Lithium-containing aqueous sulfuric acid solution and method for its production

Abstract

This invention relates to lithium-containing sulfuric acid aqueous solutions and methods for preparing the same. The method for preparing the sulfuric acid aqueous solution comprises: obtaining a valuable metal recycling composition from waste batteries, comprising a valuable metal alloy, a lithium compound, copper (Cu), and graphite; separating graphite from the valuable metal recycling composition; leaching the valuable metal, lithium compound, and copper (Cu) in the valuable metal recycling composition with sulfuric acid; recovering the valuable metal and copper (Cu) from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation; and removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recovery step.

Description

Technical Field

[0001] This invention relates to raw materials for battery manufacturing, and more particularly to a lithium-containing sulfuric acid aqueous solution obtained from waste batteries and a method for preparing the same. Background Technology

[0002] With the increasing global demand for electric vehicles, the disposal of waste batteries generated by these vehicles has become a social problem. Lithium-ion batteries, which are the main raw material for these waste batteries, contain organic solvents, explosive substances, and heavy metals such as Ni, Co, Mn, and Fe. However, Ni, Co, Mn, and Li are valuable metals with significant scarcity value, making the recycling and reuse of waste lithium-ion batteries an important research area.

[0003] Specifically, a lithium secondary battery mainly consists of copper and aluminum as current collectors, Li, Ni, Co, and Mn-containing oxides constituting the positive electrode material, and graphite as the negative electrode material. It also includes a separator for separating the positive and negative electrode materials and an electrolyte injected into the separator. The solvents and salts used to constitute the electrolyte are primarily a mixture of carbonate organic compounds such as ethylene carbonate, propylene carbonate, and, for example, LiPF6.

[0004] The development of waste battery recycling processes, which involve crushing the waste batteries into intermediate materials such as waste battery fragments or black powder, and then recovering valuable metals through subsequent processes, is in full swing.

[0005] The recovered valuable metals will undergo a process of acid leaching to recover valuable metals such as Li, Ni, Co, and Mn from the battery. This acid leaching process involves using an acid such as sulfuric acid to convert the valuable metals in the battery into an ionic state and remove impurities. The remaining valuable metals such as Ni, Co, or Mn in the sulfuric acid after impurity removal are extracted as sulfides through solvent extraction and crystallization.

[0006] After sulfuric acid leaching, the Li content in the sulfuric acid reaches approximately 6 to 10 g / L. However, after extraction and crystallization with solvents such as Ni, Co, and Mn, the residual Li in the sulfuric acid is diluted to approximately 1 to 2 g / L. To prepare battery-grade raw materials (specifically lithium) using a low-concentration lithium-containing sulfuric acid aqueous solution, multiple impurity removal and lithium concentration steps are required. The purity of Li₂CO₃ or LiOH used in battery preparation should be above 99.5%. Obtaining this purity requires high extraction costs and also presents the problem of reduced Li recovery rate. Therefore, methods to address these issues need to be researched.

[0007] Furthermore, as a method for obtaining lithium, one approach involves heat-treating lithium from lithium-containing ores, such as lithium-containing spodumene, at a temperature above approximately 900°C, followed by leaching with sulfuric acid to remove impurities. However, this method generates a large amount of precipitate during impurity removal, and the environmental remediation costs for burying this precipitate are excessively high.

[0008] Furthermore, in lithium-containing materials, when lithium oxide (Li2O) or fluoride (LiF) present in the cathode material is exposed to high temperatures, the vaporization of Li(g) or LiF(g) leads to lithium loss, resulting in a decrease in lithium recovery rate. Summary of the Invention

[0009] Technical problems to be solved One technical problem to be solved by the present invention is to provide a lithium-containing sulfuric acid aqueous solution, which can be used as a raw material for the preparation of lithium secondary batteries and contains a high concentration of lithium.

[0010] Another technical problem to be solved by the present invention is to provide a method for preparing a lithium-containing sulfuric acid aqueous solution, wherein the sulfuric acid aqueous solution can be used as a raw material for the preparation of lithium secondary batteries and contains a high concentration of lithium.

[0011] Technical solution According to one embodiment of the present invention, a lithium-containing sulfuric acid aqueous solution is recovered from waste batteries, containing lithium (Li), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn) and the balance impurities, and can satisfy the following formula 1.

[0012] <Formula 1> 1.0 ≤ [Al] = 0.0297 × [Li] 2 +1.3205×[Li]±5≤16.0 In Equation 1 above, [Li] and [Al] represent the concentrations (g / L) of Li and Al in a lithium-containing sulfuric acid aqueous solution, respectively.

[0013] In one embodiment, an aqueous solution of sulfuric acid can satisfy Equation 2.

[0014] <Formula 2> 0.05 ≤ [Ni] = 0.1907 × [Li] 2 -0.2689×[Li]±3≤16.0 In Equation 2 above, [Li] and [Ni] represent the concentrations (g / L) of Li and Ni in a lithium-containing sulfuric acid aqueous solution, respectively.

[0015] In one embodiment, an aqueous sulfuric acid solution can satisfy Equation 3.

[0016] <Formula 3> 0.05 ≤ [Co] = 0.0624 × [Li] 2 -0.1078×[Li]±2≤14.0 In Equation 3 above, [Li] and [Co] represent the concentrations (g / L) of Li and Co in lithium-containing sulfuric acid aqueous solution, respectively.

[0017] In one embodiment, an aqueous sulfuric acid solution can satisfy Equation 4 below.

[0018] <Formula 4> 0.1 ≤ [Mn] = 0.0402 × [Li] 2 +0.117×[Li]±1≤12.0 In Equation 4 above, [Li] and [Mn] represent the concentrations (g / L) of Li and Mn in lithium-containing sulfuric acid aqueous solution, respectively.

[0019] A method for preparing a lithium-containing sulfuric acid aqueous solution according to another embodiment of the present invention comprises: obtaining a valuable metal recycling composition comprising a valuable metal alloy, a lithium compound, copper (Cu), and graphite from a waste battery; separating graphite from the valuable metal recycling composition; leaching the valuable metal, lithium compound, and copper (Cu) in the valuable metal recycling composition with sulfuric acid; recovering the valuable metal and the copper (Cu) from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation; and removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recovery step.

[0020] In one embodiment, at least a portion of the lithium compound may be configured on a valuable metal alloy. In one embodiment, the step of obtaining a composition for valuable metal recycling may include: preparing a lithium (Li)-containing battery; crushing the battery; and heat-treating the crushed battery fragments in the range of 600 to 1500°C.

[0021] In one embodiment, the step of heat-treating the crushed battery fragments in the range of 600 to 1500°C may be carried out in the range of oxygen concentration in the range of 0.1 to 2.0 vol%. In one embodiment, the step of separating graphite from the valuable metal recovery composition may be carried out using at least one of particle size separation, gravity separation, and flotation.

[0022] In one embodiment, the step of leaching the valuable metals, lithium compounds, and copper (Cu) in the valuable metal recovery composition with sulfuric acid may involve controlling the pH of the lithium-containing sulfuric acid aqueous solution within the range of 0.2 to 4.0. In another embodiment, the step of leaching the valuable metals, lithium compounds, and copper (Cu) in the valuable metal recovery composition with sulfuric acid may involve using an equivalent ratio of sulfuric acid of 0.5 to 4.0.

[0023] In one embodiment, the sulfuric acid leaching step of the valuable metal, lithium compound, and copper (Cu) in the valuable metal recovery composition can be carried out in a temperature range of 10 to 150°C. In another embodiment, the sulfuric acid leaching step of the valuable metal, lithium compound, and copper (Cu) in the valuable metal recovery composition can be carried out by introducing an inert gas at a flux of 0.1 to 20.0 Nm. 3 Supply is made at a rate of / hr.

[0024] In one embodiment, the step of leaching the valuable metal, lithium compound, and copper (Cu) in the valuable metal recovery composition with sulfuric acid may include the step of adding sodium hydroxide (NaOH) to remove impurities from the lithium-containing sulfuric acid aqueous solution between the step of leaching the valuable metal, lithium compound, and copper (Cu) in the valuable metal recovery composition and the step of recovering the valuable metal and copper (Cu) from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation.

[0025] In one embodiment, the step of removing impurities from the sulfuric acid aqueous solution may involve controlling the pH of the sulfuric acid aqueous solution to between 3.0 and 8.0. In one embodiment, the step of recovering the valuable metal and the copper (Cu) from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation may include a step of removing impurities using an ion exchange method between the step of removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recovery step.

[0026] In one embodiment, the step of removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recycling step may be adjusting the pH of the lithium-containing sulfuric acid aqueous solution to a range of 8.5 to 12.0. In one embodiment, the step of preparing the lithium (Li)-containing battery may include a step of freezing the battery.

[0027] Beneficial effects According to one embodiment of the present invention, a lithium-containing sulfuric acid aqueous solution contains a predetermined proportion of valuable metals, and can therefore be used as a raw material for the preparation of lithium secondary batteries, providing a sulfuric acid aqueous solution containing a high concentration of lithium.

[0028] According to another embodiment of the present invention, a method for preparing a lithium-containing sulfuric acid aqueous solution provides a method for leaching lithium-containing compounds recovered from lithium-containing batteries with sulfuric acid under temperature and pH conditions to remove impurities, thereby preparing a high-purity lithium-containing raw material for the preparation of lithium-containing batteries. Attached Figure Description

[0029] Figure 1 This is a graph showing the change of battery voltage with cooling temperature according to an embodiment of the present invention.

[0030] Figure 2 This is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to an embodiment of the present invention.

[0031] Figure 3a and Figure 3b This is a photograph of a fire that occurred when the object broke after freezing, according to a comparative example of the present invention, where the freezing time was shorter than the minimum cooling time. Figure 3c and Figure 3d The photograph shows that no fire occurred when the item was frozen and then broken according to an embodiment of the present invention, and the freezing time was longer than the minimum cooling time.

[0032] Figure 4 This is a schematic diagram illustrating the preparation of a high-purity lithium-containing sulfuric acid aqueous solution according to an embodiment of the present invention. Detailed Implementation

[0033] The terms "first," "second," "third," etc., are used to describe parts, components, regions, layers, and / or segments, but these parts, components, regions, layers, and / or segments should not be limited by these terms. These terms are only used to distinguish one part, component, region, layer, or segment from another. Therefore, without departing from the scope of the invention, the first part, component, region, layer, or segment described below can also be described as a second part, component, region, layer, or segment.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. Unless the context clearly indicates otherwise, the singular forms used herein are intended to include the plural forms as well. The word "comprising" as used in the specification can specifically refer to a feature, domain, integer, step, action, element, and / or component, but does not exclude the presence or addition of other features, domains, integers, steps, actions, elements, and / or components.

[0035] If one part is described as being on top of another part, then other parts may exist directly on top of or in between the other part. If one part is described as being directly on top of another part, then no other parts exist in between.

[0036] Furthermore, % in this specification represents weight percentage, unless otherwise stated.

[0037] Although not otherwise defined, all terms used herein (including technical and 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 dictionaries should be interpreted as having the same meaning as disclosed in relevant technical literature and herein, and should not be interpreted in an idealized or overly formal sense.

[0038] According to one embodiment of the present invention, a lithium-containing sulfuric acid aqueous solution, having a high concentration of lithium, can be used as a raw material for preparing lithium hydroxide for use in preparing positive electrode active materials. Specifically, the lithium-containing sulfuric acid aqueous solution can be recycled from waste batteries.

[0039] In one embodiment, the lithium-containing sulfuric acid aqueous solution may contain lithium (Li), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), and the balance impurities. The balance impurities may include, for example, at least one selected from Ni, Co, Mn, Cu, Ti, Zn, Pb, P, Ca, Mg, B, K, Na, Si, Zr, and Fe.

[0040] In one embodiment, an aqueous solution of lithium-containing sulfuric acid can satisfy Equation 1.

[0041] <Formula 1> 1.0 ≤ [Al] = 0.0297 × [Li] 2 +1.3205×[Li]±5≤16.0 In Equation 1 above, [Li] and [Al] represent the concentrations (g / L) of Li and Al in a lithium-containing sulfuric acid aqueous solution, respectively.

[0042] Equation 1 above can be a relationship between the concentrations of Li and Al in a lithium-containing sulfuric acid aqueous solution. Specifically, Equation 1 can satisfy values ​​from 1.0 to 16.0, and more specifically, from 2.5 to 12.0. When Equation 1 is satisfied, it can be effectively applied to the preparation of LiOH for high-nickel cathode active materials, and due to the high lithium concentration, it has the advantage of reducing material costs.

[0043] If Equation 1 exceeds the upper limit of the aforementioned range, lithium leaching will be delayed, resulting in a decrease in lithium recovery rate. If Equation 1 exceeds the lower limit of the aforementioned range, lithium co-precipitation and loss will occur when hydroxide is precipitated after leaching to remove aluminum.

[0044] In one embodiment, an aqueous solution of lithium-containing sulfuric acid can satisfy Equation 2.

[0045] <Formula 2> 0.05 ≤ [Ni] = 0.1907 × [Li] 2 -0.2689×[Li]±3≤16.0 In Equation 2 above, [Li] and [Ni] represent the concentrations (g / L) of Li and Ni in a lithium-containing sulfuric acid aqueous solution, respectively.

[0046] Equation 2 above can be a relationship between the concentrations (g / L) of Li and Ni in the sulfuric acid aqueous solution. Specifically, Equation 2 can satisfy 0.05 to 16.0, and more specifically, 0.3 to 7.5. When Equation 2 is satisfied, it can be effectively applied to the preparation of LiOH for the preparation of high-nickel cathode active materials, and due to the high lithium concentration, it has the advantage of reducing material costs.

[0047] If Equation 2 exceeds the upper limit of the aforementioned range, lithium leaching will be delayed, resulting in a decrease in lithium recovery rate. If Equation 2 exceeds the lower limit of the aforementioned range, lithium co-precipitation and loss will occur during the generation of hydroxides to remove nickel.

[0048] In one embodiment, an aqueous solution of lithium-containing sulfuric acid can satisfy the following equation 3.

[0049] <Formula 3> 0.05 ≤ [Co] = 0.0624 × [Li] 2 -0.1078×[Li]±2≤14.0 In Equation 3 above, [Li] and [Co] represent the concentrations (g / L) of Li and Co in lithium-containing sulfuric acid aqueous solution, respectively.

[0050] Equation 3 above can be a relationship between the concentrations (g / L) of Li and Co in a lithium-containing sulfuric acid aqueous solution. Specifically, Equation 3 satisfies 0.05 to 14.0, and more specifically, it can satisfy 0.15 to 6.0. When Equation 3 is satisfied, it can be effectively applied to the preparation of LiOH for the preparation of high-nickel cathode active materials, and due to the high lithium concentration, it has the advantage of reducing material costs.

[0051] If Equation 3 exceeds the upper limit of the aforementioned range, lithium leaching will be delayed, resulting in a decrease in lithium recovery rate. If Equation 3 exceeds the lower limit of the aforementioned range, lithium co-precipitation and loss will occur during the generation of hydroxides to remove cobalt.

[0052] In one embodiment, an aqueous solution of lithium-containing sulfuric acid can satisfy Equation 4.

[0053] <Formula 4> 0.1 ≤ [Mn] = 0.0402 × [Li] 2 +0.117×[Li]±1≤12.0 In Equation 4 above, [Li] and [Mn] represent the concentrations (g / L) of Li and Mn in lithium-containing sulfuric acid aqueous solution, respectively.

[0054] Equation 4 above can be a relationship between the concentrations (g / L) of Li and Mn in the sulfuric acid aqueous solution. Specifically, Equation 4 satisfies 0.1 to 12.0, and more specifically, it can satisfy 0.5 to 6.0. When Equation 4 is satisfied, it can be effectively applied to the preparation of LiOH for the preparation of high-nickel cathode active materials, and due to the high lithium concentration, it has the advantage of reducing material costs.

[0055] If Equation 4 exceeds the upper limit of the aforementioned range, lithium leaching will be delayed, resulting in a decrease in lithium recovery rate. If Equation 4 exceeds the lower limit of the aforementioned range, lithium co-precipitation and loss will occur during the generation of hydroxides to remove manganese.

[0056] As mentioned above, the lithium content in the lithium-containing sulfuric acid aqueous solution meets the aforementioned range, thus facilitating the attempt to increase the battery capacity. It can be effectively applied to the preparation of positive electrode active material precursors for lithium secondary batteries with excellent structural stability.

[0057] A method for preparing a lithium-containing sulfuric acid aqueous solution according to another embodiment of the present invention may include: a step of obtaining a valuable metal recycling composition comprising a valuable metal alloy, a lithium compound, copper (Cu), and graphite from a waste battery; a step of separating graphite from the valuable metal recycling composition; a step of leaching the valuable metal, lithium compound, and copper (Cu) in the valuable metal recycling composition with sulfuric acid; a step of recovering the valuable metal and the copper (Cu) from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation; and a step of removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recovery step.

[0058] The steps of obtaining a valuable metal recycling composition containing valuable metal alloys, lithium compounds, copper (Cu) and graphite from waste batteries may include: preparing a lithium (Li) battery; crushing the battery; and heat-treating the crushed battery fragments in the range of 600 to 1500°C.

[0059] The steps for preparing lithium (Li) batteries may include batteries that have reached the end of their lifespan, scrap materials that constitute the waste batteries, positive electrode materials such as jelly rolls and slurries, defective products generated during the manufacturing process, residues from the manufacturing process, and waste batteries such as scrap materials generated during the manufacturing process of lithium-ion batteries.

[0060] In one embodiment, the process of preparing a lithium (Li) battery may include freezing the battery. Specifically, as the battery is subjected to a specific pressure, the separator is physically broken, resulting in a high current and sparks that cause a short circuit. These sparks can ignite the electrolyte, potentially leading to a fire.

[0061] The step of freezing the battery involves freezing the battery to suppress the ignition of the liquid electrolyte contained within the battery, followed by a crushing process, thus preventing problems caused by electrolyte ignition.

[0062] In one embodiment, the step of freezing the battery can be carried out by cooling it to a range of -150°C to -60°C. If the upper limit of the temperature range is exceeded, the residual voltage inside the battery drops to 0V, which may cause a short circuit and battery reaction, and the electrolyte cannot be completely frozen, making this unsuitable.

[0063] If the lower limit of the temperature range is exceeded, the electrolyte will be fully frozen, and the internal voltage of the battery will drop to 0V. Therefore, even if a short circuit occurs with direct contact between the positive and negative electrodes, no battery reaction will occur, and the battery temperature will not increase, thus preventing the generation and combustion of electrolyte gases. Furthermore, with the electrolyte in a frozen state, the lithium-ion mobility is very low, significantly reducing the electrical conductivity based on lithium-ion migration. This prevents electrolyte vaporization and therefore the generation of flammable gases such as ethylene, propylene, and hydrogen.

[0064] In the battery freezing step, if the upper limit of the temperature range is exceeded, the residual voltage inside the battery drops to 0V, which may cause a short circuit and battery reaction, and the electrolyte cannot be completely frozen, making it unsuitable. If the lower limit of the temperature range is exceeded, a lot of energy is required for freezing, thus posing an uneconomical problem.

[0065] In one embodiment, the battery freezing step can be carried out by cooling to a temperature range of -60 to -20°C under a vacuum environment below 100 Torr. The battery freezing step can be carried out at a temperature range capable of suppressing electrolyte vaporization. The vacuum environment can be, for example, an inert gas, carbon dioxide, nitrogen, water, or a combination thereof.

[0066] By implementing this process in a vacuum environment with pressure below 100 Torr, the reaction between the electrolyte and oxygen can be prevented by suppressing the oxygen supply, thus preventing an explosion. Furthermore, the vaporization of the electrolyte can be suppressed, thereby avoiding the generation of flammable gases such as ethylene, propylene, and hydrogen.

[0067] If the battery freezing step is carried out in an air environment or under a pressure exceeding 100 Torr, residual voltage may remain inside the battery. Since the electrolyte is not frozen in the temperature range of -60 to -20°C, there is a risk that the residual voltage could cause a short circuit, and the resulting sparks could cause the electrolyte to vaporize and explode.

[0068] In one embodiment, the step of freezing the battery satisfies the battery processing method of Formula 7 below.

[0069] [Formula 6] Minimum cooldown time (Hr) = A × (W) 0.33 ) A = 4 × e(-0.02 × dT), W = battery weight (Kg), dT = |external cooling temperature - target temperature|, where || represents the absolute value.

[0070] In one embodiment, the step of freezing the battery may include cooling the battery to -150°C to -20°C. In one embodiment, the step of preparing the battery may include performing a forced discharge.

[0071] The step of crushing the battery can be performed using a crusher to obtain pulverized material. The crushing is a non-limiting example and may include grinding the waste battery into powder by applying physical or mechanical force. The crushing step can separate a portion of the larger impurities, such as aluminum (Al), copper (Cu), iron (Fe), and plastics, from the components contained in the waste battery. The state in which the larger impurities are separated is referred to as black powder, and the battery pulverized material, such as black powder, can be prepared through the crushing step.

[0072] In one embodiment, the battery fragments may contain aluminum (Al), manganese (Mn), lithium (Li), copper (Cu), cobalt (Co), nickel (Ni), carbon (C), and residual impurities. In one embodiment, for the black powder, nickel (Ni) comprises 5 to 40 wt%, cobalt (Co) comprises 1 to 20 wt%, manganese (Mn) comprises 1 to 15 wt%, lithium (Li) comprises 0.5 to 5 wt%, carbon (C) comprises 10 to 70 wt%, aluminum (Al) comprises 0.0001 to 20 wt%, copper (Cu) comprises 0.0001 to 20 wt%, and the total amount of impurities such as iron (Fe) and phosphorus (P) may be less than 10 wt%. The composition of the black powder may vary depending on the ratio of nickel, cobalt, and manganese. When the lithium secondary battery is crushed, the nickel, cobalt, and manganese can be adjusted by the oxide of the positive electrode material in the lithium secondary battery.

[0073] In one embodiment, the step of crushing the battery can be a crushing method utilizing at least one of shear force, compressive force, and tensile force. Specifically, the crushing step can be performed, for example, by at least one of a hammer mill, a ball mill, and a stirred ball mill. The hammer mill can perform at least one of the steps of decomposition, stamping, and grinding; this is a non-limiting example, and obviously various crushing or pulverizing devices such as industrial pulverizers can be used for pulverization. In one embodiment, the particle size of the battery fragments can be within 50 mm, specifically within 30 mm. If it is larger than this range, more energy needs to be supplied in the subsequent heat treatment step, thus presenting an uneconomical problem.

[0074] The step of heat-treating the broken battery fragments in the range of 600 to 1500°C can be a dry heat treatment step. Specifically, the heat treatment step involves placing the fragments in a furnace capable of heating to a high temperature, thereby raising the fragments to a temperature above their melting point. The dry heat treatment step S200 can include a high-temperature reduction reaction, eliminating the need for a melting step.

[0075] In one embodiment, the heat treatment conditions may include a range of 900 to 1800°C. Specifically, the range may be 1200 to 1800°C, more specifically, 1300 to 1700°C. Exceeding the upper limit of the range results in lithium vaporization and loss, while exceeding the lower limit prevents the sintering and reduction of alloying elements. Within the temperature range, carbon in the fragments is burned to a minimum, allowing the reduction reaction to proceed with minimal carbon dioxide production.

[0076] In one embodiment, step S200 of dry heat treatment of the shredded material can be carried out in an environment of at least one gas selected from inert gas, carbon dioxide, carbon monoxide, and hydrocarbon gas. For example, the inert gas may include at least one of argon and nitrogen. Because the reduction reaction of the shredded material is carried out in the gas environment, a valuable metal recovery alloy composed of valuable metals contained in the shredded material can be effectively recovered.

[0077] In one embodiment, a portion of the gaseous environment may contain impurities, including residual oxygen. When the oxygen content in the impurities is high, it combines with components of the broken material during the reduction reaction to form carbon dioxide, which is then vaporized along with lithium, making recovery difficult.

[0078] In one embodiment, the average oxygen partial pressure in the dry heat treatment step can be in the range of 0.01 to 1 atm. Specifically, if the oxygen partial pressure is higher than this value, there is a problem of lithium loss and large-scale carbon dioxide generation under localized high-temperature conditions. If the oxygen partial pressure is lower than the lower limit of the range, there is a problem of decreased Li recovery rate due to poor LiAlO2 formation.

[0079] Specifically, in the dry heat treatment step, the valuable metal recycling composition, which alloys the oxides of nickel, cobalt, manganese, and lithium in the crushed material, may contain valuable metals and residual impurities. For example, the valuable metal recycling composition may contain aluminum (Al), manganese (Mn), lithium (Li), copper (Cu), cobalt (Co), nickel (Ni), carbon (C), and residual impurities. Specifically, the valuable metal recycling composition may contain valuable metal recycling alloys and lithium compounds. Specifically, the valuable metal recycling composition may contain valuable metal alloys, lithium compounds, copper (Cu), and graphite.

[0080] For the aforementioned valuable metal recycling alloy, based on 100% by weight of the total alloy composition, the valuable metal comprises 45% by weight or more, and may contain the balance of impurities. The valuable metal recycling alloy may contain at least one of valuable metals such as nickel (Ni), cobalt (Co), manganese (Mn), lithium (Li), carbon (C), aluminum (Al), and copper (Cu), and residual impurities. In this specification, valuable metal may refer to the high-valence metal component contained in the battery, and may specifically refer to nickel, cobalt, manganese, aluminum, copper, and lithium. In one embodiment, the valuable metal may comprise 70% by weight or more.

[0081] In one embodiment, the valuable metal may contain lithium (Li) ranging from 0.01% to 5% by weight. Since the lithium falls within this range, it offers the advantage of maximizing Li recovery in the Li refining process. If the upper limit of the range is exceeded, there is a decrease in Ni and Co recovery rates; if the lower limit is exceeded, the Li recovery rate in the Li refining process decreases, leading to increased process costs.

[0082] In one embodiment, the copper (Cu) content in the valuable metal recycling alloy may be 0.02% by weight or more. Specifically, the valuable metal recycling alloy may contain a content ranging from 0.1% to 15% by weight. If the copper content exceeds the upper limit of the range, there is a problem of increased process costs due to increased CuSO4 precipitation during leaching and solvent extraction. If the copper content exceeds the lower limit of the range, it is difficult to generate low-melting-point Ni-Co-Mn, resulting in an increase in the amount of unreacted matter.

[0083] In one embodiment, the copper may be combined with nickel (Ni) in the valuable metal to form an alloy. In one embodiment, the nickel may comprise 5 to 40% by weight. If the nickel exceeds the upper limit of the range, there is a problem of nickel carbide (Ni3C) formation leading to a decrease in leaching rate; if the nickel exceeds the lower limit of the range, there is a problem of decreased Ni recovery rate in leaching and solvent extraction.

[0084] In one embodiment, the graphite content in the valuable metal recycling alloy may be less than 7% by weight. Specifically, the graphite content is 1% to 6%, more specifically, it may be 2% to 5% by weight. Since the graphite content in the valuable metal recycling alloy meets the aforementioned range, the leaching efficiency can be improved during acid leaching due to the lower graphite content, and CO2 generation can be reduced by recovering the graphite.

[0085] If the upper limit of the range is exceeded, the negative electrode material will remain in an unreacted state, alloying cannot proceed normally, and there is a problem of valuable metal oxides remaining in the positive electrode material. If the lower limit of the range is exceeded, there is a possibility of lithium loss due to high temperature.

[0086] In one embodiment, for the valuable metal recycling alloy, aluminum (Al) may be present in the range of 0.25 to 30% by weight. If the aluminum content exceeds the upper limit of the range, there is a problem of decreased Ni and Co recovery rates in the leaching and solvent extraction processes; if the aluminum content exceeds the lower limit of the range, it is difficult to generate LiAlO2, resulting in a decrease in Li recovery rate.

[0087] The valuable metal content in the valuable metal recycling composition can be 45% by weight. Specifically, the basic component of the valuable metal recycling composition is nickel, and it may contain substances such as cobalt, manganese, copper, aluminum, and lithium.

[0088] In one embodiment, the lithium content in the composition may be in the range of 0.1% to 10% by weight. Specifically, the lithium content in the composition may be in the range of 8% to 10% by weight.

[0089] The lithium content in the composition can include not only the lithium in the valuable metal recovery alloy, but also the lithium content contained in the lithium compound. If the upper limit of the range is exceeded, lithium loss occurs due to the oxygen combustion of carbon process instead of an oxygen-free reaction, thus preventing the recovery of lithium from the high-value metals within the battery. If the lower limit of the range is exceeded, problems such as reduced recovery rate of valuable metals arise.

[0090] The lithium compound is a valuable metal reactant containing a lithium compound, which includes any one of LiAlO2, Li5AlO4, LiAl5O8, Li2CO3, LiF, Li3PO4, Li4P2O7, LiPO3, Li2SiO3, Li4SiO4, Li2Si2O5, LiFeO2, LiFe5O8, Li3Fe5O8, and Li5FeO4. The Li content in the compound can be from 4% to 35% by weight, based on a total weight of 100%. In one embodiment, at least a portion of the lithium compound can be disposed on a valuable metal alloy. Specifically, at least a portion of the lithium compound can form a compound through physical or chemical bonding between lithium and aluminum contained in the composition.

[0091] For example, when recovering valuable metals from waste batteries, the valuable metals exist in the form of oxides, and reduction occurs in the negative electrode material caused by graphite in the process temperature and oxygen environment described in this invention. At this time, copper, acting as a current collector, melts and exists in a liquid phase, which can play a role in aggregating the reduced valuable metals. The aluminum of the current collector and another current collector participate in a partial reduction reaction with the oxide of the positive electrode material, and the remainder reacts with lithium, remaining as a lithium-aluminum oxide. Specifically, the valuable metal recovery composition may contain a lithium compound, which may be prepared through the reduction reaction. For example, the lithium compound may be lithium aluminate (2LiAlO2).

[0092] The graphite has a graphitization degree of more than 50% and can be composed of graphite material with a total weight ratio of more than 70%.

[0093] In the step of separating graphite from the valuable metal recovery composition, sulfuric acid leaching does not dissolve the graphite, which is hydrophobic, and the powder containing sulfuric acid and nickel-containing valuable metal alloys between the graphite particles may float and be lost. To avoid this, a step of pre-removing graphite from the valuable metal recovery composition can be performed.

[0094] In one embodiment, the step of separating graphite from the valuable metal recycling composition may be carried out using at least one of particle size separation, gravity separation, and flotation.

[0095] The step of leaching the valuable metals, lithium compounds, and copper (Cu) in the aforementioned valuable metal recovery composition with sulfuric acid can be carried out in an aqueous sulfuric acid solution containing lithium at a pH range of 0.2 to 4.0, specifically 0.5 to 3.0, and more specifically 0.8 to 2.0. When the pH meets the aforementioned range, there is an advantage of excellent selective leaching of Li.

[0096] If the pH exceeds the upper limit of the aforementioned range, lithium leaching will be delayed, resulting in a decrease in lithium recovery rate. If the pH exceeds the lower limit of the aforementioned range, there will be an issue of excessive leaching of valuable metals and copper.

[0097] The step of leaching the valuable metals, lithium compounds, and copper (Cu) in the valuable metal recovery composition with sulfuric acid is wherein the equivalent ratio of the sulfuric acid is 0.5 to 4.0, specifically 0.8 to 3.5, and more specifically 1.0 to 3.0. When the equivalent ratio of the sulfuric acid meets the range, the sulfuric acid content can be minimized while increasing the leaching rate of the valuable metal recovery alloy.

[0098] If the equivalent ratio of sulfuric acid exceeds the upper limit of the aforementioned range, there is a problem of excessive leaching of valuable metals and copper. If the equivalent ratio of sulfuric acid exceeds the lower limit of the aforementioned range, lithium leaching is delayed, resulting in a decrease in lithium recovery rate.

[0099] In the step of sulfuric acid leaching of the valuable metal recovery alloy, the operating temperature is 10 to 150°C, specifically 20 to 120°C, and more specifically 40 to 90°C. When the operating temperature meets the range, the boiling over of the sulfuric acid is suppressed, and the leaching efficiency is excellent.

[0100] If the operating temperature exceeds the upper limit of the aforementioned range, there is a problem of excessive leaching of valuable metals and copper. If the operating temperature exceeds the lower limit of the aforementioned range, lithium leaching is delayed, resulting in a decrease in lithium recovery rate.

[0101] The step of sulfuric acid leaching of valuable metal recovery alloys, lithium compounds, and Cu can be performed at a concentration of 0.1 to 20.0 Nm. 3 / hr, specifically 1 to 15 Nm 3 / hr, more specifically 3 to 8 Nm 3 The process is carried out under an inert gas supply at a rate of / hr. This inert gas can be nitrogen, argon, helium, etc. If oxygen is added within this supply rate range, the selective leaching rate of Li can be accelerated during the leaching process of the valuable metal recovery alloy.

[0102] If the gas supply rate exceeds the upper limit of the aforementioned range, there is a problem of excessive leaching of valuable metals and copper. If the gas supply rate exceeds the lower limit of the aforementioned range, lithium leaching is delayed, resulting in a decrease in lithium recovery rate.

[0103] In the step of recovering the valuable metal and the copper (Cu) from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation, the lithium-containing sulfuric acid aqueous solution after lithium leaching can be separated into a liquid phase, while the valuable metal and the copper (Cu) can be separated into a solid phase.

[0104] In one embodiment, the step of recovering the valuable metal and the copper (Cu) from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation may include a step of magnetic separation after the solid-liquid separation to separate the valuable metal and Cu. By further including a magnetic separation step after the solid-liquid separation step, copper can be recovered more easily.

[0105] In one embodiment, the step of leaching the valuable metal, lithium compound, and copper (Cu) in the valuable metal recovery composition with sulfuric acid may include the step of adding sodium hydroxide (NaOH) to remove impurities from the lithium-containing sulfuric acid aqueous solution between the step of leaching the valuable metal, lithium compound, and copper (Cu) in the valuable metal recovery composition and the step of recovering the valuable metal and copper (Cu) from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation.

[0106] In one embodiment, the step of removing impurities from the sulfuric acid aqueous solution may involve controlling the pH of the sulfuric acid aqueous solution to between 3.0 and 8.0. Specifically, the pH may be between 4.0 and 7.0. The step of removing impurities from the sulfuric acid aqueous solution may be a step of removing impurities from the sulfuric acid aqueous solution before performing a solid-liquid separation process to prepare a high-concentration lithium-containing sulfuric acid aqueous solution. Specifically, the impurities may include, for example, at least one element selected from Ni, Co, Mn, Cu, Ti, Zn, Pb, P, Ca, Mg, B, K, Na, Si, and Fe.

[0107] The step of removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recovery step can remove residual impurities, such as elements like Mg or Ca, from the lithium-containing sulfuric acid aqueous solution recovered through solid-liquid separation.

[0108] In one embodiment, the step of removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recycling step may involve adjusting the pH of the lithium-containing sulfuric acid aqueous solution to a range of 8.5 to 12.0. Specifically, the pH may be between 9.0 and 11.0. Since the pH meets the aforementioned range, residual impurities such as Ca and Mg in lithium sulfate are easily removed, providing a lithium-containing sulfuric acid aqueous solution with a high lithium concentration.

[0109] In one embodiment, the step of recovering the valuable metal and the copper (Cu) from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation may include a step of removing impurities by ion exchange between the step of removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recovery step.

[0110] The step of removing impurities using ion exchange can be a step of removing small amounts of residual Zr, T, B or F elements from lithium-containing sulfuric acid aqueous solution recovered through solid-liquid separation.

[0111] Embodiments of the present invention will be described in detail below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments; the scope of the claims shall prevail.

[0112] <Experimental Example> Preparation of compositions for recycling valuable metals <Battery internal temperature based on minimum freezing time> Without freezing, the battery pack used in the example is crushed using the same crusher as in the example. During the crushing process, as... Figure 3a and Figure 3b As shown, a flame was generated due to a short circuit. The battery used at this time was a 622NCM battery.

[0113] As described above, through the embodiments and comparative examples, it can be confirmed that the step of freezing the battery pack containing the battery before the battery breaks prevents short circuits and flames from occurring during the battery breaking process, thus resulting in excellent stability.

[0114] Figure 1 This illustrates the variation of battery voltage with cooling temperature according to an embodiment of the present invention.

[0115] Reference Figure 1 It has been confirmed that when the battery is frozen to -80°C and the battery voltage is measured, the battery pack exhibits almost the same voltage at a high temperature of approximately 40°C, at room temperature, and at -60°C, thus without loss of battery characteristics. Subsequently, when the temperature drops from -60°C to -70°C, the voltage drops sharply, and it has been confirmed that the voltage reaches 0 at -70°C. As mentioned above, it has been confirmed that no short circuit occurs when the battery is frozen to -60 to -150°C.

[0116] Figure 2 This is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to an embodiment of the present invention.

[0117] Reference Figure 2 It can be confirmed that the battery processing method according to an embodiment of the present invention can derive a minimum cooling time for cooling the battery during the battery freezing step. Specifically, it can be confirmed that the minimum cooling time is related to the battery weight, the external cooling temperature, and the target temperature.

[0118] More specifically, when the target temperature is set to -70°C and the battery weights are 2.5 kg (A), 10 kg (B), 20 kg (C), and 50 kg (D), the external cooling temperature and minimum cooling time are shown in the figure. During battery cooling, the electrolyte begins to cool only after a predetermined time, confirming that the voltage reaches 0. This confirms that a minimum holding time is required to fully cool the battery to its interior (specifically, the electrolyte).

[0119] Specifically, it can be confirmed that under heat transfer conditions for cooling (heat being carried to the outside), the battery weight and cooling time are required if the battery's specific heat is taken into account. As described above, in this invention, in order to cool the battery, the minimum time required for cooling can be determined using the external cooling temperature and target temperature for freezing, and the battery weight.

[0120] Table 1 below shows the minimum cooling time based on battery weight and external cooling temperature.

[0121] Table 1

[0122] As can be seen from Table 1 above, the smaller the battery weight, the shorter the minimum cooling time required for the battery to be cooled. Furthermore, when cooling is performed using the value of Equation 2, derived from the relationship between battery weight, external cooling temperature, and target temperature—that is, the minimum cooling time—it can be confirmed that the battery is cooled, specifically to the electrolyte level. Moreover, when the battery is cooled for a time exceeding the value of Equation 2, no fire will occur during the subsequent battery crushing process.

[0123] Figure 3a and Figure 3b This is a photograph of a fire that occurred when the object broke after freezing, according to a comparative example of the present invention, where the freezing time was shorter than the minimum cooling time. Figure 3c and Figure 3d The photograph shows that no fire occurred when the item was frozen and then broken according to an embodiment of the present invention, and the freezing time was longer than the minimum cooling time.

[0124] Reference Figure 3a and Figure 3b An experiment was conducted on the fire occurrence state of the broken objects when the freezing time during battery cooling was less than the minimum required cooling time. In the experiment, with a battery weight of 25 kg, an external cooling temperature of -95°C, and a target freezing temperature of -70°C, if the value of Equation 2 below is 7 hours, then the experiment was conducted for less than 5 hours (the value of Equation 2 above).

[0125] <Formula 2> Minimum cooldown time = A × (W) 0.33 ) In Equation 2 above, A = 4 × e(-0.02 × dT), W = battery weight (Kg), dT = |external cooling temperature - target temperature|, where || represents the absolute value.

[0126] Reference Figure 3c and Figure 3d An experiment was conducted on the fire ignition state of the broken parts when the battery was frozen to a temperature exceeding the minimum freezing time required for cooling. In this experiment, [the experiment was conducted with...]. Figure 3a and Figure 3b The experiment was conducted under the same battery weight, external cooling temperature, and minimum freezing time of more than 7 hours.

[0127] Table 2 below compares according to Figures 3a to 3d The fire occurrence status of embodiments and comparative examples based on the same battery weight, external cooling temperature, and minimum freezing time is described. For the determination of the fire occurrence status, if a fire is observed after the battery breaks, it is indicated as "O"; otherwise, it is indicated as "X".

[0128] Table 2

[0129] As can be seen from Table 2 above, if the battery cooling time is less than the value of Equation 2 (equivalent to the minimum cooling time), it will not cool down to the electrolyte level, and a fire will occur after the battery breaks. As mentioned above, if the battery is cooled with the value of Equation 2 as the minimum cooling time, the broken pieces can be used stably after the battery breaks, and a fire will not occur.

[0130] <Calcination and Heat Treatment of Battery Fragments> The calcination heat treatment of the battery fragments is carried out in a dry heat treatment at a temperature range of 700 to 1350°C with oxygen content of less than 5% by volume. Specifically, the calcination heat treatment in this experiment can be carried out in a dry heat treatment at a temperature range of 900 to 1200°C, specifically about 1100°C, with oxygen content of about 3% by volume, thereby obtaining a composition for valuable metal recovery.

[0131] At this point, based on the mid-length axis of the horizontal, vertical and height, the size of the battery fragments is 10 to 20 mm, the graphite content is more than 5%, and the impurity content of the aluminum cap, PCB substrate and other plastic or iron blocks in the fragments is less than 5%.

[0132] For the valuable metal recycling composition prepared by the calcination heat treatment step, a valuable metal alloy containing a valuable metal, a lithium compound disposed on the core and disposed on the shell, a valuable metal alloy, a lithium compound, copper and graphite are prepared.

[0133] <Separation from compositions used in the recovery of valuable metals> The composition for recycling valuable metals obtained through a high-temperature reduction process is used to separate magnetic and non-magnetic materials using a magnetic separator with a magnetic strength of 3000 Gauss.

[0134] Subsequently, the non-magnetic materials separated by magnetic separation are subjected to flotation using a Denver Sub-A flotation apparatus under the following conditions: a mineral liquor concentration of 30%, an impeller speed of 500 rpm, kerosene concentration of 0.1 ml / 100 g, and MIBC concentration of 0.1 ml / 100 g. Through this flotation, the lighter graphite powder floats to the top of the apparatus, where it is separated to recover the graphite.

[0135] Through the flotation process, graphite is separated as a floating object, and lithium-containing substances are separated and recovered as precipitates.

[0136] Subsequently, the magnetically separated magnetic material was pulverized using a vertical stirring mill at 500 rpm, an impeller tip speed of 2.8 m / s, a pulverization time of 60 minutes, and a solid content of 30% by weight. For the magnetic material, it was confirmed that the reactants, consisting of a core containing a valence metal and a shell containing a lithium compound disposed on the core, were separated into the core and the shell during the pulverization process. For the product of the pulverization process, to further separate the alloy core containing the valence metal and the lithium compound, a 3000 gauss magnetic separator was used to separate the magnetic and non-magnetic materials.

[0137] Subsequently, particle size separation was performed using a 75µm sieve, thereby recovering the NCM alloy as coarse particles and the lithium oxide as fine particles.

[0138] Valuable metal alloys, lithium compounds, and Cu were obtained through the aforementioned magnetic separation, flotation, and particle size screening.

[0139] <Selective leaching steps for lithium> A valence metal alloy, lithium compound, and Cu were obtained through a high-temperature heat treatment process. The valence metal alloy, lithium compound, and Cu were then subjected to sulfuric acid leaching, thereby selectively leaching lithium (Li). The lithium leaching can be described by the following reaction formula.

[0140] [Reaction Formula 1] Ni(s) + H2SO 4(aq) =NiSO 4(aq) +H 2(g) , △G o m = -46.3 (kJ / mol) [Reaction 2] Co(s) + H2SO4(aq) =CoSO 4(aq) +H 2(g) , △G o m = -54.7 (kJ / mol) [Reaction 3] Li2O(s) + H2SO 4(aq) =Li2SO 4(aq) +H2O (aq) , △G o m = -260.5 (kJ / mol) [Reaction 4] Cu(s) + H₂SO 4(aq) =CuSO 4(aq) +H 2(g) , △G o m = 69.5 (kJ / mol) According to reactions 1 and 2, the Gibbs free energy of Ni and Co during leaching in sulfuric acid is -46 to -53 kJ / mol, which is lower than that of lithium oxides during leaching in sulfuric acid (-260.5 kJ / mol), by only about 20%, confirming that the leaching reaction is not accelerated. For Cu, compared to Ni, Co, and Li, the Gibbs free energy is as high as 69.5 kJ / mol, confirming that it is not easily leached in sulfuric acid.

[0141] Lithium-containing alloys and compounds, ensured by high-temperature heat treatment, were selectively leached for 120 minutes at a pH range of 0.4 to 2.0, a temperature of 50°C, and a sulfuric acid equivalent ratio of 0.8 to 2.0 M. The experiment was conducted until a lithium leaching rate of 6 g / L was achieved, assuming a leaching rate of 100% in the sulfuric acid aqueous solution.

[0142] Tables 3 to 5 below show the time-based lithium leaching results when the sulfuric acid equivalent ratios are 1.0 M, 1.2 M, and 1.6 M, respectively. Specifically, Table 3 shows the time-based selective Li leaching results (g / L) (sulfuric acid equivalent ratio = 1.0 M, temperature = 50 °C), Table 4 shows the time-based selective Li leaching results (g / L) (sulfuric acid equivalent ratio = 1.2 M, temperature = 50 °C), and Table 5 shows the time-based selective Li leaching results (g / L) (sulfuric acid equivalent ratio = 1.6 M, temperature = 50 °C).

[0143] Table 3

[0144] Table 4

[0145] Table 5

[0146] Tables 3 to 5 above confirm that, at 50°C, lithium leaching within 120 minutes can ensure a lithium leaching rate of 94% to 99% or higher based on the sulfuric acid equivalent ratio. Furthermore, it has been confirmed that the leaching concentrations of Ni, Co, and Mn can be controlled below 5 g / L, and the leaching concentration of Cu can be controlled below 1 g / L.

[0147] <Removal of impurities from lithium-containing sulfuric acid aqueous solution> The lithium-containing sulfuric acid aqueous solution obtained from the aforementioned lithium leaching process contains impurities such as Ni, Co, Mn, Cu, Ti, Zn, Pb, P, Ca, Mg, B, K, Na, Si, and Fe. To remove these impurities from the sulfuric acid aqueous solution, an impurity removal process is performed.

[0148] To remove impurities from the sulfuric acid aqueous solution, for the lithium-containing sulfuric acid aqueous solution ensured by the sulfuric acid leaching process of the lithium-containing sulfuric acid aqueous solution, sodium hydroxide (NaOH) is added to the sulfuric acid aqueous solution according to the following reaction formulas 5 and 6 to adjust the pH of the lithium-containing sulfuric acid aqueous solution to 3.0 to 8.0. Adjusting the sulfuric acid aqueous solution to the aforementioned pH range removes residual impurities such as Ni, Co, Mn, Cu, Ti, Zn, Pb, P, Ca, Mg, B, K, Na, Si, and Fe from the sulfuric acid aqueous solution.

[0149] [Reaction 5] Me2(SO4) 3(aq) +6NaOH=2Me(OH)3(s)+3Na2SO 4(aq) +H2SO 4(aq) (Me = Fe, Al, Ti) [Reaction Formula 6] MeSO 4(aq) +2NaOH=Me(OH)2(s)+Na2SO 4(aq) +H2SO 4(aq) (Me=Ni, Co, Mn, Cu, Zn, Pb) Solid-liquid separation Solid-liquid separation is performed to separate the precipitate from the sulfuric acid aqueous solution after removing the aforementioned impurities. The precipitate in the sulfuric acid aqueous solution is separated by solid-liquid separation, and a high-purity lithium-containing sulfuric acid aqueous solution is separately separated.

[0150] <Remove additional impurities> Subsequently, the following process was performed: ion exchange was used to remove trace amounts of residual Zr, T, B, and F impurities from the sulfuric acid aqueous solution after solid-liquid separation. Then, to further remove residual Ca and Mg impurities from the sulfuric acid aqueous solution, the pH was adjusted to 8.5 to 12.0, thereby preparing a high-purity nickel-containing sulfuric acid aqueous solution.

[0151] Table 6 below shows the concentration of lithium-containing sulfuric acid aqueous solution after the lithium leaching step and the impurity removal step.

[0152] Table 6

[0153] As confirmed in Table 6 above, the lithium-containing sulfuric acid aqueous solution of the present invention has a high lithium concentration and a low impurity concentration, thereby preparing a high-purity sulfuric acid aqueous solution that can be used to prepare raw materials (specifically, positive electrode materials) for secondary batteries.

[0154] Table 7 below compares the concentrations of the lithium-containing sulfuric acid aqueous solution of the present invention with those of the sulfuric acid aqueous solution extracted from spodumene and the lithium-containing sulfuric acid aqueous solution of the prototype used in the preparation of conventional cathode materials.

[0155] Table 7

[0156] As can be confirmed from Table 7 above, the lithium-containing sulfuric acid aqueous solution recovered from waste batteries, as described in this invention, satisfies Formulas 1 to 4 of this invention. In contrast, the sulfuric acid aqueous solution extracted from spodumene through a leaching process and the commonly recovered black mass sample do not satisfy Formulas 1 to 4 of this invention. Furthermore, the lithium-containing sulfuric acid aqueous solution recovered from waste batteries of this invention has a relatively higher lithium content than the spodumene extract of the comparative example, resulting in less aluminum hydroxide formation during solid-liquid separation, which is beneficial for solid-liquid separation. Compared to the black mass of the comparative example, it can be confirmed that the lithium-containing sulfuric acid aqueous solution recovered from waste batteries of this invention has a higher lithium content. In addition, since the lithium content in the sulfuric acid aqueous solution is relatively higher than the Ni, Co, and Mn content, the addition of NaOH to remove impurities has the advantage of reducing the loss of Ni, Co, and Mn compared to the black mass with a higher Ni, Co, and Mn content.

[0157] The preferred embodiments have been described in detail above, but the scope of the present invention is not limited to the above embodiments. Various modifications and improvements made by those skilled in the art using the basic concepts defined in the claims also fall within the scope of the present invention.

Claims

1. A method for preparing a lithium-containing sulfuric acid aqueous solution, comprising: The steps of obtaining a valuable metal recycling composition containing valuable metal alloys, lithium compounds, copper and graphite from waste batteries; The step of separating graphite from the composition for recycling valuable metals; The step of leaching the valuable metals, lithium compounds, and copper in the composition for recycling valuable metals with sulfuric acid; The step of recovering the valuable metal and the copper from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation; as well as The step of removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recycling step.

2. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 1, wherein, At least a portion of the lithium compound is disposed on a valuable metal alloy.

3. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 1, wherein, The steps for obtaining a composition for recycling valuable metals include: Steps for preparing lithium-ion batteries; The step of breaking the battery; The step of heat-treating the broken battery fragments in the range of 600 to 1500°C.

4. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 3, wherein, The step of heat-treating the broken battery fragments in the range of 600 to 1500°C is carried out in the range of oxygen concentration of 0.1 to 2.0% by volume.

5. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 3, wherein, The step of separating graphite from the composition for recycling valuable metals is carried out by at least one of particle size separation, gravity separation and flotation.

6. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 1, wherein, The step of leaching the valuable metals, lithium compounds and copper in the composition for recycling valuable metals with sulfuric acid is carried out by controlling the pH of the lithium-containing sulfuric acid aqueous solution within the range of 0.2 to 4.

0.

7. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 1, wherein, In the step of leaching the valuable metals, lithium compounds, and copper in the composition for recycling valuable metals with sulfuric acid, the equivalent ratio of the sulfuric acid is from 0.5 to 4.

0.

8. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 1, wherein, The step of leaching the valuable metals, lithium compounds and copper in the composition for recycling valuable metals with sulfuric acid is carried out in a temperature range of 10 to 150°C.

9. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 1, wherein, In the step of sulfuric acid leaching of the valuable metals, lithium compounds, and copper in the composition for recovering valuable metals, an inert gas is introduced at a concentration of 0.1 to 20.0 Nm. 3 Supply is made at a rate of / hr.

10. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 1, wherein, The step of leaching the valuable metals, lithium compounds, and copper in the composition for valuable metal recovery with sulfuric acid, and the step of recovering the valuable metals and copper from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation, includes the step of adding sodium hydroxide (NaOH) to remove impurities from the lithium-containing sulfuric acid aqueous solution.

11. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 10, wherein, The step of removing impurities from the sulfuric acid aqueous solution is carried out by controlling the pH of the sulfuric acid aqueous solution between 3.0 and 8.

0.

12. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 1, wherein, The step of recovering the valuable metal and the copper from the leached lithium-containing sulfuric acid aqueous solution by solid-liquid separation and the step of removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recovery step include a step of removing impurities by ion exchange.

13. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 1, wherein, The step of removing residual impurities from the leached lithium-containing sulfuric acid aqueous solution after the recycling step is carried out by adjusting the pH of the lithium-containing sulfuric acid aqueous solution to a range of 8.5 to 12.

0.

14. The method for preparing a lithium-containing sulfuric acid aqueous solution according to claim 3, wherein, The step of preparing a lithium-containing battery includes freezing the battery.

15. An aqueous solution of lithium-containing sulfuric acid, wherein, The lithium-containing sulfuric acid aqueous solution is recovered from waste batteries and contains lithium (Li), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), and the balance impurities, and satisfies the following formula 1. <Formula 1> 1.0 ≤ [Al] = 0.0297 × [Li] 2 +1.3205×[Li]±5≤16.0 In Equation 1 above, [Li] and [Al] represent the concentrations (g / L) of Li and Al in a lithium-containing sulfuric acid aqueous solution, respectively.

16. The lithium-containing sulfuric acid aqueous solution according to claim 15, wherein, The lithium-containing sulfuric acid aqueous solution satisfies the following formula 2. <Formula 2> 0.05 ≤ [Ni] = 0.1907 × [Li] 2 -0.2689×[Li]±3≤16.0 In Equation 2 above, [Li] and [Ni] represent the concentrations (g / L) of Li and Ni in a lithium-containing sulfuric acid aqueous solution, respectively.

17. The lithium-containing sulfuric acid aqueous solution according to claim 15, wherein, The lithium-containing sulfuric acid aqueous solution satisfies the following formula 3. <Formula 3> 0.05 ≤ [Co] = 0.0624 × [Li] 2 -0.1078×[Li]±2≤14.0 In Equation 3 above, [Li] and [Co] represent the concentrations (g / L) of Li and Co in lithium-containing sulfuric acid aqueous solution, respectively.

18. The lithium-containing sulfuric acid aqueous solution according to claim 15, wherein, The lithium-containing sulfuric acid aqueous solution satisfies the following formula 4. <Formula 4> 0.1 ≤ [Mn] = 0.0402 × [Li] 2 +0.117×[Li]±1≤12.0 In Equation 4 above, [Li] and [Mn] represent the concentrations (g / L) of Li and Mn in a lithium-containing sulfuric acid aqueous solution, respectively.

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