The term potash ( ) includes mined and manufactured salts that contain potassium in water-solute form.[ Potash , USGS 2008 Minerals Yearbook] The term potash derives from pot ash, either plant ashes or that were soaked in water in a pot, which was the primary means of manufacturing potash before the Industrial Era; the word potassium derives from the term potash.
In 2021, the worldwide production of potash exceeded 71.9 million (~45.4 million tonnes Potassium oxide equivalent), and Canada is the greatest producer of potash as fertilizer.
Terminology
The term
potash refers to compounds of potassium and to potassium-bearing materials, usually potassium carbonate. The usage of the term
potash dates from 1477, and derives from the
Middle Dutch word potaschen, denoting pot ashes.
[
]
The old method of making potassium carbonate () was either by collecting or by producing
wood ash (the occupation of the
ash burner), chemically leaching the ashes and then evaporating the resulting solution in large iron pots, which yielded a white residue denominated "pot ash";
approximately 10% by weight of common
wood ash can be recovered as potash.
The term potash later identified minerals that contained potassium salts and the artificial commercial product derived from the salts.
|
|
To the early 20th century: potassium carbonate (K2CO3); from the late-19th century: one or more compounds of potassium chloride (KCl), potassium sulfate (K2SO4), or potassium nitrate (KNO3).[ Reprinted from Agri-Briefs, of the Agronomists of the Potash & Phosphate Institute, Winter 2001–2002, No.7] the amount of potassium is reported as K2O equivalent (i.e. if in K2O form), however, to allow direct comparison between different fertilizers using different types of potash. |
| potassium hydroxide (KOH) |
| potassium carbonate (K2CO3) |
| potassium chlorate (KClO3) |
potassium chloride (KCl:NaCl = 95:5 or higher) |
| potassium nitrate (KNO3) |
| potassium sulfate (K2SO4) |
| potassium permanganate (KMnO4) |
History
Origin of potash ore
Most of the world reserves of potassium (K) were deposited as sea water in ancient
. After the water evaporated, the potassium salts crystallized into beds of potash ore. These are the locations where potash is being mined today. The deposits are a naturally occurring mixture of potassium chloride (KCl; mineral name
sylvite) and sodium chloride (NaCl; mineral name
halite), more commonly known as
table salt. Over time, as the surface of the earth changed, these deposits were covered by thousands of feet of earth.
[Robert C. Fite Origin and occurrence of commercial potash deposits , Academy of Sciences for 1951, p. 123]
Bronze Age
Potash (especially potassium carbonate) has been used in bleaching textiles, making
glass, ceramic, and making
soap, since the
Bronze Age.
Potash was principally obtained by leaching the ashes of wood burned for heating and cooking.
14th–17th century
Potash mining
Beginning in the 14th century potash was mined in
Ethiopia. One of the world's largest deposits, 140 to 150 million tons, is located in the Dallol area of the
Afar Region.
[ Ethiopia Mining. Photius.com. Retrieved on 2013-06-21.]
Wood-derived potash
Potash was one of the most important industrial chemicals. It was refined from the ashes of broadleaved trees and produced primarily in the forested areas of Europe,
Russia, and
North America. Although methods for producing artificial alkalis were invented in the late 18th century, these did not become economical until the late 19th century and so the dependence on organic sources of potash remained.
Potash became an important international trade commodity in Europe from at least the early 14th century. It is estimated that European imports of potash required 6 or more million cubic metres each year from the early 17th century.[Paul Warde, 'Trees, Trade and Textiles: Potash Imports and Ecological Dependency in British Industry, c. 1550–1770', Past & Present, 240, 1, 2018, 47–82] From the 1640s, geopolitical disruptions (i.e. Russo-Polish War (1654–1667)) meant that the centres of export moved from the Baltic to Arkhangelsk, Russia. In 1700, Russian ash was dominant though Gdańsk remained notable for the quality of its potash.
18th century
Kelp ash
On the
Orkney islands,
kelp ash provided potash and
soda ash, production starting "possibly as early as 1719" and lasting for a century. The products were "eagerly sought after by the glass and soap industries of the time."
North America
By the 18th century, higher quality American potash was increasingly exported to Britain. In the late 18th and early 19th centuries, potash production provided settlers in North America badly needed cash and credit as they cleared wooded land for crops. To make full use of their land, settlers needed to dispose of excess wood. 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
per acre (500 to 900 m
3/km
2). In 1790, the sale of ashes could generate $3.25 to $6.25 per acre ($800 to $1,500/km
2) 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.
The first US patent
The first US patent of any kind was issued in 1790 to Samuel Hopkins for an improvement "in the making of Pot ash and Pearl ash by a new Apparatus and Process".
[. en.wikisource.org] Pearl ash was a purer quality made by
calcination of potash in a reverberatory furnace or kiln.
were once used in
England to produce potash that was used in making soap for the preparation of wool for yarn production.
19th century
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.
Canada
From 1767, potash from wood ashes was exported from Canada. By 1811, 70% of the total 19.6 million lbs of potash imports to Britain came from Canada.
Exports of potash and pearl ash reached 43,958 barrels in 1865. There were 519
Ashery in operation in 1871.
20th century industrialization
The wood-ash industry declined in the late 19th century when large-scale production of
potash from mineral salts was established in
Germany. In the early 20th century, the potash industry was dominated by a cartel in which Germany had the dominant role.
WWI saw a brief resurgence of American asheries, with their product typically consisting of 66% hydroxide, 17% carbonate, 16% sulfate and other impurities.
Later in the century, the cartel ended as new potash producers emerged in the USSR and Canada.
In 1943, potash was discovered in Saskatchewan, Canada, during oil drilling. 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.
In 1964 the Canadian company Kalium Chemicals established the first potash mine using the solution process. The discovery was made during oil reserve exploration. The mine was developed near Regina, Saskatchewan. The mine reached depths greater than 1500 meters. It is now the Mosaic Corporation's Belle Plaine unit.
The USSR's potash production had largely been for domestic use and use in the Council for Mutual Economic Assistance countries.
In the beginning of the 20th century, potash deposits were found in the Dallol Depression in the Musely and Crescent localities near the Ethiopean- border. The estimated reserves in Musely and Crescent are 173 and 12 million tonnes respectively. The latter is particularly suitable for surface mining. It was explored in the 1960s but the works stopped due to flooding in 1967. Attempts to continue mining in the 1990s were halted by the Eritrean–Ethiopian War and have not resumed as of 2009.
Mining
Shaft mining and strip mining
All commercial potash deposits come originally from
evaporite deposits and are often buried deep below the earth's surface. Potash ores are typically rich in potassium chloride (KCl), sodium chloride (NaCl) and other salts and clays, and are typically obtained by conventional shaft mining with the extracted ore ground into a powder.
Most potash mines today are deep shaft mines as much as 4,400 feet (1,400 m) 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 potassium fertilizer. Other potassium salts can be separated by various procedures, resulting in potassium sulfate and potassium-magnesium sulfate.
Saskatchewan is the world’s largest producer of potash.
Dissolution mining and evaporation methods
Other methods include dissolution mining and evaporation methods from brines. In the evaporation method, hot water is injected into the potash, which is dissolved and then pumped to the surface where it is concentrated by solar induced evaporation.
Amine reagents are then added to either the mined or evaporated solutions. The amine coats the KCl but not NaCl. Air bubbles cling to the amine + KCl and float it to the surface while the NaCl and clay sink to the bottom. The surface is skimmed for the amine + KCl, which is then dried and packaged for use as a K rich fertilizer—KCl dissolves readily in water and is available quickly for
plant nutrition.
[ Potassium Fertilizer Production and Technology . International Plant Nutrition Institute.]
Recovery of potassium fertilizer salts from sea water has been studied in India.[ Recovery of Potassium Fertiliser Salts from Sea Bittern . Tifac.org.in. Retrieved on 2013-06-21.] During extraction of salt from seawater by evaporation, potassium salts get concentrated in bittern, an effluent from the salt industry.
Production
Potash deposits are distributed unevenly throughout the world.
, deposits are being mined in Canada, Russia, China, Belarus, Israel, Germany, Chile, the United States, Jordan, Spain, the United Kingdom, Uzbekistan and Brazil,
[Quick Guide to Potash. (2013, June 14). Retrieved September 29, 2015, from http://www.geoalcali.com/en/quick-guide-to-potash/ ] with the most significant deposits present under the great depths of the Prairie Evaporite Formation in
Saskatchewan, Canada.
Canada and Russia are the countries where the bulk of potash is produced; Belarus is also a major producer.
The Permian Basin deposit includes the major mines outside of Carlsbad, New Mexico, to the world's purest potash deposit in Lea County, New Mexico (near the Carlsbad deposits), which is believed to be roughly 80% pure. (Osceola County, Michigan, has deposits 90+% pure; the only mine there was converted to salt production, however.) Canada is the largest producer, followed by Russia and Belarus. The most significant reserve of Canada's potash is located in the province of Saskatchewan and is mined by The Mosaic Company, Nutrien and K+S.
In China, most potash deposits are concentrated in the deserts and salt flats of the endorheic basins of its western provinces, particularly Qinghai. Geological expeditions discovered the reserves in the 1950s[.] but commercial exploitation lagged until Deng Xiaoping's Reform and Opening Up Policy in the 1980s. The 1989 opening of the Qinghai Potash Fertilizer Factory in the remote Qarhan Playa increased China's production of potassium chloride sixfold, from less than a year at Haixi and Tanggu to just under a year.[.]
In 2013, almost 70% of potash production was controlled by Canpotex, an exporting and marketing firm, and the Belarusian Potash Company. The latter was a joint venture between Belaruskali and Uralkali, but on July 30, 2013, Uralkali announced that it had ended the venture.
Potash is Solubility and transporting it requires special transportation infrastructure.
| +List of countries by potash production
! rowspan="2" | Rank
! rowspan="2" | Country
! colspan="5" | Extraction in metric tons K2O equivalent |
|
| 1 | | 10,789,662 | 12,562,695 | 14,023,931 | 12,643,318 | 13,881,665 |
| 2 | | 6,480,000 | 7,300,000 | 7,055,000 | 7,368,000 | 8,167,300 |
| 3 | | 6,180,100 | 7,101,800 | 7,346,096 | 7,348,293 | 7,562,153 |
| 4 | | 5,783,000 | 5,534,000 | 5,452,000 | 5,902,000 | 5,530,000 |
| 5 | | 2,750,841 | 2,963,561 | 2,754,085 | 2,615,284 | 2,874,026 |
| 6 | | 2,093,100 | 2,126,700 | 2,149,300 | 2,043,500 | 2,415,600 |
| 7 | | 1,222,140 | 1,415,260 | 1,485,960 | 1,516,460 | 1,598,200 |
| 8 | | 1,303,840 | 1,238,630 | 991,180 | 683,540 | 966,680 |
| 9 | | 510,000 | 480,000 | 520,000 | 510,000 | 460,000 |
| 10 | | 672,246 | 557,468 | 635,490 | 547,100 | 455,000 |
| 11 | | 198,600 | 307,600 | 343,500 | 286,900 | 442,500 |
| 12 | | 316,429 | 306,296 | 201,181 | 269,300 | 276,600 |
| 13 | | 83,000 | 114,900 | 176,900 | 198,400 | 210,000 |
| 14 | | 482,800 | 297,400 | 291,100 | 84,000 | 99,260 |
| 15 | | 10,500 | 15,300 | 32,900 | 37,200 | 37,000 |
| 16 | | 0 | 0 | 15,200 | 11,100 | 16,000 |
| 17 | | 0 | 0 | 1,700 | 17,800 | 4,400 |
|
Occupational hazards
Excessive respiratory disease due to environmental hazards, such as
radon and
asbestos, has been a concern for potash miners throughout history. Potash miners are liable to develop
silicosis. Based on a study conducted between 1977 and 1987 of cardiovascular disease among potash workers, the overall mortality rates were low, but a noticeable difference in above-ground workers was documented.
Consumption
+Production of potash and reserves at some current mines (being <2% of global reserves)
(both in K2O equivalent)
(2021, in million tonnes) |
| Canada | 14.2 (28.57%) | 1,100 (33.33%) |
| Russia | 9.1 (17.14%) | 400 (12.12%) |
| Belarus | 7.6 (16.48%) | 750 (22.73%) |
| China | 6.0 (14.76%) | 170 (5.15%) |
| Germany | 2.8 (6.90%) | 150 (4.55%) |
| Israel | 2.4 (5.14%) | Large (?%) |
| Jordan | 1.6 (3.37%) | Large (?%) |
| Chile | 0.9 (1.85%) | 100 (3.03%) |
| United States | 0.5 (1.04%) | 220 (6.67%) |
| Spain | 0.4 (0.79%) | 68 (2.06%) |
| Brazil | 0.3 (0.58%) | 2.3 (0.01%) |
| Other countries | 0.4 (0.76%) | 300 (9.09%) |
| World total | 46.3 (100.00%) | >3,300 (100.00%) |
Fertilizers
Potassium is the third major plant and crop nutrient after
nitrogen and
phosphorus. It has been used since
Ancient history as a
soil fertilizer (about 90% of current use).
[ Fertilizer use is the main driver behind potash consumption, especially for its use in fertilizing crops that contribute to high-protein diets.]
Elemental potassium does not occur in nature because it reacts violently with water.[ Potash Price Close to all time highs – Future Outlook . ASX Release (14 November 2008). activex.com.au. Retrieved on 2013-06-21.]
Demand for food and animal feed has been on the rise since 2000. The United States 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 and Latin America greatly contributed to the increased use of potash-based fertilizer. Rising incomes in developing countries also were 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.[ Potash Around the World. southernstates.com][ "Potash global review: tunnel vision" , Industrial Minerals, May 2009]
The world's largest consumers of potash are China, the United States, Brazil, and India.[ Supply and Demand . Potassiodobrasil.com.br. Retrieved on 2013-06-21.] Brazil imports 90% of the potash it needs.
Potash imports and exports are often reported in K2O equivalent, although fertilizer never contains potassium oxide, per se, because potassium oxide is Causticity and hygroscopic.
Pricing
At the beginning of 2008, potash prices started a meteoric climb from less than US$200 a tonne to a high of US$875 in February 2009.[ 5 Year Potash Prices and Potash Price Charts – InvestmentMine. Infomine.com (2013-05-31). Retrieved on 2013-06-21.] After the surprise breakup of the world's largest potash cartel at the end of July 2013, potash prices were poised to drop some 20 percent.
Other uses
In addition to its use as a fertilizer, potassium chloride is important in many industrialized economies, where it is used in aluminium recycling, by the chloralkali industry to produce potassium hydroxide, in metal electroplating, oil-well drilling fluid, snow and ice melting, steel heat-treating, in medicine as a treatment for hypokalemia, and water softening. Potassium hydroxide is used for industrial water treatment and is the precursor of potassium carbonate, several forms of potassium phosphate, many other potassic chemicals, and soap manufacturing. Potassium carbonate is used to produce animal feed supplements, cement, fire extinguishers, food products, photographic chemicals, and textiles. It is also used in brewing beer, pharmaceutical preparations, and as a catalyst for synthetic rubber manufacturing. Also combined with silica sand to produce potassium silicate, sometimes known as waterglass, for use in paints and arc welding electrodes. These non-fertilizer uses have accounted for about 15% of annual potash consumption in the United States.[
]
Substitutes
No substitutes exist for potassium as an essential plant nutrient and as an essential nutritional requirement for animals and humans.
See also
Further reading
External links
