JP7054536B2 - Rare metal extraction method and rare metal recovery method - Google Patents

Description

The present invention relates to a method for extracting rare metals and a method for recovering rare metals.

With the increase in demand for electric vehicles, mobile batteries, etc., the demand for lithium-ion secondary batteries is increasing. The lithium ion secondary battery contains rare metals such as Co, Ni, and Li in the positive electrode active material and the like. However, ores containing these rare metals are unevenly distributed on the earth. For example, Co is mainly produced in Congo, which accounts for nearly 50% of ore production. When an unexpected natural disaster or political instability occurs in a producing country, it becomes difficult to secure a stable supply of rare metals. Further, for example, when Co is purified from a rare metal, Cu, Ni and the like can be obtained as intermediate by-products, but if only Co is purified in a state where the usage destination of these is uncertain, the cost increases.

As one means for realizing a stable supply of rare metals, a method of extracting rare metals from used lithium ion secondary batteries and reusing them is being studied. For example, Patent Document 1 describes a method of leaching lithium ion battery scrap into an acidic solution to extract manganese.

Japanese Unexamined Patent Publication No. 2018-28150

However, the method described in Patent Document 1 is a wet process, has poor reaction efficiency, and takes time to extract rare metals. Further, the method described in Patent Document 1 needs to treat the wastewater of the solution used for the reaction, and has a problem from the viewpoint of environmental load. Further, there is a problem that the equipment becomes large due to the drainage equipment and the like, and the production cost increases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a rare metal extraction method and a rare metal recovery method capable of improving productivity.

The present inventors have found that the extraction efficiency of rare metals can be increased by reacting rare metals in the vapor of an organic solvent. That is, the present invention provides the following means for solving the above problems.

(1) In the method for extracting a rare metal according to the first aspect, a gasified organic solvent and a mixture containing a rare metal are reacted, and the rare metal is extracted from the mixture containing the rare metal as a first gas containing a metal complex.

(2) In the method for extracting rare metals according to the above embodiment, the mixture containing the rare metals may contain a plurality of types of rare metals, and the plurality of types of rare metals may be taken out from the mixture containing the rare metals.

(3) In the rare metal extraction method according to the above embodiment, the flow path may be filled with the mixture containing the rare metal, and the mixture containing the rare metal may be allowed to flow in the flow path.

(4) In the rare metal extraction method according to the above embodiment, the flow path may be filled with an inorganic material together with the mixture containing the rare metal.

(5) In the rare metal extraction method according to the above embodiment, the organic solvent may be supplied in excess of the amount necessary for the reaction with the metal complex in the reaction space.

(6) In the method for extracting a rare metal according to the above embodiment, the mixture containing the rare metal may be heated to control the valence of the rare metal before the mixture containing the rare metal is reacted with the gasified organic solvent.

(7) In the method for extracting rare metals according to the above embodiment, the organic solvent is acetylacetone (Hacac), bis (pentane-2,4-dionat) propane-1,2-diimine (H2 _Pnaa ), tetra-isopropylthiophos. It may be any one of foramide (Hprps), tetra-phenyldithiophosphoramide (Hphps), and tetra-alkyldithioimide phosphine (( _Ph2PS ) 2NH).

(8) The rare metal recovery method according to the second aspect is the first step of performing the rare metal extraction method according to the above aspect, and the first gas is cooled or dissolved in an organic solvent to obtain a compound containing the metal complex. It has a second step of producing and a third step of separating the compound for each metal species contained in the metal complex.

(9) The method for recovering a rare metal according to the above embodiment further comprises a fourth step of recovering the rare metal by thermally decomposing, hydrolyzing, carbonic acid chloride treatment or reducing treatment of each of the separated substances separated from the compound. May be.

(10) In the method for recovering rare metals according to the above embodiment, the organic solvent produced in the fourth step may be reused in the first step.

(11) In the method for recovering a rare metal according to the above embodiment, in the third step, the compound containing the metal complex is heated, and the compound is separated by utilizing the difference in sublimation conditions depending on the metal species contained in the metal complex. You may.

The rare metal extraction method and the rare metal recovery method according to the above aspects can improve productivity.

It is a conceptual diagram of the recovery device used in the rare metal recovery method which concerns on 1st Embodiment. It is a schematic diagram of an example of a gas generation part and a reaction part in the recovery apparatus used in the rare metal recovery method according to the first embodiment. It is a schematic diagram of an example of the separation part in the recovery device used in the recovery method of rare metals according to the first embodiment. It is a schematic diagram of another example of the separation part in the recovery apparatus used in the recovery method of rare metal according to 1st Embodiment. It is the result of the Raman spectrum measured in Example 1. It is a photograph which showed the state of the process of Example 5. It is a graph which showed the change of the recovery rate of each metal complex by a heating temperature in Example 8. In Example 8, the change in the recovery rate when the mole fraction of Co (acac) ₃ and Mn (acac) ₃ is changed is shown. In Example 8, the result of the mole fraction of Co (acac) ₃ in the residual substance for each heating time is shown. In Example 8, it is the analysis result of the state of Co (acac) ₃ and the state of Mn (acac) ₃ after heating at 90 degreeC for 120 minutes. In Example 9, the change in the recovery rate when the mole fraction of Al (acac) ₃ and Co (acac) ₃ is changed is shown. It is a result of the recovery rate of each complex when the heating temperature was set to 80 ° C. in Example 10. It is a result of the recovery rate of each complex when the heating temperature was 90 ° C. in Example 10.

Hereinafter, the present embodiment will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios of each component may differ from the actual ones. be. The materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and the present invention can be appropriately modified without changing the gist thereof.

"First embodiment"
The method for recovering rare metals according to the first embodiment includes a first step, a second step, a third step, and a fourth step. FIG. 1 is a conceptual diagram of a recovery device used in the rare metal recovery method according to the first embodiment. The recovery device 100 includes a gas generation unit 10, a reaction unit 20, a separation unit 30, and a recovery unit 40.

The first step is an extraction step of extracting rare metals from a mixture containing rare metals. The first step is an example of a method for extracting rare metals. Mixtures containing rare metals contain one or more rare metals. Rare metals are present in the mixture as compounds. The mixture containing rare metals is, for example, a positive electrode material for a used lithium ion secondary battery. The mixture containing rare metals is not limited to the positive electrode material of the used lithium ion secondary battery. The mixture containing a rare metal may contain, for example, an oxide of a rare metal. Also, the valence of rare metals does not matter.

Rare metals include tungsten, cobalt, nickel and rare earths for which stable supply is important. Rare metals are specifically Li, Be, B, Sc, Ti, V, Cr, Mn, Co, Ni, Ga, Ge, Se, Rb, Sr, Y, Zr, Nb, Mo, Pd, In, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Pt, Tl, Bi. In particular, Li, Mn, Ni, Co, Ta, W, Nd, and Dy are preferable extraction targets.

In the first step, the rare metal is extracted as a first gas containing a metal complex of the rare metal. At the same time as the rare metal, Al, Fe and Cu may be extracted as a metal complex of Al, Fe and Cu. The first gas is obtained by reacting a gasified organic solvent with a mixture containing a rare metal. The reaction proceeds by contacting a gasified organic solvent with a mixture containing rare metals. The gasified organic solvent may be supplied so as to penetrate the deposited surface of the mixture containing the deposited rare metal, for example. By passing the gasified organic solvent through the mixture containing the deposited rare metal, the reactivity between the gasified organic solvent and the mixture containing the rare metal is enhanced. Further, the reaction rate may be increased by heating the reaction space. When the mixture containing rare metals contains a plurality of rare metals, the plurality of rare metals can be extracted at the same time.

The organic solvent is a solvent that forms a metal complex with a rare metal. That is, the organic solvent has a metal complex ability to form a complex with a rare metal. The organic solvent is, for example, diketone, phosphine oxide, phosphoramide. Specific examples of the organic solvent include, for example, acetylacetone (Hacac), bis (pentane-2,4-dionat) propane-1,2-diimine (H2 _Pnaa ), tetra-isopropylthiophosphoramide (Hprps), tetra-phenyl. Examples thereof include dithiophosphoramide (Hphps) and tetra-alkyldithioimide phosphine (( _Ph2PS ) 2NH). Acetylacetone is inexpensive and easily reacts with many kinds of rare metals, and is preferably used. When the mixture containing rare metals contains a plurality of rare metals, it is preferable to use acetylacetone. By using acetylacetone, multiple kinds of rare metals can be easily extracted. It is also possible to extract multiple types of rare metals at the same time.

When the organic solvent is acetylacetone, acetylacetone is gasified according to the following formula (1) to become acetylacetonate (acac).
C ₅ H ₈ O ₂ = C ₅ H ₇ O _2- + H ⁺ ... ⁽ 1)

Acetylacetonate forms a metal complex of a rare metal with Co, for example, according to the following reaction formulas (2) and (3).
2C ₅ H ₈ O ₂ + CoO → Co (acac) ₂ + H ₂ O ... (2)
3C _{5H 8} O ₂ + CoO _1.5 → Co (acac) ₃ + 3 / 2H ₂ O ... (3)
Moreover, although the reaction formula is described by taking the case where the rare metal is Co as an example, the same applies to the case other than Co. For example, Mn (acac) ₂ , Mn (acac) ₃ , Ni (acac) ₂ , Ni (acac) ₃ , and Li (acac) are examples of metal complexes in which rare metals are other than Co. Further, Al (acac) ₃ and Fe (acac) ₃ are examples of metal complexes of metals other than rare metals. The first gas is a gas containing these metal complexes.

The first step is performed by the gas generation unit 10 and the reaction unit 20 of the recovery device 100 (see FIG. 1). FIG. 2 is a schematic view of an example of a gas generation unit 10 and a reaction unit 20 in a recovery device used in the rare metal recovery method according to the first embodiment.

The gas generation unit 10 is a portion for gasifying an organic solvent. The gas generating unit 10 shown in FIG. 2 has a heater 11 and a flask 12. The flask 12 has a gas discharge port 12a and a gas supply port 12b. The gas discharge port 12a is a discharge port for the gasified organic solvent L. The gas supply port 12b is a supply port for the inert gas G into the flask 12.

The organic solvent L is injected into the flask 12. The organic solvent L is heated by the heater 11 and gasified. The heater 11 heats the organic solvent L to a temperature at which the organic solvent L gasifies. The heating by the heater 11 is preferably, for example, at a temperature within ± 20 ° C. around the boiling point of the organic solvent L in atmospheric pressure, and is preferably at a temperature equal to or lower than the boiling point. The heating by the heater 11 is performed, for example, at 100 ° C. or higher and 200 ° C. or lower. When the pressure in the flask 12 is set to a reduced pressure atmosphere, the heating temperature can be lowered.

It is preferable that the organic solvent L supplied into the flask 12 is supplied in excess of the amount necessary for the metal complex reaction between the organic solvent L and the rare metal. For example, Co (acac) ₂ , which is one of the metal complexes, is solid at room temperature. When the metal complex is solidified in the gas generation unit 10 and the reaction unit 20 described later, the flow path may be blocked and the extraction efficiency of rare metals is lowered. On the other hand, when the organic solvent L is excessively supplied, the unreacted organic solvent L returns to the solution again after passing through the reaction space. The organic solvent L returned to the solution dissolves the metal complex. Therefore, it prevents the metal complex from solidifying and enhances the extraction efficiency of rare metals.

Further, instead of supplying the organic solvent L in excess, an organic solvent that does not react with rare metals may be separately supplied into the flask 12. Here, "not reacting with a rare metal" means that it does not chemically bond with a rare metal (including, for example, a coordinate bond). The organic solvent that does not react with rare metals is, for example, a hydrocarbon solvent such as toluene or xylene. The metal complex is also soluble in toluene and prevents the metal complex from solidifying.

The gasified organic solvent flows from the gas discharge port 12a to the reaction unit 20 (flow f1 in FIG. 1). The inert gas G increases the pressure in the flask 12 and prevents the backflow of steam and the like from the reaction unit 20. The inert gas G is, for example, He or Ar.

The reaction unit 20 has an extraction unit 21, a condenser 22, and a storage unit 23. The extraction unit 21 is a portion that generates the first gas. The condenser 22 is a portion that produces a first solution. The storage unit 23 is a unit for storing the first solution.

The extraction unit 21 has a flow path inside. The flow path is filled with a mixture M1 containing a rare metal. The mixture M1 containing a rare metal may be in the form of powder or pellets. For example, the mixture M1 containing a rare metal may be installed on a quartz boat, and the quartz boat may be installed inside the extraction unit 21. Further, the mixture M1 containing a liquid rare metal may be impregnated with another substance and placed in the flow path. It is preferable to flow the mixture M1 containing a rare metal in the extraction unit 21. "Flow" means that the powder moves in the flow path, and means that the mixture M1 containing a rare metal is agitated by the gasified organic solvent L. The flow of the mixture M1 containing a rare metal in the extraction unit 21 enhances the reaction efficiency between the gasified organic solvent L and the mixture M1 containing a rare metal. The flow path may be filled with the inorganic material S together with the mixture M1 containing a rare metal. The inorganic material S is an inorganic substance that does not react with the gasified organic solvent L. The inorganic material S is, for example, SiO ₂ . Since the inorganic material S does not react with the gasified organic solvent L, it is not decomposed and maintains the flow in the extraction unit 21.

The organic solvent L gasified from the gas generation unit 10 flows into the flow path inside the extraction unit 21. The gasified organic solvent L is supplied so as to penetrate the mixture M1 containing the rare metal filled in the extraction unit 21, for example. When the mixture M1 containing a rare metal is installed on a quartz boat, the gasified organic solvent L passes through the surface thereof. The extraction unit 21 may be heated by an external heating means (not shown). In the flow path, the gasified organic solvent L reacts with the mixture M1 containing a rare metal. The reaction produces a first gas. When the extraction unit 21 is heated, the heating temperature is, for example, equal to or higher than the boiling point of the organic solvent L and lower than the decomposition temperature of the organic solvent L. For example, when the organic solvent L is acetylacetone, the heating temperature is preferably 100 ° C. or higher and 300 ° C. or lower. The heating temperature is measured by a thermometer connected to the extraction unit 21. The circumference of the extraction unit 21 may be covered with a heat insulating material such as glass wool so that the temperature of the extraction unit 21 does not drop.

Then, the second step is performed. The second step is a step of producing a compound from the first gas generated in the extraction unit 21. The compound may be a liquid containing a rare metal or a solid. Here, the "compound" is a liquid in which the first gas is condensed, a solid in which the first gas is condensed, a liquid in which the first gas is dissolved in an organic solvent, and a liquid or a solid in which the first gas is condensed is dissolved in an organic solvent. It is a liquid. The above-mentioned first solution corresponds to, for example, a liquid in which the first gas is condensed, a liquid in which the first gas is dissolved in an organic solvent, a liquid in which the first gas is condensed, or a liquid in which a solid is dissolved in an organic solvent. From the viewpoint of preventing blockage of the flow path, the compound is preferably a liquid. The second step is performed, for example, in the condenser 22 and the storage unit 23 of the reaction unit 20. The condenser 22 cools the first gas after the reaction. The first gas is liquefied or solidified by cooling. In the first step, if an organic solvent L that is more than necessary for the reaction with the metal complex is supplied into the flask 12 or an organic solvent that does not react with the metal complex is separately supplied into the flask 12, the metal complex is solidified. It can be prevented and the first gas can be easily liquefied. That is, the compound can be taken out as the first solution regardless of whether the first gas is liquefied or solidified. The first solution contains rare metals. The storage unit 23 stores the liquefied first solution. When the first gas is solidified, the solidified compound is deposited in the reservoir 23. When the first gas becomes the first solution, the volume changes abruptly. By supplying the inert gas G from the gas supply port 12b of the flask 12, the pressure of the extraction unit 21 is increased. Backflow of the first solution in the condenser 22 is prevented.

The first solution may be one in which the first gas is dissolved in an organic solvent. The first gas is soluble in an organic solvent. For example, the first solution may be generated by blowing the first gas into the stored organic solvent, or the organic solvent may be flowed in the middle of the flow path of the first gas to generate the first solution. .. The organic solvent may be the same as or different from the organic solvent L used in the reaction, but the same one is easier to reuse. Further, the first gas may be cooled and taken out as a solid compound.

The compound produced in the second step is carried to the separation unit 30 (flow f2 in FIG. 1). In the separation unit 30, the third step is performed. The third step is a step of separating the compound containing the metal complex (for example, the first solution). Separation is performed, for example, by fractional distillation utilizing the difference in boiling point, chromatography utilizing the difference in the ease of chemical adsorption, and utilizing the difference in sublimation conditions. The sublimation conditions are, for example, a sublimation start temperature, a sublimation speed, and the like. Hereinafter, the case of fractional distillation using the difference in boiling points will be specifically described as an example. The boiling point of the rare metal metal complex contained in the compound differs depending on the rare metal species contained therein. For example, Mn (acac) ₂ has a boiling point of 130 ° C., Co (acac) ₂ has a boiling point of 150 ° C., and Ni (acac) ₂ has a boiling point of 220 ° C. Utilizing this difference in boiling point, the compound is fractionated for each metal species contained in the metal complex.

FIG. 3 is a schematic view of an example of the separation unit 30 in the recovery device used in the rare metal recovery method according to the first embodiment. The separation unit 30 has a rectification tower 31. The rectification tower 31 has a supply pipe 32, a gas discharge pipe 33, a solution discharge pipe 34, and a partition wall 35. The supply pipe 32 is a portion that supplies the first solution to the inside of the rectification tower 31. The gas discharge pipe 33 is a portion for discharging gas from the rectification tower 31. The solution discharge pipe 34 is a portion for discharging the solution liquefied by fractional distillation. The partition wall 35 is a partition that divides the inside of the rectification tower 31 into a plurality of regions R1, R2, R3, R4, and R5 in the vertical direction. The number of partition walls 35 is not particularly limited. The partition wall 35 has a hole 35A through which gas flows in the vertical direction.

The compound produced in the second step (for example, the first solution) is supplied into the rectification column 31 via the supply pipe 32 (flow f2). When the rectification column 31 is heated from below, the compound evaporates. The temperature inside the rectification column 31 decreases from the heated bottom to the top. Since the metal complex of a rare metal has a different boiling point depending on the metal species contained in the metal complex, it is liquefied in any of the regions R1, R2, R3, R4, and R5 divided by the partition wall 35. The liquefied rare metal metal complex is stored on the partition wall 35. The liquefied rare metal metal complex is discharged from the solution discharge pipe 34. The unliquefied component of the first solution is discharged from the gas discharge pipe 33. Further, the unvaporized component of the first solution is discharged from the solution discharge pipe 34 at the lower part of the rectification column 31.

For example, a case where the compound containing the metal complex (for example, the first solution) contains Mn (acac) ₂ , Co (acac) ₂ , Ni (acac) ₂ and Li (acac) ₂ will be specifically described. .. First, the temperature of each region R1, R2, R3, R4, R5 is set. For example, the temperature of the region R1 is 250 ° C. or higher, the temperature of the region R2 is 220 ° C. or higher and lower than 250 ° C., the temperature of the region R3 is 150 ° C. or higher and lower than 220 ° C., the temperature of the region R4 is 130 ° C. or higher and lower than 150 ° C., and the region R5. The temperature is less than 130 ° C.

Li (acac) ₂ has a melting point of 250 ° C. Li (acac) ₂ is liquefied at least in the region R2 and stored in the partition wall 35 in the region R2. The stored Li (acac) ₂ is discharged from the solution discharge pipe 34 (flow f3a in FIGS. 1 and 3). On the other hand, the boiling points of Mn (acac) ₂ , Co (acac) ₂ and Ni (acac) ₂ are 220 ° C. or lower. Therefore, they exist as gases in the regions R1 and R2 and reach above the rectification column 31. As described above, Mn (acac) ₂ has a boiling point of 130 ° C., Co (acac) ₂ has a boiling point of 150 ° C., and Ni (acac) ₂ has a boiling point of 220 ° C. Therefore, Ni (acac) ₂ is liquefied in the region R3, Co (acac) ₂ is liquefied in the region R4, and Mn (acac) ₂ is liquefied in the region R5. Each liquefied metal complex is discharged from the solution discharge pipe 34 (flows f3b, f3c, f3d in FIGS. 1 and 3). Mn (acac) ₂ , Co (acac) ₂ , Ni (acac) ₂ , and Li (acac) ₂ are fractionated by being discharged from different solution discharge pipes 34.

Further, FIG. 4 is a schematic view of another example of the separation unit 30 in the recovery device used in the rare metal recovery method according to the first embodiment. The separation unit 30 has a separation device 51. The separating device 51 has a sublimation pipe 52 and a cooling pipe 53. The sublimation pipe 52 fits into the opening 52A of the cooling pipe 53. The sublimation pipe 52 has an exhaust port 52e. The exhaust port 52e is a gas discharge port in the sublimation pipe 52. When the inside of the sublimation tube 52 becomes a vacuum, it is possible to suppress the generation of by-products due to oxidation and the like. The cooling pipe 53 has an inlet 53i and an outlet 53o for cooling water. The cooling water is injected into the cooling pipe 53 from the inlet 53i and discharged from the outlet 53o.

The separation device 51 can also be used, for example, when the compound containing the metal complex is a solid. The compound containing the metal complex is stored in the bottom of the sublimation tube 52, and the sublimation tube 52 is heated. The sublimation tube 52 is heated uniformly, for example, when the outer surface is immersed in an oil bath. The metal complex is sublimated from the compound containing the metal complex by heating. The sublimated metal complex is cooled and solidified in the vicinity of the outer surface of the cooling tube 53. The solidified metal complex adheres to the outer surface of the cooling tube 53.

The sublimation conditions of the metal complex differ depending on the type of the metal complex contained in the compound. For example, the sublimation start temperature of Co (acac) ₂ is 169 ° C, the sublimation start temperature of Co (acac) ₃ is 187 ° C, the sublimation start temperature of Ni (acac) ₂ is 214 ° C, and Mn (acac). ) ₂ has a sublimation start temperature of 220 ° C., and Li (acac) has a sublimation start temperature higher than 220 ° C. These sublimation start temperatures are determined, for example, from a differential scanning calorimeter (DSC). In order to suppress the influence of oxidation by oxygen, it is preferable to measure the sublimation start temperature in an inert gas atmosphere or in a vacuum. By utilizing this difference in sublimation start temperature, the compound can be separated for each metal species contained in the metal complex.

Finally, the separated product containing the separated metal complex reaches the recovery unit 40 (flows f3a, f3b, f3c, f3d in FIG. 1). In the collection unit 40, the fourth step is performed. The fourth step is a step of thermally decomposing, hydrolyzing, carbonic acid chloride treatment or reducing treatment of each separated substance to separate rare metals. The separated product separated in the third step is in a gas, liquid, or solid state.

In the fourth step, the rare metal is separated as a simple substance or a compound. For example, when the rare metal is a highly reactive metal such as Li, it is separated as a compound such as an oxide or a carbonate. When the rare metal is a highly reactive metal such as Li, the fourth step is preferably treated in an inert gas atmosphere or an oxygen atmosphere.

The following shows an example of the chemical formula for the separation of rare metals, taking the case where the solution containing the metal complex is Co as an example.
Co (acac) ₂ + H ₂ → Co + 2C ₅ H ₈ O ₂ … (4)
Co (acac) ₂ + H ₂ O → CoO + 2C ₅ H ₈ O ₂ … (5)
Co (acac) ₂ + H ₂ CO ₃ → CoCO ₃ + 2C ₅ H ₈ O ₂ … (6)
The chemical formula (4) corresponds to the reaction of reduction treatment with hydrogen, the chemical formula (5) corresponds to the reaction of hydrolysis, and the chemical formula (6) corresponds to the reaction of carbonic acid chloride treatment.

Below, the same reaction formula holds even when the solution containing the metal complex is other than Co. As a result, in the fourth step, the rare metals M2a, M2b, M2c, and M2d are recovered separately (see FIG. 1).

Acetylacetone can be obtained after the reaction by any of the methods of the chemical formulas (4) to (6). Acetylacetone is the organic solvent L used for the reaction with the mixture M1 containing a rare metal in the second step. Therefore, the reaction by-product (organic solvent L) remaining in the fourth step can be reused in the first step again. That is, the organic solvent L circulates from the first step to the fourth step and is recycled.

As described above, in the method for extracting and recovering a rare metal according to the first embodiment, the rare metal is extracted as a metal complex from the mixture M1 containing the rare metal in the gas phase. The reaction temperature at this time is as low as about 100 ° C to 300 ° C. Therefore, the rare metal extraction method and recovery method according to the first embodiment can extract rare metals with low energy consumption.

Further, the rare metal extraction reaction in the first step and the separation treatment in the third step are performed three-dimensionally, and can be performed with a significantly higher reaction efficiency as compared with the wet process. Further, in the fractional distillation treatment, it is only necessary to divide the region to be liquefied by utilizing the difference in boiling point, and each rare metal can be very easily separated and taken out from the mixture containing a plurality of rare metals. Even when sublimation conditions are used, each rare metal can be very easily separated and taken out from a mixture containing a plurality of rare metals simply by controlling the heating profile of the compound.

Further, the rare metal extraction method and the recovery method according to the first embodiment can all be carried out using the same organic solvent L. That is, the organic solvent L can be circulated in the recovery device 100, which is excellent in recyclability and can suppress the production cost. In addition, the reaction process can be carried out in a closed environment, and the environmental load can be reduced.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments and varies within the scope of the gist of the present invention described in the claims. Can be transformed / changed.

For example, the mixture containing rare metals may be heated before reacting the mixture containing rare metals with the gasified organic solvent (first step). The valence of rare metals changes with heating, for example, from Co ²⁺ to Co ³⁺ . The reaction efficiency of the metal complex formation reaction is higher when the valence of the rare metal is trivalent than when it is divalent. By controlling the valence of rare metals by heating, the extraction and recovery efficiency of rare metals can be further improved. The heating may be performed at a temperature at which the valence of the rare metal can be controlled, and is preferably 1200 ° C. or lower, more preferably 1000 ° C. or lower, for example.

Further, for example, the rare metal recovery process may be stopped in the second step or the third step. At the time of performing the second step, the rare metal is extracted as, for example, a mixed liquid. Further, at the time of performing the third step, for example, a plurality of substances separated for each rare metal can be obtained. Rare metals are still extracted at these points before reaching the final stage. In particular, in the state after the third step (for example, the state of a plurality of solutions or the state of solid-liquid separation), different rare metals are concentrated and extracted. Even at the stage of the extract before it is finally returned to metal, there are many industrial means of use, and the extract itself is also valuable.

(Example 1)
In Example 1, an extraction device having a steam generating unit 10 and a reaction unit 20 shown in FIG. 2 was prepared. The reaction section 20 was filled with 0.6 g of SiO ₂ powder and 3.9 g of cobalt oxide (Co ₃ O ₄ ). Further, 100 ml of acetylacetone was poured into the flask 12 and heated at 130 ° C. Argon was supplied into the flask 12 as the inert gas G. Then, gasified acetylacetone was supplied to the extraction unit 21 for one hour. Then, the first gas generated in the reaction was condensed by the condenser 22 and stored in the flask (reservoir 23). The color of the stored solution was tan.

The solution obtained using Raman spectroscopy was analyzed and the spectrum was measured. FIG. 5 is the result of the Raman spectrum measured in Example 1. The horizontal axis is the wave number and the vertical axis is the intensity. As a result of the analysis, the obtained spectrum was in agreement with the spectrum of Co (acac) ₃ . It was confirmed that cobalt can be extracted from cobalt oxide in the form of a metal complex. The yield of Co (acac) ₃ was 50% based on the raw material of cobalt oxide (Co ₃ O ₄ ).

(Example 2)
Example 2 is different in that manganese oxide (MnO ₂ ) is used instead of cobalt oxide (Co ₃ O ₄ ). Acetylacetone was heated at 140 ° C., the temperature of the reaction section 20 was set to 250 ° C., and the reaction was carried out for 1 hour. As a result, a black solution was stored in the flask. The solution of acetylacetone was transparent, and the color of the reservoir changed, confirming that Mn (acac) ₂ was extracted.

(Reference example 1)
Reference Example 1 is different in that iron oxide (Fe ₂ O ₃ ) is used instead of cobalt oxide (Co ₃ O ₄ ). Acetylacetone was heated at 140 ° C., the temperature of the reaction section 20 was set to 250 ° C., and the reaction was carried out for 1 hour. As a result, an orange solution was stored in the flask. The solution of acetylacetone was transparent, and the color of the reservoir changed, confirming that Fe (acac) ₃ was extracted.

(Reference example 2)
Reference Example 2 is different from Reference Example 1 in that the apparatus configuration is changed so that iron oxide is deposited on a quartz boat and acetylacetone gas flows on the surface thereof. Iron oxide was used in each of the three types of Fe ₂ O ₃ , Fe ₃ O ₄ , and Fe O. In each case, an orange solution was stored in the flask. The concentration of the stored liquid was higher in the order of Fe ₃ O ₄ , Fe ₂ O ₃ , and Fe O.

Next, the weight of iron oxide after the reaction was measured for each quartz boat, and the weight change before and after the reaction was measured. The weight loss rate in the case of Fe ₂ O ₃ was 7.7%, the weight loss rate in the case of Fe ₃ O ₄ was 6.2%, and the weight loss rate in the case of Fe O was 28.4%. rice field. Therefore, it can be said that Fe (acac) ₂ or Fe (acac) ₃ could be extracted from the color and weight reduction rate of the stored liquid.

(Example 3)
Example 3 is different from Reference Example 2 in that cobalt oxide (CoO) is used instead of iron oxide. The color of the reservoir of Example 3 was reddish brown. The weight loss rate before and after the reaction was 28.6%. Therefore, it can be said that Co (acac) ₂ could be extracted from the color and weight reduction rate of the stored liquid.

(Example 4)
Example 4 is different from Reference Example 2 in that a sample obtained by crushing the positive electrode material of the lithium ion battery is used. Example 4 was carried out twice by changing the flow rate of the inert gas (Ar). The flow rate of the inert gas (Ar) was 250 ccm for the first time and 30 ccm for the second time. The color of the reservoir after the first treatment was dark yellow. The color of the stored liquid after the second treatment was darker than that of the first treatment. In either case, it can be seen that the metal complex is contained in the reservoir.

Then, the obtained stored liquid was analyzed by an emission spectroscopic analyzer (ICP). As a result, it was confirmed that Li, Al, Mn, Fe, Co, Ni and Cu were extracted from the stored liquid. That is, a plurality of metals could be extracted as a metal complex from the positive electrode material of lithium ion.

The above-mentioned Examples 1 to 4 and Reference Examples 1 and 2 correspond to the above-mentioned first step. By reacting various metal species with acetylacetone, it could be extracted as a metal complex.

(Example 5)
In Example 5, a mixed powder obtained by mixing 0.2070 g of a pink powder of Co (acac) 2.2H ₂ O and _{0.2052 g of a beige powder of Mn (acac) 2.2H 2 O is} put into a flask. It was sealed inside and heated. For heating, the temperature was gradually increased to room temperature, 50 ° C, 100 ° C, 130 ° C, and 140 ° C. The temperature was maintained for 10 minutes from the time when each temperature reached 50 ° C., 100 ° C., and 130 ° C., and then the temperature was raised. The temperature was maintained for 2 hours from the time when the temperature reached 140 ° C. The pressure in the flask was 50 hPa, and the flask was heated using an oil bath while rotating at 10 rpm.

FIG. 6 is a photograph showing the state of the process of Example 5. The left is before heating and the right is after heating. By heating, a part of the mixed powder stored in the bottom of the flask was sublimated. Since the temperature of the part exposed from the liquid surface of the oil bath was low, the sublimated gas adhered to the inner surface of the upper part of the flask. In addition, residual powder that did not sublimate was confirmed at the bottom of the flask.

The deposits adhering to the inner surface of the upper part of the flask were dissolved in acetylacetone. The total mass of the solution was 124.32 g and the solution was analyzed using ICP analysis and an absorptiometer (UVvis). The residual powder was also analyzed by XRD.

As a result of ICP analysis, the composition ratio of Mn and Co in the deposit containing Mn (acac) ₂ and Co (acac) ₂ was Mn: Co = 1: 6.4. The composition ratio of Mn and Co in the mixed powder before heating containing Mn (acac) ₂ and Co (acac) ₂ was Mn: Co = 1: 1, and a large amount of Co sublimated. Moreover, from the result of UVvis, almost all Co ₍ acac) _2.2H2O was sublimated and recovered as an deposit. Furthermore, as a result of XRD analysis of the residual powder, it was confirmed that Mn ₍ acac) _2.2H2O remained.

(Example 6)
In Example 6, a mixed powder obtained by mixing 0.2070 g of a pink powder of Co (acac) _{2.2H 2O} and 0.20604 g of a black powder of Mn (acac) ₃ is sealed in a flask. Heated. For heating, the temperature was gradually increased to room temperature, 50 ° C, 100 ° C, 140 ° C, and 150 ° C. The temperature was maintained for 10 minutes from the time when each temperature reached 50 ° C., 100 ° C., and 140 ° C., and then the temperature was raised. The temperature was maintained for 2 hours from the time when the temperature reached 150 ° C. The pressure in the flask was 50 hPa, and the flask was heated using an oil bath while rotating at 10 rpm.

Also in Example 6, a part of the mixed powder stored in the bottom of the flask was sublimated by heating. Since the temperature of the part exposed from the liquid surface of the oil bath was low, the sublimated gas adhered to the inner surface of the upper part of the flask. In addition, residual powder that did not sublimate was confirmed at the bottom of the flask.

The deposits adhering to the inner surface of the upper part of the flask were dissolved in acetylacetone. The total mass of the solution was 149.08 g and the solution was analyzed using ICP analysis and an absorptiometer (UVvis). The residual powder was also analyzed by XRD.

As a result of ICP analysis, the composition ratio of Mn and Co in the deposit containing Mn (acac) ₃ and Co (acac) ₃ was Mn: Co = 1: 6.9. The composition ratio of Mn and Co in the mixed powder before heating containing Mn (acac) ₃ and Co (acac) ₃ was Mn: Co = 1: 1, and a large amount of Co sublimated. As a result of XRD analysis of the residual powder, it was confirmed that Mn ₍ acac) _3.2H2O remained.

(Example 7)
Prepare samples of Co (acac) 2.2H ₂ O, Co (acac) _{3.2H 2} O, Mn (acac) _{2.2H 2 O} , Ni _{(acac) 2.2H 2 O ,} and Li (acac). Then, under inert conditions in which argon was circulated, the respective sublimation start temperatures were measured using a differential scanning calorimeter (DSC).

The sublimation start temperatures are 169 ° C for Co (acac) _{2.2H 2} O, 187 ° C for Co (acac) _{3.2H 2 O} , 214 ° C for Ni (acac) _{2.2H 2} O, and Mn (acac). It was confirmed that _{2.2H 2O} was 220 ° C. It was confirmed that Li (acac) did not sublimate even when the temperature was raised to 220 ° C., and the temperature was higher than that. That is, it is easy to sublimate in the order of Co (acac) ₂ > Co (acac) ₃ > Ni (acac) ₂ > Mn (acac) ₂ > Li (acac), and each substance utilizes this difference in sublimation temperature. Can be separated.

(Example 8)
Next, in order to exclude the influence of oxygen during heating, an experiment was conducted using the separation device 51 shown in FIG. First, Mn (acac) ₃ having a purity of 97% and Co (acac) ₃ having a purity of 97% were weighed in an amount of 30 mg each and sealed in the bottom of the sublimation tube 52. That is, two kinds of mixed substances of Co (acac) ₃ and Mn (acac) ₃ were sealed in the bottom of the sublimation tube 52. Sublimation and the inside of the sublimation tube 52 was depressurized to 10 Pa or less.

Next, the sublimation tube 52 was immersed in an oil bath to sublimate the enclosed raw material. When the temperature of the oil bath was 100 ° C. or lower, the oil bath was immersed in an oil bath preheated to 100 ° C. for 1 hour. When the temperature of the oil bath was higher than 100 ° C., the sublimation tube 52 was immersed in the oil bath at 100 ° C., the temperature was raised at 1 ° C./min, and the immersion was continued for 1 hour after reaching the target temperature. The sublimated sublimation gas was cooled and solidified on the outer surface of the cooling pipe 53. The solidified complex was dissolved in acetylacetone, and the recovery rates of each were determined using visible ultraviolet spectroscopic measurement (ultraviolet-visible near-infrared spectrophotometer (V-630IRM: JASCO)) and ICP emission spectroscopic analysis.

FIG. 7 is a graph showing changes in each recovery rate depending on the heating temperature. For example, in FIG. 7, when the heating temperature was 110 ° C., the recovery rate of Mn (acac) ₃ was almost 100%. On the other hand, the recovery rate of Co (acac) ₃ was 50%. That is, Mn (acac) ₃ is removed from the residual powder remaining at the bottom of the sublimation tube 52, and only Co (acac) ₃ can be separated.

The same study was carried out by changing the mole fractions of Co (acac) ₃ and Mn (acac) ₃ in the mixed material to be encapsulated. FIG. 8 shows the change in the recovery rate when the mole fraction of Co (acac) ₃ and Mn (acac) ₃ is changed. FIG. 8 (a) shows the recovery rate of Mn (acac) ₃ , and FIG. 8 (b) shows the recovery rate of Co (acac) ₃ .

Even if the mole fraction of the mixed substance was changed, the recovery rate of each did not change significantly. On the other hand, when heated at the same temperature, there was no change in the tendency that Mn (acac) ₃ was more likely to sublimate than Co (acac) ₃ in any temperature range.

Further, the heating temperature was fixed at 90 ° C., the mole fraction of Co (acac) ₃ and Mn (acac) ₃ in the mixed substance was fixed at 3: 1 and Co (acac) in the residual substance for each heating time. The mole fraction of ₃ was calculated. FIG. 9 shows the result. As shown in FIG. 9, the mole fraction of Co (acac) ₃ in the residual substance increased as the heating time elapsed. That is, the purity of Co (acac) ₃ can be increased from the mixed substance, and Co (acac) ₃ can be separated by advancing the heating time.

Further, the state of Co (acac) ₃ and the state of Mn (acac) ₃ after heating at 90 ° C. for 120 minutes were determined from the results of visible ultraviolet spectroscopic measurement and ICP emission spectroscopic analysis. FIG. 10 shows the result. As shown in FIG. 10, most of Mn (acac) ₃ became a gas phase and sublimated. On the other hand, nearly 90% of Co (acac) ₃ remained in the solid phase. In FIG. 10, the loss is the amount of the gas in the gas phase that has not recrystallized on the outer surface of the cooling pipe 53 and has flowed out to the outside.

(Example 9)
The same study as in Example 8 was carried out by changing the mixed substance to be sealed in the sublimation tube 52. Al (acac) ₃ having a purity of 97% and Co (acac) ₃ having a purity of 97% were weighed in an amount of 30 mg each and sealed in the bottom of the sublimation tube 52. That is, two kinds of mixed substances of Co (acac) ₃ and Al (acac) ₃ were sealed in the bottom of the sublimation tube 52.

Next, the sublimation tube 52 was immersed in an oil bath to sublimate the enclosed raw material. When the temperature of the oil bath was 100 ° C. or lower, the oil bath was immersed in an oil bath preheated to 100 ° C. for 1 hour. When the temperature of the oil bath was higher than 100 ° C., the sublimation tube 52 was immersed in the oil bath at 100 ° C., the temperature was raised at 1 ° C./min, and the immersion was continued for 1 hour after reaching the target temperature. The sublimated sublimation gas was cooled and solidified on the outer surface of the cooling pipe 53. The solidified complex was dissolved in acetylacetone, and the recovery rates of each were determined using visible ultraviolet spectroscopic measurement (ultraviolet-visible near-infrared spectrophotometer (V-630IRM: JASCO)) and ICP emission spectroscopic analysis.

FIG. 11 shows the change in the recovery rate when the mole fraction of Al (acac) ₃ and Co (acac) ₃ is changed. FIG. 11 (a) shows the recovery rate of Al (acac) ₃ , and FIG. 11 (b) shows the recovery rate of Co (acac) ₃ .

Most of Al (acac) ₃ sublimated even at low temperatures of 80 ° C and 90 ° C. On the other hand, Co (acac) ₃ hardly sublimated at low temperatures of 80 ° C. and 90 ° C. That is, by heating in these temperature ranges, Al (acac) ₃ and Co (acac) ₃ can be separated from the mixed substance.

(Example 10)
The same study as in Example 8 and Example 9 was carried out by changing the mixed substance to be sealed in the sublimation tube 52. Al (acac) ₃ having a purity of 97%, Mn (acac) ₃ having a purity of 97%, and Co (acac) ₃ having a purity of 97% were weighed in an amount of 30 mg each and sealed in the bottom of the sublimation tube 52. That is, a mixed substance of three kinds of Co (acac) ₃ , Mn (acac) ₃ and Al (acac) ₃ was sealed in the bottom of the sublimation tube 52.

Next, the sublimation tube 52 was immersed in an oil bath to sublimate the enclosed raw material. The temperature of the oil bath was 80 ° C. and 90 ° C. The sublimated sublimation gas was cooled and solidified on the outer surface of the cooling pipe 53. The solidified complex was dissolved in acetylacetone, and the recovery rates of each were determined using visible ultraviolet spectroscopic measurement (ultraviolet-visible near-infrared spectrophotometer (V-630IRM: JASCO)) and ICP emission spectroscopic analysis.

FIG. 12 shows the results of the recovery rate of each complex when the heating temperature was set to 80 ° C. in Example 10. FIG. 13 shows the results of the recovery rate of each complex when the heating temperature was 90 ° C. in Example 10. Although the metal complexes of Al and Mn sublimated in any temperature range, the metal complexes of Co hardly sublimated. Therefore, the metal complex of Co can be separated first, and then the metal complex of Al and Mn can be separated.

The above-mentioned Examples 1 to 4 and Reference Examples 1 and 2 correspond to the above-mentioned third step. Certain types of metal complexes can be separated from various metal complexes.

10 Steam generation part 11 Heater 12 Flask 12a Steam discharge port 12b Gas supply port 20 Reaction part 21 Flow layer 22 Condenser 23 Storage part 30 Fractional distillation part 31 Smelting tower 32 Supply pipe 33 Gas discharge pipe 34 Solution discharge pipe 35 Partition 35A Hole 40 Recovery device 51 Separation device 52 Sublimation tube 52A Opening 52e Exhaust port 53 Cooling tube 53i Inlet 53o Outlet 100 Recovery device f1, f2, f3a, f3b, f3c, f3d Flow G Inactive gas L Organic solvent M1 Mixture M2a, M2b, M2c, M2d Rare metal R1, R2, R3, R4 Region S Inorganic material

Claims (10)

It has a step of reacting a gasified organic solvent with a mixture containing a plurality of rare metals, and extracting a plurality of rare metals from the mixture containing the plurality of rare metals as a first gas containing a metal complex .
Extraction of rare metals in which the organic solvent is supplied in excess of the amount necessary for the reaction between the plurality of rare metals and the metal complex, or an organic solvent that does not react with the plurality of rare metals is separately supplied into the reaction space. Method. The method for extracting a rare metal according to claim 1 , wherein the flow path is filled with the mixture containing the rare metal, and the mixture containing the rare metal is allowed to flow in the flow path. The method for extracting a rare metal according to claim 2 , wherein the flow path is filled with an inorganic material together with the mixture containing the rare metal. The extraction of a rare metal according to any one of claims 1 to 3 , wherein the mixture containing the rare metal is heated before the mixture containing the rare metal is reacted with the gasified organic solvent to control the valence of the rare metal. Method. The organic solvent is acetylacetone (Hacac), bis (pentane-2,4-dionat) propane-1,2-diimine (H2 _Pnaa ), tetra-isopropylthiophosphoramide (Hprps), tetra-phenyldithiophosphoramide. The method for extracting a rare metal according to any one of claims 1 to 4 , which is either (Hphps) or tetra _- alkyldithioimide phosphine ((Ph2PS) 2NH). The first step of performing the method for extracting a rare metal according to any one of claims 1 to 5 .
The second step of cooling or dissolving the first gas in an organic solvent to produce a compound containing the metal complex, and
A method for recovering a rare metal, which comprises a third step of separating the compound for each metal species contained in the metal complex. The method for recovering a rare metal according to claim 6 , further comprising a fourth step of recovering the rare metal by thermally decomposing, hydrolyzing, carbonic acid chloride treatment or reducing treatment of each of the separated substances separated from the compound. The method for recovering a rare metal according to claim 7 , wherein the organic solvent produced in the fourth step is reused in the first step. The recovery of the rare metal according to claim 7 or 8 , wherein in the third step, the compound containing the metal complex is heated and the compound is separated by utilizing the difference in sublimation conditions depending on the metal species contained in the metal complex. Method. The method for recovering a rare metal according to any one of claims 6 to 9, wherein the third step is performed at a temperature of less than 250 ° C.

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