Method for selective recovery of lithium for recycling waste secondary battery materials

Abstract

The present invention provides a valuable metal recovery method with reduced side reactions such as the high-temperature oxidation of metals in waste battery-derived black mass or waste positive electrode materials, the method comprising the steps of: mixing a sulfur compound and a first material including valuable metals to generate a second material; heat-treating the second material to generate a third material including a valuable metal-sulfur compound; adding a first dissolving agent to the third material to separate the third material into a fourth material and a solution containing the ionized valuable metal-sulfur compound; and adding a second dissolving agent to the fourth material to separate the fourth material into a fifth material and a solution containing the ionized valuable metal component.

Description

A selective recovery method for lithium for recycling waste secondary battery materials

[0001] The present invention relates to a method for recovering valuable metals.

[0002] One of the methods for recovering valuable metals such as nickel, cobalt, and lithium from medium and large-sized waste lithium secondary batteries is to process waste battery materials in the form of mixed powder of positive and negative electrode materials through a series of recycling processes such as discharging, crushing and pulverizing classification, and heat treatment. Waste battery materials include positive electrode materials (e.g., LiCoO2, LiMnO2, Li(Ni)) used in battery manufacturing. x Co y Al z )O2, etc.) and anode materials (e.g., graphite), and some crushed and pulverized materials of current collectors (e.g., aluminum, copper) may be mixed in and included during the processing. In addition, waste cathode materials may be generated due to process defects during the manufacturing process of battery and cathode materials. Unlike waste battery materials, waste cathode materials do not contain pulverized materials of anode materials and current collectors, and may contain about 6% to about 8% of lithium.

[0003] To extract valuable metals from mineral raw materials, hydrometallurgical techniques, including leaching and solvent extraction, can be used to selectively separate and purify the target metals. Typically, the cathode materials from waste batteries or cathode materials are composed of oxides. In particular, when leaching cathode oxide materials, the mixed cathode materials and some organic binders can act as inhibitors during acid dissolution. Furthermore, lithium contained in waste batteries or cathode materials can cause environmental problems, such as ecotoxicity, if discharged into wastewater. Therefore, ongoing research is being conducted on recycling technologies for the selective recovery of lithium.

[0004] Among the representative technologies for selective lithium recovery is the dry lithium recovery method using reduction heat treatment. This method typically involves heat treatment at high temperatures (approximately 700°C to 1,000°C) in which black mass or spent cathode materials from spent batteries are introduced together with a reducing agent to induce a reduction reaction. However, this process can cause surface melting due to heat, and the products produced by the reduction reaction can clump together. Furthermore, side reactions, such as high-temperature oxidation of aluminum, can also occur, necessitating a method to mitigate these issues.

[0005] The present invention aims to solve various problems, including the aforementioned ones, by providing a method for recovering valuable metals with reduced side reactions, such as high-temperature oxidation of metals in black mass or waste cathode materials derived from spent batteries. However, these tasks are exemplary and the scope of the present invention is not limited thereto.

[0006] According to one aspect of the present invention, a method for recovering a valuable metal is provided, comprising: mixing a first material containing a valuable metal and a sulfur compound to produce a second material; heat-treating the second material to produce a third material containing the valuable metal sulfur compound; mixing a first dissolving agent into the third material to separate the third material into a solution containing the ionized valuable metal sulfur compound and a fourth material; and mixing a second dissolving agent into the fourth material to separate the fourth material into a solution containing the ionized valuable metal component and a fifth material.

[0007] In one example, the sulfur compound includes a transition metal, the third material further includes a magnetized transition metal component, and the method for recovering valuable metals may further include a step of separating the magnetized transition metal component from the third material using magnetism.

[0008] In one example, the first material may include black mass or waste cathode material generated from a waste battery.

[0009] According to one example, the step of producing the second material may include a step of mixing the first material and the sulfur compound in a mass ratio of 1:0.1 to 1:0.3.

[0010] According to one example, the step of producing the second material may include the step of crushing the sulfur compound into powder; and the step of mixing the first material and the powdered sulfur compound.

[0011] In one example, the step of producing the third material may include heat treating the second material at about 350° C. to about 600° C.

[0012] According to one example, the step of producing the third material may include a step of heat-treating the second material in a nitrogen atmosphere at a temperature increasing rate of about 1°C / min to about 10°C / min at atmospheric pressure.

[0013] In one example, the first solvent may include water, and the second solvent may include at least one of an inorganic acid and an organic acid.

[0014] In one example, the second solvent may comprise at least one of about 1 wt% to about 50 wt% of the inorganic acid and about 1 wt% to about 80 wt% of the organic acid.

[0015] According to one example, the step of mixing the first solvent into the third material may include a step of mixing the third material and the first solvent in a weight ratio of 1:1 to 1:9.

[0016] According to one example, the step of mixing the first dissolving agent into the third material may be performed at a reaction time of about 30 minutes to about 240 minutes and a reaction temperature of about 5°C to about 40°C.

[0017] According to one example, the step of mixing the second solvent into the fourth material may include a step of mixing the fourth material and the second solvent in a weight ratio of 1:1 to 1:10.

[0018] According to one example, the step of mixing the second dissolving agent into the fourth material may be performed at a reaction time of about 30 minutes to about 240 minutes and a reaction temperature of about 5°C to about 90°C.

[0019] In one example, the precious metal may be at least one selected from the group consisting of cobalt (Co), nickel (Ni), manganese (Mn), and lithium (Li).

[0020] In one example, the step of heat-treating the second material may include the step of cooling and capturing a gas containing organic matter pyrolyzed from the second material.

[0021] In one example, the metal sulfur compound may include Li2SO4.

[0022] According to one embodiment of the present invention, as described above, a method for recovering valuable metals can be implemented with reduced side reactions, such as high-temperature oxidation of metals within black mass or waste cathode materials derived from spent batteries. Of course, the scope of the present invention is not limited by these effects.

[0023] FIG. 1 is a flowchart schematically illustrating a method for recovering valuable metals according to one embodiment of the present invention.

[0024] Figure 2 is a flowchart schematically illustrating a mixing step of a method for recovering valuable metals according to one embodiment of the present invention.

[0025] Figure 3 is a flowchart schematically illustrating a low-temperature heat treatment step of a method for recovering valuable metals according to one embodiment of the present invention.

[0026] Figures 4 to 7 are tables showing the material compositions of samples of each step of a method for recovering valuable metals according to one embodiment of the present invention.

[0027] Figure 8 is a graph showing the lithium recovery rate through acid washing after washing at different heat treatment temperatures.

[0028] Figure 9 is a graph showing the lithium recovery rate according to the heat treatment method.

[0029] FIG. 10 is a graph showing XRD (X-ray diffraction) data for samples at each step of a method for recovering valuable metals according to one embodiment of the present invention.

[0030] Figure 11 shows an image of a powder (Fe2O3) containing a magnetized component and an image of a heat-treated material at different heat treatment temperatures.

[0031] The present invention is capable of various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. The effects and features of the present invention, as well as the methods for achieving them, will become clearer with reference to the embodiments described in detail below, along with the drawings. However, the present invention is not limited to the embodiments disclosed below and can be implemented in various forms.

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. When describing with reference to the drawings, identical or corresponding components are given the same reference numerals and redundant descriptions thereof will be omitted.

[0033] In the following examples, the terms first, second, etc. are not used in a limiting sense, but are used for the purpose of distinguishing one component from another.

[0034] In the examples below, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0035] In the following examples, terms such as “include” or “have” mean that a feature or component described in the specification is present, and do not preclude the possibility that one or more other features or components may be added.

[0036] In the following examples, when a part such as a film, region, component, etc. is said to be on or above another part, it includes not only the case where it is directly on top of the other part, but also the case where another film, region, component, etc. is interposed in between.

[0037] For convenience of explanation, the sizes of components in the drawings may be exaggerated or reduced. For example, the sizes and thicknesses of each component shown in the drawings are arbitrarily indicated for convenience of explanation, and thus the present invention is not necessarily limited to what is shown.

[0038] In some embodiments, where implementations are otherwise feasible, specific process sequences may be performed in a different order than described. For example, two processes described in succession may be performed substantially simultaneously, or in a reverse order from the described order.

[0039] In this specification, “A and / or B” refers to the case where it is A, or B, or both A and B. And, “at least one of A and B” refers to the case where it is A, or B, or both A and B.

[0040] FIG. 1 is a flowchart schematically illustrating a method for recovering valuable metals according to one embodiment of the present invention. FIG. 2 is a flowchart schematically illustrating a mixing step of a method for recovering valuable metals according to one embodiment of the present invention, and FIG. 3 is a flowchart schematically illustrating a low-temperature heat treatment step of a method for recovering valuable metals according to one embodiment of the present invention.

[0041] Referring to FIG. 1, the method for recovering valuable metals may include a mixing step (S10), a low-temperature heat treatment step (S20), a magnetic separation step (S30), a water washing and solid-liquid separation step (S40), and an acid washing and solid-liquid separation step (S50).

[0042] First, a mixing step (S10) may be performed. The mixing step (S10) may be a step of mixing a first material containing a valuable metal and a sulfur compound to produce a second material (or mixture).

[0043] In one embodiment, the valuable metal may be at least one selected from the group consisting of cobalt (Co), nickel (Ni), manganese (Mn), and lithium (Li).

[0044] In one embodiment, the first material may be a composite oxide containing lithium, nickel, cobalt, manganese, etc., such as black mass or waste cathode material derived from a spent battery. For example, the first material may contain nickel, cobalt, manganese, etc. in the form of oxides depending on the composition of the black mass or waste cathode material generated from a spent battery, and may include lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (LiNiCoMnO2), lithium manganese oxide (LiMnO2), etc. The first material may be lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (LiNiCoMnO2), lithium manganese oxide (LiMnO2), etc., alone or in combination.

[0045] Meanwhile, black mass derived from waste batteries may be processed into raw materials through a recycling process from waste lithium secondary batteries. Black mass derived from waste batteries may contain about 3% to about 4% lithium. Black mass derived from waste batteries is a mixture of pulverized aluminum and copper from current collectors and graphite used as a negative electrode material, and may contain some organic binders or electrolytes depending on the manufacturing process. Waste cathode materials may be generated during the synthesis process of secondary battery cathode materials. Waste cathode materials may contain about 6% to about 8% lithium.

[0046] In one embodiment, the sulfur compound may comprise a transition metal. For example, sulfur compounds include scandium (Sc), yttrium (Y), lutetium (Lu), lawrencium (Lr), titanium (Ti), zirconium (Zr), hafnium (Hf), rutherfordium (Rf), vanadium (V), niobium (Nb), tantalum (Ta), dubnium (Db), chromium (Cr), molybdenum (Mo), tungsten (W), seaborgium (Sg), manganese (Mn), technetium (Tc), rhenium (Re), bohrium (Bh), iron (Fe), ruthenium (Ru), osmium (Os), hassium (Hs), cobalt (Co), rhodium (Rh), iridium (Ir), meitnerium (Mt), nickel (Ni), palladium (Pd), platinum (Pt), darmstadtium (Ds), copper (Cu), silver (Ag), gold (Au), It may include at least one selected from the group consisting of roentgenium (Rg), zinc (Zn), cadmium (Cd), mercury (Hg), and copernicium (Cn).

[0047] In one embodiment, the mixing step (S10) may include mixing the first material and the sulfur compound in a mass ratio of 1:0.1 to 1:0.3. In other words, the mixing mass ratio of the first material and the sulfur compound may be 1:0.1 to 1:0.3.

[0048] In one embodiment, as illustrated in FIG. 2, the mixing step (S10) may include a step (S11) of pulverizing a sulfur compound into powder and a step (S12) of mixing the first material with the powdered sulfur compound. When the powdered sulfur compound is mixed with the first material, the reaction area between the first material and the sulfur compound may increase, and the efficiency of producing a valuable metal sulfur compound through a subsequent low-temperature heat treatment step (S20) may increase.

[0049] After the mixing step (S10), a low-temperature heat treatment step (S20) may be performed. The low-temperature heat treatment step (S20) may be a step of heat-treating a second material in which a first material and a sulfur compound are mixed to produce a third material including a valuable metal sulfur compound and / or a magnetized transition metal component. By performing the heat treatment on the second material, bonds with oxygen in a (valuable) metal oxide (e.g., lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (LiNiCoMnO2), lithium manganese oxide (LiMnO2), etc.) may be broken, and a (valuable) metal sulfur compound may be produced.

[0050] For example, when a sulfur compound is mixed with a first material and heat-treated, the reaction formula for producing a valuable metal sulfur compound is as follows. In the reaction formula below, the first material includes LiMeO2 (wherein, Me = Ni, Co, Mn), and the valuable metal sulfur compound includes a lithium sulfur compound (Li2SO4).

[0051] [Reaction Scheme 1] Fe2(SO4)3→ Fe2O3+ 3SO3(or SO2+ 1 / 2O2)

[0052] [Reaction Formula 2] 2LiMeO + 1 / 2O2+ SO3→ Li2SO4+ 2MeO

[0053] [Reaction Scheme 3] MeO + SO3→ MeSO4

[0054] Referring to the reaction formula, when a sulfur compound containing a transition metal is added to the first material, when the SO3 gas generated by thermal decomposition of the sulfur compound reacts with the anode oxide, compounds such as Li2SO4, MeO, and MeSO4 can be generated.

[0055] Meanwhile, as illustrated in the aforementioned Figure 2, when a powdered sulfur compound is mixed with the first material, the reaction area of ​​the first material and the sulfur compound can increase, and the conversion efficiency into a valuable metal sulfur compound through the subsequent low-temperature heat treatment step (S20) can increase.

[0056] In one embodiment, the low-temperature heat treatment step (S20) may include a step of heat treating the second material at about 350°C to about 600°C. For example, the low-temperature heat treatment step (S20) may be performed at about 400°C to about 500°C.

[0057] For example, in the case of a heat treatment process using a carbon-based auxiliary material (or reducing agent) rather than a sulfur compound, a chemical reaction to carbonize lithium is generally required at a high temperature of about 700℃ to about 1000℃ or higher. In this case, the heat treatment process is carried out at a relatively high temperature, so that surface melting of the heat treatment result may occur after the heat treatment. If surface melting occurs, an additional crushing process is required before the subsequent water washing and acid washing steps. In addition, aluminum (Al), a current collector component remaining in the black mass derived from spent batteries, undergoes an oxidation reaction at high temperatures and may begin thermal decomposition at about 530℃ or higher, generating aluminum oxide.

[0058] However, when a heat treatment process utilizing a sulfur compound is performed, as in one embodiment of the present invention, a substitution reaction can occur even at a relatively low temperature of about 500°C or less. When the substitution reaction is performed in a low temperature range of about 500°C or less, there is no surface melting phenomenon of the heat treatment result after the heat treatment, so that lithium can be recovered by performing the water washing step and the acid washing step directly without having to change it into a fine powder through a pulverization process. Therefore, the process of recovering lithium from black mass derived from spent batteries or waste cathode materials can be simplified. In addition, by performing the heat treatment process in a low temperature range of about 500°C or less, an oxidation reaction of aluminum (Al), which is a current collector component remaining in the black mass derived from spent batteries, does not occur, so that the efficiency of recovering valuable metals in a subsequent wet refining process can be improved.

[0059] Typically, in order to manufacture a positive or negative electrode plate for a lithium-ion battery, electrode active material, organic binder, and conductive material are mixed and coated on a current collector. During the recycling of waste batteries, the electrode active material and the binder, which served as a support structure, do not undergo a chemical reaction, which can hinder the recovery of lithium and valuable metals in the black mass or waste positive electrode material derived from waste batteries. To remove such hindrances, the binder composed of organic substances is removed by washing with an organic detergent or at a temperature of about 400°C to about 600°C. In one embodiment of the present invention, when a heat treatment process utilizing a sulfur compound is performed, the heat treatment process is performed at a relatively low temperature of about 500°C or less, so the organic binder can be removed without an additional heat treatment step at a separate high temperature for removing organic substances.

[0060] That is, when a heat treatment process utilizing a sulfur compound is performed as in one embodiment of the present invention, lithium can be recovered in a wet process through a heat treatment process at a relatively low temperature of about 500°C or less, and at the same time, an organic matter removal process can be omitted without a separate additional heat treatment step at a high temperature for organic matter removal, thereby reducing energy costs through efficient operation.

[0061] In one embodiment, as illustrated in FIG. 3, the low-temperature heat treatment step (S20) may include a step of cooling and capturing a gas containing pyrolyzed organic matter (S21) and a step of combusting and neutralizing the gas (S22). As described above, when low-temperature heat treatment is performed at a relatively low temperature of about 500°C or less on black mass or waste cathode material derived from spent batteries, organic matter such as binders may volatilize through pyrolysis, thereby generating a gas containing organic matter. By capturing the gas containing pyrolyzed organic matter and capturing it in a liquid form through a cooling section, carbon emissions can be reduced and environmental loads can be minimized.

[0062] That is, when a heat treatment process utilizing a sulfur compound is performed as in one embodiment of the present invention, the recovery rate of valuable metals through selective separation and recovery of lithium is increased, and organic impurities are recovered separately, thereby enabling an environmentally friendly and efficient waste battery recycling process to be operated.

[0063] In the low-temperature heat treatment step (S20), the mixing mass ratio of the first material and the sulfur compound, the heat treatment temperature, and the heat treatment time can be important factors affecting the recovery efficiency of valuable metals.

[0064] In one embodiment, the low-temperature heat treatment step (S20) is performed at normal pressure (e.g., atmospheric pressure), and may be performed at about 350°C to about 600°C in a nitrogen atmosphere by heating at a heating rate of about 1°C / min to about 10°C / min, and the reaction with the sulfur compound may be promoted generally in the range of about 400°C to about 500°C.

[0065] In one embodiment, the low-temperature heat treatment step (S20) may be performed for a time period of between about 1 hour and about 3 hours, depending on the characteristics of the process and equipment.

[0066] In one embodiment, the reactor for performing the low-temperature heat treatment step (S20) may be a batch or continuous reactor. For example, the reactor may be a rotary continuous heat treatment reactor. In this case, the reactivity between the first material and the sulfur compound can be increased and the reaction time can be reduced, thereby improving the conversion rate into a valuable metal sulfur compound. Furthermore, productivity in terms of input and output can also be increased.

[0067] After the low-temperature heat treatment step (S20), a magnetic separation step (S30) may be performed. The magnetic separation step (S30) may be a step of separating a magnetized transition metal component from a third material using magnetism.

[0068] As described above, the second material heat-treated in the low-temperature heat treatment step (S20) can produce a valuable metal sulfur compound (e.g., lithium sulfur compound) through the reaction formula described above. In addition, the sulfur compound including a transition metal (e.g., Fe) can produce a powder including a magnetized transition metal (e.g., Fe) component after a thermal decomposition reaction. That is, the second material can be heat-treated to produce a third material including a valuable metal sulfur compound and / or a magnetized transition metal component.

[0069] In the magnetic separation step (S30), powder containing magnetized transition metal components generated by the thermal decomposition reaction of sulfur compounds containing transition metals and black mass or waste cathode materials derived from spent batteries can be separated through a physical separation process utilizing magnetism. By physically separating the magnetized transition metal components, the purity of the spent battery materials can be increased, and the separated powder can be recycled. Furthermore, since the magnetized transition metal components are physically separated first, the use of hydrogen peroxide and nickel hydroxide in the iron precipitation step of the subsequent hydrometallurgical process can be reduced.

[0070] After the magnetic separation step (S30), a water washing and solid-liquid separation step (S40) may be performed. The water washing and solid-liquid separation step (S40) may be a step of mixing a first dissolving agent with a third material from which at least a portion of the magnetized transition metal component has been removed, thereby separating the third material into a solution containing an ionized valuable metal sulfur compound and a fourth material.

[0071] In one embodiment, the first solvent may include water. When the first solvent is added to the third material and mixed / stirred, the valuable metal sulfur compound (e.g., Li2SO4) produced by the substitution reaction in the low-temperature heat treatment step (S20) may be dissolved in the first solvent. The dissolution rate may be proportional to the amount of the valuable metal sulfur compound produced in the low-temperature heat treatment step (S20).

[0072] A solution containing ionized valuable metal sulfur compounds (e.g., a liquid phase in which lithium is dissolved) and a fourth substance (e.g., a powder remaining as an undissolved component) can be separated using a solid-liquid separation device. That is, the solid-liquid separation device can be used to separate the filter residue after water washing and the solution containing ionized valuable metal sulfur compounds (e.g., Li2SO4). Lithium can be dissolved and separated through the water washing and solid-liquid separation step (S40). Meanwhile, the solid-liquid separation device can include a sedimentation type, a pressure filtration type, a vacuum filtration type, a centrifugal dehydration type, etc.

[0073] The solubility of lithium sulfate (Li2SO4) generated through a substitution reaction in the low-temperature heat treatment step (S20) at room temperature is approximately 25.7 g / 100 ml, which is approximately 20 times higher than the solubility of lithium carbonate (1.26 g / 100 ml, 25 °C), a product of the reduction heat treatment reaction using a carbon-based reducing agent. Therefore, compared to heat treatment technologies using carbon-based reducing agents, a high recovery rate can be achieved even with a small water ratio at room temperature.

[0074] In one embodiment, the mixing weight ratio of the third material and the first dissolving agent may be from 1:1 to 1:9.

[0075] Generally, the recovery rate of lithium after the water washing step may increase as the mixing weight ratio increases. However, if the mixing weight ratio is high, such as 1:10 or more, the lithium concentration in the liquid phase may decrease, which may exceed the amount of water required for lithium leaching from the to-be-heated powder. In this case, a lot of energy may be consumed in the process of concentrating the recovered lithium aqueous solution. In addition, if the mixing weight ratio is low, such as 1:1 or less, the transport and filtration of the slurry may be difficult. Therefore, it may be desirable to carry out the reaction in the mixing weight ratio range of 1:3 to 1:5.

[0076] In one embodiment, the reactor for performing the water washing and solid-liquid separation step (S40) may be a batch type or a continuous type.

[0077] In one embodiment, the step of mixing the first dissolving agent into the third material may be performed for a reaction time of about 30 minutes to about 240 minutes. For example, the step of mixing the first dissolving agent into the third material may be performed for a reaction time of about 60 minutes to about 120 minutes.

[0078] In one embodiment, the step of mixing the first dissolving agent into the third material may be performed at a reaction temperature of about 5°C to about 40°C. The reaction temperature may be preferably set depending on the characteristics of the produced lithium compound and the target and purpose of recovery.

[0079] Meanwhile, the recovery rate of the heat-treated product that has undergone a heat treatment process in the range of about 700°C to about 1000°C using a carbon-based reducing agent in the water washing step and a lithium carbonation reaction is about 40% to about 60%, and the recovery rate of lithium that has undergone a heat treatment process in the range of about 350°C to about 600°C using a sulfur-based compound containing a transition metal, which is an example of the present invention, is about 40% to about 50%, and can have the same level of results as the carbon-based reduction reaction.

[0080] After the water washing and solid-liquid separation step (S40), the acid washing and solid-liquid separation step (S50) may be performed. The acid washing and solid-liquid separation step (S50) may be a step in which a second dissolving agent is mixed with the fourth material to separate the fourth material into a solution containing ionized valuable metal components and a fifth material. That is, the purpose is to recover the lithium remaining in the cathode material by adding a portion of the second dissolving agent to the undissolved residue filtered through the water washing and solid-liquid separation step (S40) and mixing / stirring it.

[0081] In one embodiment, the second dissolving agent may include at least one of an inorganic acid such as sulfuric acid, hydrochloric acid, nitric acid, and the like, and an organic acid such as oxalic acid, citric acid, and malic acid. The concentration of the acid may vary depending on the type of acid and the metal content and lithium content of the filter residue after water washing, but the acid washing step may be performed by introducing the inorganic acid in the range of about 1 wt% to about 50 wt%, and the organic acid in the range of about 1 wt% to about 80 wt%. More preferably, the inorganic acid may be introduced singly or in multiple amounts in the range of about 3 wt% to about 20 wt%, and the organic acid may be introduced in the range of about 10 wt% to about 40 wt%.

[0082] In one embodiment, the mixing weight ratio of the fourth material (e.g., filter residue after water washing) and the second dissolving agent may be 1:1 to 1:10.

[0083] While the proportion of dissolved agent added may be proportional to the lithium recovery rate, valuable metals such as nickel and cobalt may also be dissolved during this process. Furthermore, increasing the dissolved amount of metals other than lithium may require an increased alkaline source for pH adjustment and precipitation in the subsequent precipitation step to recover valuable metals. Therefore, selecting an appropriate concentration is necessary based on the metal content in the filter residue after water washing.

[0084] In one embodiment, the step of mixing the second solvent into the fourth material may be performed for a reaction time of about 30 minutes to about 240 minutes. For example, the step of mixing the second solvent into the fourth material may be performed for about 60 minutes to about 120 minutes.

[0085] In one embodiment, the step of mixing the second dissolving agent into the fourth material may be performed at a reaction temperature of about 5°C to about 90°C. However, considering the metal dissolution rate, it may also be performed at a temperature in the range of about 5°C to about 50°C.

[0086] The fifth material (e.g., the powder remaining as an undissolved component in the acid washing step) and the solution containing ionized valuable metal components (e.g., a liquid phase in which lithium and some metals are dissolved) can be separated using a solid-liquid separation device. That is, the solid-liquid separation device can be used to separate the waste battery material with reduced lithium and the solution containing Li, Ni, Co, and Mn. Lithium can be dissolved and separated through the acid washing and solid-liquid separation step (S50). The process can be simplified by maximizing the recovery rate of lithium in the acid washing step after the heat treatment step, thereby recovering lithium without an additional recovery process using water.

[0087] Meanwhile, when a heat treatment process using a carbon-based auxiliary material is generally performed, the lithium generated in the heat treatment step reacts with the solvent, generating a large amount of carbon dioxide gas, which may cause the water level in the reactor to rise by about two times. However, according to one embodiment of the present invention, by applying a heat treatment process utilizing a sulfur compound containing a transition metal, the metal mixture solid phase including ionized Li2SO4 and MeSO4 after water washing reacts with the solvent, so that no separate carbon dioxide gas is generated, and the phenomenon of the water level rising in the reactor due to this is reduced, thereby ensuring safety during process operation.

[0088] In addition, by introducing sulfate containing a transition metal in the low-temperature heat treatment step (S20), the inflow of Na ions that may be added during the auxiliary material introduction process is eliminated, thereby reducing the generation of Na2SO4 (sodium sulfate, sulphate), thereby reducing environmental problems resulting from the valuable metal recovery process.

[0089] Figures 4 to 7 are tables showing the material compositions of samples of each step of a method for recovering valuable metals according to one embodiment of the present invention.

[0090] Figure 4 is a table showing the results of confirming the composition of black mass or waste cathode material derived from spent batteries using high-frequency inductively coupled plasma (ICP-OES) analysis equipment.

[0091] Referring to Fig. 4, it can be confirmed that the black mass sample derived from a spent battery is composed of Ni 9.26 wt%, Co 6.68 wt%, Mn 6.88 wt%, Cu 11,494 ppm, Fe 148 ppm, Al 29,264 ppm, Li 30,519 ppm, Na 3,628 ppm, and S 1,545 ppm.

[0092] Figure 5 is a table showing the results of confirming the composition of waste battery materials after low-temperature heat treatment using ICP-OES analysis equipment.

[0093] 200 parts by weight of waste battery materials were mixed with a sulfur compound containing a transition metal and placed in a batch-type heat treatment furnace. At this time, the sulfur compound was placed in an amount of 20 to 60 parts by weight and mixed with black mass or waste cathode materials derived from waste batteries. The temperature was increased to 500°C at a rate of about 1°C / min to about 10°C / min and maintained for 2 hours to perform a low-temperature heat treatment step. At this time, nitrogen was introduced as an atmospheric gas at a rate of 20 L / min to 40 L / min to create a heat treatment atmosphere. As a result of the low-temperature heat treatment, 207 parts by weight of a heat-treated material was obtained. Referring to Fig. 5, it can be confirmed that the waste battery material sample after low-temperature heat treatment is composed of Ni 8.99 wt%, Co 6.34 wt%, Mn 6.63 wt%, Cu 14,061 ppm, Fe 60,374 ppm, Al 26,739 ppm, Li 29,105 ppm, Na 3,623 ppm, and S 44,240 ppm.

[0094] Figure 6 is a table showing the results of confirming the composition of a sample of the product obtained after the water washing and solid-liquid separation processes using ICP-OES analysis equipment.

[0095] After low-temperature heat treatment, 207 parts by weight of the to-be-heated material and 620 parts by weight of DIW (Deionized Water) were added, and mixing and stirring were performed for 1 hour at room temperature. At this time, the to-be-heated material that had undergone the low-temperature heat treatment step did not have a surface melting phenomenon, so the wet grinding step for changing it into a fine powder was omitted. After the water-washing reaction, the slurry was separated into liquid and solid phases using a solid-liquid separator, and 580 parts by weight of the filtrate after water washing and 172 parts by weight of the residue after water washing were obtained. Referring to Figure 6, it can be confirmed that the filtrate after water washing is composed of 0.04 wt% of Ni, 0.06 wt% of Co, 0.17 wt% of Mn, 34 ppm of Cu, 0 ppm of Fe, 106 ppm of Al, 6,077 ppm of Li, 129 ppm of Na, and 13,197 ppm of S. It can be confirmed that the water-washed residue is composed of Ni 10.57 wt%, Co 7.40 wt%, Mn 7.24 wt%, Cu 16,973 ppm, Fe 75,173 ppm, Al 30,488 ppm, Li 14,901 ppm, Na 2,578 ppm, and S 8,736 ppm. It can be confirmed that the lithium on the object to be heated was dissolved in water during the water-washing step. In addition, the pH measured in the sample of the filtrate after water-washing was 5.73, confirming that it was a weakly acidic solution. This confirmed that some nickel, cobalt, and manganese were dissolved in water during water-washing due to the phosphoric acid groups contained in the organic substances remaining in the black mass derived from spent batteries.

[0096] Figure 7 is a table showing the results of confirming the composition of a sample after the acid washing and solid-liquid separation process using ICP-OES analysis equipment.

[0097] After washing with water, 10 wt% sulfuric acid was added at a ratio of 1:3 to 227 wt% of the residue, and the acid washing step was performed by mixing and stirring for 1 hour under room temperature conditions. After the reaction, the slurry was separated into the acid-washed filtrate and the acid-washed residue using a solid-liquid separator, and 132 wt% of the acid-washed residue and 674 wt% of the filtrate were obtained. Washing was performed to recover the residual acid and valuable metals on the surface of the acid-washed residue, and 626 wt% of the washing solution was obtained during this process. Referring to Figure 7, it can be confirmed that the acid-washed filtrate is composed of 0.90 wt% of Ni, 0.63 wt% of Co, 0.64 wt% of Mn, 2,351 ppm of Cu, 1,114 ppm of Fe, 2,420 ppm of Al, 2,965 ppm of Li, 49 ppm of Na, and 26,224 ppm of S. After acid washing, it can be confirmed that the washing solution is composed of Ni 0.12 wt%, Co 0.08 wt%, Mn 0.08 wt%, Cu 265 ppm, Fe 133 ppm, Al 382 ppm, Li 278 ppm, Na 8 ppm, and S 3,172 ppm. It can be confirmed that the acid washing residue is composed of Ni 8.61 wt%, Co 6.04 wt%, Mn 5.89 wt%, Cu 8,272 ppm, Fe 87,043 ppm, Al 25,674 ppm, Li 2,471 ppm, Na 1,793 ppm, and S 2,013 ppm. It can be confirmed that the lithium contained in the water washing residue is additionally recovered through the acid washing step.

[0098] Figure 8 is a graph showing the lithium recovery rate through acid washing after washing at different heat treatment temperatures.

[0099] Figure 8 is a graph produced through tests at 350°C to 600°C using the aforementioned processes to derive the optimal point for the selective separation of lithium through the introduction of a sulfur compound containing a transition metal. It can be seen that the optimal lithium separation efficiency is achieved around 400°C to 500°C. This is a significantly lower temperature compared to the heat treatment technology in the range of 700°C to 1000°C using a carbon-based reducing agent, and it is possible to perform a low-temperature heat treatment process for the substitution reaction of lithium ions at a low temperature similar to the temperature at which the binder contained in general waste secondary battery materials is removed, while simultaneously capturing and removing organic substances such as binders. Therefore, carbon emissions can be reduced, environmental impact can be minimized, and energy costs can be lowered by efficiently operating the recycling process step.

[0100] Figure 9 is a graph showing the lithium recovery rate according to the heat treatment method.

[0101] FIG. 9 is a comparison of lithium separation efficiency for black mass that was heat-treated in the range of 500°C to 600°C without any additional material input for the purpose of removing electrolyte and binder after crushing of spent batteries, in comparison with the case of utilizing a low-temperature heat treatment process using a mixture of a sulfur compound containing a transition metal and water washing and acid washing according to the present invention. Specifically, the lithium separation efficiency (or lithium recovery rate) after the water washing and acid washing steps was compared and analyzed for black mass that underwent a low-temperature heat treatment process by inputting a sulfur compound containing a transition metal and black mass that was heat-treated alone without any additional material input.

[0102] In terms of lithium separation efficiency, when the low-temperature heat treatment process of mixing a sulfur compound including a transition metal according to the present invention is applied, the efficiency of lithium separated from the black mass is 95%, which is a significantly higher efficiency compared to the result of 59% obtained using the existing heat treatment technology. Therefore, it can be confirmed that the present invention can increase the lithium separation efficiency not only through the organic substance removal effect in the temperature range for removing organic substances such as binders included in waste secondary battery materials, but also through the substitution reaction of lithium ions of the positive electrode material in the black mass and the sulfur compound including the transition metal.

[0103] FIG. 10 is a graph showing XRD (X-ray diffraction) data for samples at each step of a method for recovering valuable metals according to one embodiment of the present invention.

[0104] Figure 10 shows the structural changes that occur during the heat treatment step, water washing step, and acid washing step of black mass or waste cathode material derived from spent batteries in a low-temperature range due to the introduction of a sulfur compound containing a transition metal, as measured by XRD analysis equipment.

[0105] Referring to Fig. 10, the black mass may include Li2O, NiO, CoO, Li2MnO3, and LiNiO2. After the low-temperature heat treatment step, the product may include Li2SO4, Li2CO3, Fe2O3, NiO, Co, and MnNi. It can be seen that lithium oxide in the black mass is replaced after the low-temperature heat treatment step to generate a lithium sulfur compound. After the water-washing step, the residue may include LiNiO2, Ni, and Fe. Looking at the decrease in peak intensity of Li2SO4 compared to the product after the low-temperature heat treatment step, it can be confirmed that Li2SO4 is dissolved and lithium on the product is washed with water. That is, it can be seen that Li2SO4 is dissolved in water in the water-washing step, so that lithium is selectively recovered. After the acid-washing step, the residue may include Li2O. The decrease in peak intensity of LiNiO2 compared to the residue after the water-washing step indicates that LiNiO2 was dissolved into Li and Ni by acid washing. In other words, it can be seen that lithium contained in the water-washing residue was additionally recovered through the acid-washing step.

[0106] Figure 11 shows an image of a powder (Fe2O3) containing a magnetized component and an image of a heat-treated material at different heat treatment temperatures.

[0107] Figure 11 shows a magnetic material containing magnetized iron components selected using a magnetic separator under a magnetic strength controlled to 500 gauss for each of the low-temperature heat treatment steps at 350°C to 600°C. It can be seen that the Fe component (e.g., Fe2O3) is not separated from the heat treatment material after the low-temperature heat treatment step at 350°C, but the Fe component is separated from the heat treatment material after each of the low-temperature heat treatment steps at 400°C to 600°C.

[0108] Also, this is a graph produced through tests at 350℃ to 600℃ using the aforementioned processes to select / remove powder containing magnetized Fe components. In the temperature range higher than 500℃, in the case of the heat-treated product, in the process of reducing the metal oxides contained in the waste battery material to the form of pure metal, magnetic metals such as nickel are magnetically selected together with iron, and the content of nickel, cobalt, etc. tends to increase. Therefore, in the magnetic selection step, it may be desirable to perform a low-temperature heat treatment process at the range of 400℃ to 500℃ in terms of separating powder containing Fe components and valuable metals such as nickel and cobalt.

[0109] While the present invention has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will appreciate that various modifications and equivalent alternative embodiments are possible. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

Claims

1. A step of producing a second material by mixing a first material containing valuable metals and a sulfur compound; A step of heat-treating the second material to produce a third material containing a valuable metal sulfur compound; A step of mixing a first solvent into the third material to separate the third material into a solution containing the ionized metal sulfur compound and a fourth material; and A method for recovering precious metals, comprising a step of mixing a second dissolving agent into the fourth material and separating the fourth material into a solution containing the ionized precious metal component and a fifth material.

2. In paragraph 1, The above sulfur compound contains a transition metal, The third material further comprises the magnetized transition metal component, The above method for recovering valuable metals is as follows: A method for recovering precious metals, further comprising a step of separating the magnetized transition metal component from the third material using magnetism.

3. In paragraph 1, A method for recovering valuable metals, wherein the first material comprises black mass or waste cathode material generated from a waste battery.

4. In paragraph 1, A method for recovering valuable metals, wherein the step of producing the second material comprises a step of mixing the first material and the sulfur compound in a mass ratio of 1:0.1 to 1:0.

3.

5. In paragraph 1, The step of producing the second material is: A step of crushing and powdering the above sulfur compound; and A method for recovering valuable metals, comprising the step of mixing the first material and the powdered sulfur compound.

6. In paragraph 1, A method for recovering valuable metals, wherein the step of producing the third material comprises a step of heat-treating the second material at about 350°C to about 600°C.

7. In paragraph 1, A method for recovering valuable metals, wherein the step of producing the third material comprises a step of heat-treating the second material in a nitrogen atmosphere at a temperature increasing rate of about 1°C / min to about 10°C / min at atmospheric pressure.

8. In paragraph 1, The first solvent comprises water, A method for recovering valuable metals, wherein the second solvent comprises at least one of an inorganic acid and an organic acid.

9. In paragraph 8, A method for recovering valuable metals, wherein the second solvent comprises at least one of about 1 wt% to about 50 wt% of the inorganic acid and about 1 wt% to about 80 wt% of the organic acid.

10. In paragraph 1, A method for recovering valuable metals, wherein the step of mixing the first dissolving agent into the third material comprises a step of mixing the third material and the first dissolving agent in a weight ratio of 1:1 to 1:

9.

11. In paragraph 1, A method for recovering valuable metals, wherein the step of mixing the first dissolving agent into the third material is performed at a reaction time of about 30 minutes to about 240 minutes and a reaction temperature of about 5°C to about 40°C.

12. In paragraph 1, A method for recovering valuable metals, wherein the step of mixing the second dissolving agent into the fourth material comprises a step of mixing the fourth material and the second dissolving agent in a weight ratio of 1:1 to 1:

10.

13. In paragraph 1, A method for recovering valuable metals, wherein the step of mixing the second dissolving agent into the fourth material is performed at a reaction time of about 30 minutes to about 240 minutes and a reaction temperature of about 5°C to about 90°C.

14. In paragraph 1, A method for recovering a precious metal, wherein the precious metal is at least one selected from the group consisting of cobalt (Co), nickel (Ni), manganese (Mn), and lithium (Li).

15. In paragraph 1, A method for recovering valuable metals, wherein the step of heat-treating the second material includes a step of cooling and capturing a gas containing organic matter thermally decomposed from the second material.

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