Method for Moisture Reduction of Fe / Al Residue Generated from Waste Lithium-Ion Battery Recycling Process and Fe / Al Residue Produced Thereby

Abstract

The present invention relates to a method for reducing the moisture content of Fe / Al residues generated in a waste lithium secondary battery recycling process and to Fe / Al residues produced thereby. More specifically, the invention relates to a method for producing Fe / Al residues with a moisture content of 50% by weight or less by applying a caustic soda slurry, prepared by diluting caustic soda with a solution containing a metal salt, to a valuable metal leaching solution to neutralize, precipitate, and wash away Fe and Al components.

Description

Technology Field

[0001] The present invention relates to a method for reducing the moisture content of Fe / Al residues generated in a waste lithium secondary battery recycling process and to Fe / Al residues produced thereby. More specifically, the invention relates to a method for producing Fe / Al residues with a moisture content of 50% by weight or less by applying a caustic soda slurry, prepared by diluting caustic soda with a solution containing a metal salt, to a valuable metal leaching solution to neutralize, precipitate, and wash away Fe and Al components. Background Technology

[0002] Recently, the volume of spent lithium-ion batteries has been rapidly increasing due to the proliferation of electric vehicles and energy storage systems (ESS). Consequently, the importance of recycling technologies to recover valuable metals such as lithium, nickel, cobalt, and manganese from spent lithium-ion batteries is growing. Generally, the recycling process for spent secondary batteries involves crushing and separation steps to separate the active material, followed by leaching with acid to obtain a leachate containing dissolved metal ions. This leachate contains large amounts of impurities, such as iron (Fe) and aluminum (Al), in addition to the valuable metals targeted for recovery, and these impurities reduce the efficiency of subsequent purification processes.

[0003] To address this, conventional technology has widely used methods to remove Fe and Al in the leachate by precipitating them in the form of hydroxides using caustic soda (NaOH) or sodium carbonate (Na2CO3). However, when such precipitation methods are applied, there is a problem in that the moisture content of the process sludge (Fe / Al residue) generated after impurity removal is high, exceeding 50% by weight. When the moisture content of the residue is excessively high, filtration efficiency is reduced, leading to lower treatment efficiency and increased loss of valuable metals during filtration. Consequently, the amount of residue generated increases, raising both treatment and transportation costs. Furthermore, sludge with high moisture content consumes more energy during drying and subsequent landfill processes, which reduces economic viability.

[0004] To solve the above-mentioned problems, the applicant examined a method to more efficiently remove Fe and Al components from the leachate of spent lithium-ion batteries. As a result, it was confirmed that using a slurry in which caustic soda is diluted with a solution containing metal salts, instead of using ordinary water (pure water or industrial water) to dilute caustic soda, significantly improves the particle aggregation and dewatering properties of Fe and Al precipitates. Through this, not only are Fe and Al components stably removed, but the moisture content of the process sludge can be significantly reduced, and at the same time, the leaching loss of valuable metals can be minimized. Prior art literature

[0005] Republic of Korea Registered Patent No. 10-1648693 (Patent Registration Date: August 9, 2016) The problem to be solved

[0006] Accordingly, the objective of the present invention is to provide a method that can significantly reduce the moisture content of the Fe / Al residue, which is process sludge, by efficiently removing Fe and Al components through the application of a caustic soda slurry diluted with a solution containing metal salts to the leachate generated in the waste lithium secondary battery recycling process.

[0007] Furthermore, the objective of the present invention is to provide a technology that can increase the economic efficiency of the entire process by improving the metal recovery efficiency during the process and improving the filterability and dewaterability of the residue.

[0008] In addition, the objective of the present invention is to provide a technology that allows the Fe / Al residue produced through the above method to maintain a moisture content of 50% by weight or less while exhibiting a stable solid form, thereby reducing transportation and drying costs during disposal or recycling.

[0009] Furthermore, the objective of the present invention is to optimize reaction conditions such as metal salt concentration, pH, and temperature to control the physical properties (particle size, density, etc.) of Fe / Al residues generated during the process, and to realize a recycling system with excellent environmental and industrial applicability.

[0010] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0011] In order to solve the above problem, according to one aspect of the present invention,

[0012] Characterized by producing an Fe / Al residue with reduced moisture content by applying a caustic soda slurry diluted with a metal salt solution to the leachate generated in the waste lithium secondary battery recycling process to neutralize, precipitate, and wash Fe and Al components.

[0013] A method is provided to reduce the moisture content of Fe / Al residues generated during the recycling process of spent lithium-ion batteries.

[0014] The solution containing the metal salt may be an aqueous solution of one or more metal salts selected from the group consisting of nickel salts, manganese salts, cobalt salts, and alkaline earth metal salts.

[0015] The concentration of the metal salt in the solution containing the above metal salt may be 3 to 60 g / L.

[0016] The above caustic soda slurry can be prepared by mixing a 33% by weight caustic soda solution and a solution containing the metal salt in a ratio of 1:1 to 5.

[0017] The process of neutralizing and precipitating the above Fe and Al components can be carried out by adding the above caustic soda slurry to the above leachate to control the neutralization conditions to pH 5~6 and temperature 50~90℃, thereby precipitating the Fe and Al components in the above leachate in the form of hydroxides.

[0018] The above leachate and caustic soda slurry can be mixed in a solid-to-liquid ratio of 1:1 to 5.

[0019] The process of cleaning the above Fe and Al components can be performed by adjusting the pH to 1.0 to 2.5 using acid, and then reintroducing a caustic soda slurry to re-neutralize it under conditions of pH 3.5 to 4.5 and a temperature of 50 to 90°C.

[0020] The above Fe / Al sludge and solution can be mixed in a solid-to-liquid ratio of 1:1 to 5.

[0021] After the above cleaning process, additional washing and solid-liquid separation processes may be performed.

[0022] The moisture content of the Fe / Al residue produced by the above method may be 50 weight% or less.

[0023] In addition, according to another aspect of the present invention,

[0024] (a) a step of preparing a caustic soda slurry by diluting caustic soda with a solution containing a metal salt;

[0025] (b) a step of producing Fe / Al sludge by adding the caustic soda slurry to the leaching solution obtained by leaching valuable metals from spent lithium secondary batteries;

[0026] (c) a step of mixing the above Fe / Al sludge with a solution, adjusting the pH using an acid, and then reintroducing the above caustic soda slurry to produce an Fe / Al washing residue; and

[0027] (d) a step of mixing the above Fe / Al washing residue with a solution and washing to produce Fe / Al residue with reduced moisture content; characterized by including

[0028] A method is provided to reduce the moisture content of Fe / Al residues generated during the recycling process of spent lithium-ion batteries.

[0029] The solution containing the above metal salt may be an aqueous solution of a metal salt containing nickel salt, manganese salt, cobalt salt, or alkaline earth metal salt.

[0030] The concentration of the metal salt in the solution containing the above metal salt may be 3 to 60 g / L.

[0031] In step (a) above, the caustic soda slurry can be prepared by mixing a 33% by weight caustic soda solution and a solution containing a metal salt in a ratio of 1:1 to 5.

[0032] In step (b) above, Fe / Al sludge can be produced by adding the caustic soda slurry to the leachate to adjust the neutralization conditions to pH 5~6 and temperature 50~90℃, thereby precipitating Fe and Al components in the leachate in the form of hydroxides.

[0033] In step (b) above, the leaching liquid and the caustic soda slurry may be mixed in a solid-to-liquid ratio of 1:1 to 5.

[0034] In step (b) above, before proceeding to step (c), the Fe / Al sludge can be filtered to separate solids and liquids.

[0035] In step (c) above, the cleaning process can produce Fe / Al cleaning residue by adjusting the pH to 1.0 to 2.5 using acid, then reintroducing a caustic soda slurry and reacting it under conditions of pH 3.5 to 4.5 and a temperature of 50 to 90°C to re-neutralize it.

[0036] In step (c) above, the Fe / Al sludge and the solution may be mixed in a solid-to-liquid ratio of 1:1 to 5.

[0037] In step (c) above, before proceeding to step (d), the Fe / Al washing residue can be filtered to separate solids and liquids.

[0038] In step (d) above, the Fe / Al cleaning residue and the solution may be mixed in a solid-to-liquid ratio of 1:1 to 5.

[0039] In step (d) above, the washing process can be performed by stirring for 10 to 30 minutes under conditions of a temperature of 50 to 90°C.

[0040] In step (d) above, after washing is completed, solid-liquid separation can be performed using a filter press or a centrifuge.

[0041] The moisture content of the Fe / Al residue produced by the above method may be 50 weight% or less.

[0042] In addition, according to another aspect of the present invention,

[0043] The present invention provides an Fe / Al residue containing Fe and Al, having a moisture content of 50 weight% or less, which can be manufactured by the above method. Effects of the invention

[0044] According to the present invention, the moisture content of Fe / Al residue, which is process sludge generated during the recycling process of waste lithium secondary batteries, can be reduced by about 10% by weight or more compared to conventional methods and significantly reduced to a level of 50% by weight or less.

[0045] In addition, according to the present invention, by precisely controlling pH and temperature conditions, it is possible to provide the effect of increasing the recovery rate of valuable metals such as lithium, nickel, cobalt, and manganese while improving the impurity removal efficiency.

[0046] In addition, the Fe / Al residue produced by the present invention exhibits excellent filtration and drying properties, which can significantly reduce energy consumption during dewatering and transportation processes. Consequently, the low-moisture residue has a reduced volume, which decreases the amount of process sludge generated and reduces disposal or recycling costs.

[0047] In addition, the application of a caustic soda slurry using a metal salt solution induces the aggregation of fine particles within the sludge, thereby minimizing clogging of the filtration membrane and increasing the efficiency of the solid-liquid separation process. Consequently, the operational stability of the equipment is improved, and it becomes easier to expand to a continuous processing process.

[0048] In addition, the method of the present invention is highly economical as it does not require separate additives or expensive coagulants, has a low environmental burden, and the residue discharged from the process has low moisture and heavy metal content, allowing it to be safely disposed of even during subsequent drying or landfill processes.

[0049] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims. Brief explanation of the drawing

[0050] FIG. 1 is an overall process flow diagram of a method for reducing Fe / Al residue moisture content in a waste lithium secondary battery recycling process according to one embodiment of the present invention. Figure 2 is a graph comparing the change in moisture content of Fe / Al residues according to the concentration of a solution containing a metal salt according to one embodiment of the present invention. Figure 3 is a graph showing the XRD analysis results according to the difference in moisture content of Fe / Al residues according to one embodiment of the present invention. Specific details for implementing the invention

[0051] Preferred embodiments according to the present invention will be described in detail below with reference to the attached drawings.

[0052] The advantages and features of the present invention and the method for achieving them will become clear by referring to the embodiments described in detail below together with the accompanying drawings.

[0053] However, the present invention is not limited by the embodiments disclosed below but may be implemented in various different forms, and these embodiments are provided merely to make the disclosure of the present invention complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0054] In addition, in describing the present invention, if it is determined that related known technologies, etc., may obscure the essence of the present invention, a detailed explanation thereof will be omitted.

[0055] The present invention will be described in detail below.

[0056] The present invention relates to a method for reducing the moisture content of Fe / Al residues generated in a waste lithium secondary battery recycling process.

[0057] The method is characterized by producing Fe / Al residue with reduced moisture content by applying a caustic soda slurry diluted with a metal salt solution to the leachate generated in the waste lithium secondary battery recycling process to neutralize, precipitate, and wash Fe and Al components.

[0058] The method according to the present invention relates to a method for reducing the moisture content of Fe / Al residue (process sludge) generated during the post-treatment step of a valuable metal leaching solution in a waste lithium secondary battery recycling process.

[0059] More specifically, by diluting caustic soda using a solution containing metal salts instead of ordinary water, the aggregation of Fe / Al residue (or sludge) particles generated during the neutralization and precipitation process is improved, and accordingly, the moisture content of the residue can be significantly reduced.

[0060] The present invention relates to a method for reducing the moisture content of Fe / Al residues generated in a waste lithium secondary battery recycling process.

[0061] (a) a step of preparing a caustic soda slurry by diluting caustic soda with a solution containing a metal salt;

[0062] (b) a step of producing Fe / Al sludge by adding the caustic soda slurry to the leaching solution obtained by leaching valuable metals from spent lithium secondary batteries;

[0063] (c) a step of mixing the above Fe / Al sludge with a solution, adjusting the pH using an acid, and then reintroducing the above caustic soda slurry to produce an Fe / Al washing residue; and

[0064] (d) a step of mixing the above Fe / Al washing residue with a solution and washing to produce Fe / Al residue with reduced moisture content; characterized by including

[0065] FIG. 1 is an overall process flow diagram of a method for reducing the moisture content of Fe / Al residue in a waste lithium secondary battery recycling process according to the present invention. Hereinafter, each step of the method according to the present invention will be described in detail with reference to FIG. 1.

[0066] (a) A step of preparing a caustic soda slurry by diluting caustic soda with a solution containing a metal salt.

[0067] In one embodiment of the present invention, the caustic soda slurry is a slurry containing metal hydroxide (M-OH) particles generated by mixing a solution containing a metal salt with a caustic soda solution, wherein the metal ions (M 2+ ) this hydroxide ion (OH - It reacts with ) and exists in the form of M(OH)2, and by using this M-OH slurry, the neutralization, precipitation, and coagulation dewatering of Fe and Al components can be improved in the next step (b).

[0068] In one embodiment of the present invention, by diluting caustic soda with a solution containing the metal salt instead of ordinary water, Na during the reaction + In addition to ions, there are multivalent cations (M 2+ ) coexist to effectively neutralize the surface charge of sludge particles, and as a result, the inter-particle aggregation and dewatering properties of the precipitate can be improved.

[0069] The solution containing the above metal salt may be an aqueous solution of one or more metal salts selected from the group consisting of nickel salts, manganese salts, cobalt salts, and alkaline earth metal salts, and specifically, it is preferable to use nickel sulfate (NiSO4), cobalt sulfate (CoSO4), manganese sulfate (MnSO4), magnesium chloride (MgCl2), etc.

[0070] The concentration of the metal salt in the solution containing the above metal salt is preferably 3 to 60 g / L, and more preferably 10 to 30 g / L. At this time, if the concentration of the metal salt is excessively low, the ion correction effect is weak and does not contribute to the aggregation of sludge particles, and if it exceeds 60 g / L, the viscosity of the solution increases and the homogeneity of the reaction system decreases, which may actually worsen dewatering performance.

[0071] The above caustic soda slurry is preferably prepared by mixing a 33 wt% caustic soda solution and a solution containing the metal salt in a ratio of 1:1 to 5. At this time, if the mixing ratio is less than 1:1, the concentration of caustic soda becomes excessively high, causing a rapid increase in the sedimentation rate and raising concerns that the flocculation structure of the sludge may become non-uniform. On the other hand, if it exceeds 1:5, the dilution effect becomes excessive, which may reduce the reaction activity. Therefore, the mixing ratio within the above range is set by considering the balance between the ease of pH control and the flocculation efficiency of sludge particles.

[0072] (b) a step of producing Fe / Al sludge by adding the caustic soda slurry to the leaching solution obtained by leaching valuable metals from spent lithium secondary batteries.

[0073] In one embodiment of the present invention, by applying a caustic soda slurry diluted with a metal salt solution to a leachate, a polyvalent cation (M) in the reaction system 2+ This can work together with the process of forming hydroxide of Fe and Al ions to improve the cohesiveness of precipitated particles, and consequently, improve the filtration and dewatering properties of the resulting Fe / Al sludge.

[0074] The above leaching solution is a solution obtained by leaching black powder separated from spent lithium secondary batteries with an acidic solution such as sulfuric acid or hydrochloric acid, and may contain at least 1 g / L each of iron (Fe) and / or aluminum (Al), which are subject to precipitation removal according to the present invention, in addition to valuable metals such as lithium (Li), nickel (Ni), cobalt (Co), and manganese (Mn).

[0075] In one embodiment of the present invention, Fe / Al sludge can be produced by introducing the caustic soda slurry into the leaching solution to control neutralization conditions of pH 5 to 6 and temperature 50 to 90°C, thereby precipitating Fe and Al ions in the leaching solution in the form of hydroxides. In this process, polyvalent cations derived from metal salts are co-adsorbed onto the surface of the sludge particles, thereby improving the cohesive force between particles, and the resulting precipitate has excellent filtration properties.

[0076] It is preferable that the above leachate and caustic soda slurry be mixed in a solid-to-liquid ratio of 1:1 to 5. At this time, if the solid-to-liquid ratio is too low (less than 1:1), excessive heat of reaction is generated, making pH control difficult, and if it is too high (more than 1:5), the precipitation reaction may proceed unevenly.

[0077] In one embodiment of the present invention, before proceeding to step (c), the Fe / Al sludge is filtered to separate solids and liquids, thereby enabling a stable subsequent washing reaction without interference from dissolved ions.

[0078] (c) A step of mixing the above Fe / Al sludge with a solution, adjusting the pH using an acid, and then reintroducing the above caustic soda slurry to produce Fe / Al washing residue.

[0079] In one embodiment of the present invention, the Fe / Al sludge produced in step (b) can be washed and re-neutralized to remove residual metal salts, hydroxides, sulfuric acid residues, etc. inside the sludge.

[0080] In the above cleaning process, metal ions and hydroxides inside the sludge are dissolved by using an acid to adjust the pH to a range of 1.0 to 2.5.

[0081] In this case, inorganic acids such as sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3) can be used, and sulfuric acid is the most economical and has excellent reactivity.

[0082] After cleaning is completed, a caustic soda slurry is reintroduced into the same reaction system to raise the pH to 3.5 to 4.5 and reacted at 50 to 90°C to produce Fe / Al cleaning residue.

[0083] It is preferable that the above Fe / Al sludge and solution be mixed in a solid-to-liquid ratio of 1:1 to 5, and deionized water, recycled washing water, or process circulating water may be used as the solution. Through this two-stage acid washing and re-neutralization treatment, the internal pore structure of the sludge is rearranged and cohesiveness is increased, so that the moisture content after filtration can be significantly reduced.

[0084] In one embodiment of the present invention, it is preferable to remove residual acid and metal salt by filtering the Fe / Al washing residue to separate solids and liquids before proceeding to step (d).

[0085] (d) A step of mixing the above Fe / Al washing residue with a solution and washing to produce Fe / Al residue with reduced moisture content.

[0086] In one embodiment of the present invention, since some acid and metal ions may remain in the residue after cleaning, a washing step is additionally performed to remove them.

[0087] The above Fe / Al cleaning residue can be washed by mixing it with water or diluted water in a solid-to-liquid ratio of 1:1 to 5, and stirring for 10 to 30 minutes at a temperature of 50 to 90°C to remove residual ions.

[0088] At this time, if washing is performed under the above temperature conditions, the surface tension is reduced and the rate of moisture removal is increased, and the hydroxyl-bound water adsorbed on the surface of the sludge is efficiently detached, thereby lowering the final moisture content.

[0089] After washing is completed, solid-liquid separation is performed using a filter press or a centrifuge to obtain Fe / Al residue with a moisture content of 50 weight% or less.

[0090] According to the present invention, the moisture content of the Fe / Al residue produced by the above method may be 50 weight% or less.

[0091] Accordingly, the present invention relates to an Fe / Al residue comprising Fe and Al, having a moisture content of 50 weight% or less, which can be produced by the above method.

[0092] The present invention will be explained in more detail below through examples. However, the following examples are intended to explain the invention more specifically and do not limit the scope of the invention. The following examples may be appropriately modified or changed by those skilled in the art within the scope of the invention.

[0093] Preparation Example 1: Preparation of caustic soda slurry

[0094] 1 L of a 33 wt% caustic soda solution was prepared, and 2 L of a metal salt solution of NiSO430 g / L was mixed to prepare a caustic soda slurry. During mixing, the temperature was maintained at room temperature (25℃) and the stirring speed at 300 rpm, and a uniform slurry was prepared by stirring for about 10 minutes.

[0095] Preparation Example 2: Preparation of caustic soda slurry

[0096] A caustic soda slurry was prepared in the same manner as in Preparation Example 1, except that 5 L of a metal salt solution of NiSO430 g / L was used.

[0097] Preparation Example 3: Preparation of caustic soda slurry

[0098] A caustic soda slurry was prepared in the same manner as in Preparation Example 1, except that 2 L of a metal salt solution of 15 g / L NiSO4 was used.

[0099] Preparation Example 4: Preparation of caustic soda slurry

[0100] A caustic soda slurry was prepared in the same manner as in Preparation Example 1, except that 5 L of a metal salt solution of 15 g / L NiSO4 was used.

[0101] Preparation Example 5: Preparation of caustic soda slurry

[0102] A caustic soda slurry was prepared in the same manner as in Preparation Example 1, except that 2 L of water was used instead of a metal salt solution.

[0103] Preparation Example 6: Preparation of caustic soda slurry

[0104] A caustic soda slurry was prepared in the same manner as in Preparation Example 1, except that 5 L of water was used instead of a metal salt solution.

[0105] Example 1: Preparation of Fe / Al Residue

[0106] A leachate (Al: approximately 3-7 g / L, pH 2) obtained from the leaching process of spent lithium secondary batteries was prepared. Then, the caustic soda slurry of Preparation Example 1 was added to the leachate, the pH was adjusted to 5.5, and a neutralization and precipitation reaction was performed at 50-90°C for 60 minutes. After the reaction, Fe / Al sludge was separated by filtration.

[0107] A slurry was prepared by mixing the separated Fe / Al sludge with water at a solid-to-liquid ratio of 1:1 to 3 to make it into a uniform suspension so that the subsequent acid washing reaction could proceed smoothly, and then the Fe / Al sludge was dissolved by adjusting the pH of the solution to 1.8 to 2.0 using a 70 to 98% sulfuric acid solution.

[0108] The caustic soda slurry of Preparation Example 1 was reintroduced into the same reactor to adjust the pH of the solution to 4.2, and the reaction was further carried out at 50 to 90°C for 60 minutes.

[0109] In this process, metal salts, hydroxides, and other impurities remaining inside the Fe / Al sludge were dissolved and removed.

[0110] Afterwards, the reaction-completed Fe / Al washing residue was mixed with water at a solid-to-liquid ratio of 1:1 to 3, reacted at 50 to 90°C for 60 minutes to wash, and filtered to obtain dehydrated Fe / Al residue.

[0111] At this time, the moisture content was measured to be about 44% by weight.

[0112] Example 2: Preparation of Fe / Al Residue

[0113] Fe / Al residue was obtained in the same manner as in Example 1, except that the caustic soda slurry prepared in Example 2 was used instead of the caustic soda slurry prepared in Example 1.

[0114] At this time, the moisture content was measured to be approximately 53% by weight.

[0115] Example 3: Preparation of Fe / Al Residue

[0116] Fe / Al residue was obtained in the same manner as in Example 1, except that the caustic soda slurry prepared in Example 3 was used instead of the caustic soda slurry prepared in Example 1.

[0117] At this time, the moisture content was measured to be approximately 52% by weight.

[0118] Example 4: Preparation of Fe / Al Residue

[0119] Fe / Al residue was obtained in the same manner as in Example 1, except that the caustic soda slurry prepared in Example 4 was used instead of the caustic soda slurry prepared in Example 1.

[0120] At this time, the moisture content was measured to be approximately 49% by weight.

[0121] Comparative Example 1: Preparation of Fe / Al Residue

[0122] Fe / Al residue was obtained in the same manner as in Example 1, except that the caustic soda slurry prepared in Example 5 was used instead of the caustic soda slurry prepared in Example 1.

[0123] At this time, the moisture content was measured to be about 56% by weight.

[0124] Comparative Example 2: Preparation of Fe / Al Residue

[0125] Fe / Al residue was obtained in the same manner as in Example 1, except that the caustic soda slurry prepared in Example 6 was used instead of the caustic soda slurry prepared in Example 1.

[0126] At this time, the moisture content was measured to be approximately 63% by weight.

[0127] The composition of each caustic soda slurry of Preparation Examples 1 to 6 used in Examples 1 to 4 and Comparative Examples 1 to 2 is shown in Table 1 below, and the change in moisture content of Fe / Al residue according to metal salt solution concentration (0, 15, 30 g / L) and caustic soda slurry dilution ratio (1:2, 1:5) is shown in Table 2 and Figure 2.

[0128] division Caustic soda slurry composition Metal salt concentration (g / L) Dilution ratio (caustic soda:metal salt solution or water) Example 1 Preparation Example 1 30 1:2 Example 2 Preparation Example 2 30 1:2 Example 3 Preparation Example 3 15 1:5 Example 4 Preparation Example 4 15 1:5 Comparative Example 1 Preparation Example 5 0 1:2 Comparative Example 2 Preparation Example 6 0 1:5

[0129] division Moisture content (%) of Fe / Al residue Example 1 44 Example 2 53 Example 3 52 Example 4 49 Comparative Example 1 56 Comparative Example 2 64

[0130] Referring to Table 2 and Figure 2 above, in the case of the comparative example without metal salt added (0 g / L), it was measured to be about 56 wt% under the 1:2 condition and about 64 wt% under the 1:5 condition, confirming that the moisture content was high.

[0131] Meanwhile, in the case of the example using a solution containing a metal salt, it was confirmed that the water content decreased compared to the comparative example. In particular, when the metal salt concentration was 15 g / L, it was about 52 wt% under the 1:2 condition and about 46 wt% under the 1:5 condition, and when the concentration was increased to 30 g / L, the lowest water content was shown at about 44 wt% under the 1:2 condition.

[0132] From this, it was confirmed that the metal salt concentration shows an optimal moisture reduction effect at a level of 30 g / L, and that a dilution ratio of 1:2 is the most efficient condition.

[0133] In addition, when a caustic soda slurry diluted with a solution containing metal salts was applied, the Fe / Al residue exhibited excellent crystal phase stability after undergoing acid washing and re-neutralization steps.

[0134] Accordingly, the process of the present invention provides the technical effect of increasing the removal efficiency of Fe and Al components, while simultaneously reducing the Fe / Al residue in process sludge and improving economical treatment.

[0135] Experimental Example 1: Analysis of Crystalline Phases According to Differences in Moisture Content (XRD)

[0136] In this experimental example, XRD analysis was performed on the Fe / Al residues of Example 1 and Comparative Example 1 among the Fe / Al residues prepared by the above method, and the results are shown in Figure 3.

[0137] Referring to Figure 3, as the dominance of the Fluoroaluminate Hydrate peak increases, the moisture content decreases. In the Fe / Al residue of Example 1, which has a low moisture content, the Fluoroaluminate Hydrate crystal peak was clearly identified, whereas in the Fe / Al residue of Comparative Example 1, which has a high moisture content, the amorphous peak was relatively increased, and the Lithium Sodium Fluoroaluminate crystal peak was relatively clearly identified.

[0138] This means that the Fe / Al residue produced through the method of the present invention secures the stability of the crystalline phase structure while simultaneously improving dehydration and storage stability.

[0139] Although specific embodiments regarding a method for reducing the moisture content of Fe / Al residues generated in a waste lithium secondary battery recycling process according to the present invention have been described so far, it is obvious that various modifications are possible within the scope of the present invention.

[0140] Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof.

[0141] That is, the aforementioned embodiments should be understood as exemplary in all respects and not limiting, and the scope of the invention is defined by the claims set forth below rather than by the detailed description, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the invention.

Claims

Claim 1 delete Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 delete Claim 11 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized by comprising: (a) a step of preparing a caustic soda slurry by diluting caustic soda with a solution containing a metal salt; (b) a step of preparing Fe / Al sludge by adding the caustic soda slurry to a leachate obtained by leaching valuable metals from a waste lithium secondary battery; (c) a step of preparing Fe / Al washing residue by mixing the Fe / Al sludge with a solution, adjusting the pH using an acid, and then adding the caustic soda slurry; and (d) a step of preparing Fe / Al residue with reduced moisture content by mixing the Fe / Al washing residue with a solution and washing. Claim 12 A method for reducing the moisture content of Fe / Al residues generated in a waste lithium secondary battery recycling process, characterized in that, in claim 11, the solution containing the metal salt is an aqueous metal salt solution containing nickel salt, manganese salt, cobalt salt, or alkaline earth metal salt. Claim 13 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in claim 11, the concentration of the metal salt in the solution containing the metal salt is 3 to 60 g / L. Claim 14 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (a) above, the caustic soda slurry is prepared by mixing a 33 wt% caustic soda solution and a solution containing a metal salt in a ratio of 1:1 to 5. Claim 15 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (b) above, the caustic soda slurry is added to the leaching solution to control the neutralization conditions to pH 5~6 and temperature 50~90℃, thereby precipitating Fe and Al components in the leaching solution in the form of hydroxides to produce Fe / Al sludge. Claim 16 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (b) above, the caustic soda slurry and the leachate are mixed in a solid-to-liquid ratio of 1:1 to 5. Claim 17 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (b) above, the Fe / Al sludge is filtered to separate solids and liquids before proceeding to step (c). Claim 18 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (c) above, the Fe / Al sludge is mixed with a solution and adjusted to a pH of 1.0 to 2.5 using an acid, and then a caustic soda slurry is reintroduced and reacted under conditions of a pH of 3.5 to 4.5 and a temperature of 50 to 90°C to re-neutralize and produce Fe / Al washing residue. Claim 19 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (c) above, the Fe / Al sludge and the solution are mixed in a solid-to-liquid ratio of 1:1 to 5. Claim 20 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (c) above, the Fe / Al washing residue is filtered to separate solids and liquids before proceeding to step (d). Claim 21 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (d) above, the Fe / Al cleaning residue and the solution are mixed in a solid-to-liquid ratio of 1:1 to 5. Claim 22 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (d) above, the washing process is performed by stirring for 10 to 30 minutes under conditions of a temperature of 50 to 90°C. Claim 23 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in step (d) above, solid-liquid separation is performed using a filter press or a centrifuge after washing is completed. Claim 24 A method for reducing the moisture content of Fe / Al residue generated in a waste lithium secondary battery recycling process, characterized in that, in claim 11, the moisture content of the Fe / Al residue produced by the above method is 50 weight% or less. Claim 25 Fe / Al residue containing Fe and Al, having a moisture content of 50% by weight or less, and capable of being produced by the method of any one of claims 11 to 24.

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