Process for preparing reactive zinc by electrochemical reduction

Abstract

The invention relates to a process for preparing reactive zinc by electrochemical reduction, wherein iron or steel is used as cathode material.

1 - 9 . (canceled) 
     
     
         10 . A process for preparing reactive zinc, the process comprising:
 a) filling an electrolysis cell comprising a cathode and a zinc anode with at least one electrolyte selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and a tertiary amide, the electrolyte further comprising:
 at least one redox mediator selected from the group consisting of naphthalene, N,N-dimethyl-1-naphthalene, a 1-substituted naphthalene, phenanthrene, anthracene, 4,4′-bipyridyl and 4,4′-di-tert-butylbiphenyl; and 
 at least one electrolyte salt selected from the group consisting of tetrabutylammonium fluoroborate and sodium methylsulfonate, 
   b) applying an electric current to the cell until a 2-20% by weight strength suspension of reactive zinc in the electrolyte is formed,   
       wherein the cathode comprises iron or steel and the applying of the electric current is carried out at a temperature in a range from 20 to 60° C. 
     
     
         11 . The process of  claim 10 , wherein the at least one electrolyte is N,N-dimethylformamide. 
     
     
         12 . The process of  claim 10 , wherein the at least one electrolyte salt is tetrabutylammonium tetrafluoroborate. 
     
     
         13 . The process of  claim 10 , wherein the applying of the electric current is carried out at a temperature in a range from 35 to 45° C. 
     
     
         14 . The process of  claim 10 , wherein a current density of from 1 to 4 A/dm 2  is employed. 
     
     
         15 . The process of  claim 10 , wherein the electrolysis cell is an undivided electrolysis cell. 
     
     
         16 . The process of  claim 10 , wherein the cathode is an iron or steel tube and the zinc anode is arranged concentrically within the cathode. 
     
     
         17 . The process of  claim 10 , wherein the process is carried out batchwise. 
     
     
         18 . The process of  claim 10 , wherein the process is carried out continuously. 
     
     
         19 . The process of  claim 11 , wherein the at least one electrolyte salt is tetrabutylammoniurn tetrafluoroborate. 
     
     
         20 . The process of  claim 11 , wherein the applying of the electric current is carried out at a temperature in a range from 35 to 45° C. 
     
     
         21 . The process of  claim 12 , wherein the applying of the electric current is carried out at a temperature in a range from 35 to 45° C. 
     
     
         22 . The process of  claim 10 , wherein a current density of from 1.5 to 3 A/dm 2  is employed. 
     
     
         23 . The process of  claim 10 , wherein a current density of from 1.5 to 2.5 A/dm 2  is employed. 
     
     
         24 . The process of  claim 11 , wherein a current density of from 1 to 4 A/dm 2  is employed. 
     
     
         25 . The process of  claim 12 , wherein a current density of from 1 to 4 A/dm 2  is employed. 
     
     
         26 . The process of  claim 13 , wherein a current density of from 1 to 4 A/dm 2  is employed. 
     
     
         27 . The process of  claim 18 , further comprising, after obtaining a 2-20% by weight strength suspension of reactive zinc,
 c) discharging the electrolyte from the electrolysis cell, and simultaneously introducing an equal amount of a fresh electrolyte.