JP2019099875A - Recovery method of lithium - Google Patents

Abstract

To provide a method for more easily recovering lithium from a manufacturing process wastewater of a positive electrode material for lithium secondary battery containing lithium and aluminum, and reducing recovery cost.SOLUTION: There is provided a recovery method of lithium for recovering lithium from manufacturing process wastewater containing lithium and aluminum of a positive electrode material for lithium secondary battery, having an adsorption process S2 for selectively adsorbing a lithium ion to an ion exchange resin by contacting the ion exchange resin with the manufacturing process wastewater, and an elution process S3 for making a solution containing acid or sodium salt in contract with the ion exchange resin to which the lithium ion is selectively adsorbed in the adsorption process S2 to elute the lithium ion from the ion exchange resin, in which the ion exchange resin is a weakly acidic cation exchange resin having a carboxyl group or a sodium salt type functional group thereof.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a lithium recovery method for recovering lithium from manufacturing process waste water containing lithium and aluminum of a positive electrode material for a lithium secondary battery.

  Lithium is widely used in industries such as additives for pottery and glass, glass flux for continuous casting of steel, grease, medicine, battery and the like. In particular, since lithium secondary batteries have high energy density and high voltage, their use as batteries for electronic devices such as laptop computers and as car batteries for electric vehicles and hybrid vehicles has recently expanded, and demand is rapidly increasing. ing.

  In recent years, in order to effectively utilize resources, it has been promoted to recover lithium from waste water discharged in the manufacturing process of a positive electrode material for lithium secondary batteries (hereinafter, also referred to as “manufacturing process drainage”).

  For example, lithium and aluminum are contained in the manufacturing process drainage in the nickel-based positive electrode material (NCA). Although it is necessary to separate lithium and aluminum in order to recover lithium from this manufacturing process waste water, the neutralization precipitation method is proposed in Patent Document 1 as a separation method, and the solvent extraction method is proposed in Patent Documents 2 and 3.

JP 2004-33984 A JP, 2012-211386, A Japanese Patent Application Publication No. 2002-121623

  However, in the neutralization precipitation method of Patent Document 1 and the solvent extraction method of Patent Document 2, lithium remains in the production process wastewater after aluminum separation. Since the concentration of lithium remaining in the manufacturing process wastewater is low, in order to recover lithium as a carbonate or hydroxide salt, it is necessary to evaporate the manufacturing process wastewater and concentrate the lithium. For this reason, there is a problem that the cost of recovering lithium increases and it is economically unpreferable.

  In the solvent extraction method of Patent Document 3, crown ether is used to separate lithium from production process wastewater, and then lithium is extracted back from crown ether. Since this method enables concentration of lithium during back extraction, it does not require concentration by evaporation and is cost effective. However, crown ether is expensive, and the solvent extraction method requires waste water treatment, which complicates the process, resulting in an increase in the cost of lithium recovery.

  The present invention has been made in view of the above problems, and provides a method for more simply recovering lithium from waste water of manufacturing process of positive electrode material for lithium secondary battery containing lithium and aluminum and reducing the recovery cost The purpose is

  One aspect of the present invention is a method for recovering lithium from manufacturing process waste water containing lithium and aluminum of positive electrode material for lithium secondary battery, which comprises contacting ion exchange resin with the production process waste water to carry out ion exchange The adsorption step of selectively adsorbing lithium ions to the resin, and the ion exchange resin in which the lithium ions are selectively adsorbed in the adsorption step are brought into contact with an aqueous solution containing an acid or a sodium salt to elute lithium ions from the ion exchange resin And the ion exchange resin is a weakly acidic cation exchange resin having a carboxyl group or a functional group of its sodium salt type.

  In this way, lithium can be selectively recovered from the wastewater in the manufacturing process. And since lithium can be concentrated without the process of evaporating manufacturing process waste water and concentrating lithium, lithium can be recovered more simply and recovery cost can be reduced.

  In one embodiment of the present invention, the pH of the production process waste water in the adsorption step may be 9 or more.

  In this way, in the adsorption step, aluminum and lithium in the manufacturing process wastewater can be separated, and inhibition of the ion exchange reaction can be prevented, so lithium can be recovered more easily and recovery cost can be reduced. It can be reduced.

  Further, in one aspect of the present invention, the lithium concentration of the production process wastewater in the adsorption step may be 0.3 g / L or more.

  In this way, lithium ions with low selectivity can be adsorbed to the ion exchange resin in the adsorption step.

  In one embodiment of the present invention, the adsorption step further includes a substitution step of substituting a functional group contained in the ion exchange resin before the adsorption step, and in the substitution step, the carboxyl group is substituted with a sodium salt type. Good.

  In this way, it is possible to prevent a decrease in pH in the adsorption step and to prevent the ion exchange reaction in the adsorption step from being inhibited.

  In one embodiment of the present invention, the elution step further includes a regeneration step of regenerating the ion exchange resin, and the regeneration step comprises a functional group changed from sodium salt type to carboxy group in the elution step and sodium salt from carboxy group It may be replaced by a type.

  In this way, it is possible to prevent the decrease in pH in the adsorption step again, and to prevent the ion exchange reaction in the adsorption step from being inhibited.

  In one aspect of the present invention, the sodium salt in the elution step may be sodium sulfate.

  In this way, since the functional group is substituted from the carboxy group to the sodium salt type in the elution step, the regeneration step can be omitted.

  According to the present invention, lithium can be selectively recovered from the production process waste water, and lithium can be concentrated without the process of evaporating the production process waste water and concentrating lithium, so lithium and aluminum containing lithium It is possible to more simply recover lithium from the production process drainage of the positive electrode material for the next battery, and to reduce the recovery cost.

It is a flowchart which shows the outline of the manufacturing process of the positive electrode material for lithium secondary batteries. It is a flow figure showing an outline of a recovery method of lithium concerning one embodiment of the present invention. FIG. 6 is a view showing the relationship between mixing and stirring time in the adsorption step and the metal concentration in the manufacturing process waste water in Example 1. FIG. 6 is a view showing the relationship between the mixing and stirring time in the elution step and the metal concentration in the production process waste water in Example 1. It is a figure which shows the relationship of the mixing stirring time in the adsorption process in the comparative example 1, and the metal concentration in a manufacturing process waste water. It is a figure which shows the relationship of the mixing stirring time in the elution process in the comparative example 1, and the metal concentration in a manufacturing process waste water.

  Hereinafter, specific embodiments of the present invention (hereinafter, referred to as “the present embodiments”) will be described in detail. In addition, this invention is not limited to the following embodiment at all, Within the range of the objective of this invention, a change can be added suitably and can be implemented.

[1. Outline of manufacturing process of positive electrode material for lithium secondary battery]
First, an outline of a production process of a positive electrode material for a lithium secondary battery will be described using the drawings. FIG. 1 is a flow chart showing an outline of the production process of a positive electrode material for a lithium secondary battery. As shown in FIG. 1, the manufacturing process of the positive electrode material for lithium secondary battery is composed of a crystallization process S101, a separation process S102, a baking process S103, and a water washing process S104. Specifically, in the crystallization step S101, an aqueous solution of sodium hydroxide is added to a mixed aqueous solution of metal salts of sulfates made of raw materials such as nickel, cobalt, or aluminum, and these metal hydroxides are coprecipitated to obtain a metal. It is a process of obtaining the slurry containing hydroxide. The separation step S102 is a step of separating the metal composite hydroxide from the obtained slurry containing the metal hydroxide by solid-liquid separation or the like. In the firing step S103, the obtained metal composite hydroxide and lithium hydroxide are mixed, and the mixture is fired at a predetermined temperature to obtain a lithium metal composite oxide. The water washing step S104 is a step of water washing the obtained lithium metal composite oxide.

  In the water washing step S104 of the manufacturing process of the positive electrode material for lithium secondary battery, since the positive electrode material is washed with water, waste water containing lithium ions and aluminum ions at high concentration is discharged. The drainage concentration is, for example, 1 to 4 g / L for lithium ions, and 0.04 to 0.18 g / L for aluminum ions. It is not preferable to discharge such drainage into public water areas because lithium is an industrially useful metal. And, in recycling of resources, it is required to recover and effectively use lithium discharged in the manufacturing process without discarding.

  As described above, for example, since the wastewater in the production process of NCA is an aqueous solution containing lithium and aluminum, separation of aluminum is required when recovering a lithium compound from the wastewater in the production process.

  In order to separate aluminum from an aqueous solution containing aluminum and lithium, there are a neutralization precipitation method (for example, Patent Document 1), a solvent extraction method (for example, Patent Documents 2 and 3), an ion exchange method, and the like.

  In the neutralization precipitation method, pH adjustment is performed in a pH range in which aluminum becomes a hydroxide, and aluminum is separated as a precipitate. Lithium remains in the aqueous solution using this method.

  In the solvent extraction method, an acidic extractant having, for example, a carboxylic acid or phosphoric acid as a functional group is widely used, but the acidic extractant is generally more difficult to extract as the metal of the formed oxide has higher basicity. Therefore, lithium is more difficult to extract than aluminum. For this reason, aluminum is extracted and separated. Lithium also remains in the aqueous solution when this method is used.

  In the ion exchange method, a cation exchange resin or a chelate resin is widely used to capture cations, but since there is no resin that selectively captures lithium compared to aluminum, aluminum is captured and separated from the solution. Lithium also remains in the aqueous solution when this method is used.

  As described above, there are many separation methods in which aluminum is selectively removed to leave lithium in the solution, but when lithium is to be recovered as a carbonate or hydroxide, it is disadvantageous when the lithium concentration in the solution is low. become. For example, when it is intended to recover lithium carbonate, a carbonated source such as sodium carbonate is added to precipitate lithium carbonate for recovery, but lithium carbonate has a solubility of about 13 g / L at 20 ° C. It must be above this concentration. By adjusting the conditions, it is possible to increase the lithium concentration by adjusting the conditions for the leachate of ores and process intermediate products, but it may become economically unfavorable situations such as consuming a large amount of acid to lower the pH at the time of leaching. There is. In addition, since the lithium concentration in the manufacturing process waste water is usually kept low to reduce losses, the lithium concentration in this case is hardly exceeded.

  For this reason, when the lithium concentration in the manufacturing process waste water is low, concentration needs to be performed. Even if it is intended to recover with lithium hydroxide, lithium hydroxide is often converted by adding slaked lime to lithium carbonate, so it is necessary to concentrate it to obtain an intermediate product lithium carbonate.

  Evaporative concentration is known as a well-known concentration method, but to evaporate water requires a large amount of energy at 539 kcal / kg at standard atmospheric pressure, resulting in high energy costs, which is not economically preferable.

  The solvent extraction method and the ion exchange method extract or adsorb the metal to be recovered, and then make the aqueous solution purified by back extraction or elution, but by adjusting the flow rate of the back extract solution or the eluent, the recovery object is recovered Metals can be concentrated. Therefore, if lithium can be selectively extracted or adsorbed, it is possible to obtain a purified liquid having a lithium concentration capable of precipitating lithium carbonate without using a high energy cost evaporative concentration method.

  As an extracting agent or resin capable of selectively extracting an alkali metal or alkaline earth metal, an extracting agent or resin having a crown ether which is a macrocyclic compound as a functional group is known (for example, Patent Document 3). Crown ethers are known to form complexes by incorporating metal ions into the ring and are selective for metal ions having an ionic radius that matches the ring radius. It is known that crown ethers of carbon and oxygen, which constitute the ring, particularly have affinity to alkali metals and alkaline earth metals, and 12-crown-4 specifically forms a complex with lithium. However, crown ethers are water soluble and thus are not suitable for solvent extraction methods that require phase separation. It may be considered to modify crown alkyl ether to a lipophilic alkyl group or the like to make it water insoluble property, but if special synthesis is required and it is attempted to be used industrially, the cost becomes expensive. And utilization is not realistic due to the problem that supply stability can not be maintained.

  Furthermore, in the solvent extraction method, since the organic phase is mixed in the state of minute droplets in the extraction residue after extraction, in order to discharge the waste water usually, an activated carbon treatment or the like is required. In addition, water-soluble impurities derived from organic solvents such as extractants and water-soluble decomposition products are dissolved in the aqueous phase, and COD in the waste water is increased, so waste water treatment such as oxidative decomposition treatment is required, and the process is complicated. And the processing cost tends to be high.

  For this reason, the simplest method is to use a resin on which crown ether is supported. However, crown ether is expensive in its reagent itself, and the resin is also expensive. Currently, practical examples can only be used as a column for analysis. There is no. Therefore, large-scale purification using crown ethers is currently at a cost disadvantage.

  Due to such problems, there has been a demand for a simple method for selectively recovering lithium from an aqueous solution containing aluminum and lithium to obtain an aqueous solution having a concentration suitable for obtaining lithium carbonate or lithium hydroxide. .

  In view of such circumstances, as a result of intensive investigations, the inventors adjusted the production process wastewater containing aluminum and lithium to a predetermined pH and adjusted the functional group to a sodium type (hereinafter referred to as Na type). Adsorption step in which lithium ions are selectively adsorbed to leave aluminum ions in the solution by contacting with a weakly acidic cation exchange resin having a carboxy group, and weakly acidic cations using an aqueous solution containing an acid or a sodium salt Suitable for recovering lithium selectively from production process waste water containing aluminum and lithium simply by combining with an elution step of eluting lithium ion adsorbed to exchange resin, and obtaining lithium carbonate and lithium hydroxide It has been found that it is possible to make an aqueous solution of concentration, and the present invention has been completed.

[2. Lithium recovery process]
The method for recovering lithium according to the present embodiment recovers lithium from the production process waste water of a positive electrode material for lithium secondary battery, and includes a replacement step, an adsorption step, an elution step, and a regeneration step. Hereinafter, the outline and each process of the recovery method of lithium are each demonstrated.

[2-1. Outline of Lithium Recovery Method]
First, an outline of a method for recovering lithium will be described using the drawings. FIG. 2 is a flowchart showing an outline of a method for recovering lithium. The method for recovering lithium according to one embodiment of the present invention, as shown in FIG. 2, comprises a substitution step S1, an adsorption step S2, an elution step S3 and a regeneration step S4.

2-2-1. Replacement process]
The substitution step S1 is a step of substituting a carboxy group (hereinafter also referred to as "H-type"), which is a functional group contained in the weak acid cation exchange resin, with a sodium type (hereinafter also referred to as "Na-type"). It is. The reason why the H-type is replaced with the Na-type in this embodiment will be described in the section of the adsorption step. In addition, since the adsorption property of weak acid cation exchange resin with respect to lithium ion falls by repeating the adsorption | suction process and elution process which are mentioned later several times, a substitution process can also be performed in order to reproduce this adsorption. . The substitution step can be omitted when the weakly acidic cation exchange resin is in the Na type.

2-2-2. Adsorption process]
In the adsorption step S2, the weakly acidic ion exchange resin is brought into contact with the production process wastewater to selectively adsorb lithium ions to the weakly acidic ion exchange resin. The lithium solution containing aluminum and lithium may have any metal concentration. However, by adjusting the pH of the aqueous solution to 9 or more, the aluminum ion is converted to an aluminate ion [Al (OH) ₄ ] ⁻ . When this solution is brought into contact with a weakly acidic cation exchange resin containing a carboxy group, which has been adjusted to the Na type, lithium ions which are cations are adsorbed, but aluminate ions which are anions are not adsorbed. Here, the aluminum ion is more selective than the lithium ion. Therefore, it is difficult to selectively adsorb lithium to the weakly acidic cation exchange resin when aluminum ions are present in the production process waste water. Therefore, in the adsorption step according to one embodiment of the present invention, lithium ions can be selectively adsorbed by converting aluminum ions into aluminate ions. At this time, if the functional group is a hydrogen type (hereinafter, described as H type), hydrogen ions exchanged with lithium ions are released into the aqueous solution, and the pH in the vicinity of the resin is lowered. In this case, aluminum hydroxide having poor filterability precipitates and adheres to the resin to inhibit the ion exchange reaction. When the pH in the vicinity of the resin is further lowered to reach an acidic region where aluminum is present as a cation, it is selectively adsorbed more than lithium ions, making separation difficult.

  However, by adjusting to Na-type in advance, such pH decrease is prevented and the formation of aluminum hydroxide and aluminum ion is suppressed, and aluminum can be held in the state of aluminate ion, so it is adsorbed to the resin. There is nothing to do. Since lithium ion is inferior in selectivity to sodium ion and lithium ion, lithium concentration needs to be 0.3 g / L or more in order to adsorb lithium ion in Na type, and 0.5 g / L or more It is desirable to have. If the lithium concentration in the manufacturing process waste water is less than 0.3 g / L, lithium ions may be difficult to be adsorbed to the Na-type weakly acidic cation exchange resin.

2-2-3. Elution process]
In the elution step S3, lithium ions are eluted with an aqueous solution containing an acid or sodium salt such as sulfuric acid or hydrochloric acid. When an acid such as sulfuric acid or hydrochloric acid is used as the eluent, the weakly acidic cation exchange resin is H-type, and therefore, after the elution, a regeneration step of passing NaOH through to Na-type is required. On the other hand, when lithium ions are eluted with an aqueous solution containing a sodium salt, it becomes Na-type, so the regeneration step can be omitted. In addition, by adjusting the flow rate of the eluent, lithium in the eluent can be concentrated. Therefore, lithium can be recovered without using a high energy cost evaporation method. In addition, since the weak acid cation exchange resin has a very high selectivity to hydrogen ions, lithium ions can be easily eluted in the elution step as compared to a strongly acidic cation exchange resin having a sulfonic acid group as a functional group.

2-2-4. Regeneration process]
The regeneration step S4 is required only when eluting with an acid such as sulfuric acid or hydrochloric acid. In this step, lithium ions are eluted with sulfuric acid or hydrochloric acid, and then converted into Na-type by passing NaOH through a weakly acidic cation exchange resin in H-type. When the lithium ion is eluted with an aqueous solution containing a sodium salt, this step is unnecessary because it becomes Na type by the elution reaction.

  Sodium salts include sodium chloride and sodium sulfate, but when sodium chloride is used, chlorine remains in precipitated lithium carbonate. The recovered lithium carbonate is recycled as a raw material of the positive electrode material of the secondary battery, but it is desirable to use sodium sulfate because chlorine has a disadvantage of corroding the structural material of the facility.

  EXAMPLES Specific examples to which the present invention is applied will be described below, but the present invention is not limited to these examples.

Example 1
[3-1. Replacement process]
Mix 5 mL of weakly acidic cation exchange resin (Duolite Co., Ltd .: C433LF) and 100 mL of 1 mol / L aqueous NaOH solution, which are adjusted to the H form, in a 200 mL Pyrex (registered trademark) beaker for 10 minutes The functional group was converted to Na form by stirring. After conversion to the Na form, the resin was recovered by filtration through 5 C filter paper. The recovered resin was washed with pure water to remove the adhering aqueous NaOH solution.

[3-2. Adsorption process]
[3-1. 5 mL of resin prepared in the substitution step and 50 mL of production process drainage were placed in a 100 mL beaker, and mixed and stirred for 10 minutes. The pH of the wastewater in the production process was 12, the lithium concentration was about 2300 mg / L, and the aluminum concentration was 100 mg / L. During the stirring, 1 mL of manufacturing process waste water was sampled every one minute, and used as an analysis sample. The relationship between the mixing and stirring time and the metal concentration in the production process drainage is shown in FIG.

[3-3. Elution process]
[3-2. In the adsorption step, 5 mL of the resin on which lithium was adsorbed was recovered by filtration through 5 C filter paper and washed with pure water. The resin and 50 mL of a 6.4% aqueous sulfuric acid solution by weight were placed in a 100 mL beaker, and mixed and stirred for 10 minutes. During the stirring, 1 mL of manufacturing process waste water was sampled every one minute, and used as an analysis sample. The relationship between the mixing and stirring time and the metal concentration in the production process drainage is shown in FIG.

  [3-1. ] Substitution process, [3-2. ] And [3-3. All elution steps were performed at normal temperature. [3-2. ] And [3-3. The metal concentration in the analysis sample sampled in the elution step of [1] was analyzed by ICP-AES.

Comparative Example 1
[4-1. Adsorption process]
In a 100 mL beaker, 5 mL of a weakly acidic cation exchange resin (Duolite Co., Ltd .: C433LF) and 50 mL of manufacturing process drainage, which are adjusted to the H shape and sold, were placed and stirred for 10 minutes. The pH of the wastewater in the production process was 12, the lithium concentration was about 2300 mg / L, and the aluminum concentration was 100 mg / L. During the stirring, 1 mL of manufacturing process waste water was sampled every one minute, and used as an analysis sample. The relationship between the mixing and stirring time and the metal concentration in the production process drainage is shown in FIG.

[4-2. Elution process]
[4-1. In the adsorption step, 5 mL of the resin on which lithium ions were adsorbed was recovered by filtration through 5 C filter paper, and washed with pure water. The resin and 50 mL of a 6.4% aqueous sulfuric acid solution by weight were placed in a 100 mL beaker, and mixed and stirred for 10 minutes. During the stirring, 1 mL of manufacturing process waste water was sampled every one minute, and used as an analysis sample. The relationship between the mixing and stirring time and the metal concentration in the production process drainage is shown in FIG.

  [4-1. ] And [4-2. All elution steps were performed at normal temperature. [4-1. ] And [4-2. The metal concentration in the analysis sample sampled in the elution step of [1] was analyzed by ICP-AES.

  In Example 1, according to FIG. 3, although the concentration of lithium decreases with time, it can be confirmed that the aluminum does not change from the initial concentration over time. Furthermore, it can be confirmed from FIG. 4 that although lithium ions are eluted from the resin after adsorption, aluminum ions are not detected in the manufacturing process waste water after the elution step. From these facts, it was found that, in the case of the Na type, aluminum ions are not adsorbed, and only lithium ions can be selectively adsorbed and recovered.

  In Comparative Example 1, it can be confirmed from FIG. 5 that the concentrations of lithium and aluminum decrease with time. Furthermore, it can be confirmed from FIG. 6 that lithium and aluminum are detected in the manufacturing process drainage after the elution step. This is because, in Comparative Example 1, since the weakly acidic cation exchange resin is a carboxy group, hydrogen ions are eluted into the production process wastewater as the lithium ion is adsorbed, and the pH of the production process wastewater decreases, and the aluminate ions are aluminum ions. It is considered that the (cation) is adsorbed to the weakly acidic cation exchange resin. From these facts, it was found that it is impossible to separate aluminum and lithium in the case of H-type.

  From the above, it has been shown that it is possible to selectively separate lithium from manufacturing process wastewater containing aluminum and lithium according to the present invention.

  Although the embodiments and examples of the present invention have been described in detail as described above, it is apparent to those skilled in the art that many modifications can be made without departing substantially from the novel matters and effects of the present invention. It will be easy to understand. Accordingly, all such modifications are intended to be included within the scope of the present invention.

  For example, in the specification or the drawings, the terms described together with the broader or synonymous different terms at least once can be replaced with the different terms anywhere in the specification or the drawings. Further, the configuration and operation of the lithium recovery method are not limited to those described in the embodiments and examples of the present invention, and various modifications can be made.

S1 substitution process, S2 adsorption process, S3 elution process, S4 regeneration process, S101 crystallization process, S102 separation process, S103 baking process, S104 water washing process

Claims (6)

A lithium recovery method for recovering lithium from manufacturing process waste water containing lithium and aluminum of positive electrode material for lithium secondary battery,
An adsorption step of bringing an ion exchange resin into contact with the waste water from the production process to selectively adsorb lithium ions to the ion exchange resin;
And an elution step of causing the lithium ion to be eluted from the ion exchange resin by bringing the aqueous solution containing an acid or a sodium salt into contact with the ion exchange resin in which the lithium ion is selectively adsorbed in the adsorption step;
The method for recovering lithium, wherein the ion exchange resin is a weakly acidic cation exchange resin having a carboxy group or a functional group of its sodium salt type.   The method for recovering lithium according to claim 1, wherein the pH of the production process waste water in the adsorption step is set to 9 or more.   The lithium concentration of the said manufacturing process waste water in the said adsorption process is 0.3 g / L or more, The collection | recovery method of the lithium of Claim 1 or 2 characterized by the above-mentioned. Before the adsorption step, the method further comprises a substitution step of substituting a functional group contained in the ion exchange resin,
The method for recovering lithium according to any one of claims 1 to 3, wherein in the substitution step, the functional group is substituted from the carboxy group to the sodium salt type. After the elution step, the method further comprises a regeneration step of regenerating the ion exchange resin,
5. The method for recovering lithium according to claim 4, wherein the regeneration step substitutes the carboxy group from the sodium salt type to the functional group in the elution step from the carboxy group to a sodium salt type. .   The method for recovering lithium according to any one of claims 1 to 4, wherein the sodium salt in the elution step is sodium sulfate.

Images