Mercury-free fusible alloy for electrolyzing salts

Abstract

An apparatus and method is provided for the production of alkali metals and caustic solutions. The apparatus and method do not require the use of toxic liquid mercury-sodium amalgam electrodes. The apparatus and methods utilize a bismuth-indium-tin eutectic alloy as a substitute for the mercury electrode used in a conventional Castner-Kellner apparatus.

1 . An electrolysis cell assembly comprising:
 a first cell chamber containing a first electrolyte salt solution and an anode;   a second cell chamber containing a second electrolyte caustic soda solution and a cathode;   a barrier physically separating the first electrolyte solution from the second electrolyte solution; and   a eutectic electrode contacting the first and second electrolyte solutions, the eutectic electrode excluding mercury-free and comprising an alloy of bismuth, indium and tin, and electrically interconnecting the first cell and the second cell.   
     
     
         2 . The electrolysis cell assembly of  claim 1 , wherein the first electrolyte salt solution is contains an alkali-metal-halide salt. 
     
     
         3 . The electrolysis cell assembly of  claim 2 , wherein the alkali-metal-halide salt is sodium chloride. 
     
     
         4 . The electrolysis cell assembly of  claim 2 , wherein the alkalai-metal-halide salt is potassium chloride. 
     
     
         5 . The electrolysis cell assembly of  claim 1 , wherein the second electrolyte caustic soda solution becomes a sodium hydroxide solution during operation of the electrolysis cell assembly. 
     
     
         6 . The electrolysis cell assembly of  claim 1 , wherein the second electrolyte caustic soda solution becomes a potassium hydroxide solution during operation of the electrolysis cell assembly. 
     
     
         7 . The electrolysis cell assembly of  claim 1 , wherein the anode comprises graphite. 
     
     
         8 . The electrolysis cell assembly of  claim 1 , wherein anode comprises titanium. 
     
     
         9 . (canceled) 
     
     
         10 . The electrolysis cell assembly of  claim 1 , wherein the eutectic alloy has a bismuth:indium:tin ratio of 32.5:51.0:16.5 by mass. 
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . An electrolysis system comprising:
 a first cell containing a first electrolysis salt solution of an alkali-metal and a halogen;   a first cell anode for receiving electrical current from the first electrolysis salt solution;   a second cell adapted to contain a second electrolysis caustic soda solution;   a second cell cathode for delivering electrical current to the second electrolysis caustic soda solution; and   a eutectic electrode electrically interconnecting the first electrolysis salt solution and the second electrolysis caustic soda solution, the eutectic electrode formed from a bismuth-indium-tin ternary alloy.   
     
     
         19 . The electrolysis system of  claim 18 , wherein the alkali-metal and the halogen constitute a salt of sodium chloride. 
     
     
         20 . The electrolysis system of  claim 18 , further comprising a wall separating the first cell from the second cell, wherein the eutectic electrode is disposed along a bottom surface of the first and second cells and the wall intersects, without bisecting, the eutectic electrode. 
     
     
         21 . The electrolysis system of  claim 18 , wherein the alloy electrode contains bismuth, indium and tin in a ratio of 32.5:51:16.5 by mass. 
     
     
         22 . (canceled)