How is coal made and how is coal formed?

Coal is the remains of plants for thousands of years in ancient times, the main thing is trees, piled up on the ground to form a very thick black humus, due to the continuous changes of the earth's crust, buried in the ground, after a long period of geological action, isolated from the air for a long time, and under high temperature and high pressure, and then through a series of physical and chemical changes and other factors, the formation of black combustible sedimentary rock, so that the formation of coal.

In the history of the earth, the most favorable geological ages for the formation of coal are mainly the Carboniferous and Permian of the Late Paleozoic; Jurassic of the Mesozoic Era; and the Tertiary of the Cenozoic.

When we look at the cross-section of coal under the microscope, we can clearly see the growth ring lines of trees, which is a strong proof that coal evolved from trees.

Layers of coal are the continuous accumulation of layers of trees and plants, and after continuous geological changes, they have entered the underground in different years, and then under the continuous physical and chemical action, they have become today's layers of underground coal!

In the Paleozoic Era, 40 million to 50 million years ago, there were large forests growing on the earth, and with the movement of the earth's crust, a large number of trees were buried in the ground, which were isolated from the air for a long time, and under high temperature and high pressure, after a series of complex physical and chemical changes to form black combustible fossils, which is the formation process of coal.

Coal is a non-renewable resource. Coal is a solid combustible mineral that was gradually formed by ancient plants buried in the ground and undergoing complex biochemical and physicochemical changes, a solid combustible organic rock, which is mainly formed by biochemical action of plant remains, and then transformed by geological action after burial. Commonly known as coal.

The formation process of coal is as follows: under normal temperature and pressure on the surface, the plant remains accumulated in stagnant water bodies are transformed into peat or saprolite through peat or saprolite; After peat or saprolite, it sinks to the depths of the underground due to the decline of the basin basement, and is transformed into lignite by diagenesis. When the temperature and pressure gradually increase, it is transformed into bituminous coal to anthracite through metamorphism.

Peat is the process by which the remains of higher plants accumulate in swamps and are transformed into peat through biochemical changes. Sludge is the process by which the remains of lower organisms are transformed into sludge through biochemical changes in swamps. Saprolite is a silt-like substance rich in water and asphaltene.

Glacial processes may contribute to the collection and preservation of coal-forming plant remains.

China was the first country in the world to use coal.

In the Xinle ancient cultural sites in Liaoning Province, coal handicrafts were found, and Gongyi City, Henan Province also found the ruins of using briquettes to make iron in the Western Han Dynasty. In the "Classic of Mountains and Seas", coal is called Shini, and in the Wei and Jin dynasties, coal is called graphite or coal. Li Shizhen's "Compendium of Materia Medica" in the Ming Dynasty used the name coal for the first time.

Greece and ancient Rome were also early countries to use coal, and the Greek scholar Theophrastus wrote the "History of Stones" in about 300 BC, which recorded the nature and origin of coal; Ancient Rome began heating with coal about 2,000 years ago.

Coal is widely used as a fuel for industrial production and began with the Industrial Revolution at the end of the 18th century. With the invention and use of the steam engine, coal was widely used as a fuel for industrial production, bringing unprecedented huge productivity to the society, promoting the development of industry, and then developing coal, steel, chemical, mining, metallurgical and other industries.

Coal is for modern industry, whether it is heavy industry or light industry; Whether it is the energy industry, metallurgical industry, chemical industry, machinery industry, or light textile industry, food industry, transportation industry, all play an important role, all kinds of industrial sectors have to consume a certain amount of coal to a certain extent, so some people call coal the "real food" of industry. Coal.

In the Paleozoic Era, 40 million to 50 million years ago, there were large forests growing on the earth, and with the movement of the earth's crust, a large number of trees were buried in the ground, which were isolated from the air for a long time, and under high temperature and high pressure, after a series of complex physical and chemical changes to form black combustible fossils, which is the formation process of coal.

A large number of plant debris is transformed into coal after complex biochemical, geochemical, and physicochemical processes, and a series of evolutionary processes have passed from plant death, accumulation, burial to coal, which is called coal-forming process.

Coal is a product of the earth's crustal movement, as far back as the Paleozoic Era more than 300 million years ago, the Mesozoic Era more than 100 million years ago, and the Cenozoic Era tens of millions of years ago. It is generally believed that the coal-forming process is divided into two stages: the peat stage and the coalification stage. The former is mainly a biochemical process, and the latter is a physicochemical process.

The peat stage is the continuous reproduction of plants in peat bogs, lakes or shallow seas, and their remains are decomposed, combined and accumulated with the participation of microorganisms, and biogeochemistry plays a leading role in this stage. The lower plants form saprolite through biogeochemical processes, and the higher plants form peat, so the first stage of coal formation can be called the saprolite stage or the peat stage.

The role of coal

Coal is the most abundant and widely distributed fossil fuel on the planet. It is widely used, and more than one-third of China's coal is used for power generation, and the average coal consumption for power generation is about 370 grams per kilowatt hour of standard coal. Power plants use the calorific value of coal to convert thermal energy into electricity.

There are many types of industrial boilers for general enterprises and heating, which are large and scattered, and the coal consumption accounts for about 26% of thermal coal. The amount of domestic coal is also larger, accounting for about 23% of the fuel coal.

Coal is also an important raw material for the metallurgical and chemical industries, mainly used for combustion, coking, gasification, low-temperature dry distillation, hydroliquefaction, etc. However, during the combustion process of coal, carbon monoxide, carbon dioxide, sulfur dioxide, soot, etc., will cause air pollution and cause certain harm to the human body.

Coal was slowly formed hundreds of millions of years ago by burying a large number of plants in the ground.

The coalification stage consists of two continuous processes: under the action of geothermal heat and pressure, the peat layer undergoes various changes such as compaction, water loss, limb aging, and induration, and becomes lignite. The density of lignite is greater than that of peat, and there is also a significant change in composition, with a relative increase in carbon content, a decrease in humic acid content, and a decrease in oxygen content.

Because coal is an organic rock, this process is also called diagenesis. In this process, the properties of the coal change, so this process is also called metamorphism.

As the earth's crust continues to sink, so does the overburden of lignite. Under the action of geothermal and static pressure, lignite continues to undergo physical and chemical changes and is compacted and loses water. Its internal composition, structure and nature have undergone further changes.

This process is the metamorphism of lignite into bituminous coal. Bituminous coal has a higher carbon content than lignite, the oxygen content is reduced, and humic acid no longer exists in bituminous coal. Bituminous coal continues to undergo metamorphism.

Change from low to high degree of metamorphism.

Coal Formation:

Coal formation refers to the process from the accumulation of dead plants to the formation of coal. Studies of modern peat bogs have shown that due to the abundance of oxygen on the peat surface, plant remains are oxidized and decomposed into simple organic compounds under the slow action of aerobic bacteria, a process known as humification. On the surface of peat bogs, silk charring often occurs due to forest fires, peat exposure and other reasons, forming silk charcoal and corresponding microscopic components in coal.

Coal formation can be divided into three stages: the first stage is the bacteriolysis stage, that is, after the plant dies, it is covered by sediment and gradually isolated from oxygen, with the participation of gas-phobic bacteria, the plant body decays, the hydrogen and oxygen components gradually decrease, and the carbon content increases relatively, generating peat; The second stage is the coalification stage, which is the peat through diagenesis, which further increases the carbon content and becomes lignite; The third stage is the metamorphic stage, which is the process of lignite being affected by high temperature and high pressure and turning into bituminous coal and anthracite.