Located 5km from our Middlewich production facility, our Warmingham Brinefields contain extensive salt reserves.

At a depth of 180m to 500m below the surface, salt deposited over 300 million years ago - when Cheshire was in the tropics - sits in between layers of rock.

The salt is extracted using sustainable solution mining techniques, whereby the salt is converted to brine which is then pumped across to the main salt plant.

Over time, the extraction of salt forms large cavities that can be 100m wide.

Many of British Salt’s old production cavities are in use for storing natural gas, providing the UK with gas storage used to help balance gas supplies.

The salt is extracted from strata that lie approximately 180 metres (590 ft) below ground. Bore holes are drilled into the strata and water is forced down to dissolve the salt. The resulting brine solution is pumped along 5 km (3.1 mi) of pipes back to the surface and direct into the Middlewich factory for purification and water evaporation to produce the pure salt. It is estimated that there are salt reserves sufficient for 200 years.

Purification
Once the brine is pumped to the main plant it goes through a multiple stage purification process, removing impurities which are naturally present in the salt deposits. The brine is purified through a series of settlement tanks and reaction vessels.

-Three stages of purification remove magnesium, sulphate and calcium carbonate impurities.

-The quality of brine is constantly monitored via an advanced analysis and monitoring system, to produce the highest purity final salt and ensure efficient operations.

-The impurities extracted are returned to the brine field in a mature cavity.

-The purified brine is then either used in the next stage of production, the evaporation process, or is available for purchase for use as a finished product.

Evaporation
The purified brine undergoes a final filtration before being passed into the first of six evaporation vessels. The brine is boiled under vacuum, a process which is hi ........