Solution mining of salt is done by injecting hot water under pressure down a well into a subsurface layer of rock salt. That same water is then withdrawn up to the surface through a nearby recovery well. While the water travels through the layer of rock salt – from the injection well to the recovery well – it dissolves a significant amount of salt. The water is returned to the surface as a concentrated salt solution known as “brine”.

Most solution mining sites in the United States are operated by chemical companies who use the brine as a feedstock at a chemical manufacturing plant a short distance from the recovery well. A few solution mining sites have ponds at the surface where they produce solar salt. Others use heat or a vacuum heating process to recrystallize the salt. These recrystallized salts have a higher purity than salt mined from the same rock unit. The recrystallized salt is a higher quality and higher purity because insoluble mineral matter and other insoluble impurities were left in the ground.