Potash is the common name given to potassium carbonate and various mined and manufactured salts that contain the element potassium in water-soluble form.
The word "potash" is derived from the Dutch word "Potasch", and originally referred to wood ash. Potassium carbonate, a basic chemical of pre-modern times, was extracted from it. Today potash refers to potassium compounds and potassium-bearing materials, the most common being potassium chloride (KCl). The term "potash" comes from the pioneer practice of extracting potassium fertilizer (K2CO3) by leaching wood ashes and evaporating the solution in large iron pots.
Potash, or carbonate of potash, is in fact a mixture of potassium salt with impure form of potassium carbonate (K2CO3). In other words, it is the common term used for the fertilizer forms of the element potassium (K).
Notable characteristics
Potassium occurs abundantly in nature, being the 7th most common element in the earth's crust. Some clay minerals which are associated with heavy soils are rich sources of potassium.
Potash bearing rock deposits occur in many regions of the world. They are derived from the minerals in ancient seas that dried up millions of years ago. Fertilizer potash is mostly derived from these potash rocks. It requires only separation from the salt and other minerals.
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.
The name derives from the old method of making potassium carbonate by leaching wood ashes and evaporating the solutions collected in large iron pots, leaving a white residue called "pot ash". Later, "potash" became the term widely applied to naturally occurring potassium salts and the commercial product derived from them.
To further confuse the terminology, potash imports/exports etc. are 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.
Type of Mining
Solution Mining: The use of water or hot water to dissolve a desired mineral from a geological ore zone into solution through directional or vertical boreholes or abandoned underground mine workings.
Solution mining can be used for many water soluble minerals, including:
Salt (Halite, NaCl)
Potash (Sylvite, KCl)
Soda Ash (Trona, Na2CO3.NaHCO3.H2O)
Baking Soda (Nahcolite, NaHCO3)
Potash solution mining in Saskatchewan has been performed for almost 50 years. Benefits of solution mining in comparison to conventional mining include lower CAPEX requirements, operation scalability, quicker timeline to production, lower technical risk and environmental impact. The largest solution mine in the world is operated by Mosaic Co., located directly adjacent to Potash One's Legacy Project in the Saskatchewan Potash Basin.
Mining Process
Potash solution mining in Saskatchewan is based upon a technique developed by Byron Edmonds, Alice and James Dahms, and Edward Helvenston for the Pittsburg Plate Glass Company (PPG) in the early 1960's (United States Patent Number 3,096,969). The process is initiated by drilling two wells (very similar to oil and gas wells) spaced between 60 and 80m apart through the potash resource. Upon completion of the drilling the following steps are usually followed to develop a solution mining cavern:
1. Sump Development. Ambient fresh water is injected to dissolve a sump area within the NaCl salt at the base of the solution mining cavern. The sump allows insoluble materials settle within the cavern to avoid affecting the solution mining process.
2. Cavern Connection and Roof Development. Upon completion of sump development, the fresh ambient water injection is continued to solution mine the two individual caverns within the NaCl salt at the base of the solution mining cavern. A special mining technique is used to cause the individual caverns to connect or merge. Upon establishing connection solution mining is continued within the NaCl salt at the base of the solution mining cavern to create additional roof area for the subsequent potash solution mining.
3. Primary Mining. Once the cavern roof is developed, primary mining is initiated by creating a 1.5 -- 3.0 meter casing cut or perforation into the potash mineralized zone. Heated fresh water is injected to dissolve both KCl (Sylvite) and NaCl (Halite). As the KCl and NaCl are dissolved into solution creating a void at the top of the cavern, the oil blanket migrates upward into the cut area and flows outward laterally controlling the vertical growth of the cut as additional salt is dissolved.
4. Secondary Batch Mining. As the potash mining progresses to the top of the Patience Lake potash zone, secondary mining can be initiated. Heated, saturated NaCl brine is injected instead of fresh water. Only the KCl is dissolved into solution and small amount of NaCl will precipitate from solution. The cavern production rate will decrease due to the slower dissolution rate of KCl into NaCl brine. Secondary mining and cooling pond potash recovery require less energy than primary mining.
Using the Edmonds et al method, each Cavern requires two wells. Each well is about 1600m deep and is drilled similar to an oil or gas well. In this representation, 18 wells (9 Caverns) are shown being directionally drilled from a single surface location. This is called pad drilling or a cavern cluster.
History
Since the 14th century, potash was widely produced by Ethiopia. It was their number one export up until the 20th century; however after the Ethiopian War against Kenya it became irrelevant. 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."
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.
During the Civil Rights era in the United States, Caustic Potash was often used as a weapon by African Americans. It was typically used on other African Americans accused of consorting with the whites, or being an "Uncle Tom"... The bleaching action of the lye would burn the skin and remove pigment, leaving the victim white after the burns healed. Availability of Caustic Potash to the general public was heavily curtailed in the 1970s, as a result of increasing instances of its use in this manner.
Producers and Consumers
Potash production is limited to only 12 countries around the world. The vast majority of global production comes from 3 producing nations: Canada, Russia and Belarus.Canada is the world's largest producer with the province of Saskatchewan hosting the country's epicenter of global potash production. Encompassing three of the world's leading producers---Mosaic Co., Potash Corp., and Agrium, Saskatchewan offers the resources, infrastructure, government policies and labor force needed to flourish in the industry.
Canadian distribution is controlled by Canpotex, an export organization wholly owned by Canada's three major producers. Likewise, Belrusian and Russian distribution is controlled by the Belarusion Potash Company (BPC). Collectively, Canpotex and BPC control over 70% of global potash exports.
Saskatchewan is favored for its potash reserves which are typically flat and consistent over many kilometers. Production costs typically depend on the grade of the deposit, ore depth, consistency, thickness, continuity and the amount of insoluble material contained in the ore body. Mining costs increase as the potash beds become twisted or folded.
Sources Sited:
http://www.potash1.ca/
http://en.wikipedia.org/wiki/Potash
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