Coal is a product of the earth’s crust.
As far back as 300 million years ago in the Paleozoic and more than 100 million years ago in the Mesozoic and Cenozoic period of tens of millions of years ago, a large number of plant debris after a complex biological chemistry, geochemistry and physical chemistry into coal, after death, accumulation, burial to shift from plants into coal through a series of evolution process, this process is known as coal.
Xiaobian today to introduce you.
It is generally believed that the coal formation process can be divided into two stages: peatification stage and coalification stage.
The former is mainly a biochemical process, while the latter is a physicochemical process.
Peatification Stage The first stage of peatification is the continuous reproduction of plants in peat bogs, lakes or shallow seas, and their remains are continuously decomposed, combined and accumulated with the participation of microorganisms. Biogeochemistry plays a leading role in this stage.
Lower plants form sapropelation through biogeochemistry, while higher plants form peat, so the first stage of coal formation can be called sapropelation stage or peatization stage.
Coalification stage The coalification stage consists of two continuous processes: the first process, under the action of geothermal heat and pressure, the peat layer occurs compaction, water loss, limb aging, induration and other changes to become lignite.
Lignite, which is denser than peat, also has 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.