Potash is a potassium-rich salt that is mined from underground deposits left behind when ancient giant seas evaporated millions of years ago. Potassium is essential for all plant, animal and human life. The dominant potash in the market is the compound potassium chloride (“KCl”). Approximately 95% of all potash production goes into the agriculture sector where it is used as a plant nutrient. Potash is a key ingredient in fertilisers that enhances water retention of plants, increases crop yields and plants' disease resistance.
Potassium, nitrogen and phosphorus are three of the most essential nutrients that a plant needs to grow. Potash plays an important role in helping plants to absorb potassium required to thrive. The role of potassium cannot be substituted by any other nutrient and potash has no commercial substitute as a potassium fertiliser source. Commercial fertilisers are used in 40% to 60% of the world’s food production.
The predominant drivers for fertiliser sales are the increasing demand for food, economic growth and ability to pay a premium for proteins, decreasing arable lands requiring more yield and increased bio-fuels demand. The United Nations expects world population to rise 40% to 9.2 billion by 2050. Such population growth means there will be an increasing need for crops used in food, animal feed, fibre and bio-fuels that will cause significant changes in agricultural production. In addition, fertiliser prices will remain robust as both the bio-fuel industry expands its use of grains and oilseeds and global grain stocks decline.
If the world adopts a balanced approach to nutrient/fertiliser application and uses the appropriate recommended scientific levels, the BRIC economies (Brazil, Russia, India, China) alone will require an additional 28 million tonnes of potash annually. Potash has for one reason or another been under-applied in most countries. As potash is added back into a balanced approach to crop application (in order to improve yields) the demand for potash will increase.
Potash ore comes in various forms and grades depending on the formation and constitution of the many individual elements and insoluble clay‐like materials that is deposited when formed geologically. Potash deposits are essentially evaporitic sequences which are formed by the progressive evaporation of land-locked saltwater basins. The continuing episodic (cyclic) evaporation of these salt-rich brines results in the deposition/precipitation of beds with enrichments of certain minerals and rock types. Typical enrichments include limestone/calcite (CaCO3), dolomite (MgCO3), anhydrite (CaSO4), halite (NaCl), Sylvite (KCl) and Carnallite (KMgCl3-6H2O).
Sylvite and Carnallite are considered the economic potash minerals of the element suite and are nearly always associated with halite as the predominant mineral. Potassium and magnesium salts are the last minerals to precipitate from the salt-rich brines and require almost complete evaporation to reach the necessary concentrations of potassium to create potash minerals.
The potash mineralisation forms in laterally‐extensive beds with a medium‐ to coarsely‐crystalline mineralogy. The ore minerals, Sylvite and Carnallite, may occur together or separately. They are present within the halite as scattered crystals, thin‐layered crystal concentrations or thick potassium‐rich beds. The ore colour depends upon the tainting of the most predominant mineral and it ranges from pale flesh pink to blood red in colour.
Potash is a relatively soft rock material that can be mined or extracted in two different basic methods:
- access the ore zones by shaft or decline and extract the bulk ore by standard mining equipment – similar in technique to underground coal mining.
- access the ore zones by drilling a series of wells from the surface to the mineralised zones then inject water, dissolve the ore and pump the potash rich solution out.
Both methods require separation of the potash from the salt when the raw material is on surface. Conventional mining uses flotation and heavy media separation techniques similar to standard ore processing, while solution mining uses evaporation of the water and crystallisation of the potash minerals.
Demand for potash is driven primarily by its use in fertilisers for food and biofuel production. An expanding global population, changing diets, and decreasing amounts of arable land have increased the need for fertiliser minerals, including potash.
This increase in demand has led to higher prices and interest in new potash sources. Global demand growth projections to 2021 indicate that potash demand will grow to 61.5 million tonnes in 2016 and to 73.1 million tonnes in 2021. This would require a 2.5 million tonne mine added to supply annually.
Muriate of Potash
MOP is the most common form of potash. It is particularly effective when used in the commercial cultivation of the carbohydrate crops including wheat, oats, and barley. MOP is composed of potassium and chloride in the forms of charged atoms, and therefore in the form of a salt which is soluble in water.
MOP has a total global market size of approximately 60 million tons.
Sulphate of Potash
SOP is the second major form of potash, with a chemical formula of K2SO4. It is particularly effective in the cultivation of fruits, vegetables, potatoes, tobacco and tree nuts. SOP has a total global market size of approximately 5.5 million short tons.
SOP provides the potassium needed to nourish and strengthen plants, ward off disease, improve transportability and add flavour. SOP improves crop yield and provides sustainable food supplies for the rapidly expanding global population, growing middle-class, and shrinking agricultural land.