BROMINE RECOVERY PLANT

It is a deep red fuming liquid, member of the halogen elements as Group VII of the periodic table that is liquid at ordinary temperature and pressure. A rare element bromine is found in, nature dispersed throughout the earth crust only in compounds such as soluble and insoluble bromides. The chief commercial source of bromine is ocean water from which the element is extracted by means of chemical replacement (oxidation) by more active chlorine. Bromine has traditionally been manufactured as a byproduct from saline mother liquors (bitterns) left after the crystallization of the main salt products.

The properties of bromine are significantly different from those of fluorine and chlorine. Discovered in the early 19th century, in the form of its salts (bromides) in the bitterns remaining after evaporating sea water and extracting the sodium chloride, it was obtained latter from stassfurt, Germany, as a byproduct in the production of potassium salts and from other deposits and salt lakes.

Its main use was originally for bromides in medicine still a minor use. Bromine first because of industrial importance with the development of modern photographic process, in which the light sensitive material is an emulsion of minute particles of silver bromide (together with silver chloride or iodide or both) in gelatin.

For a time, the expanding world automobile industry. Threatened a scarcity of bromine, obtained from brines, which contained about 0.5% bromine. To meet the demand, it was necessary to turn to sea water which contains about 70 ppm bromine.

The chief sources of bromine are sea water, brines and betters and the natural deposits of potassium salts. In these, it is present in very small quantities in the combined state. Sea-water contains, 66 parts per million (0.0066 %) of bromine and in 1933, the DOW Chemical Co., (U.S.A.) developed a process for its recovery. Large quantities of bromine are now being produced both from the sea and from the salt & lakes. The U.S.A. is now the world largest producer and used the entire output for the manufacture of ethylene bromine.

The other prominent bromine producing countries are Germany and France.

Bromine, a heavy, mobile, reddish-brown liquid with an interesting irritating odour, is the only non-metallic element that is a liquid at normal temperature. It is a diatomic molecule with the chemical formula.

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 offer a good raw material for the manufacture of bromine. Bromine is extracted from seawater.

USES, SOURCE AND SAFETY OF BROMINE

Use of Bromine

Bromine is widely used in the chemical and pharmaceutical industries. Major applications are brominated organic components used as

• Flame retardants (e.g. polybrominated biphenyls)

• Pesticide (e.g. methyl bromide)

• Reactive intermediates in organic synthesis and pharmaceutical ingredients

Sources of Bromine

Natural sources for bromine are chloride sources such as natural salt stocks and seawater where bromides are accompanying the chlorides. Industrial sources for bromine recovery are quench waters of waste incinerators (coming from the flame retardants) and effluents of industrial bromination processes.

The reactions to form the a.m. chemicals may generate hydrogen bromide as a by-product:

R-H+Br2 => R-Br+HBr

In this case no more than half of the bromine added ends up in the product, the rest being released as hydrogen bromide gas and as dissolved bromides (often rejected in washing solutions). Since bromine is an expensive, widely used raw material, recovery is usually a viable option.

Safety First

Bromine is highly corrosive, toxic, and causes serious chemical burns. 3 ppm in the air is considered immediately dangerous to life and health. Therefore, it is vitally important to take the highest safety precautions when working with bromine.

Accordingly, plants processing bromine have to be made of highly corrosion and diffusion resistant, robust materials. QVF borosilicate glass 3.3 and glass-lined steel are ideal materials for their construction. All measures are taken to avoid any bromine leakage; the equipment fulfills ASME requirements for pressure and tightness of flange connections. For extra safety measures, the vent systems are equipped with bromine scrubbers.