Patent ID: 6224740
Filing Date: 2001-05-01
Classification: C25B

Abstract:
A process for electrolysis of a sodium chloride-containing brine in which an amalgam electrolysis unit and a membrane electrolysis unit having an oxygen consumable electrode are operated in parallel with a common brine circuit comprisinga) feeding brine from a salt dissolution station to a precipitation and filter station,b) removing sulfate, calcium and magnesium ions from the brine in the precipitation and filter station,c) dividing the brine from b) into(1) a main stream and(2) a sub-stream,d) electrolyzing main stream (1) in the amalgam electrolysis unit,e) pre-treating sub-stream (2) in a dechlorination station,f) treating the sub-stream from e) in a hydroxide precipitation station,g) optionally, removing calcium and magnesium ions from the brine of f),h) electrolyzing the brine from f) or g) in a membrane electrolysis unit,i) combining the brine from d) and from h) to form a stream (3) andj) electrolyzing stream (3) in an electrolysis unit having a mercury-resistant oxygen consumable cathode.