Two types of process are available for the recovery of Bromine from Sea Bittern.

In order to maintain the efficiency, cold process is used to recover bromine from low concentration (less than 0.5 GPL) brine and hot process is used for high concentration (more than 1.5 to 6 GPL) bittern.

Cold Process

Technology - Air Blowing Process
In these process there are two stages, the acidified bittern is chlorinated then stripped in a column using air and then the liberated Bromine is absorbed in an alkali solution to form Bromides. Thus obtained Bromide is acidified/chlorinated again in a tower and bromine is stripped using steam and then condensed to liquid. This impure bromine is purified in a reflux column and packed. The overall efficiency of the process is only 70 to 75 %

Hot Process

Technology – Steam Feed Process
In this hot process, bittern is acidified to reduce the PH. This is then fed into the packed reaction column. Chlorine and Steam are fed from the bottom of the Column. The chlorine replaces the bromine and bromine vapours are passed to the condenser. The condensed bromine with chlorine as impurities is passed to the reflux column. In the reflux column, the mixture of bromine and chlorine are boiled using steam. As chlorine has a lower boiling point it evaporates leaving behind a rich mixture of bromine. The overall efficiency of the process is 90 to 95%
Reactions: MgBr2 + Cl2 ---------------- MaCl2+Br2
Even though the initial investment is marginally high, the hot process is preferred due to the following reasons: -

  • Single Stage Operation
  • High efficiency
  • Low production cost
  • Better quality

Process Flowchart

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Acidification Bittern is acidified to 3 pH using HCl or H2SO4
Oxidation Na Br present in bittern Oxidised using Cl2 to replace Br2
Stripping Replaced Bromine vapour Stripped using steam
Condensing Bromine vapour and little steam condensed to liquid form.
Physical separation Crude Bromine and water separated using phase separator
Purification Crude Bromine purified in reflux column using steam
Bottling Pure Liq. Bromine filled in glass bottles and packed
Bromine Min 99.900%
Chlorine Max 0.010%
Iodine Max 0.050%
Sulphate Max 0.150%
Residue Max 0.050%
Sp. Gravity Max 3.093% at 27° C
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