KR20230081581A - Method for electrolytic refine and electrolytic reduction apparatus - Google Patents

Abstract

The present invention relates to the steps of a) filling an electrolyte containing an oxide of a third metal in a crucible made of the same material as the first metal, which is the target metal to be refined, or the second metal included in the cathode, b) the first metal included in the electrolyte. 3 Electrolytically reducing the oxide of the metal to prepare an alloy of the second metal and the third metal, c) Injecting the oxide of the first metal into the electrolyte, and adding the oxide of the first metal to the second metal and the third metal. reducing the first metal to an alloy of the first metal and the second metal by reacting the alloy of metals; and d) electrolytically refining the solidified alloy of the first metal and the second metal, A metal refining method comprising an electrolytic refining step of recovering a first metal from an alloy of a second metal.

Description

Metal refining method and metal electrolytic reduction apparatus {Method for electrolytic refine and electrolytic reduction apparatus}

The present invention relates to a metal electrolytic reduction device, and more preferably, a metal oxide containing a target metal is reduced in-situ in the same crucible to produce an alloy of a first metal and a second metal containing the target metal. It relates to an electrolytic reduction device and an electrolytic refining method.

Electrolytic reduction refers to a method of reducing and recovering a target metal due to the movement of ions generated when an electric current is applied to an electrolyte solution.

In the past, to recover Ti and Zr, a Kroll process (US Patent No. 5,035,404) was typically used. However, in the case of the crawl process, the carbon material anode is continuously consumed, and as a result, excessive CO/C0 ₂ is emitted during the smelting process.

In order to improve this, the present inventors proposed a method of recovering metals such as Zr and Ti by combining electrolytic reduction and electrolytic refining processes through Korean Patent Registration No. 10-1793471 and Korean Patent Registration No. 10-1878652. In particular, Korean Patent Registration No. 10-1878652 discloses a method of manufacturing a low-melting Cu-Zr alloy using an alloy of CaCu second metal and third metal, and recovering pure Zr by electrolytically refining the Cu-Zr alloy. Invented. However, the above invention has a problem in that the process of producing an alloy of CaCu second metal and third metal and the process of producing a Cu—Zr alloy through an alloy of the second metal and third metal are separated from each other. This reduces the productivity of the process, and also has a problem in that the purity is reduced because the Zr component is oxidized by oxygen in the air during the transition from the previous process to the next process.

Meanwhile, as a method for melting an alloy (Ti-6Al-4V) containing Ti, a skull melting process using induction has been disclosed (Induction Skull Melting of Ti-6Al-4V: Process Control and Efficiency Optimization, Xabier Chamorro, Metals 2019, 9, 539). However, since the skull melting process is a method of forcibly cooling the crucible to form a self-solidifying shell outside the molten metal, it has the disadvantage of high energy consumption, and as in the present invention, the electrolyte with different melting points, the second metal and the third metal There is a problem that it is difficult to apply in devices where alloys, CuTi molten alloys, etc. coexist.

US registered patent 5,035,404 Republic of Korea Patent No. 10-1793471 Republic of Korea Patent No. 10-1878652

(Paper 0001)Induction Skull Melting of Ti-6Al-4V: Process Control and Efficiency Optimization, Xabier Chamorro, Metals 2019, 9, 539

The present invention relates to a process of preparing an alloy of a second metal and a third metal, and a process of preparing an alloy of the first metal and the second metal by reducing a first metal oxide through an alloy of the second metal and the third metal. It is possible to provide an electrolytic reduction device that can be manufactured in-situ through a single crucible.

In addition, in order to secure the stability of the crucible from the alloy of the second metal and the third metal and the alloy of the first metal and the second metal generated in the electrolytic reduction process, process conditions for forming a compositional skull in the crucible material are provided. can do.

In addition, a method of recovering the first metal by electrolytic reduction and electrolytic refining of the first metal in the form of a metal oxide may be provided.

In order to solve the above problems, the present invention provides a) filling a crucible of the same material as the first metal, which is the target metal to be refined, or the second metal included in the cathode, with an electrolyte containing an oxide of the third metal; b) electrolytically reducing the oxide of the third metal contained in the electrolyte to prepare an alloy of the third metal and the second metal, c) injecting the oxide of the first metal into the electrolyte and the oxide of the first metal and an alloy of the third metal and the second metal reacting to reduce the first metal to an alloy of the first metal and the second metal, and d) electrolyzing the solidified alloy of the first metal and the second metal It relates to a metal refining method comprising an electrolytic refining step of refining and recovering a first metal from an alloy of the first metal and the second metal.

In the above embodiment, the electrolyte may include a molten salt of a halide of one or two or more metals selected from the group of alkali metals and alkaline earth metals, and an oxide of a third metal.

In the above embodiment, steps b) to c) may be performed in real time in the same crucible.

In the above embodiment, steps b) to c) may be performed at 800 to 1100 °C.

In the above embodiment, in the alloy of the third metal and the second metal, the third metal is included at 60 mol% or more, and in the alloy of the first metal and the second metal, the first metal is 60 mol% more may be included.

In the above embodiment, the metal refining method may further include forming a skull inside the crucible between steps b) to c).

In the above embodiment, the first metal is a metal selected from the transition metal group consisting of Ti, Zr, Mn, Cr, Zn, Ga, Ni, Fe, Co, W, and Ta, or a rare earth element consisting of Pr, Nd, and Dy. It may be provided with any one metal selected from the metal group.

In the above embodiment, the second metal may be provided as a metal selected from the group consisting of Cu, Sn, Zn, Pb, Bi, Cd, and Fe.

According to another embodiment of the present invention, the present invention provides a crucible of the same material as the first metal or the second metal that is the metal of the solid metal cathode, an electrolyte filled in the crucible and containing an oxide of a third metal, a first An input unit for injecting a metal oxide into the electrolyte, an insoluble anode immersed in the electrolyte, and a cathode immersed in the electrolyte and containing a second metal, manufacturing an alloy of the first metal and the second metal. It relates to a metal electrolytic reduction device.

In the above embodiment, the first metal is a metal selected from the transition metal group consisting of Ti, Zr, Mn, Cr, Zn, Ga, Ni, Fe, Co, W, and Ta, or a rare earth element consisting of Pr, Nd, and Dy. It may be provided with any one metal selected from the metal group.

In the above embodiment, when the first metal is provided as a transition metal consisting of Ti, Zr, Mn, Cr, Zn, Ga, Ni, Fe, Co, W, and Ta, the crucible is made of the same metal as the first metal. can be manufactured with

In the above embodiment, the second metal may be provided as a metal selected from the group consisting of Cu, Sn, Zn, Pb, Bi, Cd, and Fe.

In the above embodiment, when the first metal is provided as a rare earth metal composed of Pr, Nd, and Dy, Fe is used as the second metal, and the crucible may be made of the second metal.

In the above embodiment, the insoluble anode includes a core layer containing any one material selected from ion conductive ceramics, electrically conductive ceramics, cermet, and conductive carbide ceramics, and an alloy containing Ni or Cu surrounding the core layer. Layers may be formed.

In the above embodiment, the alloy layer in the insoluble anode may react with oxygen generated during the electrolytic refining process to form a metal oxide-type protective film on the anode surface.

By producing the alloy of the second metal and the third metal and the alloy of the first metal and the second metal of the present invention in real time in the same crucible, the productivity of the alloy of the first metal and the second metal is improved, and the purity is greatly increased. There is an effect that can be increased.

In addition, in the electrolytic reduction process, a compositional skull is formed on the inner surface of the crucible to suppress the reaction between the crucible and the alloy of the second metal and the third metal or between the crucible and the alloy of the first metal and the second metal to improve the stability of the crucible. can

1 is a graph showing the mass loss rate according to the electrolytic reduction time of an anode manufactured according to an embodiment of the present invention.
2 is a diagram for explaining an electrolytic refining apparatus according to an embodiment of the present invention.
3 is a view for explaining in detail a metal refining method according to an embodiment of the present invention.
4 is a graph showing the results of Gibbs free energy (ΔG) calculation for limiting the concentration range of Ca in CuCa for maintaining the stability of the crucible according to an embodiment of the present invention.
5 is a photograph taken by SEM of a cross section of an alloy of a first metal and a second metal prepared in Comparative Example 1.
6 is a photograph taken by SEM of a cross section of an alloy of a first metal and a second metal prepared in Example 1.
7 is a cross-sectional photograph of a crucible for comparing the stability of the crucible according to the composition of Ta in the cathode material.
8 is a photograph for explaining a compositional skull line.
9 is a cross-sectional photograph of a crucible for comparing the stability of the crucible according to the composition of Ca in the reducing agent.
10 is a frontal photograph of a crucible for comparing the stability of the crucible according to the composition of Ca in the reducing agent.

Hereinafter, a metal refining method and a metal electrolytic reduction device according to the present invention will be described in detail. The drawings introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Therefore, the present invention may be embodied in other forms without being limited to the drawings presented below, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. At this time, unless there is another definition in the technical terms and scientific terms used, they have meanings commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention in the following description and accompanying drawings Descriptions of well-known functions and configurations that may be unnecessarily obscure are omitted.

One embodiment of the present invention relates to a metal electrolytic reduction device, specifically, to manufacture an alloy of a first metal and a second metal for use in electrolytic refining, including a crucible, a heating part, an inlet part, an insoluble anode and a cathode. can do.

In the present invention, the alloy of the first metal and the second metal refers to an alloy that acts as an anode material in an electrolytic refining process to be described later. According to an embodiment, the first metal means a target metal to be obtained through electrorefining, and the second metal means a metal having a standard reduction potential greater than that of the first metal. Due to the difference in standard reduction potential, when preparing an alloy of the first metal and the second metal, the standard reduction potential value of the first metal is shifted in a positive direction, and the alloy of the first metal and the second metal produced by electrolytic reduction productivity can be improved.

According to an embodiment, the first metal is any one metal selected from the transition metal group consisting of Ti, Zr, Mn, Cr, Zn, Ga, Ni, Fe, Co, W, and Ta, or Pr, Nd, and Dy. It may be provided with any one metal selected from the group consisting of rare earth metals, but is not limited thereto, and may be made of other transition metals or other rare earth metals not described herein.

According to an embodiment, the second metal may be provided as a metal selected from a metal group consisting of Cu, Sn, Zn, Pb, Bi, Cd, and Fe, but is not limited thereto. However, the first metal and the second metal are different metals, and the same metal cannot be used.

If Ti is selected as the first metal and Cu is selected as the second metal, the alloy of the first metal and the second metal may be made of TiCu. Hereinafter, the present specification describes that the first metal is Ti, the second metal is Cu, and the alloy of the first metal and the second metal is TiCu as an example, but is not limited thereto, and the aforementioned first metal and the second metal are described as examples. It is obvious that alloys of the first metal and the second metal having different compositions can be prepared through a combination of the two metals.

Another embodiment of the present invention relates to a metal refining method for recovering a high-purity first metal from an oxide of the first metal. The metal refining method includes the steps of a) filling an electrolyte containing an oxide of a third metal in a crucible made of the same material as the first metal, which is the target metal to be refined, or the second metal included in the cathode, b) preparing an alloy of the third metal and the second metal by electrolytic reduction of the oxide of the third metal; c) injecting the oxide of the first metal into the electrolyte and combining the oxide of the first metal with the third metal; reducing the first metal to an alloy of the first metal and the second metal by reacting the alloy of the second metal; d) electrolytically refining the solidified alloy of the first metal and the second metal; and an electrorefining step of recovering the first metal from an alloy of the metal and the second metal.

In this process, steps b) to c) may be performed in real time in the same crucible. Through this, the present invention, by manufacturing the alloy of the first metal and the second metal in-situ in the same crucible, in the process of manufacturing the alloy of the first metal and the second metal, the first metal is oxygen in the air It is possible to prevent oxidation in contact with, and greatly improve the purity of the first metal in the alloy of the first metal and the second metal.

In addition, the first metal having a purity of 99.99% or more may be recovered by electrolytically refining the alloy of the first metal and the second metal.

The embodiments of the present invention have been briefly described above. Hereinafter, a metal electrolytic reduction device according to an embodiment of the present invention will be described with reference to FIG. 1 .

1 is a diagram for explaining an electrolytic reduction device according to an embodiment of the present invention.

Referring to FIG. 1, the electrolytic reduction device 100 according to an embodiment of the present invention includes a crucible 110, an input unit 120, an insoluble anode 130, a cathode 150, a heating unit 170, a power supply unit ( 190) and a reference electrode (not shown). In more detail, an input unit 120 may be formed on the top of the crucible 110, and an insoluble anode 130, a cathode 150, and a reference electrode may be included inside the crucible 110. . A heating unit 170 for heating the electrolyte inside the crucible 110 may be positioned at a lower portion or a side surface of the crucible 110 . Finally, a power supply unit 190 connected to the insoluble anode 130 and the cathode 150 to apply current may be included.

Through the electrolytic reduction device 100 described above, the present invention electrolytically reduces the first metal (M1) input from the input unit 120 and the second metal (M2) forming the cathode to obtain the first metal (M1) And an alloy of the second metal (M2) can be prepared.

The crucible 110 has a predetermined space formed therein, and an electrolyte (MS), more preferably, a molten salt (MS) may be filled in the space.

According to an embodiment, the molten salt electrolyte MS may be a mixture of a molten salt of a halide of one or more metals selected from the group of alkali metals and alkaline earth metals and an oxide of a third metal.

Specifically, the molten salt of the halide is any one or more chlorides selected from the group consisting of LiCl, NaCl, KCl, RbCl, CsCl, FrCl, BeCl ₂ , MgCl ₂ , CaCl ₂ , SrCl ₂ , BaCl ₂ and RaCl ₂ , LiF , NaF, KF, RbF, CsF, FrF, BeF ₂ , MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ and RaF ₂ It may be any one or more fluorides selected from the group consisting of, or a mixture of the chloride and the fluoride. It can be provided as a molten salt.

The third metal refers to a metal mixed in the molten salt of the halide in the form of a metal oxide, and more preferably may be provided as an alkali metal or an alkaline earth metal.

According to an embodiment, the third metal may be provided as a metal having an eutectic point with the second metal M2. Due to the eutectic point, the alloy (M2+M3) of the second metal and the third metal may react at a temperature lower than the melting point of the second metal and the third metal to exist in an alloyed liquid phase state.

In addition, the alloy of the second metal and the third metal (M2+M3) has a relatively higher density than the electrolyte and may drop itself to the bottom of the crucible. Through this, the alloy of the second metal and the third metal (M2+M3) may be prevented from being exposed and contaminated, and may be placed on the bottom of the crucible.

According to the embodiment. The third metal may be included in the electrolyte in the form of CaO, BaO, SrO, Li ₂ O, Na ₂ O, Cs ₂ O, and K ₂ O.

According to an embodiment, the crucible 110 may be made of the same material as the first metal M1 or the second metal M2.

Specifically, when the first metal M1 is provided as a transition metal composed of Ti, Zr, Mn, Cr, Zn, Ga, Ni, Fe, Co, W, and Ta, the crucible is made of the same metal as the first metal. can be manufactured with

Alternatively, when the first metal M1 is provided as a rare earth metal composed of Pr, Nd, and Dy, Fe may be used as the second metal, and the crucible may be made of the second metal.

If the crucible 110 is made of a third metal other than the first metal M1 or the second metal M2, the component of the crucible 110 is an alloy of the second metal and the third metal. (M2+M3) or an alloy (M1+M2) of the first metal and the second metal may have reduced purity. Alternatively, the crucible 110 may be damaged because the crucible is melted by the alloy (M1+M2) of the first metal and the second metal.

To prevent this, in the present invention, the crucible 110 may be made of the same material as the first metal M1 or the second metal M2 to ensure stability of the crucible 110 . Specifically, in the present invention, the crucible 110 is made of the same material as the first metal M1 or the second metal M2, and the alloy of the first metal and the second metal (M1 + M2) and the second metal The activity of the alloy of the first metal and the second metal (M1+M2) and the alloy of the second metal and the third metal (M2+M3) by limiting the composition in the alloy of the metal and the third metal (M2+M3) degree can be reduced. Through this, the present invention prevents contamination of the alloy of the first metal and the second metal (M1 + M2), and at the same time, the alloy of the first metal and the second metal (M1 + M2) and the second metal and the third metal The melting of the crucible can be prevented by the alloy (M2+M3) of

In this process, the present invention forms a compositional skull (CS) on the inner surface of the crucible 110 to form an alloy (M1+M2) of the crucible 110 and the first metal and the second metal or the crucible 110 ) and the alloy of the second metal and the third metal (M2+M3) may be prevented from reacting. The method for reducing the activity of the alloy of the first metal and the second metal (M1 + M2) and the alloy of the second metal and the third metal (M2 + M3) and the conditions for generating the compositional skull will be described later. .

The insoluble anode 130 may include a core layer including any one material selected from ion conductive ceramics, electrically conductive ceramics, cermet, and conductive carbide ceramics, and an alloy layer surrounding the core layer.

According to an embodiment, the alloy layer may be provided with an alloy containing Ni or Cu, and the alloy layer reacts with oxygen generated during the electrolytic reduction process to form a protective film in the form of a metal oxide on the surface of the anode to form the core layer. can protect In addition, the amount of oxide of the third metal in the electrolyte may be reduced by continuously removing oxygen generated in the electrolyte. As a result, recycling of the third metal included in the electrolyte may be induced, thereby reducing the amount of electrolyte used.

The configuration of the metal electrolytic reduction device 100 according to the embodiment of the present invention has been described above. Hereinafter, the configuration of the metal electrolytic refining device 200 according to an embodiment of the present invention will be described.

2 is a diagram for explaining an electrolytic refining apparatus according to an embodiment of the present invention.

Referring to FIG. 2, a metal electrolytic refining apparatus 200 according to an embodiment of the present invention includes a crucible 210, an anode 230, a cathode 250, a reference electrode 270, and a potentiostat 290. can include

The crucible 210 means a separate crucible different from the crucible 110 of the electrolytic reduction device 100. In addition, unlike the crucible 110 of the electrolytic reduction device 100, it is not limited to the first metal M1 or the second metal M2, and may be made of a material commonly used in a previously known electrolytic reduction device. there is. For example, the crucible 210 of the electrolytic refining apparatus 200 may be made of alumina (Al ₂ O ₃ ), but is not limited thereto.

The crucible 210 may contain molten salt in which one or more metal halides selected from the alkali metal and alkaline earth metal groups are melted. Preferably, the electrolyte is a molten salt in which one or more metal halides selected from the group of alkali metals including Li, Na, K, Rb and Cs and alkaline earth metals including Mg, Ca, Sr and Ba are melted. It may be included, more preferably one or two or more molten salts selected from LiCl, KCl, SrCl2, CsCl, NaCl, LiF, KF, SrF2, CsF, CaF2 and NaF.

The anode 230 may be provided as an alloy (M1+M2) of the first metal and the second metal manufactured in the electrolytic reduction device 100. More preferably, a solidified positive electrode material may be provided by cooling the liquid alloy of the first metal and the second metal (M1+M2).

According to an embodiment, the cooling may be performed slowly at a temperature of 20° C./min or less. When the cooling rate exceeds 20 ° C./min, the phase composed of the intermetallic compound of the first metal and the second metal may not be sufficiently formed due to subcooling, and the area of the phase is reduced to be trapped by the phase composed of the second metal. can However, if the cooling rate is less than 1° C./min, the cooling time may be excessively increased, resulting in reduced productivity. For this reason, the cooling is preferably performed slowly at a temperature of 20° C./min or less, more preferably at 1 to 18° C./min.

The cathode 250 and the reference electrode 270 may be made of materials commonly used in known electrolytic reduction devices. For example, the negative electrode 250 may be made of stainless steel, and the reference electrode 270 may be made of tungsten (W).

The configuration of the metal electrolytic refining device 200 according to the embodiment of the present invention has been described above. Hereinafter, a metal refining method according to an embodiment of the present invention will be described in detail.

3 is a view for specifically explaining a metal refining method according to an embodiment of the present invention, and FIG. 4 is a Gibbs free for limiting the concentration range of Ca in CuCa for maintaining stability of a crucible according to an embodiment of the present invention. This is a graph showing the energy (ΔG) calculation result.

According to an embodiment, the electrolytic refining method includes the steps of a) filling an electrolyte containing an oxide of a third metal in a crucible made of the same material as the first metal, which is the target metal to be refined, or the second metal included in the cathode, b) ) Electrolytically reducing the oxide of the third metal contained in the electrolyte to prepare an alloy of the third metal and the second metal, c) Injecting the oxide of the first metal into the electrolyte and combining the oxide of the first metal with The alloy of the third metal and the second metal reacts to reduce the first metal to an alloy of the first metal and the second metal; and d) electrolytically refining the solidified alloy of the first metal and the second metal. Thus, an electrolytic refining step of recovering the first metal from the alloy of the first metal and the second metal may be included.

According to an embodiment, steps a) to c) may be performed in the electrolytic reduction device 100, and step d) may be performed in the electrolytic refining device 200. Steps a) to c) performed in the electrolytic reduction device 100 may be performed in real time in the same crucible. In other words, the electrolytic reduction method may be performed in-situ.

In step a), the crucible may be filled with electrolyte. In this case, the electrolyte refers to a solution obtained by mixing an oxide of a third metal with a molten salt of a halide of one or more metals selected from the group of alkali metals and alkaline earth metals.

According to an embodiment, the oxide of the third metal may be included in an amount of 0.1 to 25% based on the total weight of the electrolyte.

According to an embodiment, the crucible may be made of the same material as the first metal or the second metal. For example, if the first metal M1 is a transition metal, the crucible may be made of the same metal as the first metal, and if the first metal is a rare earth metal, the crucible and the cathode may be made of Fe. can be manufactured.

In the step b), an alloy of the third metal and the second metal may be prepared by electrolytically reducing the oxide of the third metal included in the electrolyte.

As described above, as the second metal and the third metal have an eutectic point, an alloy of the second metal and the third metal can be produced at a temperature below the melting point of the second metal and the third metal. can The alloy of the second metal and the third metal may be reduced and electrodeposited on the surface of the cathode in a liquid state and dropped in a liquid form on the bottom of the crucible.

As a specific example, when the second metal is Cu and the third metal is Ca, a reduction reaction occurs according to the following relational expression 1 to prepare an alloy of the second metal and the third metal.

[Relationship 1]

2CaO(s) → 2Ca ²⁺ + O ₂ (g) + 4e ^-

2Ca ²⁺ + 2Cu(s) + 4e ^- → 2CaCu(l)

In the relational expression 1, CaO contained in the electrolyte is electrolytically reduced and separated into Ca ²⁺ and O 2 , and the Ca ²⁺ CaCu in a liquid state may be formed by reacting with Cu of the cathode. In addition, oxygen generated during the reaction may react with the Ni or Cu alloy layer of the insoluble anode to form a conductive oxide protective film in the form of NiO or CuO on the surface of the anode.

That is, through the relational expression 1, the electrolytic reduction device generates an alloy of the second metal and the third metal and at the same time forms a conductive oxide protective film in the form of NiO or CuO on the surface of the anode to improve durability and density of the anode. mass loss can be reduced.

In the step c), an alloy of the first metal and the second metal may be prepared by introducing an oxide of the first metal into an electrolyte and reducing the oxide of the first metal to an alloy of the second metal and the third metal. there is.

In the step c), the first metal may be introduced into the electrolyte in the form of a metal oxide, for example, TiO ₂ or ZrO ₂ when the first metal is a transition metal such as Ti or Zr. Rare earth metals such as Nd and Dy may be introduced into the electrolyte in the form of Nd ₂ O ₃ and Dy ₂ O ₃ .

Thereafter, the alloy of the second metal and the third metal prepared in step b) may act as a reducing agent to reduce the first metal introduced in the form of a metal oxide to prepare an alloy of the first metal and the second metal. Specifically, when the metal oxide including the first metal is TiO ₂ and the alloy of the second metal and the third metal is CaCu, a reduction reaction may occur according to the following relational expression 2.

[Relationship 2]

TiO ₂ (s) +２CaCu(l) --> TiCu(l) + CaO(l)

In Relational Equation 2, the CuCa reducing agent present in the liquid metal form reduces TiO to produce CuTi, and the remaining CaO is included in the electrolyte again to maintain the concentration of the third metal in the electrolyte at a certain level.

However, in this process, the alloy of the second metal and the third metal (CuCa) and the alloy of the first metal and the second metal (CuTi) react in the crucible, so that the components of the crucible are an alloy of the first metal and the second metal (CuTi). ) to reduce the purity of the first metal. In addition, the crucible may be damaged by melting the crucible by reacting with CuCa and CuTi.

Therefore, in order to secure the soundness of the crucible and prevent the crucible from reacting with the alloy of the first metal and the second metal, the present invention provides a mixture of the alloy of the second metal and the third metal and the first metal and the second metal. The activity of the alloy is analyzed through a thermodynamics module, and the range of molarity that can reduce the activity of the alloy of the second metal and the third metal and the alloy of the first metal and the second metal to an appropriate level can be calculated.

Referring to FIG. 4, when the first metal is Ti, the second metal is Cu, and the third metal is Ca, CuCa When Ca in the alloy of the second metal and the third metal is 60 mol% or more, Gibbs free energy (Δ G) has a positive value in the entire region of CuTi, so that a Ti crucible can be used as an insoluble crucible.

In other words, in the present invention, the reaction with the crucible can be suppressed by controlling the number of moles of the second metal and the third metal as shown in relational expression 3 below. As a result, it is possible to control the melting of the crucible due to a reaction between the alloy of the second metal and the third metal and the alloy of the first metal and the second metal during the electrolytic reduction process.

[Relationship 3]

Cu _2-x Ca _4x +(2x)TiO ₂ =Cu _2-x Ti _2x +(4x)CaO

(In relational expression 2 above, x is an integer that satisfies 0.7 < x < 2)

Referring to the relational expression 3, when x is 0.7 or less, the concentration of Ca in the alloy of the CuCa second metal and the third metal increases to 70 mol% or more. When the concentration of Ca in the alloy of the CuCa second metal and the third metal is 60 mol% or more, the activity of Cu is relatively low enough to suppress the reaction of Cu.

In other words, when the concentration of Ca in the alloy of the CuCa second metal and the third metal is 60 mol% or more, and more preferably 70 mol% or more, the activity of Cu is lowered and the reaction with the crucible can be prevented.

Meanwhile, when x is 0.7 or less, the alloy of the CuTi first metal and the second metal may have 60 mol% or more of Ti. Even in the alloy of the first metal and the second metal, when the content of Ti is 60 mol% or more, the activity of Cu is relatively low, so that the reaction of Cu can be suppressed. In other words, when the concentration of Ti in the alloy of the CuTi first metal and the second metal is 60 mol% or more, more preferably 70 mol% or more, the activity of Cu is lowered and the reaction with the crucible can be prevented.

As a result of the experiment by changing the composition of the first, second and third metals, the alloy of the second metal and the third metal may contain 60 mol% or more of the third metal, and the first metal and the second metal It was confirmed that the alloy of may include 60 mol% or more of the first metal.

In addition, when the relational expression 3 is satisfied, a skull made of CuTi may be formed inside the crucible. As a result, the skull may cover the inside of the crucible to prevent the alloy of the second metal and the third metal in a liquid state or the alloy of the first metal and the second metal in a liquid state from directly contacting the crucible. In other words, the CuTi skull layer covers the inner surface of the crucible to prevent the alloy of the first metal and the second metal or the alloy of the second metal and the third metal from reacting with the crucible and melting the crucible. Hereinafter, a skull formed according to the composition satisfying the relational expression 3 is defined as a compositional skull, and a surface on which the compositional skull is formed is defined as a compositional skull line.

If the first metal is not a transition metal but a rare earth metal composed of Pr, Nd, and Dy, if Fe is selected as the second metal and the cathode and the crucible are made of Fe, the inside of the crucible under the same conditions as the transition metal It is possible to form a compositional skull. In other words, when the first metal is a rare earth and the second metal is Fe, the third metal is 60 mol% or more in the alloy of the second metal and the third metal, and the first metal in the alloy of the first metal and the second metal When it is contained in an amount of 60 mol% or more, the crucible can be protected by forming a compositional skull inside the crucible.

According to an embodiment, CaO generated in the relational expression 2 or the relational expression 3 may be redissolved in the electrolyte and electrolytically reduced according to the relational expression 1, but when the concentration of CaO increases to 3 mol% or more, CaCu second metal The alloy of the first metal and the third metal may reduce the rate at which TiO is reduced, thereby preventing the formation of an alloy between the first metal and the second metal. To prevent this, CaO may be continuously decomposed at the insoluble anode to be maintained at 3 mol% or less.

According to an embodiment, steps b) and c), or steps a) to c) may be performed at 800 to 1100 °C. When the steps b) and c) are less than 800 ° C, the activity of Ca decreases, so that the mol% of the third metal in the alloy of the second metal and the third metal decreases and the mol% of the second metal increases. can In this case, the second metal in the alloy of the second metal and the third metal may react with the crucible made of the first metal to melt the crucible.

Conversely, when the temperature exceeds 1100 ° C., the activity of Ti decreases, so that the mol% of the first metal in the alloy of the first metal and the second metal decreases, and the mol% of the second metal increases, so that the first metal and the second metal A second metal in the alloy of metals may react with the crucible and melt it.

For this reason, steps b) and c) may be performed at 800 to 1100 °C, more preferably at 900 to 1000 °C.

Finally, in step d), the first metal may be recovered from the alloy of the first metal and the second metal by electrolytically refining the alloy of the first metal and the second metal.

Unlike steps a) to c), step d) may be performed in an electrolytic refining apparatus. A description of the electrolytic refining device will be omitted.

According to an embodiment, in step d), electrolytic refining may be performed by applying a current density of 10 to 500 mA/cm 2 at 600 to 800 °C. At this time, the temperature and time of electrolytic refining are described only for one example and are not limited thereto, and may be modified and applied by the judgment of a person skilled in the art. In addition, the electrolytic refining may be performed for 1 to 20 hours.

The metal refining method and metal electrolytic reduction device according to the embodiment of the present invention have been described above. In the present specification, it has been described that the first metal is Ti, the second metal is Cu, and the third metal is Ca as an example, but it is not limited thereto, and the first to third metals may be replaced with other metals described in the specification. . For example, even when the first metal is Zr, it may be manufactured as an alloy of the first metal and the second metal through the same process as Ti.

Hereinafter, the present invention will be described in more detail through examples. However, it should be noted that the following examples are only for illustrating the present invention in more detail, and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the claims and the matters reasonably inferred therefrom.

go. Contamination test of the alloy of the first metal and the second metal due to the crucible

In order to compare the state of the alloy of the first metal and the second metal according to the material of the crucible, the following examples and comparative examples were prepared.

[Example 1]

A CaCl ₂ electrolyte containing 5% by weight of CaO was prepared. The electrolyte was charged into a crucible made of Ti (purity of 99% or more) of Grade 2, and an insoluble anode, cathode, and reference electrode were connected. At this time, the insoluble anode was used as a material containing an alloy layer of 30% by weight of Ti-C Cermet and the balance of NiO, the cathode was used with 30 g of Cu, and the reference electrode was used with tungsten.

Thereafter, CaCu was produced by performing electrolytic reduction in a state where the crucible was heated to 900 ° C., a current density of 500 mA / cm 2 and a cathode potential of -1.3 to -1.5 V compared to the tungsten reduction potential. In addition, while producing CaCu, TiO ₂ having an average particle size of 4.5 μm was introduced into the electrolyte through the inlet to manufacture TiCu in the same crucible.

[Example 2]

A crucible was made of Zr having a purity of 99% or more, and all processes were performed in the same manner as in Example 1 except that ZrO ₂ was introduced into the electrolyte through the inlet during electrolytic reduction.

[Comparative Example 1]

All processes were performed in the same manner as in Example 1 except that the crucible was made of Mo having a purity of 99% or more.

After preparing an alloy of the first metal and the second metal made of TiCu or ZrCu by performing electrolytic reduction for 12 hours according to Example 1, Example 2 and Comparative Example 1, the alloy of the first metal and the second metal A cross section of was cut, and components of the cross section were analyzed to determine whether or not the alloy of the first metal and the second metal was contaminated.

Specifically, FIG. 5 is a photograph taken by SEM of a cross-section of an alloy of a first metal and a second metal prepared in Comparative Example 1, and FIG. 6 is a cross-section of an alloy of a first metal and a second metal prepared in Example 1. is a photograph taken by SEM, and Table 1 is a table summarizing whether or not contamination occurs between the first metal and the crucible material manufactured according to Examples 1 and 2 and Comparative Example 1.

For the SEM, Jeol's JP/JSM-7000F field emission scanning electron microscope was used.

1st metal crucible material contamination Example 1 Ti Ti X Example 2 Zr Zr X Comparative Example 1 Ti Mo O

Referring to Table 1, in Examples 1 and 2 in which the crucible was manufactured from the same material as the first metal, the alloy of the first metal and the second metal made of TiCu or ZrCu did not react with the crucible, so that the first metal and the crucible did not react. No contamination occurred in the alloy of the second metal. On the other hand, in Comparative Example 1 manufactured with a crucible made of a material different from the first metal, the crucible reacted with the alloy of the first metal and the second metal, and the components of the crucible were included in the alloy of the first metal and the second metal. As a result, it was confirmed that the alloy of the first metal and the second metal was contaminated.

Referring to FIG. 5 , it can be seen that the alloy of the first metal and the second metal prepared in Comparative Example 1 is divided into two regions because the components are not uniformly mixed and Mo is included in some regions. To analyze this in detail, after naming the bright area as area 1 and the dark area as area 2 in FIG. 5, the compositions of the first area and the second area were compared. The results are shown in Table 2 below.

Cu Ti Mo 1 area 51.46 at.% 32.15 at.% 16.39 at.% 2 area 38.09 at.% 61.91 at.% -

Referring to Table 2, it can be seen that the alloy of the first metal and the second metal prepared according to Comparative Example 1 of the present invention is contaminated because Mo, which is a composition of the crucible, is included in a partial area. As a result, the purity of the first metal was reduced due to the inclusion of impurities of Mo, and when the first metal is recovered by electrolytic refining of an alloy of the first metal and the second metal in the future, the first metal and the second metal of the same mass It can be fully expected that the recovery amount of the first metal recovered from the alloy of may also be reduced.

On the other hand, referring to FIG. 6, the alloy of the first metal and the second metal prepared in Example 1 is divided into region 1 and region 2 according to the density of Ti and Cu in the alloy, but as shown in Table 3 below, Cu and Ti It was confirmed that only the density was different and no impurities other than Ti and Cu were included. Specifically, although the composition of region 1 is different for each location, a relatively Ti-rich phase is formed with more than 78 at.% Ti and less than 22 at.% Cu, and region 2 with 36 at.% Cu and 64 at.% Ti. As a result, a CuTi phase with a relatively low Ti concentration compared to area 1 was formed. In the Ti-rich phase, the composition of Ti increases and decreases depending on the position, but in the CuTi phase, it was confirmed that the same composition was formed at all positions with Cu fixed at 36 at.% and Ti at 64 at.%. In addition, it was confirmed that Ti was uniformly maintained at 100 at.% in 3 (crucible area) of FIG. 6 .

Cu Ti 1 area (CuTi), composition differs by location 22-3 at.% 78∼97 at.% or more 2 areas (CuTi), uniform composition by position 38.09 at.% 61.91 at.% 3 zone (Ti crucible) - 100 at.%

That is, the alloy of the first metal and the second metal manufactured according to Examples 1 and 2 does not react with the crucible, and Ti-rich regions in which Ti is concentrated exist in some regions, but Ti and Ti are present in other regions. It can be seen that Cu exists in the same atomic percentage.

That is, the present invention prevents contamination of the alloy of the first metal and the second metal by manufacturing the material of the crucible with the same material as the first metal or the second metal, and the first metal in the alloy of the second metal 1 Can increase the purity of metals.

me. Evaluation of Crucible Stability by Compositional Skull Formation

In order to evaluate the stability of the crucible by the compositional skull formation of the present invention, an alloy of the second metal and the third metal or an alloy of the first metal and the second metal having different compositions is prepared through electrolytic reduction, and then Reaction was compared.

[Example 11]

CaCu having 70 mol% of Ca and 30 mol% of Cu was prepared by the method described in Example 1 above. Thereafter, the CaCl ₂ electrolyte and the alloy of the second metal and the third metal having a composition of 70Ca-30Cu were charged into a crucible made of Grade 2 grade Ti (purity of 99% or more Ti) and maintained at 1050 ° C. for 12 hours.

[Comparative Example 11]

All processes were performed in the same manner as in Example 11 except that the composition of the alloy of the second metal and the third metal was 40Ca-60Cu.

[Comparative Example 12]

All processes were performed in the same manner as in Example 11 except that the composition of the alloy of the second metal and the third metal was 51Ca-49Cu.

[Example 12]

TiCu in which 70 mol% of Ti and 30 mol% of Cu were mixed was prepared by the method described in Example 1 above. Thereafter, the CaCl ₂ electrolyte and the alloy of the first metal and the second metal of the 70Ti-30Cu composition were charged into a crucible made of Grade 2 Ti (purity of 99% or more Ti), and 1050 ° C. was maintained for 12 hours.

[Comparative Example 13]

All processes were performed in the same manner as in Example 11 except that the composition of the alloy of the first metal and the second metal was prepared with 30 mol% of Ti and 70 mol% of Cu.

[Comparative Example 14]

All processes were performed in the same manner as in Example 11 except that the composition of the alloy of the first metal and the second metal was prepared with 50 mol% of Ti and 50 mol% of Cu.

Then, whether the crucibles according to Examples 11 and 12 and Comparative Examples 11 to 14 were formed with compositional skulls is summarized in Table 4 below.

Also, for convenience of explanation, in the embodiment, the alloy of the first metal and the second metal is referred to as a cathode material, and the alloy of the second metal and the third metal is referred to as a reducing agent.

Composition of reducing agent or cathode material (mol%) compositional skull formation Ti Ca Cu Example 11 - 70 30 O Example 12 70 - 30 O Comparative Example 11 - 40 60 X Comparative Example 12 - 51 49 X Comparative Example 13 30 - 70 X Comparative Example 14 50 - 50 X

Referring to Table 4, in Example 11, in which the reducing agent contained 60 mol% or more of the second metal (Ca), and in Example 12, in which the cathode material contained 60 mol% or more of the first metal (Ti), the outer wall of the crucible was Although the crucible was not melted and safety was ensured by the formation of a sexual skull, in Comparative Examples 11 to 14, the crucible was melted by the positive electrode material or the reducing agent because the compositional skull was not formed.

7 is a cross-sectional photograph of a crucible for comparing the stability of the crucible according to the composition of Ta in the cathode material, FIG. 8 is a photograph for explaining the compositional skull line, and FIG. 9 is a photograph of the composition of Ca in the reducing agent. 10 is a cross-sectional photograph of the crucible for comparing stability of the crucible, and FIG. 10 is a frontal photograph of the crucible for comparing the stability of the crucible according to the composition of Ca in the reducing agent.

Referring to FIG. 7, in Example 12, in which the Ti composition in the cathode material was 60 mol% or more, the shape of the crucible was maintained, but in Comparative Examples 13 and 14, in which the Ti composition in the cathode material was less than 60 mol%, the bottom of the crucible was melted. can This is because, as described above, when the Ca content of the CuCa reducing agent is 60 mol % or more, the activity of Cu is relatively low enough to suppress the reaction of Cu with the Ti crucible.

As a result, as shown in FIG. 8, a compositional skull made of CuTi may be formed inside the crucible, and a compositional skull line may be formed along the inner surface of the crucible. Due to the compositional skull line, it is possible to greatly improve the stability of the crucible by preventing the positive electrode material in a liquid state from coming into direct contact with the crucible.

Similarly, referring to FIGS. 9 and 10 , in Comparative Example 11 in which the Ca composition in the reducing agent was 40 mol% and Comparative Example 12 in which the Ca composition was 51 mol%, it could be confirmed that the crucible reacted with the reducing agent and the crucible was melted. On the other hand, in Example 11 in which the Ca composition was 60 mol% or more, the shape of the crucible was maintained. This is because, as described above, when the Ca content of the CuCa reducing agent is 60 mol % or more, the activity of Cu is relatively low enough to suppress the reaction of Cu with the Ti crucible.

The metal refining method and metal electrolytic reduction device according to the embodiment of the present invention have been described above.

As described above, the present invention includes a crucible, a heating unit, an inlet unit for introducing a first metal in the form of a metal oxide, an insoluble anode, and a cathode including a second metal, wherein the electrolyte is chloride, fluoride, or chloride and fluoride. A molten salt of a halide made of and an oxide of a third metal are mixed, and the electrolytic reduction equipment produces an alloy composed of the second metal and the third metal by electrolytically reducing the third metal in the form of a metal oxide in the same crucible. The process of preparing the alloy of the first metal and the second metal by reducing the oxide of the first metal with the alloy of the second metal and the third metal may be performed in real time.

In this process, the present invention can prevent impurities from being included in the alloy of the first metal and the second metal by making the crucible of the same metal and improve the purity of the first metal.

In addition, the present invention includes 60 mol% or more of the third metal in the alloy of the second metal and the third metal, and 60 mol% or more of the first metal in the alloy of the first metal and the second metal. A skull may be formed inside the crucible to prevent melting of the crucible due to an alloy of the second metal and the third metal or an alloy of the first metal and the second metal.

If the first metal is provided as a rare earth metal composed of Pr, Nd, and Dy, Fe is used as the second metal, and the crucible is made of Fe as the second metal, and the skull inside the crucible is formed through the same process. It is possible to prevent the crucible from melting by forming.

In the above description, various embodiments of the present invention have been presented and described, but the present invention is not necessarily limited thereto. It will be readily apparent that branch substitutions, modifications and alterations are possible.

100: metal electrolytic reduction device
Reference Numerals 110: crucible 120: input unit 130: insoluble anode 150: cathode 170: heating unit
190: power supply
200: metal electrolytic refining device
210: crucible 230: anode 250: cathode 270: reference electrode 290: potential constant

Claims (15)

a) filling an electrolyte containing an oxide of a third metal in a crucible made of the same material as the first metal, which is a target metal to be refined, or the second metal included in the cathode;
b) preparing an alloy of the second metal and the third metal by electrolytically reducing the oxide of the third metal contained in the electrolyte;
c) An oxide of the first metal is introduced into the electrolyte, and the oxide of the first metal reacts with an alloy of the second metal and the third metal to reduce the first metal to an alloy of the first metal and the second metal. step of becoming; and
d) an electrolytic refining step of recovering the first metal from the alloy of the first metal and the second metal by electrolytically refining the solidified alloy of the first metal and the second metal; According to claim 1,
The electrolyte is
A metal refining method comprising a molten salt of a halide of one or more metals selected from the alkali metal and alkaline earth metal groups and an oxide of a third metal. According to claim 1,
Steps a) to c) are performed in real time in the same crucible, metal refining method. According to claim 1,
Steps b) and c) are performed at 800 to 1100 ° C., a metal refining method. According to claim 1,
In the alloy of the third metal and the second metal, the third metal is included in 60 mol% or more,
In the alloy of the first metal and the second metal, the first metal is included in 60 mol% or more, a metal refining method. According to claim 1,
The metal refining method
Between the steps b) to c), forming a skull inside the crucible; metal refining method further comprising. According to claim 1,
The first metal is a metal selected from the transition metal group consisting of Ti, Zr, Mn, Cr, Zn, Ga, Ni, Fe, Co, W, and Ta, or any one selected from the rare earth metal group consisting of Pr, Nd, and Dy. A metal refining method, provided as one metal. According to claim 1,
The second metal is provided as a metal selected from the group consisting of Cu, Sn, Zn, Pb, Bi, Cd and Fe, metal refining method. a crucible made of the same material as the first metal or the second metal which is the metal of the solid metal cathode;
an electrolyte filled in the crucible and containing an oxide of a third metal;
an inlet for injecting an oxide of a first metal into the electrolyte;
an insoluble anode immersed in the electrolyte; and
A cathode immersed in the electrolyte and containing a second metal;
A metal electrolytic reduction device for producing an alloy of the first metal and the second metal. According to claim 9,
The first metal is a metal selected from the transition metal group consisting of Ti, Zr, Mn, Cr, Zn, Ga, Ni, Fe, Co, W, and Ta, or any one selected from the rare earth metal group consisting of Pr, Nd, and Dy. A metal electrolytic reduction device, provided by one metal. According to claim 10,
When the first metal is provided as a transition metal composed of Ti, Zr, Mn, Cr, Zn, Ga, Ni, Fe, Co, W, and Ta,
Wherein the crucible is made of the same metal as the first metal. According to claim 9,
Wherein the second metal is provided as a metal selected from the group consisting of Cu, Sn, Zn, Pb, Bi, Cd and Fe. According to claims 10 and 12,
When the first metal is provided as a rare earth metal composed of Pr, Nd, and Dy,
A metal electrolytic reduction device in which Fe is used as the second metal and the crucible is made of the second metal. According to claim 9,
The insoluble anode has a core layer including any one material selected from ion conductive ceramics, electrically conductive ceramics, cermet, and conductive carbide ceramics therein, and
A metal electrolytic reduction device in which an alloy layer containing Ni or Cu surrounding the core layer is formed. According to claim 14,
In the insoluble anode, the alloy layer reacts with oxygen generated during the electrolytic refining process to form a protective film in the form of a metal oxide on the surface of the anode.

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