Magnesiothermic som process for production of metals

Abstract

A process and apparatus are provided that allow metals including metals having stable oxide phases and metals with variable valencies to be extracted from their respective ores via an electrolytic process that is environmentally sound and economically viable. The process for lowering the oxidation state of a metal in a metal oxide comprises providing an electrolysis chamber housing a flux containing a highly reactive metal (e.g. Mg) and having a cathode, an anode, and a solid oxide membrane. A reducing chamber housing the metal oxide having a higher oxidation state to be reduced is provided. A solid oxide membrane (SOM) process is used to generate vapor of the highly reactive metal in the electrolysis chamber. The vapor of the highly reactive metal is directed to the reducing chamber, where the vapor of the highly reactive metal reacts with the metal oxide to be reduced to provide a metal or metal oxide having a lowest oxidation state and an oxide of the highly reactive metal (e.g. MgO). In certain embodiments, the oxide of the highly reactive metal is recycled back to the flux in the electrolysis chamber.

1 . A method of lowering the oxidation state of a metal in an oxide comprising:
 providing an electrolysis chamber housing a magnesium-oxide containing flux, the electrolysis chamber comprising a cathode, an anode, and a solid oxide membrane;   providing a reducing chamber housing the metal oxide to be reduced, the metal oxide to be reduced having a higher oxidation state;   using a solid oxide membrane (SOM) process to generate Mg vapor in the electrolysis chamber; and   directing the Mg vapor to the reducing chamber, wherein the Mg vapor reacts with the metal oxide to be reduced to provide a metal or metal oxide having a lowest oxidation state and magnesium oxide (MgO).   
     
     
         2 . The method of  claim 1 , comprising isolating the metal or metal oxide having the lowest oxidation state from the MgO. 
     
     
         3 . The method of  claim 2 , comprising returning the MgO to the electrolysis chamber via a conduit in communication with the electrolysis chamber and the reducing chamber. 
     
     
         4 . The method of  claim 1 , comprising subjecting the metal oxide having the lowest oxidation state to a further reducing step comprising a second SOM process to generate a metal. 
     
     
         5 . The method of  claim 4 , comprising isolating the metal generated in the second SOM process. 
     
     
         6 . The method of  claim 1 , wherein the metal provided in the reducing chamber comprises dissolved oxygen and wherein the metal provided in the reducing chamber is subjected to a second SOM process wherein the dissolved oxygen is substantially removed. 
     
     
         7 . The method of  claim 6 , comprising using the metal produced in the reducing chamber to provide a cathode in the second SOM process. 
     
     
         8 . The method of  claim 1 , wherein the metal oxide to be reduced comprises tantalum. 
     
     
         9 . The method of  claim 1 , wherein the metal oxide to be reduced comprises aluminum. 
     
     
         10 . The method of  claim 1 , wherein the metal oxide to be reduced comprises titanium. 
     
     
         11 . The method of  claim 1 , wherein using a solid oxide membrane (SOM) process to generate Mg gas in the electrolysis chamber includes providing an anode encased in an oxygen-ion-conducting solid electrolyte. 
     
     
         12 . The method of  claim 11 , wherein the oxygen-ion-conducting solid electrolyte comprises yttria-stabilized zirconia (YSZ). 
     
     
         13 . The method of  claim 11 , wherein the oxygen-ion-conducting solid electrolyte is substantially electrochemically stable when the SOM process is used to generate Mg vapor. 
     
     
         14 . The method of  claim 1 , wherein isolating the metal or metal oxide having the lowest oxidation state from the MgO comprises a separation technique selected from the group consisting of gravimetric sedimentation and selective isolation using a process comprising dissolution of MgO. 
     
     
         15 . A system for use in reducing the oxidation state of a metal in a metal oxide, comprising:
 an electrolysis chamber including a vessel for housing a flux having magnesium oxide (MgO) and an electrode having a solid oxide membrane (SOM), the electrolysis chamber constructed and arranged to reduce MgO in the flux having MgO to produce magnesium vapor;   a reduction chamber housing the metal oxide to be reduced, the metal oxide having a higher oxidation state, the reduction chamber constructed and arranged to oxidize magnesium vapor to produce MgO and to reduce the metal oxide having the higher oxidation state to produce a metal or metal oxide having a lowest oxidation state; and   at least one conduit between the electrolysis chamber and the reduction chamber for delivering MgO produced in the reduction chamber to the electrolysis chamber.   
     
     
         16 . The system of  claim 15 , wherein the electrode having the SOM comprises an anode encased in an oxygen-ion-conducting solid electrolyte. 
     
     
         17 . The system of  claim 16 , wherein the vessel for housing the flux comprises a steel cathode. 
     
     
         18 . The system of  claim 16 , wherein the oxygen-ion-conducting solid electrolyte comprises yttria-stabilized zirconia (YSZ). 
     
     
         19 . The system of  claim 18 , wherein the oxygen-ion-conducting solid electrolyte is substantially electrochemically stable when the electrolysis chamber is used to reduce MgO in the flux having MgO to produce magnesium vapor. 
     
     
         20 . The system of  claim 15 , comprising separation apparatus for isolating the metal or metal oxide having the lowest oxidation state, the separation apparatus selected from the group consisting of gravimetric sedimentation apparatus and MgO dissolution apparatus. 
     
     
         21 . The system of  claim 20 , comprising a second electrolysis chamber housing the metal oxide having the lowest oxidation state and having a SOM, the second electrolysis chamber constructed and arranged to reduce at least a portion of the metal oxide having the lowest oxidation state to produce a metal. 
     
     
         22 . The system of  claim 20 , comprising a second electrolysis chamber housing the metal produced in the reduction chamber and having a SOM, wherein the metal produced in the reduction chamber comprises dissolved oxygen and wherein the second electrolysis chamber constructed and arranged to substantially remove the dissolved oxygen. 
     
     
         23 . The system of  claim 22 , wherein the second electrolysis chamber includes a cathode comprising the metal produced in the reduction chamber. 
     
     
         24 . The system of  claim 15 , wherein the metal oxide to be reduced comprises tantalum. 
     
     
         25 . The system of  claim 15 , wherein the metal oxide to be reduced comprises aluminum. 
     
     
         26 . The system of  claim 15 , wherein the metal oxide to be reduced comprises titanium. 
     
     
         27 . A method of lowering the oxidation state of a metal of a first metal oxide comprising:
 providing a first metal oxide and a second metal oxide, wherein the oxidation potential of the metal of the second metal oxide is higher than the oxidation potential of the metal of the first metal oxide;   providing an electrolysis chamber housing a flux comprising the second metal oxide, the electrolysis chamber comprising a cathode, an anode, and a solid oxide membrane;   providing a reducing chamber housing the first metal oxide to be reduced, the first metal oxide to be reduced having a high oxidation state;   using a solid oxide membrane (SOM) process at a temperature sufficient to generate a vapor of the metal of the second metal oxide in the electrolysis chamber;   directing the vapor of the metal of the second metal oxide to the reducing chamber, wherein said vapor reacts with the first metal oxide to provide the metal of the first metal oxide or a metal oxide of the first metal oxide having a low oxidation state; and   regenerating the second metal oxide.   
     
     
         28 . The method of  claim 27 , wherein the second metal oxide comprises lithium. 
     
     
         29 . The method of  claim 27 , wherein the second metal oxide comprises calcium.