CN116685720A

CN116685720A - Reduction method and system for refractory metal oxides using fluoride-based electrolytes

Info

Publication number: CN116685720A
Application number: CN202180084243.6A
Authority: CN
Inventors: 李咏俊; 柳弘热
Original assignee: Korea Strategic Materials Technology Co ltd
Current assignee: Korea Strategic Materials Technology Co ltd
Priority date: 2020-11-17
Filing date: 2021-03-29
Publication date: 2023-09-01
Also published as: CA3201236A1; AU2021384253A1; KR20220067533A; KR20230107170A; US20240002974A1; JP2023550382A; EP4249644A1; WO2022108007A1

Abstract

The present disclosure relates to metal oxide reduction methods, and in particular, to metal oxide reduction methods that: the method achieves operation in the atmosphere by departing from the existing production process in an inert gas atmosphere when using a metal oxide as a raw material to produce a high-quality alloy metal, and is easily commercialized and can maximize efficiency due to the use of an eco-friendly method.

Description

Reduction method and system for refractory metal oxides using fluoride-based electrolytes

Technical Field

The present disclosure relates to a reduction method for refractory metal oxides, and in particular, to such a reduction method and system for metal oxides: wherein the operation in the atmosphere is achieved without using the existing production process in an inert gas atmosphere, and the efficiency thereof can be maximized and the easy commercialization thereof is provided using an eco-friendly method.

Background

When a metal generally known in the art is referred to as any metal "M", the metal M may be obtained by reducing a raw material such as an oxide or a halide. Among the processes for producing the desired metal M, the process relatively well known and most widely used in the art is the so-called Kroll process.

Generally, the kroll process can be generalized to such a process: wherein molten magnesium is used as a reducing agent and a chloride of the desired metal M, such as titanium chloride or zirconium chloride, is added thereto to reduce titanium or zirconium. In this regard, more details of the kroll process can be found in U.S. registration patent No. 5,035,404.

Since this kroll process is a process using chloride as a raw material, chlorine gas and magnesium chloride are generated as by-products during the process. Among these byproducts, chlorine gas is considered as a representative problem of the kroll process as an environmental substance causing a fatal problem to the human body, and in the case of magnesium chloride, it causes a problem in the process of rapidly corroding a reaction vessel (called a tank, a melting furnace or a crucible).

Thus, the kroll process requires additional equipment to address environmentally acceptable regulations and is accompanied by frequent replacement of the reaction vessel, resulting in high costs for operating the process.

On the other hand, in the kroll process, the obtained metal is produced in the form of a sponge comprising a large number of pores, and thus it is very difficult to control oxygen that may be present in the metal. In other words, the kroll process has a limitation in obtaining a high purity metal.

Instead of these existing methods, electrolytic refining methods are currently being studied, which have advantages over existing methods by directly reducing metal oxides without generating chlorine gas, but have problems in that the form of recovered metal is limited to powder and the particle size of the powder is also limited, making it difficult to control the oxygen concentration in the metal after the process. To overcome this, although it is necessary to reduce the specific surface area of the recycled metal by producing ingots using a method such as vacuum arc melting while the recycled metal powder produced by the refining method is not exposed to the atmosphere, in this case, large industrial equipment is difficult and there is a real difficulty in terms of cost.

On the other hand, the present inventors have proposed a liquid copper-assisted electrolysis (LCE) method (see patent documents 1 to 3) to solve the problems of the above-described methods, which involves a method of producing a target metal as an alloy by an electrolytic reduction process using a reducing agent, and then refining the high-purity target metal by electrolytic refining. However, even in such electrolytic reduction process, a chlorine-based flux having a high volatilization rate is used, resulting in problems of rapid corrosion and cost of equipment and generation of chlorine gas, which requires operation in an argon atmosphere in a closed system.

[ disclosure ] of the application

[ technical problem ]

[ patent literature ]

(patent document 1) U.S. registered patent No. 5,035,404

(patent document 2) korean patent registration No. 10-1757626

(patent document 3) korean patent registration No. 10-1793471

(patent document 4) korean patent registration No. 10-1878652

[ non-patent literature ]

(non-patent document 1) Antoine Allanaore, journal of The ElectrochemicalSociety,162 (1) (2015) E13-E22

The present disclosure is made to solve the problems of the prior art as described above, and an object of the present disclosure is to reduce a high melting point metal oxide to produce a high quality alloy metal in an environment friendly and efficient atmospheric environment using a fluoride-based flux. It is an object of the present disclosure to provide methods and systems for doing so.

The present disclosure is characterized by producing metal M ¹ And metal M ² Forming a eutectic phase with each otherA liquid metal alloy. Due to the reduction of metal M by eutectic reaction ¹ And therefore the reduction can be effectively performed at a relatively low temperature, which can save energy remarkably and produce cost reduction. Furthermore, the present disclosure provides for the production of a metal alloy in a liquid alloy state (M ¹ And M ² Is obtained such that the metal alloy itself can be used as a final product. In addition, metal M ¹ Can be obtained by subjecting the obtained metal alloy to electrolytic refining. The liquid alloy thus obtained can be completely separated from the environment in which oxygen may be present, and thus oxygen pollution can be significantly prevented. That is, according to the above aspect, a high purity metal alloy and a metal M can be obtained ¹ 。

The present disclosure relates to providing an alloy metal reduction method that can improve the high-quality productivity of the final product as compared with the related art, and has high energy efficiency and is advantageous for commercialization.

Technical scheme

According to the present disclosure, there is provided a method of reducing a metal M from a metal oxide ¹ Is a method of (2).

Reduction of metal M from metal oxides in accordance with the present disclosure ¹ The method of (1) comprises:

forming molten salt of fluoride-based flux in the tank;

adding metal M into the tank ¹ Metal M forming a eutectic phase ² And comprises a metal M ³ To produce metal M ² And metal M ³ Is a eutectic composition of (2); and

reduction of metal M by reacting a metal oxide with a eutectic composition ¹ And using reduced metal M ¹ And M ² Forming a liquid metal alloy.

Reduction of metal M from metal oxides ¹ In the method of (2), the molten salt of the fluoride-based flux may be smaller than the metal M ² With metal M ³ And the density of the metal oxide.

According to the present disclosure, the volatilization rate of the molten salt of the fluoride-based flux at 1600 ℃ for 10 hours is 10 wt% or less, specifically 5 wt% or less, and more specifically 2 wt% or less.

The fluoride-based flux may be selected from MgF in accordance with the present disclosure ₂ 、CaF ₂ 、SrF ₂ And BaF ₂ One or more of them, and may in particular be CaF ₂ 。

According to the present disclosure, metal M ¹ May be one or more selected from Ti, zr, hf, W, fe, ni, zn, co, mn, cr, ta, ga, nb, sn, ag, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb, ac, th, pa, U, np, pu, am, cm, bk, cf, es, fm, md and No.

According to the present disclosure, metal M ² May be one or more selected from Cu, ni, sn, zn, pb, bi, cd, and alloys thereof, and may be specifically Cu.

According to the present disclosure, metal M ³ May be one or more selected from Ca, mg, al, and alloys thereof, and in particular may be Mg.

According to the present disclosure, the metal oxide may include a metal selected from M ¹ _x O _z And M ¹ _x M ³ _y O _z Wherein x and y are each a real number from 1 to 3 and z is a real number from 1 to 4.

In accordance with the present disclosure, metal M is reduced by reacting a metal oxide with a eutectic composition ¹ The process of (2) may be carried out in air or in fluoride.

In accordance with the present disclosure, metal M is reduced by reacting a metal oxide with a eutectic composition ¹ May be carried out in the range 900 to 1600 ℃.

Reduction of metal M from metal oxides in accordance with the present disclosure ¹ The method of (2) may further comprise forming molten salt by adding a slag-forming additive and reducing the metal M by reacting the metal oxide with the eutectic composition ¹ Slag, and in particular, slagging, of by-products produced in the process of (a)The additive may comprise a material selected from MgO, caO, feO, baO, siO ₂ And Al ₂ O ₃ One or more of the following.

According to the present disclosure, the method comprises: forming a layer in which the liquid metal alloy is located at the bottom of the tank and separated from the eutectic composition, and continuously obtaining the liquid metal alloy through the lower portion of the tank; and

a separate layer is formed on top of the eutectic composition with slag and slag is continuously removed through the top of the trough.

In accordance with the present disclosure, the method may further include electrorefining the liquid metal alloy to produce metal M ¹ 。

The metal alloy or metal according to the present disclosure may be a metal alloy or metal obtained by any of the methods disclosed herein or a combination thereof, and may be such a metal alloy: it has a residual content of 0.1 wt% or less, specifically 0.01 wt% or less, and more specifically 0.001 wt% or less, and an oxygen content of 1800ppm or less, specifically 1500ppm or less, and more specifically 1200ppm or less.

For reducing metal M from metal oxides in accordance with the present disclosure ¹ The system of (1) may include:

a groove;

molten salt of fluoride-based flux in the tank;

metal M located in the lower part of the molten salt ² And metal M ³ Is a eutectic composition of (2); and

metal M located below the eutectic composition ¹ And metal M ² Is a liquid metal alloy of (a);

wherein the density of the molten salt may be less than the density of the metal oxide;

metal oxide and metal M ³ Can react to reduce metal M ¹ A kind of electronic device

Metal M ² Can be combined with metal M ¹ Forming a eutectic phase.

[ advantageous effects ]

The present disclosure provides an optimized system for obtaining a desired metal from a metal oxide without using metal chloride or chloride at all as a flux, and a method for producing such a metal. Accordingly, the present disclosure may solve the above-described environmental problems of the kroll process and the cost problems due to the groove corrosion.

The present disclosure is characterized by producing metal M ¹ And metal M ² Liquid metal alloys forming eutectic phases with each other. Due to the reduction of metal M by eutectic reaction ¹ And therefore the reduction can be effectively performed at a relatively low temperature, which can save energy remarkably and produce cost reduction.

The present disclosure provides a method of forming a metal alloy in a liquid alloy state (metal M ¹ And metal M ² Is obtained such that the metal alloy itself can be used as a final product. In addition, metal M ¹ Can be obtained by subjecting the obtained metal alloy to electrolytic refining. The liquid alloy thus obtained can be completely separated from the environment in which oxygen may be present, and thus oxygen pollution can be remarkably prevented. That is, according to the above aspect, a high purity metal alloy and a metal M can be obtained ¹ 。

Further, according to the present disclosure, it is easy to adjust the ratio of the target alloy, and it is possible to produce high purity metal by using the electrorefining technique of the finally produced alloy metal.

In the present disclosure, a high-quality metal M ¹ And the separation of the final product from the reaction product is easy, making continuous operation possible.

[ description of the drawings ]

FIG. 1 illustrates a process for reducing a metal M from a metal oxide in accordance with one embodiment of the present disclosure ¹ A process diagram of the process of (2).

FIG. 2 shows a schematic diagram illustrating the reduction of a metal M from a metal oxide according to one embodiment of the present disclosure ¹ A diagram of the process steps of the method of (a).

Fig. 3 shows a graph and a table of results showing the difference in volatilization rate between the fluoride-based flux and the chloride-based flux.

Fig. 4 shows a graph of vapor pressure of a fluoride-based flux and a chloride-based flux as a function of temperature.

Fig. 5 shows a photograph of a metal alloy produced according to one embodiment of the present disclosure.

Fig. 6 shows a graph and results table of elements analyzed using an Energy Dispersive Spectrometer (EDS) after cutting a metal alloy produced according to one embodiment of the present disclosure.

Fig. 7 shows a table of results of measuring the oxygen content present in the metal alloy produced according to example 2 of the present disclosure using eltronh 2000.

Embodiments of the application

Hereinafter, the intent, operation, and effects of the present disclosure will be described in detail through embodiments and specific descriptions of the present disclosure and examples to aid understanding and practice thereof, however, as described above, the following description and embodiments are presented as examples to aid understanding of the present disclosure, and the scope of the present disclosure is not limited or restricted thereto.

Before the detailed description of the present disclosure, terms or words used in the specification and claims should not be construed as being limited to the meanings of the related art or the initial meanings, and the present application should be interpreted in a meaning and concept consistent with the technical idea of the present disclosure in view of the principle that the concept of terms can be appropriately defined to explain its own application in its best mode.

Therefore, it should be understood that the configurations of the embodiments described herein are only preferred embodiments of the present disclosure and are not intended to change all the spirit of the present application, and that various equivalents and modifications may be substituted for them at the time of the present application.

In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, the terms "comprises," "comprising," or "having," and the like, are intended to specify the presence of stated features, integers, steps, components, or groups thereof, and are not to be construed as excluding the presence or addition of one or more other features or integers, steps, components, or groups thereof.

As used herein, the term "charged" may be used interchangeably with "added," "introduced," "flowed," and "injected" in this specification, and is understood to mean any material, such as raw materials, is introduced or added where desired.

Hereinafter, the metal M will be described as ¹ The sequence of the restoration method, the restoration system, and the embodiment of the present disclosure.

1. Metal M ¹ Is a reduction method of (2)

Reduction of metal M from metal oxides in accordance with the present disclosure ¹ The method of (2) may comprise:

forming molten salt of fluoride-based flux in the tank;

In the methods of the present disclosure, the molten salt of the fluoride-based flux may be less than the metal M ² With metal M ³ And the density of the metal oxide.

In the method of the present disclosure, the molten salt of the fluoride-based flux has a volatilization rate of 10 wt% or less, specifically 5 wt% or less, and more specifically 2 wt% or less at 1600 ℃ for 10 hours.

By using a molten salt of a fluoride-based flux, there is an environmental advantage in that no toxic chlorine gas is generated, and since its volatilization rate is low, the loss of the flux during the process is small, so that it is advantageous in terms of maintenance cost. In particular when combined with a chloride-based flux (e.g. CaCl ₂ Which has a volatility of about 74% by weight (FIG. 3)) for 10 hours at 1600℃The advantages of such fluoride-based fluxes can be more clearly understood. Here, the volatilization rate may be measured by standing at a specific temperature for a certain time and comparing the weights before and after the standing, but other methods known to those skilled in the art may be used, and the values in the case of using other methods may be appropriately converted according to the values in the present disclosure. However, since the flux of the present disclosure is used in the process of reducing metal by reacting metal oxide with the eutectic composition, the volatilization rate should be measured within the process temperature (900 ℃ to 1600 ℃) according to the present disclosure. In particular, because of the higher volatility at higher temperatures, it may be desirable to measure the volatility at 1600 ℃ (which is the highest of the allowable process temperatures) to ensure process stability.

In the method of the present disclosure, the fluoride-based flux may be a fluoride-based flux of one or more metals selected from alkali metals and alkaline earth metals, and by being in accordance with the target metal M ¹ And the reducing agent used are determined in consideration of the relative density difference, the volatilization rate, the convenience and safety of operation, and the like. For example, the fluoride-based flux may be selected from MgF ₂ 、CaF ₂ 、SrF ₂ And BaF ₂ One or more of them, and may in particular be CaF ₂ 。

In the method of the present disclosure, by using a metal M ² And metal M ³ And a molten salt of a fluoride-based flux having a density lower than that of the metal oxide, where the metal oxide reacts with the eutectic composition to reduce the metal M ¹ And at reduced metal M ¹ With metal M ² In the step of forming a liquid metal alloy therebetween, since the molten salt of the fluoride-based flux is located at the top of the tank, the eutectic composition and the metal oxide may not be exposed to the external environment, and inflow of oxygen from the outside may be prevented. Therefore, even in a normal air atmosphere other than the inert gas atmosphere, the metal M ¹ Also possible.

In addition, by using the fluoride-based flux having a low volatility, it is advantageous for large-scale industrialization because it allows harmful gas to be discharged in an acceptable amount even in a normal air atmosphere, thereby increasing the convenience and safety of operation and significantly reducing the corrosion degree of equipment as compared with the flux used in the related art.

Metal M ¹ The composition is not particularly limited, but may specifically be one selected from Ti, zr, hf, W, fe, ni, zn, co, mn, cr, ta, ga, nb, sn, ag, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb, ac, th, pa, U, np, pu, am, cm, bk, cf, es, fm, md and No, more specifically one selected from Ti, zr, W, fe, ni, zn, co, mn, cr, ta, er and No, even more specifically one selected from Ti, zr, W, fe, ni, zn, co, mn and Cr, and in particular Ti, zr, or W.

In the methods of the present disclosure, metal M ² Is not limited as long as it can be combined with the metal M ¹ Forming a eutectic phase, e.g. metal M ² May be one or more selected from Cu, ni, sn, zn, pb, bi, cd, and alloys thereof, and in particular Cu.

In the method of the present disclosure, a metal M is included ³ The reducing agent of (2) is not limited as long as it can reduce the metal M ¹ Of (2), e.g. metal M ³ May be one or more selected from Ca, mg, al, and alloys thereof. Specifically, metal M ³ Mg may be used.

In the methods of the present disclosure, the metal oxide may comprise a metal selected from M ¹ _x O _z And M ¹ _x M ³ _y O _z Wherein x and y are each a real number from 1 to 3 and z is a real number from 1 to 4.

For ease of understanding, non-limiting examples of the above metal oxides may include one selected from the group consisting of: zrO (ZrO) ₂ 、TiO ₂ 、MgTiO ₃ 、HfO ₂ 、Nb ₂ O ₅ 、Dy ₂ O ₃ 、Tb ₄ O ₇ 、WO ₃ 、Co ₃ O ₄ 、MnO、Cr ₂ O ₃ 、MgO、CaO、Al ₂ O ₃ 、Ta ₂ O ₅ 、Ga ₂ O ₃ 、Pb ₃ O ₄ SnO, nbO and Ag ₂ O, or a combination of two or more of these.

When using metal M ¹ And metal M ³ Is a complex oxide (M) ¹ _x M ³ _y O _z ) As metal oxide, by reacting with metal M ² And metal M ³ Is reacted with a eutectic composition to reduce metal M ¹ Can be faster. According to the findings of the present disclosure, in the use of a complex oxide (M ¹ _x M ³ _y O _z ) In the case of (a) and using M ¹ _x O _z The time required for the reduction may be reduced by at least 1/3 to 1/10 as compared with the case of (a). Namely, when metal M is used ¹ And metal M ³ When the composite oxide of (2) is used as the metal oxide, the reaction rate between the metal oxide and the eutectic composition can be higher than that of the metal M alone ¹ Is faster when the oxide is present. In addition, in using M ¹ _x M ³ _y O _z In the presence of a metal alloy that can more broadly regulate M in a liquid metal alloy produced in accordance with the present disclosure ¹ And M ² Is proportional to the ratio of the ratio. In addition, when M is used ¹ _x M ³ _y O _z When M is used ¹ _x O _z In comparison with the case of (2), M is used as a reducing agent ³ Is significantly reduced. For example, when Ti is used as the metal M ¹ Ca is used as metal M ³ Metal M when ¹ The oxide of (C) may be TiO ₂ And metal M ¹ With metal M ³ The composite oxide of (2) may be CaTiO ₃ 。

Unlike the kroll process in the related art, the process according to the present disclosure is different in that it uses a metal oxide as a raw material instead of a metal chloride. The raw materials commonly found in nature include the metal M ¹ For use in the Kroll processThe oxide involves a pretreatment process in which the metal oxide is replaced with chloride. When such a pretreatment process is performed, it itself causes an increase in process cost. In addition, hydrochloric acid is used in a pretreatment process of replacing metal oxide with chloride, which promotes corrosion of manufacturing equipment due to strong acidity, and during which toxic chlorine gas may be generated, which may cause environmental problems. Since the method according to the present disclosure does not require a pretreatment process of replacing the metal oxide with chloride, the process cost is lower than that of the kroll process, and has an advantage of not causing environmental problems.

In the methods of the present disclosure, metal M is reduced by reacting a metal oxide with a eutectic composition ¹ The process of (2) may be carried out in air or in fluoride. Since the density of the molten salt of the fluoride-based flux is lower than the densities of the eutectic composition and the metal oxide, the molten salt of the fluoride-based flux is located at the top of the tank, while the eutectic composition and the added metal oxide are located below the molten salt of the fluoride-based flux. Therefore, since the eutectic composition and the introduced metal oxide can exist in a state of not being exposed to the external environment due to the molten salt and the bath of the fluoride-based flux, reduction of the metal M by reacting the metal oxide with the eutectic composition can be performed even in a normal atmosphere other than an inert gas atmosphere ¹ Is a process of (2). In addition, since the volatilization rate of the molten salt of the fluoride-based flux is relatively low, even if the process is performed in an atmospheric atmosphere, the generation of toxic gas is reduced, and corrosion of equipment used in the process is significantly reduced, no harmful environment is formed to operators, and large-scale industrialization can be achieved.

In the method of the present disclosure, the reduction of the metal M may be performed at a temperature at which at least the fluoride-based flux may be melted ¹ Can produce a eutectic composition, and can perform reduction of metal M by reacting a metal oxide with the eutectic composition ¹ Is a process of (2). For example, the metal M is reduced by reacting a metal oxide with the eutectic composition ¹ Is too much to (a)The process may be performed at 900 ℃ or higher. Further, the method may be performed at a temperature lower than that at which the molten salt of the fluoride-based flux does not excessively evaporate, and may be performed at a temperature of 1800 ℃ or less, 1700 ℃ or less, 1600 ℃ or less, or 1600 ℃ or less in view of energy efficiency according to furnace heating. Thus, the metal M is reduced by reacting the metal oxide with the eutectic composition ¹ May be carried out in the range 900 to 1600 ℃.

As an example, when metal M ¹ Is Ti, metal oxide (M) ¹ _x O _z ) Is TiO ₂ Metal M ² Is Cu and metal M ³ In the case of Ca, the metal Ti is reduced according to the following schemes 1-1 and 1-2, and then the metal M can be separated ³ Oxide (M) ³ _a O _b ) And simultaneously obtaining the liquid metal alloy CuTi. Here, a and b are real numbers from 1 to 3, respectively.

Scheme 1-1]

2Ca+TiO ₂ ->Ti+2CaO

Schemes 1-2

Ti+Cu+2CaO- > CuTi (alloy) +2CaO (separation)

As another example, when metal M ¹ Is Ti, metal oxide (M) ¹ _x M ³ _y O _z ) Is CaTiO ₃ Metal M ² Is Cu and metal M ³ In the case of Ca, the metal Ti is reduced according to the following schemes 2-1 and 2-2, and then the metal M can be separated ³ Oxide (M) ³ _a O _b ) And simultaneously obtaining the liquid metal alloy CuTi.

Scheme 2-1]

2Ca+CaTiO ₃ ->Ti+3CaO

Scheme 2-2]

Ti+Cu+3CaO- > CuTi (alloy) +3CaO (separation)

Metal M produced according to the above reaction ³ Oxide (M) ³ _a O _b ) Is a by-product and to achieve a continuous process, continuous removal of the by-product is required. The by-product can be in molten saltCan not dissolve completely and may not be easy to remove the by-product or run the process continuously. The methods of the present disclosure may further include reducing the metal M by adding a slag-forming additive to form a metal oxide by reacting the metal oxide with the eutectic composition ¹ Slag of by-products produced in the process with molten salts of fluoride-based fluxes. When the slag is formed, the viscosity is relatively lowered and the fluidity is increased as compared with the case of a molten salt in which a by-product and a fluoride-based flux are present, and the slag containing the by-product can be continuously removed, and furthermore, a continuous process can be realized.

Examples of slag forming additives for achieving the above effect may include those selected from MgO, caO, feO, baO, siO ₂ And Al ₂ O ₃ One or more of the above, but is not limited thereto.

Reduction of metal M from metal oxides in accordance with the present disclosure ¹ The method of (2) may further comprise: forming a layer in which the liquid metal alloy is located at the bottom of the tank and separated from the eutectic composition, and continuously obtaining the liquid metal alloy through the lower portion of the tank; and forming a separate layer on top of the eutectic composition with the slag and continuously removing the slag through the top of the trough. By forming a layer in which the liquid metal alloy is located at the bottom of the trough and separated from the eutectic composition, the liquid metal alloy can be continuously tapped from the lower portion of the trough. Furthermore, the addition of the slag-forming additive causes the slag to form a separate layer on the upper portion of the eutectic composition, and the slag is continuously removed through the upper portion of the tank, so that byproducts generated during the reduction of the metal oxide can be continuously removed. Thus, by continuously removing from the tank the reaction product formed when the metal oxide is added to the eutectic composition, after a certain amount of metal oxide is added, the metal M can be obtained without interrupting the process by continuously adding the metal oxide instead of terminating all the reactions ¹ And metal M ² Is a liquid metal alloy of (a). At this time, a method known to those skilled in the art may be used to continuously obtain a liquid metal alloy through the lower portion of the bath or continuously remove slag through the upper portion of the bath.

After the slag is removed by removing the slag and the fluoride-based flux through the upper portion of the tank, the fluoride-based flux is replenished during the process operation to maintain the balance of the reaction system and to achieve a continuous process. At this time, the fluoride-based flux may be continuously separated from the removed slag, and the separated fluoride-based flux may be added again to the tank.

The resulting liquid metal alloy may be cooled to solidify. Due to the liquid metal alloy in which the metal M is ¹ And metal M ² In a homogeneously mixed state, the alloy structure obtained after solidification is greatly affected by the cooling rate of the liquid metal alloy. The cooling rate may stably form an intermetallic phase, which may be slowly cooled to room temperature at a rate of 20 deg.c/min in a temperature range where the process according to the present disclosure is performed, so that M therein may be generated ¹ And M ² Is a structure in which intermetallic phases of the two are continuously connected to each other. When the cooling rate is too fast beyond the recommended range, a dispersion is obtained in which a large amount of fine intermetallic particles are dispersed and incorporated into the metal M ¹ The structure in the matrix, and therefore there is a possibility that the metal M may not be formed ¹ Risk of a continuous and fast mass transfer path. When cooled too slowly, the benefit of the microstructure is negligible, but as the time required for the process becomes too long, the cooling rate may be substantially 1 ℃/minute or greater, more substantially 5 ℃/minute or greater.

The method according to the present disclosure may further comprise obtaining a metal M containing ¹ And metal M ² Then to the obtained alloy containing metal M ¹ And metal M ² Is subjected to electrorefining to obtain metal M ¹ 。

Obtaining metal M by performing electrorefining ¹ It is possible to solidify the obtained liquid metal alloy to obtain a solid alloy, to subject the solid alloy to electrolytic refining, and to recover the metal M from the alloy ¹ 。

In some cases, prior to electrorefining the solidified alloy, the flux that may remain in the liquid metal alloy may be removed, for example, by heat treating the liquid metal alloy in a vacuum or inert gas atmosphere to distill off the flux. The distillation temperature (heat treatment temperature) is not particularly limited as long as the temperature is higher than the boiling point of the flux used in the system of the present disclosure, for example, the temperature may be 2500 ℃ or higher, and depressurization may be performed to reduce the distillation temperature and improve the efficiency. In order to effectively prevent the liquid metal alloy from being oxidized again, it may be advantageous to conduct the distillation under vacuum and under an inert gas.

The present disclosure provides a metal M obtained by any method described in the specification of the present disclosure or a combination thereof ¹ And metal M ² Is a metal alloy of (a) and (b). For example, metal M ¹ And metal M ² Can be obtained by reducing metal M from metal oxides ¹ Obtained by a method of (1), the method comprising: forming molten salt of fluoride-based flux in the tank; adding metal M into the tank ¹ Metal M forming a eutectic phase ² And comprises a metal M ³ To produce metal M ² And metal M ³ Is a eutectic composition of (2); and reducing the metal M by reacting the metal oxide with the eutectic composition ¹ And using reduced metal M ¹ And M ² Forming a liquid metal alloy. For example, metal M ¹ And metal M ² Can be manufactured in the atmosphere or obtained from a process carried out in the range 900 to 1600 ℃. For example, metal M ¹ And metal M ² Can be obtained by a process comprising: reduction of metal M by adding slag forming additives to form molten salts and reacting metal oxides with the eutectic composition ¹ Slag of by-products generated in the process of (2). Furthermore, metal M of the present disclosure ¹ And metal M ² May be obtained by any of the methods described in the specification of the present disclosure or a combination thereof.

In one embodiment, the metal M ¹ And metal M ² Is a metal alloy having 0.1 wt% or less, specifically 0.01 wt% or less, and more specifically 0.001 wt% or less based on the total weight of the metal alloyA high quality metal alloy with a residual content. In addition, metal M ¹ And metal M ² Is a high quality metal alloy having an oxygen content of 1800ppm or less, specifically 1500ppm or less, and more specifically 1200ppm or less.

Furthermore, in the liquid alloy (M ¹ And M ² A liquid metal alloy) the metal alloy itself can be used as the final product. M is M ¹ Are generally used industrially in the form of alloys and when M ¹ When it may be produced with only a single metal, as in the croll process in the related art, a post-treatment process of alloying with another metal may be required. However, the present disclosure has high process efficiency because M can be used at the same time as the recovery without such a post-treatment process ¹ And M ² In the form of a metal alloy to obtain the final product. In addition, the reduced metal produced by the kroll process in the related art has a low yield of low oxygen content high quality (grade 1) metal and has a relatively high residual oxygen content. Therefore, even when a metal alloy is produced using a reduced metal produced by the kroll process, there is a limit in that the residual oxygen content is high. On the other hand, most metal alloys produced according to the present disclosure have very low oxygen content and high quality grade. For example, when M ¹ In the case of Ti, the method according to the present disclosure yields up to 98% or more of the high-quality metal, but the kroll method in the related art is known to yield less than 50% of the high-quality metal, whereby the advantages of the present disclosure can be more clearly understood.

2. For reduction of M ¹ Is a system of (2)

a groove;

molten salt of fluoride-based flux in the tank;

Metal M ² Can be combined with metal M ¹ Forming a eutectic phase.

In one embodiment, the bath may be an electrolytic reduction bath or the like, a high frequency melting furnace may be used to achieve a desired temperature range, or an electric furnace may be used according to a target metal alloy, but is not limited thereto. All tanks and furnaces which are easy to the person skilled in the art can be used in view of the reaction temperature range, reactivity, etc.

In one embodiment, for smooth separation of the liquid metal alloy and the reaction byproducts, the mass ratio of molten salt of the fluoride-based flux to the reaction byproducts may be 5:1 to 2:1, preferably 3:1, but is not limited thereto.

In one embodiment, the flux may further comprise an oxide of one or two or more metals selected from alkali metal groups and alkaline earth metal groups as a reactive additive. The reactive additive may be contained in an amount of 0.1 to 25 wt% based on the total weight of the flux. The reactive additive may include, but is not limited to LiO, naO, srO, csO, KO, caO, baO, or mixtures thereof. The reactive additives contained in the flux may make the metal oxide contained in the raw material module easier to reduce.

In one embodiment, a trough similar to that of fig. 1 may be used to perform the alloy metal production methods of the present disclosure. For example, a fluoride-based flux is charged into the tank 1 and melted to form molten salt 5, and will react with the metal M ¹ Metal M forming a eutectic phase ² Comprising a metal M ³ Is added to the tank to produce metal M ² And metal M ³ Is a eutectic composition 6 of (2). Since the density of the molten salt of the fluoride-based flux is less than the density of the eutectic composition, the molten salt 5 of the fluoride-based flux is located on the eutectic composition 6. Thereafter, the raw material feeding apparatus 1 will be usedMetal oxide 10 is charged into a tank and the oxide is reacted with eutectic composition 6 to produce metal M ¹ With metal M ² And after the reaction is completed, adding a slag-forming additive 9 to the reaction by-product between the liquid metal alloy and the flux to slag the by-product. Thereafter, the liquid metal alloy 7 is obtained through the lower part of the trough via a tapping section 8 connected to the lower part of the trough. Since the slag is located at the upper portion of the tank, about 50% to 90% of the slag is removed by the inclined tank, and a new fluoride-based flux is added to about 10% to 50% of the residual slag by the flux feeding means 2 to form a new flux layer. Thereafter, the metal oxide 10 is charged into the tank and reacted with the eutectic composition 6 using the raw material feeding apparatus 1 again, and the process of producing the liquid metal alloy 7 may be repeated. The liquid metal alloy 7 produced in the lower part of the bath is continuously obtained through the tapping section 8 in the lower part of the bath at all stages of the process, for example before the slag is removed or the bath is tilted to remove slag. The tank may use, for example, a high-frequency melting furnace 3 to promote stirring, but is not limited thereto.

3. Examples

Hereinafter, examples will be described in detail, by which the actions and effects of the present disclosure will be demonstrated. However, the following examples are presented as examples of the present disclosure only, and the scope of the present disclosure is not thereby determined.

Example 1]

Using the system shown in fig. 1 and following the process sequence of fig. 2. Flux CaF ₂ (40.8 g) was weighed in a resistance heating furnace, added to the tank, and then heated to about 1415 ℃ to produce a molten salt of the fluoride-based flux (fig. 2 a).

52.8g and 72.3g of Cu(s) and Ca(s) were weighed into a tank and melted to produce a eutectic composition (FIG. 2 b).

Weigh 72.1g of TiO ₂ (average particle size 100 μm) as metal oxide and allowed to react for 10 hours (FIGS. 2c and 2 d).

To remove by-products, 200g of Al was added to the slag ₂ O ₃ Powder and 100g of CaO was used as a slag forming additive (fig. 2 e) and then cooled slowly in a furnace. The process is carried out in an air atmosphere.

Example 2]

60g and 65.5g of Cu(s) and Ca(s) were weighed into a tank and melted to produce a eutectic composition (FIG. 2 b).

111g of CaTiO are weighed ₃ As metal oxide and allowed to react for 2 hours (fig. 2c and 2 d).

To remove by-products, 200g of Al was added to the slag ₂ O ₃ The powder and 100g of CaO were used as slag-forming additives (FIG. 2 e) and then cooled slowly in a furnace. The process is carried out in an air atmosphere.

Experimental example 1]

The volatility of fluoride-based fluxes and chloride-based fluxes were measured. 500g of each flux (weight before charging) was weighed and charged into a crucible, and the weight of the flux (weight after charging) after charging the crucible into a melting furnace and placing the flux at 1600 ℃ for 10 hours was measured. The volatility was evaluated using the following method.

-volatilization rate: (weight before charging-weight after charging)/(weight before charging) ×100%

As a result, caF used as a fluoride-based flux was determined ₂ Shows a low volatility of 1.8 wt% and a chloride-based flux CaCl ₂ Showing a high volatility of about 74 wt% (figure 3).

Regarding fluoride-based flux CaF measured in various temperature ranges ₂ Is based on the volatility of the solvent and on the CaCl of the chloride ₂ As can be seen, the vapor pressure of the fluoride-based flux is significantly low (fig. 4) based on the process temperature at which the process is performed, indicating that the rate of volatilization is significantly low in the fluoride-based flux process.

Thus, it is preferable to perform the efficient process as described above using a fluoride-based flux having a low volatilization rate.

Experimental example 2

The characteristics of the alloys obtained in examples 1 and 2 were evaluated using the following methods.

Recovery rate: 100- { (1 st wt% to 2 nd wt)/2 nd wt×100% of the total weight of the composition)

Residual impurity content: the produced alloy was cut and the interior of the alloy was determined using energy dispersive spectroscopy.

-oxygen content: the oxygen content present in the alloy was measured using ELTRA ONH 2000.

TABLE 1

* 1 st weight: the total amount of Cu added to the initial electrolytic bath + the chemically theoretical reduction amount of Ti contained in the metal oxide.

* Weight 2: total amount of CuTi obtained

As can be seen from the results of table 1, the alloy of the example produced according to the present disclosure shows high recovery rate, and a high purity alloy substantially free of metal or oxygen used as a reducing agent is obtained. That is, it was confirmed that, unlike the existing process which can be performed only in an inert gas atmosphere as above, even if the process is performed in an air atmosphere, the recovery rate of the target metal is better and the oxygen content is significantly lower.

While the present disclosure has been described with reference to embodiments, those skilled in the art will be able to make various applications and modifications within the scope of the present disclosure based on the above information.

Claims

1. Reduction of metal M from metal oxides ¹ Comprises the following steps:

forming molten salt of fluoride-based flux in the tank;

adding the metal M into the groove ¹ Metal M forming a eutectic phase ² And comprises a metal M ³ To produce the metal M ² And the metal M ³ Is a eutectic composition of (2); and

reducing the metal M by reacting the metal oxide with the eutectic composition ¹ And using reduced metal M ¹ And M ² Forming a liquid metal alloy;

wherein the density of the molten salt is less than the density of the eutectic composition and the metal oxide.

2. The method of claim 1 wherein the molten salt has a volatility of 10% by weight or less for 10 hours at 1,600 ℃.

3. The method of claim 1, wherein the fluoride-based flux is selected from MgF ₂ 、CaF ₂ 、SrF ₂ And BaF ₂ One or more of the following.

4. The method of claim 3, wherein the fluoride-based flux is CaF ₂ 。

5. The method of claim 1, wherein the metal M ¹ Is one or more selected from the following: ti, zr, hf, W, fe, ni, zn, co, mn, cr, ta, ga, nb, sn, ag, la, ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb, ac, th, pa, U, np, pu, am, cm, bk, cf, es, fm, md and No.

6. The method of claim 1, wherein the metal M ² Is one or more selected from Cu, ni, sn, zn, pb, bi, cd, and alloys thereof.

7. The method of claim 6, wherein the metal M ² Is Cu.

8. The method of claim 1, wherein the metal M ³ Is one or more selected from Ca, mg, al, and alloys thereof.

9. The method of claim 1, wherein the metal oxide comprises a metal selected from the group consisting of M ¹ _x O _z And M ¹ _x M ³ _y O _z One or more of the following;

wherein x and y are real numbers of 1 to 3, and z is a real number of 1 to 4, respectively.

10. The method of claim 1, wherein the metal M is reduced by reacting the metal oxide with the eutectic composition ¹ The process of (2) is carried out in air or in fluoride.

11. The method of claim 1, wherein the metal M is reduced by reacting the metal oxide with the eutectic composition ¹ The process of (2) is carried out in the range of 900 ℃ to 1,600 ℃.

12. The method of claim 1, further comprising forming the molten salt by adding a slagging additive and reducing the metal M by reacting the metal oxide with the eutectic composition ¹ Slag of by-products generated in the process of (2).

13. The method of claim 12, wherein the slagging additive comprises a compound selected from MgO, caO, feO, baO, siO ₂ And Al ₂ O ₃ One or more of the following.

14. The method of claim 12, further comprising:

forming a layer in which the liquid metal alloy is located at the bottom of the tank and separated from the eutectic composition, and continuously obtaining the liquid metal alloy through the lower portion of the tank; and

forming a separate layer on top of the eutectic composition with the slag and continuously removing the slag through the top of the trough.

15. The method of claim 1, further comprising electrorefining the liquid metal alloy to produce the metal M ¹ 。

16. A metal obtained by the method according to claim 15.

17. A metal alloy obtained by the method according to claim 1.

18. The method of claim 17, wherein the metal M is based on the total weight of the metal alloy ³ Is 0.1 wt% or less, and the oxygen content is 1,800ppm or less.

19. A method for reducing a metal M from a metal oxide ¹ Comprises:

a groove;

a molten salt of a fluoride-based flux located in the tank;

a metal M located in the lower part of the molten salt ² And metal M ³ Is a eutectic composition of (2); and

the metal M located below the eutectic composition ¹ And the metal M ² Is a liquid metal alloy of (a);

wherein the density of the molten salt is less than the density of the metal oxide,

the metal oxide and the metal M ³ Reaction to reduce the metal M ¹ A kind of electronic device

The metal M ² With the metal M ¹ Forming a eutectic phase.