KR102341658B1 - Recovery of valuable metals from spent lithium ion battery leaching solution - Google Patents

Abstract

It is an object of the present invention to provide a method for extracting and recovering an economical valuable metal from a waste lithium ion battery leachate. In order to achieve the above object, in the present invention, (a) preparing a waste lithium ion battery leachate containing a plurality of metal ions including copper ions using sulfuric acid, (b) organic phosphorus in the leachate It provides a method for extracting valuable metals from a spent lithium ion battery, comprising the steps of selectively extracting copper ions by adding an acid-based copper extractant and (c) extracting valuable metals from the filtrate remaining after the extraction of copper ions.

Description

Method for recovering valuable metals from spent lithium ion battery leaching solution

The present invention relates to a method for recovering valuable metals from a leachate of a spent lithium ion battery, and more particularly, to a method for recovering valuable metals in an economical manner with high purity after first extracting and removing copper ions from the leachate.

Lithium-ion batteries are composed of 5-20% cobalt, 5-10% nickel, 5-7% lithium, 1-5% manganese, 15% organic chemicals and plastics, depending on the manufacturing process. Therefore, it is very important to recover the valuable metals contained in the waste lithium ion battery in the production of electrode materials for secondary batteries. The recovery of valuable metals from spent lithium ion batteries consists of pretreatment, heat treatment and chemical processes. At this time, chemical processes are roughly divided into dry and wet methods. In order to recover copper, nickel, cobalt and lithium with high purity, separation and purification by a wet method is required.

For the wet method, hydrochloric acid and sulfuric acid are mainly used as leaching liquids. Among them, hydrochloric acid can selectively separate nickel, a valuable metal, but for this purpose, high concentration conditions are required and it is disadvantageous in terms of price.

Since the concentration of sulfuric acid in the leachate of a spent lithium ion battery using sulfuric acid is about 2M and valuable metal ions exist as cations, an organic phosphoric acid extractant is mainly used for separation and purification. D2EHPA, PC 88A, and Cyanex 272 are representative organic phosphoric acid extractants. These extractants are weak acids and are difficult to use immediately in a strong acid sulfuric acid extraction solution. Accordingly, the leachate is neutralized to pH 3 or higher, and extraction and washing are performed in several steps. It goes through a step of separation and purification. Such a process consumes too much reagent for neutralizing sulfuric acid leachate and adversely affects economic feasibility, such as an increase in operating cost due to a complicated process.

On the other hand, due to the importance of nickel (II) and cobalt (II) separation, many research results have been published on separation by solvent extraction from various inorganic acid solutions. Therefore, many processes have been developed for simultaneously extracting nickel (II) and cobalt (II) from the sulfuric acid leachate of a spent lithium ion battery. However, it is not easy to selectively extract nickel (II) and cobalt (II) under a condition in which copper (II) and manganese (II) are mixed. The manganese content in the spent lithium ion battery is very low compared to other valuable metals. Therefore, if copper (II) is selectively extracted from the sulfuric acid leachate of a spent lithium ion battery, nickel (II) and cobalt (II) can be easily separated in a subsequent process. Research results for the selective extraction of copper (II) have not yet been reported.

Republic of Korea Patent Publication No. 10-0644902

It is an object of the present invention to provide a method for extracting and recovering an economical valuable metal from a waste lithium ion battery leachate.

In order to achieve the above object, in the present invention, (a) preparing a waste lithium ion battery leachate containing a plurality of metal ions including copper ions using sulfuric acid, (b) organic phosphorus in the leachate It provides a method for extracting valuable metals from a spent lithium ion battery, comprising the steps of selectively extracting copper ions by adding an acid-based copper extractant and (c) extracting valuable metals from the filtrate remaining after the extraction of copper ions.

According to the present invention, it is possible to recover economically valuable metals such as cobalt or nickel metal with high purity from the leachate of a spent lithium ion battery.

1 shows the extraction rate of metal ions from the leachate of a waste lithium ion battery according to various sulfuric acid concentrations.
Figure 2 shows the metal ion extraction rate according to the concentration of Cyanex301 at a sulfuric acid concentration of 0.01 M.
Figure 3 shows the metal ion extraction rate according to the concentration of Cyanex301 at a sulfuric acid concentration of 1.0 M.
Figure 4 shows the metal ion extraction rate according to the concentration of Cyanex301 at a sulfuric acid concentration of 2.0 M.
5 shows the metal ion extraction rate according to the concentration of Cyanex301.
Figure 6 shows the metal ion extraction rate according to the concentration of Cyanex301 after the addition of TBP 0.5M.
7 shows the copper ion stripping efficiency according to the type and concentration of the inorganic acid.

Hereinafter, the configuration and operation of the embodiment of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, when a part 'includes' a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

In the present invention, in order to wetly extract valuable metals from a waste lithium ion battery, (a) preparing a waste lithium secondary battery leachate containing copper ions and a plurality of metal ions using sulfuric acid, (b) in the leachate It provides a method for extracting valuable metals from a spent lithium ion battery comprising the steps of selectively extracting copper ions by adding an organophosphate-based copper extractant and (c) extracting valuable metals from the filtrate remaining after extraction.

In addition, there is provided a method for extracting valuable metals from a spent lithium ion battery, wherein the sulfuric acid concentration of the leachate is 0.01 to 3.0 M.

As a method of extracting valuable metals using sulfuric acid from a spent lithium-ion battery, a sulfuric acid leachate containing valuable metals is prepared, and only copper is first selectively extracted and removed from here, and then valuable metals are extracted from the remaining filtrate. The sulfuric acid leachate of spent lithium ion batteries contains not only economical cobalt and nickel, but also copper. It is technically very difficult to selectively extract only cobalt and nickel by separating from copper.

To solve this problem, rather than extracting only cobalt and nickel from the sulfuric acid leachate at once, it is easier to extract and remove only copper from the sulfuric acid leachate first, and then extract economical valuable metals such as cobalt and nickel from the remaining filtrate. metal can be recovered.

At this time, the concentration of sulfuric acid used in the leachate is preferably 0.01 to 3.0 M. As is well known even at a low concentration such as 0.01 M, adding an oxidizing agent such as hydrogen peroxide can dissolve the valuable metal components smoothly, and The higher the concentration, the lower the extraction rate of metal ions other than copper ions, so it is preferable to selectively extract only copper ions.

In the present invention, in the step (b), the copper extractant is bis(2,4,4-trimethyl-pentyl)dithiophosphonic acid (bis(2,4,4-trimethyl-pentyl)dithiophosphonic acid, Cyanex301) Provided is a method for extracting valuable metals from phosphorus and waste lithium ion batteries.

In addition, there is provided a method for extracting valuable metals from a spent lithium ion battery in which the concentration of the bis(2,4,4-trimethyl-pentyl)dithiophosphonic acid added to the leachate is 0.05 to 0.3 M.

As the copper extractant, bis(2,4,4-trimethyl-pentyl)dithiophosphonic acid (bis(2,4,4-trimethyl-pentyl)dithiophosphonic acid, Cyanex301) may be used. Cyanex301 is a strong acid compared to other organic phosphoric acid extractants, so it has the advantage of being able to extract metal ions even in strong acid solutions such as sulfuric acid solutions. In addition, the inventor found that, when Cyanex301 was used, the extraction rate of copper ions and the extraction rates of other metal ions showed a large difference in the extraction rates for copper, nickel, cobalt, manganese, and lithium ions contained in the leachate of the spent lithium ion battery. . Therefore, it is possible to preferentially remove copper ions from the leachate of a waste lithium ion battery by using these characteristics.

At this time, it is preferable that the concentration of Cyanex301 is in the range of 0.05 to 0.3 M, but the extraction of copper ions must be more than 0.05 M for smooth copper ion extraction. , nickel, manganese, and lithium ions are undesirable because the extraction rate increases. Therefore, the preferred concentration of Cyanex301 is 0.05-0.3M.

In addition, in the present invention, it is possible to provide a method for extracting valuable metals from a waste lithium ion battery by additionally adding tributyl phosphate (TBP) in step (b).

If Cyanex301 is used as an extractant and TBP (Tributyl Phosphate) is additionally added to selectively remove copper ions from the spent lithium ion leachate, there is no significant difference in the copper extraction rate. The extraction rate for copper is greatly reduced, which is advantageous for selectively removing only copper.

In addition, when Cyanex301 is used as a copper extractant in the present invention, the volume of the aqueous phase in step (b) is larger than the volume of the organic phase. It provides a method of extracting valuable metals from a lithium ion battery. .

For copper extraction, an organic phosphoric acid extractant such as Cyanex301 is used, and for this, a certain organic phase is required. Therefore, in the copper ion extraction step, an organic phase is added to the waste lithium ion battery leachate of the aqueous phase. As a result of examining the extraction rates of metal ions according to the volume ratios of various organic phases and aqueous phases, when the volume of the aqueous phase is larger than the volume of the organic phase, the It was confirmed that only copper can be selectively extracted without extraction.

In addition, in the present invention, the copper ions extracted by combining with the copper extractant in step (b) in the present invention are stripped through an acidic solution containing nitric acid or aqua regia. An extraction method is provided.

Copper extracted by combining with a copper extractant is not extracted by simple ion exchange, but rather through a complex of a copper extractant and a strong bond. Therefore, it is preferable to use a strong inorganic acid to remove copper ions from these bonds. The inventor has confirmed that nitric acid is an effective inorganic acid for copper ion stripping.

Silver nitrate has oxidizing power even at room temperature by generating oxygen gas as shown in Equation (1) below. The oxygen gas generated in this way oxidizes and deteriorates the copper extractant, so that the copper ions in the bound state can be removed.

2HNO ₃ (l) = 2NO ₂ (g) + 0.5O ₂ (g) + H ₂ O(l) Formula (1)

On the other hand, it was confirmed that aqua regia containing nitric acid in addition to nitric acid was effective in removing copper ions.

In addition, in the present invention, the extraction of the valuable metal in step (c) is saponified by adding di-(2-ethylhexyl)phosphoric acid (D2EHPA), followed by lithium at pH 4 or higher. It provides a method for extracting valuable metals from a waste lithium ion battery, including extracting divalent metal ions other than ions.

After the copper ions are removed, a process of finally extracting valuable metals is required. For this, economical cobalt or nickel metal ions can be extracted using an extractant such as D2EHPA. In this case, the pH of the solution is preferably 4 or more.

[Example]

Selective leaching of copper ions

_{Analytical reagent CoSO 4} ·7H ₂ O (Duksan Chemical, > 98%), CuSO ₄ ·H ₂ O (Duksan Chemical, > 99%), Li ₂ SO in distilled water to simulate the sulfuric acid leachate of a spent lithium ion battery ·4H ₂ O (Junsei Chemical, >99%), MnSO ₄ ·H ₂ O (Duksan Chemical, > 98.5%), NiSO ₄ ·6H ₂ O (Daejeonghwageum, 98.5%) was dissolved. Table 1 shows the composition of the simulation solution prepared in this way. The composition was measured using an Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES).

element
Co(II) Cu(II) Li(II) Mn(II) Ni(II) Concentration (g/L)
24 0.78 3 0.015 0.035

As an extractant for the selective extraction of copper ions, Cyanex 301 (Cytec Industries, Ltd., 70%) was used.

First, in order to determine the copper extraction rate according to the sulfuric acid concentration, the metal ion extraction rate was measured by adding 0.5M Cyanex301 while changing the sulfuric acid concentration from 0.01M to 2M, and the results are shown in FIG. 1 .

As the concentration of sulfuric acid increased, the extraction rate of copper ions did not change, but it was confirmed that the extraction rate of metal ions other than copper tends to decrease. Although the concentration of sulfuric acid showed a high copper extraction rate even at a very low 0.01M level, the extraction rate for cobalt and nickel ions was also high.

2 to 4 show the results of measuring the extraction rates of metal ions while varying the concentrations of Cyanex301 at sulfuric acid concentrations of 0.01M, 1.0M, and 2.0M, respectively. Regardless of the concentration of sulfuric acid, when the concentration of Cyanex301 is over 0.05M, the copper extraction rate approaches 100%, but the extraction rate of metal ions other than copper shows a tendency to increase as the concentration of Cyanex301 increases. However, as the concentration of sulfuric acid increased, the increase in the extraction rate of metal ions other than copper according to the increase in the concentration of Cyanex301 decreased.

Therefore, for the selective extraction of copper ions, it is preferable that the extraction rate of copper ions is high and the extraction rates of other metal ions are low, so that the high sulfuric acid concentration is advantageous for the selective extraction of copper ions.

In addition to Cyanex301 as a copper extractant, TBP was added to measure the extraction rate of metal ions.

5 shows the change in the extraction rate according to the concentration when only Cyanex301 is added, and FIG. 6 shows the change in the extraction rate according to the concentration when Cyanex301 and TBP are added together. The input concentration of TBP was 0.5M. In both cases, the pH of the initial leachate was adjusted to 3.

As can be seen in FIGS. 5 and 6 , when TBP was added together, the extraction rate of copper ions did not change when compared to the case where Cyanex301 was used alone, but it was seen that the extraction rates of other metal ions were greatly reduced.

Therefore, it was more effective to add Cyanex301 and TBP together as a copper extractant in the copper extraction step to selectively extract only copper.

The extraction reaction of metal ions by Cyanex301 can be expressed as Equation (2) below.

M ²⁺ _(aq) + (HA) _{2 (org)} = MA _{2 (org)} + 2H ⁺ _(aq) Equation (2)

In the above formula, (HA) ₂ represents a polymer of Cyanex301, and subscripts aq and org represent an aqueous phase and an organic phase, respectively. According to the above formula, as the concentration of hydrogen ions in the aqueous phase increases, the reverse reaction of the extraction reaction proceeds, thereby reducing the extraction rate of the metal.

Therefore, the volume ratio of the organic phase and the aqueous phase greatly affects the reaction, and the extraction rate of metal ions according to the volume ratio of the organic phase and the aqueous phase was measured, and this is shown in Table 2.

O/A ratio Cu(II),% Co(II),% Li(II),% Mn(II),% Ni(II),% 5:1 99.9 5.8 0.7 1.4 5.3 3:1 99.9 4.8 0.2 0.2 0.3 2:1 99.9 6.7 0 0 0 1:1 99.9 0 0 0 0 1:2 99.9 0 0 0 0 1:3 99.9 0 0 0 0 1:5 99.9 0 0 0 0

As can be seen in Table 2, when the ratio (O/A) of the organic phase to the aqueous phase was 1 or less, that is, when the volume of the aqueous phase was larger, the extraction rate of metals other than copper became 0. Therefore, in the copper extraction step, it is preferable for the aqueous phase to have a larger volume than the organic phase for selective copper extraction.

removal of copper ions

In order to strip copper ions forming a strong complex with Cyanex301, stripping rates were measured using various inorganic acids, and the results are shown in FIG. 7 .

As can be seen from FIG. 7 , copper ion stripping was not performed at all in sulfuric acid and hydrochloric acid, but in the case of nitric acid, copper ion stripping was performed at a concentration of 5M or more, and 99% or more copper ion stripping was performed.

In addition, the removal of copper ions was tested with aqua regia containing nitric acid, and it was confirmed that copper ions were removed even when the concentration of aqua regia was 5%.

Extraction of valuable metals

After removing copper ions from the leachate of the spent lithium ion battery, economical cobalt and nickel metal ions were extracted and recovered from the remaining filtrate. Valuable metals were extracted by adding D2EHPA and carried out at pH 4 or higher.

Claims (8)

(a) preparing a waste lithium ion battery leachate containing copper ions and a plurality of metal ions using sulfuric acid;
(b) selectively extracting copper ions from the leachate by adding an organophosphate-based copper extractant; and
(c) extracting valuable metals from the filtrate remaining after extracting copper ions,
Bis(2,4,4-trimethyl-pentyl)dithiophosphonic acid (bis(2,4,4-trimethyl-pentyl)dithiophosphonic acid, Cyanex301) and A method of extracting valuable metals from a waste lithium ion battery using TBP (Tributyl Phosphate) together. The method of claim 1,
The method for extracting valuable metals from a spent lithium ion battery, wherein the sulfuric acid concentration of the leachate is 0.01 to 3.0 M. delete The method of claim 1,
A method for extracting valuable metals from a spent lithium ion battery, wherein the concentration of Cyanex301 added to the leachate is 0.05 to 0.3M. delete The method of claim 1,
The volume of the aqueous phase (aqueous phase) in step (b) is greater than the volume of the organic phase (organic phase), a valuable metal extraction method from a waste lithium ion battery. The method of claim 1,
The method of extracting valuable metals from a waste lithium ion battery, further comprising the step of stripping the copper ions extracted by combining with the copper extractant in step (b) through an acidic solution containing nitric acid or aqua regia. The method of claim 1,
The extraction of valuable metals in step (c) is saponified by adding di-(2-ethylhexyl)phosphoric acid (D2EHPA), and then divalent excluding lithium ions at pH 4 or higher. A method for extracting valuable metals from a waste lithium ion battery, comprising the step of extracting metal ions.

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