Salt

摘要

Salt, also known as sodium chloride (NaCl), is a readily available inexpensive bulk mineral, used in a variety of important applications such as food processing, chemical production, winter road maintenance, and agriculture. Most countries produce a significant amount of salt with the USA, China, Germany and India being some of the largest. World salt resources are considered to be practically unlimited, with almost every country possessing salt deposits or solar evaporation operations of various sizes. The principal brine reservoirs are the seas and oceans with 1 km~3 of seawater containing an average of 78m. tonnes of salt. Continental brine sources include saline lakes and playas, and are often commercial sources of soda ash, sodium sulphate, potash, and borates with salt as a by-product. Bedded salt deposits are derived from chemical sedimentation either in basins formed on continental platforms or in grabens along continental margins. Salt can move into zones of lower pressure to form thick salt beds, and its buoyancy allows buried beds to rise and create a bulge or pillow, which can break through overlying strata.