VERFAHREN ZUR HERSTELLUNG VON ALKALIHYDROXID, CHLOR UND WASSERSTOFF DURCH ELEKTROLYSE EINER WAEBRIGEN ALKALICHLORIDLOESUNG IN EINER MEMBRANZELLE.

摘要

In the prodn. of alkali hydroxide, Cl2 and H2 by membrane electrolysis of an aq. alkali chloride soln., a solid impure salt rich in NaCl is dissolved in water in a dissolver, the salt soln. is treated with chemicals to ppte. the impurities and transferred to a thickener, where the ppte. is sepd., then the clarified crude brine is discharged, subjected to fine purificn. and passed to membrane electrolysis and the spent brine is passed to the salt dissolver. The novel features are that the clarified crude brine from the thickener is divided into 2 sub-streams in 2-20:1 ratio. The first, large sub-stream is mixed with the salt soln. and chemicals used for pptn. before the thickener and the mixt. is transferred to the thickener, whilst the second sub-stream is subjected to fine purificn.