This module highlights the different sources of salt, and emphasizes how salt is produced. Background Geologists believe that all salt deposits were formed from the oceans or from enclosed bodies of salt water. Evaporating water left beds of salt, which in many cases were buried by rock strata formed from other sedimentary deposits. Beds of salt range from a few feet to well over a 100 feet in thickness. Layers of salt deeply buried by rock strata may become mobilized by great pressure and flow upward to form salt domes.
Salt domes are a source of salt for many salt mining operations.
In conventional underground salt mining a shaft is sunk into the deposit, where the salt is drilled, undercut and blasted with explosives, similar to coal mining. Trucks or shuttle cars carry the broken salt to a preparation station where it is crushed and screened into commercial grades. The salt is then hoisted to the surface for packaging and bulk shipment by truck, rail, ship or barge. In solution mining, fresh water is injected through a well casing into the salt deposit. A second or concentric pipe removes the brine formed when water dissolves the salt.