Method and system for reducing refractory metal oxides using fluoride-based electrolytes

Abstract

The present invention relates to a method for reducing metal oxides, and more particularly, to a method for reducing metal oxides, which can be operated in air, instead of the conventional inert gas atmosphere production process, in producing high-quality alloy metals from metal oxides as raw materials, and which uses an environmentally friendly method, thereby maximizing efficiency and being easily commercialized.

Description

[Technical field]

[0001] The present invention relates to a method for reducing a high-melting point metal oxide, and relates to a method and system for reducing a metal oxide that can be operated in air, breaking away from the conventional manufacturing process using an inert gas atmosphere, and that can maximize efficiency and be easily commercialized by using an environmentally friendly method. [Background technology]

[0002] When a metal typically known in the art is referred to as any metal "M", the metal M can be obtained by reducing a raw material such as an oxide or halide. Among the methods for producing a desired metal M, the relatively well-known method and the most widely and commonly used method in the art is the so-called Kroll process.

[0003] Typically, the Kroll process can be summarized as using molten magnesium as a reducing agent to reduce the chloride of the target metal M, such as titanium chloride or zirconium chloride, to titanium or zirconium. In this regard, more detailed information on the Kroll process can be found in U.S. Patent No. 5,035,404.

[0004] The Krol process uses chlorides as raw materials, and thus produces chlorine gas and magnesium chloride as by-products during the process. Among these by-products, chlorine gas is an environmental problem that can cause fatal problems to the human body and is considered to be a representative problem of the Krol process, while magnesium chloride causes process problems such as rapid corrosion of reaction vessels, such as electrolytic cells, melting furnaces, and crucibles.

[0005] Thus, the Kroll process has the disadvantages of requiring additional equipment to meet environmentally acceptable standards and of being expensive to operate due to the frequent changeover of reaction vessels.

[0006] In another aspect, the Kroll process produces metal in a sponge form containing many voids, making it very difficult to control oxygen that may be present in the metal, i.e., the Kroll process has limitations in obtaining high-purity metals.

[0007] To replace these existing processes, electrolytic refining processes have been researched, which have the advantage of being simpler than existing processes, since they directly reduce metal oxides and do not generate chlorine gas, but have the problem that the form of the 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, ingots must be produced using a process such as vacuum arc melting in a state where the recovered metal powder produced by the refining process is not exposed to the atmosphere, and the specific surface area of ​​the recovered metal must be reduced, but in this case, it is difficult to set up large-scale industrial equipment and there are practical difficulties in terms of cost.

[0008] Meanwhile, the LCE (Liquid Copper Aided Electrolysis) process (see Patent Documents 1 to 3), which was proposed to solve the problems of the above-mentioned processes, proposes a method of producing an alloy of a target metal through an electrolytic reduction process using a reducing agent, and then refining the target metal with high purity through electrolytic refining. However, this electrolytic reduction process also has problems in that the equipment corrodes quickly because a chlorine-based electrolyte with a high volatility is used, which causes cost problems, and chlorine gas is generated, which requires operation in a closed system with an argon gas atmosphere. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Patent No. 5,035,404 [Patent Document 2] Korean Patent No. 10-1757626 [Patent Document 3] Korean Patent No. 10-1793471 [Patent Document 4] Korean Patent No. 10-1878652 [Non-patent literature]

[0010] [Non-Patent Document 1] Antoine Allanore, Journal of The Electrochemical Society,162(1)(2015)E13-E22 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been proposed to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a method and system for producing high-quality alloy metal by reducing a high-melting point metal oxide in an environmentally friendly and highly efficient atmospheric environment using a fluoride-based electrolyte.

[0012] The present invention relates to a method for producing a eutectic phase of metals M 1 and metal M 2 The liquid metal alloy is produced by the eutectic reaction. 1 Since the melting point of M is low, reduction can be effectively performed at a relatively low temperature, resulting in considerable energy savings, which can lead to cost savings. 1 and M. 2 Since the metal alloy is obtained in the liquid state, the metal alloy itself can be used as the final product. Alternatively, the obtained metal alloy can be electrolytically refined to produce metal M. 1 The liquid alloy thus obtained can be thoroughly isolated from an environment in which oxygen may be present, and thus contamination by oxygen can be significantly prevented. 1 It is possible to obtain the following.

[0013] The present invention aims to provide a method for reducing alloy metals which can increase the production rate of high-quality final products compared to the prior art, is highly energy efficient, and is advantageous for commercialization. [Means for solving the problem]

[0014] According to the present invention, a metal M is produced from a metal oxide. 1 A method is provided for reducing

[0015] According to the present invention, the metal M is obtained by extracting the metal oxide from the metal M. 1 The method for reducing

[0016] forming a molten salt of a fluoride-based electrolyte in an electrolytic cell;

[0017] The metal M 1 Metal M that forms a eutectic phase with 2 and metal M 3 A reducing agent containing the metal M 2 and metal M 3 and producing a eutectic composition of

[0018] The metal oxide is reacted with the eutectic composition to form a metal M 1 The reduced metal M 1 Metal M 2 and forming a liquid metal alloy;

[0019] The metal oxide is converted into a metal M 1 The molten salt of the fluoride-based electrolyte is a method for reducing a metal M 2 and metal M 3 The density of the eutectic composition and metal oxides may be less than that of the eutectic composition and metal oxides.

[0020] According to the present invention, the molten salt of the fluoride-based electrolyte may have a volatilization rate of 10 wt % or less, specifically a volatilization rate of 5 wt % or less, and more specifically a volatilization rate of 2 wt % or less at 1,600° C. for 10 hours.

[0021] According to the present invention, the fluoride-based electrolyte may be one or more selected from the group consisting of MgF2, CaF2, SrF2, and BaF2, and may be CaF2 in particular.

[0022] According to the present invention, the metal M 1 may be one selected from the group consisting of 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.

[0023] According to the present invention, the metal M 2 may be one or more selected from the group consisting of Cu, Ni, Sn, Zn, Pb, Bi, Cd, and alloys thereof, and more particularly may be Cu.

[0024] According to the present invention, the metal M 3 may be one or more selected from the group consisting of Ca, Mg, Al, and alloys thereof, and more particularly may be Mg.

[0025] According to the present invention, the metal oxide is M 1 x O z and M. 1 x M 3 y O z wherein x, y are each a real number from 1 to 3, and z is a real number from 1 to 4.

[0026] According to the present invention, the metal oxide is reacted with the eutectic composition to obtain a metal M 1 The reduction process can be carried out in air or in fluoride.

[0027] According to the present invention, the metal oxide is reacted with the eutectic composition to obtain a metal M 1The reduction process can be carried out in the range of 900 to 1600°C.

[0028] According to the present invention, the metal M is obtained by extracting the metal oxide from the metal M. 1 The method for reducing the metal M is to introduce a slagging additive to react the metal oxide with the eutectic composition to produce the metal M. 1 The method may further include forming a slag of the molten salt with by-products generated in the process of reducing the molten salt, and more specifically, the slagging additive may include one or more selected from the group consisting of MgO, CaO, FeO, BaO, SiO2, and Al2O3.

[0029] According to the present invention, the liquid metal alloy is located at the bottom of the electrolytic bath and forms a layer separated from the eutectic composition, and the liquid metal alloy is continuously obtained through a lower portion of the electrolytic bath;

[0030] The slag may form a distinct layer on top of the eutectic composition, and the method may further include continuously removing the slag through an upper portion of the electrolytic cell.

[0031] According to the present invention, the liquid metal alloy is electrolytically refined to obtain M 1 The method may further include the step of manufacturing the

[0032] The metal alloy or metal according to the present invention may be obtained by any method or combination of methods disclosed herein, and more particularly, the metal alloy or metal may be obtained by a weight ratio of M 3 % or less, specifically 0.01% or less, more specifically 0.001% or less, and an oxygen content of 1,800 ppm or less, specifically 1,500 ppm or less, and even more specifically 1,200 ppm or less.

[0033] Metal M from the metal oxide according to the present invention 1 The system for returning

[0034] Electrolytic cell and

[0035] a molten salt of a fluoride-based electrolyte located in the electrolytic cell;

[0036] The metal M located under the molten salt 2 and metal M 3 and a eutectic composition of

[0037] The metal M located in the lower part of the eutectic composition 1 and the metal M 2 and a liquid metal alloy of

[0038] The density of the molten salt may be less than the density of the metal oxide, and the metal oxide and the metal M 3 reacts to form the metal M 1 is reduced to obtain the metal M 2 is the metal M 1 It is possible to form a eutectic phase with Effect of the Invention

[0039] The present invention provides a system optimized for obtaining desired metals from metal oxides without using any chlorides as metal chlorides or electrolytes, and a method for producing such metals. Therefore, the present invention can solve the environmental problems of the Kroll process and the cost problems associated with corrosion of the electrolytic cell.

[0040] The present invention relates to a method for producing a eutectic phase of metals M 1 and metal M 2 The liquid metal alloy is produced by the eutectic reaction. 1 Because of the lower melting point of , reduction can be carried out effectively at relatively low temperatures, resulting in significant energy savings which can translate into cost savings.

[0041] The present invention relates to a method for producing a liquid alloy (metal M 1 and metal M 2Since the metal alloy is obtained in the liquid state, the metal alloy itself can be used as the final product. Alternatively, the obtained metal alloy can be electrolytically refined to produce metal M. 1 The liquid alloy thus obtained can be thoroughly isolated from an environment in which oxygen may be present, and thus contamination by oxygen can be significantly prevented. 1 It is possible to obtain the following.

[0042] In addition, the present invention allows easy adjustment of the ratio of the target alloy, and the final alloy metal can be used to produce high purity metal through electrolytic refining techniques.

[0043] The present invention is a method for producing high-quality metal M 1 The recovery rate is high and the final product can be easily separated from the reaction product, making continuous operation possible. [Brief description of the drawings]

[0044] [Figure 1] FIG. 2 is a process diagram illustrating a process for reducing metal M1 from a metal oxide according to one embodiment of the present invention. [Diagram 2] 1 is a diagram illustrating a process flow of a method for reducing a metal M1 from a metal oxide according to an embodiment of the present invention. [Diagram 3] 1 is a diagram and a table showing the difference in volatility between fluoride-based electrolytes and chloride-based electrolytes. [Figure 4] 1 is a diagram showing the vapor pressure of a fluoride-based electrolyte and a chloride-based electrolyte relative to temperature. [Diagram 5] 1 is a photograph of a metal alloy manufactured according to an embodiment of the present invention. [Figure 6] 1 shows a diagram and a result table of elemental analysis of the inside of a metal alloy manufactured according to an embodiment of the present invention, which was performed by cutting the alloy and then using an energy dispersive spectrometer (EDS). [Figure 7]1 is a table showing the results of measuring the oxygen content present in the metal alloy produced according to Example 2 of the present invention using an ELTRA ONH2000. Specific Modes for Carrying Out the Invention

[0045] Hereinafter, the intention, action, and effect of the present invention will be described in detail through specific explanations and examples for carrying out the present invention, which will help understand the embodiments of the present invention. However, the following explanations and examples are presented as examples for helping understand the present invention as described above, and are not intended to define or limit the scope of the invention.

[0046] Before describing the present invention in detail, the terms and words used in the specification and claims should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a manner that is consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to best describe his / her own invention.

[0047] Therefore, it should be understood that the configuration of the embodiment described in this specification is merely one of the most preferred embodiments of the present invention and does not represent the entire technical idea of ​​the present invention, and therefore, at the time of this application, there may be various equivalents and modifications that can replace these.

[0048] In this specification, the singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, the terms "comprise", "provide", "have", and the like are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the possibility of the presence or addition of one or more different features, numbers, steps, components, or combinations thereof.

[0049] The term "charging" as used herein may be used interchangeably with "introducing," "introducing," "inflowing," and "injecting" herein and may be understood to mean delivering or putting any substance, such as a raw material, into a required location.

[0050] In the following, metal M 1 The present invention will be described in detail in the order of a reduction method, a reduction system, and examples.

[0051] 1.Metal M 1 How to redeem

[0052] Metal M from the metal oxide according to the present invention 1 The method for reducing

[0053] forming a molten salt of a fluoride-based electrolyte in an electrolytic cell;

[0054] The metal M 1 Metal M that forms a eutectic phase with 2 and metal M 3 A reducing agent containing the metal M 2 and metal M 3 and producing a eutectic composition of

[0055] The metal oxide is reacted with the eutectic composition to form a metal M 1 The reduced metal M 1 Metal M 2 and forming a liquid metal alloy.

[0056] In the method of the present invention, the molten salt of the fluoride-based electrolyte is a metal M 2 and metal M 3 The density of the eutectic composition and metal oxides may be less than that of the eutectic composition and metal oxides.

[0057] In the method of the present invention, the molten salt of the fluoride-based electrolyte may have a volatilization rate of 10 wt % or less, specifically a volatilization rate of 5 wt % or less, and more specifically a volatilization rate of 2 wt % or less at 1,600° C. for 10 hours.

[0058] The use of the molten salt of the fluoride-based electrolyte has an environmental advantage of not generating toxic chlorine gas, and is advantageous in terms of maintenance costs because the electrolyte is less lost during the process due to its low volatility. In particular, the advantage of the fluoride-based electrolyte can be more clearly understood when compared with a chloride-based electrolyte, for example, CaCl2, which has a volatility of about 74% by weight at 1,600°C for 10 hours (FIG. 3). Here, the volatility can be measured by leaving the electrolyte at a specific temperature for a certain period of time and comparing the weight before and after leaving the electrolyte, but other methods well known to ordinary engineers may be used without any problem, and values ​​when using other methods may be appropriately converted to values ​​in the present invention. However, since the electrolyte of the present invention is used in the process of reducing metal by reacting a metal oxide with a eutectic composition, the volatility must be measured within the process temperature (900 to 1600°C) according to the present invention. In particular, since the volatility increases as the temperature increases, it may be preferable to measure the volatility at 1600°C, the highest allowable process temperature, in order to ensure process stability.

[0059] In the method of the present invention, the fluoride-based electrolyte may be a fluoride-based electrolyte of one or more metals selected from the group consisting of alkali metals and alkaline earth metals, and the target metal M 1 The fluoride electrolyte may be determined in consideration of the relative density difference, volatility, convenience of operation, safety, etc., depending on the reducing agent used. The fluoride electrolyte may be, for example, one or more selected from the group consisting of MgF2, CaF2, SrF2, and BaF2, and may be CaF2 in particular.

[0060] In the method of the present invention, the metal M 2 and metal M 3 By using a fluoride-based electrolyte molten salt having a density lower than that of the eutectic composition of and the metal oxide, the metal oxide reacts with the eutectic composition to form the metal M 1 is reduced, and the reduced metal M 1 and metal M 2In the stage where the liquid metal alloy is formed, the molten salt of the fluoride-based electrolyte is located in the upper part of the electrolytic cell, so that the eutectic composition and the metal oxide cannot be exposed to the external environment, and oxygen inflow from the outside can be prevented. This makes it possible to immerse the metal M in an ordinary air atmosphere, not an inert gas atmosphere, and to immerse the metal M in an ordinary air atmosphere. 1 A reduction step of

[0061] Furthermore, by using a fluoride-based electrolyte with low volatility, harmful gases are discharged in an acceptable amount even in normal atmospheric conditions, improving the convenience and stability of operation, and the degree of equipment corrosion can be significantly reduced compared to conventional electrolytes, which is advantageous for large-scale industrialization.

[0062] The metal M 1 is not particularly limited, and specifically may be one selected from the group consisting of 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 may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, Cr, Ta, Er, and No, even more specifically may be one selected from the group consisting of Ti, Zr, W, Fe, Ni, Zn, Co, Mn, and Cr, and particularly specifically may be Ti, Zr, or W.

[0063] In the method of the present invention, the metal M 2 is metal M 1 There is no limitation as long as it can form a eutectic phase with metal M. 2 may be one or more selected from the group consisting of Cu, Ni, Sn, Zn, Pb, Bi, Cd, and alloys thereof, and more particularly may be Cu.

[0064] In the method of the present invention, the metal M 3 The reducing agent containing the metal M 1There is no limitation as long as it can reduce a metal oxide containing a metal M 3 The metal M may be one or more selected from the group consisting of Ca, Mg, Al, and alloys thereof. 3 can be Mg.

[0065] In the method of the present invention, the metal oxide is M 1 x O z and M. 1 x M 3 y O z where x, y are each a real number from 1 to 3, and z is a real number from 1 to 4.

[0066] To aid in understanding, non-limiting examples of the metal oxides can include one or a combination of two or more selected from the group consisting of ZrO2, TiO2, MgTiO3, HfO2, Nb2O5, Dy2O3, Tb4O7, WO3, Co3O4, MnO, Cr2O3, MgO, CaO, Al2O3, Ta2O5, Ga2O3, Pb3O4, SnO, NbO, and Ag2O.

[0067] Metal M as metal oxide 1 and metal M 3 The composite oxide (M 1 x M 3 y O z ) when using metal M 2 and metal M 3 reacts with the eutectic composition of metal M 1 The present invention has confirmed that the reduction process of the composite oxide (M 1 x M 3 y O z ), M 1 x O zThe time required for reduction can be reduced to at least 1 / 3 to 1 / 10 as compared with the case where a metal oxide is used. 1 and metal M 3 When using a composite oxide of metal M, the reaction rate of the metal oxide with the eutectic composition is 1 This can be even faster than using only the oxide of M. 1 x M 3 y O z When using M in the liquid metal alloy produced by the present invention, 1 and M. 2 This has the advantage that the ratio of M can be adjusted more widely. 1 x M 3 y O z When using M 1 x O z Compared to using M as a reducing agent 3 For example, the amount of metal M required is significantly reduced. 1 Ti is used as the metal M 3 When Ca is used as the 1 The oxide of is TiO2, the metal M 1 and metal M 3 The composite oxide may be CaTiO3.

[0068] The method according to the present invention differs from the conventional Kroll process in that it uses metal oxides instead of metal chlorides as raw materials. Usually, raw materials found in nature are metal M 1However, in order to use it in the Kroll process, a pretreatment process is required to convert such metal oxides to chlorides. The pretreatment process itself increases the process cost. Furthermore, hydrochloric acid is used in the pretreatment process to convert metal oxides to chlorides, but the strong acidity promotes corrosion of the manufacturing equipment and may generate toxic chlorine gas during the process, which may cause environmental problems. The method according to the present invention does not require a pretreatment process to convert metal oxides to chlorides, and therefore has the advantages of lower process cost and no environmental problems compared to the Kroll process.

[0069] In the method of the present invention, a metal oxide is reacted with a eutectic composition to form a metal M 1 The process of reducing the metal oxide can be carried out in the atmosphere or in a fluoride. Since the density of the molten salt of the fluoride-based electrolyte is lower than the density of the eutectic composition and the metal oxide, the molten salt of the fluoride-based electrolyte is located at the upper stage of the electrolytic cell, and the eutectic composition and the metal oxide added are located below the molten salt of the fluoride-based electrolyte. As a result, the eutectic composition and the metal oxide added can exist in a state that is not exposed to the external environment due to the molten salt of the fluoride-based electrolyte and the electrolytic cell, so that even in normal air, not in an inert gas atmosphere, the metal oxide can be reacted with the eutectic composition to produce the metal M. 1 Furthermore, since the volatility of the molten salt of the fluoride-based electrolyte is relatively low, even if the process is carried out in an air atmosphere, the generation of toxic gas is reduced, so that the corrosion of the equipment used in the process is significantly reduced, and a dangerous environment is not created for the operators, which is advantageous in that it can be industrialized on a large scale.

[0070] In the method of the present invention, the metal M 1 The method for reducing metal M can be achieved by melting a fluoride-based electrolyte, producing a eutectic composition, and reacting a metal oxide with the eutectic composition. 1 For example, the metal oxide is reacted with the eutectic composition to reduce the metal M. 1The process of reducing the metal M may be carried out at 900°C or higher. In addition, as long as the temperature is below the temperature at which the molten salt of the fluoride-based electrolyte does not evaporate excessively, the process may be carried out at 1800°C or lower, 1700°C or lower, or 1600°C or lower, taking into consideration the energy efficiency of heating the furnace. Therefore, the process of reducing the metal M by reacting the metal oxide with the eutectic composition may be carried out at 1600°C or lower. 1 The reduction process can be carried out in the range of 900 to 1600°C.

[0071] As an example, the metal M 1 is Ti, metal oxide (M 1 x O z ) is TiO2, metal M 2 is Cu, metal M 3 When is Ca, metal Ti is reduced according to the following reaction formula 1-1 and reaction formula 1-2, and then liquid metal alloy CuTi is obtained while metal M is reduced according to the following reaction formula 1-2. 3 Oxide (M 3 a O b ) can be separated, where a and b are real numbers from 1 to 3.

[0072] (Reaction Scheme 1-1) 2Ca+TiO2→Ti+2CaO

[0073] (Reaction Scheme 1-2) Ti+Cu+2CaO→CuTi(alloy)+2CaO(separated)

[0074] As yet another example, metal M 1 is Ti, metal oxide (M 1 x M 3 y O z ) is CaTiO3, metal M 2 is Cu, metal M 3 When is Ca, metal Ti is reduced according to the following reaction formula 2-1 and reaction formula 2-2, and then liquid metal alloy CuTi is obtained while metal M is reduced according to the following reaction formula 2-2. 3 Oxide (M 3 a O b) can be separated.

[0075] (Reaction Scheme 2-1) 2Ca+CaTiO3→Ti+3CaO

[0076] (Reaction Scheme 2-2) *92Ti+Cu+3CaO→CuTi(alloy)+3CaO(separated)

[0077] The metal M produced by the above reaction 3 Oxide (M 3 a O b) is a by-product and must be continuously removed in order to make the process continuous. Since the by-product is not completely dissolved in the molten salt, it may not be easy to remove it or to operate the process continuously. In the method of the present invention, a slagging additive is added to react the metal oxide with the eutectic composition to produce the metal M. 1 The method may further include forming a slag of the by-products and the molten salt of the fluoride-based electrolyte produced in the process of reducing the by-products. When the slag is formed, the viscosity is relatively reduced and the fluidity is relatively increased compared to when the by-products and the molten salt of the fluoride-based electrolyte are present, so that the slag containing the by-products can be continuously removed, and further, a continuous process can be realized.

[0078] An example of the slagging additive that achieves the above-mentioned effects may include, but is not limited to, one or more selected from the group consisting of MgO, CaO, FeO, BaO, SiO2, and Al2O3.

[0079] Metal M from the metal oxide according to the present invention 1The method for reducing may further include the steps of: positioning the liquid metal alloy at the bottom of the electrolytic cell to form a layer separated from the eutectic composition, and continuously obtaining the liquid metal alloy through the bottom of the electrolytic cell; and forming the slag as a layer separated from the eutectic composition through the top of the electrolytic cell. By positioning the liquid metal alloy at the bottom of the electrolytic cell to form a layer separated from the eutectic composition, the liquid metal alloy can be continuously discharged from the bottom of the electrolytic cell. In addition, by forming the slag by adding a slagging additive in a layer separated from the eutectic composition, the slag can be continuously removed through the top of the electrolytic cell, and by-products generated in the reduction process of the metal oxide can be continuously removed. Thus, the reaction product formed when the metal oxide is added to the eutectic composition is continuously removed from the electrolytic cell, and the metal M can be continuously produced without interrupting the process by continuously adding the metal oxide, rather than terminating all the reactions after adding a certain amount of the metal oxide. 1 and metal M 2 In this case, the step of continuously obtaining the liquid metal alloy through the lower part of the electrolytic cell and the step of continuously removing the slag through the upper part of the electrolytic cell may be performed by a method known to those skilled in the art.

[0080] In the step of removing the slag and the fluoride-based electrolyte through the top of the electrolytic cell, after removing the slag, the fluoride-based electrolyte can be replenished during the process operation to maintain the balance of the reaction system and enable a continuous process. In this case, the fluoride-based electrolyte can be continuously separated from the removed slag, and the separated fluoride-based electrolyte can be re-introduced into the electrolytic cell.

[0081] The obtained liquid metal alloy may be cooled to solidify. 1 and metal M 2 Since the alloy is in a homogeneous mixture, the cooling rate of the liquid metal alloy has a large effect on the structure of the alloy obtained after solidification. The cooling rate is important because it allows the intermetallic phase to be stably formed and the M 1 and M. 2In order to produce a structure in which the intermetallic compound phases are continuously connected to each other, it is preferable to slowly cool the steel from the temperature range in which the process according to the present invention is carried out to room temperature, for example, at a rate of 20° C. / min. If the cooling rate is too fast outside the range provided, the intermetallic compound may not yet be formed or fine intermetallic compound particles may be mixed with the metal M. 1 Since a large amount of metal is dispersed in the matrix, continuous and rapid metal M 1 If the cooling is too slow, there is a risk that the mass transfer pathways will not be formed. The cooling rate may be substantially greater than 1° C. / min, more substantially greater than 5° C. / min, due to the excessively long process time while the microstructural advantage is negligible.

[0082] The method according to the invention comprises the step of: 1 and metal M 2 The metal M obtained after the step of obtaining the alloy containing 1 and metal M 2 Metal M is produced by electrolytic refining of an alloy containing 1 The method may further include the step of obtaining.

[0083] The electrolytic refining of metal M 1 The step of obtaining the metal M includes solidifying the obtained liquid metal alloy to obtain a solid phase alloy, and then electrolytically refining the solid phase alloy to obtain a metal M from the alloy. 1 The step may include recovering the

[0084] In some cases, electrolytes that may remain in the liquid metal alloy may be removed before the solidified alloy is electrolytically refined. This may be achieved, for example, by heat treating the liquid metal alloy in a vacuum or inert gas atmosphere to induce the electrolyte to be distilled off. The distillation temperature (heat treatment temperature) is not particularly limited as long as it is equal to or higher than the boiling point of the electrolyte used in the system of the present invention, and may be, for example, 2,500°C or higher. The distillation may be performed under reduced pressure to reduce the distillation temperature and increase efficiency. It may be advantageous to perform the distillation under a vacuum or inert gas atmosphere in order to effectively prevent the liquid metal alloy from being re-oxidized.

[0085] The present invention relates to a metal M obtained by any method or combination of methods described in the present specification. 1 and metal M 2 For example, the metal alloy M 1 and metal M 2 The metal alloy of the present invention is prepared by forming a molten salt of a fluoride-based electrolyte in an electrolytic cell, and dissolving a metal M in the electrolytic cell. 3 and the metal M 1 Metal M that forms a eutectic phase with 2 Put in the above M 2 and M. 3 and reacting the metal oxide with the eutectic composition to form a metal M 1 The reduced metal M 1 Metal M 2 and a method for forming a liquid metal alloy from a metal oxide comprising: 1 For example, the metal M 1 and metal M 2 The metal alloy may be obtained from a process carried out in air or at temperatures in the range of 900 to 1600° C. For example, the metal M 1 and metal M 2 The metal alloy is formed by adding a slagging additive to react the metal oxide with the eutectic composition to form the metal M 1 The metal M of the present invention can be obtained by a method further comprising the step of forming a slag of the molten salt with by-products produced in the process of reducing the metal M of the present invention. 1 and metal M 2 The metal alloy may be obtained by any method or combination of methods described herein.

[0086] In one embodiment, the metal M 1 and metal M 2 The weight of the metal alloy is 100% of the total weight of the metal alloy. 3 The residual content of metal M is 0.1% by weight or less, more specifically 0.01% by weight or less, and even more specifically 0.001% by weight or less. 1and metal M 2 The metal alloy is a high quality metal alloy having an oxygen content of less than or equal to 1,800 ppm, specifically less than or equal to 1,500 ppm, and more specifically less than or equal to 1,200 ppm.

[0087] The liquid alloy (M 1 and M. 2 The liquid metal alloy phase can be used as the final product. 1 is often used industrially in the form of an alloy, but as in the conventional Kroll process, M 1 In cases where M can only be produced as a single metal, a post-processing step of forming an alloy with another metal may be required. However, the present invention provides a method for producing M simultaneously with reduction without such a post-processing step. 1 and M. 2 The process is highly efficient in that the final product is obtained in the form of a metal alloy. Furthermore, reduced metals produced through the conventional Kroll process have a relatively high residual oxygen content, since the production volume of high-grade (Grade 1) metals having a low oxygen content is small. Therefore, even if a metal alloy is produced using reduced metals produced through the Kroll process, there is a limitation that the residual oxygen content is high. On the other hand, the metal alloys produced according to the present invention have a very low oxygen content, and most of them are of a high grade. For example, M 1 When is Ti, the method of the present invention has a very high yield of high-quality metals of 98% or more, whereas the conventional Kroll process is known to have a high-quality metal yield of less than 50%, and the superiority of the present invention can be more clearly understood from this.

[0088] 2.M 1 A system for returning

[0089] Metal M from the metal oxide according to the present invention 1 The system for returning

[0090] An electrolytic cell;

[0091] a molten salt of a fluoride-based electrolyte located in the electrolytic cell;

[0092] The metal M located under the molten salt 2 and metal M 3 and a eutectic composition of

[0093] The metal M located at the bottom of the eutectic composition 1 and the metal M 2 and a liquid metal alloy of

[0094] The density of the molten salt may be less than the density of the metal oxide, and the metal oxide and the metal M 3 reacts to form the metal M 1 is reduced to obtain the metal M 2 is the metal M 1 It is possible to form a eutectic phase with

[0095] In one embodiment, the electrolytic bath may be an electrolytic reduction bath, and a high-frequency melting furnace or an electric furnace may be used to achieve a desired temperature range, depending on the desired metal alloy, but is not limited thereto. Taking into consideration the temperature range in which the reaction is carried out, reactivity, and the like, any electrolytic bath or furnace that is easy for a person of ordinary skill in the art may be used.

[0096] In one embodiment, in order to facilitate separation of the liquid metal alloy and the reaction by-products, the mass ratio of the molten salt of the fluoride-based electrolyte to the reaction by-products may be 5:1 to 2:1, and preferably 3:1, but is not limited thereto.

[0097] In one embodiment, the electrolyte may further include an oxide of one or more metals selected from the group consisting of alkali metals and alkaline earth metals as a reaction additive. The content of the reaction additive may be 0.1 to 25 wt% based on the total weight of the electrolyte. The reaction additive may include, but is not limited to, Li2O, Na2O, SrO, Cs2O, KO, CaO, BaO, or a mixture thereof. The reaction additive included in the electrolyte may enable easier reduction of the metal oxide included in the raw material module.

[0098] In one embodiment, the method for producing an alloy metal of the present invention can be carried out using an electrolytic cell similar to that shown in FIG. 1. For example, a fluoride-based electrolyte is charged into the electrolytic cell 1 and melted to form a molten salt 5, and then a metal M is added to the electrolytic cell. 1 Metal M that forms a eutectic phase with 2 and metal M 3 A reducing agent containing 2 and metal M 3 Since the density of the molten salt of the fluoride-based electrolyte is smaller than the density of the eutectic composition, the molten salt 5 of the fluoride-based electrolyte is located on the eutectic composition 6. Thereafter, the metal oxide 10 is charged into the electrolytic cell using the raw material charging device 1 and reacted with the eutectic composition 6 to produce the metal M 1 and metal M 2 After the reaction is completed, the liquid metal alloy 7 is produced, and the reaction by-product located between the liquid metal alloy and the electrolyte is slag-formed by adding a slagging additive 9. The liquid metal alloy 7 is then collected through the bottom of the electrolytic cell via a melting point 8 connected to the bottom of the electrolytic cell. Since the slag is located at the top of the electrolytic cell, the electrolytic cell is tilted to remove about 50 to 90% of the slag, and a new fluoride-based electrolyte is added to about 10 to 50% of the remaining slag via an electrolyte feed device 2 to form a new electrolyte layer. Then, the metal oxide 10 is again fed into the electrolytic cell using a raw material feed device 1, and reacted with the eutectic composition 6 to produce the liquid metal alloy 7. In all steps of the process, such as before removing the slag or when tilting the electrolytic cell to remove the slag, the liquid metal alloy 7 produced at the bottom of the electrolytic cell can be continuously collected through a melting point 8 at the bottom of the electrolytic cell. For example, the electrolytic cell can be a high-frequency melting furnace 3 to facilitate stirring, but is not limited thereto.

[0099] 3. Working Example

[0100] The following examples are provided to demonstrate the functions and effects of the present invention, but the following examples are merely presented as examples of the invention and do not define the scope of the invention.

[0101] <Example 1>

[0102] Using the system shown in Figure 1, the process was carried out according to the process sequence shown in Figure 2. The electrolyte CaF2 (40.8 g) was weighed out in a resistance heating furnace and placed in an electrolytic cell, which was then heated to about 1415°C to produce a molten salt of a fluoride-based electrolyte (Figure 2a).

[0103] Cu(s) and Ca(s) were weighed out in amounts of 52.8 g and 72.3 g, respectively, and placed in an electrolytic cell and melted to produce a eutectic composition (Figure 2b).

[0104] As the metal oxide, 72.1 g of TiO2 (average particle size 100 μm) was weighed out and reacted for 10 hours (Figure 2 c and d).

[0105] In order to remove by-products, 200 g of Al2O3 powder and 100 g of CaO, which are slagging additives, were added to the furnace to form a slag (e in FIG. 2), and the furnace was cooled slowly. The above process was carried out in an air atmosphere.

[0106] <Example 2>

[0107] Using the system shown in Figure 1, the process was carried out according to the process sequence shown in Figure 2. The electrolyte CaF2 (40.8 g) was weighed out in a resistance heating furnace and placed in an electrolytic cell, which was then heated to about 1415°C to produce a molten salt of a fluoride-based electrolyte (Figure 2a).

[0108] Cu(s) and Ca(s) were weighed out in amounts of 60 g and 65.5 g, respectively, and placed in an electrolytic cell and melted to produce a eutectic composition (Figure 2b).

[0109] As the metal oxide, 111 g of CiTiO3 was weighed out and reacted for 2 hours (Fig. 2c and d).

[0110] In order to remove by-products, 200 g of Al2O3 powder and 100 g of CaO, which are slagging additives, were added to the furnace to form a slag (e in FIG. 2), and the furnace was cooled slowly. The above process was carried out in an air atmosphere.

[0111] <Test Example 1>

[0112] The volatilization rate of fluoride-based electrolytes and chloride-based electrolytes was measured. 500g of each electrolyte (weight before charging) was weighed and charged into a crucible, and the crucible was charged into a melting furnace and left at 1,600℃ for 10 hours, after which the weight of the electrolyte (weight after charging) was measured. The volatilization rate was evaluated using the following method.

[0113] -Volatilization rate: (Weight before charging - Weight after charging) / (Weight before charging) x 100%

[0114] As a result, it was confirmed that CaF2 used as a fluoride-based electrolyte showed a low volatility rate of 1.8% by weight, while CaCl2, a chloride-based electrolyte, showed a high volatility rate of approximately 74% by weight (Figure 3).

[0115] The volatilization rate of the fluoride-based electrolyte CaF2 and the chloride-based electrolyte CaCl2 measured in each temperature range was based on the process temperature at which the process was carried out, and it was found that the vapor pressure of the fluoride-based electrolyte was significantly lower (Figure 4), which indicates that the volatilization rate of the fluoride-based electrolyte in the process is significantly lower.

[0116] For this reason, it is preferable to use fluoride-based electrolytes with low volatility for efficient processing as described above.

[0117] <Test Example 2>

[0118] The alloys obtained in Examples 1 and 2 were characterized using the following methods.

[0119] - Recovery rate: 100-{(1st weight-2nd weight) / 2nd weight x 100%}

[0120] - Residual impurity content: The produced alloy was cut and the inside of the alloy was confirmed by energy dispersive spectroscopy.

[0121] - Oxygen Content: The oxygen content present in the alloy was measured using an ELTRA ONH2000.

[0122] [Table 1] * First weight: Total amount of Cu added to the initial electrolysis tank + theoretical reduction amount of Ti contained in the metal oxide **Second weight: total amount of CuTi obtained

[0123] From the results in Table 1, it can be seen that the alloys of the examples prepared according to the present invention showed high recovery rates and high purity alloys were obtained that were substantially free of metals used as reducing agents and oxygen. That is, unlike the conventional process which was only possible in an inert gas atmosphere as described above, it was confirmed that the process showed a better recovery rate of the target metals and a significantly lower oxygen content even when carried out in an air atmosphere.

[0124] The present invention has been described above with reference to an embodiment thereof, but a person having ordinary knowledge in the field to which the present invention belongs can make various applications and modifications within the scope of the present invention based on the above content.

Claims

1. Metal oxide to metal M １ A method for reducing forming a molten salt of a fluoride-based electrolyte in an electrolytic cell; The metal M １ Metal M that forms a eutectic phase with ２ and metal M ３ A reducing agent containing metal M ２ and metal M ３ producing a eutectic composition of The metal oxide is reacted with the eutectic composition to form a metal M １ The reduced metal M １ M ２ and forming a liquid metal alloy; The method, wherein the density of the molten salt is less than the density of the eutectic composition and the metal oxide.

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

3. The fluoride-based electrolyte is MgF ２ , CaF ２ , SrF ２ , and BaF ２ The method according to claim 1, wherein the organic solvent is one or more selected from the group consisting of:

4. The fluoride-based electrolyte is CaF ２ The method according to claim 3, wherein

5. The metal M １ is one selected from the group consisting of 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 metal M ２ The method according to claim 1, wherein is one or more selected from the group consisting of Cu, Ni, Sn, Zn, Pb, Bi, Cd, and alloys thereof.

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

8. The metal M ３ The method according to claim 1 , wherein is at least one selected from the group consisting of Ca, Mg, Al, and alloys thereof.

9. The metal oxide is M １ ｘ O ｚ and M. １ ｘ M ３ ｙ O ｚ The method of claim 1 , comprising at least one selected from the group consisting of: Here, x and y are each a real number from 1 to 3, and z is a real number from 1 to 4.

10. The metal oxide is reacted with the eutectic composition to form a metal M １ The method according to claim 1 , wherein the process of reducing is carried out in air or in a fluoride atmosphere.

11. The metal oxide is reacted with the eutectic composition to form a metal M １ The method of claim 1, wherein the step of reducing is carried out in the range of 900 to 1,600°C.

12. A slagging additive is added to react the metal oxide with the eutectic composition to produce metal M. １ 2. The method of claim 1, further comprising forming a slag of the molten salt with by-products produced in the process of reducing.

13. The slagging additives are MgO, CaO, FeO, BaO, SiO ２ , and Al ２ O ３ The method of claim 12, comprising one or more selected from the group consisting of:

14. the liquid metal alloy is located at the bottom of the electrolytic bath and forms a layer separate from the eutectic composition, and the liquid metal alloy is continuously obtained through a lower portion of the electrolytic bath; 13. The method of claim 12, wherein the slag forms a distinct layer on top of the eutectic composition, and further comprising the step of continuously removing the slag through the top of the electrolytic cell.

15. The liquid metal alloy is electrolytically refined to obtain metal M １ The method of claim 1 further comprising the step of manufacturing

16. Metal M compared to the total weight of the metal alloy ３ 2. The method according to claim 1, wherein the residual content is 0.1% by weight or less and the oxygen content is 1,800 ppm or less.

17. Metal oxide to metal M １ A system for returning An electrolytic cell; a molten salt of a fluoride-based electrolyte located in the electrolytic cell; The metal M located under the molten salt ２ and Metal M ３ and a eutectic composition of The metal M located at the bottom of the eutectic composition １ and Metal M ２ and a liquid metal alloy of The density of the molten salt is smaller than the density of the metal oxide, and the metal oxide and the metal M ３ reacts to form the metal M １ is reduced to obtain the metal M ２ is the metal M １ The system forms a eutectic phase with

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