Potassium Mining

Potassium is the seventh abundant element on the earth with a weight percentage of 2.6. It is also one of the vital elements needed for living organisms to live.

Ores:

The ores which are rich in potassium are muscovite, orthoclase feldspar, carnallite (KMgCl3?6H2O), sylvite (KCl), polyhalite (K2Ca2 Mg [SO4]4?2H2O) and longbenite (K2Mg2[SO4]3). From the above ores, muscovite and feldspar is not used for the extraction of potassium as it is insoluble in water which make the extraction process tedious. The sylvite, carnallite and polyhalite ore are the most used ores for extracting potassium as they are soluble in water.

The potassium extracting ores are commonly called as potash. The potash mostly consists of potassium chloride, the primary product for the production of potassium metal.The vast deposits of sylvite ores are found in Saskatchewan, Canada which is the largest potash mining country with a reserve about 25% of the world potash mining production.

Mining:

The mining of potash can be done by two methods namely underground shaft mining and solution mining.The underground shaft mining handles the technique of digging underground tunnels to mine the potassium ores present inside the earth's surface. The ores which are collected in the underground tunnels are carried to the surface by manual labor or conveyor belts.Solution mining is used in the areas where the potash reserves are too deep to dig out.

In this method, deep wells are drilled in the bed rocks of the ores and water or brine solution is injected to it. The injected solution dissolves the potassium ore particles in it. Then the pregnant solution containing potassium ores are pumped out to the surface and are evaporated and crystallized.The major potash mining countries are Canada, Germany, Russia, Belarus, China, Jordan, Spain, India, Chile, and Israel

Processing and extraction:

The initial process for the extraction of potassium is making potassium chloride from the mined potash ores. The potash ore obtained from underground mining are crushed and grounded to powder. The obtained powder is then mixed with the brine solution and undergoes evaporation for the removal of impurities and crystallized. Commonly the ejected brine solution from the deep wells of the solution mining undergoes evaporation to annihilate the impurities and to crystallize the solution.

The processed potash salts contains potassium chloride (KCl) with other mineral constituents such as sodium and magnesium compounds. The main constituent potassium chloride needed for the production of potassium metal is separated from those compounds by fractional precipitation method. The fractional precipitation method utilized here separates potassium chloride from sodium and magnesium composites by their solubility differences.

Na + KCl ? NaCl + K

The separated potassium chloride will be reacted with sodium under thermal method and executes a chemical equilibrium reaction. In this reaction, potassium is separated from its chloride salt by sodium creating sodium chloride.This is the major effective industrial process in the production of the potassium metal.

2 KF + CaC2 ? 2 K + CaF2 + 2 C

In some cases Griesheimer process is employed in the production of potassium metal by reacting potassium fluoride with calcium carbide. Here, the calcium emits carbon as gas and forms calcium fluoride metal halide by creating potassium.But the above process is not widely used and not as effective as the thermal method.

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