Method of recovering transition metal from lithium secondary battery

Abstract

To provide a method of recovering a transition metal from a lithium secondary battery with high efficiency and high purity.SOLUTION: In a method of recovering a transition metal from a lithium secondary battery, an acidic solution is added to a recovery target material containing a transition metal so as to form a leachate. A basic compound is added to the leachate in an amount of 0.5 wt.% to 1.9 wt.% based on the total weight of the leachate so as to form a first transition metal solution. A fluorine compound is added to the first transition metal solution so as to form a second transition metal solution. This can reduce the amount impurities and enhance the purity of nickel, cobalt and manganese to be recovered.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for recovering transition metals from lithium secondary batteries, and more particularly to a method for recovering transition metals from positive electrode active materials of lithium secondary batteries. [Background technology]

[0002] Secondary batteries have been widely applied and developed as power sources for portable electronic communication devices such as camcorders, mobile phones, and notebook computers, and for vehicles such as hybrid cars, electric cars, etc. As secondary batteries, lithium secondary batteries have been actively developed and applied because of their high operating voltage and energy density per unit weight, as well as their advantages in terms of charging speed and weight reduction.

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

[0004] Since the positive electrode active material contains the expensive valuable metals, the production of the positive electrode material accounts for more than 20% of the production cost. In addition, in recent years, with the growing interest in environmental protection, research into recycling methods for the positive electrode active material has been progressing. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a method for recovering transition metals from lithium secondary batteries with high efficiency and high purity. [Means for solving the problem]

[0006] In a method for recovering transition metals from a lithium secondary battery according to an embodiment of the present disclosure, an acidic solution is added to a recovery target material containing transition metals to form a leachate. A basic compound is added to the leachate in an amount of 0.5 wt % to 1.9 wt % based on 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.

[0007] In some embodiments, forming the second transition metal solution can include precipitating calcium contained in the first transition metal solution with the fluorine compound.

[0008] In some embodiments, the transition metal can include at least one selected from the group consisting of nickel, cobalt, and manganese.

[0009] In some embodiments, cobalt and nickel may be extracted sequentially from the second transition metal solution.

[0010] In some embodiments, manganese can be extracted from the second transition metal solution.

[0011] In some embodiments, extracting the manganese may include removing residual calcium from the second transition metal solution.

[0012] In some embodiments, the material to be recovered may include a precipitate that includes reduced transition metals.

[0013] In some embodiments, the acidic solution can include sulfuric acid.

[0014] In some embodiments, the pH of the leachate may be 1-2.

[0015] In some embodiments, the basic compound can include at least one selected from the group consisting of sodium hydroxide, lithium hydroxide, and potassium hydroxide.

[0016] In some embodiments, the first transition metal solution may have a pH of 3 to 4.5.

[0017] In some embodiments, the fluorine compound can include at least one selected from the group consisting of sodium fluoride, magnesium fluoride, and potassium fluoride.

[0018] In some embodiments, the first transition metal solution can include calcium and aluminum.

[0019] In some embodiments, the fluorine compound can be added so as to satisfy the following formula 1. [Formula 1] 1≦(FL♯)÷[((CA♯)×2)+((AL♯)×3)]≦2

[0020] In Equation 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.

[0021] In some embodiments, the pH of the second transition metal solution may be greater than 5 and less than or equal to 7.

[0022] In some embodiments, the steps of forming the first transition metal solution and forming the second transition metal solution may be performed at a temperature between 50°C and 90°C. Effect of the Invention

[0023] According to the aforementioned exemplary embodiment, impurities (e.g., aluminum, iron, calcium) can be removed by selective precipitation of metal ions due to differences in solubility, and transition metals (e.g., nickel, cobalt, manganese) can be recovered in high purity.

[0024] For example, by adding a basic compound to create a pH range in which nickel, cobalt and manganese do not precipitate, aluminum and iron can be removed while reducing the losses of nickel, cobalt and manganese.

[0025] In some embodiments, a fluorine compound can be added at a predetermined content to remove calcium and reduce the loss of nickel, cobalt and manganese even in the pH range where nickel, cobalt and manganese precipitation occurs.

[0026] Accordingly, when the precipitants, that is, the basic compound and the fluorine compound, are added for each pH range, the recovery efficiency of the transition metals in the lithium secondary battery can be improved. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic flow chart illustrating a method for recovering a transition metal from a lithium secondary battery according to an exemplary embodiment. [Diagram 2] Figure 2 shows the solubility of metal hydroxides as a function of pH. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] An exemplary embodiment of the present disclosure provides a method for recovering transition metals from a lithium secondary battery, the method including the steps of sequentially adding a basic compound and a fluorine compound.

[0029] Hereinafter, embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. However, these embodiments are merely illustrative of the present disclosure and are not intended to limit the present disclosure.

[0030] FIG. 1 is a schematic flow chart illustrating a method for recovering a transition metal from a lithium secondary battery according to an exemplary embodiment.

[0031] Referring to FIG. 1, an acidic solution can be added to the transition metal-containing recovery target material to form a leachate (eg, step S10).

[0032] In some embodiments, the transition metal can include at least one selected from the group consisting of nickel, cobalt, and manganese. For example, the transition metal can include nickel and cobalt, which are ultimately extracted.

[0033] In some embodiments, the material to be recovered may include a precipitate containing a reduced transition metal. For example, a waste lithium secondary battery or a used lithium secondary battery may be crushed to obtain a positive electrode active material, and lithium may be removed from the positive electrode active material to obtain a precipitate containing a reduced transition metal.

[0034] The lithium secondary battery may include an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and 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 current collector and a negative electrode current collector, respectively.

[0035] For example, the positive electrode active material contained in the positive electrode active material layer can include an oxide containing lithium and a transition metal.

[0036] In some embodiments, the positive electrode active material may include a compound having a structure represented by Formula 1:

[0037] [Chemical formula 1] Li x Ni 1-y M y O 2+z

[0038] In Chemical Formula 1, x is 0.9≦x≦1.1, y is 0≦y≦0.7, z is −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.

[0039] In some embodiments, the active cathode material may be an NCM-based lithium oxide containing nickel, cobalt, and manganese.

[0040] For example, the positive electrode can be separated from the used lithium secondary battery to recover the used positive electrode. The used positive electrode includes a positive electrode current collector (e.g., aluminum (Al)) and a positive electrode active material layer as described above, and the positive electrode active material layer can include a conductive material and a binder in addition to the positive electrode active material.

[0041] The conductive material may include, for example, a carbon-based material such as graphite, carbon black, graphene, carbon nanotubes, etc. The binder may include, for example, a resin material such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, etc.

[0042] For example, the waste positive electrodes can be pulverized to collect the positive electrode active material, which can include a lithium transition metal oxide powder, for example, an NCM-based lithium oxide powder (e.g., Li(NCM)O2).

[0043] The positive electrode active material may include a component derived from the positive electrode current collector, the binder, or the conductive material. For example, the positive electrode active material may be substantially composed of positive electrode active material particles such as an NCM-based lithium oxide.

[0044] In some embodiments, the conductive material and binder contained in the positive electrode active material can be removed or reduced by subjecting the positive electrode active material to a heat treatment, thereby obtaining high-purity lithium transition metal oxide particles.

[0045] The temperature of the heat treatment may be, for example, about 100° C. to 500° C., preferably about 350° C. to 450° C. Within this range, the conductive material and binder are substantially removed, and decomposition and damage of the lithium transition metal oxide particles can be prevented.

[0046] In some embodiments, lithium can be removed from the positive electrode active material in the form of lithium hydroxide to obtain a precipitate containing the reduced transition metal.

[0047] For example, the positive electrode active material may be reduced with hydrogen gas, a reducing gas, to produce lithium hydroxide (LiOH), a reserve lithium precursor including a lithium oxide (e.g., Li2O), and a transition metal or transition metal oxide. For example, the reductive reaction may produce Ni, Co, Mn, NiO, CoO, or MnO along with the reserve lithium precursor.

[0048] The reduction reaction can be carried out at about 400° C. to 700° C., preferably about 450° C. to 550° C. Within this reaction temperature range, the reduction reaction can be promoted without inviting re-aggregation or recombination of the spare lithium precursor and the transition metal / transition metal oxide.

[0049] For example, when the mixture of the reserve lithium precursor and the transition metal or transition metal oxide is washed with water containing a calcium compound, the reserve lithium precursor in the form of lithium hydroxide (LiOH) may be substantially dissolved in water. For example, the reserve lithium precursor in the form of lithium oxide and lithium carbonate may be partially converted to lithium hydroxide by the washing process and may be dissolved in water.

[0050] In one embodiment, the calcium compound can include at least one of calcium hydroxide and calcium oxide. For example, when the calcium compound is added during the water washing step, lithium carbonate and lithium fluoride are converted into lithium hydroxide, which is contained in the aqueous lithium solution containing the reserve lithium precursor, and calcium carbonate and calcium fluoride, which are less soluble, can be precipitated.

[0051] In one embodiment, the lithium aqueous solution and a precipitate containing reduced transition metals can be obtained separately by a solid-liquid separation process after the water washing treatment. For example, the precipitate containing reduced transition metals can include nickel, cobalt, and manganese produced by the reductive reaction, as well as the calcium carbonate and calcium fluoride.

[0052] An acidic solution may be added to the transition metal-containing recovery target material prepared according to any of the above-described embodiments to form a leachate. For example, an acidic solution may be added to the precipitate containing the reduced transition metal, followed by solid-liquid separation to obtain a leachate and a leach residue.

[0053] In some embodiments, the leachate may contain nickel, cobalt, manganese, aluminum, iron, and calcium. For example, the sum of the concentrations of nickel, cobalt, and manganese in the leachate may be between 100 g / L and 120 g / L.

[0054] In some embodiments, the acid solution can include at least one of sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, and citric acid. In some embodiments, the acid solution can include sulfuric acid. For example, the transition metal can be easily leached using the types of acid solutions mentioned above.

[0055] In some embodiments, the pH of the leachate may be 1 to 2. Within this range, the transition metal can be sufficiently leached, while the amount of basic compound required to form the first transition metal solution can be reduced.

[0056] In some embodiments, leaching can be carried out at a temperature of 50° C. to 90° C. and 100 rpm to 500 rpm for 4 hours to 8 hours.

[0057] For example, the temperature may be 60°C to 85°C or 70°C to 80°C, the rotation speed may be 150 rpm to 400 rpm or 200 rpm to 300 rpm, and the operation time may be 5 hours to 7 hours or 5.5 hours to 6.5 hours. Within the above ranges, leaching of the transition metal can be easily performed.

[0058] For example, in step S20, a basic compound may be added to the leachate in an amount of 0.5% by weight to 1.9% by weight based on the total weight of the leachate to form a first transition metal solution.

[0059] In some embodiments, the basic compound can include at least one selected from the group consisting of sodium hydroxide, lithium hydroxide, and potassium hydroxide. In some embodiments, the basic compound can include sodium hydroxide.

[0060] For example, the above-mentioned types of basic compounds can precipitate the iron and aluminum contained in the leachate at least partially in the form of hydroxides (e.g., Fe(OH)3 and Al(OH)3), after which a first transition metal solution from which iron and aluminum have been removed can be obtained by solid-liquid separation from the leachate.

[0061] In some embodiments, the amount of the basic compound added may be 0.5 wt% to 1.9 wt%, 0.6 wt% to 1.8 wt%, 0.6 wt% to 1.7 wt%, 0.7 wt% to 1.5 wt%, 0.5 wt% to 1.5 wt%, 0.5 wt% to 1.4 wt%, 0.6 wt% to 1.3 wt%, 0.7 wt% to 1 wt%, or 0.5 wt% to 1 wt%, based on the total weight of the leachate.

[0062] For example, if the amount of the basic compound added is less than 0.5 wt. % based on the total weight of the leachate, iron and aluminum may precipitate in small amounts in the form of hydroxides and may not be sufficiently removed, whereas if the amount of the basic compound added is more than 1.9 wt. %, the pH may become high and the losses of nickel, cobalt and manganese may increase.

[0063] Figure 2 shows the solubility of metal hydroxides as a function of pH.

[0064] 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 basic compound added is within the above range, it is possible to maintain a pH at which iron and aluminum are sufficiently precipitated while nickel, cobalt, and manganese are less likely to precipitate.

[0065] 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 this range, a first transition metal solution can be obtained from which iron and aluminum have been sufficiently removed while suppressing losses of nickel, cobalt, and manganese.

[0066] In one embodiment, the basic compound may be added in the form of an aqueous solution, for example, an aqueous solution of sodium hydroxide may be added to the leachate.

[0067] In some embodiments, the first transition metal solution can include calcium and aluminum, for example, after iron and aluminum have been removed from the leach solution, the first transition metal solution can include nickel, cobalt, manganese, residual calcium and residual aluminum.

[0068] In some embodiments, the content of aluminum in the first transition metal solution may be 0.08 wt % to 0.21 wt %, 0.1 wt % to 0.2 wt %, or 0.15 wt % to 0.18 wt %, based on the total weight of the first transition metal solution.

[0069] For example, if too much aluminum is removed from the leachate, the pH of the first transition metal solution will increase to 6.0 or higher, resulting in excessive generation of colloidal precipitates (Al(OH)3), making solid-liquid separation difficult.

[0070] Therefore, within the above range, it is possible to obtain a first transition metal solution from which aluminum has been sufficiently removed while suppressing losses of nickel, cobalt and manganese.

[0071] In some embodiments, the temperature conditions for accelerating the formation of the first transition metal solution may be 50° C. to 90° C., 60° C. to 85° C., or 70° C. to 80° C. At room temperature (25° C.), the rate at which the precipitation reaction between iron and aluminum occurs is slow, and therefore the time to reach equilibrium is short within these temperature ranges.

[0072] In some embodiments, the formation of the first transition metal solution may be allowed to proceed for 1 to 4 hours, 1.5 to 3 hours, or 2 to 3 hours, which is sufficient to allow the precipitation reaction to form the hydroxides of iron and aluminum (Fe(OH)3 and Al(OH)3).

[0073] For example, in step S30, a fluorine compound may be added to the first transition metal solution to form a second transition metal solution.

[0074] In some embodiments, the fluorine compound can include at least one selected from the group consisting of sodium fluoride, magnesium fluoride, and potassium fluoride. Preferably, the fluorine compound can include sodium fluoride.

[0075] In some embodiments, forming the second transition metal solution can include precipitating calcium contained in the first transition metal solution with the fluorine compound.

[0076] For example, fluorine compounds of the aforementioned type can be used to convert calcium and residual aluminum contained in the first transition metal solution at least partially into fluoride form (e.g., CaF2 and AlF x (OH) 3-x ) can be used to precipitate the first transition metal solution. After that, a second transition metal solution from which calcium and residual aluminum have been removed can be obtained by solid-liquid separation.

[0077] In some embodiments, the fluorine compound can be added so as to satisfy the following formula 1.

[0078] [Formula 1] 1≦(FL♯)÷[((CA♯)×2)+((AL♯)×3)]≦2

[0079] For example, the fluorine compound can be added so as to satisfy the following formula 2 or 3.

[0080] [Formula 2] 1.2≦(FL♯)÷[((CA♯)×2)+((AL♯)×3)]≦1.8

[0081] [Formula 3] 1.3≦(FL♯)÷[((CA♯)×2)+((AL♯)×3)]≦1.6

[0082] In the above formulas 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.

[0083] For example, when the fluorine compound satisfies the above formula 1, formula 2 or formula 3, calcium and residual aluminum can be sufficiently removed while suppressing the loss of nickel, cobalt and manganese, thereby increasing the purity of the recovered nickel and cobalt.

[0084] 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 these ranges, a second transition metal solution can be obtained in which calcium and residual aluminum have been sufficiently removed while suppressing losses of nickel, cobalt, and manganese.

[0085] In some embodiments, the second transition metal solution can include nickel, cobalt, and manganese. For example, the second transition metal solution can be free of calcium and aluminum, or can include trace amounts of calcium and aluminum.

[0086] In some embodiments, the temperature conditions for accelerating the formation of the second transition metal solution may be 50° C. to 90° C., 60° C. to 85° C., or 70° C. to 80° C. At room temperature (25° C.), the precipitation reaction of calcium and aluminum occurs slowly, so increasing the reaction temperature shortens the time to reach equilibrium.

[0087] Within the above temperature range, the rate of calcium removal can be increased while suppressing the loss of nickel, cobalt, and manganese, thereby making it possible to efficiently obtain high-purity nickel and cobalt.

[0088] In some embodiments, the time period for forming the second transition metal solution may be between 30 minutes and 3 hours, between 30 minutes and 2 hours, or between 30 minutes and 1 hour. Within the above ranges, calcium and aluminum fluorides (CaF2 and AlF x (OH) 3-x The precipitation reaction in which ) is formed can be carried out sufficiently.

[0089] In some embodiments, manganese can be extracted from the second transition metal solution.

[0090] In some embodiments, the step of extracting the manganese can include removing calcium remaining in the second transition metal solution, for example, the calcium can be residual calcium remaining in the second transition metal solution obtained by the precipitation reaction and solid-liquid separation in step S30.

[0091] In some embodiments, the step of extracting the manganese may include administering an extractant to the second transition metal solution.

[0092] For example, the extractant can include a phosphoric acid extractant, such as di-2-ethylhexyl phosphoric acid (D2EHPA), 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester, and tributyl phosphate. For example, the extractant can be dosed with sodium hydroxide and sulfuric acid.

[0093] As a result, in step S40, trace amounts of residual calcium contained in the second transition metal solution are removed, making it possible to increase the purity of the recovered nickel and cobalt.

[0094] In some embodiments, cobalt and nickel may be extracted sequentially from the second transition metal solution (eg, step S50).

[0095] For example, the second transition metal solution can be input to the cobalt extraction step (e.g., step S51) and then input to the nickel extraction step (e.g., step S52) after the cobalt extraction. For example, the second transition metal solution can be selectively input to the manganese extraction step (e.g., step S40) before input to the cobalt extraction step.

[0096] This allows high purity cobalt and nickel to be extracted from the second transition metal solution. For example, the above-mentioned extraction of cobalt and extraction of nickel can be carried out continuously.

[0097] In some embodiments, the extractant used in the cobalt extraction step comprises a hypophosphorous acid extractant, such as bis(2,4,4-trimethylpentyl)phosphinic acid.

[0098] In some embodiments, the extractant used in the nickel extraction step can include at least one of a phosphoric acid extractant, a phosphorous acid extractant, and a carboxylic acid extractant.

[0099] For example, di-2-ethylhexyl phosphoric acid (D2EHPA), 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester, tributyl phosphate, trioctylphosphine oxide, and alkyl monocarboxylic acids.

[0100] In some embodiments, the extractants used in the cobalt extraction step and the nickel extraction step can be added with sodium hydroxide and sulfuric acid, so that nickel and cobalt can be extracted and obtained in the form of nickel sulfate and cobalt sulfate, respectively.

[0101] In the following, preferred examples are presented to aid in understanding the present invention, but these examples are merely illustrative of the present invention and do not limit the scope of the appended claims. It is clear to those skilled in the art that various changes and modifications can be made to these examples within the scope of the scope and technical ideas of the present invention, and it is natural that these changes and modifications fall within the scope of the appended claims.

[0102] Manufacturing Example The Li-Ni-Co-Mn oxide cathode active material, which is scrap metal, was reduced with hydrogen gas, washed with water while adding calcium hydroxide, and then separated into solid and liquid to obtain a precipitate (NCM Paste) containing reduced transition metals.

[0103] A 2M sulfuric acid solution was added to the precipitate and leaching was carried out for 6 hours under conditions of 80°C and 250 rpm. The leaching residue was then separated by centrifugation to obtain two types of leachates (leachate 1 and leachate 2) (step S10).

[0104] Aqueous sodium hydroxide (50%) solution was added to the obtained leachates 1 and 2, respectively, and reacted at 80° C. for 2 hours, and then centrifuged to obtain a first transition metal solution from which the precipitate had been removed (step S20).

[0105] Sodium fluoride was added to each of the first transition metal solutions obtained from leachates 1 and 2, and the solutions were reacted at 80°C for 30 minutes. Then, the solutions were centrifuged to remove the precipitate and obtain second transition metal solutions (Step S30).

[0106] Experimental Example 1. Metal concentration and pH of leachate before addition of basic compounds The metal concentrations in leachates 1 and 2 were measured before the addition of sodium hydroxide (50%) aqueous solution. The pH of the infusion solutions 1 and 2 was measured using a pH meter. The measurement results are shown in Table 1 below.

[0107] [Table 1]

[0108] 2. Metal concentration and pH of the first transition metal solution The amount of sodium hydroxide (50%) aqueous solution added relative to the total weight of leachate 1 (150 g) was varied as shown in Table 2 below, and first transition metal solutions of the examples and comparative examples were prepared by the method described in the Preparation Examples. The concentrations of metals contained in the first transition metal solutions and the pH of the first transition metal solutions of the examples and comparative examples were measured, and the results are shown in Table 2 below.

[0109] [Table 2]

[0110] Referring to Table 2, the first transition metal solutions according to the examples suppressed the loss of nickel, cobalt and manganese without excessive formation of colloidal precipitates.

[0111] In contrast, the first transition metal solution of Comparative Example 1 had a high content of aluminum and calcium, and the first transition metal solution of Comparative Example 2 had a greater loss of nickel, cobalt and manganese compared to the first transition metal solutions of the Examples.

[0112] In the first transition metal solution of Comparative Example 2, colloidal precipitate (Al(OH)3) was generated in an excessive amount, and solid-liquid separation was not easy.

[0113] 3. Metal concentration and pH of the second transition metal solution A first transition metal solution of Reference Example 1 was produced by adding 1.5 g (1 wt %) of an aqueous solution of sodium hydroxide (50%) relative to the total weight (150 g) of the leachate 2. The concentrations of metals contained in the first transition metal solution of Reference Example 1 and the pH of the first transition metal solution were measured, and the results are shown in Table 3 below.

[0114] [Table 3]

[0115] Thereafter, the second transition metal solutions of Examples 4, 5 and Comparative Example 3 were prepared by the method described in the manufacturing examples, by varying the amount of sodium fluoride added to the first transition metal solution of Reference Example 1 obtained from leachate 2 as shown in Table 4 below. The concentrations of metals contained in the secondary transition metal solutions of Examples 4 and 5 and Comparative Example 3 and the pH of the secondary transition metal solutions were measured, and the results are shown in Table 4 below.

[0116] [Table 4] 1) (FL♯)÷[((CA♯)×2)+((AL♯)×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.

[0117] Referring to Table 4, the second transition metal solutions according to Examples 4 and 5 had a pH greater than 5 and reduced losses of nickel, cobalt and manganese while also providing low concentrations of calcium and aluminum.

[0118] In contrast, the secondary transition metal solution of Comparative Example 3 had higher concentrations of calcium and aluminum than the secondary transition metal solutions of Examples 4 and 5.

[0119] 4. Metal concentration of the second transition metal solution formed by performing steps S20 and S30 at room temperature A second transition metal solution was prepared in the same manner as in Production Example, except that step S20 was performed at room temperature (25° C.) for 2 hours and step S30 was performed at room temperature (25° C.) for 22 hours.

[0120] In step S20, 1.5 g (1 wt%) of an aqueous solution of sodium hydroxide (50%) is added to the total weight (150 g) of the leachate 1, and in step S30, 1.5 eq. of sodium fluoride (see Table 4 above) is added to the first transition metal solution obtained from the leachate 1. 1) " was calculated in the same manner as ".

[0121] The concentration of metals contained in the formed second transition metal solution was measured for each run time, and the results are shown in Table 5 below.

[0122] [Table 5]

[0123] Referring to Table 5, the precipitation reaction of calcium and aluminum occurred at a slower rate in the second transition metal solution formed by performing steps S20 and S30 at room temperature compared to the second transition metal solution of Example 5 in Table 4, which had the same amounts of basic compound and fluorine compound added. This shows that high purity nickel and cobalt can be efficiently obtained when the reaction temperature is high.

Claims

1. A step of adding an acidic solution to a material to be recovered that contains a transition metal to form a leachate; adding a basic compound to the leachate in an amount of 0.5% by weight to 1.9% by weight based on the total weight of the leachate to form a first transition metal solution; and adding a fluorine compound to the first transition metal solution to form a second transition metal solution.

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

3. 2. The method for recovering transition metals from a lithium secondary battery according to claim 1, wherein the transition metal includes at least one selected from the group consisting of nickel, cobalt, and manganese.

4. 4. The method for recovering transition metals from a lithium secondary battery according to claim 3, further comprising the step of sequentially extracting cobalt and nickel from the second transition metal solution.

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

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

7. The method for recovering transition metals from a lithium secondary battery according to claim 1 , wherein the material to be recovered includes a precipitate containing reduced transition metals.

8. The method for recovering transition metals from a lithium secondary battery according to claim 1 , wherein the acidic solution contains sulfuric acid.

9. 2. The method for recovering transition metals from a lithium secondary battery according to claim 1, wherein the pH of the leaching solution is 1 to 2.

10. 2. The method for recovering transition metals from a lithium secondary battery according to claim 1, wherein the basic compound includes at least one selected from the group consisting of sodium hydroxide, lithium hydroxide, and potassium hydroxide.

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

5.

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

13. 2. The method for recovering transition metals from a lithium secondary battery according to claim 1, wherein the first transition metal solution contains calcium and aluminum.

14. The method for recovering transition metals from a lithium secondary battery according to claim 13, wherein the fluorine compound is added so as to satisfy the following formula 1: [Formula 1] 1≦(FL#)÷[((CA#) x 2) + ((AL#) x 3)]≦2 In Equation 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. 2. The method for recovering transition metals from a lithium secondary battery according to claim 1, wherein the pH of the second transition metal solution is greater than 5 and less than or equal to 7.

16. 2. The method for recovering transition metals from a lithium secondary battery according to claim 1, wherein the steps of forming the first transition metal solution and forming the second transition metal solution are carried out at a temperature of 50° C. to 90° C.

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