Page 12 - Curriculum Visions Dynamic Book

Mining salt
Salt is one of the most important minerals used today.
It is used as pure sodium chloride and also as the raw material for obtaining sodium and chlorine for other processes.
Salt occurs in thick rock beds and also in sea water.
Salt pans (evaporating sea salt) produce only a small amount
of the world’s need for salt. This is because salt is used in greater quantities and for more applications than any other mineral. Most salt is therefore obtained from underground rocks.
Solution mining
Some salt beds cannot be mined by blasting. Instead the salt is recovered by dissolving it. First a deep well is sunk down to the salt bed or dome. Hot water is then fed down the outside of the well. The water dissolves the salt, and the resulting brine is drawn back to the surface.
When the brine reaches
the surface, the water is evaporated away using special vacuum flasks.
 A diagrammatic representation of how salt is brought to the surface as a brine solution. The salt may occur as beds or as salt domes.
Deep mining
Most salt is obtained from salt beds deep underground. In some cases it is possible to mine the salt in a fashion something like coal mining. A shaft is sunk and horizontal galleries are opened out into the salt beds. The salt is a true rock and is recovered by blasting it and then hoisting it to the surface.
Once the rock salt has reached the surface it is crushed to different sizes, depending on its intended use.
Water pumped down into salt dome
Brine pumped up to the surface
Water dissolves rock salt in a dome to make
a concentrated salt solution called brine.
This can then be drawn back up to the surface.
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