This rock, which is formed in the thickness of the earth's crust, is very diverse. To date, its varieties are distinguished, such as, for example, brown coal, anthracite, coal. The composition of coal is moisture and mineral impurities. However, with regard to moisture, it significantly reduces the heat of combustion.
The composition of the breed. Chemical substances
Besides the fact that coal contains moisture, its composition also includes such a substance as sulfur. This impurity is also considered harmful, but it is not completely found in its pure form, but as a part of impurities such as pyrite, calcium, iron sulfate. When using coal, or rather, burning it with such impurities in its composition, harmful evaporation will form - sulfur dioxide, or sulfur dioxide. It negatively affects human health if they breathe. It can cause rapid corrosion of the metal, as well as poison the atmosphere with its fumes. It is worth noting that a rather low sulfur content in the coal, which is mined in the Donetsk basin. The indicator of this substance is only 1-2%. If we compare with the basins of the central and northern regions, then in them the content of this harmful impurity only starts at 3.5%. The full chemical composition of the raw materials is as follows:
- the highest percentage of carbon is from 50 to 96%;
- carbon is followed by oxygen, the content of which is from 25 to 37%;
- the third in this list is hydrogen, its percentage is from 3 to 6%;
- the last chemical is nitrogen, its content can be from 0 to 2.7%.
Peat
To date, peat is also used, which is the remains of a rock. It is used quite widely, despite the fact that it is considered, in fact, a waste. It is worth noting here that the composition of coal of this variety is different in that the quantitative content of all harmful impurities, including sulfur, is much less. The percentage of the chemical element of carbon also decreased to 50-60%.
Brown coal
Brown coal itself is an earthy mass with a sufficiently high density, which is formed from peat, but at the same time perfectly retains its woody structure. The use of coal of this type is much less common than stone, for example. This is due to the fact that during combustion it creates a smoky flame, which also creates a rather unpleasant odor. Most often it is used for dry distillation. With its help it is possible to obtain substances such as, for example, ammonia with acetic acid. This breed is considered the youngest of all other varieties. The composition of coal of this type is as follows:
- as in the previous type, carbon prevails here - 50-77%;
- practical oxygen content is the same - 26-37%;
- the percentage of hydrogen is 3-5, and nitrogen 0-2.
It is worth adding that the strong development of technology has led technologists to learn how to obtain synthetic gas from this raw material, which can be used as an alternative to fuel oil.
Coal
This fossil material is a transition material from brown coal to anthracite. It differs in that it is an excellent fuel, unlike brown matter. This breed is the most mined in our time. It is most widely used as a fuel for thermal power plants, for example. Great for heating private houses, for the operation of factories, etc. The heat of combustion, which this type of raw material has, is much higher than that of brown. As harmful impurities, coal of this type contains moisture in an amount of 3 to 12%. In addition, it includes 32% of volatile burning substances.
The chemical composition is different from previous species. The amount of carbon is much higher - from 75 to 93%. The oxygen content decreased significantly - 3-19%, the hydrogen content remained approximately at the same level - 4-6%. The nitrogen index is still as low - up to 2.7%.
If you ask the question which coal is better, then the answer to it will most likely be the following: anthracite. It differs in that its structure is as dense as possible, the surface shines a little, and the calorific value has the best indicator. Its only drawback is that it lights up badly enough. Most often it is used to make things like carbon electrodes, electrode mass. Its use as a fuel feed in the metallurgy industry is very common. The depth of this rock is quite large - 6 km. Of chemicals, it contains carbon in an amount of 95-97%, and also hydrogen - from 1 to 3%.
The method of mining
It is worth noting that the mining method very much depends on the location of the coal deposit, or rather, on the depth of its occurrence. Depending on this factor, an open (career) method is distinguished from a mine, closed method. Each method is distinguished by its technology, as well as advantages and disadvantages.
Open mining method
The main advantage of open pit coal mining is relative safety. The thing is that it is used only if the depth of the rock is not more than 100 meters. In other words, a shaft is not created that can collapse during an accident. The extraction process itself is carried out according to the following procedure.
First you need to remove the top layer of soil with which the rock is covered. This layer is called overburden, and the method of its removal is called overburden. This procedure, depending on the type of soil, is carried out using bulldozers, draglines, bucket-wheel excavators or scrapers. After the soil layer is removed, you can proceed to crushing the rock itself. For this, crushers, water guns, bulldozers and other equipment are used. If the rock in the coal deposit is too dense, in rare cases, blasting coal blasting is used. This mining method usually covers a fairly large area.
As for the disadvantages of the method, they are as follows:
- Firstly, causing significant damage to the environment at the place of extraction.
- Secondly, all the rock that is mined in this way contains a large amount of harmful impurities in its composition.
The main advantages of open pit coal mining, in addition to safety, are high speed as well as profitability.
Second method
The closed, or mine method, as you might guess, is used if the rock lies deep enough underground. On flat terrain up to the seam with coal, vertical or horizontal channels are formed, after which a mine is created. If the coal seam is in a mountainous area, the adit is the place that opens the mine.
Underground coal mining can be carried out using lavas or chamber-pillar method. Lavas are long faces. In one mine there may be one or more of such faces. In such faces, coal is cut into pieces using a mining combine. In order to deliver raw materials to the surface, the same combine is used. He loads the rock onto the conveyor. If you use this method, you can get almost all the coal that is contained in the reservoir. If the coal bed is not too deep, then the chamber-pillar method is used. In this case, pillars and horizontal passages are used that are formed between them.
The coal industry is undergoing changes. The technology of an integrated automated production system using mechanized roof supports is being introduced. A method is being actively developed that will allow you to remotely control all mining mechanisms.
The advantages of the method include the following:
- the resulting coal will be of very high quality;
- this type of extraction is much less harmful to the environment;
Among the shortcomings, it is worth highlighting that this method is the most dangerous method of production, and significant financial costs for its implementation will also be required.
Donetsk coal basin
This pool is located in areas such as Donetsk, Lugansk, Dnepropetrovsk from Ukraine. In addition, it is also located in the Rostov region of the Russian Federation. The total area of this basin is approximately 60 thousand km 2 , 50 thousand of which are located precisely on the territory of Ukraine. If we talk about its length, then it is about 650 km in the sub-latitudinal direction. Moreover, its maximum width reaches only 200 km. As for the quality and properties of the coal mined, they are very different. The thing is that in the Donetsk coal basin there is a whole metamorphic series of this fossil. In other words, any coal can be mined here - from brown to anthracite.
Quality coal for kindling
Quite often, the question arises of how to determine the quality of coal suitable for kindling a solid fuel boiler. Knowing all its properties is optional. Following is noteworthy:
- Calorie content, or heat of combustion. This characteristic describes how much heat a solid fuel can produce during combustion.
- Ash is the main characteristic of the quality of raw materials. The smaller the numerical indicator of this characteristic, the better coal will be, which means it will produce more heat during combustion. For high-quality breeds, the indicator is less than 25%.
- It is important to monitor humidity. It can be external or internal. The outer one can be removed if you just dry the coal, but the inner one - only during combustion.
Activated carbon
The structure of this coal is porous, and it is obtained from other different carbon-containing materials that differ in organic origin. Carbon in such raw materials will be from 87 to 97%; hydrogen, nitrogen and oxygen are also present. In its chemical composition, this type of coal is more similar to graphite. In addition, this type of raw material can be divided into several classes depending on the type of raw material to be obtained, by the activation method, activation method, and purpose.