alloy excluding the elements listed in the table. According to Table 3, in the case of the manufacturing method of the valuable metal recovery alloy of Example 1, it was confirmed that the content of Ti, an impurity in the valuable metal recovery alloy, was low at approximately 0.042%, while the Fe content was high at 49.9%. On the other hand, in the case of Comparative Example 1, the Ti content was 0.227% (maximum Ti content) and the Fe content was 2.18%, indicating that the Ti content was significantly higher and the Fe content was significantly lower compared to the valuable metal recovery alloy of Example 1. This implies that the reduction reaction occurred somewhat inferiorly during the formation of the valuable metal recovery alloy of Comparative Example 1. Specifically, Ti is a material that is not easily reduced and tends to be included in compounds or alloys with low magnetism. In other words, Example 1 contains a large amount of Fe, a magnetic material, resulting in high magnetism and a relatively low Ti content. Conversely, Comparative Example 1 contains a high amount of Ti, an impurity, because the content of Fe, a magnetic material, is significantly low. Therefore, the Ti content can be considered as a measure of the reduction reaction rate during the manufacture of the valuable metal recovery alloy, and it can be understood that the lower the Ti content, the better the reduction reaction with respect to the LFP battery raw material occurs. Furthermore, it can be understood that a valuable metal recovery alloy, which facilitates the selective recovery of valuable metals, has been well formed. If the Ti content is high in the valuable metal recovery alloy obtained by recycling waste batteries, particularly in Fe-P alloys, utilizing the alloy as a raw material in the steel or battery industries may lead to problems such as reduced product quality and increased production costs. For example, in the steel industry, it may degrade the physical properties of steel or cause problems during casting or processing.Ti readily forms carbides (TiC) and nitrides (TiN) within steel, which lowers the ductility and toughness of the steel and can increase the likelihood of product cracking and fracture. As another example, in the battery field, Ti can degrade the conductivity and reactivity of electrode materials, leading to reduced battery capacity and shortened lifespan. Furthermore, it can hinder ion movement, resulting in increased internal resistance and reduced thermal stability. Additionally, removing Ti, which acts as an impurity, from Fe-P alloys may require additional purification processes, which can increase production costs and time. Moreover, even if purification is performed, there is a problem in that chemically stable Ti cannot be easily removed.

[0157]

[0158] Experimental Example 4 - XRD Analysis

[0159] X-ray diffraction (XRD) analysis was performed on the valuable metal recovery alloy produced by the manufacturing method of the present invention.

[0160] Figure 2 shows the XRD analysis results of the valuable metal recovery alloy according to Example 1.

[0161] Figure 3 shows the XRD analysis results of the valuable metal recovery alloy according to Comparative Example 1.

[0162] According to Figure 2 above, it was confirmed that the valuable metal recovery alloy according to the embodiment is composed of graphite and an alloy of Fe2P.

[0163] According to Figure 3 above, it was confirmed that in the valuable metal recovery alloy of Comparative Example 1, in addition to the alloy on carbon and Fe2P, there remained LiFePO4 components that were not reduced. That is, the degree of the reduction reaction can vary depending on the total molar ratio of the reducing agent, and it was confirmed that when the total molar ratio of the reducing agent is 1.2 or higher, the metal oxide components in the LFP battery raw material can be completely reduced.

[0164]

[0165] Experimental Example 5 - Particle Size Analysis of Valuable Metal Recovery Alloys

[0166] The particle size of the valuable metal recovery alloy produced by the manufacturing method of the present invention was analyzed using a laser diffraction particle size analyzer.

[0167] According to the particle size analysis results of a valuable metal recovery alloy according to one embodiment of the present invention, a peak with a particle size Dv50 of 9.88 μm and a peak with a Dv90 of 479 μm were identified in the particle size analysis results. It can be understood that when the magnetic Fe-P alloy is separated during the separation step, the graphite component remaining without separation was analyzed together.

[0168]

[0169] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. Fe-P alloy particles comprising a weight ratio of phosphorus (P) to iron (Fe) [P] / [Fe] of 0.15 or higher, Precious metal recovery alloy.

2. In Paragraph 1, When X-ray diffraction analysis is performed, satisfying Equation 1 below Precious metal recovery alloy: [Equation 1] 0≤I(Fe-PO) / I(Fe-P)≤0.1 (In Equation 1 above, I(Fe-PO) and I(Fe-P) represent the XRD maximum peak intensity of the Fe-PO compound contained in the valuable metal recovery alloy and the XRD maximum peak intensity of the Fe-P alloy particles, respectively.) 3. In Paragraph 1, The average particle size of the above Fe-P alloy particles is 50 to 5000 μm, Precious metal recovery alloy.

4. In Paragraph 1, The above Fe-P alloy particles have an elliptical or spherical shape, and The surface of the above Fe-P alloy particles is in the form of an oxide containing at least one of oxygen (O), aluminum (Al), carbon (C), and lithium (Li) attached thereto. Precious metal recovery alloy.

5. In Paragraph 1, Based on 100% of the total weight of the above valuable metal recovery alloy, the titanium (Ti) content is 1 weight% or less, Precious metal recovery alloy.

6. In Paragraph 1, The above Fe-P alloy particles include those alloyed with copper (Cu), Precious metal recovery alloy.

7. In Paragraph 1, The above Fe-P alloy particles comprise at least one of FeP, Fe2P, and Fe3P, Precious metal recovery alloy.

8. A raw material preparation step of preparing lithium iron phosphate (LFP) battery scrap or lithium iron phosphate (LFP) waste batteries as raw materials; A mixing step of adding a reducing agent to the above raw materials to form a mixture; A firing step of heat-treating the above mixture to form a fired product; and A sorting step for separating the above-mentioned calcined product to select a valuable metal recovery alloy; is included, In the above mixing step, the ratio of reducing agent input to 1.2 based on a LiFePO4 content of 1 mole in the raw material, Method for manufacturing alloys from recovered valuable metals.

9. In Paragraph 8, In the above mixing step, the reducing agent is C, Al, Si, Ca, H2 (hydrogen gas), C x H y One or more selected from (hydrocarbons for 1≤x≤10, 4≤y≤22), Method for manufacturing alloys from recovered valuable metals.

10. In Paragraph 8, In the above screening step, the valuable metal recovery alloy comprises Fe-P alloy particles having a weight ratio of phosphorus (P) to iron (Fe) element, [P] / [Fe], of 0.15 or higher. Method for manufacturing alloys from recovered valuable metals.

11. In Paragraph 8, In the above calcination step, the heat treatment temperature is 800 to 1300 ℃, Method for manufacturing alloys from recovered valuable metals.

12. In Paragraph 8, The time for maintaining the maximum temperature during heat treatment in the above firing step is 10 minutes or more, Method for manufacturing alloys from recovered valuable metals.

13. In Paragraph 8, During the heat treatment in the above calcination step, the oxygen concentration inside the furnace is 5 vol% or less, Method for manufacturing alloys from recovered valuable metals.

14. In Paragraph 8, The method of separating the valuable metal recovery alloy in the above separation step is to select at least one of magnetic separation, particle size separation, and specific gravity separation. Method for manufacturing alloys from recovered valuable metals.

15. In Paragraph 8, In the above screening step, the calcined material contains magnetic and non-magnetic materials, and Based on 100% of the total weight of the above-mentioned sintered product, the content of the magnetic material is greater than 15 weight% and less than 25 weight%, Method for manufacturing alloys from recovered valuable metals.

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