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, receiving the heat that goes for hot water and heating homes. Minerals are used in metal smelting processes. At thermal stations, coal is converted into electricity by burning.
Scientific advances have allowed the use of this valuable substance in a different way. So, in the chemical industry, technology has been successfully mastered that makes it possible to obtain liquid fuel from coal, as well as rare metals such as germanium and gallium. Carbon-graphite composite materials with a high carbon concentration are currently being extracted from a valuable mineral. Methods have also been worked out for the production of plastics and gaseous fuels of high calorific value from coal.
A very low fraction of low-grade coal and its dust are pressed into briquettes after processing. This material is excellent for heating private homes and industrial premises. In total, more than four hundred items of various products are produced after chemical processing, to which coal is exposed. The price of all these products is ten times higher than the cost of raw materials.
Over the past few centuries, mankind has been actively using coal as a fuel necessary for the production and conversion of energy. Moreover, the need for this valuable mineral has been growing lately. This is facilitated by the development of the chemical industry, as well as the need for valuable and rare elements derived from it. In this regard, in Russia today, intensive exploration of new deposits is underway, mines and quarries are being created, enterprises are being built to process this valuable raw material.
Origin of fossil
In ancient times, the Earth had a warm and humid climate in which diverse vegetation developed rapidly. From it in the future, coal was formed. 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. About 300 million years have passed since then. Under a powerful press of sand, water and various rocks, the vegetation slowly decomposed in an oxygen-free environment. Under the influence of high temperatures, which was provided by closely located magma, this mass hardened, which gradually turned into coal. The origin of all existing deposits has only such an explanation.
Mineral reserves and its extraction
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 in its volume is in the first place. It is 2.6 billion tons per year, or 0.7 tons per inhabitant of our planet.
Coal deposits in Russia are located in various regions. Moreover, in each of them, the mineral has various characteristics and has its own depth. The following is a list of the largest coal deposits in Russia:
- Elgin field. It is located in the southeastern part of Yakutia. The depth of coal in these places allows for open mining. This does not require special costs, which affects the reduction in the cost of the final product.
- Tuvinskoye field. According to experts, there are about 20 billion tons of minerals on its territory. The field is very attractive for development. The fact is that eighty percent of its deposits are located in one layer, having a thickness of 6-7 meters.
- Minusinsk deposits. They are located in the Republic of Khakassia. These are several deposits, the largest of which are Chernogorskoye and Izykhskoye. Pool stocks are small. According to experts, they make up from 2 to 7 billion tons. Here coal is mined very valuable in its characteristics. The properties of the mineral are such that a very high temperature is recorded during its combustion.
- Kuznetsk coal basin. This field, located in the west of Siberia, provides a product used in ferrous metallurgy. Coal mined in these places is used for coking. The volume of deposits here is simply huge.
- Kuznetsk Alatau. This deposit produces the highest quality product. The greatest depth of occurrence of mineral strata reaches five hundred meters. Mining is carried out both in open pits and in mines.
Coal in Russia is mined in the Pechora coal basin. Actively developing deposits in the Rostov region.
The choice of coal for the production process
In various industries there is a need for different brands of minerals. What are the differences between coal? The properties and quality characteristics of this product range widely.
This happens even if the coal has the same marking. The fact is that the characteristics of a fossil depend on the place of its extraction. That is why every enterprise, choosing coal for its production, should get acquainted with its physical characteristics.
The properties
Coal varies in the following properties:
- Density. This is one of the most important characteristics, which ranges from 1.28 to 1.53 grams per cubic centimeter. With increasing density values, the specific heat of combustion of coal increases.
- Carbon content. This figure ranges from 75 to 97 percent. With a higher carbon content in the fuel, less volume remains for foreign impurities. This allows you to get the maximum amount of energy during the combustion of the product.
- Mechanical strength. This characteristic determines the ability of the fossil to withstand transportation. This parameter ranges from 40 kilograms per square centimeter (for brown coals) to 300 (for anthracites).
- Sulfur content. In coal, it can be from 0.5 to 5.4 percent. With a lower value of this value, it is safer to use fuel.
- The yield of volatile components (2-45%).
- Humidity. Fuel may contain 4 to 15 percent moisture. From this indicator directly depends on whether coal is effective in combustion. The properties of a wetter product are fundamentally different from dry. Such coal crumbles and undergoes rapid weathering.
- Ash content. This characteristic indicates the amount of non-combustible mixtures contained in the fossil. At lower ash content, specific heat increases. Anthracites have the lowest percentage of non-combustible mixtures. It is within 2%. Ash content within thirty percent is acceptable for heating. The highest value of this characteristic is 45%.
- Specific calorific value. This indicator ranges from 6500 to 8600 kcal / kg. It characterizes the amount of heat that is generated during the combustion of one kilogram of fuel.
Degree of enrichment
Depending on the purpose of use, various coal can be purchased. The properties of the fuel in this case become clear, based on the degree of enrichment. Allocate:
1. Concentrates. Such fuel finds application in the production of electricity and heat.
2. Industrial products. They are used in metallurgy.
3. Sludge. This is a small fraction of coal (up to six millimeters), as well as dust formed as a result of crushing the rock. Briquettes are formed from the sludge, having good performance properties for domestic solid fuel boilers.
Degree of coalification
On this indicator distinguish:
1. Brown coal. This is the same coal, only partially formed. Its properties are slightly worse than that of a better fuel. Lignite produces low heat during combustion and crumbles during transportation. In addition, he has a tendency to spontaneous combustion.
2. 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, utilities and the chemical industry.
3. Anthracites. This is the highest quality type of coal.
The properties of all these forms of mineral are significantly different from each other. So, brown coal is characterized by the lowest calorific value, and anthracites are the highest. What is the best coal to buy? The price should be economically feasible. On this basis, the cost and specific heat in the optimal ratio are found for simple coal (within 220 dollars per ton).
Size classification
When choosing coal, it is important to know its size. This indicator is encrypted in the mineral brand. So, coal happens:
- “P” - slab, which is a large pieces of more than 10 cm.
- “K” - large, the sizes of which are from 5 to 10 cm.
- “O” is 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 smoldering with dimensions of 0.6-1.3 cm.
- “” - a bayonet, which is mostly coal dust, intended for briquetting.
- “P” - ordinary, or non-standard, in which fractions of various sizes can be.
Brown coal properties
This is the least quality coal. He has the lowest price (about a hundred dollars per ton). Brown coal was formed in ancient swamps by pressing peat at a depth of about 0.9 km. This is the cheapest fuel containing 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 the furnace, then by its quality characteristics it will resemble raw firewood. The product flames up heavily, smokes heavily 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.
Coal properties
This fuel is of better quality. Coal is a rock having a black color and a matte, semi-gloss or shiny 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 heat 3.5 times more. The disadvantage of this type of fuel is its large ash content. The price of coal in the 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 over a long period, then it must be placed in a special barn or bunker. There it must be protected from direct sunlight and from rain.
If the heaps of coal are large, then during storage you need to constantly monitor their condition. Fine fractions in combination with high temperature and moisture can ignite spontaneously.