General process information
Potassium is one of the three basic plant nutrients along with nitrogen and phosphorus. There is no substitute for potassium compounds in agriculture; they are essential to maintain and expand food production.
Potash is extracted from buried ancient evaporates by underground or solution mining. This accounts for most of the potassium produced. Another important source is brine from landlocked water bodies, such as the Dead Sea, Salar de Atacama or Great Salt Lake.
Once the potash ore is extracted from the mine it is being transferred to the mill.
The ore is crushed into small pieces, which releases the crystals of potash and salt in the ore. Clay particles are separated from the crystals using agitation machines. The clay particles are much smaller than the potash and salt crystals and are removed using size separators.
Process reagents added to the potash, salt and brine mixture attach only to the potash crystals. These reagents enable potash to attach to fine air bubbles that are introduced into the bottom of flotation machines. The potash particles rise to the surface for collection and the salt remains on the bottom, where it is discarded.
Potash particles and brine are transferred to centrifuges, which separates potash from the brine. The potash is moved to dryers, which heat the product to about 200 degrees Celsius.
The resulting dry mixture contains various sizes that are separated by huge mesh screens into standard, granular and suspension grade product.
A portion of the finer product stream is fused under high pressure between two rolls. The resulting solid “board” is broken into pieces and sized to form additional granular potash.
In some mills, finer product is dissolved in hot brine to release small quantities of impurities. The brine is then cooled in vessels to produce a high purity white product suitable for use in soluble fertilizer and in industrial markets.
Finished product is transferred to onsite warehouses or large silos that have the capability to store several grades of potash.