WO2013065511A1

WO2013065511A1 - Molten salt electrolysis metal fabrication method and apparatus for use in same

Info

Publication number: WO2013065511A1
Application number: PCT/JP2012/077223
Authority: WO
Inventors: 知之粟津; 真嶋　正利
Original assignee: 住友電気工業株式会社
Priority date: 2011-11-04
Filing date: 2012-10-22
Publication date: 2013-05-10
Also published as: CN103906861A; US20140291161A1

Abstract

Provided is a method for obtaining safely and at low cost a specific metal of high purity from a material to be processed that contains two or more metal elements. The molten salt electrolysis metal fabrication method of the present invention is characterized by having a step in which two or more metal elements contained within a material to be processed are dissolved in molten salt, and a step in which, by disposing a pair of electrode members in the molten salt in which the metal elements have been dissolved and controlling the electrical potential of the electrode members to a given value, a specific metal element present in the molten salt is precipitated onto, or made to form an alloy on, one of the electrode members.

Description

Method for producing metal by molten salt electrolysis and apparatus used for the method

The present invention relates to a method for producing metal by molten salt electrolysis and an apparatus used for the method.

As a method for smelting a specific metal from slag ore, a method by dry smelting and a method by wet smelting are known.

Dry smelting smelting is a method of separating a target metal by melting ore in a high-temperature furnace. For example, a concentrate, a roasted ore, or a sintered ore is melted in a high-temperature furnace, concentrated into a crude metal lump, and gangue and impurities are separated as slag (page 46 of Non-Patent Document 1).
In smelting and refining, the metal contained in the ore is separated based on the difference in specific gravity when it is melted. In addition, it is required that the objects to be separated have a low solubility. Since elements satisfying these conditions are limited among metal materials, there is a problem that the target elements that can be separated by dry smelting are limited.

In addition, the hydrometallurgical smelting is a method in which ore is dissolved in a solution of alkali or acid, and the target metal is separated and extracted from this solution. Examples of methods for separating and extracting the target metal from this aqueous solution include a method using ion exchange, a method using solvent extraction, and a method using aqueous solution electrolysis.

The ion exchange method is a method of reversibly ion-exchange using a solid having in part a group of ions capable of ion exchange called an ion exchange agent (page 194 of Non-Patent Document 1).
Ion exchange is an excellent treatment due to the adsorption capacity and exchange capacity of ion exchange resin, but it is processed by repeated adsorption and dissociation of ions, so it is not suitable for treating large quantities of substances economically and efficiently. There is.

The solvent extraction method is a separation method that utilizes the difference in distribution depending on the type of solute in two solvents that do not dissolve in each other (page 199 of Non-Patent Document 1).
This solvent extraction is ionized by acid treatment or the like, and it is necessary to carry out a large number of treatment steps for separation, and accordingly, a large amount of acid and alkali are required and a large amount of waste liquid is generated.

The method of electrolytic smelting by aqueous solution electrolysis is a method for producing pure metal by utilizing the difference in difficulty in anodic dissolution or cathode deposition depending on elements. Moreover, the formation reaction of the hardly soluble salt with respect to the impurity ion in the electrolyte solution to be used is also utilized (page 219 of Non-Patent Document 1).
However, metal elements that can be separated and precipitated by aqueous electrolytic purification are limited, and there is a problem that, for example, a material such as rare earth cannot be deposited in principle.

As for Al, electrolytic smelting using molten salt electrolysis is also known. In this method, Al, which is a material to be refined, is alloyed to lower the melting point, and smelting is performed using the specific gravity difference as a three-layer system of molten salt and recovered metal. In order to use the specific gravity difference in this way, it is necessary to carry out the process in a state where all three layers are melted (page 254 of Non-Patent Document 1).
This method has a problem that when the target metal is Al and the potential of the coexisting impurities is close to the potential of the purification target metal, it is mixed as an impurity in the deposited target metal.

On the other hand, as a method for recovering tungsten, for example, Non-Patent Document 2 describes the following method.
First, a hard scrap or a soft scrap of a cemented carbide tool is reacted with a molten salt of sodium nitrate and then dissolved in water to prepare a sodium tungstate aqueous solution. Then, an ammonium tungstate aqueous solution is produced from the sodium tungstate aqueous solution by an ion exchange method using an ion exchange resin, and ammonium paratungstate (APT) is crystallized from the ammonium tungstate aqueous solution. Thereafter, tungsten carbide is obtained by calcining, reducing and carbonizing the ammonium paratungstate crystallized as described above.
Hard scrap is a generic term for scraps that maintain the shape of a product, and soft scrap refers to powdered scrap that consists of powder scraps, cutting scraps, and the like generated when processing and manufacturing a carbide tool.

In Patent Document 1, when sodium tungstate is produced by oxidizing hard alloy scrap and / or heavy metal scrap in a molten salt bath, sodium hydroxide 60 to 90 wt% and sodium sulfate 10 to 40 wt% % Molten salt has been proposed. It has also been proposed that the reaction between the scrap and the molten salt be carried out in a rotary kiln that is operated batchwise and can be heated directly.

However, in the method described in Non-Patent Document 2, the reaction between the hard scrap or soft scrap of the carbide tool and the molten salt of sodium nitrate occurs extremely vigorously, so that the reaction is difficult to control and there is a problem in the safety of operation. is there. Also, when hard scrap or soft scrap of cemented carbide tool and molten salt of sodium nitrate are reacted, metals such as vanadium and chromium contained in the hard scrap and soft scrap of cemented carbide tool are water-soluble metals. It will be contained in the sodium tungstate aqueous solution in the form of oxide ions. For this reason, these metals become impurities and there is a problem that high purity is difficult.

In addition, in the method described in Patent Document 1, the melting point of sodium sulfate as a molten salt serving as an oxidizing agent is as high as 884 ° C., and the temperature during the reaction must be as high as 884 ° C. or higher. For this reason, there is a problem that the metal material is corroded. Moreover, since reaction becomes slow, there exists a problem that reaction takes time and energy loss is large.

On the other hand, lithium is extracted mainly from lithium-containing ores (spodumene, ambrigonite, petalite, lepidrite, etc.), salt lakes and underground brines with high lithium concentration. However, since Japan has neither lithium-containing ore nor salt lakes, the actual situation is that almost all of them depend on imports.
Therefore, recently, studies have been started to separate and recover lithium from lithium-containing waste generated in the manufacturing process of lithium-containing products such as lithium batteries or lithium-containing products that are used and discarded.

As a method for recovering lithium, lithium cobaltate, which is a positive electrode material of a lithium secondary battery, is subjected to a reduction reaction in a lithium chloride molten salt together with metal lithium to produce lithium oxide, and cobalt or cobalt oxide is precipitated and separated. In addition, a method has been proposed in which lithium oxide is electrolyzed in a lithium chloride molten salt to deposit and recover metallic lithium on the cathode (Japanese Patent Application Laid-Open No. 2005-011698).
However, this method needs to add metallic lithium in order to reduce and separate cobalt contained in the object to be treated, and employs a process of adding metallic lithium to recover metallic lithium. There is a problem that it is not efficient.

In addition, a mixture of carbon and lithium manganate, which is a positive electrode material of a lithium secondary battery, is roasted in any of an air atmosphere, an oxidizing atmosphere, an inert atmosphere, and a reducing atmosphere to obtain lithium. A method for recovering lithium by eluting lithium as lithium hydroxide and lithium carbonate by leaching this roasted product with water by using lithium oxide has been proposed (Patent Document 3).
However, in this method, since the solubility of lithium hydroxide and lithium carbonate is not large, the recovery efficiency is poor, and a large amount of water is required to elute lithium hydroxide and lithium carbonate into water. There is a problem that a large amount of wastewater is generated.

Furthermore, tantalum (Ta) is mainly used for tantalum capacitors and can be recovered from tantalum capacitor scrap. Specifically, it is recovered through processes of oxidation treatment, magnetic separation, sieving, running water separation, pulverization, sieving, leaching, oxidation treatment, reduction treatment, and leaching (Non-patent Documents 3, pages 319 to 326). reference).

Vanadium (V) is used as an additive to steel and as a desulfurization catalyst in petroleum refining. What was used as a steel additive is collected as steel scrap and recycled as steel. Vanadium pentoxide can be obtained by sequentially carrying out the steps of classification, roasting, pulverization, leaching, filtration, leachate, dehydration, thermal decomposition, and dissolution for the spent catalyst (the same document, pages 391 to 396). page).

Molybdenum (Mo) is also used as an additive and alloy for steel and as a desulfurization catalyst in petroleum refining. Those used as steel additives and alloy elements can be recovered as steel and alloys and used as they are in the form of steel and alloys. Mo can be obtained by sequentially performing the steps of roasting, removal of oil / water / sulfur, basic leaching, and recovery for the used catalyst (the same reference, pages 301 to 303). .

Most of the niobium (Nb) is used as an additive to steel, and those used as such steel additives are recovered as steel scrap. However, the content of niobium such as high-strength steel and stainless steel is extremely low and is not recycled as niobium (Id., Page 339).

Manganese (Mn) is mostly used for steel and aluminum alloys, and is recovered as steel scrap and aluminum alloy scrap, respectively. In the case of recycling for steel, manganese has a large proportion of remaining in various slags, and manganese forming slag is not suitable for recycling. Manganese in slag is partly used as manganese calcium fertilizer.
In addition, aluminum cans used as aluminum alloys are recycled after being collected (page 343 to 344).

Chromium (Cr) used for steel (stainless steel) and superalloy is recycled as steel scrap and superalloy scrap, respectively, and is recycled and recycled. Pp. 219-221).

The recovery techniques as described above have a problem that the number of processes in the recovery process such as roasting (heating), pulverization, leaching, reduction, etc. is large and complicated, so that the processing takes time and costs increase.
In addition, roasting is necessary to perform the processing, and processing that is not subject to extraction accompanying the processing is performed, and unnecessary energy is used. Furthermore, by subjecting a non-treatment target to a roasting process, unnecessary oxides are generated, and a lot of waste is generated. Moreover, since acid treatment and base treatment are performed, waste liquids of acid and base are generated after the treatment, and an environmental load is generated.
As described above, the conventional metal recovery technique has problems such as high processing cost, large energy loss, large amount of waste, and large environmental load. In addition, some metals are not regenerated as a single unit due to cost and technical problems.

Japanese National Patent Publication No. 11-505801 JP 2005-011698 A JP 2011-094227 A

In view of the above problems, the present invention provides a metal production method for obtaining a low-cost, high-purity metal that can be used for any ore and an apparatus used for the production method. And The present invention provides a method for producing a metal that can obtain a specific metal with high purity, safety and low cost from a treatment object containing two or more kinds of metal elements, and an apparatus used for the method. Is an issue.

In one embodiment of the present invention, a step of dissolving a metal element contained in a processing object containing two or more kinds of metal elements in a molten salt, and a pair of electrode members provided in the molten salt in which the metal element is dissolved And a step of precipitating or alloying a specific metal present in the molten salt on one of the electrode members by controlling the potential of the electrode member to a predetermined value. This is a method for producing a metal.
In another embodiment of the present invention, the treatment target is ore or a crude metal block obtained from the ore.
Another embodiment of the present invention is a method for producing tungsten, wherein the metal element contained in the object to be treated is tungsten, and in the step of dissolving the metal element from the object to be treated in a molten salt, In the step of dissolving tungsten from the object to be treated and precipitating or alloying the specific metal, a pair of electrode members are provided in the molten salt in which the tungsten is dissolved, and the potential at the electrode members is controlled to a predetermined value. Thus, tungsten existing in the molten salt is deposited on one of the electrode members.
In another embodiment of the present invention, the processing object is a metal material containing tungsten.
In another embodiment of the present invention, the object to be processed is a metal material containing tungsten and a transition metal.
In another embodiment of the present invention, the processing object is a cemented carbide product.
Another embodiment of the present invention is a method for producing lithium, wherein the metal element contained in the object to be treated is lithium, and in the step of dissolving the metal element from the object to be treated in a molten salt, In the step of dissolving lithium from the object to be treated and precipitating or alloying the specific metal, a pair of electrode members are provided in the molten salt in which the lithium is dissolved, and the potential at the electrode members is controlled to a predetermined value. As a result, lithium existing in the molten salt is deposited on one of the electrode members.
In another embodiment of the present invention, the object to be treated is a material containing lithium and a transition metal.
In another embodiment of the present invention, the processing object is a battery electrode material containing lithium.
In another embodiment of the present invention, the processing object includes a transition metal or a rare earth metal.
In another embodiment of the present invention, the processing object contains one or more metals selected from the group consisting of V, Nb, Mo, Ti, Ta, Zr, and Hf.
In another embodiment of the present invention, the processing object includes Sr and / or Ba.
In another embodiment of the present invention, the processing object includes one or more kinds of metals selected from the group consisting of Zn, Cd, Ga, In, Ge, Sn, Pb, Sb, and Bi.
In another embodiment of the present invention, in the step of precipitating or alloying the specific metal, the standard electrode potential of the single metal or its alloy in the molten salt and the standard of another single metal or its alloy are used. The molten salt is selected so that the difference from the electrode potential is 0.05 V or more.
In another embodiment of the present invention, in the step of depositing or alloying the specific metal, the potential of the electrode member is controlled to a predetermined value, and the specific metal element in the molten salt is selectively precipitated. Or alloy it.
In another embodiment of the present invention, in the step of dissolving the metal element contained in the object to be treated in the molten salt, the metal is dissolved in the molten salt by a chemical method.
In another embodiment of the present invention, in the step of dissolving the metal element contained in the object to be treated in the molten salt, the molten salt includes a cathode and an anode made of an anode material containing the object to be treated. By providing and controlling the potential at the anode to a predetermined value, the metal element corresponding to the controlled potential from the object to be treated is dissolved in the molten salt.
In another embodiment of the present invention, in the step of dissolving a metal element contained in the object to be treated in a molten salt, a standard electrode potential of the specific metal alone or an alloy thereof in the molten salt and another metal The molten salt is selected so that the difference from the standard electrode potential of the simple substance or alloy thereof is 0.05 V or more.
In another embodiment of the present invention, in the step of dissolving the metal element contained in the object to be treated in the molten salt, the potential at the anode is controlled to a predetermined value, and the specific metal element is selectively melted. Dissolve in salt.
In another embodiment of the present invention, one or more specific metals are dissolved in the molten salt in the step of dissolving the metal element contained in the object to be processed in the molten salt.
In another embodiment of the present invention, the specific metal to be deposited or alloyed is a transition metal.
In another embodiment of the present invention, the specific metal to be deposited or alloyed is a rare earth metal.
In another embodiment of the present invention, the specific metal to be precipitated or alloyed is V, Nb, Mo, Ti, Ta, Zr, or Hf.
In another embodiment of the present invention, the specific metal to be deposited or alloyed is Sr or Ba.
In another embodiment of the present invention, the specific metal to be deposited or alloyed is Zn, Cd, Ga, In, Ge, Sn, Pb, Sb, or Bi.
In another embodiment of the present invention, a chloride-based or fluoride-based molten salt is used as the molten salt.
In another embodiment of the present invention, a molten salt obtained by mixing a chloride-based molten salt and a fluoride-based molten salt is used as the molten salt.
In another embodiment of the present invention, the object to be processed is granular or powdery.
In another embodiment of the present invention, the granular or powder object to be processed is pressed into the anode.
Another embodiment of the present invention is a method for producing a specific metal from a treatment object containing two or more kinds of metal elements by molten salt electrolysis, and comprises a cathode in the molten salt and an anode containing the treatment object An anode made of a material is provided, and by controlling the potential at the anode to a predetermined value, a metal element corresponding to the potential controlled from the object to be processed is dissolved in the molten salt, thereby allowing a specific metal to be used as the anode. It is a method for producing a metal by molten salt electrolysis, which is characterized by remaining.
In another embodiment of the present invention, the treatment target is ore or a crude metal block obtained from the ore.
Another embodiment of the present invention is a method for producing tungsten from a treatment object containing tungsten by molten salt electrolysis, wherein a cathode and an anode made of an anode material containing the treatment object are provided in the molten salt. By controlling the potential at the anode to a predetermined value, the metal element corresponding to the controlled potential from the object to be processed is dissolved in the molten salt, so that tungsten remains in the anode.
According to another embodiment of the present invention, in the step of dissolving a metal element from the object to be treated in the molten salt, the standard electrode potential of the specific metal alone or its alloy in the molten salt and other metal The molten salt is selected so that the difference from the standard electrode potential of a single substance or an alloy thereof is 0.05 V or more.
In another embodiment of the present invention, a container holding a molten salt therein, a cathode immersed in a molten salt held in the container, and a molten salt held in the container are immersed in 2 An anode holding a treatment object containing at least one kind of metal element inside, the anode is capable of flowing the molten salt between the inside and the outside, and further, the potential at the cathode and the anode Is a device for use in a method for producing a metal by molten salt electrolysis, wherein the control unit is capable of changing the value of the potential.
Another embodiment of the present invention includes a container holding therein a molten salt in which two or more kinds of metal elements are dissolved, a cathode and an anode immersed in the molten salt held inside the container, and the cathode And a control unit that controls the potential at the anode to a predetermined value, and the control unit is used in a method for producing a metal by molten salt electrolysis, wherein the potential value can be changed. Device.
In another embodiment of the present invention, the two or more metal elements include at least one of tungsten and lithium.

金属 The metal production method of the present invention and the apparatus used for the production method can be used for any ore. With the production method of the present invention and the apparatus used for the production method, a specific metal can be obtained with high purity, safety and low cost from a treatment object containing two or more kinds of metal elements.

It is a flowchart explaining embodiment of this invention. It is a schematic diagram which shows the example of the precipitation potential of the rare earth metal in molten salt. It is a graph which shows the example of the relationship between the processing time at the time of implementing this invention, and the ion concentration of the rare earth metal in molten salt. It is a cross-sectional schematic diagram for demonstrating the structure of the apparatus which implements this invention. It is a cross-sectional schematic diagram for demonstrating the structure of the apparatus which implements this invention. It is a flowchart for demonstrating other embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating other embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating other embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating other embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating other embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating the modification of other embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating the modification of other embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating the modification of other embodiment of this invention. It is a photograph for demonstrating the anode electrode used in the Example which concerns on this invention. It is a graph which shows the relationship between the anode electric current value and time in the Example which concerns on this invention. It is a scanning electron micrograph which shows the surface part of the cathode electrode used at the electrolysis process of the Example which concerns on this invention. The scale on the lower right of the photograph shows 8 μm. It is a scanning electron micrograph which shows the distribution condition of Dy about the area | region of the electron micrograph shown in FIG. It is a cross-sectional schematic diagram for demonstrating an example of a structure of the apparatus of embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating an example of a structure of the apparatus of embodiment of this invention.

In one embodiment of the present invention, a step of dissolving a metal element contained in a processing object containing two or more kinds of metal elements in a molten salt, and a pair of electrode members provided in the molten salt in which the metal element is dissolved And a step of precipitating or alloying a specific metal present in the molten salt on one of the electrode members by controlling the potential of the electrode member to a predetermined value. Is a method for producing a metal.
[First embodiment]
In the first embodiment, the processing object is an ore containing two or more kinds of metal elements or a rough metal lump obtained from the ore (hereinafter also simply referred to as a rough metal lump).

That is, the above-described embodiment is roughly divided into a process of dissolving a metal contained in an object (the ore or the coarse metal lump) in molten salt, and one electrode (cathode) by molten salt electrolysis from the molten salt in which the metal is dissolved. And the process of precipitating the metal or alloy of the target element to be separated and extracted. The feature of the present embodiment is that the potential at the electrode is controlled to selectively dissolve or precipitate a specific element to be separated and refined.

First, a process for dissolving a metal element contained in an object in a molten salt will be described.
Examples of the method for dissolving the metal element contained in the ore or the coarse metal block in the molten salt include a method of dissolving by a chemical method. Specifically, the ore or the rough metal lump is pulverized into a granular or powder form, and these and a salt are mixed and heated to melt two or more metal elements contained in the ore or the rough metal lump. Can be dissolved in. Further, the object to be treated may be put into molten salt and dissolved.

別 Another method is an electrochemical method. Specifically, the object is attached as an anode in the molten salt, and the elements contained in the object are selectively dissolved according to the magnitude of the potential controlled on the object. This is because the potential at which an element dissolves in molten salt electrolysis has different properties depending on the type of the element, and this property is used to selectively separate metals according to the potential. Thus, the metal element to be refined can be selectively dissolved in the molten salt by controlling the potential at the time of dissolution using the object as the anode.

In the process of dissolving the metal element contained in the object in the molten salt, it is preferable to control the potential so that the impurities contained in the object remain without being dissolved. Thereby, it is possible to reduce the introduction of impurities in the subsequent deposition process.
For this purpose, in the step of dissolving the metal element contained in the ore or the coarse metal block in the molten salt, the standard potential of the specific metal (the metal element to be dissolved) in the molten salt or its alloy and the like. It is preferable to select the molten salt so that the difference from the standard electrode potential of the single metal or alloy thereof is 0.05 V or more. Thereby, the metal element dissolved in the molten salt and the metal element remaining on the anode can be satisfactorily separated. The difference in the standard electrode potential is more preferably 0.1 V or more, and further preferably 0.25 V or more.
The value of the potential controlled at the anode can be calculated by the Nernst equation described later.

In addition, when the ore or coarse metal lump to be used contains a plurality of specific target metals, the potential may be controlled so that each of them is dissolved in the molten salt. Further, when one kind of specific metal is dissolved, the remaining ore or coarse metal block (anode) containing the remaining metal is transferred to another molten salt, and the potential is similarly controlled to a predetermined value, thereby remaining A specific metal may be dissolved in the molten salt.
Depending on the metal species, separation by precipitation, which will be described later, may be easier. In such a case, all of the object to be treated may be dissolved, or a specific metal species and some of the remaining metal species. Only may be dissolved.
In addition, from the viewpoint of reducing the introduction of impurities, in the step of dissolving the metal element contained in the ore or the coarse metal lump in the molten salt, the potential at the anode is controlled to a predetermined value, and the specific metal element is It is preferable to selectively dissolve in the molten salt.

As the molten salt, a chloride-based or fluoride-based salt can be used. The molten salt of the chloride-based, for example _{KCl, NaCl, CaCl 2, LiCl} , RbCl, CsCl, be used, for example _{_{_{SrCl 2, BaCl 2, MgCl 2}}} . As the molten salt fluoride, e.g. LiF, may NaF, KF, RbF, CsF, be used _{_{_{MgF 2, CaF 2, SrF 2}}} , BaF 2. In the case of the molten salt electrolysis of rare earth elements, it is preferable to use a chloride-based molten salt from the viewpoint of efficiency. Among them, KCl, NaCl, and CaCl ₂ are preferably used because they are inexpensive and easily available. preferable.
Moreover, the use of these molten salts can be used as a molten salt of any composition by combining a plurality of types of molten salt, for example KCl-CaCl ₂ and LiCl-KCl or molten salt composition, such as NaCl-KCl, it can.

材料 As the cathode, a material that is easily alloyed with an alkali metal such as Li or Na constituting carbon or a cation in the molten salt is used. For example, use aluminum (Al), zinc (Zn), gallium (Ga), cadmium (Cd), indium (In), tin (Sn), antimony (Sb), lead (Pb), bismuth (Bi), etc. Can do.

In order to use the ore or the coarse metal lump as the anode, for example, the ore or the coarse metal lump may be accommodated in a conductive basket made of metal or the like and provided in the molten salt. An opening is provided in the upper part of the basket so that the ore or the rough metal lump, which is the object to be processed, can be inserted through the opening, and a large number of holes are formed in the side wall and the bottom wall of the basket to form a molten salt. Can be allowed to flow into the basket. As a material constituting the cage, any material such as a net-like member formed by knitting a metal wire or a sheet member in which a large number of holes are formed in a sheet-like metal plate can be used. In particular, it is effective to use C, Pt, Mo or the like as the material.
When the object is an ore or the like and has a high electric resistance, the contact amount with the conductive material is preferably increased. It is effective to use the electrode as an electrode by wrapping it with a metal mesh member or filling the space inside the porous metal body.

By providing the cathode and the cage holding the ore or the coarse metal lump in the molten salt, and controlling the potential at the anode (cage) from the outside as described above, The resulting metal can be dissolved in the molten salt.

In the next deposition process, a pair of electrode members are provided in the molten salt, and a metal element dissolved in the molten salt is deposited on one electrode member (cathode) by molten salt electrolysis. In this case, a specific metal element can be selectively deposited on the cathode as a metal or alloy depending on the magnitude of the potential controlled by molten salt electrolysis.
In this deposition process, as in the melting process, the potential at which an element is deposited on the cathode as a metal or alloy in molten salt electrolysis has different properties depending on the type of the element. Thus, even when a plurality of specific metals of interest are contained in the molten salt, the potential can be controlled to deposit one by one on the cathode alone.

ニッケル As the electrode member, for example, nickel (Ni), molybdenum (Mo), glassy carbon (C) or the like can be used.

The present embodiment separates and extracts a specific metal element to be smelted from an object by the above two processes. In this embodiment, since the molten salt is used, it is necessary to heat the system so that the temperature of the system in each process is equal to or higher than the melting point of the molten salt.

The characteristics of the above two processes are the use of molten salt, which makes use of the fact that the potential of dissolution / precipitation of each element differs depending on the type of molten salt, and the specific metal element of interest and the others It is possible to select and design the molten salt so that the dissolution / precipitation potential of the metal element as the impurity target becomes a value that is easy to process. Specifically, in the step of precipitating or alloying the specific metal, the standard electrode potential of the specific metal or its alloy in the molten salt and the standard electrode potential of another metal or its alloy It is preferable to select the molten salt so that the difference is 0.05 V or more. The difference between the standard electrode potential of the specific metal or its alloy in the molten salt and the standard electrode potential of another metal or its alloy is more preferably 0.1 V or more, and 0.25 V or more. More preferably.
Thus, in the step of precipitating or alloying the specific metal, the potential of the electrode member is controlled to a predetermined value, and the specific metal element in the molten salt is selectively precipitated or alloyed. It is preferable.

The deposition potential of a single metal or alloy deposited on the cathode can be calculated by electrochemical calculation. Specifically, it is calculated using the Nernst equation.
For example, the potential for precipitating Pr alone from trivalent praseodymium (Pr) ions (hereinafter referred to as Pr (III)) can be obtained by the following equation.

E _Pr = E ⁰ _Pr + RT / 3F · ln (a _{Pr (III)} / a _{Pr (0)} ) (1) In the above formula (1), E ⁰ _Pr is a standard potential, R Is the gas constant, T is the absolute temperature, F is the Faraday number, a _{Pr (III)} is the activity of Pr (III) ions, and a _{Pr (0)} is the activity of Pr alone.

When the above equation (1) is rewritten in consideration of the activity coefficient γ _{Pr (III)} , since a _{Pr (0)} = 1, the following equation is obtained.
E _Pr = E ⁰ _Pr + RT / 3F · lna _{Pr (III)}
= E ⁰ _Pr + RT / 3F · ln (γ _{Pr (III)} · C _{Pr (III)} ) (2) E _Pr = E ^{0 ′} _Pr + RT / 3F · lnC _{Pr (III)} Formula (3) In the above formula (3), C _{Pr (III)} is the concentration of trivalent Pr ions, E ^{0 ′} _Pr is the formula electrode potential (here, E ⁰ _Pr + RT / 3F · lnγ Means _{Pr (III))} .

Similarly, the potential (precipitation potential: E _{Pr · Ni} ) when the PrNi alloy is deposited on the electrode surface can be determined based on the following equation.
E _{Pr · Ni} = E ^{0 ′} _{Pr · Ni} + RT / 3F · lnC _{Pr (III)} (4) In the above formula (4), E ^{0 ′} _{Pr · Ni} is the formula electrode potential (here Then, E ⁰ _{Pr ·}
_Ni + RT / 3F · lnγ _{Pr (III))} .

Similarly, the precipitation potential can be obtained for each type of molten salt with respect to all precipitates by the above formula. In the process of depositing or alloying a specific metal on the cathode, the deposition potential value of this specific metal or its alloy is looked at, and the precipitate from which a potential difference with other metal or its alloy is obtained is selected. Determine the order of deposition.
Since the voltage and current in operation vary depending on the size and positional relationship of the electrodes, after determining the reference value by setting the conditions, determine it at each step based on the potential value and order obtained by the above method. To do.

As described above, in the method for producing a metal by molten salt electrolysis according to this embodiment, the target metal can be dissolved and deposited electrochemically by controlling the potential value. For this reason, a process can be simplified compared with the case of repeating processes, such as melt | dissolution and extraction using an acid etc. like the conventional wet process, and a specific element can be selectively isolate | separated and collect | recovered. Furthermore, it is not necessary to adjust the specific gravity of the molten salt, and a simple apparatus configuration can be obtained by selecting a low-temperature molten salt that can be processed in a solid state of the object. In addition, the operation mode can be simplified. For this reason, process efficiency and cost reduction can be achieved.

In addition, as described above, a specific metal can be smelted by a concept completely opposite to the concept of depositing or alloying a specific metal on the cathode.
That is, the method for producing a metal according to the present embodiment is a method for producing a specific metal by molten salt electrolysis from an ore containing two or more kinds of metal elements or a crude metal lump obtained from the ore. A cathode and an anode made of an anode material containing the ore or the coarse metal lump are provided therein, and a metal element corresponding to the potential from the ore or the coarse metal lump is controlled by controlling the potential at the anode to a predetermined value. A specific metal is left on the anode by dissolving in a molten salt.

In this method, the object (the ore or the coarse metal block) is used as an anode, and only a metal element other than a specific metal element, that is, an impurity, is dissolved in a molten salt, thereby leaving a specific metal on the anode. That's it. Also in this case, by controlling the potential at the anode, a phenomenon occurs in which the metal element to be smelted remains on the anode and the impurity element dissolves in the molten salt. Thereby, the metal material smelted by the anode is obtained.

Also in this method, in the step of dissolving the metal element from the ore or the coarse metal lump in the molten salt, the standard electrode potential of the specific metal or its alloy in the molten salt and the simple substance of other metal or The molten salt is preferably selected so that the difference from the standard electrode potential of the alloy is 0.05 V or more. Thereby, a specific metal and another metal can be isolate | separated favorably, and only a specific metal can remain in an anode. The difference in standard electrode potential is more preferably 0.1 V or more, and further preferably 0.25 V or more.
The value of the potential controlled at the anode can be calculated using the Nernst equation as described above.

As the ore used in the method for producing a metal by molten salt electrolysis according to the present embodiment, it is sufficient that the target specific metal is included. For example, gold ore, silver ore, copper ore, iron ore, aluminum ore, lead ore, zinc ore, tin ore, mercury ore, sulfur ore, phosphorus ore, nickel ore, cobalt ore, manganese ore, chromium ore, molybdenum ore, Examples include tungsten ore, antimony ore, arsenic ore, bismuth ore, strontium ore, beryllium ore, magnesium ore, barium ore, and calcium ore. For example, rare earth metals can be obtained by using bastonite, monazite, loparite, apatite, xenotime, fergsonite, udialite, and the like.

In addition, the crude metal block obtained from the ore refers to a metal whose target specific metal has a low purity, such as a metal obtained by smelting the ore.

The method for producing a metal by molten salt electrolysis according to the present embodiment is suitably applied to a material containing a transition metal or a rare earth metal (rare earth metal) as a crude metal block obtained from ore or ore used as an anode. Is done.
The transition metal is not particularly limited as long as it is an element included in Group 3 (Group IIIA) to Group 11 (Group IB) of the periodic table. The rare earth metal is not particularly limited as long as it is 15 elements of scandium (Sc), yttrium (Y), and lanthanoid belonging to Group 3 (IIIA group) of the periodic table.

The method for producing a metal by molten salt electrolysis according to this embodiment can be suitably used even when the specific metal deposited or alloyed on the cathode is a rare earth metal. In the present embodiment, by appropriately selecting the composition of the molten salt, a rare earth metal that cannot be precipitated by electrolysis with an aqueous solution can also be deposited. For this reason, it becomes possible to easily obtain rare earth metals that are difficult to collect in terms of resources.

Moreover, in this embodiment, it is preferable that the rough metal lump obtained from the said ore or ore is a granular form or a powder form. By making the said ore or rough metal lump to be processed into a granular or powder form, the surface area can be increased and the processing efficiency can be increased. From this viewpoint, the maximum particle size of the ore or the rough metal lump is preferably 0.01 mm to 2 mm, more preferably 0.01 mm to 1 mm, and still more preferably 0.01 mm to 0.2 mm.
Furthermore, it is preferable to compress the granular or powdered ore or coarse metal lump into the anode. The powdered ore or coarse metal lump can be used as an anode (anode) by compacting. In this case, it is desirable that there is a space where the molten salt can easily enter between the particles.

Hereinafter, the present embodiment will be described based on the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.
[First Embodiment-1]
As an example of this embodiment, a method is described in which Nd, Dy, and Pr are obtained by molten salt electrolysis using an ore containing neodymium (Nd), dysprosium (Dy), and praseodymium (Pr). As such ore, for example, monazite, apatite, xenotime, fergussonite, udialite and the like can be used.

First, as shown in FIG. 1, a preparatory process (S10) is implemented.
In this step, an ore that is an object to be processed, a molten salt to be used, and an apparatus including a container and an electrode for holding the molten salt are prepared. In addition, in order to accelerate | stimulate melt | dissolution in the molten salt of a process target object, it is also possible to grind | pulverize a process target object finely in order to enlarge the contact area of a process target object and molten salt.
As an ore containing Nd, Dy, and Pr, for example, a xenotime ore can be used. An example of the composition of xenotime ore is that Nd is 3.0%, Dy is 7.9%, and Pr is 0.5%.

Next, the melt | dissolution process (S20) in molten salt is implemented.
In this step (S20), the electric potential is controlled by immersing the ore and (another) electrode member in the prepared molten salt and connecting a power source between the ore and the electrode member. And the rare earth elements (Nd, Dy, and Pr) in the ore are selectively dissolved in the molten salt by adjusting the potential of the ore. As the molten salt, a molten salt having an arbitrary composition can be used.

For example, as an example, LiF—NaF—KF can be used as the molten salt, an electrode made of glassy carbon can be used as the other electrode member, and the ore can be used as the processing object.
In this case, for example, the heating temperature of the molten salt is set to 700 ° C., and Nd, Dy, and Pr can be selectively dissolved from the ore into the molten salt. The potential to be controlled is set such that elements other than Nd, Dy, and Pr are hardly dissolved in the molten salt while Nd, Dy, and Pr are dissolved.

Next, as shown in FIG. 1, a separation and extraction step (S30) is performed.
Specifically, as described above, a pair of electrodes is inserted into the molten salt in which Nd, Dy, and Pr are dissolved, and the potential at this electrode member is controlled to a predetermined value. The value of this potential is adjusted to a potential corresponding to the deposition potential determined for each rare earth metal as shown in FIG. 2, for example, when using a LiCl-KCl molten salt. As a result, the kind of rare earth metal deposited on the electrode can be selected according to the adjusted potential. For this reason, rare earth metals can be selectively recovered for each element.

For example, as shown in FIG. 2, the rare earth elements such as Nd, Dy, and Pr have different precipitation potential values for each element. Specifically, as shown in FIG. 2, the precipitation potential of Nd is about 0.40 V (vs. Li ⁺ / Li), and the precipitation potentials of Pr and Dy are about 0.47 V (vs. Li ⁺ / Li). In addition, the precipitation potential of DyNi ₂ which is a compound of Dy is about 0.77 V (vs. Li ⁺ / Li).
The deposition potential shown in FIG. 2 is based on Li. In FIG. 2, the vertical axis indicates the deposition potential (unit: V). The precipitation potential is a value when LiCl-KCl is used as the molten salt and the temperature of the molten salt is 450 ° C.

Since the deposition potential of each element or compound is different as described above, a pair of electrodes are immersed in a molten salt in which a specific metal is melted, and the cathode is controlled to have a potential corresponding to the above-described deposition potential. Thus, a specific rare earth element can be selectively deposited on the cathode. And the kind of the specific metal to deposit can also be selected by changing the value of the electric potential in a cathode (for example, changing an electric potential sequentially).

For example, as shown in FIG. 3, a pair of electrodes are immersed in the molten salt in which Nd, Dy, and Pr are dissolved, and different voltages are sequentially applied between the electrodes. Note that the concentrations (ion concentrations) of Nd, Dy, and Pr in the molten salt are 0.5 mol%, respectively.
When the data shown in FIG. 2 is used as the value of the precipitation potential, for example, LiCl-KCl is used as the molten salt, and the temperature of the molten salt is set to 450.degree. In FIG. 3, the horizontal axis represents the treatment time, and the vertical axis represents the ion concentration of the rare earth element in the molten salt. The unit of the vertical axis is mol%.

First, as STEP 1, Ni is used as the cathode material, and the cathode potential is lower than 0.77 V (vs. Li ⁺ / Li) and slightly higher than 0.63 V (vs. Li ⁺ / Li) (for example, setting) When the potential difference is 0.631 V (vs. Li ⁺ / Li)), Dy ions are alloyed with Ni of the cathode material, and DyNi ₂ is deposited on the cathode surface. As a result, as shown in FIG. 3, the ion concentration of Dy in the molten salt is rapidly reduced. The recovery of Dy can be performed until the Dy ion concentration in the molten salt is about 3.6 × 10 ⁻⁴ mol%.

Next, as STEP2, another electrode (for example, Mo electrode) is used as a cathode, and the potential of the cathode is slightly higher than 0.40V (vs. Li ⁺ / Li) (for example, the set potential difference is 0.401V). (Vs. Li ⁺ / Li)), Pr is deposited on one electrode (cathode). As a result, as shown in FIG. 3, the ion concentration of Pr in the molten salt is rapidly reduced. This recovery of Pr can be performed until the Pr ion concentration in the molten salt reaches about 0.017 mol%.
In STEP 2, an electrode different from the electrode on which DyNi ₂ is deposited in STEP 1 is used. For example, electrodes DyNi ₂ is precipitated in STEP1 is previously removed from the molten salt before STEP2 begins, it may be previously dipped another electrode in a molten salt, an electrode to which the DyNi ₂ was precipitated It may be left as it is, and the potential of another electrode may be controlled in STEP2.

Next, as STEP3, when the potential of another electrode (for example, Mo electrode) is set to 0.10 V (vs. Li ⁺ / Li), Nd is deposited on this electrode (cathode). As a result, as shown in FIG. 3, the ion concentration of Nd in the molten salt is rapidly reduced. The recovery of Nd can be performed until the Nd ion concentration in the molten salt becomes about 2.7 × 10 ⁻⁷ mol%, for example.
The electrode on which Pr is deposited in STEP 2 may be taken out from the molten salt before STEP 3 starts, and another electrode may be immersed in the molten salt. Alternatively, the electrode on which Pr is deposited in STEP 2 may be immersed in the molten salt as it is, and another electrode may be used in STEP 3.

For DyNi ₂ collected in STEP 1, as STEP 4, the electrode on which DyNi ₂ is deposited is immersed in a molten salt together with another electrode (for example, Mo electrode), and Dy dissolves the potential of the DyNi ₂ electrode. However, by setting Ni within a potential range (0.77 to 2.6 V (vs. Li ⁺ / Li)) that does not dissolve, Dy is dissolved in the molten salt and only Dy is deposited on the surface of another electrode. It can be deposited.
As described above, each target specific metal can be recovered from the molten salt.

(Apparatus used for the method of this embodiment)
Next, an apparatus used in the method of the present embodiment shown in FIG. 1 will be described with reference to FIGS. 4 and 5. The recovery device shown in FIG. 4 includes a container 1 that holds a molten salt therein, a molten salt 2 that is held inside the container 1, and a basket that holds a processing object (the ore or the rough metal lump) 3 inside. 4, electrodes 6 to 8, a heater 10 for heating the molten salt 2, and a control unit 9 electrically connected to the cage 4 and the electrodes 6 to 8 by a conductive wire 5. The controller 9 can control the potential of these electrodes (change the potential) using the cage 4 as one electrode and any of the electrodes 6 to 8 as the other electrode. Further, the control unit 9 can change the value of the potential to be controlled. The heater 10 is arranged so as to surround the container 1 in an annular shape. The electrodes 6 to 8 can be made of any material. For example, the electrode 6 can be made of nickel (Ni). Moreover, as a material of the

electrodes

7 and 8, for example, carbon (C) can be used. The shape of the container 1 may be a circular shape on the bottom or a polygonal shape. Further, the basket 4 can be the aforementioned basket.

The cage 4 and the electrodes 6 to 8 are controlled to a predetermined potential value by the control unit 9. By controlling the electrodes 6 to 8 at different potentials, different specific metals are deposited on the surfaces of the electrodes 6 to 8 depending on the value of the controlled potential as described later. For example, as described later, the value of the potential controlled by the electrode 6 can be adjusted so that the DyNi ₂ film 11 is deposited on the surface of the electrode 6. In addition, the Pr film 12 can be deposited on the surface of the electrode 7 by adjusting the potential controlled by the electrode 7. Further, the Nd film 13 can be deposited on the surface of the electrode 8 by adjusting the potential controlled to the electrode 8.

Then, the electrode 6 on which the DyNi ₂ film 11 is deposited is further placed in the container 1 holding the molten salt 2 therein as shown in FIG. Further, another electrode is arranged in the molten salt 2 so that the DyNi ₂ film 11 faces the electrode 6 deposited on the surface, and each

electrode

6, 15 is connected to the control unit 9 by the conductive wire 5. Then, the potential of the

electrodes

6 and 15 is controlled to a predetermined value by the controller 9 while the molten salt 2 is heated by the heater 10 disposed around the container 1. The potential to be controlled at this time is adjusted so that the potential at the cathode (electrode 15) becomes the deposition potential of Dy.
As a result, Dy is dissolved into the molten salt 2 from the DyNi ₂ film 11 deposited on the surface of the electrode 6, while the Dy film 16 is deposited on the surface of the electrode 15. In addition, the heating temperature of the molten salt 2 by the heater 10 can be set to, for example, 800 ° C. for any of the processes in the apparatus shown in FIGS. In this way, a specific metal can be deposited as a single substance on the surfaces of the

electrodes

7, 8, 15.

When implementing the method of this embodiment using the apparatus as shown in FIG.4 and FIG.5, it is possible to implement as follows, for example.
First, 9 kg of the ore is prepared as the object 3 to be processed, and LiF—NaF—KF is prepared as the molten salt 2. As the ore, for example, one containing 3.0 wt% Nd, 0.5 wt% Pr, and 7.9 wt% Dy can be used. The ore is crushed and placed inside the basket 4. From the viewpoint of improving the efficiency of the treatment, it is preferable to pulverize the ore that is the treatment object 3 as small as possible. For example, the maximum particle size is 2 mm or less, more preferably 1 mm or less, and even more preferably 0.2 mm or less. The ore is pulverized into fine granules. The amount of the molten salt 2 is about 16 liters (mass: 25 kg).

Then, STEP 1 to STEP 3 of the method of the present embodiment described with reference to FIG. 2 and FIG. carry out. Specifically, the processing object 3 and the electrode 6 held in the basket 4 as STEP 1 described above are used as a pair of electrodes, and the potential at the electrode is controlled to a predetermined value. As a result, DyNi ₂ is deposited on the surface of the electrode 6. Further, the processing object 3 and the electrode 7 held in the basket 4 as STEP 2 described above are used as a pair of electrodes, and the potential at the electrode is controlled to a predetermined value. Thereby, Pr is deposited on the surface of the electrode 7. The mass of the Pr film deposited on the surface of the electrode 7 shown in FIG.

In addition, the processing object 3 and the electrode 8 held in the basket 4 as the above STEP 3 are used as a pair of electrodes, and the potential at the electrode is controlled to a predetermined value. As a result, Nd is deposited on the surface of the electrode 8. The mass of the Nd film deposited on the surface of the electrode 8 is, for example, about 200 g to 300 g.

Further, as STEP 4 described above, the electrode 6 and the electrode 15 are arranged in the apparatus shown in FIG. 5, and the potential at these electrodes is controlled to a predetermined value in the molten salt. Thereby, Dy is deposited on the surface of the electrode 15. The mass of the Dy film 16 deposited on the surface of the electrode 15 is 600 g to 800 g, for example.
As described with reference to FIG. 4, the step of dissolving the target metal in the molten salt 2 and the step of depositing a specific metal as a simple substance on the surfaces of the

electrodes

7, 8 and the like are the same apparatus. (Using the same molten salt 2). On the other hand, for the step of separating and extracting Dy from DyNi ₂ shown in STEP 4 above, the device used in the step of dissolving the metal in the molten salt 2 described with reference to FIG. 4 (the device shown in FIG. 4) It is preferable to carry out in an apparatus different from () shown in FIG.

As described above, specific metals (for example, Dy, Pr, and Nd) can be recovered from the ore or the rough metal lump as the processing object 3.

[First embodiment-2]
As an example of this embodiment, a method of obtaining Nd, Dy, and Pr by molten salt electrolysis using a crude metal lump obtained by smelting ore containing neodymium (Nd), dysprosium (Dy), praseodymium (Pr) Is described.
As the crude metal block containing Nd, Dy, and Pr, for example, a mixed rare earth metal (dydymium) can be used. The refining method for obtaining the mixed rare earth metal is not particularly limited, and a known method can be used.

As shown in FIG. 6, first, a step (S11) of preparing a rough metal lump that is a processing object is performed. Specifically, as shown in FIG. 7, a crude metal lump as the processing object 3 is immersed in the molten salt 2 held in the container 1, and the power source in the control unit 9 is connected to the processing object 3. A conductive wire 5 for connection is connected. LiCl-KCl was used as the salt.

Then, the electrode material 25 held inside the cage 24 as the other electrode is immersed in the molten salt 2 together with the cage 24. As the electrode material 25, a material that is easily alloyed with an alkali metal such as Li or Na constituting a cation in the molten salt is used. Examples of the electrode material 25 include aluminum (Al), zinc (Zn), gallium (Ga), cadmium (Cd), indium (In), tin (Sn), antimony (Sb), lead (Pb), bismuth ( Bi) or the like can be used.

Next, the step (S21) of dissolving Nd, Dy, and Pr in the molten salt shown in FIG. 6 is performed.
Specifically, as shown in FIG. 7, the potential in the processing object 3 and the electrode material 25 held inside the basket 24 is controlled by the control unit 9, so that the potential in the processing object 3 is a predetermined value. Adjust to. As a result, rare earth elements such as Nd, Dy, and Pr are dissolved in the molten salt 2 from the crude metal block that is the processing object 3.

Next, a step (S31) of depositing DyNi ₂ by electrolysis shown in FIG. 6 is performed. Specifically, instead of the electrode material 25 held by the cage 24 shown in FIG. 7, the electrode 6 made of nickel is immersed in the molten salt 2 as shown in FIG. 8. The electrode 6 is connected to the control unit 9 by the conductive wire 5. In this state, the control unit 9 controls the potentials of the processing object 3 as one electrode and the electrode 6 as the other electrode to adjust to a predetermined value.
As a result, a rare earth element such as Dy is dissolved from the object to be treated 3 into the molten salt 2, and DyNi ₂ is deposited from the molten salt 2 on the surface of the electrode 6.

Next, a step of collecting Pr by electrolysis (S32) shown in FIG. 6 is performed. Specifically, as shown in FIG. 9, the electrode 27 made of carbon is immersed in the molten salt 2 as one electrode instead of the processing object 3. Further, instead of the electrode 6 shown in FIG. 8, an electrode 7 made of carbon is disposed in a state of being immersed in the molten salt 2 at a position facing the electrode 27. The electrode 27 and the electrode 7 are electrically connected to the control unit 9 and the conductive wire 5. In this state, the potential at one electrode 27 and the other electrode 7 is controlled to be adjusted to a predetermined value.
As a result, Pr dissolved in the molten salt 2 is deposited on the surface of the electrode 7. When chloride is used as the molten salt 2, chlorine gas (Cl ₂ ) is generated from the electrode 27 side.

Next, a step of recovering Nd by electrolysis (S33) shown in FIG. 6 is performed. Specifically, instead of the electrode 7, as shown in FIG. 10, the electrode 8 made of carbon is disposed so as to be opposed to the electrode 27 while being immersed in the molten salt 2. The electrode 8 is electrically connected to the control unit 9 by the conductive wire 5. Then, the potential at the electrode 8 and the electrode 27 is controlled by the control unit 9 to be adjusted to a predetermined value. As a result, Nd is deposited on the surface of the electrode 8. At this time, chlorine gas is generated from the electrode 27 side.

Next, a step (S34) of recovering Dy by electrolysis from DyNi ₂ recovered in the step (S31) is performed. Specifically, as shown in FIG. 5, the electrode 6 (see FIG. 8) on which DyNi ₂ is deposited is immersed in the molten salt 2, and another electrode 15 is immersed in the molten salt 2. The potentials at these

electrodes

6 and 15 are adjusted to a predetermined value by the control unit 9. Thereby, after Dy is once dissolved in the molten salt 2 from DyNi ₂ deposited on the surface of the electrode 6, the Dy film 16 is deposited on the surface of the electrode 15. In this way, the rare earth metals Nd, Dy, Pr can be individually recovered.

Note that the above-described steps (S21 to S32) may be performed by the following apparatus configuration. For example, the above-described step (S31) may be performed with an apparatus configuration as shown in FIG.
Specifically, the cage 24 holding the material 26 alloyed in the process shown in FIG. 7 is immersed in the molten salt 2 instead of the processing object 3 in the apparatus configuration shown in FIG. Then, as shown in FIG. 11, the basket 24 and the control unit 9 are electrically connected by the conductive wire 5. Then, the potential of the electrode 6 and the material 26 alloyed in the process shown in FIG. 7 and held in the cage 24 is adjusted to a predetermined value. Thereby, Dy dissolved in the molten salt ₂ is deposited as DyNi _{2 on} the surface of the electrode 6. It should be noted that Dy can be recovered as a simple substance from the DyNi ₂ deposited on the surface of the electrode 6 by a process similar to the process (S34) of FIG.

Next, as the step (S32) described above, processing may be performed with an apparatus configuration as shown in FIG. Specifically, instead of the electrode 6 shown in FIG. 11, the electrode 7 made of carbon is arranged at a position facing the cage 24 and immersed in the molten salt 2 as shown in FIG. 12. The electrode 7 and the control unit 9 are electrically connected by the conductive wire 5. And the electric potential in the alloy 26 and the electrode 7 hold | maintained inside the cage | basket 24 is controlled to a predetermined value by a control part. As a result, Pr dissolved in the molten salt 2 is deposited on the surface of the electrode 7.

Next, as the above-described step (S33), processing may be performed with an apparatus configuration as shown in FIG. Specifically, as shown in FIG. 13, instead of the electrode 7 of FIG. 12, an electrode 8 made of carbon is disposed at a position facing the cage 24 and immersed in the molten salt 2. Then, the electrode 8 and the control unit 9 are electrically connected by the conductive wire 5. The potential is adjusted to a predetermined value by controlling the potential at the electrode 26 and the alloy 26 disposed inside the cage 24 by the control unit 9. As a result, Nd is deposited on the surface of the electrode 8.

By the method as described above, the specific metals contained in the rough metal lump can be recovered individually and sequentially. In addition, according to the method of the present embodiment, the apparatus configuration can be simplified and the processing time can be shortened as compared with the conventional wet separation method, so that the cost for obtaining elements such as rare earth elements is reduced. be able to. Furthermore, since a specific metal can be deposited as a simple substance on the electrode surface by appropriately setting the potential at the electrode, a highly pure metal can be obtained. In addition, the electric potential for depositing each metal or alloy can be calculated by the above-described calculation.

[Second Embodiment]
The method for producing tungsten by molten salt electrolysis according to the present embodiment is a method for producing tungsten from a treatment object containing tungsten by molten salt electrolysis, and a step of dissolving tungsten from the treatment object in the molten salt; Providing a pair of electrode members in the molten salt in which the tungsten is dissolved, and precipitating tungsten present in the molten salt on one of the electrode members by controlling the potential at the electrode member to a predetermined value. It is characterized by that.

That is, the present embodiment is roughly divided into a process in which tungsten contained in the object to be processed is dissolved in a molten salt, and tungsten is deposited on one electrode (cathode) by molten salt electrolysis from the molten salt in which the tungsten is dissolved. Process. The feature of this embodiment is that tungsten is selectively precipitated by controlling the potential at the electrode to obtain high-purity tungsten.

First, a process for dissolving tungsten contained in the object to be processed in the molten salt will be described.
As a method for dissolving tungsten contained in the object to be treated in the molten salt, for example, a method of dissolving by a chemical method can be mentioned. Specifically, the processing object is pulverized into granules and powders, and these and a salt are mixed and heated, whereby tungsten contained in the processing object can be dissolved in the molten salt. Further, the object to be treated may be put into molten salt and dissolved.

別 Another method is an electrochemical method. Specifically, an anode made of an anode material containing a processing object is provided in the molten salt, and tungsten contained in the processing object is selectively selected depending on the magnitude of the potential to be controlled by the processing object attached as the anode. Dissolve. In molten salt electrolysis, since the potential at which an element dissolves has different properties depending on the type of element, tungsten can be separated from other metals using this property. In this way, tungsten can be selectively dissolved in the molten salt by controlling the potential at the time of dissolution using the object to be treated as the anode.

すべて In this step, all of the object to be treated may be dissolved, or a part of tungsten or only tungsten may be dissolved. Conditions under which metals other than tungsten contained in the object to be processed may be dissolved, but it is preferable to control the potential so that only tungsten is dissolved as much as possible. That is, in the step of dissolving tungsten in the molten salt, it is preferable to selectively dissolve tungsten in the molten salt by controlling the potentials at the anode and the cathode to predetermined values. Thereby, it is possible to reduce the amount of impurities introduced in the subsequent deposition step.

For this purpose, in the step of dissolving tungsten from the object to be treated in the molten salt, the standard electrode potential of the tungsten alone or tungsten alloy in the molten salt and the standard electrode potential of another metal alone or alloy thereof It is preferable to select the molten salt so that the difference between the two is 0.05 V or more. Thereby, the tungsten dissolved in the molten salt and the metal element remaining on the anode can be satisfactorily separated. The difference in the standard electrode potential is more preferably 0.1 V or more, and further preferably 0.25 V or more.
The value of the potential controlled at the anode can be calculated by the Nernst equation described later.

陰極 As the cathode used in the melting step, a material which is easily alloyed with an alkali metal such as Li or Na constituting carbon or a cation in the molten salt is used. For example, use aluminum (Al), zinc (Zn), gallium (Ga), cadmium (Cd), indium (In), tin (Sn), antimony (Sb), lead (Pb), bismuth (Bi), etc. Can do.

In order to use the object to be treated containing tungsten as an anode, for example, the object to be treated may be accommodated in a conductive basket (anode material) made of metal or the like and provided in the molten salt. An opening is provided in the upper part of the basket so that the object to be processed can be inserted into the interior from the opening, and a large number of holes are formed in the side wall and the bottom wall of the basket so that the molten salt can flow into the interior of the basket. You can do that. As a material constituting the cage, any material such as a net-like member formed by knitting a metal wire or a sheet member in which a large number of holes are formed in a sheet-like metal plate can be used. In particular, it is effective to use C, Pt, Mo or the like as the material.
When the object is an oxide or the like and has a high electric resistance, the contact amount with the conductive material is preferably increased. It is effective to use the electrode as an electrode by wrapping it with a metal mesh member or filling the space inside the porous metal body.

Control in which the cathode and an anode made of an anode material containing the object to be processed (for example, a metal basket holding the object to be processed inside) are provided in the molten salt, and the electric potential is controlled from the outside at both electrodes. By connecting the parts and controlling the potential as described above, tungsten can be dissolved in the molten salt from the object to be treated.

In the next deposition process, tungsten is deposited on one electrode member (cathode) by providing a pair of electrode members in the molten salt in which the tungsten is dissolved and performing molten salt electrolysis. In this case, tungsten can be selectively deposited as a metal or alloy on the cathode depending on the magnitude of the potential controlled by molten salt electrolysis.

Also in this deposition process, tungsten and other metals are separated by utilizing the property that in molten salt electrolysis, the potential at which an element is deposited on the cathode as a metal or alloy varies depending on the type of element, as in the case of the melting process. To do. Accordingly, even when a metal other than tungsten is contained in the molten salt, only tungsten can be deposited on the cathode by controlling the potential. Thereby, high purity tungsten can be obtained.

When depositing tungsten, if the difference between the dissolution / precipitation potential of tungsten and the dissolution / precipitation potential of other metals contained in the molten salt is small and difficult to separate from the metal, the cathode The cathode material may be selected and the potential may be controlled so that the material and tungsten are alloyed and deposited. As a result, tungsten in the molten salt is separated from other impurity metals as a tungsten alloy, and then, for example, a melting step and a precipitation step are performed in another molten salt using a cathode material alloyed with tungsten. As a result, high-purity tungsten can be obtained.

電極 As the electrode member used in the deposition step, for example, nickel (Ni), molybdenum (Mo), glassy carbon (C), or the like can be used.

In the present embodiment, tungsten is separated and extracted from the object to be processed by the above two processes. In this embodiment, since the molten salt is used, it is necessary to heat the system so that the temperature of the system in each process is equal to or higher than the melting point of the molten salt.
It is also possible to smelt with the opposite idea in this process. That is, only the metal element which becomes an impurity is dissolved in the molten salt with the object to be processed as an anode. Also in this case, by controlling the potential at the anode to a predetermined value, a phenomenon occurs in which tungsten remains on the anode and the impurity element dissolves. Thereby, tungsten is obtained at the anode.

A feature of the above two processes is the use of molten salt. In other words, by utilizing the property of molten salt electrolysis in which the potential of dissolution / precipitation of each element varies depending on the type of molten salt, the dissolution / precipitation potential of tungsten and the dissolution / precipitation potential of the target metal other than tungsten are determined. It is possible to select and design the molten salt so as to be a value that is sufficiently separated and easy to process.
Specifically, in the step of precipitating or alloying tungsten, the difference between the standard electrode potential of tungsten alone or tungsten alloy in the molten salt and the standard electrode potential of another impurity metal alone or alloy thereof is 0. It is preferable to select the molten salt so that it becomes 05 V or higher. The difference between the standard electrode potential of the tungsten simple substance or tungsten alloy in the molten salt and the standard electrode potential of another metal simple substance or alloy thereof is more preferably 0.1 V or more, and 0.25 V or more. Is more preferable.
Thus, in the step of depositing or alloying tungsten, it is preferable to selectively precipitate or alloy the tungsten in the molten salt by controlling the potential of the electrode member to a predetermined value.

The deposition potential of tungsten deposited on the cathode can be calculated by electrochemical calculation. Specifically, it is calculated using the Nernst equation.
For example, the potential for depositing single W from divalent tungsten (W) ions (hereinafter referred to as W (II)) can be obtained by the following equation.

E _W = E ⁰ _W + RT / 3F · ln (a _{W (II)} / a _{W (0)} ) (1) In the above formula (1), E ⁰ _W is a standard potential, R Is the gas constant, T is the absolute temperature, F is the Faraday number, a _{W (II)} is the activity of W (II) ions, and a _{W (0)} is the activity of W alone.

When the above equation (1) is rewritten in consideration of the activity coefficient γ _{W (II)} , a _{W (0)} = 1, so that the following equation is obtained.
E _Wr = E ⁰ _W + RT / 3F · lna _{W (II)}
= E ⁰ _W + RT / 3F · ln (γ _{W (II)} · C _{W (II)} ) (2) E _W = E ^{0 ′} _W + RT / 3F · lnC _{W (II)} Formula (3)
In the above formula (3), C _{W (II)} is the concentration of divalent W ions, E ^{0 ′} _W is the formula electrode potential (here, E ⁰ _W + RT / 3F · lnγ _{W (II)} Means).

Similarly, the precipitation potential can be obtained for each type of molten salt with respect to all precipitates by the above formula. The same calculation can be performed when tungsten is alloyed and deposited. In the process of depositing or alloying tungsten on the cathode, the precipitation potential of this single tungsten or tungsten alloy is observed, and melting is performed so as to obtain a sufficient potential difference from the precipitation potential of another single metal or its alloy. The salt or cathode material is selected and it is determined whether to deposit as tungsten or tungsten alloy.
Since the voltage and current in operation vary depending on the size and positional relationship of the electrodes, after determining the reference value by setting the conditions, determine it at each step based on the potential value and order obtained by the above method. To do.

As described above, in the method for producing tungsten by molten salt electrolysis according to this embodiment, tungsten can be dissolved and deposited electrochemically by controlling the value of the potential. For this reason, a process can be simplified compared with the case of repeating processes, such as melt | dissolution and extraction using an acid etc. like the conventional wet process, and a specific element can be selectively isolate | separated and collect | recovered. Furthermore, it is not necessary to adjust the specific gravity of the molten salt, and by selecting a low-temperature molten salt that can treat tungsten in a solid state, a simple apparatus configuration can be obtained. In addition, the operation mode can be simplified. For this reason, it is possible to increase the efficiency and cost of the process.

Further, as described above, tungsten can be smelted in a way that is completely opposite to the way of depositing or alloying tungsten on the cathode.
That is, the method for producing a metal according to the present embodiment is a method for producing tungsten from a processing object containing tungsten by molten salt electrolysis, and includes a cathode in the molten salt and an anode material containing the processing object. An anode is provided, and by controlling the potential at the anode, the metal element corresponding to the potential value is dissolved in the molten salt from the object to be processed, so that tungsten remains in the anode.

This method uses the anode material containing the object to be treated as an anode, and dissolves only the metal element other than tungsten, that is, an impurity, in the molten salt, thereby leaving tungsten on the anode. Also in this case, by controlling the potential at the anode, it is possible to generate a phenomenon in which tungsten to be smelted remains on the anode and the impurity element dissolves in the molten salt. Thereby, tungsten refined on the anode is obtained.

Also in this method, in the step of dissolving the metal element from the object to be treated in the molten salt, the standard electrode potential of tungsten alone or tungsten alloy in the molten salt and the standard electrode potential of another metal alone or alloy thereof It is preferable to select the molten salt so that the difference from the above becomes 0.05 V or more. Thereby, tungsten and other metals can be satisfactorily separated, and only tungsten can remain on the anode. The difference in standard electrode potential is more preferably 0.1 V or more, and further preferably 0.25 V or more.
The value of the potential controlled at the anode can be calculated using the Nernst equation as described above.

In the method for producing tungsten by molten salt electrolysis according to the present embodiment, for example, a metal material containing tungsten can be preferably used as the processing object containing tungsten. Examples of the metal material containing tungsten include a tungsten heater.

In addition, the present embodiment can be preferably applied to the case where the processing object is a metal material containing tungsten and a transition metal. The transition metal is not particularly limited as long as it is an element included in Group 3 (Group IIIA) to Group 11 (Group IB) of the periodic table. Examples of the metal material containing tungsten and transition metal include cemented carbide.

超 For example, a cemented carbide product can be used as the processing object. The cemented carbide product here is a general term for products using a cemented carbide material, and examples thereof include cutting tools, jigs and tools, and molds using the cemented carbide material.

As the molten salt, a chloride-based molten salt or a fluoride-based molten salt can be used. A molten salt obtained by mixing a chloride-based molten salt and a fluoride-based molten salt can also be used.
The molten salt of the chloride-based, for example _{KCl, NaCl, CaCl 2, LiCl} , RbCl, CsCl, be used, for example _{_{_{SrCl 2, BaCl 2, MgCl 2}}} . As the molten salt fluoride, e.g. LiF, may NaF, KF, RbF, CsF, be used _{_{_{MgF 2, CaF 2, SrF 2}}} , BaF 2. It is preferable to use a chloride-based molten salt from the viewpoint of efficiency, and KCl, NaCl, and CaCl ₂ are particularly preferable because they are inexpensive and easily available.
Moreover, the use of these molten salts can be used as a molten salt of any composition by combining a plurality of types of molten salt, for example KCl-CaCl ₂ and LiCl-KCl or molten salt composition, such as NaCl-KCl, it can.

In the method for producing tungsten by molten salt electrolysis according to this embodiment, the following apparatus can be preferably used. That is, an apparatus used in the method for producing tungsten by molten salt electrolysis according to the present embodiment includes a container holding a molten salt therein, a cathode immersed in the molten salt held inside the container, It is immersed in a molten salt held inside, and has an anode that holds a conductive object to be processed containing tungsten, and the anode allows the molten salt to flow between the inside and the outside. Furthermore, a control unit for controlling the potential at the cathode and the anode to a predetermined value is provided, and the control unit can change the value of the potential. An apparatus used in the method for producing tungsten by molten salt electrolysis according to the present embodiment includes a container holding therein a molten salt in which tungsten is dissolved, and a cathode immersed in the molten salt held inside the container. An anode, and a controller that controls the cathode and the potential at the anode to a predetermined value, wherein the controller can change the value of the potential.

The apparatus of this embodiment is demonstrated with reference to FIG. 18 and FIG. The apparatus shown in FIG. 18 includes a container 1 that holds a molten salt therein, a molten salt 2 that is held inside the container 1, a basket 4 that holds a treatment object 3 containing tungsten, and an electrode 6; The heater 10 for heating the molten salt 2 and the control unit 9 electrically connected to the cage 4 and the electrode 6 by the conductive wire 5 are provided.
The control unit 9 can control the potential at this electrode to a predetermined value with the cage 4 as one electrode (anode) and the electrode 6 as the other electrode (cathode). Further, the control unit 9 can change the value of the potential to be controlled. The heater 10 is arranged so as to surround the container 1 in an annular shape. The electrode 6 can be made of any material, and for example, carbon can be used. The shape of the container 1 may be a circular shape on the bottom or a polygonal shape. Further, as the basket 4, the aforementioned basket can be used.

A potential is controlled between the cage 4 and the electrode 6 by the control unit 9 so as to have a predetermined potential value. As a result, tungsten is dissolved in the molten salt 2 from the processing object 3.
Then, after tungsten is sufficiently dissolved from the processing object 3, the cage 4 and the electrode 6 are taken out, and another electrode 7 (cathode) and electrode 8 (anode) are put into the molten salt 2. The

electrodes

7 and 8 are connected to the control unit 9 through the conductive wires 5, respectively. And the electric potential in the

electrodes

7 and 8 is controlled from the control part 9 to a predetermined value. At this time, the potential to be controlled is adjusted so that the potential of the electrode 7 becomes the deposition potential of tungsten. As a result, tungsten dissolved in the molten salt 2 is deposited on the surface of the electrode 7 (cathode). As a material for the

electrodes

7 and 8, for example, glassy carbon (C) can be used.

It should be noted that the heating temperature of the molten salt 2 by the heater 10 can be set to 800 ° C., for example, in any of the treatments in the apparatus shown in FIGS. In this way, tungsten can be deposited as a simple substance on the surface of the electrode 7.

Note that the potential controlled in the

electrodes

7 and 8 may be adjusted so that an alloy of tungsten and a cathode material is deposited on the surface of the electrode 7 (cathode). In this case, the above-described melting step and precipitation step may be performed using the alloyed electrode 7. That is, a new apparatus as shown in FIG. 18 may be prepared, and the electrode 7 alloyed with tungsten may be used in place of the processing object 3 described above.

When performing the tungsten manufacturing method according to the present embodiment using the apparatus as shown in FIGS. 18 and 19, for example, the following may be considered.
First, 9 kg of a cemented carbide cutting tool is prepared as the processing object 3, and KCl—NaCl is prepared as the molten salt 2. As the cemented carbide cutting tool, for example, 90 wt% tungsten carbide (WC) and 10 wt% cobalt (Co) are contained. The cemented carbide cutting tool is pulverized and placed inside the basket 4. From the viewpoint of improving the processing efficiency, it is preferable that the cemented carbide cutting tool that is the processing object 3 is pulverized as small as possible. The cemented carbide cutting tool is crushed into such a granular shape. The amount of the molten salt 2 is about 16 liters (mass: 25 kg).
Then, the above-described dissolution process is performed using an electrode made of carbon as the electrode 6, and then the deposition process is performed using electrodes made of glassy carbon as the

electrodes

7 and 8.

As described above, tungsten can be recovered from the cemented carbide cutting tool as the processing object 3. According to the method for producing tungsten by molten salt electrolysis according to the present embodiment, the apparatus configuration can be simplified and the processing time can be shortened as compared with the conventional wet separation method, so that the cost can be reduced. . Furthermore, by setting the potential at the electrode appropriately, tungsten can be deposited as a simple substance on the electrode surface, so that tungsten with high purity can be obtained. In addition, the electric potential for depositing each tungsten or tungsten alloy can be calculated by the above-described calculation.

[Third embodiment]
The method for producing lithium by molten salt electrolysis according to the present embodiment is a method for producing lithium from a treatment object containing lithium by molten salt electrolysis, the step of dissolving lithium from the treatment object in the molten salt; Providing a pair of electrode members in the molten salt in which the lithium is dissolved, and precipitating lithium existing in the molten salt on one of the electrode members by controlling the potential at the electrode member to a predetermined value. It is characterized by that.

That is, the method for producing lithium according to the present embodiment includes a process of dissolving lithium contained in the object to be processed in a molten salt, and a lithium salt dissolved in one electrode (cathode) by molten salt electrolysis from the molten salt. And a step of precipitating. The feature of this embodiment is that the potential at the electrode is controlled in the lithium melting step to selectively dissolve lithium from the object to be processed, and the potential at the electrode is controlled to a predetermined value in the lithium deposition step. This is to obtain lithium having high purity by selectively precipitating lithium from the molten salt on the cathode.

First, the process of dissolving lithium contained in the object to be treated in the molten salt will be described.
As a method of dissolving lithium contained in the object to be treated in the molten salt, for example, a method of dissolving by a chemical method can be mentioned. Specifically, the processing object is pulverized into granules and powders, and these and a salt are mixed and heated, whereby lithium contained in the processing object can be dissolved in the molten salt. Further, the object to be treated may be put into molten salt and dissolved.
Another method is an electrochemical method. Specifically, an anode made of an anode material containing a processing object is provided in the molten salt, and the potential value in the processing object attached as the anode is controlled to selectively select lithium contained in the processing object. Dissolve in. In molten salt electrolysis, the potential at which an element dissolves varies depending on the type of element. Thus, by using the object to be treated as an anode and controlling the potential at the time of dissolution, lithium is selectively molten salt. It can be dissolved in to separate lithium from other metals.

In this step, the entire object to be treated may be dissolved, or a part of lithium or only lithium may be dissolved. Although metals other than lithium contained in the object to be treated may be dissolved, it is preferable to control the potential value so that only lithium is dissolved as much as possible. That is, in the step of dissolving lithium in the molten salt, it is preferable to selectively dissolve lithium in the molten salt by controlling the potentials at the anode and the cathode to predetermined values. Thereby, it is possible to reduce the amount of impurities introduced in the subsequent deposition step.
For this purpose, in the step of dissolving lithium from the object to be treated in the molten salt, the standard electrode potential of lithium alone or lithium alloy in the molten salt and the standard electrode potential of another metal alone or alloy thereof It is preferable to select the molten salt so that the difference between the two is 0.05 V or more. Thereby, the lithium dissolved in the molten salt and the metal element remaining on the anode can be well separated. The difference in the standard electrode potential is more preferably 0.1 V or more, and further preferably 0.25 V or more.
The value of the potential controlled at the anode can be calculated by the Nernst equation described later.

In order to use the object to be treated containing lithium as an anode, for example, the object to be treated may be accommodated in a conductive basket (anode material) made of metal or the like and provided in the molten salt. An opening is provided in the upper part of the basket so that the object to be processed can be inserted into the interior from the opening, and a large number of holes are formed in the side wall and the bottom wall of the basket so that the molten salt can flow into the interior of the basket. You can do that. As a material constituting the cage, any material such as a net-like member formed by knitting a metal wire or a sheet member in which a large number of holes are formed in a sheet-like metal plate can be used. In particular, it is effective to use C, Pt, Mo or the like as the material.
When the object is an oxide or the like and has a high electric resistance, the contact amount with the conductive material is preferably increased. It is effective to use the electrode as an electrode by wrapping it with a metal mesh member or filling the space inside the porous metal body.

The cathode and an anode made of an anode material containing the object to be processed (for example, a metal cage holding the object to be processed inside) are provided in the molten salt, and a predetermined potential is externally applied between the electrodes. By connecting to a control unit that controls the value and controlling the potential as described above, lithium can be dissolved from the object to be processed in the molten salt.

In the subsequent deposition step, lithium is deposited on one electrode member (cathode) by providing a pair of electrode members in the molten salt in which lithium is dissolved and performing molten salt electrolysis. In this case, lithium can be selectively deposited as a metal or alloy on the cathode depending on the magnitude of the potential controlled by molten salt electrolysis.

In this precipitation step, as in the melting step, lithium and other metals are separated by utilizing the property that in molten salt electrolysis, the potential at which an element is deposited on the cathode as a metal or alloy varies depending on the type of element. To do. Thereby, even when metals other than lithium are contained in the molten salt, only lithium can be deposited on the cathode by controlling the potential. Thereby, high purity lithium can be obtained.

When depositing lithium, if the difference between the dissolution / precipitation potential of lithium and the dissolution / precipitation potential of other metals contained in the molten salt is small and difficult to separate from the metal, the cathode The cathode material may be selected and the potential may be controlled so that the material and lithium are alloyed and deposited. Thereby, lithium in the molten salt is separated from other impurity metals as a lithium alloy, and then, by using a cathode material alloyed with lithium, a melting step and a precipitation step are performed in another molten salt. High purity lithium can be obtained.

In the present embodiment, lithium is separated and recovered from the object to be processed by the two steps as described above.
In this embodiment, since the molten salt is used, it is necessary to heat the system so that the temperature of the system in each step is equal to or higher than the melting point of the molten salt.

The feature of the above two steps is that a molten salt is used as the electrolytic solution. That is, by utilizing the property of molten salt electrolysis in which the dissolution and precipitation potential of each element varies depending on the type of molten salt, the dissolution and precipitation potential of lithium and the dissolution and precipitation potential of the metal that is an impurity target other than lithium are determined. It is possible to select and design the molten salt so that it becomes a value that is sufficiently separated and easy to process.
Specifically, in the step of depositing or alloying lithium, the difference between the standard electrode potential of lithium alone or lithium alloy in the molten salt and the standard electrode potential of another impurity metal alone or alloy thereof is 0.05 V. The molten salt is preferably selected so as to achieve the above. The difference between the standard electrode potential of the lithium alone or lithium alloy in the molten salt and the standard electrode potential of another metal alone or its alloy is more preferably 0.1 V or more, and 0.25 V or more. Is more preferable.
Thus, in the step of precipitating or alloying the lithium, it is preferable to selectively precipitate or alloy the lithium in the molten salt by controlling the potential of the electrode member to a predetermined value.

The deposition potential of lithium deposited on the cathode can be calculated by electrochemical calculation. Specifically, it is calculated using the Nernst equation.
For example, the potential for depositing Li alone from lithium ions (Li ⁺ ) can be obtained by the following equation.

_{^{_{_{E Li = E 0 Li + RT}}}} / 3F · ln (a Li (I) / a Li (0)) ··· formula (1)
In the above formula (1), E ⁰ _Li is the standard potential, R is the gas constant, T is the absolute temperature, F is the Faraday number, a _{Li (I)} is the Li ion activity, a _{Li (0)} means the activity of Li alone.

When the above equation (1) is rewritten in consideration of the activity coefficient γ _{Li (I)} , since a _{Li (0)} = 1, the following equation is obtained.
E _Li = E ⁰ _Li + RT / 3F · lna _{Li (I)}
= E ⁰ _Li + RT / 3F · ln (γ _{Li (I)} · C _{Li (I)} ) (2) E _Li = E ^{0 ′} _Li + RT / 3F · lnC _{Li (I)} Formula (3)
In the above formula (3), C _{Li (I)} is the concentration of Li ions, E ^{0 ′} _Li is the formula electrode potential (here, E ⁰ _Li + RT / 3F · lnγ _{Li (I)} is equal) Means each.

Similarly, the potential (precipitation potential: E _LiM ) when a LiM alloy (M is a metal to be alloyed) is deposited on the electrode surface can be determined based on the following equation.
E _{Li · M} = E ^{0 ′} _{Li · M} + RT / 3F · lnC _{Li (I)} Formula (4)
In the above formula (4), E ^{0 ′} _{Li · M} means a formula electrode potential (here, equal to E ⁰ _{Li · M} + RT / 3F · lnγ _{Li (I))} .

Similarly, the precipitation potential can be obtained for each type of molten salt with respect to all precipitates by the above formula. In the step of depositing or alloying lithium on the cathode, the lithium is melted so that a sufficient potential difference can be obtained from the deposition potential of another single metal or its alloy by observing the value of the deposition potential of this single lithium or lithium alloy. The salt or cathode material is selected, and it is determined whether to deposit as lithium or as a lithium alloy.
Since the voltage and current in operation vary depending on the size and positional relationship of the electrodes, after determining the reference value by setting the conditions, determine it at each step based on the potential value and order obtained by the above method. To do.

As described above, in the method for producing lithium by molten salt electrolysis according to this embodiment, lithium can be dissolved and precipitated electrochemically by controlling the potential value. For this reason, a process can be simplified compared with the case where the process of melt | dissolution and extraction using an acid etc. is repeated like the conventional wet process, and a specific element can be selectively isolate | separated and collect | recovered. Furthermore, it is not necessary to adjust the specific gravity of the molten salt, and by selecting a low-temperature molten salt capable of treating lithium in a solid state, a simple apparatus configuration can be obtained. In addition, the operation mode can be simplified. For this reason, it is possible to increase the efficiency and cost of the process.

In the method for producing lithium by molten salt electrolysis according to the present embodiment, the material to be treated is not limited as long as it is a material containing lithium, but preferred examples include a negative electrode material for a lithium primary battery and a lithium ion secondary battery. A positive electrode material can be mentioned.
For example, as a positive electrode active material of a positive electrode material of a lithium ion secondary battery, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium nickel cobaltate (LiCo _0.3 Ni _0.7 O ₂ ), lithium manganate ( LiMn ₂ O ₄ ), lithium titanate (Li ₄ Ti ₅ O ₁₂ ), lithium manganate compound (LiM _y Mn _{2 -y} O ₄ ); M = Cr, Co, Ni), lithium acid and the like.

In the method for producing lithium by molten salt electrolysis according to this embodiment, the following apparatus can be preferably used. That is, an apparatus used in the method for producing lithium by molten salt electrolysis according to the present embodiment includes a container holding a molten salt therein, a cathode immersed in the molten salt held inside the container, It is immersed in a molten salt held inside, and includes an anode holding a conductive processing object containing lithium inside, and the anode allows the molten salt to flow between the inside and the outside. Furthermore, a control unit for controlling the potential at the cathode and the anode to a predetermined value is provided, and the control unit can change the value of the potential.
The apparatus used for the method for producing lithium by molten salt electrolysis according to the present embodiment includes a container holding therein a molten salt in which lithium is dissolved, and a cathode immersed in the molten salt held inside the container. An anode, and a controller that controls the cathode and the potential at the anode to a predetermined value, wherein the controller can change the value of the potential.

The apparatus of the present embodiment will be described with reference to FIGS. The apparatus shown in FIG. 18 includes a container 1 that holds a molten salt therein, a molten salt 2 that is held inside the container 1, a basket 4 that holds a processing object 3 containing lithium, and an electrode 6; The heater 10 for heating the molten salt 2 and the control unit 9 electrically connected to the cage 4 and the electrode 6 by the conductive wire 5 are provided.
The control unit 9 can control the potential at this electrode to a predetermined value with the cage 4 as one electrode (anode) and the electrode 6 as the other electrode (cathode). Further, the control unit 9 can change the value of the potential to be controlled. The heater 10 is arranged so as to surround the container 1 in an annular shape. The electrode 6 can be made of any material, and for example, aluminum can be used. The shape of the container 1 may be a circular shape on the bottom or a polygonal shape. Further, as the basket 4, the aforementioned basket can be used.

A potential is controlled between the cage 4 and the electrode 6 by the control unit 9 so as to have a predetermined potential value. As a result, lithium is dissolved in the molten salt 2 from the processing object 3.
After the lithium is sufficiently dissolved from the object 3 to be processed, the cage 4 and the electrode 6 are taken out, and another electrode 7 (cathode) and electrode 8 (anode) are put into the molten salt 2 as shown in FIG. . The

electrodes

7 and 8 is controlled from the control part 9 to a predetermined value. At this time, the potential to be controlled is adjusted so that the potential of the electrode 7 becomes the deposition potential of lithium. As a result, lithium dissolved in the molten salt 2 is deposited on the surface of the electrode 7 (cathode). As a material for the

electrodes

7 and 8, for example, glassy carbon (C) can be used.

It should be noted that the heating temperature of the molten salt 2 by the heater 10 can be set to 800 ° C., for example, in any of the treatments in the apparatus shown in FIGS. In this way, lithium can be deposited as a simple substance on the surface of the electrode 7.

Note that the potential value controlled in the

electrodes

7 and 8 may be adjusted so that an alloy of lithium and a cathode material is deposited on the surface of the electrode 7 (cathode). In this case, the above-described melting step and precipitation step may be performed using the alloyed electrode 7. That is, a new apparatus as shown in FIG. 18 may be prepared, and the electrode 7 alloyed with lithium may be used in place of the processing object 3 described above.

When the method for producing lithium according to the present embodiment is performed using the apparatus as shown in FIGS. 18 and 19, for example, the following may be considered.
First, a cathode material of a lithium ion battery containing lithium is prepared as the processing object 3, and KCl—NaCl is prepared as the molten salt 2. As the positive electrode material, for example, a powder containing lithium cobalt oxide (LiCoO ₂ ) or lithium manganate is used. The positive electrode material is pulverized and placed inside the cage 4. From the viewpoint of improving the processing efficiency, the positive electrode material that is the processing object 3 is preferably pulverized as small as possible. For example, the maximum particle size is 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less. The positive electrode material is pulverized into granules. Then, the above-described dissolution process is performed using an electrode made of carbon as the electrode 6, and then the deposition process is performed using electrodes made of glassy carbon as the

electrodes

7 and 8.
As described above, lithium can be recovered from the positive electrode material as the processing object 3.

According to the method for producing lithium by molten salt electrolysis according to the present embodiment, the apparatus configuration can be simplified and the processing time can be shortened as compared with the conventional wet separation method, so that the cost can be reduced. . Furthermore, since lithium can be deposited as a simple substance on the electrode surface by appropriately setting the potential value at the electrode, lithium with high purity can be obtained.

[Fourth embodiment]
In the present embodiment, a step of dissolving a metal element contained in a processing object containing two or more kinds of metal elements in a molten salt, a pair of electrode members is provided in the molten salt in which the metal element is dissolved, and the electrodes A method of producing a metal by molten salt electrolysis comprising a step of precipitating or alloying a specific metal present in a molten salt on one of electrode members by controlling a potential of the member to a predetermined value.

In the present embodiment, the specific metal contained in the object to be treated is generally dissolved in the molten salt, and the molten salt in which the specific metal is dissolved is specified as one electrode (cathode) by molten salt electrolysis. And a process of depositing a metal. The feature of this embodiment is that a specific metal having a high purity is obtained by selectively precipitating a specific metal from the object to be processed by controlling the potential at the electrode to a predetermined value.

First, a process for dissolving a specific metal contained in a processing object in a molten salt will be described.
Examples of the method for dissolving the specific metal contained in the object to be treated in the molten salt include a method for dissolving by a chemical method. Specifically, a specific metal contained in the processing object can be dissolved in the molten salt by crushing the processing object into a granular or powder form, mixing these and a salt, and heating. . Further, the object to be treated may be put into molten salt and dissolved.

別 Another method is an electrochemical method. Specifically, the molten salt was controlled from the processing object by providing a cathode and an anode made of an anode material containing the processing object, and controlling the potential at the anode to a predetermined value. A metal element corresponding to the potential value is dissolved in the molten salt. In molten salt electrolysis, the potential at which an element dissolves has different properties depending on the type of the element. Therefore, a specific metal can be separated from other metals using this property. Thus, a specific metal can be selectively dissolved in the molten salt by controlling the potential at the time of dissolution using the object to be treated as an anode.

In this step, all the metals contained in the treatment object may be dissolved, the specific metal contained in the treatment object and other metals may be dissolved, and further included in the treatment object. It is preferable to dissolve only a specific metal. Although the condition may be that the specific metal contained in the object to be treated and other metals are dissolved, it is preferable to control the potential so that only the specific metal is dissolved as much as possible. That is, in the step of dissolving the specific metal in the molten salt, it is preferable to control the potential at the anode to a predetermined value and selectively dissolve the specific metal element in the molten salt. Thereby, it is possible to reduce the amount of impurities introduced in the subsequent deposition step.

For this purpose, in the step of dissolving the specific metal from the object to be treated in the molten salt, the standard electrode potential of the specific metal or its alloy in the molten salt and the other single metal or its metal The molten salt is preferably selected so that the difference from the standard electrode potential of the alloy is 0.05 V or more. Thereby, the specific metal dissolved in the molten salt and the other metal elements remaining on the anode can be satisfactorily separated. The difference in the standard electrode potential is more preferably 0.1 V or more, and further preferably 0.25 V or more.
The value of the potential controlled at the anode can be calculated by the Nernst equation described later.

In addition, when the said process target object contains 1 or more types of the specific metal used as the objective, 1 type or 2 types or more of specific metals are dissolved in the said molten salt in the said melt | dissolution process.
When only one type of specific metal is included in the object to be treated, the target metal is obtained by performing the precipitation step after dissolving the specific metal as described above. In addition, when two or more kinds of target specific metals are contained in the object to be treated, only one of them is dissolved in the molten salt, followed by the precipitation step, and then the dissolution step again. The remaining types of specific metals may be dissolved in the molten salt. In this case, the object to be treated after the first dissolution step is transferred to a molten salt different from the molten salt used in the dissolution step, and the dissolution step is performed, so that the remaining types of specific metals can be obtained. It may be dissolved.
When two or more types of specific metals contained in the object to be treated are dissolved in the molten salt, one type of the specific metals present in the molten salt is used in the subsequent precipitation step. A desired specific metal can be produced by depositing or alloying the electrode material. In this case, after depositing or alloying one type of specific metal on the electrode material, the electrode material is exchanged to deposit or deposit the remaining specific metal dissolved in the molten salt on the electrode material. What is necessary is just to alloy.

陰極 As the cathode used in the melting step, a material that is easily alloyed with an alkali metal such as Li or Na constituting carbon or a cation in the molten salt is used. For example, aluminum (Al), zinc (Zn), gallium (Ga), cadmium (Cd), indium (In), tin (Sn), antimony (Sb), lead (Pb), bismuth (Bi), or the like is used. Can do.

In order to use the object to be treated containing the specific metal as the anode, for example, the object to be treated may be accommodated in a conductive basket (anode material) made of metal or the like and provided in the molten salt. An opening is provided in the upper part of the basket so that the object to be processed can be inserted into the interior from the opening, and a large number of holes are formed in the side wall and the bottom wall of the basket so that the molten salt can flow into the interior of the basket. You can do that. As a material constituting the cage, any material such as a net-like member formed by knitting a metal wire or a sheet member in which a large number of holes are formed in a sheet-like metal plate can be used. In particular, it is effective to use C, Pt, Mo or the like as the material.
When the object is an oxide or the like and has a high electric resistance, the contact amount with the conductive material is preferably increased. It is effective to use the electrode as an electrode by wrapping it with a metal mesh member or filling the space inside the porous metal body.

The cathode and an anode made of an anode material containing the object to be processed (for example, a metal cage that holds the object to be processed inside) are provided in the molten salt, and the potential at the anode is controlled to a predetermined value. As a result, a specific metal can be dissolved in the molten salt from the object to be treated.

In the subsequent deposition process, a specific metal is deposited on one electrode member (cathode) by providing a pair of electrode members in the molten salt in which the specific metal is dissolved and performing molten salt electrolysis. In this case, a specific metal can be selectively deposited as a metal or alloy on the cathode depending on the magnitude of the potential controlled by molten salt electrolysis.

Also in this precipitation process, similar to the dissolution process, in molten salt electrolysis, the potential that an element is deposited on the cathode as a metal or alloy varies depending on the type of the element, so that a specific metal and other metals can be used. Isolate. Thus, even when a metal other than the specific metal is contained in the molten salt, the specific metal element is selectively deposited on the cathode by controlling the potential of the electrode member to a predetermined value. Can be alloyed. That is, a high purity specific metal can be obtained.

Moreover, when depositing a specific metal, the difference between the dissolution / precipitation potential of the specific metal and the dissolution / precipitation potential of other metals contained in the molten salt is small, and the specific metal is separated from other metals. If this is difficult, the cathode material and the potential may be controlled so that the cathode material and a specific metal are alloyed and deposited. Thereby, a specific metal in the molten salt is precipitated as an alloy, separated from other impurity metals, and then dissolved in another molten salt using, for example, a cathode material alloyed with the specific metal. By performing the precipitation step, a specific metal with high purity can be obtained.

電極 As an electrode member used in the precipitation step, for example, nickel (Ni), molybdenum (Mo), glassy carbon (C), or the like can be used.

In the present embodiment, a specific metal is separated and extracted from the object to be processed by the above two processes. In this embodiment, since the molten salt is used, it is necessary to heat the system so that the temperature of the system in each process is equal to or higher than the melting point of the molten salt.
Further, as will be described later, it is possible to smelt using the completely opposite idea to this process. That is, only the metal element which becomes an impurity is dissolved in the molten salt with the object to be processed as an anode. Also in this case, by controlling the potential at the anode, a phenomenon occurs in which the specific metal remains on the anode and the impurity element dissolves. Thereby, a specific metal is obtained for the anode.

A feature of the above two processes is the use of molten salt. In other words, by utilizing the property of molten salt electrolysis in which the potential of dissolution / precipitation of each element varies depending on the type of molten salt, the dissolution / precipitation potential of a specific metal and the dissolution / precipitation of a target metal other than a specific metal It is possible to select and design the molten salt so that the deposition potential is sufficiently separated from the deposition potential.
Specifically, in the step of precipitating or alloying the specific metal, the standard electrode potential of the specific metal or its alloy in the molten salt and the standard electrode potential of another metal or its alloy It is preferable to select the molten salt so that the difference is 0.05 V or more.
The difference between the standard electrode potential of the specific metal or its alloy in the molten salt and the standard electrode potential of another metal or its alloy is more preferably 0.1 V or more, and 0.25 V or more. More preferably.
Thus, in the step of precipitating or alloying the specific metal, the potential of the electrode member is controlled to a predetermined value, and the specific metal element in the molten salt is selectively precipitated or alloyed. It is preferable.

The deposition potential of a specific metal deposited on the cathode can be calculated by electrochemical calculation. Specifically, it is calculated using the Nernst equation.
For example, the potential at which Mo is precipitated from a molten salt in which molybdenum is dissolved as a specific metal to form tetravalent molybdenum (Mo) ions (hereinafter referred to as Mo (IV)) can be obtained by the following equation. it can.

E _Mo = E ⁰ _Mo + RT / 3F · ln (a _{Mo (IV)} / a _{Mo (0)} ) (1) In the above formula (1), E ⁰ _Mo is a standard potential, R Is the gas constant, T is the absolute temperature, F is the Faraday number, a _{Mo (IV)} is the activity of Mo (IV) ions, and _{aMo (0)} is the activity of Mo alone.

When the above equation (1) is rewritten in consideration of the activity coefficient γ _{Mo (IV)} , since a _{Mo (0)} = 1, the following equation is obtained.
E _Mo = E ⁰ _Mo + RT / 3F · lna _{Mo (IV)}
^{_{= E 0 Mo + RT / 3F}} · ln (γ Mo (IV) · C Mo (IV)) ··· formula _{^{(2) E Mo = E 0}} 'Mo + RT / 3F · lnC Mo (IV) ··· Formula (3)
In the above formula (3), C _{Mo (IV)} is the concentration of tetravalent Mo ions, E ^{0 ′} _Mo is the formula electrode potential (here, E ⁰ _Mo + RT / 3F · lnγ _{Mo (IV))} Means equal).

Similarly, the precipitation potential can be obtained for each type of molten salt with respect to all precipitates by the above formula.
The same calculation can be performed when molybdenum is precipitated as an alloy.
In the process of depositing or alloying molybdenum on the cathode, the precipitation potential of this molybdenum alone or molybdenum alloy is observed, so that a sufficient potential difference can be obtained from the precipitation potential of other metals alone or their alloys. The salt or cathode material is selected, and it is determined whether to precipitate as molybdenum alone or as a molybdenum alloy.
Since the voltage and current in operation vary depending on the size and positional relationship of the electrodes, after determining the reference value by setting the conditions, determine it at each step based on the potential value and the order obtained by the above method. To do.

As described above, in the method for producing a specific metal by molten salt electrolysis according to the present embodiment, the specific metal can be dissolved and deposited electrochemically by controlling the potential value. For this reason, a process can be simplified compared with the case of repeating processes, such as melt | dissolution and extraction using an acid etc. like the conventional wet process, and a specific metal can be selectively isolate | separated and collect | recovered. Furthermore, it is not necessary to adjust the specific gravity of the molten salt, and by selecting a low-temperature molten salt that can treat a specific metal in a solid state, a simple apparatus configuration can be obtained. In addition, the operation mode can be simplified. For this reason, it is possible to increase the efficiency of the process and reduce the cost.

In addition, as described above, it is possible to smelt a specific metal based on a concept that is completely opposite to the concept of depositing or alloying a specific metal on the cathode.
That is, the method for producing a metal by molten salt electrolysis according to the present embodiment is a method for producing a specific metal by molten salt electrolysis from a treatment object containing two or more kinds of metal elements, and a cathode in the molten salt, An anode made of an anode material containing the object to be treated is provided, and the potential at the anode is controlled to a predetermined value, whereby the metal element corresponding to the potential is dissolved in the molten salt from the object to be treated. The metal is left on the anode.

In this manufacturing method, an anode material containing the object to be treated is used as an anode, and only a metal element other than a specific metal, that is, an impurity, is dissolved in a molten salt, thereby leaving a specific metal on the anode. is there. Also in this case, by controlling the potential at the anode, it is possible to generate a phenomenon in which the specific metal to be smelted remains on the anode and the impurity element dissolves in the molten salt. Thereby, the specific metal smelted by the anode is obtained.

Also in this method, in the step of dissolving the metal element from the object to be treated in the molten salt, the standard electrode potential of the specific metal or its alloy in the molten salt and the other metal simple or its alloy The molten salt is preferably selected so that the difference from the standard electrode potential is 0.05 V or more. Thereby, a specific metal and another metal can be isolate | separated favorably, and only a specific metal can remain in an anode. The difference in standard electrode potential is more preferably 0.1 V or more, and further preferably 0.25 V or more.
The value of the potential controlled at the anode can be calculated using the Nernst equation as described above.

において In the method for producing a metal by molten salt electrolysis according to this embodiment, the object to be treated containing two or more kinds of metal elements is not limited as long as it is a metal material containing a target specific metal. For example, Mn, Co, Sb, etc. from recovered battery materials, Nb, etc. from metal superconducting materials, Bi, Sr etc. from oxide superconducting materials, V from ferrovanadium, and Mo-Cu heat spreaders Can obtain Mo or the like, and Ge or the like from the optical fiber material.

The present embodiment can be preferably applied to the case where the object to be treated is a metal material containing a transition metal or a rare earth metal. The transition metal is not particularly limited as long as it is an element included in Group 3 (Group IIIA) to Group 11 (Group IB) of the periodic table. The present embodiment is also suitably used when the object to be treated includes one or more metals selected from the group consisting of V, Nb, Mo, Ti, Ta, Zr, and Hf as transition metals. Can do.
The present embodiment is also suitably used when the metal contained in the processing object is either Sr or Ba, or both. Furthermore, the present invention is also suitably used when the object to be processed contains one or more metals selected from the group consisting of Zn, Cd, Ga, In, Ge, Sn, Pb, Sb, and Bi.

By making the specific metal to be deposited or alloyed into a transition metal or a rare earth metal, a transition metal or a rare earth metal can be obtained by the method for producing a metal by molten salt electrolysis according to this embodiment. The transition metal is not particularly limited as long as it is an element included in Group 3 (Group IIIA) to Group 11 (Group IB) of the periodic table.
Similarly, the specific metal to be deposited or alloyed is V, Nb, Mo, Ti, Ta, Zr or Hf, Sr or Ba, or Zn, Cd, Ga, In, Ge, Sn. , Pb, Sb or Bi, these metals can be obtained.
As described above, in the melting step, one or more kinds of these metals contained in the object to be treated are dissolved in a molten salt, and a specific metal is deposited or alloyed on the electrode member sequentially from the molten salt. it can.

The processing object is preferably granular or powdery. By making the object to be processed granular or powdery, the surface area can be increased and the processing efficiency can be increased.
Furthermore, it can be used as an anode (anode) by compacting the object to be processed in a granular or powder form. In this case, it is desirable that there is a space where the molten salt can easily enter between the particles.

As the molten salt, a chloride-based molten salt or a fluoride-based molten salt can be used. A molten salt obtained by mixing a chloride-based molten salt and a fluoride-based molten salt can also be used.
As the chloride-based molten salt, for example, KCl, NaCl, CaCl ₂ , LiCl, RbCl, CsCl, SrCl ₂ , BaCl ₂ , MgCl _{2 and the} like can be used. As the fluoride-based molten salt, for example, LiF, NaF, KF, RbF, CsF, MgF ₂ , CaF ₂ , SrF ₂ , and BaF ₂ can be used. It is preferable to use a chloride-based molten salt from the viewpoint of efficiency, and KCl, NaCl, and CaCl ₂ are preferably used from the viewpoint of being inexpensive and easily available.
These molten salts can be used as a molten salt having an arbitrary composition by combining a plurality of types of molten salts. For example, a molten salt having a composition such as KCl—CaCl ₂ , LiCl—KCl, or NaCl—KCl can be used. it can.

In the method for producing metal by molten salt electrolysis according to this embodiment, the following apparatus can be preferably used. That is, a container holding a molten salt therein, a cathode immersed in a molten salt held inside the container, and two or more kinds of metal elements immersed in a molten salt held inside the container An anode holding a conductive object to be processed inside, the anode is configured such that the molten salt can flow between the inside and the outside, and the potential at the cathode and the anode is set to a predetermined value. It is preferable that a control unit for controlling the potential is provided, and the control unit is capable of changing the value of the potential. Moreover, the apparatus used for the method for producing a metal by molten salt electrolysis according to the present embodiment is immersed in a molten salt in which a specific metal is dissolved and a molten salt held in the container. It is preferable that a cathode and an anode are provided, and a controller that controls a potential at the cathode and the anode to a predetermined value is provided, and the controller can change the value of the potential.

The apparatus will be described with reference to FIGS. The apparatus shown in FIG. 18 includes a container 1 that holds a molten salt inside, a molten salt 2 that is held inside the container 1, and a basket 4 that holds a processing object 3 containing two or more kinds of metal elements inside. An electrode 6, a heater 10 for heating the molten salt 2, and a control unit 9 electrically connected to the cage 4 and the electrode 6 by a conductive wire 5.
The control unit 9 can control the potential at this electrode to a predetermined value with the cage 4 as one electrode (anode) and the electrode 6 as the other electrode (cathode). Further, the control unit 9 can change the value of the potential to be controlled. The heater 10 is arranged so as to surround the container 1 in an annular shape. The electrode 6 can be made of any material, and for example, carbon can be used. The shape of the container 1 may be a circular shape on the bottom or a polygonal shape. Further, as the basket 4, the aforementioned basket can be used.

In the cage 4 and the electrode 6, the potential is controlled by the control unit 9 so as to have a predetermined potential value. As a result, the specific metal is dissolved in the molten salt 2 from the processing object 3.
Then, after the specific metal is sufficiently dissolved from the processing object 3, the cage 4 and the electrode 6 are taken out, and another electrode 7 (cathode) and electrode 8 (anode) are put into the molten salt 2. The

electrodes

7 and 8 are connected to the control unit 9 through the conductive wires 5, respectively. Then, the control unit 9 controls the potentials at the

electrodes

7 and 8 to a predetermined value. At this time, the potential to be controlled is adjusted so that the potential of the electrode 7 becomes the deposition potential of the specific metal. As a result, the specific metal dissolved in the molten salt 2 is deposited on the surface of the electrode 7 (cathode). As a material for the

electrodes

7 and 8, for example, glassy carbon (C) can be used.

It should be noted that the heating temperature of the molten salt 2 by the heater 10 can be set to 800 ° C., for example, in any of the treatments in the apparatus shown in FIGS. In this way, a specific metal can be deposited as a simple substance on the surface of the electrode 7.

Note that the potentials at the

electrodes

7 and 8 may be adjusted so that an alloy of a specific metal and a cathode material is deposited on the surface of the electrode 7 (cathode). In this case, the above-described melting step and precipitation step may be performed using the alloyed electrode 7. That is, a new apparatus as shown in FIG. 18 may be prepared, and the electrode 7 alloyed with a specific metal may be used in place of the processing object 3 described above.

When the metal manufacturing method according to the present embodiment is performed using the apparatus as shown in FIGS. 18 and 19, for example, it can be performed as follows. Hereinafter, vanadium, molybdenum, strontium, and germanium will be described as examples.

(vanadium)
For example, in order to obtain vanadium by the metal production method of the present embodiment, first, 1 kg of ferrovanadium is prepared as the object to be processed 3 and NaCl—KCl is prepared as the molten salt 2. As ferrovanadium, for example, vanadium (V) is contained at 75 wt% and iron (Fe) is contained at 25 wt%. The ferrovanadium is crushed and placed inside the basket 4. The amount of the molten salt 2 is about 15 liters.
Then, the above-described dissolution process may be performed using an electrode made of carbon as the electrode 6, and then the deposition process may be performed using electrodes made of glassy carbon as the

electrodes

7 and 8.

(molybdenum)
In order to obtain molybdenum by the metal manufacturing method of the present embodiment, first, 1 kg of Mo—Cu heat spreader is prepared as the object to be processed 3, and LiCl—KCl is prepared as the molten salt 2. The Mo—Cu heat spreader includes, for example, 50 wt% molybdenum (Mo) and 50 wt% copper (Cu). The heat spreader is crushed and placed inside the basket 4. The amount of the molten salt 2 is about 5 liters.
Then, the above-described dissolution process is performed using an electrode made of carbon as the electrode 6, and then the deposition process is performed using electrodes made of glassy carbon as the

electrodes

7 and 8.

(strontium)
In order to obtain molybdenum by the metal manufacturing method of the present embodiment, first, 1 kg of an oxide-based superconducting material is prepared as the object to be processed 3 and LiF—CaF ₂ is prepared as the molten salt 2. As the oxide-based superconducting material, for example, 17 wt% of strontium (Sr) and 8 wt% of calcium (Ca) are contained. The oxide superconducting material is pulverized and placed inside the cage 4. The amount of the molten salt 2 is about 4 liters.
Then, the above-described dissolution process is performed using an electrode made of carbon as the electrode 6, and then the deposition process is performed using electrodes made of glassy carbon as the

electrodes

7 and 8.

(germanium)
In order to obtain germanium by the metal production method of the present embodiment, first, 1 kg of an optical fiber material is prepared as the object to be processed 3 and LiF—CaF ₂ is prepared as the molten salt 2. As an optical fiber material, for example, germanium (Ge) is contained at 3 wt%. The optical fiber material is crushed and placed inside the basket 4. The amount of the molten salt 2 is about 4 liters.
Then, the above-described dissolution process is performed using an electrode made of carbon as the electrode 6, and then the deposition process is performed using electrodes made of glassy carbon as the

electrodes

7 and 8.

As described above, vanadium, molybdenum, strontium, and germanium can be obtained by using ferrovanadium, a Mo—Cu heat spreader, an oxide superconducting material, and an optical fiber material as the processing object 3, respectively. From the viewpoint of improving the processing efficiency, the ferrovanadium, the Mo—Cu heat spreader, the oxide superconducting material, and the optical fiber material used as the processing object 3 are preferably crushed as small as possible. It is preferable to pulverize into a granule so that the maximum value is 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less.
According to the method for producing a metal by molten salt electrolysis according to the present embodiment, the apparatus configuration can be simplified and the processing time can be shortened as compared with the conventional recovery method and the like, so that the cost can be reduced. Furthermore, since a specific metal can be deposited as a simple substance on the electrode surface by appropriately setting the potential at the electrode, a highly pure metal can be obtained.
Note that the potential for depositing each vanadium, vanadium alloy, molybdenum, molybdenum alloy, strontium, strontium alloy, germanium, or germanium alloy can be calculated by the above-described calculation.

As described above, the first to fourth embodiments have been described separately. For example, in order to obtain the tungsten, lithium, transition metal, and rare earth metal according to the second to fourth embodiments, the method according to another embodiment. Can be employed in whole or in part.

[First Embodiment (Example)]
Nd, Dy, and Pr were produced by molten salt electrolysis from ores containing rare earth metals.
(sample)
Xenotime ore was used as the ore to be treated. The xenotime ore was pulverized by means of a crusher or a ball mill so that the particle size became about 2 mm. Then, the crushed sample (xenotime ore) was wrapped in a mesh (50 mesh) made of molybdenum (Mo).
As shown in FIG. 14, the sample powder held inside the net was used as an anode (anode electrode).

(Experiment contents)
A molten salt having a eutectic composition of LiF—NaF—KF was used as the molten salt, and the mixture was heated to 700 ° C. and completely dissolved. And the anode electrode and cathode electrode which were mentioned above were wired and immersed in the said molten salt. Glassy carbon was used as the cathode electrode material.

Dissolution process:
Thus, the anode electrode was kept at a predetermined potential with the anode electrode and the cathode electrode immersed in the molten salt. After about 4 hours, a sample was taken from the molten salt, and the sample was subjected to composition analysis by ICP-AES.

Electrolysis process:
After the dissolution step, a cathode electrode made of Ni and an anode electrode made of glassy carbon were immersed in the molten salt, and the potential of the cathode electrode was maintained at a predetermined potential. Specifically, the LiF—NaF—KF molten salt was maintained at a potential such that a Dy—Ni alloy was formed. And after predetermined time progress, the surface state of the cathode electrode was observed.

(result)
About dissolution process:
The anode current observed in the dissolution process showed a change with time as shown in FIG.
In addition, the horizontal axis of FIG. 15 shows time (unit: minute), and a vertical axis | shaft shows the electric current value (unit: mA) of anode current. As shown in FIG. 15, the current value decreased with time. Moreover, the time rate of change of the current value was highest at the start of measurement (at the start of energization), and thereafter the rate of change gradually decreased.

As a result of analyzing the composition of the sample collected from the molten salt by ICP-AES, it was confirmed that Nd and Dy were dissolved in the molten salt.

About the electrolysis process:
The result of having observed the cross section about the surface layer of the cathode electrode with the scanning electron microscope (SEM) is shown in FIG. 16 and FIG. As shown in FIGS. 16 and 17, the Dy—Ni alloy 32 was deposited on the surface of the electrode main body 31 made of Ni constituting the cathode electrode. This Dy—Ni alloy 32 is considered to be that Dy present in the molten salt reacted with Ni constituting the cathode electrode and deposited on the surface of the cathode electrode. Thus, Dy contained in the xenotime ore can be separated and extracted from the ore in the form of a Dy-Ni alloy.

Note that FIG. 16 shows a reflected electron image by SEM, and FIG. 17 shows the distribution of Dy atoms by X-ray analysis of the region shown in FIG. As shown in FIG. 17, Dy is hardly detected in the region 33 corresponding to the electrode main body 31, but Dy is detected in the region 34 corresponding to the Dy—Ni alloy 32.

[Second Embodiment (Example)]
Tungsten was manufactured by molten salt electrolysis using a cemented carbide tool as a metal material containing tungsten.
(sample)
As the cemented carbide tool to be treated, a cutting tool having 90 wt% tungsten carbide and 10 wt% cobalt as a binder was used. The cutting tool was pulverized by means of a bead mill or an attritor so that the particle size was about 2 mm. The crushed sample (cutting tool) was wrapped in a mesh (50 mesh) made of molybdenum (Mo). As shown in FIG. 14, the sample powder (object to be processed) held inside the Mo net was used as the anode (anode electrode).

(Experiment contents)
A molten salt having a eutectic composition of NaCl-KCl was used as the molten salt, and it was completely melted by heating to 700 ° C. And the anode electrode and cathode electrode which were mentioned above were wired and immersed in the said molten salt. Glassy carbon was used as the cathode electrode material.

Dissolution process:
Thus, the anode electrode was kept at a predetermined potential with the anode electrode and the cathode electrode immersed in the molten salt. After a predetermined time, a sample was taken from the molten salt, and the sample was subjected to composition analysis by ICP-AES.

Electrolysis process:
After the dissolution step, a cathode electrode made of glassy carbon and an anode electrode made of glassy carbon were immersed in the molten salt, and the potential of the cathode electrode was maintained at a predetermined potential. Specifically, the potential was maintained such that tungsten precipitated in the NaCl-KCl molten salt. And after predetermined time progress, the surface state of the cathode electrode was observed.

(result)
About dissolution process:
The anodic current observed in the dissolution process showed the same change with time as in the first embodiment (Example) (FIG. 15). In addition, the horizontal axis of FIG. 15 shows time (unit: minute), and a vertical axis | shaft shows the electric current value (unit: mA) of anode current. As shown in FIG. 15, the current value decreased with time. Moreover, the time rate of change of the current value was highest at the start of measurement (at the start of energization), and thereafter the rate of change gradually decreased.

As a result of analyzing the composition of the sample collected from the molten salt by ICP-AES, it was confirmed that tungsten was dissolved in the molten salt.

About the electrolysis (deposition) process:
As a result of observing the cross section of the surface layer of the cathode electrode with a scanning electron microscope (SEM), tungsten was deposited on the surface of the electrode main body portion made of glassy carbon constituting the cathode electrode.
Thus, the tungsten contained in the cemented carbide cutting tool containing tungsten could be obtained with high purity.

[Third Embodiment (Example)]
Lithium was produced by molten salt electrolysis using a commercially available lithium ion secondary battery as a treatment object containing lithium.
(sample)
Commercially available lithium ion secondary battery (lithium cobaltate for positive electrode, graphite for negative electrode, lithium cobaltate content: mass%)
(Separation of lithium battery positive electrode material)
The lithium ion secondary battery was immersed in an electrolytic solution (5% NaCl) and discharged to 0.1 mV. Thereafter, the positive electrode material was taken out by manual decomposition and pulverized using a cutter mill to obtain a positive electrode material powder having an average particle diameter of 0.1 mm. The composition is shown in Table 1. As a result of analysis, it was confirmed that the separated powder was lithium cobaltate.

The powder was wrapped in a mesh (200 mesh) made of molybdenum (Mo). As shown in FIG. 14, the sample powder held inside the Mo net was used as an anode (anode electrode).

(Preparation of electrolyzer)
A molten salt having a eutectic composition of NaCl-KCl was used as the molten salt, and it was completely melted by heating to 700 ° C. And the anode electrode and cathode electrode which were mentioned above were wired and immersed in the said molten salt. Carbon was used as a material for the cathode (cathode electrode).

(Electrolytic dissolution process)
Thus, the anode electrode was kept at a predetermined potential with the anode electrode and the cathode electrode immersed in the molten salt. After a predetermined time, a sample was taken from the molten salt, and the sample was subjected to composition analysis by ICP-AES.
The anodic current observed in the dissolution process showed the same change with time as in the first embodiment (Example) (FIG. 15). In addition, the horizontal axis of FIG. 15 shows time (unit: minute), and a vertical axis | shaft shows the electric current value (unit: mA) of anode current. As shown in FIG. 15, the current value decreased with time. Moreover, the time rate of change of the current value was highest at the start of measurement (at the start of energization), and thereafter the rate of change gradually decreased.
As a result of analyzing the composition of the sample collected from the molten salt by ICP-AES, it was confirmed that lithium was dissolved in the molten salt.

(Electrolytic deposition process)
After the dissolution step, a cathode electrode made of glassy carbon and an anode electrode made of glassy carbon were immersed in the molten salt, and the potential of the cathode electrode was maintained at a predetermined potential. Specifically, the potential was maintained such that lithium was precipitated in the NaCl-KCl molten salt. After a predetermined time, the cross section of the surface layer of the cathode electrode was observed with a scanning electron microscope (SEM).
As a result of the observation, lithium was deposited on the surface of the electrode body portion made of glassy carbon constituting the cathode electrode.
Thus, the lithium contained in the positive electrode material containing lithium could be recovered.

[Fourth Embodiment (Example) -1]
Using ferrovanadium as a metal material containing vanadium, vanadium was produced by molten salt electrolysis.
(sample)
Ferrovanadium having 75 wt% vanadium and 25 wt% iron was used as the object to be treated. The ferrovanadium was pulverized by means of a bead mill or an attritor so that the particle size was about 2 mm. The ground sample (ferrovanadium) was wrapped in a mesh (50 mesh) made of molybdenum (Mo). As shown in FIG. 14, the sample powder (processing object) held inside the Mo net was used as an anode (anode electrode).

(Experiment contents)
A molten salt having a eutectic composition of NaCl—KCl was used as the molten salt, and the mixture was heated to 700 ° C. and completely melted. And the anode electrode and cathode electrode which were mentioned above were wired and immersed in the said molten salt. Glassy carbon was used as the cathode electrode material.

Dissolution process:
Thus, the anode electrode was kept at a predetermined potential with the anode electrode and the cathode electrode immersed in the molten salt. The potential at this time was such that iron was not dissolved but only vanadium was selectively dissolved. After a predetermined time, a sample was taken from the molten salt, and the sample was subjected to composition analysis by ICP-AES.

Electrolysis process:
After the dissolution step, a cathode electrode made of glassy carbon and an anode electrode made of glassy carbon were immersed in the molten salt, and the potential of the cathode electrode was maintained at a predetermined potential. Specifically, the potential was maintained such that vanadium was precipitated in the NaCl—KCl molten salt. And after predetermined time progress, the surface state of the cathode electrode was observed.

(result)
About dissolution process:
The anodic current observed in the dissolution process showed the same change with time as in the first embodiment (Example) (FIG. 15). In addition, the horizontal axis of FIG. 15 shows time (unit: minute), and a vertical axis | shaft shows the electric current value of anode current. As shown in FIG. 15, the current value decreased with time. Moreover, the time rate of change of the current value was highest at the start of measurement (at the start of energization), and thereafter the rate of change gradually decreased.

As a result of analyzing the composition of the sample collected from the molten salt by ICP-AES, it was confirmed that vanadium was dissolved in the molten salt.

About the electrolysis (deposition) process:
As a result of observing the cross section of the surface layer of the cathode electrode with a scanning electron microscope (SEM), vanadium was deposited on the surface of the electrode main body portion made of glassy carbon constituting the cathode electrode.
Thus, vanadium contained in ferrovanadium containing vanadium could be obtained with high purity.

[Fourth Embodiment (Example) -2]
Molybdenum was produced by molten salt electrolysis using a Mo—Cu heat spreader as a metal material containing molybdenum.
(sample)
As the Mo—Cu heat spreader to be processed, a heat spreader having 50 wt% molybdenum and 50 wt% copper was used. The heat spreader was pulverized by means of a bead mill or an attritor so that the particle size became about 2 mm. The ground sample (heat spreader) was wrapped with a platinum (Pt) mesh (50 mesh). The sample powder (object to be treated) held inside the Pt net was used as the anode (anode electrode).

(Experiment contents)
A molten salt having a eutectic composition of LiCl—KCl was used as the molten salt and heated to 450 ° C. to be completely melted. And the anode electrode and cathode electrode which were mentioned above were wired and immersed in the said molten salt. Glassy carbon was used as the cathode electrode material.

Dissolution process:
Thus, the anode electrode was kept at a predetermined potential with the anode electrode and the cathode electrode immersed in the molten salt. The potential at this time was such that copper was not dissolved but only molybdenum was selectively dissolved. After a predetermined time, a sample was taken from the molten salt, and the sample was subjected to composition analysis by ICP-AES.

Electrolysis process:
After the dissolution step, a cathode electrode made of glassy carbon and an anode electrode made of glassy carbon were immersed in the molten salt, and the potential of the cathode electrode was maintained at a predetermined potential. Specifically, the potential was maintained such that molybdenum precipitated in the LiCl—KCl molten salt. And after predetermined time progress, the surface state of the cathode electrode was observed.

(result)
About dissolution process:
As in the case of vanadium, the current value of the anode current observed in the melting process decreased with time. Moreover, the time rate of change of the current value was highest at the start of measurement (at the start of energization), and thereafter the rate of change gradually decreased.

As a result of analyzing the composition of the sample collected from the molten salt by ICP-AES, it was confirmed that molybdenum was dissolved in the molten salt.

About the electrolysis (deposition) process:
As a result of observing the cross section of the surface layer of the cathode electrode with a scanning electron microscope (SEM), molybdenum was deposited on the surface of the electrode main body portion made of glassy carbon constituting the cathode electrode.
Thus, the molybdenum contained in the heat spreader containing molybdenum could be obtained with high purity.

[Fourth Embodiment (Example) -3]
Strontium was produced by molten salt electrolysis using an oxide-based superconducting material as a metal material containing strontium.
(sample)
As the oxide superconducting material to be treated, an oxide superconducting material having 17 wt% strontium and 8 wt% calcium was used. The oxide superconducting material was pulverized by means of a bead mill or an attritor so that the particle size was about 2 mm. The pulverized sample (oxide-based superconducting material) was wrapped with a platinum (Pt) mesh (50 mesh). The sample powder (object to be treated) held inside the Pt net was used as the anode (anode electrode).

(Experiment contents)
A molten salt having a eutectic composition of LiF—CaF ₂ was used as the molten salt and heated to 850 ° C. to be completely melted. And the anode electrode and cathode electrode which were mentioned above were wired and immersed in the said molten salt. Glassy carbon was used as the cathode electrode material.

Dissolution process:
Thus, the anode electrode was kept at a predetermined potential with the anode electrode and the cathode electrode immersed in the molten salt. In this case, the potential was set such that only strontium and calcium were selectively dissolved, and other contained elements were not dissolved. After a predetermined time, a sample was taken from the molten salt, and the sample was subjected to composition analysis by ICP-AES.

Electrolysis process:
After the dissolution step, a cathode electrode made of glassy carbon and an anode electrode made of glassy carbon were immersed in the molten salt, and the potential of the cathode electrode was maintained at a predetermined potential. Specifically, the potential was maintained such that strontium was precipitated in the LiF—CaF ₂ molten salt. And after predetermined time progress, the surface state of the cathode electrode was observed.

As a result of analyzing the composition of the sample collected from the molten salt by ICP-AES, it was confirmed that strontium was dissolved in the molten salt.

About the electrolysis (deposition) process:
As a result of observing the cross section of the surface layer of the cathode electrode with a scanning electron microscope (SEM), strontium was adhered to the surface of the electrode main body portion made of glassy carbon constituting the cathode electrode. Since the melting point of strontium is 768 ° C., it is a liquid. When the amount of adhesion to the electrode body increases, it floats due to the difference in specific gravity with the molten salt. Therefore, a jig for collecting floating strontium was installed on the upper side of the electrode.
Thus, strontium contained in the oxide-based superconducting material containing strontium could be obtained with high purity.

[Fourth Embodiment (Example) -4]
Germanium was produced by molten salt electrolysis using an optical fiber material as a metal material containing germanium.
(sample)
As an optical fiber material to be processed, an optical fiber material having 3 wt% germanium was used. The optical fiber material was pulverized by means of a bead mill or an attritor so that the particle size was about 2 mm. The crushed sample (optical fiber material) was wrapped with a platinum (Pt) mesh (50 mesh). The sample powder (object to be treated) held inside the Pt net was used as the anode (anode electrode).

Dissolution process:
Thus, the anode electrode was kept at a predetermined potential with the anode electrode and the cathode electrode immersed in the molten salt. In this case, the potential was such that only germanium was selectively dissolved and other contained elements were not dissolved. After a predetermined time, a sample was taken from the molten salt, and the sample was subjected to composition analysis by ICP-AES.

Electrolysis process:
After the dissolution step, a cathode electrode made of glassy carbon and an anode electrode made of glassy carbon were immersed in the molten salt, and the potential of the cathode electrode was maintained at a predetermined potential. Specifically, the potential was maintained such that germanium was precipitated in the LiF—CaF ₂ molten salt. And after predetermined time progress, the surface state of the cathode electrode was observed.

(result)
About dissolution process:
The anodic current observed in the dissolution process decreased with time, as in the case of vanadium. Moreover, the time rate of change of the current value was highest at the start of measurement (at the start of energization), and thereafter the rate of change gradually decreased.

As a result of analyzing the composition of the sample collected from the molten salt by ICP-AES, it was confirmed that germanium was dissolved in the molten salt.

About the electrolysis (deposition) process:
As a result of observing the cross section of the surface layer of the cathode electrode with a scanning electron microscope (SEM), germanium was deposited on the surface of the electrode main body portion made of glassy carbon constituting the cathode electrode.
Thus, germanium contained in the optical fiber material containing germanium could be obtained with high purity.

As mentioned above, the embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The present invention can be suitably used in a method for obtaining a high purity specific metal from a processing object containing two or more kinds of metal elements. Or this invention can be utilized suitably for the method of obtaining arbitrary metals from an ore or a rough metal lump. Or it can utilize suitably for the method of obtaining highly purified tungsten from the process target object containing at least any one of tungsten and lithium.

1 container, 2 molten salt, 3

processing object

4, 24 car, 5 conductive wire, 6-8,15,27 electrode, 9 control unit, 10 a heater, 11 DyNi ₂ film, 12 Pr film, 13 Nd film, 16 Dy film, 25 electrode material, 26 alloy, 31 electrode body, 32 Dy-Ni alloy, 33, 34 region

Claims

Dissolving a metal element contained in a processing object containing two or more kinds of metal elements in a molten salt;
By providing a pair of electrode members in the molten salt in which the metal element is dissolved and controlling the potential at the electrode member to a predetermined value, a specific metal present in the molten salt is deposited on one of the electrode members or Alloying step,
A method for producing a metal by molten salt electrolysis, comprising:
The method for producing a metal by molten salt electrolysis according to claim 1, wherein the object to be treated is ore or a crude metal block obtained from the ore.
A method for producing tungsten, comprising:
The metal element contained in the processing object is tungsten,
In the step of dissolving the metal element in the molten salt from the treatment object, tungsten is dissolved from the treatment object,
In the step of precipitating or alloying the specific metal, a pair of electrode members is provided in the molten salt in which the tungsten is dissolved, and the potential of the electrode member is controlled to a predetermined value, whereby one of the electrode members has a molten salt. The method for producing a metal by molten salt electrolysis according to claim 1 or 2, wherein tungsten existing therein is precipitated.
The method for producing tungsten by molten salt electrolysis according to claim 3, wherein the object to be treated is a metal material containing tungsten.
The method for producing tungsten by molten salt electrolysis according to claim 3 or 4, wherein the object to be treated is a metal material containing tungsten and a transition metal.
The method for producing a metal by molten salt electrolysis according to any one of claims 3 to 6, wherein the object to be treated is a cemented carbide product.
A method for producing lithium, comprising:
The metal element contained in the processing object is lithium,
In the step of dissolving the metal element in the molten salt from the treatment object, lithium is dissolved from the treatment object,
In the step of precipitating or alloying the specific metal, a pair of electrode members is provided in the molten salt in which the lithium is dissolved, and the potential of the electrode member is controlled to a predetermined value, whereby one of the electrode members has a molten salt. The method for producing a metal by molten salt electrolysis according to claim 1 or 2, wherein lithium existing therein is deposited.
The method for producing a metal by molten salt electrolysis according to claim 7, wherein the object to be treated is a material containing lithium and a transition metal.
The method for producing a metal by molten salt electrolysis according to claim 7 or 8, wherein the object to be treated is a battery electrode material containing lithium.
The method for producing a metal by molten salt electrolysis according to claim 1 or 2, wherein the object to be treated contains a transition metal or a rare earth metal.
3. The molten salt electrolysis according to claim 1, wherein the object to be treated includes one or more kinds of metals selected from the group consisting of V, Nb, Mo, Ti, Ta, Zr, and Hf. Metal manufacturing method.
The method for producing a metal by molten salt electrolysis according to claim 1 or 2, wherein the object to be treated contains Sr and / or Ba.
The said process target object contains 1 or more types of metals chosen from the group which consists of Zn, Cd, Ga, In, Ge, Sn, Pb, Sb, and Bi, The Claim 1 or 2 characterized by the above-mentioned. A method for producing a metal by molten salt electrolysis.
In the step of depositing or alloying the specific metal, the difference between the standard electrode potential of the specific metal or its alloy in the molten salt and the standard electrode potential of another metal or its alloy is 0.05 V. The method for producing a metal by molten salt electrolysis according to any one of claims 1 to 13, wherein the molten salt is selected so as to achieve the above.
In the step of depositing or alloying the specific metal, the potential of the electrode member is controlled to a predetermined value, and the specific metal element in the molten salt is selectively precipitated or alloyed. The method for producing a metal by molten salt electrolysis according to any one of claims 1 to 14.
In the step of dissolving the metal element contained in the treatment object in the molten salt,
The method for producing a metal by molten salt electrolysis according to any one of claims 1 to 15, wherein the metal is dissolved in the molten salt by a chemical method.
In the step of dissolving the metal element contained in the treatment object in the molten salt,
The molten salt is provided with a cathode and an anode made of an anode material containing the object to be processed, and a metal corresponding to the potential controlled from the object to be processed by controlling the potential at the anode to a predetermined value. The method for producing a metal by molten salt electrolysis according to any one of claims 1 to 16, wherein the element is dissolved in the molten salt.
In the step of dissolving the metal element contained in the object to be treated in the molten salt, the standard electrode potential of the specific metal alone or its alloy in the molten salt and the standard electrode potential of another metal alone or its alloy The method for producing a metal by molten salt electrolysis according to claim 17, wherein the molten salt is selected so that a difference from the difference is 0.05 V or more.
In the step of dissolving the metal element contained in the object to be treated in the molten salt, the potential at the anode is controlled to a predetermined value, and the specific metal element is selectively dissolved in the molten salt, The method for producing a metal by molten salt electrolysis according to claim 17 or 18.
20. The step of dissolving the metal element contained in the object to be treated in the molten salt, wherein one or more kinds of the specific metal are dissolved in the molten salt. A method for producing a metal by molten salt electrolysis according to claim 1.
The method for producing a metal by molten salt electrolysis according to any one of claims 1 to 6, 10, 11, and 14 to 20, wherein the specific metal to be deposited or alloyed is a transition metal.
The method for producing a metal by molten salt electrolysis according to any one of claims 1, 2, 10, and 14 to 20, wherein the specific metal to be deposited or alloyed is a rare earth metal.
The specific metal to be precipitated or alloyed is V, Nb, Mo, Ti, Ta, Zr, or Hf, according to any one of claims 1, 2, 10, 11, 14 to 20 A method for producing a metal by molten salt electrolysis.
The method for producing a metal by molten salt electrolysis according to any one of claims 1, 2, 12, and 14 to 20, wherein the specific metal to be deposited or alloyed is Sr or Ba.
The specific metal to be deposited or alloyed is Zn, Cd, Ga, In, Ge, Sn, Pb, Sb, or Bi, according to any one of claims 1, 2, 13 to 20, A method for producing a metal by molten salt electrolysis.
The method for producing a metal by molten salt electrolysis according to any one of claims 1 to 25, wherein a molten salt of chloride or fluoride is used as the molten salt.
The method for producing a metal by molten salt electrolysis according to any one of claims 1 to 26, wherein a molten salt obtained by mixing a chloride-based molten salt and a fluoride-based molten salt is used as the molten salt.
The method for producing a metal by molten salt electrolysis according to any one of claims 1 to 27, wherein the object to be treated is granular or powder.
29. The method for producing a metal by molten salt electrolysis according to claim 28, wherein the granular or powdery object to be treated is pressed into the anode.
A method for producing a specific metal from a processing object containing two or more kinds of metal elements by molten salt electrolysis,
By providing a cathode and an anode made of an anode material containing the object to be processed in the molten salt, and controlling the potential at the anode to a predetermined value, a metal element corresponding to the potential controlled from the object to be processed is obtained. A method for producing a metal by molten salt electrolysis, wherein a specific metal is left on the anode by dissolving in a molten salt.
The method for producing a metal by molten salt electrolysis according to claim 30, wherein the object to be treated is ore or a crude metal lump obtained from the ore.
A method for producing tungsten from a processing object containing tungsten by molten salt electrolysis,
By providing a cathode and an anode made of an anode material containing the object to be processed in the molten salt, and controlling the potential at the anode to a predetermined value, a metal element corresponding to the potential controlled from the object to be processed is obtained. 32. The method for producing a metal by molten salt electrolysis according to claim 30 or 31, wherein tungsten is left in the anode by being dissolved in the molten salt.
In the step of dissolving a metal element from the object to be treated in the molten salt, a standard electrode potential of the specific metal alone or its alloy in the molten salt and a standard electrode potential of another metal simple substance or its alloy The method for producing a metal by molten salt electrolysis according to any one of claims 30 to 32, wherein the molten salt is selected so that the difference between the two is 0.05 V or more.
A container holding the molten salt inside;
A cathode immersed in a molten salt held inside the container;
An anode which is immersed in a molten salt held inside the container and holds a treatment object containing two or more kinds of metal elements therein;
The anode is capable of circulating the molten salt between the inside and the outside,
further,
A controller for controlling the potential at the cathode and the anode to a predetermined value;
The said control part can change the value of the said electric potential, The apparatus used for the manufacturing method of the metal by molten salt electrolysis characterized by the above-mentioned.
A container holding therein a molten salt in which two or more kinds of metal elements are dissolved;
A cathode and an anode immersed in a molten salt held inside the container;
A controller for controlling the potential at the cathode and the anode to a predetermined value;
The said control part can change the value of the said electric potential, The apparatus used for the manufacturing method of the metal by molten salt electrolysis characterized by the above-mentioned.
36. The apparatus according to claim 34 or 35, wherein the two or more kinds of metal elements include at least one of tungsten and lithium.