The commodity called "soda ash" is anhydrous sodium carbonate (that is, sodium carbonate without water, Na2CO3). It is made both by the processing of the minerals trona (Na3H(CO3)2.2H2O)and nahcolite (NaHCO3), and by processing sodium carbonate-rich waters (called brines). Sodium carbonate is one of the most important compounds in the chemical industry. The production of these chemicals and their compounds is known as the “alkali” 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 carbon dioxide, it precipitates out as sodium carbonate.
When companies process and produce soda ash, a number of other sodium compounds are made as co-products, including sodium bicarbonate (also known as baking soda), sodium sulfite, sodium tripolyphosphate, and chemical caustic soda.
Soda ash is one of the most widely used and important commodities in the United States. Because so much soda ash is used by so many industries, monthly soda ash production information is one of the pieces of information used to determine the condition of the United States economy.
Deposits of sodium carbonate are found in large quantities in the United States, China, Botswana, Uganda, Kenya, Mexico, Peru, India, Egypt, South Africa and Turkey. It is found both as extensive beds of sodium minerals and as sodium-rich waters (brines).
Six companies in the United States (four in Wyoming, one in California, and one in Colorado) produce over 14 million tons of soda ash annually. The largest trona deposit in the world is in the Green River Basin of Wyoming. It is estimated that this deposit alone could produce as much as 47 billion tons of soda ash. This deposit consists of thick, extensive beds of trona and thin trona beds inter-bedded with salt (halite). In California, Searles Lake and Owens Lake are soda brine lakes that are estimated to contain 815 million tons of soda ash.
By far, the majority of soda ash is used to make glass. The next largest use is to make a variety of chemicals, followed by soaps and detergents, distributors, the removal of sulfur from smokestack emissions, paper and paper pulp production, water treatment, and other assorted uses. These other uses include oil refining, making synthetic rubber, and explosives.
Worldwide, more than 60 natural sodium carbonate deposits have been identified.
Substitutes and Alternative Sources
Soda ash can be made synthetically using limestone, salt and ammonia. This is known as the Solvay process, and was the main source of soda ash until the Wyoming trona deposits were discovered. However, it is more expensive than mining natural sodium carbonate deposits. In addition, the waste products of this process are harmful to the environment and could cause serious waste management problems. The enormous natural deposits will not be exhausted for decades to come. If ever soda ash must be synthesized using the Solvay process, nearly limitless sources of limestone and salt are available.
- Common Minerals and Their Uses, Mineral Information Institute.
- More than 170 Mineral Photographs, Mineral Information Institute.
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