Extraction of metals

Abstract

A method of producing a metal or an alloy from metalliferous material by removing O,S, or N from a solid body of metalliferous material by electrolysis in an electrolytic cell is disclosed. The cell includes a molten halide salt or mixture of halide salts as an electrolyte. The cation of the salt is selected from the group that includes Ca, Ba, Li, Na, K, Mg, Sr, Cs and Y. In one aspect of the invention the method includes conducting the electrolysis under conditions wherein the solid body of metalliferous material is made part of a cathode of the electrolytic cell, the cathode includes a conductor for electrically connecting the cathode with an electrical potential, the conductor has high resistance to chemical attack by the electrolyte at high temperatures, and the conductor is at least partly immersed in the electrolyte. In another aspect of the invention the method includes conducting the electrolysis under conditions wherein the potential applied between an anode and the cathode of the electrolytic cell is chosen such that permanent decomposition of the electrolyte is avoided to an extent that substantial deposition of the electrolyte cation at the cathode is avoided and anode material transport towards and into the cathode is substantially prevented. A cathode for use in the method is also disclosed, which cathode includes a body of metalliferous material distributed around one or more electrical conductors that are substantially inert in the electrolyte at high temperatures and which provide a plurality of reduction zones at the cathode.

1 . A method of producing a metal or an alloy from metalliferous material by removing an impurity (I) selected from the group including O, S, or N from a solid body of metalliferous material by electrolysis in an electrolytic cell that includes molten halide salt or mixture of halide salts as an electrolyte, wherein the cation of said salt is selected from the group that includes Ca, Ba, Li, Na, K, Mg, Sr, Cs and Y, which method includes conducting the electrolysis under conditions wherein: 
 (a) the potential applied between an anode and a cathode of the electrolytic cell is chosen such that permanent decomposition of the electrolyte is avoided to an extent that substantial deposition of the electrolyte cation at the cathode is avoided; and    (b) the body is made part of the cathode of the electrolytic cell, the cathode includes a conductor for electrically connecting the cathode with an electrical potential, the conductor has high resistance to chemical attack by the electrolyte at high temperatures, and the conductor is at least partly immersed in the electrolyte; and    (c) O, S, or N is removed from the cathode and passes into solution and/or chemically reacts with the electrolyte cation.    
     
     
         2 . The method defined in  claim 1  wherein the metalliferous material contains an oxide, sulfide, carbide or nitride of said metal.  
     
     
         3 . The method defined in  claim 1  or  claim 2  wherein the metalliferous material is a titanium-containing material.  
     
     
         4 . The method defined in  claim 3  wherein the titanium-containing material is titania.  
     
     
         5 . The method defined in any one of the preceding claims wherein the impurity is oxygen.  
     
     
         6 . The method defined in any one of the preceding claims wherein the anode is formed from graphite.  
     
     
         7 . A method of producing a metal or an alloy from metalliferous material by removing an impurity (I) selected from the group including O, S, or N from a solid body of metalliferous material by electrolysis in an electrolytic cell that includes molten halide salt or mixture of halide salts an an electrolyte, wherein the cation of said salt is selected from the group that includes Ca, Ba, Li, Na, K, Mg, Sr, Cs and Y, which method includes conducting the electrolysis under conditions wherein: 
 (a) the potential applied between an anode and a cathode of the electrolytic cell is chosen such that permanent decomposition of the electrolyte is avoided to an extent that substantial deposition of the electrolyte cation at the cathode is avoided and anode material transport towards and into the cathode is substantially prevented;    (b) the body is made part of the cathode of the electrolytic cells; and    (c) O, S, C or N is removed from the cathode and passes into solution and/or chemically reacts with the electrolyte cation.    
     
     
         8 . The method defined in  claim 7  wherein the cathode includes a conductor having high resistance to chemical attack by the electrolyte at high temperatures for connecting the cathode with an electrical potential and the conductor is at least partly immersed in the electrolyte.  
     
     
         9 . The method defined in  claim 7  or  claim 8  wherein the metalliferous material contains an oxide, sulfide, carbide or nitride of said metal.  
     
     
         10 . The method defined in any one of  claims 8  to  9  wherein the metalliferous material is a titanium-containing material.  
     
     
         11 . The method defined in  claim 10  wherein the titanium-containing material is titania.  
     
     
         12 . The method defined in any one of  claims 7  to  11  wherein the impurity is oxygen.  
     
     
         13 . The method defined in any one of  claims 7  to  12  wherein the anode is formed from graphite.  
     
     
         14 . A cathode for use in the method defined in any one of the preceding claims includes the body of metalliferous material distributed around one or more electrical conductors that are substantially inert in the electrolyte at high temperatures and which provide a plurality of reduction zones at the cathode.