There are three methods used to produce salt: solar evaporation, rock salt mining, and vacuum pan evaporation.
Solar Evaporation Method
The oldest method of salt production known to man is solar evaporation. Solar salt production is the capturing of sea water in shallow ponds where the sun evaporates most of the water. This method uses two types of ponds — concentrating ponds and crystallizing ponds. In the concentrating ponds, the water from the sea or ocean evaporates due to the effects of sun and wind. The highly concentrated salt brine is then drained into the crystallizing pond. In the crystallizing pond, the salt crystals begin to grow. When the salt layer is thick enough, the salt is harvested with a mechanical harvesting machine.
Rock Salt Mining Method
The underground mining of salt is the second oldest method of producing salt. There are two shafts in each Morton mine: one for personnel and one to lower equipment and materials into the mine, as well as to hoist the mined salt to the surface. Large chunks of salt are crushed and the salt is then loaded into “Skips” (large holding bins) and then hoisted above ground.
Vacuum Pan Evaporation Method
In this method, salt from any of several sources is dissolved to create saturated brine. This brine is then pumped into vacuum pans. The steam vessels are normally in a series of three. The brine is pumped into the pans, steam is then introduced. When the brine reaches the boiling point, the brine separates into steam and the salt begins to crystallize. The heavier salt crystals will fall to the bottom of the pan in a slurry. The salt slurry is then drawn off and sent to the dryer wheel.