JP5539942B2 - Method for separating iron and aluminum - Google Patents

Description

  The present invention relates to a method for separating iron and aluminum, for example, a method for separating iron and aluminum from raw materials after incineration, pulverization and selection of a lithium ion battery.

  Lithium ion batteries are rapidly expanding their applications for hybrid vehicles, and the production capacity of large batteries is expected to increase rapidly due to higher unit capacity. Moreover, establishment of the valuable metal recovery method from a lithium ion battery is calculated | required with respect to the demand expansion of a lithium ion battery.

  Lithium ion batteries mainly consist of a positive electrode, a negative electrode, a separator, and a casing. The positive electrode includes a positive electrode active material containing manganese, cobalt, nickel, lithium on a current collector of aluminum foil, and a conductive agent such as carbon black. Is kneaded and applied to a fluorine-based binder. The positive electrode material is composed of an aluminum foil having a thickness of about 15 microns and a binder layer containing a positive electrode active material, and has an appearance in which a black positive electrode active material is coated on the aluminum foil.

  As a recycling method for lithium ion batteries, acid leaching is performed using raw materials after incineration, crushing and sorting used lithium ion batteries, and then each metal is extracted and separated by solvent extraction from the obtained leachate. A method has been proposed. However, if iron or aluminum is contained as an impurity in the raw material, iron or aluminum is leached due to acid leaching, which adversely affects extraction separation in solvent extraction. Therefore, when iron or aluminum is contained in the leachate obtained by acid leaching of the raw material, it is necessary to remove the iron or aluminum.

  As a method for removing iron or aluminum in an acidic solution, a neutralization method is generally proposed. As such a neutralization method, for example, Patent Document 1 discloses a method of neutralizing to pH 4.0 to 4.5 with an alkaline earth metal hydroxide. Patent Document 2 discloses a method of adjusting the pH to 4.0 to 4.5 by blowing a mixed gas of sulfurous acid gas and air or oxygen and adding calcium carbonate.

JP 2002-154825 A JP 2010-180439 A

  Some raw materials for recycling used lithium ion batteries have high iron and aluminum contents. When a raw material having a high iron and aluminum content is leached, there arises a problem that iron and aluminum are contained in a high concentration in the leachate. Metals to be collected in lithium ion battery recycling are manganese, cobalt, nickel, and lithium, and iron and aluminum must be separated as impurities.

  However, when a high-concentration iron and aluminum-containing liquid is treated by the neutralization method described in Patent Document 1 or 2, aluminum in the raw material is precipitated at a time, and a large amount of gelled aluminum hydroxide is filtered. As a result, the separation takes a very long time and the processing efficiency is poor. In addition, when the raw material contains other metals such as cobalt and nickel in addition to iron and aluminum, other metals such as cobalt and nickel in the liquid are also precipitated due to coprecipitation during neutralization. Therefore, it is difficult to efficiently recover other metals. In the method of Patent Document 2, it is specified that the coprecipitation of nickel can be suppressed, but the behavior of cobalt and lithium is not specified, and gas such as sulfurous acid gas and oxygen is purchased and blown into the solution. Need arises. As a result, it is necessary to install a blowing apparatus, to operate the apparatus, and to use an exhaust gas treatment facility when using sulfurous acid gas, and to take fire prevention measures when using oxygen.

  Then, this invention makes it a subject to provide the method of isolate | separating iron and aluminum with favorable process efficiency, and recovering | recovering other metals efficiently from the solution containing iron, aluminum, and manganese.

  As a result of intensive studies to solve the above problems, the present inventor did not separate aluminum from the solution at once with iron, but first separated and separated some aluminum by neutralization with iron. The inventors have found that by performing two-stage separation of aluminum to separate the remaining aluminum, iron and aluminum can be separated with good treatment efficiency, and other metals can be efficiently recovered.

In one aspect, the present invention completed based on the above knowledge is obtained by neutralizing a sulfuric acid acidic solution containing aluminum, iron, and manganese with a redox potential (silver / silver chloride electrode reference) of 500 mV or higher. some, and, in step 1 of separating iron, the obtained in step 1, Bei example and step 2 of the aluminum from the post-neutralization solution containing most of the aluminum is separated to recover manganese, the Step 2 is a step 2a for extracting aluminum and manganese into a solvent by solvent extraction of the post-neutralization solution obtained in Step 1, and a step 2b for washing the extract obtained in Step 2a. Step 2c of extracting aluminum and manganese into a back extract by back-extracting the washed extract obtained in Step 2b, and separating the aluminum from the back extract by neutralization. Iron and aluminum separation methods that includes a step 2d of recovering manganese and.

  In one embodiment of the method for separating iron and aluminum according to the present invention, the pH at the time of neutralization in Step 1 is 3.5 to 4.5.

In another embodiment of the method for separating iron and aluminum according to the present invention, in the step 1, the sulfuric acid acidic solution containing aluminum, iron, and manganese further contains at least one of cobalt, nickel, and lithium. And at least one of cobalt, nickel and lithium is transferred to the post-neutralization solution by the neutralization , and the step 2a is solvent-extracted from the post-neutralization solution obtained in the step 1, All of cobalt, nickel and lithium contained in the post-neutralization solution, and step 2A for extracting aluminum and manganese into a solvent, wherein step 2b is the extract obtained in step 2A. In step 2B, all of the cobalt, nickel, and lithium contained in the extract are separated from the extract by washing. Step 2c is a step 2C in which aluminum and manganese are extracted into a back extract by back extracting the washed extract obtained in Step 2B, and Step 2d is the back extract. It is process 2D which isolate | separates aluminum by neutralization from and collect | recovers manganese .

  In still another embodiment of the method for separating iron and aluminum according to the present invention, the solvent extraction in the step 2A is performed by adjusting the pH to 2.6 to 3.0 using an acidic phosphate ester extractant. .

  In still another embodiment of the method for separating iron and aluminum according to the present invention, the acidic phosphate ester extractant is bis (2-ethylhexyl) phosphate.

  In still another embodiment of the method for separating iron and aluminum according to the present invention, the washing in the step 2B is performed with a manganese sulfate solution having an equilibrium pH adjusted to 1.8 to 2.0.

  In another embodiment of the method for separating iron and aluminum according to the present invention, the back extraction in the step 2C is performed with a sulfuric acid acidic solution having a sulfuric acid concentration of 25 to 200 g / L.

  In another embodiment of the method for separating iron and aluminum according to the present invention, the pH at the time of neutralization in the process step 2D is 4.0 to 4.5.

  In yet another embodiment of the method for separating iron and aluminum according to the present invention, the sulfuric acid acidic solution containing aluminum, iron, and manganese in the step 1 is obtained by leaching a waste material of a lithium ion battery with sulfuric acid. Leachate.

  ADVANTAGE OF THE INVENTION According to this invention, the method of isolate | separating iron and aluminum with favorable process efficiency and recovering | recovering other metals efficiently from the solution containing iron, aluminum, and manganese can be provided.

It is a flowchart which shows the thought of the separation method of iron and aluminum which concerns on this invention. It is a flowchart of the separation method of iron and aluminum concerning the embodiment of the present invention. Using sodium hydroxide aqueous solution as a neutralizing agent, when neutralization treatment was performed by changing the pH value, the rate of decrease in the neutralization reaction solution relative to the neutralization reaction of iron, aluminum, manganese, cobalt, and nickel It is a graph to show. It is a graph which shows the relationship between the equilibrium pH at the time of solvent extraction, and the extraction rate of each element.

  The method for separating iron and aluminum according to the embodiment of the present invention can be suitably used for, for example, a method for recovering valuable metals from a used lithium ion battery main body. The present invention can be used for a method of separating iron and aluminum, which are impurities, from a solution generated when processing the contained positive electrode material by neutralization and solvent extraction. Hereinafter, the case where iron and aluminum in the leachate in lithium ion battery recycling are separated by neutralization treatment and solvent extraction will be described as an example, but the present invention is not limited to the following examples, and iron and aluminum other than this are also described. Of course, it can be used in various applications for separating aluminum.

  FIG. 1 is a flowchart showing the concept of the iron and aluminum separation method according to the present invention. As shown in FIG. 1, in the present invention, aluminum is not separated from the solution together with iron at a time, but first, only a part of aluminum is precipitated by neutralization with iron and separated (step 1 in FIG. 1). After that, by separating the remaining aluminum (step 2 in FIG. 1), the two-stage separation of aluminum can separate iron and aluminum with good processing efficiency and efficiently recover other metals. it can. In step 1, the Fe content in the solution is mainly separated as an Fe hydroxide by neutralization. In step 2, the Al content in the solution is mainly separated. The Al component separated in this step 2 may be separated in any form, for example, it may be separated as an Al hydroxide by neutralization, and Al is selectively selected using activated carbon or an ion exchange resin. Adsorption separation may be performed, and after the substance in the liquid after the treatment in Step 1 is neutralized and separated as a solid, Al may be separated by dry treatment.

  FIG. 2 is a flowchart of a method for separating iron and aluminum according to an embodiment of the present invention. As a method for separating iron and aluminum according to an embodiment of the present invention, first, an acid leaching solution is prepared. As the acid leaching solution, a sulfuric acid acidic solution containing aluminum, iron, and manganese obtained in lithium ion battery recycling can be used. For this reason, the acid leaching solution may contain cobalt, nickel, lithium, and the like in addition to aluminum, iron, and manganese. Such an acid leachate is typically 10-300 g / L sulfuric acid, 0.001-10 g / L iron, 0.001-20 g / L aluminum, 0.001-30 g / L manganese, It is composed of 0.001 to 40 g / L cobalt, 0.001 to 30 g / L nickel, and 0.001 to 30 g / L lithium.

  Next, iron is separated and removed from the acid leaching solution as a hydroxide by neutralization. The neutralizing agent may be an alkali metal or alkaline earth metal hydroxide aqueous solution or a carbonate aqueous solution. For example, an aqueous solution of sodium hydroxide or sodium carbonate may be used. FIG. 3 shows a neutralization treatment using a sodium hydroxide aqueous solution as a neutralizing agent, and the neutralization reaction solution before the neutralization reaction of iron, aluminum, manganese, cobalt and nickel. Indicates the rate of decrease. It can be seen from FIG. 3 that the pH in the neutralization treatment is preferably adjusted in the range of 3.5 to 4.5. If the pH exceeds 4.5, the reduction rate of other metals such as manganese, cobalt, nickel, etc. will increase. If the pH is less than 3.5, iron removal may be insufficient.

  The oxidation-reduction potential (silver / silver chloride electrode standard) during the neutralization treatment is preferably 500 mV or more. If it is 500 mV or less, the oxidation of iron in the liquid is insufficient and the removal of iron in the neutralization treatment is insufficient. As a method for increasing the oxidation-reduction potential to 500 mV or more, there are a method of adding hydrogen peroxide water and a method of blowing air.

  By prescribing the pH value and oxidation-reduction potential during neutralization as described above, while aluminum is well separated and removed from the acid leachate as a hydroxide, aluminum is only partially precipitated as a hydroxide, Most can be left in the solution after neutralization. For this reason, the time spent for removing the aluminum hydroxide having poor filterability in the neutralization step is shortened, and precipitation of other metals such as cobalt and nickel due to coprecipitation during neutralization is suppressed. As a result, other metals can be efficiently recovered in the subsequent process.

Next, aluminum and manganese are extracted from the neutralized solution obtained by filtration from the acid leaching solution by solvent extraction.
The extractant used here is preferably an acidic phosphate ester extractant. Among acidic phosphate ester extractants, bis (2-ethylhexyl) phosphate has a pH value close to that for extracting aluminum and manganese, so that it can be used for simultaneous extraction of aluminum and manganese. Particularly preferred as an extractant.
The solvent extraction is performed by mixing a solvent prepared by diluting the above extractant with a hydrocarbon solvent and a solution after neutralization. When bis (2-ethylhexyl) phosphate is used as the extractant, the mixing ratio of the extractant and the hydrocarbon solvent is preferably 1: 3. As the hydrocarbon solvent, aromatic, paraffinic, naphthenic solvents and the like can be used, and naphthenic solvents are more preferable.

  FIG. 4 shows the relationship between the equilibrium pH at the time of solvent extraction and the extraction rate of each element. FIG. 4 shows that the equilibrium pH during extraction of manganese and aluminum is preferably adjusted to a range of 2.6 to 3.0 by adding a neutralizing agent. As the neutralizing agent, sodium hydroxide, sodium carbonate or the like can be used. If the equilibrium pH is higher than 3.0, aluminum hydroxide contained in the leachate may be generated and clog the piping of the apparatus. On the other hand, if the pH is lower than 2.6, the extraction rate of manganese and aluminum is lowered, and extraction and separation of manganese and aluminum from the leachate may not be sufficiently performed.

  Next, it wash | cleans using the manganese sulfate solution with which equilibrium pH was adjusted to 1.8-2.0 with respect to the solvent (extract) containing aluminum and manganese obtained by solvent extraction. By this washing, metals such as cobalt, nickel and lithium contained in the extract other than aluminum and manganese are recovered by extraction. The recovered cleaning liquid containing the metal can be returned as a pre-extraction liquid for solvent extraction, whereby the loss of metals such as cobalt, nickel, and lithium can be reduced. If the equilibrium pH of the manganese sulfate solution at the time of washing is less than 1.8, there is a possibility that back extraction occurs and a part of manganese in the solvent is extracted into the washing solution. Further, if the equilibrium pH of the manganese sulfate solution at the time of washing is more than 2.0, the washing may be insufficient because it is close to the pH at which cobalt is extracted.

  Next, aluminum and manganese are extracted into a back extract by back extracting the extract after the washing step with a sulfuric acid acidic solution. The sulfuric acid concentration of the sulfuric acid acidic solution is preferably 25 to 200 g / L. When the sulfuric acid concentration is less than 25 g / L, there is a possibility that the back extraction of aluminum may be insufficient, and when it exceeds 200 g / L, there is a problem that costs are increased.

  Next, the back extract obtained by back extraction is neutralized to separate aluminum and manganese in the reaction solution. The neutralizing agent may be an alkali metal or alkaline earth metal hydroxide aqueous solution or a carbonate aqueous solution. For example, an aqueous solution of sodium hydroxide or sodium carbonate may be used. The pH in the neutralization treatment is preferably adjusted to a range of 4.0 to 4.5. If the pH exceeds 4.5, the decrease rate of manganese may increase. If the pH is less than 4.0, removal of aluminum may be insufficient. By this neutralization, aluminum is separated and recovered as a hydroxide. Manganese is contained in the post-neutralization solution, and can be recovered by known means if necessary.

  Examples of the present invention will be described below, but the examples are for illustrative purposes and are not intended to limit the invention.

Example 1
The sulfuric acid solution containing various metals listed in Table 1 (H ₂ SO ₄ concentration 10 g / L) was adjusted to pH 4.2 with sodium hydroxide and neutralized with a redox potential (silver / silver chloride electrode standard) of 650 mV. Processed. Table 2 shows the decreasing rate of each element concentration in the liquid after the neutralization treatment when compared with that before the neutralization treatment. Table 3 shows the concentration of each element in the liquid after the neutralization treatment.

  Table 2 shows that most of the iron was removed by the neutralization treatment. Manganese, cobalt, and nickel were also reduced by about 20%, but the rate of reduction was smaller than when iron and aluminum were removed by neutralization treatment as shown in Comparative Example 1 described later. Moreover, although Al hydroxide was produced, since it was a small amount, it was easy to separate by filtration.

  A neutralized solution (the composition is described in Table 4) and a solvent obtained by diluting bis (2-ethylhexyl) phosphate (LANXESS trade name: D2EHPA) to 25 vol% with a naphthenic solvent (Shell Chemicals trade name: shellsol D70). Mixing and stirring were performed so that the organic phase / aqueous phase = 4 (volume ratio), and manganese and aluminum were extracted while adjusting with sodium hydroxide so that the equilibrium pH was 2.8. Table 5 shows the extraction rate of each element. Table 6 shows the concentration of each element in the solution after extraction.

  Tables 5 and 6 show that most of manganese and aluminum in the liquid were extracted. Co is also extracted by about 20%, but the extracted Co can be recovered by washing with solvent extraction, so there is no loss.

Next, the extracted solvent was back-extracted with a sulfuric acid solution (H ₂ SO ₄ concentration 100 g / L) to obtain a back-extracted solution having the composition shown in Table 7, and then the back-extracted solution was hydroxylated. The pH was adjusted to 4.0 with sodium and neutralized. Table 8 shows the decreasing rate of each element concentration in the liquid after the neutralization treatment when compared with that before the neutralization treatment. Table 9 shows the concentration of each element in the liquid after the neutralization treatment.

  From Tables 8 and 9, it can be seen that manganese and aluminum can be separated by neutralization treatment.

(Comparative Example 1)
A sulfuric acid solution containing various metals described in Table 10 (H ₂ SO ₄ concentration 10 g / L) was adjusted to pH 5.0 with sodium hydroxide and neutralized. Table 11 shows the decreasing rate of each element concentration in the liquid after the neutralization treatment when compared with that before the neutralization treatment. Table 12 shows the concentration of each element in the liquid after the neutralization treatment.

  From Example 1 and Comparative Example 1, rather than removing iron and aluminum at a time by neutralization treatment, a part of iron and aluminum was separated and removed by neutralization treatment, and the remaining most by solvent extraction. It can be seen that the loss of other metals is smaller when the two-stage aluminum separation method of separating and removing aluminum is used.

Claims (9)

Step 1 of separating a part of aluminum and iron from a sulfuric acid acidic solution containing aluminum, iron, and manganese by neutralization with an oxidation-reduction potential (silver / silver chloride electrode reference) of 500 mV or more ;
Step 2 for recovering manganese by separating aluminum from the neutralized solution containing most of the aluminum obtained in Step 1, and
Bei to give a,
Step 2 is
Step 2a for extracting aluminum and manganese into a solvent by solvent extraction of the post-neutralization solution obtained in Step 1, and
A step 2b of washing the extract obtained in the step 2a;
Step 2c for extracting aluminum and manganese into a back extract by back extracting the washed extract obtained in Step 2b;
Step 2d for separating manganese from the back extract by neutralization and recovering manganese;
A method for separating iron and aluminum.   The method for separating iron and aluminum according to claim 1, wherein the pH during neutralization in Step 1 is 3.5 to 4.5. In the step 1, the acidic sulfuric acid solution containing aluminum, iron, and manganese further contains at least one of cobalt, nickel, and lithium, and at least one of cobalt, nickel, and lithium is neutralized by the neutralization. It is a method to transfer to the back solution ,
Step 2a is a solvent extraction of the post-neutralization solution obtained in Step 1, so that all of cobalt, nickel, and lithium contained in the post-neutralization solution, and aluminum and manganese are used as solvents. Step 2A of extracting to
The step 2b is a step 2B in which all of the cobalt, nickel and lithium contained in the extract are separated from the extract by washing the extract obtained in the step 2A.
The step 2c is a step 2C of extracting aluminum and manganese into a back extract by back extracting the washed extract obtained in the step 2B.
The method for separating iron and aluminum according to claim 1 or 2 , wherein step 2d is step 2D in which manganese is recovered by separating aluminum from the back-extracted liquid by neutralization . The method for separating iron and aluminum according to claim 3 , wherein the solvent extraction in the step 2A is performed by adjusting the pH to 2.6 to 3.0 using an acidic phosphate ester extractant. The method for separating iron and aluminum according to claim 4 , wherein the acidic phosphate-based extractant is bis (2-ethylhexyl) phosphate. The method for separating iron and aluminum according to any one of claims 3 to 5 , wherein the washing in the step 2B is performed with a manganese sulfate solution having an equilibrium pH adjusted to 1.8 to 2.0. The method for separating iron and aluminum according to any one of claims 3 to 6 , wherein the back extraction in the step 2C is performed with a sulfuric acid acidic solution having a sulfuric acid concentration of 25 to 200 g / L. The method for separating iron and aluminum according to any one of claims 3 to 7 , wherein the pH during neutralization in Step 2D is 4.0 to 4.5. Aluminum in the step 1, iron, and sulfuric acid solution containing manganese, iron and aluminum according to scrap lithium-ion battery to any one of claims 1 to 8, which is a leaching solution obtained by leaching with sulfuric acid Separation method.

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