Sodium sulfate (Na2SO4) is one of the most important minerals in the chemicals industry.
Natural sodium deposits are formed by a long geologic process of the erosion of igneous rocks, the transportation of sodium from these rocks and chemical reactions. First, the sodium is released from igneous rocks when they weather and break down. In the right situation, the sodium is carried by water in rivers, streams and as runoff and collects in basins. Then, when it comes in contact with sulfur, it precipitates out as sodium sulfate. The sulfur can come from the weathering of the mineral pyrite (iron sulfide), from volcanic sources, or from gypsum beds (gypsum is calcium sulfate).
The mineral thenardite is natural sodium sulfate. Thenardite was named after the French chemist Louis J. Thenard. It is soluble in water and has a salty taste like the mineral halite.
In the United States, two companies operate natural sodium sulfate plants in California and Texas. The brine waters of Searles Lake in California are estimated to contain about 450 million metric tons of sodium sulfate. Approximately 12% of the salt in the Great Salt Lake of Utah is sodium sulfate. This translates into 400 million tons of sodium sulfate. In addition, Nevada, Washington and Wyoming also have identified sodium sulfate resources.
Many other nations around the world also have significant natural sodium sulfate deposits. These nations include Canada, Mexico, Spain, Turkey, China, Egypt, Italy, Romania and South Africa. The United States imports sodium sulfate from Canada, Mexico, and other nations.
In addition, significant amounts of sodium sulfate are produced as a by-product from the production of other materials such as ascorbic acid, boric acid, cellulose, rayon, and silica pigments, to name a few.
A small amount is recycled by the paper and paper pulp industry. Based on the amount of sodium sulfate consumed each year worldwide, there is enough natural sodium sulfate to last hundreds of years.
Most sodium sulfate consumed annually is used to make soaps and detergents. It is an especially important ingredient in powdered soaps. Not as much is needed to make liquid soaps. It is also used to make textiles, in the production of paper and paper pulp, in glass production, and a variety of other applications.
Substitutes and Alternative Sources
Emulsified sulfur and caustic soda (sodium hydroxide) can be used in place of sodium sulfate in paper production. It is easily replaced by a number of products in soap and detergent production. Soda ash and calcium sulfate can be used in place of sodium sulfate in glass production, but the glass produced is considered "less-than-perfect."
- Common Minerals and Their Uses, Mineral Information Institute.
- More than 170 Mineral Photographs, Mineral Information Institute.
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