How Do We Get Salt from Seawater?

Salt is primarily obtained from seawater through evaporation. This process leverages the fact that water evaporates, leaving behind the dissolved salts. This method has been used for centuries and remains a significant source of salt production globally.

Several techniques are used to extract salt from seawater, all relying on the principle of separating water from dissolved solids:

• Solar Evaporation: This traditional method utilizes the sun's heat to evaporate water from shallow ponds or basins filled with seawater. The remaining concentrated brine is then further processed to yield salt crystals. This is a cost-effective, low-energy method, often used in regions with abundant sunshine. The process can take several weeks or months depending on weather conditions. [This process is described in several references.][1, 7, 8]

• Boiling: Seawater can also be boiled in large containers. As the water boils and turns into steam, the salt remains behind. This method is faster than solar evaporation but requires significant energy input. [References confirm that boiling is a viable method.][2, 5] For example, boiling two gallons of seawater can take approximately four hours. 5

• Freezing: In colder climates, seawater can be frozen. As the water freezes into ice, the salt remains in the unfrozen brine, which can then be further processed to obtain salt. This alternative method is mentioned in one reference.

The Composition of Sea Salt

It's important to note that sea salt isn't purely sodium chloride (NaCl). Seawater contains various dissolved salts and minerals. While sodium and chloride ions constitute the majority (over 90%), other ions like magnesium, calcium, potassium, and sulfate are also present. [9, 10] The exact composition varies depending on the location and specific conditions of the water source.

Commercial and Industrial Salt Production

Commercial salt production involves large-scale operations employing sophisticated techniques that may include multiple evaporation stages, and specialized equipment for purification and processing to ensure high purity standards for various applications.

[1]: Evaporation is the method for extracting common salt from seawater.