Changes that occur when coal comes into contact with water
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Why does coal become soft and sticky when it comes into contact with water? Is it because certain inorganic substances in the coal dissolve in water, thereby changing the physical properties of the coal? If that’s the case, once the coal dries out, spontaneous combustion resumes, right?
The composition of coal consists mainly of organic and inorganic components; the organic components are primarily formed by condensed aromatic ring structures and hydrocarbon chains, which belong to hydrophobic groups. Therefore, the organic components mentioned do not dissolve in water. Coal lumps contain many well-developed pores, including internal and external pores; this pore structure absorbs moisture, thereby changing the density and viscosity of the coal. The moisture content of coal is also one of the important indicators in industrial analysis; the other three are ash, volatile matter, and fixed carbon.
Mud doesn’t dissolve in water, so why can water be used to wash away mud?
It depends on what type of coal it is; the earlier-formed coal, such as coal, is likely to soften when exposed to water as well