Monica Wolodkowicz, age 9, of Mundelein, I11., for her question:

HOW IS SALT PRODUCED?

Salt is found in many different countries around the world and in the following of the United States: New York, Ohio, Michigan, Kansas, Louisiana, Virginia, Texas, West Virginia, Pennsylvania, Utah, New Mexico, California, Oklahoma, Idaho, Nevada and Hawaii. It probably represents the residue left when ancient seas evaporated.
Rock salt is mined in many countries and in the states of New York, Louisiana, Michigan, Texas, Kansas, Utah and California. A few are surface mines but most are operated in the same manner as coal mines. Shafts are drilled and galleries run into salt deposits. Drills are run by compressed air and electric crushing and shoveling machines are used to break up and load the salt. The salt is then crushed and screened into various size crystals.
Most salt, however, is produced in the United States, Canada and Great Britain with the well system rather than by mining.
With the well system of obtaining salt, a hole is drilled down into a rock salt deposit with a double casing or pipe, one inside the other, being put into the hole. Water is then pumped down the outer casing into the salt vein. A brine is formed which is then forced up the inner casing by the pressure of the fresh water coming down. If the well is especially deep, a compressed air pipe is dropped down partway in the inner casing to aid in bringing the brine water to the surface.
A great advantage in the well system of obtaining salt is that all insoluble impurities, such as rock or shale, remain in the earth.
After the brine is allowed to settle and has been chemically treated to remove impurities, it is evaporated either in open evaporators or in a vacuum evaporator.
Salt is also obtained from oceans or salt seas and lakes. Quantities are pumped into large ponds where it is allowed to evaporate until it becomes thick with salt. The water is then pumped or run into other ponds where impurities are scientifically removed and salt crystals are allowed to form. The finished product with this production method is of high quality.
One major salt product is production of blocks of rock salt for animals to lick. Blocks are pressed from fine evaporated salt in hydraulic presses. Blocks are made hard enough to resist weather but not too hard for animals to get what they need.
Salt is also used in refrigeration, ice plants, refrigerator cars, cold storage, pickling, preserving, curing and medicine. It's also heavily used in the chemical industry.