Method and apparatus for producing metal

Abstract

The present invention relates to a method for producing a metal by a direct oxide reduction process with Ca. A CaCl 2 -based molten salt containing Ca is held in a reduction chamber 1 , a metal oxide is introduced into the molten salt in the reduction chamber 1 , and the metal oxide is reduced with the Ca in the molten salt to form said metal. The metal formed in the molten salt is separated from the molten salt in a separation means 2 , and the molten salt deprived of the metal is introduced into a chlorination chamber 7 and subjected to chlorination treatment with chlorine gas to eliminate the byproduct CaO in the molten salt. The molten salt after chlorination treatment is introduced into an electrolysis chamber 8 and electrolyzed for the formation of Ca and chlorine from CaCl 2 , and the thus-formed Ca or Ca-containing molten salt is transferred from the electrolysis chamber 8 to the reduction chamber 1 . The chlorine obtained in the electrolysis chamber 8 is used in the chlorination chamber 7 . Thus, the present invention provides a metal production method and an apparatus wherein high levels of productivity are obtained and the product metal can be inhibited from carbon contamination due to CaO, without any generation of CO 2 from the production process, while their being based on the direct oxide reduction process comprising the step of reducing a metal oxide with Ca.

1 . A method for producing a metal which comprises: 
 a reduction step in which a metal oxide is introduced into a CaCl 2 -based molten salt containing Ca for the formation of said metal by reduction of the metal oxide with Ca in the molten salt;    a separation step in which said metal formed in the molten salt is separated from the molten salt;    a chlorination step in which the molten salt after separation of said metal is subjected to chlorination treatment with chlorine gas to chlorinate the byproduct CaO in the molten salt; and    an electrolysis step in which the molten salt after chlorination treatment is electrolyzed to form Ca and chlorine from CaCl 2 , and the thus-formed Ca or Ca-containing molten salt is sent to the above-mentioned reduction step.    
     
     
         2 . A method for producing a metal which comprises: 
 a reduction step in which a metal oxide is introduced into a CaCl 2 -based molten salt containing Ca for the formation of said metal by reduction of the metal oxide with Ca in the molten salt;    a separation step in which the metal formed in the molten salt is separated from the molten salt;    a chlorination step in which the molten salt after separation of said metal is subjected to chlorination treatment with chlorine gas to chlorinate the byproduct CaO in the molten salt; and    an electrolysis step in which the molten salt after chlorination treatment is electrolyzed to form Ca and chlorine from CaCl 2 , and the thus-formed Ca or Ca-containing molten salt is sent to the above-mentioned reduction step, wherein, in said reduction step, the metal formed is allowed to settle and the metal that has settled is drawn out together with the molten salt and transferred to the separation step.    
     
     
         3 . A method for producing a metal according to  claim 1 , wherein said metal is one of titanium, tungsten, niobium, tantalum, chromium, zirconium and neodymium.  
     
     
         4 . A method for producing a metal according to  claim 1 , wherein part of the molten salt after chlorination treatment is sent to the electrolysis step and the remaining portion of the molten salt is sent to the reduction step.  
     
     
         5 . A method for producing a metal according to  claim 1 , wherein the chlorine gas formed in said electrolysis step is used in said chlorination step.  
     
     
         6 . A method for producing a metal according to  claim 1 , wherein, in said electrolysis step, an electrolysis chamber in which the anode side and cathode side are separated from each other by a partition wall is used.  
     
     
         7 . A method for producing a metal according to  claim 6 , wherein a flow of the molten salt from the anode side toward the cathode side is formed in the electrolysis chamber.  
     
     
         8 . A method for producing a metal according to  claim 1 , further comprising the step of rinsing the metal separated from the molten salt using part of the CaCl 2  after completion of said chlorination step.  
     
     
         9 . A method for producing a metal according to  claim 1 , wherein, in said separation step, said metal is separated from the molten salt by physical compacting together.  
     
     
         10 . A method for producing a metal according to  claim 1 , further comprising the step of melting the metal obtained in the separation step in an inert atmosphere to make an ingot.  
     
     
         11 . An apparatus for producing a metal comprising: 
 a reduction chamber in which a CaCl 2 -based molten salt containing Ca is held and a metal oxide introduced into the molten salt is reduced with Ca in the molten salt to obtain said metal;    means for separating the metal formed in the molten salt from the molten salt;    a chlorination chamber in which the molten salt after separation of the metal is held and the molten salt is subjected to chlorination treatment with chlorine gas for the chlorination of the byproduct CaO in the molten salt;    an electrolysis chamber in which the molten salt after chlorination treatment is held and the molten salt is electrolyzed to form Ca and chlorine from CaCl2; and    means for transferring the thus-formed Ca or Ca-containing molten salt from the electrolysis chamber to said reduction chamber.    
     
     
         12 . An apparatus for producing a metal comprising: 
 a reduction chamber in which a CaCl 2 -based molten salt containing Ca is held and a metal oxide introduced into the molten salt is reduced with Ca in the molten salt to obtain said metal;    means for separating the metal formed in the molten salt from the molten salt;    a chlorination chamber in which the molten salt after separation of the metal is held and the molten salt is subjected to chlorination treatment with chlorine gas for the chlorination of the byproduct CaO in the molten salt;    an electrolysis chamber in which the molten salt after chlorination treatment is held and the molten salt is electrolyzed to form Ca and chlorine from CaCl 2 ; and    means for transferring the thus-formed Ca or Ca-containing molten salt from the electrolysis chamber to said reduction chamber,    wherein said chlorination chamber is unified with said reduction chamber.    
     
     
         13 . An apparatus for producing a metal comprising: 
 a reduction chamber in which a CaCl 2 -based molten salt containing Ca is held and a metal oxide introduced into the molten salt is reduced with Ca in the molten salt to obtain said metal;    means for separating the metal formed in the molten salt from the molten salt;    a chlorination chamber in which the molten salt after separation of the metal is held and the molten salt is subjected to chlorination treatment with chlorine gas for the chlorination of the byproduct CaO in the molten salt;    an electrolysis chamber in which the molten salt after chlorination treatment is held and the molten salt is electrolyzed to form Ca and chlorine from CaCl 2 ; and    means for transferring the thus-formed Ca or Ca-containing molten salt from the electrolysis chamber to said reduction chamber,    wherein said electrolysis chamber is integrated with said reduction chamber.    
     
     
         14 . An apparatus for producing a metal according to  claim 11 , wherein said electrolysis chamber has, between the anode side and cathode side, a partition wall through which the molten salt can pass.  
     
     
         15 . An apparatus for producing a metal according to  claim 13 , wherein the cathode side of said electrolysis chamber is unified with said reduction chamber.  
     
     
         16 . An apparatus for producing a metal according to  claim 15 , wherein said electrolysis chamber is configured in such a manner that the molten salt introduced into the anode side can flow through the cathode to the reduction chamber.  
     
     
         17 . An apparatus for producing a metal according to  claim 16 , further comprising a Ca reservoir for retaining Ca in the liquid on the reduction chamber side from the cathode.  
     
     
         18 . An apparatus for producing a metal according to  claim 15 , wherein said electrolysis chamber is formed like a ring surrounding the reduction chamber which has a cylindrical shape.  
     
     
         19 . An apparatus for producing a metal according to  claim 18 , wherein said electrolysis chamber comprises an outer cylinder serving also as the anode and an inner cylinder serving also as the cathode and allowing the molten salt to pass therethrough, the inside of said inner cylinder being the reduction chamber.