Hard coal


Surname: Hard coal
other names: "Black Gold", Bituminous coal (engl.)
mineral class: Elements
chemical formula: C
Chemical elements: Carbon
Similar minerals: Charcoal
colour: black
shine: Matt
crystal structure: /
mass density: approx. 1.4
magnetism: not magnetic
Mohs hardness: approx. 2
stroke color: black
transparency: opaque
use: Fuel

General to the hard coal:

hard coal describes a sedimentary rock that emerged from the remains of dead plants that developed over three hundred million years ago. It consists predominantly of carbon, which accounts for more than seventy percent of its total volume and at least half its weight. As an important raw material that plays a key role in the production of heat and electricity, this fossil energy source is also referred to as "black gold" or "black diamonds".

Occurrence and localities:

Coal was created millions of years ago when the earth was covered with impenetrable jungles with trees several hundred meters high and covered by huge swamps and bogs. The giant trees and dense ferns died in the course of millions of years and were replaced by new ones. From the vegetable remnants formed thick layers of fertile humus. Dead plants that perished in the vast swamps could not be decomposed by the bacteria that live on the surface of the earth and need oxygen to live on and were not transformed into soil but into peat. This marked the first phase of so-called coalification, the process in which plant material is used to develop fossil fuel. The peat layers that accumulated over time were repeatedly flooded by oceans during the course of Earth's history and covered with sand, rocks and boulders, which exerted a strong pressure and finally squeezed out the water. In combination with high temperatures, this triggered the next step of coalification, namely the conversion of peat into lignite. The brown coal sank into ever deeper layers of earth and was eventually trapped in airtight spaces. There, various gases such as methane, nitrogen oxides and carbon monoxide and dioxide accumulated in the lignite, which led to their conversion into hard coal under high temperatures.

History and usage:

Hard coal has been specifically promoted in Europe since the Middle Ages and used for heat production in living spaces. Since it is deposited in deep layers of the earth's crust, it can only be mined by the so-called underground mining. Today, hard coal is mined and exported extensively, especially in China, the United States, India, Indonesia, Australia, Russia and South Africa. Although there are hard coal deposits in many countries, it is not worth the promotion because of the high costs. The people who do this work at temperatures of about 30 ° C in the dark and are exposed to high levels of dust. The gases trapped in the coal, which are referred to as mine gases, also cause explosions and fires, which again and again led to serious accidents, especially in the past. Today, coal is mined using modern machinery and jackhammers and transported up on conveyor belts. As it has a significantly higher calorific value compared to lignite, it is still produced in large quantities despite the high financial costs and, after heating to about 1200 ° C, is processed into coke, which plays an important role in the production of iron. Coal is also used in the manufacture of gasoline, plastics, rubber, soaps, paints and varnishes, and pharmaceuticals.