As seawater is moved through a series of evaporating ponds, the various minerals evaporate before the salt does, leaving a product that is 95 to 98 percent sodium chloride, the encyclopedia says. Salt also is mined from rock salt, the huge deposits beneath the ground. This method requires that about half of the salt be left behind as pillars. In solution mining, a well is drilled into the ground and two pipes are lowered into the hole. The pipes consist of a small central pipe inside a larger pipe.
Fresh water is pumped down the central pipe to the salt deposit.
The water dissolves some salt to form brine, which is pumped to the surface through the outer pipe. The brine is either shipped as a liquid or evaporated in special devices called vacuum pans to form solid salt. You can get a list of minimum requirements for a dealer's license from the Department of Motor Vehicles' Enforcement Section. The Fayetteville office is on the second floor of the N.C. Highway Patrol building beside the Cumberland County Civic Center. The phone number is 486-1331.