Bromine Production from Bitterns – Bromine is widely available in nature but in small proportions. Bromine and Bromo compounds find their application in textile industry, oil exploration, photography chemicals, insecticides, fuming agents, drugs and pharmaceutical products, manufacture of dye intermediate and dye stuff.
The bromine available for extraction occurs as bromide in the ocean, in salt lakes and in brine or saline deposits left by evaporation of such waters by solar heat. Sea bitterns, the left over concentrated solution after the crystallizing out of salt from the sea water, are very rich in bromine and offers a good raw material for the manufacture of bromine. Sea bittern having at least 2.2 gm/lit bromine, is most suitable for the manufacture of bromine.
The bittern from the reservoirs is taken in sump tank and then fed to the chlorinating tower. After per-chlorination, the cold bitterns is preheated by hot recycle brine and the fed at the top of a stripping tower wherein steam is introduced at the bottom to further heat the bittern to boiling point and strip the bromine liberated by chlorine.
Sulphuric acid is also added to the tower to facilitate stripping of bromine. The liberated bromine with excess steam is passed through the two stage condenser to separate steam and uncondensed bromine and chlorine gas mixture is scrubbed in the chlorinating tower. The crude bromine is separated from water in gravity separator and further purified by fractional distillation and passing through sulphuric acid column. The water condensed overhead of stripping tower and the impure gas emerging from the distillation column are recycled. The debrominated effluent brine is treated with caustic soda and is used for pre-heating chlorinated bittern.