Data Bank

What is Coal?

Coal is a combustible sedimentary organic rock. Coal is mainly composed of elements such as carbon, hydrogen and oxygen, and it has been formed as a result of heat, pressure and microbiological effects for a long time (millions of years) between the other rock layers. Coal is divided into types according to organic maturity;

HOW DOES COAL FORM?

Coal was formed as a result of the alteration of the layers formed as a result of the accumulation of turbines in the swamp areas. These deposits were buried in depth as a result of the accumulation of various sediments and the movements of the supply. These burials are buried; When they are exposed to increasing heat and pressure, they become physical and chemical changes and become coal. This process takes place in millions of years and the coals are divided into Lignite, Subbitum, Coal, Bituminous coal and Anthracite types according to their organic maturity.

Lignite and partly Sub-bituminous coals are generally soft, brittle and matt in appearance. The main feature of this type of coals is that they contain relatively high moisture and have a low carbon content. Anthracite and bituminous coals are generally seert and bright in appearance. Relatively low moisture content and high carbon content. Geologically, the ages of coals range from 400 million to 15 million years. Generally, aged coals are of higher quality.

WHY COAL IS IMPORTANT IN DAILY LIFE ALL OVER THE WORLD?

Coal It is the oldest in the world and is a clean fossil fuel that is reliable and can be obtained at low costs.

Common: Coal is produced in more than 50 countries around the world. Coal reserves, like other fossil fuels (oil and natural gas), are not common in a particular part of the Earth but are widespread throughout the world.

Safe: Coal is the safest fossil fuel in terms of use, storage and transportation.

Reliable: In terms of reliable and reliable supply of electrical energy in industrial and other fields, the widespread presence of coal in the world and the fact that it is produced by many countries provide reliability in supply.

Clean: By using Clean Coal Technologies, coal is used all over the world without polluting nature.

Cheap: As it is a cheap and competitive fuel in electricity generation, 40% of the world's electricity production is supplied from coal.

HOW DOES COAL FORM?

Coal is not homogeneous, compact, mostly composed of lignocellulosic plant parts, shows stratification, mostly C, small amounts of H - O - S and N elements, but inorganic materials (such as clay, silt, z elements), brown and flammable, solid fossil organic bodies in black tones. Coals are used as fuel raw materials, as well as for various purposes (coke production, chemical production).

Coals, swampy environment, appropriate (humid and hot climate, the presence of sufficient organic matter, the presence of the Ph conditions around 4-5 Ph, the swamp material with the arrival of downward sedimentation, swamp, depending on the time such conditions are covered) they are formed as a result of some chemical reactions and physical and chemical changes of this organic material.

THE ENVIRONMENTS IN THE SWABS THAT MAKE COALS SQUARE

• Deltas (where the thickest coal veins are formed)
• Lakes (Lake shores are suitable marsh environments where thick coal veins occur),
• Lagoons (They form fine coal veinlets with marine effect)
• River overflow plains (They form fine coal veinlets)

CARBONIZATION

Mostly plant materials or plant parts are deposited in suitable swampy environments and are buried underground with geological functions. After burial, these organic bodies are affected by the pressure conditions created by burial, and then by the thermal conditions of the environment. As a result of this effect, physical and chemical changes occur within this organic matter. These organic materials, formerly known as peat and known as the ancestors of coals, have darker colors and have a harder structure over time. As a result of the influence of temperature and pressure conditions on these masses, water and water vapor, carbon dioxide (CO2), oxygen (O2) and hydrogen (H2) (in the anthracite stage) are removed from this environment (peat to hard coal stage) respectively. Of course, the ideal conditions and the thermal conditions of the environment must be dominant and increased in the long term (thousands of years). ground temperature increases by 10 ° C every 30 meters. Of course, the temperature increase is ideal and applies to normal conditions. Apart from these conditions (volcanic activity, fault movements, in the presence of radioactive elements) the temperature of the earth increases in an extraordinary way and in excess of normal. As the temperature of the ground increases, this organic material, which was formerly called "peat" but is not considered as coal, first converts to "lignite", then to "sub-bituminous coal", then to "hard coal", "anthracite" and finally to "graphite" if the conditions are appropriate. This progressive maturation process is called "Coalification", and each level is called "rank".

The coals have undoubtedly contain clay, silt, sand and inorganic (mineral) material in different proportions. These inorganic substances in the coals directly affect the quality of the coal negatively. The quality of a coal may have different meanings depending on the area in which it is used. For example; The best quality coal in coke production, which can be swollen, porous and durable, non-oxidized coal is the best coal. When the coal is subjected to liquefaction process, the most sought-after feature of the volatile substance is much more likely. It comes. In all, however, the inorganic substance is not a desired component.

CLASSIFICATION OF COALS

Coals are subject to many different classifications. Europeans are classified as "hard coal (quality coal on lignite)", "brown coal". The most widely used classification is undoubtedly the A.S.T.M (1983) and volatile matter, calorific value in the table below. In order to define an inorganic substance well, sometimes these classifications are not sufficient and organic petrographic investigations are taken into consideration. However, the degree of carbonization of the coals can be determined with the most accurate reflection values. In addition to these values, it is also important to know some trace element contents (such as Arsenic, Cadmium) which are pollutant for the environment.

PHYSICAL AND CHEMICAL PROPERTIES

Coals are brittle, brittle, combustible sedimentary rocks which contain inorganic substances with different properties besides organic materials. Chemical properties of the coals rather than the physical properties of the people are widely used.

• Their porosity varies between 3% (anthracite) and 25% depending on their degree of carbonization.
• Their hardness (Vickers) ranges from 30 (lignite) to 120 (anthracite) kg / mm2.

PHYSICAL CHARACTERISTICS

Roughly the physical properties of coals; Their density varies between 1.1 and 2.2 g / cm3, although they increase by looking at the inorganic material and moisture content they contain.

REFLECTION PROPERTIES OF COALS

Rmax, Rmean, Rrandom and Rmin reflection values are measured in coals. The reflection values give us the actual degree of carbonization of a basin coals, directly presenting the diagenetic properties (thermal values to which they have been exposed) in the past.

The Rmax values of the coals directly give the highest thermal values of the environment from the past to the present. The information gathered here helps us to explain what kind of pressures the media has undergone and what features it has.

Vitrinite reflection values are used in oil and gas exploration. In oil explorations, any trees found in sedimentary rocks on oil-containing formations, etc. The measurements we make on this part of the environment give us a great deal of help in determining what kind of hydrocarbon (heavy liquid, liquid, gas, or anything) can or cannot be found in this environment.

The reflection values can vary depending on the depth of the coal in the natural state. Since deeper coals are affected by more "geothermal gradient", it is natural that they show higher carbonization values ("Hilt's Law"). Other factors that increase the reflection value of coals, mountain formations that increase the temperature of the environment, volcanic activities, living fault movements, radioactive minerals, etc. d.

FLOURANCE CHARACTERISTICS

Coals are organic materials and some organic materials have fluorescence properties because they show fluorescence properties. Fluorescence properties of coals are exactly opposite values with reflection properties. In peat and coals with low reflection values, fluorescence properties are on the contrary high values. As the degree of carbonization increases, the fluorescence properties of liptinite and vitrinite decrease in parallel and disappear at high carbonization levels.

Liptinites, as previously mentioned, are the highest fluorescence macerals since they are the latest macers involved in the carbonization event. Except for some semifusinites, inertinite group macerals generally have no fluorescence properties. The fluorescent light itself is also dropped onto the polished sample and the sample is examined and measured. Substances with higher fluorescence values appear in lighter colors (light green, etc.), and substances with lower fluorescence values appear in darker colors (such as red, dark brown). The detailed properties of liptinites and their ability to easily distinguish them from inorganic substances (bristles, etc.) can be much easier with this method. Coals have many similar physical properties that they exhibit.

CHEMICAL PROPERTIES

Calorie (thermal), which shows the quality and properties of coals, are short and elemental analyzes. In addition, trace element analysis in coals can be done.

SHORT ANALYSIS OF COALS

Humidity, Volatile Matter, Ash and Fixed ("FIXED") carbon analyzes. These analyzes can reveal the characteristics of a coal together with petrographic analyzes.

ELEMENT ANALYSIS OF COALS

Determination of "C", "S", "O", "N", "H" elements in coals. It can be made for very specific and detailed researches.

Coal analyzes can be carried out in the Mining Analysis and Technology Department of the General Directorate of Mineral Research and Exploration (TTA), iron and steel factories, some coal enterprises (TTK and some TKI regional directorates), some private universities such as Hacettepe and METU.

COAL COMPONENTS

When we take a piece of coal, we see that they have different surfaces and appearances. Some coals crumble in the form of cubic divisions. Plant parts (fiterals) appear in peats, while thick, thin, glossy and matt banding occurs in some coals.

There is a stratification plane in the upper part of a piece of coal, and they are always horizontal, ie, parallel to the ground surface, if they are not folded, broken or displaced.

In the coals, there are planes called "Cleats" on the sides, perpendicular to each other and perpendicular to the stratification planes. Of these, the front or face clip is smooth, while the side butt clip is more rough. The side clits are parallel to the fold axes of the rocks of the environment. Clits are formed by being influenced by the factors that make up the mountain. Clit angles are 90 ° mercury at the level of hard coal and at lower carbonization levels (lower bituminous coal and lignite) this angle is smaller or different. The number of clites in anthracite is more than two (three) and they combine to provide conchoidal cleavage.

Especially at the level of hard coal, coals show banded appearance. When the coals are examined by hand, their banded, matte, hand-wetting components are their so-called & quot; lithotype & quot; units. Lithotypes end up with "ain". Four different lithotypes are available. These are Vitren ("Showcase"), Claren ("Clarain"), Duren ("Durain") and Fuzen ("Fusain"). The characteristics of the lithotypes are shown in Table 4 in detail. In Table 4, the clay and coal coals in relation to each other related features are also available.