Method for recovering transition metal of lithium secondary battery

Abstract

In a method for recovering a transition metal of a lithium secondary battery, an acidic solution is added to a substance to be recovered containing a transition metal to form a leachate. 0.5-1.9 wt% of a basic compound relative to the total weight of the leachate is added to the leachate to form a first transition metal solution. A fluorine compound is added to the first transition metal solution to form a second transition metal solution. Thus, the amount of impurities can be reduced, and the purity of the recovered nickel, cobalt, and manganese can be improved.

Description

Technical Field

[0001] The present invention relates to a method for recovering active metals of a lithium secondary battery. More specifically, the present invention relates to a method for recovering transition metals from a positive electrode active material of a lithium secondary battery. Background Art

[0002] Secondary batteries are widely used and developed as power sources for portable electronic communication devices such as camcorders, mobile phones, and laptop computers, and vehicles such as hybrid cars and electric cars. As secondary batteries, lithium secondary batteries have high operating voltage and energy density per unit weight, and are advantageous in charging speed and light weight, and are therefore actively developed and used.

[0003] The positive electrode active material of the lithium secondary battery may be a lithium metal oxide, which may further contain valuable metals such as iron, nickel, cobalt, and manganese.

[0004] Since the high-cost valuable metals are used in the positive electrode active material, more than 20% of the preparation cost is required to prepare the positive electrode material. In addition, due to the increasing environmental protection issues in recent years, methods for recycling positive electrode active materials are being studied. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] A technical problem of the present invention is to provide a method for recovering transition metals of lithium secondary batteries with high efficiency and high purity.

[0007] (II) Technical solution

[0008] In the method for recovering transition metals of lithium secondary batteries according to an embodiment of the present invention, an acidic solution is added to a recovery target material containing transition metals to form a leachate. An alkaline compound is added to the leachate in an amount of 0.5-1.9 wt % relative to the total weight of the leachate to form a first transition metal solution. A fluorine compound is added to the first transition metal solution to form a second transition metal solution.

[0009] In some embodiments, the step of forming the second transition metal solution may include precipitating calcium contained in the first transition metal solution with the fluorine compound.

[0010] In some embodiments, the transition metal may include at least one selected from nickel, cobalt, and manganese.

[0011] In some embodiments, cobalt and nickel may be extracted sequentially from the second transition metal solution.

[0012] In some embodiments, manganese may be extracted from the second transition metal solution.

[0013] In some embodiments, extracting the manganese may include removing residual calcium from the second transition metal solution.

[0014] In some embodiments, the material to be recovered may include a precipitate containing reduced transition metals.

[0015] In some embodiments, the acidic solution may include sulfuric acid.

[0016] In some embodiments, the pH of the leachate may be between 1 and 2.

[0017] In some embodiments, the alkaline compound may include at least one selected from the group consisting of sodium hydroxide, lithium hydroxide, and potassium hydroxide.

[0018] In some embodiments, the pH of the first transition metal solution may be between 3 and 4.5.

[0019] In some embodiments, the fluorine compound may include at least one selected from the group consisting of sodium fluoride, magnesium fluoride, and potassium fluoride.

[0020] In some embodiments, the first transition metal solution may include calcium and aluminum.

[0021] In some embodiments, the fluorine compound may be added to satisfy the following Formula 1:

[0022] [Formula 1]

[0023] 1≤(FL#)÷[((CA#)×2)+((AL#)×3)]≤2.

[0024] In Formula 1, FL# is the number of moles of fluorine contained in the fluorine compound, CA# is the number of moles of calcium contained in the first transition metal solution, and AL# is the number of moles of aluminum contained in the first transition metal solution.

[0025] In some embodiments, the pH of the second transition metal solution may be greater than 5 and less than 7.

[0026] In some embodiments, the step of forming the first transition metal solution and the step of forming the second transition metal solution may be performed at a temperature of 50-90°C.

[0027] (III) Beneficial effects

[0028] According to the above exemplary embodiments, impurities (eg, aluminum, iron, calcium) can be removed and transition metals (eg, nickel, cobalt, manganese) can be recovered with high purity by selective precipitation of metal ions according to solubility differences.

[0029] For example, by adding an alkaline compound to form a pH range where nickel, cobalt, and manganese do not precipitate, it is possible to reduce the loss of nickel, cobalt, and manganese while removing aluminum and iron.

[0030] In some embodiments, calcium can be removed by adding a predetermined amount of fluorine compound, and the loss of nickel, cobalt, and manganese can also be reduced in the pH range where precipitation of nickel, cobalt, and manganese occurs.

[0031] Therefore, when an alkaline compound and a fluorine compound are added as precipitants in each pH range, the recovery efficiency of transition metals in lithium secondary batteries can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic flowchart for explaining a method of recovering a transition metal of a lithium secondary battery according to an exemplary embodiment.

[0033] Figure 2 is the solubility of metal hydroxides according to pH. DETAILED DESCRIPTION

[0034] An exemplary embodiment of the present invention provides a method of recovering a transition metal of a lithium secondary battery including a process of sequentially adding an alkaline compound and a fluorine compound.

[0035] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, these are merely exemplary embodiments, and the present invention is not limited to the specific embodiments exemplarily described.

[0036] Figure 1 is a schematic flowchart for explaining a method of recovering a transition metal of a lithium secondary battery according to an exemplary embodiment.

[0037] Reference Figure 1 , an acidic solution may be added to the recovery target material containing transition metals to form a leaching solution (eg, S10 process).

[0038] In some embodiments, the transition metal may include at least one selected from nickel, cobalt and manganese. For example, the transition metal may include nickel and cobalt that are finally extracted.

[0039] In some embodiments, the recycling target material may include a precipitate containing a reduced transition metal. For example, a positive electrode active material may be obtained by crushing a waste lithium secondary battery or a used lithium secondary battery, and lithium may be removed from the positive electrode active material to obtain a precipitate containing a reduced transition metal.

[0040] The lithium secondary battery may include an electrode assembly including a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode. The positive electrode and the negative electrode may include a positive electrode active material layer and a negative electrode active material layer coated on a positive electrode collector and a negative electrode collector, respectively.

[0041] For example, the positive electrode active material included in the positive electrode active material layer may include an oxide containing lithium and a transition metal.

[0042] In some embodiments, the positive active material may include a compound having a structure represented by the following Chemical Formula 1.

[0043] [Chemical formula 1]

[0044] Li x Ni 1-y M y O 2+z

[0045] In Chemical Formula 1, x may be 0.9≤x≤1.1, y may be 0≤y≤0.7, z may be -0.1≤z≤0.1, and M may be one or more elements selected from Na, Mg, Ca, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Co, Fe, Cu, Ag, Zn, B, Al, Ga, C, Si, Sn, or Zr.

[0046] In some embodiments, the positive active material may be an NCM-based lithium oxide including nickel, cobalt, and manganese.

[0047] For example, the positive electrode can be separated from the waste lithium secondary battery to recover the waste positive electrode. As described above, the waste positive electrode may include a positive electrode current collector (eg, aluminum (Al)) and a positive electrode active material layer, and the positive electrode active material layer may include the above-mentioned positive electrode active material as well as a conductive material and a binder.

[0048] The conductive material may include carbon-based materials such as graphite, carbon black, graphene, carbon nanotubes, etc. The adhesive may include resin materials such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, etc.

[0049] For example, the positive electrode active material may be collected by pulverizing the waste positive electrode. Therefore, the positive electrode active material may include a powder of a lithium transition metal oxide, for example, an NCM-based lithium oxide powder (eg, Li(NCM)O2).

[0050] The positive electrode active material may also include a portion of components derived from the positive electrode current collector, the binder or the conductive material. For example, the positive electrode active material may also be substantially composed of positive electrode active material particles such as NCM-based lithium oxide.

[0051] In some embodiments, the conductive material and the binder included in the positive electrode active material may be removed or reduced by heat-treating the positive electrode active material, thereby obtaining high-purity lithium transition metal oxide particles.

[0052] The heat treatment temperature may be, for example, about 100-500° C., preferably about 350-450° C. Within the above range, the conductive material and the binder may be substantially removed while preventing decomposition and damage of the lithium transition metal oxide particles.

[0053] In some embodiments, lithium may be removed from the positive active material in the form of lithium hydroxide, and a precipitate including reduced transition metals may be obtained.

[0054] For example, when the positive electrode active material is reduced using hydrogen as a reducing gas, a primary lithium precursor including lithium hydroxide (LiOH), lithium oxide (e.g., Li2O) and a transition metal or transition metal oxide may be generated. For example, the primary lithium precursor and Ni, Co, Mn, NiO, CoO or MnO may be formed by a reduction reaction.

[0055] The reduction reaction may be performed at about 400-700° C., preferably about 450-550° C. Within the above reaction temperature range, the reduction reaction may be promoted without causing reaggregation and recombination of the primary lithium precursor and the transition metal / transition metal oxide.

[0056] For example, when the primary lithium precursor and the mixture of the transition metal or transition metal oxide are subjected to a water washing treatment with water containing a calcium compound, the primary lithium precursor in the form of lithium hydroxide (LiOH) can be substantially dissolved in water. For example, the primary lithium precursor in the form of lithium oxide and lithium carbonate can be partially converted into lithium hydroxide by the water washing treatment and can be dissolved in water.

[0057] In one embodiment, the calcium compound may include at least one of calcium hydroxide and calcium oxide. For example, when the calcium compound is added during the water washing process, lithium carbonate and lithium fluoride are converted into lithium hydroxide, which can be included in the lithium aqueous solution containing the primary lithium precursor, and calcium carbonate and calcium fluoride with low solubility can be precipitated.

[0058] In one embodiment, after the water washing treatment, the lithium aqueous solution and the precipitate containing the reduced transition metal can be obtained respectively through a solid-liquid separation process. For example, the precipitate containing the reduced transition metal can contain nickel, cobalt and manganese generated by the reduction reaction as well as the calcium carbonate and calcium fluoride.

[0059] An acidic solution may be added to the recovery target material containing transition metals prepared according to some of the above embodiments to form a leachate. For example, an acidic solution may be added to the precipitate containing reduced transition metals and solid-liquid separation may be performed to obtain a leachate and a leaching residue.

[0060] In some embodiments, the leachate may contain nickel, cobalt, manganese, aluminum, iron, and calcium. For example, the total concentration of nickel, cobalt, and manganese in the leachate may be 100-120 g / L.

[0061] In some embodiments, the acidic solution may include at least one of sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, and citric acid. In some embodiments, the acidic solution may include sulfuric acid. For example, when using an acidic solution of the above type, the transition metal may be easily leached.

[0062] In some embodiments, the pH of the leachate may be between 1 and 2. Within the above range, the transition metal can be fully leached while reducing the amount of the alkaline compound required to form the first transition metal solution.

[0063] In some embodiments, leaching may be performed at a temperature of 50-90°C and 100-500 rpm for 4-8 hours.

[0064] For example, the temperature may be 60-85° C. or 70-80° C., the rotation speed may be 150-400 rpm or 200-300 rpm, and the duration may be 5-7 hours or 5.5-6.5 hours. Within the above range, the leaching of transition metals may be easily performed.

[0065] For example, in the S20 process, 0.5-1.9 wt % of a basic compound relative to the total weight of the leachate may be added to the leachate to form a first transition metal solution.

[0066] In some embodiments, the alkaline compound may include at least one selected from sodium hydroxide, lithium hydroxide, and potassium hydroxide. In some embodiments, the alkaline compound may include sodium hydroxide.

[0067] For example, the above-mentioned alkaline compounds can precipitate at least a portion of the iron and aluminum contained in the leachate in the form of hydroxides (e.g., Fe(OH)3 and Al(OH)3). Afterwards, the first transition metal solution from which the iron and aluminum are removed can be obtained from the leachate by solid-liquid separation.

[0068] In some embodiments, the basic compound may be added in an amount of 0.5-1.9 wt%, 0.6-1.8 wt%, 0.6-1.7 wt%, 0.7-1.5 wt%, 0.5-1.5 wt%, 0.5-1.4 wt%, 0.6-1.3 wt%, 0.7-1 wt% or 0.5-1 wt% relative to the total weight of the leachate.

[0069] For example, when the amount of the alkaline compound added is less than 0.5 wt % relative to the total weight of the leachate, less iron and aluminum are precipitated in the form of hydroxides, and thus they may not be sufficiently removed. When the amount of the alkaline compound added exceeds 1.9 wt % relative to the total weight of the leachate, the pH increases, and thus the loss of nickel, cobalt, and manganese may increase.

[0070] Figure 2 is the solubility of metal hydroxides according to pH.

[0071] Reference Figure 2 It can be seen that as the pH increases, iron, aluminum, nickel, cobalt, manganese and calcium are precipitated in the form of hydroxides in sequence. For example, when the amount of the alkaline compound added is within the above range, a pH at which iron and aluminum are fully precipitated while nickel, cobalt and manganese are less precipitated can be maintained.

[0072] In some embodiments, the pH of the first transition metal solution may be 3.0 to 4.5. In some embodiments, the pH of the first transition metal solution may be 3.0 to 4.3, 3.0 to 4.0, 3.5 to 4.0, or 3.8 to 4.0. Within the above range, a first transition metal solution that suppresses the loss of nickel, cobalt, and manganese while fully removing iron and aluminum can be obtained.

[0073] In one embodiment, the alkaline compound may be added in the form of an aqueous solution. For example, an aqueous sodium hydroxide solution may be added to the leachate.

[0074] In some embodiments, the first transition metal solution may include calcium and aluminum. For example, after removing iron and aluminum from the leachate, the first transition metal solution may include nickel, cobalt, manganese, residual calcium, and residual aluminum.

[0075] In some embodiments, the first transition metal solution may contain aluminum in an amount of 0.08-0.21 wt %, 0.1-0.2 wt %, or 0.15-0.18 wt % relative to the total weight of the first transition metal solution.

[0076] For example, when aluminum is excessively removed from the leachate, the pH of the first transition metal solution increases to more than 6.0, and an excessive amount of precipitate (Al(OH) 3 ) in the form of colloid is generated, so that solid-liquid separation may not be easily performed.

[0077] Therefore, within the above range, the first transition metal solution in which aluminum is sufficiently removed while suppressing the loss of nickel, cobalt, and manganese can be obtained.

[0078] In some embodiments, the temperature conditions for forming the first transition metal solution may be 50-90° C., 60-85° C., or 70-80° C. The precipitation reaction of iron and aluminum occurs slowly at room temperature (25° C.), so the time to reach equilibrium can be reduced within the above temperature range.

[0079] In some embodiments, the time for forming the first transition metal solution can be 1-4 hours, 1.5-3 hours or 2-3 hours. Within the above range, the precipitation reaction of forming iron and aluminum hydroxides (Fe(OH)3 and Al(OH)3) can be fully carried out.

[0080] For example, in the S30 process, a fluorine compound may be added to the first transition metal solution to form a second transition metal solution.

[0081] In some embodiments, the fluorine compound may include at least one selected from sodium fluoride, magnesium fluoride and potassium fluoride. Preferably, the fluorine compound may include sodium fluoride.

[0082] In some embodiments, the step of forming the second transition metal solution may include precipitating calcium contained in the first transition metal solution with the fluorine compound.

[0083] For example, the above-mentioned fluorine compounds can make at least a portion of the calcium and residual aluminum contained in the first transition metal solution in the form of fluorides (e.g., CaF2 and AlF x (OH) 3-x ) precipitation. Then, through solid-liquid separation, a second transition metal solution from which calcium and residual aluminum are removed can be obtained from the first transition metal solution.

[0084] In some embodiments, the fluorine compound may be added to satisfy Formula 1 below.

[0085] [Formula 1]

[0086] 1≤(FL#)÷[((CA#)×2)+((AL#)×3)]≤2

[0087] For example, the fluorine compound may be added to satisfy Formula 2 or Formula 3 below.

[0088] [Formula 2]

[0089] 1.2≤(FL#)÷[((CA#)×2)+((AL#)×3)]≤1.8

[0090] [Formula 3]

[0091] 1.3≤(FL#)÷[((CA#)×2)+((AL#)×3)]≤1.6

[0092] In Formulae 1 to 3, FL# is the number of moles of fluorine contained in the fluorine compound, CA# is the number of moles of calcium contained in the first transition metal solution, and AL# is the number of moles of aluminum contained in the first transition metal solution.

[0093] For example, when the fluorine compound satisfies Formula 1, Formula 2, or Formula 3, the loss of nickel, cobalt, and manganese can be suppressed while calcium and residual aluminum can be sufficiently removed. Therefore, the purity of recovered nickel and cobalt can be increased.

[0094] In some embodiments, the pH of the second transition metal solution may be greater than 5 and less than 7. In some embodiments, the pH of the second transition metal solution may be greater than 5 and less than 7, 5.5 to 7, 5.5 to 6.5, or 6.0 to 6.5. Within the above range, a second transition metal solution can be obtained that suppresses the loss of nickel, cobalt, and manganese while fully removing calcium and residual aluminum.

[0095] In some embodiments, the second transition metal solution may include nickel, cobalt, and manganese. For example, the second transition metal solution may not include calcium and aluminum or may include trace amounts of calcium and aluminum.

[0096] In some embodiments, the temperature conditions for forming the second transition metal solution can be 50-90° C., 60-85° C. or 70-80° C. At room temperature (25° C.), the precipitation reaction of calcium and aluminum occurs slowly, so increasing the reaction temperature can reduce the time to reach equilibrium.

[0097] In the above temperature range, the loss of nickel, cobalt and manganese can be suppressed while the rate of calcium removal is increased, so that high-purity nickel and cobalt can be obtained efficiently.

[0098] In some embodiments, the time for forming the second transition metal solution can be 30 minutes to 3 hours, 30 minutes to 2 hours, or 30 minutes to 1 hour. Within the above range, the formation of calcium and aluminum fluorides (CaF2 and AlF x (OH) 3-x ) precipitation reaction.

[0099] In some embodiments, manganese may be extracted from the second transition metal solution.

[0100] In some embodiments, the step of extracting the manganese may include removing calcium remaining in the second transition metal solution. For example, the calcium may be residual calcium remaining in the second transition metal solution obtained by the precipitation reaction and solid-liquid separation in the S30 process.

[0101] In some embodiments, the step of extracting the manganese may include adding an extractant to the second transition metal solution.

[0102] For example, the extractant may include a phosphoric acid-based extractant. For example, the phosphoric acid-based extractant may include di-2-ethylhexyl phosphoric acid (D2EHPA), 2-ethylhexyl phosphate mono-2-ethylhexyl ester, and tributyl phosphate, etc. For example, the extractant may be added together with sodium hydroxide and sulfuric acid.

[0103] Therefore, in the S40 process, a trace amount of residual calcium contained in the second transition metal solution is removed, thereby improving the purity of the recovered nickel and cobalt.

[0104] In some embodiments, cobalt and nickel may be extracted sequentially from the second transition metal solution (eg, S50 process).

[0105] For example, the second transition metal solution can be added to the process of extracting cobalt (e.g., S51), and can be added to the process of extracting nickel (e.g., step S52) after extracting cobalt. For example, the second transition metal solution can be optionally added to the above-mentioned process of extracting manganese (e.g., S40) before being added to the process of extracting cobalt.

[0106] Therefore, high-purity cobalt and nickel can be extracted from the second transition metal solution. For example, the above-mentioned extraction of cobalt and extraction of nickel can be performed continuously.

[0107] In some embodiments, the extractant used in the step of extracting cobalt may include a phosphinoic acid-based extractant, for example, bis(2,4,4-trimethylpentyl)phosphinic acid and the like.

[0108] In some embodiments, the extractant used in the step of extracting nickel may include at least one of a phosphoric acid-based extractant, a phosphite-based extractant, and a carboxylic acid-based extractant.

[0109] For example, di-2-ethylhexyl phosphoric acid (D2EHPA), 2-ethylhexyl phosphate mono-2-ethylhexyl ester, tributyl phosphate, trioctylphosphine oxide, alkyl monocarboxylic acid and the like can be cited.

[0110] In some embodiments, the extracting agent used in the step of extracting cobalt and the step of extracting nickel can be added together with sodium hydroxide and sulfuric acid. Therefore, nickel and cobalt can be extracted and obtained in the form of nickel sulfate and cobalt sulfate, respectively.

[0111] Below, specific experimental examples are proposed to help understand the present invention, but this is only used to illustrate the present invention rather than to limit the scope of rights. Various changes and modifications can be made to the embodiments within the scope of the present invention and the technical idea, which is obvious to those skilled in the art, and such changes and modifications also fall within the scope of rights.

[0112] Preparation Example

[0113] The Li-Ni-Co-Mn oxide positive electrode active material as waste metal is reduced with hydrogen, washed with water while adding calcium hydroxide, and then solid-liquid separation is performed to obtain a precipitate (NCM paste) containing reduced transition metals.

[0114] A 2M sulfuric acid solution was added to the precipitate, and leaching was performed at 80°C and 250 rpm for 6 hours, and then the leaching residue was separated by centrifugation to obtain two leachates (leachate 1 and leachate 2) (S10 process).

[0115] Sodium hydroxide (50%) aqueous solution was added to the obtained leachate 1 and leachate 2, respectively, and the mixture was reacted at 80° C. for 2 hours and then centrifuged to obtain a first transition metal solution from which the precipitate was removed (S20 process).

[0116] Sodium fluoride was added to each of the first transition metal solutions obtained from the leachate 1 and the leachate 2, and the mixture was reacted at 80° C. for 30 minutes and then centrifuged to obtain a second transition metal solution from which the precipitate was removed (S30 process).

[0117] Experimental example

[0118] 1. Metal concentration and pH of the leachate before adding alkaline compounds

[0119] The concentrations of metals contained in the leachate 1 and the leachate 2 before adding the sodium hydroxide (50%) aqueous solution were measured.

[0120] In addition, the pH of the leachate 1 and the leachate 2 was measured using a pH meter.

[0121] The measurement results are recorded in Table 1 below.

[0122] [Table 1]

[0123]

[0124] 2. Metal concentration and pH of the first transition metal solution

[0125] According to Table 2 below, the amount of sodium hydroxide (50%) aqueous solution added relative to the total weight (150 g) of the leachate 1 was changed, and the first transition metal solutions of Examples and Comparative Examples were formed according to the method described in the Preparation Examples.

[0126] The concentration of the metal contained in the first transition metal solution of the example and the comparative example and the pH of the first transition metal solution were measured, and the measurement results are described in Table 2 below.

[0127] [Table 2]

[0128]

[0129] Referring to Table 2, an excessive amount of precipitates in the form of colloids were not formed in the first transition metal solution according to the example, and the losses of nickel, cobalt, and manganese were suppressed.

[0130] However, the contents of aluminum and calcium in the first transition metal solution according to Comparative Example 1 were high, and the losses of nickel, cobalt, and manganese in the first transition metal solution according to Comparative Example 2 were greater than those in the first transition metal solution according to the embodiment.

[0131] According to Comparative Example 2, an excessive amount of precipitate (Al(OH) 3 ) in the form of colloid is generated in the first transition metal solution, so that solid-liquid separation is not easy.

[0132] 3. Metal concentration and pH of the second transition metal solution

[0133] 1.5 g (1 wt %) of a sodium hydroxide (50%) aqueous solution was added relative to the total weight (150 g) of the leachate 2 to prepare the first transition metal solution of Reference Example 1.

[0134] The concentration of the metal contained in the first transition metal solution of Reference Example 1 and the pH of the first transition metal solution were measured and are shown in Table 3 below.

[0135] [Table 3]

[0136]

[0137] Then, according to Table 4 below, for the first transition metal solution of Reference Example 1 obtained from leachate 2, the amount of sodium fluoride added was changed, and the second transition metal solutions of Examples 4 and 5 and Comparative Example 3 were formed by the method described in the Preparation Example.

[0138] The concentration of the metal contained in the second transition metal solution of Examples 4 and 5 and Comparative Example 3 and the pH of the second transition metal solution were measured, and the measurement results are recorded in Table 4 below.

[0139] [Table 4]

[0140]

[0141] 1) (FL#)÷[((CA#)×2)+((AL#)×3)]

[0142] FL# is the number of moles of fluorine contained in the fluorine compound, CA# is the number of moles of calcium contained in the first transition metal solution, and AL# is the number of moles of aluminum contained in the first transition metal solution.

[0143] Referring to Table 4, the pH of the second transition metal solutions according to Examples 4 and 5 exceeded 5, and the losses of nickel, cobalt, and manganese were suppressed while the concentrations of calcium and aluminum were low.

[0144] However, compared with the second transition metal solutions according to Examples 4 and 5, the concentrations of calcium and aluminum in the second transition metal solution according to Comparative Example 3 were high.

[0145] 4. Metal concentration of the second transition metal solution formed by performing the S20 process and the S30 process at room temperature

[0146] The second transition metal solution was formed by the same method as in the preparation example, except that the S20 process was performed at room temperature (25° C.) for 2 hours, and the S30 process was performed at room temperature (25° C.) for 22 hours.

[0147] At this time, in the S20 process, 1.5 g (1 wt%) of a sodium hydroxide (50%) aqueous solution was added relative to the total weight (150 g) of the leachate 1, and in the S30 process, 1.5 equivalents of sodium fluoride (equivalent to the total weight of Table 4) was added to the first transition metal solution obtained from the leachate 1. 1) calculated in the same way).

[0148] The concentration of the metal contained in the formed second transition metal solution was measured at each processing time, and the measurement results are described in Table 5 below.

[0149] [Table 5]

[0150]

[0151] Referring to Table 5, the precipitation reaction of calcium and aluminum in the second transition metal solution formed by performing the S20 process and the S30 process at room temperature is slow compared to the second transition metal solution of Example 5 of Table 4 in which the addition amount of the basic compound and the fluorine compound is the same. Therefore, it can be seen that high-purity nickel and cobalt can be efficiently obtained when the reaction temperature is high.

Claims

1. A method for recovering transition metals from lithium secondary batteries, The following steps are involved: Adding an acidic solution to a recovery target substance containing transition metals to form a leaching solution; adding 0.5-1.9 wt % of a basic compound relative to the total weight of the leachate to the leachate to form a first transition metal solution; as well as A fluorine compound is added to the first transition metal solution to form a second transition metal solution.

2. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The step of forming the second transition metal solution includes precipitating calcium contained in the first transition metal solution with the fluorine compound.

3. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The transition metal includes at least one selected from nickel, cobalt and manganese.

4. The method for recovering transition metals from lithium secondary batteries according to claim 3, in, The method further comprises the steps of sequentially extracting cobalt and nickel from the second transition metal solution.

5. The method for recovering transition metals from lithium secondary batteries according to claim 3, in, The method further comprises the step of extracting manganese from the second transition metal solution.

6. The method for recovering transition metals from lithium secondary batteries according to claim 5, in, The step of extracting the manganese includes removing residual calcium from the second transition metal solution.

7. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The recovery target material includes a precipitate containing reduced transition metals.

8. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The acidic solution comprises sulfuric acid.

9. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The pH of the leachate is 1 to 2.

10. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The alkaline compound includes at least one selected from the group consisting of sodium hydroxide, lithium hydroxide and potassium hydroxide.

11. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The pH of the first transition metal solution is 3 to 4.

5.

12. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The fluorine compound includes at least one selected from the group consisting of sodium fluoride, magnesium fluoride and potassium fluoride.

13. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The first transition metal solution comprises calcium and aluminum.

14. The method for recovering transition metals from lithium secondary batteries according to claim 13, in, The fluorine compound is added to satisfy the following formula 1: [Formula 1] 1≤(FL#)÷[((CA#)×2)+((AL#)×3)]≤2 In Formula 1, FL# is the number of moles of fluorine contained in the fluorine compound, CA# is the number of moles of calcium contained in the first transition metal solution, and AL# is the number of moles of aluminum contained in the first transition metal solution.

15. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The pH of the second transition metal solution is greater than 5 and less than 7.

16. The method for recovering transition metals from lithium secondary batteries according to claim 1, in, The step of forming the first transition metal solution and the step of forming the second transition metal solution are performed at a temperature of 50-90°C.

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