System for the electrolytic production of sodium chlorate

Abstract

A system for the electrolytic production of sodium chlorate having a sodium chloride brine buffered with phosphate and having a reduced or zero chromium content is disclosed. The system comprises electrolytic cells of the undivided type with intercalated cathodes and anodes. The cathodes can comprise steel perforated sheets activated with a Fe—Mo alloy coating.

1 . System for sodium chlorate production comprising at least one electrolytic cell equipped with a multiplicity of cathodes and a multiplicity of anodes, fed with a sodium chloride brine added with a buffering agent, wherein the buffering agent comprises at least 1 g/l of phosphate ions. 
     
     
         2 . The system of  claim 1 , the cathodes of the electrolytic cell comprising a ferrous matrix provided with a coating comprising a molybdenum and/or tungsten alloy with at least one metal selected from the group of iron, cobalt and nickel. 
     
     
         3 . The system of  claim 1 , wherein the feed contains chromate and dichromate ions at a concentration not exceeding 0.1 g/l. 
     
     
         4 . The system of  claim 1 , the feed being free of chromium. 
     
     
         5 . The system of  claim 2 , the ferrous matrix of the cathodes comprising a carbon steel. 
     
     
         6 . The system of  claim 5 , the coating comprising a galvanic coating containing 30 to 70% Fe and 30 to 70% Mo expressed as weight percentage. 
     
     
         7 . The system of  claim 6 , the galvanic coating having a thickness between 10 and 50 micrometres. 
     
     
         8 . The system of  claim 1 , the electrolytic cell comprising a cell of the undivided type and the cathodes are disposed in a comb-like fashion intercalated to the anodes. 
     
     
         9 . The system of  claim 8 , the cathodes comprising a ferrous matrix comprising a perforated sheet.