Method of reclaiming contaminated metal

Abstract

A method of reclaiming a metal M 1 from a source of highly contaminated metal M 1 X having a high oxygen content includes the steps of: sintering the highly contaminated finely divided metal M 1 X into a perform; introducing the preform into an electrochemical cell, the cell containing a liquid electrolyte comprising a fused salt or mixture of salts generally designated as M 2 Y in which oxygen is soluble, and a relatively inert anode; conducting electrolysis under conditions favorable to the selective dissolution of oxygen in preference to the deposition of the M 2 cation to form a decontaminated metal preform; and following electrolysis, reclaiming the decontaminated metal preform from the cathode. The reclaimed decontaminated metal preform may optionally be crushed to yield a powder of the metal M 1 . The highly contaminated finely divided metal may comprise swarf, chips and such-like from machining operations, or may comprise high oxygen content metal powders such as hydride-dehydride (HDH) titanium powder. By using the method of the present invention, the oxygen content of the finely divided metal can be reduced to less than 4000 ppm, preferably less than 2000 ppm, more preferably less than 1000 ppm and even more preferably less than 500 ppm.

1 . A method of reclaiming a metal M 1  from a source of highly contaminated metal M 1 X having a high oxygen content, said method including the steps of: 
 sintering the highly contaminated finely divided metal M 1 X into a preform;    introducing the preform into an electrochemical cell, the cell containing a liquid electrolyte comprising a fused salt or mixture of salts generally designated as M 2 Y in which oxygen is soluble, and a relatively inert anode;    conducting electrolysis under conditions favorable to the selective dissolution of oxygen in preference to the deposition of the M 2  cation to form a decontaminated metal preform; and    following electrolysis, reclaiming the decontaminated metal preform from the cathode.    
     
     
         2 . A method according to  claim 1 , wherein the sintering step increases the density of the preform by no more than 5%.  
     
     
         3 . A method according to  claim 2 , wherein the sintering step increases the density of the preform by no more than 2%.  
     
     
         4 . A method according to  claim 1 , wherein M 1  comprises titanium and the finely divided metal is sintered for less than 4 hours.  
     
     
         5 . A method according to  claim 1 , wherein the finely divided metal is formed by crushing chips or swarf.  
     
     
         6 . A method according to  claim 5 , wherein the finely divided metal has a size of 2 mm to 5 mm.  
     
     
         7 . A method according to  claim 1 , wherein the highly contaminated finely divided metal is hydrogen-dehydride (HDH) titanium powder.  
     
     
         8 . A method according to  claim 6 , wherein the HDH powder has a particle size of between 45 μm and 250 μm.  
     
     
         9 . A method according to  claim 6 , wherein a metal oxide is mixed with the HDH powder in an amount equivalent to an alloying addition.  
     
     
         10 . A method according to  claim 1 , wherein M 1  is selected from the group consisting of a Group IV element, Ti, Si, Ge, Zr or Hf, a lanthanide Sm or Nd, a transition metal Mo, Cr, Nb or Sc, and an alloy comprising any combination thereof.  
     
     
         11 . The method according to  claim 10  wherein M 1  is Ti, Si, Ge, Zr or Hf.  
     
     
         12 . The method according to  claim 10  wherein M 1  is Sm or Nd.  
     
     
         13 . The method according to  claim 10  wherein M 1  is Mo, Cr, Nb or Sc.  
     
     
         14 . A method according to  claim 1 , wherein M 1  is titanium or a titanium alloy.  
     
     
         15 . A method according to  claim 1 , wherein the preform also contains metal oxide.  
     
     
         16 . A method according to  claim 1 , wherein M 2 Y is CaCl 2 .