Brine
Brine is water saturated or nearly saturated with salt (NaCl). It is used (now less popular than historically) to preserve vegetables, fish, and meat. Brine is also commonly used to age Halloumi and Feta cheeses. Although brine is used in preservation much like sugar or vinegar, it can be used to great effect in transportation. Brine is a common fluid used in the transport of heat from place to place. It is used because the addition of salt to water lowers the freezing temperature of the solution and the heat transport efficiency can be greatly enhanced for the comparatively low cost of the material. At a concentration of 23.3%, the freezing point of the solution is lowered to -21°C (252.15 K, -6°F).
At 15.5 °C (288.65 K, 60 °F) saturated brine is 26.4% salt by weight (100 degree SAL). At 0 °C (273.15 K, 32 °F) brine can only hold 23.3% salt.
| Water salinity based on dissolved salts in parts per thousand (ppt) | |||
|---|---|---|---|
| Fresh water | Brackish water | Saline water | Brine |
| < 0.5 | 0.5 - 35 | 35 - 50 | > 50 |
Other uses
- Road treatment
Brine is used to pre-treat roads for winter storms. The solution is poured onto the roadways along with actual salt pellets to create a safer roadway (lowering the freezing point of the surface water, causing snow and ice to melt in higher temperature) when winter weather is in the forecast.
- Heat exchange
Brine is used in removing heat from ice surfaces such as hockey or figure skating rinks. The brine is cycled through the refrigeration plant and returned under the slab of ice at a colder temperature. Brine is used in cruise vessels' cooling systems.
- Heat treatment
Brine is used as quenching medium for cooling ferrous metals.
- Medicinal purposes
In Europe, brine baths are sometimes used medicinally for curing a variety of ailments from skin conditions to bladder trouble.
- Oil extraction
Brine is used in the offshore oil and gas industry where a pipeline, prior to commissioning, is flooded with a meg/brine mix to prevent the formation of hydrates on production start-up. This is dependent on the well properties.
- Mining industry
Brine can be used for underground mining in the Arctic where the ground is permanently frozen (permafrost) in order to use water-fed drills without having them freeze. Chilled brine has also been used for localised freezing of the water table to allow mine shafts to be sunk without the risk of flooding.
- Synthetic Chemistry
Brine is commonly used to dry organic solvents after an aqueous wash. The brine wash is intended to remove the majority of the water from the organic solvent and the remainder is removed by chemical methods (typically anhydrous magnesium sulfate).
- Chemical industry
Brine is electrolyzed in the chloralkali process to make sodium hydroxide, chlorine and hydrogen, as well as the hypochlorite and chlorate salts on an industrial scale. In this case, the chloride ions are oxidized to chlorine, while water is reduced to hydrogen gas and hydroxide anions, which, together with the sodium ions already present, give sodium hydroxide on evaporation.
By adjusting the conditions, the chlorine gas produced also reacts with the hydroxide anions to give hypochlorite and chlorate anions as well.
It is also used in the Solvay process to produce sodium carbonate, and in the solution mining of salt from underground deposits. Brines are also used in the pharmaceutical industry.
When used for industrial purpose, brine is generally transported by pipeline made with welded steel pipes, coated for corrosion protection.