KR20200123659A - Manufacturing Method of Mixed Metal Compounds for Preparing Precursors from Waste Cathode Active Material Powders - Google Patents

Abstract

A method for manufacturing a mixed metal compound for manufacturing a precursor from a waste positive electrode active material powder comprises the following steps: leaching the waste positive electrode active material powder with an acidic leaching agent by using at least one reducing agent among H_2O_2, SO_2, Na_2S_2O_5, NaHSO_3, Na_2SO_3, KHSO_3, K_2SO_3, FeSO_4, H_2S, ascorbic acid, and glucose; (b) conducting a reaction by adding a positive electrode active material powder to the leached filtrate at a high liquid ratio of 100 to 150 (g/L); (c) removing hydroxide compounds of copper (Cu), aluminum (Al), and iron (Fe) at pH 6.3 to 6.5 by adding an alkali agent containing at least one of NaOH and KOH to the reacted filtrate; (d) adding an alkali agent containing at least one of sodium carbonate (Na_2CO_3), sodium hydroxide (NaOH), and potassium hydroxide (KOH) to the filtrate from which hydroxide compounds of (Cu), aluminum (Al), and iron (Fe) have been removed to coprecipitate nickel (Ni)-cobalt (Co)-manganese (Mn); and washing the coprecipitated coprecipitate with water, and dissolving the washed coprecipitate in a sulfuric acid solution to manufacture a complex sulfate solution containing the mixed metal compound. A sulfuric acid compound of the present invention can be reused in a precursor manufacturing process, thereby having an effect of improving economic efficiency.

Description

Manufacturing Method of Mixed Metal Compounds for Preparing Precursors from Waste Cathode Active Material Powders}

The present invention relates to a method for preparing a mixed metal compound for preparing a precursor from a waste cathode active material powder, and more particularly, to prepare a precursor for a cathode active material by using the waste cathode active material powder obtained from a ternary cathode active material of a waste lithium secondary battery. It relates to a method for producing a mixed metal compound for preparing a precursor from a waste cathode active material powder capable of obtaining a mixed metal compound to be used.

In recent years, the spread of electric vehicles is expanding due to the strengthening of automobile fuel economy regulations and carbon dioxide emission standards in major global countries. In addition, according to the need for an energy storage system (ESS), which is essential for maximizing the use of new and renewable energy, the secondary battery utilization industry and market are expected to expand explosively. For example, among lithium secondary batteries, the positive electrode active material accounts for a high proportion of 35% or more of the total manufacturing cost, and in particular, the amount of Ni-Co-Mn (NCM)-based positive electrode active material is increasing. Therefore, the process of recovering the valuable metals contained in the waste cathode active material from the discarded lithium secondary battery is a very important task in terms of resource recycling as well as recovering rare metals and metals such as cobalt and lithium designated as strategic minerals.

Public Patent Publication No. 10-2017-0061206 proposes a method of recovering precursor raw materials from a waste cathode material, but does not present a method of recovering lithium and a process for removing impurities such as copper, which are generally present as an anode material. . In addition, since the solvent extraction process, which is a conventional wet treatment method, has to be separated and recovered into nickel, cobalt, and manganese compounds, it is not economical.

Accordingly, an object of the present invention is a mixed metal compound for preparing a precursor from a waste cathode active material powder capable of recovering and manufacturing a cathode active material that can be used as a precursor raw material through an economical method of waste cathode active material powder generated from a waste lithium secondary battery. It is to provide a method of manufacturing.

In addition, an object of the present invention is to provide a method for preparing a mixed metal compound for preparing a precursor from a waste cathode active material powder capable of excluding lithium components that affect the physical properties of the mixed metal compound as a precursor raw material as much as possible.

The method for preparing a mixed metal compound for preparing a precursor from the waste cathode active material powder for achieving the object of the present invention includes (a) an acidic leachant and the waste cathode active material powder as H ₂ O ₂ , SO ₂ , Na ₂ S ₂ O ₅ , NaHSO ₃ , Na ₂ SO ₃ , KHSO ₃ , K ₂ SO ₃ , FeSO ₄ , H ₂ S, ascorbic acid, glucose (glucose) using at least one reducing agent of the lung anode Leaching the active material powder; (b) reacting by additionally adding positive electrode active material powder at a high-liquid ratio of 100 to 150 (g/L) to the leached filtrate; (c) removing a hydroxide compound of copper (Cu), aluminum (Al), and iron (Fe) at pH 6.3 to 6.5 by adding an alkali agent containing at least one of NaOH and KOH to the reacted filtrate; (d) The filtrate from which hydroxide compounds of copper (Cu), aluminum (Al), and iron (Fe) have been removed contains at least one of sodium carbonate (Na ₂ CO ₃ ), sodium hydroxide (NaOH), and potassium hydroxide (KOH) Co-precipitation of nickel (Ni)-cobalt (Co)-manganese (Mn) by introducing an alkali agent; And (e) washing the coprecipitated product with water, and dissolving the washed coprecipitate in a sulfuric acid solution to prepare a complex sulfate solution containing the mixed metal compound. The waste anode active material powder generated from the waste lithium secondary battery is separated into nickel, cobalt, and manganese compounds through a solvent extraction process, which is a conventional wet treatment method, and the co-precipitate is re-dissolved in sulfuric acid without recovery. Accordingly, the finally obtained sulfuric acid compound having various molar ratio compositions such as nickel, cobalt, and manganese can be reused in the precursor manufacturing process by adjusting the molar ratio of nickel, cobalt, and manganese.

Here, the step of roasting the waste cathode active material powder at 500°C or higher before step (a); Recovering lithium (Li) in the filtrate other than the coprecipitate in step (d) at 25°C to 90°C; And adding a fluorine compound containing NaF or NH ₄ F after the step (b) to remove calcium (Ca) from the filtrate with CaF ₂ , the leaching rate increases as the roasting temperature increases, Lithium can be recovered and calcium can be removed, which is preferable.

And in the leaching step of step (a), the amount of the reducing agent added is 0.4 to 0.7 compared to the equivalent amount of the reducing agent required to reduce (cobalt (Co) + nickel (Ni) + manganese (Mn)) contained in the waste cathode active material powder. And the concentration of the acidic leachant is adjusted to a molar concentration of 1.5 to 2 times the molar concentration of (cobalt (Co) + nickel (Ni) + manganese (Mn)) contained in the leached filtrate. After leaching, the pH of the filtrate is adjusted to be 0.7 to 1.5, and if the leaching reaction temperature is 50 to 95°C, the leaching rate of (cobalt (Co) + nickel (Ni) + manganese (Mn)) can be increased, which is preferable.

Here, the coprecipitation of step (d) is performed at a reaction temperature of 25±2° C., and when the alkali agent is a hydroxide, it is performed at a pH of 9.5 to 10 at which manganese (Mn) can be recovered, and the alkali agent is carbonated. In the case of a compound, it is preferable that nickel (Ni) can be co-precipitated at the same time when nickel (Ni) is carried out in a pH range of 8 to 9 or less that can be finally recovered.

And the step of preparing the complex sulfate solution, the water washing temperature for removing the sodium (Na) and lithium (Li) co-existing in the coprecipitate is 25 ℃ ~ 50 ℃ solid-liquid ratio to the coprecipitate 500 ~ 1,000 (g Water washing at least two times at a rate of /L); And adding a reducing agent so that the complex sulfate solution has a pH of 3.5 to 4, some of the recovered coprecipitates of nickel (Ni)-cobalt (Co)-manganese (Mn) are oxidized to exist in a trivalent state. It is preferable because the coprecipitate can be removed using a reducing agent.

Here, in the step of reacting in step (b), the waste cathode active material powder is added so that the leachate has a pH of 3.0 to 3.5, and iron (Fe), which is an impurity, is performed at a reaction temperature of 50 to 70° C. for 0.5 to 1 hour. , Copper (Cu), aluminum (Al), etc. can be removed with a hydroxide, which is preferable.

According to the present invention, the waste cathode active material powder generated from the waste lithium secondary battery is separated into nickel, cobalt, and manganese compounds through a solvent extraction process, which is a conventional wet treatment method, and the co-precipitate is redissolved in sulfuric acid without recovery. Accordingly, the finally obtained sulfuric acid compound having various molar ratio compositions, such as nickel, cobalt, and manganese, can be reused in the precursor manufacturing process by adjusting the molar ratio of nickel, cobalt, and manganese, thereby improving economic efficiency.

By roasting the waste cathode active material powder above 500℃, the leaching rate increases as the roasting temperature increases, and lithium (Li) in the filtrate other than the coprecipitate can be recovered, and calcium (Ca) can be removed from the filtrate after the neutralization step. It can have an effect.

The amount of reducing agent is added in a ratio of 0.4 to 0.7 relative to the equivalent of the reducing agent, and the concentration of the acidic leachant is adjusted to a molar concentration of 1.5 to 2 times the molar concentration of (cobalt (Co) + nickel (Ni) + manganese (Mn)). So that the pH of the filtrate is 0.7 ~ 1.5 after leaching, and the leaching rate of (cobalt (Co) + nickel (Ni) + manganese (Mn)) can be increased if the leaching reaction temperature is 50 ~ 95℃. There is.

The reaction temperature is 25±2℃, in the range of pH 9.5 to 10 where manganese (Mn) can be recovered when the alkali agent is a hydroxide, and pH 8 to 9 or less where nickel (Ni) can be finally recovered when the alkali is a carbonate compound. At the same time, nickel (Ni)-cobalt (Co)-manganese (Mn) can be co-precipitated.

There is an effect of removing some of the recovered nickel (Ni)-cobalt (Co)-manganese (Mn) co-precipitates that may exist in a trivalent state due to oxidation using a reducing agent.

The waste cathode active material powder is added so that the leachate becomes pH 3.0 to 3.5, and the reaction temperature is 50 to 70°C for 0.5 to 1 hour, and the reaction temperature is 50 to 70°C for 0.5 to 1 hour. It has the effect of removing impurities such as iron (Fe), copper (Cu), and aluminum (Al) as hydroxide through the secondary neutralization process of pH 4.5 ~ 6.5 by adding an alkali agent to the secondary neutralization filtrate at room temperature. have.

1 is a schematic flow chart of the production of a mixed metal compound for preparing a precursor from a waste cathode active material powder according to the present invention.
Figure 2 is a detailed manufacturing flow chart.

Hereinafter, a method of preparing a mixed metal compound for preparing a precursor from a waste cathode active material powder according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The waste cathode active material powder of the present invention is obtained from a discarded ternary cathode active material for lithium ion batteries, and in particular, a Ni-Co-Mn (NCM) ternary anode active material is used. The collected waste cathode active material is prepared in a waste cathode active material powder state through a predetermined powdering process. In the waste cathode active material powder, various components such as aluminum (Al), copper (Cu), iron (Fe), and calcium (Ca) are mixed in addition to nickel (Ni), cobalt (Co), manganese (Mn), and lithium (Li). Has been.

In the method for preparing a mixed metal compound of the present invention, as shown in Figs. 1 and 2, the prepared waste anode active material powder is acid-leached with a reducing agent, and first and second neutralization precipitation is performed to remove metallic impurities in the leached filtrate, The neutralized filtrate is co-precipitated with a ternary compound including nickel, cobalt, manganese, etc. by alkali precipitation, and the co-precipitate is redissolved in sulfuric acid to obtain a hydroxide of a mixed metal compound. Here, the waste cathode active material can be roasted and used in the acid leaching process, and the lithium component can be recovered first prior to the sulfuric acid re-dissolution process of the coprecipitate. Hereinafter, each process will be described in detail based on a schematic manufacturing flow chart of a mixed metal compound for preparing a precursor from the waste cathode active material powder according to the present invention of FIG. 1 and a detailed flow chart of FIG. 2.

Roast the waste anode active material powder above 500℃. The leaching efficiency of the co-precipitate may be increased by the roasting process of the waste positive electrode active material through a predetermined heating mechanism, and the roasting process may not be performed depending on the manufacturing environment.

Acid leachants and H ₂ O ₂ , SO ₂ , Na ₂ S ₂ O ₅ , NaHSO ₃ , Na ₂ SO ₃ , KHSO ₃ , K ₂ SO ₃ , FeSO ₄ , H ₂ S, ascorbic acid, glucose The waste cathode active material powder is leached using at least one reducing agent among (glucose). The reducing agent is added in a ratio of 0.4 to 0.7 compared to the equivalent of reducing agent required to reduce (cobalt (Co) + nickel (Ni) + manganese (Mn)) contained in the waste cathode active material powder, and the concentration of the acidic leachant is The pH of the filtrate after leaching is adjusted to be 0.7 ~ 1.5 by adjusting the molar concentration of 1.5 to 2 times the molar concentration of (cobalt (Co) + nickel (Ni) + manganese (Mn)) contained in the filtrate, and leaching reaction The temperature is 50 ~ 95 ℃. The ternary cathode active material (Li(Ni _x Co _y Mn _z )O ₂ )(x+y+z = 1) collected from waste batteries is physically separated from the battery case, separator, positive electrode (Al), negative electrode ( It is preferable to remove Cu) and the like. As the acidic leaching agent, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, or organic acids such as citric acid, acetic acid, malic acid, and carboxylic acid may be used. In the case of hydrochloric acid or nitric acid, a reducing atmosphere is formed by the generation of Cl ₂ (g) or NO _x (g) during the reaction, and in the case of sulfuric acid and organic acids, a reducing atmosphere can be created by adding a reducing agent.

The reaction temperature in the leaching step is preferably 50 ~ 95 ℃. When the reaction temperature is less than 50℃, the leaching reaction rate is slow and the leaching efficiency decreases. When the reaction temperature is higher than 95℃, the evaporation reaction of the aqueous solution is active under atmospheric pressure, so the leaching efficiency decreases and the energy cost increases. In addition, the concentration of the organic or inorganic acid used as the leaching agent is adjusted to a molar concentration of 1.5 or more and less than 2 times the molar concentration of nickel (Ni) + cobalt (Co) + manganese (Mn) in the solution, so that the pH of the filtrate after leaching is It is preferable to adjust it to be 0.7 to 1.5. If the acid concentration is high, the leaching rate due to diffusion may be increased by Fick's law, but the amount of alkali agent consumed in the next step of neutralization increases, and if the acid concentration is low, the leaching rate is slow, and the reaction time may be lengthened.

The positive electrode active material powder is additionally added to the leached filtrate at a high-liquid ratio of 100 to 150 (g/L) and reacted. Accordingly, the leached filtrate is first neutralized, and consumption of an alkali agent can be reduced in a subsequent neutralization process, and may be particularly preferable for removing iron (Fe) components among impurities. The waste cathode active material powder added here is added so that the leaching filtrate has a pH of 3.0 to 3.5, and the reaction temperature is carried out for 0.5 to 1 hour at 50 to 70°C.

If the concentration of calcium (Ca) in the filtrate is high after the first neutralization of the filtrate, a fluorine compound containing NaF and NH ₄ F is added to remove calcium (Ca) from the filtrate as CaF ₂ . Depending on the concentration of calcium in the filtrate, this process may be omitted.

An alkali agent containing at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH) is added to the filtrate reacted by the first neutralization, and copper (Cu), aluminum (Al), and iron (Fe) at pH 6.3 to 6.5 Removes hydroxide compounds. Accordingly, the filtrate is secondary neutralized to remove impurities, this secondary neutralization can be carried out at room temperature around 25±2℃, and the pH is adjusted to be greater than or equal to 4.5 and less than or equal to 6.5. Copper (Cu), aluminum (Al) It may be desirable for component removal. In addition, since the first neutralization process is in a reducing condition, some remaining iron (Fe) components in the form of Fe (II) may be removed together with copper and aluminum components during the secondary neutralization process.

In the filtrate from which hydroxide compounds of copper (Cu), aluminum (Al), and iron (Fe), which are impurities, have been removed by primary and secondary neutralization, sodium carbonate (Na ₂ CO ₃ ), sodium hydroxide (NaOH), potassium hydroxide ( An alkali agent containing at least one of KOH) is added to co-precipitate nickel (Ni)-cobalt (Co)-manganese (Mn). This coprecipitation process is carried out at room temperature within 25±2℃ of the reaction temperature, and in the range of pH 9.5 to 10 where manganese (Mn) can be recovered when the alkali agent is a hydroxide, nickel (Ni) when the alkali is a carbonate compound. This should be carried out in a pH range of 8 to 9 that can be finally recovered.

When the coprecipitate is recovered, lithium (Li) in the remaining filtrate is recovered at 25°C to 90°C. Since a considerable concentration of lithium remains in the filtrate after recovery of the coprecipitate, trisodium phosphate (Na ₃ PO ₄ ) is added to recover the lithium component in the form of lithium phosphate (Li ₃ PO ₄ ).

On the other hand, water washing is performed to remove sodium (Na) and lithium (Li) co-existing in the co-precipitate, and the water washing temperature is between 25°C and 50°C and the solid-liquid ratio of the recovered coprecipitate in a wet cake state is 500 ~ 1,000 (g Wash with water at least twice at a rate of /L). The co-precipitates are recovered in the form of wet cakes by washing with water, and the moisture content of the wet cakes is about 75 to 80%. Lithium (Li) is essential for the production of the positive electrode active material, but in the precursor production process, if the lithium component remains in the coprecipitate, it is preferable to be excluded as much as possible because it affects physical properties such as particle size distribution of the mixed metal compound used as the precursor material. Accordingly, the lithium (Li) component is removed prior to formation of the mixed metal compound synthesized as a subsequent precursor.

A reducing agent is added so that a complex sulfate solution formed by dissolving the washed wet cake-shaped coprecipitate with a sulfuric acid solution is pH 3.5 to 4 to prepare a complex sulfate solution containing a mixed metal compound. This dissolution is carried out at room temperature within the reaction temperature of 25±2℃, and some of the coprecipitates of nickel (Ni)-cobalt (Co)-manganese (Mn) recovered earlier during dissolution may be oxidized and exist in a trivalent state. Some oxidized coprecipitates are removed using an appropriate amount of reducing agent.

The coprecipitate is dissolved in a sulfuric acid solution to prepare a precursor by adjusting the molar ratio of nickel, cobalt, and manganese to a sulfuric acid compound composed of nickel, cobalt, and manganese particles.

[Example]

[Table 1] is an example of the raw material composition of the nickel (Ni)-cobalt (Co)-manganese (Mn) NCM-based positive electrode active material powder used in the experiment.

NCM-based raw material composition (wt.%) NCM Co Cu Fe Mn Ca Al Ni Li LOI wt.% 10.67 2.7 0.14 11.77 0.03 0.11 29.86 6.06 2.4

(LOI = Loss on Ignition)

[Step 1: Acid leaching]

Mountain type And reducing agent type change

The following [Table 2] compares the leaching rate by changing the acid type (sulfuric acid, citric acid) and reducing agent type (H ₂ O ₂ , Na ₂ S ₂ O ₅ ) from the powdery positive electrode active material having the composition of [Table 1]. One result. When leaching for 2 hours at 80℃ using a solid-liquid ratio of 100 (g/l) of the positive electrode active material with sulfuric acid and citric acid and hydrogen peroxide as a reducing agent, the leaching rate of nickel in citric acid was 92% lower than that of sulfuric acid, but cobalt and The manganese leaching rate showed similar trends in both. In addition, when comparing the reducing agent with hydrogen peroxide (H ₂ O ₂ ) and sodium metabisulfite (Na ₂ S ₂ O ₅ ) under the sulfuric acid leaching conditions, it can be seen that the leaching rate of cobalt and manganese by hydrogen peroxide is excellent compared to the same equivalent weight. . When citric acid, which is an organic acid, is used as an acidic leaching agent, the pH after leaching is 6.3, which is weakly alkaline, so there is an advantage in that the use of an alkali agent used for subsequent neutralization and precipitation can be reduced.

Leach rate according to acid type and reducing agent type Mountain type reducing agent Acid concentration
(M) Reaction time (hr) Temperature
(℃) pH Co(g/L) Ni(g/L) Mn(g/L) Sulfuric acid H ₂ O ₂ 2.0 2 80 1.5 10.6 29.8 10.5 Sulfuric acid Na ₂ S ₂ O ₅ 2.0 2 80 0.7 9.6 27.9 8.8 Citric acid H ₂ O ₂ One 2 80 6.3 10.5 24.5 10.9

At roasting temperature Follow Leaching rate change

[Table 3] shows the cathode active material in sulfuric acid conditions using sodium metabisulfite (Na ₂ S ₂ O ₅ ) as a reducing agent after 1 hour roasting while changing the roasting temperature of the cathode active material from 500℃ to 700℃ in units of 100℃. This is the result of comparing the leaching efficiency. As the roasting temperature increased, the weight loss increased due to the decrease of organic matter such as carbon and separator, and the reduction effect of the NCM ternary cathode active material became active, so that when the same amount of reducing agent (Na ₂ S ₂ O ₅ ) was added, the roasting temperature increased. As it increased, the leaching rate tended to increase.

Leach rate according to roasting temperature Roasting temperature (℃) Weight loss(%) Concentration (g/L) Leach rate (%) Co Mn Ni Li Co Mn Ni Li none none 9.6 8.8 27.9 6.5 82.3 69.0 83.4 98.0 500 4.93 10.5 10.0 31.6 6.4 86.6 81.7 85.3 97.2 600 5.63 11.9 11.3 35.9 6.5 88.2 82.3 89.1 98.0 700 5.80 12.7 12.0 36.5 6.4 95.4 93.3 95.3 98.0

[Step 2: Removal of impurities]

In the first neutralization step after the leaching process, in order to reduce the consumption of alkali agents and to concentrate the NCM ternary cathode active material in the filtrate, an additional cathode active material powder was added to adjust the pH to 3.2. Accordingly, iron (Fe) components are effectively removed compared to copper (Cu) and aluminum (Al). In the first neutralization step, the cathode active material powder was added at a ratio of 10 to a solid-liquid ratio (mg/mL), and the reaction was performed at a reaction temperature of 70°C for 1 hour.

Then, in the second neutralization step, the first neutralization filtrate was raised to pH 6.5 by adding sodium hydroxide (NaOH) at room temperature to remove impurities such as copper (Cu), aluminum (Al), and iron (Fe) as hydroxide. On the other hand, when the pH is adjusted to 4.5 during the secondary neutralization, since copper and aluminum, which are impurities, are present in the solution at 154 ppm and 92 ppm, respectively, it is preferable to adjust the pH to 4.5 or more and 6.5 or less. Accordingly, the filtrate is secondary neutralized to remove impurities, and this secondary neutralization can be carried out at room temperature around 25±2℃, and the primary neutralization process along with copper (Cu) and aluminum (Al) components is a reduction condition. Fe (II) form of iron (Fe) component that has been partially remaining in the state can be removed during the secondary neutralization process.

Neutralization process (impurity removal) Unit (mg/L) pH Fe Cu Al Mg Ca Li Co Mn Ni 1st neutralization 3.2 48.6 1,206 481 5.9 9.2 10,490 15,020 13,930 43,840 Secondary neutralization 4.5 16 154 92 2.2 8.6 10,080 13,630 12,790 39,740 6.5 ND ND 0.2 2.1 5.7 9,975 12,850 11,360 37,800

(ND: Not Detected)

[Step 3: Recovery of ternary co-precipitates and washing with water]

The process of co-precipitation of nickel (Ni)-cobalt (Co)-manganese (Mn) by adding alkali agents such as sodium carbonate (Na ₂ CO ₃ ), sodium hydroxide (NaOH), potassium hydroxide (KOH), etc. to the filtrate from which impurities have been removed. to be. The reaction temperature is carried out at room temperature around 25℃ and in the range of pH 9.5 to 10.5 where manganese can be recovered when the alkali agent is a hydroxide, and between pH 8 and 9 or less at which nickel can be finally recovered when the alkali agent is a carbonate compound. Perform (Graphs 1 and 2).

[Graph 1] Solubility of Metal-Hydroxide (25℃, 1atm)

[Graph 2] Solubility of Metal-Carbonate (25℃, 1atm)

[Table 5] and [Table 6] show that nickel, cobalt, and manganese as ternary cathode active materials are recovered by co-precipitation with carbonate and hydroxide, respectively, after the neutralization process for impurities removal, and then the removal of impurities such as lithium and sodium from the coprecipitates. This is the result of performing water washing. When coprecipitation with carbonates shown in [Table 5], the final pH was adjusted to 9, reacted at room temperature for about 1 hour, and after filtration, the concentrations of nickel, cobalt and manganese to be recovered in the solution were less than 100 ppm. Among them, carbonates with the highest solubility The nickel concentration was the highest at 98ppm. The recovered coprecipitate was washed with water four times, and the concentration of lithium and sodium in the solution (washing efficiency) decreased as the number of washings increased. Meanwhile, in the case of the hydroxide coprecipitation shown in [Table 6], the coprecipitation reaction was performed at room temperature by adjusting the pH to 9.5. After filtration, the total concentration of cobalt, nickel, and manganese was about 10 ppm in the filtrate, and the loss rate was lower than that of carbonate coprecipitation. In addition, loss of nickel, cobalt, and manganese during the washing process was relatively lower than that of carbonate, and only lithium and sodium were selectively removed.

NCM carbonate-water washing division division Co Fe Mn Ni Ca Al Li Na unit NCMCO ₃ precipitation Filtrate 14 ND 41 98 2 0.3 6,188 35,310 ppm NCMCO ₃ cake 1st washing ND ND 5.2 30 0.1 0.01 1,805 11,940 2nd washing ND ND 2.8 ND 0.1 0.01 443 3,850 3rd washing 33 ND ND ND 0.1 0.01 135 1,134 4th washing ND ND 3.2 ND 0.1 0.01 63 523

NCM hydroxide-water washing division division Co Cu Fe Mn Mg Ca Al Ni Na Li unit NCM(OH) ₂ precipitation Filtrate 3 ND ND 9 One 31 ND 1.0 19,360 6,627 ppm NCM(OH) ₂ cake 1st washing 2 ND ND 11.0 4.6 54 ND 2.7 5,896 1,301 2nd washing One ND ND 16.0 ND 25 ND ND 1,840 345

[Step 4: Re-dissolving sulfuric acid]

A complex sulfate solution was prepared by adding hydrogen peroxide as a small amount of reducing agent and re-dissolving it with sulfuric acid in order to reduce some oxidized cobalt, manganese, nickel, etc. of the wet cake recovered through water washing after coprecipitation of ternary NCM carbonate/hydroxide. As can be seen from the analysis results of the sulfate solution shown in [Table 7], the impurities excluding cobalt, manganese, and nickel to be recovered were recovered to a level that satisfies the required specifications of the precursor of less than 5,000 ppm of sodium and 400 ppm of lithium.

NCM carbonate/hydroxide-sulfuric acid re-dissolution division pH Co Cu Fe Mn Mg Ca Al Ni Na Si Li unit NCMCO ₃ sulfuric acid dissolution 3.0 17,190 ND ND 16,290 ND 25 4.4 47,760 474 ND 27 ppm NCM(OH) ₂ sulfuric acid dissolution 3.9 17,216 ND ND 10,774 0.02 3.0 0.4 51,250 301 ND 61

[Step 5: Lithium recovery]

In [Table 5] and [Table 6], the concentration of lithium remaining in the filtrate after coprecipitation with NCMCO ₃ and NCM(OH) ₂ is about 6,100 ~ 6,600 ppm, which is present in a fairly concentrated amount. In order to recover lithium from this, lithium recovered after 1 hour reaction at a reaction temperature of 70°C by adding about 1.2 equivalents of tribasic sodium phosphate (Na ₃ PO ₄ ) based on the concentration of lithium is 16wt, as shown in [Table 8]. %, and when converted to lithium phosphate (Li ₃ PO ₄ ) based on lithium concentration, it was recovered with a purity of about 89%. After lithium recovery, the concentration of lithium remaining in the filtrate was about 455ppm, and more than 93% of lithium could be recovered from the filtrate after coprecipitation.

Li ₃ PO ₄ recovery division pH Reaction temperature Li ₃ PO ₄ recovery (unit: mg/kg) Li in filtrate (mg/L) Na Mg Ca Li Li ₃ PO ₄ 11 70 24,600 0.7 0.6 160,100 455

Due to the method of manufacturing a mixed metal compound for preparing a precursor from the waste cathode active material powder, the waste anode active material powder generated from the waste lithium secondary battery is converted to nickel, cobalt, and manganese compounds through a solvent extraction process, which is a conventional wet treatment method. They are not separated and recovered, but are recovered as their co-precipitate, and the co-precipitate is redissolved in sulfuric acid. Accordingly, the finally obtained sulfuric acid compound having various molar ratio compositions, such as nickel, cobalt, and manganese, can be reused in the precursor manufacturing process by adjusting the molar ratio of nickel, cobalt, and manganese, thereby improving economic efficiency.

In addition, according to the present invention, the leaching rate increases as the roasting temperature increases by roasting the waste cathode active material powder at 500°C or more, and lithium (Li) in the filtrate other than the coprecipitate can be recovered, and the filtrate after the neutralization step Calcium (Ca) can be removed from

In addition, according to the present invention, the amount of the reducing agent added in the acid leaching process is added in a ratio of 0.4 to 0.7 relative to the equivalent of the reducing agent, and the concentration of the acidic leaching agent is (cobalt (Co) + nickel (Ni) + manganese (Mn)). Adjust the molar concentration to 1.5 ~ 2 times the molar concentration to adjust the pH of the filtrate after leaching to be 0.7 ~ 1.5, and if the leaching reaction temperature is 50 ~ 95 ℃ (cobalt (Co) + nickel (Ni) + manganese ( The leaching rate of Mn)) can be increased.

In addition, according to the present invention, in the course of coprecipitation, the reaction temperature is 25±2℃, when the alkali agent is a hydroxide, the pH 9.5 to 10 at which manganese (Mn) can be recovered, and when the alkali agent is a carbonate compound, nickel (Ni) is finally recovered. It is possible to perform in a pH range of 8 to 9 or less so that nickel (Ni)-cobalt (Co)-manganese (Mn) can be co-precipitated at the same time.

In addition, according to the present invention, some of the co-precipitates of nickel (Ni)-cobalt (Co)-manganese (Mn) recovered through the co-precipitation process are partially oxidized to remove the co-precipitates that may exist in a trivalent state using a reducing agent. I can.

In addition, according to the present invention, the waste anode active material powder is added to the leaching filtrate generated through the acid leaching process so that the leaching filtrate has a pH of 3.0 to 3.5, and the first neutralization is performed at a reaction temperature of 50 to 70°C for 0.5 to 1 hour. Through the process and a second neutralization process of pH 4.5 ~ 6.5 by adding an alkali agent to the first neutralization filtrate at room temperature, impurities such as iron (Fe), copper (Cu), and aluminum (Al) are removed as hydroxide. I can.

In addition, according to the present invention, it is possible to recover valuable metals economically and efficiently compared to the conventional solvent extraction process, and in the case of lithium, a much higher concentration (Li> than the recovery concentration (Li <3g/L) of the solvent extraction process) 7g/L), it is possible to consequently increase the recovery rate of lithium and reduce the cost of the concentration process.

Claims (6)

In the method for producing a mixed metal compound for preparing a precursor from waste cathode active material powder,
(a) Acidic leachants and H ₂ O ₂ , SO ₂ , Na ₂ S ₂ O ₅ , NaHSO ₃ , Na ₂ SO ₃ , KHSO ₃ , K ₂ SO ₃ , FeSO ₄ , H ₂ S, ascorbic acid ), leaching the waste cathode active material powder using at least one reducing agent of glucose;
(b) reacting by additionally adding positive electrode active material powder at a high-liquid ratio of 100 to 150 (g/L) to the leached filtrate;
(c) removing a hydroxide compound of copper (Cu), aluminum (Al), and iron (Fe) at pH 6.3 to 6.5 by adding an alkali agent containing at least one of NaOH and KOH to the reacted filtrate;
(d) The filtrate from which hydroxide compounds of copper (Cu), aluminum (Al), and iron (Fe) have been removed contains at least one of sodium carbonate (Na ₂ CO ₃ ), sodium hydroxide (NaOH), and potassium hydroxide (KOH) Co-precipitation of nickel (Ni)-cobalt (Co)-manganese (Mn) by introducing an alkali agent; And
(e) washing the co-precipitate with water, and dissolving the washed co-precipitate in a sulfuric acid solution to prepare a complex sulfate solution containing the mixed metal compound.
The method of claim 1,
Roasting the waste cathode active material powder at 500°C or higher before step (a);
Recovering lithium (Li) in the filtrate other than the coprecipitate in step (d) at 25°C to 90°C; And
After the step (b), adding a fluorine compound containing NaF and NH ₄ F to remove calcium (Ca) from the filtrate with CaF _{2 A} method for producing a mixed metal compound, characterized in that it further comprises.
The method of claim 1,
The leaching of step (a),
The amount of the reducing agent added is added in a ratio of 0.4 to 0.7 relative to the equivalent amount of the reducing agent required to reduce (cobalt (Co) + nickel (Ni) + manganese (Mn)) contained in the waste cathode active material powder, and the concentration of the acidic leachant Is adjusted to a molar concentration of 1.5 to 2 times the molar concentration of (cobalt (Co) + nickel (Ni) + manganese (Mn)) contained in the leached filtrate so that the pH of the filtrate after leaching is 0.7 ~ 1.5 And, the leaching reaction temperature is 50 ~ 95 ℃ method for producing a mixed metal compound, characterized in that.
The method of claim 1,
The coprecipitation of step (d),
It is carried out at a reaction temperature of 25±2℃,
When the alkali agent is a hydroxide, it is carried out at a pH of 9.5 to 10 where manganese (Mn) can be recovered, and when the alkali is a carbonic acid compound, it is carried out at a pH of 8 to 9 or less at which nickel (Ni) can be finally recovered. Method for producing a mixed metal compound, characterized in that to be.
The method of claim 1,
The step of preparing the complex sulfate solution of step (e),
The water washing temperature for removing sodium (Na) and lithium (Li) co-existing in the co-precipitate is washed with water at least two times at a rate of 500 to 1,000 (g/L) of the co-precipitate at a high-liquid ratio of 500 to 1,000 (g/L) at 25°C to 50°C Step to do; And
A method for producing a mixed metal compound comprising the step of adding a reducing agent to the complex sulfate solution to a pH of 3.5 to 4.
The method of claim 1,
The step of reacting in step (b),
The waste cathode active material powder is added so that the leachate has a pH of 3.0 to 3.5, and the method for producing a mixed metal compound is performed at a reaction temperature of 50 to 70°C for 0.5 to 1 hour.

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