Potash

Kathy Feick

Potash is a group of minerals consisting of potassium salt mixed with the impure form of potassium carbonate (K₂CO₃). The word potash was derived from the Dutch word “Potasch,” which originally referred to wood ash. It cannot be produced synthetically.

Until the 20^th century, potash was one of the most important industrial chemicals. It was produced primarily in Europe, Russia and North America. Potash was made by refining the ashes of broad leaved trees and as early as 1767, potash from wood ashes was exported from Canada.

By 1871, there was a maximum of 519 asheries open in Canada. This number decreased substantially in the 19^th century when large-scale production of potash from mineral salts was established in Germany.

Fortunately, in 1943, a large deposit of potash was discovered in Saskatchewan in the process of drilling for oil. Today, Canada is once again the world’s largest potash exporter, accounting for 43% of world trade. Canada exports potash to over 40 countries.

Uses:

95% of the world’s potash consumption is fertilizers
Small amounts of potassium are used to manufacture soaps, glass, ceramics, chemical dyes, drugs, synthetic rubber, de-icing agents, water softener and explosives.

The role of potassium:

Potassium is an essential element to life on earth. It fulfils numerous vital processes in plants, animals and humans. For the average adult human, approximately 2 grams of potassium is required per day. Typical intakes are about 2.8-4.5 grams per day. There are no health risks associated with over-consumption of this element.

Localities:

Potash can be found world-wide. It is the seventh most common element in the Earth’s crust. It can also be found in rain water (only about 4parts per million), and in sea water (390 mg/l K). Today, only 12 countries produce the world’s supply of potash.

Alone, Canada has almost 10 billion tonnes of recoverable K2O deposits in Saskatchewan. The next largest reserves are Russia with up to 2.2 billion tonnes K2O, Belarus with up to 1.0 billion tonnes K2O, Germany with up to 0.9 billion tonnes, USA, England, Spain and Brazil.

Potassium mining:

All major solid potash deposits are of marine origin and were formed due to the evaporation of sea water. Potash deposits have been found dating all the way back to the Cambrian period, approximately 550 million years ago. There are two main ways to mine for potash.

Conventional underground mining. This process involves extracting solid potash from underground mines with use of explosive charges and then bringing the materials up to the surface via vertical shafts to be processed in above ground plants.
Solution mining: A relatively new technique, introduced only a few decades ago, which involves dissolving the easily soluble potash salts in the deposits with fresh water via deep boreholes and bringing the solution to the surface in large containers. The warm solution is allowed to cool off, causing the potassium chloride to crystallize and settle.