Mining of brown coal in russia. Miner's hard work, or how coal is mined

Since ancient times, mankind has been using coal as one of the sources of energy. And today this mineral is widely used. It is sometimes called solar energy, which is preserved in stone.

Application

Coal is burned to generate heat, which is used for hot water and heating houses. The mineral is used in the technological processes of metal smelting. In thermal power plants, coal is converted into electricity by burning.

Scientific advances have made it possible to use this valuable substance in a different way. For example, the chemical industry has successfully mastered a technology that makes it possible to obtain liquid fuel from coal, as well as such rare metals as germanium and gallium. At present, carbon-graphite ones with a high concentration of carbon are extracted from the valuable minerals. Methods for obtaining high-calorific value plastic and gaseous fuel from coal have also been developed.

A very low fraction of low-grade coal and its dust are pressed into briquettes after processing. This material is excellent for heating private houses and industrial premises. In general, more than four hundred names of various products are produced after chemical processing to which coal is subjected. The price of all these products is tens of times higher than the cost of raw materials.

Over the past several centuries, mankind has been actively using coal as a fuel, necessary for the production and transformation of energy. Moreover, the need for this valuable mineral has been increasing lately. This is facilitated by the development of the chemical industry, as well as the need for valuable and rare elements obtained from it. In this regard, in Russia today, intensive exploration of new deposits is being carried out, mines and quarries are being created, enterprises are being built to process this valuable raw material.

Fossil origin

In ancient times, the Earth had a warm and humid climate in which a variety of vegetation flourished. Later, coal was formed from it. The origin of this fossil lies in the accumulation of billions of tons of dead vegetation at the bottom of the swamps, where they were covered with sediment. Since then, about 300 million years have passed. Under the powerful pressure of sand, water and various rocks, the vegetation slowly decomposed in an oxygen-free environment. Under the influence of high temperatures, which were given by closely located magma, this mass solidified, which gradually turned into coal. The origin of all existing deposits has only such an explanation.

Mineral reserves and its production

There are large deposits of coal on our planet. In total, according to experts, the earth's bowels store fifteen trillion tons of this mineral. Moreover, the extraction of coal is in the first place in terms of its volume. It is 2.6 billion tons per year, or 0.7 tons per inhabitant of our planet.

Coal deposits in Russia are located in different regions. Moreover, in each of them, the mineral has different characteristics and has its own depth of occurrence. Below is a list of the largest coal deposits in Russia:

1. It is located in the southeastern part of Yakutia. The depth of coal in these places allows open-pit mining. This does not require special costs, which affects the reduction in the cost of the final product.
2. Tuva deposit. According to experts, there are about 20 billion tons of minerals on its territory. The deposit is very attractive for development. The fact is that eighty percent of its deposits are located in one layer with a thickness of 6-7 meters.
3. Minusinsk deposits. They are located in the Republic of Khakassia. These are several deposits, the largest of which are Chernogorskoye and Izykhskoye. The basin's reserves are small. According to experts, they range from 2 to 7 billion tons. Coal, which is very valuable in its characteristics, is mined here. The properties of the mineral are such that a very high temperature is recorded during its combustion.
4. This deposit, located in the west of Siberia, provides a product used in ferrous metallurgy. The coal mined in these places is used for coking. The volume of deposits here is simply enormous.
5. This deposit produces the highest quality product. The greatest depth of occurrence of layers of minerals reaches five hundred meters. Mining is carried out both in open pits and in mines.

Bituminous coal in Russia is mined in the Pechora coal basin. Deposits are being actively developed in the Rostov region.

Choosing coal for the production process

In different industries there is a need for different grades of minerals. What are the differences between bituminous coal? The properties and quality characteristics of this product vary widely.

This happens even if the charcoal has the same marking. The fact is that the characteristics of a fossil depend on the place of its extraction. That is why each enterprise, when choosing coal for its production, should become familiar with its physical characteristics.

Properties

Coal differs in the following properties:

Enrichment degree

Depending on the purpose of use, various coal can be purchased. In this case, the properties of the fuel become clear based on the degree of its enrichment. Allocate:

1. Concentrates. Such fuel is used in the production of electricity and heat.

2. Industrial products. They are used in metallurgy.

3. fine fraction of coal (up to six millimeters), as well as dust generated as a result of rock crushing. The sludge is used to form briquettes that have good performance properties for household solid fuel boilers.

Coalification degree

According to this indicator, they are distinguished:

1. Brown coal. This is the same bituminous coal, only partially formed. Its properties are somewhat worse than those of higher quality fuel. Lignite produces low heat during combustion and crumbles during transportation. In addition, it has a tendency to ignite spontaneously.

2. Bituminous coal. This type of fuel has a large number of grades (brands), the properties of which are different. It is widely used in energy and metallurgy, housing and communal services and the chemical industry.

3. Anthracites. This is the highest quality type of coal.

The properties of all these forms of minerals differ significantly from each other. So, the lowest calorific value is characteristic of brown coal, and the highest is anthracite. What is the best coal to buy? The price must be economically viable. Based on this, the cost and specific heat are in the optimal ratio for simple coal (within $ 220 per ton).

Size classification

When choosing coal, it is important to know its dimensions. This indicator is encrypted in the grade of the mineral. So, coal happens:

- "P" - slab, which is large pieces over 10 cm.

- "K" - large, the size of which ranges from 5 to 10 cm.

- "O" - a nut, it is also quite large, with fragment sizes from 2.5 to 5 cm.

- "M" - small, with small pieces of 1.3-2.5 cm.

- "C" - seed - a cheap fraction for long-term smoldering with dimensions of 0.6-1.3 cm.

- "Ш" - a spear, which is mostly coal dust, intended for briquetting.

- "P" - private, or non-standard, in which there may be fractions of various sizes.

Brown coal properties

This is the least quality bituminous coal. Its price is the lowest (about one hundred dollars per ton). formed in ancient bogs by pressing peat at a depth of about 0.9 km. It is the cheapest fuel and contains a large amount of water (about 40%).

In addition, brown coal has a rather low heat of combustion. It contains a large amount (up to 50%) of volatile gases. If you use brown coal for burning a stove, then in terms of its quality characteristics, it will resemble raw firewood. The product is hard to ignite, has a lot of smoke and leaves behind a large amount of ash. Often, briquettes are prepared from this raw material. They have good performance characteristics. Their price ranges from eight to ten thousand rubles per ton.

Properties of bituminous coal

This fuel is of higher quality. Coal is a rock that is black in color and has a matte, semi-matte or glossy surface.

This type of fuel contains only five to six percent moisture, which is why it has a high calorific value. Compared to oak, alder and birch firewood, coal gives 3.5 times more heat. The disadvantage of this type of fuel is its high ash content. The price of coal in summer and autumn ranges from 3900 to 4600 rubles per ton. In winter, the cost of this fuel increases by twenty to thirty percent.

Coal storage

If the fuel is supposed to be used for a long time, then it must be placed in a special shed or bunker. There it must be protected from direct sunlight and precipitation.

If the heaps of coal are large, then during storage it is necessary to constantly monitor their condition. Fine fractions in combination with high temperature and moisture can ignite spontaneously.

The Russian Coal company mines brown coal in the Amur Region and the Krasnoyarsk Territory. Brown coal is an intermediate link between the peat from which it is formed and coal. In addition to peat, it is also formed from lignite. Brown coals of each deposit have their own unique characteristics and properties. Brown coal burns more easily than hard coal. It contains 60% - 80% combustible substances. It is the youngest type of fossil coal. When burned, this type of fuel is used in powder form. Brown coal is cheaper than hard coal. Therefore, its use is widespread in Russian regions - in boiler houses and small thermal power plants. Some European countries purchase it for steam power plants. The company "Russian Coal" offers a wide range of grades of brown coal.

The brown coal mined at the company's open-pit mines is of high quality. Russian Coal is ready to supply brown coal to any region of Russia as soon as possible on the most favorable terms for the buyer.

All about brown coal

Brown coals are a type of combustible fossil, weakly metamorphosed remains of ancient plants or plankton, a transitional stage from peat to bituminous coals.
They got the name from the color of the breed composing them, which varies from yellow to dark brown.
While in Russia and Europe there is a synonym term “lignite” to designate brown coals, in America lignites are distinguished as a separate variety of young coals with low calorific value, and brown coals proper, which are harder and more nutritious.

Brown coal generally consists of amorphous, often layered rock, sometimes retaining the structure of the plant residues from which it was formed. In the air, it quickly loses its structure, turning into a fine placer. In terms of chemical composition, this type of coal is poorer in carbon than coal, and contains no more than 76% of it; it also consists of oxygen (about 30%), nitrogen, hydrogen and other impurities, including uranium and other radioactive elements.

Brown coals occur at shallow depths, and sometimes very close to the surface, with seams up to 60 cm thick, which greatly facilitates their development, making open-pit mining possible.

Conditions for the formation of brown coal

Brown coals arise from peat mainly of the Mesozoic-Cenozoic age at the primary stages of coalification. Different types of coals were formed depending on natural conditions. So, in lake basins or sea lagoons, sapropelites were formed - coals composed of the remains of algae and aquatic organisms. They are characterized by higher viscosity and higher volatile content.

The overwhelming majority of brown coals were formed in bog conditions, where plant remains did not have time to decompose completely, being buried under younger deposits. Later, under the influence of gravity, the peat was pressed at a shallow depth and transformed into the so-called humus brown coal.

The use of coal from antiquity to the present day

Brown coal, like its relatives - peat and coal, has been used as fuel since antiquity; ancient scientists wrote about it in their works. The Indians, who did not yet know the Europeans, used coal to burn ceramics. In England, from antiquity, they were heated with coal, by the 14th century having introduced its use in the furnaces of London. At one time, the people tried to rebel against an unconventional type of fuel, considering it unclean. However, the benefits of using coal were clear and the protests died down.

Already in the middle of the 17th century, a treatise was published in Latin, telling about the ways of using peat and its varieties. Gradually, the rate of coal use increased. Currently, brown coal is used as a power fuel. In the chemical industry, it is in demand for obtaining various types of fuel - liquid and gaseous; fertilizers and synthetic materials are produced from it.

Traditionally, it is believed that brown coal is used as a fuel to a lesser extent than bituminous. However, its low cost and availability make it attractive for small CHP plants and for consumers in close proximity to developments. In Germany, about 20% of electricity is obtained from brown coal, while in Greece its share in the energy sector is about 50%.

Brown coal marking

All brown coals in our country belong to one grade of coal - B. According to GOST, this grade is divided into three classes according to the stages of coalification, and three technological groups according to moisture content. They are also divided by hardness and density, structure.

The international classification implies the division of brown coals into six moisture classes and five classes according to the degree of rock metamorphosis.

World reserves and production

The proven reserves of brown coal in the world are enormous. The leaders in terms of reserves are the United States, Russia and China. It is interesting that Germany, three times behind Russia in terms of reserves of brown coal, is the largest producer of this fuel in Europe. The United States traditionally conserves its reserves, occupying only the fourth place in the extraction of brown coal.

Huge deposits are drawn by schoolchildren on contour maps, boldly painting over large chunks of Siberia and Europe; in America, the western and southern states are listed as the most coal-bearing regions in the world. Combined with the development of new fuels for coal processing, the energy outlook for humankind looks far less bleak than has been portrayed in recent years.

Qualitative characteristics of brown coal from the Russian coal company

As a result of prolonged exposure to high temperatures and pressures, brown coals are converted into coal, and the latter into anthracite.

The irreversible process of gradual change in the chemical composition, physical and technological properties of organic matter at the stage of transformation from brown coal to anthracite is called coal metamorphism. Structural and molecular rearrangement of organic matter during metamorphism is accompanied by a sequential increase in the relative carbon content in coal, a decrease in the oxygen content, and the release of volatile substances; changes in hydrogen content, heat of combustion, hardness, density, fragility, opticality, electricity, and other physical properties. Bituminous coals at the middle stages of metamorphism acquire sintering properties - the ability of gelified and lipoid components of organic matter to pass, when heated under certain conditions, into a plastic state and form a porous monolith - coke.

In zones of aeration and active action of groundwater near the surface of the Earth, coals are subject to oxidation. In terms of its effect on the chemical composition and physical properties, oxidation has the opposite direction in comparison with metamorphism: coal loses its strength and sintering properties; the relative oxygen content in it increases, the amount of carbon decreases, humidity and ash content increase, and the heat of combustion sharply decreases. The depth of oxidation of fossil coals, depending on the modern and ancient relief, the position of the groundwater table, the nature of climatic conditions, material composition and metamorphism, ranges from 0 to 100 meters vertically.

The greatest heat transfer is obtained from anthracites, less from brown coal. Bituminous coals - win in terms of price - quality ratio. Coal grades D, G and anthracite are most often used in boiler houses, because they can burn without blowing. Coal of grades SS, OS, T is used to obtain electrical energy, because it has a large heat transfer during combustion, but the combustion of this type of coal is associated with technological difficulties, which are justified only if a large amount of coal is needed. In ferrous metallurgy, grades G, Zh are usually used, for the production of steels and cast iron. The fraction of a given coal grade is determined based on the lower value of the finest fraction and the larger value of the largest fraction indicated in the name of the coal grade. So, for example, the fraction of the DKOM brand (K - 50-100, O - 25-50, M - 13-25) is 13-100 mm.

Brown coal

Brown coal is in the form of a dense, earthy, woody or fibrous carbonaceous mass with a brown streak, with a significant content of volatile bituminous substances. The plant woody structure is often well preserved in it; fracture, earthy, or woody; the color is brown or pitch black; easily burns with a smoky flame, emitting an unpleasant, peculiar smell of burning; when treated with caustic potassium gives a dark brown liquid. On dry distillation, it forms ammonia, free or associated with acetic acid. The specific gravity is 0.5-1.5. Average chemical composition, excluding ash: 50-77% (average 63%) carbon, 26-37% (average 32%) oxygen, 3-5% hydrogen and 0-2% nitrogen.

The photo below shows brown coal.

Brown coal, as the name shows, differs from bituminous coal in color (sometimes lighter, then darker); there are, however, black varieties, but in this case they are still brown in powder, while anthracite and coal always give a black line on a porcelain plate. A significant difference from bituminous coal is a lower carbon content and a significantly higher content of bituminous volatiles. This explains why brown coal burns more easily, gives more smoke, smell, and also the aforementioned reaction with caustic potassium. The nitrogen content is also significantly inferior to coal.

Coal

Coal is a raw material for producing naphthalene. Coal and coke are used as a reducing agent in metallurgy in iron smelting. Depending on the grade, bituminous coal is 75% to 97% carbon, water and volatile compounds. Coal is the basis of almost all hydrocarbons. By its structure, coal is hard coal, it is finely crushed graphite.

The characteristics of hard coal are different and depend on the place of extraction. To select a suitable grade and type of coal, you need to familiarize yourself with the characteristics.

The main characteristics that determine the quality of bituminous coal are: moisture content, heat of combustion, sulfur content, ash content and the release of volatile substances.

The coal grade is determined by the size of the piece and the grade. More than 14 technological coal grades are known.

Coal- sedimentary rock, which is a product of deep decomposition of plant remains (tree ferns, horsetails and lymphoids, as well as the first gymnosperms). Most of the coal deposits were formed in the Paleozoic, mainly in the Carboniferous period, about 300-350 million years ago. In terms of chemical composition, coal is a mixture of high molecular weight polycyclic aromatic compounds with a high mass fraction of carbon, as well as water and volatile substances with small amounts of mineral impurities, which form ash when burning coal. Fossil coals differ from each other in the ratio of their constituent components, which determines their heat of combustion. A number of organic compounds that make up coal have carcinogenic properties.

The use of coal is diverse. It is used as a household, energy fuel, raw material for the metallurgical and chemical industries, as well as for the extraction of rare and trace elements from it. Liquefaction (hydrogenation) of coal with the formation of liquid fuel is very promising. For the production of 1 ton of oil, 2-3 tons of coal are consumed; during the embargo, South Africa almost completely provided itself with fuel due to this technology. Artificial graphite is obtained from coal.

Coal it was historically used by humans to generate energy and heat when it was burned. The principle of transformation of plant remains into coal is based on the fact that over many millions of years, under conditions of increased pressure and lack of oxygen, peat did not rot and, accordingly, did not return the previously obtained carbon to the atmosphere. As a result of this long process, coal was formed, which, in addition to carbon (75-97%), also includes hydrogen (1.5-5.7%), oxygen (5-15%), sulfur (0.5 -4%), nitrogen (<1,5%) и незначительная часть летучих веществ. Нагревая каменный уголь до пиковых температур, из него получают так называемый кокс, используемый для производства чугуна, а сгораемые при сухой перегонке летучие вещества, образуют каменноугольные смолы, составляющие основу некоторых типов промышленных масел.

Anthracite

It differs from stone in its increased carbon content. If brown coal contains 65-70% carbon, then anthracite contains 92-98%. Anthracite coal is a good fuel and has an increased heat transfer. Anthracite is difficult to ignite, however, during combustion it releases a large amount of energy (7-8.5 kcal / unit) and practically does not bake. It is anthracite coal that is used in blast furnaces and for boiler houses..

If anthracite coal is used on an industrial scale, then in private houses, stove coal is used to heat the premises, as a rule, of the WPC, DKO brands and their analogues... It burns in a furnace, this coal is faster, however, compared to anthracite, it has the main advantage - this coal is much easier to ignite, and such coal costs less. The price of stove coal is almost half that of anthracite. WPC coal is a long-flame "fist" (where K is the designation of the size or fraction of coal) by weight is lighter than anthracite and outwardly differs in its matte black color, i.e. unlike anthracite, furnace charcoal does not have a glassy luster.

Anthracite- it is black coal, externally differs from charcoal in glass luster and increased hardness. Being an excellent fuel, anthracite is used in boiler rooms, where, burning in special furnaces, it releases energy used for heating. Anthracite is a naturally occurring coal mined from tectonic coal seams. In the process of coal formation, anthracite goes through several stages. First, the wood dies away, falls into the soil, which turns into peat, then the peat, under the influence of natural forces, is gradually compressed and, solidifying, becomes brown coal. From brown, coal turns into stone and only then becomes anthracite. A similar cycle of transformation of wood into anthracite takes about 40 million years.

TO coal... According to its external features, it differs from peat in greater compaction and a lower content of distinguishable plant residues, from coal - mainly in the color of brown tones. It is also diagnosed by reactions with caustic alkali and dilute nitric acid, staining solutions, respectively, in dark brown and bright yellow (to red-brown) colors. It turns brown and cracks in the air; high hygroscopicity and humidity are characteristic. Density 1200-1500 kg / m 3. Distinguish between earthy friable brown coals, dense matte and shiny. According to the composition of the initial substance, most brown coals belong to humites, in which sapropel and humus-sapropel varieties are found in the form of interlayers. Of microcomponents of coal in most brown coals (80–98%), representatives of group showcase, in some varieties - fusinite or liptinite.

The elemental composition of the combustible mass of brown coals: C 65–76%, H 4–6.5%, sometimes more, O + N 18–30%; combustion heat 23.9–32.0 MJ / kg; content of humic acids 2–63%, volatile substances 40–65%, primary resin 5–20% and more. According to the degree of metamorphism ( coalification) brown coals are divided into 3 classes (01, 02, 03); this division is based on the vitrinite reflectance index (correspondingly less than 0.30%, 0.30–39%, 0.40–0.49%). With an increase in the degree of metamorphism in brown coals, the carbon content and specific heat of combustion increase, the content of oxygen, humic acids and resins decreases. Industrial classifications of brown coals in different countries are adopted for various technological parameters. In Russia, brown coals are divided into three technological groups according to moisture content (1B - over 40%, 2B - 30–40%, and 3B - less than 30%). According to the international classification adopted by the European Economic Commission (1957), brown coals are divided into 6 classes in terms of moisture content and 5 groups in terms of the yield of semi-coking resins. There are other classifications. In a number of countries (India, Australia, etc.) brown coals are called lignites. A significant part of brown coals occurs in coal seams (deposits) with a thickness of 10–60 m (sometimes 100–200 m) and at shallow depths, which makes it possible to extract them mainly by open pit mining.

By reserves (billion tons), brown coal basins are divided into unique (over 500), large (50–500), medium (10–50) and small (less than 10). Total world reserves are estimated at 1316 billion tons, proven reserves are 398 billion tons (2nd half of the 2000s). Proven reserves are mostly concentrated in the United States - 135.3 billion tons ( Fort Union, Mississippi and Texas coal basins), Russia - 101.5 billion tons ( Kansk-Achinsk coal basin, Irkutsk coal basin, Lena coal basin , Moscow region coal basin ), China - 53.3 billion tons, Australia - 39.9 billion tons (lignite basin Latrobe Valley), Brazil - 10.1 billion tons (lignite basin Alta Amazonas ), Germany - 6.6 billion tons ( Lower Rhine coal basin, Thuringo-Saxon and Magdeburg coal basins).

World production in the 2nd half of the 2000s amounted to 924.83 million tons.The main coal-mining countries (production in million tons): Germany (176.3), USA (76.4), Russia (73.0), Greece (71.5), Australia (67 , 7), Turkey (61.0), Poland (60.8).

Brown coal is used as a power and municipal fuel, for the production of coal briquettes, gaseous and liquid fuels, carbon-alkali reagents, humic acids, wax, metallurgical coke, extraction of rare and trace elements.

The industrial classification of brown coals provides for their division into groups according to moisture and ash content and into grades according to the size of lumps. By the moisture content in the working fuel ( W p) brown coals are divided into three groups: B1, B2 and B3 at W p> 40, W p = 30 ... 40 and W R<30 % соответственно. По зольности сухой массы (BUT c) brown coals, depending on the basin, are divided into a number of groups (from three to five). According to the size of lumps, brown coals are divided into grades: BK (large brown - with lump sizes from 50 to 100 mm); BO (brown walnut - pieces from 25 to 50 mm); BM (small brown - pieces from 13 to 25 mm); BR (brown ordinary - pieces up to 200 mm for mines and up to 300 mm for quarries).

Deposits of brown coal in our country are ubiquitous, and their reserves are very large. In the Kansk-Achinsk Basin alone, the geological reserves of brown coal are estimated at 600 billion tons, of which 140 billion tons can be mined in the open pit.

Even larger reserves of coal are concentrated in the Tunguska basin (several trillion tons). Large deposits of brown coal are found in Kazakhstan, Ukraine, in the central zone of the Russian Federation, in Central Asia and in the Far East.

Due to the high ballast content and low mechanical strength, brown coals are not transportable over long distances and, like peat, are classified as local fuels. However, the various technologies developed for their preparation make it possible to convert brown coals into transportable fuel, which, in combination with new combustion methods (for example, in a fluidized bed), will significantly expand the possibilities of their transportation and make their combustion at power plants more efficient.

The energy-technological or energy-chemical use of brown coals is promising, in which they can be used to obtain synthetic liquid fuel, chemical raw materials, and various commercial products.

Coals. The change in the organic matter of fossil fuels at the Carboniferous stage occurs under the influence of a number of geological factors in zones of increased tectonic activity. The main factor, apparently, is the temperature (it is assumed that the formation of coal took place at temperatures of 250-350 ° C). It has been established that some rocks and mineral inclusions in the coal mass (for example, oxides of iron, aluminum, etc.) can play the role of catalysts for a number of reactions in the coal substance. As a result, the organic material is further enriched with carbon with the loss of oxygen- and hydrogen-containing compounds that form carbon monoxide and dioxide, water, and methane. The humic acids contained in brown coal are converted into insoluble neutral humins at the coal stage.

Bituminous coals are very diverse in chemical maturity, and therefore they are classified according to a number of characteristics: the release of volatile substances referred to the combustible mass of fuel, V d, the sintering capacity of the solid residue, determined by heating the fuel without air access to a temperature of 850 ° C under standard conditions, and the heat of combustion per bomb per combustible mass. In the accepted classification, bituminous coals are subdivided into the following grades (with the designation of grades): long-flame (D), gas (G), gas fat (GZh), fatty (F), coke (K), coke fat (KZh), coke second ( K2), lean sintered (OS), slightly sintered (CC), lean (T). The number of coal grades and their characteristics are determined by GOST for each pool.

The reserves of coal in the Russian Federation are also very large, while most of them, like brown coal, are concentrated in Siberia. Among the largest coal basins in the country, Kuznetsk, Pechora, Yuzhno-Yakutsk, and Kizelovsky are currently being developed.

Bituminous coals have a relatively lower ash and moisture content than brown coals: BUT p = (5 ... 15)%; W p = (5 ... 10)%. As a result, their heat of combustion is higher:

Q n p = (23 ... 27.3) MJ / kg (5500 ... 6500 kcal / kg).

Anthracite. Anthracite is the end result of coal conversion. This type of coal is characterized by a very high degree of coalification (the carbon content in the combustible mass reaches 94 - 96%), high hardness and density, low moisture content and a well-defined fine-crystalline structure of natural graphite. Due to the increased fragility, the extraction of anthracite is accompanied by the formation of a larger amount of fines (with pieces less than 6 mm in size) - the so-called lump. Anthracite shtyb (ASh) is a relatively low-grade energy fuel, the combustion of which was for the first time in the world organized on a large scale at the power plants of the USSR in the pre-war period.

These coals have a low volatile yield ( V r = 2 ... 9%).

The heat of combustion of such coals is quite high: Q n p = 34.5 MJ / kg (8300 kcal / kg). Coals, by their characteristics located between bituminous coals and anthracites, are called semi-anthracites... The volatile output of such coals is V r = (5 ... 10)%, and the heat of combustion is somewhat higher than that of anthracites ( Q n p = 35 MJ / kg). Semi-anthracites and anthracites are divided according to the volumetric yield of volatile substances in the conventional fuel mass V g about: semi-anthracites - (220 ... 300) cm 3 / g, anthracites - less than 220 cm 3 / g. The heat of combustion of volatile substances for anthracites is 43.1 MJ / kg, for semi-anthracites - 48.2 MJ / kg.

Oil shale. Oil shale belongs to the class of sapropelites, strongly ballasted by sedimentary rocks (sand, clay), the content of which reaches 70%. With a ballast content of more than 70%, the combustion of sapropelite in conventional combustion devices (layered or chamber) becomes impossible, however, in fluidized bed furnaces, it is possible to burn oil shale containing less than 30% of combustible organic matter.

As a typical low-grade fuel, oil shale is also a valuable raw material for the production of synthetic liquid fuels and combustible gas, in particular when used in combination. Shale ash is also of some value as a building material and a product for soil deoxidation in agriculture.

Our country has large reserves of oil shale. Shale fuel deposits are located in the regions of Kuibyshevskaya, Saratovskaya, Ulyanovskaya, Leningradskaya and others.

The ash content of the shale is very high and reaches BUT p = (50 ... 60)%. Due to the large ballast, their calorific value is low Q n p = (5.87 ... 10) MJ / kg (1400 ... 2000 kcal / kg). The content of hydrogen in the combustible mass is high H p = (7.5 ... 9.5)%, which causes a large release of volatiles, reaching (80 ... 90)%, and their flammability.

Fuelwood and municipal waste. In addition to firewood itself, this category of fuel also includes various types of plant waste generated both during felling and during its further processing (stumps, twigs, branches, top parts of trees, trimmings, chips, shavings, sawdust, the so-called waste: needles , foliage, dead wood, bark), crop waste: straw, fire, husk, stems of some plants, etc.

The organic part of wood and other plant formations consists mainly of carbohydrates and, to a lesser extent, of proteins, fats, waxes and resins that are part of plant cells or fill the intercellular space of plant tissue. The main components of carbohydrates are cellulose (C 6 H 24 O 5) x, from which the cell walls are built, hemicellulose, which is a hydrolyzing part of cellulose, and a special encrusting substance that fills the intercellular spaces - lignin (C 9 H 24 O 10). The cellulose content in the organic part of multicellular plants reaches 60%, the lignin content ranges from 20 to 30%, depending on the species and age of the wood. The content of mineral salts in the main wood is 0.21%, in birch - 0.29 ... 0.38%, in oak - 0.37%, in spruce - 0.22 ... 0.37%. However, in the bark, leaves, as well as in the stems of annual plants, the content of mineral salts is much higher and is: in spruce bark - 5.77%, in beech bark - 8.84%, in straw - from 3.3 to 7.2%, in husk - 2.31%, reeds - 7.4%. The elemental composition and characteristics of various types of wood fuel are given in table. 6.