Lithium-containing aqueous sulfuric acid solution and method for preparing same

Abstract

The present invention relates to a lithium-containing aqueous sulfuric acid solution and a method for preparing same. This method for preparing the aqueous sulfuric acid solution comprises the steps of: obtaining a valuable metal recovery composition from waste batteries, the valuable metal recovery composition containing valuable metal alloys, lithium compounds, copper (Cu), and graphite; separating graphite from the valuable metal recovery composition; performing sulfuric acid leaching of valuable metals, lithium compounds, and copper (Cu) in the valuable metal recovery composition; recovering the valuable metals and the copper (Cu) through solid-liquid separation in a leached lithium-containing aqueous sulfuric acid solution; and removing residual impurities from the leached lithium-containing aqueous sulfuric acid solution after the recovery step.

Description

Aqueous sulfuric acid solution containing lithium and method for producing the same

[0001] The present invention relates to a raw material for battery manufacturing, and to a sulfuric acid aqueous solution containing lithium obtained from a used battery and a method for manufacturing the same.

[0002] As global demand for electric vehicles grows, the disposal of waste batteries generated from these vehicles is emerging as a social issue. Lithium secondary batteries, the primary raw material for these waste batteries, contain organic solvents, explosive materials, and heavy metals such as nickel, cobalt, manganese, and iron. However, nickel, cobalt, manganese, and lithium are valuable metals with high scarcity value. Therefore, the recovery and recycling processes for discarded lithium secondary batteries are emerging as a key research area.

[0003] Specifically, a lithium secondary battery is mainly composed of copper and aluminum used as a current collector, Li, Ni, Co, Mn-containing oxides constituting a positive electrode material, and graphite used as an negative electrode material, and includes a separator separating the positive electrode material and the negative electrode material, and an electrolyte injected into the separator. The solvent used as the solvent and salt constituting the electrolyte is mainly a mixture of carbonate organic substances such as ethylene carbonate and propylene carbonate, and for example, LiPF6 is used.

[0004] In order to utilize the above-mentioned waste batteries, development is actively underway on a waste battery recycling process that crushes the waste batteries to produce intermediate materials such as waste battery shreds or black powder, and then recovers valuable metals through a post-process.

[0005] The recovered valuable metals are then subjected to an acid leaching process to recover valuable metals within the battery, such as Li, Ni, Co, and Mn. Acid leaching utilizes an acid, such as sulfuric acid, to ionize the valuable metals within the battery and remove impurities. Valuable metals, such as Ni, Co, or Mn, within the sulfuric acid from which the impurities have been removed are extracted in the form of sulfides through solvent extraction and crystallization processes.

[0006] After sulfuric acid leaching, the Li content in the sulfuric acid is about 6 to 10 g / L, but after solvent extraction and crystallization of Ni, Co, Mn, etc., the Li remaining in the sulfuric acid is diluted to about 1 to 2 g / L. In order to manufacture raw materials for battery manufacturing, specifically lithium, by utilizing a low-concentration Li-containing aqueous sulfuric acid solution, a multi-stage impurity removal step and a Li concentration step are performed. The purity of Li2CO3 or LiOH for battery manufacturing must be 99.5% or higher, so high extraction costs are required to obtain a material with the corresponding purity, and there is a problem of lowering the Li recovery rate, so research on a method to solve the above problem is necessary.

[0007] Additionally, as a method for obtaining lithium, a method can be performed in which lithium is extracted from lithium-containing ores, such as spodumene, by heat treatment at approximately 900°C or higher, followed by leaching with sulfuric acid to remove impurities. However, this method has the problem of generating a large amount of sediment during the removal of impurities, and excessive environmental treatment costs are incurred for landfilling the sediment.

[0008] In addition, among lithium-containing materials, the Li oxide (Li2O) or fluoride (LiF) present in the cathode material has a problem in that when exposed to high temperatures, Li(g) or LiF(g) vaporizes and lithium is lost, thereby reducing the lithium recovery rate.

[0009] The problem to be solved by the present invention is to provide a lithium-containing sulfuric acid solution that can be used as a raw material for manufacturing a lithium secondary battery and contains a high concentration of lithium.

[0010] Another technical problem to be solved by the present invention is to provide a method for producing a lithium-containing sulfuric acid solution that can be used as a raw material for manufacturing a lithium secondary battery and contains a high concentration of lithium.

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

[0012] <Formula 1>

[0013] 1.0 ≤ [Al] = 0.0297 × [Li] 2 + 1.3205 × [Li] ±5 ≤ 16.0

[0014] (In the above equation 1, [Li] and [Al] represent the concentrations (g / L) of Li and Al in the sulfuric acid solution containing lithium, respectively.)

[0015] In one embodiment, the sulfuric acid aqueous solution may satisfy the following equation 2.

[0016] <Formula 2>

[0017] 0.05 ≤ [Ni] = 0.1907 × [Li] 2 - 0.2689 × [Li] ±3 ≤ 16.0

[0018] (In the above equation 2, [Li] and [Ni] represent the concentrations (g / L) of Li and Ni in the sulfuric acid solution containing lithium, respectively.)

[0019] In one embodiment, the sulfuric acid aqueous solution may satisfy the following equation 3.

[0020] <Formula 3>

[0021] 0.05 ≤ [Co] = 0.0624 × [Li]2 - 0.1078 × [Li] ±2 ≤ 14.0

[0022] (In the above formula 3, [Li] and [Co] represent the concentrations (g / L) of Li and Co in the sulfuric acid solution containing lithium, respectively.)

[0023] In one embodiment, the sulfuric acid aqueous solution may satisfy the following equation 4.

[0024] <Formula 4>

[0025] 0.1 ≤ [Mn] = 0.0402 × [Li] 2 + 0.117 × [Li] ±1 ≤ 12.0

[0026] (In the above equation 4, [Li] and [Mn] represent the concentrations (g / L) of Li and Mn in the sulfuric acid solution containing lithium, respectively.)

[0027] According to another embodiment of the present invention, a method for producing a sulfuric acid aqueous solution containing lithium includes the steps of obtaining a composition for recovering valuable metals, which comprises a valuable metal alloy, a lithium compound, copper (Cu), and graphite from a spent battery, separating graphite from the composition for recovering valuable metals, leaching the valuable metals, lithium compounds, and copper (Cu) in the composition for recovering valuable metals with sulfuric acid, separating solid and liquid in the sulfuric acid aqueous solution containing the leached lithium to recover the valuable metals and the copper (Cu), and removing residual impurities from the sulfuric acid aqueous solution containing the leached lithium that has undergone the recovery step.

[0028] In one embodiment, at least a portion of the lithium compound may contain lithium disposed on a precious metal alloy. In one embodiment, the step of obtaining a composition for recovering precious metal may include the steps of preparing a battery containing lithium (Li), crushing the battery, and heat-treating the crushed battery waste at a temperature ranging from 600 to 1,500°C.

[0029] In one embodiment, the step of heat-treating the shredded battery scrap at a range of 600 to 1,500°C may contain lithium in which an oxygen concentration is performed at a range of 0.1 to 2.0 vol%. In one embodiment, the step of separating graphite from the composition for recovering valuable metals may be performed by at least one of particle size separation, gravity separation, and flotation.

[0030] In one embodiment, the step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid may be performed such that the pH of the sulfuric acid aqueous solution containing lithium is controlled to be in the range of 0.2 to 4.0. In one embodiment, the step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid may be performed such that the equivalent ratio of the sulfuric acid is in the range of 0.5 to 4.0.

[0031] In one embodiment, the step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid may be performed at a temperature range of 10 to 150° C. In one embodiment, the step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid may be performed using an inert gas at a pressure of 0.1 to 20.0 Nm 3 It can be supplied at a supply rate of / hr.

[0032] In one embodiment, the method may include a step of removing impurities in the sulfuric acid aqueous solution containing lithium by adding sodium hydroxide (NaOH) between the step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid and the step of recovering the valuable metal and the copper (Cu) by solid-liquid separation in the sulfuric acid aqueous solution containing the leached lithium.

[0033] In one embodiment, the step of removing impurities in the sulfuric acid aqueous solution may control the pH of the sulfuric acid aqueous solution to 3.0 to 8.0. In one embodiment, the step of recovering the valuable metal and the copper (Cu) by solid-liquid separation in the sulfuric acid aqueous solution containing the leached lithium and the step of removing residual impurities in the sulfuric acid aqueous solution containing the leached lithium that has undergone the recovery step may include a step of removing impurities by an ion exchange method.

[0034] In one embodiment, the step of removing residual impurities from the sulfuric acid solution containing the leached lithium that has undergone the recovery step may adjust the pH of the sulfuric acid solution containing lithium to a range of 8.5 to 12.0. In one embodiment, the step of preparing the battery containing lithium (Li) may include the step of freezing the battery.

[0035] According to one embodiment of the present invention, a sulfuric acid aqueous solution containing lithium contains a predetermined proportion of valuable metals, and thus can be used as a raw material for manufacturing a lithium secondary battery, and provides a sulfuric acid aqueous solution containing a high concentration of lithium.

[0036] According to another embodiment of the present invention, a method for producing a sulfuric acid aqueous solution containing lithium is provided, wherein a lithium-containing compound recovered by treatment from a lithium-containing battery is leached with sulfuric acid under temperature and pH conditions, and impurities are removed to produce a sulfuric acid aqueous solution as a high-purity lithium-containing raw material for producing a lithium-containing battery.

[0037] FIG. 1 is a graph showing changes in battery voltage according to cooling temperature according to one embodiment of the present invention.

[0038] FIG. 2 is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0039] FIGS. 3a and 3b are photographs showing a fire occurring when crushing was performed after freezing for a shorter time than the minimum cooling time according to a comparative example of the present invention, and FIGS. 3c and 3d are photographs showing an example in which a fire did not occur when crushing was performed after freezing for a longer time than the minimum cooling time according to an embodiment of the present invention.

[0040] Figure 4 is a schematic diagram of the preparation of a high-purity lithium-containing sulfuric acid aqueous solution according to one embodiment of the present invention.

[0041] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0042] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "singular" and "comprising" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising" as used herein specifies a particular feature, region, integer, step, operation, element, and / or component, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0043] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0044] Additionally, % in this specification means weight % unless otherwise specified.

[0045] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0046] According to one embodiment of the present invention, a lithium-containing sulfuric acid solution has a high lithium concentration and can be used as a raw material for producing lithium hydroxide, which is used in the production of a cathode active material. Specifically, the lithium-containing sulfuric acid solution may be recovered from a spent battery.

[0047] In one embodiment, the lithium-containing sulfuric acid aqueous solution may include lithium (Li), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), and residual impurities. The residual impurities may include, for example, at least one of Ni, Co, Mn, Cu, Ti, Zn, Pb, P, Ca, Mg, B, K, Na, Si, Zr, and Fe.

[0048] In one embodiment, the lithium-containing sulfuric acid aqueous solution may satisfy the following equation 1.

[0049] <Formula 1>

[0050] 1.0 ≤ [Al] = 0.0297 × [Li] 2 + 1.3205 × [Li] ±5 ≤ 16.0

[0051] (In the above equation 1, [Li] and [Al] represent the concentrations (g / L) of Li and Al in the sulfuric acid solution containing lithium, respectively.)

[0052]

[0053] The above equation 1 may be a relationship between the concentrations of Li and Al in a sulfuric acid aqueous solution containing lithium. The equation 1 may specifically satisfy 1.0 to 16.0, more specifically 2.5 to 12.0. When the equation 1 is satisfied, it can be usefully applied to the production of LiOH used in the production of a high-nickel positive electrode active material, and there is an advantage in that the cost of the material can be reduced due to the high lithium concentration.

[0054] If the above equation 1 exceeds the upper limit of the above-mentioned range, there is a problem that lithium leaching is delayed and the lithium recovery rate is reduced. If the above equation 1 exceeds the lower limit of the above-mentioned range, there is a problem that Li is coprecipitated and lost during hydroxide precipitation for Al removal after leaching.

[0055] In one embodiment, the lithium-containing sulfuric acid aqueous solution may satisfy the following equation 2.

[0056] <Formula 2>

[0057] 0.05 ≤ [Ni] = 0.1907 × [Li] 2 - 0.2689 × [Li] ±3 ≤ 16.0

[0058] (In the above equation 2, [Li] and [Ni] represent the concentrations (g / L) of Li and Ni in the sulfuric acid solution containing lithium, respectively.)

[0059] The above equation 2 may be a relationship for the concentrations (g / L) of Li and Ni in the sulfuric acid aqueous solution. Specifically, the equation 2 may satisfy 0.05 to 16.0, and more specifically 0.3 to 7.5. When the equation 2 is satisfied, it can be usefully applied to the production of LiOH used in the production of a high-nickel positive electrode active material, and there is an advantage in that the cost of the material can be reduced due to the high lithium concentration.

[0060] If the above equation 2 exceeds the upper limit of the above-mentioned range, there is a problem that lithium leaching is delayed and the lithium recovery rate is reduced. If the above equation 2 exceeds the lower limit of the above-mentioned range, there is a problem that Li is coprecipitated and lost when generating hydroxide to remove Ni.

[0061] In one embodiment, the lithium-containing sulfuric acid aqueous solution may satisfy the following equation 3.

[0062] <Formula 3>

[0063] 0.05 ≤ [Co] = 0.0624 × [Li] 2 - 0.1078 × [Li] ±2 ≤ 14.0

[0064] (In the above formula 3, [Li] and [Co] represent the concentrations (g / L) of Li and Co in the sulfuric acid solution containing lithium, respectively.)

[0065] The above equation 3 may be a relationship for the concentrations (g / L) of Li and Co in a sulfuric acid aqueous solution containing lithium. Specifically, the above equation 2 may be satisfied in a range of 0.05 to 14.0, more specifically 0.15 to 6.0. When the above equation 3 is satisfied, it can be usefully applied to the production of LiOH used in the production of a high-nickel positive electrode active material, and there is an advantage in that the cost of the material can be reduced due to the high lithium concentration.

[0066] If the above equation 3 exceeds the upper limit of the above-mentioned range, there is a problem that lithium leaching is delayed and the lithium recovery rate is reduced. If the above equation 3 exceeds the lower limit of the above-mentioned range, there is a problem that Li is coprecipitated and lost when generating hydroxide to remove Co.

[0067] In one embodiment, the lithium-containing sulfuric acid aqueous solution may satisfy the following equation 4.

[0068] <Formula 4>

[0069] 0.1 ≤ [Mn] = 0.0402 × [Li] 2+ 0.117 × [Li] ±1 ≤ 12.0

[0070] (In the above equation 4, [Li] and [Mn] represent the concentrations (g / L) of Li and Mn in the sulfuric acid solution containing lithium, respectively.)

[0071] The above equation 4 may be a relationship for the concentrations (g / L) of Li and Mn in the sulfuric acid aqueous solution. Specifically, the equation 4 may be satisfied in a range of 0.1 to 12.0, and more specifically, 0.5 to 6.0. When the equation 4 is satisfied, it can be usefully applied to the production of LiOH used in the production of a high-nickel positive electrode active material, and has the advantage of reducing the cost of the material due to the high lithium concentration.

[0072] If the above equation 4 exceeds the upper limit of the above-mentioned range, there is a problem that lithium leaching is delayed and the lithium recovery rate is reduced. If the above equation 4 exceeds the lower limit of the above-mentioned range, there is a problem that Li is coprecipitated and lost when generating hydroxide to remove Mn.

[0073] In this way, since the lithium content in the sulfuric acid aqueous solution containing lithium satisfies the above-mentioned range, it is easy to increase the capacity of the battery, and it can be usefully applied to the production of a positive electrode active material precursor for a lithium secondary battery with excellent structural stability.

[0074] According to another embodiment of the present invention, a method for producing a sulfuric acid aqueous solution containing lithium may include the steps of obtaining a composition for recovering valuable metals, including a valuable metal alloy, a lithium compound, copper (Cu), and graphite, from a spent battery, separating graphite from the composition for recovering valuable metals, leaching the valuable metals, lithium compounds, and copper (Cu) in the composition for recovering valuable metals with sulfuric acid, separating solid and liquid in the sulfuric acid aqueous solution containing the leached lithium to recover the valuable metals and the copper (Cu), and removing residual impurities from the sulfuric acid aqueous solution containing the leached lithium that has undergone the recovery step.

[0075] The step of obtaining a composition for recovering valuable metals including a valuable metal alloy, a lithium compound, copper (Cu), and graphite from a spent battery may include the steps of preparing a battery containing lithium (Li), crushing the battery, and heat-treating the crushed battery waste at a temperature ranging from 600 to 1,500° C.

[0076] The step of preparing a battery containing lithium (Li) may include waste materials such as batteries that have reached the end of their useful life, scrap constituting the waste battery, positive electrode materials such as jelly rolls and slurry, defective products generated during the manufacturing process, residues within the manufacturing process, and debris generated during the manufacturing process, for example, waste materials within the manufacturing process of lithium ion batteries.

[0077] In one embodiment, the step of preparing a lithium (Li)-containing battery may include freezing the battery. Specifically, when a certain pressure is applied to the battery, the separator may be physically fractured, causing a short circuit to occur, generating a high current and generating a spark. This spark may ignite the electrolyte, potentially resulting in a fire.

[0078] The step of freezing the battery is to freeze the battery to suppress ignition of the liquid electrolyte contained within the battery, and then perform the crushing process, so that no problem due to ignition of the electrolyte occurs.

[0079] In one embodiment, the step of freezing the battery may be performed by cooling it to a temperature in the range of -150°C to -60°C. If the temperature exceeds the upper limit of the above temperature range, the voltage remaining inside the battery may not decrease to 0 V, which may cause a battery reaction due to a short circuit, and the electrolyte may not be completely frozen, which is not suitable.

[0080] When the temperature exceeds the lower limit of the above temperature range, the electrolyte is sufficiently frozen, the internal voltage of the battery is also lowered to 0 V, and even if a short circuit occurs in which the positive and negative electrodes are in direct contact, no battery reaction occurs, so the battery temperature does not increase, and gas generation and combustion of the electrolyte do not occur. In addition, since the electrolyte is in a frozen state, the mobility of lithium ions is very low, so that the conduction characteristics according to lithium ion movement may be significantly reduced, and since vaporization of the electrolyte does not occur, flammable gases such as ethylene, propylene, and hydrogen may not be generated.

[0081] In the step of freezing the battery, if the temperature exceeds the upper limit of the above-mentioned temperature range, the voltage remaining inside the battery may not decrease to 0 V, which may result in a battery reaction due to a short circuit, and the electrolyte may not be completely frozen, which is not appropriate. If the temperature exceeds the lower limit of the above-mentioned temperature range, a large amount of energy must be invested for freezing, which is uneconomical.

[0082] In one embodiment, the step of freezing the battery may be performed by cooling the battery to a temperature range of -60 to -20°C under a vacuum atmosphere of 100 torr or less. The step of freezing the battery may be performed at a temperature range capable of suppressing the evaporation of the electrolyte. The vacuum atmosphere may be, for example, an inert gas, carbon dioxide, nitrogen, water, or a combination thereof.

[0083] Since the process is performed by controlling the pressure to a vacuum atmosphere of 100 torr or less, the supply of oxygen is suppressed, thereby preventing the electrolyte from reacting with oxygen, preventing an explosion caused by this, and suppressing the vaporization of the electrolyte, thereby preventing the generation of flammable gases such as ethylene, propylene, and hydrogen.

[0084] In the step of freezing the above battery, if it is performed in an air atmosphere or at a pressure exceeding 100 torr, there is a problem that voltage may remain within the battery, and since the electrolyte is not in a frozen state in the temperature range of -60 to -20°C, the electrolyte may vaporize and explode due to a spark generated when a short circuit occurs due to the remaining voltage.

[0085] In one embodiment, the step of freezing the battery is a battery processing method that satisfies the following equation 7.

[0086] [Formula 6]

[0087] Minimum cooling time (Hr) = A × (W 0.33 )

[0088] (A = 4 × e(-0.02×dT), W = battery weight (Kg), dT= │external cooling temperature - target temperature│, ││ represents the absolute value)

[0089] In one embodiment, the step of freezing the battery may include a step of cooling the battery to -150° C. to -20° C. In one embodiment, the step of preparing the battery may include a step of performing a forced discharge.

[0090] The step of shredding the battery may utilize a shredder to obtain shredded material. Non-limiting examples of the shredding may include physically or mechanically crushing the waste battery and crushing the waste battery into fine powder. The shredding step may separate some large impurities, such as aluminum (Al), copper (Cu), iron (Fe), and plastic, from the components contained in the waste battery. The state in which the large impurities are separated is called black powder, and the shredding step may produce battery shredded material such as black powder.

[0091] In one embodiment, the battery shredder may include aluminum (Al), manganese (Mn), lithium (Li), copper (Cu), cobalt (Co), nickel (Ni), carbon (C) and residual impurities. In one embodiment, the black powder includes 5 to 40 wt% of nickel (Ni), 1 to 20 wt% of cobalt (Co), 1 to 15 wt% of manganese (Mn), 0.5 to 5 wt% of lithium (Li), 10 to 70 wt% of carbon (C), 0.0001 to 20 wt% of aluminum (Al), and 0.0001 to 20 wt% of copper (Cu), and the sum of impurities such as iron (Fe) and phosphorus (P) may be less than 10 wt%. The components of the above black powder may vary depending on the ratio of nickel, cobalt, and manganese, and the nickel, cobalt, and manganese may be controlled by the positive electrode oxide in the lithium secondary battery when the lithium secondary battery is crushed.

[0092] In one embodiment, the step of crushing the battery may be a crushing method using at least one of shear, compression, and tensile force. Specifically, the crushing step may be performed by, for example, at least one of a hammer mill, a ball mill, and a stirred ball mill. The hammer mill may perform at least one of disintegration, punching, and milling, and it is clear that the crushing may be performed using various types of crushing or crushing devices, for example, an industrial crusher, as a non-limiting example. In one embodiment, the particle size of the battery crushed material may be within 50 mm, specifically, within 30 mm. If the particle size is larger than the above range, there is an uneconomical problem because more energy is required in the heat treatment step described below.

[0093] The step of heat-treating the shredded battery waste at a temperature ranging from 600 to 1,500°C may be a step of dry heat-treating the battery waste. Specifically, the heat-treating step may include placing the shredded battery into a heating furnace capable of raising the temperature to a temperature higher than the melting point of the shredded battery. The step of dry heat-treating the shredded battery (S200) may involve heat-treating conditions that perform a high-temperature reduction reaction without going through a melting step.

[0094] In one embodiment, the heat treatment conditions may involve heat treatment conditions in the range of 900 to 1,800°C. Specifically, the range may be performed in the range of 1,200 to 1,800°C, and more specifically, 1,300 to 1,700°C. If the upper limit of the range is exceeded, there is a problem of loss due to lithium vaporization, and if the lower limit of the range is exceeded, there is a problem of sintering and reduction of alloy elements not proceeding. In the above temperature range, the reduction reaction can be performed in a state where carbon in the crushed material is minimally burned and carbon dioxide generation is almost non-existent.

[0095] In one embodiment, the step (S200) of dry heat treating the shredded material may be performed in a gas atmosphere of at least one of an inert gas, carbon dioxide, carbon monoxide, and a hydrocarbon gas. The inert gas may include, for example, at least one of argon and nitrogen. By performing the reduction reaction of the shredded material in the gas atmosphere, a valuable metal recovery alloy comprising the valuable metal contained in the shredded material as a component can be effectively recovered.

[0096] In one embodiment, a portion of the gaseous atmosphere may contain impurities containing residual oxygen. If the oxygen content among the impurities is high, it may combine with the components of the shredded material during the reduction reaction to form carbon dioxide, which may then be gasified together with the lithium, making recovery difficult.

[0097] In one embodiment, the average oxygen partial pressure in the dry heat treatment step may be in the range of 0.01 to 1 atm. Specifically, if the oxygen partial pressure is higher than the above value, there is a problem of lithium loss and large amounts of carbon dioxide being generated in local high-temperature conditions. If the oxygen partial pressure is lower than the lower limit of the above range, there is a problem of reduced Li recovery rate due to the inferiority of LiAlO2 production.

[0098] Specifically, in the dry heat treatment step, a valuable metal recovery composition is provided by alloying components such as nickel, cobalt, manganese, and lithium-containing oxides in the crushed material, which may include valuable metals and residual impurities. The valuable metal recovery composition may include, for example, aluminum (Al), manganese (Mn), lithium (Li), copper (Cu), cobalt (Co), nickel (Ni), carbon (C), and residual impurities. Specifically, the valuable metal recovery composition may include a valuable metal recovery alloy and a lithium compound. Specifically, the valuable metal recovery composition may include a valuable metal alloy, a lithium compound, copper (Cu), and graphite.

[0099] The above-mentioned valuable metal recovery alloy may include 45 wt% or more of valuable metal and the remainder being impurities, based on 100 wt% of the total composition of the alloy. The above-mentioned valuable metal recovery alloy may include at least one of valuable metals such as nickel (Ni), cobalt (Co), manganese (Mn), lithium (Li), carbon (C), aluminum (Al), and copper (Cu) and the remainder being impurities. In the present specification, the valuable metal may mean an expensive metal component included in a battery, and may mean nickel, cobalt, manganese, aluminum, copper, and lithium. In one embodiment, the valuable metal may be 70 wt% or more.

[0100] In one embodiment, lithium (Li) among the above-mentioned valuable metals may be included in a range of 0.01 to 5 wt%. By satisfying the above-mentioned range, there is an advantage in that the Li recovery rate can be maximized during the Li refining process. If the lithium content exceeds the upper limit of the above-mentioned range, there is a problem of reduced Ni and Co recovery rates, and if the lithium content exceeds the lower limit of the above-mentioned range, there is a problem of increased process costs due to a reduced Li recovery rate during the Li refining process.

[0101] In one embodiment, the precious metal recovery alloy may contain copper (Cu) in an amount of 0.02 wt% or more. Specifically, the precious metal recovery alloy may contain copper in a range of 0.1 to 15 wt%. If the content of the copper is outside the upper limit of the range, there is a problem of process cost due to an increase in the amount of CuSO4 precipitated in leaching and solvent extraction, and if the content of the copper is outside the lower limit of the range, there is a problem of an increase in the amount of unreacted material due to difficulty in producing low-melting-point Ni-Co-Mn.

[0102] In one embodiment, the copper may be combined with nickel (Ni) among the valuable metals to form an alloy. In one embodiment, the nickel may be included in an amount ranging from 5 to 40 wt%. When the nickel is outside the upper limit of the above range, there is a problem of a decrease in the leaching rate due to the formation of nickel carbide (Ni3C), and when the nickel is outside the lower limit of the above range, there is a problem of a decrease in the Ni recovery rate in leaching and solvent extraction.

[0103] In one embodiment, the valuable metal recovery alloy may contain graphite in an amount of 7 wt% or less. Specifically, the graphite content may be 1 to 6 wt%, and more specifically, 2 to 5 wt%. By ensuring that the graphite content in the valuable metal recovery alloy satisfies the aforementioned range, the leaching efficiency may be improved due to a reduced graphite content during acid leaching, and the recovery of the graphite may reduce CO2 emissions.

[0104] If the upper limit of the above range is exceeded, the negative electrode material remains unreacted, preventing proper alloying and leaving valuable metal oxides within the positive electrode material. If the lower limit of the above range is exceeded, there is a risk of lithium loss due to high temperatures.

[0105] In one embodiment, the valuable metal recovery alloy may contain aluminum (Al) in a range of 0.25 to 30 wt%. If the content of aluminum is outside the upper limit of the range, there is a problem of reduced Ni and Co recovery rates during the leaching and solvent extraction processes, and if the content of aluminum is outside the lower limit of the range, there is a problem of reduced Li recovery rates due to difficulty in producing LiAlO2.

[0106] The content of the valuable metal in the above-mentioned valuable metal recovery composition may include 45 wt%. Specifically, the valuable metal recovery composition may include nickel as a basic component, but may also include materials such as cobalt, manganese, copper, aluminum, and lithium.

[0107] In one embodiment, the lithium content in the composition may be in the range of 0.1 to 10 wt%. Specifically, the lithium content in the composition may be in the range of 8 to 10 wt%.

[0108] The lithium content in the composition may include not only the content of the valuable metal recovery alloy, but also the content of lithium contained in the lithium compound. If the upper limit of the above range is exceeded, there is a problem in that lithium is lost through a process in which oxygen burns carbon rather than an oxygen-free reaction, making it impossible to recover lithium among the expensive valuable metals in the battery. If the lower limit of the above range is exceeded, there is a problem in that the recovery rate of the valuable metal is reduced.

[0109] The lithium compound may be a precious metal reactant including a lithium compound including at least one of LiAlO2, Li5AlO4, LiAl5O8, Li2CO3, LiF, Li3PO4, Li4P2O7, LiPO3, Li2SiO3, Li4SiO4, Li2Si2O5, LiFeO2, LiFe5O8, Li3Fe5O8, and Li5FeO4, wherein the content of Li in the compound may be 4 to 35% based on the total 100% by weight. In one embodiment, at least a portion of the lithium compound may be disposed on the precious metal alloy. Specifically, at least a portion of the lithium compound may be combined into a compound by physically or chemically bonding lithium and aluminum included in the composition to each other.

[0110] For example, when recovering valuable metals from a spent battery, the valuable metals in the spent battery exist in the form of oxides, and reduction occurs by graphite in the negative electrode material at the process temperature and oxygen atmosphere of the present invention described below. At this time, the copper in the current collector may melt and exist in a liquid state, and may play a role in agglomerating the reduced valuable metals. The aluminum in the current collector and other current collectors may participate in a partial reduction reaction with the positive electrode oxide, and the remainder may react with lithium and remain as lithium-aluminum oxide. Specifically, the composition for recovering valuable metals may include a lithium compound, and the lithium compound may be manufactured by the reduction reaction. For example, the lithium compound may be lithium-aluminate (2LiAlO2).

[0111] The above graphite may be composed of a graphite material having a graphitization degree of 50% or more and a total weight ratio of 70% or more.

[0112] The step of separating graphite from the composition for recovering valuable metals above may result in the loss of powder containing a valuable metal alloy containing sulfuric acid and nickel that does not dissolve during sulfuric acid leaching, has hydrophobic characteristics, and floats between graphite particles. To prevent this, a step of removing graphite from the composition for recovering valuable metals above may be performed in advance.

[0113] In one embodiment, the step of separating graphite from the composition for recovering valuable metals may be performed through at least one of particle size separation, gravity separation, and flotation.

[0114] The step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid can be performed at a pH of the sulfuric acid aqueous solution containing lithium of 0.2 to 4.0, specifically 0.5 to 3.0, and more specifically 0.8 to 2.0. When the pH satisfies the above range, the selective leaching of Li has an excellent advantage.

[0115] If the pH exceeds the upper limit of the aforementioned range, there is a problem of delayed lithium leaching, resulting in a decrease in lithium recovery. If the pH exceeds the lower limit of the aforementioned range, there is a problem of excessive leaching of valuable metals and copper.

[0116] The step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering valuable metals with sulfuric acid may be performed at an equivalent ratio of the sulfuric acid of 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 satisfies the above range, the leaching rate of the valuable metal recovery alloy can be increased while minimizing the content of sulfuric acid.

[0117] If the equivalent ratio of the 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 the sulfuric acid exceeds the lower limit of the aforementioned range, there is a problem of delayed leaching of lithium, resulting in a decrease in the lithium recovery rate.

[0118] In the step of leaching the above-mentioned valuable metal recovery alloy with sulfuric acid, the temperature at which the process is performed may be 10 to 150°C, specifically 20 to 120°C, and more specifically 40 to 90°C. When the temperature at which the process is performed satisfies the above range, the phenomenon of the sulfuric acid boiling over is suppressed, while the leaching efficiency is excellent.

[0119] If the above-mentioned operating temperature exceeds the upper limit of the above-mentioned range, there is a problem of excessive leaching of valuable metals and copper. If the above-mentioned operating temperature exceeds the lower limit of the above-mentioned range, there is a problem of delayed lithium leaching, resulting in a decrease in the lithium recovery rate.

[0120] The step of leaching the above valuable metal recovery alloy, lithium compound and Cu with sulfuric acid is performed using an inert gas at a rate of 0.1 to 20.0 Nm 3 / hr, specifically 1 to 15 Nm 3 / hr, more specifically 3 to 8 Nm 3 / hr. The inert gas may be nitrogen, argon, helium, etc. When the oxygen is supplied within the above-mentioned supply rate range, the selective leaching rate of Li can be accelerated during the process of leaching the valuable metal recovery alloy.

[0121] If the supply rate of the gas exceeds the upper limit of the aforementioned range, there is a problem of excessive leaching of valuable metals and copper. If the supply rate of the gas exceeds the lower limit of the aforementioned range, there is a problem of delayed leaching of lithium, resulting in a decrease in the lithium recovery rate.

[0122]

[0123] The step of recovering the valuable metal and the copper (Cu) by separating the solid and liquid in the sulfuric acid aqueous solution containing the leached lithium is such that the sulfuric acid aqueous solution containing the leached lithium is separated in a liquid phase, and the valuable metal and the copper (Cu) can be separated in a solid phase.

[0124] In one embodiment, the step of recovering the valuable metal and copper (Cu) by solid-liquid separation in a sulfuric acid solution containing leached lithium may include a magnetic separation step for separating the valuable metal and Cu after the solid-liquid separation. By further including a magnetic separation step after the solid-liquid separation step, copper can be recovered more easily.

[0125] In one embodiment, the method may include a step of removing impurities in the sulfuric acid aqueous solution containing lithium by adding sodium hydroxide (NaOH) between the step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid and the step of recovering the valuable metal and the copper (Cu) by solid-liquid separation in the sulfuric acid aqueous solution containing the leached lithium.

[0126] In one embodiment, the step of removing impurities in the sulfuric acid aqueous solution may control the pH of the sulfuric acid aqueous solution to 3.0 to 8.0. Specifically, the pH may be 4.0 to 7.0. The step of removing impurities in the sulfuric acid aqueous solution may be a step for removing impurities in the sulfuric acid aqueous solution before performing a solid-liquid separation process to produce a sulfuric acid aqueous solution containing a high concentration of lithium. Specifically, the impurities may include at least one element selected from the group consisting of Ni, Co, Mn, Cu, Ti, Zn, Pb, P, Ca, Mg, B, K, Na, Si, and Fe.

[0127] The step of removing residual impurities in the sulfuric acid aqueous solution containing the leached lithium that has gone through the recovery step can remove residual impurities in the sulfuric acid aqueous solution containing the recovered lithium through solid-liquid separation, for example, elements such as Mg or Ca.

[0128] In one embodiment, the step of removing residual impurities of the sulfuric acid aqueous solution containing the leached lithium that has undergone the recovery step may adjust the pH of the sulfuric acid aqueous solution containing lithium to a range of 8.5 to 12.0. Specifically, the pH may be 9.0 to 11.0. By satisfying the above-described pH range, residual impurities such as Ca and Mg in the lithium sulfate can be easily removed, thereby providing a sulfuric acid aqueous solution containing lithium with a high lithium concentration.

[0129] In one embodiment, the step of recovering the valuable metal and the copper (Cu) by solid-liquid separation in the sulfuric acid aqueous solution containing the leached lithium and the step of removing the residual impurities in the sulfuric acid aqueous solution containing the leached lithium that has undergone the recovery step may include a step of removing impurities by an ion exchange method.

[0130] The step of removing impurities by the above ion exchange method may be a step of removing elements such as Zr, T, B, or F remaining in small amounts in the sulfuric acid solution containing lithium recovered by solid-liquid separation.

[0131] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and the present invention is not limited thereto, and the present invention is defined solely by the scope of the claims set forth below.

[0132] <Experimental Example>

[0133] Preparation of a composition for the recovery of valuable metals

[0134] <Battery internal temperature according to minimum freezing time>

[0135] The battery pack used in the examples was shredded without refrigeration using the same shredder as in the examples. During the shredding process, a flame occurred due to a short circuit, as shown in Figures 3a and 3b. The battery used in this case was a 622NCM battery.

[0136] In this way, through examples and comparative examples, it can be confirmed that by including a step of freezing a battery pack including the battery before crushing the battery, no short circuit occurs and no flame is generated in the battery crushing step, resulting in excellent stability.

[0137] Figure 1 shows the change in voltage of a battery according to cooling temperature according to one embodiment of the present invention.

[0138] Referring to Fig. 1, when the battery is frozen to -80°C and the battery voltage is measured, the battery pack shows almost the same voltage at a high temperature of about 40°C, room temperature, and up to -60°C, confirming that the battery characteristics are not lost. Next, when the temperature decreases from -60°C to -70°C, the voltage drops rapidly, and below -70°C, the voltage becomes 0. In this way, it was confirmed that a short circuit does not occur when the battery is frozen to -60 to -150°C.

[0139] FIG. 2 is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0140] Referring to FIG. 2, it can be confirmed that a battery processing method according to one 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.

[0141] More specifically, when the target temperature is set to -70℃ 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. When cooling the battery, it can be confirmed that the electrolyte of the battery begins to cool after a certain period of time and the voltage becomes 0. Through this, it can be confirmed that a minimum maintenance time is required to sufficiently cool the inside, specifically the electrolyte, when cooling the battery.

[0142] Specifically, in a heat transfer situation for cooling where heat is lost to the outside, considering the specific heat of the battery itself, it can be confirmed that the battery weight and cooling time are required. Thus, the present invention can determine the minimum time required for cooling by using the external cooling temperature for refrigeration, the target temperature, and the battery weight.

[0143] Table 1 below lists the minimum cooling time based on battery weight and external cooling temperature.

[0144] Battery weight [kg] External cooling temperature [℃] Target temperature [℃] Formula 2Minimum cooling time [h]A_12.5-120-701.91.9A_22.5-100-702.92.9A_32.5-80-704.44.4B_110-120-703.13.1B_210-100-704.64.6B_310-80-707.07.0C_120-120-703.93.9C_220-100-705.85.8C_320-80-708.88.8D_150-120-705.35.3D_250-100-707.97.9D_350-80-7011.911.9

[0145] Looking at Table 1 above, it can be seen that the smaller the battery weight, the shorter the minimum cooling time required for the battery to be cooled. Furthermore, when the value of Equation 2, derived from the relationship between the battery weight, external cooling temperature, and target temperature, is cooled for the minimum cooling time, it can be confirmed that the battery, specifically the electrolyte of the battery, is cooled. Furthermore, when the battery is cooled for a time longer than the value of Equation 2, no fire occurs during the post-process, that is, the battery crushing process.

[0146] FIGS. 3a and 3b are photographs showing a fire occurring when crushing was performed after freezing for a shorter time than the minimum cooling time according to a comparative example of the present invention, and FIGS. 3c and 3d are photographs showing an example in which a fire did not occur when crushing was performed after freezing for a longer time than the minimum cooling time according to an embodiment of the present invention.

[0147] Referring to Figures 3a and 3b, the fire occurrence status of shredded material was tested when the battery was frozen for a time shorter than the minimum cooling time required for cooling. In the experiment, when the battery weight was 25 kg, the external cooling temperature was -95°C, and the target freezing temperature was -70°C, the experiment was conducted for 5 hours, which is lower than the value of Equation 2, when the value of Equation 2 below was 7 hours.

[0148] <Formula 2>

[0149] Minimum cooling time = A × (W 0.33 )

[0150] (In the above equation 2, A = 4 × e(-0.02×dT), W = battery weight (Kg), dT = │external cooling temperature - target temperature│, ││ represents an absolute value)

[0151] Referring to Figures 3c and 3d, the fire occurrence status of shredded material was tested when the battery was frozen for a period exceeding the minimum freezing time required for cooling. The above experiment was conducted under the same battery weight as Figures 3a and 3b, the external cooling temperature, and the minimum freezing time of 7 hours or more.

[0152] Table 2 below compares the fire occurrence status of the examples and comparative examples according to the same battery weight, external cooling temperature, and minimum freezing time according to 3a to 3d. The fire occurrence status was determined as "O" if fire occurrence was observed after crushing the battery, and "X" if not.

[0153] Battery weight [Kg] External cooling temperature [℃] Target temperature [℃] Formula 2 Actual cooling time [h] Fire occurrence Comparative example 25- 95- 707.05 O Example 25- 95- 707.07 X

[0154] Examining Table 2 above, it can be seen that if the battery is cooled to a value lower than the value in Equation 2, which corresponds to the minimum cooling time, the electrolyte will not be cooled, resulting in a fire after the battery is shredded. Thus, it can be confirmed that if the battery is cooled using the value in Equation 2 as the minimum cooling time, the shredded material can be reliably utilized without a fire after the battery is shredded.

[0155] <Battery shredder calcination heat treatment>

[0156] The step of calcining and heat treating the above-mentioned battery shreds was performed by dry heat treatment under conditions of 5 vol% or less of oxygen in a temperature range of 700 to 1,350°C. Specifically, the calcining heat treatment of this experiment was performed by dry heat treatment in a temperature range of 900 to 1,200°C, specifically about 1,100°C, and under conditions of about 3 vol% or less of oxygen, thereby obtaining a composition for recovering valuable metals.

[0157] At this time, the size of the battery shreds is 10 to 20 mm in length, width, and height as a long axis, the graphite content is 5% or more, and the impurity content of plastic or iron pieces such as Al covers and PCB substrates in the shreds is less than 5%.

[0158] The composition for recovering precious metals manufactured through the above-mentioned sintering heat treatment step is a composition comprising a core part including precious metals and a shell part including a lithium-containing compound disposed on the core part, a precious metal alloy, a lithium compound, copper, and graphite.

[0159]

[0160] <Separation from a composition for the recovery of valuable metals>

[0161] The composition for recovering the precious metal obtained through a high-temperature reduction process was separated into magnetic and non-magnetic substances through a magnetic separator having a magnetic strength of 3000 Gauss.

[0162] Thereafter, the non-magnetic material separated through the magnetic separation was subjected to flotation using Denver Sub_A flotation equipment at a concentration of 30%, an impeller rotation speed of 500 rpm, kerosene 0.1 ml / 100 g, and MIBC 0.1 ml / 100 g. Through the flotation, light graphite powder floated to the top of the column, and this was separated to recover the graphite.

[0163] Through the above flotation process, graphite was separated as a float, and lithium-containing material was separated as a sediment and recovered.

[0164] Afterwards, the magnetic material that has undergone magnetic separation is ground using an Attrition Mill, which is a vertical stirring mill, under the conditions of 500 rpm, impeller tip speed 2.8 m / sec, grinding time 60 minutes, and solid content weight 30%. It was confirmed that the magnetic material, which is composed of a core part including a valuable metal and a shell part including a compound including lithium disposed on the core part, is separated into the core part and the shell part through the grinding process. In order to further separate the alloy core part including the valuable metal and the lithium compound from the resultant product that has gone through the grinding process, the magnetic material and the non-magnetic material are separated using a magnetic separator of 3000 Gauss.

[0165] Afterwards, particle size separation was performed using a mesh having a mesh size of 75 ㎛ to recover coarse particles of NCM alloy and fine particles of Li oxide.

[0166] The valuable metal-containing alloy, lithium compound, and Cu were obtained through the magnetic separation, flotation separation, and particle size separation described above.

[0167]

[0168] <Selective leaching step of lithium>

[0169] A precious metal-containing alloy, a lithium compound, and Cu were obtained through a high-temperature heat treatment process, and lithium (Li) was selectively leached from the precious metal-containing alloy, the lithium compound, and Cu through sulfuric acid leaching. The leaching of lithium can be explained by the following reaction formulas.

[0170] [Reaction Scheme 1] Ni(s)+H2SO 4(aq) = NiSO 4(aq) +H 2(g) , △G o m = -46.3 (kJ / mol)

[0171] [Reaction Scheme 2] Co(s)+H2SO 4(aq) = CoSO 4(aq) +H 2(g) , △Go m = -54.7 (kJ / mol)

[0172] [Reaction Scheme 3] Li2O(s)+H2SO 4(aq) = Li2SO 4(aq) +H2O (aq) , △G o m = -260.5 (kJ / mol)

[0173] [Reaction Scheme 4] Cu(s)+H2SO 4(aq) = CuSO 4(aq) +H 2(g) , △G o m = 69.5 (kJ / mol)

[0174] According to the above reaction formulas 1 and 2, when Ni and Co are leached in sulfuric acid, the Gibbs Free Energy is -46 to -53 kJ / mol, which is about 20% lower than the Gibbs Free Energy of -260.5 kJ / mol when lithium oxide is leached in sulfuric acid, confirming that the leaching reaction is not accelerated. In the case of Cu, the Gibbs Free Energy is high at 69.5 kJ / mol compared to Ni, Co, and Li, confirming that leaching in sulfuric acid is not easy.

[0175] Lithium-containing alloys and lithium compounds obtained through 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 range of 0.8 to 2.0 M. At this time, the experiment was conducted so that the leaching rate of lithium in the sulfuric acid aqueous solution was 6 g / L, assuming 100%.

[0176] Tables 3 to 5 below show the results of lithium leaching over time when sulfuric acid equivalent ratios were 1.0 M, 1.2 M, and 1.6 M, respectively. Specifically, Table 3 below shows the results of selective Li leaching over time (g / L) (sulfuric acid equivalent ratio = 1.0 M, temperature = 50 ℃), Table 4 below shows the results of selective Li leaching over time (g / L) (sulfuric acid equivalent ratio = 1.2 M, temperature = 50 ℃), and Table 5 below shows the results of selective Li leaching over time (g / L) (sulfuric acid equivalent ratio = 1.6 M, temperature = 50 ℃).

[0177] Time (minutes)LiAlNiCoMnCu0000000304.155.992.190.641.170.11604.897.723.290.961.490.18905.458.643.981.171.680.241205.819.204.461.311.790.28

[0178] Time (minutes)LiAlNiCoMnCu0000000304.185.452.090.611.130.24605.047.853.511.031.5780.31905.428.894.261.251.800.481205.889.744.671.441.970.65

[0179] Time (minutes)LiAlNiCoMnCu0000000304.284.720.760.331.600.31605.177.571.520.591.760.38905.689.062.430.901.930.591205.999.823.551.272.220.81

[0180] Looking at Tables 3 to 5 above, it can be confirmed that when lithium is leached at a temperature of 50°C for less than 120 minutes, a lithium leaching rate of 94 to 99% or more can be secured depending on the sulfuric acid equivalent ratio. In addition, it was confirmed that the leaching concentrations of Ni, Co, and Mn can be controlled to 5 g / L or less, and the leaching concentration of Cu can be controlled to 1 g / L or less at the same time.

[0181] Removal of impurities from lithium-containing sulfuric acid solutions

[0182] The sulfuric acid aqueous solution containing lithium that has undergone the lithium leaching process described above contains impurities of Ni, Co, Mn, Cu, Ti, Zn, Pb, P, Ca, Mg, B, K, Na, Si, and Fe. In order to remove the impurities from the sulfuric acid aqueous solution, an impurity removal process was performed.

[0183] In order to remove impurities in the above sulfuric acid aqueous solution, the lithium-containing sulfuric acid aqueous solution obtained through the sulfuric acid leaching process of the lithium-containing sulfuric acid aqueous solution was adjusted to pH 3.0 to 8.0 by adding sodium hydroxide (NaOH) to the sulfuric acid aqueous solution according to the following reaction formulas 5 and 6. By adjusting the sulfuric acid aqueous solution to the above-mentioned pH range, the impurities of Ni, Co, Mn, Cu, Ti, Zn, Pb, P, Ca, Mg, B, K, Na, Si, and Fe remaining in the sulfuric acid aqueous solution were removed.

[0184] [Reaction Formula 5] Me2(SO4) 3(aq) + 6NaOH = 2Me(OH)3(s)+3Na2SO 4(aq) +H2SO 4(aq)

[0185] (Me = Fe, Al, Ti)

[0186] [Reaction Scheme 6] MeSO 4 (aq) + 2NaOH = Me(OH)2(s)+Na2SO 4(aq) +H2SO 4(aq)

[0187] (Me = Ni, Co, Mn, Cu, Zn, Pb)

[0188]

[0189] High-value separation

[0190] A solid-liquid separation was performed to separate the precipitated material from the sulfuric acid solution from which the aforementioned impurities had been removed. Through the solid-liquid separation, the precipitated material from the sulfuric acid solution was separated, and a high-purity lithium-containing sulfuric acid solution was separated separately.

[0191]

[0192] <Removal of additional impurities>

[0193] Afterwards, a process was performed to remove impurities such as Zr, T, B, and F remaining in small amounts in the separated sulfuric acid solution using an ion exchange method. Afterwards, in order to further remove impurities such as Ca and Mg remaining in the sulfuric acid solution, the pH of the sulfuric acid solution was adjusted to 8.5 to 12.0 to produce a high-purity Ni-containing sulfuric acid solution.

[0194]

[0195] Table 6 below shows the concentration of a lithium-containing sulfuric acid solution that has undergone a lithium leaching step and an impurity removal step.

[0196] Classification (g / L) LiAlNiCoMnCuFeTiCaMgZnPbAfter leaching5.999.823.551.272.220.810.050.020.260.110.0050.004After removing impurities5.900.0030.0010.0010.0020.0020.0010.0010.0040.0030.0010.001

[0197] Looking at Table 6 above, it was confirmed that the lithium-containing sulfuric acid aqueous solution of the present invention has a high lithium concentration and a low impurity concentration, and thus a high-purity sulfuric acid aqueous solution that can be used to manufacture raw materials for lithium secondary batteries, specifically, cathode materials, was produced.

[0198] Table 7 below compares the concentrations of a lithium-containing sulfuric acid aqueous solution of the present invention, a sulfuric acid aqueous solution extracted from spodumene, and a lithium-containing sulfuric acid aqueous solution of a prototype generally used in the manufacture of cathode materials.

[0199] Classification (g / L) LiAlNiCoMnFormula 1 Formulation 2 Formulation 3 Formulation 4 Notes Example 5.999.823.551.272.22OOOO Waste battery extract Comparative example 7.554.80.0040.0060.2XXXX Spodumene extract Comparative example 4.80.521.410.29.7XXXX Black mass (prototype)

[0200] Referring to Table 7 above, it can be confirmed that the lithium-containing sulfuric acid solution recovered from a spent battery, as in the present invention, satisfies Equations 1 to 4, which are the characteristics of the present invention. In contrast, it was confirmed that the sulfuric acid solution extracted through a leaching process from spodumene and the generally recovered black mass prototype did not satisfy Equations 1 to 4, which are the characteristics of the present invention. In addition, the lithium-containing sulfuric acid solution recovered from a spent battery of the present invention has a higher lithium content than the aluminum content compared to the spodumene extract of the comparative example, and thus, the amount of aluminum hydroxide generated during solid-liquid separation is less, which is advantageous for solid-liquid separation. It can be confirmed that the lithium content of the lithium-containing sulfuric acid solution recovered from a spent battery of the present invention is higher than that of the black mass of the comparative example. In addition, since the lithium content is high compared to the Ni, Co, and Mn content in the sulfuric acid solution, there is an advantage in that the loss of Ni, Co, and Mn can be reduced compared to black mass with a high Ni, Co, and Mn content when removing impurities by adding NaOH.

[0201]

[0202] Although the preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts defined in the following claims also fall within the scope of the present invention.

Claims

1. A step of obtaining a composition for recovering valuable metals including a valuable metal alloy, a lithium compound, copper (Cu), and graphite from a spent battery; A step of separating graphite from the composition for recovering valuable metals; A step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid; A step of recovering the valuable metal and the copper (Cu) by solid-liquid separation in a sulfuric acid aqueous solution containing the leached lithium; and A method for producing a sulfuric acid aqueous solution containing lithium, comprising a step of removing residual impurities from a sulfuric acid aqueous solution containing the leached lithium that has undergone a recovery step.

2. In paragraph 1, A method for producing an aqueous sulfuric acid solution containing lithium, wherein at least a portion of the lithium compound is disposed on a metal alloy.

3. In paragraph 1, The step of obtaining a composition for recovering valuable metals comprises: A step for preparing a battery containing lithium (Li); The step of crushing the above battery; A method for producing a lithium-containing sulfuric acid aqueous solution, comprising the step of heat-treating shredded battery waste at a temperature ranging from 600 to 1,500° C.

4. In paragraph 3, A method for producing a lithium-containing sulfuric acid aqueous solution, wherein the step of heat-treating the above-mentioned crushed battery waste at a range of 600 to 1,500° C. is performed at an oxygen concentration range of 0.1 to 2.0 vol%.

5. In paragraph 3, A method for producing a lithium-containing sulfuric acid aqueous solution, wherein the step of separating graphite from the composition for recovering precious metals is performed by at least one of particle size separation, specific gravity separation, and flotation.

6. In paragraph 1, A method for producing a sulfuric acid aqueous solution containing lithium, wherein the step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid controls the pH of the sulfuric acid aqueous solution containing lithium in a range of 0.2 to 4.

0.

7. In paragraph 1, The step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid is a method for producing a sulfuric acid aqueous solution containing lithium having an equivalent ratio of sulfuric acid of 0.5 to 4.

0.

8. In paragraph 1, A method for producing a sulfuric acid aqueous solution containing lithium, wherein the step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal using sulfuric acid is performed at a temperature range of 10 to 150° C.

9. In paragraph 1, The step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid is performed by using an inert gas at a rate of 0.1 to 20.0 Nm 3 A method for producing an aqueous sulfuric acid solution containing lithium supplied at a supply rate of / hr.

10. In paragraph 1, A method for producing a sulfuric acid aqueous solution containing lithium, comprising a step of removing impurities in the sulfuric acid aqueous solution containing lithium by adding sodium hydroxide (NaOH) between the step of leaching the valuable metal, lithium compound, and copper (Cu) in the composition for recovering the valuable metal with sulfuric acid and the step of recovering the valuable metal and the copper (Cu) by solid-liquid separation in the sulfuric acid aqueous solution containing the leached lithium.

11. In clause 10, A method for producing a sulfuric acid aqueous solution containing lithium, wherein the step of removing impurities in the sulfuric acid aqueous solution controls the pH of the sulfuric acid aqueous solution to 3.0 to 8.

0.

12. In paragraph 1, A method for producing a sulfuric acid aqueous solution containing lithium, comprising a step of removing impurities by an ion exchange method between the step of recovering the valuable metal and the copper (Cu) by performing solid-liquid separation in the sulfuric acid aqueous solution containing the leached lithium and the step of removing residual impurities in the sulfuric acid aqueous solution containing the leached lithium that has undergone the recovery step.

13. In paragraph 1, A method for producing a sulfuric acid aqueous solution containing lithium, wherein the step of removing residual impurities of the sulfuric acid aqueous solution containing the lithium that has undergone the above recovery step adjusts the pH of the sulfuric acid aqueous solution containing lithium to a range of 8.5 to 12.

0.

14. In paragraph 3, A method for producing a lithium-containing sulfuric acid aqueous solution, wherein the step of preparing a battery containing the lithium (Li) includes the step of freezing the battery.

15. As recovered from waste batteries, Containing lithium (Li), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), and residual impurities, A sulfuric acid aqueous solution containing lithium satisfying the following equation 1. <Formula 1> <h2 style=";text-align:left;direction:ltr">1.0 ≤ [Al] = 0.0297 × [Li]<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> + 1.3205 × [Li] ±5 ≤ 16.0 (In the above equation 1, [Li] and [Al] represent the concentrations (g / L) of Li and Al in the sulfuric acid solution containing lithium, respectively.) 16. In paragraph 15, A sulfuric acid aqueous solution containing lithium satisfying the following equation 2. <Formula 2> 0.05 ≤ [Ni] = 0.1907 × [Li] 2 - 0.2689 × [Li] ±3 ≤ 16.0 (In the above equation 2, [Li] and [Ni] represent the concentrations (g / L) of Li and Ni in the sulfuric acid solution containing lithium, respectively.) 17. In paragraph 15, A sulfuric acid aqueous solution containing lithium satisfying the following equation 3. <Formula 3> 0.05 ≤ [Co] = 0.0624 × [Li] 2 - 0.1078 × [Li] ±2 ≤ 14.0 (In the above equation 3, [Li] and [Co] represent the concentrations (g / L) of Li and Co in the sulfuric acid solution containing lithium, respectively.) 18. In paragraph 15, A sulfuric acid aqueous solution containing lithium satisfying the following equation 4. <Formula 4> <h2 style=";text-align:left;direction:ltr">0.1 ≤ [Mn] = 0.0402 × [Li]<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> + 0.117 × [Li] ±1 ≤ 12.0 (In the above equation 4, [Li] and [Mn] represent the concentrations (g / L) of Li and Mn in the sulfuric acid solution containing lithium, respectively.)

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