The process of manufacture of Bromine from Sea Bitterns is given below :-
The bittern is acidified with Sulphuric acid to a pH of 3.5 and pre-heated to 85 to 90 deg C. The hot bittern is run through a tall granite tower packed with raschig rings while low pressure stress and a 10% excess of the theoretical chlorine are introduced slightly above the bottom of the tower and made to pass in counter current direction at suitable rates.
MgBr2 + Cl2 พพพพพ> MgCl2 + Br2
The Bromine is liberated in vapour form which is condensed in a tantalum condenser along with steam and some chlorine and then taken to the gravity separator, where Bromine and water layer are separated.
Manufacturing Process of Bromine (Developments in the process routes).
The first economically successful recovery of Bromine directly from the sea was carried out near Wilmington, North Carolina (USA), using an air-blowing process originally developed for brine operations by H.H. Dow, USA.
The use of air rather than steam has been preferred, because the cost of steam to heat ocean water, with its Bromine content of only about 65 mg/litre. would be prohibitive.
Another process for the recovery of Bromine from sea water was developed on a commercial scale by Ethyl Corporation in the US. The process involved the treatment of seawater with chlorine and aniline and collection of the precipitated Tri bromo aniline.
Current bromine production methods are based on modified Kubierschky or steaming out processes and the Dow chemicals blowing out process.
Bromine producers have formed the Bromine Science and Environmental Forum to tout the safety and value of bromineproducts, including bromine based flame retardants.
The group says that it will sponsor research on bromine compounds to evaluate health and environmental effects. It will also "act as the industry's global voice" on environmental issues and seek to ensure that scientific information on its products is advanced and more widely understood." The group consists of Albemarle, Dead Sea Bromine, Great Lakes Chemicals, Elf atochem and Tosoh.