The Earth's crust is made up of hundreds of different rocks. This article will discuss only one of them. What are phosphorites? What are their physical and chemical properties? In what countries are they mined, and how are they used in the modern world? We will tell you about all this further.
General information about the breed, its composition and properties
So, what are phosphorites? This is a rock of sedimentary origin, consisting mainly of phosphorus anhydrite (chemical formula - P2O5), 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 have the appearance of darkly colored stones of bizarre shapes. The most common is a dark gray color, samples of burgundy or brown are a little less common. Often, phosphorites are presented in the form of round balls with a radiant structure in a break, orlarge slabs up to 0.5-1 meters in thickness.
Earlier, people called this rock "bread ore" and did not know its real value. Therefore, they were used only as a building material for the construction of houses and fences. The generally accepted scientific name of the breed comes from the Greek word "phosphorus", which translates as "carrying light".
Phosphorite is a relatively hard rock with variable mineral composition and rather dense structure. If you look at its break 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.
Origin of phosphorites
The origin of this breed is organic, namely biolytic. Phosphorites were formed from the remains of marine organisms - shells, bones, shells, which accumulated in large quantities in the bottom sediments of shallow relict seas (up to 1000 meters). Subsequently, they decomposed and succumbed to complex chemical transformation. It is possible that this happened with the participation of live bacteria.
Let's consider this process in more detail. Single-celled organisms (plankton) are able to absorb phosphorus from sea water. Larger creatures (for example, fish or shellfish), feeding on plankton, saturate their organisms with this element. Dying, they contribute to the concentration of phosphorus in bottom sediments. And, at the same time, they are all prey for the same microorganisms. Such a continuous and long cycle of phosphorus in nature just led to the formation of phosphate rocks and minerals.
Phosphorites are often present in geological deposits of ancient seas in the form of rounded conglomerates or massive clastic pieces. Often - in black or brown clays. Such a deposit, for example, can be seen on the banks of the Moskva River, near the village of Kolomenskoye.
Main varieties of phosphate rock
Based on the texture and saturation of the rock with phosphates, several genetic types of phosphorites are distinguished:
- Granular - rocks containing a certain amount of small grains and strips of phosphates up to two millimeters in size, connected by clayey-ferruginous or carbonate "cement". The content of P2O5ranges from 7 to 16%.
- Reservoir - relatively homogeneous rocks, consisting of micrograins with a thickness of not more than 0.1 millimeters. They occur in the form of longitudinal layers (hence the name). Content P2O5: 26-28%.
- Nodular (nodules) - consist of nodules of a rounded or kidney-shaped shape over two millimeters in size. Unlike formation deposits, deposits of nodular phosphorites are poor and thin. The content of P2O5 varies widely (from 12 to 38%).
- Shell is a special kind of phosphorite with a high content of phosphate shells in the rock structure. Content P2O5: 5-12%.
So, what are phosphorites, we have already figured it 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 layers,whose thickness ranges from a few centimeters to several tens of meters. In one deposit, 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 pit. If the field is located under water, special installations are used. Together with phosphorites, sand, soil and some other rocks are usually extracted to the surface. Phosphorites often occur in the bowels of the earth next to apatites. In this case, they are mined in a complex.
The main reserves of phosphorites are concentrated in the following states (see the 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 area of the mining industry in Russia.
Yusufiya in Morocco remains the largest phosphorite deposit.
Use of phosphate rock
The breed is primarily used for the production of mineral fertilizers for agriculture - the so-called ammophos and superphosphates. These products are used in the agro-industrial complex in order to:
- increase crop yields;
- improve soil quality;
- slow down the aging process of plants;
- provide plants with essential nutrients (mineral and organic).
Another product made from this rock is phosphate rock. This is a cheap, effective and relatively harmless mineral fertilizer that is used mainly on acidic soils (tundra, podzolic and peat).
In addition, the process of processing phosphorites 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 materials processing often grow in the places where the rock is mined. Examples of such enterprises in Russia: Phosphorit JSC, Apatit JSC, Phosphorit-Portstroy JSC and others.
In conclusion…
What are phosphorites? This is a sedimentary rock of dark color and at the same time a mineral mined in a number of countries of the world. The main areas of phosphorite mining 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.
