Method for electrolyzing molten salt, electrolytic cell, and process for producing ti using said method

Abstract

The present invention provides a method for electrolyzing molten salt that can enhance the concentration of metal-fog forming metal in the molten salt by carrying out the electrolysis under conditions that the molten salt containing the chloride of metal-fog forming metal is supplied from one end of an electrolytic cell to a space between an anode and a cathode in a continuous or intermittent manner to provide a flow rate in one direction to the molten salt in the vicinity of the surface of the cathode and thus to allow the molten salt to flow in one direction in the vicinity of the surface of the cathode. According to the present invention, while high current efficiency is maintained, only the molten salt enriched with metal-fog forming metal such as Ca can be effectively taken out. Further, this method can easily be carried out by using the electrolytic cell according to the present invention. Furthermore, the application of the method for electrolyzing molten salt according to the present invention to the production of Ti by Ca reduction can realize the production of metallic Ti with high efficiency. Thus, the method for electrolyzing molten salt, the electrolytic cell, and the process for producing Ti, each according to the present invention, can be effectively utilized in the production of Ti by Ca reduction.

1 - 7 . (canceled) 
   
   
       8 . A method for electrolyzing molten salt employing an electrolytic cell provided, between an anode and a cathode, with a diaphragm or a partition wall configured so that part of the molten salt can communicate therethrough, comprising:
 supplying molten salt containing the chloride of a metal-fog forming metal to a space between said cathode and said diaphragm or partition wall in a continuous or intermittent manner; and,   providing a flow rate in one direction to the molten salt in the vicinity of the surface of the cathode to thereby cause the formation of a flow of the molten salt in one direction along the surface of the cathode, and   carrying out the electrolyzing along the flow to thereby enhance the concentration of the metal-fog forming metal.   
   
   
       9 . The method for electrolyzing a molten salt according to  claim 8 , in which the method entails employing an electrolytic cell comprised of an anode and a cathode where the surfaces of said anode and cathode are disposed facing each other in a substantially vertical direction. 
   
   
       10 . The method for electrolyzing molten salt according to  claim 8 , wherein the concentration of the metal-fog forming metal in the molten salt in the electrolytic cell is controlled so that it may be at a level lower than the saturation solubility. 
   
   
       11 . An electrolytic cell, comprising:
 an electrolytic cell container elongated in one direction and intended for retaining molten salt containing the chloride of the metal-fog forming metal;   an anode and a cathode disposed along the lengthwise direction of the electrolytic cell container;   a diaphragm or a partition wall, being configured so that part of the molten salt can communicate therethrough, as disposed between said anode and said cathode;   a molten salt feeding port capable of supplying the molten salt to a space between said cathode and said diaphragm or said partition wall, as provided at one end of the electrolytic cell container; and   a molten salt drawing out port provided at the other end thereof for drawing out the molten salt increased in Ca concentration as formed by electrolysis of the molten salt.   
   
   
       12 . The electrolytic cell according to  claim 11 , wherein the surfaces of said anode and said cathode are disposed facing each other in a substantially vertical direction. 
   
   
       13 . A process for producing Ti, comprising:
 a reduction step of causing TiCl 4  to react with Ca in a molten salt containing CaCl 2  and further Ca dissolved therein to thereby cause formation of Ti particles in said molten salt;   a separation step of separating said Ti particles formed in said molten salt from said molten salt; and   an electrolysis step of electrolyzing molten salt decreased in Ca concentration in association with formation of Ti particles to increase the Ca concentration,   wherein the molten salt increased in Ca concentration as formed in the electrolysis step is used for reduction of TiCl 4  in the reduction step,   and wherein the method for electrolyzing molten salt according to  claim 8  is applied in said electrolysis step.   
   
   
       14 . The method for electrolyzing molten salt according to  claim 9 , wherein the concentration of the metal-fog forming metal in the molten salt in the electrolytic cell is controlled so that it may be at a level lower than the saturation solubility.