In industrial countries, the salt is mechanically harvest and washed with saturated brine. After that, the salt is washed with freshwater before being stored for use, sale or further processing.
Salt Mining
The evaporation of ancient salt lakes results in the formation of underground salt deposits. The thick layers of salt are in the natural and impure form, known as rock salt. These layers are found about 300 m below the ground surface.
The salt deposits can be dug from underground mines by usual excavation methods(Figure 2.5 ). The rock salt is drilled and blasted out, then transported to the groundsurface. Underground caverns are formed from the removal of the salt deposits.As long as pillars of rock salt are left in place, these caverns will not cave in.
The mined rock salt can be used to grit roads in winter to prevent vehicles from skidding (Figure2.6). In this case, the salt used does not have to be pure. For purposeswhich require pure salt, the rock salt obtained from mining is refined to purify it.