Reduction system and method for high-melting point metal oxides, using liquid metal crucible

Abstract

The present disclosure provides a system and a method for reducing metal oxide to metal M1.

1 . A system for reducing a metal oxide to metal M 1 , the system comprising:
 a cell;   a liquid metal crucible accommodated at a bottom of the cell and comprising a liquid metal alloy of metal M 1  and metal M 2  forming a eutectic phase with each other;   a liquid flux accommodated in the cell while forming a layer on the liquid metal crucible without being mixed with the liquid metal crucible; and   a solid raw material module comprising a metal oxide, metal M 2 , and reducing metal M 3 ,   wherein the metal oxide is reduced to metal M 1  by reaction with the reducing metal M 3  while the solid raw material module reaches the liquid metal crucible and is melted, and the reduced metal M 1  and the metal M 2  are continuously incorporated into the liquid metal crucible while forming a liquid metal alloy.   
     
     
         2 . The system according to  claim 1 , further comprising an electrorefining part configured to collect and electrorefine the liquid metal alloy formed by the reduced metal M 1  and the metal M 2  to obtain metal M 1 . 
     
     
         3 . The system according to  claim 1 , wherein the metal oxide comprises at least one selected from the group consisting of M 1   x O z  and M 1   x M 3   y O z , wherein x and y are each a real number ranging from 1 to 3, and z is a real number ranging from 1 to 4. 
     
     
         4 . The system according to  claim 1 , wherein the solid raw material module comprises: a core layer comprising the metal oxide and the reducing metal M 3 ; and a shell layer composed of metal M 2  surrounding the core layer. 
     
     
         5 . The system according to  claim 1 , wherein:
 the solid raw material module is a multilayer structure comprising: a core layer comprising the metal oxide; and a shell layer coated to surround an outer surface of the core layer; and   the shell layer comprises an alloy phase composed of the metal M 2  and the metal M 3 .   
     
     
         6 . The system according to  claim 1 , wherein:
 the solid raw material module is configured to descend vertically within the cell until it reaches the liquid metal crucible through the flux; and   the solid raw material module descends at a rate of a distance corresponding to 0.1% to 10% of a depth of the cell per min.   
     
     
         7 . The system according to  claim 1 , wherein, when the metal oxide is reduced to the metal M 1  by reaction with the reducing metal M 3  while the solid raw material module is melted, oxide M 3   a O b  is produced, and the oxide M 3   a O b  has a lower specific gravity than that of the flux, wherein a and b are each a real number ranging from 1 to 3. 
     
     
         8 .- 10 . (canceled) 
     
     
         11 . The system according to  claim 1 , wherein the reaction between the metal oxide and the reducing metal is performed in an inert gas atmosphere and/or air. 
     
     
         12 . The system according to  claim 4 , wherein the core layer is composed of a powder mixture comprising powder of the metal oxide powder and powder of the reducing metal M 3 . 
     
     
         13 . The system according to  claim 4 , wherein the core layer is a multilayer structure comprising: a first core composed of the metal oxide; and a second core coated to surround an outer surface of the first core and composed of the metal M 3 . 
     
     
         14 . The system according to  claim 4 , wherein the solid raw material module further comprises an oxidation-preventing layer surrounding the shell layer and serving to prevent oxidation of the metal contained in the core layer and/or the shell layer. 
     
     
         15 . (canceled) 
     
     
         16 . The system according to  claim 1 , wherein 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, Nb, Pm, Sm, Eu, Al, V, Mo, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md and No. 
     
     
         17 . The system according to  claim 1 , wherein the metal M 2  is at least one selected from the group consisting of Cu, Ni, Fe, Sn, Zn, Pb, Bi, Cd, and alloys thereof. 
     
     
         18 . The system according to  claim 1 , wherein the metal M 3  is at least one selected from the group consisting of Ca, Mg, Al, and alloys thereof. 
     
     
         19 . The system according to  claim 1 , wherein the flux comprises a molten halide salt of at least one metal selected from the group consisting of alkali metals and alkaline earth metals. 
     
     
         20 . A method of reducing a metal oxide to metal M 1 , the method comprising:
 providing a cell;   introducing a liquid flux into the cell;   introducing metal M 1  and metal M 2  forming a eutectic phase with each other, thereby producing a liquid metal crucible having a specific gravity higher than that of the flux and accommodated in the cell while forming a layer under the flux without being mixed with the flux;   moving a solid raw material module comprising a metal oxide, metal M 2  and reducing metal M 3  to the cell until it reaches the liquid metal crucible through the flux; and   obtaining a liquid metal alloy comprising metal M 1  derived from the metal oxide of the solid raw material module and metal M 2 .   
     
     
         21 . The method according to  claim 20 , further comprising obtaining metal M 1  by electrorefining the obtained metal alloy comprising the metals M 1  and M 2 . 
     
     
         22 . The method according to  claim 20 , wherein oxide M 3   a O b  is produced as a by-product in moving the solid raw material module and/or obtaining the liquid metal alloy, and the oxide M 3   a O b  has a lower specific gravity than that of the flux, and
 the method further comprises continuously collecting the by-product M 3   a O b  forming a layer on the flux, and adding and mixing M 1   x O z  with the collected M 3   a O b , thereby producing a metal oxide expressed as M 1   x M 3   y O z  derived from the by-product M 3   a O b  and the added M 1   x O z .   
     
     
         23 . A metal alloy obtained by the method according to  claim 20 . 
     
     
         24 . A metal obtained by the method according to  claim 21 . 
     
     
         25 . (canceled)