The earth's crust consists of hundreds of different rocks. This article will focus only on one of them. What are phosphorites? What physical and chemical properties do they differ? In which countries are they mined, and how are they used in the modern world? We will tell you about all this later.
General information about the breed, its composition and properties
So what are phosphorites? This is a rock of sedimentary origin, consisting mainly of phosphoric anhydrite (chemical formula - P 2 O 5 ), calcium oxides and some other minerals - quartz, dolomite, chalcedony, glauconite and others. The composition of phosphorite may also include iron oxides, aluminosilicates, organic substances.
The appearance of this rock is extremely diverse. Most often, phosphorites look like dark-colored stones of bizarre shapes. The most common is dark gray color, a little less common are bard or brown samples. Often phosphorites are presented in the form of round balls with a radiant structure in a fracture, or large plates up to 0.5-1 meters in thickness.
Previously, people called this breed “bread ore” and did not know its real value. Therefore, they used it only as building material for the construction of houses and fences. The universally recognized scientific name of the breed comes from the Greek word "phosphorus", which translates as "carrying light."
Phosphorite is a relatively hard rock with an unstable mineral composition and a fairly dense structure. If we consider its kink through a microscope or a strong magnifying glass, you can see individual grains of sand, shells and fragments of the skeletons of small marine organisms.
The origin of phosphorites
The origin of this breed is organic, namely biolithic. Phosphorites were formed from the remains of marine organisms - shells, bones, shells, which in large quantities accumulated in the bottom sediments of shallow relict seas (up to 1000 meters). Subsequently, they decomposed and succumbed to complex chemical transformations. It is possible that this happened with the participation of live bacteria.
Consider this process in more detail. Unicellular organisms (plankton) are able to absorb phosphorus from seawater. Larger creatures (for example, fish or mollusks), feeding on plankton, saturate their organisms with this element. When they die, they contribute to the concentration of phosphorus in the bottom sediments. And, at the same time, they are prey all for the same microorganisms. Such a continuous and prolonged circulation of phosphorus in nature just led to the formation of phosphate rocks and minerals.
Phosphorites are often present in geological deposits of the ancient seas in the form of rounded conglomerates or massive clastic pieces. Often - in black or brown clay. Such a field, for example, can be seen on the banks of the Moskva River, near the village of Kolomenskoye.
The main types of phosphorites
Based on the texture features and the saturation of the rock with phosphates, several genetic types of phosphorites are distinguished:
- Granular - rocks containing a certain amount of small grains and phosphate strips up to two millimeters in size, connected by clay-ferruginous or carbonate “cement”. The content of P 2 O 5 ranges from 7 to 16%.
- Formation - relatively homogeneous rocks, consisting of micrograins with a capacity of not more than 0.1 millimeters. They occur in the form of longitudinal layers (hence the name). The content of P 2 O 5 : 26-28%.
- Zhelvakovye (nodule) - consist of nodules of a round or kidney-shaped in size over two millimeters. Unlike strata, deposits of jelly phosphorites are poor and low-power. The content of P 2 O 5 varies widely (from 12 to 38%).
- Shells are a special kind of phosphorite with a high content of phosphate shells in the rock structure. The content of P 2 O 5 : 5-12%.
So, what are phosphorites, we have already figured out. Now let's find out where they are mined and how they are used.
Phosphorite mining
Phosphorites occur in the ground most often in formations, the thickness of which varies from a few centimeters to several tens of meters. In one field, there can be from two to fifteen tons of rock per square kilometer of production area.
Phosphorite is mined, as a rule, in an open way. If the field is located under water, use special facilities. Together with phosphorites, sand, soil and some other rocks are usually extracted to the surface. Often phosphorites occur in the bowels of the earth near apatites. In this case, they are mined comprehensively.
The main reserves of phosphorites are concentrated in the following states (see map below):
- Morocco.
- Russia.
- USA.
- Tunisia.
- Ukraine.
- Chile.
- Peru.
- Nauru.
- Jordan.
- China.
- Argentina.
On the territory of the Russian Federation, the main production centers are located in Yakutia, Murmansk, Voronezh, Smolensk, Kursk and Kaliningrad regions. Smaller enterprises can also be found in Tatarstan. To date, a number of modernizations are being carried out in this field of mining in Russia.
The largest phosphorite deposit remains Yusufiya in Morocco.
The use of phosphorites
The breed is primarily used for the production of mineral fertilizers for agriculture - the so-called ammophos and superphosphate. These products are used in the agricultural sector in order to:
- increase crop yields;
- improve soil quality;
- slow down the aging process of plants;
- provide plants with necessary nutrients (mineral and organic).
Another product made from this rock is phosphorite flour. This is a cheap, effective and relatively harmless mineral fertilizer that is used mainly on acidic soils (tundra, podzolic and peaty).
In addition, the phosphorite processing process is accompanied by the release of a large amount of sulfuric and phosphoric acid. Therefore, quite large chemical plants with a full cycle of raw material processing often grow in the places of rock production. Examples of such enterprises in Russia: OJSC Fosforit, OJSC Apatit, OJSC Fosforit-Portstroy and others.
Finally…
What are phosphorites? This is a sedimentary rock of a dark color and at the same time a mineral extracted in a number of countries of the world. The main phosphorite mining areas are concentrated in countries such as Russia, the USA, Morocco, China and Tunisia. The main "consumers" of this rock are agriculture and the chemical industry.