Done by: Li Shida (1O2)

How is Sodium Chloride(Salt) obtained commercially?

Definitions

• Brine solution: H2O + NaCl (water + salt)• Commercially (In This Case): Methods that are

used to obtain NaCl is suitable for commercial uses.

3 Main Methods

• Solar Evaporation• Rock Salt mining• Vacuum Evaporation

Solar evaporation

• Oldest Method• First observed in sea water caught in holes

and evaporate to form salt as a natural process

• Was manually done by our ancestors to obtain salt

• Commercialized now days • Evaporation, Filtration and Crystallization used

Step 1

Step 1: Diverge large amounts of sea water into salt ponds.The ponds must be large in total area for commercial production.

Step 2

Step 2: Wait for natural evaporation• This process might take 2 years• Concentration of water causes crystallization• Chemicals such as calcium carbonate will

crystallize first and will be removed• Sunshine and wind are key factors. The more

of these, the faster the evaporation will take place.

Step 3

Step 3: Removal of brine solution into crystallizing ponds• The saturated salt solution will be filtrated and

pumped into crystallizing ponds• Other impurities that are not dissolved will be

drained away

Step 4

Step 4 : Crystallization & final cleaning• All water will evaporate in the crystallization

ponds, forming solid NaCl of purity more than 99.7%

• The NaCl will then be washed with brine solution. Since no salt can dissolve more in the brine solution, there will be no loss

• 99.8% purity of NaCl is finally obtained

Separation Methods used

• Filtration: Impurities that can affect the quality of NaCl production is removed

• Evaporation: Saves energy as compared to manual heating. Concentrates water

• Crystallization: To obtain almost pure dry NaCl, the final product

Diverge Sea water into

evaporation ponds (~3.5% concentration)

Removal of impurities

Natural Evaporation

(~99.7% concentration)

Crystallization & Final

cleaning

Method 2: Rock Salt Mining

• Second oldest method• Mines rock salt underground2 types of rock salt deposit: Vein form and dome formVein form: salt deposit spreads over a large area like veinsDome form: Salt chunked together in large amounts

Step 1

Step 1: Locating & Blasting• After a salt deposit is located, explosives will

be used to make them fall to the ground. Older methods such as mining was also used.

Step 2

Step 2: Crushed into manageable chunks & hauled to the surface• Transportation of rock salt requires it to be

smaller in size

Step 3

Step 3: Screening• The rock salt is screened to make sure that its

quality is of standard.• Some minerals must be removed because it

might be harmful.• A brine solution might also be used to treat it.

The solution might also be filtrated to leave the rock salt as the residue.

• 99. 8% purity of NaCl is obtained

Methods used & Process

• Filtration: Filters the unwanted minerals away. Important for quality control of the salt.

Locating and

Blasting

Crushing and

Hauling

Screening

Vacuum Evaporation

• Dissolving rock salt or solar salt in water to create a brine solution, then boiling off the water to leave behind pure salt.

• Newest and most high-tech method• Lowers atmospheric pressure to lower boiling

point• Can increase purity to 99.99%

Step 1

Step 1: Dissolving• Rock salt or solar salt is dissolved to obtain a

brine solution• Normally done in large amounts

Step 2

Step 2: Boiling• The brine solution will be pumped into a

vacuum• The boiling point lowers since there is less

atmospheric pressure in a vacuum• Water is boiled away to obtain 99.99% purity

of NaCl

Interesting facts about vacuum evaporation

• Purifies salt to meet high standards of purity• The vacuum “boiling pots” can be stacked

together, with pots on top having a lower atmospheric pressure than pots below. The water vapor from the lower ones can cause the upper one to boil, saving energy and money

Methods used & process

• Evaporation: Separation of NaCl and H2O was very important and evaporation does the job well

Dissolving

Boiling

Bibliography

• http://www.scribd.com/doc/17490071/How-is-Salt-Produced

• http://www.saltinstitute.org/Production-industry/Production-technologies/Solar-salt-sea-salt

• http://www.mortonsalt.com/salt-facts/salt-production-and-processing

• http://www.bigsiteofamazingfacts.com/how-is-salt-made

• http://www.madehow.com/Volume-2/Salt.html

• http://www.cargill.com/salt/about/howsaltismade/index.jsp

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