This page gives an illustration of the production capacity of the site in 2003.

Sea water contains around 65 grams of bromide per tonne. If we assume that the BOT extraction process is around 80% efficient during the summer months. One BOT pumping 180,000 gpm of sea water will result in the extraction of around 2.5 te of bromine each hour.The variation of sea water flow and extraction efficiency throughout the year means that the maximum capacity of both BOTs is around 38,000 tonnes of bromine per annum. A one percent increase in extraction efficiency throughout the year would result in an extra 400 tonnes of bromine being made which would generate an extra £250,000 per annum income.

Before the bromine can be extracted, the sea water must be adjusted to the optimum pH of 3.4. The various salts in sea water have a buffering effect on pH changes. The change in pH requires the equivalent of 0.135 tonnes of 98% sulphuric acid per tonne of sea water. Which is equivalent to 2.6 tonnes of strong sulphuric acid per tonne of bromine produced. This acid is produced by burning around 1.2 tonnes of sulphur. The control of BOT main to the correct pH has a major effect on acid usage. A change in pH from 3.5 to 3.2 will need a two fold increase in acid usage. With an SOT operating to maintain PAL acid stocks we use around 120 tonnes per day of strong acid to adjust the pH for operation of both BOTs.

The amount of chlorine used to convert the bromide in the sea water to bromine is around 104 % of the theoretical amount. This is around 0.46 tonnes of chlorine per tonne of bromine produced.

 2HBr + Cl2 = Br2 +2HCl

The bromine is converted back to bromide using SO2 gas to produce Primary Acid liquor.

Br2 + SO2 + 2H2O = 2HBr + H2SO4  

This requires 0.4 tonnes of SO2 per tonne of bromine. The BOT process has resulted in the concentration of bromine being increased from 65 grams per tonnes in sea water to around 0.150 te/te in PAL.

The PAL is next treated in the steaming out tower where the bromide is converted back to Bromine. This again needs around 0.46 tonnes of chlorine per tonne of elemental bromine produced.

The production of 1 tonne of elemental bromine has hence used:-

  • 4,320,000 gallons of sea water.
  • 2.6 tonnes of 98% sulphuric acid.
  • 0.4 tonnes of SO2 gas.
  • 0.92 tonnes of chlorine
  • MWH of electrical power.

The elemental bromine produced can be converted to dibromoethane (DBE)

C2H4 + Br2 = C2H4Br2

This requires 0.18 tonnes of ethylene per tonne of bromine converted.

The bromine can also be burnt in hydrogen to produce Hydrogen bromide gas for conversion to hydrobromic acid , compression to liquified gas or use in down stream products.

Br2 + H2 = 2 HBr

The conversion of one tonne of bromine needs 0.01 tonnes of hydrogen.

The HBr gas can be reacted with Dichloromethane (DCM) to give Bromochloromethane (BCM) or Dibromomethane (DBM). This is achieved using Aluminium Chloride as the catalyst. The HBr conversion efficiency is around 80%.

C2H2Cl2 + HBr +AlCl3 = C2H2ClBr + HCl + AlC3

The production of one tonne of BCM needs 0.68 tonnes of DCM and 0.72 tonnes of HBr gas. The conversion of DCM to one tonne of DBM needs 0.52 tonnes of DCM and around 1.1 tonnes of HBr.

C2H2Cl2 + 2HBr +AlCl3 = C2H2Br2 + 2HCl + AlCl3

 Hydrogen bromide gas can also be used in various processes on the MPBF plant.

 Allyl Chloride + Hydrogen Bromide = Bromochloropropane

CH2CHCH2Cl +             HBr           = BrCH2CHBrCH2Cl

  • Tonnes   +   0.34 Tonnes         = 1 Tonne

n-Propanol         + Hydrogen Bromide = n -propyl bromide

CH3CH2CH2OH +         HBr               = CH3CH2CH2Br

  • Tonnes       +   0.66 Tonnes       = 1 Tonne

Each BOT will run at a maximum sea water flow rate of around 180,000 gallons per minute. The tidal cycle means that the mean flow is less than this. In addition during the winter months high pumping cost and low extraction efficiency make high flows uneconomic.


The annual site capacity to produce Bromine is thought to be just under 40,000 tonnes per year.


The steaming out towers are capable of running at up to 36 tonnes per hour of PAL. This is equivalent to around 5.4 tonnes per hour of crude bromine. Equivalent to 47,000 tonnes per annum Br2

 We have three bromine driers each capable of packing at a maximum rate of around 1.5 tonnes per hour. This is equivalent to around 39000 tonnes per annum of dried bromine.


Normal requirements are met with only two of the three driers being used. Packing rates of around 3 tonnes per hour are normal. This is around 26,000 tonnes per annum of dried bromine.


We have four DBE reactors. Each reactor can produce around 1.25 tonnes per hour of DBE. This is equivalent to around 44,000 tonnes per annum of DBE. Which would need around 37,000 tonnes per annum of Bromine.


Normal requirements are met with only two of the reactors on line making around 22,000 tonnes per annum. Which needs around 19,000 tonnes per annum of bromine and 3300 tonnes of ethylene.


We have two HBr burners which are currently limited by our IPC authorisation to 600 Kg/hr of bromine. This is equivalent to around 1200 kg/hr of 48% acid. However the HBr acid absorber is limited to 1000 kg/hr of 48% acid make. This is equivalent to around 8750 Tonnes per annum of 48% HBr acid.


The HBr liquefaction plant has a feed of up to 50 kg/hr of HBr gas. The liquefaction efficiency is around 70% giving a maximum annual make of around 300 tonnes of liquid. The plant is run on a campaign basis and the make is around 2/3 of the maximum.


The DBM / BCM plant is designed to make a maximum of 2.5 tonnes per day DBM. Alternatively it can be run to make around 2 tonnes per day DBM and 0.5 tonnes per day BCM. This gives around 700 tonnes per annum of DBM and 180 tonnes of BCM. It uses around 400 tonnes per annum of DCM.