GB887670A - Improvements in or relating to a process for the production of caustic alkali solutions from alkali metal amalgams and to apparatus therefor - Google Patents

Abstract

A process for the continuous production of caustic alkali solution comprises introducing alkali metal amalgam and water or dilute aqueous caustic alkali solution into a column to form therein a dispersion of aqueous phase in the amalgam, separating caustic alkali solution from partially denuded amalgam at the top of the column, passing the partially denuded amalgam from the top of the column into an annulus surrounding the column, introducing water or <PICT:0887670/III/1> dilute aqueous caustic alkali solution into the annulus to form therein a dispersion of amalgam in aqueous phase, removing caustic alkali solution from the top of the annulus and removing mercury from the base of the annulus. The caustic alkali solution removed from the top of the annulus may be mixed with that from the top of the column. In one embodiment, alkali metal amalgam is fed via a pipe 6 to the base of a column 5 packed with graphite rings. Water from a distributer 19 and the amalgam pass upwards in column 5 together with hydrogen generated in the resulting decomposition of the amalgam. The partially denuded amalgam flows through holes 13 into an annulus 9, packed with lumps of graphite, to form a dispersion of amalgam in water introduced into the annulus 9 by a pipe 22. At a level 27, caustic alkali solution formed in the annulus 9 overflows into caustic alkali solution 26 formed in the column 5 and separating above the partially denuded amalgam at the top of column 5. The mixed solutions are withdrawn through a pipe 12. Mercury is removed by a pipe 23 and hydrogen by a pipe 24. Specification 846,603 is referred to.