Coal is a sedimentary rock formed by the decomposition of plant remains (tree ferns, horsetails and mosses, as well as the first gymnosperms). The main reserves of coal currently mined were formed during the Paleozoic period, about 300-350 million years ago. Coal has been mined for several centuries and is one of the most important minerals. Used as solid fuel.
Coal consists of a mixture of high molecular weight aromatic compounds (mainly carbon), as well as water and volatile substances dream a large number impurities. Depending on the composition of coal, the amount of heat released during its combustion changes, as well as the amount of ash produced. The value of coal and its deposits depends on this ratio.
For the formation of a mineral, the following condition also had to be met: rotting plant material should have accumulated faster than its decomposition occurred. That's why coal formed mainly on ancient peat, where carbon compounds accumulated, and there was practically no access to oxygen. The starting material for the formation of coal is, in fact, peat itself, which was also used as fuel for some time. Coal was formed when peat layers were under other sediments. At the same time, the peat was compressed and lost water, resulting in the formation of coal.
Coal occurs when peat layers occur at a significant depth, usually more than 3 km. At greater depths, anthracite is formed - the highest grade of coal. However, this does not mean that all coal deposits are located at great depths. Over time, under the influence of tectonic processes various directions some layers experienced uplift, resulting in them being closer to the surface.
The method of coal mining also depends on the depth at which coal-bearing minerals are located. If coal lies at a depth of up to 100 meters, then mining is usually carried out open method. This is the name for removing the top of a deposit, in which the mineral appears on the surface. For mining from great depths, the shaft method is used, in which access is achieved through the creation of special underground passages - shafts. The deepest coal mines in Russia are located at a distance of about 1200 meters from the surface.
The largest coal deposits in Russia
Elga field (Sakha)
This coal deposit, located in the southeast of the Republic of Sakha (Yakutia) 415 km east of the city of Neryungri, is the most promising for open-pit mining. The field area is 246 km2. The deposit is a gentle asymmetrical fold.
The deposits of the Upper Jurassic and Lower Cretaceous are coal-bearing. The main coal seams are located in the deposits of the Neryungri (6 seams with a thickness of 0.7-17 m) and Undyktan (18 seams with a thickness of also 0.7-17 m) formations.
The coals here are mostly semi-shiny with a very high content of the most valuable component - vitrinite (78-98%), medium- and high-ash, low-sulfur, low-phosphorus, well-sintered, with a high calorific value. Elga coal can be enriched using special technology, which will produce a product of higher quality that meets international standards. Thick, flat coal seams are overlain by thin deposits, which is very important for open-pit mining.
Elegest deposit (Tuva)
Located in the Republic of Tuva. This field has reserves of about 20 billion tons. Most reserves (about 80%) are located in one layer 6.4 m thick. The development of this deposit is currently ongoing, so coal production here should reach its maximum capacity around 2012.
Large deposits coal (the area of which is thousands of km2) are called coal basins. Typically, such deposits are located in some large tectonic structure (for example, a trough). However, not all fields located close to each other are usually combined into basins, and sometimes they are considered as separate fields. This usually happens according to historically established ideas (deposits were discovered in different periods).
Minusinsk coal basin is located in the Republic of Khakassia. Coal mining here began in 1904. The largest deposits include Chernogorskoye and Izykhskoye. According to geologists, coal reserves in this area amount to 2.7 billion tons. The pool is dominated by long-flame coals with a high calorific value. The coals are classified as medium ash. The maximum ash content is typical for coals of the Izykh deposit, the minimum – for coals of the Beiskoye deposit. Coal mining in the basin is carried out in different ways: there are both open-pit mines and mines.
Kuznetsk coal basin (Kuzbass)- one of the largest coal deposits peace. Kuzbass is located in the south in a shallow basin between the mountain ranges of Mountain Shoria and. This is the territory of the Kemerovo region. The abbreviation “Kuzbass” is the second name of the region. The first deposit in the Kemerovo region was discovered back in 1721, and in 1842 the geologist Chikhachev introduced the term “Kuznetsk coal basin.”
Mining here is also carried out in different ways. There are 58 mines and more than 30 open-pit mines on the territory of the basin. The quality of "" coals is varied and is among the best coals.
The coal-bearing strata of the Kuznetsk coal basin consists of approximately 260 coal seams of varying thickness, unevenly distributed across the section. The predominant thickness of coal seams is from 1.3 to 4.0 m, but there are also thicker seams of 9-15 and even 20 m, and in some places up to 30 m.
The maximum depth of coal mines does not exceed 500 m (average depth is about 200 m). The average thickness of the developed coal seams is 2.1 m, but up to 25% of coal mine production occurs in seams over 6.5 m.
Today, coal is one of the most necessary minerals.
This resource is formed naturally, has huge reserves and a lot of useful properties.
What is coal and what does it look like?
Construction of a mine is a very expensive investment, but over time all costs are fully recouped. When coal is mined, other resources also come to the surface.
There is a possibility of mining precious metals and rare earthly elements, which can later be sold and receive additional profit.
Oil is practically the most precious resource and the main source of fuel today. However, not a single company or country that mines coal will neglect its extraction in the name of oil, because solid fuel also has great value and high value.
Formation of coal
Coal in nature is formed by changing surface topography. Tree branches, plants, leaves and other natural remains that have not had time to rot are saturated with moisture from the swamps, which is why they are converted into peat.
Then it hits land sea water when it goes away, it also leaves behind a layer of deposits. After the river makes its own adjustments, the ground becomes swamped, again forms or covers the soil. Therefore, the composition of coal is highly dependent on age.
Hard coal is intermediate in age between brown, the youngest, and anthracite, the oldest.
Types of coal, their composition and properties
There are several types of coal:
- long flame;
- gas;
- fat;
- coke;
- low-caking;
- skinny.
Also common are species consisting of several, so-called mixed, having the properties of two groups.
Coal is distinguished by its black color, hard, layered, easily destructible structure, and has shiny inclusions. The combustible properties are quite high, since the material is used as fuel.
Let's consider physical characteristics:
- Density (or specific gravity) varies greatly (the maximum can reach 1500 kg/m³).
- The specific heat capacity is 1300 J/kg*K.
- Combustion temperature - 2100°C (1000°C during processing).
Coal deposits in Russia
On Russian territory contains about a third of the world's reserves.
Coal and oil shale deposits in Russia (click to enlarge)
The largest coal deposit in Russia is Elginskoye. It is located in the Yakutia region.
Reserves, according to approximate calculations, amount to more than 2 billion tons.
The terrain close to the Kuznetsk coal basin (Kuzbass) was severely damaged due to large-scale resource extraction operations.
The largest coal deposits in the world
Map of coal deposits in the world (click to enlarge)
In the United States, the most famous coal basin is the Illinois. The total reserves of deposits in this field amount to 365 billion tons.
Coal mining
In our time, hard coal is mined in three fundamental ways. Such as:
- career method;
- mining through adits;
- mining method.
The quarry mining method is used when coal seams lie on the surface, approximately one hundred meters deep or higher.
Quarries involve simply digging up the ground or sand pit from which mining is carried out; usually in such cases the coal seam is quite thick, which makes its extraction easier.
Adits mean wells with a large angle of inclination. All mined minerals are transported upward along it, without the need to use serious equipment or dig out a basin.
Typically, deposits in such places are thin and not buried particularly deep. Therefore, the method of mining through adits allows for rapid production without special costs.
Mining through mines is the most common method of extracting minerals, at the same time the most productive, but at the same time dangerous. The mines are drilled to great depths, reaching several hundred meters. However, this requires a permit confirming the justification for such large-scale work and evidence of the presence of deposits.
Sometimes the mines can reach a kilometer or more in depth, and stretch for several kilometers in length, forming interconnected webs of corridors underground. In the 20th century, settlements even formed around the mines and small towns, in which miners lived with their families.
It is precisely because of the mining conditions that work in the mines is considered very difficult and dangerous, because huge amount times the mines collapsed, burying dozens or even hundreds of people working there.
Application of coal
Coal is used in the most various fields. It is widely used as solid fuel (main purpose), in metallurgy and in chemical industry, plus many other components are made from it.
It is from coal that some aromatic substances, metals, chemicals, more than 360 other processed products are obtained.
In turn, the substances produced from it have a market value tens of times higher; the most expensive method is considered to be the method of processing coal into liquid fuel.
For production of 1 ton liquid fuel 2-3 tons of coal will need to be processed. All industrial waste obtained during processing is often used for the production of building materials.
Conclusion
There are many coal deposits on earth that are still being actively mined to this day. In biology lessons in the 5th grade and even earlier, in natural history lessons in the second grade, children are introduced to this concept. In this work, we briefly repeated the basic facts about coal - origin, formula, grades, chemical composition and use, extraction and much more.
Coal is one of the most important resources widely used in industry. However, you should still be careful when disrupting the natural flow of substances, because development disrupts the relief and gradually depletes natural reserves.
Today, coal is the most widely used. With its help, electrical energy, rare and trace elements, and graphite are obtained. Coal is an important raw material in the chemical and metallurgical industries. This is why the request “buy coal” comes up very often.
Russia boasts huge coal reserves, the basins and deposits of which are scattered throughout the country. They differ in geological structure, coal quality, coal saturation and age of sediments. Depending on the structural characteristics, Russian basins are classified into folded, transitional and platform.\
Most of the deposits contain humus coals, among which the main place belongs to coking varieties. Main basins: Donetsk, Pechora, South Yakutsk and Kuznetsk. Brown coal deposits are found in the regions of Eastern Siberia and the Urals, as well as in the Moscow basin.
Coal deposits are uneven in the quality of the fossil, the volume of its reserves and the area occupied. In addition, they, like development companies, are located in different regions of the country. Today coal is mined in ten coal basins. The largest deposits are considered to be the Kuznetsk, Kansko-Achinsk, Gorlovka basins and Eastern Donbass.
The Kuznetsk basin is the main coal base country and provides half of the total volume of extracted raw materials. Almost twelve percent of mining is done by open pit mining. Kansk-Achinsk basin supplies brown coal, which is considered the cheapest in the country. Due to its low quality, it is poorly transportable, so it mainly ensures the operation of powerful thermal power plants operating on the basis of the largest open-pit mines. The Pechora basin accounts for four percent of the country's coal production. It is located away from industrial centers, mining is carried out only in mines.
Coal mining
Coal is mined in two main ways - closed and open. In the first case, these are mines or cuts. Mine - complex mining enterprise for underground coal mining. On average, she works for about forty years. Coal is mined in layers, each layer taking approximately ten years to remove. After this, the horizon is reconstructed and a deeper layer is developed. The open-pit mine involves excavating coal in benches and successive strips. Coal mined in mines and open pits is sent directly to the consumer or to processing plants, where it is first sorted and then enriched.
Promising coal basins include Lensky, Tungussky and Taimyrsky. They occupy significant areas in sparsely populated areas of Siberia and Far East. Today, coal production in the western regions is gradually declining, while in the eastern regions it is increasing. One of the oldest basins is Donbass. The coal mined here has high quality, how it differs from competitors' products.
People have been using coal fuel since ancient times. Its flammability and heat transfer, the duration of heat retention in the hearth became the salvation of people during the cold periods that cyclically replaced each other on our planet. Coal is actively used in modern times; in the fuel and energy complex it is one of the top three raw materials along with oil and gas.
How were coal deposits formed?
Formed coal deposits in places of huge green areas. This is ancient organic matter that remains after the death of tree plantations. In order for dead plants to become coal, certain conditions are necessary: wood debris must not rot under the influence of bacteria. This is only possible if they fall under swamp water, and then underground, where oxygen does not flow. Coal is considered a mineral extracted from rock layers located at various depths.
How are coal deposits found and developed?
Places where there is coal on the planet have long been explored. Its reserves in different countries huge, they will be enough for heating and industrial needs for almost three centuries. But According to geologists, there may be more of them, since deep geological prospecting for the presence of coal fuel was not carried out in all parts of the world. The development of coal deposits is relevant and brings significant income to the states that are engaged in the extraction of this solid black gold. The process of developing deposits is carried out depending on the terrain and the depth of the coal seams.
Low cost and large inventories are the main factors driving the increase in the number of applications brown coal. This type of fossil solid fuel, the earliest type of coal, has been mined by humans for hundreds of years. Brown coal is a product of peat metamorphism, in a stage between lignite and hard coal. Compared to the last one, this type fuel is less popular, however, due to its low cost, it is quite widely used for the production of electricity, heating and other types of fuel.
Structure
Brown coal is a dense, earthy or fibrous carbonaceous mass of brown or pitch-black color with a high content of volatile bituminous substances. As a rule, the plant structure, conchoidal fractures, and woody masses are well preserved in it. It burns easily, the flame is smoky, and a peculiar bad smell burning. Reacting with potassium hydroxide, it forms a dark brown liquid. When dry distilled, brown coal forms ammonia with acetic acid. Chemical composition(on average), minus ash: carbon - 63%, oxygen - 32%, hydrogen 3-5%, nitrogen 0-2%.
Origin
Brown coal forms layers of deposits sedimentary rocks- flanges, often of great power and length. The materials for the formation of brown coal are various kinds of hoops, conifers, trees and peat plants. Deposits of these substances gradually decompose without access to air, under water, under a cap of a mixture of clay and sand. The smoldering process is accompanied by the constant release of volatile substances and gradually leads to the enrichment of plant residues with carbon. Brown coal is one of the first stages of metamorphism of such plant deposits, after peat. Further stages are coal, anthracite, graphite. The longer the process, the closer the state is to pure carbon-graphite. Thus, graphite belongs to the Azoic group, coal - to the Paleozoic, brown coal - mainly to the Mesozoic and Cenozoic.
Hard and brown coal: differences
As you can see from the name itself, brown coal differs from stone coal in color (lighter or darker). There are also black varieties, but in powder form the shade of such coal is still brown. The color of stone and anthracite always remains black. The characteristic properties of brown coal are a higher carbon content compared to hard coals and a lower content of bituminous substances. This explains why brown coal burns more easily and produces large number smoke. The high carbon content also explains the mentioned reaction with potassium hydroxide and the peculiar unpleasant odor during combustion. The nitrogen content, compared to hard coals, is also significantly lower. When exposed to air for a long time, brown coal rapidly loses moisture, crumbling into powder.
Varieties
There are quite a lot of varieties and varieties of brown coal, among which there are several main ones:
- Regular brown coal, dense consistency, matte brown color.
- Brown coal of earthy fracture, easily ground into powder.
- Resinous, very dense, dark brown, sometimes even bluish-black. When broken, it resembles resin.
- Lignite, or bituminous wood. Coal with a well-preserved plant structure. Sometimes it is even found in the form of entire tree trunks with roots.
- Disodil is brown paper coal in the form of decayed thin-layered plant mass. Easily divided into thin sheets.
- Brown peat coal. Resembling peat, with a lot of foreign impurities, sometimes reminiscent of earth.
The percentage of ash and combustible elements in various types brown coal varies widely, which determines the merits of a particular type of combustible material.
Production
The methods for extracting brown coal are similar for all fossil coals. There are open (career) and closed. The oldest method of closed mining is adits, inclined wells to a coal seam of low thickness and shallow occurrence. It is used in case of financial inefficiency of quarry construction.
A mine is a vertical or inclined hole in the rock from the surface to the coal seam. This method used in deep coal-bearing seams. It is characterized by the high cost of extracted resources and a high accident rate.
Open-pit mining is carried out at a relatively shallow (up to 100 m) depth of the coal seam. Open pit or open pit mining is the most economical; today approximately 65% of all coal is mined this way. The main disadvantage of career development is a lot of damage environment. Brown coal is mainly mined using open-pit mining due to its shallow depth. Initially, the overburden (the layer of rock above the coal seam) is removed. After this, the coal is broken down using the drilling and blasting method and transported by specialized (quarry) vehicles from the mining site. Stripping operations, depending on the size and composition of the layer, can be carried out by bulldozers (for a loose layer of insignificant thickness) or rotary excavators and draglines (for a thicker and denser layer of rock).
Application
Brown coal is used much less frequently as fuel than hard coal. It is used for heating private houses and small power plants. By the so-called Dry distillation of brown coal produces rock wax for the woodworking, paper and textile industries, creosote, carbolic acid and other similar products. It is also processed into liquid hydrocarbon fuel. Humic acids in brown coal make it possible to use it in agriculture as a fertilizer.
Modern technologies make it possible to produce synthetic gas from brown coal, which is an analogue of natural gas. To do this, the coal is heated to 1000 degrees Celsius, resulting in gas formation. In practice, a fairly effective method is used: through a drilled well, brown coal deposits are supplied through a pipe. high temperature, and the finished gas is already coming out through another pipe - a product of underground processing.
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