Potash
01-13-2011
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For other uses, see Potash (disambiguation).
PotashPotash is the common name for potassium carbonate and various mined and manufactured salts that contain the element potassium in water-soluble form. In some rare cases, potash can be formed with traces of organic materials such as plant remains.[1]
Contents [show]
1 Terminology
2 History
3 Production and consumption
3.1 Potash as baking aid
4 References
5 External links
[edit] Terminology
Potash refers to potassium compounds and potassium-bearing materials, the most common being potassium chloride (KCl). The term "potash" comes from the old-Dutch word potaschen. The old method of making potassium carbonate (K2CO3) was by leaching wood ashes and evaporating the solution in large iron pots, leaving a white residue called "pot ash".[2][3] Later, "potash" became the term widely applied to naturally occurring potassium salts and the commercial product derived from them.[4]
The following table lists a number of potassium compounds which use the word potash in their traditional names:
Common name Chemical name Formula
Potash fertilizer[citation needed] potassium oxide K2O
Caustic potash or potash lye potassium hydroxide KOH
Carbonate of potash, salts of tartar, or pearlash potassium carbonate K2CO3
Chlorate of potash potassium chlorate KClO3
Muriate of potash potassium chloride KCl
Nitrate of potash or saltpeter potassium nitrate KNO3
Permanganate of potash potassium permanganate KMnO4
[edit] History
Potash (potassium carbonate) has been used from the dawn of history in bleaching textiles, making glass, and, from about A.D. 500, in making soap. Potash was principally obtained by leaching of the ashes of land and sea plants. Beginning in the 14th century potash was mined in Ethiopia. One of the world's largest deposits, a deposit of 140 to 150 million tons, is located in the Tigray's Dallol area.[5] Potash was one of the most important industrial chemicals in Canada. It was refined from the ashes of broadleaved trees and produced primarily in the forested areas of Europe, Russia, and North America. The first U.S. patent was issued in 1790 to Samuel Hopkins for an improvement "in the making Pot ash and Pearl ash by a new Apparatus and Process."[6]
As early as 1767, potash from wood ashes was exported from Canada, and exports of potash and pearl ash (potash and lime) reached 43,958 barrels in 1865. There were 519 asheries in operation in 1871. The industry declined in the late 19th century when large-scale production of potash from mineral salts was established in Germany. In 1943, potash was discovered in Saskatchewan, Canada, in the process of drilling for oil. Active exploration began in 1951. In 1958, the Potash Company of America became the first potash producer in Canada with the commissioning of an underground potash mine at Patience Lake; however, due to water seepage in its shaft, production stopped late in 1959 and, following extensive grouting and repairs, resumed in 1965. The underground mine was flooded in 1987 and was reactivated for commercial production as a solution mine in 1989.[3]
Potash production provided late-18th and early-19th century settlers in North America a way to obtain badly needed cash and credit as they cleared their wooded land for crops. To make full use of their land, excess wood, including stumps, needed to be disposed. The easiest way to accomplish this was to burn any wood not needed for fuel or construction. Ashes from hardwood trees could then be used to make lye, which could either be used to make soap or boiled down to produce valuable potash. Hardwood could generate ashes at the rate of 60 to 100 bushels per acre (500 to 900 m3/km2). In 1790, ashes could be sold for $3.25 to $6.25 per acre ($800 to $1500/km2) in rural New York State – nearly the same rate as hiring a laborer to clear the same area. Potash making became a major industry in British North America. Great Britain was always the most important market. The American potash industry followed the woodsman's ax across the country. After about 1820, New York replaced New England as the most important source; by 1840 the center was in Ohio. Potash production was always a by-product industry, following from the need to clear land for agriculture.[7]
Most of the world reserves of potassium (K) were deposited as sea water from ancient inland oceans evaporated, and the potassium salts crystallized into beds of potash ore. These are the locations where potash is currently being mined today. The deposits are a naturally-occurring mixture of potassium chloride (KCl) and sodium chloride (NaCl), better known as common table salt. Over time, as the surface of the earth changed, these deposits were covered by thousands of feet of soil.[7]
Most potash mines today are deep shaft mines as much as 3,300 feet (1,000 meters) underground. Others are mined as strip mines, having been laid down in horizontal layers as sedimentary rock. In above-ground processing plants, the KCl is separated from the mixture to produce a high analysis natural potassium fertilizer. Other naturally occurring potassium salts can be separated by various procedures, resulting in potassium sulfate and potassium-magnesium sulfate.
Today some of the world's largest known potash deposits are spread all over the world from Saskatchewan Canada, to Brazil, Belarus, Germany, and more notably the Permian Basin. The Permian basin deposit includes the major mines outside of Carlsbad New Mexico, to the world's purest potash deposit is in Lea County New Mexico (not far from the Carlsbad deposits) which is believed to be roughly 80% pure.[8]
[edit] Production and consumption
Potassium is the seventh most abundant element in the Earth's crust, and is the third major plant and crop nutrient after nitrogen and phosphate. About 93% of world potash consumption is used in fertilizers,[1] with small amounts used in manufacturing soaps, glass, ceramics, chemical dyes, drugs, synthetic rubber, de-icing agents, water softeners and explosives. Other main potash fertilizer products include potassium sulfate (K2SO4) and potassium nitrate (KNO3).
Potash has been used since antiquity in the manufacture of glass, soap, and soil fertilizer. Potash is important for agriculture because it improves water retention, yield, nutrient value, taste, colour, texture and disease resistance of food crops. It has wide application to fruit and vegetables, rice, wheat and other grains, sugar, corn, soybeans, palm oil and cotton, all of which benefit from the nutrient’s quality enhancing properties.[9]
Demand for food and animal feed has been on the rise since 2000. The U.S. Department of Agriculture’s Economic Research Service (ERS) attributes the trend to average annual population increases of 75 million people around the world. Geographically, economic growth in Asia, India, and Latin America greatly contributed to the increased use of potash-based fertilizer. Rising incomes in developing countries also was a factor in the growing potash and fertilizer use. With more money in the household budget, consumers added more meat and dairy products to their diets. This shift in eating patterns required more acres to be planted, more fertilizer to be applied and more animals to be fed – all requiring more potash.
After years of trending upward, fertilizer use slowed in 2008. The worldwide economic downturn is the primary reason for the declining fertilizer use, dropping prices and mounting inventories.[10][11]
While about 150 countries use potash for their crops, it is only produced in about a dozen of them. World production totaled 36 million metric tons in 2008, according to the U.S. Geological Survey. Canada is the world’s leading producer, followed by Russia and Belarus; the United States ranks seventh. The most significant reserve of Canada's potash is located in the province of Saskatchewan and controlled by the Potash Corporation of Saskatchewan.[1]
Potash imports and exports are traditionally reported in "K2O equivalent", although fertilizer never contains potassium oxide, per se, because potassium oxide is caustic and so highly reactive that it must be stored under kerosene, as with metallic potassium.[12]
In the beginning of the 20th century, potash deposits were found in the Dallol Depression in Musely and Crescent localities near the Ethiopean-Eritrean border. The estimated reserves are 173 and 12 million tonnes for the Musely and Crescent, respectively. The latter is particularly suitable for surface mining; it was explored in the 1960s but the works stopped due to the flood in 1967. Attempts to continue mining in the 1990s were halted by the Eritrean–Ethiopian War and have not resumed by 2009.[13]
Potash prices have soared in recent years. What was once a commodity worth about $200 a tonne is expected in 2009 to reach $1,500 by 2020; Vancouver prices are US$872.50 per tonne in 2009, which is a record high.[14]