Potash is any of various mined and manufactured salts that contain potassium in water-soluble
form. The name derives from "pot ash", which refers to plant ashes soaked in water in a
pot, the primary means of manufacturing the product before the industrial era. The word
"potassium" is derived from potash. Today, potash is produced worldwide at amounts
exceeding 30 million tonnes per year, mostly for use in fertilizers. Various types of fertilizer-potash
thus constitute the single largest global industrial use of the element potassium. Potassium
was first derived by electrolysis of caustic potash, in 1808.
Terminology Potash refers to potassium compounds and potassium-bearing
materials, the most common being potassium chloride. The term "potash" comes from the
Old Dutch word potaschen. The old method of making potassium carbonate (K
2CO 3) was by leaching of wood ashes and then
evaporating the resulting solution in large iron pots, leaving a white residue called
"pot ash". Approximately 10% by weight of common wood ash can be recovered as pot ash.
Later, "potash" became the term widely applied to naturally occurring potassium salts and
the commercial product derived from them. The following table lists a number of potassium
compounds which use the word potash in their traditional names:
Production All commercial potash deposits come originally
from marine deposits and are often buried deep in the earth. Potash ores are typically
rich in potassium chloride and sodium chloride and are obtained by conventional shaft mining
with the extracted ore ground into a powder. For deep potash deposits 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.
History of production
Potash has been used since the dawn of history in bleaching textiles, making glass, and,
from about AD 500, in making soap. Potash was principally obtained by leaching the ashes
of land and sea plants. 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 Tigray's Dallol
area. 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 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". "Pearl ash" was a purer quality made by the ignition of cream of tartar. Potash
pits were once used in England to produce potash that was used in making soap for the
preparation of wool for yarn production. As early as 1767, potash from wood ashes was
exported from Canada, and exports of potash and pearl ash 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 but
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.
In the late 18th and early 19th centuries, potash production provided settlers in North
America a way to obtain 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 bushels per acre. In 1790, ashes could be sold for $3.25 to $6.25 per acre
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.
Most of the world reserves of potassium were deposited as sea water in 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 and sodium chloride, better known as common table salt. Over time,
as the surface of the earth changed, these deposits were covered by thousands of feet
of earth. Most potash mines today are deep shaft mines
as much as 4,400 feet 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 in Lea County, New Mexico, which is believed to be roughly
80% pure. 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 controlled by
the Potash Corporation of Saskatchewan. 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 as of 2009. Recently, recovery of potassium fertilizer
salts from sea water has been studied in India. During extraction of salt from seawater by
evaporation, potassium salts get concentrated in bittern, an effluent from the salt industry.
In 2013, almost 70% of potash production was controlled by two cartels, Canpotex 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.
Consumption Fertilizers
Potassium is the third major plant and crop nutrient after nitrogen and phosphorus. It
has been used since antiquity as a soil fertilizer. Elemental potassium does not occur in nature
because it reacts violently with water. As part of various compounds, potassium makes
up about 2.6% of the weight of the Earth's crust and is the seventh most abundant element,
similar in abundance to sodium at approximately 1.8% of the crust. 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.
Demand for food and animal feed has been on the rise since 2000. The United States Department
of Agriculture’s Economic Research Service 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 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. The world's largest consumers of potash are
China, the United States, Brazil, and India. 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 caustic and hygroscopic.
Pricing At the beginning of 2008, Potash prices started
a meteoric climb from less than $200 a tonne to a high of $875 in Feb 2009. These subsequently
dropped dramatically to an April 2010 low of $310 level, before recovering in 2011–12,
and relapsing again in 2013. For reference, prices in November 2011 were about $470 per
tonne, but as of May 2013 were stable at $393. After the surprise breakup of the world's
largest potash cartel at the end of July 2013, potash prices are poised to drop some 20 percent.
Other uses In addition to its use as a fertilizer, potassium
chloride is important in 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. These non-fertilizer uses have accounted for about
15% of annual potash consumption in the United States.
Potash along with hartshorn was also used as a baking aid similar to baking soda in
old German baked goods such as lebkuchen, or gingerbread.
References This article incorporates public domain
material from the United States Geological Survey document: "Potash".
Further reading Seaver, Frederick J. "Historical Sketches
of Franklin County And Its Several Towns", J.B Lyons Company, Albany, NY, Section "Making
Potash" pp. 27–29 External links
They Burned The Woods and Sold the Ashes Henry M. Paynter, The First Patent, Invention
& Technology, Fall 1990 The First U.S. Patent, issued for a method
of potash production World Agriculture and Fertilizer Markets Map
Russia reaps rich harvest with potash