How to dispose of lithium-ion battery waste

Abstract

To provide a lithium ion battery waste processing method capable of effectively depositing aluminum ions and iron ions in a liquid through neutralization and relatively easily separating the deposits.SOLUTION: A lithium ion battery waste processing method includes: a bleeding step of bleeding battery powder containing at least aluminum and iron and obtained from a lithium ion battery waste in acid, removing a bleeding residual through solid-liquid separation, and obtaining a bled liquid containing at least aluminum ions and iron ions; and a neutralization step of adding a phosphoric acid and / or a phosphate and an oxidant, raising pH within the range of 2.0-3.5, depositing the aluminum ions and the iron ions in the liquid after bleeding respectively as an aluminum phosphate and an iron phosphate, and removing a neutral residual through solid-liquid separation to obtain a neutralized liquid.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This specification discloses a technique relating to a method for treating lithium ion battery waste. [Background technology]

[0002] In recent years, from the perspective of effective resource utilization, recovery of valuable metals such as cobalt and nickel from lithium-ion battery waste, which is discarded due to product life, manufacturing defects, or other reasons, through wet processing, has been widely considered.

[0003] To recover valuable metals from lithium-ion battery waste, for example, battery powder obtained through roasting or other specified processes is leached in acid to obtain a leaching solution in which nickel, cobalt, manganese, aluminum, iron, etc. in the battery powder are dissolved. Thereafter, as described in Patent Documents 1 to 3, among the elements dissolved in the post-leaching solution, aluminum, iron, manganese, etc. are sequentially or simultaneously removed by solvent extraction or neutralization, and valuable metals such as nickel and cobalt are separated and concentrated by solvent extraction. As a result, a solution in which each metal is dissolved is obtained. Nickel and cobalt are recovered from each solution by electrolysis, etc.

[0004] In this regard, Patent Documents 4 to 8 describe a technique for removing aluminum and iron dissolved in a leaching solution by neutralization and oxidation. Specifically, Patent Documents 4 and 5 state that the process "includes a leaching step of leaching lithium-ion battery scrap, performing solid-liquid separation on the leaching solution obtained thereby to obtain a first separated solution, a de-ironization step of adding an oxidizing agent to the first separated solution to adjust the pH of the first separated solution to within a range of 3.0 to 4.0, performing solid-liquid separation, and removing iron from the first separated solution to obtain a second separated solution, and a dealumination step of neutralizing the second separated solution to within a pH range of 4.0 to 6.0, performing solid-liquid separation, and removing aluminum from the second separated solution to obtain a third separated solution." Furthermore, Patent Documents 6 and 7 state that the process "includes a leaching step in which lithium-ion battery scrap is leached to obtain a leaching liquid, a dealumination step in which the leaching liquid is neutralized to a pH range of 4.0 to 6.0, followed by solid-liquid separation to remove aluminum from the leaching liquid to obtain a first separated liquid, and a de-ironization step in which an oxidizing agent is added to the first separated liquid to adjust the pH to a range of 3.0 to 5.0, followed by solid-liquid separation to remove iron from the first separated liquid to obtain a second separated liquid."

[0005] When aluminum is removed by neutralization, the aluminum ion concentration in the solution can be effectively reduced by increasing the pH to a relatively high value, but nickel and cobalt may also precipitate to a small extent depending on the conditions, which may result in the loss of nickel and cobalt.

[0006] Here, Patent Document 8 proposes a method for recovering a high-purity cobalt compound from lithium-ion battery waste, comprising: (A) leaching lithium-ion battery waste containing a cobalt component with an inorganic acid; (B) adjusting the molar ratio of phosphorus to aluminum ions in the leached aqueous solution to 0.6 to 1.2 and oxidizing iron ions at an oxidation potential of 500 mV or higher; (C) adjusting the pH of the aqueous solution to 3.0 to 4.5 and removing impurity metals by precipitation to obtain a purified solution; and (D) adding oxalic acid to the purified solution to obtain cobalt oxalate, or adjusting the pH of the purified solution to 6 to 10 to obtain cobalt hydroxide or cobalt carbonate as a precipitate. Here, with regard to "(B)" and "(C)", in more detail, it is stated that "in step (B), the molar ratio of phosphorus to aluminum ions in the leached aqueous solution containing cobalt is adjusted to a range of 0.6 to 1.2 by adding phosphorous acid, orthophosphoric acid, or the like, and then an oxidizing agent such as hydrogen peroxide solution is added to the solution to set the oxidation potential to 500 mV or more, and the divalent iron ions are oxidized to trivalent iron ions. If the molar ratio of phosphorus to aluminum ions is less than 0.6, the removal of aluminum during pH adjustment in the next step (C) will be incomplete, and conversely, even if the oxidation potential exceeds 1.2, no significant effect will be obtained. Furthermore, if the oxidation potential is less than 500 mV, the oxidation of iron will be incomplete." and "Furthermore, in step (C), an alkaline agent such as a caustic soda solution is added to adjust the pH to 3.0 to 4.5, iron hydroxide and aluminum phosphate will precipitate, and the precipitate is removed by filtration or the like to obtain a purified solution." [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2010-180439 A [Patent Document 2] US Patent Application Publication No. 2011 / 0135547 [Patent Document 3] JP 2014-162982 A [Patent Document 4] International Publication No. 2017 / 159745 [Patent Document 5] US Patent Application Publication No. 2019 / 0106768 [Patent Document 6] International Publication No. 2017 / 159743 [Patent Document 7] US Patent Application Publication No. 2019 / 0084839 [Patent Document 8] Japanese Patent Application Publication No. 11-006020 Summary of the Invention [Problem to be solved by the invention]

[0008] As described in Patent Document 8, by adding phosphoric acid or the like, aluminum ions in the liquid are precipitated as aluminum phosphate without the need to raise the pH too much, and it is possible to remove this by precipitating it. In addition, by maintaining a relatively low pH during this neutralization, the loss of valuable metals such as cobalt and nickel can be suppressed.

[0009] On the other hand, Patent Document 8 states that iron is precipitated as iron hydroxide. Iron hydroxide often forms a gel-like precipitate and is not easy to separate from the liquid by filtration or the like. This leads to a decrease in the efficiency of treating lithium-ion battery waste.

[0010] This specification discloses a method for treating lithium ion battery waste, which can effectively precipitate aluminum ions and iron ions in a liquid by neutralization and can separate the precipitate relatively easily. [Means for solving the problem]

[0011] The method for treating lithium ion battery waste disclosed in this specification includes a leaching step of leaching battery powder obtained from lithium ion battery waste and containing at least aluminum and iron with an acid, removing the leaching residue by solid-liquid separation, and obtaining a leaching solution containing at least aluminum ions and iron ions; a leaching step of adding phosphoric acid and / or a phosphate and an oxidizing agent to the leaching solution to raise the pH to within a range of 2.0 to 3.5, precipitating the aluminum ions and iron ions in the leaching solution as aluminum phosphate and iron phosphate, respectively, and removing the neutralization residue by solid-liquid separation; , containing cobalt ions and nickel ions, and having an aluminum ion concentration of 0.1 g / L to 2 g / L. The method includes a neutralization step of obtaining a neutralized liquid, and an aluminum extraction step of extracting aluminum ions in the neutralized liquid obtained in the neutralization step into a solvent. Effect of the Invention

[0012] According to the above-mentioned method for treating lithium ion battery waste, aluminum ions and iron ions in the liquid can be effectively precipitated by neutralization, and the precipitate can be separated relatively easily. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a flow diagram showing a method for treating lithium ion battery waste according to one embodiment. [Diagram 2] 1 is a graph showing the change in distribution rate of various metals in the liquid with respect to the change in pH in Test Example 1 of the embodiment. [Diagram 3] 1 is a graph showing the change in distribution rate of aluminum into the liquid with respect to the change in pH in Test Example 2 of the embodiment. [Figure 4] 1 is a graph showing the change in distribution rate of various metals in the liquid with respect to the change in pH in Test Example 3 of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the above-mentioned method for treating lithium ion battery waste will be described in detail. In one embodiment of the method for treating lithium ion battery waste, a leaching step and a neutralization step are performed on battery powder obtained by subjecting lithium ion battery waste to pretreatment, etc., as shown in Fig. 1. The battery powder contains at least aluminum and iron, and in the leaching step, the battery powder is leached with an acid and the leaching residue is removed by solid-liquid separation to obtain a leaching solution containing at least aluminum ions and iron ions.

[0015] Then, in the neutralization step, phosphoric acid and / or a phosphate and an oxidizing agent are added to the post-leaching solution to raise the pH to within the range of 2.0 to 3.0, and aluminum ions and iron ions in the post-leaching solution are precipitated as aluminum phosphate and iron phosphate, respectively. Here, most of the aluminum ions and iron ions are precipitated as phosphate, not hydroxide, and are included in the neutralization residue. This makes it possible to easily separate and remove the neutralization residue from the liquid by solid-liquid separation such as filtration. After solid-liquid separation in the neutralization step, the neutralization residue is removed to obtain the post-neutralization solution.

[0016] In this embodiment, as shown in FIG. 1, the neutralized liquid is subjected to an extraction step and a precipitation step in sequence to obtain a mixed metal salt, but the treatment after the neutralization step is not limited to this.

[0017] (Lithium ion battery waste) The target lithium-ion battery waste is a lithium-ion secondary battery that can be used in mobile phones and various other electronic devices, and has been discarded due to the end of the battery product's life, manufacturing defects, or other reasons. It is preferable to recover valuable metals from such lithium-ion battery waste in terms of effective use of resources. The objective here is to recover valuable metals, cobalt and / or nickel, and manganese, with high purity, so that they can be reused in the manufacture of lithium-ion secondary batteries.

[0018] Lithium ion battery waste has a housing containing aluminum as an exterior that envelops the periphery. For example, this housing may be made of only aluminum, or may contain aluminum and iron, aluminum laminate, etc. In addition, lithium ion battery waste may contain a positive electrode active material made of a single metal oxide selected from the group consisting of lithium, nickel, cobalt, and manganese, or two or more composite metal oxides, etc., in the above-mentioned housing, or an aluminum foil (positive electrode substrate) to which the positive electrode active material is applied and fixed, for example, by polyvinylidene fluoride (PVDF) or other organic binders, etc. In addition, lithium ion battery waste may contain copper, iron, etc. Furthermore, lithium ion battery waste usually contains an electrolyte in the housing. For example, ethylene carbonate, diethyl carbonate, etc. may be used as the electrolyte.

[0019] (Pretreatment) Lithium-ion battery waste is often subjected to pre-treatment, which may include roasting, crushing and sieving processes. Lithium-ion battery waste is converted into battery powder through pre-treatment.

[0020] In the roasting step, the lithium ion battery waste is heated. This roasting step is carried out for the purpose of, for example, changing metals such as lithium and cobalt contained in the lithium ion battery waste into a form that is easily melted. In the roasting step, it is preferable to heat the lithium ion battery waste by holding it at a temperature range of, for example, 450°C to 1000°C, preferably 600°C to 800°C for 0.5 to 4 hours. Here, various heating equipment such as a rotary kiln furnace or other various furnaces, or a furnace that heats in an air atmosphere can be used.

[0021] After the roasting process, a crushing process can be performed to remove the positive electrode active material and the like from the casing of the lithium ion battery waste. In the crushing process, the casing of the lithium ion battery waste is destroyed, and the positive electrode active material is selectively separated from the aluminum foil on which the positive electrode active material is applied. In the crushing step, various known devices or equipment can be used, but it is particularly preferable to use an impact crusher that can crush the lithium ion battery waste by applying an impact while cutting it. Examples of this impact crusher include a sample mill, a hammer mill, a pin mill, a wing mill, a tornado mill, and a hammer crusher. A screen can be installed at the outlet of the crusher, so that the lithium ion battery waste is discharged from the crusher through the screen when it is crushed to a size that can pass through the screen.

[0022] After the lithium-ion battery waste is crushed in the crushing process, a sieving process is performed in which the waste is sieved using a sieve with appropriate openings in order to remove aluminum powder, for example. This allows aluminum and copper to remain on the sieve, and battery powder from which aluminum and copper have been removed to a certain extent to be obtained below the sieve.

[0023] The battery powder obtained through the pretreatment contains at least aluminum and iron. The battery powder has an aluminum content of, for example, 1% by mass to 10% by mass, typically 3% by mass to 5% by mass, and an iron content of, for example, 1% by mass to 5% by mass, typically 1% by mass to 3% by mass. The battery powder may further contain manganese, cobalt and / or nickel. For example, the battery powder may contain 0% to 30% by mass of cobalt, 0% to 30% by mass of nickel, and 0% to 30% by mass of manganese. The battery powder may also contain 2% to 8% by mass of lithium. The battery powder may also contain copper, etc.

[0024] (Leaching process) In the leaching process, the battery powder is added to an acidic leaching solution such as sulfuric acid and leached with the acid. After that, the leaching residue and the leaching solution are separated by solid-liquid separation using a filter press, thickener, etc., and the leaching residue is removed.

[0025] If necessary, the battery powder may be brought into contact with water before the leaching with the acid leaching solution to leach and separate only the lithium contained in the lithium-ion battery waste. In this case, the water leaching residue obtained after the battery powder is brought into contact with water to leach lithium is added to the acid leaching solution to perform the acid leaching.

[0026] The acid leaching in the leaching step can be carried out by a known method or under known conditions, but it is preferable to set the pH at 0.0 to 3.0. After the acid leaching is completed, the pH of the leached solution may be 0.5 to 2.0. The oxidation-reduction potential (ORP value, based on silver / silver chloride potential) may be, for example, -250 mV to 0 mV immediately after the acid leaching, and may be about 300 mV in the leached solution after solid-liquid separation.

[0027] The leaching solution obtained here contains at least aluminum ions and iron ions. The leaching solution may also contain manganese ions, and one or more metal ions selected from the group consisting of cobalt ions and nickel ions. Copper that may be contained in the battery powder can be removed by leaving it in the leaching residue without being dissolved by the acid leaching. If copper is also leached and dissolved in the leaching solution, a step of removing copper by electrolysis may be carried out before the neutralization step described below.

[0028] The post-leaching solution may have, for example, a cobalt ion concentration of 10 g / L to 30 g / L, a nickel ion concentration of 10 g / L to 30 g / L, a manganese ion concentration of 10 g / L to 30 g / L, an aluminum ion concentration of 1.0 g / L to 5.0 g / L, and an iron ion concentration of 1.0 g / L to 5.0 g / L.

[0029] (neutralization process) In the neutralization step, at least a portion of the aluminum ions and at least a portion of the iron ions are precipitated from the post-leaching solution, and the neutralization residue containing the precipitates is removed by solid-liquid separation, thereby obtaining a post-neutralization solution.

[0030] More specifically, phosphoric acid and / or a phosphate and an oxidizing agent are added to the post-leaching solution to raise the pH to within a range of 2.0 to 3.5, whereby the aluminum ions and iron ions contained in the post-leaching solution are precipitated as aluminum phosphate and iron phosphate, respectively, and are included in the precipitate.

[0031] Since such phosphates are easier to separate by filtration or the like during solid-liquid separation than hydroxides, a decrease in treatment efficiency due to the difficulty of the separation is effectively suppressed. In this embodiment, since the neutralization residue contains such phosphates such as aluminum phosphate and iron phosphate, the neutralization residue can be easily separated from the liquid by solid-liquid separation such as filtration. In other words, if the precipitate produced by neutralization contains a large amount of hydroxides such as iron hydroxide, the hydroxides in a gel-like form or the like are difficult to separate from the liquid, which reduces the treatment efficiency of lithium-ion battery waste.

[0032] In addition, since phosphoric acid and / or a phosphate are added to the post-leaching solution to precipitate aluminum ions and iron ions as aluminum phosphate and iron phosphate, there is no need to significantly increase the pH at this time. If the pH is increased to a relatively low value within the range of 2.0 to 3.5, aluminum phosphate and iron phosphate are effectively precipitated, and aluminum and iron can be removed, thereby suppressing the loss of cobalt, nickel, etc.

[0033] That is, if the pH is increased to a value higher than 3.5, even cobalt ions and nickel ions in the post-leaching solution will precipitate, resulting in a loss of these valuable metals. On the other hand, if the pH is too low, there is a concern that the precipitation of aluminum phosphate and iron phosphate will be insufficient. From this viewpoint, the pH during neutralization is preferably 2.5 to 3.5.

[0034] In addition, if the leaching solution contains manganese ions derived from the battery powder, if the pH during neutralization is too high, even the manganese ions may precipitate as manganese phosphate. As described later, if a mixed metal solution or even a mixed metal salt is to be produced, it is not desirable for many manganese ions to be precipitated and removed in the neutralization step, since this may cause a large change in the composition ratio of cobalt and / or nickel to manganese. In this embodiment, by setting the pH within the above-mentioned range, it is possible to remove aluminum and iron while suppressing the precipitation of such manganese ions.

[0035] In the neutralization step, phosphoric acid and / or a phosphate is added to the post-leaching solution. The phosphoric acid referred to here means a compound (so-called phosphoric acid) having a phosphoric acid skeleton, which is generated, for example, by hydration of diphosphorus pentoxide (P2O5), and includes orthophosphoric acid (H3PO4), diphosphoric acid (H4P2O7), etc. The phosphate is a compound containing a polyatomic ion or group composed of phosphorus and oxygen, and specifically includes trisodium phosphate (Na3PO4), disodium hydrogen phosphate (Na2HPO4), sodium dihydrogen phosphate (NaH2PO4), and hydrates thereof. When such phosphoric acid and / or a phosphate is added to the post-leaching solution and the pH is increased as described above, for example, a reaction such as Al2(SO4)3+2H3PO4+6NaOH→2AlPO4+3Na2SO4+6H2O occurs for aluminum, and aluminum phosphate (AlPO4) and iron phosphate (Fe3(PO4)2, FePO4) are generated.

[0036] The amount of phosphoric acid and / or phosphate to be added to the post-leaching solution is preferably an amount in which the phosphorus in the phosphoric acid and / or phosphate is 0.6 to 1.2 times the molar equivalent relative to the total of aluminum ions and iron ions in the post-leaching solution. By adding phosphoric acid and / or phosphate in an amount containing phosphorus of 0.6 times or more molar equivalent relative to the total of aluminum ions and iron ions, the aluminum ions and iron ions in the post-leaching solution are sufficiently precipitated as aluminum phosphate and iron phosphate, and they can be removed more effectively. In order to suppress the increase in cost due to excessive addition, it is desirable to add phosphoric acid and / or phosphate in an amount in which the phosphorus in the phosphoric acid and / or phosphate is 1.2 times or less molar equivalent relative to the total of aluminum ions and iron ions. The amount added is preferably 0.6 to 1.2 times molar equivalent.

[0037] The post-leaching solution may contain a small amount of phosphorus derived from the electrolyte of the lithium ion battery waste, etc., but such phosphorus can also be consumed in the neutralization process.

[0038] An oxidizing agent is also added to the post-leaching solution. The addition of the oxidizing agent oxidizes the iron in the solution from divalent to trivalent, which makes it easier to precipitate as iron phosphate. The oxidizing agent is not particularly limited as long as it can oxidize iron, and for example, hydrogen peroxide or manganese dioxide can be used. The manganese dioxide used as the oxidizing agent may be a reagent, a positive electrode active material containing manganese dioxide, or a manganese-containing leaching residue obtained by leaching a positive electrode active material. Alternatively, air or oxygen may be supplied by bubbling. In order to precipitate iron, the oxidation-reduction potential (ORP value, based on silver / silver chloride potential) during oxidation is preferably 300 mV to 900 mV, for example, about 600 mV. Prior to the addition of the oxidizing agent, an acid such as sulfuric acid, hydrochloric acid, or nitric acid can be added to lower the pH.

[0039] After the addition of phosphoric acid and / or a phosphate salt and an oxidizing agent, an alkali can be added to adjust the pH to the above range. The alkali is not particularly limited, but in the case of a post-leaching solution containing sulfuric acid, sodium hydroxide, which is a sodium-based alkali, is preferred over calcium-based alkali.

[0040] The neutralized solution often contains manganese ions, and may further contain one or more metal ions selected from the group consisting of cobalt ions and nickel ions. In addition, the neutralized solution may contain aluminum ions and lithium ions that remain after neutralization. For example, the cobalt ion concentration in the neutralized solution may be 0 g / L to 20 g / L, the nickel ion concentration may be 0 g / L to 20 g / L, and the manganese ion concentration may be 1 g / L to 20 g / L. The aluminum ion concentration in the neutralized solution may be 0.1 g / L to 2 g / L. The lithium ion concentration may be, for example, 2.0 g / L to 5.0 g / L.

[0041] (extraction process) After the neutralization step, an extraction step using a solvent extraction method can be carried out. If aluminum ions remain in the neutralized liquid, the aluminum ions are first extracted and removed, and then one or more metal ions selected from cobalt ions and nickel ions and manganese ions are extracted and back-extracted together. However, if the neutralized liquid contains almost no aluminum ions, the solvent extraction for removing aluminum can be omitted.

[0042] To remove aluminum ions, the aluminum ions are extracted into a solvent (organic phase) while manganese ions and the like in the neutralized liquid remain in the aqueous phase. As a result, the extraction residue contains at least cobalt ions and / or nickel ions and manganese ions after the aluminum ions are removed. Here, the manganese ion concentration after the extraction of the aluminum ions is preferably 80% or more, more preferably 90% or more, of the manganese ion concentration before the removal of the aluminum ions.

[0043] Here, as long as manganese ions are not extracted much and aluminum ions are extracted, various extractants such as phosphate extractants and carboxylic acid extractants can be used, and an appropriate equilibrium pH is set during extraction accordingly. Among these, examples of carboxylic acid extractants include neodecanoic acid and naphthenic acid. Among them, neodecanoic acid is preferred from the viewpoint of extracting aluminum ions without extracting manganese ions as much as possible. The carboxylic acid extractant preferably contains a carboxylic acid having 8 to 16 carbon atoms. Specifically, Versatic Acid 10 (also called "VA-10") manufactured by Shell Chemical Co., Ltd. can be used. In this case, the equilibrium pH during extraction is preferably 4.0 to 5.0, more preferably 4.3 to 4.7. If the equilibrium pH is too low, aluminum ions may not be sufficiently extracted into the solvent and may remain in a large amount in the neutralized liquid. On the other hand, if the equilibrium pH is too high, aluminum ions are hydroxylated to become solid aluminum hydroxide, and cannot be extracted by the solvent. Using a solvent containing a carboxylic acid extractant to achieve such an equilibrium pH allows for the removal of nearly all of the aluminum ions while leaving most of the manganese ions in the aqueous phase.

[0044] When an extractant is used, it is typically diluted with a hydrocarbon-based organic solvent to form a solvent. Examples of the organic solvent include aromatic, paraffinic, and naphthenic solvents. For example, the concentration of the phosphate extractant in the solvent may be 20% to 30% by volume, and the concentration of the carboxylic acid extractant in the solvent may be 20% to 30% by volume. However, this is not limited to this. The O / A ratio may be 1.0 to 5.0.

[0045] The above extraction can be carried out based on a general method. As an example, the solution (aqueous phase) and the solvent (organic phase) are brought into contact with each other, and typically stirred and mixed for 5 to 60 minutes using a mixer, to react the ions with the extractant. The temperature during extraction is from room temperature (about 15 to 25°C) to 60°C or less, and is preferably carried out at 35 to 45°C for reasons of extraction speed, phase separation, and evaporation of the organic solvent. Thereafter, the mixed organic phase and aqueous phase are separated by a settler due to the difference in specific gravity. Extraction of cobalt ions and / or nickel ions and manganese ions, which will be described later, can also be carried out in a substantially similar manner.

[0046] After the aluminum ions are extracted, for example, the cobalt ion concentration may be 0 g / L to 20 g / L, the nickel ion concentration may be 0 g / L to 20 g / L, the manganese ion concentration may be 1 g / L to 20 g / L, and the aluminum ion concentration may be 0.001 g / L or less.

[0047] The extraction of one or more metal ions selected from cobalt ions and nickel ions, and manganese ions, is carried out under conditions in which two or three of these ions are simultaneously extracted and stripped, thereby leaving impurities such as sodium ions, calcium ions, lithium ions, magnesium ions, etc., which may be contained in the neutralized solution, in the aqueous phase and separating them from the metal ions and manganese ions, to obtain a mixed metal solution as a stripped solution containing the metal ions and manganese ions.

[0048] In this extraction, a solvent containing a carboxylic acid extractant is used, and the equilibrium pH is preferably set to 6.5 to 7.5. If the equilibrium pH is within this range, cobalt ions and / or nickel ions and manganese ions can be effectively extracted, and impurities can be left in the aqueous phase. The equilibrium pH is more preferably set to 6.8 to 7.2.

[0049] The carboxylic acid extractant may be naphthenic acid or the like as described above, but preferably contains neodecanoic acid, and more preferably contains a carboxylic acid having 8 to 16 carbon atoms, and VA-10 is particularly suitable. When a carboxylic acid extractant containing neodecanoic acid is used, cobalt ions and / or nickel ions, and manganese ions can be effectively extracted without extracting other metal ions. The carboxylic acid extractant can be diluted with an organic solvent such as an aromatic, paraffinic, or naphthenic solvent to form a solvent. The concentration of the carboxylic acid extractant in the solvent is preferably 20% by volume to 30% by volume. This allows manganese ions, cobalt ions, and / or nickel ions to be sufficiently extracted while leaving most of the impurities in the aqueous phase. The O / A ratio is preferably 1.0 to 1.5. If the O / A ratio is in this range, impurities are hardly extracted, and manganese ions, cobalt ions, and / or nickel ions are sufficiently extracted.

[0050] The neutralized liquid may contain phosphorus due to the addition of phosphoric acid and / or a phosphate in the neutralization step, etc., but the phosphorus remains in the aqueous phase when one or more metal ions selected from cobalt ions and nickel ions, and manganese ions are extracted with a solvent, and can be separated from these one or more metal ions and manganese ions.

[0051] After cobalt ions and / or nickel ions and manganese ions are extracted into a solvent, the solvent is subjected to back extraction, and cobalt ions and / or nickel ions and manganese ions are transferred to an aqueous phase. Specifically, the solvent is mixed with a back extraction solution such as sulfuric acid or hydrochloric acid, and stirred for 5 to 60 minutes, for example, by a mixer or the like. It is preferable to use sulfuric acid as the back extraction solution. When a back extraction solution of sulfuric acid is used, the metal mixed solution, which is the liquid after back extraction, becomes a sulfuric acid solution. In order to effectively back extract manganese ions, cobalt ions and / or nickel ions in the solvent, the acid concentration of the back extraction solution is preferably adjusted to 0.05 g / L to 200 g / L (pH: -0.6 to 3.0), and more preferably adjusted to 1.5 g / L to 15 g / L (pH: 0.5 to 1.5). The temperature of the back extraction can be from room temperature to 60°C or less, and is preferably performed at 35 to 45°C for reasons of back extraction speed, phase separation, and evaporation of the organic solvent.

[0052] The mixed metal solution contains cobalt ions and / or nickel ions, and manganese ions. For example, the mixed metal solution may have a cobalt ion concentration of 0 g / L to 50 g / L, a nickel ion concentration of 0 g / L to 50 g / L, and a manganese ion concentration of 1 g / L to 50 g / L. The mixed metal solution may contain sodium, calcium, and magnesium as impurities, and the total concentration of the impurities is preferably 1.0 g / L or less.

[0053] In the precipitation step, a mixed metal salt containing metal salts of cobalt and / or nickel and manganese is precipitated from the mixed metal solution (post-stripping liquid) obtained in the above extraction step.

[0054] Here, for example, an alkali such as sodium hydroxide is added to the metal mixture solution to adjust the pH to 9.0 to 10.0, and cobalt and / or nickel and manganese are precipitated. The oxidation-reduction potential (ORP value, silver / silver chloride potential standard) at this time can be, for example, 0 mV to 600 mV. The liquid temperature can be 60°C to 90°C.

[0055] The mixed metal salt obtained by the subsequent solid-liquid separation may contain a mixture of metal salts of cobalt and / or nickel and manganese, such as cobalt hydroxide and / or nickel hydroxide and manganese hydroxide, etc. The neutralization residue may contain oxides of the metals, such as Co3O4, Mn3O4, Mn2O3, Ni3O4, etc.

[0056] If necessary, the neutralized residue may be washed with water or the like, and then dissolved in a sulfuric acid acidic solution, which may then be heated and concentrated or cooled to give a mixed metal salt containing cobalt sulfate and / or nickel sulfate and manganese sulfate.

[0057] The mixed metal salt containing the hydroxides or sulfates of cobalt and / or nickel and manganese as described above may have a cobalt content of 0% to 60% by mass, a nickel content of 0% to 60% by mass, and a manganese content of 1% to 60% by mass. The mixed metal salt preferably has a sodium content of 60 ppm by mass or less, a calcium content of 10 ppm by mass or less, and a magnesium content of 10 ppm by mass or less as impurities. Such mixed metal salts are easier to recover at lower cost than the cobalt, nickel and manganese metals and may be suitable for use in the manufacture of lithium ion batteries. EXAMPLES

[0058] Next, the above-mentioned lithium ion battery waste treatment method was experimentally carried out and will be described below. However, the description here is merely for illustrative purposes and is not intended to be limiting.

[0059] (Test Example 1) Lithium-ion battery waste was roasted, crushed, and sieved to obtain battery powder, which was then leached in a sulfuric acid solution, and the leaching residue was separated to obtain a leaching solution. Figures 2(a) and (b) show the liquid distribution ratios of each metal when the leaching solution was neutralized by adding NaOH without adding phosphoric acid, and when the leaching solution was neutralized by adding NaOH after adding phosphoric acid, respectively. The phosphoric acid used here contained 1.2 molar equivalents of phosphorus relative to the amount of aluminum ions in the leaching solution.

[0060] When phosphoric acid was not added, as shown in Figure 2(a), more than 90% of aluminum could be separated at a pH of 4.5 or higher, but nickel and cobalt were lost by 4 to 10%.

[0061] On the other hand, when phosphoric acid was added, as shown in FIG. 2(b), it was possible to separate aluminum by precipitating it at a pH of 2.0 to 3.5. In particular, when the pH was 3.5, 90% or more of aluminum could be separated, and nickel and cobalt loss at pH 3.5 was suppressed to 1 to 3%. Also, from FIG. 2(b), it can be seen that a large amount of manganese precipitates when the pH exceeds 3.5. From the viewpoint of suppressing the precipitation of manganese, it is preferable to set the pH to 3.5 or less. Therefore, it can be seen that by setting the pH to 2.0 to 3.5, it is possible to separate aluminum while suppressing the precipitation of nickel, cobalt, and manganese.

[0062] (Test Example 2) The amount of phosphoric acid added to the post-leaching solution was varied to 0.0, 0.6, 0.9, and 1.2 molar equivalents in terms of the amount of phosphorus relative to the amounts of aluminum ions and iron ions in the post-leaching solution, and the distribution coefficient of aluminum in the solution when neutralized is shown in Figure 3.

[0063] When the pH during neutralization is set to 3.5 or less to suppress the loss of nickel and cobalt, in order to effectively remove aluminum, it can be seen from FIG. 3 that the amount of phosphoric acid added should be 0.6 molar equivalents or more, and preferably 0.9 molar equivalents or more.

[0064] (Test Example 3) Figures 4(a) and (b) show the liquid distribution coefficients of each metal when the leaching solution was neutralized with NaOH after adding hydrogen peroxide as an oxidizing agent without adding phosphoric acid and after adding phosphoric acid and the oxidizing agent, respectively.

[0065] As can be seen from FIG. 4(b), by oxidizing the iron before neutralization, it is possible to effectively precipitate not only aluminum but also iron at a lower pH range.

Claims

1. A method for treating lithium ion battery waste, comprising: a leaching step of leaching battery powder obtained from lithium ion battery waste and containing at least aluminum and iron with an acid, removing the leaching residue by solid-liquid separation, and obtaining a leaching solution containing at least aluminum ions and iron ions; a neutralization step of adding phosphoric acid and / or a phosphate and an oxidizing agent to the leaching solution to raise the pH to a range of 2.0 to 3.5, thereby precipitating aluminum ions and iron ions in the leaching solution as aluminum phosphate and iron phosphate, respectively, and removing neutralization residues by solid-liquid separation to obtain a neutralized solution containing cobalt ions and nickel ions and having an aluminum ion concentration of 0.1 g / L to 2 g / L; an aluminum extraction step of extracting aluminum ions in the neutralized liquid obtained in the neutralization step into a solvent; A method for treating lithium ion battery waste, comprising:

2. 2. The method for treating lithium ion battery waste according to claim 1, wherein in the neutralization step, an amount of the phosphoric acid and / or the phosphate added to the post-leaching solution is an amount such that phosphorus in the phosphoric acid and / or the phosphate is 0.6 to 1.2 times the molar equivalent of a total of aluminum ions and iron ions in the post-leaching solution.

3. The leaching solution further contains manganese ions derived from the battery powder, 3. The method for treating lithium ion battery waste according to claim 1, wherein the neutralization step is performed at a pH within the range to precipitate the aluminum phosphate and the iron phosphate while suppressing precipitation of the manganese ions.

4. the leaching solution further contains one or more metal ions selected from cobalt ions and nickel ions derived from the battery powder; The method for treating lithium ion battery waste according to claim 3, further comprising a metal extraction step of adjusting the equilibrium pH of the neutralized solution that has been subjected to the aluminum extraction step to 6.5 to 7.5 using a solvent containing a carboxylic acid-based extractant, extracting manganese ions and the one or more metal ions in the neutralized solution into the solvent, and then back-extracting the manganese ions and the one or more metal ions from the solvent to obtain a mixed metal solution.

5. 5. The method for treating lithium ion battery waste according to claim 4, wherein, in the metal extraction step, phosphorus contained in the neutralized solution is left in the neutralized solution during extraction and separated from the manganese ions and the one or more metal ions extracted into the solvent.

6. The method for treating lithium ion battery waste according to claim 4 or 5, wherein the carboxylic acid extractant contained in the solvent in the metal extraction step includes neodecanoic acid.

7. The method for treating lithium ion battery waste according to any one of claims 4 to 6, further comprising a precipitation step of precipitating a mixed metal salt containing a metal salt of manganese and one or more metal salts of cobalt and nickel from the mixed metal solution.

8. 8. The method for treating lithium ion battery waste according to claim 7, wherein in the precipitation step, the mixed metal solution is neutralized with sodium hydroxide to precipitate a mixed metal salt containing a hydroxide of manganese and one or more hydroxides of cobalt and nickel.

9. 9. The method for treating lithium ion battery waste according to claim 7 or 8, wherein the mixed metal salt is used in the manufacture of lithium ion batteries.

10. The method for treating lithium ion battery waste according to any one of claims 1 to 9, wherein the solvent used in the aluminum extraction step contains only a phosphate ester-based extractant as an extractant.

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