Potash

Among potash is understood with a high content of potassium compounds in general, a mixture of different salt minerals. Be economically used by these salt minerals only potassium chloride and magnesium sulfate.

Important components of potash are:

• Halite: NaCl
• Sylvite: KCl
• Carnallite: KMgCl3 · 6 H2O
• Kieserit: MgSO4 · H2O

In contrast to the usually colorless rock salt, which consists almost entirely of halite, potash often has an orange-red to light brown color, caused by embedded iron oxides and hydroxides. Depending on the main ingredient, a distinction between kieseritischem, sylvinitischem and carnallitischem potash. Most of the world's mined deposits have a sylvinitisch or carnallitisch distinct commodity. Extensive Kieseritvorkommen there are mainly in Germany.

Formation

Potash arose before some 250 million years ago in the so-called Zechstein ( Permian young ) or tertiary ( Upper Rhine Graben, Bay of Wittelsheim, Upper Alsace and South Baden Buggingen ). Within today's potash deposits were at that time the border areas of former continents. Tectonic movements emerged in these marginal regions repeated shallow sea water pools, which were separated by barriers from the rest of the ocean, the Zechstein Sea. The dry and hot climate favored a strong and rapid evaporation, so that depending on the solubility crystallize successively the following substances:

Usually the Evaporitfolge but was already stopped at the stage of gypsum or halite deposition. The crystallized salt sequence was then protected either by registered blew dust (clay ), continued to grow through coverage by already heavily eingedunstetes seawater or was partially dissolved again.

This process was repeated, so that today we speak in Europe in Zechstein salt series of five, also called Zechsteinserien.

Over time, these layers are covered several times ( for example, sandstone). Since salt reacts plastically under pressure, it follows the least resistance to lines of weakness. This can, for example, His faults or fractures. Thus arose salt pillows, salt walls and floors. On the edge of this climb salts Mesozoic strata were broken drags, and it comes in part to bulges on the surface. This may be smaller saddles, but also such well-known places such as the " Hildesheimer forest " or the island of Helgoland.

Occurrence

The largest foreign potassium salts are found in Russia, Ukraine and Belarus, in Canada and the U.S. and the Chinese Lop Nor in the desert of Lop Nor. Also from the Dead Sea to be won by Israel and Jordan significant Kalisalzmengen. The earlier and partly still exploitable deposits in Germany are in the room Gorleben Braunschweig -Hannover in Lower Saxony, in the Altmark and the semolina area, in the Magdeburg - Halle in Saxony -Anhalt ( Zielitz ) as well as in South Baden ( since the 70s decommissioned), in Solling, southern Harz ( decommissioned) and fertilizer and in the Werra- Fulda area in Hesse and Thuringia ( Neuhof -Ellers, Werra potash district, with plants in herring, Philip Thal and Unterbreizbach ). A more recent method tried to make Carnallitite economically usable by hot Solenlaugung. A major difficulty lies in the treatment of waste in the Kalisalzgewinnung difficult and usable residual liquors containing high levels of magnesium salts and sodium chloride. These brines are partly in porous layers of the upper Muschelkalk pressed ( lithographic ), they go to the part in the receiving waters (eg Werra).

Use

Potassium salts are mainly processed into fertilizer. There are, depending on the value of material and finishing processes have different qualities. Usually, the product used in agriculture has a purity of about 93 percent KCl. This is used as a so-called 60 Kali as fertilizer; in the amount of potassium is equal to a 60 percent K2O -containing fertilizers. The high-purity potassium chloride 99er or industrial potash found in the chemical industry and medicine use.

Extraction

Potassium salts are mined in Germany in underground mining operations. Worldwide, there are attempts, however, similar to win the potash rock salt by solution mining over holes. Such a solution mining takes place in Thuringia in Bleicherode eg.

The mining extraction can be performed either by conventional drilling and blasting or machine by means of partial and full -face machines.

Preparation

Since the crude salt extracted contains only an average material content of 20 to 35 percent, a processing factory in surface facilities is necessary. As a treatment procedure, the flotation, the Heißverlösen or electrostatic separation are suitable. Depending on the treatment process, the product is then dried and finished, for example by granulation.

Effect as fertilizer

The potassium mineral is a main feeding element of the plant nutrition of plants and enhances the metabolic processes: Photosynthesis is intensified, accelerates the transformation of glucose (glucose ) in thickness and the structure of protein. Wherein the growth of plants is promoted.

The K ion is the most important ion in the metabolism of the plant to increase the osmotic pressure and turgidity. An adequate potassium fertilization results in a better adaptation of the plant to drought and frost hardiness. Indirectly the stability of the plant is increased. Potassium deficiency leads to " wilt costume ", chlorosis of older leaves and necrosis from the blade edge from ( Randnekrose ).