Salt Mine?

Who knew Arizona had a salt mine? In fact, one of at least three is in Glendale. That was last Saturday's adventure...geocaching in Glendale and neighboring communities.

Twelve to fifteen million years ago, this area was filled with large lakes which did not drain out to the sea. Over time the water evaporated and formed the salt deposit known as Luke Salt Deposit. The deposit is estimated between one and ten thousand feet deep, an estimated 15 cubic miles of salt in the Basin and Range Region.

There are no mine shafts at this salt mine. The salt is harvested from solar salt brine ponds. The plant pumps water into the salt deposit. The salt dissolves and the saturated fluid (brine) is pumped out into evaporation ponds. Arizona's sun, wind, and low humidity remove the water from the brine causing salt crystals to form and settle to the bottom of the four to five foot pond.

At this plant the salt is harvested from the solar ponds by a special harvester that removes the salt from the pond's bottom while it is still covered with brine. Most other solar salt facilities drain the brine from the pond and then harvest the salt from the dried pond.

The salt crystals and brine are pumped to a wash plant where the crystals are separated from the brine and washed. The salt is stockpiled to cure before processing. After several days of curing the salt is taken from the stockpile to a kiln for drying. After drying the salt is screened into various grades for its end use.

About two-thirds of the salt harvested at this plant is used for water softening products. The remaining third is used for agricultural and industrial use. This plant started operation in 1969.

 In this area a mile or so from the salt mine, the small hills are caused by the soil being pushed up by the salt deposits. 

A sodium chloride salt deposit is located near Kingman and the other Arizona salt mine is near Eloy. It is anhydrite salt or a calcium sulfite salt. 

Who knew!