Sulfate crust is a zone observed in the axial (central) parts of
burning
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combust ...
coal
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal i ...
dumps and related sites. It is a zone built mainly by anhydrous
sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
minerals, such as
godovikovite and
millosevichite. The outer zone can easily be hydrated giving rise to minerals like
tschermigite and
alunogen. The zone forms due to interaction with hot (even around 600 °C) coal-derived gases (mainly
and
) with the "sterile" material (i.e. shales and other rocks serving as the source of , , and other cations) in case of the lack of vents for the gases to escape into the atmosphere.
[Sokol E. V., Maksimova N. V., Nigmatulina E. N., Sharygin V. V. and Kalugin V. M. 2005: Combustion metamorphism. Publishing House of the SB RAS, Novosibirsk]
See also
*
Coal seam fire
*
Coal underground fires
References
Coal mining
Combustion
Sulfate minerals
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