Kansas Geological Survey, Public Information Circular (PIC) 21
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Salt Production

Salt is mined in Kansas using two methods: underground mining and solution mining. Underground mines in Kansas (fig. 5) range in depth from 600 to 1,000 feet. They use the room-and-pillar method of mining, which begins with a shaft sunk through the overlying rock to the salt deposit. The salt is removed in a checkerboard pattern, in which large square caverns alternate with square pillars of salt that serve as support for the rock above. Approximately 75 percent of the salt is mined, while 25 percent is left for pillars. Blasting breaks the salt into manageable pieces, which are conveyed to crushers and removed to the surface through the shaft with large buckets. Because of the impurities (mostly shale and anhydrite), rock salt is used mostly as road salt for melting ice. Active underground salt mines are found in Lyons, Kanopolis, and Hutchinson.

Figure 5--Underground salt mine at Hutchinson. Salt is mined in a room-and-pillar fashion, and moved along a conveyor belt and eventually to the surface.

Early mining of the deep salt beds in central Kansas was done by solution mining, and this process continues today. Solution mining uses water to dissolve the salt. Freshwater forced down a cased well dissolves the salt and produces an artificial brine, which is then pumped to the surface and evaporated to recover the salt. As long as freshwater is added and saturated brine removed, the cavern continues to enlarge. The shape of the cavern is controlled by directing the water. A sonar tool is used to measure the shape and size of the cavern.

Evaporation plants produce a variety of salts for which purity is essential, such as table salt, food processing salt, salt for animal feeds, and water softening salt. Brine is evaporated in a series of large vessels called vacuum pans. The result is a high-purity product consisting of over 99.8% sodium chloride.

In 2000, Kansas ranked fifth in the U.S. in salt production, producing 2,944,000 tons valued at $111 million. Roughly 13 trillion tons of salt reserves, about 1,100 cubic miles, underlie Kansas. This is enough to form a salt cube more than 10 miles long on each edge.

Underground space created by salt mining is also valuable. In the Hutchinson mine, space is leased for high-security record storage. The constant temperature and humidity make an ideal environment to archive fragile items such as classic movies, paintings, furs, and collections. In the 1960's, the Atomic Energy Commission studied a salt mine in Lyons for the potential storage of high-level radioactive waste, an idea that was eventually abandoned. Today, an underground mine in Hutchinson is being developed into a salt museum. [Now open. Information at http://www.undergroundmuseum.org/ as of Aug. 2008.]

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Why are the Quivira Salt Marshes Salty?

Kansas Geological Survey, Public Outreach
Web version July 2002
http://www.kgs.ku.edu/Publications/pic21/pic21_3.html