KR20110056033A - Method for recovering cobalt from waste lithium ion battery - Google Patents

Abstract

PURPOSE: A method of recovering cobalt from a waste lithium ion battery is provided to recover high purity of cobalt by enhancing the removal of impurities and the recovery of cobalt. CONSTITUTION: A method of recovering cobalt from a waste lithium ion battery comprises next steps. Waste lithium ion battery powder is leached using sulfate reduction. After leaching using sulfate reduction, neutralization titration on leached solution is performed to remove impurities. After neutralization titration, oxidizer is added to remove Mn. The Mn removed solution is divided into solution and residue. Solvent leaching and reverse leaching on the divided solution are performed to recover cobalt.

Description

Cobalt recovery method from waste lithium ion battery {Method for Recovering Cobalt from Waste Lithium Ion Battery}

The present invention relates to a cobalt recovery method from a waste lithium ion battery, and more particularly, after the waste lithium ion battery sample is sequentially applied to the sulfuric acid reduction leaching, neutralization titration, solid-liquid separation and solvent extraction / back extraction process, A cobalt recovery method from a waste lithium ion battery, characterized in that the cobalt is recovered.

Lithium secondary batteries, which have recently increased in usage among lithium batteries, are composed of a cathode, an anode, an organic electrolyte, and an organic separator. In addition, lithium cobalt oxide, which has excellent reversibility, low self discharge rate, high capacity and high energy density, and is easily synthesized, is commercially available as a positive electrode active material.

In particular, lithium-ion batteries are widely used as a power source for small portable devices due to their light weight, and in recent years, demand for them has increased in proportion to the explosion of mobile communication terminals. In addition, as the demand for lithium ion batteries increases, the amount of generated lithium ion batteries is also rapidly increasing.

This waste lithium ion battery is simple in appearance and contains a large amount of valuable metals such as lithium and cobalt, which are relatively expensive as a cathode active material, and thus, it is recognized as an economically valuable waste resource and requires recycling.

However, in the case of a lithium ion battery employing lithium cobalt oxide as a cathode active material, valuable metals such as cobalt and lithium should be recycled, and for efficient recycling of lithium ion batteries, not only efficient recovery of valuable metals but also during recycling of waste lithium batteries Hazardous wastes generated should be properly disposed of.

In particular, during the mechanical treatment of waste lithium ion batteries, metal lithium is oxidized while reacting violently with moisture, which can be very dangerous. Therefore, in order to efficiently recover cobalt from waste lithium ion batteries, it is necessary to provide stable mechanical treatment and minimize harmful components It is important.

Accordingly, the present inventors have diligently tried to develop an efficient cobalt recovery method from waste lithium ion batteries. When applied sequentially, it was confirmed that high purity cobalt from which impurities were removed can be recovered, thereby completing the present invention.

It is an object of the present invention to provide an efficient cobalt recovery method from waste lithium ion batteries.

The present invention to achieve the above object, (a) sulfuric acid reduction leaching the waste lithium ion battery powder; (b) neutralizing the leaching solution obtained after the sulfuric acid reduction leaching in step (a) to remove impurities; (c) removing Mn by adding an oxidizing agent to the leaching solution neutralized in step (b); (d) solid-liquid separation of the solution from which Mn is removed in step (c) into a solution and a residue; And (e) recovering cobalt by solvent extraction and back extraction of the solid-liquid separated solution in step (d).

According to the present invention, while recovering cobalt from a waste lithium ion battery, cobalt of high purity can be recovered by increasing the removal rate of impurities and the recovery rate of cobalt.

The present invention in one aspect, (a) sulfuric acid reduction leaching the waste lithium ion battery powder; (b) neutralizing the leaching solution obtained after the sulfuric acid reduction leaching in step (a) to remove impurities; (c) removing Mn by adding an oxidizing agent to the leaching solution neutralized in step (b); (d) solid-liquid separation of the solution from which Mn is removed in step (c) into a solution and a residue; And (e) recovering cobalt by solvent extraction and back extraction of the solution separated from the solid-liquid separation in step (d) (FIG. 1).

The waste lithium ion battery powder used in the present invention may be obtained by a physical treatment method of Korean Patent No. 860972, which is the prior patent of the present inventor, and it is preferable to use a powder having 0mesh <particle size <8mesh.

Waste lithium ion batteries contain a large amount of impurities in addition to valuable metals such as cobalt and lithium. Therefore, in order to remove impurities from the solution obtained after sulfuric acid reduction leaching of the lithium ion battery powder in step (a), neutralization titration is performed.

In the present invention, the neutralization titration of step (b) is a calcium compound selected from the group consisting of CaO, Ca (OH) ₂ and CaCO ₃ ; Alkaline solution which is NaOH or NH ₄ OH; And it may be characterized in that the pH is adjusted to 5.5 ~ 6.5 by the material selected from the group consisting of a mixture thereof.

Impurities that can be removed from the leaching solution by neutralization titration may be selected from the group consisting of Fe, Cu, Al and mixtures thereof, but is limited to impurities other than recyclable valuable metals such as Co and Li. It doesn't happen.

In the leaching solution from which impurities are removed by neutralization titration, Mn contained in the leaching solution can be removed using an oxidizing agent. At this time, the oxidizing agent of step (c) may be selected from the group consisting of air, oxygen, ozone, KMnO ₄ and NaClO, but is not limited to any oxidizing agent capable of removing Mn.

In addition, the residue includes not only impurities such as Fe, Cu, and Al, but also some Co, and after washing the residue separated in solid-liquid in step (d), recovering the remaining cobalt contained in the residue It may further include. On the other hand, impurities such as Fe, Cu, and Al contained in the residue other than Co are removed.

In addition, the present invention may further comprise the step of recovering gypsum by pickling the washed residue. The residue is pickled to recover high purity gypsum and the residues generated are discarded.

Meanwhile, after solid-liquid separation, Co can be recovered by solvent extraction and back extraction of the leaching solution from which Mn is removed by neutralization titration and oxidizing agent. Here, the reverse extraction is a reverse operation of the solvent extraction, and when the organic material is used as the extraction solvent, the reverse extraction is an operation of turning over the material extracted in the organic layer to the water layer.

At this time, the solvent used in the solvent extraction of step (e) is di-2-ethyl hexyl phosporic acid solvent, 2-ethyl hexyl phosponic acid solvent, mono-2-ethyl hexyl ester solvent, di-2,4 , 4-trimethyl penthyl phosphpinic acid solvent, di-2-ethyl hexyl phospinic acid solvent, di-2,4,4-trimethyl penthyl dithiophosphpinic acid solvent and di-2,4,4-trimethyl penthyl monothiophosphpinic acid solvent It may be characterized in that selected from the group consisting of.

In addition, the solvent used during the solvent extraction is preferably saponified by an alkaline solution, by using a 30 ~ 50% saponified solvent, it is possible to increase the recovery of Co and minimize the generation of impurities. In addition, saponification of the solvent used during the solvent extraction can prevent the pH change during solvent extraction to increase the efficiency of solvent extraction.

For example, the reaction of extracting and back-extracting (removing) Co using bis (2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272, Cytec Inc., USA) as a solvent is performed using the reaction formula (1). ) Wherein, R is C ₁₆ H ₃₄ PO ₂ ^- a.

Co ²⁺ + 2HR ↔ CoR ₂ + 2H ⁺ (1)

In this case, the Cyanex 272 has a molecular weight of 290, viscosity 142cp (25 ℃), specific gravity 0.92gm / cc (24 ℃) and purity of 85%, the molecular formula is C ₁₆ H ₃₄ PO ₂ H, has the same structure as formula (I).

(I)

(I)

As the reaction of Scheme (1) proceeds, the pH of the solid-liquid separated solution of step (e) decreases, so that the solvent used for extracting the solvent is used an alkaline solution such as NaOH, NH ₄ OH, etc. After saponification (Scheme (2)), it was used for solvent extraction (Scheme (3)).

HR + NaOH (or NH ₄ OH) ↔ NaR (or NH ₄ R) + H ₂ O (2)

Co ²⁺ + NaR (or NH ₄ R) ↔ CoR ₂ + 2Na ⁺ (or 2NH ₄ ⁺ ) (3)

Scheme (2) is a reaction scheme illustrating the saponification process of the solvent, and the H ⁺ ions of the solvent are replaced with Na ⁺ or NH ₄ ⁺ ions. Thus, when Co 2+ ions are extracted by the solvent as in Scheme (3), Since Na ⁺ or NH ₄ ⁺ ions substituted in 2) are discharged into the solution phase, the pH change of the solution can be prevented.

Hereinafter, the present invention will be described in more detail by way of examples. These examples are intended to illustrate the present invention in more detail, and it will be apparent to those skilled in the art that the scope of the present invention is not limited to these examples.

Example 1 Cobalt Recovery from Waste Lithium-ion Battery

1-1: sulfuric acid reduction leaching

As a leachate, 16 mesh waste lithium ion battery powder was leached using a mixed solution of 2M H ₂ SO ₄ solution and a reducing agent 6vol% H ₂ O ₂ . At this time, the reaction conditions were 60 ℃, the reaction rate 250rpm, solid solution ratio 100g / L and the reaction time 2hr, sulfuric acid reduction leaching the waste lithium ion battery powder.

At this time, the waste lithium ion battery powder was obtained by physical treatment as disclosed in Korean Patent No. 860972.

1-2: neutralization titration

To 500 mL of the leaching solution obtained after sulfuric acid reduction leaching in 1-1, neutralization titration was performed using 150 mL of 50% CaCO ₃ solution and 25 mL of 4M NaOH solution at room temperature with stirring at 400 rpm, and then the pH was adjusted to 6.

1-3: Mn removal using oxidant

After adding 1.75 ml of a 10% KMnO ₄ solution to 500 mL of the neutralized solution at 1-2, Mn was removed by stirring at 200 rpm for 10 minutes at room temperature. At this time, the concentration of Co in the solution Mn was removed was 19420mg / L.

As shown in Table 1, it was confirmed that the removal efficiency of Mn using the oxidant shows a high efficiency of 82.57%.

Mn removal efficiency by KMnO ₄ and valuable metal composition before and after Mn removal reaction (%) Solution analysis result Co Li Ni Cu Fe Al Mn Na Before reaction 14600 2230 27.34 1.95 1.37 0.92 12.07 4060 After reaction 14430 2180 26.94 0.95 0.638 0.41 2.104 3940 Removal rate (%) 1.16 2.24 1.46 51.28 53.43 55.43 82.57 2.96

Table 2 and Figure 2 shows the composition of the solution obtained in each process before solvent extraction, Example 1-1 (sulfuric acid reduction leaching solution), 1-2 (impact removal solution after neutralization titration) and 1-3 (solid-liquid separation) After the process of washing the residue after the end), the composition of the solution and the removal rate of each composition, it was confirmed that the Fe, Cu and Al were mostly removed.

Solution composition (ppm) before solvent extraction Co Li Ni Fe Mn Cu Al Ca Na K pH Example 1-1 24880 3000 37.94 159.5 16.06 782.7 1800 13 37.6 6.45 0.17 Example 1-2 13800 2040 14.84 0.429 5.75 0.422 3.4 480 4200 239.1 6.58 Example 1-3 9425 912 15.74 0.52 3.1 0.247 0.214 430 1570 75.4 5.72 Removal rate (%) 6.7 1.6 19.4 99.4 55.1 99.9 99.8 - - - -

1-4: solid-liquid separation

The leaching solution from which neutralization titration and Mn was removed at 1-3 was solid-liquid separated by a filter press, and separated into a solution and a residue. It is also possible to use filter paper instead of the filter press.

At this time, the residue is washed with distilled water, the residual Co contained in the residue is recovered and reused in the sulfuric acid reduction leaching step 1-1, impurities such as Fe, Cu, Al contained in the residue Removed.

1-5: solvent extraction and back extraction

The solvent (Co concentration 19420mg / L) obtained after solid-liquid separation at 1-4 was subjected to Co solvent extraction and stripping (back extraction) experiment using a Mixer-settler.

In Co solvent extraction and stripping (back extraction), 0.7 M bis (2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272, Cytec Inc., USA) 40% saponified with extraction solvent and H ₂ as stripping solvent SO ₄ was used. In this case, the Cyanex 272 is an organic phase (H ₂ SO ₄ ) is an aqueous phase (aqueous phase), the experiment was conducted under the condition that the flow rate of the water phase is 7.5ml / min at 0 / A (Organic / Aqueous) = 2 Was carried out. After Co solvent extraction and stripping experiment, the appearance after 3 hours was observed.

As a result, as shown in Figure 2, raffinate (raffinate) was confirmed that all cobalt was extracted colorless (Fig. 2 (c)), Cyanex 272 after stripping and the solvent after stripping (a The color of)) showed no cobalt. In addition, it was confirmed that extraction and removal were well performed without any occurrence of three phases. As a result of the extraction experiment up to 8 hours, it was found that the extraction reaction was relatively well under the condition that three phases did not occur in the mixer-settler. In this case, the three phase refers to a phase in which the organic phase and the aqueous phase are not separated by combining the organic phase and the aqueous phase in the form of an emulsion in the process of mixing the organic phase and the aqueous phase for solvent extraction.

Mixer-settler experiments using 40% saponified 0.7M bis (2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272, Cytec Inc., USA) solvent are shown in Tables 2, 3 and 4 below.

As a result, as shown in Table 3, after 8 hours in the Mixer-settler, Co loss of raffinate was confirmed that Co extraction rate of about 99.9% or more to about 1 ~ 2mg / L.

Raffinate Assay (mg / L) time Co Li Ni Cu Fe Mn Na K pH 2 316.7 2150 10.43 0.549 0.515 0.272 12080 9.34 6.28 3 118.6 1730 3.898 0.535 0.487 0.169 13150 7.65 6.87 4 33.15 1609 2.319 0.465 0.465 0.134 12890 10.94 6.97 5 7.115 1662 1.439 0.447 0.482 0.132 12920 7.56 6.96 6 3.171 1870 1.247 0.411 0.489 0.14 12410 7.62 7.08 7 2.291 2430 1.285 0.384 0.507 0.161 12310 8.12 6.91 8 1.654 2560 1.617 0.402 0.539 0.178 12650 8.8 6.9

As shown in Table 4, the Co content in the stripping solution was about 8.1%, but it was confirmed that Li contained 22 mg / L and Na 17.8 mg / L as impurities.

Analysis result of stripping solution (mg / L) time Co Li Ni Cu Fe Mn Na K 2 38420 10.2 1.842 10.5 1.234 5.47 59.7 1.878 3 41920 9.27 1.878 10.97 1.604 5.62 59.3 1.416 4 49440 10.3 1.921 11.42 1.526 5.95 53.2 2.037 5 58390 17.3 2.354 11.23 1.261 6.64 51.7 1.454 6 70070 18.7 2.431 12.27 1.16 7.52 30.8 2.002 7 73470 21.6 2.649 11.82 1.067 7.43 19.8 1.34 8 81240 22.0 2.663 12.34 1.063 8.72 17.8 0.833

In addition, as shown in Table 5, the Co content in the cobalt sulfate solution finally prepared after stripping was 96000 mg / L, the impurity content was 50.2 mg / L.

Composition of cobalt sulfate solution prepared after stripping (mg / L) Co Li Ni Cu Fe Mn Al Na Ca Sum of impurities Stripping liquid 96000 3.4 1.6 1.1 2.3 22 4 11.7 4.1 50.2

Experimental Example 1: Co extraction efficiency simulation test according to the degree of saponification of the solvent

For Mn-free solution (Co concentration 19420 mg / L) in Example 1-4, 0.7 M bis (2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272, Cytec Inc., USA) was used as an extraction solvent. Co extraction efficiency simulation test was conducted.

In order to compare the Co extraction efficiency according to the saponification degree of the extraction solvent, a two step count current simulation extraction test of 30%, 35%, 40% and 50% saponification solvent of 0.7M Cyanex 272 was performed. (FIG. 4).

As a result, as shown in Table 6, when the saponification degree of the extraction solvent is 40%, the total Co extraction efficiency is high, the extraction efficiency of Li and Ni is low, it was shown that the selective extraction of Co is possible.

Simulation test results of 30%, 35%, 40% and 50% saponified solvents of 0.7M Cyanex 272 (1st stage Raffinate: Raffinate obtained after 1st stage extraction, 2nd stage Raffinate: Raffinate obtained after 2nd stage extraction) mg / L Co Li Ni pH Stock solution 19420 2010 26.42 7.17 30%
1-stage Raffinate 18550 2050 25.64 3.97 2-stage Raffinate 2536 2540 45.7 4.6 35%
1-stage Raffinate 14670 2480 59.36 4.33 2-stage Raffinate 2.10 2390 8.465 6.49 40%
1-stage Raffinate 9300 3230 66.79 4.22 2-stage Raffinate 0.13 1720 1.003 7.05 50%
1-stage Raffinate 3020 2.82 0.0673 5.2 2-stage Raffinate 0.12 1.704 0.00087 7.03

Example 2: Recycling of residues generated during neutralization titration and Mn removal

In Example 1-2, the residue generated during neutralization titration and Mn removal was washed with distilled water, solid-liquid separation, residual Co was recovered, and the washing residue was separated. At this time, since the gypsum containing impurities remains as a solid, an experiment was performed to recover pure gypsum after removing impurities in the gypsum.

In order to remove impurities from the gypsum containing the impurity, 2M H ₂ SO ₄ was used for 1 hour at 60 ° C, 250 rpm solid solution ratio of 50g / 500mL reaction conditions.

As a result, as shown in Table 7 and Table 8, the impurity content in the gypsum obtained after leaching the pH-controlled residue was only 0.0547%, while as shown in Table 9 and Figure 5, the removal rate of the recovered gypsum is high It was confirmed that pure gypsum could be obtained.

In addition, as shown in Figure 6, it can be seen that the pure gypsum can also be obtained from the XRD analysis of the gypsum obtained after leaching the pH control residue.

In addition, as shown in Figure 7, it was confirmed that through the color change before and after the removal of impurities of the gypsum, pure gypsum can be obtained after the removal of the impurities.

Analysis result of pH adjustment residue (%) Co Mn Fe Ni Li Cu Na K Sum of impurities pH adjustment residue (raw sample)% 3.03 0.0325 0.105 0.0595 0.0285 1.684 0.0956 0.0074 5.0425

Impurity content of gypsum recovered after leaching (%) Co Mn Fe Ni Li Cu Na K Sum of impurities Purity of recovered gypsum (%) 0.003 0.001 0.0128 0.0057 0.0015 0.0046 0.0205 0.0056 0.0547

% Impurity removal of recovered gypsum relative to raw material impurity content Co Mn Fe Ni Li Cu Na K Remarks Impurity Removal Rate 99.83 94.46 86.67 90.92 94.04 99.52 76.15 20.27

Example 3: Regeneration of Solvent

Pickling and washing were performed to regenerate the 40% saponified 0.7M bis (2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272, Cytec Inc., USA) solvent used in the Mixer-settler experiment of Example 1-5. Was carried out. At this time, pickling was performed using a sulfuric acid solution of 2M, water washing was performed using distilled water.

As a result of analyzing the Na concentration of the washed acid solution and the distilled water wash solution of the solvent washed in the laboratory by sampling the solvents completed with pickling and washing, it was determined to be 0.2 mg / L. Therefore, almost no Na in the solvent, it was confirmed that all Na is washed off during the solvent regeneration process.

Na concentration in aqueous phase after pickling and washing of regenerated solvents (mg / L) Kinds Na concentration after pickling Na concentration after washing PH after washing Pickled and washed solvent samples 0.2 0.2 3.02

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

1 shows a process chart for recovering cobalt from a spent lithium ion battery.

Figure 2 is a graph showing the composition and impurity removal rate of the solution obtained in each step in the cobalt recovery method from the waste lithium ion battery.

3 is a photograph observing the state after the Co solvent extraction and stripping experiment (a: solvent after stripping, b: stripping solution, c: raffinate).

4 is a schematic diagram of Co recovery simulation test using 30% (a), 35% (b), 40% (c) and 50% (d) saponification solvent of 0.7M Cyanex 272.

Figure 5 is a graph showing the removal rate of impurities in the gypsum recovered by solid-liquid separation of the pH adjustment residue washed with distilled water when neutralization titration.

Figure 6 is a graph showing the XRD analysis of the gypsum recovered by the solid-liquid separation of the pH adjustment residue washed with distilled water when neutralization titration.

7 is a result of observing the color change before and after removing the impurities of the gypsum recovered by the solid-liquid separation of the pH adjustment residue washed with distilled water during neutralization titration.

Claims (9)

A cobalt recovery method from a waste lithium ion battery, comprising the following steps: (a) sulfuric acid reduction leaching of the spent lithium ion battery powder; (b) neutralizing the leaching solution obtained after the sulfuric acid reduction leaching in step (a) to remove impurities; (c) removing Mn by adding an oxidizing agent to the leaching solution neutralized in step (b); (d) solid-liquid separation of the solution from which Mn is removed in step (c) into a solution and a residue; And (e) recovering cobalt by solvent extraction and back extraction of the solid-liquid separated solution in step (d). The method of claim 1, wherein the neutralization titration of step (b) is selected from the group consisting of CaO, Ca (OH) ₂ and CaCO ₃ ; Alkaline solution which is NaOH or NH ₄ OH; And it is adjusted to pH 5.5-6.5 by the substance chosen from the group which consists of these mixtures. The method of claim 1, wherein the impurity of step (b) comprises selecting from the group consisting of Fe, Cu, Al, and mixtures thereof. The method of claim 1, wherein the oxidizing agent of step (d) is selected from the group consisting of air, oxygen, ozone, KMnO ₄ and NaClO. The method of claim 1, further comprising, after washing the residue solid-separated in step (d), recovering the remaining cobalt contained in the residue. 6. The method of claim 5, further comprising pickling the washed residue to recover gypsum. According to claim 1, wherein the solvent used in the solvent extraction of step (e) is di-2-ethyl hexyl phosporic acid solvent, 2-ethyl hexyl phosponic acid solvent, mono-2-ethyl hexyl ester solvent, di -2,4,4-trimethyl penthyl phosphpinic acid solvent, di-2-ethyl hexyl phospinic acid solvent, di-2,4,4-trimethyl penthyl dithiophosphpinic acid solvent and di-2,4,4-trimethyl penthyl Method selected from the group consisting of monothiophosphpinic acid solvent. 8. The method of claim 7, wherein the solvent is saponified by an alkaline solution. The method of claim 8, wherein the solvent is a 30-50% saponified solvent.

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