Method of extracting metal from salt solution derived from spent battery

Abstract

To provide a method of extracting a metal from a salt solution derived from a spent battery.SOLUTION: The method includes 1) preparing a salt solution derived from a waste battery containing ions of metals including Mn, Co, Ni, Li or a combination thereof; 2) preparing a metal-extractant mixture including a metal-extractant and a metal-extractant activator including LiOH; 3) bringing the metal-extractant mixture into contact with the salt solution to form a complex compound of the metal-extractant mixture and the metals and a first filtered solution; 4) recovering each of the complex compound and the first filtered solution; 5) bringing an acid into contact with the complex compound to form a metal-salt and a second filtered solution; 6) recovering each of the metal-salt and the second filtered solution; and 7) recovering the metal-extractant activator and the acid from the first filtered solution using an electrodialysis method.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for extracting metals from a salt solution derived from spent batteries.

Background Art

[0002] In recent years, environmental problems caused by the excessive use of fossil fuels have emerged as a global issue, and there is an increasing need for transportation means that use environmentally friendly alternative fuels instead of fossil fuels. Among such transportation means that use alternative fuels, the most rapidly spreading at present is the electric vehicle that utilizes electric energy.

[0003] An electric vehicle includes a battery as a device for supplying power to the vehicle. However, the battery has a short lifespan of several years to approximately 10 years at most because its maximum capacity decreases as it is used.

[0004] As the popularity of electric vehicles has rapidly progressed as described above, the amount of waste salts generated in the battery manufacturing process used for them has been increasing globally, and the amount of waste salts generated from spent batteries of electric vehicles that have reached the end of their lifespan has also been increasing.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] According to one aspect of the present disclosure, an object is to provide a method for extracting metals from a salt solution derived from spent batteries.

Means for Solving the Problems

[0007] The method for extracting metals from a salt solution derived from waste batteries according to the present disclosure comprises: 1) preparing a salt solution derived from waste batteries containing metal ions including Mn, Co, Ni, Li, or a combination thereof; 2) preparing a metal extractant mixture comprising a metal extractant and a metal extractant activator containing LiOH; 3) contacting the salt solution with the metal extractant mixture to form a complex compound of the metal extractant mixture and the metal, and a first filtrate; 4) recovering each of the complex compound and the first filtrate; 5) contacting the complex compound with an acid to form a metal salt and a second filtrate; 6) recovering each of the metal salt and the second filtrate; and 7) recovering the metal extractant activator and the acid from the first filtrate using electrodialysis.

[0008] According to one embodiment, the metal extractant may be an acidic metal extractant containing a -POOH functional group, a -COOH functional group, or a combination thereof.

[0009] According to one embodiment, in step 2), the metal extractant activator may be mixed in an amount of 0.2 to 1.0 mol per 1 mol of the metal extractant.

[0010] According to one embodiment, in step 3), the metal extractant mixture may be introduced in an amount of 2.0 to 4.0 mol per 1 mol of the metal ions in the salt solution.

[0011] According to one embodiment, the acid in step 5) may be sulfuric acid.

[0012] According to one embodiment, in step 5), the acid may be introduced in an amount of 1.0 to 2.0 mol per 1 mol of the complex compound.

[0013] According to one embodiment, the electrodialysis method in step 7) may be performed using a bipolar membrane, a cation membrane, an anion membrane, or a combination thereof.

[0014] According to one embodiment, the method may further include recycling the recovered metal extractant activator to step 2).

[0015] According to one embodiment, the acid recovered in step 7) may be recycled to step 1).

[0016] According to one embodiment, the method may further include removing impurities contained in the first filtrate before the metal extractant activator and acid recovery steps using electrodialysis.

[0017] According to one embodiment, the impurity removal step may include precipitation, adsorption, oxidation, ion exchange, or a combination thereof.

Advantages of the Invention

[0018] According to one embodiment of the present disclosure, valuable metals can be recovered from a salt solution derived from waste batteries while minimizing the generation of waste salts, thereby suppressing environmental pollution.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0020] Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings. However, this is merely exemplary, and the present disclosure is not limited to the specific embodiments described by way of example.

[0021] Referring to FIG. 1, a method for extracting metals from a salt solution derived from a spent battery according to an embodiment is provided.

[0022] The method for extracting metals from a salt solution derived from a spent battery of the present disclosure includes a step of preparing a salt solution derived from a spent battery containing metal ions (step 1), and the metals include Mn, Co, Ni, Li, or a combination thereof. The salt solution derived from a spent battery refers to a salt solution derived from a pretreatment process for recovering reusable metal parts from a spent battery after the battery life has ended, and the salt solution derived from the spent battery can be derived from, for example, a valuable metal recovery process of a spent lithium battery containing Ni, Co, Mn, Li, or a combination thereof. Preferably, the used lithium battery is LiCoO 2 (LCO), LiFePO 4 (LFP), LiMn 2 O 4 (LMO), LiNiMnCoO 2 (NMC), LiNiCoAlO 2 (NCA), LiMnO 2 , LiSOCl 2 , LiFeS 2 , or a combination thereof. Specifically, the pretreatment process may be a process of recovering black powder containing the cathode active material from the scrap of the spent battery and then performing acid treatment to generate a salt solution containing metal ions. The salt solution thus generated corresponds to the salt solution derived from the spent battery, which contains metal ions derived from the metals corresponding to the cathode active material of the spent battery. As described above, when the cathode active material contains Ni, Co, Mn, Li, or a combination thereof, the metals can include Mn, Co, Ni, Li, or a combination thereof. Also, the salt solution derived from the spent battery can include ions derived from the acid used in the pretreatment process. For example, when sulfuric acid is used in the pretreatment process, SO 4 2- ions can also be included. Referring to FIG. 1, the salt solution derived from the spent battery is represented by a Mn / Co / Ni / Li and SO 4 salt solution.

[0023] The above method includes a step (step 2) of manufacturing a metal extractant mixture including a metal extractant and a metal extractant activator, where the metal extractant activator includes LiOH. The metal extractant corresponds to a compound that is activated through reaction with the metal extractant activator and forms a complex compound with metal ions present in a salt solution derived from waste batteries, and the metal extractant activator corresponds to a compound that activates the functional group of the metal extractant. In the present disclosure, the metal extractant activator includes LiOH, specifically, the metal extractant activator may be LiOH. This is mixed with the metal extractant to form a metal extractant mixture. In the metal extractant mixture, the metal extractant exists in a state where its functional group is activated by reaction with the metal extractant activator. As described above, the method of the present disclosure does not use a compound containing Na ions, such as NaOH, as the metal extractant activator, so hereinafter, the first filtrate does not contain Na. Thus, the method of the present disclosure + has the advantage that it does not require steps such as evaporation concentration, crystallization, water washing, and / or recrystallization for recovering and purifying Li salts from the Na 2 SO 4 -containing solution, and does not generate by-products such as Na 2 SO 4 .

[0024] In one embodiment, the metal extractant may be an acidic metal extractant containing a -POOH functional group, such as D2HEPA (di-2-ethylhexylphosphoric acid), Cyanex 272 (bis(2,4,4-trimethylpentyl)phosphinic acid), PC88A (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester), Ionquest 801, DEHPA (diethylhexylphosphoric acid), a -COOH functional group, such as Versatic® 10 (neodecanoic acid), naphthenic acid, LIX 860, or a combination thereof. The acidic metal extractant containing a -POOH functional group and / or a -COOH functional group is used to extract metals such as Mn, Co, Ni from a salt solution. As shown in Figure 2, for the extractant containing a -POOH functional group, H at the end of the functional group is replaced by Li through an acid-base reaction with LiOH which is a metal extractant activator and is thus activated. Then, it can form a complex compound with metal ions (Co 2+ ) in the salt solution to extract the metal in the salt solution.

[0025] In one embodiment, in Step 2, the metal extractant activator can be mixed in an amount of 0.2 to 1.0 mol per 1 mol of the metal extractant. As shown in Figure 2, the metal extractant often contains one functional group per molecule. Thus, one molecule of the metal extractant reacts with one molecule of the metal extractant activator and is activated. When the metal extractant activator is mixed in an amount less than 0.2 mol per 1 mol of the metal extractant in Step 2, the activation of the metal extractant is not smooth. When the metal extractant activator is mixed in an amount exceeding 1.0 mol per 1 mol of the metal extractant, it may increase the pH of the salt solution and have an adverse effect on the efficiency of metal extraction. In one embodiment, in Step 2, the metal extractant activator can be mixed in an amount of 0.4 to 0.8 mol per 1 mol of the metal extractant, or in an amount of 0.5 to 0.6 mol per 1 mol of the metal extractant.

[0026] The above method includes the step of contacting the salt solution with a metal extractant mixture to form a complex compound of the metal extractant mixture and the metal, and a first filtrate (step 3). This is shown as the "formation of complex compound" step in Figure 1. In step 3, the two activated metal extractants contained in the metal extractant mixture contact one divalent metal ion in the salt solution to form a complex compound. The remaining components of the salt solution that do not participate in the formation of the complex compound correspond to the first filtrate. The complex compound is an oil phase, and the first filtrate is a water phase, and they are phase-separated by the density difference.

[0027] In one embodiment, in step 3, the metal extractant mixture can be introduced in an amount of 2.0 to 4.0 mol per mol of metal ions in the salt solution. As shown in Figure 2, since the metal ions in the salt solution mainly have an oxidation number of +2, they react with two molecules of the activated metal extractant to form a complex compound. If the metal extractant mixture is introduced in an amount of less than 2.0 mol per mol of metal ions in the salt solution in step 3, a large amount of metal ions that do not contribute to the complex compound formation reaction may remain in the salt solution, which may reduce the efficiency of metal extraction. If the metal extractant mixture is introduced in an amount exceeding 4.0 mol per mol of metal ions in the salt solution in step 3, the excess metal extractant mixture remains without reacting with the metal ions, which is uneconomical. In one embodiment, in step 3, the metal extractant mixture can be introduced in an amount of preferably 2.0 to 3.0 mol, or 2.2 to 2.5 mol per mol of metal ions in the salt solution, and more preferably in an amount along the pH isotherm curve of the target metal to be extracted.

[0028] The above method includes the step of recovering each of the complex compound and the first filtrate. The complex compound and the first filtrate are recovered so as to be separated from each other and undergo separate treatments as described below.

[0029] The above method includes the step (step 5) of contacting the complex compound with an acid to form a metal salt and a second filtrate. This is shown as the "metal salt formation" step in Figure 1. When the complex compound and the acid come into contact, as shown in Figure 2, the bond between the metal extractant functional group portion in the complex compound and the metal ion is broken, and the metal extractant is regenerated. At the same time, the metal ion is converted into the form of a metal salt. The metal salt is in a state of being dissolved in an aqueous solution (water phase) and is recovered by phase separation due to the density difference with the second filtrate in the oil phase. The second filtrate contains the regenerated metal extractant in which the metal extractant functional group portion of the complex compound is bonded to the H + ions of the acid, as shown in Figure 2.

[0030] In one embodiment, the acid in step 5 may be sulfuric acid, nitric acid, hydrochloric acid, or a combination thereof. The acid introduced into the complex compound is not limited as long as it can regenerate the metal extractant and recover the metal in the salt solution in the form of a metal salt. However, from the perspective of being able to recover the metal in the salt solution in the form of a metal sulfate, which is a raw material for manufacturing battery precursors, the acid is preferably sulfuric acid. Also, sulfuric acid can have the advantage of being inexpensive compared to other strong acids in terms of cost.

[0031] In one embodiment, in step 5, the acid can be introduced in an amount of 1.0 to 2.0 mol per mol of the complex compound in the complex compound. As shown in FIG. 2, when the acid contacting the complex compound in step 5 is sulfuric acid, one molecule of sulfuric acid breaks the bond between two metal extractant functional groups - metal ions present in the complex compound, and forms two molecules of metal extractant and one molecule of metal salt. In step 5, when the acid is introduced in an amount of less than 1.0 mol per mol of the complex compound in the complex compound, there may be molecules in which only part of the bond between the metal extractant functional group - metal ion in the complex compound is broken, so the amount of the recovered metal salt can be reduced. When the acid is introduced in an amount exceeding 2.0 mol per mol of the complex compound in the complex compound in step 5, the pH of the aqueous solution containing the metal salt becomes low due to the excess acid, and there are restrictions on the equipment in the subsequent metal salt concentration and crystallization steps. In one embodiment, in step 5, the acid can be introduced in an amount of preferably 1.0 to 1.5 mol, more preferably 1.0 to 1.2 mol, per mol of the complex compound in the complex compound.

[0032] The above method includes a step of recovering each of the metal salt and the second filtrate (step 6). The metal salt recovered here can be reused as a raw material for manufacturing battery precursors through separate concentration / crystallization and purification processes, and the recovered second filtrate can be recycled to step 3). In step 3), the metal extractant in the recovered second filtrate can react with the metal extractant activator in the metal extractant mixture to be activated and then contribute to the complex compound formation reaction.

[0033] The above method includes a step of recovering the metal extractant activator and the acid from the first filtrate respectively using electrodialysis (step 7). This is shown as the "electrodialysis" step in FIG. 1. In the step of recovering the metal extractant activator and the acid using electrodialysis, by applying a power source between two electrodes, the water component of the first filtrate is decomposed into H + and OH - and then, together with these, the ionic components or salts present in the first filtrate, such as Li 2 SO 4This is a step of combining and recovering in the forms of an acid and a base. The base recovered in the electrodialysis step corresponds to a metal extractant activator. The apparatus used in the electrodialysis step can be used without limitation as long as it can recover the acid and the base from the first filtrate. The high-concentration salts in the salt solution derived from waste batteries are separated in the electrodialysis step and recycled to the acid and the base, whereby the salt solution is partially desalted. The partially desalted salt solution (desalted water) is referred to as "diluted salt" in FIG. 1. The diluted salt is concentrated (to the "salt concentration" in FIG. 1) to the salt concentration level before the electrodialysis step (to the "concentrated water" in FIG. 1), and the concentrated water can be recycled to the electrodialysis step again.

[0034] In one embodiment, the step of recovering the metal extractant activator and the acid using the electrodialysis method can be performed using a bipolar membrane (BPM), a cation exchange membrane (CEM), an anion exchange membrane (AEM), or a combination thereof. The cation exchange membrane is a membrane composed of a polymer layer through which only cations can permeate, the anion exchange membrane is a membrane composed of a polymer layer through which only anions can permeate, and the bipolar membrane is a membrane in which a polymer layer through which cations can permeate and a polymer layer through which anions can permeate overlap. In one embodiment, the electrodialysis step can be performed using a bipolar membrane.

[0035] Referring to FIG. 3, the step of recovering the metal extractant activator and the acid using the electrodialysis method of the present disclosure is schematically shown. After water is decomposed into H + and OH - at the interface of the cation-permeable polymer layer - anion-permeable polymer layer of the bipolar membrane, among which, OH - combines with Li 2 ions generated by the decomposition of the Li 4 SO + salt to form the base LiOH, and H + combines with SO 2 generated by the decomposition of the Li 4 SO4 2- Combine with ions to form acid H 2 SO 4 To be able to generate. The existing membrane process is characterized in that the substances that can permeate through the membrane are selective, whereas in the case of the process using a bipolar membrane, the electrolysis reaction of water occurs at the interface where the cation-permeable polymer layer and the anion-permeable polymer layer are in contact, rather than on the surface of the electrode. Therefore, the bipolar membrane has the advantage that electrodialysis can be carried out by providing electrodes only at both ends of the membrane stack without the need to provide electrodes between each membrane, and operation is possible even at a lower voltage, so that the device design cost and the device operation cost can be reduced.

[0036] In one embodiment, the above method may further include a step (step 8) of recycling the recovered metal extractant activator to step 2. As described above, the first filtrate introduced into the electrodialysis contains Li, which is an ion remaining after the activation reaction of the metal extractant. + This reacts with OH generated by the electrolysis of water and is converted to the metal extractant activator LiOH. The metal extractant activator thus generated is the same as the metal extractant activator used in the metal extractant mixture preparation step (step 2), can be recovered and recycled to step 2. The recycled metal extractant activator can activate the functional groups of the metal extractant in the same manner as the existing metal extractant activator. On the other hand, the recycled metal extractant activator can be used for the activation of the metal extractant after passing through a concentration step if necessary. - -

[0037] In one embodiment, the recovered acid can be recycled to the step of preparing a salt solution derived from a waste battery containing metal ions (step 1). The anions constituting the acid recovered in the electrodialysis step are derived from the acid introduced in the pretreatment process for leaching the metal to prepare the salt solution in step 1. For example, if the acid introduced in the pretreatment process of step 1 is H 2 SO 4In the case of, SO 4 2- Ions are contained in the first filtrate and introduced into the metal extractant activator and acid recovery step using electrodialysis in step 7. In the metal extractant activator and acid recovery step using electrodialysis, SO 4 2- Ions are combined with H + produced by electrolysis of water to form H 2 SO 4 which is recovered and is the same as the acid introduced in step 1. Therefore, the acid recovered using electrodialysis can be recycled to step 1 and used in the pretreatment to leach metals to prepare the salt solution.

[0038] In one embodiment, the method may further include a step of removing impurities contained in the first filtrate before the metal extractant activator and acid recovery step using electrodialysis. This is shown as the "impurity removal" step in FIG. 1. The first filtrate may contain impurities derived from steps 1 to 5 in addition to Li + ions derived from the metal extractant and anions of the acid derived from step 5 (e.g., SO 4 2- ). Here, "impurities" refer to substances present in the aqueous phase in addition to the components constituting the acid and base recovered by electrodialysis in step 7, for example, the metal extractant slightly dissolved in the first filtrate in step 3, complex compounds, metal ions other than Li + remaining without being recovered in the form of metal salts, etc. The impurity removal step is not limited to the method as long as it can remove impurities.

[0039] In one embodiment, the impurity removal step can include precipitation, adsorption, oxidation, ion exchange, or a combination thereof. The precipitation can include coagulation precipitation. Coagulation precipitation is a process of separating a treatment liquid by making impurities present in a first filtrate precipitate by adding a chemical coagulant or by coarsening through electrocoagulation. More specifically, the coagulation step is a step of adding a chemical coagulant or eluting metal ions from an electrode to form a hydroxide of the metal ions, and forming aggregates through an aggregation reaction between such hydroxides and impurities present in the first filtrate. Here, the aggregate means a substance in which impurities present in the first filtrate are aggregated by electrocoagulation, and the treatment liquid means a liquid component after the aggregates are separated from the first filtrate.

[0040] The precipitation step after coagulation is a step of separating and removing aggregates from the treatment liquid by the density difference between the treatment liquid and the aggregates of the first filtrate. In one embodiment, the precipitation can be performed by known means for separating aggregates from the treatment liquid. For example, the precipitation can be performed by known means such as a sedimentation tank and a skimmer. After the precipitation step, the aggregates separated from the treatment liquid can be discarded or introduced into an additional treatment step, and the treatment liquid can be introduced into electrodialysis.

[0041] The adsorption is a step of adsorbing and removing impurities present in the first filtrate with an adsorbent. The adsorption is not limited to a method as long as it can separate the treatment liquid and the impurities. For example, it can be performed by filtration using a filter containing an adsorbent. The type of the adsorbent is not limited as long as it can adsorb impurities. For example, activated carbon can be used.

[0042] The oxidation step can be performed using a chemical substance. For example, the oxidation can include a step utilizing Fenton oxidation that generates hydroxyl radicals (OH radicals) through a catalytic reaction between impurities and hydrogen peroxide, or ozone oxidation that injects ozone. In addition to this, any process that oxidizes and removes harmful substances through an oxidation reaction can be used without limitation.

[0043] The ion exchange step corresponds to a step for separating polyvalent metal ions remaining in the treatment liquid. In the ion exchange step, the polyvalent metal ions in the treatment liquid are precipitated and separated in the form of salts by the introduction of an ion exchange cleaning solution.

[0044] As described above, the present disclosure has been described in detail by way of specific embodiments. The embodiments are for specifically explaining the present disclosure, and the present disclosure is not limited thereto. It is obvious that those having ordinary knowledge in the art can make modifications and improvements within the technical idea of the present disclosure.

[0045] Any mere change or modification of the present disclosure belongs to the scope of the present disclosure, and the specific protection scope of the present disclosure will be clarified by the appended claims.

Claims

1. 1. A method for extracting metals from a salt solution derived from waste batteries, comprising: 1) preparing a salt solution derived from waste batteries containing ions of metals including Mn, Co, Ni, Li, or combinations thereof; 2) providing a metal extractant mixture comprising a metal extractant and a metal extractant activator comprising LiOH; 3) contacting the salt solution with a metal extractant mixture to form a complex of the metal extractant mixture and a first filtrate; 4) recovering each of the complex and the first filtrate; 5) contacting the complex with an acid to form a metal salt and a second filtrate; 6) recovering each of the metal salt and the second filtrate; 7) recovering the metal extractant activator and the acid from the first filtrate using electrodialysis, respectively.

2. 2. The method for extracting metals from salt solutions derived from waste batteries according to claim 1, wherein the metal extractant is an acidic metal extractant containing -POOH functional groups, -COOH functional groups, or a combination thereof.

3. The method for extracting metals from a salt solution derived from waste batteries according to claim 1, wherein in step 2), the metal extractant activator is mixed in an amount of 0.2 to 1.0 mol per mol of the metal extractant.

4. The method for extracting metals from a salt solution derived from waste batteries according to claim 1, wherein in step 3), the metal extractant mixture is introduced in an amount of 2.0 to 4.0 mol per mol of metal ions in the salt solution.

5. 2. The method for extracting metals from salt solutions derived from waste batteries as claimed in claim 1, wherein the acid in step 5) is sulfuric acid.

6. The method for extracting metals from a salt solution derived from waste batteries according to claim 5, wherein in step 5), the acid is added in an amount of 1.0 to 2.0 mol per 1 mol of the complex compound.

7. 2. The method for extracting metals from a salt solution derived from waste batteries according to claim 1, wherein the electrodialysis in step 7) is carried out using a bipolar membrane, a cationic membrane, an anionic membrane, or a combination thereof.

8. 2. The method for extracting metals from a salt solution derived from waste batteries as described in claim 1, further comprising the step of recycling the recovered metal extractant activator to step 2).

9. 2. The method for extracting metals from a salt solution derived from waste batteries according to claim 1, wherein the acid recovered in step 7) is recycled to step 1).

10. 2. The method for extracting metals from a salt solution derived from waste batteries according to claim 1, further comprising removing impurities contained in the first filtrate prior to the metal extractant activator and acid recovery step using electrodialysis.

11. 11. The method for extracting metals from salt solutions derived from waste batteries according to claim 10, wherein the impurity removal step comprises precipitation, adsorption, oxidation, ion exchange or a combination thereof.

Images