Electrolytic reduction of metal oxides such as titanium dioxide and process applications

Abstract

A method of removing oxygen from a solid metal, metal compound or semi-metal M1O by electrolysis in a fused salt of M2Y or a mixture of salts, which comprises conducting electrolysis under conditions such that reaction of oxygen rather than M2 deposition occurs at an electrode surface and that oxygen dissolves in the electrolyte M2Y and wherein, M1O is in the form of (sintered) granules or is in the form of a powder which is continuously fed into the fused salt. Also disclosed is a method of producing a metal foam comprising the steps of fabricating a foam-like metal oxide perform, removing oxygen from said foam structured metal oxide preform by electrolysis in a fused salt of M2Y or a mixture of salts, which comprises conducting electrolysis under conditions such that reaction of oxygen rather than M2 deposition occurs at an electrode surface. The method is advantageously applied for the production of titanium from Ti-dioxide.

1 - 22 . (canceled) 
     
     
         23 . A method of removing oxygen from titanium dioxide by electrolysis in a fused salt of M 2 Y or a mixture of salts, which comprises providing the titanium dioxide as a first cathode, conducting electrolysis under conditions such that reaction of oxygen rather than M 2  deposition occurs at the first cathode surface and that oxygen dissolves in the electrolyte M 2 Y, to form titanium at the first cathode, and wherein a second cathode having a potential more negative than the first cathode is switched on, leading to the dissolution of the titanium from the first cathode and the deposition of titanium onto the second cathode. 
     
     
         24 . A method according to  claim 23  in which the titanium deposited on the second cathode is dendritic in structure. 
     
     
         25 . A method according to  claim 23  comprising the further step of turning the titanium deposited on the second cathode into powder. 
     
     
         26 . A method according to  claim 23  in which M 2  is Ca, Ba, LI, Cs or Sr. 
     
     
         27 . A method according to  claim 23  in which Y is Cl. 
     
     
         28 . An electrolysis apparatus for the production of titanium comprising a carbon anode, a first cathode formed from titanium dioxide and a second cathode capable of being maintained at a potential which is more negative than the first cathode. 
     
     
         29 . An apparatus according to  claim 28  further comprising a fused salt. 
     
     
         30 . Titanium powder formed using a method according to  claim 23 . 
     
     
         31 . A method for producing titanium from titanium dioxide comprising the steps of:
 (a) providing titanium oxide as a first cathode;   (b) removing oxygen from the titanium dioxide in a fused salt of M 2 Y or a mixture of salts, which comprises conducting electrolysis under conditions such that reaction of oxygen rather than M 2  deposition occurs at an electrode surface and that oxygen dissolves in the electrolyte M 2 , and   (c) switching on a second cathode having a potential more negative than the first cathode leading to the dissolution of titanium from the first cathode and the deposition of titanium onto the second cathode.