A versatile commodity
Potash mines are a common sight in Saskatchewan, and most residents are well aware that the industry commands billions of dollars on the global market and is an important component of the province’s economy. Less obvious, however, are its origins and its uses, which range from the biological to the chemical.
The term “potash” refers to not one, but several potassium compounds and potassium-bearing materials that contain water-soluble potassium. It is so named for the pre-industrial practice of using large, iron pots to collect potassium evaporated from wood ash. Eventually, the term would be applied to both naturally-occurring potassium salts and the substances produced through the industrial extraction and refinement of those salts.
Potassium is a metal, and an extremely active one at that. When ignited, it burns with a purple hue and, when introduced in its pure form into the atmosphere, it reacts violently with any oxygen and water that it encounters. Its interaction with water is particularly dramatic, creating corrosive potassium hydroxide and leaving free hydrogen atoms to react with other molecules.
Stable potassium salts were infused into the soil of this province beginning roughly 544 million years ago, between the Cambrian and Mississippian periods. During that time, a tropical, inland sea filling the area known as the Phanerozoic basin drowned much of what is now Saskatchewan, collecting the sediment that would crystallize into potash ore once the sea finally receded and dried. In the process, this potassium became naturally intermingled with sodium chloride, also known as common table salt.
In the present, potash deposits can be found in a belt running from the midwestern border of the province to the southeastern corner. The further south one surveys, the deeper the potash has been buried, since Saskatchewan emerged from beneath its primordial sea, from 1,000 metres in the north to nearly 3,000 metres in the south.
The vast majority of the potash mined in the province is used in foreign agricultural efforts. In the international potash market, China, the United States, Brazil and India are the greatest consumers. Agriculture claims at least 90 per cent of the world’s potash production, and only five per cent of Saskatchewan potash remains in the province. Potash — whether in the form of potassium carbonate, potassium chloride, potassium sulfate, potassium magnesium sulfate, langbeinite or potassium nitrate — is the third most important ingredient in crop fertilizers, behind nitrogen and phosphorus.
Across the external surface of a plant, potassium regulates water intake and gas exchange by forming ion pumps that control the opening and closing of pore-like openings called stromata. The element is also necessary in the synthesis of proteins and other physiological processes within a plant’s cells.
Without an adequate diet of potassium, a plant will become vulnerable to drought, frost and disease due to its inability to absorb and retain water. Scorched and curled leaves, spots, and reduced growth of roots, seeds, and fruit are the symptoms of such a potash deficiency.
Although crop applications are the foundation of the potash market, potassium is just as essential to the function of animal cells, and potash can improve the health of livestock. Nerve transmission is dependent on potassium ion diffusion, so animal feed supplements can contain potassium carbonate to prevent nervous disorders such as cardiac dysfunction.
In humans, a deficiency of potassium in the body is known as hypokalemia, and it can be treated with the potash potassium chloride. Even though a diet rich in the appropriate vegetables is usually the best way of preventing and treating the disease, potassium chloride can be quickly absorbed by the body if ingested as a supplement.
Biological processes aside, potassium chloride can also be used in chemical processes such as aluminum recycling, metal electroplating, steel heat-treating and water softening, and it is an ingredient in oilwell drilling fluid and snow-melting agents.
Potassium chloride is just one of the forms of potash that have industrial and chemical applications. For instance, potassium carbonate, the same potash that appears in fertilizers and animal feeds, can be employed in the brewing of beer and the manufacture of synthetic rubber, and as an ingredient in cement, fire extinguishers, photographic chemicals and textiles. Yet another form of potash, the caustic potassium hydroxide, can be used as the precursor of other forms of potassium, such as potassium phosphate and the aforementioned potassium carbonate, and can play a role in the manufacture of soap.
These applications, although numerous and diverse, are merely a sampling of the roles that potash has played in industries throughout the world. Saskatchewan is indeed fortunate to have access to rich deposits of such an important and versatile substance, the salty bed of an ancient sea buried under the fertile soil of a modern prairie.