If you are thinking of investing in potash this article briefly looks at the history of potash mining and explains how potash is mined or extracted from the earth before being refined.
A brief history of potash mining
Potash has been produced since the 5th Century when its main uses were for glass making, soap, and bleaching. Potash mining began in Ethiopia in the 14th Century and became the world’s most important industrial chemical.
During the 19th Century, large scale potash production began in Germany and in 1943 deposits were discovered in Canada. Potash production became a cottage industry amongst settlers in north America who obtained it from wood ash by burning the trees they felled to clear land for farming.
Potash mining today
Although potassium is widely distributed, its concentration in rocks is usually low. Salt deposits sufficiently rich in potassium for commercially viable extraction are usually complex mixtures of potassium, magnesium and sodium salts. These are mined and then refined using simple processes including thermal dissolution, flotation and electrostatic purification.
How does the potash mining process work?
There are three main methods of potash mining:
1. Solid mining
In the four main potassium producing countries, underground deposits are mined using conventional solid mining methods. Most potash mines are deep shaft mines up to 1,400 metres underground. Strip mines are also used to mine horizontal layers of potash containing sedimentary rock.
2. Evaporation
In Israel and Jordan, potassium salts are extracted from the Dead Sea by evaporating the brine in shallow ponds. The resulting solids are refined. Similar techniques are being exploited in India.
3. Solution mining
Some locations use solution mining. This involves pumping water into the ore and bringing the dissolved salts to the surface for refining.
How is potash refined?
Several different methods are used for refining potash and these depend on both the source and the final application.
Typically, finely ground crude salts are added to a hot saturated solution of sodium chloride. This dissolves potassium chloride, precipitating out sodium chloride which is removed by filtration. The resulting solution is cooled and the potassium chloride that crystallises is removed and dried.
Depending on the demand for different kinds of phosphate, one form may be converted into another. For example, “Muriate of Potash” (MOP) is often converted into the more valuable “Sulphate of Potash” (SOP). This process is described here.
What is potash and what is it used for?
If you would like to learn more about potash, the different types of potash and what it is used for, then please click here.
