Method for recovering high-purity iron from waste lithium iron phosphate by dry smelting process

Abstract

The present invention relates to a method for recovering high-purity iron from waste lithium iron phosphate. Through a first step of heat-treating a crushed material of waste lithium iron phosphate (LiFePO4, LFP) in an oxygen atmosphere; a second step of recovering FeO-containing slag from a melt produced by adding a flux to and heat-treating, in an oxygen-free atmosphere, the crushed material of the waste lithium iron phosphate that has undergone the first step; a third step of recovering a melt produced by adding a reducing agent to and heat-treating, in an inert atmosphere, the FeO-containing slag recovered in the second step; a fourth step of injecting oxygen gas into the melt recovered in the third step; and a fifth step of adding FeS2 to and heat-treating, in an inert atmosphere, the melt that has undergone the fourth step, high-purity iron metal from which copper and phosphorus have been removed may be recovered.

Description

Method for recovering high-purity iron from waste lithium iron phosphate using a dry refining process

[0001] The present invention relates to a method for recovering high-purity iron from waste lithium iron phosphate (LiFePO4, LFP) using a dry refining process. More specifically, the present invention relates to a method for recovering high-purity iron metal by first separating copper and iron from waste lithium iron phosphate through a dry melting process and then removing any residual copper within the separated iron.

[0002] Lithium secondary batteries are undergoing diverse development. Recently, with carbon regulations being strengthened both domestically and internationally, the development of secondary batteries for electric vehicles has accelerated to address this. This has necessitated the development of new materials with high output and high safety. To meet this demand, highly safe materials such as LiMn2O4 and LiFePO4 have been developed.

[0003] Among these, lithium iron phosphate (LFP) is recognized as one of the most promising cathode materials for lithium-ion batteries due to its advantages, including high power output, low cost, low toxicity, excellent thermal stability, and high reversibility. In particular, its low electrochemical potential makes it a highly safe cathode material. For this reason, lithium iron phosphate batteries have recently been widely used in electric vehicles (EVs) and hybrid electric vehicles (HEVs), particularly electric buses.

[0004] The disposal of lithium secondary batteries for electric vehicles (EVs) that have reached the end of their current life cycles (5-10 years) is entering a period of significant increase. The rapid increase in demand for lithium iron phosphate batteries is expected to pose a significant challenge for the disposal of these batteries. In particular, the toxic LiPF6 and organic electrolytes containing metal ions in LFP batteries can migrate into soil and groundwater, causing environmental pollution when disposed of in landfills. Therefore, post-processing processes, including recycling and reuse, are crucial. Furthermore, securing technology to recycle waste LFP batteries as future resources and convert them into industrial raw materials like iron and copper is crucial for strengthening the competitiveness of related industries. Therefore, recycling waste LFP batteries is expected to contribute significantly not only to environmental protection but also to securing iron and copper supply.

[0005] Conventional recycling methods for spent LFP batteries include hydrometallurgy and direct regeneration. Hydrometallurgy is the primary method for recycling spent batteries. It involves leaching the cathode active material obtained through a pretreatment step, selectively separating the metal from the leach solution, and then refining it. The current hydrometallurgy method for recycling spent LFP batteries requires a complex process: leaching all elements from the cathode active material using inorganic acids such as H2SO4, HCl, and H3PO4, followed by chemical precipitation using NaOH or NH3. Furthermore, the addition of acid to leach the metal into the solution is often excessive and highly concentrated, requiring a significant amount of alkali during the separation process.

[0006] Direct regeneration involves recovering the cathode material from spent batteries, soaking it in an organic solvent, and then reusing it as a raw material for battery cathode materials. One example of a direct regeneration method for spent LFP batteries is to directly separate LFP powder from the cathode and then recover it by heating it at high temperatures or soaking it in an organic solvent. However, the recovered cathode material is prone to containing large amounts of impurities, and its structure is typically destroyed after numerous charge / discharge cycles, resulting in poor electrochemical performance when reused.

[0007] Therefore, to develop an industrially feasible recycling process for waste LFP batteries, it is necessary to increase the efficiency of the process and make it environmentally friendly.

[0008] Meanwhile, the heat treatment process for scrap lithium iron phosphate (LFP) battery waste can cause problems, such as copper and iron mixing, resulting in residual copper within the steel. This residual copper can affect the mechanical properties of recovered iron, such as strength, ductility, and durability, thereby reducing its quality and usability. In particular, industries requiring high-purity iron require additional refining processes to remove residual copper. However, this additional process can lead to increased costs and energy consumption.

[0009] Accordingly, the present invention provides a method for efficiently recovering high-purity iron through a simplified process by including a residual copper removal step using dry melting in the iron recovery process without a separate residual copper removal process.

[0010] One object of the present invention is to provide a method for separating and recovering high-purity iron from waste lithium iron phosphate (LiFePO4, LFP) using a dry refining process, thereby securing a technology for materializing copper and iron used as industrial raw materials, and solving the problem of generating a large amount of waste liquid, which is a problem of the existing method, thereby also solving environmental problems.

[0011] The present invention provides a method for recovering metals from waste lithium iron phosphate. Specifically, the present invention provides a method for recovering high-purity iron from waste lithium iron phosphate. The method may include a first step of heat-treating waste lithium iron phosphate (LiFePO4, LFP) scrap in an oxygen atmosphere; a second step of adding flux to the LFP scrap, which has completed the first step, and heat-treating it in an oxygen-free atmosphere to recover FeO-containing slag from the resulting melt; a third step of adding a reducing agent to the FeO-containing slag recovered in the second step, and heat-treating it in an inert atmosphere to recover the resulting melt; a fourth step of injecting oxygen gas into the melt recovered in the third step; and a fifth step of adding FeS2 to the melt, which has completed the fourth step, and heat-treating it in an inert atmosphere.

[0012] The first step involves heat-treating the waste lithium iron phosphate (LFP) scrap in an oxygen atmosphere to remove carbon present within the LFP. This carbon removal process effectively reduces impurities within the LFP by preventing unnecessary carbon components from interfering with the reaction, thereby enhancing the metal recovery efficiency in subsequent processes. By performing the heat treatment in an oxygen atmosphere, the carbon within the LFP may react with oxygen and be removed in the form of CO2.

[0013] In one embodiment, in the first step, oxygen gas may be injected so that the oxygen equivalent to the carbon content of the waste lithium iron phosphate fragments is 2.1 or more.

[0014] In one embodiment, the oxygen gas can be injected at a rate of 450 to 500 cc per minute.

[0015] In one embodiment, the heat treatment of the first step can be performed at 600 to 800°C.

[0016] The second step involves adding flux to the decarbonized LFP shredded material and heat-treating it to produce a molten product containing FeO-containing slag and a copper-based alloy. During this process, copper (Cu) present in the LFP is separated into the form of a copper-based alloy, and iron (Fe) exists in the form of FeO-containing slag. In a molten state, the copper-based alloy and the FeO-containing slag naturally separate due to differences in specific gravity, enabling the removal of copper and the separation and recovery of the iron-containing slag.

[0017] In one embodiment, the heat treatment of the second step may be performed at about 1200 to 1400°C.

[0018] In one embodiment, in the second step, the flux may comprise SiO2.

[0019] The third step is a step of recovering Fe metal by separating Fe metal and P-containing slag from the FeO-containing slag recovered in the second step. Specifically, by adding a reducing agent and performing heat treatment, FeO is reduced to molten Fe metal, and a slag containing some P can be formed. That is, the molten material recovered in the third step contains Fe metal and P-containing slag. In this process, P is removed as slag, but a small amount of P may remain in the Fe metal. After removing the P-containing slag and recovering the Fe metal, an additional dephosphorization process is required to completely remove the remaining P.

[0020] In one embodiment, the heat treatment of the third step can be performed at about 1400 to 1600°C in an argon atmosphere in a carbon crucible.

[0021] In one embodiment, in the third step, the reducing agent may include CaO.

[0022] The fourth step is a dephosphorization step to remove any P remaining in the Fe metal contained in the molten material recovered in the third step. Flux is added to the Fe metal, which is then melted, and oxygen gas is injected. During this process, P and oxygen react to form phosphate, which is then oxidized to form phosphate oxide. This oxide then combines with the flux and separates into slag. By utilizing the difference in specific gravity between the slag and the metal, the upper P-containing slag can be removed, thereby recovering the dephosphorized Fe metal.

[0023] In one embodiment, the fourth step may include a step of adding a flux to the Fe metal contained in the molten material recovered in the third step and melting it; and a step of injecting oxygen gas into the molten material.

[0024] In one embodiment, in the fourth step, oxygen gas can be injected at 300 to 400 cc per minute for 10 to 30 minutes.

[0025] In one embodiment, the melting may be performed at about 1400 to 1600°C in an alumina crucible.

[0026] The fifth step is a process for recovering high-purity Fe metal by removing the copper (Cu) remaining in the dephosphorized Fe metal after the fourth step is completed. Iron sulfide (FeS2) is added to the dephosphorized Fe metal, melted, and then argon (Ar) gas is injected to remove the residual copper. During this process, the sulfur (S) released when the iron sulfide is thermally decomposed at high temperatures reacts with the copper in the Fe to transform into copper sulfide (Cu2S), which is then separated along with the slag.

[0027] In one embodiment, the fifth step may include a step of adding FeS2, CaO, SiO2, and Al2O3 to the Fe metal included in the melt in the fourth step and melting it; and a step of injecting argon gas into the melt.

[0028] In one embodiment, the argon gas can be injected at 250 to 350 cc per minute for 100 to 130 minutes.

[0029] In one embodiment, the melting may be performed at about 1500 to 1700° C. in a magnesium oxide (MgO) crucible.

[0030] In one embodiment, the waste lithium iron phosphate may be derived from a used cathode active material.

[0031] The dry refining process according to an embodiment of the present invention enables efficient and environmentally friendly separation and recovery of copper and iron from waste lithium iron phosphate. Furthermore, a step for removing residual copper within the separated iron can be included, enabling the recovery of high-purity iron metal.

[0032] Figure 1 is a flow chart showing a method for recovering high-purity iron from waste lithium iron phosphate according to an embodiment of the present invention.

[0033] Figures 2 to 6 show the XRF analysis results and SEM-EDS analysis results of the products according to each step of the method for recovering high-purity iron from waste lithium iron phosphate according to one embodiment of the present invention.

[0034] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The present invention is susceptible to various modifications and variations, and thus specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0035] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, steps, operations, components, parts, or combinations thereof.

[0036] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0037] Figure 1 is a flow chart showing a method for recovering high-purity iron from waste lithium iron phosphate according to an embodiment of the present invention.

[0038] Referring to FIG. 1, a method (100) for recovering high-purity iron from waste lithium iron phosphate according to an embodiment of the present invention may include a first step (S110) of heat-treating waste lithium iron phosphate (LiFePO4, LFP) scrap in an oxygen atmosphere, a second step (S120) of adding flux to the LFP scrap after the first step is completed and heat-treating the same in an oxygen-free atmosphere to recover FeO-containing slag from the resulting melt, a third step (S130) of adding a reducing agent to the FeO-containing slag recovered in the second step and heat-treating the same in an inert atmosphere to recover the resulting melt, a fourth step (S140) of injecting oxygen gas into the melt recovered in the third step, and a fifth step (S150) of adding FeS2 to the melt after the fourth step is completed and heat-treating the same in an inert atmosphere.

[0039] Figure 2 shows the XRF analysis results of waste lithium iron phosphate (LFP) battery shredder.

[0040] Referring to Figure 2, the major elements of the waste LFP battery shredder were confirmed to include copper, iron, phosphorus, aluminum, and trace elements such as nickel, sulfur, cobalt, and chromium. Among these, copper was found to be present at a high content of 42.25 wt%, followed by iron at a high content of 39.52 wt%. The present invention proposes a method for removing phosphorus and copper from waste LFP of this composition and recovering high-purity iron.

[0041] The first step (S110) is a step of removing carbon by heat-treating the waste lithium iron phosphate scrap in an oxygen atmosphere. A large amount of carbon is present in the waste lithium iron phosphate scrap. The present invention can remove the carbon present in the waste lithium iron phosphate scrap through heat treatment in an oxygen atmosphere. As long as the above phenomenon occurs, the process variables of the first step (S110) are not particularly limited. In one embodiment, to form the oxygen atmosphere in the first step (S110), oxygen gas may be injected so that the oxygen equivalent is 2.1 or more relative to the carbon content of the waste lithium iron phosphate scrap. Under these conditions, carbon can be efficiently removed. In one embodiment, the oxygen gas may be injected at about 450 to 500 cc per minute. In one embodiment, the heat treatment in the first step (S110) may be performed at about 600 to 800°C and may be performed for about 1 to 2 hours. The above first step (S110) may be performed by injecting oxygen and then heating it to form an oxygen atmosphere, or by injecting heated oxygen, but the addition of an additional step for temperature elevation is not excluded.

[0042] The second step (S120) is a step of adding flux to the carbon-free waste lithium iron phosphate scrap and heat-treating it to obtain a copper-based alloy and FeO-containing slag. The carbon-free waste lithium iron phosphate scrap contains a large amount of metals including copper and iron. In the present invention, the copper-based alloy and the FeO-containing slag may be separated through a dry melting process of adding flux to the carbon-free waste lithium iron phosphate scrap and heat-treating it.

[0043] In one embodiment, the second step may be performed in a carbon crucible. In addition, the flux used in the second step may include SiO2, but is not particularly limited. In one embodiment, the heat treatment of the second step may be performed at about 1200 to 1400°C and may proceed for about 3 to 10 hours. In one embodiment, the heat treatment of the second step may be performed at an equilibrium oxygen partial pressure of about 10 -11 It can be carried out in the following oxygen-free atmosphere.

[0044] The copper-based alloy obtained in the second step can be recovered by separating it from the FeO-containing slag. This allows copper to be recovered from waste lithium iron phosphate.

[0045] The third step (S130) is a step of adding a reducing agent to FeO-containing slag, heat-treating it in an inert atmosphere to form a molten product, and separating and recovering Fe metal and P-containing slag contained in the molten product. The FeO-containing slag may contain P. In the present invention, Fe metal can be separated and recovered by reducing FeO-containing slag with a reducing agent.

[0046] In one embodiment, the third step may be performed in an argon atmosphere in a carbon crucible. In addition, the reducing agent used in the third step may include CaO, but is not particularly limited. In one embodiment, the heat treatment in the third step may be performed at about 1400 to 1600°C, and may be maintained at 1600°C for 50 minutes in an argon atmosphere of 300 cc / min. P present in the FeO-containing slag reacts with the reducing agent CaO and is removed as slag during Fe reduction. This reaction formula is as follows.

[0047]

[0048] Through the third step described above, slag containing Fe metal and P can be separated, and Fe metal can be recovered. The Fe metal separated and recovered in the third step can undergo the following dephosphorization process to remove P and obtain high-purity Fe metal.

[0049] The fourth step (S140) is a step for dephosphorizing the Fe metal contained in the molten material recovered in the third step. In one embodiment, the fourth step (S140) may include the following steps.

[0050] First, a step (S141) of adding a flux to the Fe metal recovered in the third step and melting it is performed. In one embodiment, the melting in step S141 may be performed at about 1400 to 1600°C in an alumina crucible. In one embodiment, the flux used in step S141 may include a mixture of CaO and SiO2, but is not particularly limited thereto.

[0051] Next, a step (S142) of injecting oxygen gas into the melt of step S141 is performed. By injecting the oxygen gas, P of the Fe metal can be removed and high-purity Fe metal can be recovered. As long as the above phenomenon occurs, the process variables of step S142 are not particularly limited. In one embodiment, in step S142, oxygen gas can be injected at about 300 to 400 cc per minute for about 10 to 30 minutes. The oxygen gas can be injected while maintaining the molten state of the melt, heated oxygen can be injected to maintain the molten state, or the temperature can be heated after injecting oxygen. As a step of removing P remaining in the Fe metal recovered in the third step, the following reaction formula can be performed.

[0052]

[0053]

[0054]

[0055]

[0056] Finally, a fifth step (S150) may be performed to remove residual copper within the Fe metal by heat-treating the Fe metal dephosphorized through the fourth step in an inert atmosphere. In one embodiment, the fifth step (S150) may include the following steps.

[0057] First, a step (S151) of adding FeS2, CaO, SiO2, and Al2O3 to the Fe metal included in the melt in which the fourth step has been completed and melting it is performed. The Fe metal included in the melt in which the fourth step has been completed is a dephosphorized Fe metal. In one embodiment, the melting in the S151 step may be performed at about 1500 to 1700°C in a magnesium oxide (MgO) crucible. The FeS2 (Pyrite) is thermally decomposed at high temperature, and the released sulfur (S) reacts with the remaining copper in the Fe to change into the form of copper sulfide (Cu2S), and the copper sulfide is separated into slag, thereby removing the remaining copper in the iron. This reaction formula is as follows.

[0058]

[0059] Through this, high-purity Fe metal can be recovered from waste lithium iron phosphate.

[0060] Next, a step (S152) of injecting argon gas into the melt of step S151 is performed. Since the argon gas is an inert gas, it can prevent oxidation by blocking contact with the atmosphere containing oxygen. Accordingly, by injecting the argon gas, oxidation of iron and copper in the melt is prevented, thereby creating a stable reaction environment for the melt, and uniform mixing is promoted, thereby recovering high-purity Fe metal from which residual copper has been removed. In one embodiment, in step S152, the argon gas can be injected at 250 to 350 cc per minute for 100 to 130 minutes.

[0061] The process variables described above are exemplary and the scope of the present invention is not limited thereto, but one skilled in the art can select some or all of the process variables described above to achieve certain advantageous effects associated with the present invention.

[0062] In one embodiment, the waste lithium iron phosphate may be derived from a used cathode active material, but this is exemplary and the scope of the present invention is not limited to the source of the waste lithium iron phosphate as described above.

[0063] Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments described below are merely some embodiments of the present invention, and the scope of the present invention is not limited to the embodiments described below.

[0064] Example

[0065] In this example, discharged LFP batteries were shredded and used. XRD (X-ray diffraction) and carbon / silicate sulfide (C / S) analyses were performed on the shredded waste products of the used LFP batteries. The analysis results confirmed that LFP in the shredded waste LFP batteries existed in the form of LiFePO4 and had a high carbon content. Therefore, carbon removal from the shredded waste LFP batteries was first performed.

[0066] 1) Carbon removal from waste LFP fragments

[0067] Experiments were conducted using 100 g of waste LFP shredder under three conditions of parallel oxygen equivalence (oxygen equivalent relative to carbon content). 100 g of waste LFP shredder was introduced into an atmosphere box furnace, and oxygen gas was injected according to the parallel oxygen equivalence. The experiment was conducted at 800°C for 2 hours. The oxygen injection conditions were set as shown in Table 1 below.

[0068]

[0069] As a result of the experiment, when the oxygen equivalent to the carbon content was 2.1 or higher, the carbon content of the waste LFP shredding product after the experiment was completed was 0.190 wt.%, confirming that this was the optimal condition for carbon removal.

[0070] Meanwhile, Fig. 2 shows the XRF analysis results of the waste LFP shredder product from which carbon has been removed. Referring to Fig. 2, it can be confirmed that it contains high contents of copper and iron, with Cu at 42.25 wt.% and Fe at 39.52 wt.%.

[0071] 2) Heat treatment of carbon removal waste LFP shredding products

[0072] 52g of carbon-free waste LFP shredder was mixed with 11.05g of SiO2 and placed in a crucible, and the equilibrium oxygen partial pressure was 10 -11 , and maintained at 1200~1400℃ for 3~10 hours. As a result, 29.49g of copper-based alloy and 32.79g of FeO-containing slag were obtained. Figure 3 shows the XRF analysis results of the produced copper-based alloy and FeO-containing slag. Referring to Figure 3, the content of Cu in the copper-based alloy was 67.8wt.%, and it was confirmed through the following calculation formula that more than 91% of copper was recovered. The content of Fe in the FeO-containing slag was 53.9wt.%.

[0073]

[0074] 3) Fe reduction from FeO-containing slag

[0075] 33.761 g of FeO-containing molten slag and 16.239 g of CaO were mixed and placed in a carbon crucible and maintained at 1400 to 1600°C for 30 to 120 minutes. As a result, it was confirmed that distinct separation of Fe metal and slag occurred. Figure 4 shows the results of SEM-EDS analysis of Fe metal and slag separated from FeO-containing slag. Referring to Figure 4, the Fe content in the Fe metal was 80 wt.% or more, and it was confirmed that P existed as an impurity in the metal. The Fe content in the slag was 0.83 wt.%, confirming that most of the Fe was reduced to metal. In order to increase the purity of the Fe metal, a dephosphorization process was performed to remove P.

[0076] 4) Oxygen blowing process for removing P from Fe metal

[0077] The recovered Fe metal was mixed with CaO and SiO2 and placed in an alumina crucible, and oxygen gas was blown into the molten metal at a flow rate of 300 cc / min for 10 to 30 minutes at 1400 to 1600°C. The SEM-EDS analysis results of the dephosphorized Fe metal and slag are shown in Fig. 5. Referring to Fig. 5, the purity of the Fe metal was 85% or higher, and the weight was 19.62 g, indicating that more than 80% of the Fe was recovered from the spent LFP battery.

[0078] 5) Pyrite addition to remove Cu from reduced Fe metal

[0079] In order to remove the residual Cu in the dephosphorized Fe metal, 1.917 g of Pyrite (FeS2), 0.726 g of CaO, 0.363 g of SiO2, and 0.363 g of Al2O3 were placed in a MgO crucible and maintained at 1600°C under Ar 300 cc / min for 120 min. As a result, ICP-OES analysis was performed to measure the purity of the produced Fe metal, and the results are shown in Fig. 6. Referring to Fig. 6, the purity of the Fe metal was over 90%, and the weight was 19.036 g, indicating that over 85% of Fe was recovered from the spent LFP battery.

[0080] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. The first step is to heat treat the waste lithium iron phosphate (LiFePO4, LFP) fragments in an oxygen atmosphere; A second step of adding flux to the crushed LFP of which the first step has been completed and heat treating it in an oxygen-free atmosphere to recover FeO-containing slag from the resulting molten material; A third step of adding a reducing agent to the FeO-containing slag recovered in the second step and heat-treating it in an inert atmosphere to recover the generated molten product; A fourth step of injecting oxygen gas into the molten material recovered in the third step; and A fifth step comprising adding FeS2 to the melt in which the fourth step is completed and heat treating it in an inert atmosphere; A method for recovering high-purity iron from waste lithium iron phosphate.

2. In paragraph 1, In the above first step, oxygen gas is injected so that the oxygen equivalent to the carbon content of the waste lithium iron phosphate fragments is 2.1 or more. A method for recovering high-purity iron from waste lithium iron phosphate.

3. In paragraph 2, The above oxygen gas is injected at 450 to 500 cc per minute. A method for recovering high-purity iron from waste lithium iron phosphate.

4. In paragraph 1, By the above first step, carbon is removed from the LFP, A method for recovering high-purity iron from waste lithium iron phosphate.

5. In paragraph 1, In the second step above, The above flux contains SiO2, A method for recovering high-purity iron from waste lithium iron phosphate.

6. In paragraph 1, In the second step above, The above melt comprises a molten copper-based alloy and FeO-containing slag. A method for recovering high-purity iron from waste lithium iron phosphate.

7. In paragraph 1, The heat treatment in the third step is performed at about 1400 to 1600°C in an argon atmosphere in a carbon crucible. A method for recovering high-purity iron from waste lithium iron phosphate.

8. In paragraph 1, In the third step above, The reducing agent comprises CaO, A method for recovering high-purity iron from waste lithium iron phosphate.

9. In paragraph 1, In the third step above, The above melt contains molten Fe metal and P-containing slag, A method for recovering high-purity iron from waste lithium iron phosphate.

10. In paragraph 1, The fourth step above is, A step of adding flux to the Fe metal contained in the melt recovered in the third step and melting it; and a step of injecting oxygen gas into the molten material; A method for recovering high-purity iron from waste lithium iron phosphate.

11. In paragraph 10, The above melting is performed at about 1400 to 1600°C in an alumina crucible. A method for recovering high-purity iron from waste lithium iron phosphate.

12. In paragraph 10, By the above 4th step, the P remaining in the Fe metal is dephosphorized. A method for recovering high-purity iron from waste lithium iron phosphate.

13. In paragraph 1, The fifth step above is, A step of melting by adding FeS2, CaO, SiO2 and Al2O3 to the Fe metal contained in the melt in which the fourth step is completed; and a step of injecting argon gas into the molten material; A method for recovering high-purity iron from waste lithium iron phosphate.

14. In paragraph 13, The above melting is performed at about 1500 to 1700°C in a magnesium oxide (MgO) crucible. A method for recovering high-purity iron from waste lithium iron phosphate.

15. In paragraph 13, By the above fifth step, the copper remaining in the Fe metal is removed. A method for recovering high-purity iron from waste lithium iron phosphate.

16. In paragraph 1, The above-mentioned waste lithium iron phosphate is derived from the cathode active material after use. A method for recovering high-purity iron from waste lithium iron phosphate.

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