POTASSIUM:

Potassium is the seventh most abundant element on Earth, constituting approximately 2.6% by weight. It is also one of the vital elements necessary for the survival of living organisms.Potassium is the chemical element with the symbol K, atomic number 19, and atomic mass 39.0983. It was first isolated from potash. Elemental potassium is a soft, silvery-white metallic alkali metal that oxidizes quickly in air and is highly reactive with water.Potassium is the second least dense metal, with only lithium being less dense. It is a soft, low-melting solid that can be easily cut with a knife. Freshly cut potassium appears silvery, but it quickly dulls to grey in air.

ORES:

The ores rich in potassium include muscovite, orthoclase feldspar, carnallite (KMgCl₃[H₂O]₆), sylvite (KCl), polyhalite (K₂Ca₂Mg[SO₄]₄.2H₂O), and longbenite (K₂Mg₂[SO₄]₃). Muscovite and feldspar are not typically utilized for potassium extraction due to their insolubility in water, which complicates the extraction process. Conversely, sylvite, carnallite, and polyhalite ores are favored for potassium extraction because they readily dissolve in water, facilitating the extraction process.

The potassium-extracting ores are commonly called potash. 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 reserves accounting for about 25% of the world's potash mining production.

MINING:

The mining of potash can be done by two methods, namely underground shaft mining and solution mining. Underground shaft mining involves digging underground tunnels to extract the potassium ores from the Earth's surface. The ores collected in the underground tunnels are transported to the surface either by manual labor or conveyor belts. Solution mining is utilized in areas where the potash reserves are too deep to be excavated.

In this method, deep wells are drilled into the bedrocks of the ores, and water or brine solution is injected into them. The injected solution dissolves the potassium ore particles within it. Then, the pregnant solution containing potassium ores is pumped out to the surface and 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 extracting potassium involves producing potassium chloride from mined potash ores. The potash ore obtained from underground mining is crushed and ground into powder. The resulting powder is then mixed with a brine solution and undergoes evaporation to remove impurities and crystallize.Typically, the brine solution ejected from the deep wells of solution mining undergoes evaporation to eliminate impurities and crystallize the solution.

The processed potash salts contain potassium chloride (KCl) along with other mineral constituents such as sodium and magnesium compounds. Potassium chloride, the main constituent needed for producing potassium metal, is separated from these compounds using the fractional precipitation method. This method exploits the solubility differences between potassium chloride, sodium, and magnesium composites.

Na + KCl ----- > NaCl + K

The separated potassium chloride is then reacted with sodium using a thermal method, which initiates a chemical equilibrium reaction. In this reaction, potassium separates from its chloride salt, resulting in sodium chloride. This is the primary industrial process for producing potassium metal.

2KF + CaC₂ ----- > 2K + CaF₂+ 2C

In some cases, the Griesheimer process is employed, which involves reacting potassium fluoride with calcium carbide. In this process, calcium emits carbon as gas and forms calcium fluoride metal halide, producing potassium. However, this method is not widely used and is not as effective as the thermal method.

APPLICATIONS:

Potassium ions are a necessary component of plant nutrition and are found in most soil types. Their primary use in agriculture, horticulture, and hydroponic culture is as a fertilizer in the form of chloride (KCl), sulfate (K₂SO₄), or nitrate (KNO₃). In animal cells, potassium ions are crucial for maintaining cell viability.

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