METHOD FOR RECOVERING METALS AND APPARATUS FOR RECOVERING METALS

Abstract

To provide a metal recovery method capable of easily recovering Co as metal Co.SOLUTION: A metal recovery method holds a voltage for a recovery device 20A having a power source 3, an electronic load 30, an electrolyte 40, a first tank 100A which has a positive electrode that is connected to the power source 3 and the electronic load 30 and contains at least Co, and a supply port and a discharge port of H2O and is immersed in the electrolyte 40, and a second tank 200A which has a negative electrode connected to the power source 3 and the electronic load 30 and has the supply port and the discharge port of H2O, and is immersed in the electrolyte 40, so that the potential of the positive electrode becomes higher than the potential of the negative electrode by the power source 3 and the electronic load 30, and recovers Co eluted from the positive electrode.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a metal recovery method and a metal recovery apparatus. [Background technology]

[0002] In recent years, nickel-metal hydride batteries and other storage batteries have become widespread as storage batteries for vehicles and other purposes. One of the main uses of storage batteries is in hybrid and electric vehicles. As a result, a large amount of the storage batteries installed in the vehicles remains as waste after use during their life cycle. There is a demand for these used storage batteries to be reused as resources.

[0003] For example, a storage battery generally has a structure in which electrodes (negative and positive electrodes), a separator, and an electrolyte are enclosed within an exterior body. Materials containing metals such as Co and Ni (e.g., nickel hydroxide, cobalt hydroxide, and other positive electrode active materials used in the positive electrode) may be used for the electrodes. For used storage batteries, it is required to recover and reuse the metals contained in the electrodes.

[0004] For example, Patent Document 1 discloses a method for recovering valuable metals (Cu, Ni, Co, etc.), which includes the steps of preparing a charge containing at least the valuable metal as a raw material, heating and melting the raw material to form an alloy and slag, and separating the slag to recover an alloy containing the valuable metal, and in which metallic aluminum is introduced into the raw material as a reducing agent when the raw material is heated and melted. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-085446 A Summary of the Invention [Problem to be solved by the invention]

[0006] It should be noted that recovery of metals contained in components from the viewpoint of reusing metals is required not only in storage batteries but also in various other fields.

[0007] In light of such conventional demands, the present disclosure aims to provide a metal recovery method and a metal recovery device that can easily recover cobalt (Co) components as metallic Co. [Means for solving the problem]

[0008] Means for solving the above problems include the following aspects. <1> Power supply, An electronic load; An electrolyte; a first tank having a positive electrode containing at least Co connected to the power source and the electronic load, and an HO supply port and an HO discharge port, and being immersed in the electrolyte; a second tank having a negative electrode connected to the power source and the electronic load, and an H2O supply port and discharge port, and being immersed in the electrolyte; For a recovery device having A metal recovery method comprising: maintaining a voltage by the power source and the electronic load so that the potential of the positive electrode is higher than the potential of the negative electrode, and recovering Co dissolved from the positive electrode. <2> The positive electrode contains Ni, The power source and the electronic load are used to maintain a voltage such that the potential of the positive electrode is higher than the potential of the negative electrode, and then Ni remaining in the positive electrode is recovered. <1> 2. A method for recovering metals according to claim 1. <3> At least one of the first tank and the second tank is a nickel-metal hydride battery; <1> or <2> 2. A method for recovering metals according to claim 1. <4> The nickel-metal hydride storage battery is a used storage battery. <3> 2. A method for recovering metals according to claim 1. <5> A water electrolysis reaction is caused by maintaining the voltage, and O2 gas is extracted from the first tank and H2 gas is extracted from the second tank. <1> ~ <4> 13. The method for recovering metals according to claim 12. <6> Power supply, An electronic load; An electrolyte; a first tank having a positive electrode containing at least Co connected to the power source and the electronic load, and an HO supply port and an HO discharge port, and being immersed in the electrolyte; a second tank having a negative electrode connected to the power source and the electronic load, and an H2O supply port and discharge port, and being immersed in the electrolyte; having A metal recovery device that recovers Co dissolved from the positive electrode by maintaining a voltage such that the potential of the positive electrode is higher than the potential of the negative electrode using the power supply and the electronic load. <7> The positive electrode contains Ni, The power source and the electronic load can hold a voltage so that the potential of the positive electrode is higher than the potential of the negative electrode, and then Ni remaining in the positive electrode can be recovered. <6> A metal recovery apparatus according to claim 1. <8> At least one of the first tank and the second tank is a nickel-metal hydride battery; <6> or <7> A metal recovery apparatus according to claim 1. <9> The nickel-metal hydride storage battery is a used storage battery. <8> A metal recovery apparatus according to claim 1. <10> A water electrolysis reaction is caused by maintaining the voltage, and O2 gas is extracted from the first tank and H2 gas is extracted from the second tank. <6> ~ <9> 13. A metal recovery apparatus according to claim 12. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a metal recovery method and a metal recovery device that can easily recover Co components as metallic Co. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic perspective view illustrating a metal recovery device according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a schematic perspective view illustrating a metal recovery device according to an embodiment of the present disclosure. [Diagram 3] FIG. 1 is a schematic diagram showing an example of the configuration of a nickel-metal hydride storage battery. [Figure 4] 1 is a graph showing voltage cycles in an experimental example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The metal recovery method and metal recovery device of the present disclosure will be described in detail below with reference to the drawings. Each of the drawings shown below is a schematic illustration, and the size and shape of each part are appropriately exaggerated to facilitate understanding. In addition, in this specification, when expressing an aspect in which another member is arranged relative to a certain member, the term "above" or "below" is used, unless otherwise specified, it includes both a case in which another member is arranged directly above or below a certain member so as to be in contact with the certain member, and a case in which another member is arranged above or below a certain member via another member.

[0012] [Metal recovery method and metal recovery device] The metal recovery device according to the present disclosure includes a power source, an electronic load, an electrolyte, a first tank having a positive electrode connected to the power source and the electronic load and containing at least Co, and a supply and discharge port for H2O, and being immersed in the electrolyte, and a second tank having a negative electrode connected to the power source and the electronic load, and a supply and discharge port for H2O, and being immersed in the electrolyte. The power source and the electronic load maintain a voltage such that the potential of the positive electrode is higher than the potential of the negative electrode, thereby recovering Co dissolved from the positive electrode.

[0013] One embodiment of a metal recovery device according to the present disclosure will be described with reference to FIG. FIG. 1 is a schematic perspective view illustrating a metal recovery device according to an embodiment of the present disclosure. As shown in FIG. 1, the recovery device 20A includes a power source 3, an electronic load 30, a housing 4 in which an electrolytic solution 40 is accommodated, a first tank 100A and a second tank 200A immersed in the electrolytic solution 40 in the housing 4, and a distillation device 5. The power source 3 and the electronic load 30 adjust the increase and decrease of the voltage, and the voltage can be maintained at a desired voltage. A power source having an electronic load function may be used. The first tank 100A has a positive electrode containing Co and Ni, and this positive electrode is connected to the power source 3 and the electronic load 30. The second tank 200A has a negative electrode, and this negative electrode is connected to the power source 3 and the electronic load 30. The first tank 100A has a water supply port, and a water supply pipe (not shown) equipped with a water supply pump is connected to this supply port, and the water supply pump (not shown) is driven to supply water (H2O). The second tank 200A has a water supply port, to which a water supply pipe (not shown) equipped with a water supply pump 6 is connected, and the water supply pump 6 is driven to supply water (H2O). The first tank 100A has an oxygen (O2) exhaust passage 101, which is connected to the distillation device 5. The second tank 200A has a hydrogen (H2) exhaust passage 201. An electrolyte is contained in the distillation device 5, and the electrolyte in the distillation device 5 and the electrolyte 40 in the housing 4 are circulated through a circulation pipe (not shown) equipped with a liquid delivery pump 7. The distillation device 5 has a water vapor (H2O) exhaust port 8.

[0014] The recovery device 20A uses nickel-metal hydride batteries as the first tank 100A having a positive electrode containing Co and Ni, and the second tank 200A having a negative electrode. These nickel-metal hydride batteries may be used nickel-metal hydride batteries. The term "used" refers to a battery whose charging capacity is lower than that of the battery immediately after manufacture.

[0015] In the recovery device 20A, the power source 3 and the electronic load 30 maintain a voltage such that the potential of the positive electrode in the first tank 100A is higher than the potential of the negative electrode in the second tank 200A. This causes a water electrolysis reaction in the water (H2O) supplied to the first tank 100A and the second tank 200A, and O2 gas is generated from the first tank 100A. The generated O2 gas is sent to the distillation device 5 through the exhaust passage 101, and is converted to HCoO2 gas, which will be described later, in the distillation device 5. - and is discharged as water vapor (H2O) from the outlet 8. In the second tank 200A, a water electrolysis reaction occurs to generate H2 gas, which is discharged from the discharge passage 201. From the viewpoint of efficiently causing the water electrolysis reaction in the water (H2O) supplied to the first tank 100A and the second tank 200A, it is preferable to maintain the potential difference between the positive electrode and the negative electrode at 1.48 V or more. The reaction formula at the positive electrode and the negative electrode is shown below. (Positive electrode)OH - →1 / 2H2O+1 / 4O2+e - (Negative electrode) H2O+e - →1 / 2H2+OH -

[0016] From the viewpoint of facilitating the progress of the water electrolysis reaction, the potential difference obtained by subtracting the potential of the negative electrode in the second tank from the potential of the positive electrode in the first tank is more preferably in the range of 1.48 V to 2.00 V, and from the viewpoint of efficiency, is even more preferably in the range of 1.55 V to 1.80 V. In this case, the temperature is preferably higher, with the upper limit being 80° C.

[0017] In the recovery device 20A, the power source 3 and the electronic load 30 maintain the voltage so that the potential of the positive electrode in the first tank 100A is higher than the potential of the negative electrode in the second tank 200A, and Co is converted from the positive electrode to HCoO2. - The dissolved HCoO2 is dissolved in the electrolyte 40. -is sent to the distillation apparatus 5 by driving the liquid pump 7, and is oxidized with O2 gas to precipitate and be recovered as metallic CoO2. Note that some Co is not dissolved but is pushed out as a solid from the positive electrode, and this can also be recovered. In addition, by continuing to hold the voltage so that the potential of the positive electrode is higher than the potential of the negative electrode by the power source 3 and the electronic load 30, after Co and the like are completely dissolved from the positive electrode, Ni2O3 and Ni(OH)2 remain on the positive electrode, and can be recovered and separated as metallic Ni from this positive electrode. For example, Fe and Ni may remain on the positive electrode, and metallic Ni can be recovered by separating them based on the difference in melting point. From the viewpoint of efficiently dissolving Co from the positive electrode, it is preferable to keep the voltage at the positive electrode between 0.60V and 1.00V. Note that the reaction formula for dissolving Co and remaining Ni is shown below. CoO2 →Co(OH)3 →Co(OH)2 →Co NiO2→1 / 2Ni2O3→Ni(OH)2→Ni

[0018] In addition, from the viewpoint of efficiently causing the water electrolysis reaction and efficiently dissolving Co from the positive electrode, the voltage may be repeatedly changed. For example, the voltage may be held so that the potential difference between the positive electrode and the negative electrode is 1.48 V or more, and then the voltage may be repeatedly held so that the voltage at the positive electrode is 0.60 V or more and 1.00 V or less. This allows the water electrolysis reaction to occur more efficiently when the potential difference between the positive electrode and the negative electrode is held at 1.48 V or more, while Co can be more efficiently dissolved from the positive electrode when the voltage of the positive electrode is held at 0.60 V or more and 1.00 V or less. For example, the voltage may be held for 50 minutes so that the potential difference between the positive electrode and the negative electrode is 1.48 V or more, and then the voltage may be adjusted to hold the voltage for 10 minutes so that the voltage of the positive electrode is 0.60 V or more and 1.00 V or less, and this cycle may be repeated.

[0019] Next, another embodiment will be described.

[0020] Another embodiment of the metal recovery device according to the present disclosure will be described with reference to Fig. 2. Note that the same components as those in the recovery device shown in Fig. 1 are denoted by the same reference numerals. FIG. 2 is a schematic perspective view illustrating a metal recovery device according to an embodiment of the present disclosure. As shown in FIG. 2, the recovery device 20B includes a power source 3, an electronic load 30, a housing 4 in which an electrolytic solution 40 is accommodated, a first tank 100B and a second tank 200B immersed in the electrolytic solution 40 in the housing 4, and a distillation device 5. In the recovery device 20B, a plurality of nickel-hydrogen storage batteries (six nickel-hydrogen storage batteries in FIG. 2) are used as both the first tank 100B and the second tank 200B. Each of the six nickel-hydrogen storage batteries in the first tank 100B has a positive electrode containing Co and Ni, and these positive electrodes are all connected to the power source 3 and the electronic load 30. Each of the six nickel-hydrogen storage batteries in the second tank 200B has a negative electrode, and these negative electrodes are all connected to the power source 3 and the electronic load 30. The first tank 100B has a water supply port, to which a water supply pipe (not shown) equipped with a water supply pump is connected, and water (H2O) is supplied by driving the water supply pump (not shown). The second tank 200B has a water supply port, to which a water supply pipe (not shown) equipped with a water supply pump 6 is connected, and water (H2O) is supplied by driving the water supply pump 6. The first tank 100B has an oxygen (O2) exhaust passage 101, which is connected to the distillation device 5. The second tank 200B has a hydrogen (H2) exhaust passage 201. The distillation device 5 contains an electrolyte, and the electrolyte in the distillation device 5 and the electrolyte 40 in the housing 4 are circulated through a circulation pipe (not shown) equipped with a liquid delivery pump 7. The distillation device 5 has a water vapor (H2O) exhaust port 8.

[0021] In the recovery device 20B, the nickel-metal hydride storage batteries used in the first tank 100B and the second tank 200B may be used nickel-metal hydride storage batteries.

[0022] In the recovery device 20B, the power source 3 and the electronic load 30 maintain the voltage so that the potential of the positive electrode in the first tank 100B is higher than the potential of the negative electrode in the second tank 200B. This causes a water electrolysis reaction in the water (H2O) supplied to the first tank 100B and the second tank 200B, and O2 gas is generated from the first tank 100B. The generated O2 gas is sent to the distillation device 5 through the exhaust passage 101, and is converted to HCoO2 gas, which will be described later, in the distillation device 5. - and is discharged from the outlet 8 as water vapor (H2O). In the second tank 200B, a water electrolysis reaction occurs to generate H2 gas, which is discharged from the discharge passage 201. From the viewpoint of efficiently causing a water electrolysis reaction in the water (H2O) supplied to the first tank 100B and the second tank 200B, it is preferable to maintain the potential difference between the positive electrode and the negative electrode at 1.48 V or more. The potential difference between the positive electrode and the negative electrode is more preferably in the range of 1.48 V to 2.00 V, and even more preferably in the range of 1.55 V to 1.80 V. In addition, the temperature is preferably higher, with the upper limit being 80°C.

[0023] In the recovery device 20B, the power source 3 and the electronic load 30 maintain the voltage so that the potential of the positive electrode in the first tank 100B is higher than the potential of the negative electrode in the second tank 200B, and Co is converted from the positive electrodes of the six nickel-metal hydride storage batteries to HCoO2. - The dissolved HCoO2 is dissolved in the electrolyte 40. - is sent to the distillation apparatus 5 by driving the liquid pump 7, where it is oxidized with O2 gas and can be precipitated and recovered as metallic CoO2. Note that some Co is not dissolved but is pushed out as a solid from the positive electrode, and this can also be recovered. In addition, after the voltage is maintained by the power source 3 and the electronic load 30 and Co and the like are completely dissolved from the positive electrodes of the six nickel-metal hydride storage batteries, Ni2O3 and Ni(OH)2 remain in each positive electrode, and can be recovered from these positive electrodes as metallic Ni. From the viewpoint of efficiently dissolving Co from the positive electrodes, it is preferable to maintain the voltage at the positive electrodes at 0.60 V or more and 1.00 V or less.

[0024] In addition, from the viewpoint of efficiently causing the water electrolysis reaction and efficiently dissolving Co from the positive electrode, the voltage may be repeatedly changed. For example, the voltage may be repeatedly held (e.g., held for 50 minutes) so that the potential difference between the positive electrode and the negative electrode is 1.48 V or more, and then the voltage may be repeatedly held (e.g., held for 10 minutes) so that the voltage at the positive electrode is 0.60 V to 1.00 V. This allows the water electrolysis reaction to occur more efficiently when the potential difference between the positive electrode and the negative electrode is held at 1.48 V or more, while allowing Co to be more efficiently dissolved from the positive electrode when the voltage at the positive electrode is held at 0.60 V to 1.00 V.

[0025] As described above, according to the metal recovery method and metal recovery device of the present disclosure, Co contained in the positive electrode can be easily recovered as metallic Co (i.e., pure Co). Furthermore, when Ni is contained in the positive electrode, this Ni can be easily recovered as metallic Ni (i.e., pure Ni).

[0026] In the present disclosure, a nickel-metal hydride storage battery can be applied to one or both of the first tank and the second tank. This nickel-metal hydride storage battery may be a used nickel-metal hydride storage battery. In other words, according to the present disclosure, Co and Ni contained in the positive electrode of a used nickel-metal hydride storage battery can be easily recovered as metal Co and metal Ni.

[0027] In the present disclosure, the power source and electronic load are used to hold the voltage of the water (H2O) supplied to the first tank and the second tank so that the potential of the positive electrode is higher than the potential of the negative electrode (for example, the potential difference between the positive electrode and the negative electrode is held at 1.48 V or more), causing a water electrolysis reaction, and O2 gas generated in the first tank and H2 gas generated in the second tank can be extracted. In addition, the power source and electronic load are used to hold the voltage of the positive electrode so that the potential of the positive electrode is higher than the potential of the negative electrode (for example, the voltage of the positive electrode is held at 0.60 V or more and 1.00 V or less), so that Co and Ni contained in the positive electrode can be recovered as metal Co and metal Ni. As a result, in the metal recovery method and metal recovery device according to the present disclosure, Co and Ni contained in the positive electrode can be recovered as metal Co and metal Ni while causing a water electrolysis reaction to extract O2 gas and H2 gas. Therefore, in terms of the electrical energy held by the power source and the electronic load, the electrical energy required to extract O2 gas and H2 gas through the water electrolysis reaction can also be utilized to recover metals contained in the positive electrode, thereby reducing energy consumption.

[0028] (Preferred embodiment) ·Electrolyte From the viewpoint of increasing the recovery efficiency of metallic Co and metallic Ni, the electrolytic solution in which the first tank and the second tank are immersed preferably has a pH of 14 or more, more preferably a pH of 15 or more, and even more preferably a pH of 16 or more. The pH is a value measured at 25° C. using a pH meter.

[0029] The electrolyte is not particularly limited, but is preferably an aqueous electrolyte. For example, an alkaline aqueous solution can be suitably used as the aqueous electrolyte. The alkaline aqueous solution contains, for example, water and an alkali metal hydroxide dissolved in the water. The alkali metal hydroxide may have a concentration of, for example, 1 mol / L to 45 mol / L. For example, the alkali metal hydroxide includes potassium hydroxide (KOH), sodium hydroxide (NaOH), lithium hydroxide (LiOH), etc.

[0030] ·Voltage From the viewpoint of efficiently causing the water electrolysis reaction, it is preferable to maintain the voltage so that the potential difference between the positive electrode and the negative electrode is 1.48 V or more. On the other hand, from the viewpoint of efficiently dissolving Co from the positive electrode, it is preferable to maintain the voltage at the positive electrode in the range of 0.60 V to 1.00 V. Therefore, it is possible to repeatedly maintain the potential difference between the positive electrode and the negative electrode in the range of 1.48 V or more (e.g., for 50 minutes), and then adjust the voltage to maintain the voltage at the positive electrode in the range of 0.60 V to 1.00 V (e.g., for 10 minutes).

[0031] Water supply In terms of easiness of extracting the generated O2 gas and H2 gas, it is preferable to supply water (H2O) to the first tank and the second tank from below (from the direction of gravity to the direction against gravity) in both cases. For example, it is preferable to supply water from the bottom surface of the tank to the top surface by capillary action.

[0032] ·distance From the viewpoint of ease of occurrence of the water electrolysis reaction, the distance between the first tank and the second tank is preferably 0 cm or more and 5 cm or less, and more preferably 0 cm or more and 1 cm or less. Note that the distance between the first tank and the second tank refers to the shortest distance between the first tank and the second tank.

[0033] 1 and 2, from the viewpoint of transportability of O2 gas generated in the first tank 100B to the distillation apparatus 5, it is preferable that the temperature and pressure inside the distillation apparatus 5 are lower than those inside the housing 40. From the same viewpoint, it is preferable that the arrangement position of the distillation apparatus 5 is lower in the direction of gravity than the arrangement position of the housing 40.

[0034] (Nickel metal hydride battery) Here, a nickel-metal hydride storage battery that can be used for the first and second tanks will be described. The nickel-metal hydride storage battery (hereinafter sometimes abbreviated as "battery") may be a used nickel-metal hydride storage battery that has been used, for example, as a battery for portable devices, an in-vehicle battery, or a storage battery for renewable energy power generation.

[0035] FIG. 3 is a schematic diagram showing an example of the configuration of a nickel-metal hydride storage battery. The battery 1 is a nickel-metal hydride storage battery. The battery 1 includes a housing 2. The housing 2 is a cylindrical case. The housing 2 is made of metal. However, the housing 2 may have any shape. The housing 2 may be, for example, a rectangular case. The housing 2 may be, for example, a pouch made of an aluminum laminate film. The housing 2 may be, for example, made of resin.

[0036] The housing 2 houses an electricity storage element 10 and an electrolyte. The electricity storage element 10 includes a positive electrode 11, a negative electrode 12, and a separator 13. The illustrated electricity storage element 10 is a wound type. The electricity storage element 10 is formed by winding a strip-shaped electrode in a spiral shape. The electricity storage element 10 may be, for example, a laminated type. The electricity storage element 10 may be formed, for example, by laminating sheet-shaped electrodes.

[0037] 《Negative electrode》 The negative electrode 12 is in the form of a sheet. The negative electrode 12 may have a thickness of, for example, 10 μm to 1 mm. The negative electrode 12 has a lower potential than the positive electrode 11.

[0038] The negative electrode includes, for example, a negative electrode current collector and a negative electrode active material. The negative electrode current collector can be, for example, a nickel mesh. The negative electrode active material can be, for example, a hydrogen storage alloy. The composition of the hydrogen storage alloy is not limited as long as it can store and release hydrogen. The hydrogen storage alloy can be, for example, an Mm-Ni-Mn-Al-Co alloy. "Mm" indicates a mixture of rare earth elements called misch metal.

[0039] 《Positive electrode》 The positive electrode 11 is in the form of a sheet. The positive electrode 11 may have a thickness of, for example, 10 μm to 1 mm. The positive electrode 11 has a higher potential than the negative electrode 12. The positive electrode 11 includes a positive electrode active material. The positive electrode active material may include any component. Examples of the positive electrode active material include nickel hydroxide (Ni(OH)2), cobalt hydroxide (Co(OH)2), manganese dioxide, and silver oxide. The positive electrode active material is preferably nickel hydroxide.

[0040] The positive electrode 11 may be substantially composed of only a positive electrode active material. The positive electrode 11 may further include a current collector, a conductive material, a binder, and the like, in addition to the positive electrode active material. The current collector may include, for example, a porous metal sheet, and the like. The current collector is made of, for example, Ni.

[0041] For example, the positive electrode 11 can be formed by applying a positive electrode active material, a conductive material, and a binder to a current collector. The conductive material has electronic conductivity. The conductive material can include any component. The conductive material can include, for example, carbon black, Co, cobalt oxide, etc. The amount of the conductive material can be, for example, 0.1 parts by mass to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material. The binder bonds the current collector and the positive electrode active material. The binder can include any component. The binder can include, for example, ethylene vinyl acetate (EVA), etc. The amount of the binder can be, for example, 0.1 parts by mass to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material.

[0042] <Separator> The separator 13 is in the form of a sheet. The separator 13 is disposed between the positive electrode 11 and the negative electrode 12. The separator 13 physically separates the positive electrode 11 and the negative electrode 12. The separator 13 may have a thickness of, for example, 50 μm to 500 μm. The separator 13 is porous. The separator 13 may include, for example, a stretched porous film, a nonwoven fabric, or the like. The separator 13 is electrically insulating. The separator may be made of, for example, polyolefin, polyamide, or the like.

[0043] 《Electrolyte》 The electrolyte is not particularly limited, but is preferably an aqueous electrolyte. For example, an alkaline aqueous solution can be suitably used as the aqueous electrolyte. The alkaline aqueous solution contains, for example, water and an alkali metal hydroxide dissolved in the water. The alkali metal hydroxide may have a concentration of, for example, 1 mol / L to 20 mol / L. For example, the alkali metal hydroxide includes potassium hydroxide (KOH), sodium hydroxide (NaOH), lithium hydroxide (LiOH), etc.

[0044] Here, whether or not metallic Co was recovered in the metal recovery device according to the embodiment of the present disclosure was confirmed by an experiment.

[0045] (Experimental Example 1) A recovery apparatus was prepared, which has the same configuration as the recovery apparatus 20A shown in FIG. 1, using the following as the electrolyte, the first tank, the second tank, and the positive electrode of the first tank, and connecting the positive electrode in the first tank and the negative electrode in the second tank to a power source and an electronic load. Electrolyte: Potassium hydroxide (KOHaq, pH 15) First tank and second tank: nickel-metal hydride storage battery Positive electrode of the first cell: an electrode containing Co(OH2) and Ni(OH2) as positive electrode active materials

[0046] In this recovery device, water (H2O) was supplied from a water supply pump to the first tank and the second tank, and the potential of the positive electrode in the first tank was maintained higher than the potential of the negative electrode in the second tank by the power supply and electronic load. Specifically, as shown in the graph in Figure 4, the potential difference between the positive and negative electrodes was maintained at 1.53 V / cell for 50 minutes, and then the voltage was adjusted to maintain the positive electrode voltage at 0.60 V / cell for 10 minutes. This voltage maintenance was repeated for 15 hours. After the voltage started to be maintained, it was confirmed that oxygen (O2) gas was discharged from the first tank through the exhaust passage to the distillation apparatus, and that hydrogen (H2) gas was discharged from the exhaust passage of the second tank.

[0047] -Dissolution of Co into the electrolyte After the voltage was maintained for the above-mentioned time, it was confirmed whether or not Co had dissolved in the electrolyte circulating in the distillation apparatus and the housing by the liquid pump. As a result, it was confirmed that 3.1 mass % (1.2 atomic %) of Co had dissolved in the electrolyte. Thus, it was confirmed that Co had dissolved in the electrolyte in Experimental Example 1, that is, it was confirmed that metallic Co could be recovered.

[0048] In addition, in Experimental Example 1, when the elements remaining in the positive electrode of the first tank after the voltage was continuously applied for the above-mentioned time were analyzed, Ni and Fe were detected, which confirmed that metallic Ni could be separated and recovered. [Explanation of symbols]

[0049] 1 battery 10. Energy storage element 11 Positive electrode 12 Negative electrode 13 Separator 2. Chassis 3 Power supply 4. Chassis 40 Electrolyte 5. Distillation Apparatus 6. Water supply pump 7 Liquid delivery pump 8 Outlet 20A Recovery Device 30 electronic load 100A, 100B First tank 200A, 200B Second tank 101, 201 Discharge passage

Claims

1. Power supply, An electronic load; An electrolyte; a positive electrode connected to the power source and the electronic load and including at least Co; and ２ a first tank having an O supply port and an O discharge port and immersed in the electrolyte; A negative electrode connected to the power source and the electronic load, and H ２ a second tank having an O supply port and an O exhaust port and immersed in the electrolyte; For a recovery device having A metal recovery method comprising: maintaining a voltage by the power source and the electronic load so that a potential of the positive electrode is higher than a potential of the negative electrode, and recovering Co dissolved from the positive electrode.

2. The positive electrode contains Ni, 2. The metal recovery method according to claim 1, further comprising the steps of: maintaining a voltage such that a potential of the positive electrode is higher than a potential of the negative electrode by the power source and the electronic load; and then recovering Ni remaining in the positive electrode.

3. 2. The method of claim 1, wherein at least one of the first tank and the second tank is a nickel-metal hydride battery.

4. The method for recovering metals according to claim 3 , wherein the nickel-metal hydride storage battery is a used storage battery.

5. By maintaining the voltage, a water electrolysis reaction is caused to occur, and O ２ Remove gas and H from the second vessel. ２ 2. The method for recovering metals according to claim 1, further comprising removing a gas.

6. Power supply, An electronic load; An electrolyte; a positive electrode connected to the power source and the electronic load and including at least Co; and ２ a first tank having an O supply port and an O discharge port and immersed in the electrolyte; A negative electrode connected to the power source and the electronic load, and H ２ a second tank having an O supply port and an O exhaust port and immersed in the electrolyte; having The metal recovery device is capable of recovering Co dissolved from the positive electrode by maintaining a voltage such that the potential of the positive electrode is higher than the potential of the negative electrode using the power supply and the electronic load.

7. The positive electrode contains Ni, 7. The metal recovery device according to claim 6, wherein the power source and the electronic load are used to maintain a voltage such that the potential of the positive electrode is higher than the potential of the negative electrode, and then Ni remaining in the positive electrode is recovered.

8. 7. The metal recovery apparatus of claim 6, wherein at least one of the first tank and the second tank is a nickel-metal hydride battery.

9. The metal recovery device according to claim 8 , wherein the nickel-metal hydride storage battery is a used storage battery.

10. By maintaining the voltage, a water electrolysis reaction is caused to occur, and O ２ Remove gas and H from the second vessel. ２ 7. The metal recovery apparatus according to claim 6, further comprising a gas extraction device.

Images